A piezoelectric element includes a plurality of vibration regions that are separated from each other by a slit, and the slit is formed to have a tapered portion that is tapered from a first surface of the vibration regions on an opposite side to a support to a second surface opposite to the first surface. An electrode film is positioned inside than the slit when being viewed from a normal direction orthogonal to the first surface, and an angle formed by a side surface of the tapered portion in the vibration region and a surface parallel to the first surface is in a range of 39 to 81 degrees.

A bonded body has a piezoelectric material substrate 11, a support substrate 13 bonded to the piezoelectric material substrate, and an outer peripheral processed part in which outer peripheral parts of the piezoelectric material substrate 11 and the support substrate 13 are inclined with respect to a main surface of the piezoelectric material substrate 11. The outer peripheral processed part includes a first inclined surface that is a surface that the piezoelectric material substrate 11 faces, and a second inclined surface that is on a plane extending from the first inclined surface toward the outer peripheral part and that is a surface that the support substrate 13 faces. Consequently, a bonded body in which no corners are formed on the outer peripheral part and fracture and cracks are less likely to occur in the outer peripheral part in subsequent steps, and a method for producing a bonded body are provided.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. Patterned electrodes are deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the electrodes and a planarized support layer is deposited over the sacrificial layer. The device can include temperature compensation layers (TCL) that improve the device TCF. These layers can be thin layers of oxide type materials and can be configured between the top electrode and the piezoelectric layer, between the bottom electrode and the piezoelectric layer, between two or more piezoelectric layers, and any combination thereof. In an example, the TCLs can be configured from thick passivation layers overlying the top electrode and/or underlying the bottom electrode.

An acoustic wave transmitting structure and a display device are provided. The acoustic wave transmitting structure includes a first layer, a second layer, and an intermediate layer. The first layer has a first acoustic impedance Z1. The second layer has a second acoustic impedance Z2. The intermediate layer is disposed between the first layer and the second layer, and has a third acoustic impedance Z3. Z1, Z2, and Z3 satisfy a relation: (Z1+Z2)/6.8Z3(Z1+Z2)/0.6. The display device includes a display panel and an acoustic wave generator. The display panel has a substrate. A plurality of display elements are disposed on one side of the substrate. The acoustic wave generator is disposed on the other side of the substrate of the display panel through the acoustic wave transmitting structure. The other side of the substrate is opposite to the one side of the substrate.

A semiconductor substrate with oxide single crystal heterostructures, to which a sacrificial layer, an epitaxy functional oxide thin film having a perovskite structure and a metal layer are grown on an oxide single crystal substrate, prepared another metal layer on a semiconductor substrate, and bonded the metal layer of the oxide single crystal substrate to the metal layer of the semiconductor substrate to be face each other, and separated the oxide single crystal substrate by selectively etching and removing only the sacrificial layer after the bonding.

A piezoelectric valve is a piezoelectric valve driven by a DC component, and includes a plurality of piezoelectric elements electrically connected in parallel via electrodes made of a metal-plated film; a conductive diaphragm joined to the plurality of piezoelectric elements via the electrodes; and a resistor electrically connected to the plurality of piezoelectric elements, and an electric resistance value of the resistor is less than an insulation resistance value of each of the piezoelectric elements.