Improvement of charge collection efficiency of the CdZnTe detectors by decreasing the Te inclusions

Abstract

CdZnTe is a promising material for room-temperature radiation semiconductor detectors. However, their radiation response performance might be deteriorated owing to defects within the material such as Te inclusions. This study employs the Cd thermal annealing process to reduce the size of these Te inclusions. An ampoule containing Cd powder and CdZnTe was sealed under the vacuum conditions of 2.5 × 10⁻⁵ Torr for Cd-vapor annealing. Subsequently, the ampoule was annealed at 783 K for 64 h. An IR camera was used to observe the distribution of Te inclusions in the CdZnTe before and after annealing. As a second experiment, NH₄F + H₂O₂ passivation was performed to suppress the increased leakage current due to Cd-vapor annealing. Then an ²⁴¹Am radioisotope source was used to obtain a radiation response spectrum. The improved charge collection efficiency was about 35%.