PREPARATION OF CUGASE2 THIN-FILM SOLAR-CELLS COMPRISING AN ELECTROCHEMICAL GALLIUM DEPOSITION STEP

Thin film CuGaSe2 solar cells were prepared from the elements using el ectrochemical deposition of Ga from an alkaline bath. Sputtered copper layers with a small gallium content (Cu0.86Ga0.14) on Mo/soda-lime gl ass served as a substrate. Subsequent reactive annealing of the thus c reated Cu/Ga precursor layer with selenium vapour yielded CuGaSe2. Cha lcopyrite phase formation was studied with XRD, micro-Raman spectrosco py, SEM-EDX and Auger electron spectroscopy. It was concluded from the se measurements that the binary phases Cu2Se and Ga2Se3 are generated prior to the formation of the favoured CuGaSe2 phase. Complete solar c ell structures were fabricated by chemical bath deposition of CdS and chemical vapour deposition of ZnO onto the CuGaSe2 absorber layer. Pro mising 3.2% efficiency with U-oc = 542 mV, I-sc = 12.0 mA/cm(2) and FF = 0.49 were achieved, proving that electrochemical gallium deposition from an aqueous bath can contribute to the efficient thin film proces sing of chalcopyrite solar cells.