A substrate for a surface acoustic wave device or bulk acoustic wave device, comprising a support substrate and an piezoelectric layer on the support substrate, wherein the support substrate comprises a semiconductor layer on a stiffening substrate having a coefficient of thermal expansion that is closer to the coefficient of thermal expansion of the material of the piezoelectric layer than that of silicon, the semiconductor layer being arranged between the piezoelectric layer and the stiffening substrate.

A composite substrate includes a final substrate, and a piezoelectric material directly molecularly bonded to the final substrate at a first interface. The piezoelectric material comprises an epitaxial layer, but does not comprise a seed layer. Additional composite substrates include a final substrate, and a piezoelectric material directly molecularly bonded to the final substrate at a first interface. The piezoelectric material comprises an epitaxial layer. The composite substrate further includes a seed layer on which the piezoelectric material has been epitaxially grown. The seed layer is disposed on a side of the epitaxial layer opposite the final substrate. An acoustic wave device comprises such a composite substrate with at least one electrode on a surface of the piezoelectric layer opposite the substrate.

A composite substrate includes a final substrate, and a piezoelectric material directly molecularly bonded to the final substrate at a first interface. The piezoelectric material comprises an epitaxial layer, but does not comprise a seed layer. Additional composite substrates include a final substrate, and a piezoelectric material directly molecularly bonded to the final substrate at a first interface. The piezoelectric material comprises an epitaxial layer. The composite substrate further includes a seed layer on which the piezoelectric material has been epitaxially grown. The seed layer is disposed on a side of the epitaxial layer opposite the final substrate. An acoustic wave device comprises such a composite substrate with at least one electrode on a surface of the piezoelectric layer opposite the substrate.

An ultrasonic sensor includes a vibration plate that includes a vibration portion and is formed of a resin; a wall portion that is provided on the vibration plate, surrounds the vibration portion and is formed of a resin; and a piezoelectric element that is provided in the vibration portion of the vibration plate. Accordingly, the wall portion surrounding the vibration portion can suppress a frequency variation of an ultrasonic wave output from the ultrasonic sensor and can deform the ultrasonic sensor into a shape corresponding to a surface of an object having various shapes.

A diaphragm for a piezoelectric micromachined ultrasonic transducer (PMUT) is presented having resonance frequency and bandwidth characteristics which are decoupled from one another into independent variables. Portions of at least the piezoelectric material layer and backside electrode layer are removed in a selected pattern to form structures, such as ribs, in the diaphragm which retains stiffness while reducing overall mass. The patterned structure can be formed by additive, or subtractive, fabrication processes.

A method for manufacturing a monocrystalline piezoelectric material layer includes providing a donor substrate made of the piezoelectric material, providing a receiving substrate, transferring a so-called “seed layer” of the donor substrate onto the receiving substrate, and using epitaxy of the piezoelectric material on the seed layer until the desired thickness for the monocrystalline piezoelectric layer is obtained.

A method for separating a removable composite structure using a light flux includes supplying the removable composite structure, which successively comprises: a substrate that is transparent to the light flux; an optically absorbent layer for at least partially absorbing a light flux; a sacrificial layer adapted to dissociate subject to the application of a temperature higher than a dissociation temperature and made of a material different from that of the optically absorbent layer; and at least one layer to be separated. The method further includes applying a light flux through the substrate, the light flux being at least partly absorbed by the optically absorbent layer, so as to heat the optically absorbent layer; heating the sacrificial layer by thermal conduction from the optically absorbent layer, up to a temperature that is greater than or equal to the dissociation temperature; and dissociating the sacrificial layer under the effect of the heating.

A polymeric piezoelectric material, comprising at least two regions: a region H, which is an oriented polymeric piezoelectric region that includes an optically active helical chiral polymer (A) having a weight average molecular weight of from 50,000 to 1,000,000, the region H having a crystallinity of from 20% to 80% and having a standardized molecular orientation-of from 3.5 to 15.0; and a region L, which is a low orientation region that includes the optically active helical chiral polymer (A) having a weight average molecular weight of from 50,000 to 1,000,000, the region L being present near at least part of an end portion of the region H, having an average width when viewed from a normal direction with respect to the principal plane of the region H of from 10 μm to 300 μm, and having a retardation is 100 nm or less.

The present disclosure of at least one embodiment provides a method for manufacturing ultrasound probes comprising a machining process, the method including depoling a piezoelectric element as a material for the ultrasonic probes before the machining process.

In manufacturing method of a cylindrical piezoelectric element, a cylindrical piezoelectric material is formed by molding a piezoelectric material into a cylindrical shape and subjecting the molded piezoelectric material to calcination. A reference electrode is provided on an inner circumferential surface of the cylindrical piezoelectric material. Drive electrodes are provided in a circumferential direction so that the drive electrodes are extending in an axial direction from one end to the other end on an outer circumferential surface. A polarization electrode is provided at a part of the circumferential surface in the vicinity of the one end. A predetermined voltage is applied between the polarization electrode and the reference electrode. The polarization electrode is removed from the cylindrical piezoelectric material.