Two-dimensional lateral IV-ene heterostructures for innovative topological devices.

Silicene, germanene and stanene, three honeycomb two-dimensional (2D) lattices constituted by Si, Ge, and Sn, respectively, are predicted to be topological insulators and to present an electronic bandgap in correspondence to Dirac's cone. Recently, the lateral growth of pseudomorphic germanene/stanene junctions has been experimentally achieved triggering further interest on these materials. Within the framework of the density functional theory, by plane wave pseudopotential techniques we computed the band offset of lateral heterostructures composed of silicene/germanene and germanene/stanene nanoribbons, thus forming 2D layers. We simulated the structural properties and the microscopic mechanisms responsible of the dependence of the band-offset on the orientation of the heterojunction. We enlightened the electronic properties governing the band alignment of H functionalized heterojunctions to design 2D heterostructures with tunable band-offset to be used as building block in forthcoming electronic devices based on 2D materials. The study of quantum confinement and topological effects complete the work.