Identification of twin and nanoscale Te precipitations in CdZnTe crystals grown by vertical gradient method with HRTEM

Abstract

CdZnTe (CZT) has attracted much attention in nuclear detection field attribute to its high detection efficiency, high energy resolution and room-temperature operation. In this work, the CdZnTe samples were prepared by Vertical gradient method. High-resolution transmission electron microscopy (HRTEM) was used to investigate the nanoscale defects in CZT crystals. It is found that the twins are symmetric about the {111} plane, and the dislocations and stacking faults locate around the twin boundary. Te precipitations with hexagonal crystal structure is coherent with the CZT matrix. Te precipitated phases have three shapes of hexagon, polygon and irregularity, which determined by the interface energy between precipitations and matrix. The ordered phase with acicular shapes was found along [011] zone axis. The two variants of the ordered phase is corresponding to 1/211¯1 and 1/31¯11 ultrasound lattice, respectively. Besides the small angle grain boundaries with semi-coherent interface are observed. It is important to explore the behavior of nanoscale defects in the growth of CZT crystals in order to enlighten a path to regulate the nanoscale defects. The stability of the temperature interface is crucial to the preparation of high quality CZT crystals.