Analysis of band gap formation in graphene by Si impurities: Local bonding interaction rules

We report band gap formation in graphene by using bonding interactions with Si impurities in the form of Si cluster (Sin). We demonstrate that neither the distortion in graphene nor the periodicity of the adsorption can lead to band gap opening. The calculated band gap for Si2 is 0.83 eV at Dirac points and the effect of this Si–C interaction is maintained even when the cluster size is increased. However, there is a strong dependence of the size of the band gap on the size of the Sin. Analysis of the trend points to the change in the dispersion of the gap states due to the change in the Si–C bond.