Photovoltaic Devices Including Nitrogen-Containing Metal Contact

Abstract

A photovoltaic cell can include a nitrogen-containing metal layer in contact with a semiconductor layer.

What is claimed is: 
     
         1 . A method of manufacturing a photovoltaic cell comprising:
 forming a first semiconductor layer over a substrate, wherein the first semiconductor layer comprises CdTe, CdSe, or mixtures thereof;   forming a second layer over the first semiconductor layer, wherein the second layer comprises CdO;   depositing a metal layer over the second layer in the presence of nitrogen to form a nitrogen-containing metal layer in contact with the second layer, wherein the nitrogen-containing metal layer includes an aluminum nitride, a molybdenum nitride, a nickel nitride, a titanium nitride, a tungsten nitride, a selenium nitride, a tantalum nitride, or a vanadium nitride;   depositing an aluminum layer over the nitrogen-containing metal layer; and   depositing a chromium layer over the aluminum layer.   
     
     
         2 . The method of  claim 1 , further comprising:
 placing a transparent conductive layer on the substrate; and   placing a capping layer between the transparent conductive layer and the first semiconductor layer.   
     
     
         3 . The method of  claim 1 , wherein the step of depositing the metal layer over the second layer in the presence of nitrogen further comprises: sputtering in a nitrogen gas mixture comprising 2% to 50% nitrogen. 
     
     
         4 . The method of  claim 1 , wherein the step of depositing the metal layer over the second layer in the presence of nitrogen further comprises: sputtering in a nitrogen argon gas mixture composed of 13% nitrogen and 87% argon. 
     
     
         5 . The method of  claim 1 , wherein the nitrogen-containing metal layer comprises an atomic percent nitrogen in a range between 1 percent and 50 percent. 
     
     
         6 . The method of  claim 1 , wherein the nitrogen-containing metal layer comprises an atomic percent nitrogen greater than 50 percent. 
     
     
         7 . The method of  claim 1 , further comprising transporting the substrate into a series of one or more deposition stations on a conveyor, wherein at least one deposition station comprises a deposition chamber heated to a processing temperature in a range from about 450° C. to about 700° C. 
     
     
         8 . The method of  claim 1 , wherein the nitrogen-containing metal layer includes a non-stoichiometric nitride. 
     
     
         9 . A method of manufacturing a photovoltaic cell comprising:
 forming a first semiconductor layer over a substrate, wherein the first semiconductor layer comprises CdTe, CdSe, or mixtures thereof;   forming a second semiconductor layer over the first semiconductor layer, wherein the second semiconductor layer comprises Zn;   depositing a metal layer over the second semiconductor layer in the presence of nitrogen to form a nitrogen-containing metal layer, wherein the nitrogen-containing metal layer includes an aluminum nitride, a molybdenum nitride, a nickel nitride, a titanium nitride, a tungsten nitride, a selenium nitride, a tantalum nitride, or a vanadium nitride;   depositing an aluminum layer over the nitrogen-containing metal layer; and   depositing a chromium layer over the aluminum layer.   
     
     
         10 . The method of  claim 9 , wherein the second semiconductor layer comprises ZnTe. 
     
     
         11 . The method of  claim 9 , wherein the second semiconductor layer comprises ZnSe. 
     
     
         12 . The method of  claim 9 , wherein the second semiconductor layer comprises ZnO. 
     
     
         13 . The method of  claim 9 , wherein the nitrogen-containing metal layer comprises titanium nitride. 
     
     
         14 . The method of  claim 9 , wherein the nitrogen-containing metal layer comprises molybdenum nitride. 
     
     
         15 . The method of  claim 9 , wherein the step of depositing the metal layer over the second layer in the presence of nitrogen further comprises: sputtering in a nitrogen gas mixture comprising 2% to 50% nitrogen. 
     
     
         16 . The method of  claim 9 , wherein the nitrogen-containing metal layer comprises an atomic percent nitrogen greater than 50 percent. 
     
     
         17 . A method of manufacturing a photovoltaic cell comprising:
 forming a first semiconductor layer over a substrate, wherein the first semiconductor layer comprises CdTe, CdSe, or mixtures thereof;   forming a second semiconductor layer over the first semiconductor layer, wherein the second semiconductor layer comprises ZnTe;   depositing a metal layer over the second semiconductor layer in the presence of nitrogen to form a nitrogen-containing metal layer in contact with the second semiconductor layer, wherein the nitrogen-containing metal layer includes an aluminum nitride, a molybdenum nitride, a nickel nitride, a titanium nitride, a tungsten nitride, a selenium nitride, a tantalum nitride, or a vanadium nitride.   
     
     
         18 . The method of  claim 17 , further comprising:
 placing a transparent conductive layer on the substrate; and   placing a capping layer between the transparent conductive layer and the first semiconductor layer.   
     
     
         19 . The method of  claim 18 , wherein the transparent conductive layer comprises tin oxide. 
     
     
         20 . The method of  claim 17 , wherein the nitrogen-containing metal layer comprises titanium nitride.