FIELD-EFFECT PHOTOVOLTAIC ELEMENTS

• US 20190157488A1
• Filed: 01/06/2019
• Published: 05/23/2019
• Est. Priority Date: 01/13/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hekmatshoartabari, Bahman, Sadana, Devendra K., Haensch, Wilfried E., Shahidi, Ghavam G., Shahrjerdi, Davood
• Granted Patent: US 11,011,662 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 31/022433 Particular geometry of the grid contacts
• CPC Class Codes: H01L 31/022441 Electrode arrangements specially adapted for back-contact solar cells
• CPC Class Codes: H01L 31/0304 including, apart from doping materials or other impurities, only AIIIBV compounds
• CPC Class Codes: H01L 31/062 the potential barriers being only of the metal-insulator-semiconductor type
• CPC Class Codes: H01L 31/075 the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
• CPC Class Codes: H01L 31/076 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/1126 the device being a field-effect phototransistor
• CPC Class Codes: H01L 31/1133 the device being a conductor-insulator-semiconductor diode or a CCD device
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells

Abstract

Photovoltaic devices such as solar cells having one or more field-effect hole or electron inversion/accumulation layers as contact regions are configured such that the electric field required for charge inversion and/or accumulation is provided by the output voltage of the photovoltaic device or that of an integrated solar cell unit. In some embodiments, a power source may be connected between a gate electrode and a contact region on the opposite side of photovoltaic device. In other embodiments, the photovoltaic device or integrated unit is self-powering.

Claims

1. A photovoltaic structure comprising:

a gallium arsenide absorption layer having a front side, a back side and a first conductivity type;

a gate dielectric layer in direct contact with the front side of the absorption layer;

a gate electrode in direct contact with the gate dielectric layer;

a back surface field layer in direct contact with the back side of the absorption layer, the back surface field layer having a second conductivity type opposite from the first conductivity type; and

a source/drain region on the back side of the absorption layer;

the absorption layer, the gate dielectric layer, the gate electrode and the back surface field layer being configured to cause diffusion of charge carriers, thereby forming a n-p or a p-n junction including a charge carrier inversion layer, when light penetrates the absorption layer.

2. The photovoltaic structure of claim 1, further including an ohmic contact operably associated with the back surface field layer, the ohmic contact being electrically connected to the gate electrode.

3. The photovoltaic structure of claim 2, wherein the absorption layer comprises n-type gallium arsenide.

4. The photovoltaic structure of claim 2, wherein the absorption layer comprises p-type gallium arsenide.

5. The photovoltaic structure of claim 2, further including a power supply connected between the gate electrode and the ohmic contact.

6. The photovoltaic structure of claim 5, wherein the source/drain region is a Schottky source/drain device.

7. The photovoltaic structure of claim 1, wherein the source/drain region is a Schottky source/drain device.

8. The photovoltaic structure of claim 7, further including an ohmic contact operably associated with the back surface field layer, the ohmic contact being electrically connected to the gate electrode.

9. The photovoltaic structure of claim 1, further including a transparent insulating substrate, the gate electrode being bonded to the transparent insulating substrate.

10. A photovoltaic circuit comprising:

a plurality of solar cell devices, each solar cell device comprising;

a gallium arsenide absorption layer having a front side, a back side and a first conductivity type;

a gate dielectric layer in direct contact with the front side of the absorption layer;

a gate electrode in direct contact with the gate dielectric layer;

a back surface field layer in direct contact with the back side of the absorption layer, the back surface field layer having a second conductivity type opposite from the first conductivity type; and

a source/drain region on the back side of the absorption layer;

the absorption layer, the gate dielectric layer, the gate electrode and the back surface field layer of each solar cell device being configured to cause diffusion of charge carriers, thereby forming a n-p or a p-n junction including charge carrier inversion layer, when light penetrates the absorption layer;

the solar cell devices being electrically connected in series and wherein the gate electrode of at least one of the solar cell devices is electrically connected to one of the back surface field layers of another of the solar cell devices.

11. The photovoltaic circuit of claim 10, further comprising a power supply electrically connected between the gate terminal of at least one of the solar cell devices and one of the back surface field layers of another of the solar cell devices.

12. The photovoltaic circuit of claim 10, wherein the absorption layer of one or more of the solar cell devices comprises n or p type gallium arsenide.

13. The photovoltaic circuit of claim 10, wherein each solar cell device further includes an ohmic contact operably associated with the back surface field layer, the ohmic contact being electrically connected to the gate electrode thereof.

14. The photovoltaic circuit of claim 13, wherein the source/drain region of each solar cell device is a Schottky source/drain device.

15. The photovoltaic circuit of claim 10, wherein each solar cell device further includes a transparent insulating substrate, the gate electrode of each solar cell device being bonded to the transparent insulating substrate.