Patent ID: 8344243

Claim:
A method for forming a thin film photovoltaic device comprising: providing a transparent substrate having a surface; forming a first electrode layer over the surface; depositing a barrier layer over the first electrode layer to protect the first electrode layer from contamination; forming a copper layer over the barrier layer; forming an indium layer over the copper layer to form a multi-layered structure comprising the copper layer and the indium layer; subjecting the multi-layered structure to a thermal treatment process in an environment containing a sulfur bearing species to thereby form bulk copper indium disulfide material, the bulk copper indium disulfide material comprising a copper poor surface region with n-type impurity characteristic, wherein the copper poor surface region comprises a copper to indium atomic ratio of less than about 0.95:1; exposing the bulk copper indium disulfide material to an aluminum species to form a p-type copper indium aluminum disulfide material; forming a high resistivity transparent material over the copper indium aluminum disulfide material; and forming a second electrode layer having a p-type impurity characteristic over the high resistivity transparent layer.