Natural charge spatial separation and quantum confinement of ZnO/GaN core/shell nanowires

We performed density-functional calculations to investigate the electronic structure of ZnO/GaN core/shell heterostructured nanowires (NWs) orientating along direction. The build-in electric filed arising from the charge redistribution at the {1-100} interfaces and the band offsets were revealed. ZnO-core/GaN-shell NWs rather than GaN-core/ZnO-shell ones were predicted to exhibit natural charge spatial separation behaviors, which are understandable in terms of an effective mass model. The effects of quantum confinement on the band gaps and band offsets were also discussed.Comment: 3 pages, 3 figure

Phagraphene: A Low-energy Graphene Allotrope composed of 5-6-7 Carbon Rings with Distorted Dirac Cones

Using systematic evolutionary structure searching we propose a new carbon allotrope, phagraphene, standing for penta-hexa-hepta-graphene, because the structure is composed of 5-6-7 carbon rings. This two-dimensional (2D) carbon structure is lower in energy than most of the predicted 2D carbon allotropes due to its sp2-hybridization and density of atomic packing comparable to graphene. More interestingly, the electronic structure of phagraphene has distorted Dirac cones. The direction-dependent cones are further proved to be robust against external strain with tunable Fermi velocities.Comment: 5 pages, 3 figure