Alloying Reversed Anisotropy of Thermal Transport in Bulk Al 0.5 Ga 0.5 N.

Anisotropic heat transfer is crucial for advanced thermal management in nanoelectronics, optoelectronics, thermoelectrics, etc . Traditional approaches modifying thermal conductivity (κ) mostly adjust the magnitude but disregard anisotropy. Herein, by solving the Boltzmann transport equation from first principles, we report κ anisotropy modulation by alloying gallium nitride (GaN) and aluminum nitride (AlN). The alloyed Al 0.5 Ga 0.5 N demonstrates reversed κ anisotropy compared to the parent materials, where the preferred thermal transport direction shifts from cross-plane to in-plane . Moreover, the κ anisotropy (κ in-plane /κ cross-plane ) in the Al 0.5 Ga 0.5 N alloy is enhanced to 1.63 and 1.51 times that in bulk GaN and AlN, respectively, which can be further enhanced by increased temperature. Deep analysis attributes the alloying reversed κ anisotropy of Al 0.5 Ga 0.5 N to the structure distortion-driven phonon group velocity, as well as phonon anharmonicity. The alloying reversed κ anisotropy as reported in this study sheds light on future studies in advanced heat dissipation and intelligent thermal management.