Copper indium gallium chalcogenide multilayer structure with optimized gallium content at its surface

Abstract

A method of forming a Group IBIIIAVIA solar cell absorber, which includes a top surface region of less than or equal to 300 nm depth. The Ga/(Ga+In) molar ratio within the top surface region is in the range of 0.1-0.3. The Group IBIIIAVIA solar cell absorber is formed by reacting the layers of a multilayer material structure which includes a metallic film including at least Cu and In formed on a base, a separator layer including Se is formed on the metallic film, a metallic source layer substantially including Ga formed on the separator layer, and a cap layer substantially including Se formed on the source layer.

1 - 23 . (canceled) 
     
     
         24 . A multilayer structure to form Group IBIIIAVIA absorber layers for solar cells, comprising:
 a base;   a substantially metallic film formed over the base, wherein the substantially metallic film includes Cu and In;   a separator layer formed over the substantially metallic film, the separator layer substantially comprises a Group VIA material;   a substantially metallic source layer formed over the separator layer, the source layer substantially comprises Ga; and   a cap layer formed over the source layer, the cap layer substantially comprises Se.   
     
     
         25 . The multilayer structure of  claim 24 , wherein the thickness of the substantially metallic film is in the range of 500-1000 nm, the thickness of the separator layer is in the range of 100-1000 nm, the thickness of the source layer is in the range of 20-100 nm, and the thickness of the cap layer is in the range of 800-3000 nm. 
     
     
         26 . The multilayer structure of  claim 25 , wherein the separator layer further a first additive material, wherein a ratio of the molar amount of the Group VIA material to the total molar amounts of the Group VIA material and the first additive material is in the range of 0.95-1.0. 
     
     
         27 . The multilayer structure of  claim 26 , wherein the Group VIA material comprises at least one of Se and Te, and the first additive material comprises at least one of Cu, In, Ga, and a dopant material selected from the group of Na, K and Li. 
     
     
         28 . The multilayer structure of  claim 25 , wherein the source layer further comprises a second additive material, wherein a ratio of the molar amount of Ga to the total molar amounts of Ga and the second additive material is in the range of 0.7-1.0. 
     
     
         29 . The multilayer structure of  claim 28 , wherein the second additive material comprises at least one of Cu, In, and a dopant material selected from the group of Na, K and Li. 
     
     
         30 . The multilayer structure of  claim 25 , wherein the cap layer further comprises a third additive material and a ratio of the molar amount of Se to the total molar amounts of Se and the first additive material is in the range of 0.95-1.0. 
     
     
         31 . The multilayer structure of  claim 30 , wherein the third additive material comprises at least one of Te and a dopant material selected from the group of Na, K and Li. 
     
     
         32 . The multilayer structure of  claim 25 , wherein the base comprises a substrate and a contact layer and the substantially metallic film is on the contact layer. 
     
     
         33 . The multilayer structure of  claim 32 , wherein the substrate comprises one of glass sheet, polyimide foil, stainless steel foil and aluminum alloy foil, and the contact layer comprises Mo. 
     
     
         34 . The multilayer structure of  claim 24 , wherein the substantially metallic film further comprises Ga. 
     
     
         35 . The multilayer structure of  claim 34 , wherein the substantially metallic film further comprises a fourth additive material, wherein a ratio of the molar amount of In to the total molar amounts of In, Cu, Ga and the fourth additive material is in the range of 0.25-0.6. 
     
     
         36 . The multilayer structure of  claim 35 , wherein the fourth additive material comprises at least one dopant material selected from the group of Na, K and Li. 
     
     
         37 . The multilayer structure of  claim 34 , wherein the molar ratio of Cu/(In+Ga) in the substantially metallic film is in the range of 0.8-1.0. 
     
     
         38 . The multilayer structure of  claim 24 , wherein at least one of separator, source and cap layers includes a dopant film including one of Na, K and Li. 
     
     
         39 . The multilayer structure of  claim 38 , wherein the thickness of the dopant film is in the range of 5-20 nm.