Phonon transport in Al-rich AlxGa1−xN thin films
Abstract
AlxGa1−xN with a high Al composition (x) presents significant potential for advancing next-generation high-power electronic devices. To support the thermal design of AlxGa1−xN-based electronics, the thermal conductivity of AlxGa1−xN thin films was measured as a function of Al composition, temperature, and film thickness using time-domain thermoreflectance and frequency-domain thermoreflectance techniques. The measurement results were interpreted by modeling phonon transport in AlxGa1−xN films using the phonon Boltzmann transport equation. Phonon properties, including frequencies, group velocities, and lifetimes, were calculated using a virtual crystal approximation, with the effects of mass-disorder scattering incorporated via the Tamura model. The measured thermal conductivity of Al0.7Ga0.3N is an order of magnitude lower than those for GaN and AlN, exhibits an increase followed by saturation with temperature, and shows a modest decrease with a reduction in the film thickness. The modeling results agree with the measurement results and reveal that mass-disorder scattering and phonon-boundary scattering are the dominant mechanisms that reduce the thermal conductivity of AlxGa1−xN thin films.
Article Details
Journal Info
Journal of Applied Physics
American Institute of Physics
Authors (15)
Kyuhwe Kang
Department of Mechanical Engineering, The Pennsylvania State University 1 , University Park, Pennsylvania 16802,
Abhishek Pathak
Yiwen Song
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics
Husam Walwil
Department of Mechanical Engineering, The Pennsylvania State University 1 , University Park, Pennsylvania 16802,
Timothy Mirabito
Department of Materials Science and Engineering, The Pennsylvania State University, 3 University Park, Pennsylvania 16802,
Nathaniel S. McIlwaine
Department of Materials Science and Engineering, The Pennsylvania State University, 3 University Park, Pennsylvania 16802,
Mihee Ji
DEVCOM Army Research Laboratory 4 , Adelphi, Maryland 20783,
LeighAnn S. Larkin
DEVCOM Army Research Laboratory 4 , Adelphi, Maryland 20783,
Christopher B. Saltonstall
Sandia National Laboratories 5 , Albuquerque, New Mexico 87123,
Andrew A. Allerman
Sandia National Laboratories 2 , Albuquerque, New Mexico 87123,
Jon-Paul Maria
Joan M. Redwing
Jonathan A. Malen
Department of Mechanical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213,
Alan J. H. McGaughey
Department of Mechanical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213,
Sukwon Choi
Department of Mechanical Engineering, The Pennsylvania State University 1 , University Park, Pennsylvania 16802,