Structural and optical study of samarium doped cerium oxide thin films prepared by electron beam evaporation

Research highlights: → Triangular shaped grain growth. → Samarium doping in CeO2 promotes vacancy formation. → Reduction in band gap with samarium doping. → Sm doped CeO2 films: Good candidate for fuel cell application. - Abstract: Samarium doped cerium oxide films were grown on the glass substrate using e-beam deposition technique and then characterized using different techniques: X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and UV-visible spectroscopy measurements. XRD analysis shows that all the films have cubic structure and the crystallite size decreases from 18 to 13 nm as the samarium (Sm) concentration increases. The FE-SEM images indicate that all the films have columnar growth. UV-visible measurements reflect that the films have high transparency (>80%) in the visible region. From the Raman spectra, we have observed two peaks at 466 and 565 cm-1. The peak at 466 cm-1 is assigned to the F2g mode of cerium oxide (CeO2) whereas the peak at 565 cm-1 is due to the presence of the oxygen vacancies. The increase in the intensity of the peak at 565 cm-1 indicates that the oxygen vacancy increases with Sm doping.