Microstructural, dielectric and ferroelectric properties of calcium-modified lead titanate thin films derived by chemical processes

Ferroelectric Pb1−xCaxTiO3 (x=0.24) thin films were formed on a Pt/Ti/SiO2/Si substrate by the polymeric precursor method using the dip-coating technique for their deposition. Characterization of the films by X-ray diffraction showed a perovskite single phase with a tetragonal structure after annealing at 700°C. Atomic force microscopy (AFM) analyses showed that the film had a smooth and crack-free surface with low surface roughness. In addition, the PCT thin film had a granular structure with an 80 nm grain size. The thickness of the films observed by the scanning electron microscopy (SEM) is 550 nm and there is a good adhesion between the film and substrate. For the electrical measurements metal-ferroelectric-metal of the type capacitors were obtained, where the thin films showed good dielectric and ferroelectric properties. The dielectric constant and dissipation factor at 1 kHz and measured at room temperature were found to be 457 and 0.03, respectively. The remanent polarization and coercive field for the deposited films were Pr=17 μC/cm2 and Ec=75 kV/cm, respectively. Moreover, the 550-nm-thick film showed a current density in the order of 10−8 A/cm2 at the applied voltage of 2 V. The high values of the thin filmʹs dielectric properties are attributed to its excellent microstructural quality and the chemical homogeneity obtained by the polymeric precursor method.