NOVELTY - Method for selenization in fabricating copper indium diselenide semiconductor film involves forming electrode layer over surface region of substrate member; depositing precursor layer including copper, indium and gallium on sodium doping layer; placing substrate in annular chamber and introducing selenium gaseous species and carrier gas to form copper indium diselenide film; introducing sulfur species into annular chamber; heating and maintaining substrate member in environment having sulfur species to substitute 3-10% atomically of selenium gas species from film with sulfur species.    USE - In photovoltaic techniques for selenization in fabricating copper indium diselenide species (CIS), copper indium gallium diselenide species (CIGS) based thin film photovoltaic cell e.g. solar cell; also can be applied to cylindrical/tubular photovoltaic modules, non-planar surfaces, flexible sheets, building or window glass, roof tiles and automobiles.    ADVANTAGE - The method provides semiconductors based on copper indium diselenide configuration which can be used in thin film solar cell application because of their high optical absorption coefficients and versatile optical and electrical characteristics. Selenium allows for better uniformity across the layer and so the number of recombination sites in the film are reduced which benefits the quantum efficiency and thus the conversion efficiency. The flexibility in substrate shape selection provides huge cost-saving in production. The method can provide benefits over conventional techniques. In particular, the present system and process allow cost effective implementation; also the temperature control method maintains structure integrity of substrates while allowing various reactions to occur.    DETAILED DESCRIPTION - Method for selenization in fabricating copper indium diselenide semiconductor film involves providing substrate member having surface region; forming first electrode layer overlying surface region; sputtering sodium doping layer; depositing precursor layer which includes copper, indium and gallium over sodium doping layer; placing substrate in vertically oriented annular chamber; introducing gaseous species including selenium gas species and carrier gas into annular chamber; transferring thermal energy into annular chamber to increase its temperature to 350-450 degrees C to initiate formation of copper indium diselenide film from precursor layer; maintaining temperature for first period of time; suspending introduction of selenium gas species from annular chamber during first period of time; introducing sulfur species into annular chamber during first period of time; and increasing temperature at the end of first period of time from first temperature to second temperature of 500- 525 degrees C while substrate member is maintained in environment including sulfur species to substitute between 3-10% atomically of selenium gas species from copper indium diselenide film with sulfur species.    DESCRIPTION OF DRAWING(S) - The figure shows simplified diagram of method of selenization for forming copper indium diselenide film.