| In this experiment ,Indium tin oxide (ITO)film which is highly conductive and transparent to visible light has been prepared by sol-gel dip-coating technique and In(NO3) was chose as raw material, acetylacetone as solvent, SnCl4 was chose as dopant. The structure properties and the physical properties (electrical resistance and transmittance) of the film were investigated by XRD, SEM , IR four-probe method and UV-VIS spectrometer. The process that the film was transformed from amorphous state to the polycrystalline structure has been determined by the DTA-TG technique. In addition, The influence of different technological conditions (dipping times and speed, annealing temperature, cooling speed and matrix materials) on the film properties have been investigated in detail .The experimental results is discussed and the experimental conditions i s optimized.The experimental results indicate the possibility to prepare ITO conductive and transparent film by the sol -gel dipping method .ITO film have the polycrystalline cubic bixbyite In2O3 structure, but the result that no XRD pattern of Sn compound (SnO or SnO2) has been determined shows the fact that a solution of Sn in In2O3 was formed .the transformation from the amorphous state to the polycrystalline state was finished completely at 600℃.The thickness after 5 times dip coating is less than 150nm,the desirable connection with matrix can be determined .Meanwhile ,few macro defects such as holes can be observed .The micro structure of this film is the porous structure which is accumulated by many spherical particles .the micro structure of film ,including the size and distribution of second phase, is obviously changed by different annealing techniques .The minimum of sheet resistance is about 110 Ω□,the minimum specific resistance of can reach 1.65 X 10-2 Ω·cm. When the wavelength of visible light rang from 400nm to l000nm, the 90% maximum of transmittance can be reached.,The experimental results indicates: At the beginning, the sheet resistance of ITO film decreased with the increase of [ In.] But it increased when the certain point of [In] has been surpassed. Superfluous [In] may contribute the process of hydrolysis and reduce the transmittance of the film .The maximum of the sheet resistance can be reached.The doping speed has little influence on the conductivity of film and the sheet resistance decreased with the increase of annealing temperature, and the minimum ofresistance of ITO film can be abtained when the rapid cooling process is conducted .In the experiment. The different properties of matrix have obvious influence on the sheet resistance of ITO film .But such influence may decrease with the increase of coating layers.With the increase of coating times and the thickness of film ,its transmittance reduced because of the increase of the absorption to visible light .When ITO film remains amorphous state ,It has the maximum of transmittance .the transformation from the amorphous state to the polycrystalline may lead to the decrease of transmittance ,but with the increase of annealing temperature ,the transmittance of the film may increase slowly. Doped [Sn] show little influence on the transmittance of ITO film. And it can be found that the increase of [Sn] may lead the slight decline of transmittance of film. After the process of rapid cooling, ITO film shows the relative low transmittance ,but such phenomenon is not very obvious when the annealing temperature is relative high or low, the decrease of transmittance is due to the fact that the different cooling speeds changed the grain size and the rough state of ITO film. |
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