He Zhihui, Li Zhenxiong, Li Chunjiang, Xue Weiwei, Cui Wei
Opt Express. 2020 Jun 8;28(12):17595-17610. doi: 10.1364/OE.395640.
Silicon (Si), germanium (Ge), and gallium arsenide (GaAs) are familiar semiconductors that always act in the role of optical dielectrics. However, these semiconductors also have plasmonic behaviors in ultraviolet (UV) ranges due to the strong interband transitions or valence electrons. And few studies are aimed at investigating plasmonic properties in the semiconductor at the nanoscale. In this work, we discuss UV plasmonics and sensing properties in single and dimer Si, Ge, and GaAs triangular prism meta-antenna systems. The results show that obvious local surface plasmon resonances (LSPRs) can be realized in the proposed triangular prism meta-antennas, and the resonant wavelength, electromagnetic field distribution, surface charge distribution, and surface current density can be effectively tuned by structural and material parameters. In addition, we also find that the Si triangular prism meta-antenna shows more intense plasmonic responses in UV ranges than that in the Ge or GaAs triangular prism nanostructures. Especially, the phase difference between the triangular prism nanostructure and light source can effectively regulate the symbol and value of the surface charge. Moreover, the great enhancement of electric field can be seen in the dimer triangular prism meta-antennas when the distance of the gap is g<5 nm, especially g=1 nm. The most interesting result is that the maximum of refractive index sensitivity s and figure of merit (FoM) are greatly enlarged in dimer triangular prism meta-antennas. Particularly, the sensitivity can reach up to 215 nm/RIU in the dimer GaAs triangular prism meta-antennas, which is improved more than one order of magnitude. These research results may play important roles in applications of the photo detecting, plasmonic sensing and disinfecting in UV ranges.
硅（Si）、锗（Ge）和砷化镓（GaAs）是常见的半导体，它们通常充当光学电介质。然而，由于强烈的带间跃迁或价电子，这些半导体在紫外（UV）波段也具有等离子体行为。并且很少有研究旨在研究纳米尺度下半导体中的等离子体特性。在这项工作中，我们讨论了单晶硅、锗和砷化镓三角棱镜超材料天线系统中的紫外等离子体特性和传感特性。结果表明，在所提出的三角棱镜超材料天线中可以实现明显的局域表面等离子体共振（LSPR），并且共振波长、电磁场分布、表面电荷分布和表面电流密度可以通过结构和材料参数进行有效调节。此外，我们还发现硅三角棱镜超材料天线在紫外波段比锗或砷化镓三角棱镜纳米结构表现出更强的等离子体响应。特别是，三角棱镜纳米结构与光源之间的相位差可以有效地调节表面电荷的符号和值。而且，当间隙距离g<5 nm，特别是g=1 nm时，在双体三角棱镜超材料天线中可以看到电场的大幅增强。最有趣的结果是，双体三角棱镜超材料天线中的折射率灵敏度s和品质因数（FoM）的最大值大大提高。特别是，在双体砷化镓三角棱镜超材料天线中，灵敏度可达215 nm/RIU，提高了一个多数量级。这些研究结果可能在紫外波段的光检测、等离子体传感和消毒应用中发挥重要作用。
