Nd、N掺杂ZnO的电子结构和光学性质的第一性原理研究

First-principles study on the electronic structure and optical properties of Nd/N-doped ZnO

基于密度泛函理论的第一性原理,使用GGA+U方法计算出N、Nd分别单掺ZnO及N、Nd共掺ZnO晶体的形成能,能带结构,态密度及光学性质.经过对比发现:N、Nd各掺杂ZnO中,共掺体系比单掺体系更容易形成,其中低浓度掺杂难度更低;共掺体系随着掺杂浓度的升高,其畸变的强度就越强,禁带宽度变窄,电子跃迁到导带上所需的能量更小,光吸收系数较大,并且都产生了红移,光谱响应范围扩展到了整个可见光区域;共掺体系在低能区域的介电谱峰值较高,说明其极化能力较强,光生电场强度较大,会使光激发载流子在晶体内的迁移变快,对电荷的束缚能力增强.因此N、Nd共掺可以有效提升ZnO的光催化性和极化能力.

Based on the first principle of density functional theory,the formation energy,band structure,density of states and optical properties of N and Nd doped ZnO and N,Nd co-doped ZnO crystals were calculated by using the GGA+U method.After comparison,it is found that the co-doped system is easier to form than the single-doped system in N and Nd doped ZnO,and the low concentration doping is less difficult;the intensity of the distortion of the co-doped system increases with the increased doping concentration.The narrower the band gap is,the less energy is required for the electron transfer to the conduction band;the light absorption coefficient of the co-doped systems is larger,and all are red-shifted,and the spectral response range extends to the entire visible region;The peak of the dielectric spectrum of the co-doping system in the low energy region is high,indicating that the polarization ability is strong,and the intensity of the photogenerated electric field is large,which makes the migration of photoexcited carriers in the crystal faster and the ability to bind the charge is enhanced.Therefore,N,Nd co-doping can enhance the photocatalytic and polarizing ability of ZnO.