Dispersion of surface acoustic waves in thin films at extreme wavelength-to-thickness ratios

Marc Duquennoy (1, 2, 3) , Tahar Kadi (2) , Mohammadi Ouaftouh (3, 2, 1) , Nikolay Smagin (1, 3) , Frédéric Jenot (2, 3, 1)

1 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
2 TPIA - IEMN - Transduction, Propagation et Imagerie Acoustique - IEMN
3 UPHF - Université Polytechnique Hauts-de-France

Surface acoustic waves (SAWs) are sensitive to the presence of a layer on the surface of a material, even if this layer is extremely thin compared to their wavelengths. Given the very slow propagation velocities of SAWs compared to electromagnetic waves, their wavelengths are on the order of 40 μm for acoustic frequencies on the order of 100 MHz. However, it has been shown that these waves are dispersive for coatings whose thicknesses are more than 1000 times smaller than their wavelength. This sensitivity is verified by studying the dispersion of SAWs for a frequency range between 90 and 260 MHz.

Mots clés: Thin films; Interdigital transducers; Vibrometer; Rayleigh waves; Poisson's ratio; Electromagnetism; Elastic modulus; Fourier analysis; Atomic force microscopy; Surface acoustic waves

Domaines: Sciences de l'ingénieur [physics]

Marc Duquennoy, Tahar Kadi, Mohammadi Ouaftouh, Nikolay Smagin, Frédéric Jenot. Dispersion of surface acoustic waves in thin films at extreme wavelength-to-thickness ratios. JASA Express Letters, 2022, 2 (10), pp.104002. ⟨10.1121/10.0014859⟩. ⟨hal-03835165⟩