Influence of the preparation conditions on optical properties of single crystals ZnGeP₂ in THz range

The influence of growth conditions and post-growth treatment processing on the quality of the ZnGeP₂ single crystals obtained was considered. It was revealed that the properties measurements carried out in the THz region have shown that the refractive index of the ordinary beam is greater than the extraordinary one, in contrast to the IR spectral range. It was found that the refractive indices of crystals ZnGeP₂ in THz band under heat treatment are reduced. The absorption coefficient of an ordinary beam in the THz range of crystals ZnGeP₂ is smaller than that of an extraordinary one. The absorption coefficients in the 250-1000 μm region increase for the annealed crystals ZnGeP₂ (600°C, 300-400 h). For wavelengths >1000 μm, the absorption coefficient of crystals ZnGeP₂ doesn't exceed value 0.1 cm⁻¹. The correlation of the optical quality of the ZnGeP₂ single crystals in THz region with the growth conditions and post-growth processing was established. (paper)