Loss Control with Annealing and Lattice Kerker Effect in Silicon Metasurfaces
Loss Control with Annealing and Lattice Kerker Effect in Silicon Metasurfaces
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硅超表面中退火和晶格克尔克效应的损耗控制
DOI：
10.1002/adpr.202100235
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Tanaka Katsuhisa
中科院分区：
文献类型：
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作者：
Liu Libei;Zhang Feifei;Murai Shunsuke;Tanaka Katsuhisa
超颖表面的共振现象在很大程度上依赖于各组分的散射强度及其相互干扰。损耗修改相位并降低所有多极子的幅度;因此，损耗控制对于获得设计特性至关重要。非晶（a-）Si具有比晶体形式更高的吸收系数，这限制了其光学应用。提出了一种简单的快速热退火（RTA）方法来细化a-Si超颖表面，并将其应用于溅射法制备的由正方形纳米盘阵列组成的a-Si超颖表面。虽然大的损耗消除了原超颖表面的谐振，但在RTA之后实现了具有接近完美吸收率的尖锐和接近零的反射率，通过磁偶极子和电偶极子的干扰满足晶格Kerker条件。在晶格Kerker条件下，从沉积在超颖表面上的发射极层观察到向前增强和向后减少的定向光致发光。数值计算结果与实验结果吻合较好，单纳米盘的多极展开分析给出了这一现象的物理背景。这种通过RTA处理对a-Si超颖表面的细化为实现激动人心的光学和光电应用（如探测器和滤波器）铺平了简单而稳健的道路。
The resonant phenomena of metasurfaces highly depend on the scattering strength of each component and their interferences. The losses modify the phase and reduce the amplitude of all multipoles; thus, the loss control is vital for obtaining the designed properties. Amorphous (a‐)Si has a higher absorption coefficient than that of the crystalline form, which limits its optical application. A simple rapid thermal annealing (RTA) path to refine thea‐Si metasurfaces is found. It is applied to the sputtering‐madea‐Si metasurface comprising square array of nanodisks. While the large loss smears out the resonances for the as‐made metasurface, the sharp and near‐zero reflectance with near‐perfect absorptance is achieved after RTA, satisfying the lattice Kerker condition via the interference of magnetic and electric dipoles. At the lattice Kerker condition, the forward‐enhanced and backward‐reduced directional photoluminescence is observed from the emitter layer deposited on the metasurface. The numerical results are all found to be in good agreement with the experimental results, and the multipole expansion analysis for the single nanodisk gives the physical background of this observation. This refinement ofa‐Si metasurfaces by RTA treatment paves the simple and robust way for realizing thrilling optical and optoelectrical applications, such as detectors and filters.