Title: Ultrahigh thermal conductivity of isotopically enriched silicon

Abstract

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 atmore » 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.« less

Authors:

Inyushkin, Alexander V.  ^[1];

• Search DOE PAGES for author "Inyushkin, Alexander V."
• Search DOE PAGES for ORCID "0000-0002-3809-3615"

Taldenkov, Alexander N. ^[1]; Ager, Joel W.  ^[2];

• Search DOE PAGES for author "Ager, Joel W."
• Search DOE PAGES for ORCID "0000-0001-9334-9751"

Haller, Eugene E. ^[2]; Riemann, Helge ^[3]; Abrosimov, Nikolay V.  ^[3];

• Search DOE PAGES for author "Abrosimov, Nikolay V."
• Search DOE PAGES for ORCID "0000-0002-2042-4754"

Pohl, Hans-Joachim ^[4]; Becker, Peter ^[5]

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+ Show Author Affiliations

1. National Research Centre (NRC), Moscow (Russian Federation). Kurchatov Inst. (NRCKI)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
3. Leibniz-Institut für Kristallzüchtung, Berlin (Germany)
4. VITCON Projectconsult GmbH, Jena (Germany)
5. Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

Publication Date:

Tue Mar 06 00:00:00 EST 2018

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; Russian Foundation for Basic Research; USDOE

OSTI Identifier:

1530344

Alternate Identifier(s):

OSTI ID: 1423925

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Applied Physics

Additional Journal Information:

Journal Volume: 123; Journal Issue: 9; Journal ID: ISSN 0021-8979

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY