Effects of second-phase particles and elemental distributions of ITO targets on the properties of deposited ITO films

As the key material of transparent electrodes in various optoelectronic devices, ITO targets with uniform microstructure and homogeneous elemental distributions are vital to obtain high-quality ITO films in industrial production. In this paper, the differences in the crystalline structure, sheet resistance and transmittance of ITO films with 40 nm, 70 nm and 100 nm thickness were studied between two ITO targets that were respectively sintered at 1580 °C for 10 h (target A) and 1600 °C for 5 h (target B). Surface morphology, surface roughness and thickness uniformity of ITO films with 100 nm thickness and etching property of ITO films with 40 nm and 70 nm thickness in mixed acids were further focused in the paper. The results indicate that target A, which owns homogeneous distributions of second-phase particles and elements, could be conductive to obtain the ITO films with low crystallinity that are easy to be etched leaving less and smaller residual particles. Based on the analysis, the change of sintering process has a great influence on the electrical and etching properties, but it has only a little influence on the optical property.