Preparation of ITO thin films by sol-gel method

Abstract

ITO thin films were prepared at 550 °C by a sol-gel method using colloidal particles derived from a solution of indium nitrate and tin chloride. The colloidal particles were secondary particles with about 50 nm in diameters and were dispersed by adding indium chloride as a peptizer to prepare a dipping solution. Firing of gel films at 550 °C for 2 min developed a film microstructure consisting of ITO particles through thermal decomposition of the colloidal particles. Indium chloride was also decomposed to form indium oxide by firing, and the oxide was found to crosslink the ITO particles in the film. ITO films with thickness up to 2 μm were obtained by a single dipping-firing procedure. The sheet resistivity of the films prepared at 550 °C for 30 min was 500 ω/cm2 and the optical transmittance was above 90% in the visible region.