# US 5,346,853 A · Microwave energized deposition process with substrate temperature control for the fabrication of P-I-N photovoltaic devices

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- Number: US 5,346,853 A
- Document ID: US5346853A
- Status: Granted
- Kind: A
- Application number: 08/185,309
- Filed: 1994-01-21
- Granted: 1994-09-13
- Earliest claimed: 1992-06-29
- Assignees: United Solar Systems Corporation
- Inventors: Subhendu Guha; Chi C. Yang; XiXiang Xu
- Web page: https://patentgrep.com/patent/US5346853A

## CPC

- H10F 71/1035: {having multiple Group IV elements, e.g. SiGe or SiC}
- H10F 71/103: {including only Group IV materials}
- H10F 71/107: {Continuous treatment of the devices, e.g. roll-to roll processes or multi-chamber deposition}
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P 14/3444: {P-type}
- Y02E 10/50: Photovoltaic [PV] energy
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Substrate temperatures are maintained above 400.degree. C. During the microwave energized glow discharge deposition of Group IV semiconductor materials. The substrate temperature range provides for the preparation of materials having improved electrical properties. Cell efficiency of a photovoltaic device of the p-i-n type is significantly improved by depositing the intrinsic layer using a microwave generated plasma and a substrate temperature in excess of 400.degree. C. Maximum cell efficiency occurs for depositions carried out in the range of 400.degree.-500.degree. C.

## Claims

### Claim 1

A method for the manufacture of an p-i-n type photovoltaic device of the type comprising a body of substantially intrinsic Group IV semiconductor alloy interposed between two oppositely doped semiconductor layers, said method including the steps of:
I. Depositing a body of semiconductor material of a first conductivity type upon a substrate;
II. Depositing a body of a substantially intrinsic Group IV semiconductor alloy upon said body of semiconductor :material of a first conductivity type, by a microwave energized glow discharge deposition process comprising:
a. providing a deposition system having a plasma region defined therein, said system including a conduit for introducing a process gas there into and a source of of microwave energy for activating said process gas in said plasma region so as to decompose said gas and form a plasma therefrom;
b. supporting said substrate, with said body of semiconductor material of a first conductivity type thereupon, in said plasma region;
c. maintaining said substrate at a temperature in excess of 400.degree. C.;
d. introducing a process gas having a Group IV semiconductor element therein into said system;
e. maintaining the process gas at a process pressure which is less than atmospheric;
f. inputting microwave energy into said system at a power level at least sufficient to sustain a plasma of said process gas at said process pressure in said plasma region, whereby said microwave energy creates a plasma from, and decomposes, the process gas so as to deposit a layer of said Group IV semiconductor alloy material on the body of semiconductor material of a first conductivity type; and
III. Depositing a body of semiconductor material of a second conductivity type, opposite said first conductivity type, upon said layer of Group IV semiconductor alloy material.

### Claim 2

In a method for the manufacture of a p-i-n type photovoltaic device by a process which includes the steps of:
depositing a first, doped layer of a semiconductor material of a first conductivity type on a substrate; depositing a substantially intrinsic layer of a Group IV semiconductor alloy material upon said first doped layer by a microwave energized glow discharge deposition process; and
depositing a second doped layer of a semiconductor material of a second conductivity type, opposite said first conductivity type, upon said substantially intrinsic layer, wherein the improvement comprises in combination:
maintaining said substrate, with said first doped layer thereupon, at a temperature which is greater than 400.degree. C., but less than 500.degree. C. during the deposition of said substantially intrinsic layer.