Effect of de-trapping on carrier transport process in semi-insulating CdZnTe

The effect of de-trapping on the carrier transport process in the CdZnTe detector is studied by laser beam-induced transient current (LBIC) measurement. Trapping time, de-trapping time, and mobility for electrons are determined directly from transient waveforms under various bias voltages. The results suggest that an electric field strengthens the capture and emission effects in trap center, which is associated with field-assisted capture and the Poole-Frenkel effect, respectively. The electron mobility is calculated to be 950 cm²/V·s and the corresponding electron mobility-lifetime product is found to be 1.32 × 10^-3 cm²/V by a modified Hecht equation with considering the surface recombination effect. It is concluded that the trapping time and de-trapping time obtained from LBIC measurement provide direct information concerning the transport process.