Surface plasmon enhanced quantum efficiency of metal-insulator-semiconductor junctions in the visible

Abstract
Narrowband photosignals with quantum efficiencies up to 30% are observed on Al‐SiO2p‐Si junctions. The frequency selective photosignals are due to surface plasmon polaritons confined to the metal‐air interface excited by grating coupling. The best results are achieved with Ag‐Al‐SiO2p‐Si junctions providing a 12‐nm linewidth and a signal to background ratio of 7:1 at a wavelength of 632.8 nm. The spectral sensitivity of these photodetectors is tunable over the whole visible spectrum either by a variation of the tilt angle or by a dielectric coating.