Microwave losses in metal-ferroelectric-metal thin-film capacitors

The design and technology of microwave ferroelectric capacitors based on Pt/(Ba,Sr)TiO 3 /Cu thin-film structures are considered. The structural and electrical characteristics of a ferroelectric layer deposited over a Pt film are presented. The frequency dependence of microwave losses in a 1–30 GHz range have been measured for a capacitor ensuring approximately two-fold variation of the capacitance in a bias voltage range of ∼30 V. On the basis of an equivalent scheme, the metal-related contribution to total losses in the capacitor is determined and it is concluded that this contribution is predominating in the millimeter wavelength range.