title: Studying Edge Defects of Hexagonal Boron Nitride Using High-Resolution Electron Energy Loss Spectroscopy.
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(3) 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⊥ mode.
authors.affiliation: Department of Chemistry and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543.|NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Centre for Life Sciences , #05-01, 28 Medical Drive, Singapore 117456.
authors.forename: Chang Tai
authors.initials: CT
authors.lastname: Nai
authors.affiliation: Department of Chemistry and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543.
authors.forename: Jiong
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Chemistry and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Chemistry and Graphene Research Centre, National University of Singapore , 3 Science Drive 3, Singapore 117543.
authors.forename: Kian Ping
authors.initials: KP
authors.lastname: Loh
keywords: 2D material; edge phonon; hexagonal boron nitride; high-resolution electron energy loss spectroscopy; optical phonon