Electronic Structure and Quasiparticle Band Gap of Silicene Structures

TL;DR

This study uses first-principles calculations to analyze various silicene structures, revealing their electronic properties, including band gaps and Fermi velocity renormalization, with implications for electronic applications.

Contribution

It provides the first-principles analysis of multiple silicene structures, identifying their electronic nature and explaining experimental measurements with detailed quasiparticle gap calculations.

Findings

Planar and buckled silicenes are zero-gap semimetals with renormalized Fermi velocity.

Two other silicene structures are gapped semiconductors with tunable band gaps.

Calculated quasiparticle gaps match recent photoemission spectroscopy data.

Abstract

We report first-principles results on the electronic structure of various silicene structures. For planar and simply buckled silicenes, we confirm their zero-gap nature and show a significant renormalization of their Fermi velocity by including many-electron effects. However, the other two recently proposed silicene structures exhibit a finite band gap, indicating that they are gapped semiconductors instead of previously expected Dirac-fermion semimetals. Moreover, our calculated quasiparticle gap quantitatively explains the recent angle-resolved photoemission spectroscopy measurements. In particular, the band gap of the latter two structures can be tuned in a wide range by applying strain, giving hope to bipolar-devices applications.