Thermal conductivity of crystalline AlN and the influence of atomic-scale defects

Runjie Lily Xu, Miguel Muñoz Rojo, SM Islam, Aditya Sood, Bozo Vareskic, Ankita Katre, Natalio Mingo, Kenneth E. Goodson, Huili Grace Xing, Debdeep Jena, Eric Pop*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

6 Citations (Scopus)

Abstract

Aluminum nitride (AlN) plays a key role in modern power electronics and deep-ultraviolet photonics, where an understanding of its thermal properties is essential. Here, we measure the thermal conductivity of crystalline AlN by the 3ω method, finding that it ranges from 674 ± 56 Wm−1 K−1 at 100 K to 186 ± 7 Wm−1 K−1 at 400 K, with a value of 237 ± 6 Wm−1 K−1 at room temperature. We compare these data with analytical models and first-principles calculations, taking into account atomic-scale defects (O, Si, C impurities, and Al vacancies). We find that Al vacancies play the greatest role in reducing thermal conductivity because of the largest mass-difference scattering. Modeling also reveals that 10% of heat conduction is contributed by phonons with long mean free paths (MFPs), over ∼7 μm at room temperature, and 50% by phonons with MFPs over ∼0.3 μm. Consequently, the effective thermal conductivity of AlN is strongly reduced in submicrometer thin films or devices due to phonon-boundary scattering.
Original languageEnglish
Article number185105
JournalJournal of Applied Physics
Volume126
Issue number18
DOIs
Publication statusPublished - 14 Nov 2019

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