Large Nontrivial Topological Band Gap in Heterostructure of Fluorine-Functionalized Bismuthene and h-BN Substrate: A First Principles Study

Two dimensional topological insulators (2D TIs) are well-known as one of the most prominent and interesting materials in condensed matter physics and also nanoelectronics. Time Reversal Symmetry (TRS) protected helical edge states, dissipationless charge transport, spin-momentum locked carriers and other properties, provoked the employment of 2D TIs in several applications such as electronics, spintronics, topological quantum computation and superconductivity. In order to have a high temperature practical transport application, a substrate is required, which stabilizes the 2D TI, while at the same time keeps the nontrivial topological behavior untouched with a sizable band gap. Based on first principles calculations, we studied the interface of two-sided fluorine-functionalized bismuthene (2D BiF) 2D TI and h-BN substrate, in a van der Walls heterostructure. Our results indicate that the optimized heterostructure has a large nontrivial band gap of about 0.87 eV. This structure can be considered as a promising candidate for room temperature low dissipation spintronic applications.