Growth and characterization of ZnTe single crystal via a novel Te flux vertical Bridgman method

Abstract: In this work, an II–VI group semiconductor zinc telluride (ZnTe) single crystal is prepared by a novel vertical Bridgman method using Te as flux. The initial mole ratio of Zn/Te = 3:7 is designed for raw material synthesis.ZnTe polycrystalline combined with rich Te is effectively fabricated through rocking technique at 1100 °C. A Φ 25 mm × 65 mm ZnTe boule is successfully grown under a ~ 40 °C·cm⁻¹ temperature gradient with a growth speed of 5 mm·day⁻¹. The as-grown ZnTe crystal has a standard 1:1 stoichiometric ratio and pure F43m phase structure. The maximum transmittance perpendicular to (110) plane is about 64%, and the band gap (E_g) is tested to be 2.225 eV. Terahertz (THz) examination results demonstrate that the time of the highest THz signal is around 17 ps and the frequency of the highest THz transmission is about 0.78 THz, implying that the ZnTe crystal grown by the present Te flux vertical Bridgman method has a good feasibility for THz application. Graphic abstract: [Figure not available: see fulltext.]