Photovoltaic device with a zinc magnesium oxide window layer
View Patent ↗Methods and devices are described for a photovoltaic device and substrate structure. In one embodiment, a photovoltaic device includes a substrate structure and a CdTe absorber layer, the substrate structure including a Zn 1-x Mg x O window layer and a low conductivity buffer layer. Another embodiment is directed to a process for manufacturing a photovoltaic device including forming a Zn 1-x Mg x O window layer over a substrate by at least one of sputtering, evaporation deposition, CVD, chemical bath deposition process and vapor transport deposition process. The process including forming a CdTe absorber layer above the Zn 1-x Mg x O window layer.
1. A photovoltaic device comprising:
a transparent glass substrate;
a transparent conductive oxide layer;
a Zn 1-x Mg x O semiconductor window layer, wherein 0<x<1 and the transparent conductive oxide layer is between the transparent glass substrate and the Zn 1-x Mg x O semiconductor window layer;
a buffer layer between the transparent conductive oxide layer and the Zn 1-x Mg x O semiconductor window layer; and
a semiconductor absorber layer on the Zn 1-x Mg x O semiconductor window layer, wherein the semiconductor absorber layer comprises cadmium and tellurium, and wherein x is tuned such that the conduction band offset of the Zn 1-x Mg x O semiconductor window layer with respect to the semiconductor absorber layer that comprises cadmium and tellurium is in the range of 0 to +0.4 eV;
wherein the Zn 1-x Mg x O semiconductor window layer is doped with Mn, Nb, N, F or by introducing oxygen vacancies.
2. The photovoltaic device of claim 1 , wherein the Zn 1-x Mg x O semiconductor window layer is on the buffer layer.
3. The photovoltaic device of claim 1 , wherein the thickness of the Zn 1-x Mg x O semiconductor window layer ranges from about 2 nm to about 2000 nm.
4. The photovoltaic device of claim 1 , wherein the conductivity of the Zn 1-x Mg x O semiconductor window layer is within a range of about 1 mOhm per cm to about 10 Ohm per cm.
5. The photovoltaic device of claim 1 , further comprising a barrier layer between the glass substrate and the transparent conductive oxide layer.
6. The photovoltaic device of claim 1 , wherein the Zn 1-x Mg x O semiconductor window layer has a dopant concentration of between about 1×10 14 cm −3 and about 1×10 19 cm −3 .
7. The photovoltaic device of claim 1 , wherein the Zn 1-x Mg x O semiconductor window layer has a dopant concentration of between about 1×10 17 cm −3 and about 1×10 18 cm −3 .
8. A method of forming a photovoltaic device, the method comprising:
forming a transparent conductive oxide layer over a transparent glass substrate;
forming a Zn 1-x M x O semiconductor window layer over the transparent conduct oxide layer, wherein 0<x<1 and the transparent conductive oxide layer is between the transparent glass substrate and the Zn 1-x Mg x O semiconductor window layer;
forming a buffer layer between the transparent conductive oxide layer and the Zn 1-x Mg x O semiconductor window layer; and
forming a semiconductor absorber layer over the Zn 1-x Mg x O semiconductor window layer, wherein the semiconductor absorber layer comprises cadmium and tellurium, and wherein x is tuned such that the conduction band offset of the Zn 1-x Mg x O semiconductor window layer with respect to the semiconductor absorber layer that comprises cadmium and tellurium is in the range of 0 to +0.4 eV; and
doping the Zn 1-x Mg x O semiconductor window layer with Mn, Nb, N, F or by introducing oxygen vacancies.
9. The method of claim 8 further comprising forming a second semiconductor window layer between the Zn 1-x Mg x O semiconductor window layer and the semiconductor absorber layer, wherein the second semiconductor window layer comprises cadmium sulfide.
10. The method of claim 8 , wherein the semiconductor absorber layer is on the Zn 1-x Mg x O semiconductor window layer.
11. The method of claim 8 , wherein the Zn 1-x Mg x O semiconductor window layer has a dopant concentration of between about 1×10 14 cm −3 and about 1×10 19 cm −3 .
12. The method of claim 8 , wherein the Zn 1-x Mg x O semiconductor window layer has a dopant concentration of between about 1×10 17 cm −3 and about 1×10 18 cm −3 .
13. The method of claim 8 , wherein the Zn 1-x Mg x O semiconductor window layer is formed by at least one of sputtering, evaporation deposition, CVD, chemical bath deposition process and vapor transport deposition process.
14. The method of claim 8 , wherein the Zn 1-x Mg x O semiconductor window layer is formed such that its conductivity is within a range of about 1 mOhm per cm to about 10 Ohm per cm.