点缺陷对单层六角氮化硼二阶光学极化率的影响  

Influence of Point Defects on Second-Order Optical Susceptibility of Monolayer Hexagonal Boron Nitride

作　　者：蓝尤钊[1] Lan Youzhao(Key Laboratory of Ministry of Education for Advanced Catalysis Materials,College of Chemistry and Materials Science,Zhejiang Normal University,Jinhua 321004,Zhejiang,China)

机构地区：[1]浙江师范大学化学与材料科学学院先进催化材料教育部重点实验室,浙江金华321004

出　　处：《光学学报》2025年第2期231-242,共12页Acta Optica Sinica

摘　　要：基于第一性原理计算方法研究空位点缺陷对单层六角氮化硼材料的非线性二次谐波产生系数的影响。结合线性单光子吸收光谱,详细分析了二次谐波产生系数增强的微观机制,并利用态求和跟踪技术准确定位缺陷态对二次谐波产生系数的贡献。结果表明,缺陷态总体导致含缺陷结构的二次谐波产生系数相比于原生结构的系数明显增大,与实验结果一致,部分二次谐波产生系数增强峰几乎完全由缺陷态决定。缺陷态把单层六角氮化硼材料的光学应用从深紫外区扩展到紫外可见光区。Objective For two-dimensional layered hexagonal boron nitride(2D-hBN)materials,various defects are inevitably generated during experimental synthesis.Defects directly affect the electronic structure of the material and thus influence the optical properties of the material.The defect-related electronic states cause the red-shift of the linear absorption spectrum from the deep ultraviolet region of pristine 2D-hBN to the ultraviolet-visible region of defective 2D-hBN.Meanwhile,defects also have a significant effect on the nonlinear optical properties of the material.Recent experiments have shown that defects increase the nonlinear second-harmonic generation(SHG)coefficient of 2D-hBN by an order of magnitude.These findings suggest that defects can be used to tune the nonlinear optical properties of materials.To use defects to tail the optical properties of materials,it is of great significance to reveal their influence on optical properties from a microscopic view.In this study,we attempt to study the influence of point defects on the SHG coefficient of monolayer 2D-hBN(ML-BN).The sum-over-states method is used to study the microscopic mechanism of the enhancement of SHG coefficients and to reveal the relationship between the enhanced SHG coefficients and defect states.Methods We create three vacancy-related defective structures in the 5×5 supercell of ML-BN(Fig.1).The PBE functional of generalized gradient approximation(PBE-GGA)combined with the norm-conserving pseudopotential planewave method is used to optimize all defective structures.We use a 3×3×1 k grid,a force threshold of 0.01 eV/Å,and a pressure threshold of 0.02 GPa for optimization.The relaxation of the unit cell is included during the optimization process and a vacuum spacing greater than 15Åis used to ensure negligible interlayer interactions.The PBE-GGA combined with the norm-conserving pseudopotential plane-wave method is used to calculate the energy band structure of three defective structures.A k-grid of 24×24×1 and a kinetic energy cutoff o

关 键 词：材料 态求和 二次谐波产生 缺陷 单层六角氮化硼 第一性原理 

分 类 号：O437[机械工程—光学工程]