Study Of A Novel Solar-blind Ultraviolet Photodetector Based On ?-Ga₂O₃ And Graphene

The Solar-blind ultraviolet?UV?light is an electromagnetic radiation with a wavelength between 200 nm and 280 nm.The solar-blind UV photodetector does not need cooling system and has good environmental adaptability.It is widely used in missile warning,ultraviolet imaging,and ultraviolet security communication and so on.Although solar-blind UV photodetectors have a series of advantages,some of the common problems of current solar-blind UV photodetectors as follows:the surface state and pinning effect of the wide bandgap semiconductor,resulting in poor performance of semiconductor-to-metal contact;The common metal electrode makes the effective reception rate of the optical signal drop,which easily leads to lower performance parameters of device;the material preparation conditions based on the semiconductor micro-nano structure are not precisely controlled,and the device prepared is easily affected by environmental factors,making the poor repeatability and stability of the device.In order to solve the problems above,In this study,we deposited a layer of Cr/Au electrode on the unpolished surface of a n-type beta-gallium oxide??-Ga₂O₃?wafer and transferred multi-layer graphene on the other side.The as-assembled MLG-Ga₂O₃heterojunction device exhibited not only rectifying behavior,but also obvious sensitivity to Solar-blind ultraviolet light illumination?254 nm?with very good stability and reproducibility.The responsivity and detectivity were estimated to be 39.3 A/W and5.92×10¹³ Jones,respectively,which are much better than most of the Ga₂O₃nanostructures based devices ever reported.What is more,further spectral response analysis revealed that the photodetector was highly sensitive to UV light with wavelength less than 254 nm,but was nearly blind to photons with wavelength longer than 280 nm.Such a spectral selectivity is in good consistence with the operation mechanism.The above results signify that the present simply-structured MLG-Ga₂O₃ photodetector will have promising application in future optoelectronic systems.