Metal-semiconductor-metal photodetectors using widegap semiconductor capping layer

To improve the Schottky contact performances and carrier confinement, we employed the wide bandgap material InAlGaP for the capping in the metal-semiconductor-metal photodetectors (MSM-PDs). The electrical behaviors of InAlGaP/GaAs MSM-PD are studied by reverse dark current-voltage measurements at different temperatures. The reverse characteristics of the Schottky contact are examined by taking into account the dependence of the barrier height on the electric field in the depletion region and hence on the applied bias. We investigated the possibilities of evaluating the main Schottky contact parameters straight on the MSM-PD structure with and without capping layer InAlGaP. We also measured the relationship between the photoresponsivity and difference photon wavelength.