The electrical properties of CdTe and Cd_(1-x)Zn_(x)Te crystals grown under excess tellurium by a modified Bridgman technique are critically dependent on the zinc content. Below an x value of 0.07, the as-grown CdZnTe crystals are n type while, above this value, CdZnTe crystals are p type. The origin of the shallow donor level at 0.01 eV below the conduction band is most likely singly ionized Te antisites (Te at Cd sites). The origin of the deep donor level at 0.75 eV below the conduction band is therefore doubly ionized tellurium antisites. Based on this model, the conduction type of CdZnTe crystals is determined by the results of compensation between the shallow donors of Te antisites and the shallow acceptors of Cd vacancies. High resistivity Cd_(0.9)Zn_(0.1)Te crystals are produced by compensating the p-type crystals with indium impurity at a low doping level of 1-5×10~(15) cm~(-3). At room temperature, CdZnTe radiation detectors can resolve the six low energy peaks in the ~(241)Am spectrum, a performance comparable to that of the best CdZnTe detectors reported.
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