Growth and defect structure of zinc germanium phosphide crystal

A high-purity ZnGeP2 polycrystalline material was synthesized by two-temperature zone technique. The single crystals with the diameter of 40-50 mm were grown by a vertical Bridgman technique. The possible point defects in the ZnGeP2 crystal and its influence to the near-infrared light transmittance of crystal were investigated via the density functional theory calculation. The results showed that VZn- defects gave the greater optical losses than other point defects. According to the analysis by X-ray diffraction topography, there exist the microdefects, i.e., dislocation, stacking fault, twin boundary, inclusion, etc. It is indicated that the temperature field stability and the growth interface shape are the crucial factors affecting the crystal growth.