Strain-Robust and Electric Field Tunable Band Alignments in van der Waals WSe2–Graphene Heterojunctions

Abstract

We study the band alignments and band structures of van der Waals WSe2–graphene heterojunctions by varying out-of-plane external electric field and in-plane mechanical strain using density-functional calculations. We find that the electronic properties of WSe2–graphene heterojunctions are insensitive to the change of the mechanical strain, showing strong robustness. However, the external electrical field intensity is able to significantly change the band alignments of WSe2–graphene heterojunctions, while a constant band gap value of WSe2 in the heterojunctions is nearly maintained. We further show that the highest hole concentration injected by the external electric field is estimated as high as 6.40 × 1012 cm–2, while the highest electron density is about 3.00 × 1012 cm–2. These findings suggest that the WSe2–graphene heterojunctions are a promising structure instrumental for electronic device applications.