Preparation of CuInS2 thin films by sequential evaporation of In2S3 and CuS

CuInS2 thin films have been prepared by sequential evaporation of In2S3 and CuS. At a substrate temperature T-s = 100 degrees C an In2S3/CuS bilayer system is formed. After an increase of T-s to 215 degrees C we observed the formation of CuInS2. Post-growth treatment led to an improvement in crystallinity. The impact of the Cu-In-ratio, the post-growth annealing atmosphere, annealing temperature and annealing duration on the photoluminescence were investigated. For In-rich films two broad emissions at E = 1.368 eV and E = 1.412 eV were observed whereas Cu-rich films revealed three emissions at E = 1.369 eV, E = 1.462 eV and E = 1.501 eV. ZnO/CdS/CuInS2 solar cells were fabricated with efficiencies up to eta = 5.4 % (total area 0.5 cm(2)), given by an open circuit voltage of U-oc = 562 mV, a short-circuit current density of J(sc) = 14.4 mA/cm(2) and a fill factor of FF = 67 % under 100 mW/cm(2) AM1.5 illumination.