Abstract
Based on the first-principles calculations, we have investigated in detail the bandgap opening of silicene nanomeshes. Different to the mechanism of bandgap opening induced by the sublattice equivalence breaking, the method of degenerate perturbation through breaking the bond symmetry could split the π-like bands in the inversion symmetry preserved silicene nanomeshes, resulting into the πa1 − πa2 and πz1 − πz2 band sets with sizable energy intervals. Besides the bandgap opening in the nanomeshes with Dirac point being folded to Γ point, the split energy intervals are however apart away from Fermi level to leave the semimetal nature unchanged for the other nanomeshes with Dirac points located at opposite sides of Γ point as opposite pseudo spin wave valleys. A mass bandgap could be then opened at the aid of uniaxial strain to transfer the nanomesh to be semiconducting, whose width could be continuously enlarged until reaching its maximum Emax. Moreover, the Emax could also be tuned by controlling the defect density in silicene nanomeshes. These studies could contribute to the understanding of the bandgap engineering of silicene-based nanomaterials to call for further investigations on both theory and experiment.
Highlights
Based on the first-principles calculations, we have investigated in detail the bandgap opening of silicene nanomeshes
In Berdiyorov et al.’s studies[16], the effects of vacancy defect on the thermal stability of silicene has been investigated with molecular dynamics method
A recent experimental study[17] has shown the presence of a large number of defect clusters which has recently been carefully investigated by Li et al.[18] with ab initio molecular dynamics simulations
Summary
Based on the first-principles calculations, we have investigated in detail the bandgap opening of silicene nanomeshes. A bandgap engineering mechanism–degenerate perturbation which is different to the sublattice equivalence breaking has been proposed This phenomena could be seen in a recent experimental study on the fabricating of silicene on ZrB2(0001) surface[6], where the periodic pattern of interaction between silicene and substrate modulates the boundary conditions of silicene. A kind of nanomeshes with Dirac cone being folded to Γ to form four-fold degeneracy could be opened a bandgap by the degenerate perturbation through introducing an inversion symmetry preserved antidot in the repeated unit. Such antidot would not change the semimetal nature of the other nanomeshes which are still less of investigations. We would show that such band splitting can transfer the nanomesh to be semiconducting at the aid of strain
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