Distortion and electric-field control of the band structure of silicene

Abstract

Density functional theory with local density approximation for exchange and correlation functional is used to tune the electronic band structure of silicene monolayer. The cohesive energy of the free-standing monolayer increases (decreases) with the external electric field (distortion). Electrons in silicene behave like Dirac fermions, when the bond angle between the Si atoms is larger than . Large distortions destroy the electronic structure of silicene so that it is no longer a semi-metallic material, and the distorted silicene acts like an n-doped system. The electric field opens a band gap around the K-point in the Brillouin zone, which increases with electric field. The bond angle between the Si atoms is a key player to determine the presence or absence of Dirac cones in silicene.