Research On Hydrothermal Synthesis,Annealing Of ZnO Nanorod Arrays And Their Ultraviolet Photodetectors

Zinc oxide(ZnO),a very important direct wide bandgap semiconductor materials,has a bandgap of about 3.37 e V at room temperature and large exciton binding energy(60 me V).Also,it has some advantages,such as good photoelectronic properties,easy fabrications and nontoxic.At present,it has widely used in some fields,such as solar cells,light emitting diodes and ultraviolet(UV)photodetectors.ZnO nanorood arrays have the unique structure,large specific surface area and direct transport path for electrons,which are one of the most promising nanostructures to build high-performance UV photodetectors.In this thesis,ZnO nanorod arrays were grown by a hydrothermal method,UV photodetectors were built using the ZnO nanorod arrays as photosensitive layer and their performances were investigated.Furthermore,the performances of UV photodetectors based on ZnO nanorod arrays from different growth conditions and annealed at different temperatures are investigated.The main research contents and detailed results are as follows:(1)The hydrothermal growth of ZnO nanorod arrays and the performance of their UV photodetector were investigated.ZnO nanorod arrays were grown on an FTO interdigital electrodes substrate,the concentration of precursors,growth temperature and time were 0.05mol/L,93 ℃ and 2 h,respectively,the results showed that the ZnO nanorods almost grew perpendicular to the substrate densely,well-aligned ZnO nanorod arrays with hexagonal wurtzite structure were obtained.Furthermore,the UV photodetector was established using the as-grown ZnO nanorood arrays as the photosensitive layer,and the device showed good response to UV light,its responsivity,photocurrent gain,sensitivity,response time,decay time for this device were 1.06 A/W(3 V),3.55(5 V),37.93(-0.05 V),0.8 s,3.8 s,respectively.(2)The hydrothermal growths of ZnO nanorod arrays under different conditions and their UV photodetectors were investigated.ZnO nanorod arrays were grown at different precursor concentrations of 0.01 mol/L,0.025 mol/L,0.025 mol/Land 0.075 mol/L,respectively,the growth temperature and time were of 93 ℃ and 2 h,respectively.It was found that the average diameter of ZnO nanorods increased and the crystallinity quality improved gradually with increasing the precursors concentration.In addition,ZnO nanorods arrays were grown at three different temperatures of 88 ℃,93 ℃ and 98 ℃.The results showed that the diameter distribution range of ZnO nanorods became narrower and the average diameter decreased with increasing the growth temperature.ZnO nanorood arrays were grown with precursor concentration of 0.05 mol/L and growth temperature of 2 h,and UV photodetectors based this nanorood arrays had optimal performance.(3)ZnO nanorod arrays were annealed at different temperatures and the performances of their UV photodetectors were investigated.The as-grown ZnO nanorod arrays were annealed at different temperatures,the annealing temperatures were 350 ℃,400 ℃,450 ℃and 500 ℃,respectively.It was found that the ZnO nanorods aligned denser and more uniform with increasing annealing temperature.In addition,UV photodetectors based on the ZnO nanorod arrays annealed at different temperatures was fabricated,the device had optimal performance when annealed at 450 ℃.