The embodiments herein relate to surface acoustic wave (SAW) devices, such as filters and duplexers. The surface acoustic wave device includes piezoelectric layer and a high acoustic velocity layer coupled to the piezoelectric layer at a first surface of the high acoustic velocity layer. At least one transducer is provided within the high acoustic velocity layer and flush with or near the first surface. The at least one transducer is configured to propagate a surface acoustic wave having an operating wavelength along the piezoelectric layer.

A surface acoustic wave (SAW) device including a piezoelectric layer, a high acoustic velocity layer coupled to the piezoelectric layer, and at least one transducer. The SAW device may include a multi-layer graphene layer in the electrodes of the transducer and/or in a conductive layer that is coupled to the piezoelectric layer.

An acoustic wave device includes a piezoelectric layer, an IDT electrode, a high-acoustic-velocity support substrate, and a low-acoustic-velocity film. The high-acoustic-velocity support substrate is located on an opposite side of the piezoelectric layer from the IDT electrode in the thickness direction of the piezoelectric layer. The low-acoustic-velocity film is disposed between the high-acoustic-velocity support substrate and the piezoelectric layer in the thickness direction. The high-acoustic-velocity support substrate includes a base region and a surface region disposed nearer to the low-acoustic-velocity film than the base region in the thickness direction and whose crystal quality is worse than that of the base region. The surface region includes first and second layers disposed nearer to the base region than the first layer in the thickness direction and whose crystal quality is better than that of the first layer.

A surface acoustic wave (SAW) device including a piezoelectric layer, a high acoustic velocity layer coupled to the piezoelectric layer, and at least one transducer. The SAW device may include a multi-layer graphene layer in the electrodes of the transducer and/or in a conductive layer that is coupled to the piezoelectric layer.

An elastic wave device includes a support substrate, a polycrystalline nanodiamond layer provided directly or indirectly on the support substrate, at least one inorganic material layer provided on the polycrystalline nanodiamond layer, a piezoelectric body provided directly or indirectly on the at least one inorganic material layer, and an IDT electrode provided directly or indirectly on the piezoelectric body. The piezoelectric body propagates an elastic wave at a higher velocity than the polycrystalline nanodiamond layer propagates a bulk wave, and at a lower velocity than the at least one inorganic material layer propagates a bulk wave. The polycrystalline nanodiamond layer has a percentage of sp3 bonds of about 50% or more.

The embodiments herein relate to surface acoustic wave (SAW) devices, such as filters and duplexers. The surface acoustic wave device includes piezoelectric layer and a high acoustic velocity layer coupled to the piezoelectric layer at a first surface of the high acoustic velocity layer. At least one transducer is provided within the high acoustic velocity layer and flush with or near the first surface. The at least one transducer is configured to propagate a surface acoustic wave having an operating wavelength along the piezoelectric layer.

The embodiments herein relate to surface acoustic wave (SAW) devices, such as filters and duplexers. The SAW device may have a high acoustic velocity layer and a piezoelectric layer coupled to the high acoustic velocity layer. At least one transducer is coupled at least to the piezoelectric layer, where the transducer propagates a surface acoustic wave having an operating wavelength along a surface of the piezoelectric layer. A metallic layer may be coupled to the surface of the piezoelectric layer and electrically isolated from the transducer.

Methods for fabricating a piezoelectric device are provided. The methods can include providing a substrate and forming a nanocrystalline diamond layer on a first surface of the substrate. The methods can also include depositing a piezoelectric layer on a first surface of the nanocrystalline diamond layer.

A method for manufacturing an acoustic wave device with an excellent frequency-temperature profile is performed such that the acoustic wave device produced includes a piezoelectric substrate, an IDT electrode located on the piezoelectric substrate, and a dielectric film mainly including Si and O and arranged on the piezoelectric substrate to cover the IDT electrode. The dielectric film is formed by sputtering in a sputtering gas containing H.sub.2O.

A surface acoustic wave filter includes a support substrate with a first acoustic velocity layer disposed above. The first acoustic velocity layer is silicon dioxide with a piezoelectric layer above. Euler angles of a cut of the piezoelectric layer are (5 to 5, 81 to 83, 85 to 95), and an interdigital electrode is disposed above the piezoelectric layer. A second acoustic velocity layer included between the first acoustic velocity layer and the support substrate; and a material of the second acoustic velocity layer is aluminum nitride or silicon nitride, where a longitudinal wave acoustic velocity in the first acoustic velocity layer is lower than a longitudinal wave acoustic velocity in the piezoelectric layer, and a longitudinal wave acoustic velocity in the second acoustic velocity layer is higher than the longitudinal wave acoustic velocity in the piezoelectric layer.