Optical and electrical characterization of Ni-doped orthoferrites thin films prepared by sol-gel process

This paper presents a low-temperature route for producing RFe0.6Ni0.4O3 (where R = Pr, Nd and Sm) thin films by an aqueous inorganic sol-gel process. The films produced were characterized by X-ray diffraction (XRD) for structural, four probes for electrical and UV-vis spectroscopy for optical properties. As-deposited films were amorphous and after annealing them at 650 °C, crystallinity appears and shows an orthorhombic structure. From UV-vis spectroscopy, variation in optical band gap and transmission is seen with change of rare-earth ions. From electrical resistivity measurement, semiconducting behavior is observed. The difference in activation energy is observed. This variation could be due to the orthorhombic distortion caused by size of rare-earth ion and which may impact the Fe-O-Fe or Fe-O-Ni or Ni-O-Ni bond angle, and hence affects the single particle band width in the present system.