Nanograins dependent dielectric constant, tunability, phase transition, impedance spectroscopy and leakage current of (Pb1 − xSrx)TiO3 thin films

Nanostructured (Pb1 − xSrx)TiO3 (PST) (x = 0.1, 0.2 and 0.3) thin films have been prepared by chemical solution deposition process using spin coating technique. The solution as such was deposited on Pt/Ti/SiO2/Si substrates and annealed at 650 °C/3h. Nanograins dependent dielectric properties of PST films show dielectric constant up to the higher frequency region, low losses, large tunability and phase transition at small temperature. The impedance data has been fitted by Cole–Cole model to study the effect of grain boundaries on the dielectric properties. The current–voltage characteristics have been measured to study leakage current in PST films and described by Poole–Frenkel emission model. It is suggested that the key carrier transport process in PST films is emission of electrons from a trap state near the metal–film interface into a continuum of states associated with each conductive dislocation. The activation energy value for carrier transport in PST films is obtained from temperature-dependent current–voltage characteristics.