Responsivity enhancement of MIS photodetectors on SOI substrates by plasmonic nanoantennas

We report MIS photodetectors fabricated on a SOI substrate in a CMOS-compatible process, exhibiting an enhanced responsivity in the near-infrared (NIR) due to the incorporation of Au-nanoantennas at the optical input port. These nanoantennas modify the propagation of the input optical signals, serving as an effective anti-reflection coating in the NIR wavelength range. The optimal antenna design and the photo-response enhancements have been calculated using detailed FDTD simulations. The maximum responsivity enhancement, 40%, was obtained at 780 nm, while at wavelengths shorter than 720 nm, responsivity is reduced due to absorption losses in the Au-nanoantennas.