Solar-Blind Ultrathin Sn-Doped Polycrystalline Ga2O3 UV Phototransistor for Normally Off Operation

Deep ultraviolet (DUV) photodetectors (PDs) based on ultrawide bandgap beta-Ga2O3 have great potential for aerospace, military, and civilian applications, especially because of their inherent solar blindness. An 8 nm thick Sn-doped polycrystalline beta-Ga2O3 semiconductor is used as the channel material for a solar-blind PD in this study. The beta-Ga2O3 channel is fully depleted by upward bending of the energy band owing to the work function difference between the highly p-type Si (gate electrode) and beta-Ga2O3, resulting in normally off behavior with a positive threshold voltage under dark conditions. The normally off behavior is beneficial for simplicity of the gate-driver circuitry and low power consumption under standby conditions. The fully depleted 8 nm thick polycrystalline beta-Ga2O3 exhibits high-performance DUV detection capability of light at 215 nm: a low dark current of 29.3 pA and high photo-to-dark-current ratio of approximate to 10(4) at zero gate voltage. This fully depleted n-type beta-Ga2O3 semiconductor with a wafer-scale substrate can expedite the realization of high-performance and low-power-consumption solar-blind PDs.