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A thin dielectric resonator consisting of a dielectric substrate and the thin film deposited upon it is shown to suffice for microwave characterization and dielectric parameter measurement of high-permittivity thin films without electrodes. The TE01δ resonance mode was excited and measured in thin (down to 0.1 mm) rectangular- or disk-shaped low-loss dielectric substrates (D∼10 mm) with permittivity ε′≥10 inserted into a cylindrical shielding cavity or rectangular waveguide. The in-plane dielectric permittivity and losses of alumina, DyScO3, SmScO3, and (LaAlO3)0.29(SrAl1/2Ta1/2O3)0.71 (LSAT) substrates were measured from 10 to 18 GHz. The substrate thickness optimal for characterization of the overlying thin film was determined as a function of the substrate permittivity. The high sensitivity and efficiency of the method, i.e., of a thin dielectric resonator to the dielectric parameters of an overlying film, was demonstrated by characterizing ultrathin strained EuTiO3 films. A 22 nm thick EuTiO3 film grown on a (100) LSAT substrate and strained in biaxial compression by 0.9% exhibited an increase in microwave permittivity at low temperatures consistent with it being an incipient ferroelectric; no strain-induced ferroelectric phase transition was seen. In contrast, a 100 nm thick EuTiO3 film grown on a (110) DyScO3 substrate and strained in biaxial tension by 1% showed two peaks as a function of temperature in microwave permittivity and loss. These peaks correspond to a strain-induced ferroelectric phase transition near 250 K and to domain wall motion.

Microwave methods for thin ferroelectric film parameter investigations are classified, discussed and improved. Being non-electrode and in some cases non-contact these methods are non-destructive and the information about parameters of films can be obtained from a distance and even during the technological process. High-resistivity silicon or semi-insulated gallium arsenide wafer adds little to microwave absorption or reflection. On the contrary, the crucial factor for the latter is the ferroelectric film with its microwave dielectric dispersion. It is assumed that some of microwave methods would be used in various stages of ferroelectric-semiconductor device characterisation.

Functional possibilities of lJHF and microwave devices based on dielectric resonators (DRs) could be essentially extended if the basic resonant frequency of attenuation-frequency characteristic (AFC) could be fast controlled. It was shown that each DR by itself allows to control its resonantpequency up to 10 -30% with a high Q-factor preservation [ 11. However, the commonly accepted constructions of DR-filters are unsuitable for such controlling owing to the unwanted change in their AFC. Proposed in this Report new design of DR-systems provides AFC shifting in frequency while the shape of AFC being undistorted due to independence of own modes of DRs employed. Based on this concepts, various band-pass and band-rejection overturned DR-based filters were realized. Some new results were obtained as toJilter AFC controlling.

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