Solar cell front contact doping

1. A photovoltaic device comprising:

a substrate;

a transparent conductive oxide layer doped by a first dopant;

a buffer layer doped by a second dopant, wherein the second dopant comprises at least one element selected from the group consisting of chlorine, gallium, fluorine, and magnesium, the buffer layer comprising at least one material selected from the group consisting of zinc telluride and cadmium zinc telluride;

a semiconductor window layer doped by a third dopant, the semiconductor window layer comprising at least one material selected from the group consisting of cadmium sulfide, zinc telluride, cadmium zinc sulfide, zinc oxide, zinc sulfide, zinc aluminum oxide, zinc silicon oxide, zinc zirconium oxide, tin aluminum oxide, tin silicon oxide, tin zirconium oxide and cadmium oxide; and

a semiconductor absorber layer comprising cadmium telluride,

wherein the transparent conductive oxide layer is between the substrate and the buffer layer,

wherein the semiconductor window layer is between the buffer layer and the semiconductor absorber layer, and

wherein the first and third dopants comprise at least one element selected from the group consisting of aluminum, sodium, indium, boron, copper, chlorine, gallium, fluorine, and magnesium.

2. The photovoltaic device of claim 1 , wherein the transparent conductive oxide layer comprises at least one component selected from the group consisting of zinc oxide, cadmium stannate, and tin oxide.

3. The photovoltaic device of claim 1 , wherein the dopant comprises first and second dopants comprise an N-type dopant.

4. The photovoltaic device of claim 1 , wherein the substrate comprises glass.

5. The photovoltaic device of claim 1 , wherein the window layer comprises an M 1-x G x O y semiconductor, the M is selected from the group consisting of zinc and tin, and the G is selected from the group consisting of aluminum, silicon, and zirconium, or at least one component selected from the group consisting of cadmium sulfide, zinc telluride, cadmium zinc sulfide, zinc oxide, zinc sulfide, zinc magnesium oxide, cadmium magnesium sulfide, zinc aluminum oxide, zinc silicon oxide, zinc zirconium oxide, tin aluminum oxide, tin silicon oxide, tin zirconium oxide, and cadmium oxide.

6. The photovoltaic device of claim 2 , the transparent conductive oxide comprising cadmium stannate.

7. The photovoltaic device of claim 1 , the semiconductor window layer comprising at least one material selected from the group consisting of cadmium sulfide and zinc oxide.

8. The photovoltaic device of claim 1 , wherein the first dopant comprises at least one element selected from the group consisting of sodium, boron and fluorine.

9. The photovoltaic device of claim 1 , further comprising a zinc telluride interfacial layer between the semiconductor window layer and the semiconductor absorber layer.

10. The photovoltaic device of claim 1 , wherein only a region of the transparent conductive oxide layer is doped.

11. The photovoltaic device of claim 2 , the transparent conductive oxide layer having a sheet resistance of about 5 ohms per square or less.