An ultrasonic transducer device includes a base, a first electrode film, a piezoelectric film, a second electrode film and a first conductive film. The base has a plurality of vibrating film portions arranged in an array pattern. The first electrode film is disposed on each of the vibrating film portions. The piezoelectric film is disposed on the first electrode film. The second electrode film is disposed on the piezoelectric film. The first conductive film is connected to the first electrode film. The first conductive film has a film thickness larger than a film thickness of the first electrode film.

An acoustic resonator structure comprises a first electrode disposed on a substrate, a piezoelectric layer disposed on the first electrode and comprising aluminum scandium nitride, a second electrode disposed on the piezoelectric layer, and a temperature compensation feature having a temperature coefficient offsetting at least a portion of a temperature coefficient of the piezoelectric layer, the first electrode, and the second electrode.

There is provided a piezoelectric element which includes a first electrode, a piezoelectric layer which is formed on the first electrode by using a solution method, and is formed from a compound oxide having a perovskite structure in which potassium, sodium, and niobium are provided, and a second electrode which is provided on the piezoelectric layer. A cross-sectional SEM image of the piezoelectric layer is captured at a magnification of 100,000. When evaluation is performed under a condition in which a measured value in a transverse direction is set to 1,273 nm, two or more voids are included in the piezoelectric layer, a difference between the maximum value and the minimum value among diameters of the voids to be largest in a film thickness direction is equal to or smaller than 14 nm, and the maximum value is equal to or smaller than 24 nm.

A piezoelectric thin film having better FoM and piezoelectric strain constant, a manufacturing apparatus and manufacturing method, and a fatigue estimation system using the film; wherein, the piezoelectric thin film is made of (MgHf).sub.xAl.sub.1-xN in which Mg and Hf are co-doped into the Al site of AlN, where x is 0.3 or more and 0.49 or less, and has a figure of merit (FoM) of 45 GPa or more and a piezoelectric strain constant (d.sub.33) of 18 pm/V or more. Multiple first pieces made of Mg and multiple second pieces made of Hf are on the surface of a target made of AlN wherein an average surface area of each first piece is 0.9 to 1.1 times an average surface area of each second piece with respect to a surface area of the target, and a piezoelectric thin film is grown on a substrate by magnetron sputtering.

Acoustic filters are disclosed. A filter device includes a plurality of resonators connected in a ladder filter circuit, each resonator of the plurality of resonators comprising an interdigital transducer (IDT) with interleaved fingers disposed on a respective piezoelectric diaphragm. A first frequency setting dielectric layer having a first thickness is disposed over the interleaved fingers of one or more IDTs of a first subset of the plurality of resonators. A second frequency setting dielectric layer having a second thickness greater than the first thickness is disposed over the interleaved fingers of one or more IDTs of a second subset of the plurality of resonators, wherein the first subset and the second subset are not identical.

In a piezoelectric element and an actuator, the piezoelectric element includes a substrate; and a first electrode, a first piezoelectric film, a second electrode, a second piezoelectric film, and a third electrode provided on the substrate in this order, in which the first piezoelectric film and the second piezoelectric film each have a perovskite-type oxide as a main component, and one of the first piezoelectric film and the second piezoelectric film is an epitaxial film and the other is a uniaxial alignment film.

An electronic device may include a first electrode, a first piezoelectric layer electrically coupled to the first electrode, a first magnetostrictive layer above the first piezoelectric layer, a first tunnel barrier layer above the first magnetostrictive layer, and a ferromagnetic layer above the first ferroelectric layer. The electronic device may further include a second electrode electrically coupled to the ferromagnetic layer a second tunnel barrier layer above the ferromagnetic layer, a second magnetostrictive layer above the second tunnel barrier layer, a second piezoelectric layer above the second magnetostrictive layer, and a third electrode electrically coupled to the second piezoelectric layer. The first piezoelectric layer may be strained responsive to voltage applied across the first and second electrodes, and the second piezoelectric layer may be strained responsive to voltage applied across the second and third electrodes.

A piezoelectric element comprising a first electrode, a second electrode, and a lead zirconate titanate film located between the first electrode and the second electrode. The piezoelectric element is formed on a Si substrate whose principal surface is (001) plane. The Si substrate has uniform crystalline orientation in an in-plane direction and an out-of-plane direction. (110) plane of the Si substrate and (100) plane of the lead zirconate titanate film are parallel. In a rocking curve measurement of an X-ray diffraction method, symmetric surface reflection peak of the lead zirconate titanate film obtained by X-rays incident from [100] direction of the Si substrate can be fitted with three component peaks.

A method for forming and a film stack for a piezoelectric device includes a first seed layer of aluminum nitride, aluminum oxide, or silicon nitride formed on a substrate, an intermediate film layer formed on the first seed layer at a temperature of approximately 300 degrees Celsius to approximately 400 degrees Celsius where the intermediate film layer includes a first layer of a first material and a second layer of a second material that is different from the first material, a second seed layer of aluminum nitride, aluminum oxide, or silicon nitride formed on the intermediate film layer, and an active film layer with a full width half maximum (FWHM) of 1.2 degrees or less formed on the second seed layer.

A complex oxide includes a chemical compound represented by ABO.sub.3 (Chemical Formula 1). In the Chemical Formula 1, A is one or more elements selected from Ba, Ca, and Sr; and B is one or more elements selected from Ti, Zr, Hf, and Sn. When a field having a size of 1 m1 m on a surface of the complex oxide is observed with an atomic force microscope (AFM), a typical particle size is greater than or equal to 300 nm and less than 660 nm. Here, the typical particle size is a maximum length of a maximum particle observed in the field.