Indium tin oxide (ITO) thin films were deposited on polyethylene terephthalate substrates using a DC facing target sputtering (DC-FTS) system at room temperature. The sputtering conditions including oxygen partial pressure and discharge current were varied from 0% to 4% and 0.5 A to 1.3 A, respectively. X-ray diffraction and scanning electron microscopy were used to study the structure and surface morphology of as-prepared films. All the films exhibited amorphous structures and smooth surfaces. The dependence of electrical and optical properties on various deposition parameters was investigated by a linear array four-point probe, Hall-effect measurements, and ultraviolet/visible spectrophotometry. A lowest sheet resistance of 17.4 Omega/square, a lowest resistivity of 3.61 x 10(-4) Omega cm, and an average relative transmittance over 88% in the visible range were obtained under the optimal deposition conditions. The relationship between the Hall mobility (mu) and carrier concentration (n) was interpreted by a functional relation of mu similar to n(-0.127), which indicated that ionized donor scattering was the dominant electron scattering mechanism. It is also confirmed that the carrier concentration in ITO films prepared by the DC-FTS system is mainly controlled by the number of activated Sn donors rather than oxygen vacancies. (C) 2014 Elsevier B. V. All rights reserved.