Strain-engineered electronic and topological properties of bismuthene on SiC(0001) substrate

Abstract

By combining density functional theory with low-energy effective Hamiltonian, we demonstrate strain-engineered electronic and topological properties of the recently synthesized two-dimensional (2D) bismuthene on SiC(0001) substrate. As bismuthene on SiC(0001) exhibits an indirect gap of 0.62 eV with nontrivial topology, we show that the band gap size can be further increased by an applied tensile strain, which follows a nearly linear fashion. Especially, with a tensile strain of 7%, the topological gap can be enhanced to an unprecedented value of 0.83 eV, originating from the different deformation potentials of the conduction band minimum principally contributed from p orbitals of Bi and valance band maximum from the hybridized states of Bi overlayer and SiC substrate. Moreover, we discuss the strength of spin–orbit coupling, in additional to the strain effect, in tuning the electronic structures and topological edge states. Our results suggest the promise of strain engineering in manipulating large-gap quantum spin Hall states on conventional semiconductor for practical dissipationless electronic transport and quantum information processing.

Nearly perfect spin-filtering in curved two-dimensional topological insulators

“…However, it has been well established both theoretically and experimentally that the Rashba term, although large, is not sufficient to close the topological gap in planar bismuthene on SiC. [11][12][13][14][15][16][17][18][19] Since the Rashba effect has a similar origin (the Bi-Si interaction) in our model system as in the planar bismuthene on SiC, it is reasonable to expect the Rashba effect not to close the topological gap in the present system either.…”

“…Recent theoretical and experimental work has provided strong evidence that monolayer bismuthene on SiC is a wide gap 2DTI. [11][12][13][14][15][16][17][18][19] Tight binding models of the bismuthene monolayer employing basis sets consisting only of the valence orbitals of the bismuth atoms but parameterized so as to take into account the influence of the SiC substrate on the bismuthene have been constructed. [12][13][14][15][16][17][18] These simple models have succeeded in capturing the essential topological insulator and QSH physics of this planar system.…”

“…[11][12][13][14][15][16][17][18][19] Tight binding models of the bismuthene monolayer employing basis sets consisting only of the valence orbitals of the bismuth atoms but parameterized so as to take into account the influence of the SiC substrate on the bismuthene have been constructed. [12][13][14][15][16][17][18] These simple models have succeeded in capturing the essential topological insulator and QSH physics of this planar system. [12][13][14][15][16][17][18] Whether curved bismuthene monolayers chemically modified by suitable adsorbates can also exhibit topological insulator and QSH physics is unknown at present.…”

“…[12][13][14][15][16][17][18] These simple models have succeeded in capturing the essential topological insulator and QSH physics of this planar system. [12][13][14][15][16][17][18] Whether curved bismuthene monolayers chemically modified by suitable adsorbates can also exhibit topological insulator and QSH physics is unknown at present. However, theoretical studies have suggested that approximately spherical and cylindrical bismuthene nanostructures may be stable.…”

Metallenes: Recent Advances and Opportunities in Energy Storage and Conversion Applications

“…Moreover, the tunable band gap expands the use of pnictogen metallenes. To meet the different application demands, the electronic structure could be elegantly adjusted by doping, stress, defects, electric field, heterostructures, and other strategies.…”