Abstract: A layered portion includes, at least above an opening, a first single-crystal piezoelectric body layer, a second single-crystal piezoelectric body layer, an intermediate electrode layer, a lower electrode layer, and an upper electrode layer. The first single-crystal piezoelectric body layer includes a material that produces a difference in etching rate between a positive side and a negative side of a polarization charge. The polarization charge of the first single-crystal piezoelectric body layer is negative on a side of the intermediate electrode layer and positive on a side of the lower electrode layer.

Abstract: In a piezoelectric device, when viewed in a direction perpendicular to one main surface, an outer shape of a recess is a polygonal shape or a circular shape. When n represents a number of sides of the polygonal shape, r represents a radius of a circumscribed circle of an imaginary regular polygon including n sides with a length identical to a length of a shortest of the sides, and d represents a maximum thickness of a membrane portion, which is located above the recess, of a multilayer portion, r?197.7 dn?0.6698 when 3?n?7, and r?52.69 d when 8?n or when the outer shape of the recess is a circular shape.

Abstract: In a piezoelectric device, a cantilever portion includes a fixed edge portion and a free edge portion. A plate-shaped portion includes a facing edge portion, a support edge portion, a first lateral support edge portion, and a second lateral support edge portion. The facing edge portion faces the free edge portion. The support edge portion is on an opposite side from the facing edge portion in an extension direction of the cantilever portion. The plate-shaped portion is connected to an inner surface at at least a portion of the support edge portion, at least a portion of the first lateral support edge portion, and at least a portion of the second lateral support edge portion.

Abstract: An acoustic device includes an acoustic MEMS device. An acoustic path communicates with the acoustic MEMS device. Ultrasound generated by vibration of the acoustic MEMS device can resonate in the acoustic path. An ultrasonic transducer has sound pressure frequency characteristics such that sound pressure peaks occur as a result of a combination of resonance of the acoustic MEMS device and resonance in the acoustic path. A relationship of about 5?(f0?fl)/f0×100?about 33 is satisfied, where f0 represents a resonance frequency of the acoustic MEMS device and fl represents a frequency lower than the resonance frequency and closest to the resonance frequency among frequencies at which the sound pressure peaks occur in the sound pressure frequency characteristics.

Abstract: A piezoelectric device includes a membrane portion including a through slot extending through the membrane portion in an up-down direction. A width of the through slot in a single crystal piezoelectric material layer becomes narrower as the through slot extends downward. In the single crystal piezoelectric material layer and a reinforcing layer, a maximum width of the through slot in a layer located on a bottom side is smaller than a minimum width of the through slot in a layer located on a top side.

Abstract: A transducer is provided that includes a base having a cavity, and a vibrating layer disposed on an upper side of the base. The vibrating layer includes a fixed portion fixed to the base, and a membrane that is connected to the fixed portion and extends above the cavity. The vibrating layer includes a lower electrode layer connected to the base, a piezoelectric layer disposed on the lower electrode layer, and an upper electrode layer disposed on an upper side of the piezoelectric layer. In at least a portion of the membrane, the upper and lower electrode layers sandwich the piezoelectric layer. The upper electrode layer or the lower electrode layer includes a fixed electrode portion in the fixed portion, a movable electrode portion in a portion of the membrane, and a connection electrode portion that connects the fixed electrode portion to the movable electrode portion.

Abstract: A piezoelectric device includes a connection section including a first coupling portion, a second coupling portion, and a bridging portion. The first coupling portion extends along a slit and is connected to one of a pair of beam sections. The second coupling portion extends along the slit and is connected to another of the pair of beam sections. The bridging portion is located between the slit and an opening and is connected to both of the first coupling portion and the second coupling portion. The beam sections are connected to each other in a circumferential direction of a base having an annular shape via the connecting section while each of the beam sections is interposed between the slits extending in intersecting directions.

Abstract: A transducer that includes: a base portion; a plurality of beam portions each having a fixed end portion connected to the base portion and a crest portion located close to a center of the base portion on a side thereof opposite to the fixed end portion, the plurality of beam portions each extending from the fixed end portion toward the crest portion; and a connection portion that connects a pair of beam portions of the plurality of beam portions to each other, the pair of beam portions being adjacent to each other in a peripheral direction of the base portion, wherein the connection portion includes: at least one bent portion, and at least one dividing slit in the connection portion, the at least one dividing slit dividing the connection portion such that the connection portion is partially branched and rejoined.

Abstract: A piezoelectric element includes a piezoelectric layer, a first electrode layer, a second electrode layer, and a connecting electrode. The piezoelectric layer includes first and second surfaces, and a through-hole. The second electrode layer is adjacent to the second surface of the piezoelectric layer. The second electrode layer faces the through-hole. The second electrode layer includes silicon as a major component. The connecting electrode is on a connecting surface of the second electrode layer, and the connecting surface faces the through-hole. The connecting electrode is made of a metal. A surface roughness of the connecting surface is greater than a surface roughness of a major surface. The major surface is a portion, other than the connecting surface, of a surface of the second electrode layer, and the surface is adjacent to the piezoelectric layer.

