Investigation of the microstructural and optical properties of Co doped ErFeO3 thin films synthesized via sol-gel method

Abstract

In this paper, the impacts of chemical doping with Co ions on the microstructural, electronic and optical properties of sol-gel synthesized ErFe_1-xCo_xO₃ thin films, where x = 0.0, 0.05, 0.1 and 0.2, were investigated. The films exhibited high crystalline orthorhombic ErFeO₃ phase and showed gradual reduction of lattice parameters with Co doping. Porous microstructure was observed at x = 0.1 and 0.2. The Co ions existed in a mixed valence of Co⁺² and Co³⁺ ions. The energy band gap (E_g) decreased from 2.79 eV for film x = 0.0–2.59 eV for film x = 0.2. The absorption coefficient reduced with Co doping in the range of 3.8–6.0 eV, however, it increased and red shifted at E < 3.8 eV. Both real refractive index and dielectric constant increased for film x = 0.05 at E > 4 eV and then decreased with further increasing of Co doping.