Engineering Interfacial Defects in β -Ga ₂ O ₃ /Lu ₂ O ₃ Heterojunctions for Achieving High Detectivity in Self-Powered Solar-Blind UV Communication

Solar-blind ultraviolet (SBUV) optical communication system leverages atmospheric ozone absorption to fulfill low background noise, enabling high anti-interference and security in complex environments, which has gradually attracted widespread attention. Gallium oxide (Ga 2 O 3 ) as an ultrawide bandgap semiconductor possesses excellent physicochemical stability and electron mobility, making it an ideal choice for photodetectors in SBUV communication systems due to its intrinsic spectral alignment with the solar-blind spectrum. Nevertheless, high-concentration oxygen vacancy defects and deep intrinsic acceptor levels, respectively, constrain conventional Ga 2 O 3 -based photodetectors’ responsivity and block homojunction formation via p -doping. Furthermore, externally biased metal–semiconductor-metal structure devices pose challenges in attaining miniaturization and integration simplicity. To address these constraints, this study employed plasma-enhanced chemical vapor deposition combined with spin-coating processes to fabricate an annealing-optimized β -Ga 2 O 3 /Lu 2 O 3 heterojunction photodetector with a precisely modulated oxygen vacancy concentration. The 650 °C-annealed detector realized a low dark current, a 5.1 × 10 3 photo-to-dark current ratio, and a 7.07 × 10 11 Jones detectivity under 254 nm illumination at 0 V. First-principles calculations corroborated that carrier transport across the heterojunction interface is governed by a type-II band alignment. Significantly, a high-fidelity solar-blind ultraviolet communication system using a β -Ga 2 O 3 /Lu 2 O 3 heterojunction detector achieved accurate baseband transmission via on–off keying modulation. The present work supplies a key foundation for the design and fabrication of subsequent-generation self-powered SBUV optical communication systems.