Visser D, Choudhury B Dev, Krasovska I, Anand S
Opt Express. 2017 May 29;25(11):12171-12181. doi: 10.1364/OE.25.012171.
Si nanopillar (NP) arrays are investigated as refractive index sensors in the visible/NIR wavelength range, suitable for Si photodetector responsivity. The NP arrays are fabricated by nanoimprint lithography and dry etching, and coated with thin dielectric layers. The reflectivity peaks obtained by finite-difference time-domain (FDTD) simulations show a linear shift with coating layer thickness. At 730 nm wavelength, sensitivities of ~0.3 and ~0.9 nm/nm of SiO and SiN, respectively, are obtained; and the optical thicknesses of the deposited surface coatings are determined by comparing the experimental and simulated data. The results show that NP arrays can be used for sensing surface bio-layers. The proposed method could be useful to determine the optical thickness of surface coatings, conformal and non-conformal, in NP-based optical devices.
硅纳米柱（NP）阵列作为可见/近红外波长范围内的折射率传感器进行了研究，适用于硅光电探测器的响应度。NP阵列通过纳米压印光刻和干法蚀刻制造，并涂覆有薄介电层。通过有限时域差分（FDTD）模拟获得的反射率峰值显示出随涂层厚度的线性偏移。在730nm波长下，分别获得了SiO和SiN的灵敏度约为0.3和0.9nm/nm；通过比较实验数据和模拟数据确定了沉积表面涂层的光学厚度。结果表明，NP阵列可用于传感表面生物层。所提出的方法对于确定基于NP的光学器件中保形和非保形表面涂层的光学厚度可能是有用的。
