  Hydrogenation has proven to be an effective tool to open the bandgap of
graphene. In the present density functional study we demonstrate that
single-side-hydrogenated graphene is a semiconductor with an indirect bandgap
of 1.89 eV, in between the gapless graphene and wide bandgap graphane. We show
that its electronic structure and lattice characteristics are substantially
different from those of graphene, graphone, or graphane. The lattice parameter
and C-C bond length are found to be lengthened by 15% of those of graphene. Our
binding energy analysis confirms that such a single sided hydrogenation leads
to thermodynamically stable material.
