5101 -149

Department of Energy

Low-Cost Solar Array Project

15th Project Integration Meeting

Handout

Pasadena Center April 2 and 3, 1980

Jet Propulsion Laboratory California Institute of Technology

Pasadena, California

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for the Departme nt of lncrg, through 311 apeement wi th the National Aeronautic, and Space A<lmin1Slra110 11 .

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(DOE) and for111s part of the Solar Pho10 1'ol1a ic Conversion Progra m to initia te a 111ajor effort toward the tkvdop111cn1 of low-cost sol.tr array,.

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5101-149

Department of Energy

Low-Cost Solar Array Project

15th Project Integration Meeting

Handout

Pasadena Center April 2 and 3, 1980

Jet Propulsion Laboratory California Institute of Technology

Pasadena, California

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I TECHNOLOGY

DEVELOPMENT AREA

vt.M. KOLIWAD, MGR M. LE IPOLD, DEP. MGR.

-

-

--

SILICON MATERIAL TASK

R. LUTWACK, MGR

LARGE AREA Si SHEET TASK

J. K. LI U, MGR

ENCAPSULATION TASK

C. COULB~RT, MGR

ADVANCED PHOTOVO LTAICS

TASK R,J . STIRN, MGR

LOW-COST SOLAR ARRAY PROJECT

STAFF

E. CHRISTENSEN C. T. HANSEN

I PRODUCTIO N

PROCESS AND EQUIP. AREA

.,.6 .s. BICKLER, MGR

.,_ PROCESS AUTOMATION

'-- NEWLY DEVELOPED PROCESSES

.... TECHNOLOGY TRANSFER

- ASSESSMENT Or EMERGING TECHNOLOGY

....._ NEAR- TER,'v\ co:;T REDUCTION

PROJECT MANAGER J;<it . T. CALLAGHAN

DEPUTY MANAG ER R. R. McDONALD

SECY:M.J. PHILLIPS

ANALYSIS AND INTEGRATION

AREA

W.K. HENRY, MGR

- PROJECT INTEGRATION

.._ AR RAY TECHNOLOGY C03TS

._ ECONOMICS/ IN DUSTR IALIZATION

.._ ARRAY LI FE CYCLE ANALYSIS

FINANCIAL B. S. LENC K, MGR

PROCUREMEN T P. S, RYKEN

QUALITY ASSURANCE K. J. ANHALT

l ENGINEERING

AREA

Vfl.G. ROSS , MGR

- ARRAY ENGINEERING

- ADVANCED ARRAY REQUIREMENTS

- ARRAY DEVELOPMENT

- ENV IR01-.JMENTAL TE STING R&D

- ENV IRONMENTAL ASSESSME NT

' O PERATIONS AREA

VL. N. DUMAS, MGR

--LARGE SCALE PRODUCTION

TASK L.D. RUNKLE

....._ FAILURE ANALYS IS AN;) REPORTING

.__ ENVIR/FIELD TESTS

....._ PERFORMANCE MEASUREMENTS

.__ MODULE INTERFACE AND CONTROL

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CONTENTS

MEETING OBJECTIVES------------------------------------------------ 1

MAP: Meeting Locations------------------------------------------- 2

AGENDAS----------------------------------------------------------- 3

STATUS OF TECHNOLOGY TRANSFER------------------------------------- 9

TECHNICAL SUMMARIES

Silicon Material-------------------------------------------- 13

Large-Area Silicon Sheet------------------------------------ 23 I.

·Encapsulation----------------------------------------------- 39

t Production Process and Equipment---------------------------- 51

, Engineering------------------------------------------------- 73

·Operations-------------------------------------------------- 81

Large-Scale Production-------------------------------------- 82

LSA PROJECT ACTIVE CONTRACTS-------------------------------------- 91

LSA PROJECT PUBLISHED DOCUMENTS----------------------------------- 97

MAPS: Pasadena Area; Pasadena Center--------------------------- Inside Back

Cover

For Your Information

Check-in: Please check in at the registration desk on the lower level of the conference building before the start of the meeting on Wednesday morning.

Telephone Messages: Incoming calls will be received at JPL on (213) 577-9520. Constant coverage of this phone will be provided and messages transmitted .

Badges: We will appreciate your returning your badges at the end of the meeting.

iii

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MEETING OBJECTIVES

The LSA Project is convening its fifteenth Project Integration Meeting (PIM). We will be meeting on April 2 and 3, 1980 at the Pasadena Center, Pasadena, California, with registration beginning at 7:30 a.m. on April 2 in the lower level of the Conference Building. Attendance is by invitation only.

The LSA Project Integration Meetings are conducted to enable the exchange of data and information required to assess recent progress; to identify, implement, and evaluate integration activities; to gain perspective of trends and new developments; and to guide the Project's near- and long-term planning and adjustment of priorities. Consequently, final conclusions are not necessarily reached during one PIM. Often, subjects brought up for discussion during one meeting will be con-tinued in subsequent PIM sessions.

The objectives of the fifteenth PIM are to assess the general technology development status of the Project; to review the status of Czochralski ingot growth and ingot wafering; to review the production processes and equipment Phase II activities and to exchange and discuss technical information at the working level.

This will be our first meeting held away from the Caltech Campus for several years. The Convention Center will house the PIM in one building with the meeting rooms and display areas co-located. We sincerely hope this will facilitate your needs in going from one meeting to another. A map showing room numbers is located adjacent to the agenda for ease in locating assigned rooms for the different sessions. Your conunents on these facilities will be welcome.

1

MEETING LOCATIONS

C 314 C304 C 306

C305 0307

C312 I ~II f"_•Hi:;.

~

CONFERENCE BUILDING PLAZA LEVEL

;; iii ii El

C 101 C 102 C 103 C 104 C 105

cl H H lb

1=n D EXHIBIT AREA D D[ EXrT ~~~ B ti

C 124 C 112

LITTLE TtEATRE

L:rJ --1.: FREIGHT DOOR

I LOM>ING

DOCK

CONFERENCE BUILDING LOWER LEVEL

2

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AGENDA c., . .,,.,.,~..,,~o,J

Wednesday - April 2, 1980

7: 30 Registration

8 : 30 Welcome/LSA Annoucements

ll : 40 DOE/NASA/LC Announcements

9 :00

10 :00

JO : ?.O

10 : 50

11 : 50

12 :00

12 : 20

Cz Ingo t/Wa fe ring Summa r y

SAMICS Results Ove r view

Coffee Break

PP&E Phase II Overview

Module/Array Circui t Design Overview

SERI P/V R&D Overvi ew

Lunch

1 : 30 Technology Sess ions (Simultaneous)

Silicon Mate r ial

PP&E Review of Phase II -Process and Sequence Develonment

3 :00- 4 : 30 Coffee Available

3 : 45 Continuation of above 2 sessions

Encapsula t ion

Social Hour (Starts at 5 : 30)

Tiursday - April 3, 1980

8 : 00 Technology Sessions (Simultaneous)

Silicon Material

Sil icon Sheet

Encapsulation

PP&E

PA&I

Engi neering/Operations (following PA&l session)

9:30- 11:00 Coffee avai l able

12 :15 Lunch

1: 30 Parallel Sessions

Effects of wafer dimens ions

Module applications

2 :00-3 : 15 Coffee available

3:15 Summaries

iA'.'sA Lead Center DOE

4:45 End of meeting .

l

3

Lower Level

~=I ~ mu/ _,,..,-- IN'OJ·;]'IZ{,'

of Conference Building .~

/i, . Cal laghan ~ 10 min .

~ / /. -1iaycock"!Mag id/~ / ~ 20 mi n .

101-102- 103

301- 302

101-102-103

.-1. Liu

~- llenry

/o. Bickler

4 . Ross

A . Wagner

R. Lutwack

D. Bickler

(Same as above) /

310 .{,_ Cou lhert

Lowe r Level of Conference Hui l dine

301- 302

324-326

310

312

316

324- 326

316

101-102-103

R. l..utwack

J . Liu

v( Coulbe rt

D. Bickler

P . Henry

i,!(" Ross/ L.

M. Le ipold

;If. Oumas

Dumas

60 min .

20 mi n .

30 min .

60 min .

10 min .

20 min .

70 min .

2 h rs .

2 hrs .

2 h rs .

2 hrs .

/, hrs .

4 hrs .

/1 hrs .

4 hrs .

2 hrs .

2 hrs .

1-1/4 hrs .

1-1/4 hrs .

1-1/4 hrs .

SILICON MATERIAL

WEDNESDAY p.m. - Room 301/302

R. Lutwack, Chairman

1:30 Gaseous Melt Replenishment System

2:00

2:45

Silane/Silicon Process

Hydrogenation of Silicon Tetrachloride

3:30 Coffee

4:00

4:30

Effects of Impurities on Solar Cell Performance

Definition of Purity Requirements

THURSDAY a.m. - Room 301/302

R. Lutwack, Chairman

8:15

8:45

9:30

10:00

10:30

11:00

Zinc Reduction of Silicon Tetrachloride

Chemical Vapor Deposition Process

Coffee

Investigation of Silicon Halide/ Alkali Metal Flames

Process Analysis

In-House Silicon Program

4

Energy Materials Corp.

Union Carbide Corp.

Massachusetts Institute of Technology

Solarex Corp.

Westinghouse R&D Center

Battelle Columbus Labs.

Hemlock Semiconductor Corp.

AeroChem Research Labs.

Lamar University

JPL

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LARGE AREA SHEET TASK

THURSDAY a.m. - Room 324/326

J . Liu, Chairman

8:00 HEM

8:25 soc

8:55 EFG

9:25 Coffee

9:45 Web

10:15 Vacuum Die Casting

10:40 Oxygen Partial Pressure

11:05 Cell Fabrication

11:30 Cell Fabrication

Crystal Systems, Inc .

Honeywell

Mobil Tyco

Westinghouse

Arco Solar

University of Missouri

ASEC

Spectrolab

NOTE: Time allocated includes 5 minutes for discussion after each presentation .

5

ENCAPSULATION

WEDNESDAY - 3:45-5:45 p.m. - Room 310

Materials and Process Developmen t

C. D. Coulbert, Chairman

v3 :45

~ :00

i-1; : 20

4:50

Overview

El ec tros t atic Bonding

Low Cost Materia l s

Ion Plating

THURSDAY a . m. - Room 310

Module Performance and Life Prediction

C. D. Coulbert, Chair man

9:35

10:15

10:45

11: 25

11:40

Analys is

Coffee

Photodegradation and its Prevention

Degradation Diagnostics

Hydromechanical ·Failure

Coulbert

SPIRE Corp. f?ae:x. '/ou ;vt..c:;e ,P. 4-S-

Springborn ?#

ITW

Spectrolab 4l.ezC ~c.1n Neu~ C"/./uc.<. #,,,.N,,./C

JPL (Maxwell) r.41 ??:

Scien ce Center~4r/£,K4~~,e

Univ . of Toronto

JPL (Gupta)

Co l orado State (Du Bow)

JPL (Hong)

NOTE: Time allocated inc ludes discuss ion and answering ques tions .

6

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PRODUCTION PROCESS AND EQUIPMENT

WEDNESDAY p.m. - Room 101/102/103

D. Bickler, Chairman

1:30

1:50

2:10

2:30

3:30

4:30

Auto Assembly

Phase III Sequences

5:30 Close

THURSDAY a.m./p.m. - Room 312

D. Bickler, Chairman

8:00

8:10

8:30

8:50

9:00

9:10

9:30

9:50

10:10

10:50

11:00

11:20

11:40

12:00

1:30

2:45

P/N Cells

Cu Plating

Thick Film

Laser

Wax

Phase II

Phase II

Polycrystal

Coffee

Mega sonic

Ni Plating

Midfilm

Pulsed Beam

Lunch

7

{

ARCO Solar, Inc.

Kulicke & Soffa Ind., Inc.

MBAssociates

{

RCA Corporation

Westinghouse

Spectrolab, Inc.

Applied Solar Energy Corp .

Applied Solar Energy Corp.

Bernd Ross Associates

Lockheed Missiles & Space

Motorola, Inc.

Motorola, Inc.

Photowatt International, Inc.

Photowatt International, Inc.

RCA Corporation

Solarex

Spectrolab, Inc.

SPIRE Corporation

Motorola

University of Pennsylvania

OPERATIONS/ENGINEERING

THURSDAY a .m. - Room 316

vR . Ross/£ . Dumas , Chairmen

111) : 15

l{o: 35

~ 0 : 50

~ 1:05

\/11 : 25

ilf1: 35

S OIL t.,../C,

PV Module/Array ~tan dard s Activities

Reliability Engineering Data Analysis

Low- Cost Array Structures Status

Performance Measurements & Standards at JPL

Block IV Contract Status

Environmental Tes t Update

THURSDAY p .m. - Room 316

IC. Dumas , Chairman

~ 30

~ 50

vf. : 10

MIT/LL Test and Applicat i ons Overvi ew

PV for Village Power

Sol ar- Powered Transportation

8

C' . /I,( flfl G,

·A JJ, 1 E f rnan (JPL)

,: l'./l~J.MJ t.f(.A,IJ p./ Q h d ii D (IITRI)

A. Wilson (JPL)

R. G. Downing (JPL)

L. D. Runkle (JPL)

J . Griffith (JPL)

S . For man (MIT/LL)

L. Partain (LLL)

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STATUS OF TECHNOLOGY TRANSFER

The Production Processes and Equipment Area is concerned with the transfer of technologies developed by the LSA Project for manufacturers of solar modules. The status of this transfer activity is reported periodically to provide an overview of processes available from JPL, and to promote experimentation, modification, and application. Inquiries and requests for process specifications should be directed to the LSA Project PP&E Area at (213) 577-9225.

SURFACE PREPARATION

PROCESS CONTRACTOR STATUS SURVEYED BY CONFIRMED

TEXTURE ETCH SENSOR TECH EVALUATED LOCKHEED CO.NFIRMED RECOMMEND MOD.

UNIV OF PA ECONOMIC ONLY PROXIMITY TEXAS INST. UNDER DEV. TEXTURING

TEXTURE ETCH LOCKHEED UNDER EVAL. GENERAL ELECTRIC UNIV. a= PA. ECONOMIC ONLY

SPRAY A-R SENSOR TECH UNDER DEV.

SPRAY A-R LOCKHEED UNDER EVAL. SPECTROLAB

SPRAY A-R RCA EVALUATED PHOTOWATT CONFIRMED UNDER EVAL. SPECTROLAB

WESTINGHOUSE UNIV. OF PA. ECONOMIC ONLY

WAX-MASK ING MOTOROLA UNDER EVAL. WESTINGHOUSE UNIV. OF PA. ECONOMIC ONLY

CVD Si3N4 MOTOROLA AVAILABLE

PLASMA DAMAGE MOTOROLA EVALUATED WESTINGHOUSE CONFIRMED ETCH UNIV. Of PA. ECONOMIC ONLY

UNDER EVAL. SPECTROLAB ASEC

DIP A-R WESTINGHOUSE EVALUATED ASEC CONFIRMED BY SPIN ON

UNDER EVAl. GENERAL ELECTRIC

PLASMA METAL MOTOROLA UNDER EVAL. ASEC PATTERN DEFINITION

WAFER SURFACE PREP .

PLASMA CVD

DAMAGE REMOVER ETCHING

TEXTURE ETCHING

SURFACE PREP.

Si3N4 A/R COATING

SENSOR TECH UNDER EVAL. UNIV. OF PA. ECONOMIC ONLY

SENSOR TECH AVAILABLE

MB ASSOC. AVAILABLE

MB ASSOC. AVAILABLE

SOL..AREX AVAILABLE ------------, 48 PROCESSES LISTED

SENSOR TECH AVAILABLE 26 BEING EVALUATED BY INDUSTRY 18 CONFIRMED BY INDUSTRY

9

STATUS OF TECHNOLOGY TRANSFER (Continued)

JUNCTION FORMATION

PROCESS

PRINT & FIRE BSF

ION IMPLANTATION FURNACE ANNEAL

LASER ANNEALING

CVD p+

CONTRACTOR STATUS

SPECTROLAB EVALUATED

UNDER EVAL.

SPIRE EVALUATED

UNDER EVAL .

LOCKHEED AVA ILABLE

WESTING - AVAILABLE HOUSE

SURVEYED BY CONFIRMED

ASEC CONFIRMED WESTINGHOUSE CONFIRMED RCA GENERAL ELECTRIC

MOTOROLA CONF IRMED RCA CONF IRMED GENERAL ELECTRIC UNIV . OF PA . ECONOMIC ONLY MOTOROLA CONF IRMRD

ION IMPLANT LOCKHEED UNDER EVAL . GENERAL ELECTRIC

LASER SCRIBING SENSOR TECH EVALUATED

PLASMA EDGE ETCH MBA AVAILABLE

SPRAY- ON POLYMERS

SENSOR TECH AVAILABLE

UN IV. OF PA . ECONOMIC ONLY

MOBIL TYCO CONFIRMED SPECTROLAB CONFIRMED UN IV . OF PA . ECONOMIC ONLY

SPIN-ON POLYMER DOPANTS

TEXAS INST. UNDER EVAL . UNIV . OF PA . ECONOMIC ONLY

POCL3 DIFFUSION

POCL3 DIFFUSION

RCA UNDER EVAL. GENERAL ELECTRIC

MB ASSOC . AVAI LABLE

POLYMER DIFFUSED SPECTROLAB AVAILABLE WAFER

SPRAY -ON DOPANTS SENSOR TECH AVAI LABLE

ION IMPLANRATION MOTOROLA UNDER EVAL . ASEC UNDER EVAL. UN IV. OF PA . ECONOMIC ONLY

POST DIFFUSION SOLAREX AVAILABLE CLEANING

10

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STATUS OF TECHNOLOGY TRANSFER (Continued)

METALLIZATION

PROCESS CONTRACTOR STATUS SURVEYED BY COMMENTS

ELECTROLESS Pd/Ni MOTOROLA EVALUATED EVALUATED EVALUATED EVALUATED EVALUATED EVALUATED EVALUATED UNDER EVAL. UNDER EVAL.

WESTINGHOUSE CONFIRMED(MOD)

THICK FILM

THICK FILM

WRAP AROUND

ALUMINUM BACK CONTACTS

PLATE COPPER

ELECTROLESS Ni

SILVER PRINTING PASTE

ELECTROLESS Ni

PRINT & FIRE FRONT CONTACT

REMOVE OXIDE & CLEAN ALUM BACK

ALUMINUM BSF

FRONT CONTACT FORMATION

NEGATIVE SILK SCREENING

WAVE SOLDERING

'

Mo/Sn METALLIZATION

RCA

LOCKHEED

ASEC CONFIRMED PHOTUWATT SOLAREX SOLAR POWER SOLOMAT UNIV. OF PA. ECONOMIC ONLY ARCO SOLAR UNIV. OF DELAWARE

UNDER EVAL. UNIV. OF PA. ECONOMIC ONLY UNDER EVAL. GENERAL ELECTRIC UNDER EVAL. SPECTROLAB

UNDER EVAL. GENERAL ELECTRIC UNIV. OF PA. ECONOMIC ONLY

SPECTROLAB SUSPENDED NOT COST EFFeCTI VE AT THIS TIME

ARCO SOLAR EVALUATED WESTINGHOUSE CONFIRMED

OCLI

SOLAREX

UNIV. OF PA. ECONOMIC ONLY UNDER EVAL. GENERAL ELECTRIC

UNDER DEV.

UNDER EVAL SOLAR POWER MOTOROLA UNIV. OF PA. ECONOMIC ONLY UNIV. OF DELAWARE

SPECTROLAB UNDER EVAL. UNIV. OF PA. ECONOMIC ONLY

SENSOR TECH UNDER EVAL. UNIV. OF PA. ECONOMIC ONLY UNIV. OF DEL.

SPECTROLAB UNDER EVAL. UNIV. OF PA. ECONOMIC ONLY GENERAL ELECTRIC

SPECTROLAB UNDER EVAL. UNIV. OF PA. ECONOMIC ONLY

MB ASSOC. AVAILABLE

MB ASSOC. AVAILABLE

SOLAREX AVAILABLE

SOLAREX AVAILABLE

SYSTEM SOL/LOS AVAILABLE

11

STATUS OF TECHNOLOGY TRANSFER (Continued)

MODULE ASSEMBLY

PROCESS CONTRACTOR STATUS SURVEYED BY CONFIRMED

DOUBLE GLASS RCA AVAILABLE

MASS SOLDERING RCA AVAILABLE

GAP WELD RCA SUSPENDED NOT COST EFFECTIVE AT THIS TIME

APPLYING SPECTROLAB AVAILABLE INTERCONNECTS

INTERCONNECT & SOLAREX AVAILABLE ENCAPSULATION

MODULE LAYOUT MB ASSOC. AVAILABLE & INTERCONNECT

LAMINATION MB ASSOC. AVAILABLE

FRAMING MB ASSOC. AVAILABLE

LAMINATION SPRINGBORN AVAILABLE LABS

12

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TECHNICAL SUMMARIES

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SILICON MATERIAL TASK

AeroChem Research Laboratories, Inc.

