INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 14, No. 8, pp. 1465-1469 AUGUST 2013 / 1465 © KSPE and Springer 2013 Electrical and Optical Properties of Indium-tin Oxide (ITO) Films by Ion-Assisted Deposition (IAD) at Room Temperature Mansour S. Farhan 1 , Erfan Zalnezhad 2 , Abdul Razak Bushroa 2,# , and Ahmed Aly Diaa Sarhan 2 1 College of Engineering, Wasit University, Iraq 2 Center of Advanced Manufacturing and Material Processing, Department of Engineering Design and Manufacture, Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia # Corresponding Author / E-mail: bushroa@um.edu.my, TEL: +60-7967-4593, FAX: +60-7967-5330 KEYWORDS: IAD, ITO thin films, Electrical properties, Optical properties Indium-tin oxide (ITO) films have been traditionally deposited at elevated substrate temperature of 400 o C to achieve low resistivity and high transmission. In some cases, films deposited at low substrate temperatures can be annealed at higher temperature to achieve lower resistivity. In this paper, thin films of ITO with various oxygen flow rates are prepared by ion-assisted electron beam evaporation at room temperature. Electrical, optical and structural properties of ITO thin films have been investigated with the function of oxygen flow rate, rate of deposition and layer thickness. Low resistivity of 7.5 × 10-4Ω-cm, high optical transmittance of 85% at wavelength 550 nm, optical band-gap of 4.2 eV and crystalline ITO films can be achieved at room temperature almost one order smaller than that prepared by other method. Manuscript received: March 25, 2013 / Accepted: May 26, 2013 1. Introduction A distinctive class of transparent oxide films comprises electrically conducting. While most oxides are fine insulators, some are wide band- gap semiconductors. Indium tin oxide (ITO) thin films are widely utilized in numerous industrial applications due to the unique combined properties of transparency to visible light and electrical conductivity. 1 Coatings on glass with highly transparent conductive oxide films (TCO) are mostly performed with indium tin oxide layers (ITO). This oxide material is very common in applications where both high electrical conductivity and optical transmittance are essential. ITO films are reactively sputtered with single magnetron sputter sources of different sizes. The aim of ITO process technology development is to obtain stable film properties for large-area coatings with exceptionally low resistivity and high transmittance within the visible spectrum range. ITO films may be prepared in several ways including reactive evaporation 8-10 or sputtering, DC magnetron reactive 10,11 or RF sputtering, 12-14 as well as Ultralow-Pressure Sputtering 15 and sol-gel. 16 All of these processes involve a reactive oxygen background. The oxygen level during the procedure is a critical component of controlling film quality. ITO films are highly degenerate n-type semiconductors, and have low electrical resistivity (10 -4 Ω-cm) along with high carrier concentration. Furthermore, ITOs have a wide band-gap (Eg > 4.1 eV) and high transmittance (> 85%) in the visible range. 2 This unique combination of electrical and optical properties has prompted numerous researchers to thoroughly investigate ITO film growth and characterization. ITO finds potential applications in a number of devices, such as flat panel displays, solar cells, gas sensors, camera lenses, anti-reflection coatings, heat reflection mirrors and surface heaters for automobile windows. 3 In the last 22 years, considerable data has been reported on ion sources 4 utilized for both substrates pre- cleaning and to assist with thin film deposition and growth processes. 6,7 Currently a plethora of ion sources are available for commercial use besides countless improvements of older designs. Ion-assisted deposition (IAD) modifies many of the physical characteristics of thin films. Since visible transmission and electrical conductivity are fundamentally in conflict with each other, ITO seems one of the better film materials available for such applications. However, as an oxygen- deficient material it behaves like metal, becoming conductive, optically absorbing and highly reflective in the infrared region. DOI: 10.1007/s12541-013-0197-5