Ohmic contact of thin film solar cell

Abstract

A chalcogen-resistant material including at least one of a conductive elongated nanostructure layer and a high work function material layer is deposited on a transition metal layer on a substrate. A semiconductor chalcogenide material layer is deposited over the chalcogen-resistant material. The conductive elongated nanostructures, if present, can reduce contact resistance by providing direct electrically conductive paths from the transition metal layer through the chalcogen-resistant material and to the semiconductor chalcogenide material. The high work function material layer, if present, can reduce contact resistance by blocking chalcogenization of the transition metal in the transition metal layer. Reduction of the contact resistance can enhance efficiency of a solar cell including the chalcogenide semiconductor material.

What is claimed is: 
     
         1 . A semiconductor structure comprising:
 a transition metal layer comprising at least one transition metal element and located on a substrate;   a plurality of conductive elongated nanostructures in contact with a surface of said transition metal layer; and   a semiconductor chalcogenide material layer in contact with said plurality of conductive elongated nanostructures.   
     
     
         2 . The semiconductor structure of  claim 1 , further comprising a transition metal chalcogenide layer comprising a chalcogenide of said at least one transition metal element and in contact with said semiconductor chalcogenide material and said transition metal layer. 
     
     
         3 . The semiconductor structure of  claim 2 , wherein first portions of said plurality of conductive elongated nanostructures are embedded within said transition metal chalcogenide layer, and second portions of said plurality of conductive elongated nanostructures are embedded in said semiconductor chalcogenide material layer. 
     
     
         4 . The semiconductor structure of  claim 1 , further comprising a high work function transition metal element layer comprising at least one elemental metal having a work function greater than 4.6 eV and greater than any work function of said at least one transition metal element, and contacting a surface of said semiconductor chalcogenide material layer and a surface of said transition metal layer. 
     
     
         5 . The semiconductor structure of  claim 4 , wherein first portions of said plurality of conductive elongated nanostructures are embedded within said high work function transition metal element layer, and second portions of said plurality of conductive elongated nanostructures are embedded in said semiconductor chalcogenide material layer. 
     
     
         6 . The semiconductor structure of  claim 4 , wherein said high work function transition metal element layer comprises at least one element selected from Group VIIIB elements, Group IB elements, and Re. 
     
     
         7 . The semiconductor structure of  claim 4 , wherein said high work function transition metal element layer comprises at least one element selected from Co, Ru, Rh, Pd, Os, Ir, Pt, and Au. 
     
     
         8 . The semiconductor structure of  claim 1 , wherein said semiconductor chalcogenide material is a semiconductor sulfide material. 
     
     
         9 . The semiconductor structure of  claim 1 , wherein said at least one transition metal element comprises molybdenum. 
     
     
         10 . The semiconductor structure of  claim 1 , wherein said plurality of conductive elongated nanostructures is predominantly metallic, and has a random distribution of spatial orientations. 
     
     
         11 . The semiconductor structure of  claim 1 , wherein said transition metal layer consists essentially of said at least one transition metal element. 
     
     
         12 . The semiconductor structure of  claim 11 , wherein said at least one transition metal element is selected from Nb, V, Zn, Ti, Mo, Cr, and W. 
     
     
         13 . The semiconductor structure of  claim 1 , wherein said semiconductor chalcogenide material layer includes a p-n junction therein. 
     
     
         14 . The semiconductor structure of  claim 1 , wherein said semiconductor chalcogenide material layer comprises at least one of CuIn(Se,S) 2  (CIS), CuInGaSe 2  (CIGS), Cu 2 (Zn,Fe)Sn(S,Se) 4 , Ga(S,Se), GaTe, GaAs, In 2 (S,Se) 3 , and InTe, InP, CdTe, Cd(S, Se), ZnTe, Zn 3 P 2 , Pb(Se,S), Zn(S, Se), W(S,Se) 2 , Bi 2 S 3 , Ag 2 S, NiS, ZnO, Cu 2 O, CuO, Cu 2 S, FeS 2 . 
     
     
         15 . The semiconductor structure of  claim 1 , wherein said substrate is selected from an insulator substrate including a dielectric material and a metallic substrate including a diffusion barrier layer on the top surface thereof. 
     
     
         16 . A semiconductor structure comprising:
 a transition metal layer comprising at least one transition metal element and located on a substrate;   a high work function transition metal element layer comprising at least one elemental metal having a work function greater than 4.6 eV and contacting a surface of said transition metal layer, wherein said at least one transition metal element has a work function less than any work function of said at least one elemental metal; and   a semiconductor chalcogenide material layer in contact with said high work function transition metal element layer.   
     
     
         17 . The semiconductor structure of  claim 16 , wherein said high work function transition metal element layer consists essentially of said at least one elemental metal, has a contiguous bottom surface contacting said transition metal layer, and has a contiguous top surface contacting said semiconductor chalcogenide material layer. 
     
     
         18 . The semiconductor structure of  claim 16 , further comprising a plurality of conductive elongated nanostructures embedded in said high work function transition metal element layer. 
     
     
         19 . The semiconductor structure of  claim 18 , wherein said plurality of conductive elongated nanostructures is in contact with a surface of said transition metal layer, and includes portions that are embedded in said semiconductor chalcogenide material layer. 
     
     
         20 . The semiconductor structure of  claim 16 , wherein said high work function transition metal element layer comprises at least one of platinum and ruthenium. 
     
     
         21 . The semiconductor structure of  claim 16 , wherein said high work function transition metal element layer comprises at least one element selected from Group VIIIB elements, Group IB elements, and Re. 
     
     
         22 . The semiconductor structure of  claim 16 , wherein said high work function transition metal element layer comprises at least one element selected from Co, Ru, Rh, Pd, Os, Ir, Pt, and Au. 
     
     
         23 . The semiconductor structure of  claim 16 , wherein said semiconductor chalcogenide material is a semiconductor sulfide material. 
     
     
         24 . The semiconductor structure of  claim 16 , wherein said transition metal layer consists essentially of said at least one transition metal element. 
     
     
         25 . The semiconductor structure of  claim 16 , wherein said semiconductor chalcogenide material layer includes a p-n junction therein.