Electrically Tunable Band Gap in Silicene

TL;DR

This paper investigates how an external electric field can tune the electronic properties of silicene, revealing a controllable band gap and phase transitions relevant for electronic applications.

Contribution

It provides first-principles calculations showing electric field-induced band gap tuning and phase transitions in silicene, a novel 2D material.

Findings

Electric field induces a tunable band gap in silicene.

High polarizability suppresses the band gap by about eight times.

Transition from topological to band insulator occurs at low electric fields.

Abstract

We report calculations of the electronic structure of silicene and the stability of its weakly buckled honeycomb lattice in an external electric field oriented perpendicular to the monolayer of Si atoms. We find that the electric field produces a tunable band gap in the Dirac-type electronic spectrum, the gap being suppressed by a factor of about eight by the high polarizability of the system. At low electric fields, the interplay between this tunable band gap, which is specific to electrons on a honeycomb lattice, and the Kane-Mele spin-orbit coupling induces a transition from a topological to a band insulator, whereas at much higher electric fields silicene becomes a semimetal.