A piezoelectric actuator includes an electrode layer including a trunk portion and a plurality of branch portions branched from the trunk portion. The trunk portion includes a plurality of junction points from each of which a corresponding branch portion of the plurality of branch portions are branched, an end spaced from the plurality of junction points, and a second through hole positioned between the plurality of junction points and the end of the trunk portion. A plurality of first through holes are grouped into a first group and a second group. The first group overlaps, in a first direction, a particular area defined between the end of the trunk portion and the second through hole and the second group overlaps, in the first direction, another particular area defined between the second through hole and the plurality of junction points.

Fingerprint identification modules, methods for forming the fingerprint identification modules and electronic devices are provided. The method may include providing a substrate, containing a signal process circuit formed therein; providing a carrier substrate; forming one or more piezoelectric transducers on the carrier substrate, wherein a piezoelectric transducer of the one or more piezoelectric transducers includes a first electrode, a piezoelectric layer on the first electrode and a second electrode on the piezoelectric layer; forming a permanent bonding layer, containing one or more cavities, on one of the carrier substrate and the substrate; bonding the carrier substrate with the substrate using the permanent bonding layer, wherein the permanent bonding layer is between the one or more piezoelectric transducers and the substrate, and each piezoelectric transducer covers one cavity; and removing the carrier substrate.

A sensor for obtaining downhole data includes a first piezoelectric layer. The sensor also includes a second piezoelectric layer having a trench extending a depth below a surface of the second piezoelectric layer. The sensor also includes an electrode positioned within the trench. The first piezoelectric layer is directly coupled to the second piezoelectric layer.

An ultrasonic fingerprint recognition sensor and a manufacturing method thereof, and a display device are disclosed. The ultrasonic fingerprint recognition sensor includes a resonant cavity, a receiver electrode, a drive electrode, and a piezoelectric thin film layer between the receiver electrode and the drive electrode, the resonant cavity is on a side, closer to the piezoelectric thin film layer, of the receiver electrode, and is configured to increase vibration amplitude of the piezoelectric thin film layer.

An electromechanical device comprising: first and second electrodes each comprising a metal layer; an active layer comprising at least one ferroelectric polymer and disposed between the first and the second electrode. The first electrode and the second electrode each comprise an interface layer comprising poly(3,4-ethylenedioxythiophene). Each interface layer is interposed between the active layer and the corresponding metal layer. The invention further relates to a method for manufacturing such a device.

A semiconductor structure is provided. The semiconductor structure includes a substrate, a first piezoelectric layer, and a first dummy layer. The first piezoelectric layer is over the substrate, and the first piezoelectric layer has a first top surface. The first dummy layer is over the first piezoelectric layer, and the first dummy layer has a second top surface. And an average roughness of the first top surface is greater than an average roughness of the second top surface. A method for manufacturing the semiconductor structure is also provided.

A plurality of conductive via connections are fabricated on a substrate located at positions where MTJ devices are to be fabricated, wherein a width of each of the conductive via connections is smaller than or equivalent to a width of the MTJ devices. The conductive via connections are surrounded with a dielectric layer having a height sufficient to ensure that at the end of a main MTJ etch, an etch front remains in the dielectric layer surrounding the conductive via connections. Thereafter, a MTJ film stack is deposited on the plurality of conductive via connections surrounded by the dielectric layer. The MTJ film stack is etched using an ion beam etch process (IBE), etching through the MTJ film stack and into the dielectric layer surrounding the conductive via connections to form the MTJ devices wherein by etching into the dielectric layer, re-deposition on sidewalls of the MTJ devices is insulating.

In a non-limiting embodiment, a device may include a substrate, and a hybrid active structure disposed over the substrate. The hybrid active structure may include an anchor region and a free region. The hybrid active structure may be connected to the substrate at least at the anchor region. The anchor region may include at least a segment of a piezoelectric stack portion. The piezoelectric stack portion may include a first electrode layer, a piezoelectric layer over the first electrode layer, and a second electrode layer over the piezoelectric layer. The free region may include at least a segment of a mechanical portion. The piezoelectric stack portion may overlap the mechanical portion at edges of the piezoelectric stack portion.

In a piezoelectric device, electrode layers are spaced apart from each other in the direction of the normal thereto. A first piezoelectric layer is interposed between two electrode layers of electrode layers in the direction of the normal. A second piezoelectric layer is provided on an opposite side of the first piezoelectric layer from a base portion. The second piezoelectric layer is interposed between two electrode layers of the electrode layers in the direction of the normal. The half-width of a rocking curve measured by X-ray diffraction for a lattice plane of the first piezoelectric layer substantially parallel to a first main surface is smaller than a half-width for the second piezoelectric layer. The piezoelectric constant of a material defining the first piezoelectric layer is smaller than the piezoelectric constant of a material defining the second piezoelectric layer.

An acoustic wave device includes a piezoelectric substrate made of LiNbO.sub.3 or LiTaO.sub.3 and including first and second main surfaces that face each other, a functional electrode provided on the first main surface of the piezoelectric substrate to excite acoustic waves, and a Li.sub.2CO.sub.3 layer provided on the second main surface of the piezoelectric substrate.