Methods for depositing bulk layer crystalline material having a predetermined c-axis tilt on a substrate include a first step of depositing a first portion of bulk layer material at a first incidence angle to achieve a predetermined c-axis tilt, and a second step of depositing a second portion of the bulk material layer onto the first portion at a second incidence angle that is smaller than the first incidence angle. The second portion has a second c-axis tilt that substantially aligns with the first c-axis tilt.

Aspects of this disclosure relate to a switchable acoustic wave filter. The switchable acoustic wave filter can include a switch configured to electrically connect an acoustic wave resonator to a node in a first state and to electrically isolate the acoustic wave resonator from the node in a second state. The switchable acoustic wave filter can filter a radio frequency signal with at least the acoustic wave resonator and a second acoustic wave resonator in the first state. The switchable acoustic wave filter can filter the radio frequency signal with at least the second acoustic wave resonator in the first state. Related multiplexers, radio frequency systems, wireless communication devices, and methods are also disclosed.

A structure includes a substrate including a wafer or a portion thereof; and a piezoelectric bulk material layer comprising a first portion deposited onto the substrate and a second portion deposited onto the first portion, the second portion comprising an outer surface having a surface roughness (Ra) of 4.5 nm or less. Methods for depositing a piezoelectric bulk material layer include depositing a first portion of bulk layer material at a first incidence angle to achieve a predetermined c-axis tilt, and depositing a second portion of the bulk material layer onto the first portion at a second incidence angle that is smaller than the first incidence angle. The second portion has a second c-axis tilt that substantially aligns with the first c-axis tilt.

Bulk acoustic wave resonator structures include a bulk layer with inclined c-axis hexagonal crystal structure piezoelectric material supported by a substrate. The bulk layer may be prepared without first depositing a seed layer on the substrate. The bulk material layer has a c-axis tilt of about 32 degrees or greater. The bulk material layer may exhibit a ratio of shear coupling to longitudinal coupling of 1.25 or greater during excitation. A method for preparing a crystalline bulk layer having a c-axis tilt includes depositing a bulk material layer directly onto a substrate at an off-normal incidence. The deposition conditions may include a pressure of less than 5 mTorr and a deposition angle of about 35 degrees to about 85 degrees.

A structure includes a substrate including a wafer or a portion thereof; and a piezoelectric bulk material layer comprising a first portion deposited onto the substrate and a second portion deposited onto the first portion, the second portion comprising an outer surface having a surface roughness (Ra) of 4.5 nm or less. Methods for depositing a piezoelectric bulk material layer include depositing a first portion of bulk layer material at a first incidence angle to achieve a predetermined c-axis tilt, and depositing a second portion of the bulk material layer onto the first portion at a second incidence angle that is smaller than the first incidence angle. The second portion has a second c-axis tilt that substantially aligns with the first c-axis tilt.

A filter is disclosed. The filter can be a band pass filter or a band rejection filter. The filter can have bulk acoustic wave resonators. The filter can include a shunt bulk acoustic wave resonator and a series bulk acoustic wave resonator. The shunt bulk acoustic wave resonator and the series bulk acoustic wave resonator include different raised frame structures. The different raised frame structures contribute to one of the shunt bulk acoustic wave resonator or the series bulk acoustic wave resonator to have a higher quality factor below a resonant frequency than the other.

An acoustic resonator filter includes a series portion of the acoustic resonator filter, the series portion including at least one series acoustic resonator electrically connected, in series, between first and second ports of the acoustic resonator filter configured to pass a radio-frequency (RF) signal from the first port to the second port, and a shunt portion of the acoustic resonator filter, the shunt portion including a plurality of shunt acoustic resonators electrically connected between one node of the series portion and a ground, where a difference between anti-resonant frequencies of each of the plurality of shunt acoustic resonators is smaller than a difference between resonant frequencies of each of the plurality of shunt acoustic resonators.

An acoustic wave device includes a support including a support substrate, a piezoelectric layer on the support, a functional electrode at the piezoelectric layer, a frame-shaped support frame on the piezoelectric layer and surrounding the functional electrode in a plan view in a stacking direction of the support and the piezoelectric layer, and a lid covering an opening of the support frame, wherein the support includes a first cavity at a position overlapping at least a portion of the functional electrode in the plan view, a second cavity defined by the piezoelectric layer, the support frame, and the lid between the piezoelectric layer and the lid, the piezoelectric layer includes a through hole communicating with the first and second cavities, and the first and second cavities are under vacuum.

The present disclosure provides an integration method and integration structure for a control circuit and an acoustic wave filter. The method includes: providing a base, the base being provided with a control circuit; forming a first cavity and a second cavity on the base; providing a Surface Acoustic Wave (SAW) resonating plate and a Bulk Acoustic Wave (BAW) resonating structure, a first input electrode and a first output electrode being arranged on a surface of the SAW resonating plate, a second input electrode and a second output electrode being arranged on a surface of the BAW resonating structure, and the BAW resonating structure including a third cavity; facing the surface of the SAW resonating plate towards the base, such that the SAW resonating plate is bonded to the base and seals the first cavity, and facing the surface of the BAW resonating structure towards the base, such that the BAW resonating structure is bonded to the base and seals the second cavity; and electrically connecting the control circuit to the first input electrode, the first output electrode, the second input electrode and the second output electrode. The present disclosure may control the acoustic filters through the control circuit provided on the base, and may avoid the problems of the complex electrical connection process, large insertion loss and the like due to a fact that the existing acoustic filters are integrated to the Printed Circuit Board (PCB) as discrete devices.

A Sc.sub.xAl.sub.1-xN based filter may include a Sc.sub.xAl.sub.1-xN material formed directly on a III-N material. The III-N material may include an n-type III-N layer or a III-N heterostructure having a 2DEG therein. The Sc.sub.xAl.sub.1-xN based filter may be monolithically integrated with a III-N device such as a HEMT device to form a monolithically integrated circuit.