Influence of Stoichiometric Ratio and Mn-Doping on the Surface Morphology and Dielectric Properties of Perovskite (La,Sr)FeO3 Films

Lanthanum strontium ferrite (La1−x Sr x FeO3, x = 0.1, 0.3, 0.5, 0.7) (LSF) films were prepared on platinized/silica/silicon (Pt/SiO2/Si) substrates by a sol–gel method. The crystallization, surface morphology and dielectric properties of the LSF films have been studied. Among the samples, La0.5Sr0.5FeO3 thin film have the most homogeneous, smooth surface and the best dielectric properties (e r = 2881.58, tanδ = 1.20) at the frequency of 1 kHz. Mn-doping (y) in La0.5Sr0.5FeO3 further improves the dielectric properties (e r = 2922.91, tanδ = 1.11) of the film. Both e r and tanδ values of the Mn-doped (y = 0.02) La0.5Sr0.5FeO3 films decreases with increasing the frequency. The biggest e r value is 3238.18 at the frequence of 0.02 kHz.