Ab Initio Modeling of the Electronic and Energy Structure and Opening the Band Gap of a 4 p -Element-Doped Graphene Mono
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nitio Modeling of the Electronic and Energy Structure and Opening the Band Gap of a 4p-Element-Doped Graphene Monolayer M. M. Asadova, *, S. S. Guseinovab, and V. F. Lukichevc, ** aInstitute
of Catalysis and Inorganic Chemistry, National Academy of Sciences of Azerbaijan, Baku, AZ-1143 Azerbaijan b Institute of Physics, National Academy of Sciences of Azerbaijan, Baku, AZ-1143 Azerbaijan c Valiev Institute of Physics and Technology, Russian Academy of Sciences, Moscow, 117218 Russia *e-mail: [email protected] **e-mail: [email protected] Received April 20, 2020; revised April 20, 2020; accepted April 20, 2020
Abstract—In this paper, we study the electronic and band structure of 4p-elements (M = Ge, Si)-doped graphene nanosheets with vacancies by the density functional theory method. The adsorption energy of the doping atoms and the relative stability of doped graphene monolayers are estimated. An antiferromagnetic ordering is discovered in these graphene-based systems. Based on the analysis of the electronic populations of atomic orbitals according to Mulliken, the states’ densities in graphene systems are calculated. The equilibrium parameters of the electronic structure of graphene nanosheets are obtained. The regularities of changes in the electronic structure of the valence band and the induction of an energy gap in M-doped graphene monolayers containing vacancies are studied. The features of the electronic structure near the Fermi level, as well as the role of the structural effect in opening the energy gap in graphene–M systems, are discussed. Doping with 4p elements opens the energy gap in graphene–Ge(Si) systems. The local magnetic moments for antiferromagnetic ordering are estimated on carbon atoms of graphene nanosheets including Ge(Si). The calculated values of the local magnetic moments on carbon atoms in graphene–M (Ge, Si) systems are comparable with each other. Keywords: Ab initio modeling, electronic and band structure, graphene monolayers, doping with 4p elements, magnetic moments, electronic properties DOI: 10.1134/S1063739720050030
INTRODUCTION The transformation of the microstructure into the state of the nanostructure can lead to noticeable changes in the physical properties of 2D materials [1– 3]. An increase in the surface-to-volume ratio and transfer of a particle to the region with quantum effects are the main factors for changing the physical characteristics of 2D materials [4, 5], in particular graphene [6, 7]. Graphene consists of an infinite two-dimensional system of carbon atoms located in the corners of regular hexagons. Graphenes consist of atomic planes joined by van der Waals forces, where the carbon atoms are in the state of sp2 hybridization. Graphene is intensively studied [8–14], in particular, with the aim of finding the possibility of replacing silicon by carbon in the elemental base of micro- and nanoelectronics [8]. However, pure graphene is of little use for the needs of semiconductor technology, which is related to the zero density of the states at the Fermi level and t
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