High gain β-Ga₂O₃ solar-blind Schottky barrier photodiodes via carrier multiplication process

β-Ga₂O₃, which is a ultra-wide band-gap semiconductor, is an attractive material for next-generation solar-blind photodetectors. A high gain solar-blind Schottky barrier photodetector using an exfoliated single crystalline β-Ga₂O₃ nano-layer was demonstrated by employing internal carrier multiplication process. Excellent spectral selectivity with high responsivity was obtained between UV-A and UV-C wavelengths with fast response/decay characteristics. The gain of our β-Ga₂O₃ solar-blind PD was ∼3.78 × 10³ under the multiplication mode at the reverse bias of −60 V, where the peak electric field was estimated to be 4.3 MV/cm (equivalent to impact ionization coefficient of 5 × 10³ cm⁻¹). Compared with non-multiplication mode, outstanding photo-sensing performances were achieved under the multiplication mode, including a responsivity of 8.18 A/W, a photocurrent-to-dark-current ratio of ∼10³ and external quantum efficiency of ∼4 × 10³%. High gain via carrier multiplication process in a β-Ga₂O₃ photodiode proposes a new route toward high performance solar-blind deep-UV photodetectors.