Ferroelectric thin‐film characterization using a coplanar waveguide bandstop filter

Abstract

Abstract A new structure for the characterization of the permittivity of ferroelectric thin films at microwave frequencies is proposed. This new structure involves a coplanar waveguide (CPW) bandstop filter based on a ferroelectric thin film. Using the resonant frequency and Q value of the CPW bandstop filter, the dielectric constant ( ε r ) and the loss tangent (tan δ ) of the ferroelectric thin film were determined by comparing the measured responses with simulated results. To demonstrate this new structure, a CPW bandstop filter was fabricated on MgO substrate coated with Ba 0.5 Sr 0.5 TiO 3 (BST‐0.5). The dielectric parameters determined as a function of temperature and external bias are reported. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)