Tailoring Inclusions and Improvement of ZnTe Crystal Quality by Annealing

The temperature gradient solution method can effectively reduce the growth temperature of zinc telluride (ZnTe) crystal. However, it is inevitable to introduce Te inclusions in the as-grown ZnTe crystals, leading to degrading the crystal quality. In this paper, the Te inclusions under saturated Zn vapor were eliminated via both isothermal annealing and gradient annealing. The removal efficiency of Te inclusions was evaluated, which was determined by the annealing temperature and gradient. A removal efficiency of 83% is achieved via gradient annealing at 650 ℃ for100 h. In addition, V_Te–Te_i complex defects caused by Te atoms diffusion appear in the crystal after annealing, thus affecting the crystal quality and photoelectric properties of the ZnTe crystal. Based on the X-ray double-crystal rocking curves of the ZnTe crystal, the crystal quality is generally improved when the Te inclusions are removed, indicating that the Te inclusions are a dominated factor affecting the quality of ZnTe crystal.