Growth And Field Emission Properties Of Zn O Nanostructures

As the most intuitionistic component in interaction between human and machines, displays and their devices have been widely applied in and deeply penetrated into all aspects of social development. With the improvement of the demand of interactive interfaces and development of information society, displays show a trend of high resolution, flat and digital. Although traditional CRT devices could provide high imaging quality, they are eliminated gradually by its large volume and power consumption. The replaced LCD and PDP devices have advantages in power consumption and volume. However, the imaging qualities of LCD and PDP devices are not as high as CRT devices. FED devices with low power consumption, small volume and high imaging quality which is comparable with CRT devices attracted a great deal of attention in recent years. In FED researches, the most important thing is to find a proper field emission(FE) cathode. ZnO is an ideal material as field emission cathode because of its high melting point, high mechanical strength and tolerance of terrible conditions.We studied the preparation of different morphologies of ZnO nanostructures and their field emission properties on different substrate via CVD method. On silicon substrate with Au catalyst, the morphology of the nanostructures is substrate position controlled while Zn is excessive in the whole procedure. If Zn is not excessive in the whole procedure, the morphologies of the nanostructure approach to be wire-like. FE measurements imply that FE properties are related to the curvature of the top of nanostructures.Meanwhile, we obtained two kinds of ZnO seed layers on silicon, one of them utilize MgO as buffer layer between ZnO and silicon, the other one have no MgO buffer layer. Then we obtained nanowire arrays grown on the two seed layers via CVD. When compared with ZnO seed layer which didn't utilize MgO buffer between seed layer and silicon substrate(noted as seed layer without MgO), ZnO seed layer which utilize MgO buffer between seed layer and silicon substrate(noted as seed layer with MgO) show a higher crystallinity and single orientation. As for nanowires grown on the seed layers, nanowire arrays with MgO show more vertical alignment and better FE properties. Raman spectra show that both samples have few oxygen vacancies. In addition, after annealed at 800 °C in oxygen, nanowire arrays with MgO show degraded FE properties at low electrical field, better FE properties at high electrical field since sample without annealing process cannot increase sustainedly as the electrical field increase. Photoluminescence spectra show that this phenomenon results from the decrease of the oxygen vacancies. When compared with nanostructures grown on Si substrate with Au catalyst, the nanowire arrays grown on ZnO seed layer show better FE properties.