Electronic properties, contact types and Rashba splitting of two-dimensional graphyne/WSeTe van der Waals heterostructures

Abstract

Recently, graphyne has shown great promise in nanoelectric and spintronic devices, which has attracted much attention. For improving its application, graphyne/WSeTe heterostructures are investigated systematically in this work. The electronic structure and Rashba splitting of graphyne/WSeTe heterostructures are calculated by density functional theory. In graphyne/WSeTe heterostructures, the contact types (such as Ohmic or Schottky contact) can be affected by different stacking patterns. Graphyne/TeWSe heterostructures possess Ohmic contact. However, Graphyne/SeWTe heterostructures have Schottky contact and a type-II band arrangement, which is beneficial to the separation of electron-hole pairs and the conversion of solar energy. Without considering spin-orbit coupling, the direct-indirect band gap transition appears in graphyne/WSeTe heterostructures by changing electric field and interlayer distance. The Schottky barrier and contact types in graphyne/WSeTe heterostructures are easier to be adjusted by vertical electric field. As the electric field changes from −0.2 to 0.2 V/Å, the Schottky contact of graphyne/SeWTe heterostructures turns into Ohmic contact. Meanwhile, the Rashba spin splitting appears in graphyne/WSeTe heterostructures, which can be significantly enhanced by electric field. The electric dipole moment of Janus WSeTe monolayer is also enhanced by covering graphyne. These results can provide a good guidance for the applications of graphyne/WSeTe heterostructures in spintronic devices.