Pras

ertS

inse

rmsu

ksak

ul,

Jaey

eong

Heo,

and

Roy

G. G

ordo

n

Depa

rtm

ent o

f Che

mist

ry a

nd C

hem

ical

Bio

logy

Harv

ard

Uni

vers

ity

Atom

ic L

ayer

Dep

ositi

on o

f Tin

(II) S

ulfid

e

2

Cu(In

,Ga)

(Se,

S)2

(CIG

S)Cd

TeHi

ghes

t ene

rgy

conv

ersio

n ef

ficie

ncy

of ~

20%

Adva

ntag

e�

Low

man

ufac

turin

g co

st�

Mod

erat

e ef

ficie

ncy

Lim

itatio

n�

Use

rare

ele

men

ts (I

n, Te

, and

Se)

�Co

ntai

n to

xic

elem

ent (

Cd)

NRE

L

wik

iped

ia

SnS

has s

ome

of th

ese

prop

ertie

s.

�Ba

sic C

riter

ia fo

r the

Abs

orbe

r Mat

eria

l.

�Su

itabl

e en

ergy

ban

dgap

( Eg

~ 1.

0-1.

5 eV

).

�Hi

gh o

ptic

al a

bsor

ptio

n co

effic

ient

( 10

4 -10

5 cm

-1).

�th

ickn

ess /

mas

s of m

ater

ial r

equi

red.

? Hi

gh q

uant

um y

ield

for t

he e

xcite

d ca

rrie

rs

? Lo

ng c

arrie

r diff

usio

n le

ngth

/ lo

w c

ombi

natio

n ve

loci

ty

�PV

effi

cien

cy

�Th

e co

nstit

uent

ele

men

ts a

re n

on-T

oxic

and

abu

ndan

t.

�no

n-ha

zard

, sca

labi

lity,

low

cos

t PV.

3

�Li

mita

tion

from

var

ious

dep

ositi

on te

chni

ques

�Co

ntai

n ot

her b

inar

y ph

ases

(SnS

2an

d Sn

2S3)

�Co

ntam

inat

ion

from

oxy

gen

(CBD

) and

chl

orin

e (C

VD)

�La

rge

devi

atio

n fr

om id

eal s

toic

hiom

etric

SnS

(tin

vac

anci

es)

�N

arro

w d

epos

ition

tem

pera

ture

win

dow

(25-

50 o C

rang

e @

~ 3

00 o C

)

4

Atom

ic L

ayer

Dep

ositi

on�

exce

llent

con

trol

ove

r sur

face

reac

tion

�w

ell-c

ontr

olle

d st

oich

iom

etry

�hi

gh d

ensit

y fil

m�

low

impu

rity

�lo

w d

epos

ition

tem

pera

ture

Sn(a

md)

2pr

ecur

sor

�ea

sily

synt

hesiz

ed�

suffi

cien

t vap

or p

ress

ure

�th

erm

ally

stab

le Sn(a

md)

2+

H 2S �

SnS

5

�M

inim

um e

xpos

ures

of 1

.5 To

rr·s

of S

n(am

d)2

and

1.1

Torr

·s o

f H 2S

are

requ

ired

to sa

tura

te th

e su

rfac

e re

actio

ns�

Grow

th ra

te o

f 0.9

0 Å/

cycl

e (1

20 o C

)

6

�N

ot d

etec

t oth

er b

inar

y ph

ase

(e.g

.Sn

S 2an

d Sn

2S3)

.�

Wid

e de

posit

ion

tem

pera

ture

win

dow

.

Ram

an S

pect

rosc

opy

7

S

Sn

SiO

2 su

bstr

ate

SnS 1±

0.01

Ruth

erfo

rd B

acks

catt

erin

g Sp

ectr

osco

py (R

BS)

�St

oich

iom

etric

SnS

(Low

Sn+2

vaca

ncy)

bel

ow 2

00 o C

�De

nsity

~ 4

.6 g

/cm

3(~

90%

of b

ulk

valu

e)

8

From

XPS

�N

o ca

rbon

, nitr

ogen

, or o

xyge

n de

tect

ed o

n Sn

Sfil

m d

epos

ited

belo

w 2

00 o C

.(SI

M)

�~

1-2%

car

bon

cont

amin

atio

n on

film

dep

osite

d ab

ove

250

o C.

