jp1c07277_si_006.mp4 (11.79 MB)
An Ammonization-Based Transformation of Hexagonal Boron Nitride on Ir(111) from Surface to Near-Surface Regions
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posted on 2021-10-25, 16:40 authored by Jiaqi Pan, Wei Wei, Rui Wang, Rong Huang, Chi Zhang, Yi CuiEpitaxial
growth of thin films on solid substrates significantly
depends on the surface structure, including outmost and near-surface
reconstruction. Here, using in situ surface measurements,
we show an ammonization-based hexagonal boron nitride (h-BN) transformation
on the Ir(111) substrate, from surface to near-surface regions. Near-surface
B dopants are driven to segregate onto the surface induced by N atoms
from NH3 dehydrogenation; thus, B species react with N
species to form h-BN overlayers on the surface, i.e., the ammonization
growth route. Further, growth dynamics in near-surface-dependent ammonization
and normal chemical vapor deposition growth are systematically investigated.
The activation energy of the former is 0.53 eV higher than the latter.
The difference in growth barriers is attributed to the diffusion of
B species from near-surface to surface regions, causing the growth
mechanism changes from reaction-limited aggregation to diffusion-limited
aggregation. In addition, h-BN overlayers are converted into boron
oxide (B2O3) in an O2 atmosphere
and reverse back to h-BN by reacting with NH3 on the surface;
thus, a reversible structural transformation on the surface was achieved
by successive oxidation and ammonization. This work gains a deep understanding
of the h-BN conversion from surface to near-surface regions and provides
valuable insights into their evolution dynamics.
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provides valuable insights53 ev higherhexagonal boron nitridegrowth mechanism changesreversible structural transformation3 sub2 subb species reactammonization growth routesurface b dopantssitu b speciesgrowth dynamicsgrowth barriersboron oxiden specieswork gainsthin filmssystematically investigatedsurface structuresurface regionssurface reconstructionsurface measurementssurface inducedsuccessive oxidationsegregate ontoreverse backn atomslimited aggregationincluding outmostevolution dynamicse .,dependent ammonizationdeep understandingbased transformationactivation energy