In this paper, a large-size and crack-free ZnTe single crystal 40 mm in diameter and 110 mm in length was grown in a two-zone vertical furnace by the modified Bridgman method. To reduce the defect concentration and improve the resistivity of ZnTe crystals for satisfying the requirements in terahertz applications, we investigated an effective thermal annealing process with the first step in Zn vapor at 950 ℃ for 240 h and the second step in In and Zn vapor at 1050/950 ℃(ZnTe/In and Zn) for 120 h. The inductively coupled plasma mass spectrometer (ICP-MS) analysis indicates that the concentration of indium in the annealed crystals is about 4.85 × 10 cm. Compared with the ZnTe crystals annealed in Zn vapor, the X-ray rocking curve (XRC) show that ZnTe crystals annealed in In and Zn vapor still have high crystallization quality. Additionally, the resistivity is enhanced by 5–6 orders to 10 Ω cm while preserving the high infrared (IR) transmittance with about 65 % in the region from 2.5 to 20 μm. The terahertz (THz) transmission spectra of the annealed crystals show higher amplitude, and the maximum transmission is approximately 70 % at the range of 0.5–2 THz, which is 40 % more than the ZnTe crystals annealed in Zn vapor in the low-frequency region.

中文翻译：

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通过 In 和 Zn 蒸气退火提高 ZnTe 晶体的质量

本文采用改进的布里奇曼法在两区立式炉中生长了直径40 mm、长度110 mm的大尺寸、无裂纹的ZnTe单晶。为了降低缺陷浓度并提高 ZnTe 晶体的电阻率以满足太赫兹应用的要求，我们研究了一种有效的热退火工艺，第一步在 950 ℃ Zn 蒸气中持续 240 h，第二步在 950 ℃ 下在 In 和 Zn 蒸气中退火 240 h。 1050/950℃(ZnTe/In和Zn)120小时。电感耦合等离子体质谱仪(ICP-MS)分析表明退火晶体中的铟浓度约为4.85×10 cm。与Zn蒸气退火的ZnTe晶体相比，X射线摇摆曲线（XRC）表明In和Zn蒸气退火的ZnTe晶体仍然具有较高的结晶质量。此外，电阻率提高了 5-6 个数量级，达到 10 Ω cm，同时保持了 2.5 至 20 μm 区域约 65% 的高红外 (IR) 透射率。退火晶体的太赫兹（THz）透射光谱显示出更高的振幅，在0.5-2 THz范围内最大透射率约为70%，比低频Zn蒸气退火的ZnTe晶体高40%地区。