CMOS-compatible metallic nanostructures for visible and infrared filtering

Metal-Insulator-Metal (MIM) and Insulator-Metal (IM) sub-wavelength arrays are studied to perform filtering in Visible (VIS) and Near-Infrared (NIR) respectively. We investigate the MIM sub wavelength pattern using CMOS compatible materials like silicon nitride (SiN) core and aluminum (Al) metal for visible color filtering, and IM sub wavelength array with the same materials for near- infrared filtering using Rigorous Coupled Wave Analysis (RCWA). Transmission as high as 50 % is observed for VIS-filters, while for NIR filters maximum transmissions of 80% is observed. Metallic absorption in Infrared is significantly reduced using IM structure. Enhancement in Infrared transmission by factor of 1.5 is observed upon using IM structure instead of MIM structure. Blue shift in transmission spectra is observed with increase in roundness of the patch corners. Angular tolerance of ± 20° in incidence is observed for the arrays studied.