# US 4,398,054 A · Compensated amorphous silicon solar cell incorporating an insulating layer

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- Number: US 4,398,054 A
- Document ID: US4398054A
- Status: Granted
- Kind: A
- Application number: 06/367,812
- Filed: 1982-04-12
- Granted: 1983-08-09
- Earliest claimed: 1982-04-12
- Assignees: Chevron Research Company
- Inventors: Arun Madan
- Web page: https://patentgrep.com/patent/US4398054A

## CPC

- H10F 71/103: {including only Group IV materials}
- H10F 10/17: Photovoltaic cells having only PIN junction potential barriers
- Y02E 10/548: Amorphous silicon PV cells
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- Y10S 438/904: Charge carrier lifetime control
- 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 P-I-N type compensated amorphous silicon solar cell which incorporates an insulating layer adjacent to the compensated intrinsic amorphous silicon layer.

## Claims

### Claim 1

A solar cell comprising:
an electrically conductive substrate;
a layer of P-type conductivity hydrogenated amorphous silicon electrically contacting said substrate;
a layer of photoactive compensated intrinsic hydrogenated amorphous silicon contacting said P-type layer, said layer having a bandgap energy less than about 1.6 eV and incorporating N-type and P-type dopants in an amount sufficient to reduce the bandgap of the layer while maintaining a recombination lifetime which is greater than the transit time of holes and electrons out of said layer during the illumination of said layer by solar radiation;
a layer of electrically insulating material contiguous to and deposited on said photoactive layer of compensated hydrogenated amorphous silicon;
a layer of N-type conductivity hydrogenated amorphous silicon contacting said insulating layer; and
means for electrically contacting said N-type layer.

### Claim 2 (depends on 1)

The amorphous silicon solar cell according to claim 1 wherein said insulating layer has a thickness of from about 1 to 5 nanometers.

### Claim 3 (depends on 2)

The amorphous silicon solar cell according to claim 2 wherein the insulator is selected from the group consisting of Si.sub.3 N.sub.4, SiO.sub.2, BN, Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5.

### Claim 4 (depends on 3)

The amorphous silicon solar cell according to claim 3 wherein said insulating layer has a thickness of about 3 nanometers.

### Claim 5 (depends on 1, 2)

The amorphous silicon solar cell according to claims 1 or 2 wherein said photoactive compensated layer incorporates N-type and P-type dopants in an amount of from about 500 to about 1500 volume ppm.

### Claim 6 (depends on 5)

A solar cell according to claim 5 wherein the compensated layer has a bandgap of about 1.5 eV.

### Claim 7 (depends on 5)

The solar cell according to claim 5 wherein the amorphous silicon incorporates a halogen therein.

### Claim 8

A method of reflecting holes back into a photoactive compensated intrinsic hydrogenated amorphous silicon layer in an amorphous silicon solar cell, said solar cell incorporating an N-type layer incident to solar radiation, said method comprising:
incorporating suitable N-type and P-type dopants into the photoactive compensated intrinsic layer during the fabrication thereof in an amount sufficient to reduce the bandgap of said photoactive intrinsic region, said dopants being incorporated in an amount such that the recombination lifetime of holes and electrons is greater than the transit time of said holes and electrons out of said layer during the illumination of said intrinsic layer; and
fabricating an insulating layer between the photoactive compensated layer and a layer of N-type conductivity hydrogenated amorphous silicon incident to solar radiation.

### Claim 9 (depends on 8)

The method according to claim 8 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 10 (depends on 9)

The method according to claim 9 wherein the substrate temperature is from about 250.degree. C. to about 350.degree. C. during the deposition.

### Claim 11 (depends on 8)

The method according to claim 8 wherein the growth atmosphere for said amorphous silicon comprises silicon-hydrogen-halogen gases.

### Claim 12 (depends on 11)

The method according to claim 11 wherein the atmosphere is SiF.sub.4 and H.sub.2.

### Claim 13 (depends on 8, 11)

The method according to claim 8 or 11 wherein the insulating layer is from about 1 to about 5 nanometers thick.

### Claim 14 (depends on 13)

The method according to claim 13 wherein the insulator is selected from the group consisting of Si.sub.3 N.sub.4, SiO.sub.2, BN, Ta.sub.2 O.sub.5, and Nb.sub.2 O.sub.5.

### Claim 15 (depends on 14)

The method according to claim 14 wherein the compensated layer has a bandgap energy less than about 1.6 eV.