Princeton, NJ

Contract Title: Development of Processes for the Production of Solar Grade

Silicon from Halides and Alkali Metals

Contract No.: 955 491

The objective of this program is to develop a process for producing solar grade silicon based on the reaction of silicon halides and alkali metals. Work has centered on the development and use of a laboratory scale apparatus which demonstrates the potential of employing flames of SiCl4 and sodium to produce solar grade silicon. The current apparatus is one which can produce silicon at a nominal rate of 0.5 kg b- 1

• The major components of the apparatus are (i) sodium and SiCl4 vaporizers, (ii) a reactor in which the reaction

4 Na(g) + SiCl4(g) ~ 4NaCl(g) + Si(l)

is carried out to> 95% completion, and (iii) a low pressure silicon collection region into which a jet of reaction products is impacted on surfaces and partially fused Si droplets are separated from the salt vapor and consolidated.

The apparatus is being operated currently in batch runs lasting 20 min (as limited by the present sodium reservoir volume). Typically, consol­idated metallic silicon samples representing about 50 to 80% of the total silicon produced are being collected; the remaining silicon is deposited, along with the salt, as a fine powder on cool walls- down­stream of the collection region. A major problem in collecting the silicon in consolidated metallic form has been to find appropriate con­struction materials for the Si collector. The low density graphites which are readily available are rapidly infiltrated by the molten sili­con. Quartz does not withstand exposure to the NaCl(g) byproduct. Alu­mina tolerates the collector environment but is etched and is thus a potentially serious source of contamination. A solution to the problem has been found by operating at or just below the Si melting point. In this situation infiltration of graphite is minimized and the Si consoli­dates into a dense polycrystalline material. In the near future a lar­ger sodium delivery system, now being assembled, will allow 1 to 2 h runs so that 250 g Si samples can be produced. Efforts are also being made to further improve the collector efficiency.

Approval Signature

13

7 March 1980

Date

SILICON MATERIAL TASK

BATTELLE'S COLUMBUS LABORATORIES Columbus, Ohio 43201

Contract Tit( e: EVALUATION OF SELECTED CHEMICAL PROCESSES FOR PRODUCTION OF LOW-COST SILICON

Contract No.: 954339

Battelle's Columbus Laboratories (BCL) is developing the zinc vapor reduction of silicon tetrachloride in a fluidized bed of seed particles as a promising process for producing low-cost high-purity free-flowing silicon granules.

Current activity relates to the Process Development Unit (PDU) which consists of four critical units from the 50,000 kg/year full-scale EPSDU design, i.e., the zinc vaporizer, fluidized-bed reactor, by-product condenser, and electro­lytic cell, with auxilliary equipment to permit operation in an 8-hour batch mode. At the time of the Fourteenth PIM in December, tqe PDU was ready for a "dry run". However, problems developed in the zinc vaporizer which have delayed feeding zinc to the fluidized bed. Subtle differences in design between the zinc vaporizer built for the PDU and that used earlier in the laboratory to obtain the 60 lb/hour zinc vapor feed rate have lead to inef­ficient r.f. induction coupling and undesirable plasma formation.

A piston-displacement-fed, graphite-tray-type vaporizer, scaled up from that used in the miniplant, has been built, tested, and attached to the PDU for interim use pending solution of the problems with the direct-coupled vaporizer.

At the writing of this summary, ~a kg of high-purity silicon seed was being satisfactorily fluidized with inert gas in the fluidized bed of the PDU and all units had been brought to operating condition in preparation for the first run.

Factors have been identified to account for the difference in the 300 ppmw and 3000 ppmw levels of residual zinc in the miniplant silicon granule pro­duct, which point the way to decreasing the residual zinc content to below 300 ppmw in the PDU product. At the same time, the removal of residual zinc by heat-treatment of the as-produced granules is being studied, should· the need for post-process treatment persist.

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SILICON MATERIAL TASK

Energy Materials Cor~oration

Harvard, Massachusetts

c·o n t r a c t T i t 1 e : GASEOUS MELT REPLENISHMENT SYSTEM

955269

---------Contract No. :

The objective of this program is to develop a system which incorporates both silicon formation and melt replenishment in the same equipment. The processes and equipment are scaled such that a modest investment can make available to the Czo­chralski crystal grower a low cost source of silicon.

The chemical reactions, H2 reduction of SiHC1 3 , are those in commercial use for poly formation. The major innovation is in reactor design which allows a high productivity of silicon. Calculations based on epitaxial deposition rates indicate that a reasonable sized system can produce material rapidly enough to keep pace with either 10 cm or 12 cm diameter Czochralski crystal growth operating in a semi-continuous mode.

Polycrystalline silicon will be deposited on the inside walls of a resistively heated, multi-walled fused silica reaction chamber by Hz reduction of SiHCl3. After sufficient silicon has been produced, the reactor is flushed with argon and the silicon melted out of the reactor into a Czochralski crystal growth crucible. The reactor is then returned to the deposi­tion stage. The reaction chamber and a heated delivery tube to the crystal growth system are separated by a "U" tube which acts as a valve by adjusting the temperature above or below the melting point of silicon contained in the U-bend .

The first phase of the program comprises development of a prototype system capable of a production rate of 0.5 kg/hr. During the last three months we have completed construction and have been testing the gas handling and reactor heating system. We have found it necessary to design and install a gas equilibration system to minimize the effect of gas pres­sure upon the reactor. Another development has required a temporary support for the internal heat exchanger to prevent thermal expansion from distorting or breaking the reactor feed tubes. The reactor tests will begin this month .

15 ~

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Silicon Materials Task

Hemlock Semiconductor Corporation

Hemlock, Michigan 48626

Contract Title: Development of a Polysilicon Process Based on Chemical Vapor Deposition

Contract No.: 955533

The objective of this program is to demonstrate the feasibility of a chlorosilane based chemical vapor deposition process for the production of a low cost-high purity polysilicon. Efforts are currently being expended in the following technical areas

Dichlorosilane Reactor Feasibility

Intermediate Sized Dichlorosilane Reactor Development

Dichlorosilane Process/Product Evaluation

Preliminary EPSDU Design/Integration

During this reporting period fifteen reactor runs were completed using dichlorosilane feed. Deposition rate was nearly double that achieved using trichlorosilane under comperable operating conditions while power consumption is nearly halved. Vent product composition is in close agreement to that projected prior to contract initiation in­dicating a significant reduction in vent product recovery system load for a dichlorosilane based plant. Maximum rod diameter grown to date is 42.3 mm and no unusual problems unique to the use of dichlorosilane feed have been encountered.

A laboratory scale rearranger system for preparation of dichloro­silane has been completed and is now operational along with associated analytical equipment designed to support both the laboratory scale and PDU development effort. Catalyst characteristics are under investi­gation and equilibrium product composition is being established using a mixed HSiCl -SiCl feed.

A mixed ~eed cftsicl3-siC14) design was selected for incorporation

into the PDU. The design provides a low cost redistribution-distil­lation system while suppressing the formation of monochlorosilane. Design of the unit is complete and the overall PDU design is now under­going a corporate safety audit prior to initiating equipment procure­ment.

Based on analysis of reactor vent product composition collected to date, a preliminary EPSDU material balance was completed and reported in the first quarterly report.

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Approval Signature Date

16

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SILICON MATERIAL TASK I

LAMAR UNIVERSITY Beaumont, Texas 77710

CONTRACT TITLE: PROCESS FEASIBILITY STUDY IN SUPPORT OF SILICON

MATERIAL TASK I

CCNrRACJ Mo. : 954343

Analyses of process system properties were continued for important chemical materials involved in the several processes under consideration for semiconductor and solar cell grade silicon production. Major acti­vities were devoted to physical, thermodynamic and transport property data for silicon. Property data are reported for vapor pressure, heat of vaporization, heat of sublimation, liquid heat capacity and solid heat capacity as a function of temperature to permit rapid usage in engineering.

Chemical engineering analyses of the HSC process (Hemlock Semicon­ductor Corporation) for production of silicon was initiated. The process is based on hydrogen reduction of dichlorosilane (DCS) to produce the polysilicon. The chemical vapor deposition reaction for DCS is faster in rate than the conventional process route which utilizes trichlorosilane (TCS) as the silicon raw material. Status and progress are reported for primary activities of base case conditions (30%), reaction chemistry (25%) and process flow diagram (20%). Discussions with HSC and construction of a process flow diagram are in progress .

Preliminary economic analysis of the BCL process (Case B) was completed. cost analysis results are presented based on a preliminary process design of a plant to produce 1,000 metric tons/year of silicon. Fixed capital investment for the plant is $14.35 million (1980 dollars) and product cost without profit is 11.08 $/kg of silicon (1980 dollars). cost sen­sitivity analysis indicate that the product cost is influenced most by plant investment and least by labor. For profitability, a sales price of 14 $/kg (1980 dollars) gives a 14% DCF rate of return on investment after taxes.

~a.-Q_~-~~ APPROVALiG~TURE

3/to/ <oo llATE

17

SILICON MATERIAL TASK

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Cambridge, Massachusetts

Contract Title: Investigation of the Hydrogenation of SiC1 4

Contract No. : 955382 (subcontract under NASA Contract NAS7-100, Task Order No. RD-152)

A laboratory research and development program has been carried out since April of last year to study the hydrogenation of silicon tetra­chloride to trichlorosilane,

3 SiC14

+ 2 H2 +Sit 4 SiHC13

After some initial reaction kinetic measurement as functions of pressure, temperature and H2/sicl4 ratio, the effect of copper catalyst on the rate of the hydrogenation reaction was studied. A cement type copper was evaluated at 5 wt% loading based on Si metal charged. This catalyst is the type of copper selected for the hydrogenation unit in the EPSDU of the Union Carbide Silane-to-Silicon Process. The reaction rate in the presence of copper is measured as functions of reaction temperatures (450°, 500°C), reactor pressures (300, 500 psig) and H2/SiCl4 ratios (1.0, 2.8). The initial stage of the reaction in the presence of copper showed an induction period during which no catalyt­ic activities were observed. After about 20% conversion of the Si mass bed, the rate of the hydrogenation reaction increased significant­ly. For example, at 500 psig, 450°C and Hz/SiCl4 ratio of 2.8, the hydrogenation of SiCl4 in the presence of copper gave 28% SiHCl3 (based on total chlorosilanes) at 60 seconds residence time versus 22% SiHCl3 under similar reaction conditions but with no copper added.

The large increase of dichlorosilane conversion in the presence of copper is most interesting. All the hydrogenation experiments in the presence of copper show that the SiH2Cl2 conversion increases by 200% to 300% over the same reaction with no copper added. For example, at 500 psig, 500°C and Hz/SiC14 ratio of 2.8, the hydrogenation of SiCl4 in the presence of copper produces 3.6% SiH2Clz at 180 seconds resi­dence time versus only 1.6% of SiHzClz with no copper added. Evalua­tion of other forms of copper catalyst and equilibrium constant measurements are in progress.

18

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Contract Tit I e :

Contract No. :

SILICON MATERIAL

Solarex Corporation

Rockville, MD 20850

Analysis of the Effects of Impurities

in Silicon

955307

The purpose of this program is to conduct a solar cell fabrication and analysis program to determine the effects on the resultant solar cell efficiency of impurities in­tentionally incorporated into silicon. The program em­ploys "flight-quality" technologies and quality assurance to assure that variations in cell performance are due to the impurities incorporated in the silicon .

A total of thirty-one (31) experimental lots and one (1) baseline (uncontaminated) lot have been processed and tested along with verification, monitor and control cells. The cells from control silicon including verification, monitor and control cells have exhibited average AMO cell efficiencies of nearly 13% at 25°c (in excess of 15% AMl at 25°c). No cross contamination of control or monitor cells has been observed. The results from the baseline material supplied by JPL indicated excellent control of the experiment. This lot was run at the very end of the program and the results were practically indistinguishable from the control wafers.

Cells with various doping materials and doping levels were fabricated. The test cells appear to be clustered in two distinct resistivity ranges, namely around 0.2 n-cm and between 3.0 and 5.0 n-cm. The lower-resistivity cells in general exhibit higher open-circuit voltages and lower short-circuit currents than the control cells (1.0 to 3.0 n-cm). The higher-resistivity cells exhibit lower open­circuit voltages. The short-circuit current is much more susceptible to change by impurity incorporation than the open-circuit voltage although several lots have shown sev­ere degradation of both current and voltage. Further study with control wafers in the same resistivity range would be required to clear up any ambiguity due to dif­ferences in starting resistivity. There was ample evi­dence, however, that certain impurities such as titanium, tantalum, and vanadium are particularly bad even in very small concentrations. Cell performance appears relative­ly tolerable to impurities such as copper, carbon, cal­cium, chromium, iron and nickel in the concentration levels which we considered.

19

Contract Tit I e :

Contract No.:

SILICON MATERIALS TASK (Part 2)

Westinghouse R&D Center/Dow Corning Corp.

Pittsburgh, PA 15235

INVESTIVATION OF THE EFFECTS OF IMPURITIES AND PROCESSING OF SILICON SOLAR CELLS

954331

The objective of this program is to determine the effects of impurities, processing and impurity-process interactions on the properties of silicon and silicon solar cells so that impurity limits for solar grades of sili­con can be defined and that cost-benefit tradeoffs can be made by the users of this. cheaper, less pure silicon grades.

Phase III of this effort is now complete. The topics of investigation were thermochemical processing (including gettering synergic and im­purity complexing behavior), performance reduction inn and p-basecells by impurities, non-uniform impurity distributions in conventional CZ ingots and large area ribbons, and preliminary investigations of aging (long term) effects of impurities.

Overall our data show that bulk lifetime reduction by impurities in both n and p-silicon are the dominant cause for efficiency reduction in sili­con solar cells. We can by use of a mathematical model and impurity concentration data,project the performance of solar cells fabricated on impure single crystal wafers. Assuming some form of melt replenishment will be employed to transform polycrystalline silicon via crystal growth to sheet or wafers we estimate that no more than 'v 100 ppma of the more benign impurities will be tolerable in solar grade feedstocks. For impurities like Ti or V which severely degrade cell efficiency an upper limit on feedstock concentration is about lppm if cell efficiency is to remain within 90% that of uncontaminated devices. If higher efficienc:f.es are required the impurity tolerance must be reduced further.

Fast diffusing species like Fe or Cr can be neutralized by POCi3 or HCi gettering at temperatures between 900 and 1000°C. The efficiency of Ti doped cells can be improved by up to 1.5% (absolute) after 5 hr. treat­ment of 1100°C. Mo contaminated cells show no improvement in perform­ance even after intensive gettering.

A corollary to these experiments is that our data suggest little change in extrapolated cell performance after 20 years for Mo or Ti-doped de­vices but that Cr doped cells may well undergo adverse aging effects.

There is no evidence for extra device performance degradation due to non­uniform distributions of impurities like Fe, Cu, Ti or Mn in 3 in. di­ameter CZ crystals or 4 cm wide silicon webs.

We find correlations between cell performance reduction, impurity segregation, and liquid diffusivities according to the position of a given impurity in the periodic table which can be used to estimate im­purity effects where hard data are unavailable.

Approval ignature Date

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Contract Title:

Contract No. :

SILICON MATERIAL TASK

UNION CARBIDE CORPORATION

Tonawanda, New York 14150

Silane-to-Silicon EPSDU

954334

Design and engineering work on the EPSDU, sized for 100 MT/YR throughput, has concentrated in three activity areas: Finalizing general facility requirements; detailing equipment specifications; and initiating equipment procurement/fabrication. The program sche­dule calls for EPSDU installation subcontracting to begin in July, 1980, with preliminary site preparation.

General facility requirements which have been finalized include such items as site design/evaluation. Service utilities such as electric power, fuel, process/potable water, sanitary sewer, and process gases have been defined. Environmental permit applications have been sub­mitted to appropriate municipal agencies.

Detailed specifications have been written and vendor quotations re­ceived ·for the major portion of all process and waste treatment equip­ment associated with producing high purity silane. Several design modifications were made to improve on operability and economics, which included a simplified hydrogenation reactor feed system, a much sim­pler waste treatment system, and a packed silane column, instead of a trayed column. Specifications for equipment associated with silane pyrolysis and silicon product melting will await additional results from supporting R & D activities in these areas.

Equipment procurement/fabrication was initiated in early February, 1980, which represents a major activity during the next several months.

Installation and checkout of the free-space reactor PDU was com­pleted, and was operated for eight hours at the design feed rate of 5 lb/hr. A longer duration (24 hr.) run will be tried shortly. Work is in progress on an alternate silane pyrolysis using a fluidized bed. Basic design data were obtained such as deposition rate, critical silane concentration, product particle separation, and capacitive bed heating. PDU design was initiated.

A subcontract was signed with Hamco for the design and development of a silicon melter system for EPSDU, and work started on March 1, 1980. The consolidation scheme is based on dropping molten silicon shots through the bottom of a crucible and solidifying them in a cooling tower.

A chromatographic method has been identified and evaluated for determining trace levels of phosphine in silane. Using a photoioniza­tion detector, an ultimate detection limit of about 3 parts-per-billion should be possible. This method forms part of the EPSDU Q.C. system.

~·~ 3/o/;1.Pv 1~oval Signature · ' Dafu

In-House Program

SILICON MATERIAL TASK

Jet Propulsion Laboratory

Pasadena, California

Silicon Processing

To investigate the extent of silicon dust for mation in silane pyrolys is, a series of experiments . us ing the one-inch- diameter fluidized bed reactor (FBR) was conducted. I n these tests , over the range of 1 to 15 mole percent silane in hydrogen feed at 600-7000C, less than 2% of the silicon produced was in the form of fine dust. Consid~r ab l e agglomer ation of the bed occurred in these runs when the velocity was less than six times the minimum fluidi­zation velocity (HFV). Above e ight times MFV, agglomeration did not occur. The deposit was dense when deposi t ed at temperatures above 650°C .

In the area of the continuous flow pyrolyzer (CFP), a seri es of eight exploratory runs at various silane concentrations, flow rates, t emperatures , and pressures was conducted. Runs 5 and 6 gave indi­cations of extremely high throughput a t 100% conversion in small reactor l engths, a t temperatures of 800°C and above . For these conditions, the mean particle size was about 0.2µm. Conditions for Run No. 8 were: silane f low rate of l . 6kg/hr, temperature 600°C , pressure 100 psig, and no particl e feed . About 33% of the silane was converted to s ilicon. BET anal ys i s gave an average diameter of 0.58µTI for the particles, which were of a ·dull black color . This diameter is much l a r ger than any other achi eved to- date for free space silicon production. Pr e limina ry SEM examination s hows that coagulation and CVD condensation pr ocesses occurred simul t aneous l y in the CFP during a run .

The program of the Silicon Materia l Research Laboratory , an in-house laboratory for direct support of contractor activities in the areas of the consolidat ion of silicon materials as well as con­centration and analyses of impurities, has progressed as fol l ows : The Thermally St imulated Capaci tance Measurement apparatus (TSCAP) for the analysis of impurities in silicon and a number of other pieces of equipment are operational; plans have been made for the investiga tion of the consolidation of submicron silicon powder from Union Carbide Corporation.

3/tu/so Approval Signature Dote

21

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LARGE AREA SILICON SHEET TASK

Applied Solar Energy Corporation City of Industry, California

Contract Title: Silicon Solar Cell Process Development, Fabrication and Analysis

Contract No.: 955089

The objective of this program is to investigate, develop and utilize tech­nologies appropriate and necessary for improving the efficieny of solar cells made from various unconventional silicon sheets .

In this period, four sheet forms, namely EFG (RH) multi-ribbon, dendritic web, SOC and HEM have been processed and evaluated.

