Method to form a photovoltaic cell comprising a thin lamina

• US 7,842,585 B2
• Filed: 09/11/2008
• Issued: 11/30/2010
• Est. Priority Date: 02/05/2008
• Status: Expired due to Fees

• Current Assignee: Neutron Therapeutics Inc.
• Original Assignee: Twin Creeks Technologies, Inc.
• Inventors: Petti, Christopher J., Herner, S. Brad, Agarwal, Aditya, Sivaram, Srinivasan
• Primary Examiner(s): Brewster; William M
• Assistant Examiner(s): JEAN BAPTISTE, WILNER
• Application Number:
  US12/208,392
• Publication Number:
  US 20090197368A1
• Time in Patent Office: 810 Days
• Field of Search: 438/5, 438/460, 438/86, 438/459, 438/458, 438/57, 438/455, 257/E21.001, 257/E31.001
• US Class Current: 438/460
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/0682 back-junction, i.e. rearside emitter, solar cells, e.g. interdigitated base-emitter regions back-junction cells
• CPC Class Codes: H01L 31/0747 comprising a heterojunction of crystalline and amorphous materials, e.g. heterojunction with intrinsic thin layer
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/1892 methods involving the use of temporary, removable substrates
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials
• CPC Class Codes: Y02E 10/545 Microcrystalline silicon PV cells
• CPC Class Codes: Y02E 10/546 Polycrystalline silicon PV cells
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• 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 very thin photovoltaic cell is formed by implanting gas ions below the surface of a donor body such as a semiconductor wafer. Ion implantation defines a cleave plane, and a subsequent step exfoliates a thin lamina from the wafer at the cleave plane. A photovoltaic cell, or all or a portion of the base or emitter of a photovoltaic cell, is formed within the lamina. In preferred embodiments, the wafer is affixed to a receiver before the cleaving step. Electrical contact can be formed to both surfaces of the lamina, or to one surface only.

Claims

1. A method for forming a device, the method comprising:

permanently adhering a first surface of a semiconductor body to a receiver, wherein the receiver is metal; and

cleaving a lamina from the semiconductor body, wherein the lamina comprises the first surface, the first surface remains adhered to the receiver, and the lamina is between 1 and 80 microns thick.

2. The method of claim 1 wherein the lamina is between 1 and 20 microns thick.

3. The method of claim 1 wherein the semiconductor body is a silicon wafer.

4. The method of claim 1 wherein the lamina comprises a second surface opposite the first, wherein a metal or transparent conductive oxide makes electrical contact to the second surface.

5. The method of claim 4 further comprising, before the adhering step, doping the first surface to a first conductivity type.

6. The method of claim 4 further comprising doping the second surface to a second conductivity type opposite the first conductivity type.

7. The method of claim 4 wherein a transparent conductive oxide makes electrical contact to the second surface, and wherein the transparent conductive oxide is zinc oxide.

8. The method of claim 1 further comprising, before the adhering step, implanting one or more species of gas ions through the first surface, wherein a depth of maximum concentration of the implanted gas ions defines a cleave plane for the cleaving step.

9. The method of claim 8 wherein the one or more species of gas ions comprise hydrogen ions and helium ions.

10. The method of claim 1 wherein the lamina is between about 1 and about 5 microns thick.

11. The method of claim 1 wherein the lamina is between about 1 and about 2 microns thick.

12. The method of claim 1 wherein the semiconductor body is a monocrystalline silicon wafer.

13. The method of claim 1 wherein the semiconductor body comprises polycrystalline or multicrystalline semiconductor material.

14. The method of claim 1 further comprising, after the cleaving step, fabricating a photovoltaic cell, wherein the photovoltaic cell comprises the lamina.

15. The method of claim 1 wherein the receiver is aluminum.