Perfect absorption induced by plasmon toriodal mode for hot electron based NIR photo-detection

Abstract

Abstract Hot electron can break through the native limitation of silicon energy gap and expand its photo-response range. Plasmon modes improve detectors responsivity by the high hot electrons production. In this letter, we designed a C-shaped groove array carved on gold/silicon substrate, and numerically studied its optical properties and hot electron responsivity. An especial electromagnetic resonance (the dipole toroidal mode) can be excited in this nanostructure, which brings a nearly perfect absorption (∼98%) at 1395 nm and a higher responsivity. Our simple design demonstrated an effective hot electron photodetector without extra collect electrodes.