Solar cells were fabricated using either a standard process (baseline process) and some additional process modifications. These process modifications included: formation of shallow junction and fine grid line pattern, application of better AR coating (i.e. MLAR), BSF and BSR processes, gettering by diffusion glass, grain boundary passivation efforts and large area cell fabrication. Performance was evaluated under both AMO and AMl conditions and efficiency conversion ratios were also obtained. In addition, back-up measurements were made of minority carrier diffusion length, spectral response, dark diode I-V characteristics and use of fine lightspot scanning . Results are reported •

Efforts to identify shunting problems caused py the BSF process were made by ion microprobe/SIMS analysis and optical microscope observation of front junction areas of the finished cells. The results suggested that junction area was contaminated with aluminum, in the form of alloy penetration pits. A discussion of the junction shunting problem will be given •

Approval Signature Date

23

SILICON SHEET TASK

ARCO Solar, Inc. Chatsworth, California

Contract Title: Vacuum Die Casting of Silicon Sheet for Photovoltaic Applications

Contract No.: q55325

The objective of this program is to develop a die casting process for producing silicon sheet suitable for photovoltaic cells and to develop production techniques for optimization of polycrystalline silicon solar cell output.

The vacuum aspect of the process has been replaced by a casting technique at atmospheric pressure in which sheets are formed by press­ing a liquid sessile drop of silicon in a two-piece die. Die materials consisting of high density graphite coated with a fused barrier layer of NaF - Na Si03 have been selected. After solidifying the silicon, the die par~s are separated at approximately 1100°c before the barrier layer freezes. In the laboratory, sheets are released from the die by etching in HF, but in production this step can probably be avoided. Dies are reused. Both circular and square sheets up to 30 mm across by 1 mm thick have been produced. Difficulties encountered in the process are (1) incomplete filling of the die, (2) surface crazing of the sheets, (3) bulk cracking. Also cracks and surface irregularities can lead to fracture during lapping. Incomplete filling of the die seems to involve both the reaction of silicon with NaF and die symmetry. The problem is less severe for square dies. Surface craz­ing is due to differential contraction between the fused salts and silicon and can be eliminated by altering the composition of the salt mixture. Bulk cracking appears to be associated with the expansion of silicon as it solidifies. Progress in die design to avoid bulk cracking will be described.

Approval Signature Date

24

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LARGE AREA SILICON SHEET TASK

CORNELL UNIVERSIJV Ithaca, New York 14853

Contract Title: Characterization of Structural, Electrical and Chemical Properties of Silicon Sheet Material

Contract No. : 954852

Large grain EFG and Web material was investigated by optical micro­scopy, x-ray, EBIC, TEM and HVTEM (High voltage transmission electron microscopy). Results obtained to date:

a) Large grain EFG The defect structure of this material is similar to that of small grain EFG, i.e. the predominant defects are coherent twins and micro­twins, incoherent twins on 112 planes, and dislocations. The disloca­tion distribution is uneven and varies greatly from grain to grain. Twin boundaries are not, partially, or fully electrically active. No precipitates were found, although a search was made in view of the eutectic theory of large grain EFG. It should be noted, however, that small carbon related defects may be invisible in the TEM, due to lack of strain contrast (an example for a carbon related, TEM invisible defect is the socalled B swirl). A combined EBIC and TEM study on one and the same specimen is being carried out in order to relate electri­cal activity to defect structure of the boundary. The 3 •• 4 um speci­mens are thick enough to contain the full EBIC generation volume (Eelectron = 10 KeV) but thin enough to be transparent to the 1.2 MeV electrons of the HVTEM.

b) Web material The defects in this material (dendrites excluded) are a coherent twin boundary in the mid-plane of the ribbon and dislocations. EBIC shows that the twin boundary per se is not (or only weakly) electrically active. The twin boundary appears to act as a di3loc,tion source. The dislocation density distribution count (5 •• 10 /cm) in the center. Close to the edges {d~nd!ites) the dislocation density is about a factor 50 lower {1.10 cm) •

Approval Signature Date

25

Contract Title:

Contract No. :

LARGE AREA SILICON SHEET TASK

CRYSTAL SYSTEMS, INC.

SALEM, MA 01970

SILICON INGOT CASTING--HEAT EXCHANGER METHOD/MULTI-WIRE

SLICING--FIXED ABRASIVE SLICING TECHNIQUE (PHASE III)

954373

This contract is for casting silicon ingots by the Heat Exchanger Method (HEM) and slicing by multi-wire Fixed Abrasive Slicing Technique (FAST). Phase III of this program has been completed and Phase IV has been started since December 15, 1979.

The scope of Phase IV of the HEM program is to scale up to 30 cm cube, 63 kg silicon ingots and also show technical demonstration of the tech­nology. A large HEM furnace with a 60 cm diameter heat zone has been designed, fabricated and used for casting 20 cm cube ingots.

Two significant developments towards reducing costs have been carried out. It has been shown that flat plates welded to form a crucible can be used to cast crack-free ingots. This improves the squareness of the corners and, therefore, the yield. Slagging experiments during direc­tional solidification with low-cost UMG meltstock have improved the structure of the cast ingots.

The scope of the FAST program is to slice 10 cm x 10 cm and 15 cm diam­eter ingots. The goal is to slice 750 wafers at 25 wafers/cm. A new bladehead to acconunodate 750 wires has been designed and is presently being fabricated.

Recent experiments with slicing had produced low yields. Causes for this poor performance have been vibrations transmitted to the workpiece at higher speed and use of stressed polycrystalline silicon ingots. The present bladehead on the high speed slicer is a modification to the machine where emphasis was on achieving high surface speeds. At these speeds the support members of the slicer were not rigid enough to ab­sorb resultant vibrations. Slicing experiments at lower speeds which are conunensurate with the support members have produced high yields. Slicing at lower speeds has, therefore, reduced the life of the wires. The large bladehead currently being fabricated has been designed to provide rigid supports at high speeds. Under these conditions combina­tion of effective slicing and long blade life will be achieved.

In the area of blade development with recently fabricated impregnation unit significant improvement in performance has been achieved. Experi­ments have shown 86% yield with cutting rates of 2.5 mils/min, 0.062 mm/min. The failure mode of these wires has been identified as diamond pull-out. The optimiza~i of this multi-parameter condition for

-~LJl,._,.tion

26

March s, 1980 Date

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LARGE AREA SHEET GROWTH

Energy Materials Corporation

Harvard, Massachusetts

LOW ANGLE SILICON SHEET GROWTH

955378

This program's objective is to demonstrate the feasibility of a novel approach to horizontal crystal growth. Low Angle Sili­con Sheet Growth has the potential of combining the material quality and high volume solidification rates of casting and Czochralski growth with the direct shaping characteristics of ribbon growth. This technique will also allow very high pull rates without generating the stresses which appear to limit ribbon growth. In horizontal crystal growth the ribbon is pulled horizontally or at a small positive angle from the melt surface. The key feature is that the direction of the ribbon pull is essentially perpendicular to the direction of the bulk crystal growth. The freezing interface is oriented so that the crystal grows slowly into the melt and loses heat of fusion through the thin ribbon above it, radiating from the large solid surface. The leading edge of the interface must grow at an equal, but opposite, velocity to the pulling velocity. This thin edge is then the continuously forming seed for the bulk crystal growth.

The basic premise of our approach to control of the growth rates at the leading edge, the lateral edges, and in the thick­ness direction (into the melt) is that thermal impe.dances in the crucible can function to provide the required temperature distribution which will lead to inherent growth stability. A small positive angle of growth from the melt surface, to provide a slightly raised meniscus under the solidifying crystal, and a relatively shallow melt to preclude convection currents are also important aspects of this approach .

Progress to date indicates that the process works. Initial ex­periments demonstrated the utility of a scraper mechanism to stabilize a meniscus under the growing ribbon. Ribbon lengths up to 68 cm were obtained. Ribbons could be grown at widths up to 2.5 cm and thicknesses from .06 to .25 cm. Growth rates have usually been set at 20 to 30 cm/min; however, maximum rates of more than - 70 cm/min - can easily be achieved. One ribbon 18 inches long by 1 inch wide .has been grown. The present 1 imi­tation has been either the length of the puller mechanism or the decrease in melt level. Initial experiments have indicated that relatively simple modifications to the thermal impedance struc­tures can easily achieve the geometric control needed for cross­section shape.

¥dt?& Date

27

LARGE AREA SILICON SHEET TASK

P.R. HOFFMAN COMPANY

Carlisle, Pennsylvania 17013

Contract Title: Slicing of Single Crystal and Polycrystalline

Silicon Ingots using Multi-Blade Saws

Contract No.: 955563

The objective of this program is to slice several silicon ingots to yield 8 and 10 mil thick wafers at a rate of 18 to 25 wafers per centimeter of ingot length, and to provide all necessary cost data to allow complete process cost analysis for each of the three types of multi-blade slurry saws utilized. Although a complete analysis ·of the quality of wafers produced will not be provided, sufficient eval­uation of dimensional parameters, yields and production rates will be performed to provide for optimization of the wafering process.

Progress to date has resulted in moderately successful wafering of a 100mm diameter polycrystalline ingot on 2 of the 3 saws to be utilized, with completion of a run on the third saw anticipated by 14 March 1980. Yield from the Varian 686 saw was particularly encouraging, with only 3 of 273 wafers damaged in slicing. Major difficulties encountered have been in mounting the ingot securely to the work holder and supporting partially completed wafers to eliminate the tendency to tilt to one side, resulting in both greater Kerf loss and tapered wafers. As the first run on each of the 3 saws was intended to be performed under controlled conditions, i.e., process variables would be related to machine design only, both mounting and wafer support problems will be addressed in sub­sequent wafering runs.

Approval Signature Date

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Contract No. :

LARGE AREA SILICON SHEET

HONEYWELL TECHNOLOGY CENTER

BLOOMINGTON, MN 55420

Silicon-On-Ceramic Process

954356

The objective of the program is to demonstrate technology readiness of the silicon-on-ceramic process. There are two areas in which improve­ment must be made: throughput and cell efficiency. The throughput will be achieved by a SCIM-coating system that simultaneously coats two mul­lite substrates, each 5"x40". This system has been designed, construc­tion of parts is complete and assembly is in the final stages (3/5/80). The design is based onamathematical model of the thermal conditions in the coater, and differs considerably from that of the present SCIM coater, with vastly improved transverse temperature uniformity, menis­cus height control, and substrate transport. These three areas continue to present problems in the present (SCIM I) coater. SCIM I has been modified several times in the past quarter but silicon layers with uni­form thickness have not been produced consistently. The system has been used to demonstrate the coating of slotted substrates. The silicon appears to cover the slots in much the same watt as in the dip-coating process •

An extensive investigation of the cell processing variables has now been completed. The substrate doping, diffusion time, diffusion temperature and layer thickness were varied over wide ranges. Unfortunately, this investigation has not led to significant improvement in efficiency. The best efficiencies are obtained with material grown at 0.06 cm/sec (230µm thick) with a base doping concentration of 5xl0 16 /cm 3 with a PH3 diffusion at 850°C for 60 minutes. The average efficiency is just over 9% with the best cells measuring 10%. With the present process, we can­not reach the cell efficiency goal of 11%. The basic limitation is the short circuit Jsc, which is found to decrease as the doping is increased.

The short circuit current limitations of SOC cells has been explored in detail by a high resolution light beam scan (LBIC) technique to measure effective diffusion length Ln• We find that (1) At grain boundaries, the Ln is one-tenth of the value within good grains. The average value of Ln is one-third of the value within grains; (2) Doping has an un­expectedly large effect on Ln, with Lu~ NA- 0 • 3 ; and (3) Early studies of hydrogen passivation with a hydrogen plasma (at Sandia Labs) shows that recombination at grain boundaries is reduced by a factor of three. Based on these results, we anticipate that the SCIM coating process will give improved cell efficiency because (1) fewer regions with grain boundaries because of the closer approach to "equilibrium" crystallo­graphic texture, and (2) fewer impurities from·the substrate, because of th ch shorter contact time with the melt.

3-5-80 Date

29

Contract Title:

Contract No. :

Large Area Silicon Sheet Growth

Hamco Division of Kayex Corporation

Rochester, New York 14624

Continuous Czochralski Ingot Growth

954888

During the current reporting period, the original phase of the program, requiring the development of equipment and process for the growth of 100 kgms of silicon ingot from one crucible, has been completed.

A 3 month extension has been granted to develop equipment and process capability for the growth of 150 kgms of 150 mms diameter silicon ingot from one crucible. To date, this has been demonstrated once (Run /170) •

The three runs completed during this reporting period are sum­marized below:

Total Si melted Total ingot pulled Pulled yield Monocrystal produced Throughput Crucible diameter Recharge material Ingot diameter

Run //60

108. 7 kg 100.4 kg 92.4%

60.8 kg (60.6%) 1.18 kg/hr

14" 100% lump 12.7 cm

Run //62

104.5 kg 103 .o kg 98. 6%

89. 3 kg ( 86. 7%) 1.06 kg/hr

14" 100% lump

12. 7 cm

Run 1170

156.1 kg 151.5 kg

97% 67.3 kg (44.4%)

1.53 kg/hr 14"

100% lump 15 cm

The emphasis for the remaining 150 kg run will be towards the improvement of the single crystal yield and throughput.

Solar cell efficiencies and purity analysis data have been re­ceived for previously reported 100 kg growth runs. The solar cell efficiency results indicate that there is no apparent degradation in cell efficiency from crystal to crystal for up to 100 kg of crystal growth from one crucible.

Approval Signature

30

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Hamco Division of Kayex Corporation

Rochester, New York 14624

Contract Title: Low Cost Czochralski Crystal Growing Technology

Contract No.: 955270

The program objective is to demonstrate the growth of 150 kg of 6" diameter single crystal silicon from one crucible utilizing the Czochralski technique. The process concepts to be used deal with process improvements aimed at lowering both the melt down and cry­stal growth costs.

Improved process automation techniques utilizing microprocessor controlled crystal growth will also reduce cost and improve process yield.

The contract is divided into the following sections: 1. Accelerated meltback program: a) rods and b) chunk material 2. Accelerated growth rate 3. Microprocessor controls

All equipment and piece parts for the accelerated melt back of polycrystalline rods and the accelerated growth programs have been received and installation is complete.

Work is ongoing to develop the process parameters for poly rod accelerated melt. To date, satisfactory melting has been demonstrated off the puller utilizing the R.F. work coil. Melting inside the Czochralski puller has not yet been demonstrated due to arcing problems at the R.F. coil.

Design of the cold crucible system for melting of polycrystalline chunk material is complete and the purchase order has been placed. Delivery is scheduled during March.

The interfacing of the microprocessor control system to the puller is complete. To date, microprocessor control of initial meltdown, melt temperature stabilization and all motor functions are control­lable by the microprocessor. The crystal growth process can be manually controlled by the operator through the microprocessor. Full microprocessor control of the growth process is the next phase of the program under development.

Approval Signature

31

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Contract Title:

Contract No. :

LARGE AREA SILICON SHEET TASK

Mobil Tyco Solar Energy Corporation

Waltham, Massachusetts 02154

LARGE AREA SILICON SHEET BY EFG

954355

Significant progress in the growth of 10-cm wide ribbon, both in single and multiple arrangements has occurred in the last four months.

In a single ribbon growth unit, 10-cm wide ribbon of a thickness between 150 and 200-µm has been grown repeatedly at speeds of 3.8 to 4. 2-cm/min.

Multiple growth of three 10-cm wide ribbons under continuous melt replenishment has also been demonstrated over six hours, during which ~25 meters of ribbon were grown. However, in that multiple run, the speed at which stable growth occurred was restricted to 2.8-cm/min. due to edge instabilities which require further investigation, in particular with respect to the differences in thermal environment between the cartridges in the multiple machine and that in the single machine. Based on these studies, a minor redesign of the cold shoe arrangement will likely be undertaken.

Efficiencies of 5 x 10-cm2 cells from 10-cm wide ribbons so far have been around 9.5%~ but an efficiency of 12.5% (AMl) has been reached for a 2.5 x 5-cm cell from a 5-cm wide ribbon.

by Fritz Wald 03/07/80 Approval Signature Date

32 I

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Contract No.:

LARGE AREA SILICON SHEET TASK

Siltec Corporation Menlo Park, California

CONTINUOUS LIQUID FEED CZOCHRALSKI GROWTH

DOE/JPL-954886

This project is directed toward the design and development of equipment and processes to demonstrate continuous growth of crystals, by use of the Czochralski method, suitable for producing monocrystalline silicon for use in solar cells. 11 Continuous 11 is defined as the growth of at least 150 kg of monocrystalline silicon ingots, 150 mm in diameter, obtained from one growth container.

Our approach in meeting this goal is to develop a furnace with continuous liquid replenishment of the growth crucible. This has been accomplished through use of a meltdown system with a continuous solid silicon feeder and a melt transfer system, with associated automatic feedback controls.

During the past month the effort for the development of the new melt transfer system continued with the following goals achieved:

The size of the transfer tube system was significantly reduced so that growth of a 150 nm ingot from a 1211 dia crucible could be accomplished.

The development of a new heating element formed of graphite, usable for multiple runs, was completed. Difficulties in achieving precise tempera­ture distribution along the tube arose through the miniaturization of the transfer system. Many temperature profiles along the melt transfer tube had to be established before a heating element could be produced that would assure the required temperature tolerances nece·ssary to avoid melt solidification inside the tube during continuous melt replenishment.

Additional instrumentation was added to the melt transfer system so that stagnation of melt within the tube during continuous melt replenishment can immediately be detected. The accuracy for key elements of this transfer control system, such as temperature regulation of the tube and melt level sensor, was significantly improved.

Fabrication of the silicon particle feed mechanism, to be used for con­tinuous recharging of the meltdown_ chamber, was completed. The system was assembled and tested under simulated conditions. The mechanism is designed in such a manner that crystal growth and continuous melt replenishment are not interrupted through reloading of the storage container for the silicon particle feeder.

Date

33

Contract Title:

Contract No.:

LARGE AREA SILICON SHEET TASK

Siltec Corporation Menlo Park, California

ENHANCED I.D. SLICING TECHNOLOGY

DOE/JPL-955282

The purpose of this program is to develop and demonstrate enhanced I.D. slicing technology that will significantly increase the number of useable slices per inch of ingot over industry practice. This method requires a reduction of both blade and slice thickness and will be achieved through a combination of three key slicing technology elements: ingot rotation with minimum exposed blade area, dynamic cutting edge control and the use of prefabricated insert blades.

Demonstration runs of ingot cutting with ingot rotation and minimum exposed blade area were performed. Slices with a diameter of 100 mm, 250 µm thick and kerfs of 152 µm were produced. Typically achieved cutting feed rates are in the range of 13 to 15 mm per minute. Elec­tronically programmed ramping devices for the ingot feed system were developed to optimize cutting rates.

The cutting edge position control system was manufactured and installed on the 12 11 saw head. It was demonstrated that blade deflection through the use of a hydrostatic hydrodynamic bidirectional bearing assembly, which responds to a signal continuously received from a blade position monitor, can be controlled. Cutting test runs showed that typical blade deflection of 50 to 75 µm, with low kerf blades of 152 µm, can be reduced by an order of magnitude through the use of dynamic cutting edge control. With blade deflection minimized, major benefits are obtained: wafer edge chipping and breakage are drastically reduced, effective kerf loss is smaller, and average cutting rates from 13 to 15 mm/min were increased to 25 mm/min.

Cores for the low kerf blade with the prefabricated inserts made of stainless steel and beryllium copper were received. Prefabricated cutting edges with a 4 3/4 11 diameter lip 10 mils thick are presently manufactured. Some difficulties were experienced in obtaining these large diameter rings.

Low kerf blades 152 µm, requiring special etching techniques, were tested. The cutting performance of this blade is good. Tensioning of the cutting edge can be substantially increased due to the removal of microfractures by the etch process in the core material near the cutting edge. Lifetime tests for this new blade are underway.

J,.fJPva1 Sig~ture 'oafe 34

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LARGE AREA SHEET SILICON

Spectrolab, Inc •

Sylmar, CA

Contract Title: Silicon Solar Cell Process Development, Fabrication and Analysis

Contract No. : 955055

Phase I of this contract has been concerned with the processing of solar cells from silicon material produced in the Large Area Silicon Sheet Task. Cells have been made by a baseline processing regimen utilizing aerospace cell production techniques and also by "optimized" processing that might be expected to enhance the con­version efficiency of particular silicon materials •

In the second phase of this contract additional goals have been introduced for the attainment of suitable conversion efficiencies utilizing low cost processing methods. Phase I measurements of conversion efficiency were made at AM0-28°c, Phase II measurements will include a limited number of conversion efficiency determina-

o tions made under AMl-28 C.

