Sulfide species treatment of thin film photovoltaic cell and manufacturing method

• US 8,193,028 B2
• Filed: 08/02/2011
• Issued: 06/05/2012
• Est. Priority Date: 10/06/2008
• Status: Expired due to Fees

• Current Assignee: Stion Corporation
• Original Assignee: Stion Corporation
• Inventors: Lee, Howard W. H.
• Primary Examiner(s): Vu, David
• Assistant Examiner(s): Taylor, Early
• Application Number:
  US13/196,827
• Publication Number:
  US 20110287575A1
• Time in Patent Office: 308 Days
• Field of Search: 438/85, 257E21466-E2147, 257/E21.483, 257/E21.485, 257/E21.497, 136/265
• US Class Current: 438/85
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02491 Conductive materials
• CPC Class Codes: H01L 21/02568 Chalcogenide semiconducting materials not being oxides, e.g. ternary compounds
• CPC Class Codes: H01L 21/02614 Transformation of metal, e.g. oxidation, nitridation
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 31/0322 comprising only AIBIIICVI chalcopyrite compounds, e.g. Cu In Se2, Cu Ga Se2, Cu In Ga Se2
• CPC Class Codes: H01L 31/03923 including AIBIIICVI compound materials, e.g. CIS, CIGS
• CPC Class Codes: H01L 31/0749 including a AIBIIICVI compound, e.g. CdS/CulnSe2 [CIS] heterojunction solar cells
• CPC Class Codes: Y02E 10/541 CuInSe2 material PV cells

Abstract

A method for forming a thin film photovoltaic device. The method includes providing a transparent substrate comprising a surface region, forming a first electrode layer overlying the surface region, forming a copper layer overlying the first electrode layer and forming an indium layer overlying the copper layer to form a multi-layered structure. The multi-layered structure is subjected to a thermal treatment process in an environment containing a sulfur bearing species to forming a copper indium disulfide material. The copper indium disulfide material comprising a copper-to-indium atomic ratio ranging from about 1.2:1 to about 2:1 and a thickness of substantially copper sulfide material having a copper sulfide surface region. The thickness of the copper sulfide material is selectively removed to expose a surface region having a copper poor surface comprising a copper to indium atomic ratio of less than about 0.95:1. The method subjects the copper poor surface to a sulfide species to convert the copper poor surface from an n-type semiconductor characteristic to a p-type semiconductor characteristic. A window layer is formed overlying the copper indium disulfide material.

Claims

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

providing a transparent substrate comprising a surface region;

forming a first electrode layer overlying the surface region;

forming a copper layer overlying the first electrode layer;

forming an indium layer overlying the copper layer to form a multi-layered structure;

subjecting at least the multi-layered structure to a thermal treatment process in an environment containing a sulfur bearing species;

forming a copper indium disulfide material from at least the thermal treatment process of the multi-layered structure, the copper indium disulfide material comprising a thickness of substantially copper sulfide material having a sulfur deficient region;

subjecting the sulfur deficient region to a sulfide species;

subjecting the sulfur deficient region to a treatment process during a time period; and

forming a window layer overlying the copper indium disulfide material.

2. The method of claim 1 further comprising:

removing the thickness of the copper sulfide material to expose a surface region having a copper poor surface; and

subjecting the copper poor surface to a sodium species.

3. The method of claim 2 wherein the subjecting to the sodium species and the subjecting to sulfide species is provided by at least one process selected from spin coating, spraying, spray pyrolysis, pyrolysis, dipping, deposition, sputtering, or electrolysis.

4. The method of claim 2 wherein the copper poor surface is compensated by sodium ions derived form a sodium sulfide material and the sulfur deficient region is compensated by the sulfide ions derived from the sodium sulfide material or an ammonium sulfide species.

5. The method of claim 2 wherein the removing comprises using a solution of potassium cyanide to selectively remove the thickness of copper sulfide material.

6. The method of claim 1 wherein the window layer is selected from a group consisting of a cadmium sulfide, a zinc sulfide, zinc selenium, zinc oxide, or zinc magnesium oxide.

7. The method of claim 1 wherein the treatment process of the copper poor surface comprises a thermal process characterized by a temperature from about 100 Degrees Celsius to about 500 Degrees Celsius.

8. The method of claim 1 wherein the forming of the copper layer is provided by a sputtering process or a plating process.

9. The method of claim 1 wherein the forming of the indium layer is provided by a sputtering process or a plating process.

10. The method of claim 1 wherein the copper indium disulfide has a p-type semiconductor characteristic.

11. The method of claim 1 wherein the window layer comprises an n+-type semiconductor characteristic.

12. The method of claim 1 further comprising introducing an indium species in the window layer to cause formation of an n+-type semiconductor characteristic.

13. The method of claim 1 wherein the copper indium disulfide is mixed with a copper indium aluminum disulfide or copper indium gallium disulfide.

14. The method of claim 1 wherein the treatment process is provided in an environment containing at least a sulfur bearing species comprising hydrogen sulfide in fluid phase.

15. A method for forming a thin film photovoltaic device, the method comprising:

providing a transparent substrate comprising a surface region;

forming a first electrode layer overlying the surface region;

forming a copper indium material by at least sputtering a target comprising an indium copper material;

subjecting the copper indium material to a first thermal treatment process in an environment containing a sulfur bearing species;

forming a copper indium disulfide material from at least the first thermal treatment process of the copper indium material;

forming a sulfur deficient copper indium disulfide material in a region of the copper indium disulfide material;

compensating for the lack of sulfur in the sulfur deficient copper indium disulfide material; and

forming a window layer overlying the copper indium disulfide material.

16. The method of claim 15 wherein the compensating is provided by at least one process selected from spin coating, spraying, spray pyrolysis, pyrolysis, dipping, deposition, sputtering, or electrolysis.

17. The method of claim 15 wherein the compensating for the lack of sulfur is performed using a sulfur species comprising sulfide ions.

18. The method of claim 17 wherein the sulfur species comprises hydrogen sulfide.

19. The method of claim 15 further comprising:

forming a copper poor copper indium disulfide material in a surface region of the copper indium disulfide material; and

subjecting at least the copper poor copper indium disulfide material to a second thermal treatment process ranging in temperature from about 100 Degrees Celsius to about 500 Degrees Celsius.

20. The method of claim 15 wherein the window layer is selected from a group consisting of a cadmium sulfide, a zinc sulfide, zinc selenium, zinc oxide, or zinc magnesium oxide.

21. The method of claim 15 further comprising forming a transparent conductive oxide overlying a portion of the window layer.

22. The method of claim 15 wherein the copper indium disulfide material has a p-type semiconductor characteristic.

23. The method of claim 15 wherein the window layer comprises n+-type semiconductor characteristic.

24. The method of claim 15 further comprising introducing an indium species in the window layer to cause formation of an n+-type semiconductor characteristic.

25. A method for forming a thin film photovoltaic device, the method comprising:

providing a transparent substrate comprising a surface region;

forming a first electrode layer overlying the surface region;

forming a chalcopyrite material overlying the electrode layer, the chalcopyrite material comprising at least a sulfur deficient copper indium disulfide material; and

exposing the sulfur deficient copper indium disulfide material to a sulfur species comprising sulfide ions;

forming a window layer overlying the chalcopyrite material; and

forming a second electrode layer overlying the window layer.