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The Effects of RF Sputtering Power and Gas Pressure on Structural and Electrical Properties of ITiO Thin Film

DOI: 10.1155/2012/651587

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Transparent conductive titanium-doped indium oxide (ITiO) films were deposited on corning glass substrates by RF magnetron sputtering method. The effects of RF sputtering power and Ar gas pressure on the structural and electrical properties of the films were investigated experimentally, using a 2.5?wt% TiO2-doped In2O3 target. The deposition rate was in the range of around ?nm/min under the experimental conditions of ?mTorr of gas pressure and ?W of RF power. The lowest volume resistivity of -cm and the average optical transmittance of 75% were obtained for the ITiO film, prepared at RF power of 300?W and Ar gas pressure of 15?mTorr. This volume resistivity of -cm is low enough as a transparent conducting layer in various electrooptical devices, and it is comparable with that of ITO or ZnO:Al conducting layer. 1. Introduction In the last decade transparent conducting thin films have attracted much attention due to their wide range of applications in electrooptical devices. High-quality transparent conducting films are characterized by a high transmittance in the optical range from 400 to 800?nm and by an electrical resistivity as low as possible. Moreover, the increases in use of transparent electrodes for many optical devices such as solar cell, PDP, and heat mirrors, so forth, have accelerated the development of inexpensive transparent materials. Indiumtinoxide (ITO) and aluminum-doped zinc oxide (ZnO:Al) thin films have been widely used as a transparent conducting electrode of various electrooptical devices. F-doped tinoxide (FTO) has been also well used, especially in a dye-sensitized solar cell (DSC). However, the FTO/ITO films, which are prepared by the chemical vapor deposition (CVD) method, are costly and complicated for mass production. The FTO/ITO films have also limitations in their infrared ray (IR) transmission and thermal resistance as a transparent conductor. Titanium-doped indiumoxide (ITiO) has also emerged as a transparent conducting oxide (TCO) because it has a low sheet resistance, aside from its high mobility and near-IR transmittance. The properties of ITiO layer show that the long-wavelength falloff in transmittance does not occur until 1500?nm compared to about 1000?nm for an 8??/sq sheet resistivity [1]. Usually, DSCs are still responsive in the 1000–1100?nm range. Thus, they benefit from the improved TCO layer transmission in this near-IR wavelength range [2]. Therefore, the electrical and optical properties of ITiO thin film should be studied in order to investigate the possible application of the film as a transparent

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