Tellurium Secondary-Phase Defects in CdZnTe and their Association With the 1.1-eV Deep Trap

Abstract

Defects located at the EC - 1.1 (eV) level, which are electro-optically active deep traps, generally have been overlooked since their presence cannot be detected except for those in highly resistive CdTe compounds. The origin of this trap is still debated on whether it is from Te vacancies or from dislocations induced by secondary phase defects in Te. We have grown high-resistivity Te-rich CZT ingots to clarify the origin of the 1.1 eV defects and to analyze the defect levels in the CZT samples by current deep level transient spectroscopy (I-DLTS) and photoluminescence (PL). From the analysis, defect levels such as shallow acceptor/donor, A-centers, Cd vacancies and Te antisite appeared to be in both high and low concentrations of Te inclusions, but the level of 1.1-eV defects exhibited dependence on the density of Te inclusion in the CZT samples. We also evaluated the effect of the 1.1-eV deep-level defects on the detector's performance in point view of carrier trapping and de-trapping.