Tuning the Topological Band Gap of Bismuthene with Silicon-based Substrate

TL;DR

This study uses first-principles calculations to show that silicon-based substrates can stabilize bismuthene polymorphs, preserve their topological properties, and enhance their potential for experimental and technological use.

Contribution

The paper demonstrates that silicon-based substrates can stabilize bismuthene polymorphs and influence their topological electronic properties through substrate interactions.

Findings

Bismuthene polymorphs become stable on SiC, Si, and SiO2 substrates.

Substrate interactions significantly affect the electronic structure of bismuthene.

Van der Waals forces and sublattice symmetry breaking are key factors in electronic modifications.

Abstract

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.