Effect of transient space–charge perturbation on carrier transport in high-resistance CdZnTe semiconductor**Project supported by the National Natural Science Foundation of China (Grant No. 61874089), the Fund of MIIT (Grant No. MJ-2017-F-05), the 111 Project of China (Grant No. B08040), the NPU Foundation for Fundamental Research, China, and the Research Found of the State Key Laboratory of Solidification Processing (NWPU), China.

Abstract

The polarization effect introduced by electric field deformation is the most important bottleneck of CdZnTe detector in x-ray imaging. Currently, most of studies focus on electric field deformation caused by trapped carriers; the perturbation of electric field due to drifting carriers has been rarely reported. In this study, the effect of transient space–charge perturbation on carrier transport in a CdZnTe semiconductor is evaluated by using the laser-beam-induced current (LBIC) technique. Cusps appear in the current curves of CdZnTe detectors with different carrier transport performances under intense excitation, indicating the deformation of electric field. The current signals under different excitations are compared. The results suggest that with the increase of excitation, the amplitude of cusp increases and the electron transient time gradually decreases. The distortion in electric field is independent of carrier transport performance of detector. Transient space–charge perturbation is responsible for the pulse shape and affects the carrier transport process.