Direct Visualization of Thermal Conductivity Suppression Due to Enhanced Phonon Scattering Near Individual Grain Boundaries

Aditya Sood, Ramez Cheaito, Tingyu Bai, Heungdong Kwon, Yekan Wang, Chao Li, Luke Yates, Thomas Bougher, Samuel Graham, Mehdi Asheghi, Mark Goorsky, Kenneth E. Goodson

Research output: Contribution to journalArticlepeer-review

83 Scopus citations

Abstract

Understanding the impact of lattice imperfections on nanoscale thermal transport is crucial for diverse applications ranging from thermal management to energy conversion. Grain boundaries (GBs) are ubiquitous defects in polycrystalline materials, which scatter phonons and reduce thermal conductivity (κ). Historically, their impact on heat conduction has been studied indirectly through spatially averaged measurements, that provide little information about phonon transport near a single GB. Here, using spatially resolved time-domain thermoreflectance (TDTR) measurements in combination with electron backscatter diffraction (EBSD), we make localized measurements of κ within few μm of individual GBs in boron-doped polycrystalline diamond. We observe strongly suppressed thermal transport near GBs, a reduction in κ from ∼1000 W m-1 K-1 at the center of large grains to ∼400 W m-1 K-1 in the immediate vicinity of GBs. Furthermore, we show that this reduction in κ is measured up to ∼10 μm away from a GB. A theoretical model is proposed that captures the local reduction in phonon mean-free-paths due to strongly diffuse phonon scattering at the disordered grain boundaries. Our results provide a new framework for understanding phonon-defect interactions in nanomaterials, with implications for the use of high-κ polycrystalline materials as heat sinks in electronics thermal management.

Original languageEnglish (US)
Pages (from-to)3466-3472
Number of pages7
JournalNano Letters
Volume18
Issue number6
DOIs
StatePublished - Jun 13 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Condensed Matter Physics
  • Mechanical Engineering
  • Bioengineering
  • General Materials Science

Keywords

  • Grain boundary
  • disorder
  • phonon scattering
  • thermal management
  • time-domain thermoreflectance

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