Ultraviolet photodetectors based on non-stoichiometric amorphous Ga2O3−δ thin films deposited by radio-frequency powder sputtering

Abstract

We report the performance of ultraviolet (UV) photodetectors based on non-stoichiometric amorphous Ga<inf>2</inf>O<inf>3−δ</inf> thin films deposited using the radio-frequency powder sputtering method. At a substrate temperature of 25 °C, the Ga<inf>2</inf>O<inf>3−δ</inf> film grew with an amorphous phase on a sapphire (0001) substrate. Hard X-ray photoelectron spectroscopy analysis revealed that the chemical composition of the as-deposited thin film was highly non-stoichiometric owing to the oxygen deficiency associated with sub-oxide Ga<inf>2</inf>O and metallic Ga species. Metal–semiconductor–metal photodetectors were fabricated, and their photoresponse properties under UV exposure were investigated. The photo-to-dark current ratio was estimated to be 2.91 × 105. The photoresponsivity and specific detectivity were calculated to be ∼29.54 A/W and 8.95 × 1014 Jones, respectively, at an applied bias of 10 V and a wavelength of 250 nm. Our results indicate that non-stoichiometric amorphous Ga<inf>2</inf>O<inf>3−δ</inf> thin films with thicknesses less than 100 nm are suitable for the fabrication of solar-blind photodetectors with self-powered characteristics. © 2025 Elsevier B.V., All rights reserved.