Heterojunction III-V Photovoltaic Cell Fabrication

• US 20100307572A1
• Filed: 02/26/2010
• Published: 12/09/2010
• Est. Priority Date: 06/09/2009
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Shahidi, Ghavam, Cortes, Norma Sosa, Bedell, Stephen W., Fogel, Keith E., Sadana, Devendra, Shahrjerdi, Davood
• Granted Patent: US 8,802,477 B2
• Time in Patent Office: Days
• US Class Current: 136/255
• CPC Class Codes: H01L 21/20 Deposition of semiconductor materials on a substrate, e.g. epitaxial growth solid phase epitaxy
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: H01L 31/0304 including, apart from doping materials or other impurities, only AIIIBV compounds
• CPC Class Codes: H01L 31/03762 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/0725 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/074 comprising a heterojunction with an element of Group IV of the Periodic Table, e.g. ITO/Si, GaAs/Si or CdTe/Si solar cells
• 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 31/184 the active layers comprising only AIIIBV compounds, e.g. GaAs, InP
• CPC Class Codes: H01L 31/1892 methods involving the use of temporary, removable substrates
• CPC Class Codes: H01L 31/20 such devices or parts thereof comprising amorphous semiconductor materials
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method for forming a heterojunction III-V photovoltaic (PV) cell includes performing layer transfer of a base layer from a wafer of a III-V substrate, the base layer being less than about 20 microns thick; forming an intrinsic layer on the base layer; forming an amorphous silicon layer on the intrinsic layer; and forming a transparent conducting oxide layer on the amorphous silicon layer. A heterojunction III-V photovoltaic (PV) cell includes a base layer comprising a III-V substrate, the base layer being less than about 20 microns thick; an intrinsic layer located on the base layer; an amorphous silicon layer located on the intrinsic layer; and a transparent conducting oxide layer located on the amorphous silicon layer.

Claims

1. A method for forming a heterojunction III-V photovoltaic (PV) cell, the method comprising:

performing layer transfer of a base layer from a wafer of a III-V substrate, the base layer being less than about 20 microns thick;

forming an intrinsic layer on the base layer;

forming an amorphous silicon layer on the intrinsic layer; and

forming a transparent conducting oxide layer on the amorphous silicon layer.

2. The method of claim 1, wherein the layer transfer comprises smart cut, and wherein smart cut comprises:

performing hydrogen implantation in the wafer below the base layer; and

annealing the wafer to initiate a fracture below the base layer.

3. The method of claim 1, wherein the layer transfer comprises epitaxial layer transfer, and wherein epitaxial layer transfer comprises:

forming a sacrificial layer in the wafer below the base layer; and

using a wet chemical etch of the sacrificial layer to remove the base layer from the wafer.

4. The method of claim 1, wherein the layer transfer comprises spalling, and wherein spalling comprises:

forming a metal layer having a tensile stress on the wafer;

adhering a flexible substrate to the metal layer;

using the tensile stress in the metal layer to cause a fracture in the wafer below the base layer; and

removing the flexible substrate from the metal layer.

5. The method of claim 4, wherein the metal layer comprises nickel.

6. The method of claim 4, wherein the flexible substrate comprises a material having a radius of curvature of less than 5 meters.

7. The method of claim 1, further comprising forming a back surface field on the wafer before performing layer transfer, wherein the back surface field comprises at least one of zinc, indium, and wherein the back surface field is layer transferred from the wafer with the base layer.

8. The method of claim 1, wherein the amorphous silicon layer comprises a doping type that is opposite a doping type of the substrate, and the amorphous silicon layer is configured to act as an emitter.

9. The method of claim 1, further comprising forming a second intrinsic layer on the wafer and forming a second amorphous silicon layer on the second intrinsic layer before performing layer transfer, wherein the second intrinsic layer and second amorphous silicon layer are layer transferred from the wafer with the base layer.

11. The method of claim 1, The method of claim 10, wherein the second amorphous silicon layer comprises a doping type that is the opposite to a doping type of the substrate, and the second amorphous silicon layer is configured to act as an emitter.

12. The method of claim 1, wherein the wafer comprises one of germanium or gallium arsenide.

10. The method of claim 10, wherein the second amorphous silicon layer comprises a doping type that is the same as a doping type of the substrate, and the second amorphous silicon layer is configured to act as a back surface field.

13. A heterojunction III-V photovoltaic (PV) cell, comprising:

a base layer comprising a III-V substrate, the base layer being less than about 20 microns thick;

an intrinsic layer located on the base layer;

an amorphous silicon layer located on the intrinsic layer; and

a transparent conducting oxide layer located on the amorphous silicon layer.

14. The heterojunction III-V PV cell of claim 13, further comprising a back surface field located under the base layer, wherein the back surface field comprises at least one of zinc, indium, or aluminum.

15. The heterojunction III-V PV cell of claim 13, wherein the amorphous silicon layer comprises a doping type that is opposite a doping type of the substrate, and the amorphous silicon layer is configured to act as an emitter.

16. The heterojunction III-V PV cell of claim 13, further comprising a second intrinsic layer located under the base layer, and a second amorphous silicon layer located under the second intrinsic layer.

17. The heterojunction III-V PV cell of claim 16, wherein the second amorphous silicon layer comprises a doping type that is the same as a doping type of the substrate, and the second amorphous silicon layer is configured to act as a back surface field.

18. The heterojunction III-V PV cell of claim 16, wherein the second amorphous silicon layer comprises a doping type that is opposite to a doping type of the substrate, and the second amorphous silicon layer is configured to act as an emitter.

19. The heterojunction III-V PV cell of claim 13, further comprising a metal layer located under the base layer, the metal layer comprising nickel.

20. The heterojunction III-V PV cell of claim 13, wherein the III-V substrate comprises one of germanium or gallium arsenide.