Photovoltaic device with protective layer over a window layer and method of manufacture of the same

1. A photovoltaic device, comprising:

a window layer;

an absorber layer; and

a protective layer between the window layer and the absorber layer which inhibits movement of the window layer into the absorber layer during device processing; and

an intermediate layer formed between the protective layer and absorber layer,

wherein the protective layer comprises Zn, the absorber layer comprises Cd, and the intermediate layer comprises Zn and Cd.

2. A photovoltaic device, comprising:

a window layer;

an absorber layer;

a protective layer between the window layer and the absorber layer which inhibits movement of the window layer into the absorber layer during device processing; and

an intermediate layer formed between the protective layer and absorber laver,

wherein the protective layer comprises ZnO: ZnS, the absorber layer comprises CdTe, and-the intermediate layer comprises ZnTe.

3. A photovoltaic device, comprising:

a window laver;

an absorber layer; and

a protective layer between the window layer and the absorber layer which inhibits movement of the window layer into the absorber layer during device processing,

wherein the window layer comprises CdS and the absorber layer comprises CdTe, and

wherein the protective layer comprises a material selected from the group consisting of Cu 2 S and Cu 2 O.

4. The photovoltaic device of claim 3 , wherein the window layer has a thickness of between about 10 nm and about 40 nm.

5. A photovoltaic device, comprising:

a window layer;

an absorber layer; and

a protective layer between the window layer and the absorber layer which inhibits movement of the window layer into the absorber layer during device processing,

wherein the window layer comprises CdS and the absorber layer comprises CdTe, and wherein a graded CdS x Te y A z layer (0<x<1,0<y<1, 0<z<1) is formed between the window layer and absorber layer, wherein A is one of As, P or Se.

6. The photovoltaic device of claim 5 , wherein the graded CdS x Te y A z layer is formed from a material selected from the group consisting of CdSe, GaP, As 2 Se 3 , Se and Zn 3 P 2 which diffuses into the absorber layer during device processing.

7. The photovoltaic device of claim 5 , wherein the graded CdS x Te y A z layer has an energy band-gap between those of the window layer and the absorber layer.

8. The photovoltaic device of claim 5 , wherein the window layer has a thickness of between about 10 nm and about 40 nm.

9. A method of forming a photovoltaic device, comprising:

forming a window laver;

forming an absorber layer;

forming a protective layer between the window layer and the absorber layer; and

activating the absorber layer,

wherein the protective layer inhibits intermixing of the window layer into the absorber layer during the activation and comprises at least one of Zn, ZnO, ZnS, and ZnO:ZnS, the window layer comprises CdS, and the absorber layer comprises CdTe.

10. A method of forming a photovoltaic device, comprising:

forming a window layer;

forming an absorber layer;

forming a protective layer between the window layer and the absorber layer; and

activating the absorber layer,

wherein the window layer comprises CdS, the absorber layer comprises CdTe, and the protective layer inhibits intermixing of the window layer into the absorber layer during the activation and comprises a material selected from the group consisting of Cu 2 S and Cu 2 O.

11. The method of claim 10 , wherein the window layer has a thickness of between about 10 nm and about 40 nm.

12. A method of forming a photovoltaic device, comprising:

forming a window layer;

forming an absorber layer;

forming a protective layer between the window layer and the absorber layer; and

activating the absorber layer,

wherein the window layer comprises CdS, the absorber layer comprises CdTe, and the protective layer inhibits intermixing of the window layer into the absorber layer during the activation, comprises a material selected from the group consisting of CdSe, GaP, As 2 Se 3 , Se and Zn 3 P 2 , and diffuses into the absorber layer during the activation step, forming a graded CdS x Te y A z , layer (0<x<1, 0<y<1,0<z <1), wherein A is one of As, P or Se.

13. The method of claim 12 , wherein the graded CdS x Te y A z layer has an energy band-gap between those of the window layer and the absorber layer.

14. The method of claim 12 , wherein the window layer has a thickness of between about 10 nm and about 40 nm.

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

forming a window layer;

forming an absorber layer;

forming a protective layer between the window layer and the absorber layer;

activating the absorber layer;

forming an intermediate layer between the protective layer and the absorber laver,

wherein the protective layer inhibits intermixing of the window layer into the absorber layer during the activation, comprises Zn, and has different material characteristics from the window laver, and wherein the absorber layer comprises Cd, and the intermediate layer comprises Zn and Cd.

16. A method of forming a photovoltaic device, comprising:

forming a window layer;

forming an absorber layer;

forming a protective layer between the window layer and the absorber layer;

activating the absorber layer;

forming an intermediate layer between the protective layer and the absorber layer,

wherein the protective layer inhibits intermixing of the window layer into the absorber layer during the activation, comprises ZnO:ZnS, and has different material characteristics from the window layer, and wherein the absorber layer comprises CdTe, and the intermediate layer comprises ZnTe.

17. A method of forming a photovoltaic device, comprising:

forming a window layer;

forming an absorber laver;

forming a protective layer between the window layer and the absorber layer, the protective layer;

activating the absorber layer; and

forming an intermediate layer between the protective layer and the absorber layer,

wherein the protective layer inhibits intermixing of the window layer into the absorber layer during the activation, comprises Zn and has different material characteristics from the window laver, and the intermediate layer comprises ZnTe.