An array of plasmonic nanoparticles can sustain surface plasmon modes from visible to infrared spectral range and thus offers effective surface light trapping, enhancement of local fields, and interaction with the thin active regions of optical devices. We report the fabrication and optical characterization of a planar Ge/Si quantum dot (QD) detector grown on silicon-on-insulator (SOI) substrate for photodetection in the near-infrared telecommunication wavelength range. The multilayer Ge/Si QD heterostructures are near-field coupled to the adjacent layers of aluminum nanodisks on the detector top. The periodic Al disk arrays have the square lattice symmetry with a lattice constant of 400 nm and the disk diameter varying from 150 to 225 nm. A significant enhancement in the room-temperature detector sensitivity is achieved due to the excitation of localized surface plasmons supported by the metallic disks and radiative coupling to the SOI waveguide modes. Through extinction spectroscopy and numerical modeling, we confirm the emergence of nanoparticle-induced plasmon resonances near the Si–Al interface. We demonstrate that an appropriate choice of the array periodicity and the size of the metal disks is able to increase the photodetector's efficiency by ∼ 40× at λ = 1.2 μ m and by 15× at λ ≈ 1.55 μ m relative to a bare detector with no plasmonic structure. These outcomes pave the way toward the use of Al as a low-cost plasmonic material with potential applications in infrared photodetection similar to those of the noble metals.

中文翻译：

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铝纳米盘支持的局域表面等离子体增强了 Ge/Si 量子点的近红外光响应

一系列等离子体纳米粒子可以维持从可见光到红外光谱范围的表面等离子体模式，从而提供有效的表面光捕获、局部场增强以及与光学器件的薄活性区域的相互作用。我们报告了在绝缘体上硅 (SOI) 衬底上生长的平面 Ge/Si 量子点 (QD) 探测器的制造和光学特性，用于在近红外电信波长范围内进行光电探测。多层 Ge/Si QD 异质结构近场耦合到探测器顶部的相邻铝纳米盘层。周期性铝盘阵列具有方形晶格对称性，晶格常数为 400 nm，盘直径从 150 到 225 nm。由于金属盘支持的局部表面等离子体激元的激发和与 SOI 波导模式的辐射耦合，室温检测器的灵敏度显着提高。通过消光光谱和数值模拟，我们证实了在 Si-Al 界面附近出现了纳米粒子诱导的等离子体共振。We demonstrate that an appropriate choice of the array periodicity and the size of the metal disks is able to increase the photodetector's efficiency by ∼ 40× at λ = 1.2 μ m and by 15× at λ ≈ 1.55 μ m relative to a bare detector with没有等离子体结构。这些结果为使用铝作为低成本等离子体材料铺平了道路，其在红外光电探测中的潜在应用类似于贵金属。