Elastic surface wave device having electrodes embedded in a piezoelectric layer, and design and production thereof

Abstract

An elastic surface wave device includes a piezoelectric layer, first and second interdigitated electrodes embedded in the piezoelectric layer, and a substrate carrying the piezoelectric layer and the electrodes. The substrate satisfies both of the following conditions: an attenuation of an elastic mode having an electrode in the piezoelectric layer is less than 0.1 dB/λ; and a speed ratio between a volumetric elastic shear mode for the substrate and a fundamental elastic shear mode for the piezoelectric layer is smaller than a predetermined speed ratio having a value equal to 1. The substrate is chosen from among gallium arsenide and a glass having a Young's modulus of between 60 GPa and 180 GPa, a Poisson's ratio of between 0.15 and 0.35, and a density of between 2000 kg/m3 and 6000 kg/m3.

Dependencies are inferred from the claim text.