Tunable electronic structures in Type-II PtSe2/HfS2 van der Waals heterostructure by external electric field and strain

Abstract

Based on first-principles calculations, we investigate in detail the structural stability and electron-optical properties of monolayer PtSe 2 , HfS 2 , and two-dimensional (2D) PtSe 2 /HfS 2 van der Waals (vdW) heterostructure . The results show that 0.57eV indirect bandgap semiconductor and Type-II band alignment are formed at the PtSe 2 /HfS 2 vdW heterostructure, which greatly promotes the effective separation of photogenerated electrons and holes. It is worth mentioning that the heterostructure exhibits a wider light absorption range and a higher light absorption intensity. The band structure of the heterostructure can be changed significantly by applying an applied electric field, but the Type-II band alignment remains all the time, and the transition from semiconductor to metal occurs when the critical electric field is reached. In addition, the PtSe 2 /HfS 2 heterostructure changes from Type-II to Type-I band alignment under different biaxial strains, while the heterostructure keeps the Type-II band alignment under uniaxial strains , and changes from semiconductor to metal with the increase of strain. It is worth noting that the heterostructure is sensitive to compressive strain but insensitive to tensile strain , which provides theoretical guidance for photoelectric devices in specific environments. These results indicate that PtSe 2 /HfS 2 heterostructure will be widely used in photodetectors and nanodevices . • Effective carrier separation is realized in a novel PtSe 2 /HfS 2 vdW heterostructure. • The heterostructure shows different band alignment under biaxial and uniaxial strains. • The PtSe 2 /HfS 2 vdW heterostructure shows a prominent absorption coefficient of 10 5 cm −1 . • The PtSe 2 /HfS 2 vdW heterostructure is adequate for light-emitting diodes, lasers, and photodetectors.