Electronic properties of twisted Sb/WTe2 van der Waals heterostructure with controllable band gap, band alignment, and spin splitting

Two-dimensional van der Waals heterostructures (vdWHs) have been extensively studied for their excellent physical characteristics. In this paper, two twisted $\mathrm{Sb}/\mathrm{W}{\mathrm{Te}}_{2}$ vdWHs are respectively constructed by stacking of Sb and $\mathrm{W}{\mathrm{Te}}_{2}$ monolayers with different interlayer rotation angles, and their electronic properties are studied by first-principles calculation. Firstly, the effects of spin-orbit coupling on the electronic structure of $\mathrm{Sb}/\mathrm{W}{\mathrm{Te}}_{2}$ vdWHs, such as band gap and band alignment, are addressed in detail. Furthermore, for the $\mathrm{Sb}/\mathrm{W}{\mathrm{Te}}_{2}$ vdWH with an interlayer rotation angle of ${30}^{\ensuremath{\circ}}$, its band gap, band alignment, and spin splitting are investigated by adjusting the external electric field, biaxial strain, and interlayer coupling, respectively. Under an applied external electric field, the band structure of the $\mathrm{Sb}/\mathrm{W}{\mathrm{Te}}_{2}$ vdWH undergoes a transition from a direct band gap to an indirect band gap, and a semiconductor-metal transition occurs at $\ifmmode\pm\else\textpm\fi{}0.7\phantom{\rule{0.16em}{0ex}}\mathrm{V}/\AA{}$ along with the transition of types I, II, and III band alignments. Similarly, the band gap and band alignment of the $\mathrm{Sb}/\mathrm{W}{\mathrm{Te}}_{2}$ vdWH can also be modulated by biaxial strain and interlayer coupling. In addition, the calculated electronic structure present that the Rashba- and Zeeman-type spin splitting are dependent on the external electric field, biaxial strain, and interlayer coupling. Thus, the controllable electronic properties of $\mathrm{Sb}/\mathrm{W}{\mathrm{Te}}_{2}$ vdWHs have great application potential for spintronic and optoelectronic devices.