PHOTOVOLTAIC DEVICE CONDUCTING LAYER

1 . A multilayered structure comprising:

a barrier layer adjacent to a substrate;

a transparent conductive oxide layer adjacent to the barrier layer; and

a buffer layer comprising a dopant adjacent to the transparent conductive oxide layer.

2 . The multilayered structure of claim 1 , wherein the dopant is selected from the group consisting of copper, arsenic, and antimony.

3 . The multilayered structure of claim 1 , wherein the doped buffer layer comprises a material selected from the group consisting of tin oxide, zinc oxide, zinc stannate, zinc magnesium oxide, and tin silicon oxide.

4 . The multilayered structure of claim 1 , wherein the doped buffer layer comprises multiple layers.

5 . The multilayered structure of claim 4 , wherein one of the multiple layers comprises a doped layer, and another one of the multiple layers is an undoped layer, and the doped layer is adjacent to the undoped layer.

6 . The multilayered structure of claim 1 , wherein the doped buffer layer has a dopant concentration of more than about 1×10 15 /cm 2 .

7 . The multilayered structure of claim 1 , wherein the doped buffer layer comprises a tin oxide and has a dopant to tin oxide ratio of about 10 −5 to about 10 −1 .

8 . The multilayered structure of claim 1 , further comprising a semiconductor window layer adjacent to the doped buffer layer, wherein the semiconductor window layer comprises a material selected from the group consisting of cadmium sulfide, zinc sulfide, cadmium zinc sulfide, and zinc magnesium oxide.

9 . The multilayered structure of claim 8 , further comprising a semiconductor absorber layer adjacent to the doped buffer layer, wherein the semiconductor absorber layer comprises a material selected from the group consisting of cadmium telluride, zinc telluride, and cadmium zinc telluride.

10 . The multilayered structure of claim 9 , wherein the multilayered structure has a carrier concentration of greater than about 1×10 14 /cm 3 .

11 . A method of manufacturing a multilayered structure, the method comprising:

forming a doped buffer layer adjacent to a transparent conductive oxide layer, wherein the transparent conductive oxide layer is adjacent to a substrate; and

forming a semiconductor window layer adjacent to the buffer layer;

forming a semiconductor absorber layer adjacent to the semiconductor window layer; and

and heating the multilayered structure to a temperature sufficient to diffuse dopant from the buffer layer into the semiconductor absorber layer.

12 . The method of claim 11 , wherein the step of heating the multilayered structure comprises heating the multilayered structure to a temperature greater than 300 degrees C.

13 . The method of claim 11 , wherein the step of heating the multilayered structure comprises heating the multilayered structure to a temperature greater than 450 degrees C.

14 . The method of claim 11 , wherein the step of heating the multilayered structure comprises heating the multilayered structure to a temperature greater than 600 degrees C.

15 . The method of claim 11 , wherein the step of heating the multilayered structure comprises heating the multilayered structure to a temperature greater than 750 degrees C.

16 . The method of claim 11 , wherein the dopant comprises a material selected from the group consisting of copper, arsenic, and antimony.

17 . The method of claim 11 , further comprising forming the transparent conductive oxide layer adjacent to the substrate before forming the doped buffer layer.

18 . The method of claim 11 , wherein the step of forming a doped buffer layer comprises co-sputtering buffer layer material and dopant from separate sputter targets.

19 . The method of claim 14 , wherein the buffer layer material comprises tin and the dopant comprises a material selected from the group consisting of copper, arsenic, and antimony.

20 . The method of claim 11 , wherein the step of forming a doped buffer layer comprises forming a buffer layer adjacent to the transparent conductive oxide layer and doping the buffer layer with a dopant.

21 . The method of claim 11 , wherein the doped buffer layer has more than about 1×10 15 /cm 2 of dopant.

22 . The method of claim 11 , wherein the step of forming a doped buffer layer comprises a reactive sputtering process.

23 . The method of claim 11 , wherein the step of forming a doped buffer layer comprises atmospheric pressure chemical vapor deposition.

24 . The method of claim 11 , further comprising an additional step of heating the transparent conductive oxide stack comprising the transparent conductive oxide layer to anneal the transparent conductive oxide stack.

