Quasi-two-dimensional β-gallium oxide solar-blind photodetectors with ultrahigh responsivity

Solar-blind photodetectors have received a great deal of interest owing to their high selectivity for deep ultra-violet tight in the presence of visible tight. The development of alternative materials and innovative device designs are necessary for such solar-blind photodetectors, as the currently available commercial devices have issues pertaining to chemical and thermal instability, cost, and material handling due to their rigidity. Here, we fabricated solar-blind photodetectors based on exfoliated quasi-two-dimensional beta-Ga2O3 flakes with optimal opto-electrical properties (direct bandgap of similar to 4.9 eV), chemical and thermal stability, and then systematically characterized their photoresponsive properties. The fabricated device structures were based on back-gated field-effect transistors, allowing us to control the dark currents. These photodetectors exhibit extraordinary photoresponsive properties including the highest responsivity (1.8 x 10(5) A W-1) among reported semiconductor thin-film solar-blind photodetectors.