GaN thermal transport limited by the interplay of dislocations and size effects
Hang Li, Riley Hanus, Carlos A. Polanco, A. Zeidler, Gregor Koblmüller, Yee Kan Koh, Lucas Lindsay
Abstract
Measurements and first-principles calculations probe the temperature-dependent thermal conductivity $(k)$ of GaN films with large densities of highly oriented dislocations. We demonstrate that phonon-dislocation scattering is weaker than suggested by previous measurements, likely due to sample and experiment size effects. Nonetheless, dislocation-limited $k$ is observed in samples with large dislocation densities and at lower temperatures where $k$ anisotropy is also observed. Combination of experiment and theory give insights into the interplay of thermal resistance mechanisms limiting GaN functionalities and suggest pathways for tuning $k$ via defect engineering.