The Growth Mechanism Of ZnO Nanowires Based On Hydrothermal Method

With the changes and continuous development of the times,human beings have entered the Internet era.Now,artificial intelligence is an emerging industry,and new semiconductor nanomaterials have been applied in many emerging fields.ZnO is a typical wide bandgap semiconductor,due to its unique electrical,optical and piezoelectric properties,it has developed rapidly in recent years.ZnO also has diverse nanostructures.One-dimensional ZnO nanomaterials can be used as a good photosensitive material,They have high sensitivity to ultraviolet light and high emission efficiency at room temperature.They can be used to make photodetectors or optical switches.Moreover,it can be applied as a working electrode in solar cell,improving the separation efficiency of the excitons,suppressing the recombination of electrons and hole pairs,and thereby reducing the probability that electrons between the nanocrystals are trapped during the hopping transmission process.In this paper,one-dimensional ZnO nanowires were used as the research object,and ZnO nano wires were successfully prepared by two-step methods:pulsed laser deposition(PLD)and hydrothermal methods.The morphology,crystal crystallization and light emission of ZnO nanowires were studied.Firstly,the factors affecting the properties of pulsed laser deposition of film are studied.Then,the morphology,structure and properties of one-dimensional ZnO nanowires were explored at different deposition times,hydrothermal reaction times and temperatures.And at room temperature,the effect of Annealing on luminescent properties was tested.The main work of this thesis consists of three parts.The first part explores several factors affecting the growth of pulsed laser deposited ZnO thin films,including changing the substrate temperature and pulse energy.By observing the surface morphology and crystal structure of ZnO thin films,the results show that under the same sedimentary time,pulsed laser deposition growth of ZnO thin film seed crystal The suitable conditions for depositing and growing ZnO thin film are substrate temperature of 350 ? and pulse energy of 20 mJ.The second part includes annealing the film which wsa deposited on the Si(100)substrate at 400 ?.The thin film ZnO is acted as the seed layer,and then the ZnO nano wires are hydrothermally grown under certain conditions.The pulsed deposition time and the hydrothermal reaction temperature and time were changed to find the optimal hydrothermal growth conditions for ZnO nanowires.Our work was characterized and verified by XRD,SEM and PL spectra.The ZnO thin film deposited by pulsed laser deposition as a seed layer can effectively buffer the lattice mismatch between ZnO and Si,assist the growth of ZnO nano wires,and have important effects on the growth of ZnO nano wires.The research shows that the ZnO nanocrystals treated by annealing at 400 ? for 1 h is an ideal seed layer for growing ZnO nanowires.Choose the same 0.04 mol/L(M)of Zn(NO3)2·6H2O and HMT 1:1 by volume,hydrothermal temperature 90 ? and the growth time of 6 h are the preferred conditions for hydrothermal growth of ZnO nano wires.In the third part,the luminescence properties of annealing and unannealing at room temperature were studied under the same condition of pulsed laser deposition and hydrothermal treatment.And it was found that the luminescence performance was better after annealing.It is proved that the one-dimensional ZnO nanowire crystal with good crystallinity and excellent luminescence property is obtained under suitable pulsed laser deposition and hydrothermal conditions.