Polycrystalline CDTE thin film semiconductor photovoltaic cell structures for use in solar electricity generation
A reverse p-n junction solar cell device and methods for forming the reverse p-n junction solar cell device 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.
1. A method for forming a photovoltaic device, comprising:
forming a first layer over a superstrate or substrate, the first layer comprising tellurium (Te) and cadmium (Cd) or zinc (Zn);
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,
wherein:
(i) 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.
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. A method for forming a photovoltaic device, comprising:
forming a low ohmic ZnTe contact layer over a superstrate or substrate, the low ohmic ZnTe contact layer doped with a p-type dopant;
forming a p-type layer comprising cadmium (Cd) and tellurium (Te) over the lower ohmic ZnTe layer;
forming an n-type CdZnTe layer over the p-type layer to form a p-n heterojunction or homojunction; and
forming a low ohmic contact layer comprising Cd and Te over the n-type CdZnTe layer.
5. The method of claim 4 , further comprising forming a ZnTe buffer layer over the superstrate or substrate before forming the low ohmic ZnTe contact layer.
6. The method of claim 4 , wherein the p-type layer and/or the n-type CdZnTe layer are compositionally graded.
7. A method for forming a photovoltaic device, comprising:
forming a low ohmic p-type ZnTe contact layer over a superstrate or substrate;
forming an intrinsic CdTe (i-CdTe) layer over the low ohmic p-type ZnTe layer; and
forming a low ohmic n-type CdTe contact layer over the i-CdTe layer.
8. The method of claim 7 , further comprising forming a ZnTe buffer layer over the superstrate or substrate before forming the low ohmic p-type ZnTe contact layer.
9. A method for forming a high performance single junction photovoltaic device, comprising:
forming a low ohmic CdTe contact layer over a superstrate or substrate;
forming an n-type layer comprising cadmium (Cd) and tellurium (Te) over the low ohmic CdTe layer;
forming a p-type CdZnTe layer over the n-type layer to form an n-p heterojunction or homojunction; and
forming a low ohmic p-type CdZnTe contact layer over the p-type CdZnTe layer.
10. The method of claim 9 , further comprising forming a ZnTe buffer layer over the superstrate or substrate before forming the low ohmic CdTe contact layer.
11. The method of claim 9 , wherein the p-type CdZnTe layer and/or the low ohmic CdZnTe layer are compositionally graded.
12. The method of claim 9 , wherein the superstrate or substrate is non-crystalline.
13. 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.
14. The method of claim 13 , wherein the photovoltaic device comprises a superstrate below the n-type layer.
15. The method of claim 13 , wherein the photovoltaic device comprises a superstrate above the p-type layer.
16. A method for forming a photovoltaic device, comprising:
forming a first layer over a non-crystalline superstrate or substrate, the first layer comprising tellurium (Te) and cadmium (Cd) or zinc (Zn);
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, wherein:
(i) 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; or
(ii) 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.
17. The method of claim 1 , 4 or 16 , wherein one or more layers of the photovoltaic device are formed at a deposition rate between about 6 micrometers/hour and 12 micrometers/hour.
18. The method of claim 1 , 4 or 16 , wherein one or more layers of the photovoltaic device are formed at a deposition temperature between about 200° C. and 400° C.