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Title: Phonon scattering and transmission at silicon-helium interfaces

Abstract

Using a 2D thermal conductivity technique, the phonon scattering and transmission probabilities have been measured from 0.05K to 2.5K for silicon in contact with liquid [sup 4]He. For polished surfaces at low temperature, the diffuse scattering probability is less than 0.5%, and the classical Acoustic Mismatch Model of Khalatnikov correctly describes the observed transmission probability. At higher temperatures, the residual roughness of the surface causes additional diffuse phonon scattering which leads to enhanced transmission across the interface. Samples with thermal oxide films on the surfaces have additional diffuse scattering, which can be adequately described by assuming the films scatter phonons with the same probability as bulk a-SiO[sub 2]. Samples with either 60[angstrom] or 300[angstrom] Au films have diffuse scattering probabilities and transmission probabilities that are practically identical, confirming the hypothesis of Klitsner that thin Au films scatter phonons because of the [open quotes]mud-flat[close quotes] film morphology, a form of scattering that will not depend strongly on film thickness. The transmission probability is only 25-30% of that predicted by Diffuse Mismatch Model however, and this discrepancy has not been adequately explained. Samples with 2D Au diffraction gratings on them exhibited coherent resonant scattering of the phonons, but little phonon transmission. Samplesmore » which had been roughened by sandblasting or chemical etching had very high diffuse scattering probabilities, but the transmission probability for the sandblasted sample was much smaller than for the etched sample because of the subsurface damage caused the physical sandblasting process. Of the samples measured, only the etched sample showed a large transmission probability at low temperatures. Summarizing, the author has confirmed the veracity of the Acoustic Mismatch Model for the thermal boundary resistance at an ideal solid surface in contact with liquid helium.« less

Authors:
Publication Date:
Research Org.:
Cornell Univ., Ithaca, NY (United States)
OSTI Identifier:
7003462
Resource Type:
Miscellaneous
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; HELIUM 4; INTERFACES; THERMAL CONDUCTIVITY; PHONONS; SCATTERING; SILICON; CRYOGENICS; HEAT TRANSFER; SURFACE PROPERTIES; TEMPERATURE RANGE 0000-0013 K; ELEMENTS; ENERGY TRANSFER; EVEN-EVEN NUCLEI; HELIUM ISOTOPES; ISOTOPES; LIGHT NUCLEI; NUCLEI; PHYSICAL PROPERTIES; QUASI PARTICLES; SEMIMETALS; STABLE ISOTOPES; TEMPERATURE RANGE; THERMODYNAMIC PROPERTIES; 665000* - Physics of Condensed Matter- (1992-)

Citation Formats

Olson, J R. Phonon scattering and transmission at silicon-helium interfaces. United States: N. p., 1993. Web.
Olson, J R. Phonon scattering and transmission at silicon-helium interfaces. United States.
Olson, J R. 1993. "Phonon scattering and transmission at silicon-helium interfaces". United States.
@article{osti_7003462,
title = {Phonon scattering and transmission at silicon-helium interfaces},
author = {Olson, J R},
abstractNote = {Using a 2D thermal conductivity technique, the phonon scattering and transmission probabilities have been measured from 0.05K to 2.5K for silicon in contact with liquid [sup 4]He. For polished surfaces at low temperature, the diffuse scattering probability is less than 0.5%, and the classical Acoustic Mismatch Model of Khalatnikov correctly describes the observed transmission probability. At higher temperatures, the residual roughness of the surface causes additional diffuse phonon scattering which leads to enhanced transmission across the interface. Samples with thermal oxide films on the surfaces have additional diffuse scattering, which can be adequately described by assuming the films scatter phonons with the same probability as bulk a-SiO[sub 2]. Samples with either 60[angstrom] or 300[angstrom] Au films have diffuse scattering probabilities and transmission probabilities that are practically identical, confirming the hypothesis of Klitsner that thin Au films scatter phonons because of the [open quotes]mud-flat[close quotes] film morphology, a form of scattering that will not depend strongly on film thickness. The transmission probability is only 25-30% of that predicted by Diffuse Mismatch Model however, and this discrepancy has not been adequately explained. Samples with 2D Au diffraction gratings on them exhibited coherent resonant scattering of the phonons, but little phonon transmission. Samples which had been roughened by sandblasting or chemical etching had very high diffuse scattering probabilities, but the transmission probability for the sandblasted sample was much smaller than for the etched sample because of the subsurface damage caused the physical sandblasting process. Of the samples measured, only the etched sample showed a large transmission probability at low temperatures. Summarizing, the author has confirmed the veracity of the Acoustic Mismatch Model for the thermal boundary resistance at an ideal solid surface in contact with liquid helium.},
doi = {},
url = {https://www.osti.gov/biblio/7003462}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1993},
month = {1}
}

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