Single-Atom-Resolved Vibrational Spectroscopy of a Dislocation.

Abstract

Dislocations in III-nitride semiconductors impede heat transport, leading to localized overheating, which severely limits the performance and reliability of optoelectronic and power devices. Current research on phonon-dislocation interactions primarily addresses bulk materials, focusing on the average effects at specific dislocation densities. However, phonon resistance from dislocation scattering arises from both short-range core interactions and long-range strain field interactions, which remain largely unexplored. Here, electron energy-loss spectroscopy is used to investigate a GaN dislocation. Vibrational modes localized on specific core atoms are revealed, reflecting short-range interactions. Additionally, phonon energy shifts driven by strain fields surrounding the dislocation are observed, reflecting long-range interactions. <i>Ab initio</i> calculations support these findings and draw out additional details. This work establishes a paradigm for probing defect-induced phonon scattering at the single-atom level, revealing how dislocations affect phonon behavior through atomic reconstruction and strain engineering, thus offering insights for designing improved material functionalities.