Frequency dependence of the dielectric properties of La-doped Pb(Zr0.35Ti0.65)O3 thin films

Abstract

Frequency dependence of the dielectric properties of La-doped lead zirconate titanate thin films with Pt and Ir electrodes and two different La doping levels is studied by impedance spectrometry between 10−3 and 104 Hz. A constant phase element with an impedance of Z=A0(jω)−α is introduced into the equivalent circuit, which fits very well both the real and imaginary components of the measured impedance over the full frequency range, including the resonance, using a single α (0≪α<1). Our analysis shows that α is not related to the ferroelectric properties of the films, but it has a monotonic correlation with the real dielectric constant. The close resemblance to the well-known butterfly-shaped C–V curve shown by α with the applied dc bias (α-V) suggests that α may be affected by the density of the domain walls in the film, in addition to various dielectric relaxation processes.