Gallium oxide nanocrystals for self-powered deep ultraviolet photodetectors

Zero-dimensional colloidal nanocrystals (NCs) of gamma-phased gallium oxide (γ-Ga2O3) were successfully synthesized using the sol-gel method, resulting in nanocrystals with high crystallinity. Heterojunction photodetectors were then constructed by employing spin-coating technology to deposit γ-Ga2O3 NCs film of varying thicknesses onto p-type GaN substrates. The resulting devices demonstrated self-power capability through a photovoltaic effect when exposed to ultraviolet light illumination. Notably, a device with a 300 nm thick active layer, annealed in 400 °C, exhibited a responsivity of 6.7 × 10–3 A W–1, a detectivity of 3.10 × 1011 Jones, and an external quantum efficiency of 3.2% under 254 nm light illumination at 0.16 mW cm–2, all without the need for an external power supply. These findings suggest promising practical applications for such photodetectors in single-point imaging systems. This study presents a straightforward and viable approach for developing high-performance and self-powered ultraviolet photodetectors based on zero-dimensional γ-Ga2O3 NCs, thereby opening up possibilities for various photonic systems and applications that do not rely on an external power supply.