Construction of GaN/Ga2O3 p–n junction for an extremely high responsivity self-powered UV photodetector

Abstract

A self-powered ultraviolet photodetector was constructed with GaN/Ga₂O₃ p–n junction by depositing n-type Ga₂O₃ thin film on Al₂O₃ single crystals substrate covered by p-type GaN thin film. The fabricated device exhibits a typical rectification behavior in dark and excellent photovoltaic characteristics under 365 nm and 254 nm light illumination. The device shows an extremely high responsivity of 54.43 mA W⁻¹, a fast decay time of 0.08 s, a high I_light/I_dark ratio of 152 and a high detectivity of 1.23 × 10¹¹ cm Hz^1/2 W⁻¹ under 365 nm light with a light intensity of 1.7 mW cm⁻² under zero bias. Such excellent performances under zero bias are attributed to the rapid separation of photogenerated electron–hole pairs driven by built-in electric field in the interface depletion region of GaN/Ga₂O₃ p–n junction. The results strongly suggest that the GaN/Ga₂O₃ p–n junction based photodetectors are suitable for applications in secure ultraviolet communication and space detection which require high responsivity and self-sufficient functionality.