Simple (YGa)₂O₃/F-SnO₂ Heterojunction-Based Solar-Blind Ultraviolet Photodetector Operable in Two Modes With Superb Performance

Abstract

Gallium oxide (Ga₂O₃), with its wide direct bandgap (~4.9 eV) and high stability, holds great potential for applications in solar-blind ultraviolet (SBUV) photodetectors. In this work, simple vertical-structured SBUV photodetectors based on (YGa)₂O₃/F-SnO₂ (YGO/FTO) heterojunctions were designed and fabricated for the first time. Owing to the wider bandgap of Y₂O₃ (~5.9 eV) compared to Ga₂O₃ and the stronger Y–O bonding relative to Ga–O, the YGO alloy films exhibit an expanded bandgap (~5.2 eV) with fewer oxygen vacancies than pure Ga₂O₃. This results in SBUV photodetectors with an extremely low dark current and fast photoresponse. Moreover, the YGO/FTO-based photodetectors demonstrate excellent performance in both biased and self-driven modes. At 0 V bias, the photodetector with a YGO layer thickness of 246 nm exhibits an exceptionally low dark current of 0.145 pA, a short photoresponse time of 15 ms, high responsivity of 12.2 mA W⁻¹, and a detectivity of 2.84 × 10¹² Jones. At a bias of −10 V, the device with a 425 nm-thick YGO layer achieves a high photocurrent/dark current (I_photo/I_dark) ratio of 10⁶, UV/visible rejection ratio of 10⁵, and remarkably high responsivity of 12.3 A W⁻¹ with a detectivity of 1.08 × 10¹⁵ Jones. These results highlight the great promise of YGO alloys in developing simple vertical-structured YGO/FTO high-performance photodetectors for ultraweak SBUV detection.

Keywords

gallium oxide / heterojunction / photodetector / solar-blind / yttrium doping

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