The use of nitrogen as background gas to assist pulsed-laser deposition in the fabrication of indium tin oxide (ITO) films at room temperature produces both highly conductive and transparent films (similar to8 X 10(-4) Omega cm and similar to85% of transmittance), comparable to those obtained by using oxygen (similar to4 X 10(-4) Omega cm and similar to90% of transmittance). Hall-effect electrical measurements, Rutherford backscattering spectrometry, X-ray diffraction and optical transmission on these films are reported. For the films with best conducting and transparent properties, atomic nitrogen is 5% of the atomic oxygen content in the films. The amount of nitrogen correlates to the amount of electron-carrier concentration in the films, which suggests that incorporation of nitrogen from the background gas plays an important role in the creation of oxygen vacancies-the main conduction mechanism in high-quality ITO films grown over substrates at room temperature. (C) 2003 Elsevier Science B.V. All rights reserved.