Presentation at this PIM will include results for cells fabricated from EFG, HEM, Web and Hamco materials.

35

March 7, 1980

Date

Contract Tit I e :

Contract No. :

LARGE AREA SILICON SHEET TASK

University of Missouri - Rolla

Rolla, Missouri

Determination of Effect of Varying Partial Pressures of

Reactant Gases, Primarily Oxygen and Nitrogen, in a Fur­nace Atmosphere where Molten Silicon is in Contact with Die and Container Material. 955415

During this period the interaction of molten silicon with various substrates, including hot pressed silicon nitride, sialon, silicon carbide coated graphite, and CVD silicon nitride on hot pressed silicon nitride, was investigated. The behavior was similar to previous results on CNTD silicon nitride, but anomalous results with the sialon substrates (non-melt of the silicon above the nor­mal melting temperature), and the silicon carbide on graphite (apparent absorption of the molten silicon through the silicon carbide coating into the graphite), was found. The results of post-sessile drop experiment analysis of these specimens will be presented.

The thoria-yttria oxygen cell has been modified to provide a better seal against possible leaks when operating at slight neg­ative pressures. These conditions occur during p02 measurement at some other LSA sheet task contractors' facilities. The cell is currently being readied for transport to Pasadena where po2 measurements of the atmosphere in JPL's silicon sessile drop furnace will be measured.

Approval Signature

36

Marcb 2 , J 980 Date

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LARGE AREA SILICON SHEET

Westinghouse Research and Development Center

Pittsburgh, PA 15235

SILICON WEB PROCESS DEVELOPMENT

DOE/JPL 954654

In the period since the most recent Project Integration Meeting ex­cellent progress has been made in melt replenishment. Simultaneous melt replenishment and web growth has now been demonstrated for periods up to a one day growth cycle which comprises 17 hours of web growth and 7hours of. non-growth time such as cleaning loading, start-up and cool-down. The SAMICS/IPEG economics analysis indicates that melt replenished growth must be sustained for periods approaching a two day growth cycle. Large increases in the demonstrated time periods of melt replenished growth are expected in the near future. Because of the success of the initial melt replenishment system, a second web growth furnace has re­cently been converted for melt replenished growth.

Important improvement in the thermal gradients within the susceptor, crucible and melt system have been attained. This improvement permits growth under a wide range of growth conditions from start-up to high throughput. This improveme~t also permits growth of web within the preferred geometric center of the susceptor system because it provides thermal symmetry over the full range of melt replenishment feed rates.

Melt level sensing was demonstrated during the period s·ince -the last Project Integration meeting. This achievement had earlier fallen be­hind the expected demonstration date because of delayed delivery of system components. The demonstrated system provides a visual (meter) output and permits manual control of the polysilicon feed rate for melt replenishment. A temporary circuit for coupling the melt level sensor and the mechanized pellet feeder to provide closed loop control is now being built and will be used experimentally in the near future.

The economic consequence of dendrite utilization was evaluated by con­sidering three options: 1) throw away the dendrites, 2) salvage (re­melt) the dendrites as removed from web prior to cell fabrication, and 3) salvage the dendrites as removed from web after cell fabrication. All of the options indicated web costs, based on the SAMICS/IPEG analy­sis, that fell well below the DOE/JPL 1986 goal. The difference of the costs was small, the spread being less than one cent per peak watt • Growth behavior under the conditions of options 2 and 3 have been found to be no different from that of option 1. Solar cells prepared accord­ing to option 2 have been found to be equivalent to cells prepared according to option 1. Cells prepared according to option 3 are now being evaluated.

Approval Signature Date

37

LARGE AREA SILICON SHEET TASK

Jet Propulsion Laboratory

Pasadena, California

In-House Program

(1) Silicon Crystal Growth Laboratory: Crystal growth work on silicon bicrystals with varying grain orientation has been initiated.

(2) Photovoltaic Materials and Device Testing Laboratory:

(a) Material preparation facility consisting of lapping and polishing machines and dicing saw is in use.

(b) Beam Blanking system has been incorporated on the scanning electron microscope and experimental set-up has been completed with lock-in amplifier, X-Y recorder, voltage ramping circuit and digital readout meters. EBIC measuring system is also operational.

(c) Low temperature system for I.R. spectrophotometer has been made operational.

(d) Laser scanning technique using helium-neon laser is being used for the study of grain boundaries in silicon sheet material.

(3) Solar Cell Prototype Fabrication Laboratory: Initial photo­lithographic processing has been completed, but further process optimization is necessary. A baseline process for 2x2cm CZ and HEM silicon wafers has been established, with repeatable effi­ciencies of 12% AM~ at 28~C. Gettering experiments with low temperature hydrogen anneal have been initiated.

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ENCAPSULATION

CASE WESTERN RESERVE UNIVERSITY

CLEVELAND, OHIO

SYSTEMS STUDIES OF BASIC AGING AND DIFFUSION

954738

The objective of this study is to establish the kinetics and mechanism of thermal and photo-oxidative degradation of candidate encapsulation materials for the LSA Project. That information is to be used to dev­elop accelerated testing and life performance prediction methods and to guide the continuing selection of optimum performance encapsulation material systems.· The study is being carried out in cooperation with related studies at JPL.

The present work is aimed toward establishing the modes of degradation of poly(n-butylacrylate)(PNBA). It has been found that for PNBA:

1. There is relatively little change in polymer mass after exposure to a high intensity medium pressure mercury lamp for times up to 120 minutes.

2. Exposure over the first two hours results in a small decrease in molecular weight determined by a dilute solution viscosity method. The viscosity appears to increase slowly with further exposure.

3. Similarly, there is little indication of gel formation over the initial period.

4. The absorbance band at 275 nm which grows rapidly during the first 20 hours of UV exposure in a filtered QUV Acclerated Weathering Tes­ter is attributed to the formation of a relatively stable degradation product from trace ketone groups in the polymer •

Continuing studies include the determination of:

1. Changes in polymer mass, molecular weight and its distribution, and sol-gel ratio after long term exposures.

2. Formation of degradation products by UV and Fourier transform infrared techniques •

3. The quantum efficiency of the reactions.

The results are being used to establish the validity of predictions of long exposure performance based on short term testing and to evaluate the feasibility of using these polymeric materials as encapsulants.

3/10/80

39

Conl!ract Title:

Contract No. :

ENCAPSULATION TASK

Illinois Tool Works INC., Venture Group

Elgin, Illinois

Ion Plating of Solar Cell Arrays

955506

Sununary of Progress from December 4, 1979 to March 1, 1980

The ITW contract was initiated in December 1979 to investigate, de­velop and demonstrate the capability to produce operational solar cells having metallizations and AR coatings deposited by gasless ion plating, which will separately and/or in combination with a low cost encapsulation system meet the LSA project life, cost and performance goals.

Preliminary studies have been performed to determine what, if any, ill effects the deposition of energetic metallic ions may have on the diffused Si wafer. Of particular interest at this point was the possibility that during ion plating of the front surface electrode, metallic ions would "punch through" the p-n junction, having a dele­terious effect on the cells performance.

To investigate this possibility completed solar cells with conven­tional front and back metallizations (less AR coatings) were sub­jected to ion plating at the highest practical energy levels attain­able with present equipment. Measurement of the dark I-V character­istics of these cells before and after their front surfaces had been ion plated demonstrated that no decrease in the cells performance had occurred.

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"3-7-80 Date

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ENCAPSULATION TASK

MOTOROLA INC., SEMICONDUCTOR GROUP

PHOENIX, ARIZONA

Contract Title: ANTI-REFLECTION COATINGS ON LARGE AREA GLASS SHEETS

Contract No. : 955339

Summary of Progress for Period of December 1, 1979 to March 1, 1980.

This project was performed in order to develop a method of producing inexpensive and durable antireflective coatings for use on solar module cover panels. The method researched employs aqueous solutions of sodium silicate which are applied to cover glass panels in a thin, uni­form film by constant-speed withdrawal of the panels from the solution. Hardening of the sodium silicate film is then accomplished by exposure to mineral acid. The project is now nearly completed.

The preferred sodium silicate concentration for coating has been identified. In conjunction with this, coating has been performed at a full range of withdraw! speeds in order to characterize the properties of the films produced, and the optimum speed has been selected.

Durability evaluation has been performed by exposure to staining materials and biological substances. On the basis of these tests, soil and stain release properties of the films have been shown to be close to that of unfilmed glass.

In addition, prolonged detergent exposure and ultrasonic agitation have been used to determine long term durability. Although the detergent tests are still being evaluated, ultrasonic exposure results indicate extreme film strength.

Approval Signature

41

March 7 ~ 1980 Date

Contract Title:

Contract No. :

ENCAPSULATION TASK

MOTOROLA INC., SEMICONDUCTOR GROUP

PHOENIX, ARIZONA

ANTI-REFLECTION COATINGS APPLIED BY ACID LEACHING PROCESS

955387

Summary of Progress for Period of December 1, 1979 to March 1, 1980

This project has as its purpose the research of an established process for producing antireflective films on glass surfaces. The process is being evaluated for use on solar module cover panels.

The process involves the etching of soda-lime glass in fluosilicic acid solution to produce a skeletonized silica layer which serves as the AR coating. Etching of glass at 45°c, ss0 c, and 65°c has been performed, with the determination of optimum solution compositions, etch durations, and film effectiveness for these temperatures.

Because of the microscopically porous nature of the film produced, stain testing was performed using intense dyes and biological substances. Stain and soil release characteristics were very good, being only slightly below that of unfilmed glass.

In addition, prolonged exposure to detergents and to ultrasonic agitation have been used to evaluate long term durability. Although the results of detergent testing have not been analyzed, ultrasonic agitation has revealed good durability.

Approval Signature

42

March 7, 1980

Date

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Contract Title:

Contract No. :

ENCAPSULATION TASK

ROCKWELL INTERNATIONAL SCIENCE CENTER

Thousand Oaks, CA. 91360

Study Program for Encapsulation Materials

Interface for Low Cost Silicon Solar Array (LSA).

954739

The major objectives of this study are to conduct a physical/chemical study of surface and interface degradation in solar cell encapsulant systems induced by moisture, temperature, and UV radiation. Current efforts are now concentrated on development of an atmospheric corrosion model and test plan for low cost solar arrays (LSA).

An atmospheric corrosion model has been developed and verified by five months of corrosion rate and climatology data acquired at the Mead, Nebraska LSA test site. Atmospheric corrosion rate monitors (ACM) installed at the Mead test site show that moisture condensation prob­ability and ionic conduction at the corroding surface or interface are controlling factors in corrosion rate. Protection of the corroding surface by encapsulant is clearly shown by the ACM recordings to be maintained, independent of climatology, over the five months outdoor exposure period.

A newly designed Mead climatology simulator has been implemented in laboratory corrosion studies to clarify corrosion mechanisms displayed by two types of LSA modules at the Mead test site. Further verification of the corrosion model is one important outcome of these controlled laboratory studies. These studies show that the macroscopic corrosion processes which occur at Mead can be reproduced in the ·climatology simulator. Controlled experiments with identical moisture and temper­ature aging cycles show that UV radiation causes corrosion while UV shielding inhibits LSA corrosion. Modification of ionic conductivity by UV degradation at the encapsulant/wafer interface is now suggested as the probable controlling factor in corrosion mechanisms previously documented on Mead aged LSA modules.

Approval Signature

43

;Jua S: /:f'J°>C' Date

Contract Title:

Contract No. :

ENCAPSULATION

Spectrolab, Inc.

Sylmar, CA

Design, Analysis, and Test Verification of Advanced Encapsulation Systems

955567

The objective of this program is to develop test and analysis meth­edology for advance encapsulation systems designs and to determine optimum systems for meeting the Low-Cost Solar Array Project goals.

Progress since the last PIM has included the start up of the contract. Subcontracts have been let with groups at Hughes to develop computer software for structural, optical, thermal, electrical, and economic analysis.

Three strawman designs have been developed to aid in the development of analytical techniques. These designs include a superstrate and a substrate design.

The material properties which are necessary for the analysis have been listed and a matrix of materials· versus these properties prepared. The determing of properties in this matrix has begun.

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ENCAPSULATION TASK

Spire Corporation

Bedford, MA

Contract Title: Integral Glass Encapsulation for Solar Arrays

Contract No.: 954521

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This program is aimed at the development of electrostatic bonding (ESB) as an advanced encapsulation technique for terrestrial solar arrays. The electrostatic bonding process is used to join cells directly to the front cover glass without use of adhesives or other organic materials. A variety of backings can be applied to this bonded assembly.

As of December 1979, all equipment, materials and parts necessary for the fabricat ion of integral glass front modules had been obtained and made operational. Process development required for scaling up the module size had been completed. An initial run of modules had been bonded and backings consisting of ethylene vinyl acetate (EVA) and an aluminum foil/Mylar laminate had been applied. Four of these ESB assemblies are mounted on a standard JPL minimodule frame.

Bonding of these large modules ha,s proceeded during the present period. Routine processing has been applied. However, nonflatness of the hand rolled glass has caused some problems. Grinding and polishing of this material is required.

Work on integrating cell processing and encapsulation by use of preformed contact applied during bonding has continued. Multiple cell assemblies have been fabricated . Process uniformity, necessary for achieving high yield and performance has improved.

During the present period a new task has been added to this program. Spire will demonstrate a specialized application of electrostatic bonding in which planar front surfaced solar cells with interdigitated back contacts will be bonded to Pyrex glass on a hot plate bonder. This approach provides a unique method of handling these thin solar cells since bonding can be performed early in the cell fabrication process. The module bonded at low temperature employs commercially available glass and an electrostatic bonder that can be fabricated at very low cost.

45

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Contract Title:

Contract No. :

Springborn Laboratories, Inc.

Enfield, Connecticut

Investigation of Test Methods, Materi al Properties

and Processes for Solar Cel l Encapsulants

LSA 954527

This program involves the eval uation of materi a l s and processes for the encapsulation of Solar cells. Material sel ections are based on the 1986 cost objective of $2 . 70/M2 (1975 dol l ars ) , ($3.78/M2 - 1980 doll ars) .

During this quarter development efforts on solar modul e potting com­pounds continued. Treatments were developed for the elimi nation of the "blocking" or surface sticking problem in EVA that has presented difficulties for some users. Three approaches were tried: dusting with a release powder, embossing, and extrusion onto one side of a glass fiber mat. The results appear very promising and one or more of these approaches may be empl oyed in a commercia l version that will be made avail abl e to industry. Evaluation of the other candidate pottants (ethylene- propylene rubber, polyvinyl ch l ori de p l astisol, aliphatic polyurethane) continued with measurement of mechanical properties after exposure to RS/4 fluorescent sunlamp and outdoor weathering conditions . Assessment of the corrosion protection provided by the pottants to encapsul ated metal s was a l so determined with the use of salt spray experiments .

A new candidate, poly-butyl acryl ate, was brought into investigation and small quantities were prepared for evaluation. Experimental modules were made with thi s compound using the liquid casting tech­nique and submitted for thermal/humidity cycling tests. Springborn Labs has successful ly dupl icated the synthesi s of a silicone-acrylic block co-polymer initiall y devel oped by Dow Corning under JPL con­tract . This compound has been modified by the incorporati on of a new chemically bound ultraviolet screening agent and is intended for use as an outer cover material . Cast fi l ms of thi s compound are highl y transparent , compliant , and have excellent res i stance to soiling . Experimental modules prepared with this coating are currently under t est.

46

3/7/80

Dote

ENCAPSULATION TASK

UNIVERSITY OF MASSACHUSETTS

AMHERST, MASSACHUSETTS

Contract Title : Development of Synthetic Techniques for Ultraviolet Stablilizers

Contract No . : 955531

The objective of this research Contract is to prepare polymerizable ultraviolet stabilizers and demonstrate facile copolymerization and/or grafting of these stabilizers with acrylic monomers or on polymeric acrylic film formers, eg Korad . Towards this objective, synthesis of 5-vinyl, 2 hydroxy phenyl benzotriazole was demonstrated on the bench scale and in 250 gram scale. A supply of this polymerizable UV stabilizer has been made available to JPL and to Springborn Laboratories for industrial evaluation purposes. Synthesis of other isomers of this class of stabilizers (known as Tinuvin P type stabilizers) is in progress. Yields at each step of the multistage synthetic procedure have been improved, so that the final (wet) yield is satisfactory. The best isomer will be selected on the basis of 1) UV absorp tion characteristics and 2) UV stabilization characteristics through tests conducted partly at JPL. The systhesis of this best i somer will then be scaled up.

Original signed by Dr . V. D. Gupta

Approval Signature

47

3/10/80

Date

ENCAPSULATION TASK

UNIVERSITY OF TORONTO

TORONTO, CANADA

Contract Title: Development of a Life Prediction Model for Solar Cell Modules Containing EVA as a Pottant Material

Contract No. : 955591

Development and validation of a life prediction model for photovoltaic modules is an essential objective of the Encapsulation Task.

Towards this objective, work on this contract was initiated on 7 January 1980. A literature survey of photodegradation of polyolefins such as polyethylene and EVA was completed. A computer model of photo­oxidation of hydrocarbon polymers will be constructed and refined by using experimentally obtained data on photooxidation of simple alkanes. The model will subsequently be extended to ethylene vinyl acetate copolymers and validated by using experimental data on photooxidation of EVA films obtained in the laboratory and short term real time data on two cells and mini.modules depolyed outdoors. Simultaneously a sub­contract with Ecoplastics Ltd has been let to develop instrumental techniques to detect and quantify degradation data in modules after a short term outdoor exposure.

Original signed by Dr. V. D. Gupta

Approval Signature

43

3/10/80

Date

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In-House Program

Encapsulation Task

Jet Propulsion Laooratory

Pasadena, California

Life Prediction Modeling

Quantitative relationships that relate environmental stress such as solar ultraviolet, wind, temperature extremes, and moisture to the rate of degradation of module performance and structural integrity are objectives of the Encapsulation Task in-house efforts. These activ­ities are integrated with contractual activities to develop an over­all module life prediction method.

Photodegradation rates and mechanisms and ultraviolet absorption characteristics of polymeric encapsulants are being measured as a function of polymer composition and test exposure conditions. Data are being obtained for silicones, EVA, and P-nBA. Additional materials will be characterized during the coming year.

Modeling of the photodegradation of UV screening acrylic outer cover films has yielded rates of degradation of the material constituents and of the total system. These data have been _used to provide mate­rial composition criteria for the achievement of optimum low-cost long-life cover films.

Encapsulation material degradation data for low-cost advanced encap­sulant systems is being gathered using various test hardware such as mini-modules (12" x 16"), two-cell modules and individual material samples. Exposure facilities include JPL laboratory test chambers and selected California field test sites at Point Vicente, JPL, Goldstone, and Table Mountain.

A structural computer model has been formulated to study failure modes associated with temperature and moisture expansion stresses within the module encapsulation system. The purpose of this study is to identify areas of potential cracking and delamination and evaluate the possible propagation of these failures.

A long term accelerated module life test is being implemented to eval­uate the validity of a life testing plan developed by Battelle. A closely controlled and monitored module degradation rate experiment with accelerated temperature cycling, high humidity, SOz gas and ap­plied current flow will be conducted with ten prototype modules simul­taneously over a four to six month test period. The test chamber has been modified and preliminary experiments are being conducted in prep­aration for prototype module testing to be initiated in the coming months •

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Contract Title:

Contract No. :

PRODUCTION PROCESS AND EQUIPMENT

Applied Solar Energy Gorporation City of Industry, California

Development of High Efficiency (14%) Solar Cell Array Module

955217

The objective of this program are (1) to design and develop 3" diameter, P /N solar cells with conversion efficiency of 16.596 or better at AMl and 28°c, (2) to design and fabricate tooling necessary to produce the cells and the modules, and (3) to design, fabricats and deliver six modules with a minimum output of 90 watts and AMl and 28 C and with the design goal of 14% overall efficiency.

The module design has been firmly established as previously reported. The following tooling required for the fabrication of the solar cells and the modules has been completed and checked out: (1) AR tooling which utilizes high power magnets to shield the center contact from coating material which impairs solderability of the cell, (2) a back contact soldering machine which solders 120 cells into a series-parallel connected cell assembly, (3) vacuum pick up, and (4) test fixtures. All components for the modules are in house.

It was established in the last PIM that textured P /N cell can yield 1 % efficiency higher than those of polished surface. All cells reported today will have textured surface.

