# US 4,396,793 A · Compensated amorphous silicon solar cell

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- Number: US 4,396,793 A
- Document ID: US4396793A
- Status: Granted
- Kind: A
- Application number: 06/367,811
- Filed: 1982-04-12
- Granted: 1983-08-02
- Earliest claimed: 1982-04-12
- Assignees: Chevron Research Company
- Inventors: Arun Madan
- Web page: https://patentgrep.com/patent/US4396793A

## CPC

- H10F 10/17: Photovoltaic cells having only PIN junction potential barriers
- H10F 71/103: {including only Group IV materials}
- Y02E 10/548: Amorphous silicon PV cells
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- Y10S 438/919: Compensation doping
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- 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
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A hydrogenated amorphous silicon solar cell incorporating a compensated photoactive intrinsic region containing N-type and P-type dopants.

## Claims

### Claim 1

In a hydrogenated amorphous silicon solar cell which comprises an electrically conductive substrate, a layer of hydrogenated amorphous silicon having regions of differing conductivity with at least one region of photoactive intrinsic hydrogenated amorphous silicon, said layer of hydrogenated amorphous silicon having opposed first and second major surfaces where said first major surface contacts said electrically conductive substrate, and means for electrically contacting said second major surface, the improvement wherein the photoactive intrinsic hydrogenated amorphous silicon region is compensated with suitable N-type and P-type dopants to reduce the bandgap energy of the material to less than about 1.6 eV, said doping concentration adjusted such that the recombination lifetime of the photoactive intrinsic region is greater than the transit time for the holes and electrons generated in said photoactive intrinsic region out of said region during illumination of the solar cell.

### Claim 2 (depends on 1)

The solar cell according to claim 1 wherein the P-type and N-type dopant concentrations in said compensated intrinsic region are from about 500 to about 1500 vol. ppm.

### Claim 3 (depends on 2)

The solar cell according to claim 2 wherein the photoactive intrinsic region has a bandgap energy of about 1.5 eV.

### Claim 4 (depends on 1)

The solar cell according to claim 1 wherein the cell is a P-I-N solar cell.

### Claim 5 (depends on 1)

The solar cell according to claim 1 wherein the solar cell is an NIP solar cell.

### Claim 6 (depends on 1)

The solar cell according to claim 1 wherein said cell comprises an N.sup.+ -type region contacting the electrically conductive substrate, a photoactive compensated intrinsic region contacting said N.sup.+ -type region and a Schottky barrier metal layer contacting the photoactive intrinsic region to form a Schottky barrier solar cell.

### Claim 7 (depends on 1, 3, 4, 5)

The solar cell according to claim 1, 3, 4 or 5 wherein said layer of hydrogenated amorphous silicon includes a P-type layer fabricated from an atmosphere comprising silane and diborane; silane, ammonia and diborane; silane, methane and diborane; or silane, nitrous oxide and diborane.

### Claim 8 (depends on 1, 3)

The solar cell according to claim 1 or 3 wherein the photoactive compensated intrinsic region is fabricated from an atmosphere comprising silane, diborane, and phosphine.

### Claim 9 (depends on 8)

The solar cell according to claim 8 wherein the hydrogenated amorphous silicon further incorporates a halogen.

### Claim 10 (depends on 1)

The solar cell according to claim 1 wherein the photoactive compensated intrinsic hydrogenated amorphous silicon region further includes a halogen.

### Claim 11

A method of reducing the bandgap energy of a photoactive intrinsic hydrogenated amorphous silicon region incorporated into a hydrogenated amorphous silicon solar cell, said method comprising:
incorporating a suitable P-type and N-type dopants during the growth of said layer in amounts sufficient to reduce the bandgap energy of the photoactive intrinsic hydrogenated amorphous silicon region to less than about 1.6 eV, said concentrations of said N-type and P-type dopants also being sufficient to fabricate a photoactive intrinsic region wherein the recombination lifetime is greater than the transit time of holes and electrons out of said photoactive region during illumination.

### Claim 12 (depends on 11)

The method according to claim 11 wherein the N-type and P-type dopants are incorporated in an amount sufficient to fabricate an intrinsic region containing N-type and P-type dopant concentrations on the order of 500 to about 1500 vol. ppm.

### Claim 13 (depends on 12)

The method according to claim 12 wherein the substrate temperature is from about 250.degree. C. to about 350.degree. C. during the deposition.

### Claim 14 (depends on 13)

The method according to claim 13 wherein the growth atmosphere for hydrogenated amorphous silicon comprises silicon-hydrogen-halogen gases.

### Claim 15 (depends on 14)

The method according to claim 14 wherein the atmosphere is SiF.sub.4 and H.sub.2 plus dopant gases.