Open AccessRefractive index sensing in the visible/NIR spectrum using silicon nanopillar arrays
Author(s) -
Dennis Visser,
Bikash Dev Choudhury,
Inese Krasovska,
Srinivasan Anand
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.012171
Subject(s) - nanopillar , materials science , refractive index , optics , responsivity , finite difference time domain method , dielectric , photodetector , optoelectronics , wavelength , nanoimprint lithography , etching (microfabrication) , silicon , thin film , layer (electronics) , nanostructure , fabrication , nanotechnology , medicine , physics , alternative medicine , pathology
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 2 and Si 3 N 4 , 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.