Impact of polishing on crystallinity and static performance of Cd_1−xZn_xTe

This article focuses on the impact of polishing of CdZnTe crystals on the electrical properties of the resulting detectors. It is shown that the standard rough polishing of the crispy crystals by 5μm size alumina powder increases the effective surface area by a factor 3 and introduces in-depth defects. The defects affect the static current–voltage dependence and were also observed by crystallographic characterization. The depth of the defected layer was determined to be 20–25μm by a consecutive stripping of surface layers. The crystallographic results, indicating structural imperfections, fully correspond to the electrical characteristics. The results are explained by limited CdZnTe/In contact recombination velocity and enhanced generation–recombination velocity of the defected (polycrystalline) layer. The hypothesis was corroborated by a finite element computation.