Frequency dependence of the specular and diffuse phonon scattering from silicon surfaces

Abstract

Phonon backscattering experiments with polished silicon surfaces show that there is no Kapitza anomaly at frequencies corresponding to the aluminum junction detector threshold (sim80 GHz), whereas at higher frequencies the anomalous transmission into liquid helium or solid nitrogen increases (reduced backscattering by the coverage), closely related to the increase of the diffuse scattering at the uncovered surface.