Significant interplay effect of silicon dopants on electronic properties in graphene

Using first-principles calculations, we have systematically studied the effects of the interplay between Si dopants in graphene. Four stable Si-pair doping configurations have been predicted and investigated. It is shown that the Si dopants tend to agglomerate in graphene. In particular, the band structures can be remarkably modulated by the doping sites of Si atoms in graphene. With the change of the Si–Si distance, the electronic structures can be widely tuned to exhibit isotropic, direction-dependent, and semiconducting properties. Based on this unique interplay effect, we reveal two ordered C–Si alloys, CSi and C3Si. It is found that CSi has an indirect band gap of 2.5 eV while C3Si still retains the Dirac features. Our results suggest that more remarkable electronic properties of graphene can be obtained by controllable tuning of the multi-doping of Si in graphene.