Details

Autor(en) / Beteiligte

• Haas, Benedikt
• Boland, Tara M.
• Elsässer, Christian
• Singh, Arunima K.
• March, Katia
• Barthel, Juri
• Koch, Christoph T.
• Rez, Peter

Titel

Atomic-Resolution Mapping of Localized Phonon Modes at Grain Boundaries

Ist Teil von

• Nano letters, 2023-07, Vol.23 (13), p.5975-5980

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2023

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Phonon scattering at grain boundaries (GBs) is significant in controlling the nanoscale device thermal conductivity. However, GBs could also act as waveguides for selected modes. To measure localized GB phonon modes, milli-electron volt (meV) energy resolution is needed with subnanometer spatial resolution. Using monochromated electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) we have mapped the 60 meV optic mode across GBs in silicon at atomic resolution and compared it to calculated phonon densities of states (DOS). The intensity is strongly reduced at GBs characterized by the presence of 5- and 7-fold rings where bond angles differ from the bulk. The excellent agreement between theory and experiment strongly supports the existence of localized phonon modes and thus of GBs acting as waveguides.