NOVELTY - Thin film photovoltaic device includes an n-type, wide band gap, thin film window layer (703) of a semiconductor material; an n-type thin film semiconductor photon absorber layer (704); a back metal contact; and thin protective layer between the absorber layer and the metal contact. The protective layer protects the photon absorber layer from chemically reacting with the metal contact.    USE - Used as thin film photovoltaic device, e.g. solar cell (701).    ADVANTAGE - The photovoltaic device has improved performance efficiencies. Specifically, the photon absorber layer enhances the n-type electrical conduction, and increases the height of the Schottky barrier. The device provides open circuit voltage over 600 mV, fill factors of 0.45, short circuit current density over 60 mA/cm2, and efficiency of 18 %.    DETAILED DESCRIPTION - A thin film photovoltaic device includes an n-type, wide band gap, thin film window layer (703) of a semiconductor substrate (702); an n-type thin film semiconductor photon absorber layer (704) specifically deposited on the window layer to operate as an n-type layer; a back metal contact; and thin protective layer between the absorber layer and the back metal contact (705). The absorber layer includes a compound consisting of Class II B element and Group VI element containing compounds, and Group III and V elements containing compounds. The protective layer protects the photon absorber layer from chemically reacting with the metal contact. An INDEPENDENT CLAIM is also included for fabricating a thin film photovoltaic device by configuring an n-type, wide band gap, thin film window layer of a semiconductor substrate material; depositing a thin film of an n-type semiconductor photon absorber compound on the substrate layer; forming a thin protective layer on the outer surface of the photon absorber layer; and fixing a back metal contact to the protective layer so that the protective layer is intermediate to the photon absorber layer and the metal contact and protects the photon absorber layer from chemically reacting with the metal contact.    DESCRIPTION OF DRAWING(S) - The figure shows cadmium chalcogenides based solar cell.    Solar cell (701)    Substrate (702)    Window layer (703)    Photon absorber layer (704)    Metal contact (705)