Polycrystalline CdTe thin film semiconductor photovoltaic cell structures for use in solar electricity generation

• US 9,190,555 B2
• Filed: 08/28/2014
• Issued: 11/17/2015
• Est. Priority Date: 07/17/2008
• Status: Active Grant

• Current Assignee: Uriel Solar, Inc.
• Original Assignee: Uriel Solar, Inc.
• Inventors: Garnett, James David
• Primary Examiner(s): Lee, Kyoung
• Application Number:
  US14/471,887
• Publication Number:
  US 20140370647A1
• Time in Patent Office: 446 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 31/0296 including, apart from doping material or other impurities, only AIIBVI compounds, e.g. CdS, ZnS, HgCdTe
• CPC Class Codes: H01L 31/02966 including ternary compounds, e.g. HgCdTe
• CPC Class Codes: H01L 31/0392 including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate textured substrates H01L31/02366
• CPC Class Codes: H01L 31/03925 including AIIBVI compound materials, e.g. CdTe, CdS
• CPC Class Codes: H01L 31/0725 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/073 comprising only AIIBVI compound semiconductors, e.g. CdS/CdTe solar cells
• CPC Class Codes: H01L 31/078 including different types of potential barriers provided for in two or more of groups H01L31/062 - H01L31/075
• CPC Class Codes: H01L 31/1828 the active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe
• CPC Class Codes: H01L 31/1832 comprising ternary compounds, e.g. Hg Cd Te
• CPC Class Codes: H01L 31/1836 comprising a growth substrate not being an AIIBVI compound
• CPC Class Codes: Y02E 10/543 Solar cells from Group II-VI materials
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Solar cell structures formed using molecular beam epitaxy (MBE) that can achieve improved power efficiencies in relation to prior art thin film solar cell structures are provided. A reverse p-n junction solar cell device and methods for forming the reverse p-n junction solar cell device using MBE are described. A variety of n-p junction and reverse p-n junction solar cell devices and related methods of manufacturing are provided. N-intrinsic-p junction and reverse p-intrinsic-n junction solar cell devices are also described.

Claims

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

forming a first layer over a substrate, the first layer comprising tellurium (Te) and zinc (Zn) and not containing cadmium (Cd);

forming a second layer over the first layer, the second layer comprising Cd and Te; and

forming a third layer over the second layer, the third layer comprising Cd, Zn and Te.

2. The method of claim 1, further comprising forming a layer comprising Zn and Te over the substrate before forming the first layer.

3. The method of claim 1, further comprising forming an other layer over the third layer, the other layer comprising Cd, Zn and Te.

4. The method of claim 1, wherein the first layer is chemically doped n-type, the second layer is chemically doped n-type, and the third layer is chemically doped p-type.

5. The method of claim 1, wherein the first layer is chemically doped p-type, the second layer is chemically doped p-type, and the third layer is chemically doped n-type.

6. A method for forming a photovoltaic device, comprising:

forming a low ohmic ZnTe;

N++ contact layer over a superstrate;

forming a p-type CdTe layer over the low ohmic ZnTe;

N++ layer;

forming an n-type, compositionally graded, CdZnTe layer over the p-type CdTe to form a p-n heterojunction; and

forming a low ohmic CdZnTe;

In++ contact layer over the p-n heterojunction.

7. The method of claim 6, further comprising forming a ZnTe buffer layer over the superstrate before forming the ZnTe:

N++ contact layer.

8. A method for forming a photovoltaic device, comprising:

forming a low ohmic ZnTe;

N++ contact layer over a superstrate;

forming an intrinsic CdTe (i-CdTe) layer over the low ohmic ZnTe;

N++ layer; and

forming a low ohmic CdZnTe;

In++ contact layer over the i-CdTe layer.

9. The method of claim 8, further comprising forming a ZnTe buffer layer over the superstrate before forming the ZnTe:

N++ contact layer.

10. A method for forming a high performance single junction photovoltaic device, comprising:

forming a low ohmic CdTe;

In++ contact layer over a superstrate;

forming an n-type CdTe layer over the low ohmic CdTe;

In++ layer;

forming a p-type, compositionally graded, CdZnTe layer over the n-type CdTe to form a p-n heterojunction; and

forming a low ohmic CdZnTe;

As++ contact layer over the p-n heterojunction.

11. The method of claim 10, further comprising forming a ZnTe buffer layer over the superstrate before forming the CdTe:

In++ contact layer.

12. A method for forming a photovoltaic device, comprising

forming an n-type layer having Cd and Te;

forming an intrinsic CdTe layer over the n-type layer; and

forming a p-type layer having Te and one or more of Cd and Zn over the intrinsic CdTe layer.

13. The method of claim 12, wherein the photovoltaic device comprises a superstrate below the n-type layer.

14. The method of claim 12, wherein the photovoltaic device comprises a superstrate above the p-type layer.

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

forming a first layer over a substrate that does not contain CdTe, the first layer comprising cadmium (Cd) and tellurium (Te), wherein the substrate is amorphous;

forming a second layer over the first layer, the second layer comprising Cd, Zn and Te; and

forming a third layer over the second layer, the third layer comprising Te.

16. The method of claim 15, wherein the first layer is chemically doped n-type, the second layer is chemically doped p-type, and the third layer is chemically doped p-type.

17. The method of claim 15, wherein the third layer does not contain Cd.

18. A method for forming a photovoltaic device, comprising:

forming a first layer over a substrate, the first layer comprising tellurium (Te) and cadmium (Cd), wherein the first layer does not contain zinc (Zn), wherein the substrate is amorphous;

forming a second layer over the first layer, the second layer comprising Cd, Zn and Te; and

forming a third layer over the second layer, the third layer comprising Te.

19. The method of claim 18, wherein the substrate does not contain CdTe.

20. The method of claim 18, wherein the first layer is chemically doped n-type, the second layer is chemically doped p-type, and the third layer is chemically doped p-type.

21. The method of claim 18, wherein the third layer does not contain Cd.