Phonon scattering at a crystal surface fromin situ-deposited thin films

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Abstract
We have studied diffuse scattering of phonons from in situ-deposited thin films (average thicknesses from 1 Å to 1 μm) using boundary-limited thermal conductivity measurements of the Si substrate. Our temperature range is 0.05-2 K corresponding to dominant phonon frequencies from 5 to 180 GHz. We show that the scattering occurs within the films themselves, not at the sample-film interface, and give evidence that this scattering is caused by structural irregularities of the thin films. Our findings have a direct bearing on the Kapitza resistance problem.