An acoustic wave device includes a silicon substrate, a piezoelectric layer, and an IDT electrode. Each of the silicon substrate and the piezoelectric layer includes first and second opposed main surfaces. The IDT electrode is on the first main surface of the piezoelectric layer, and includes first and second electrode fingers. When a wavelength of an acoustic wave determined by an electrode finger pitch of the IDT electrode is denoted as λ, a distance between the first main surface of the silicon substrate and the second main surface of the piezoelectric layer in a thickness direction of the silicon substrate is less than about 0.84λ. The first main surface of the silicon substrate is rougher than the first main surface of the piezoelectric layer.

Embodiments of a Surface Acoustic Wave (SAW) device having a guided SAW structure that provides spurious mode suppression and methods of fabrication thereof are disclosed. In some embodiments, a SAW device includes a non-semiconductor support substrate, a piezoelectric layer on a surface of the non-semiconductor support substrate, and at least one interdigitated transducer on a surface of the piezoelectric layer opposite the non-semiconductor support substrate. A thickness of the piezoelectric layer, a SAW velocity of the piezoelectric layer, and an acoustic velocity of the non-semiconductor support substrate are such that a frequency of spurious modes above a resonance frequency of the SAW device is above a bulk wave cut-off frequency of the SAW device. In this manner, the spurious modes above the resonance frequency of the SAW device are suppressed.

The present disclosure provides an acoustic resonator device, among other things. One example of the disclosed acoustic resonator device includes a substrate having a carrier layer, a first layer disposed over the carrier layer, and a piezoelectric layer disposed over the first layer. The acoustic resonator device is also disclosed to include an interdigitated metal disposed over the piezoelectric layer, where the interdigitated metal is configured to generate acoustic waves within an acoustically active region. The acoustic resonator device is further disclosed to include an acoustic wave scattering structure.

An adaptive RF acoustic resonator contains tunable and switchable hybrid surface-bulk acoustic waves (SAW-BAW). The surface and bulk acoustic waves couple for the spectral sensing and configurable filtering. The acoustic resonator includes a piezoelectric or ferroelectric layer, such as a SLAIN layer, which is patterned into interdigital transducers, and an intermediate layer of AlGaN—GaN, which is built on a SiC substrate. The device is protected under a plastic packaging cap. An external tuning voltage applies on the acoustic resonator to generate the tunable frequency and bandwidth of the bulk and surface acoustic waves. An RF switch generates an electric field to suppress a residual polarization during acoustic resonator switching. The bulk acoustic wave excited in the piezoelectric or ferroelectric layer couples with the surface acoustic wave propagating in the intermediate layer. The Sc concentration in the ferroelectric layer exceeds 28%. The transducers are capped with Bragg reflectors made of multiple Al and W layers.

Aspects of this disclosure relate to an acoustic wave device with a piezoelectric layer that includes a wurtzite structure. The wurtzite structure can include a group 2 element and have a high acoustic velocity. For example, the wurtzite structure can include a carbide and the group 2 element can be carbon of the carbide. The high acoustic velocity can be over 10,000 meters per second. Related piezoelectric layers, acoustic wave filters, radio frequency modules, wireless communication devices, and methods are disclosed.

Aspects of the disclosure relate to an electroacoustic device that includes a piezoelectric material and an electrode structure. The electrode structure includes a first busbar and a second busbar. The electrode structure further includes a first conductive structure connected to the first busbar and a second conductive structure connected to the second busbar. The first conductive structure and the second conductive structure is disposed between the first busbar and the second busbar. The first conductive structure and the second conductive structure each include a plurality of conductive segments separated from each other and extending towards one of the first busbar or the second busbar. The electrode structure further includes electrode fingers arranged in an interdigitated manner and each connected to either the first conductive structure or the second conductive structure. The electrode fingers have a pitch that is different than a pitch of the plurality of conductive segments.

A piezoelectric thin film (PTF) is located above a carrier substrate. The PTF may be Z-cut LiNbO.sub.3 thin film adapted to propagate an acoustic wave in at least one of a first mode excited by an electric field oriented in a longitudinal direction along a length of the PTF or a second mode excited by the electric field oriented at least partially in a thickness direction of the PTF. A first interdigitated transducer (IDT) is disposed on a first end of the PTF. The first IDT is to convert a first electromagnetic signal, traveling in the longitudinal direction, into the acoustic wave. A second IDT is disposed on a second end of the PTF with a gap between the second IDT and the first IDT. The second IDT is to convert the acoustic wave into a second electromagnetic signal, and the gap determines a time delay of the acoustic wave.

An acoustic wave device includes a silicon oxide film, a piezoelectric body, and an interdigital transducer electrode laminated on a support substrate made of silicon. Where a wave length that is determined by an electrode finger pitch of the interdigital transducer electrode is λ, a thickness of the support substrate is greater than or equal to about 3λ. An acoustic velocity of the first higher mode that propagates through the piezoelectric body is an acoustic velocity V.sub.Si=(V.sub.1).sup.1/2 of bulk waves that propagate in the support substrate, which is determined by V.sub.1 out of solutions V.sub.1, V.sub.2, and V.sub.3 of x derived from the mathematical expression Ax.sup.3+Bx.sup.2+Cx+D=0, or higher than V.sub.Si.

A hybrid structure for a surface acoustic wave device comprises a useful layer of piezoelectric material having a first free surface and a second surface disposed on a support substrate that has a lower coefficient of thermal expansion than that of the useful layer, wherein the useful layer comprises an area of nanocavities.

Certain aspects of the present disclosure provide a filter. The filter generally includes a series resonator coupled between a first port of the filter and a second port of the filter, and a shunt resonator coupled between a node of the filter and a reference potential node of the filter, the node being coupled between the first port and the second port. The shunt resonator typically includes a first piezoelectric substrate, a first plurality of reflectors disposed above the first piezoelectric substrate, and a first plurality of interdigital transducers (IDTs) disposed above the first piezoelectric substrate and between the first plurality of reflectors, wherein the shunt resonator is configured as a dual mode structure (DMS).