Growth of ZnTe single crystals from Te solution by vertical Bridgman method with ACRT

ZnTe ingots 30 mm in diameter and about 60 mm in length were grown from Te solution based on vertical Bridgman method with accelerated crucible rotation technique (ACRT). The composition homogeneity and the optical and electrical properties of the crystals were investigated using optical transmission microscope, energy dispersive spectrometer (EDS), scanning electron microscope (SEM), electron probe micro-analyzer (EPMA), ultraviolet-visible (UV-Vis) spectrophotometer, Fourier transform infrared (FT-IR) spectrometer and digital electrometer. The growth method was found efficient for mass transfer, and produced large size single crystal with the volume up to 10 mm×10 mm×40 mm. Single crystals formed in the earlier stage of growth process are larger in size with less Te inclusions. Secondary inclusions formed due to thermal migration and crystal cracking were found. The IR transmittance over the wavenumber range from 500 to 4000 cm^-1 is about 60%, and the band gap is about 2.23 eV at room temperature (RT). Its resistivity can reach up to about 700 Ω cm, which is the highest ever reported for unintentionally doped ZnTe crystal.