Origin of band bending at domain boundaries of MoS₂: First-principles study

Using first-principles calculations based on density functional theory, the energetics and electronic structure of domain boundaries of MoS₂, in which the same polar edges face each other, are investigated. We find that the interface model with homoelemental bonds is not energetically preferred in this system. The domain boundaries have defect levels that have wide distributions inside the band gap of MoS₂. The upshift (or downshift) of the MoS₂ energy band occurs around the domain boundaries when the occupation number of electrons in the defect levels increases (or decreases). The charge transfer of electrons from the graphite substrate plays an important role in band bending, which is observed in the recent experiments by scanning tunneling microscopy/spectroscopy.