GRAPHENE NANORIBBONS TRANSPORT PROPERTIES CALCULATION

Graphene, a two-dimensional sheet of sp(2)-bonded carbon arranged in a honeycomb lattice, is a potential candidate for use in future nanodevices. The lateral confinement of the two-dimensional electron gas in graphene nanoribbons (GNR) can tune their electrical properties. We performed density-functional theory (DFT) based calculations to obtain electronic structure of both zig-zag and armchair GNRs with lateral constrictions. The spin-dependent exchange-correlation potential is approximated within the generalized gradient approximation using the QuantumWise toolkit ATK, which employs local numerical double-zeta polarized basis orbitals. The spin-dependent transport properties of the electrode-device-electrode geometry were calculated by means of non-equilibrium Green's function formalism as implemented in ATK. Band structures calculated by the DFT were compared with results of the semi-empirical method (Extended Huckel model). Our results show that GNRs with the constrictions exhibit novel transport properties. The horizontal layout of the GNR constrictions determines main features important for electrical and spintronic applications of these structures. The constrictions could be realized by means of local anodic oxidation using scanning probe microscope.