The objective of developing 3" diameter, P /N solar cells with an average efficiency of 16.596 was more difficult than expected. With the best processing sequence available, 1,112 cells were fabricated. The average efficiency of these cells is 13.596. Six modules are being processed each with projected output of 78 watts.

Twenty-five (25) P/N reference cells (2x2 cm2) were delivered to JPL in February, 1980. The average AMl efficiency measured at JPL was 16.2%.

Approval Signature

51

3-10-ao Date

PRODUCTION PROCESS AND EQUIPMENT

Applied Solar Energy Corporation City of Industry, California

Contract Title: Development of Low Cost Contact to Silicon Solar Cells

Contract No.: 955244

The goal of the contract is to test the technical feasibility and effective cost of a copper plating system for the production of low cost contacts in the manufacture of solar cells for high volume.

Nickel has been experimentally shown to be a good barrier to copper diffusion. For cost purposes we are looking at replacing the chromium bath in the previous process with an electroless nickel bath. Work is also being done on replacing the immersion palladium bath by an adherent nickel bath.

The process has been scaled to 3" diameter using the print-on resist mask technique. Line widths of less than 5 mils have been successfully produced.

s/;ol.ru I Date Approval Signature

52

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ARCO SOLAR, INC.

CHATSWORTH, CALIFORNIA

Contract Title: AUTCMATED SOLAR PANEL ASSEMBLY LINE

Contract No. : 955278

The objectives of this program are to design, develop, and demonstrate an automated solar cell module production line. Included in this program are 1) a module design compatible with automation methods, 2) a machine capable of soldering interconnects at a rate of 12 cells/ minute and 3) a lamination system capable of producing 12 laminates per hour.

The solar cell/interconnect configuration incorporates full redundancy utilizing multiple small solder connections. Ribbon and solder connection locations are identical on both the front and back surfaces of the solar cell.

The soldering machine incorporates cassette unloading and wafer align­ment, ribbon feed and deployment, simultaneous soldering of front and backside interconnects and in-line removal of soldering flux.

The lamination system is a two chamber vessel separated by a rubber diaphragm. Key features of this equipment are thin lamination capa­bility, fully automated operation, infrared heating and operation at low pressures (no autoclaving).

Two fully automated laminators have been shipped to JPL and the auto­soldering equipment is undergoing final assembly and checkout.

Howard Samberg Approval Signature rJB 3/10/g-0

53

3-10-80 Date

Contract Title:

Contract No. :

PRODUCTION PROCESS AND EQUIPMENT AREA

Bernd Ross Associates

San Diego, CA 92109

DEVELOPMENT OF ECONOMICAL IMPROVED

THICK FILM SOLAR CELL CONTACT

955164

End of contract summary. The metallurgy of the all metal ink concept was first demon­strated with the silver-lead system. Three solid materials capable of selectively etching silica at modest temperatures were identified. Best results were obtained with silver fluoride, which removed a 3000R silica layer during decompo­sition, leaving behind a metallic silver layer on the well­wetted silicon surface. A suitable low temperature ink b~nder for use in the proposed systems was obtained. Sin­tering experiments supplemented with electron micrography showed the low temperature melting metal concept to be valid (lead-silver). However the silver electrodes were charac­terized by a Schottky barrier relative to the silicon.

In the second half of the investigation of all metal screen­ed electrodes, the focus was on base metal pastes, in addi­tion to further work with the silver systems. Contact re­sistance measurements were refined. A facility allowing firing in hydrogen and other atmospheres was acquired. Several experiments involved applying screenable pastes to solar cells. Doping investigations emphasized eutectic al­loys reduced to powders. Metal systems were reviewed. A previously published vapor pressure curve for silver fluor­ide was corrected. Base metal experiments were done with nickel and copper, using lead and tin as the frit metals. Severe adhesion problems were experienced with hydrogen at­mospheres in all metal systems. A two step firing schedule was devised based upon experimentation which gave evidence that the silver fluoride-silicon dioxide reaction was modi­fied by the presence of hydrogen. Nitrogen prefiring allow­ed the silver fluoride dissociation and oxide removal with­out causing catastrophic oxidation of the base metal pow­ders. The subsequent hydrogen firing step reduced oxides that had formed and gave the proper sintered structure. Electrodes were coherent, adherent and solderable in both

nickel-lead and copper-lead systems. Aluminum-silicon and~ aluminum-germanium eutectic doping additions to copper pastes were tried on 2 1/4" diameter solar cell back con­tacts, both with good results (n = 9.4% AMl uncoated).

3-8-1980 Appr~val Signature Date

54

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PRODUCTION PROCESS AND EQUIPMENT AREA

KULICKE AND SOFFA INDUSTRIES, INC.

HORSHAM, PA., 19044

Contract Title: Automated Solar Module Assembly Line

Contract No.: 955287

The machine which Kulicke and Soffa is to deliver under this contract is a cell stringing and string applique machine which will be flexible in design, capable of handling a variety of cells and assembling strings of cells which can then be placed in a matrix up to 2' X 4' in series or parallel arrangement. The target machine cycle is to be 5 seconds per cell. This machine will be primarily adapted to 3 inch diameter round cells with one or two tabs between cells. The design of the machine will be flexible so that it can be modified to handle other cell sizes. Pulsed heat will be used as the bond technique for solar cell inter­connects.

The first half of the machine (from cassette unload through cell orient, flux application and first interconnect) uo to transfer to the Rtrin3 conveyor has been assembled, as well as its microprocessor controls. It is going through debugging stage prior to final machine performance test­ing.

The second half of the machine (from transfer to string conveyor through to vacuum transfer to module array) is in process of being assembled as parts are received from vendors.

A lamp simulator has been used to test bonded solar cells to determine if the bonding operation had any degrading effect on the cell. I-V pro­file curves taken of these sample cells, before and after the bonding operation indicate no apparent effect on the electrical characteristics of the solar cell by the bonding operation.

Max Bycer 14 February 1980

55

PRODUCTION PROCESS AND EQUIPMENT

Lockheed Missiles and Space Co., Inc. Sunnyvale, CA.

Contract Title: EVALUATION OF LASER ANNEALING FOR SOLAR CELL

JUNCTION FORMATION

Contract No.: DOE/JPL-955696

This contract is just now getting underway and has an effectivity date of 3 March 1980. It will address pulsed laser annealing of phosphorus implanted 3-inch diameter CZ silicon wafers. The main thrust of the program is to carry the pulsed laser annealing technology beyond the small "scriber" type lasers in common use today, to one with the potential of delivering large beam spot sizes, ultimately 3-inches diameter and larger.

For this contract a Q switched Nd:Glass Laser capable of greater than 30 joules output, recently acquired by Lockheed, will be used. The laser is equipped with a second harmonic generator (SHG) feature, thus yielding capability for both 1064 and 532 nm wavelength operation. The pulse width of the system is 20-50 ns and has a beam spot size of greater than 25 mm diameter· with external optics in the energy density of interest, 2 to 4 J/em.2.

M. Lopez/J. S. Katzeff 3-4-80 Approval Signature Date

56

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Contract Title:

Contract No.:

PRODUCTION PROCESS AND EQUIPMENT

MB ASSOCIATES

San Ramon, CA 94583

Automated Cell Placement and Interconnection Using an Industrial Robot

954882

The scope of work under this contract involves the analysis and develop­ment of techniques for automating the placement and interconnection of solar cells. The diversity of solar cell shapes, sizes and metalliza­tion patterns requires a versatile interconnection system, unless or until an optimum, industry-wide standard emerges. Progrannnable auto­mation provides thi.s versatility in an off-the-shelf form.

A prototype system has been built which will interconnect solar cells in any array configuration up to l'x4'. The system is centered around a Unimate 2000B industrial robot which gives us the versatility and re­liability of a well proven design. Our method incorporates a robot end effector which combines an induction heating coil and a compliant vacuum pickup. The vacuum pickup has been used with nearly zero breakage rate and will pick up broken, partial and off-center cells with equal ease. The encapsulated induction heating coil heats the entire cell hence will reflow all four full length leads front and back simultaneously. Bond time is about 7-10 seconds.

This scheme of robot operation requires that it interface with a "smart" preparation station. This station accepts standard H bar cassettes of randomly oriented cells, unloads the cells, rotates them to the orien­tation the robot is expecting, applies the proper amount of solder paste in the correct place, measures and cuts lengths of interconnect lead, places a stress-relief crimp in the correct place in the leads and does it all with a cycle time less than or equal to that of the robot. The robot then picks up this fully prepared cell, begins heating it while "in transit", and places the hot cell on top of the exposed, solder­coated leads from the previous cell completing the connection. A small micro computer is used to synchronize all of this activity.

The preparation station is essentially the same as presented at the pre­vious PIM last December. Operational testing, however, pointed to areas where some modifications were necessary. These have been made and are mostly in the area of the solder paste dispensing •

7 !VJ a rel, 90 Date

57

Contract Title:

Contract No.:

PRODUCTION PROCESS AND EQUIPMENT AREA

MOTOROLA INC., SEMICONDUCTOR GROUP

PHOENIX, ARIZONA

PHASE 2 OF THE AUTOMATED ARRAY ASSEMBLY TASK OF THE

LOW-COST SILICON SOLAR-ARRAY PROJECT

954847

Summary of Progress for Period of November, 1979 through February, 1980.

This portion of the contract is concerned with specification of process control parameters and limits which will allow progress toward automation of the process sequence. The main objective of this contract is sufficient process control limit definition to permit advanced equipment prototypes to be designed for incorporation into an advance pilot line facility.

Motorola is developing a process sequence which is capable of utilizing both sliced ingot wafers or directly grown sheet. The sequence incorporates texture etching, ion implantation, LPCVD silicon nitride (for an antireflection coating, surface passivation, and as a plating mask), mechanically masked plasma patterning of the nitride, and plated metallization.

The dimensions of the openings in the mask used for the plasma patterning of silicon nitride are the only apparent limitation on the linewidths which can be patterned. Several methods for manufacturing durable metal masks have been investigated. One very promising technique is currently being developed. This technique uses a combination of ehemical·etching and laser. scribing.

Non-mass-analyzed ion implantation studies have continued. Excellent three inch diameter solar cells have been fabricated using high beam current phosphorus implants.

Reliability of solar cell metallization is a continuing concern for operational modules. In developing the nickel-copper metallization system, it has been considered desirable to form a passivating layer· for the copper conductor. Experiments have now shown that both tin and nickel can readily be plated onto the copper layer. Both have environmental stability. and both are solderable. Use of either layer should enhance operational life-of the cells and ease encapsulation requirements.

March 2 ]980 ;

Approval Signature Date

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MOTOROLA INC., SEMIGONDUCTOR GROUP

PHOENIX, ARIZONA

Contract Title: THE DEVELOPMENT OF A METHOD OF PRODUCING ETCH RESISTANT WAX PATTERNS ON SOLAR CELLS

Contract No. : 955324

Summary of Progress for Period of December I, 1979 to March 1, 1980.

This project is performed to determine the feasibility of using recover­able wax for producing etch resistant images on silicon wafers during processing. The image production is achieved by using a letterpress printing technique as an alternative to conventional photoresist processes.

The use of wax-solvent solutions has been adopted in place of molten wax. The use of room temperature wax solutions allows printing plates to be fabricated from a wider range of materials than is possible with plates that must withstand heat. A number of different solvents have been evaluated for use with Apiezon Wand Multiwax 195 M, and it appears that perchloroethylene and mineral spirits, respectively, offer the required slow drying, effective solvent character desired.

Trials of different printing plate configuration continue. Experiments indicate that cylindrical plates have potential for faster processing of wafers and that a cylindrical shape produces images of higher quality than flat plates, particularly in cases where wafers have poor flatness.

Approval Signature

59

March 7; 1980

Date

PRODUCTION PROCESS AND EQUIPMENT AREA

MOTOROLA INC., SEMICONDUCTOR GROUP

PHOENIX, ARIZONA

Contract Title: THE ESTABLISHMENT OF A PRODUCTION-READY MANUFACTURING

PROCESS UTILIZING THIN SILICON SUBSTRATES FOR SOLAR CELLS

Contract No. : 955328

Summary of Progress for period of December 1979 to March 1980 .

This program calls for investigation, development, and characterization of methods to es t ablish a production- ready manuf acturing process which utilizes thin s ilicon substrates for solar ce l ls . These thin substrates are prepared by sawing directly to thicknesses of 8 mils and 5 mils.

A pilot line process using ion implanted phosphorus and boron layers has been speci fied . ~

Saw damage removal s tudies have confirmed that e t ching 0 .0005 inch of silicon from each side of a wire- sawed wafer is sufficient to guarantee the abs ence of saw damage.

Pilot production l ot s have been prepared and are in process. Over 400 wafers are being run and are scheduled to be complet ed in April.

3-7-80

Approval Signature Date

60

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PHOTOWATT INTERNATIONAL, INC., {SENSOR TECHNOLOGY, INC.)

CHATSWORTH, CA 91311

Contract Title: PHASE 2 ARRAY AUTOMATED ASSEMBLY TASK

Contract No. : 954865

Date: November 1, 1979 to March 7, 1980

Several microwave systems for use in solar cell fabrication were developed and experimentally tested during this report­ing period. The first system used a rectangular waveguide horn applicator with the silicon wafers perpendicular to the direction of wave propagation. Satisfactory results were achieved with this system when it was tested for impedance matching and wafer surface heating uniformity at the manufacturer's plant. The microwave system was recently delivered. Spray-on dopant junction formation drive-in experiments and metal sintering experiments will follow installation.

A second microwave system was studied that uses a circular waveguide operating in a cross-polarized and circular polarized TE11 mode exciting a conical horn with the silicon wafer perpendicular to the direction of wave pro­pagation. This system has the potential for producing good wafer surface heating uniformity. A fixture for holding the silicon wafers and a technique for controlling the depth of wafer heating are being investigated.

The aluminum spray-on metallization chamber was installed and a complete overhaul of the existing spray-on dopant and A.R. coating system was performed. Initial tests indicate that the system performance is good. Spray-on experiments are planned for coordination with the micro­wave system •

61

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PRODUCTION PROCESSES AND EQUIPMENT

PHOTOWATT INTERNATIONAL INC., {SENSOR TECHNOLOGY, INC.)

CHATSWORTH, CA 91311

Contract Title: DEVELOPMENT OF LOW-COST POLYSILICON SOLAR CELLS

Contract No.: 955265

Date: November 1, 1979 to March 7, 1980

Processes were explored for the purpose of improving the polysilicon solar cell efficiencies. Several metalliza­tion techniques were examined for suitability with the spray-on dopant junction formation process sequence, one that has produced good solar cells earlier in this program. A metallization problem was encountered this quarter with cause and solution yet to be resolved. To check probable contamination, the spray-on dopant equipment was over­hauled and cleaned.

An equation was derived to compute the functional power loss associated with insufficient gridline coverage of polysilicon crystal grains. The fractional power loss was computed to be 0.77% for the Wacker polysilicon solar cells with 0.16 inch average crystal grain size and using a gridline spacing of 0.125 inches and a width of 0.010 inches. The calculations also showed that fractional power loss is a factor to consider for gridline spacing optimization.

JJ.-~ ~ ·-- . ~lignature

62

March 7, 1980 Date

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PRODUCTION PROCESS & EQUIPMENT DEVELOPMENT (TASK 4)

Contract Title:

Contract No. :

RCA Laboratories

Princeton, New Jersey 08540

AUTOMATED ARRAY ASSEMBLY, PHASE II

DOE/JPL-954868

1 Dec 1979 - 10 March 1980

During this period, our phase II work was completed. Previously identified material and process compatibility problems have required that an alternative to ion implantation for junction formation be explored. Therefore, development was continued, and this work has provided a manufacturing sequence which utilizes sliced solar-grade wafers with diffused junctions, plasma etched edge definition, screen printed contacts, and spray-on AR coating. The~e processes were found to be internally compatible and suitable for use with the low-cost solar-grade wafers. Solar cells with 13% AM-1 efficiency can be readily made with this process.

Work was also continued on a solder reflow process for cell interconnection and string/array assembly. Panel assembly by the lamination of a glass/ PVB/glass structure was assessed, and while found to be technically feasible, the yield and cost of this process is now considered questionable.

At this PIM, the results of our experimental production studies combined with cost analyses will be reviewed and reconnnendations will be made regarding the cost/performance effectiveness of the selected process sequence •

~ ~ dJdui~ R.V. D'Aiello

Approval Signature

63

March Z, J 9SQ Date

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Contract Title: Development of Megasonic Cleaning of Silicon Wafers

Contract No. : 955342

The purpose of this work is to develop and demonstrate a continuous megasonic cleaning process with a throughput not less than 2500 wafers/hour in preparation for the large scale production of flat-panel silicon solar cell arrays. During this reporting period the cleaning and drying system were fully tested for functionality and rate. In the laboratory the design goals have been achieved. The following performance has been demonstrated: 1. With carriers having 3/32" spacing between wafers the demonstrated cleaning rate is 4500 wafers/hour. 2. As determined by the laser scanning method, the 160 W per transducer available from the commercial unit is adequate to remove particulate contaminants to a small background level. 3. Cold air drying of wafers in the quartz carriers used for annealing and diffusion is practical at speeds of 3300 wafers per hour with 3/32" spaced wafer carriers. 4. The laboratory tests indicate that continuous filtration permits the cleaning solution to be used for at least a two week period with only daily make-up of hydrogen peroxide and annnonia solution. 5. The solar cells made via megasonic cleaning compared with those made by "Z" cleaning showed a higher average efficiency, mainly because the "low-efficiency" cells normally encountered were almost eliminated. 6. The silicon wafer laser scanner is an excellent diagnostic tool and is recommended for process control on a sampling basis. Polished reference wafers can be recycled. The patterns of residual particles displayed on the storage scope screen allow an operator to diagnose sources of contamination such as rinse water quality or dust, as well as damage caused by improper wafer handling. 7. Operating instructions for factory operation of the megasonic cleaning system have been written.

A. Mayer 0. i/1~ Approval Sig~

64

10 March J980 Date

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Solarex Corporation

Rockville, Maryland

Contract Title: Phase II of the Array Automated Assembly Task for the

Low Cost Silicon Solar Array Project

Contract No. : 954854

This program focuses attention on one key step of a low cost process for mass production of inexpensive solar cells: the metallization step. It comprises several experimental tasks involving studies of electroless nickel contacts and culminates in a direct comparison of the Solarex and Motorola metallization processes which use electroless nickel and solder ~etallization.

In one task, environmental stress tests were conducted on solar cells having nickel-solder contacts. No accelerated stress regimen has been demonstrated to be a reliable predictor of solar cell lifetime behav­ior, but four stress tests were selected which were expected to be relatively demanding on the integrity of the silicon-metal bond.

The cells performed perfectly for 1,000 hours at s5oc, 85% relative humidity under 0.45 volt forward bias, but did not do well at 15QOC for 1,000 hours, and temperature cycle and shock tests between -650C and +150°C were also too severe. At least two different failure mechanisms were operating in these tests, as evidenced by different modes of failure prevailing with different kinds of stresses, and this implies that at least some of these tests ·are not valid as accelerated life tests, because•an accelerated life test procedure, to be valid, must not alter the failure mechanism.

In a second task, experiments directed at assessing the quality of electroless nickel plates on oxidized silicon surfaces have demon­strated conclusively that the plating solution dissolves most of the oxide before plating any nickel.

In a third task, electrical measurements (light I-V and dark reverse 1-V) were made on cells which had been plated for different lengths of time in an effort to detect any deleterious effects to the cells which might be caused by exposure to the plating solution. No such effects have yet been detected, but it was observed, as expected, that contact quality varied with plating time, the best contacts being ob­tained with an intermediate range of plating times.

~ c.r?.~ Approval Signature Date

65

PRODUCTION PROCESS AND EQUIPMENT

Spectrolab, Inc.

Sylmar, CA

Contract Title: Array Automated Task Solar Cell and Module Process Sequence

Contract No. : 954853

The objective of this effort· is to develop, optimize, and demonstrate the feasibility of a process sequence for low-cost fabrication of solar cells and solar cell modules.

Evaluation of the improvement of cell performance by sulfur hexaflouride (SF6) plasma etching the front surface has shown a peak performance increase of approximately twelve percent after a sixty second etch. Investigations indicate that reduced junction depth effects partially explain observed increases. Spectral response measurements indicate other mechanisms may be involved.

