Preparation of indium tin oxide (ITO) thin film with (400) preferred orientation by sol–gel spin coating method

Tin doped indium oxide (ITO) thin films with (400) preferred orientation were fabricated by sol–gel spin coating method with metal indium and SnCl ₄ ·5H ₂ O as indium and tin precursors, oxalic acid was used for synthesis of ITO sol as a stabilizer and methylcellulose as a binder. This study creatively combines thermal treatment at different temperatures with post-annealing treatment at 500 °C to prepare ITO thin films with enhanced conductivity and highly transmittance. It was found that the (400) preferred orientation growth strongly depends on thermal treatment temperature. Growth preferred orientation of the ITO thin films changed from (222) plane to (400) plane with the increase of thermal treatment temperature. The ITO thin film was thermal treated at 250 °C shows highly (400) preferred orientation, which exhibited an excellent conductivity (a low sheet resistance of 230 Ω Sq ⁻¹ and a low resistivity of 4.14 × 10 ⁻³  Ω cm) combining with a highly average transmittance of 85.12% and obtained the best figure of merit (8.68 × 10 ⁻⁴  Ω ⁻¹ ).