Abstract: A thin-film piezoelectric resonator includes a substrate, and first and second excitation portions. The substrate includes first and second cavities. The first excitation portion is disposed over the first cavity, and includes a first electrode, a first piezoelectric material and a second electrode laminated successively. An overlapping region among the first electrode, the first piezoelectric material and the second electrode defines a contour of a periphery of the first excitation portion. A first distance is defined as a distance from an end of the first excitation portion to an opening end of the first cavity. The second excitation portion is disposed over the second cavity, and includes a third electrode, a second piezoelectric material and a fourth electrode laminated successively. A second distance is defined as a distance from an end of the second excitation portion to an opening end of the second cavity and different from the first distance.

Abstract: A film bulk acoustic-wave resonator encompasses a substrate having a cavity; a bottom electrode partially fixed to the substrate, part of the bottom electrode is mechanically suspended above the cavity; a piezoelectric layer provided on the bottom electrode; and a top electrode provided on the piezoelectric layer having crystal axes oriented along a thickness direction of the piezoelectric layer, a full width at half maximum of the distribution of the orientations of the crystal axes is smaller than or equal to about six degrees.

Abstract: A film bulk acoustic-wave resonator encompasses (a) a substrate having a cavity, (b) a bottom electrode partially fixed to the substrate, part of the bottom electrode is mechanically suspended above the cavity, (c) a piezoelectric layer disposed on the bottom electrode, a planar shape of the piezoelectric layer is defined by a contour, which covers an entire surface of the bottom electrode in a plan view, (d) a top electrode on the piezoelectric layer, (e) an intermediate electrode located between the substrate and the piezoelectric layer, and at the contour of the piezoelectric layer, the intermediate electrode is connected to the bottom electrode in the inside of the contour, and (f) a bottom electrode wiring connected to the intermediate electrode extending from the contour to an outside of the contour in the plan view, wherein a longitudinal vibration mode along a thickness direction of the piezoelectric layer is utilized.

Abstract: A piezoelectric thin film device includes an amorphous metal film disposed on a substrate and a piezoelectric film disposed on the amorphous metal. One of crystal axis of the piezoelectric film is aligned in a direction perpendicular to a surface of the amorphous metal.

Abstract: A voltage controlled oscillator includes a resonator configured to resonate with an initial oscillation frequency during starting period of oscillation and a steady oscillation frequency during a steady state oscillation. The resonator includes a film bulk acoustic resonator having a series resonance frequency higher than the steady oscillation frequency. A negative resistance circuit configured to drive the resonator, has a positive increment for reactance in the steady state oscillation compared with reactance in the starting period.

Abstract: A piezoelectric thin film resonator which comprises a first electrode, a second electrode, and a piezoelectric film which is interposed between the first electrode and the second electrode, and formed of an epitaxial ferroelectric thin film containing barium titanate, a spontaneous polarization of the epitaxial ferroelectric thin film being uniaxially orientated in a direction normal to a film surface.

Abstract: A piezoelectric thin film resonator which comprises a first electrode, a second electrode, and a piezoelectric film which is interposed between the first electrode and the second electrode, and formed of an epitaxial ferroelectric thin film containing barium titanate, a spontaneous polarization of the epitaxial ferroelectric thin film being uniaxially orientated in a direction normal to a film surface.

Abstract: A method of manufacturing an epitaxially-strained lattice film of an oxide, in which epitaxially-strained lattices having a good crystalline property are formed by applying RF power to a substrate holder and irradiating positive ions having a moderate energy while preventing damage to the strained lattice film to be stacked by oxygen negative ions. This method simultaneously overcomes both the problem of damage to the film by irradiation of oxygen negative ions, which is peculiar to sputtering of oxides, and the problem of failure to strain due to relaxation of the strain during deposition.

Abstract: A method of manufacturing an epitaxially-strained lattice film of an oxide, in which epitaxially-strained lattices having a good crystalline property are formed by applying RF power to a substrate holder and irradiating positive ions having a moderate energy while preventing damage to the strained lattice film to be stacked by oxygen negative ions. This method simultaneously overcomes both the problem of damage to the film by irradiation of oxygen negative ions, which is peculiar to sputtering of oxides, and the problem of failure to strain due to relaxation of the strain during deposition.