Atomic-scale visualization of defect-induced localized vibrations in GaN

Phonon engineering is crucial for thermal management in GaN-based power devices, where phonon-defect interactions limit performance. However, detecting nanoscale phonon transport constrained by III-nitride defects is challenging due to limited spatial resolution. Here, we used advanced scanning transmission electron microscopy and electron energy loss spectroscopy to examine vibrational modes in a prismatic stacking fault in GaN. By comparing experimental results with ab initio calculations, we identified three types of defect-derived modes: localized defect modes, a confined bulk mode, and a fully extended mode. Additionally, the PSF exhibits a smaller phonon energy gap and lower acoustic sound speeds than defect-free GaN, suggesting reduced thermal conductivity. Our study elucidates the vibrational behavior of a GaN defect via advanced characterization methods and highlights properties that may affect thermal behavior.. Authors: Jiang, Hailing [Peking Univ., Beijing (China)]; Wang, Tao [Peking Univ., Beijing (China)] (ORCID:0000000247897041); Zhang, Zhenyu [Peking Univ., Beijing (China)]; Liu, Fang [Peking Univ., Beijing (China)] (ORCID:0000000217801723); Shi, Ruochen [Peking Univ., Beijing (China)]. DOE Contract: AC02-05CH11231; AC05-00OR22725. Subjects: 36 MATERIALS SCIENCE; semiconductors; transmission electron microscopy