Abstract: A piezoelectric element includes a second electrode layer on a second surface of a single-crystal piezoelectric layer. A hole continuous with a through-hole is provided in the second electrode layer. The second electrode layer is made of Pt, Ti, Al, Cu, Au, Ag, Mg, or an alloy including at least one of the metals as a main ingredient. A third electrode layer is on one side of the second electrode layer opposite to the single-crystal piezoelectric layer. The third electrode layer includes at least a portion outside of an edge of the hole with a distance maintained relative to the edge of the hole when viewed in a direction perpendicular or substantially perpendicular to the second surface. The third electrode layer is made of Ni or an alloy including Ni as a main ingredient.

Abstract: In a piezoelectric device, a layered portion includes, at a position at least above a recess, a single crystal piezoelectric layer and a pair of electrode layers to apply voltage to the single crystal piezoelectric layer. At least a portion of the pair of electrode layers includes a lower electrode layer extending along a surface of the single crystal piezoelectric layer, the surface being closer to a base. The lower electrode layer is present only inside the recess.

Abstract: A piezoelectric device includes a substrate including a first main surface and a second main surface. A piezoelectric element is on the first main surface. A cover on the first main surface. The cover covers the piezoelectric element and is spaced apart from piezoelectric element on the first main surface side. The piezoelectric element includes a base portion and a membrane portion. The base portion is on the first main surface and has an annular external shape when viewed from the first main surface side. The membrane portion is inside the annular base portion when viewed from the first main surface side. The cover includes a first through hole. The substrate includes a second through hole facing the membrane portion and extends between the first main surface and the second main surface.

Abstract: A piezoelectric device includes a beam portion with a fixed end portion and a free end portion opposite to the fixed end portion. The beam portion extends from the fixed end portion towards the free end portion. The beam portion includes a multilayer body including a piezoelectric layer and first and second electrode layers. A base is connected with the fixed end portion of the beam portion. As viewed from a layering direction of the multilayer body, the base surrounds the beam portion at an interval from the beam portion except for the fixed end portion. As viewed from the layering direction, an average of a dimension of a width of the beam portion in an orthogonal or substantially orthogonal direction to an extension direction of the beam portion is greater than a maximal dimension of a length thereof in the extension direction.

Abstract: A piezoelectric device includes an outer base, a protruding base, and only one cantilevered portion. A protruding base includes a protrusion and a tip portion. The protrusion protrudes from an internal circumferential surface of the outer base toward a center of a ring shape. The tip portion is connected to the protrusion and located at the center. The cantilevered portion is connected to the tip portion, and extends while being spaced apart from the protrusion. The cantilevered portion includes a fixed end portion and a free periphery. The fixed end portion is connected to the tip portion. The free periphery is located along the internal circumferential surface. The protrusion is located between a first end and a second end of the free periphery.

Abstract: A piezoelectric device includes a substrate, a piezoelectric element, and a lid. The piezoelectric element includes a base portion and a membrane portion. The base portion is on a first main surface and has an annular outer shape when viewed from a normal direction of the first main surface. The membrane portion is at an inner side portion of the base portion when viewed from the normal direction. The lid is on the first main surface, covers the piezoelectric element, and is spaced apart from the piezoelectric element on the first main surface side. In the substrate, a first through hole extending from the first main surface to a second main surface is facing the membrane portion. The membrane portion includes a through slit.

Abstract: A piezoelectric device includes a base portion and an upper layer on an upper side of and supported by the base portion. The upper layer includes a membrane portion that does not overlap with the base portion in plan view. The membrane portion includes at least one piezoelectric layer sandwiched by electrode layers from a top and a bottom thereof. An intermediate layer is between a lower electrode and the base portion. The intermediate layer includes one or more individual layers, and an individual layer exposed as a lower surface of the membrane portion among the one or more individual layers includes a bent portion, which extends from the lower surface of the membrane portion to a lateral wall, on a boundary between a portion defining and functioning as the lower surface of the membrane portion and a portion overlapping with the base portion.

Abstract: A transducer includes a first connection portion connecting a first tip and a second tip to each other. The first connection portion is surrounded by a split slit connecting a center of the first tip, a center of a base, and a center of the second tip, the first tip, and the second tip.

Abstract: A device may include a first substrate provided with a first through hole. A device may include a second substrate arranged adjacent to the first through hole and configured to partially overlap with the first substrate on a second side of the first substrate. A device may include a vibration layer arranged adjacent to and overlap with the first substrate on a first side of the first substrate opposite the second substrate and configured to stride across the first through hole. A device may include a resin layer disposed to overlap with a portion of the vibration layer overlapping with the first substrate. A device may include a first pad electrode. A device may include a second pad electrode. A device may include the first pad electrode and the second pad electrode being disposed on a surface of the resin layer opposite from the vibration layer.

Abstract: A MEMS device is provided that includes a piezoelectric element including a piezoelectric membrane including a ferroelectric and configured to vibrate based on an application of a voltage. A device may include a diode portion electrically connected in parallel to the piezoelectric element and including a diode.

Abstract: A piezoelectric device includes a membrane portion including a single-crystal piezoelectric layer, an upper electrode layer, and a lower electrode layer. The upper electrode layer is on a first surface. The lower electrode layer is on a second surface facing at least a portion of the upper electrode layer sandwiching the single-crystal piezoelectric layer. The single-crystal piezoelectric layer includes piezoelectric body cleavage directions extending along a boundary line between a cleavage plane occurring when the single-crystal piezoelectric layer is cleaved and the first surface. When viewed in a vertical direction, at least a portion of an upper electrode outer edge and at least a portion of a lower electrode outer edge are non-parallel to at least one of the piezoelectric body cleavage directions.