Indium–tin oxide coatings via chemical solution deposition

Thin films of indium-tin oxide (ITO) were formed on glass substrate via a chemical solution deposition method. Indium nitrate coordinated with 2,4-pentanedione and ethylene glycol, and tin oxalate were used as the raw materials of the coating solution. Composition ratios of Sn/In were varied between 0 and 14 mol%. The solutions were coated on non-alkali glass substrate using a spin-coating process. Then, the coated glass was fired in air to thermally decompose the precursors and to densify the coating. The resistivity of the coatings fired in air at 300°C was 5.0 Ω cm and decreased at higher firing temperatures. The resistivity of the coatings fired at 700°C was 2.8 × 10 -3 Ω cm, which is more than 10 times higher than that of ITO coatings formed by the sputtering process. A post-annealing in non-oxidizing atmospheres such as vacuum, N 2 , Ar and H 2 /Ar after the firing lowered the resistivity of the coating. Treatment in hydrogen-containing atmosphere was particularly effective in lowering the resistivity of the coating to 6.2 × 10 -4 Ω cm. It was found that the decomposition of organic residues and formation of oxygen vacancies in the coatings were promoted by the hydrogen treatment.