Characteristics of amorphous Yb-doped ITO films deposited on polyimide substrate by DC magnetron sputtering

The ITO and Yb-doped ITO (ITO:Yb) films were deposited on polyimide (PI) substrates by DC magnetron sputtering using ITO targets (doped-Yb: 0, 0.57, 3.2 and 7.75 at.%) containing different Yb ratios. Film deposition and post-annealing were carried out at room temperature and different temperatures (170 °C and 200 °C), respectively, in a pure Ar gas atmosphere at 1.0 Pa for 1 h. The ITO:Yb films had a higher crystallization temperature than that of the ITO films, which was attributed to Yb3+ atoms degrading the crystallinity of the ITO film. The ITO:Yb films also had good mechanical properties and a very flat surface morphology above the crystallization temperature of the ITO films (approximately 170 °C). The lowest resistivity of the polycrystalline ITO films obtained was 2.983 × 10− 4 Ω cm at 200 °C. On the other hand, the amorphous ITO:Yb films deposited from the 3.2 at.% Yb-doped ITO target at 170 °C had the lowest resistivity of 4.672 × 10− 4 Ω cm. The transmittance of all the ITO:Yb films was > 80% in the visible region.