Indentation-introduced dislocation rosettes and their effects on the carrier transport properties of CdZnTe crystal

Abstract

Herein, we study the crystallographic configuration of rosette-like dislocation clusters introduced by indentation in CdZnTe (CZT) crystal and the effects of the dislocations on the carrier transport process. The Vickers hardness test was used to generate dislocations artificially on the () Te face of the CZT crystal at room temperature. Etch pit density (EPD) revealed by Everson etchant showed that the dislocation density increased from 4.9 × 10⁴ cm⁻² to a concentration too high to be evaluated after the indentation. A model was proposed to explain the rosette-like dislocation clusters. It was verified that the tetrahedron with small size and high EPD belonged to Te(g) dislocations on the () Te face. The hexagon-like distribution of pile-ups formed during the indentation was determined by the zinc-blende structure of CZT, rather than the direction of the indenter. The dislocation pile-up during propagation was observed and analyzed based on the rule proposed by Lomer and Cottrell. The ion beam induced charge (IBIC) measurements showed low carrier collection efficiency (CCE) in the dislocation generation areas, which confirms that the dislocations and related defects can significantly degrade the CCE of a CZT detector. Measurements of low temperature photo-luminescence (PL) showed that the emission peak located at 1.485 eV highly increased in the indentation area and was responsible for the performance degradation of the detectors.