CADMIUM-FREE JUNCTION FABRICATION PROCESS FOR CuInSe2 THIN FILM SOLAR CELLS

摘要

The present invention provides an economical, simple, dry and controllable semiconductor layer junction forming process to make cadmium free high efficiency photovoltaic cells having a first layer (14) comprised primarily of copper indium diselenide having a thin doped copper indium diselenide n-type region, generated by thermal diffusion with a group II(a, b) element such as zinc, and a group VII element such as chlorine, and a second layer (20) comprised of a conventional zinc oxide bilayer. A photovoltaic device (10) according to the present invention includes a first thin film layer (14) of semiconductor material formed primarily from copper indium diselenide. Doping of the copper indium diselenide with zinc chloride is accomplished using either a zinc chloride solution or a solid zinc chloride material. Thermal diffusion of zinc chloride into the copper indium diselenide upper region creates the thin n-type copper indium diselenide surface. A second thin film layer (20) of semiconductor material comprising zinc oxide is then applied in two layers. The first layer (20a) comprises a thin layer of high resistivity zinc oxide. The second relatively thick layer (20b) of zinc oxide is doped to exhibit low resistivity.