Melt growth of high-resistivity CdZnTe crystals by controlling Cd over-pressures

In this study, Cd1−xZnxTe crystals, with x=0.20, were grown unseeded by closed-ampoule vertical directional solidification (Bridgman) technique under controlled Cd over-pressures. CdZnTe crystals of high electrical resistivity have been reproducibly obtained with the In dopant concentration of 4–6 ppm, atomic and a Cd reservoir temperature between 785 and 825 °C. A combination of three process modifications have contributed to the accomplishment: (1) homogenizing the ampoules of starting materials under the vacuum environment to minimize contamination, (2) performing growth under controlled Cd over-pressures with the optimal In dopant, and (3) controlling post-growth cooling procedures to maintain uniformity of electrical properties over the crystal.