Local Reconstructions of Silicene Induced by Adatoms

Abstract

The interaction of silicene with Si, C, H, O, Ti atoms along with H${}_2$, H${}_2$O and O${}_2$ molecules are investigated and the induced functionalities thereof are analyzed using first principles density functional theory. Si adatom initially adsorbed at the top site of silicene pushes down the Si atom underneath to form a dumbbell like structure with 3+1 coordination. This prediction is important for silicene research and reveal new physical phenomena related with the formation of multilayer Si, which is apparently the precursor state for missing layered structure of silicon. We found that dumbbell structure attributes coverage dependent electronic and magnetic properties to nonmagnetic bare silicene. Even more interesting is that silicene with dumbbells is energetically more favorable than the pristine silicene: The more dense the dumbbell coverage, the stronger is the cohesion. Incidentally, these structures appear to be intermediate between between silicene and silicon. Carbon adatom, which is initially adsorbed to the bridge position, substitutes one Si atom, if it overcomes a small energy barrier. Oxygen molecule can dissociate on silicene surface, whereby constituent oxygen atoms oxidize silicene by forming strong bonds. By varying the concentration and decoration of carbon, hydrogen and oxygen atoms one can tune the band gap of silicene. Through the adsorption of hydrogen or titanium adatom, silicene acquires spin polarized state. A half metallic ferromagnetic behavior is attained at specific uniform coverage of Ti adatom, which may function as a spin valve.

Accepted for publication in The Journal of Physical Chemistry http://pubs.acs.org/doi/abs/10.1021/jp408647t

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Cited by in corpus (10)

• Large Enhancement and Tunable Band Gap in Silicene by Small Organic Molecule Adsorption
• The atomic structure of the $\sqrt{3}\times \sqrt{3}$ phase of silicene on Ag(111)
• Stable single-layer honeycomb like structure of silica
• Effects of extrinsic point defects in phosphorene: B, C, N, O and F Adatoms
• Silicite: the layered allotrope of silicon
• New Phases of Germanene
• Adsorption of Group-IV Elements on Graphene, Silicene, Germanene, Stanene: Dumbbell Formation
• Diverse forms of $\sigma$ bonding in two-dimensional Si allotropes: Nematic orbitals in the $Mo{S}_2$ structure
• Topological phase in oxidized zigzag stanene nanoribbons
• π-Conjugation in Epitaxial Si(111)-($\sqrt{3}$$\times$$\sqrt{3}$) Surface: an Unconventional "Bamboo Hat" Bonding Geometry for Si