| Solar-blind ultraviolet photodetectors(PDs)and its related technologies can accurately detect the weak signal while being disturbed by the intense background ultraviolet band radiation.The solar-blind ultraviolet photodetector,working in the atmospheric environment,has,in particular,advantaged predominance in accuracy of detecting deep ultraviolet rays due to the absorption of deep ultraviolet light by the ozone layer,and possesses huge potential application value in military and civilian fields,such as ultraviolet communication,missile tracking,rocket tail flame detection,quantum communication,space exploration,high-energy physics,corona detection,environmental monitoring,biomedicine,etc.?-Ga2O3,a natural solar blind ultraviolet material,full of potential capability,holds the band gap of 4.8 eV,breakdown filed strength of 8 MV/cm and the thermal and chemistry stability and lures,increasingly,specialists and scholars in recent years.Graphene,a two dimensional materials with hexagonal cellular lattice structure,is structured in the bonding way of sp2 hybridized orbital by only a single carbon atomic layer and the Pz orbitals of internal adjacent carbon atoms,normal to the plane of atomic layer,form a extended ? bond over the whole layer,which is half-full and strong delocalized.Therefore,graphene has extremely high carrier mobility and optical transparency ranging from the deep-UV to infrared spectral,which means graphene is a superior transparent electrode and well compatible with photodetectors.Thus,the distinctive integration,by single layer graphene and ?-Ga2O3 thin film,provides the future advance of deep ultraviolet integrated devices with infinite possibilities.The main research work of this paper is comparing the photoelectric property differences of photodetectors,caused by different electrodes on an epitaxial ?-Ga2O3 thin film,including double single layer graphene electrodes,double Au/Ti electrodes and single layer graphene and Au/Ti electrodes.The main research results are as follows:1.The high-quality epitaxial ?-Ga2O3 thin film is grown along the crystal orientation of(201)lattice plane on(0001)sapphire substrate with size of 1 cm × 2 cm via radio frequency magnetron sputtering technique and the ambient gas,pressure,deposition temperature,sputtering power and the thickness and bandgap of the as-grown thin film are argon,1 Pa,750?,75 W,500 nm and 4.8 eV,respectively.2.Single layer graphene is transferred to the top of the as-grown ?-Ga2O3 thin film by wet transfer method,the surface of which is smooth,clean and uniform in thickness without folds observed by optical microscope.The lateral Au/Ti electrodes are deposited by direct current magnetron sputtering technique,using metal pattern plate to keep roughly equal interval between both electrodes.3.The three as-fabricated plane solar-blind ultraviolet photodetectors with SLG-SLG(single layer graphene),SLG-AuTi and Au/Ti-Au/Ti electrodes still exhibit stable photoresponse after multiple illumination cycles,indicating the strong robustness and reproducibility.Photodetector with SLG-SLG electrodes possesses much higher response speed(?78 ms),light-dark current ratio(?141),254 nm/365 nm rejection ratio(?1020)and detectivity(?6.29×1011 Jones)than that of two other photodetectors.In the end,some deep sights in the intrinsic photoelectric mechanisms of three photodetectors with different electrodes are put,expounding the interface barrier in between the electrode and ?-Ga2O3 thin film has an effect in the performance of these devices in working state. |
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