Experimental observation of high intrinsic thermal conductivity of AlN

Zhe Cheng, Yee Rui Koh, Abdullah Mamun, Jingjing Shi, Tingyu Bai, Kenny Huynh, Luke Yates, Zeyu Liu, Ruiyang Li, Eungkyu Lee, Michael E. Liao, Yekan Wang, Hsuan Ming Yu, Maki Kushimoto, Tengfei Luo, Mark S. Goorsky, Patrick E. Hopkins, Hiroshi Amano, Asif Khan, and Samuel Graham

Phys. Rev. Materials 4, 044602 – Published 23 April 2020

Abstract

Wurtzite AlN is an ultrawide bandgap semiconductor that has been developed for applications including power electronics and optoelectronics. Thermal management of these applications is the key for stable device performance and allowing for long lifetimes. However, the intrinsic high thermal conductivity of bulk AlN predicted by theoretical calculations has not been experimentally observed because of the difficulty in producing high-quality materials. This work reports the growth of thick (>15 μm) AlN layers by metal-organic chemical vapor deposition and experimental observation of intrinsic thermal conductivity from 130 to 480 K that matches density-functional-theory calculations for single crystal AlN, producing some of the highest values ever measured. Detailed material characterizations confirm the high quality of these AlN samples with one or two orders of magnitude lower impurity concentrations than commercially available bulk AlN. The thermal conductivity of these commercially available bulk AlN substrates are also measured as comparison. To interpret the reduced thermal conductivity, a simple Callaway model is built. This work demonstrates the possibility of obtaining theoretically high values of thermal conductivity in AlN and will impact the thermal management and reliability of future electronic and optoelectronics devices.

Received 15 January 2020
Accepted 13 March 2020

DOI:https://doi.org/10.1103/PhysRevMaterials.4.044602

Physics Subject Headings (PhySH)

Defects Phonons Thermal conductivity Thermal properties

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Zhe Cheng ¹, Yee Rui Koh², Abdullah Mamun ³, Jingjing Shi¹, Tingyu Bai⁴, Kenny Huynh⁴, Luke Yates¹, Zeyu Liu⁵, Ruiyang Li⁵, Eungkyu Lee⁵, Michael E. Liao ⁴, Yekan Wang⁴, Hsuan Ming Yu ⁴, Maki Kushimoto ⁶, Tengfei Luo⁵, Mark S. Goorsky⁴, Patrick E. Hopkins^2,8,9, Hiroshi Amano⁷, Asif Khan³, and Samuel Graham ^1,10,*

¹George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
²Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904, USA
³Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina 29208, USA
⁴Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
⁵Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
⁶Department of Electrical Engineering and Computer Science, Nagoya University, Furo-cho, Chikusa-ku 464–8603, Nagoya, Japan
⁷Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku 464–8601, Nagoya, Japan
⁸Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904, USA
⁹Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA
¹⁰School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA