A composite substrate includes a supporting substrate and a functional substrate that are directly joined together, the supporting substrate being a sintered sialon body.

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.

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.

An elastic wave device includes a supporting substrate, an acoustic reflection layer disposed on the supporting substrate, a piezoelectric layer disposed on the acoustic reflection layer, and an interdigital transducer electrode disposed on the piezoelectric layer. The acoustic reflection layer includes three or more low acoustic impedance layers and two or more high acoustic impedance layers. A film thickness of the low acoustic impedance layer closest to the piezoelectric layer is larger than a film thickness of the low acoustic impedance layer closest to the low acoustic impedance layer that is closest to the piezoelectric layer.

An elastic wave device includes a supporting substrate, an acoustic reflection layer disposed on the supporting substrate, a piezoelectric layer disposed on the acoustic reflection layer, and an interdigital transducer electrode disposed on the piezoelectric layer. The acoustic reflection layer includes three or more low acoustic impedance layers and two or more high acoustic impedance layers. A film thickness of the low acoustic impedance layer closest to the piezoelectric layer is larger than a film thickness of the low acoustic impedance layer closest to the low acoustic impedance layer that is closest to the piezoelectric layer.

An acoustic wave device is disclosed. The acoustic wave device includes a support layer, a ceramic layer positioned over the support layer, a piezoelectric layer positioned over the ceramic layer, and an interdigital transducer electrode positioned over the piezoelectric layer. The support layer has a higher thermal conductivity than the ceramic layer. The ceramic layer can be a polycrystalline spinel layer. The acoustic wave device can be a surface acoustic wave device configured to generate a surface acoustic wave.

An acoustic wave device is disclosed. The acoustic wave device includes a support layer, a ceramic layer positioned over the support layer, a piezoelectric layer positioned over the ceramic layer, and an interdigital transducer electrode positioned over the piezoelectric layer. The support layer has a higher thermal conductivity than the ceramic layer. The ceramic layer can be a polycrystalline spinel layer. The acoustic wave device can be a surface acoustic wave device configured to generate a surface acoustic wave.

An acoustic wave device includes: a support substrate; a single piezoelectric substrate that is located on the support substrate and is single-crystal; first electrodes located on a first surface of the piezoelectric substrate; second electrodes located on a second surface of the piezoelectric substrate; and an acoustic mirror that is bonded on the support substrate, is located between the support substrate and the first electrodes in resonance regions where the first electrodes and the second electrodes face each other across at least a part of the piezoelectric substrate, is not located between the support substrate and the first electrodes in at least a part of a region between the resonance regions, and reflects an acoustic wave propagating through the piezoelectric substrate.

An acoustic wave device includes: a support substrate; a single piezoelectric substrate that is located on the support substrate and is single-crystal; first electrodes located on a first surface of the piezoelectric substrate; second electrodes located on a second surface of the piezoelectric substrate; and an acoustic mirror that is bonded on the support substrate, is located between the support substrate and the first electrodes in resonance regions where the first electrodes and the second electrodes face each other across at least a part of the piezoelectric substrate, is not located between the support substrate and the first electrodes in at least a part of a region between the resonance regions, and reflects an acoustic wave propagating through the piezoelectric substrate.

Guided Surface Acoustic Wave (SAW) devices with improved quartz orientations are disclosed. A guided SAW device includes a quartz carrier substrate, a piezoelectric layer on a surface of the quartz carrier substrate, and at least one interdigitated transducer on a surface of the piezoelectric layer opposite the quartz carrier substrate. The quartz carrier substrate includes an orientation that provides improved performance parameters for the SAW device, including electromechanical coupling factor, resonator quality factor, temperature coefficient of frequency, and delta temperature coefficient of frequency.