Drift mobility and photoluminescence measurements on high resistivity Cd_1−xZn_xTe crystals grown from Te-Rich solution

Abstract

The drift mobilities of chlorine doped high resistivity Cd_0.8Zn_0.2 Te have been investigated by using the time-of-flight technique. Electron as well as hole mobility in the as-grown crystals is limited by trap-controlled carrier transport. The energy locations of the defects responsible for carrier trapping are determined to be E_c- 0.03 and E_v+ 0.14 eV for electrons and holes, respectively. After annealing at 400°C for 80 h, no evidence of trap-controlled mobility was recognized for electrons. On the other hand, no significant change before and after the annealing was observed for hole transport. Those results and the change in the photoluminescence spectra before and after the annealing are explained by the complex defect model composed of the Cd vacancy and chlorine donor. Further, the alloy scattering potentials of ΔU_e and ΔU_h were estimated by employing the theoretical calculation method recently reported by D. Chattopadhyay [Solid State Commun. 91, 149 (1994)].