# US 10,374,119 B1 · Heterojunction GaSb infrared photovoltaic cell

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- Number: US 10,374,119 B1
- Document ID: US10374119B1
- Status: Granted
- Kind: B1
- Application number: 15/819,894
- Filed: 2017-11-21
- Granted: 2019-08-06
- Earliest claimed: 2016-11-21
- Assignees: JX Crystals Inc.
- Applicants: JX Crystals Inc.
- Inventors: Lewis M. Fraas
- Web page: https://patentgrep.com/patent/US10374119B1

## CPC

- H10F 71/127: {The active layers comprising only Group III-V materials, e.g. GaAs or InP}
- H10F 77/124: comprising only Group III-V materials, e.g. GaAs
- H10F 10/166: the Group IV-IV heterojunctions being heterojunctions of crystalline and amorphous materials, e.g. silicon heterojunction [SHJ] photovoltaic cells
- H10F 10/167: comprising Group I-III-VI materials, e.g. CdS/CuInSe2 [CIS] heterojunction photovoltaic cells
- H10F 77/219: {Arrangements for electrodes of back-contact photovoltaic cells}
- H10F 77/247: {comprising indium tin oxide [ITO]}
- Y02E 10/541: CuInSe2 material PV cells
- Y02E 10/544: Solar cells from Group III-V materials
- 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

## Abstract

Heterojunction GaSb Photocells for operating in wavelengths around 1.6 microns have P type GaSb wafers with backside P+ back metal contacts. Patterned active areas are created on the front side and receive a thin passivation film. A thin N+ transparent SnO2 or tin conductive oxide is deposited on the passivation film. A front contact grid is deposited. The thin passivating film is either amorphous silicon (a-Si:H) or TiO2 with a hydrogen plasma pretreatment. The deposited N+ transparent SnO2 or tin conductive oxide forms an N+/P Heterojunction cell. Front grid contacts and full back contacts are deposited. An antireflective coating is applied through the grids.

## Claims

### Claim 1

Apparatus comprising:
heterojunction N+ on P GaSb infrared photovoltaic cell, further comprising:
a P type GaSb single crystal substrate having a front side and a back side,
a P+ ohmic metal contact on the back side,
a thin passivating front side coating,
a N+ transparent conductive oxide coating on the thin passivating front side coating, and
a collecting front metal grid on the transparent conductive oxide coating; wherein the heterojunction is between the N+ transparent conductive oxide coating and the P type GaSb single crystal substrate.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the P type GaSb crystal is doped to between 0.5 and 2×1017/cm3.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the thin passivating layer is a-Si:H layer.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein the thin passivating layer is TiO2 with a hydrogen plasma treatment.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein the N+ transparent conductive oxide is fluorine doped tin oxide with doping between 0.5 and 1.5×1020/cm3.

### Claim 6 (depends on 1)

The device of claim 1, further comprising an antireflection coating on the front side.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the antireflection coating is SiNx.

### Claim 8 (depends on 1)

The apparatus of claim 1, further comprising plural cells in a panel of cells.

### Claim 9 (depends on 8)

The apparatus of claim 8, further comprising plural panels in an array of panels.

### Claim 10

A process for forming an infrared photovoltaic cell comprising:
providing a P type GaSb single crystal wafer as the substrate, having a front side and a back side,
depositing a SiNx layer on the front side of the wafer,
diffusing a P+ ohmic metal contact on the back side of the wafer,
patterning the SiNx layer, and creating cell active areas on the front side,
depositing a passivation layer on the cell active areas,
depositing an N+ transparent conductive oxide coating on the passivation layer,
depositing and patterning an antireflection coating layer, and
depositing front and back contacts on the front side and the back side, respectively;
wherein a heterojunction is formed by the N+ transparent conductive oxide coating and the p type GaSb single crystal substrate.

### Claim 11 (depends on 10)

The process of claim 10, wherein the depositing of a passivation layer comprises depositing an a-SiH layer.

### Claim 12 (depends on 10)

The process of claim 10, wherein the depositing and creating an antireflection area comprises depositing a SiNx layer.

### Claim 13 (depends on 10)

The process of claim 10, further comprising depositing an N+ transparent SnO2 layer before depositing the front contacts.

### Claim 14 (depends on 10)

The process of claim 10, further comprising depositing a SiNx antireflection layer and creating patterned grid openings in the SiNx antireflection layer.

### Claim 15 (depends on 14)

The process of claim 14, wherein the depositing front contacts comprises depositing front contacts through the grid openings and through the antireflection layer.

### Claim 16 (depends on 10)

The process of claim 10, wherein the depositing the back contacts comprises covering a back of the wafer with the back contact.