Nano tree-like branched structure with α-Ga2O3 covered by γ-Al2O3 for highly efficient detection of solar-blind ultraviolet light using self-powered photoelectrochemical method

Abstract For photoelectrochemical ultraviolet detector, carrier recombination, low light trapping efficiency and long-distance charge carries transport are the main factors restricting its detection performance. Herein, a novel tree-like branched structure with α-Ga2O3 covered by γ-Al2O3 has been successfully fabricated by simple two-step hydrothermal treatment and applied into the self-powered photoelectrochemical solar-blind detector. Owning to the introduction of γ-Al2O3 layer with ultra-wide bandgap to coat outside of α-Ga2O3, an energy barrier has been established at the semiconductor/electrolyte interface accelerating the photogenerated carriers separation and thus suppressing interfacial charge recombination. Besides, the obtained tree-like branched structure significantly expands the contact surface area between carries and electrolyte to shorten the distance of charge transport improving response speed and brings a larger specific surface area to capture and scatter incident photons enhancing light absorption. Campared with the pure α-Ga2O3, the α-Ga2O3-γ-Al2O3 based on the photoelectrochemical device shows higher responsivity, larger photocurrent density and faster response time to solar-blind ultraviolet signal, some performance improvements exceed 100%, indicating the highly efficient detection.