Studying Edge Defects of Hexagonal Boron Nitride Using
High-Resolution Electron Energy Loss Spectroscopy
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Abstract
Studying the phonons of hexagonal
boron nitride (h-BN) is important
for understanding its thermal, electronic, and imaging applications.
Herein, we applied high-resolution electron energy loss spectroscopy
(HREELS) to monitor the presence of edge defects in h-BN films. We
observed an edge phonon at 90.5 meV with the initial formation of
island-like domains on Ru(0001), which subsequently weakens with respect
to the bulk phonon as the islands congregate into a film. The presence
of a weak edge phonon peak even at full surface coverage of the h-BN
film indicates the sensitivity of HREELS in detecting line defects.
A shoulder peak at ∼160 meV assignable to sp<sup>3</sup> bonded
modes was attributed to grain boundaries arising from misaligned domains.
In addition, the strengths of substrate interaction and the rippling
of the h-BN film can be judged from the shift in the phonon energy
of the out-of-plane TO<sub>⊥</sub> mode
