Patent ID: 8236597

Claim:
A method for forming a thin film photovoltaic device, the method comprising: providing a transparent substrate comprising a surface region; forming a first electrode layer overlying the surface region; forming a copper layer overlying the first electrode layer; forming an indium layer overlying the copper layer to form a multi-layered structure; subjecting at least the multi-layered structure to a thermal treatment process in an environment containing a sulfur bearing species; forming a bulk copper indium disulfide material from at least the treatment process of the multi-layered structure, the bulk copper indium disulfide material comprising one or more portions of copper indium disulfide material characterized by a copper-to-indium atomic ratio of less than about 0.95:1 and the bulk copper indium disulfide material having a surface region characterized by a copper poor surface comprising a copper to indium atomic ratio of less than about 0.95:1; subjecting the copper poor surface and one or more portions of the bulk copper indium disulfide material to metal cation species to convert the copper poor surface from an n-type characteristic to a p-type characteristic and to convert any of the one or more portions of the bulk copper indium disulfide material having the copper-to-indium atomic ratio of less than about 0.95:1 from an n-type characteristic to a p-type characteristic; forming a window layer overlying the copper indium disulfide material; and whereupon the subjecting of the copper poor surface and the one or more portions of the bulk copper indium disulfide material is performed during at least a thermal treatment process for a time period.