Microwave characterization of (Pb,La)TiO₃ thin films integrated on ZrO₂/SiO₂/Si wafers by sol-gel techniques

Abstract

Polycrystalline perovskite lead lanthanum titanate (PLT) thin films were prepared by a sol-gel method on ZrO₂/SiO₂/Si substrates. The structure of the films was studied by x-ray diffraction and scanning electron microscopy, and the microwave dielectric properties characterized on a network analyzer. A strong dependence of the dielectric constant of PLT films and, correspondingly, the resonance frequency of PLT-based interdigital capacitor on the sample preparation conditions were observed. They resulted from the structural transformation of PLT from a layered structure to a uniform film as the annealing temperature was raised from 550 to 700 °C, suggesting a possible way to modify the device performance by controlling the layered structure of the ferroelectric film.