La掺杂ZnO的电子结构和光学性质的第一性原理

The First Principles of the Electronic Structure and Optical Property of La-doped ZnO

采用基于密度泛函理论的第一性原理平面波超软赝势方法,构建Zn1-xLaxO(x=0,0.0625,0.125)3种超胞模型。结构优化后,对La掺杂前后体系的态密度、布居值和光学性质进行计算分析。结果表明,随着La掺杂量的增加,掺杂体系的体积增加,形成能减少,共价性降低,体系稳定性增强。与未掺杂ZnO相比,La掺杂后引起可见光区的吸收边发生蓝移。体系的介电函数虚部和光吸收系数在低能区出现新的峰值。在高能区的吸收峰出现红移且峰值强度减弱。能量损失峰向低能方向移动,掺杂体系的能量损失明显减少。

Three supercell models of Zn1-xLaxO(x=0,0.0625,and 0.125)were constructed using the first-principle plane-wave ultrasoft pseudopotential method in density functional theory.After structural optimization,the density of states,Mulliken bond population,and optical properties of the system before and after La doping were calculated and analyzed.The results show that with the increase of La-doping amount,the volume of the doping system increased,the formation energy decreased,the covalent property weakened,and the stability of the system was enhanced.Compared with undoped ZnO,the absorption edge of the visible region had blue-shift after La-doping.The imaginary part of the dielectric function and the optical absorption coefficient showed a new peak in the low-energy region.The absorption peak in the high-energy region appearred a red shift and the peak intensity decreased.The energy loss peak moved toward the low-energy direction,and the energy loss of the doping system was significantly reduced.