The capability of junction isolation by laser scribing the front sur­face of finished, non-AR coated solar cells was demonstrated. It was determined that high laser power output levels and a low Q-factor are necessary to produce a clean continuous groove. Non-AR coated cell efficiency as high as 10.4% was achieved at a laser output level of 7 watts/cm2 and a Q-factor of 3000 pulses/inch. All work was done in the TEMoo laser resonator mode.

Efforts have continued in developing a process to laminate 2'x4' modules using EVA. There is still a tendency to trap bubbles in the central portion of the module. The best results have been obtained using .005" Craneglass 250 (a non woven glass web) at various places in the layup. Slight problems with bubble entrapment are not seen as a problem since a double vacuum bag technique is now being used and will be replaced with a true double vacuum chamber in any future production. Out present layup scheme consists of primed .glass, clear EVA, circuit, Craneglass, white EVA, Craneglass, and Al foil in that order. The back layer of Aluminum foil has added to increase relia-· bility by minimizing failures from moisture penetration.

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Spectrolab, In~.

Sylmar, CA

Contract Title: High Resolution, Low-Cost Solar Cell Contact Development

Contract No.: 955298

The objective of this effort is to demonstrate the feasibility of form­ing solar cell collector grid contacts by the MIDFILM R process. This is a proprietary process developed by the Ferro Corporation, a sub­contractor for the program.

The MIDFILM process attains a line resolution characteristic comparable to photoresist methods with a process related to screen printing. The surface to be processed is first coated with a thin layer of photo­resist material. Upon exposure to ultraviolet light through a suitable mask, the resist in the non-pattern areas remains tacky. The conductor material is applied in the form of a dry mixture of metal and frit particles which adhere to the tacky pattern area. The assemblage is then fired to ash the photo-polymer and sinter the fritted conductor powder. ·

Feasibility of the MIDFILM process as a low-cost means of applying solar cell collector metallization was demonstrated during this contract. Cell efficiencies of above 14% (AMl, 280C) were achieved with fritted silver metallization. Environmental tests suggest that the metallization is slightly humidity sensitive and degradation is observed on cells with high series resistance. The major yield loss in the fabrication of cells was due to discontinuous grid lines, resulting in high series resistance. Standard lead-tin solder plated interconnections do not appear compatible with the MIDFILM contact.

Copper, nickel and molybdenum base powder were investigated as low-cost metallization systems. The copper based powder degraded the cell re­sponse. The nickel and molybdenum base powders oxidized when sintered in the oxidizing atmosphere necessary to ash the photoresin.

7hi/~( Approval Signature Date

67

PRODUCTION PROCESS & EQUIPMENT DEVELOPMENT (TASK 4)

Spire Corporation Bedford, Massachusetts 01730

Contract Title: DEVELOPMENT AND FABRICATON OF A SOLAR CELL JUNCTION PROCESSING SYSTEM

Contract No.: DOE/JPL 955640

10 January - 7 March 1980

The objectives of this program are to design, develop, construct and demonstrate a 10 MW per year junction formation system utilizing a high throughput, continuous feed ion implanter followed by a pulse electron beam annealer both connected by a common wafer interlock and vacuum transport system. The system will be able to implant and anneal approximately 100 cm2 wafers. The ion implanter will be dedicated to provide P31 + ions at 16 milliamps total, 10 keV, in a rectangular beam 10 cm x 1 cm which is swept across the wafer orthogonal to the wafer feed direction. The pulsed annealer· will deliver up to 2 joules/cm2 of a 15 kilovolt mean energy electron beam with a pulse duration of approximately 100 nanoseconds. Wafer throughput ~hrough both units of the system will be up to one wafer every two seconds.

In the first two months of the program, experiments involving both solid and liquid phase epitaxial regrowth of ion implant damage were investigated to determine the quality of cells developed. In addition, concepts using multiple overlapping spots of small area electron beams to cover the complete wafer area were investigated. These results showed that the most efficient and most economical method is to use liquid epitaxial regrowth using a sing~e shot per wafer of a large, 100 cm2 electron beam.

Tradeoff studies have presently determined the optimum ranges for the energy store, the inductance of the transmission line, and the charging voltage to be used in the pulser. These values are presently 40 nanofarads capacitance, 100 nanohenries inductance, and 300 kilovolts maximum charging voltage.

The present design layout of the pulser consists of a N2/C02 pressure tank containing 19 coaxial capacitors which are fed into the process chamber through a low inductance coaxial transmission line. The electron beam emission diode is contained within a magnetic guide field to both prevent the beam from pinching and to guide the beam onto the wafer. The cathode area, anode-cathode gap, and beam drift parameters are being designed with sufficent flexability so that the optimum conditions can be. found emperically during wafer annealing experiments.

Present status of the program is that the preliminary design iayouts have been completed. All critical physics inputs have been completed and we are now proceeding into detailed design of each subsystem. However, detailed design has been completed on the coaxial capacitors and their containment tank. These parts are now ready to be procured. Activities for the next few months will include completion of all detailed design and the testing of the prototype coaxial capacitor.

U/~· ,.horized Signature

J/7180 Date

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PRODUCTION PROCESS AND EQUIPMENT AREA University of Pennsylvania

Philadelphia, PA

Contract Title: Analysis and Evaluation of Processes and Equipment

Contract No.: JPL-954796

The setting of an LSA 1986 goal 260 -soLAR cELL vALuE --MODULE VJ.LUE

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between module (or cell) value { ~o and module efficiency. As the '

~ f60 pivot point for this relation-ship serves the $0.683/W(peak) ~ 140 LSA goal for 14% efficient c · modules (circles in figure). ~ 120

These curves provide a useful .:> aoo tool for fast, preliminary ·ffi comparisons of the cost effect-~ iveness of competing process 3 60

options which result in differ- i ent efficiencies, assuming 40

equal yield. This has been found particularly helpful in

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differences in the resistance of the metal layers and in the front contact area coverage, with consequent efficiency impacts, can be readily determined. The data collected so far on metallization seem to indicate that the costs of the various processes for metal depos­ition, including pattern definition, do not vary by more than a factor of two up or down, after the metal costs have been substracted. How­ever, the processes have different capabilities with respect to grid line width and metal layer sheet resistance which lead to differing efficiencies. The impact of these efficiency differences on the cell value is of the same magnitude as the process price differences. This places an important constraint on the metallization process selection. In addition, the use of noble metals, except perhaps in trace amounts, is clearly to be excluded from consideration for cost-effectivecontact systems. Since the contact resistance between the metal and the semi­conductor makes a significant contribution to the total series resist­ance, the metal-semiconductor contact theories are being examined to determine what predictions can be made from this viewpoint with respect to metal and process selection.

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69

PRODUCTION PROCESS AND EQUIPMENT

Westinghouse Electric Corporation

Pittsburgh, PA 15235

Contract Title: PHASE 2 OF THE ARRAY AUTOMATED ASSEMBLY TASK

FOR THE LOW COST SOLAR ARRAY PROJECT

Contract No. : 9 548 73

The objectives of this contract were to specify a process sequence for the fabrication of solar modules from dendritic web silicon, and to further develop key process steps within the process sequence. The cost goal of the program was that all module fabrication step costs selected, including the input dendritic web silicon (at $0.24/peak watt-1980$) should permit a selling price of $0.70/peak watt (1980 $).

The process sequence defined was as follows:

o Pre-diffusion cleaning of p-type Base o POC1

3 Diffusion for n+ p n+ Structure

o Back Surface Field Formation for n+ pp+ Structure o Deposition of Antireflection Coating o Deposition of Photoresist Layer o Grid Delineation (Mask-Expose-Develop-Etch) o Metallization o Reject ion of Exe ess Metal o Electroplate Conductive Grid o Cell Separation o Test o Interconnection o Encapsulation

Since dendritic web is most easily (and economically) processed in long lengths, several process steps in the process sequence were developed specifically for this type of processing.

We have developed process specifications for this process sequence and determined the limits of controls required for each step.

During the course of the program, several changes were made in the sequence, one of which was the substitution of an Al BSF for a boron diffused BSF. The rationale for these changes will be discussed.

A cost analysis using SAMICS methodology has been carried out on the sequence, and these data indicate that in a high volume, automated manufacturing setting, the cost goals should be realizable. In addition several sensitivity analyses have been carried out to show the effect on the overall cost of capital expenditures, module efficiency, dendritic web width, and process yield.

Date

70

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PRODUCTION PROCESS AND EQUIPMENT

JET PROPULSION LABORATORY

PASADENA, CALIFORNIA

NON-MASS ANALYZED ION IMPLANTATION

The present design hollow cathode Freeman ion source is functional but still has some problems. The most serious problem is the fact that the hollow cathode has shown considerable erosion in a short period of time. The cathode erosion is thought to be caused by exposure to the high energy ions coming from the main discharge. Thus the present work on the Freeman source has been divided into two parts. The present source is being retrofitted with a phosphorous vaporizer to perform ion implantations and a second ion source is being used to test design changes. Documented design improvements will then be incorporated into the phosphorous ion source.

An EXB mass analyzer was designed and fabricated to sample the ion beam during ion implantation. The analyzer will be used to determine the fraction of beam current which is dopant material; i.e., phosphorous. The total ion beam current received by the implanted sample is integrated and multiplied by the dopant fraction to calculate the total dose. The current integrator has been bench tested, successfully. The EXB analyzer test should be done within the week. With the analyzer complete, all of the necessary components are ready for performing ion implants. It is anticipated that a solid phosphorous implant will be performed within two weeks.

Dennis Fitzgerald .:z) ~ 3/10/80

Approval Signature Date

71

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ENGINEERING AREA, BURT HILL KOSAR RITTELMANN ASSOCIATES

BUTLER, PENNSYLVANIA

Contract Title: Operation and Maintenance Cost Data for Residential

Photovoltaic Modules/Panels

Contract No. : 955614

From October 1979 to March, 1980

The objective of this study was to identify and estimate costs associated with the operation and maintenance of residential photovoltaic modules and arrays. The approach used in accomplishing this objective was to identify the potential problems associated with photovoltaic modules and arrays; identify and describe the correct procedures related to these problems; identify and estimate costs to perform the corrective procedures; identify the cost drivers relative to the specified O amd M procedures; and to recommend, where possible, potential techniques and procedures for the reduction of operation and maintenance procedures.

There are six basic topics pertaining to the operation and maintenance of photovoltaic arrays which were investigated in this study. These tasks include:

General (normal) maintenance Cleaning Panel replacement Gasket repair/replacement Wiring repair/replacement Termination repair/replacement

Reviewing the general characteristics of residential maintenance, it becomes readily apparent that the typical homeowner is not likely to perform but the simplest of maintenance procedures on a photovoltaic array. This implies the use of professional maintenance personnel, thus increasing the life cycle cost of photovoltaic systems.

The results of this study indicate that all components of the photo­voltaic module and array must be designed to be maintenance free and long-lived. In order to accomplish this, care must be taken in the choice of materials, and a design optimization must include a detailed evaluation of the need for and the associated costs of maintenance. Also, photovoltaic module manufacturers must develop maintenance procedures, safety procedures, and maintenance schedules which will be incorporated in a detailed operation and maintenance manual.

The final report is anticipated to be available in May, 1980.

c/L.. £ 0 ~-(), ~ Approval Signature I

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Date

73

Contract Tit I e :

Contract No. :

ENGINEERING AREA

Clemson University

Clemson, SC 29631

INVESTIGATION OF RELIABILITY ATTRIBUTES AND ACCELERATED

STRESS FACTORS ON TERRESTRIAL SOLAR CELLS

954929

The objective of this study is to develop test methods for eval­uation of solar cells, perform investigations of factors involved in the reliability of terrestrial solar cells and develop specifications for the accelerated stress testing of solar cells. The overall pro­gram approach involves determining the reliability characteristics of currently available corranercial cells by accelerated stress testing. The third year's effort also entials studying methods of second-qua­drant characterization, and some preliminary experimental work on second-quadrant effects.

A cell reliability test facility was established and jigs have been designed and constructed for electrical measurement and stress testing of a total of seven cell types to date. The capability for reproducible measurements o.f Isc, V0 c, Im, Vm, FF, Rs, Rsh has been demonstrated, although that capability is reduced considerably for non-planar cells which have been encountered in the study. Stress test equipment is in place and operational for temperature-voltage (T-V) stress, temperature-humidity-bias under pressure (T-H-B) stress, pulsed power-temperature stress, temperature-voltage-humidity (85°C-85RH and 121°C/15 Psig steam), and thermal cycle/thermal shock.

Long term (~9000 hours) B-T stressing of the four original cell types (A,B,C,&E) indicates that two types (B,C) continue to show lit­tle degradation while one type (A) continues to show large degreda­tion in line with earlier results. The final type (E) which had shown no degradation at 2000 hours showed appreciable degradation at 9000 hours. In addition, E type cells showed appreciable photon de­gradation behavior after 9000 hours.·

Medium term stressing of three advanced cell types showed varying amounts of degradation. Thermal cycle/thermal shock tests indicate that EFG cells are more susceptible to breakage (shattering) than other cell types.

Second quadrant measurements have confirmed the thermal nature of breakdown and it appears that cells with low breakdown will be more unreliable than those with higher breakdown. The phenomenon of second quadrant operation is being studied using an IR scanner.

Date

74

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ENGINEERING .AREA

DSET LABORATORIES, INC. PHOENIX, ARIZONA

Contract Tit le : SUNLIGHT AGING TESTS OF SOLAR CELL M)DULES

Contract No. : BQ-713131

The accelerated aging of mini-modules was continued using DSET's Super-Maq® Fresnel-concentrating accelerated weathering machine. Through February 29, 1980, the two Block II modules have been sub­jected to 2,075,950 langleys of radiation, and the six Block III modules have been subjected to 658,090 langleys of radiation. lhe Block II and Block III modules have been exposed to an equivalent of 11yearsand31/2 years, respectively, of outdoor weathering in an "average" southwestern environment.

Weekly visual inspections, monthly 35nm slide photos, and monthly I-Vmeasurements are used in monitoring the physical and electrical characteristics of the modules. Failure modes such as cell cracking, delamination, carbonation, and contact corrosion, as well as max power losses, non-ohmic contact, and series resistance changes have been observed during the Super-Maq® exposure program. In some cases, early detection of such failures has accurately predicted similar field failures in block series modules employed in IX)E demonstration programs.

Future work includes the real-time exposure testing of block series modules at both nonnal incidence (one sun) tracking, and at a south facing fixed angle. The data developed from these tests will be used to establish a baseline comparison to modules exposed on the Super-Maq®.

75

March S, 1980

Date

Contract Title:

Contract No.:

ENGINEERING AREA

DSET LABORATORIES, INC. Phoenix, Arizona 85029

NATURAL SUNLIQ-IT SPECTRAL MEASUREMENTS

BQ-713137

Utilizing DSET Laboratories' recently completed Solar Spectroradiometer, calibration and operational procedures are being developed for data formatting employing both a Data General Nova 3D Computer (DSET's main frame) and a "transportable" Data General MicroNova M:100 for field operations. (All hardware and the rights to the design and construction are the property of DSET Laboratories.) The computer programs required to interface the 16-bit BCD output of the radiometer with the two com­puters are being developed under the auspices of this contract so as to be compatible with JPL data acquisition capabilities. The spectro­radiometer is based on the following components : (1) source optics com­prising a 6-in integrating sphere and a detachable/coupled pyrheliometer with 6° field of view, (2) a double quartz prism high resolution mono­chromator manufactured by Carl Leiss (Berlin), a Princeton .Applied Research synchronous motor-chopper assembly and a PAR 1-,bdel 286 Synchro­Het(erodyne) phase-locked amplifier, (3) thermoelectrically cooled lead sulfide infrared and UV-enhanced silicon photodiode UV-VIS detectors,and (4) associated calibration and control eql:lipment .

Current work involves completion of the writing of the calibration pro­cedures and the computer software package for (1) the spectn.un of the NBS-calibrated standard of irradiance (lamp), (2) the file information on the calibration constant of the radiometer for each of 400 wavelength settings from 290- to 2500nm, and (3) completion of the ''write" programs for digital plotting of solar spectra. The trivial work of writing the programs has been completed: Debugging and documentation have not yet begun. The analog-to-digital electronics package has been modified for acquisition of the raw spectral data.

When operational, the completed package is capable of making complete wavelength continuous solar spectral measurements in the above region for both the direct beam and global conditions--the latter at any angle of tilt from horizontal and 0° horizontal. In the meantime, hand calibrated spectral data have been produced for AM 1.05. These curves, along with high resolution ultraviolet spectra, showing the fundamental Fratmhofer : absorptions in the sun, are appended.

The spectroradiometer will be employed to measure both the direct beam and global spectrun all day on approximately the 15th of each month for two years, and all day for a complete week at each of the two annual solstices and two annual equinoxes.

76

February 28, 1980 Dote

Contract Title:

Contract No. :

ENGINEERING AREA

IIT Research Institute

Chicago, Ill.

TECHNICAL SUPPORT IN RELIABILITY ENGINEERING OF PHOTOVOLTAIC MODULES/ARRAYS

955720

The objective of this technical support effort is to develop useful, engineering-oriented reliability data on LSA module designs. The approach being used includes indepth follow-up analyses of data taken from LSA Problem/Failure Reports (P/FRs), test results and Engineering Area studies. Deliverables which will result from this support effort include determination of failure rates by different module designs and by (a) field applications, (b) environments encountered, (c) failure modes, etc.

In parallel with that effort there is a program to develop "strawman" reliability models for two alternative module designs. These "straw­man" reliability models will be used to establish reliability alloca­tions/apportionments for module components and to support reliability engineering, and design activities within the Engineering Area.

A unique adjunct to this effort is the provision made that allows LSA to utilize component failure rate data that may be deemed useful from the Reliability Analysis Center of Rome Air Development Center, Rome, New York (operated for the Air Force by IITRI).

P. A. M ihalkanin/R. T. Anderson

Approval Signature

77

March 7," 1980

Date

In-House Program

Array Design/Engineering

ENGINEERING AREA

JPL

Pasadena, CA

Principal in-house work in the module/array circuit design and analysis task within this activity concentrated on application of series/paral­lel analysis to the problem of multi-cell failures for intermediate load applications and on development of design guidelines for fault and "hot-spot" tolerant circuit designs. Life cycle costing methodology was employed as part of the performance assessment of various series/ parallel design approaches and provided important inputs to a paper presented at the 14th IEEE PV Specialists Conference, "Circuit Design Considerations for PV Modules and Systems." Preparations for the Module/Array Circuit Design Workshop scheduled March 31-April 1, imme­diately preceding this meeting, have continued through this reporting period.

Work continued on design, fabrication, and proof testing of low cost array support structures and foundations for Intermediate Load and Utility applications. Full size 8' x 16' panels were fabricated and successfully tested to 50 psf. An integrated, low cost soil-buried foundation/array structure was designed and fabricated and will be on display with a full complement of simulated 4 x 4 and 4 x 8 modules at this Project Integration Meeting.

Reliability/Durability

High voltage continuous stress testing of mini-modules has continued at JPL Field Site No. 1 with periodic performance measurements and in­spections being conducted. An analytical investigation of long term voltage stress related degradation factors for various encapsulation systems has been initiated. The effects of high voltage phenomena, including arc generated corona excitation and voltage gradient concen­trations, are being evaluated both analytically and empirically. Generation of improved high voltage design guidelines for the higher operating voltages expected in PV utility applications is the goal of this effort.

Work continued on the Phase II module soiling investigations. Efforts centered on comparing the differences between the relative normal hemispherical transmittance (RNHT) and the integrated hemispherical transmittance (measured at Battelle Pacific Northwest Laboratories). The values measured at Battelle show, in most cases, a greater loss in hemispherical transmittance than previously thought. Additional mea­surements are under way to resolve these discrepancies.

Date

78

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ENGINEERING AREA

IIT Research Institute

Chicago, Ill.

Contract Title: TECHNICAL SUPPORT IN RELIABILITY ENGINEERING OF PHOTOVOLTAIC MODULES/ARRAYS

Contract No. : 955720

The objective of this technical support effort is to develop useful, engineering-oriented reliability data on LSA module designs. The approach being used includes indepth follow-up analyses of data taken from LSA Problem/Failure Reports (P/FRs), test results and Engineering Area studies. Deliverables which will result from this support effort include determination of failure rates by different module designs and by (a) field applications, (b) environments encountered, (c) failure modes, etc.

In parallel with that effort there is a program to develop "strawman" reliability models for two alternative module designs. These "straw­man" reliability models will be used to establish reliability alloca­tions/apportionments for module components and to support reliability engineering, and design activities within the Engineering Area.

