Microwave synthesis, single crystal growth and characterization of ZnTe

ZnTe has been synthesized for the first time by microwave heating from high purity Zn and Te and the minimum reaction time determined to be 30 min. Single crystals were grown by modified vertical Bridgman technique from 4% rich Te melt, the growth direction being found to be [111]. XRD showed formation of the zincblende phase with lattice constant 6.106 Angstrom. Inductively coupled plasma (ICP) analysis showed Si, In, Cu, Au and Fe to be the main impurities present at ppm level. Crystals were p-type with resistivity 8.5 Ohm cm, hole concentration 1.6 x 10(16) cm(-3) and mobility 46 cm(2)/V s at 300 K. Mobility was found to vary with temperature as mu(p) proportional to T-2.7 in the range 120-300 K. Photoluminescence (PL) at 10 K showed emission peaks at 2.06, 1.47, 1.33 and 1.05 eV. Thermal quenching of the PL bands has been studied. The samples showed weak photoconductivity due to small minority carrier lifetime. From the temperature dependence of the photoconductive gain, the minority carrier lifetime (tau(n)) has been determined in the temperature range of 80-300 K. tau(n) was thus found to go through a maximum of 4.5 x 10(-7) s at 220 K and its variation with temperature is also discussed. (C) 1998 Elsevier Science B.V. All rights reserved.