Microstructural, Electrical, Optical and Magnetic Properties of Fe- and Cu-Doped In1.95Cr0.05O3Thin Films Synthesised by Sol-Gel Method

In2O3 is multifunctional material with rich physical phenomena. In this paper, effects of Fe and Cu doping on the physical properties of In1.95-xCr0.05MxO3 (M = Fe, Cu) thin films prepared by sol-gel method followed by spin-coating technique were investigated. The films were characterised using X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectrophotometer, Hall effect, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer. Doping with Cu reduced the lattice parameter and optical transmittance of In1.95-xCr0.05MxO3 films more than that with Fe. In addition, Cu doping induced p-type conductivity in In1.95-xCr0.05MxO3 films. Optical band gap was increased from 3.76 eV for In1.95Cr0.05O3 to similar to 3.8 eV for both Cu- and Fe-doped films, which was attributed to quantum confinement behaviour. Average grain size measured using TEM was reduced from 8.2 nm for In1.95Cr0.05O3 to 6.6 and 5.6 nm for Fe and Cu doped films, respectively. Saturation magnetisation of films was reduced with Fe doping more than that with Cu doping. Magnetic behaviours of films were explained within the framework of bound magnetic polaron model.