25 . A photovoltaic device comprising

a barrier layer adjacent to a substrate;

a transparent conductive oxide layer adjacent to the barrier layer;

a buffer layer comprising a dopant adjacent to the transparent conductive oxide layer;

a semiconductor window layer adjacent to the buffer layer;

a semiconductor absorber layer adjacent to the semiconductor window layer, wherein the semiconductor absorber layer comprises a portion of the dopant, diffused from the buffer layer; and

a back contact adjacent to the semiconductor absorber layer.

26 . The photovoltaic device of claim 25 , wherein the dopant comprises a material selected from the group consisting of copper, arsenic, and antimony.

27 . The photovoltaic device of claim 25 , wherein the dopant diffused from the buffer layer to the semiconductor absorber layer is present in a substantially uniform concentration proximate to the buffer layer.

28 . A sputter target comprising:

a sputter material comprising tin and a material selected from the group consisting of copper, arsenic, and antimony; and

a stainless steel tube, wherein the sputter material is connected to the stainless steel tube to form a sputter target.

29 . The sputter target of claim 28 , wherein the sputter material comprises a tin oxide.

30 . The sputter target of claim 28 , wherein the sputter material has a copper to tin ratio of about 10 −6 to about 5×10 −2 .

31 . The sputter target of claim 28 , wherein the sputter target comprises a ceramic tin oxide and copper.

32 . The sputter target of claim 28 , further comprising a bonding layer bonding the sputter material and the backing tube.

33 . A method of manufacturing a sputter target comprising:

forming a sputter material comprising tin and a material selected from the group consisting of copper, arsenic, and antimony; and

attaching the sputter material to a backing tube to form a sputter target.

34 . The method of claim 33 , wherein the step of attaching the sputter material to a backing tube to form a sputter target comprises a thermal spray forming process.

35 . The method of claim 33 , wherein the step of attaching the sputter material to a backing tube to form a sputter target comprises a plasma spray forming process.

36 . The method of claim 33 , wherein the step of attaching the sputter material to a backing tube to form a sputter target comprises a powder metallurgy process.

37 . The method of claim 33 , wherein the powder metallurgy process comprises a hot press process.

38 . The method of claim 33 , wherein the powder metallurgy process comprises an isostatic process.

39 . The method of claim 33 , wherein the step of attaching the sputter material to a backing tube to form a sputter target comprises a flow forming process.

40 . The method of claim 33 , wherein the step of attaching the sputter material to the backing tube comprises bonding the sputtering material to the backing tube with a bonding layer.

41 . A photovoltaic module comprising:

a plurality of photovoltaic cells adjacent to a substrate; and

a back cover adjacent to the plurality of photovoltaic cells, each one of the plurality of photovoltaic cells comprising:

a barrier layer adjacent to the substrate;

a transparent conductive oxide layer adjacent to the barrier layer;

a buffer layer comprising a dopant adjacent to the transparent conductive oxide layer;

a semiconductor window layer adjacent to the buffer layer;

a semiconductor absorber layer adjacent to the semiconductor window layer, wherein the semiconductor absorber layer comprises a portion of the dopant, diffused from the buffer layer; and

a back contact adjacent to the semiconductor absorber layer.

42 . The photovoltaic module of claim 41 , further comprising a plurality of positive and negative electrical lines configured to electrically connect the photovoltaic cells to a positive lead and a negative lead.

43 . The photovoltaic module of claim 42 , further comprising a positive bus bar and negative bus bar configured to electrically connect the photovoltaic cells to a positive lead and a negative lead.

44 . The photovoltaic module of claim 43 , wherein the positive lead and negative lead are configured to electrically connect the photovoltaic module to at least on additional photovoltaic module to form a photovoltaic array.

45 . A method for generating electricity, the method comprising:

illuminating a photovoltaic cell with a beam of light to generate a photocurrent; and

collecting the generated photocurrent, wherein the photovoltaic cell comprises:

a barrier layer adjacent to a substrate;

a transparent conductive oxide layer adjacent to the barrier layer;

a buffer layer comprising a dopant adjacent to the transparent conductive oxide layer;

a semiconductor window layer adjacent to the buffer layer;

a semiconductor absorber layer adjacent to the semiconductor window layer, wherein the semiconductor absorber layer comprises a portion of the dopant, diffused from the buffer layer; and

a back contact adjacent to the semiconductor absorber layer.