Electrical transport properties and complex impedance investigation of Fe3+ and La3+ co-doping (Pb,Sr)TiO3 thin films

Highlights: • The influence of Fe³⁺ and La³⁺ incorporation on properties of PST has been analyzed carefully. • The electrical transport properties have been investigated. • The impedance spectroscopy shows dielectric relaxation phenomenon. • Increase in conduction to be directly related to a decrease in the Schottky barrier height. - Abstract: This work investigates the impact of Fe³⁺ and La³⁺ co-doping on the structural, electrical transport and dielectric relaxation properties of PST thin films. XRD and Raman spectroscopy data show that the Fe³⁺ and La³⁺ doping induce a pseudocubic to tetragonal structural phase transformation. Schottky barrier heights calculated from temperature-dependent current–voltage plots for the PST, PSTF and PSLTF films decreased to 1.20, 0.59, and 0.36 eV, respectively. This behavior was directly assigned to the increase in oxygen vacancies. The frequency dependence of sample's impedance revealed the presence of the typical electrical relaxation phenomenon in all films. Activation energies calculated from the imaginary part of the impedance are 1.73 and 0.57 eV: the high value (1.73 eV, PST films) suggests the presence of long-range oxygen vacancy diffusion, while the lower one (0.57 eV PSLTF films) should be associated to the short-range oxygen vacancy diffusion.