Ultrahigh thermal conductivity of isotopically enriched silicon
- National Research Centre (NRC), Moscow (Russian Federation). Kurchatov Inst. (NRCKI)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
- Leibniz-Institut für Kristallzüchtung, Berlin (Germany)
- VITCON Projectconsult GmbH, Jena (Germany)
- Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)
Most of the stable elements possess two and more stable isotopes. The physical properties of materials composed of such elements depend on the isotopic abundance to some extent. A remarkably robust isotope effect is observed in the phonon thermal conductivity, the principal mechanism of heat conduction in nonmetallic crystals. An isotopic disorder due to random distribution of the isotopes in the crystal lattice sites results in a rather strong phonon scattering and, consequently, in a reduction of thermal conductivity. In this paper, we present new results of accurate and precise measurements of thermal conductivity κ(T) for silicon single crystals having three different isotopic compositions at temperatures T from 2.4 to 420 K. The highly enriched crystal containing 99.995% of 28Si, which is one of the most perfect crystals ever synthesized, demonstrates a thermal conductivity of about 450 ± 10 W cm-1K-1 at 24 K, the highest measured value among bulk dielectrics, which is ten times greater than the one for its counterpart natSi with the natural isotopic constitution. For highly enriched crystal 28Si and crystal natSi, the measurements were performed for two orientations [001] and [011], a magnitude of the phonon focusing effect on thermal conductivity was determined accurately at low temperatures. The anisotropy of thermal conductivity disappears above 31 K. The influence of the boundary scattering on thermal conductivity persists sizable up to much higher temperatures (~80 K). The κ(T) measured in this work gives the most accurate approximation of the intrinsic thermal conductivity of single crystal silicon which is determined solely by the anharmonic phonon processes and diffusive boundary scattering over a wide temperature range.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; Russian Foundation for Basic Research; USDOE
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1530344
- Alternate ID(s):
- OSTI ID: 1423925
- Journal Information:
- Journal of Applied Physics, Vol. 123, Issue 9; ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Thermal conductivity of strained silicon: Molecular dynamics insight and kinetic theory approach
|
journal | August 2019 |
Heat transfer in rough nanofilms and nanowires using full band ab initio Monte Carlo simulation
|
journal | November 2018 |
Heat transfer in rough nanofilms and nanowires using Full Band Ab Initio Monte Carlo simulation | text | January 2018 |
Thermal conductivity of strained silicon: molecular dynamics insight and kinetic theory approach | text | January 2019 |
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