Study of the buckling effects on the electrical and optical properties of the group III-Nitride monolayers

TL;DR

This study investigates how buckling in group III-Nitride monolayers influences their electronic and optical properties, revealing that tuning buckling can control band gaps and optical responses for nanoscale optoelectronic applications.

Contribution

It demonstrates how planar buckling in group III-Nitride monolayers can be used to modulate their electronic and optical properties, providing a new way to design nanoscale optoelectronic devices.

Findings

Band gaps decrease with increasing buckling for certain monolayers.

Optical properties like dielectric function and refractive index are tunable via buckling.

Tuning buckling can both enhance and reduce optical responses.

Abstract

We consider electronic and optical properties of group III-Nitride monolayers using first-principle calculations. The group III-Nitride monolayers have flat hexagonal structures with almost zero planar buckling, $\Delta$. By tuning the $\Delta$, the strong $\sigma\text{-}\sigma$ bond through sp$^2$ hybridization of a flat form of these monolayers can be changed to a stronger $\sigma\text{-}\pi$ bond through sp$^3$ hybridization. Consequently, the band gaps of the monolayers are tuned due to a dislocation of the $s$- and $p$-orbitals towards the Fermi energy. The band gaps decrease with increasing $\Delta$ for those flat monolayers, which have a band gap greater than $1.0$ eV, while no noticeable change or a flat dispersion of the band gap is seen for the flat monolayers, that have a band gap less than $1.0$ eV. The decreased band gap causes a decrease in the excitation energy, and thus the static dielectric function, refractive index, and the optical conductivity are increased. In contrast, the flat band gap dispersion of few monolayers in the group III-Nitride induces a reduction in the static dielectric function, the refractive index, and the optical conductivity. We therefore confirm that tuning of the planar buckling can be used to control the physical properties of these monolayers, both for an enhancement and a reduction of the optical properties. These results are of interest for the design of optoelectric devices in nanoscale systems.