高浓度氧空位(V_(o))掺杂ZnO的电子结构和光学性质的第一性原理计算

Electronic Structure and Optical Properties of ZnO Doped with high Concentration Oxygen Vacancies First Principles Calculation

基于密度泛函理论的第一性原理平面波超软赝势GGA+U的方法,构建了本征ZnO和不同浓度O空位掺杂ZnO_(x)(x=0.625、0.75、0.875)的超晶胞体系,对掺杂前后体系的能带结构、态密度以及光学性质进行了计算.计算结果表明:对比本征ZnO体系,掺杂后的体系都出现了杂质能级,带隙明显比本征ZnO体系小得多,表示电子在带间跃迁时所需能量变小,有利于其对光响应范围的拓展,这在光吸收谱中得到验证,掺杂后体系的吸收带边均发生了明显的红移,其响应范围拓展到可见光区域,并且掺杂后体系的光吸收强度显著高于纯ZnO体系,其中ZnO_(0.625)体系在可见光区域红移最明显并且光吸收系数最高.

Based on the first principle plane wave ultra soft pseudopotential GGA+U method of density functional theory,the supercell systems of intrinsic ZnO and different concentrations of O vacancy doped ZnO_(x)(x=0.625,0.75,0.875)are constructed.The energy band structure,density of states and optical properties of the systems before and after doping are calculated.The calculation results show that compared with the intrinsic ZnO system,the impurity energy levels appear in the doped system,The band gap is much smaller than that of the intrinsic ZnO system,which means that the energy required for the electron to transition between bands becomes smaller,which is conducive to the expansion of its light response range.This is verified in the light absorption spectrum.The absorption band edge of the doped system has an obvious red shift,and its response range is extended to the visible light region,and the light absorption intensity of the doped system is significantly higher than that of the pure ZnO system,Among them,ZnO_(0.625) system has the most obvious red shift in the visible region and the highest light absorption coefficient.