Non-resonant, electrode-less method for measuring the microwave complex permittivity of ferroelectric thin films

Abstract

A procedure is described for measuring the complex permittivity of dielectric thin films with relatively large dielectric constants (epsilon: about 10(2)-10(4)) and considerable losses (tan delta: about 10(-3)-1). The ferroelectric films studied here are deposited on a relatively low-E dielectric substrate and placed in the centre of a rectangular waveguide parallel to the direction of wave propagation. The dielectric constants and losses of thin films are determined not by the shift of the resonant peak, but by numerical analysis of measured scattering parameters using a vector network analyser. The proposed method does not require electrode deposition on the film surface, and provides the natural properties of the film without complications due to conductive electrodes and their interfaces.