Electro-acoustic transducer with periodic ferroelectric polarization produced on a micromachined vertical structure

摘要

A piezoelectric and ferroelectric bulk wave transducer operating at a predetermined frequency includes a block of substrate, having a first thickness and in a first material, and a piezoelectric and ferroelectric transduction plate, having a length, a width and a second thickness, and in a second piezoelectric material, first and second metal electrodes covering the plate in the direction of the length thereof. The plate has first and second ferroelectric domains with alternating polarizations, distributed along the length of the plate according to a periodic pattern of pitch. The plate is attached perpendicularly to the block so that the width of the plate and the first thickness of the block are the same direction. The first and second material, the first thickness of the block, the length, the width, the second thickness, the pitch of the plate are configured for generating and trapping bulk waves at the operating frequency of the transducer, guided between both electrodes.

主权项

1. A bulk wave piezoelectric transducer operating at a predetermined frequency f and comprising:
a block of substrate comprising a plane face having a first thickness along a normal to the plane face and comprising of a first material, and a piezoelectric transduction plate comprising a first and a second plane face positioned facing each other, having a length, a width and a second thickness, and comprised of a second piezoelectric material, first and second metal electrodes covering at least partly the first face and the second face of the piezoelectric transduction plate respectively and at least partly facing each other, wherein: the piezoelectric transduction plate is formed by a ferroelectric material layer which comprises first domains with a positive polarization and second domains with a negative polarization, the first domains and the second domains being distributed in the direction of the length of the piezoelectric transduction plate alternately according to a repetition pattern, the repetition pattern being defined by a pitch and a cyclic ratio, and the piezoelectric transduction plate is attached perpendicularly in the vicinity of the plane face of the block of substrate so that the width of the piezoelectric transduction plate and the first thickness of the block of substrate have a same direction, and the first material, the second material, the first thickness of the block of substrate, the length, the width, the second thickness of the piezoelectric transduction plate, the pitch are configured in order to generate and trap bulk waves at the operating frequency of the transducer, which are guided between both of the plane faces of the piezoelectric transduction plate, the guided acoustic waves propagating in the direction of the length L of the transduction plate.