A SAW resonator which, using a quartz crystal substrate with Euler angles (−1.5°≦φ≦1.5°, 117°≦θ≦142°, and 41.9°≦|ψ|≦49.57°, includes an IDT that excites a stop band upper end mode SAW, and an inter-electrode finger groove provided between electrode fingers configuring the IDT. When a wavelength of the SAW is λ, a first depth of the inter-electrode finger groove is G, a line occupation rate of the IDT is η, and an electrode film thickness of the IDT is H, λ, G, η and H satisfy the relationship of 0<H≦0.005λ, 0.01λ≦G≦0.09λ, and 0.18≦η≦0.71.

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.

Surface acoustic wave device having mass-loaded electrode. In some embodiments, a surface acoustic wave device for providing resonance of a surface acoustic wave having a wavelength λ can include a quartz substrate and a piezoelectric plate formed from LiTaO.sub.3 or LiNbO.sub.3 disposed over the quartz substrate. The piezoelectric plate can have a thickness greater than 2λ. The surface acoustic wave device can further include an interdigital transducer electrode formed over the piezoelectric plate. The interdigital transducer electrode can have a mass density ρ in a range 1.50 g/cm.sup.3<ρ≤6.00 g/cm.sup.3, 6.00 g/cm.sup.3<ρ≤12.0 g/cm.sup.3, or 12.0 g/cm.sup.3<ρ≤23.0 g/cm.sup.3, and a thickness greater than 0.148λ, greater than 0.079λ, or greater than 0.036λ, respectively.

In a surface acoustic wave filter according to an embodiment, a thickness of a piezoelectric crystal substrate bonded over a support substrate made of an oxide crystal is 0.05 to 0.5 μm, and an odd-order harmonic is used.

An acoustic wave device that has a better TCF and can improve a resonator Q or impedance ratio is provided. The acoustic wave device includes a substrate 11 containing 70 mass % or greater of silicon dioxide (SiO.sub.2), a piezoelectric thin film 12 including LiTaO.sub.3 crystal or LiNbO.sub.3 crystal and disposed on the substrate 11, and an interdigital transducer electrode 13 disposed in contact with the piezoelectric thin film 12.

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.

An acoustic wave element which can be reduced in size and produced relatively easily, practically used without using harmful substances, and can suppress a surface acoustic wave propagation loss, which has an excellent temperature coefficient of frequency and a velocity dispersion characteristic, and with which an increase in the reflection coefficient of interdigital transducers can be suppressed, and a method for manufacturing the acoustic wave element are provided. The acoustic wave element includes a pair of electrodes provided on both surfaces of a piezoelectric substrate, and a dielectric film provided on a first surface of the piezoelectric substrate so as to cover the electrode. The acoustic wave element alternatively includes interdigital transducers provided on a first surface of the piezoelectric substrate, and a dielectric film provided on the interdigital transducers, a gap between the interdigital transducers, and/or a second surface of the piezoelectric substrate.

An acoustic wave device includes a support substrate, a piezoelectric layer, and an IDT electrode. The support substrate is made of quartz. The piezoelectric layer is provided on the support substrate and is made of LiTaO.sub.3. The IDT electrode is on the piezoelectric layer and includes electrode fingers. The IDT electrode is on a negative surface side of the piezoelectric layer. The cut angle of the piezoelectric layer is equal to or more than about 39° Y and equal to or less than about 48° Y.

A piezoelectric composite substrate for SAW devices with small loss is provided. A composite substrate for a surface acoustic wave device according to one embodiment of the present invention has a piezoelectric single crystal thin film, a support substrate, and a first intervening layer between the piezoelectric single crystal thin film and the support substrate. In said composite substrate, the first intervening layer is in contact with the piezoelectric single crystal thin film, and the acoustic velocity of the transverse wave in the first intervening layer is faster than the acoustic velocity of the fast transverse wave in the piezoelectric single crystal thin film.

A surface-acoustic-wave (SAW) resonator includes a substrate formed from an anisotropic crystal and first and second acoustic reflectors disposed on a surface of the substrate. The first and second acoustic reflectors face each other to form an acoustic cavity whose axis is aligned with a crystallographic orientation of the anisotropic crystal such that the SAW resonator is minimally diffracting at cryogenic temperatures. The substrate may be a piezoelectric crystal, in which case the acoustic cavity can be excited by driving electrodes located on the surface of the substrate. Since the SAW resonator is minimally diffracting, it has less loss, and therefore can achieve higher Qs, than SAW resonators based on other crystallographic orientations.