Cathodoluminescence and photoinduced current spectroscopy studies of defects in Cd_(0.8)Zn_(0.2)Te

Abstract

Deep levels in Cd_(1-x)Zn_xTe have not yet been fully characterized and understood, even though this material is very promising for medical and optoelectronic applications. We have investigated p-type semi-insulating Cd_(0.8)Zn_(0.2)Te with cathodoluminescence (CL) and photoinduced current transient spectroscopy (PICTS) methods. PICTS analyses allow detection of deep levels which are not revealed by other current spectroscopy techniques generally used, as they permit scanning of a wider region of the energy gap. Five levels have been detected (0.16, 0.25, 0.57, 0.78, and 1.1 eV) and, by combining the results obtained with the above-mentioned CL techniques, we were able to advance hypotheses on the character (donor or acceptor) and origin of some of these levels. The key role prayed by the 0.78-eV level in controlling the carrier transport properties has also been confirmed.