An acoustic wave device includes a scandium-containing aluminum nitride film and electrodes on at least one of first and second principal surfaces of the scandium-containing aluminum nitride film. The scandium-containing aluminum nitride film includes areas in which a crystal axis is deviated with respect to remaining portions of the scandium-containing aluminum nitride film.

An acoustic wave device is disclosed. The acoustic wave device can include a substrate, an interdigital transducer electrode disposed on the substrate, and a temperature compensation layer over the interdigital transducer electrode. The IDT electrode includes a lower layer, an upper layer, and a buffer layer disposed between the lower layer and the upper layer. A modulus of elasticity of the buffer layer is less than a modulus of elasticity of the upper layer. The buffer layer is configured to release stress between the lower layer and the upper layer caused due to a difference between a coefficient of thermal expansion of the lower layer and a coefficient of thermal expansion of the upper layer.

An acoustic wave device includes a crystal substrate, a silicon nitride film on the crystal substrate, a lithium tantalate layer on the silicon nitride film, and an interdigital transducer electrode on the lithium tantalate layer and including multiple first and second electrode fingers.

An acoustic wave device comprising a transmit filter including a plurality of surface acoustic wave resonators. Each surface acoustic wave resonator of the transmit filter including an interdigital transducer electrode comprising a first material. The acoustic wave device further comprising a receive filter including a plurality of surface acoustic wave resonators. At least a proportion of the plurality of surface acoustic wave resonators of the receive filter each including an interdigital transducer electrode comprising a second material. The density of the first material is greater than the density of the second material.

An acoustic wave device includes a crystal substrate, a silicon carbide layer on the crystal substrate, a lithium tantalate layer on the silicon carbide layer, and an interdigital transducer electrode on the lithium tantalate layer and including multiple first and second electrode fingers.

Aspects of this disclosure relate to a surface acoustic wave resonator. The surface acoustic wave resonator includes a piezoelectric substrate, interdigital transducer electrodes formed on an upper surface of the piezoelectric substrate, a dielectric temperature compensation layer formed on the piezoelectric substrate to cover the interdigital transducer electrodes, and a dielectric passivation layer over the temperature compensation layer. The passivation layer may include an oxide layer configured to have a sound velocity greater than that of the temperature compensation layer to suppress a transverse signal transmission.

An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode formed with the piezoelectric layer, a temperature compensation layer over the interdigital transducer electrode. The interdigital transducer electrode includes a bus bar and fingers that extend from the bus bar. The fingers each includes an edge portion and a body portion. The acoustic wave device can include a mass loading strip overlaps the edge portions of the fingers. The acoustic wave device can include a portion of the temperature compensation layer is positioned between the mass loading strip and the piezoelectric layer. The acoustic wave device can include a buffer layer that is disposed at least partially between the mass loading strip and the temperature compensation layer. The buffer layer can have a coefficient of thermal expansion greater than a coefficient of thermal expansion of the temperature compensation layer and less than a coefficient of thermal expansion of the mass loading strip.

An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode formed with the piezoelectric layer, a temperature compensation layer over the interdigital transducer electrode. The interdigital transducer electrode includes a bus bar and fingers that extend from the bus bar. The fingers each includes an edge portion and a body portion. The acoustic wave device can include a mass loading strip overlaps the edge portions of the fingers. The acoustic wave device can include a portion of the temperature compensation layer is positioned between the mass loading strip and the piezoelectric layer. The acoustic wave device can include a buffer layer that is disposed at least partially between the mass loading strip and the temperature compensation layer. A thickness of the buffer layer can be at least one forth a thickness of the mass loading strip. The buffer layer can be disposed at least partially between a bottom side, a top side, and a side wall of the mass loading strip and the temperature compensation layer.

An acoustic wave device and a method of forming the same is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode formed with the piezoelectric layer, and a temperature compensation layer over the interdigital transducer electrode. The interdigital transducer electrode includes a bus bar and fingers that extend from the bus bar. The fingers each includes an edge portion and a body portion. The acoustic wave device can include a mass loading strip that overlaps the edge portions of the fingers. A portion of the temperature compensation layer is positioned between the mass loading strip and the piezoelectric layer. The acoustic wave device can include a buffer layer that is disposed at least partially between the mass loading strip and the temperature compensation layer. The buffer layer includes a material different from materials of the temperature compensation layer and the mass loading strip.

An acoustic wave device is disclosed. The acoustic wave device can include a first multiplexer that has a first portion and a second portion. The acoustic wave device can include a second multiplexer that has a third portion and a fourth portion. The first portion and the third portion are formed in a first die. The second portion and the fourth portion are formed in a second die. A difference between a velocity of an acoustic wave that is generated by the first die and a velocity of an acoustic wave that is generated by the second die is at least 200 m/s.