Order–disorder transition in a two-dimensional boron–carbon–nitride alloy

Abstract

Two-dimensional boron-carbon-nitride materials exhibit a spectrum of electronic properties ranging from insulating to semimetallic, depending on their composition and geometry. Detailed experimental insights into the phase separation and ordering in such alloy are currently lacking. Here we report the mixing and demixing of boron-nitrogen and carbon phases on ruthenium (0001) and found that energetics for such processes are modified by the metal substrate. The brick-and-mortar patchwork observed of stoichiometrically percolated hexagonal boron-carbon-nitride domains surrounded by a network of segregated graphene nanoribbons can be described within the Blume-Emery-Griffiths model applied to a honeycomb lattice. The isostructural boron nitride and graphene assumes remarkable fluidity and can be exchanged entirely into one another by a catalytically assistant substitution. Visualizing the dynamics of phase separation at the atomic level provides the premise for enabling structural control in a two-dimensional network for broad nanotechnology applications.

Self-assembly of ordered graphene nanodot arrays

“…1b), the background appears as regions of disordered darker and brighter small spots, which covers most of the Ir surface. This structure closely resembles the brick-and-mortar structure reported by Lu et al 18 , resulting from the exposure of a submonolayer of graphene on a Ru(0001) substrate at 900 K to a low dose of borazine. Notably, the disordered background was identified as a BCN alloy, while the lines were interpreted as segregated graphene ribbons 18 .…”

“…This structure closely resembles the brick-and-mortar structure reported by Lu et al 18 , resulting from the exposure of a submonolayer of graphene on a Ru(0001) substrate at 900 K to a low dose of borazine. Notably, the disordered background was identified as a BCN alloy, while the lines were interpreted as segregated graphene ribbons 18 . A similar domain with disordered BCN alloy coexisting with bright-contrast faint lines was previously observed by Sutter et al 4 , while synthesizing graphene-hBN planar heterostructures on Ru.…”

Bandgap renormalization and work function tuning in MoSe2/hBN/Ru(0001) heterostructures

“…It had been used as a platform to grow graphene/hBN heterostructures25262728 and moreover, such heterostructures can be separated from the Ru(0001) substrate by using electrochemical exfoliation2930. Owing to the slight lattice mismatch between the hBN and Ru(0001) surfaces, a so-called nanomesh Moiré pattern forms2223.…”

Electromechanical response at polar zigzag boundaries in hybrid monolayers

“…In addition, we have evaluated the response to external electric fields and obtained a strong magnetoelectric effect that could be of much interest for spintronic applications based on carbon nanostructures. We propose that the recently grown ultrathin C ribbons segregated from percolated BC 2 N domains [33] could be candidates for the experimental observation of these effects. More importantly, the phenomena discussed here could also be expected for other two-dimensional materials whenever a polar discontinuity is present.…”

“…Recently, ultrathin graphene nanoribbons segregated from boron-carbon-nitride domains have been experimentally observed [33]. Scanning tunneling microscopy imaging found two dominant configurations for stoichiometrically percolated BC 2 N that correspond to the type I and type II polymorphic structures that were theoretically predicted in the late 1980's [34].…”