Study On Preparation And Properties Of ITO Films By The Hydrothermal Method

ITO thin films on glass substrates have been prepared by hydrothermal treating a mixed solution of the indium tin chloride and ammonia. The element, morphology, thickness and refractive index, electrical resistance and transmittance of the prepared ITO films were studied by EDS, SEM, elliptical polarized, four-probe method and UV-VIS spectrometer. The crystal phase, grain size of the powders synthesized in the same system as the film's were studied by XRD, DTA techniques. The thickness and refractive index ofhydrothermal method derived ITO thin films as functions of [InCl₃, SnCl₄]precursor concentration and ammonia concentration, hydrothermal temperature, soak time and hydrothermal treating times were studied in details; and the influence of precursor concentration, ammonia concentration and temperature and soak time on grain size were discussed as well. The as-obtained thin films are 196.3～201.3nm in thickness and 2.45～2.51 in refractive index in the hydrothermal condition of [InCl₃, SnCl₄]=0.3～0.7 mol/l, [ammonia]=3～5mol/l and 140～180℃for 4～8 hours. The films are body-centered cubic polycrystalline, homogenous, dense and crack-free. It is proved that high concentration of precursor, long hydrothermal time and appropriate treating times are of advantage to the increase of films thickness. The prepared ITO films are body-centered cubic polycrystalline, 23～44nm, and high precursor concentration, high ammonia concentration, high temperature and long soak time are of advantage to ITO crystal growth. Magnetron sputtering method to prepare the ITO thin films usually has the oxygen environment. This paper by magnetron sputtering method using indium oxide target(In₂O₃:SnO₂=90:10, wt%), highly transparent and conductive ITO films could be successfully deposited on glass substrate at room temperature. The effect of pAr on the film structure and properties was discussed in detail. The films deposited at lower pAr had more excellent body-centered cubic polycrystalline and more excellent electrical properties. And at pAr = 0.3 Pa, the maximal transmittance of ITO film was 92.9% for the visible light spectrum, and its conductance was 8.9×10^-4Ω·cm.The sol-gel method usually uses the organic alkoxide for the precursor, dissolves in the organic solvent, therefore the cost is high. ITO thin films on glass substrates have been prepared by sol-gel method treating a mixed solution of the price inexpensive inorganic salt and ammonia, carried on the performance contrast in this experiment.