Surface acoustic wave electroacoustic device for reduced transversal modes

A method for forming an electroacoustic device, comprising:

• forming a layer of a piezoelectric material;
• and
• forming an electrode structure on or above the piezoelectric material, forming the electrode structure comprising:
• forming a first busbar and a second busbar;
• forming electrode fingers arranged in an interdigitated manner, where forming the electrode fingers comprises forming a first plurality of fingers connected to the first busbar and forming a second plurality of fingers connected to the second busbar, a first distance between the first busbar and the second plurality of fingers and a second distance between the second busbar and the first plurality of fingers both being less than a pitch of the electrode fingers, the electrode fingers formed to have a central region and formed to have a first trap region and a second trap region respectively located on boundaries of the central region;
• and
• adjusting or forming a structural characteristic of the electroacoustic device in the first and second trap regions to reduce an acoustic velocity.

An electroacoustic device, comprising:

• a substrate;
• a piezoelectric material comprising Lithium tantalate disposed on the substrate;
• and
• an electrode structure disposed on the piezoelectric material and comprising:
• a first busbar and a second busbar;
• and
• electrode fingers arranged in an interdigitated manner and comprising a first plurality of fingers connected to the first busbar and a second plurality of fingers connected to the second busbar,
• a first distance between the first busbar and the second plurality of fingers and a second distance between the second busbar and the first plurality of fingers both being less than a pitch of the electrode fingers,
• the electrode fingers having a central region with a first trap region and a second trap region respectively located on boundaries of the central region, wherein a structural characteristic of the electroacoustic device is different in the first trap region and the second trap region relative to the central region.

An electroacoustic device, comprising:

• a piezoelectric material comprising Lithium tantalate disposed on a substrate;
• and
• an electrode structure disposed on the piezoelectric material and comprising:
• a first busbar and a second busbar;
• and
• electrode fingers arranged in an interdigitated manner and comprising a first plurality of fingers connected to the first busbar and a second plurality of fingers connected to the second busbar,
• the electrode fingers having a central region with a first trap region and a second trap region respectively located on boundaries of the central region, wherein a structural characteristic of the electroacoustic device is different in the first trap region and the second trap region relative to the central region to reduce an acoustic velocity of the electroacoustic device in a region defined by the first trap region and the second trap region relative to a region defined by the central region,
• wherein the acoustic velocity of the electroacoustic device in a region defined by the first busbar and the second busbar is higher than in the region defined by central region.