TY  - JOUR
AU  - Haas, Benedikt
AU  - Boland, Tara M.
AU  - Elsässer, Christian
AU  - Singh, Arunima K.
AU  - March, Katia
AU  - Barthel, Juri
AU  - Koch, Christoph T.
AU  - Rez, Peter
TI  - Atomic-Resolution Mapping of Localized Phonon Modes at Grain Boundaries
JO  - Nano letters
VL  - 23
IS  - 13
SN  - 1530-6984
CY  - Washington, DC
PB  - ACS Publ.
M1  - FZJ-2023-03273
SP  - 5975 - 5980
PY  - 2023
AB  - 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.
LB  - PUB:(DE-HGF)16
C6  - 37341711
UR  - <Go to ISI:>//WOS:001016724900001
DO  - DOI:10.1021/acs.nanolett.3c01089
UR  - https://juser.fz-juelich.de/record/1014371
ER  -