A first lamination step of forming lower electrode films on both surfaces of a diaphragm and directly forming a first Pb-containing perovskite oxide film which has a larger thermal expansion coefficient than that of the diaphragm and has a columnar structure on a front surface of the lower electrode film; and a second lamination step of directly forming a second Pb-containing perovskite oxide film on a front surface of the lower electrode film are sequentially performed. The second Pb-containing perovskite oxide film is formed under a condition that a difference between a molar ratio R.sub.A1 of Pb to a B-site element in the first Pb-containing perovskite oxide film and a molar ratio R.sub.B1 of Pb to a B-site element in the second Pb-containing perovskite oxide film after the second lamination step is 0.056 or less.

A piezoelectric film of the present invention is a piezoelectric film including a perovskite oxide represented by the following formula (P), in which crystal phases of the perovskite oxide include tetragonal crystals and rhombohedral crystals at a ratio that satisfies the following formula (1).
A.sub.1+?[(Zr.sub.xTi.sub.1?x).sub.1?aNb.sub.a]O.sub.y(P)
0.70?rhombohedral crystals/(rhombohedral crystals+tetragonal crystals)?0.95 (1), where, in the formula (P), A is an A-site element primarily containing Pb, and Zr, Ti, and Nb are B-site elements. x is equal to or higher than 0.4 and lower than 1, excluding x of equal to or higher than 0.51 and equal to or lower than 0.53. a is equal to or higher than 0.08.

A semiconductor device comprising a passive magnetoelectric transducer structure adapted for generating a charge via mechanical stress caused by a magnetic field. The first transducer structure has a first terminal electrically connectable to the control terminal of an electrical switch, and having a second terminal electrically connectable to the first terminal of the electrical switch for providing a control signal for opening/closing the switch. The switch may be a FET. A passive magnetic switch using a magnetoelectric transducer structure. Use of a passive magnetoelectric transducer structure for opening or closing a switch without the need for an external power supply.

A bulk acoustic wave (BAW) resonator includes a substrate having a top side surface and a bottom side surface. A Bragg mirror is on the top side surface of the substrate. A bottom electrode layer is on the Bragg mirror, and a piezoelectric layer is on the bottom electrode layer. A top dielectric layer is on the piezoelectric layer, and a top electrode layer is on the top dielectric layer. The bottom side surface of the substrate has a surface roughness of at least 1 ?m root mean square (RMS).

A piezoelectric element includes a first electrode formed on a substrate, a piezoelectric layer formed on the first electrode and composed of a complex oxide having a perovskite structure containing potassium (K), sodium (Na), niobium (Nb), and manganese (Mn), and a second electrode formed on the piezoelectric layer. The manganese includes divalent manganese (Mn.sup.2+), trivalent manganese (Mn.sup.3+), and tetravalent manganese (Mn.sup.4+), a molar ratio of the divalent manganese to a sum of the trivalent manganese and the tetravalent manganese ((Mn.sup.2+/(Mn.sup.3++Mn.sup.4+)) is 1 or more and 10 or less, and a molar ratio of the potassium to the sodium (K/Na) is 1.1 or less.

A piezoelectric thin film resonator includes: a piezoelectric film located on a substrate; lower and upper electrodes facing each other across a part of the piezoelectric film; and an insertion film located between the lower and upper electrodes, located in a part of an outer peripheral region within a resonance region where the lower and upper electrodes face each other across the piezoelectric film, and not located in a center region of the resonance region, a first width in the resonance region of the insertion film in a first region, where the upper electrode is extracted from the resonance region, being greater than a third width in the resonance region in a third region other than a second region, where the lower electrode is extracted from the resonance region, and the first region, a second width in the resonance region in a second region being the third width or greater.

A piezoelectric element includes a first electrode, a piezoelectric layer which is provided on the first electrode and which is formed of crystals of a composite oxide with a perovskite structure which is preferentially oriented in a plane, and a second electrode which is provided on the piezoelectric layer and which is formed of platinum which is preferentially oriented in a plane, in which, in the piezoelectric layer, plane intervals L.sub.1 of the crystals on the first electrode side are larger than plane intervals L.sub.2 of the crystals on the second electrode side.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

An ultrasonic transducer and a method for a transmitting an acoustic wave using an ultrasonic transducer comprising a membrane; two or more patterned top electrodes; a pMUT array, wherein the patterned top electrode is arranged as row pin selector and column selector in an N?N array; the pMUT array having N+N electrical contacts; a single unpatterned bottom electrode; a row and column where the electrode is at equal or opposite polarities; and a AC driving voltage is applied to top electrodes with a phase difference of zero or is applied to one electrode to transmit the ultrasonic wave.

A transceiver includes an array of pMUT elements, where each pMUT element includes: a substrate; a membrane suspending from the substrate; a bottom electrode disposed on the membrane; a piezoelectric layer disposed on the bottom electrode; and a first electrode disposed on the piezoelectric layer. Each pMUT element exhibits one or more modes of vibration.