The Optimization Of ZnO Nanorods’ Growth Via Hydrothermal

Since the mid-1990 s, one-dimensional(1-D) nanostructure semiconductor materials became the forefront of nano-materials research. Compared to the other one-dimensional nanostructure materials, one-dimensional ZnO with wurtzite structure,is a broadband gap semiconductor material with a high exciton binding energy(60me V approximately) at room temperature, which can obtain high-exciton light emission. Compared to other one-dimensional ZnO nanostructure materials, ZnO nanorods have a large specific surface area, low defect density, good optoelectronic properties and other advantages. In this paper, ZnO nanorod arrays grown via the hydrothermal method are used to study the changes morphology, optical and other properties of ZnO nanorods under different reaction conditions.A layer of ZnO was deposited on quartz substrate as the seed layer ZnO nanorods seed layer on a quartz substrate with the sol-gel method before the ZnO nanorods were grown via hydrothermal method. The effects of sol concentrations, with/without Na dopant, and the number of spin-coating times on the properties of ZnO films are discussed. From XRD patterns, all the seed layer samples with different sol concentrations show three peaks of(100),(101), and(002). At a sol concentration of0.8 mol / L, the sample shows a clear preferred orientation along the(002) peak. With the introduction of Na dopant, the Na atoms substitute the Zn atoms in ZnO lattice and form stable Na Zn defects that stress the lattice in the directions of(101) and(001), and develop it in(002) direction, which improve the preferential orientation of the film.During the film preparation process, the introduction of the buffer layer, effectively reduce the crystal mismatch between the film and the substrate, and the crystalline quality is improved. Under the circumstances of the same concentration of the sol, the effects of spin-coating times on the film properties could be neglected.In this thesis, the influencing factors for the properties of ZnO nanorod arrays grown by hydrothermal method are discussed, such as the precursor concentration, the reaction time, the function of seed layer, the effect of Mg doping and polyethylene imine morphology, and so on. In our experiment, with the increase of the precursor concentration, the length of ZnO nanorod decreases, and the diameter of nanorod increases, and the the orientation of(002) peak in X-RD measurement is obviously.Furthermore, the ultraviolet luminescence intensity increases with the increasing of theprecursor concentration, too. Compared with the samples with Na doping, as well as the samples without doping, the samples grown on AZO(Al doped ZnO) substrates show a well orientation and high rod intensity. In Pl measurement, a strong purple emission peak near 391 nm and a weak blue emission peak near 465 nm are observed.The doping of Mg into ZnO crystal results in a reduction of nanorod diamenter, and induces a change of the end face of nanorod from six prismatic structure into a sharp cone-shaped structure, and the same phenomena was observed from the samples added with polyethyleneimine imine during sol preparation process. For the sample with the Mg/Zn atomic ration of 6:100, the length of nanorod reaches to 2.32 nm, and the intensity of UV emission reaches maximum. For the samples with the adding polyethyleneimine imine during sol preparation process, the length of nanorod reaches to 4.39 nm at the concentration of 0.003mol/L. In PL measurement, a sharp UV emission appears near 393 nm, and the UVB emission reaches to maximum.