Characterization of growth defects in ZnTe single crystals

(111) wafers sliced from a boule of ZnTe grown by horizontal physical vapor transport (PVT) have been characterized using synchrotron white beam X-ray topography. The growth axis was about 6° off [311]. The presence of dislocation slip bands, subgrain structures and [1̄11] axis 180° rotational twins were revealed. The slip bands were observed to break up the ordered dislocation cell structures comprising the subgrain boundaries. The initiation of slip at regions of stress concentration at the junctions of subgrain boundaries and twin boundaries was observed. The asymmetric distribution of slip bands either side of the twinned region of crystal suggests that twin boundaries can act as barriers for slip. Several types of detailed twin boundary configuration were determined from the topographs. Using a combination of white beam X-ray topography and Nomarski interference microscopy, the three dimensional shapes of the twin boundaries were determined. Approximate atomic structures at these boundaries are presented.