Abstract: 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.

Key words: Ga₂O₃ nanocrystals, Sol-gel method, Ultraviolet photodetector, Self-powered