Hot-electron photodetector with wavelength selectivity in near-infrared via Tamm plasmon

Abstract

Tamm plasmonic (TP) structures, consisting of a metallic film and a distributed Bragg reflector (DBR), can exhibit pronounced light confinement allowing for enhanced absorption in the metallic film at the wavelength of the TP resonance. This wavelength dependent absorption can be converted into an electrical signal through the internal photoemission of energetic hot-electrons from the metallic film. Here, by replacing the metallic film at the top of a TP structure with a hot-electron device in a metal–semiconductor–ITO (M–S–ITO) configuration, for the first time, we experimentally demonstrate a wavelength-selective photoresponse around the telecommunication wavelength of 1550 nm. The M–S–ITO junction is deliberately designed to have a low energy barrier and asymmetrical hot-electron generation, in order to guarantee a measurable net photocurrent even for sub-bandgap incident light with a photon energy of 0.8 eV (1550 nm). Due to the excitation of TPs between the metallic film in the M–S–ITO structure and the underlying DBR, the fabricated TP coupled hot-electron photodetector exhibits a sharp reflectance dip with a bandwidth of 43 nm at a wavelength of 1581 nm. The photoresponse matches the absorptance spectrum, with a maximum value of 8.26 nA mW⁻¹ at the absorptance peak wavelength that decreases by more than 80% when the illumination wavelength is varied by only 52 nm (from 1581 to 1529 nm), thus realizing a high modulation wavelength-selective photodetector. This study demonstrates a high-performance, lithography-free, and wavelength-selective hot-electron near-infrared photodetector using an M–S–ITO–DBR planar structure.