Preparation And Characterization Of Aluminum Doped Zinc Oxide Thin Films And Nanorod Arrays

Because of its excellent optical and electrical properties, ZnO:Al(ZAO)thin films are regarded as an alternative transparent conductive material to ITO,which are of interest for a various applications such as displays,window coating,gas sensors and solar cells. Owing to its special photoelectric properties,1D ZnO nanostructures have attracted much research attention for a wide range of applications such as ultraviolet,piezoelectric devices,field emission.But to the best of our knowledge,by far few reports have been made on Al-doped ZnO nanorod arrays by hydrothermal method.In this paper,the research of ZAO thin films and nanorod arrays was combined organically by a reasonable experimental method.ZAO thin films with high preferential c-axis orientation were deposited on glass substrates using sol-gel method.The effects of the processing parameters,including solution concentration,Al doping, preheating and annealing temperature,on the microstructure,electrical and optical properties of the films were investigated.The results showed that the optical and electrical properties of the films were strongly related to the crystallographic orientation and surface morphology of the films. And higher crystal orientation was favorable for reducing the resistivity. The film without preheat treatment exhibited only a small preferential c-axis.The lowest sheet resistivity(515Ω/□)was achieved in the film that contained 2at%of aluminum with 15 layers,using 300℃as the preheating temperature,and 550℃as the annealing temperature.In this case,the transmittance of the film was over 83%with the visible wavelength region.The probable mechanisms underlying the preferential c-axis orientation of the films are the initial orientation due to heterogenous nucleation and the final growth orientation at the film/substrate interface.Well-aligned Al-doped ZnO nanorod arrays with a narrow diameter distribution were successfully grown on glass substrates by hydrothermal method,where the substrates were spin-coated with seed layer.The effects of the processing parameters on the morphology,size and properties were investigated.The results showed as follows:well-aligned ZAO nanorods with an average diameter of 50 nm crystallized along[002] direction were grow vertically on the substrate;the surfactant PEI can promote the rod-like growth of the ZAO nanostructures;with increasing Al doping,the ultraviolet emission of the arrays blue shifted.The best photoluminescence performance appeared when the Al doping is 2at%.The results showed that the Al-doping can enhance the photoluminescence intensity of ZnO nanorod arrays,which provide a new method on the application of 1D ZnO nanostructures in the optical field.