Adsorption of Hydrogen in Graphene without Band Gap Opening at the Dirac Point

TL;DR

This study demonstrates that hydrogen doping in graphene with specific periodicities does not open a band gap at the Dirac point, offering new possibilities for band gap engineering in graphene-based devices.

Contribution

The paper reveals that certain periodic hydrogen doping patterns in graphene do not induce a band gap at the Dirac point, confirmed by both tight-binding and DFT calculations.

Findings

No gap opens at the Dirac point for specific periodicities (NGPs).

Tiny gaps due to exchange effects are much smaller than gaps from other periodicities.

Results suggest new avenues for band gap engineering in graphene.

Abstract

The band gap of periodically-doped graphene with hydrogen is investigated. It is found through a tight-binding model (TB) that for certain periodicities, called here NGPs (non-gap periodicities), no gap is opened at the Dirac point. This result is confirmed by Density Functional Theory (DFT) calculations. DFT results show that a tiny gap is opened for NGPs due to exchange effects, not taken into account in the TB model. However, this tiny gap is one or two orders of magnitude smaller than the gap opened for other periodicities different from NGPs. This finding opens up a new path for band gap engineering experiments in graphene.