Growth of large-size high-quality ZnTe bulk crystals by traveling solvent melting zone method

Abstract

ZnTe crystal is a promising electro-optical crystal materials applied for THz generation and detection. However, there is still a big challenge to obtain large sized high quality ZnTe crystals. In this work, large sized ZnTe bulk crystals with Φ30 mm × 150 mm were grown by the traveling solvent melting zone (TSMZ) method. With the characterization of the optical and electrical properties of as-grown ZnTe crystals, the band gap (2.22 eV), high IR transmittance (around 60%), high resistivity (3.5 × 103 Ω·cm), low density (1.3 × 105 cm−2) and small sizes (3 μm - 5 μm) of Te inclusions in ZnTe crystals, low etch pit densities (1.5 × 105 cm−2), high peak intensity to FWHM ratio (2.5 × 104) of the LO peak in the Raman spectra were obtained. Furthermore, the THz transmission spectra was measured and the maximum transmittance is more than 40% at the range of 0.3 - 3 THz. Based on these results, high quality and large aspect ratio ZnTe bulk crystals can be obtained by the TSMZ technique. Our work has greatly facilitated the application of ZnTe crystals in THz device.