Vertical solar blind Schottky photodiode based on homoepitaxial Ga2O3 thin film

Abstract

High quality germanium doped β-Ga2O3 epitaxial film was grown by PMBE technique and fabricated into a vertical type Schottky photodiode with a Pt/nGa2O3/n+Ga2O3(010) structure. The photodiode exhibited excellent rectifying characteristics with a turn on voltage ~ 1V and near zero bias leakage current ~ 100 fA. The photoresponse measurement showed a true solar blind sensitivity with cutoff wavelength ~260 nm and an out of band rejection ratio of ~104. A maximum responsivity of 0.09 A/W at 230 nm was measured at zero bias, corresponding to an external quantum efficiency of ~52 %. The time response of the photovoltaic diode is in the millisecond range and has no long-time decay component which is very common in the MSM photoconductive wide bandgap devices. The photodiode performance remains stable up to 300°C, suggesting its potential use for high temperature applications.