Band alignment in carbon-based one-dimensional van der Waals heterostructures

Abstract

Various studies are concentrated on the band alignment in van der Waals heterostructures (vdWhs). In this paper, the density functional theory method is employed to investigate the electronic structures of carbon-based one-dimensional (1D) vdWhs under axial strain and an external electric field. It is found that the type-II and type-Ⅲ band alignment appear in carbon nanotubes (CNTs)/graphene nanoribbons (GNRs) 1D vdWhs with different diameters. Furthermore, it is shown that the CNTs/GNRs 1D vdWhs band alignment can change from type-II to type-I at 0.4 V/Å, while the band gaps are closed at 0.9 V/Å. Besides, it is discovered that type-Ⅲ to type-Ⅱ and type-Ⅱ to type-Ⅰ band alignment transitions can appear under the axial strain of −3% and 3 %, respectively. These discoveries indicate theoretically that the axial strain and the external electric field can turn the band alignment of CNTs/GNRs 1D vdWhs. • The electronic structure of CNTs/GNRs 1D vdWhs in response to external electric field and axial strain were presented. • The band alignment of the CNTs/GNRs changed from type-II to type-I at 0.4 V/Å and the band gaps are closed at 0.9 V/Å. • The band alignment of the CNTs/GNRs changed from type-Ⅱ to type-Ⅰ and type-Ⅲ to type-Ⅱ under the strain of 3 % and −3%.