Negative Magnetoresistance of Indium Tin Oxide Nanoparticle Thin Films Grown by Chemical Thermolysis

To clarify the electrical transport properties of nanostructured thin films, tin-doped indium oxide (ITO) nanoparticle (NP) solution-processed films were fabricated. An air-atmosphere, simple chemical thermolysis method was used to grow the ITO NPs, and the structural and electrical properties of spin-coated granular ITO NP films were investigated. X-ray diffraction measurements showed clear observation of the cubic indium oxide (222) diffraction peak, and films with a smaller Sn concentration were shown to have a better crystalline quality. We further explored the physical origin of the sign of the magnetoresistance (MR) in the variable-range hopping (VRH) region. A negative MR under a magnetic field perpendicular to the film surface increases with decreasing Sn concentration, and these results can be explained by the forward interference model in the VRH region. A larger negative MR is attributed to longer localization and hopping lengths, and better crystallinity. Thus, ITO NP thin films produced by this method are attractive candidates for oxide-based diluted magnetic semiconductors and other electronic devices.