Strain Engineering of Adsorbate Self-Assembly on Graphene for Band Gap Tuning

Recent
interest in functionalized graphene has been motivated by
the prospect of creating a two-dimensional semiconductor with a tunable
band gap. Various approaches to band gap engineering have been made
over the last decade, one of which is chemical functionalization.
In this work, a predictive physical model of the self-assembly of
halogenated carbene layers on graphene is suggested. Self-assembly
of the adsorbed layer is found to be governed by a combination of
the curvature of the graphene sheet, local distortions, as introduced
by molecular adsorption, and short-range intermolecular repulsion.
The thermodynamics of bidental covalent molecular adsorption and the
resultant electronic structure are computed using density functional
theory. It is predicted that a direct band gap is opened that is tunable
by varying coverages and is dependent on the ripple amplitude. This
provides a mechanism for the controlled engineering of graphene’s
electronic structure and thus its use in semiconductor technologies.