ELECTRICAL CHARACTERIZATION OF ALL-SPUTTERED CDS/CUINSE2 SOLAR-CELL HETEROJUNCTIONS

Current-voltage (J-V) and capacitance-frequency (C-F) measurements were taken for all-sputtered CdS/CuInSe2 solar cell heterojunctions, in the range 100 Hz - 10 MHz, to investigate the effect of interface states on the conduction mechanism. The samples analyzed had different compositions for the chalcopyrite CuInSe2 layer. All of the samples showed a hybrid tunneling/interface recombination mechanism with the major contribution coming from the interface recombination mechanism for devices having a stoichiometric or indium-rich CuInSe2 layer, and from the tunneling conduction mechanism for copper-rich devices. An estimation of the relative distribution of interface states has been performed. The values obtained for interface state density were as high as 6 × 1012 V-1 cm-2 for copper-rich heterojunctions, and were lower than 2 × 1011 V-1 cm-2 for devices having a stoichiometric or indium-rich CuInSe2 layer. © 1990.