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Register a new userSuperlattice Structures of Graphene based Nanoribbons
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Based on first-principles calculations we predict that periodically repeated junctions of armchair graphene nanoribbons of different widths form superlattice structures. In these superlattice heterostructures the width and the energy gap are modulated in real space and specific states are confined in certain segments. Orientation of constituent nanoribbons, their width and length, the symmetry of the junction are the structural parameters to engineer electronic properties of these quantum structures. Not only the size modulation, but also composition modulation, such as periodically repeated, commensurate heterojunctions of BN and graphene honeycomb nanoribbons result in a multiple quantum well structure. We showed that these graphene based quantum structures can introduce novel concepts to design nanodevices.
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We consider the gapped graphene superlattice (SL) constructed in accordance with the Fibonacci rule. Quasi-periodic modulation is due to the difference in the values of the energy gap in different SL elements. It is shown that the effective splitting of the allowed bands and thereby forming a series of gaps is realized under the normal incidence of electrons on the SL as well as under oblique incidence. Energy spectra reveal periodical character on the whole energy scale. The splitting of allowed bands is subjected to the inflation Fibonacci rule. The gap associated with the new Dirac point is formed in every Fibonacci generation. The location of this gap is robust against the change in the SL period but at the same time it is sensitive to the ratio of barrier and well widths; also it is weakly dependent on values of the mass term in the Hamiltonian.
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