  Some meta-stable polymorphs of bismuth monolayer (bismuthene) can host
topologically nontrivial phases. However, it remains unclear if these
polymorphs can become stable through interaction with a substrate, whether
their topological properties are preserved, and how to design an optimal
substrate to make the topological phase more robust. Using first-principles
techniques we demonstrate that bismuthene polymorphs can become stable over
silicon carbide (SiC), silicon (Si), silicon dioxide (SiO2) and that the
proximity interaction in the heterostructures has a significant effect on the
electronic structure of the monolayer, even when bonding is weak. We show that
the van der Waals interactions and the breaking of the sublattice symmetry are
the main factors driving changes in the electronic structure. Our work
demonstrates that substrate interaction can strengthen the topological
properties of bismuthene polymorphs and make them accessible for experimental
investigation and technological applications.
