Unusually low thermal conductivity of gallium nitride nanowires

  • Guthy C
  • Nam C
  • Fischer J
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Abstract

We report measurements of thermal conductivity κ on individual gallium nitride nanowires (GaN NWs) with diameters ranging from 97 to 181 nm grown by thermal chemical vapor deposition. We observed unexpectedly small κ values, in the range of 13–19 W/m K at 300 K, with very weak diameter dependence. We also observe unusual power law κ∼Tn behavior with n=1.8 at low temperature. Electron-energy-loss-spectroscopy measurements indicate Si and O concentrations in the ranges of 0.1–1 and 0.01–0.1 at. %, respectively. Based on extensive numerical calculations, we conclude that both the unexpectedly low κ and the T1.8 dependence are caused by unusually large mass-difference scattering, primarily from Si impurities. Our analysis also suggests that mass-difference scattering rates are significantly enhanced by the reduced phonon group velocity in nanoscale systems. Planar defects running the length of the NW, previously characterized in detail, may also play a role in limiting the phonon mean free path. [ABSTRACT FROM AUTHOR] Copyright of Journal of Applied Physics is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Authors

  • Csaba Guthy

  • Chang-yong Yong Nam

  • John E. Fischer

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