Electron scattering mechanisms in indium-tin-oxide thin films: grain boundary and ionized impurity scattering

Abstract

Carrier concentrations and mobilities of indium-tin-oxide (ITO) thin films by DC magnetron sputtering at the various process temperatures were measured using the Hall Technique. The relationship between the carrier concentrations and mobilities had two distinct regions: (i) roughly up to the process temperatures of 300degreesC with carrier concentrations of 9.0 x 10(20)/cm(3), both carrier concentrations and mobilities increased together with the process temperatures; (ii) above the process temperature of 300degreesC with carrier concentrations over 9.0 x 10(20)/cm(3), the carrier mobilities decreased as the carrier concentrations increased with the process temperatures. These distinct relationship between carrier concentrations and mobilities were due to the transition of the dominant electron scattering mechanisms in ITO thin films with the process temperatures. At low process temperatures, the crystallinities were low and the grain boundary scattering was dominant. However, at high process temperatures, ITO thin films were highly crystallized and the ionized impurity scattering was dominant. The overall characterizations related to the carrier concentrations and mobilities were also performed using an X-ray diffractometer and a scanning electron microscope. (C) 2004 Elsevier Ltd. All rights reserved.