Structures, Mobilities, and Electronic Properties of Functionalized Silicene: Superhalogen BO₂ Adsorption

The narrow band gap of silicene severely hinders its application in nanoelectronic devices. Therefore, it is significant to open the band gap of silicene and maintain its high carrier mobility. And for that, the adsorption of different coverage superhalogens BO₂ on the silicene surface have been investigated based on density functional theory and the CALYPSO method. The results show that BO₂ unit prefers to adsorb on silicene with adjacent mode irrespective of the size of substrate. The electronic structure analysis indicates that the density of states near the Fermi level are mainly contributed by Si-p and BO₂-p orbitals. (BO₂)-silicene exhibits metallic character with the exception of (BO₂)₂ adsorbed on 4 × 4 supercell. As for (BO₂)₂-silicene, silicene transforms from a gapless direct semiconductor to an indirect semiconductor. Furthermore, the effective electron mass of two BO₂ superhalogens on 4 × 4 silicene is estimated and found to be smaller than that of graphene. It is expected to result in higher electron mobility.