| Metal oxide conductive thin films such as ITO, SnO2, ZnO, and NiO are widely used in many applications including solar cells, transparent electrode, monitor, luminescent devices, and gas sensors, etc. The composite metal oxide thin films possess good properties of the traditional metal oxide thin films. The electrical, optical properties of the composite thin films can also be improved by changing the components to meet different practical needs. Dual metal oxides have attracted considerable attention because of the potential requirements of the synthesis of the advantages of different transparent metal oxides such as SnO2, ZnO, NiO, etc.In this paper, the undoped, Cu/Li/Ag/Ru-doped, Ru-Li co-doped NiO thin films, ZnO-SnO2, NiO-SnO2, NiZnO composite thin films, Ag-Li co-doped ZnO-SnO2and Ru-Al co-doped NiO-SnO2were prepared on Si, ITO and glass substrates by Sol-Gel method. The effects of process conditions such as the sol concentration, doping concentrations, annealing temperatures, and layer number etc. on the structure, morphology, and photoelectric characteristic of the thin films were studied by X-ray diffraction, Scanning electron microscope, Transmission electron microscopy, UV-Vis photometer, Electrochemical workstation etc. The specific contents of the dissertation are as follows:First, the influences of the mole ratio between Zn and Sn on the structure, morphology and photoelectric properties of the ZnO-SnO2composite thin film are investigated. The results show that when the mole ratio is4:1, the crystallinity of the composite film is better, the grain size is smaller, and the photoelectric properties are also improved. On that basis, we prepared Ag-Li co-doped ZnO-SnO2films and annealed at different temperatures. The characterization results show that the co-doped film annealed at500℃exhibits a better electrical property and the electrical conductivity increases approximately3times compared with the undoped ZnO-SnO2films.Second, we investigated the influences of the sol concentration, number of the layers, annealing conditions, and the doping of Cu and Ru-Li on the photoelectric properties of NiO films. The concentration of Ni+in the sol is0.2mol/L. The samples are annealed at400℃for one hour. The transmittance of the3%Ru-4%Li co-doped NiO bilayer film is above80%. And the films have a low threshold voltage and a big on/off ratio.Based on the pure NiO thin film, we have fabricated the undoped and Ru-Al co-doped NiO-SnO2composite films with different mole ratio between Ni and Sn and surveyed the effects of the mole ratio of Ni and Sn and the doped metallic element on the film properties. The results show that the5%Ru-1%Al co-doped NiO-SnO2film with the mole ratio of Ni and Sn of3:1exhibit better comprehensive properties. The diffraction peaks are the most acute which illustrates a good crystallinity. And the transmittance is up to about80%. The average threshold voltage is1.40V and on/off ratio is248with an increase of16%compared to the pure NiO thin film.In addition, the effects of the mole ratio between Ni and Zn on the film structure, morphology and photoelectric properties are also investigated. From the testing of ITO/NiZnO film/GaIn device, it is found that the NiZnO films with Ni/Zn molar ratio of1:1do not have resisitive swithing properties as the oxygen vacancy can hardly from filament conduction. However, when the molar ratio is more than1:1, good resisitive swithing properties occurs, especially for the the sample with Ni/Zn molar ratio of2:1. |
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