偶极子镜面效应FDTD仿真研究与定量分析

FDTD Simulation and Quantitative Analysis of Dipole Mirror Effect

贵金属纳米颗粒的局域等离子体共振可以显著增强宽禁带半导体的可见光响应,但纳米颗粒小体积强散射特性存在吸收系数低的问题,严重限制了其光电转换效率。偶极子镜面效应通过相对简单的金属-介质-金属(metal-insulator-metal,MIM)结构就可以实现宽频谱高效吸收,而了解其性能随关键参数调变规律对于器件设计制备具有重要指导作用。以AuNPs/TiO_(2)/Au三明治结构为基础,通过时域有限差分法(finite difference time domain,FDTD)仿真了AuNPs/TiO_(2)/Au的电/磁场强度和面积,得到不同结构参数下电磁场以及吸收效率的变化趋势。仿真结果表明,中间介质层可以有效调控结构的光吸收特性。当介质层厚度为60 nm时,MIM三明治结构会产生最强的等离子磁共振,且在宽频带(500~850 nm)实现最佳的可见光吸收效率(92%).该研究为进一步设计基于MIM三明治结构的高效等离子光催化剂和光电器件提供了理论指导。

The local plasma resonance of noble metal nanoparticles can significantly enhance the visible light response of wide bandgap semiconductors,but the absorption coefficient of noble metal nanoparticles with small volume and strong scattering is low,which severely limits the photoelectric conversion efficiency.The dipole mirror effect can achieve wide spectrum absorption with high efficiency by a relatively simple metal-insulator-metal(MIM)structure,and it is important for device design and preparation to understand the adjustment principle by the key parameters study.On the basis of AuNPs/TiO_(2)/Au sandwich structure,the variation trends of the electromagnetic field and absorption efficiency with different structural parameters were obtaimed by using the Finite Difference Time Domain(FDTD)to simulate the electric/magnetic field intensity and area of AuNPs/TiO_(2)/Au.The simulation results show that the intermediate dielectric layer can effectively control the light absorption characteristics of the structure.When the dielectric layer thickness is 60 nm,the MIM sandwich structure produces the strongest plasma magnetic resonance and achieves the best visible light absorption efficiency of 92%in wideband(500~850 nm).This study deepens the understanding of the electromagnetic field absorption enhancement mechanism of the dipole mirror effect and provides theoretical guidance for further design of efficient plasma photocatalysts and optoelectronic devices based on MIM sandwich structure.