Developments of Point Defects in ZnGeP2 Crystals
ZnGeP2晶体点缺陷的研究进展

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, V0P and Ge+Zn donors, and their energy levels are E(V-Zn)=EC-(1.02±0.03)eV, E(V0P)=EV+(1.61±0.06)eV and E(Ge+Zn)=EV+(1.70±0.03)eV. In addition, the two defects V-3Ge 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.