Electrically tunable spectral responsivity in metal–semiconductor–metal photodetectors based on low-dimensional ZnCdS/ZnMgS/GaP, ZnCdS/ZnS/GaP heterostructures

Abstract

We report on growth, fabrication and characterization of metal–semiconductor–metal (MSM) photodetectors based on periodic heterostructures with ZnCdS quantum wells separated by ZnMgS and ZnS barrier layers. Heterostructures were grown on semi-insulating GaP substrates by MOVPE. MSM-diodes with width of Ni–Au interdigitated Schottky barrier contacts and gap between them of 3μm and total detector area of 100×100μm2 have been fabricated. Detecting properties of MSM-heterophotodiodes have been investigated. We observe electrically tunable spectral response of these detectors. At low bias detectors provide narrowband response (FWHM=18nm at the wavelength 350nm) determined by a composition of ZnCdS quantum well. Increasing bias up to 70V shifts maximum detector sensitivity at the wavelength 450nm while narrowband response at 350nm remains. Thus, a two-color detection of light emission is provided.