Hot electron photodetection with spectral selectivity in the C-band using a silicon channel-separated gold grating structure

Abstract

Photodetection based on hot electrons is attracting interest due to its capability of enabling photodetection at sub-bandgap energies of semiconductor materials. Si-based photodetectors incorporating hot electrons have emerged as one of the most widely studied devices used for near infrared (NIR) photodetection. However, most reported Si-based NIR photodetectors have broad bandwidths with responsivities that change slowly with the target wavelength, limiting their practicality as spectrally selective photodetectors. This paper reports a Si channel-separated Au grating structure that exhibits the spectrally selective photodetection in the C-band (1530-1565 nm). The measured responsivity of the structure drops from 64.5 nA mW-1 at 1530 nm to 19.0 nA mW-1 at 1565 nm, representing a variation of 70.5% over the C-band. The narrowband, ease of tuning the resonant wavelength, and spectral selectivity of the device not only help bridge the gap between the optical and electrical systems for photodetection but are also beneficial in other potential applications, such as sensing, imaging, and communications systems.