Chemical reaction process and the single crystal growth of CuInS2 compound

In order to establish the preparation method of high-quality CuInS2 single crystals, we have investigated the chemical reaction process by means of differential thermal analysis and powder X-ray diffraction measurements. In the chemical reaction process of a Cu + In + 2S mixture, an explosive exothermic reaction occurs at 640 degrees C, which is ascribed to the formation of products of the In-S system. In the case of a CuIn + 2S mixture, an explosive sulfurization reaction occurs at about 700 degrees C, leading to the CuInS2 phase. The melting point decreases by 17 degrees C under S vapor pressure increasing from 200 Torr to 8 atm. The formation of heterogeneous products are greatly suppressed by the sulfurization of CuIn alloy at temperatures higher than 750 degrees C. In conclusion, high-quality bulk single crystals can be grown by the sulfurization horizontal Bridgeman method with controlling S vapor pressure. (C) 1999 Elsevier Science B.V. All rights reserved.