Preferential orientation of Te particles in melt-grown CZT

摘要

Cadmium zinc telluride (Cd_(1-x)Zn_xTe or CZT) has proved to be a useful material for semiconductor gamma-ray spectrometers and other electro-optic devices. It is often grown Te-rich to optimize its electrical characteristics, but this off-stoichiometric growth leads to the formation of semimetallic Te particles in the semiconducting host crystal. These particles can impair device performance and their formation needs to be inhibited, if possible, during growth. In this study, characterization of several particles of different faceted shapes revealed that most of the Te particles were preferentially oriented with the {101}_(CZT)‖{1210}_(Te). A secondary orientation relationship was also observed as {111}_(CZT)‖{0111}_(Te) for one of the {111}_(CZT) family of planes. One of the particles exhibited {110}_(CZT)‖{0110}_(Te), and {0 01}_(CZT)‖{0 0 01}_(Te). Particles were often found on {111}_(CZT) twin boundaries and, in these cases, it was possible to assign specific orientations with respect to the twin plane. Ab initio calculations predicted a good lattice match between the {0 0 01}-plane of Te aligned with the {111}-plane of CZT, however, no such particle orientation was observed. Observations of strained and polycrystalline Te particles are also discussed with relevance to the ab initio model and to impacts on electronic properties.