Studying room temperature RF magnetron-sputtered indium tin oxide (ITO) thin films for large scale applications

Indium Tin Oxide (ITO) thin films are well known transparent conductive layers used for a range of areas and applications such as touchscreen technology. In general, heat treatment at > 200°C is essential to optimize film properties including crystallinity, transmission, and conductivity. However, such treatment restricts the development of such films on temperature sensitive substrates. In this work, we have developed industrial scale Indium Tin Oxide (ITO) thin films on 4 inches Silicon (Si) substrate at room temperature using radio frequency magnetron sputtering to eradicate the requirement of process or post-process heat treatment. As studied, ITO films grown at lower deposition pressure (2 mTorr) with lower radio frequency (RF) power (200 W) show the best result in terms of electrical properties with topological properties. Such controlled growth of the films eventually leads to the development of industrial scale transparent conductive layers. The electrical, topological, structural, and morphological characteristics of the films were assessed through various techniques including Hall effect measurement, atomic force microscopy (AFM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM). The morphological data validates the development of compact, uniform, and defect-free TCO films grown at lower RF power, as verified by TEM technique. AFM measurements confirm the roughness of films is below 1 nm at lower for the deposition pressure of 2 mTorr with lower RF power of 200 W. The better conductivity of the films grown at lower deposition power without any heat treatment has been observed. These findings confirm a favorable growth procedure to develop such metal oxide films on temperature tolerant substrates, opening possibilities to develop flexible optoelectronics. • ITO thin films have been successfully sputtered at room temperature. • All films exhibited preferential polycrystalline (222) primary peaks. • TEM analysis showed polycrystallinity at lower RF power and pressure. • n-type with a mobility of 30.41 cm 2 /V and a resistivity lower than 3.29 × 10 −4 Ω cm. • Suitable for usage in energy applications, without additional adjustments.