Substitute beer and pizza?

Basic Silicon Solar Cellas fabricated in Cameron

With

Schematic

A detailed traveler is used to define the process steps

The process begins with a silicon wafer, 100mm in diameter, (100) orientation,

PRIME grade, p-type boron doped, 1-10 ohm-cm resistivity

The process begins with a silicon wafer, 100mm diameter, (100) orientation, PRIME grade, p-type boron doped, 1-10 ohm-cm

resistivity

Shown in cross section of wafer

The wafer is cleaned using the sulfuric acid/hydrogen peroxide

clean

Using PECVD (plasma enhanced chemical vapor deposition) the back side is coated

with SiO2 to prevent doping of the backside

Using POCl3 as the source for phosphorus doping an n-region will be created in the p-

type silicon wafer

POCl3 bubbler – nitrogen is bubbled through the liquid POCl3 and carries phosphorus into the tube

With the POCl3 running into the tube, phophorus is diffused into the silicon wafer

at 950C

A n-region is now diffused into the silicon wafer at 950C

A metal film (aluminum) is sputtered on the top surface and a photolithographic mask

creates a conductive grid in the metal

A metal film (Aluminum) is sputtered on the top surface and a photolithographic mask

creates a conductive grid in the metal

Positive photoresist is spun on the metal coated wafer

A transparency mask of the top side grid is placed on top of the photoresist coated

wafer and exposed to UV

The image is developed which leaves the metal conductor pattern

With photoresist protecting the metal, the unprotected metal is etched away

leaving the top side grid pattern in metal

A metal film is evaporated on the top surface and a photolithographic mask creates a

conductive grid in the metal

A second metal film (aluminum) is deposited on the back for backside contact

A second metal film is deposited on the back for backside contact

Using PECVD (plasma enhanced chemical vapor deposition) an anti-reflective coating

of SiO2 is deposited on the top surface

Using PECVD (plasma enhanced chemical vapor deposition) a anti-relective coating of

SiO2 is deposited on the top surface

Individual cells are diamond saw cut from the wafer

Individual cells are diamond saw cut from the wafer

Electrical testing (I-V trace) of the cell is performed under a solar light simulator

Calibration cell determines the intensity of sunlight

Electrical testing (I-V trace) of the cell is performed under a solar light simulator

Electrical testing (I-V trace) of the cell is performed under a solar light simulator

Blue trace is without sun light, red trace is with sunlight at 1.0 sun

Completed Solar Cell

Assignment

• Lecture 4 assignment from web site