A unique adjunct to this effort is the provision made that allows LSA to utilize component failure rate data that may be deemed useful from the Reliability Analysis Center of Rome Air Development Center, Rome, New York (operated for the Air Force by !ITRI) •

P. A. M ihalkanin/R. T. Anderson

Approval Signature

77

March 7, 1980

Date

In-House Program

Array Design/Engineering

ENGINEERING AREA

JPL

Pasadena, CA

Principal in-house work in the module/array circuit design and analysis task within this activity concentrated on application of series/paral­lel analysis to the problem of multi-cell failures for intermediate load applications and on development of design guidelines for fault and "hot-spot" tolerant circuit designs. Life cycle costing methodology was employed as part of the performance assessment of various series/ parallel design approaches and provided important inputs to a paper presented at the 14th IEEE PV Specialists Conference, "Circuit Design Considerations for PV Modules and Systems." Preparations for the Module/Array Circuit Design Workshop scheduled March 31-April 1, innne­diately preceding this meeting, have continued through this reporting period.

Work continued on design, fabrication, and proof testing of low cost array support structures and foundations for Intermediate Load and Utility applications. Full size 8' x 16' panels were fabricated and successfully tested to 50 psf. An integrated, low cost soil-buried foundation/array structure was designed and fabricated and will be on display with a full complement of simulated 4 x 4 and 4 x 8 modules at this Project Integration Meeting.

Reliability/Durability

High voltage continuous stress testing of mini-modules has continued at JPL Field Site No. 1 with periodic performance measurements and in­spections being conducted. An analytical investigation of long term voltage stress related degradation factors for various encapsulation systems has been initiated. The effects of high voltage phenomena, including arc generated corona excitation and voltage gradient concen­trations, are being evaluated both analytically and empirically. Generation of improved high voltage design guidelines for the higher operating voltages expected in PV utility applications is the goal of this effort.

Work continued on the Phase II module soiling investigations. Efforts centered on comparing the differences between the relative normal hemispherical transmittance (RNHT) and the integrated hemispherical transmittance (measured at Battelle Pacific Northwest Laboratories). The values measured at Battelle show, in most cases, a greater loss in hemispherical transmittance than previously thought. Additional mea­surements are under way to resolve these discrepancies.

Date

78

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ENGINEERING AREA

JPL

Pasadena, CA

Development was initiated of a high temperature soak module accelerated environmental exposure using the "greenhouse" effect. The purpose is to provide a low cost method for manufacturers to use in checking potential long term chemical or physical degradation mechanisms in new module designs. The relative importance of UV and high temperatures in causing module degradation will be investigated. A test box accept­ing up to eight mini-modules has been fabricated and initial exposures are under way.

Standards/Specifications

The Array Subsystem Task Group delivered to SERI an updated package of criteria and test methods for the January 1980 draft of the Interim Performance Criteria Document, which was a major milestone for SERI's Performance Criteria and Test Standards Project. Engineering Area personnel participated in the review of the draft document on January 21-25, 1980. Future standards work will include: letting contract for the development of criteria test methods for optical systems and PV concentrators, combined photovoltaic/thermal standards, and further reliability/durability studies.

Preparation and release of a new module design requirement specifica­tion for use in the PP&E Phase III effort was accomplished. The LSA Document 5101-138, "1982 Technical Readiness Module Design and Test Specification-Intermediate Load Applications" dated January 15, 1980, has been released for distribution to the photovoltaic connnunity.

1 /1-z_ I vD ' ..

Approval Signature Date

79

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OPERATIONS AREA

JPL Pasadena, Ca 1 .

As of the end of February 215 kW (99%) of the Block I I I modules have been delivered.

Block IV modules have been received from Motorola, General Electric, Applied Solar Energy and Spire. The other contractors are running be­hind the planned schedules for various reasons. Quotations for the Block IV follow-on phase have been received, but contract awards are being delayed pending completion of testing associated with the design phase.

Block I II exploratory environmental testing has been completed, and Block IV environmental qualification testing has been initiated. Re­sults of these tests will be given at this Integration Meeting.

The Annual Field Test Report, 5101-141, has been issued. A portable current-voltage meter, designed and constructed in-house for in-situ module measurements, is undergoing field evaluation. This instrument, together with interfacing hardware and software, can access the data reduction and archiving capability of the mini-computer at the Pasadena Field Test Site.

No module failures have been observed at the four local field test sites since the last Integration meeting, but some scattered module degradation has been observed at the Pasadena Site, where individual module output is closely monitored.

~<rZ .. oo-! ~proval Signature

03/10/80 Date

81

LARGE SCALE PRODUCTION TASK

Applied Solar Energy Corporation City of Industry, California

Contract Title: Third Generation Design Solar Cell Module

Contract No.: 955409

The objective of this contract is to design, fabricate, acceptance test, and evaluate ten (10) pre-production modules complying with the requirments of JPL Document No. 5101-16, Revision A, entitled "Block IV Solar Cell Module Design and Test Specifications for Intermediate Load Center Applications", dated 1 November 1978, in addition, ASEC will prepare a standardized price estimate using SAMICS for 10, 100, and 1000 kilowatts of solar modules.

The total power output of the ten (10) modules shall be in excess of 900 watts at AMl.5, NOCT, and V Nn of 15 VDC. The module dimensions are 27.38" x 47 .24" (69.55 cm x no cm). Each module has 136 silicon solar cells (3.05" diameter) connected thirty-four (34) in series and four (4) in parallel. Reliability of the module has been further enhanced with the addition of a

. parallel connection across the sixth row of the cells from each end. The 3.05" diameter cell size was established in order to achieve the maximum packing, factor for this particular design 76.9, and still adhere to the JPL Envelop Dimensional Restrictions. The circular cells utilize a radial contact pattern with a central interconnection point. This contact pattern, combined with the copper mesh interconnects, results in an easily automated assembly feature for future consideration. The modules anodized aluminum frame is made of special press fit corner fasteners. The simplicity of design and assembly technique lends itself for automation.

Six (6) modules have been delivered to JPL at this time. The efficiency is, however, lower than expected under the pulsed xenon solar simulator testing. The average power of these six (6) modules was 76.4 watts at V N.O of 15 VDC and NOCT estimated at 48°c with a maximum variation of only 2.3 watts. The discrepancy in measurement between sunlight and xenon light simulation has not yet been resolved, but xenon appears to be approximately 8 to 10% lower than in natural sunlight. No other pro~lems have been encountered.

Approval Signature

82

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LARGE-SCALE PRODUCTION

General Electric Company - Space Division

Philadelphia, PA

Contract Title: Design, Fabrication, Test, Qualification and Price Analysis of 11 Third-Generation 11 Design Solar Cell Modules

Contract No. : 955401

All work effort on the subject contract has been concluded with the ex­ception of the Final Design Review which is schedu led for March 31, 1980. A total of 62 pre-production modules, with a cumulative output at Standard Operating Conditions in excess of 900 watts, has been delivered to JPL. Six of these modules were mounted on two simulated roof sections; one of which is shown in the photograph. The f irst of these roof sections was delivered to JPL for qualifica­tion testing while the other was retained by GE for the performance of a simi lar sequence of environmental exposures which included a 50 cycle thermal cycling test between the extremes of -40° and +gooc, a 7 day humidity temperature exposure, and a wind resistance test per the requirements of UL997. The change in roof section maximum power output as a result of these exposures was measured as al .4 percent de­crease, which is well within the overall illumination test accuracy .

A SAMIS/SAMICS price analysis has been performed for annual module production rates of 10,100 and l ,000 kW.

~~ ~ ~~,~et\ ( ]''-Approval Signature

83

Simulated Roof Test Article

Date

LARGE SCALE PRODUCTION TASK

MOTOROLA INC., SEMICONDUCTOR GROUP PHOENIX, ARIZONA

Contract Title: DESIGN, FABRICATION, TEST, QUALIFICATION AND PRICE ANAL-YSIS OF "THIRD GENERATION 11 DESIGN SOLAR CELL MODULES

Contract No.: 955406

Summary of Progress for Period of November 1979 through February 1980.

The objective of this contract is to design and test an advanced solar module that meets or exceeds the requirements of JPL 5101-16. Motorola's objective is also to design in a significant degree of tolerance to normal production related defects such as cells containing terminated cracks.

Efforts during the last four months have centered around the actual production and shipment of the modules. Qualification testing is nearly complete with excellent results and the final revisions of engineering, manufacturing, and Quality Control documents are being finalized in preparation for the final design review. In addition, the SAMICS/SAMIS pricing package has been completed.

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PHOTOWATT INTERNATIONAL, INC., (SENSOR TECHNOLOGY, INC.)

CHATSWORTH, CA 91311

Contract Title: THIRD GENERATION SOLAR CELL MODULE

Contract No. : 955410

Date: November 1, 1979 to March 7, 1980

During the first quarter of 1980, contract activities consisted of a re-evaluation of the earlier proposed design, and the subsequent redesign of the Block IV module. The additional design time period was made available via a long lead vendor item in the previous version. The re­designed Block IV module consists of a laminate of low iron glass/PVB/tedlar. Its electrical subassembly is made up of 72 three inch diameter solar cells. They are arranged in six parallel rows of twelve series connected cells, making the nominal electrical output (SOC) of the module 6.6 amperes at 5.0 volts. The module design also incorporates two paralleled by-pass diodes to enhance long-term power capability and limit "hot-spot" problems when the module is utilized in high voltage applications • Redundant output terminations are provided via an AMP Corporation connector design.

All piece parts documents and initial process specifica­tions are complete. The pre-production versions of CM-1 and QA-1 have been submitted to JPL for approval. A formal design review occurred in March, and initial module deliveries are scheduled for late April.

85

March 10, 1980 Date

Contract Tit I e :

Contract No. :

LARGE~SCALE PRODUCTrON

SES, Incorporated

Newark, Delaware

Exchange of Information

LK-694034

SES, Incorporated has started delivery of initial orders for photo­voltaic systems using modules containing cells made from cadmium sulfide/copper sulfide. Real time and accelerated testing have proven the product to be stable, reliable and durable.

Module efficiency ranges from 3 to 4% for commercial product.

Technical Explanations for Design & Performance Improvements

Four major changes have been made in the SES product:

• New substrate - steel alloy with improved surface finish characteristics.

• Improved process control - of high vacuum deposition, wet chemical and encapsulation processes.

• Improved grid design - provides increased transparency and conductivity with additional production cost economics.

• Different encapsulant - allows simplification of process and economics in usage of material.

The major item delaying quantity output of product is the require­ment to modify the production equipment to accommodate the above process/material changes. These changes are the result of a vigorous life testing program instituted in 1977 •.

~.z,/£6 Date

86

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LARGE-SCALE PRODUCTION

Solarex Corporation

Rockville, Maryland

Contract Title: Design, Fabrication, Test, Qualification and Price Analysis of "Third Generation" Design Solar Cell Modules

Contract No.: 955404

Solarex is building 36 modules, 18 for intermediate load center applications and 18 for residential applications • Features include:

Semicrystalline silicon as the basic cell material.

Outside envelope dimensions of 63.5 cm x 120 cm.

72 9.5 cm x 9.5 cm cells arranged in a high density pattern.

Cells which are made by a low cost manufacturing process which is amenable to high volume rates.

High reliability cell-interconnect design which allows all solder interconnections to be made from the back.

3/16" tempered Sunadex Superstrate, Ethylene Vinyl Acetate (EVA) Pottant, White Tedlar moisture barrier.

Production has begun and the first five modules of each type will be subjected to environmental tests as specified in JPL 5101-83 and 5101-16 Rev. A.

Approval Signature Date

87

LARGE-SCALE PRODUCTION

SOLAR POWER CORPORATION

Woburn, Massachusetts 01801

Contract Title: DESIGN' FABRICATION' TEST' QUALIFICATION AND PRICE ANALYSIS OF "THIRD GENERATION" DESIGN SOLAR MODULES,

Contract No.: 955403

The objectives of this program are to design, fabricate, test, qualify, and perform a price analysis on modules intended for use in the 20-500 KW range.

This 2' x 4' ultra high density module is designed to meet JPL cost goals for 1986. The 96% packing density is achieved by using rectangular cells capable of being series-paralleled entirely from the rear, and also by placing the cell string in a porcelainized mild steel substrate requiring no perimeter support. The encapsulation package is EVA with a UV s~able cover film.

When arrayed, the rear structural support will become an integral part of the array, and not necessarily contribute to the module cost. This feature is intended to promote balance of system costs _by ailowing the strength requirements to be optimized between module and support structure.

Production quantities of these modules will be delivered to JPL over the next several months.

Approval Signature

88

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LARGE~CALEPRODUCTION

Spire Corporation

Bedford, MA

Contract Title: Design, Fabrication, Test, Qualification and Price Analysis of Third Generation De.sign Solar Cell Modules

Contract No.: 955405

This contract, started on 25 May 1979, is aimed at the design of a high efficiency panel capable of delivering 50 watts at standard operating conditions. Cell efficiency goal is 15 percent. Twenty modules, designed for Intermediate Load Center Applications, will be delivered to JPL. The module will contain 152 ion implanted rectangular cells in a closely packed configuration. The cells will be encapsulated with EVA between Sunadex glass and a laminated backing of Mylar and aluminum foil. A two piece stainless steel frame will contain the encapsulated structure.

As of December 1979, development of the encapsulation equipment and processes had been completed. At this time the fabrication procedures were being proven. Concurrently prototype modules were being fabricated.

During the present period delivery of 7 modules has been completed. These are currently undergoing acceptance testing and qualification testing. The delivered modules had an average power at operating temperature of nearly 53 watts. The spread in module performance was less the 2 percent. Average module efficiency at 28°c was 12.4 percent. The remainder of the modules due under this program are now being fabricated •

~ff~~ · ApprovalSig ture

89

?)4~~ ,,yu Date

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LSA PROJECT ACTIVE CONTRACTS

NAME

SILICON MATERIAL TASK:

AEROCHEM RESEARCH LABORATORY PRINCETON NJ

AEROCHEM RESEARCH LABORATORY PRINCETON NJ

AEROSPACE CORP. LOS ANGELES CA

BAILEY, DR. DONALD L.

BATT~LLE COLUMBUS LABORATORIES COLUMBUS OH

DOW CORNING CORP. HEMLOCK HI

ENERGY MATERIALS CORP. HARVARD MA

FITZGERALD, PROF. THOMAS

HEMLOCK SEMICONDUCTOR CORP. HEMLOCK MI

LAHAR UNIVERSITY BEAUMONT TX

LAWRENCE LIVERMORE LABORATORIES LIVERMORE CA

LEVENSPIEL, PROF. OCTAVE

MIT CAMBRIDGE MA

SAH, C.T., ASSOCIATES

SAH, DR.C.T.

SOLAREX CORP. ROCKVILLE MD

SRI INTERUATIONAL MENLO PARK CA

UNION CARBIDE CORP. SISTERSVILLE WV

WESTINGHOUSE R&D CENTER PITTSBURGH PA

WESTINGHOUSE ~LECTRIG CORP. TRAFFORD PA

YAWS, PROF. CARL

START DATE

9/21/77

10/3/79

9/12/78

5/19/78

10/9/75

7 /30/76

4/17 /79

9/20/76

10/2/79

10/1/75

2/1/78

9/20/76

4/2/79

2/9/77

1/31/77

1/19/79

2/24/76

10/6/75

10/1/75

7 /29/76

1/12/78

TERMINATION CONTRACT DATE NUMBER

12/79

11/80

11/79

5/19/80

3/80

l/79

9/80

5/1/80

1/81

12/79

7/80

5/1/80

3/81

3/80

8/1/80

1/80

1/80

12/82

5/80

2/80

1/80

91

954862

955491

955201

686062

954339

954559

955269

660360

955533

954343

-8626

660359

955382

954685

660411

955307

9541171

9543311

954331

9511589

681081

TASK DESCRIPTION

Si REACTIONS MODEL

SILICON HALIDE--ALKALI METAL FLAMES

Si IMPURITY ANALYSIS

EVALUATION OF Si PROCESSES

SEMICONDUCTOR-GRADE Si PROCESS

SOLAR CELL-GRADE Si PROCESS, ARC FURNACE

GASEOUS MELT REPLENISHMENT

EVALUATION OF Si PROCESSES

SEMICONDUCTOR-GRADE Si PROCESS-­CVD FROM CHLOROSILANES

TECHNOLOGY AND ECONOMIC ANALYSIS

NEUTRON ACTIVATION ANALYSIS OF Si PROCESS DEVELOPMENT SAMPLES

EVALUATION OF Si PROCESSES

HYDROGENATION OF SiCl4

EFFECTS OF IMPUHITIES

EVALUATION OF Si PROCESSES

ErFECTS OF IMPURITIES

SOLAR CELL GRADE Si PROCESS

SEMICONDUCTOR GRADE Si PROCESS --SI LANE/SILICON

30LAR CELL GRADE Si DEFINITION

HIGH-CAPACITY ARC HEATER PRODUCTION OF Si

EVALUATION OF Si PROCESSES

NAME

LARGE-AREA SHEET TASK:

APPLIED SOLAR ENERGY CITY OF INDUSTRY CA

ARCO SOLAR, INC. CHATSWORTH CA

BATTELLE MEMORIAL INSTITUTE COLUMBUS OH

CORNELL IJNIVERSITY ITHACA NY

CRYSTAL SYSTEMS, INC. SAT.EM MA

EAGLE PICHER MIAMI OK

SNERGY MATERIAL HARVARD MA

CHARLES EVANS & ASSOCIATES SAN MATEO CA.

HONEYWELL CORP. BLOOMING NM

KAYEX CORP. ROCHESTER NY

KAYF:X CORP. ROCHESTER NY

MATERIAL RESE~RCH SALT LAKE CITY UT

MOBIL TYCO SOLAR ENERGY WALTHAM MA

MOTOROLA, INC. PHOEtHX AZ

ijORLIN INDUSTRIES, INC. CARLISLE, PA

RCA LABORATORIES. PRINCETON NJ

SILICON TECHNOLOGY CORP. OAKLAND NJ

SILTEC TECHNOLOGY CORP. MENLO PARK CA

SILTEC CORP. MENLO PARK CA

SPECTROLAB SYLMAR CA

TYLAN CORP. TORRANCE CA

UNIVERSITY OF CALIF. L.A. LOS ANGELES CA

UNIVERSITY OF CALIF. L.A. LOS ANGELES CA

ITART DATE

5/31178

3/16/79

11/27179

3/1/78

11/20175

9/29/79

5/8/79

5/7 /79

10/21/75

9/21/77

3/12/79

2/281 J

10/29175

2/4/76

1/3/80

9/30177

12/5/78

12/5/78

1/24/77

8/2/79

12/13/77

10/5/77

10/5/77

TERMINATION CONTRACT TAIK DEICRIPTION DATE NUMBER

7/80

5/81.

