Phase diagram of the CuIn-2Se system for CuInSe2 crystal growth by controlling Se contents

The detailed phase diagram of a CuIn-2Se system is indispensable to control Se contents in owing CuInSe2 bulk single crystals by the selenization method. The phase diagram is constructed by the differential thermal analysis (DTA) and powder X-ray diffraction measurements. The solidifying point in the composition ranging from CuInSe2 to CuInSe3 decreases by more than 100 degrees C with increasing the Se content, and the samples do not contain heterogeneous phases. In addition, the Se vapor pressure dependence of the solidifying point of CuInSe2 is investigated by the DTA measurement, using a electric furnace with two temperature zones. The solidifying point decreases by about 130 degrees with increasing the Se vapor pressure up to 760 Torr. It is shown that the high-quality bulk single crystals with controlled Se content can be grown by controlling the Se vapor pressure.