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Dislocation-induced thermal transport anisotropy in single-crystal group-III nitride films

Dislocation-induced thermal transport anisotropy in single-crystal group-III nitride films Dislocations, one-dimensional lattice imperfections, are common to technologically important materials such as III–V semiconductors, and adversely affect heat dissipation in, for example, nitride-based high-power electronic devices. For decades, conventional nonlinear elasticity models have predicted that this thermal resistance is only appreciable when the heat flux is perpendicular to the dislocations. However, this dislocation-induced anisotropic thermal transport has yet to be seen experimentally. Using time-domain thermoreflectance, we measure strong thermal transport anisotropy governed by highly oriented threading dislocation arrays throughout micrometre-thick, single-crystal indium nitride films. We find that the cross-plane thermal conductivity is almost tenfold higher than the in-plane thermal conductivity at 80 K when the dislocation density is ~3 × 1010 cm−2. This large anisotropy is not predicted by conventional models. With enhanced understanding of dislocation–phonon interactions, our results may allow the tailoring of anisotropic thermal transport with line defects, and could facilitate methods for directed heat dissipation in the thermal management of diverse device applications. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Materials Springer Journals

Dislocation-induced thermal transport anisotropy in single-crystal group-III nitride films

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References (71)

Publisher
Springer Journals
Copyright
Copyright © 2018 by The Author(s), under exclusive licence to Springer Nature Limited
Subject
Materials Science; Materials Science, general; Optical and Electronic Materials; Biomaterials; Nanotechnology; Condensed Matter Physics
ISSN
1476-1122
eISSN
1476-4660
DOI
10.1038/s41563-018-0250-y
Publisher site
See Article on Publisher Site

Abstract

Dislocations, one-dimensional lattice imperfections, are common to technologically important materials such as III–V semiconductors, and adversely affect heat dissipation in, for example, nitride-based high-power electronic devices. For decades, conventional nonlinear elasticity models have predicted that this thermal resistance is only appreciable when the heat flux is perpendicular to the dislocations. However, this dislocation-induced anisotropic thermal transport has yet to be seen experimentally. Using time-domain thermoreflectance, we measure strong thermal transport anisotropy governed by highly oriented threading dislocation arrays throughout micrometre-thick, single-crystal indium nitride films. We find that the cross-plane thermal conductivity is almost tenfold higher than the in-plane thermal conductivity at 80 K when the dislocation density is ~3 × 1010 cm−2. This large anisotropy is not predicted by conventional models. With enhanced understanding of dislocation–phonon interactions, our results may allow the tailoring of anisotropic thermal transport with line defects, and could facilitate methods for directed heat dissipation in the thermal management of diverse device applications.

Journal

Nature MaterialsSpringer Journals

Published: Dec 17, 2018

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