Thermal conductivity of AlxGa1−xN layers with and variable thicknesses is systematically studied by combined thermoreflectance measurements and a modified Callaway model. We find a reduction in the thermal conductivity of AlxGa1−xN by more than one order of magnitude compared to that of GaN, which indicates a strong effect of phonon-alloy scattering. It is shown that the short-mean free path phonons are strongly scattered, which leads to a major contribution of the long-mean free path phonons to the thermal conductivity. In thin layers, the long-mean free path phonons become efficiently scattered by the boundaries, resulting in a further decrease in the thermal conductivity. Also, an asymmetry of thermal conductivity as a function of Al content is experimentally observed and attributed to the mass difference between Ga and Al host atoms.
Phonon-boundary scattering and thermal transport in AlxGa1−xN: Effect of layer thickness
Note: This paper is part of the Special Topic on Ultrawide Bandgap Semiconductors.
Dat Q. Tran, Rosalia Delgado-Carrascon, John F. Muth, Tania Paskova, Muhammad Nawaz, Vanya Darakchieva, Plamen P. Paskov; Phonon-boundary scattering and thermal transport in AlxGa1−xN: Effect of layer thickness. Appl. Phys. Lett. 21 December 2020; 117 (25): 252102. https://doi.org/10.1063/5.0031404
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