CHALCOPYRITE CU(IN,GA)SE-2 AND DEFECT-CHALCOPYRITE CU(IN,GA)(3)SE-5 MATERIALS IN PHOTOVOLTAIC P-N-JUNCTIONS

Efficient photovoltaic action in polycrystalline solar cells based on Cu-In-Ga-Se materials is postulated to rely strongly on a chalcopyrite /defect-chalcopyrite interface. Growth and fundamental properties of s uch materials are discussed to understand better junction formation in such devices. A change in conductivity type (from n to p) has been ob served for the defect chalcopyrite materials with increased Ga content . Specifically, we found that the p-n nature of the interface in unifo rm Ga content absorbers is only possible at low Ga contents (< 30% rel ative to In). Furthermore, crystallographic data reveal significant di fferences in lattice size between both chalcopyrite materials as Ga is increased beyond 30% relative to In.