Intrinsic defects and their effects on the optical properties in the nonlinear optical crystal CdSiP2: a first-principles study
Intrinsic defects and their effects on the optical properties in the nonlinear optical crystal CdSiP2: a first-principles study
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非线性光学晶体 CdSiP2 的本征缺陷及其对光学性能的影响：第一性原理研究
DOI：
10.1039/c7cp01312d
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发表时间：
2017
影响因子：
3.3
通讯作者：
Tao Xutang
中科院分区：
文献类型：
--
作者：
Wang Ci;Sun Jie;Gou Huiyang;Wang Shanpeng;Zhang Jian;Tao Xutang
CdSiP 2（CSP）晶体具有高的非线性光学系数和良好的相位匹配特性，被认为是非线性光学应用领域最有前途的材料之一。然而，在e偏振光下，在1.34 μm和1.78 μm附近的轻微吸收损失一直影响其性能。在这项研究中，第一性原理计算进行，以确定各种电荷缺陷的吸收性能的影响。利用HSE方法计算了CSP晶体中不同的本征缺陷，并根据实验中的具体化学环境进行了比较。结果表明，在贫Cd环境中，可以自发形成的V2−Cd、Si 2 +Cd和V4−Si的点缺陷占主导地位。Si 2 +Cd和V2−Cd缺陷的组合是Cd贫乏情况下最有利的团簇，因为其形成能相对较低。此外，反位缺陷SiCd对1.34和1.78 μm处的吸收峰有贡献，而其它缺陷和团簇，如Si ~（2+）Cd和V_0Si也对这些红移的吸收峰有贡献。我们的研究结果旨在提供一个指导方针，通过修改其缺陷的CSP的光吸收。
In view of their high nonlinear optical coefficients and good phase-matching properties, CdSiP2 (CSP) crystals are considered as one of the most promising materials in the field of nonlinear optical applications. However, the slight absorption losses around 1.34 μm and 1.78 μm under e-polarized light have been affecting its performance. In this study, first-principles calculations were performed to identify the effects of various charge defects on the absorption properties. Different intrinsic defects in the CSP crystal were calculated using the HSE method and compared according to the specific chemical environments in the experiments. The results show that the point defects of V2−Cd, Si2+Cd, and V4−Si, which can be spontaneously formed, are dominant in the Cd-poor environment. The combination of Si2+Cd and V2−Cd defects is the most favorable cluster in the Cd-poor case because of its relatively low formation energy. Furthermore, the antisite defect SiCd was found to be responsible for the main absorption peaks at 1.34 and 1.78 μm in the experimental spectra, whereas other defects and clusters, such as the defects Si2+Cd and V0Si, also contribute to these red shifted absorptions. Our results intend to provide a guideline for adjusting the optical absorption in CSP by modifying its defects.