Broadband Characterization of Multilayer Dielectric Thin-Films

We developed a measurement technique for obtaining the broadband complex permittivity of thin-film dielectric materials over the frequency range from 100 Hz -40 GHz. Such broad frequency coverage can only be accomplished by combining lumped-element and distributed devices, and is implemented in this technique using planar capacitors and transmission lines. We experimentally determined the capacitance and conductance per unit length for these different structures fabricated on the same thin-film samples, and, through the use of detailed finite-element simulations, extract consistent values for the relative permittivity. We demonstrate the utility of this technique by applying it to study the frequency dependence of the dielectric response of ferroelectric, ferromagnetic, and multi-ferroic thin-film samples.