Studies of Cd-vacancies, indium dopant and impurities in CdZnTe crystals (Zn = 10%)

Using modified vertical Bridgman and a seeded technique, 3-inch-diameter CdZnTe (CZT) ingots were successfully grown with 40% of the ingots having single-crystal volumes of over 300 cm³, and 80% of the ingots with single-crystal volumes of over 100 cm³. High-yield growth of CZT crystals with these dimensions enables the production of novel monolithic, multi-element detectors. Defects such as Cd-vacancies, indium dopant and impurities were studied systematically. The studies show that by appropriately reducing the Cd-vacancy and the Group III dopant, one can increase the μτ(e) and μτ(h) products. Furthermore, the indium doping and the purity of the CZT were found to limit the value of the μτ(e) product. The "best" purity source material coupled with an optimized indium doping concentration will produce μτ(e) products as high as 1.8x10^-2 cm²/V (collimated and the "best" area), and the best μτ(h) is 7x10^-4 cm²/V.