Self-Compensation of Conductionin Cd0.95Zn0.05Te:Cl Crystals in a Wide Range of Cd Vapor Pressures

Abstract

The process of self-compensation in Cd0.95Zn0.05Te:Cl solid-solution crystals has been studied by annealing single crystals under a controlled Cd vapor pressure, with subsequent measurements of the Hall effect, photoluminescence, carrier lifetime and mobility, and photocurrent memory in the annealed crystals. By means of this annealing, conditions of thermal treatment that make it possible to fabricate low-conductivity samples with a low carrier density, 10E7-10E11 cm-3, are denned. In these samples, a p -- n conduction inversion is observed at a higher free-carrier density ((n, p) near 10E9 cm-3) and the dependence of the electron density on the Cd vapor pressure exhibits a more gentle slope than in the case of CdTe:Cl crystals. The obtained data are dis-cussed in terms of a self-compensation model in which intrinsic point defects act as acceptors with deep levels. This level is attributed to a Zn vacancy, which remains active at high Cd pressure.