11/80

10/79

3/80

8179

10/79

5/80

12/80

5/80

91ao

11/79

3/81

7 /.79

4/80

6/79

10/79

2/80

1 I 15/80

1/81

3/79

3/79

3/18/80

92

955039 Si CELL PROCESS DEVELOPMENT

)55325 VACUUM DIS CASTING

955582 DIE AND CONTAINER MATERIALS

954852 CHARACTERIZATION--Si PROPERTIES

954373 CASTING INGOT AND SLICING

954877 DIE AND CONTAINER MATERIIALS

955378 LOW ANGLE Si SHEET

LK-694028 TECHNOLOGY FOR IMPURITY AND SURFACE ANALYSIS,SOC

954356 DIP COATING

954888

955270

954977

)54 355

954376

955563

954901

955131

954886

955282

955055

954896

954851

954902

ADVANCED Cz CONTINUOUS GROWTH

LOW-COST CONTINUOUS-GROWTH TECHNOLOGY

ANALYSIS--DEFECTS IN SILICON

RIBBON GROWTH--EFG

RIBBON GROWTH-LASEH ZONE

MULTIBLADE SLICING

CVD SILICON NITRIDE

INGOT SLICING

ADVANCED Cz

INGOT SLICING

Si SOLAR CELL FABRICATION, DEVELOPMENT AND ANALYSIS

CARBON~COATING ANALYSIS

MATERIAL EVALUATION CHARACTERIZATION

SOLAR CELL FAB TECH

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NAME

UNIVERSITY OF SOUTHERN CALIF. LOS ANGELES CA

UNIVERSITY OF MISSOURI COLUMBIA MO

VARIAN VACUUM DIV. LEXINGTON MA

VARIAN VACUUM DIV. PITTSBURGH PA

WESTINGHOUSE ELECTRIC CORP. PITTSBURGH PA

ENCAPSULATIO~ TASK:

CASE WESTERN UNIVERSITY CLEVELAND OH

DOW CORNING MIDLAND MI

ILLINOIS TOOL WORKS ELGIN IL

RB ASSOCIATES SAN RAMON CA

MOTOROLA, INC. PHOENIX AZ

MOTOROLA, INC. PHOENIX AZ

ROCKWELL SCIENCE CENTER THOUSAND OAKS CA

SPIRE CORP. BEDFORD MA

SPECTROLAB, INC. SYLMAR CA

SPRINGBORN LABORATORIES, INC. ENFIELD CT

UNIVERSITY OF MASSACHUSETTS AMHERST MA

UNIVERSITY OF TORONTO TORONTO, ONTARIO, CANADA

START DATE

1/15/80

5/3/79

1/9/76

9/21/77

4/20/77

3/21/77

2/14/78

9/24/79

12/05/78

2/19/79

3/20/79

3/23/77

5/7176

11/8/79

5/ 12/76

8/3/79

1/2/80

TERMINATION CONTRACT DATE NUMBER

3/80 955612

5/80 955415

10/79 954374

7/79 954884

7/80 954654

12/81 954738

9/79 954995

8/81 955506

2/80 955281

12/79 955339

12/79 }55387

2/80 954739

6/80 954521

11/81 955567

8/80 954527

11/80 955531

12/80 955591

93

TASK DESCRIPTION

ABSORPTION COEFFICIENT

PARTIAL PRESSUR~S OF REACTANT GASES

INGOT SLICING

ADVANCED Cz

DENDRITIC WEB

SYSTEM STUDIES--BASIC AGING AND DIFFUSION

ENCAPSULATION SYSTEM

DEPOSIT OF ANTI-REFLECTIVE COATING BY ION PLATING

GLASS-REINFORCED CONCRETE

AR COATING

AR COATING

MATERALS INTERFACE PROBLEM STUDY

ENCAPSULATION--MATERIALS PROPERTIES & PROCESSING

ADVANCED ENCAPSULATION SYSTEMS

METHODS AND MATERIAL PROPERTIES EVALUATION

PRuCESS FOR POLYMERIC UV STABILIZERS & ABSORBERS

?HOTODEGRADATION MODELING

NAME

PRODUCTION PROCESS AND EQUIPMENT:

APPLIED SOLAR ENERGY CORP. CITY OF INDUSTRY CA

APPLIED SOLAR ENERGY CORP. CITY OF INDUSTRY CA

APPLIED SOLAR ENERGY CORP. CITY OF INDUSTRY CA

APPLIED SOLAR ENERGY CORP. CITY OF INDUSTRY CA

ARCO SOLAR, INC. CHATSWORTH CA

BERND ROSS ASSOCIATES SAN DIEGO CA

KINETIC COATINGS INC. BURLINGTON MA

KULICKE & SOFFA INC. HORSHAM PA

MBASSOCIATES SAN RAMON CA

MOTOROLA, INC. PHOENIX AZ

MOTOROLA, INC. PHOENIX AZ

MOTOROLA, INC. PHOENIX AZ

PHOTOWATT INTERNATIONAL, INC. CHATSWORTH CA

PHOTOWATT INTERNATIONAL, INC. CHATSWORTH CA

PHOTOWATT INTERNATIONAL INC. CHATSWORTH CA

RCA CORP. PRINCETON NJ

RCA CORP. PRINCETON NJ

SENSOR TECHNOLOGY CHATSWORTH CA

SENSOR TECHNOLOGY CHATSWORTH CA

SOL/LOS, INC. LOS ANGELES CA

SOLAREX CORP. ROCKVILLE MD

SPECTROLAB, INC. SYLMAR CA

SPECTROLAB, INC. SYLMAR CA

SPIRE CORP. BEDFORD MA

START DATE

8/25/77

11/;?7178

10/4/78

3/30/79

1/8/79

9/11/78

6/8/78

12/ 13/78

11/10/77

9/27177

1/19/79

1/26/79

9/20/77

12/20/78

12/14/78

9/30/77

3/15/79

2/9/78

12/20/78

12/15/78

9/27177

9/30/77

5/30/79

9/16/77

TERMINATION CONTRACT DATE NUMBER

7/80 955217

1/80 )55244

4/80 955423

1/80 955278

1/80 955164

4/79 955079

3/80 955287

2/80 954882

4/80 954847

1/80 955324

1/80 955328

3/80 954865

3/80 955265

11/80 955266

1/80 954868

3/80 955342

3/80 954865

3/80 955265

12/79 955318

8/80 954854

4/80 954853

1/80 955298

6/79 954786

94

TASK DEICRIPTION

SLICING

HIGH-EFFICIENCY SOLAR MODULE

LOW-COST CONTACTS

LABORATORY SERVICES

AUTOMATED SOLAR PANEL ASSEMBLY

THICK-FILM SOLAR CELL CONTACT

ION IMPLANTATION

AUTOMATED SOLAR MODULE ASSEMBLY

PHASE II, PROCESS DEVELOPMENT

PHASE II, PROCESS DEVELOPMENT

ETCH-RESISTANT WAX PATTERNS

THIN-SUBSTRATE CELLS

PHASE II--PRODUCTION PROCESS

POLYSILICON SOLAR CELL

Si WAFER SURFACE TEXTURING

PHASE II, PROCESS DEVELOPMENT

MEGASONIC CLEANING

AUTOMATED ARRAY ASSEMBLY

LOW-COST POLYSILICON SOLAR CELLS

METALLIZATION

PHASE II, PROCESS DEVELOPMENT

PHASE II, PROCESS DEVELOPMENT

HIGH-RESOLUTION CONTACT DEVELOPMENT

ION IMPLANTER

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NAME

SPIRE CORP. BEDFORD MA

TB & A LOS ANGELES CA

TEXAS INSTRUMENTS DALLAS TX

UNIVERSITY OF PENNSYLVANIA PHI LADELPHIA PA

WESTINGHOUSE RESEARCH PITTSBURGH PA

ENGINEERING:

BECHTEL NATIONAL INC. mt;UMBUS~

START DATE

1/10/80

9/30 /77

7 /8/79

9/ 28 /77

2/7177

BOEING CO . 8/19/77 SEATTLE WA

BURT HI LL KOSAR RITTELMAN ASSOC . 8/ 3/78 BUTLER PA

BURT HI LL KOSAR RITTLEMAN ASSOC. 10/22/79 BUTLER PA

CLEMSON UNIVERSITY 12/9/77 CLEMSON SC

DSET 11/5/79 PHOENI X AZ

MOTOROLA INC. 2/27/79 PHOENI X AZ

UNDERWRITE RS LABORATORY , INC. 5/ 2/79 MELVILLE NY

LARGE SCALE PRODUCT ION :

APPLIED SOLAR ENERGY COR P. CITY-OF INDUSTRY CA

GENERAL ELECTRIC PHILADELPHIA PA

MOTOROLA, INC. PHOENIX AZ

SENSOR TECHNOLOGY CHATSWORTH CA

SENSOR TECHNOLOGY CHATSWORTH CA

SOLAR POWER WOBURN MA

SOLA REX CORP . ROCKVILLE MD

SOLEN EAGY COA P. WAKEFI ELD MA

SPIRE CORP . BEDFORD MA

5/ 2/79

5/30/79

5/25/79

1/29/78

11;211179

6/ 13/79

5/ 21/79

8/2/79

5/22/79

TERMINATION CONTRACT TASK DESCRIPTION DATE NUMBER

2/82 955640 SOLAR CELL J UNCTIO N

1/30

9/79

11/80

3/80

3/80

5/79

1/79

2/80

10/80

:i / 81

8/79

11/79

2/ 80

8/80

3/80

12/78

12/79

11/79

2/80

10/79

2/ 80

95

9555 19

954881

954796

9511873

954698

954833

955149

955614

954929

713137

955367

955392

9551109

95540 l

SAPS TECH INSTRUCTION MANUAL & MATHEMATICS

CELL DEVELOPMENT--TANDEM JU NCT [ON CELL

AUTOMATED AR RAY

PHASE I I , PROCESS DEVELO PMENT

CURVED-GLASS MODULE

FEASIBI LI TY STU DY --SOLAR DOME ENCAPSULATION

RESIDENTIAL MODULE REQUIREMENT STUDY

OPER AT ION- MAI NTENANCE COST DATA FOR RESIDENTIAL PHOTOVOLTA I CS

SOLAR CELL RELIABILITY TEST

SPECTRA RADIOMETRI C AND ACCESSOR EQU IPMENT DOCUMENT

STUDY OF TERMINATI ON DESIGN REQUI REMENTS

SOLAR ARRAY & MODULE SAFETY REQUIREMENTS

BLOCK IV

BLOCK IV

955406 BLOCK I V

BF- 67259' 40 kW - BLOCK III

955410 BLOCK TV

955403 BLOCK IV

955404 BLOCK IV

BQ- 713125 BLOCK IV

9551105 BLOCK IV

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LSA PROJECT PUBLISHED DOCUMENTS*

Document No.

5040-29

Author

DOANE, J. W. June, 1976

Title

The Cost of Energy From Utility-owned Solar Electric Systems

5101-7 PROJECT OFFICE LSA First Quarterly Report - April to June 1976 ERDA/JPL-1012-76/6 October, 8, 1976

5101-10 PROJECT OFFICE ERDA/JPL-1012-77/1

5101-12 ZOUTENDYK, J.

5101-13

5101-14

October 28, 1976

GONZALEZ, C. C. February 14, 1977

EDELSON, E. January 26, 1977

LSA Second Quarterly Report - July to September 1976

Progress in Silicon for Terrestrial Photovoltaic Crystal Technology'Solar Energy Conversion

Availability of Ultraviolet Radiation Data (for Encapsulation System Design)

Preliminary Analysis of Industrial Growth and the Factors that Affect Growth Rate

5101-15 CHAMBERLAIN, R. G. SAMICS (Solar Array Manufacturing Industry Costing September 1977 Standards) Workbook

5101-16 LSA ENGR. AREA Rev. A November 1, 1978 DOE/JPL-1012-78/10

5101-19 MOORE, D. February 28, 1977

Block IV Solar Cell Module Design and Test Specifica­tion for Intermediate Load Center Applications

Cyclic Pressure-Load Developmental Testing of Solar Panels

5101-20 CANTU, A.H. Test Program on Low-Cost Connector For Solar Array February 28, 1977 Modules

5101-21 BISHOP/ANHALT Rev. B November 3, 1978

5101-24 PROJECT OFFICE ERDA/JPL-1012-77/2

5101-31 STULTZ/WEN July 29, 1977

5101-32 PROJECT OFFICE DOE/JPL-1012-77/3

Acceptance/Rejection Criteria for JPL/LSA Modules

Project Quarterly Report-3 for the Period October 1976 to December 1976

Thermal Performance Testing and Analysis of Photovoltaic Modules in Natural Sunlight

Quarterly Report-4 for the Period January 1977 to March 1977

5101-33 CHAMBERLAIN/ASTER Interim Price Estimation Guidelines: A Precursor and September 10, 1977 an Adjunct to SAMIS III, Version One

5101-36 SMOKLER, M. User Handbook for Block II Silicon Solar Cell Modules October 15, 1977

5101-39 JAFFE, f, LSA Field Test Activity System Description

5101-40

5101-43

August 3, 1977

COULBERT, C. D. June 8, 1977

GRIPPI, R. A. October 7, 1977

Development & Validation of A Life-Prediction Methodology for LSA Encapsulated Modules

Module Efficiency Definitions, Characteristics and Exijmples

* Documents with DOE/JPL numbers are available from: Technical Information Center P.O. Box 62 Oak Ridge, TN 37830 Phone: (615) 576-1304

97

Document No.

5101-44 Rev. A DOE/JPL-1012-22

5101-45

Author

CHAMBERLAIN/ASTER March 1, 1979

GONZALEZ, C. C. December 6, 1977

5101-46 PROJECT OFFICE DOE/JPL-1012-77/4 June 1977

5101-51 PRATURI/LUTWACK/ Hsu July 17, 1977

5101-53 O'DONNELL/LEIPOLD/ DOE/JPL-1012-77/6 HAGAN

March 1, 1978

5101-54 Vol. I SMITH, J. L. DOE/JPL-1012-78/1 April 1978

5101-54 Vol. II SMITH, J. L. DOE/JPL-1012-78/1 April 1978

5101-55 PROJECT OFFICE DOE/JPL-1012-78/2

5101-56 TURNER, G. B. DOE/JPL-1012-78/3 March 1, 1978

5101-57 CHEN, C. P. DOE/JPL-1012-78/7 February 22, 1978

5101-58 ESTEY, R. S. March 15, 1978

5101-59 CHAMBERLAIN, R. G. February 1, 1978

5101-60 FIRNETT, P.J. Rev. A April 27, 1979

5101-61 CUDDIHY, E. April 13, 1978

5101-62 MOORE/WILSON DOE/JPL-1012-78/6

5101-65 LSA ENGR. AREA DOE/JPL-1012/78/7A March 24, 1978

5101-68

5101-69

ASTER, R. W. May 12, 1978

DAUD/KOLIWAD June 15, 1978

Title

SAMICS Input Data Preparation

Environmental Hail Model for Assessing Risk to Solar Collectors

Project Quarterly Report-5 for the Period April 1977 to June 1977

Chemical Vapor Deposition of Silicon from Silane Pyrolysis

Compatability Studies of Various Refractory Materials in Contact with Molten Silicon

Historical Evidence of Importance to the Industriali­zation of Flat-Plate Silicon Photovoltaic Systems: Executive Summary

Historical Evidence of Importance to the Industriali­zation of Flat-Plate Silicon Photovoltaic SystP.ms

Project Quarterly Report-6 for the Period July 1977 to September 1977

Structure of Deformed Silicon and Implications for Low-Cost Solar Cells

Multi-Wire Slurry Wafering Demonstrations

Measurement of Solar and Simulator Ultraviolet Spectral Irradiance

SAMICS Usage No. 1

SAMIS Computer Program User's Guide -Release 2

Encapsulation Material Trends Reliability 1986 Cost Goals

Photovoltaic Solar Panel Resist - Simulated Hail

Photovoltaic Module Design, Qualification and Testing Specification

Price Allocation Guidelines

Effect of Grain Boundary in Silicon Sheet on Minority Carrier Diffusion Length and Solar Cell Efficiency

5101-70 Rev. A

CHAMBERLAIN/FIRNETT SAMIS III Design Document (Solar Array April 27, 1979 Manufacturing Industry Simulation)

Release 2

98

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.....,

Document No.

5101-71 Rev. A

5101-72

5101-73 DOE/JPL-1012-78/8

5101-75

5101-76 DOE/ JPJ,-1012-78/9

5101-77

5101-79

5101-81 DOE/JP~-1012-78/13

5101-82 DOE/JPL-1012-79/6

5101-83 DOE/JPL-1012-78/14

5101-84 DOE/JPL-1012-78/11

5101-85 OOE/JPL-1012-78/12

5101-88 JPL Publ. 79-14

5101-93 DOE/JPL-1012-79/5

5101-94 DOE/JPL-1012-78/17

5101-98 DOE/JPL-1012-79/1

5101-99 DOE/JPL-1012-3

5101-100 DOE/JPL-1012-4 JPL Puhl. 79-16

Author

CHAMBERLAIN, R. G. April 27, 1979

MAXWELL, H. June 15, 1978

VON ROOS, o. May 31, 1978

SMITH, J. L. May 30, .1978

STULTZ, J. W. July 31, 1978

GUPTA, A. August 10, 1978

GUPTA, A. August 18, 1978

PROJECT OFFICE November 15, 1978

SMOKLER, M. I. November 15, 1979

LSA ENGR. AREA November 1, 1978

HOFFMAN/MILLER October 15, 1978

JAFFE, P • September 15, 1978

PROJECT OFFICE

CHAMERLAIN, R. G. January 15, 1979

ASTER, R. December 1, 1978

GRIFFITH, J. S. January 1, 1979

PROJECT OFFICE

PROJECT OFFICE

Title

SAMIS III Computer Program Source Code -Release 2

Encapsulant Candidate Materials for 1982 Cost Goals

Determination of Bulk Diffusion Lengths for Angle-Lapped Semiconductor Material via the Scanning Electron Microscope - A Theoretical Analysis

The Penetration of the International Market by Domestically Produced Photovoltaic Power Systems: A Survey of Recent Estimates

Thermal and Other Tests of Photovoltaic Modules Performed in Natural Sunlight

Photodegradation of Polymeric Encapsulants of Solar Cell Modules

Effect of Photodegradation on Chemical Structure and Surface Characteristics of Silicon Pottants Used in Solar Cell Modules

Project Quarterly Report-7 for the Period Octob2r 1977 to December 1977

User Handbook for Block III Silicon Solar Cell Modules

Bleck IV Solar Cell Module Design and Test Specification for Residential Applications

Bias-Humidity Testing of Solar Modules

LSA Field Test Annual Report August 1977 to August 1978

Project Quarterly Report-8 for the Period of January - March 1978

A Normative Price for a Manufactured Product: The SAMICS Methodology Volume I: Executive Summary/Volume II: Analysis

Economic Analysis of a Candidate 50¢/Wpk Flat-Plate Photovoltaic Manufactur-ing Technology

Environmental Testing of Block II Solar Cell Modules

Project Quarterly Report-9 for the Period April - June 1978

Project Quarterly Report-10 for the Period July - September 1978

99

Document No.

5101-102

5101-103 DOE/JPL- 1012-7 9/8A

5101- 104 DOE/JPL- 1012-79/1

5101-105 DOE/JPL-1012-20

5101-106 DOE/JPL-1012-21

5101-107 DOE/JPL- 1012-18

5101- 108 DOE/JPJ.- 1012- 19

5101-11 2 DOE/JPL 1012-27

510 1-133 DOE/JPL-1012-29 JPL Publ . 79-88

5101-1 34 DOE/JPL-1012-30 JPL Pub 1. 79-96

5101-1 35 DOE/JPL-1012-31 JPL Publ. 79-92

5101-137 DOE/JPL- 1012-32 JPL Puhl . 79-102

5101-139 DOE/JPL-1 012-34 JPL Publ. 79- 116

5101-141 DOE/JPL-101 2-38 JPL Publ. 80-5

5101-143

5101- 147 DOE/JPL-1012-40 JPL Publ. 80-1 2

Author

SLONSKI, M. L, Februar y 15, 1979

REPAR, J. January 1, 1979

GRIFFITH, J • S. Januar y 1, 1979

PRATURI, A. K. April 15; 1979

PRATURI, A. K. Apri l 1, 1979

RHEIN, R. A. Apri l 15, 1979

RHEIN, R. A. April 15, 1979

PROJECT OFF! CE

PROJECT OFFICE

GRIFFITH, J . S. Sep tember 1 , 1979

LAUE/GUPTA September 21, 1979

CHEN , C. P . October 15, 1979

SALAMA , A, M. November 1, 1979

Jaffe , Peter December 15, 1979

PROJECT OFFICE January 1980

BOUQUET, F. L, February 1, 1980

Title

Energy Systems Economi c Ana lys i s (ESEA) Methodology & User's Guide

Experience with Si licones in Photovoltaic Modules

' Environmenta l Testing of Block II Solar Cell Modules

Modeling of Si licon Particle Growth ; a Progress Report

On the Mod eling of Silane Pyrolysis in a Continuous Flow Reactor

Purification of Si li con by the Silicon Fluoride Transport Process - A Thermochemical Study

Si licon Preparation and Purity from the React ion of Sodium with Silicon Tetraf luoride and Silicon Tetrachloride - A Thermochemi cal Study

Progress Repor t 12 for the Period January 1979 to April 1979

Progress Report 13 for the Period Apr il 1979 to Augus t 1979

Environmental Testing of Block III So lar Cell Modules - Part 1: Qualification Testing of Standard Production Modules

Reactor for Simu l ation and Acceleration of Solar Ultravio l et Damage

Fracture Str ength of Silicon Solar Cells

Characterization of De l iberate l y Nickel-Doped Silicon Wa fers and So l ar Cel l s

LSA Field Test Annual Report August 1978 - August 1979

Electr icity from Photovoltaic Solar Ce ll s Status of Low-Cos t ,Solar Array Project

Glass for Low-Cost Photovoltaic So lar Arrays

100

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