ELECTRICAL AND OPTICAL-PROPERTIES OF CUINSE2 SINGLE-CRYSTALS PREPARED BY 3-TEMPERATURE-HORIZONTAL BRIDGMAN METHOD

Single crystals of CuInSe2 have been prepared by the three-temperature-horizontal Bridgman method. The crystals prepared under pressure higher than 10 Torr show p-type conduction and have a single phase, while those prepared under lower pressure show n-type conduction and contain a CuIn alloy phase. The crystals prepared under Se vapor pressure of 10 Torr have the largest Hall mobility and the smallest carrier concentration of all p-type crystals. The band tail spreads towards the low-energy side with increasing Se vapor pressure. It is considered that the p-type crystals have the acceptor level of similar to 40 meV due to V-Cu, and the donor level due to In-Cu for Se vapor pressures higher than 25 Torr or due to V-Se for Se vapor pressure of 10 Torr.