Measurement and modelisation of dielectric properties of ferroelectrics thin layers

In this study, the real and imaginary parts of the complex permittivity of PZT ferroelectric thin films are studied in the frequency range of 100 Hz - 100 MHz. The permittivity is well fitted by the Cole-Cole model. The variation of the relaxation time with temperature is described by the Arrhenius law and an activation energy of 0.38 eV is found. Due to its nonlinear character, the dielectric response of the ferroelectric sample depends on the amplitude of the applied ac electric field. The permittivity is composed of three different contributions: the first is due to intrinsic lattice, the second to domain wall vibrations and the third to domain wall jumps between pinning centers. The last one depends on the electric field so it is important to control the field amplitude to obtain the desired values of permittivity and tunability.