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-SiO2-p-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-SiO2-p-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.