Tuning the electronic structures of silicene and germanene by biaxial strain and electric field

TL;DR

This study uses first-principles calculations to explore how biaxial strain and electric fields can tune the electronic and phonon properties of silicene and germanene, revealing significant shifts in band structures and potential for electronic property control.

Contribution

It provides new insights into the combined effects of mechanical strain and electric fields on silicene and germanene's electronic structures, demonstrating tunability for potential applications.

Findings

Biaxial strain shifts conduction bands towards the Fermi level.

Electric field induces a small band gap in silicene.

Strain enhances or mitigates the electric field-induced gap in silicene.

Abstract

We present a first-principles study of effects of small biaxial strain ($|\varepsilon|\le 5\%$) and perpendicular electric field (E-field) on the electronic and phonon properties of low-buckled silicene and germanene. With an increase of the biaxial strain, the conduction bands at the high symmetric $\Gamma$ and $M$ points of the first Brillouin zone shift significantly towards the Fermi level in both silicene and germanene. In contrast, the E-field changes the band dispersions near the $\Gamma$ and open a small band gap at the K point in silicene. We found that the field-induced gap opening in silicene could be enhanced by a compressive strain while mitigated by a tensile strain. This result highlights the tunability of the electronic structures of silicene by combining the mechanical strain and the electric field.