Anisotropic and inhomogeneous thermal conduction in suspended thin-film polycrystalline diamond

Aditya Sood, Jungwan Cho, Karl D. Hobart, Tatyana I. Feygelson, Bradford B. Pate, Mehdi Asheghi, David G Cahill, Kenneth E. Goodson

Research output: Contribution to journalArticle

Abstract

While there is a great wealth of data for thermal transport in synthetic diamond, there remains much to be learned about the impacts of grain structure and associated defects and impurities within a few microns of the nucleation region in films grown using chemical vapor deposition. Measurements of the inhomogeneous and anisotropic thermal conductivity in films thinner than 10 μm have previously been complicated by the presence of the substrate thermal boundary resistance. Here, we study thermal conduction in suspended films of polycrystalline diamond, with thicknesses ranging between 0.5 and 5.6 μm, using time-domain thermoreflectance. Measurements on both sides of the films facilitate extraction of the thickness-dependent in-plane (κ r) and through-plane (κ z) thermal conductivities in the vicinity of the coalescence and high-quality regions. The columnar grain structure makes the conductivity highly anisotropic, with κ z being nearly three to five times as large as κ r, a contrast higher than that reported previously for thicker films. In the vicinity of the high-quality region, κ r and κ z range from 77 ± 10 W/m-K and 210 ± 50 W/m-K for the 1 μm thick film to 130 ± 20 W/m-K and 710 ± 120 W/m-K for the 5.6 μm thick film, respectively. The data are interpreted using a model relating the anisotropy to the scattering on the boundaries of columnar grains and the evolution of the grain size considering their nucleation density and spatial rate of growth. This study aids in the reduction in the near-interfacial resistance of diamond films and efforts to fabricate diamond composites with silicon and GaN for power electronics.

Original languageEnglish (US)
Article number175103
JournalJournal of Applied Physics
Volume119
Issue number17
DOIs
StatePublished - May 7 2016

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thick films
diamonds
conduction
thermal conductivity
thin films
nucleation
diamond films
coalescing
grain size
vapor deposition
impurities
conductivity
anisotropy
composite materials
defects
silicon
scattering
electronics

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Sood, A., Cho, J., Hobart, K. D., Feygelson, T. I., Pate, B. B., Asheghi, M., ... Goodson, K. E. (2016). Anisotropic and inhomogeneous thermal conduction in suspended thin-film polycrystalline diamond. Journal of Applied Physics, 119(17), [175103]. https://doi.org/10.1063/1.4948335

Anisotropic and inhomogeneous thermal conduction in suspended thin-film polycrystalline diamond. / Sood, Aditya; Cho, Jungwan; Hobart, Karl D.; Feygelson, Tatyana I.; Pate, Bradford B.; Asheghi, Mehdi; Cahill, David G; Goodson, Kenneth E.

In: Journal of Applied Physics, Vol. 119, No. 17, 175103, 07.05.2016.

Research output: Contribution to journalArticle

Sood, A, Cho, J, Hobart, KD, Feygelson, TI, Pate, BB, Asheghi, M, Cahill, DG & Goodson, KE 2016, 'Anisotropic and inhomogeneous thermal conduction in suspended thin-film polycrystalline diamond', Journal of Applied Physics, vol. 119, no. 17, 175103. https://doi.org/10.1063/1.4948335
Sood, Aditya ; Cho, Jungwan ; Hobart, Karl D. ; Feygelson, Tatyana I. ; Pate, Bradford B. ; Asheghi, Mehdi ; Cahill, David G ; Goodson, Kenneth E. / Anisotropic and inhomogeneous thermal conduction in suspended thin-film polycrystalline diamond. In: Journal of Applied Physics. 2016 ; Vol. 119, No. 17.
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