Accurate electronic band gap of pure and functionalized graphane from GW calculations

TL;DR

This study uses GW calculations to accurately determine the electronic band gaps of pure and functionalized graphane, revealing direct gaps at the Gamma point and effects of functionalization on electronic structure.

Contribution

First GW-based analysis of graphane's electronic structure, including effects of functionalization and defects, providing precise band gap values.

Findings

Pure chair conformation has a 5.4 eV band gap.

Boat conformation has a 4.9 eV band gap.

Hydroxyl groups and vacancies modify electronic states.

Abstract

Using the GW approximation, we study the electronic structure of the recently synthesized hydrogenated graphene, named graphane. For both conformations, the minimum band gap is found to be direct at the $\Gamma$ point, and it has a value of 5.4 eV in the stable chair conformation, where H atoms attach C atoms alternatively on opposite sides of the two dimensional carbon network. In the meta-stable boat conformation the energy gap is 4.9 eV. Then, using a supercell approach, the electronic structure of graphane was modified by introducing either an hydroxyl group or an H vacancy. In this last case, an impurity state appears at about 2 eV above the valence band maximum.