Effects of IR irradiation on the transport properties through deep-level defects in CdZnTe crystals studied by thermally stimulated current

The effects of infrared (IR) irradiation on the transport properties in CdZnTe crystals were investigated by using thermally stimulated current (TSC) measurements. The temperature increasing process in TSC measurements could be described by the standard Shockley-Read-Hall (SRH) model. When applying IR irradiation to this process, the relative balance from the mixing effect of the six thermal and optical transitions could be described by the modified SRH model. Under steady-state condition at room temperature, the increase of the ionization probability of the deep donor (T4) from ~0.71 in the dark to ~0.93 with IR irradiation, theoretically predicted by the SRH model was identified, which is consistent with the increase of the effective density of T4 from (5.28±0.26)×10¹³ cm⁻³ in the dark to (7.25±0.36)×10¹³ cm⁻³ with IR irradiation, experimentally measured from TSC results. Therefore, the effects of IR irradiation on the transport properties, by suppressing trapping and encouraging de-trapping through the defect traps, would further contribute to improving the charge collection processes and the consequent spectroscopic characteristics of CZT detectors.