Transparent conductive electrode for three dimensional photovoltaic device

Abstract

A method for forming a photovoltaic device includes forming a plurality of three-dimensional structures in a substrate to form a textured profile. A first transparent electrode layer is formed on the structures from a transparent conductive oxide having a metal dopant and deposited at a thickness configured to maintain the textured profile. The first transparent electrode layer is annealed to increase conductivity and transmittance. A continuous photovoltaic stack including an N-type layer, a P-type layer and an intrinsic layer is formed on the first transparent electrode layer. A second electrode layer is deposited over the photovoltaic stack.

What is claimed is: 
     
         1 . A method for forming a photovoltaic device, comprising:
 forming a plurality of three-dimensional structures in a substrate to form a textured profile;   forming a first transparent electrode layer on the structures from a transparent conductive oxide doped with a metal and deposited at a thickness configured to maintain the textured profile;   annealing the first transparent electrode layer to increase conductivity and transmittance;   forming a continuous photovoltaic stack including an N-type layer, a P-type layer and an intrinsic layer on the first transparent electrode layer; and   depositing a second electrode layer over the photovoltaic stack.   
     
     
         2 . The method as recited in  claim 1 , wherein the thickness configured to maintain the textured profile includes a thickness of less than 450 nm and maintains the textured profile. 
     
     
         3 . The method as recited in  claim 1 , wherein the textured profile includes conically shaped peaks having non-perpendicular lateral surfaces configured to provide light trapping. 
     
     
         4 . The method as recited in  claim 1 , wherein the first transparent conductive oxide includes ZnO and the metal includes Al. 
     
     
         5 . The method as recited in  claim 1 , wherein forming the first transparent electrode layer includes depositing a ZnO:Al layer at about 300 nm in thickness and the step of annealing comprises annealing the first transparent electrode layer to activate the Al to increase the conductivity. 
     
     
         6 . The method as recited in  claim 1 , wherein the first transparent electrode layer is deposited over the structures on non-planar surfaces and the step of annealing includes annealing the first transparent electrode layer to increase conductivity and transmittance to at least equal to a planar formed layer of a same transparent conductive oxide material. 
     
     
         7 . The method as recited in  claim 1 , wherein the step of annealing includes annealing the first transparent electrode layer at a temperature of between about 300 degrees to about 600 degrees Celsius. 
     
     
         8 . The method as recited in  claim 1 , wherein the step of annealing includes annealing the first transparent electrode layer for a duration of between 5 seconds and 90 seconds. 
     
     
         9 . The method as recited in  claim 1 , wherein the second electrode layer includes a transparent conductive oxide material and the method further comprises:
 annealing the second electrode layer to increase conductivity and transmittance and maintain the textured profile.   
     
     
         10 . The method as recited in  claim 1 , wherein the second electrode layer includes a thickness of less than 500 nm and is configured to maintain the textured profile. 
     
     
         11 . A method for forming a photovoltaic device, comprising:
 forming a plurality of three-dimensional structures in a substrate to form a textured profile, the textured profile including conically shaped peaks having non-perpendicular lateral surfaces configured to provide light trapping;   depositing a first transparent electrode layer on the structures, from a transparent conductive oxide having a metal dopant, at a thickness configured to maintain the textured profile, the thickness configured to maintain the textured profile including a thickness of less than 450 nm;   annealing the first transparent electrode layer at a temperature of between about 300 degrees to about 600 degrees Celsius and a duration of between 5 seconds and 90 seconds to increase conductivity and transmittance;   forming a continuous photovoltaic stack including an N-type layer, a P-type layer and an intrinsic layer on the first transparent electrode layer; and   depositing a second electrode layer over the photovoltaic stack.   
     
     
         12 . The method as recited in  claim 11 , wherein the first transparent conductive oxide includes ZnO and the metal dopant includes Al. 
     
     
         13 . The method as recited in  claim 11 , wherein forming the first transparent electrode layer includes depositing a ZnO:Al layer at about 300 nm in thickness and the step of annealing comprises annealing the first transparent electrode layer to activate the Al to increase the conductivity. 
     
     
         14 . The method as recited in  claim 11 , wherein the first transparent electrode layer is deposited over the structures on non-planar surfaces and the step of annealing includes annealing the first transparent electrode layer to increase conductivity and transmittance to at least equal to a planar formed layer of a same transparent conductive oxide material. 
     
     
         15 . The method as recited in  claim 11 , wherein the second electrode layer includes a transparent conductive oxide material and the method further comprises:
 annealing the second electrode layer to increase conductivity and transmittance and maintain the textured profile.   
     
     
         16 . The method as recited in  claim 11 , wherein the second electrode layer includes a thickness of less than 500 nm and is configured to maintain the textured profile. 
     
     
         17 . A method for forming a photovoltaic device, comprising:
 forming a plurality of three-dimensional structures in a substrate to form a textured profile, the textured profile including conically shaped peaks having non-perpendicular lateral surfaces configured to provide light trapping;   depositing a ZnO:Al layer on the structures including over non-planar surfaces at a thickness configured to maintain the textured profile, the thickness ranging between about 100 nm and about 350 nm;   annealing the first transparent electrode layer at a temperature of between about 300 degrees to about 600 degrees Celsius and duration of between 5 seconds and 90 seconds to activate the Al to increase conductivity and to increase transmittance;   forming a continuous photovoltaic stack including an N-type layer, a P-type layer and an intrinsic layer on the first transparent electrode layer; and   depositing a second electrode layer over the photovoltaic stack.   
     
     
         18 . The method as recited in  claim 17 , wherein forming the ZnO:Al layer includes a thickness of about 300 nm. 
     
     
         19 . The method as recited in  claim 17 , and the step of annealing includes annealing the ZnO:Al layer to increase conductivity and transmittance to at least equal to a planar formed ZnO:Al layer. 
     
     
         20 . The method as recited in  claim 17 , wherein the second electrode layer includes a transparent conductive oxide material and the method further comprises:
 annealing the second electrode layer to increase conductivity and transmittance and maintain the textured profile.   
     
     
         21 . The method as recited in  claim 17 , wherein the second electrode layer includes a thickness of less than 500 nm and is configured to maintain the textured profile.