Transparent Conductive Oxide Films Prepared By Sol-Gel Method

The transparent conductive oxide films have excellent electrical and optical properties, they are widely applied to liquid crystal display, transparent electrode, anti-static coat, solar cell and other micro-electronics devices. At present, the kinds of films were prepared by means of sputtering. But the films prepared by this method can't meet the development of photoelectricity technology, for example the conductive substrates of the large area display device and the anti-static coats of the display device. So the sol-gel technology has gained more and more attention. In this paper, transparent conductive oxide films, including Sb. F, P doped tin oxide films and Sn-doped indium oxide films, were prepared respectively by sol-gel method from inorganic salts. At the same time the preparing process, the electrical and optical properties and the crystal structure have been investigated. The results show that:(1) The steady and usable sols can be prepared by sol-gel method from inorganic salts. Among the numerous preparing schemes, the optimal mol ratio of SnCln-lF^O, HiO and ethanol is 1:4:20~40 in the tin oxide film. And the preparing scheme of indium oxide films is that the mol ratio of ln(NO)3-4.5H20. AcAc and ethanol is 1:3:20-40.(2) During the preparing tin oxide films, SbCl3, H2SiF6 and (C2H5)3PO4 are chosen to dope tin oxide films. And the films have excellent properties. Minimum sheet resistance will be given to these films doped with 8mol%Sb, 5mol%F and l~3mol%P respectively.(3) Comparing with the tin oxide films, the indium oxide films have better electrical properties. And the films doped with about 10~12mol%Sn have minimum sheetThis research was supported by Nature Science Foundation of Shaanxi (2001 COS).resistance value.(4) The tin oxide films doped with different dopants have different properties. The Sb-doped Sn02 films have the lowest sheet resistance. P-doped SnO2 films have the highest transmission and the conductivity of F-doped SnCK films is between SnO2:Sb films and SnC>2:P films, the optical transmission of the SnC>2:F films is the lowest. According to needs, the different dopants can be selected.(5) The heat-treatment process influents the films properties greatly. The lowest sheet resistance value are recorded for SnO:Sb. SnO;:F. SnO2:P and ITO films heat-treated at 400 , 380; 380 and 480癈 in air. The value is about 460: 2800n? 5490 and 339 . respectively. The thicknesses of the films are about 0.3um. And these films heat-treated in N2 or in vacuum have lower sheet resistance, at the same time the transmittance of the films reduces to about 80%.(6) The X-ray diffraction patterns show that Sn02:Sb. SnO2:F. SnO-:P films are all rutile structure, their lattice constant is: a=4.738A. c=3.19lA. and the films crystal grain diameters are 40.5nm. But ITO films retain the cubic In2O3 structure. Their lattice constant is: a=1.0143A. the grains of the films are about 86nm.