Effects of Intrinsic Defects on the Carrier Lifetime in CdZnTe: Insights from Ab Initio Calculations

CdZnTe (CZT) has garnered substantial attention due to its outstanding performance in room-temperature semiconductor radiation detectors, where carrier transport properties are critical for assessing the detector performance. However, due to the complexities of crystal growth, CZT is prone to defects that affect carrier lifetime and mobility. To investigate how defects affect nonequilibrium carrier transport, nonadiabatic molecular dynamics (NAMD) is employed to examine six types of intrinsic defects and their impact on electron-hole (e-h) recombination. The findings reveal that Te substitution at the Cd site (TeCd) and Te interstitial (Tei) defects expedite recombination by introducing intermediate energy levels. The coupling of new energy levels in Te vacancy (VTe) with the conduction band minimum (CBM) slows down electron release and results in an extended recombination time. Cd substitution at the Te site (CdTe) and Cd interstitial (Cdi) defects enhance nonadiabatic coupling (NAC) to accelerate the recombination. In contrast, Cd vacancy (VCd) diminishes NAC through weakening carrier coupling with high-frequency phonons and leads to a deceleration of the recombination rate. Overall, the intrinsic defects may change electron structures to vary NAC, which is critical for the recombination rate. It is believed that this research may benefit the understanding of defects on the carriers' lifetime in CZT and provide hints for further optimizing the performance of CZT material in nuclear radiation detection.