Laser Diagnostics of Cadmium Telluride: Crystal Quality and Exciton Dynamics

Abstract

Cadmium telluride is a II-VI semiconductor of increasing interest because of the use of its ternary alloy HgCdTe as a tunable-bandgap IR detector material. CdTe is often used as a substrate for the growth of HgCdTe epilayers and the detector performance depends upon the purity and crystal quality of both the epilayer and substrate.[1] Laser diagnostics of CdTe make possible the nondestructive screening of detector materials. In many cases electronic properties such as donor and acceptor concentrations can be determined without contact fabrication. Here we present both CW and time-resolved low-temperature spectra of CdTe. The CW spectra are useful for evaluating the crystal quality and the photoluminescence (PL) decays represent the first time-resolved results on single crystal CdTe.