| Ultraviolet(UV)light plays an important role in the fields of medical sterilization,animal and plant biosynthesis,and chemical industry.Among them,short-wave ultraviolet light(100nm?280nm)is widely used in ultraviolet communications,missile early warning and space detection due to its natural "solar blind" characteristic.In recent years,UV detectors have developed rapidly.Among them,self-powered detectors can work without external power source,which is conform to the trend of miniaturization of optoelectronic devices.Ga2O3 has an ultra-wide band gap(4.9eV),and the absorption edge of Ga2O3 corresponds to the solar blind band,which is an ideal UV detection materialOn the one hand,the nanorod arrays are the ideal structure for building high-performance UV photodetectors due to the excellent advantages.Such as large specific surface area,fast carrier transport channels,and relatively low preparation costs.On the other hand,in the heterojunction photo detector,due to the difference in energy band structure,carriers diffuse freely,and a built-in electric field is generated in the junction region.When a photon was irradiated to the space charge region,the electrons in the low energy band were excited,resulting in an increase in the carrier concentration of the semiconductor material,which was separated and transferred to the corresponding electrode under the action of the built-in electric field to achieve the self-powered property.In this paper,?-Ga2O3 nanorod arrays with controlled morphology were prepared by hydrothermal method.?-Ga2O3/TiO2 and ?-Ga2O3/Cu2O heterojunctions were constructed with TiO2 and Cu2O microspheres,respectively,and the UV photodetectors with self-powered characteristics were prepared.The main research contents are as follows:1.Explore the optimal parameters and successfully prepare an ?-Ga2O3 nanorod arrays with controllable morphology and good crystallinity.Using Ga(NO)3 solution as the precursor,by adjusting the precursor concentration,hydrothermal reaction temperature and time,the conditions of hydrothermal reaction with 150? for 12 hours were determined to prepare GaOOH nanorod arrays.After annealing treatment(500?,4 hours),?-Ga2O3 nanorod arrays with good morphology and high crystal quality was obtained.2.A self-powered solar blind UV detector based on the ?-Ga2O3/TiO2 heterojunction was constructed.A TiO2 was prepared on the surface of the ?-Ga2O3 nanorod arrays by magnetron sputtering,and combined with a graphene/silver nanowires composite film to form a self-powered solar blind UV photodetector.Under 0 V bias and 254 nm UV light,the Responsivity of the detector is 0.36 mA/W,the Detection rate is 1.57×1010 cm·Hz1/2·W-1,the Iphoto/Idark ratio reaches to 275,and the rise time and decay time are 0.727 s and 0.140 s respectively.In addition,the photoelectric response characteristics of the detector under vacuum,oxygen and nitrogen environment were also tested and compared.The results show that the high relative humidity in the air environment will greatly increase the light and dark current of the detector and slow down the response speed.The presence of oxygen in the test environment will reduce the dark current of the detector,increase the photocurrent,and slow down the response speed.3.A self-powered photoelectrochemical UV detector based on ?-Ga2O3/Cu2O p-n junction was constructed,and the distinguish of incident light in different wavelength bands was realized.Cu2O microspheres were synthesized on the surface of ?-Ga2O3 nanorod arrays by chemical bath deposition method.Under the irradiation of 254 nm or 365 nm ultraviolet light,different transmission directions of photo-generated carriers in the detector will produce a photoresponse current with opposite directions,which can effectively distinguish these two types of incident light.The ?-Ga2O3/Cu2O p-n junction photodetector has a Responsivity of 0.57 mA/W(0.42 mA/W)upon 365 nm(254 nm)UV light.In addition,the detector also has a fast response speed,with a rise time of only 103 ms under 365 nm UV light. |
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