Investigation of photoconductivity and electric field distribution in CZT detectors by time-of-flight (TOF) and charge extraction by linearly increasing voltage (CELIV)

摘要

Although cadmium zinc telluride (CZT) is the most widely used room-temperature photoconductor for low flux radiation sensing, utilization of this promising material in high flux applications, like computed tomography is challenging, due to possible dynamic polarization. Indeed, trapping of the X-ray-generated charge may cause space charge build-up and electric field distortion. Combining the conventional time-of-flight and the photo-generated charge extraction by linear increasing voltage (photo-CELIV) techniques, we track changes of the main electrodynamic parameters (such as electric potential and intrinsic electric field) of CZT under various fluxes. In addition, we investigate transport properties of electrons and holes in a wide range of temperatures and electric fields. Multiple trapping was found to govern the hole transport, while electrons conduct electrical current via various scattering mechanisms.