Gallium-based Wide Bandgap Semiconductor Self-powered UV Detector

Recently,the demand of ultra-violet detectors increases significantly,and the miniaturization,integration and low power consumption of detectors have become the focus of research.In this case,self-powered photodetectors can work normally without any external voltage,which is of great significance for realizing the sustainable development of resources and environment.Gallium-based wide band gap semiconductors,such as gallium nitride（Ga N）and gallium oxide（Ga₂O₃）,have high band-gap,strong radiation resistance and high temperature resistance.Among these,they are good candidate material for ultra-violet detection.In this paper,graphene/Ga N Schottky UV detectors,Ni/β-Ga₂O₃ Schottky UV detectors and NiO/β-Ga₂O₃ heterojunction UV detectors have been fabricated successfully,and their photo-response and self-power characteristic were investigated.The main research contents are as follow:1.After introducing combination of a single-layer graphene and Ga N,a fast-response ultraviolet（UV）detector based on a highly-rectifying graphene/Ga N Schottky diode was fabricated.The device was fabricated by mechanically transferring a monolayer graphene onto lightly-doped Ga N and showed ultra-high rectification ratio over>10⁸,a close-to-unity ideality factor and a relatively high Schottky barrier height（1.01 e V）.At zero bias,the graphene/Ga N detector exhibited strong photovoltaic response to UV light with a fast rise/decay time of221/546μs.A trap-related photoconductive mechanism became dominant during the response process when the reverse bias went beyond 1 V,and this could be identified by sharply increased responsivity and decay time in the graphene/Ga N detector.2.After a NiO film was deposited on aβ-Ga₂O₃bulk using RF magnetron sputtering,to fabricate NiO/β-Ga₂O₃ heterojunction UV detectors,and a Ni/β-Ga₂O₃Schottky UV detectors were prepared using e-beam evaporation.These two gallium-based UV detectors have an extremely high rectification ratio（Ni/β-Ga₂O₃～10⁹,NiO/β-Ga₂O₃～10⁸）,low dark current(<10^-7 A/cm²).The ideality factor and barrier height of Ni/β-Ga₂O₃（NiO/β-Ga₂O₃）junction are1.17（2.27）and 1.23 e V（1.53 e V）.At zero bias,the photo-current of the detectors have a good linear relationship with incident light power,which indicates excellent self-powered characteristic.Furthermore,the influence of p-type NiO is negligible during deep UV detection（R254nm/R280nm=8）.