Band Gap Engineering of Two-Dimensional Nitrogene

TL;DR

This study explores how the electronic properties of nitrogene, a two-dimensional nitrogen monolayer, can be tuned through stacking, strain, and electric fields, revealing potential for electronic device applications.

Contribution

It provides a comprehensive analysis of band gap engineering methods for nitrogene, including stacking, strain, and electric field effects, and discovers the transition to a Dirac semimetal state.

Findings

Band gap decreases with more layers.

Electric field can close the band gap at 0.35V/Å.

Strain induces Dirac points, transforming nitrogene into a Dirac semimetal.

Abstract

In our previous study, we have predicted the novel two-dimensional honeycomb monolayers of pnictogen. In particular, the structure and properties of the honeycomb monolayer of nitrogen, which we call nitrogene, are very unusual. In this paper, we make an in-depth investigation of its electronic structure. We find that the band structure of nitrogene can be engineered in several ways: controlling the stacking of monolayers, application of biaxial tensile strain, and application of perpendicular electric field. The band gap of nitrogene is found to decrease with the increasing number of layers. The perpendicular electric field can also reduce the band gap when it is larger than 0.18V/ {\AA}, and the gap closes at 0.35V/ {\AA}. A nearly linear dependence of the gap on the electric field is found during the process. Application of biaxial strain can decrease the band gap as well, and eventually closes the gap. After the gap-closing, we find six inequivalent Dirac points in the Brillouin zone under the strain between 17% and 28%, and the nitrogene monolayer becomes a Dirac semimetal. These findings suggest that the electronic structure of nitrogene can be modified by several techniques, which makes it a promising candidate for electronic devices.