【Device Papers】Interface states and related trap assisted tunneling in p-GaN/n-Ga₂O₃ heterojunction solar-blind photodetectors

      Researchers from Xiamen University have published a dissertation titled " Interface states and related trap assisted tunneling in p-GaN/n-Ga₂O₃ heterojunction solar-blind photodetectors " in Applied Surface Science.

Abstract

      Ga₂O₃-based p-n heterojunction photodetectors (such as p-GaN/n-Ga₂O₃ devices) are promising for solar-blind ultraviolet detection because of their self-powered operation, fast response, and strong visible-light rejection. However, the role of interface states in carrier transport and photoelectric gain remains unclear. In this work, the role of interfacial state in p-GaN/n-Ga₂O₃ heterojunction UVC PDs was investigated by combining temperature-dependent I–V, C–V, and C–f measurements. The PD exhibited a pronounced threshold-like surge in UVC photoresponse (from 0.018 A/W at −1.5 V to 32 A/W at −10 V) under 254 nm illumination, a blueshift of the spectral response peak wavelength (from 283 nm at −1.5 V to 254 nm at −10 V), enhanced selectivity ratio R_254nm/R_400nm (from 30 at −1.5 V to 5684 at −10 V) and prolonged response time (from 31 μs at 0 V to 105 μs at −10 V) after −1.5 V. It was showed that the interface states could only be activated by UVC illumination. The photoactivated interface states were located at 0.246 eV below the conduction band of Ga₂O₃ side, which contributed to the above device performance by the trap-assisted tunneling beyond −1.5 V. These findings establish an experimental and mechanistic basis for controlling interface-trap-mediated carrier transport and optimizing the gain-selectivity-speed trade-off in p-GaN/n-Ga₂O₃ solar-blind photodetectors.

DOI：

https://doi.org/10.1016/j.apsusc.2026.168101