Study On The Impacts On The Electronic Structure Of Bi, Se,Te Adsorption On N/p Type Graphene

Graphene is an important kind of materials for research in materials science and condensed-matterphysics, for its numerous unique properties, such as spin orbit coupling effect, anomalous quantum halleffect, high electron mobility, zero band gap semiconductor features and the sub-lattice symmetry, and soon. Graphene will be good candidate for the next generation electronic materials, because of theseproperties. It has been widely applied in many fields. For example, electronic equipment, catalysis, gassensor and so on. Topological insulator is a new substance which has strong spin orbit coupling effect. It isdifferent from traditional semiconductor or insulator. It has attracted extensive attention due to inherentspecial properties. Graphene and topological insulators have many characteristics in common. They areboth Dirac material, have edge states on zero energy level and spin orbit coupling effect, and so on. Thereare many experiments of have successfully grown topological insulator Bi2Se3/Bi2Te3thin films ondouble-layer graphene by molecular beam epitaxy.Based on first-principles calculations, combined with supercell model, pseudo potential and the VASPpackage, the configurations, electronic and magnetic properties of Bi, Se or Te adsorption on the perfectand defects graphene are studied in this article, we have obtained some meaningful results. We hope theresearch results will provide theoretical reference for the experiment and preparation of spintronic devices.1. The research of Bi, Se or Te adsorption on perfect and single defects grapheneThe stable configurations of Bi, Se or Te adsorption on perfect and single defects graphene are studied.The results show that stable configurations for Bi and Se adsorption in energy, but the one of Te is notenergy preferred. There are C atoms suspended bonds at the vacancy of single defect graphene, and theformation energy of Bi, Se and Te adsorbed at the single vacancy is much bigger than those on the perfectgraphene. Then through analyzing density of states, we found that magnetic moment was not observedamong all the systems studied except the Bi adsorption on perfect graphene. We also found that Biadsorption on single defects graphene system have two symmetrical peak at the Fermi level. At last, theelectronic density and charge density difference are further studied.2. The study on Bi, Se or Te adsorption on B-doping and N-doping graphene The related systems of n-type doping and p-type doping graphene materials played an important rolein the development of electronic devices. B doped graphene is p-type doping, N doped graphene is n-typedoping, and the configurations remain almost unchanged after doping, so we study the effects of Bi, Se orTe adsorption on B/N-doping graphene. The study results show that magnetic moment was observed amongall the systems studied except the Se adsorped B-doped graphene system. The Fermi level of Se on theN-doped graphene system moved from the conduction band to the valence band. The one of Bi on theB-doped graphene system moved from the valence band to the band gap. In order to reveal thecircumstance of electron transfer, the electronic density and charge density difference are further studied.In all the systems studied, Se atom has the strongest adsorption than Bi and Te atom. The defects ofsingle defect, B doping and N doping enhanced interactions between Bi/Se/Te and graphene, the effectorder from strong to weak is single defect system, B doping system, N doping system. Compare to thedefects, Bi, Se and Te adsorptions on the perfect graphene have smaller affects.