Effects of annealing temperature and heat-treatment duration on electrical properties of sol-gel derived indium-tin-oxide thin films

Transparent indium tin oxide (ITO) thin films have been deposited by the dip-coating process on silica substrates using solutions of 2,4-pentanedione, ethanol, indium and tin salts. The films have been first dried in air at 260 °C for 10 min and then annealed in a reducing atmosphere at different temperatures for various durations. The resistivity of ITO layers was found to decrease with increasing the metal concentration of the starting solution or the annealing temperature. Hence, by adjusting both metal concentration in the coating solution and heat-treatment, resistivities lower than 5 × 10^− 3 Ω cm for an annealing temperature of 550 °C and lower than 2 × 10^− 2 Ω cm for an annealing temperature of 300 °C, were obtained. These results are correlated with the density and the size of ITO grains in the films.