Velocity of subsonic and hypersonic surface acoustic waves on silicon with native oxide layer
Résumé
The anisotropic dependence of the velocity of surface acoustic
waves (SAW) on silicon is explored using surface Brillouin light
scattering. Measurements of the SAW velocity are compared to a
numerical model that takes into account the native thin amorphous
oxide layer formed at the top surface of the silicon wafer. The
model accounts for material loss and provides a relative estimate
for the backscattered intensity resulting from the ripple effect.
For the (100) sample considered, a thickness of 4 nm fits well with
experimental data, considering material constants of amorphous
silica for the oxide. A global phase velocity decrease of −11 m/s
per nanometer of silica thickness is predicted for surface phonons
at frequencies around 16 GHz.
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