Single-Atom-Resolved Vibrational Spectroscopy of a Dislocation

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. Ab initio 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.