High-performance self-powered NiO/Ga ₂ O ₃ heterojunction solar-blind photodetector driven by a strong built-in electric field

Self-powered solar-blind photodetector offers irreplaceable advantages for applications such as wearable electronics and ultra-low power systems, but their performance is often limited due to the absence of an external bias. In this work, we demonstrate a high-performance self-powered photodetector based on a well-designed NiO/Ga₂O₃ p-i-n heterostructure that requires no complex pre-treatment methods. The photodetector exhibits a high photo-to-dark current ratio of 378, a high responsivity of 137 mA W^-1, and fast response times of 27 ms/650 ms. Furthermore, we quantitatively elucidated the physical origin of the self-powered behavior. The analysis of the p⁺-n^-one-sided abrupt junction, based on repeatable capacitance-voltage characterization, confirmed the presence of a strong built-in electric field with a calculated maximum field strength of 136 kV cm^-1. It is the fundamental driving force for the photodetector's excellent self-powered performance.