Effects of oxygen ion beam plasma conditions on the properties of Indium tin oxide thin films

Tin-doped indium oxide (ITO) films were depositied at room temperature by ion beam-assisted evaporation and the effects of oxygen ion beam conditions on the properties of room-temperature ITO thin films were investigated. It is well known that high conductivity of ITO is caused by intrinsic defect(oxygen vacancy) and dopant(tin). One of the techniques to obtain highly conductive ITO film at room temperature is to cause electron degeneracy in the band gap by introducing non-stoichiometry in the ITO film using oxygen ion beam plasma while evaporating ITO films using an electron beam evaporation. In this study, flux and energy of oxygen ion beam plasma were varied to modify depositing ITO thin films by controlling gas flow rates and grid bias potential. The structure of deposited ITO thin film was amorphous for all of the experimental conditions. The increase of oxygen ion beam flux increased the optical transmittance of the deposited ITO film, however, at a given ITO evaporation rate, the resistivity showed a minimum in a certain range of ion beam flux. The increase of oxygen ion beam energy up to 900 V decreased the resistivity and increased the optical transmittance of deposited ITO thin films. Using the oxygen ion beam-assisted method, ITO thin films with the resistivity of 5.2 x 10(-4) Omega cm and optical transmittance of above 90% could be deposited at room temperature. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.