The Study Of Preparation And Properties Of ZnO Thin Films And Powders

ZnO is a II-VI compound semiconductor with a direct wideband gap of3.37eV and alarge exciton binding of60meV at room temperature. As a new type of functional material，ZnO has excellent optical and electrical properties. ZnO is considered as a promising materialfor short-wavelength optoelectronic devices. On the other hand,ZnO also has a wealth ofnanostructures, such as nanodots, nanowires, nanotubes, nanobelts and nanorings. For a kindof important photocatalyst, ZnO was one of several semiconductors which could realizequantum size effect.It was also gained people comprehensive research in recent years.In this paper, ZnO films and ZnO powers were prepared by the sol-gel method. Thin filmpreparation technology was studied as well as the influence factors on the film structure andperformance of doping ions on the properties of ZnO powder structure and light catalytic effect.The work includes the following content:(1) ZnO thin films prepared by sol-gel spin coating method, Preheat treatment temperature,substrate, thin film thickness and the influence of annealing temperature on the film structureand performance was studied. The results showed that both of these factors have influence onthe c axis preferred orientation of ZnO thin films. Preheat the best processing temperature is250℃, Higher than that of ZnO thin film crystallization start temperature film preferredorientation as well, The preferred orientation of single crystal substrate does not favor themembranes. The thicker the thickness of the ZnO films, the smaller it influenced by thesubstrate and the crystallization performance was better; Along with the increase of annealingtemperature, the grain size increased gradually; Preferred orientation gradually increased, thelattice constant decreases firstly and then increased, the minimum was at the temperature of600℃, ZnO thin film resistivity decreased gradually at700℃, ZnO thin film resistivitydecreased to0.61x10~4Ω·cm; And the maximum dielectric constant and minimal loss was atthe temperature of600℃. (2) Experiment was the Na, Mg, Al, La, Ag doping elements, the corresponding dopingnano ZnO powder was prepared. Na doped ZnO nano powder in low doping concentration timeinstead of catalytic efficiency was reduced, with the increase of doping concentration graduallyrestored, the maximum reached at the doping amount of15wt%, doping concentration furtherincreased instead of decreased, the largest photocatalytic degradation rate was56.7%. Mgdoped ZnO nano photocatalytic efficiency was reduced, the optimum doping concentration was10wt%in the doping amount, the photocatalytic degradation rate was43%by methyl orangesolution in3hours when the addition level was0.5g/l. Grain size of Al doped ZnO nanopowder was reduced, the photocatalytic efficiency greatly improved, the best dopingconcentration was10wt%, the3h of the photocatalytic degradation rate was95.7%. La dopedZnO nano powder grain size was reduced, and the light catalytic efficiency did not increasesignificantly, La doping concentration was2.0wt%, the photocatalytic degradation rate was46.3%by methyl orange solution in3hours when the addition level was3.5g/l. Ag compositeZnO nano photocatalytic efficiency increased with a linear illumination time, the bestcomposite coating was1.0wt%, the degradation rate was98.3%by photocatalytic in3hours.