ZnGeP2晶体点缺陷的研究进展

ZnGeP₂晶体是具有重要应用背景的红外非线性光学材料. 晶体中的点缺陷严重限制了ZnGeP₂晶体的应用发展. 本工作介绍了ZnGeP₂晶体点缺陷的最新研究进展情况. 首先, 利用电子顺磁共振技术研究了ZnGeP₂晶体的点缺陷. 主要存在缺陷是受主缺陷V^-_Zn及施主缺陷V⁰_P和Ge⁺_Zn, 其相应的缺陷能级分别为E(V^-_Zn)=E_C-(1.02±0.03)eV, E(V⁰_P)=E_V+(1.61±0.06)eV和E(Ge⁺_Zn)=E_V+(1.70±0.03)eV. 对晶体作了电子照射及高温退火等处理后, 又分别发现了两种缺陷V ^3-_Ge和VPi. 其次, 利用全势能线性muffin-tin轨道组合法模拟研究了ZnGeP₂晶体的点缺陷. 主要存在缺陷及缺陷能级的计算结果与实验结果基本一致, 但由于理论模拟与实际情况还存在差距, 有些计算结果与实验结果相矛盾. 因此, 将实验与理论有机结合研究晶体的点缺陷是今后研究的重点.

Developments of Point Defects in ZnGeP2 Crystals

ZnGeP₂ is a nonlinear optical material which is useful for important applications in the infrared region. A serious limitation to the development of ZnGeP₂-based applications is the presence of point defects in the crystals. The latest development of the point defects in ZnGeP₂ is summarized in the paper. Firstly, the point defects are studied by electron paramagnetic resonance technique. The dominant point defects in ZnGeP₂ are V^-_Zn acceptor, V⁰_P and Ge⁺_Zn donors, and their energy levels are E(V^-_Zn)=E_C-(1.02±0.03)eV, E(V⁰_P)=E_V+(1.61±0.06)eV and E(Ge⁺_Zn)=E_V+(1.70±0.03)eV. In addition, the two defects V^-3_Ge and VPi are observed in electron irradiated and annealed ZnGeP₂, respectively. Secondly, the point defects are studied simulatively by full-potential linearized muffin-tin orbital method. The results of the dominant defects and their energy levels are in agreement with the experimental evidences. However, there still exists difference between the theoretical simulation and the actual situation, some results are discrepant with the experimental conclusions. Therefore, it is important to investigate point defects by the combination of experiment and theory.