ITO thin films were prepared by electron beam evaporation of ceramic ITO target. The films were subsequently annealed in air atmosphere at the temperatures 300°C and 600°C in order to improve their optical and electrical properties. The crystal structure and morphology of the films are investigated by X-ray diffraction and scanning electron microscope techniques, respectively. The films exhibited cubic structure with predominant orientation of growth along (222) direction, and the crystallite size increases by rising annealing temperature. Transparency of the films, over the visible light region, is increased by annealing temperature. The resulting increase in the carrier concentration and in the carrier mobility decreases the resistivity of the films due to annealing. The absorption coefficient of the films is calculated and analyzed. The direct allowed optical band gap for as-deposited films is determined as 3.81？eV; this value is increased to 3.88 and 4.0？eV as a result of annealing at 300°C and 600°C, respectively. The electrical sheet resistance is significantly decreased by increasing annealing temperature, whereas figure of merit is increased. 1. Introduction Conducting oxide thin films are being an important component in different optoelectronic devices such as solar cells [1], light emitting diodes [2], photodiodes [3], and electrochromic devices [4] in which they are used as transparent electrodes. The resistivity of these electrodes should be minimized as much as possible with keeping its high optical transparency particularly over the visible region of the solar spectrum. Indium tin oxide (ITO) thin films are being the most used material, the interest of which has been trusted by fundamental advantages over the competing materials. ITO thin films have been manufactured by using a variety of methods including direct current and radiofrequency sputtering [5, 6], reactive evaporation [7], pulsed laser ablation [8], electron beam evaporation [9], spray pyrolysis [10], and sol-gel techniques [11]. Studies on ITO films, grown by the above-mentioned deposition techniques, revealed that the electro-optical properties of such films are highly sensitive towards the method of preparation, composition, partial pressure of oxygen, substrate temperature, substrate type, and annealing processes. The microstructure of the films could be changed with the change of annealing temperature and hence could affect the optical and electron transport properties. Furthermore, the identification of intrinsic changes to ITO characteristics is crucial because these
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