Preparation And Properties Of Ag-doped And Fe-Doped Zinc Oxide Films

As a wide band-gap semiconductor material,ZnO has excellent physical and chemical properties:its high thermal conduction,high stability of its chemical properties, especially its abundance in resources,low cost and toxicity,thus ZnO is considered having potential application for many fields.If elements like Ga,Si,Al,B and In are doped into ZnO,the performance of ZnO would be greatly improved and the field of its application would be greatly broadened as well.By Ag doping,ZnO has excellent electrical and optical properties especially light sensitivity and nonlinear optical properties.For Fe-doped ZnO,its magneto-optical and magnetic characteristics have attracted much attention.In this work,the Ag-doped ZnO films and Fe-doped ZnO films were deposited using pulsed laser deposition technique.The influences of deposition parameters and Ag/Fe doping concenstrations on the structure, morphologies and optical properties of the films were investigated.The main results are as follows:1.ZnO films with different Ag concentrations were deposited on glass and Si wafers by PLD method.Microstructures and optical properties of the films were investigated.The results show that:when the Ag doping concentration is low,the samples are highly c-axis preferred and the Ag⁺ were substituted into the Zn²⁺ site in the Ag-doped ZnO crystal;when the doping concentration reaches certain value, the sample clusters in the Ag precipitation.2.Effect of the substrate temperature and oxygen pressure on the structures and optical properties of the 2 wt%Ag:ZnO films was studied.With increasing substrate temperature,the crystallization quality of the film was improved,and the optical band gap of the films move closely to that of pure ZnO.However,the ultraviolet fluorescence of the film prepared at 300℃is strongest among all the films.When the oxygen pressure was 10 Pa,the crystalline quality of the films is the best,so is the UV peak.And the band gap of the films is widened first and then narrowed with increasing oxygen pressure.3.Fe-doped ZnO films with different concentions were deposited on glass and Si wafers by PLD method.Microstructures and optical properties of the films were investigated.The results show that:when the Fe doping concentration is low,the samples exhibit highly c-axis preferred structure and Ag⁺ were substituted into the Zn²⁺ site in the Fe-doped ZnO crystal.With increasing Fe content,the crystalline qualitiy of the films decreases and its UV peak reaches maximum at Fe content of 5at%.4.Influence of substrate temperature and oxygen pressure on the structure and optical properties of the 5at%Fe:ZnO films was studied.Among the films prepared at different temperatures,the film at 400℃has the best crystalline quality,the strongest UV peak,and excellent transmittance(＞80%).With increasing oxygen pressure,the quality of the films is enhanced first and then decreased.The film prepared at oxygen pressure of 15 Pa has the best crystalline quality.