# US 2014/0190561 A1 · Solar cell with reduced base diffusion area

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- Number: US 2014/0190561 A1
- Document ID: US20140190561A1
- Status: Published application
- Kind: A1
- Application number: 14/159,292
- Filed: 2014-01-20
- Published: 2014-07-10
- Earliest claimed: 2006-07-24
- Assignees: SunPower Corporation
- Applicants: Sunpower Corporation
- Inventors: Denis DE CEUSTER; Peter John COUSINS
- Web page: https://patentgrep.com/patent/US20140190561A1

## CPC

- H10F 77/211: {for photovoltaic cells}
- H10F 10/11: Photovoltaic cells having point contact potential barriers (H10F10/18 takes precedence)
- H10F 10/146: {Back-junction photovoltaic cells, e.g. having interdigitated base-emitter regions on the back side}
- H10F 77/219: {Arrangements for electrodes of back-contact photovoltaic cells}
- Y02E 10/547: Monocrystalline silicon PV cells
- 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

In one embodiment, a solar cell has base and emitter diffusion regions formed on the back side. The emitter diffusion region is configured to collect minority charge carriers in the solar cell, while the base diffusion region is configured to collect majority charge carriers. The emitter diffusion region may be a continuous region separating the base diffusion regions. Each of the base diffusion regions may have a reduced area to decrease minority charge carrier recombination losses without substantially increasing series resistance losses due to lateral flow of majority charge carriers. Each of the base diffusion regions may have a dot shape, for example.

## Claims

### Claim at position 1

1-20. (canceled)

### Claim 21

A solar cell comprising:
a first metal contact electrically coupled to an emitter diffusion region;
a second metal contact electrically coupled to a base diffusion region, wherein the second metal contact is formed over the base diffusion region and the emitter diffusion region; and
a first insulator between the second metal contact and the emitter diffusion region, the first insulator electrically insulating the emitter diffusion region from the second metal contact.

### Claim 22 (depends on 21)

The solar cell of claim 21, wherein the emitter diffusion region is a continuous emitter diffusion region.

### Claim 23 (depends on 21)

The solar cell of claim 21, wherein the base diffusion region is a dotted base diffusion region.

### Claim 24 (depends on 21)

The solar cell of claim 21, further comprising:
a second insulator between the first insulator and the second metal contact.

### Claim 25 (depends on 21)

The solar cell of claim 21, wherein the emitter diffusion region is doped with boron and the base diffusion region is doped with phosphorus.

### Claim 26 (depends on 21)

The solar cell of claim 21, wherein the first metal contact and second metal contact are interdigtitated.

### Claim 27 (depends on 21)

The solar cell of claim 21, wherein the substrate is an N-type silicon substrate.

### Claim 28

A method of fabricating a solar cell, the method comprising:
forming an emitter diffusion region on a substrate;
forming a base diffusion region on the substrate;
forming a first metal contact electrically coupled to the emitter diffusion region;
forming a second metal contact over the emitter diffusion region and the base diffusion region, wherein the second metal contact is electrically coupled to base diffusion region; and
forming a first insulator between the second metal contact and the emitter diffusion region, the first insulator electrically insulating the emitter diffusion region from the second metal contact.

### Claim 29 (depends on 28)

The method of claim 28, wherein forming the emitter diffusion region comprises forming a continuous emitter diffusion region.

### Claim 30 (depends on 28)

The method of claim 28, wherein forming the base diffusion region comprises forming a dotted based diffusion region.

### Claim 31 (depends on 28)

The method of claim 28, wherein forming the first metal contact and second metal contact comprises forming the first and second metal contacts in an interdigtitated pattern.

### Claim 32 (depends on 28)

The method of claim 28, wherein forming the emitter diffusion region comprises using a high-temperature diffusion process.

### Claim 33 (depends on 28)

The method of claim 28, wherein forming the base diffusion region comprises using a high-temperature diffusion process.

### Claim 34 (depends on 28)

The method of claim 28, further comprising:
forming a second insulator between the first insulator and the second metal contact.

### Claim 35

A solar cell, comprising:
an emitter diffusion region configured to collect minority charge carriers in the solar cell;
a base diffusion region configured to collect majority charge carriers in the solar cell;
a first metal contact electrically coupled to the emitter diffusion region;
a second metal contact electrically coupled to the base diffusion region, wherein the second metal contact is formed over the base diffusion region and the emitter diffusion region; and
a first insulator between the second metal contact and the emitter diffusion region, the first insulator electrically insulating the emitter diffusion region from the second metal contact.

### Claim 36 (depends on 35)

The solar cell of claim 35, wherein the emitter diffusion region is a continuous emitter diffusion region.

### Claim 37 (depends on 35)

The solar cell of claim 35, wherein the base diffusion region is a dotted base diffusion region.

### Claim 38 (depends on 35)

The solar cell of claim 35, further comprising:
a second insulator layer between the first insulator layer and the second metal contact.

### Claim 39 (depends on 35)

The solar cell of claim 35, wherein the first metal contact and second metal contact are interdigtitated.

### Claim 40 (depends on 35)

The solar cell of claim 35, wherein the silicon substrate is an N-type silicon substrate.