Size dictated thermal conductivity of GaN

Thomas E. Beechem, Anthony E. McDonald, Elliot J. Fuller, A. Alec Talin, Christina M. Rost, Jon Paul Maria, John T. Gaskins, Patrick E. Hopkins, Andrew A. Allerman

Research output: Contribution to journalArticlepeer-review

79 Scopus citations


The thermal conductivity of n- and p-type doped gallium nitride (GaN) epilayers having thicknesses of 3-4 μm was investigated using time domain thermoreflectance. Despite possessing carrier concentrations ranging across 3 decades (1015-1018cm-3), n-type layers exhibit a nearly constant thermal conductivity of 180 W/mK. The thermal conductivity of p-type epilayers, in contrast, reduces from 160 to 110 W/mK with increased doping. These trends - and their overall reduction relative to bulk - are explained leveraging established scattering models where it is shown that, while the decrease in p-type layers is partly due to the increased impurity levels evolving from its doping, size effects play a primary role in limiting the thermal conductivity of GaN layers tens of microns thick. Device layers, even of pristine quality, will therefore exhibit thermal conductivities less than the bulk value of 240 W/mK owing to their finite thickness.

Original languageEnglish (US)
Article number095104
JournalJournal of Applied Physics
Issue number9
StatePublished - Sep 7 2016

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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