Effect of ITO target crystallinity on the properties of sputtering deposited ITO films

Abstract

The crystallinity of Indium tin oxide (ITO) targets has crucial effect on the photoelectric properties of ITO films, which has only rarely been reported. In this study, ITO targets with different crystallinities were used to prepare ITO thin films (approximately 150 nm) under similar conditions using radio frequency (RF) magnetron sputtering. The crystal structure and element state of ITO targets and ITO thin films were analyzed by X-ray diffraction (XRD) and X-ray photoelectron (XPS), respectively. Moreover, the electrical and optical properties of sputtering ITO thin films were systematically characterized by a four-probe meter and ultraviolet–visible (UV-VIS) spectrophotometer. It was found that the strength ratios for (222) and (400) peaks of ITO thin films were affected by the crystallinities of ITO targets. When the ITO film was prepared using target A, which had the best crystallinity, its strength ratio of (222) and (400) peaks (I222/I400) was close to 1, resistivity reached the lowest value of 1.75 × 10−4 Ω cm, and the average transmittance and optical band gap of the films were 90.7% and 3.67 eV, respectively. To obtain a high-quality ITO film, it is important to prepare an ITO target that exhibits enhanced crystallization, and that provides a good understanding of the sintering behavior of ITO target.