Effects of Doping Ratio and Thickness of Indium Tin Oxide Thin Films Prepared by Magnetron Sputtering at Room Temperature

Transparent conducting films on polymeric substrates are increasingly applied in diverse novel displays and flexible electronics. In this paper, indium tin oxide films on polymeric substrates were deposited by magnetron sputtering using ceramic targets with different doping ratios. These films were characterized by X-ray photoelectron spectroscopy, X-ray diffractometer, atomic force microscopy, spectroscopic ellipsometry, spectrophotometer, sheet resistance meter, and the Hall effect measurement. In terms of transparency and conductivity, the results have shown that the doping ratio played a less important role in determining the optical properties, while the electrical properties were significantly influenced. It was found that, when the thickness was less than 130 nm, these films with the nominal doping ratio of 95:5 (wt. %) demonstrated higher electrical conductivity compared to those with 90:10 (wt. %), which were widely used in industry. Therefore, for the flexible polymeric substrate, the target with a doping ratio of 95:5 (wt. %) could be suitable to achieve high electrical conductivity.