Sn(a

md)

2st

arts

to

deco

mpo

se a

bove

250

o C.

SnS

CuI

nSe 2

GaA

s

CdT

e

Silic

on

a-Si

MD

MO

-PPV

(o

rgan

ic d

ye)

9

Eg ~

1.3

5 eV

�~

105

cm-1�

Nee

d ~

500

nm fo

r 95%

abs

orpt

ion

N

elso

n, J.

The

Phy

sics o

f Sol

ar C

ells;

Impe

rial C

olle

ge P

ress

10

Top

view

alo

ng b

axi

sSi

de v

iew

Ort

horh

ombi

c St

ruct

ure

( a�

b� c

and

�=

�=

�=

90o

)

a =

4.28

, b =

11.

20, c

= 3

.99

Å

(111)(040)

(101)

(002)

�De

sirab

le c

ryst

al o

rient

atio

n.�

high

er m

obili

ty th

roug

h th

e fil

m.

(Sin

gle

crys

tal:

μ /// μ

�~

10.)*

�ca

rrie

r tra

nspo

rt a

long

def

ect-

tole

rant

la

yer p

lane

crys

tal p

refe

rred

orie

ntat

ion

�do

uble

laye

r dist

orte

d N

aCl

stru

ctur

e.�

high

ly a

niso

trop

ic m

ater

ial.

c

b

http

://w

ebm

iner

al.c

om

*Nas

sary

, M.M

., Jo

urna

l of A

lloys

and

Com

poun

ds, 2

005.

398

(1-2

): p.

21-

25.

�Ha

ll m

easu

rem

ent

�la

tera

l res

istiv

ity �

~ 1

0 –

900

�•c

m

�lo

w h

ole

conc

entr

atio

n ~

1016

cm-3

�fe

w S

n+2va

canc

ies

�w

ide

depl

etio

n re

gion

in p

-n ju

nctio

n

�la

tera

l hol

e m

obili

ty ~

1-4

cm

2V-1

s-1

11

500n

m

SnS

Colu

mna

r str

uctu

re

�� ve

rtic

al/ �

late

ral ~

3�

low

er sc

atte

ring

from

gra

in b

ound

ary

�hi

gher

mob

ility

alo

ng c

ryst

al la

yer

plan

es

500n

m

Tsub

= 12

0 o C

Tsub

= 20

0 o C

12

Tim

e-Re

solv

ed P

hoto

lum

ines

cenc

e

�M

inor

ity c

arrie

r life

time

~ 90

ns

�Es

timat

ed m

inor

ity c

arrie

r diff

usio

n le

ngth

~ 1

.5 μ

m

�Sn

S is

a pr

omisi

ng a

bsor

ber m

ater

ial f

or e

arth

-abu

ndan

t, no

n-to

xic

thin

film

sola

r cel

ls.

�AL

D of

SnS

from

the

reac

tion

of ti

n(II)

am

idin

ate

and

H2S

.�

pure

SnS

phas

e ov

er w

ide

tem

pera

ture

rang

e.�

stoi

chio

met

ricSn

S�

no im

purit

y fr

om o

ther

ele

men

ts.

�lo

w d

epos

ition

tem

pera

ture

.

�O

ptic

al a

nd e

lect

rical

pro

pert

ies s

uita

ble

for t

hin

film

sola

r cel

ls.�

Eg =

1.3

5 eV

with

�>

105

cm-1

�[p

] ~ 1

016cm

-3w

ith μ

p~

1 -4

cm

2 V-1

s-1

�~

3x h

ighe

r mob

ility

thro

ugh

the

film

due

to c

olum

nar s

truc

ture

an

d cr

ysta

l orie

ntat

ion

�lo

ng m

inor

ity c

arrie

r life

time

(~ 9

0 ns

)13

Prof

. Roy

G. G

ordo

n

Prec

urso

r: Ad

am S

. Hoc

k an

d W

onta

eN

oh

Reac

tor:

Shen

gXu

and

Haris

h Bh

anda

ri

Colle

ague

s : Ja

eyeo

ngHe

o, L

eizh

iSun

, and

Hel

en P

ark

Hall

mea

sure

men

t: M

ark

Win

kler

, Ren

ee S

her,

and

Prof

. Eric

Maz

ur

14