Consequence of source material on the surface properties of nebulizer spray coated cerium oxide thin films

Abstract

Cerium oxide thin films are coated on glass substrates by nebulizing spray pyrolysis technique using cerium nitrate and cerium chloride as a source material. Their crystallographic structures, surface morphology, optical properties and I–V characteristics are analyzed as a function of substrate temperature (300–500 °C). XRD is used to estimate the crystallographic texture, crystalline size, strain and lattice constant. All films exhibit a cubic fluorite structure with different preferred orientation depending on the preparation conditions. All the films exhibit dense, smooth and crack-free spherical nanostructures with some uneven surfaces in the range 400 nm. PL analysis indicates the presence of indigo and blue emission in the visible region centered at ∼425 and ∼467 nm respectively. UV-ViS spectra revealed that the films are transparent (70%) in the visible region. Optical parameters like refractive index, optical conductivity and band gap are calculated for different Ts. XPS analysis revealed the existence of Ce, O and C in the films. It demonstrates the prevalent occurrence of Ce4+ rather than Ce3+. I–V characteristics confirm the semiconducting behavior of cerium oxide thin films due to its linear response to applied voltage.