Charge trapping in detector grade thallium bromide and cadmium zinc telluride: Measurement and theory

Carrier trapping times were measured in detector grade thallium bromide (TlBr) and cadmium zinc telluride (CZT) from 300 to 110 K and the experimental data were analyzed using a trapping model. In CZT, because the majority carrier concentration is close to the intrinsic carrier concentration, the trapping time increases exponentially as the temperature decreases below about 160 K. In TlBr, the majority carrier concentration is many orders of magnitude greater than the intrinsic carrier concentration and the trapping time followed a (1/T)1/2 temperature dependence over the range of temperatures studied. The results of the model suggest that a moderately deep compensation center could be used to significantly increase the room temperature trapping time in TlBr.