Curvature-controlled band alignment transition in 1D van der Waals heterostructures
Shu Zhao, Chunxia Yang, Ziye Zhu, Xiaoping Yao, Wenbin Li
Abstract
Abstract The effect of curvature on the band alignment of one-dimensional (1D) van der Waals (vdW) transition metal dichalcogenide (TMDC) heterostructures is studied by comprehensive first-principles calculations. We find that, as the diameter of a TMDC nanotube decreases, the combined effect of curvature-induced flexoelectricity and circumferential tensile strain causes a rapid lowering of the conduction band minimum, whereas the valence band maximum exhibits an initial lowering before rising. As individual TMDC nanotubes form coaxial heterostructures, the concerted effect of diameter-dependent band-edge levels and intertube coupling via flexovoltage can result in a transition of intertube band alignment from Type II to Type I in multiple heterostructural systems, including large-diameter MoSe 2 @WS 2 , MoTe 2 @MoSe 2 , and MoTe 2 @WS 2 heterostructures. These results lay down a foundation for the rational design of 1D vdW heterostructures.