Strain, electric-field and functionalization induced widely tunable electronic properties in MoS2/BC 3, /C 3 N and /$C_{3}N_{4}$ van der Waals heterostructures

In this paper, the effect of BC3, C3N and substrates on the atomic and electronic properties of MoS2 were systematically investigated using first-principles calculations. Our results show that the MoS2/BC3 and MoS2/C3N4 heterostructures are direct semiconductors with band gaps of 0.4 and 1.74 eV, respectively, while MoS2/C3N is a metal. Furthermore, the influence of strain and electric field on the electronic structure of these van der Waals heterostructures is investigated. The MoS2/BC3 heterostructure, for strains larger than −4%, transforms it into a metal where the metallic character is maintained for strains larger than −6%. The band gap decreases with increasing strain to 0.35 eV (at +2%), while for strain (>+6%) a direct-indirect band gap transition is predicted to occur. For the MoS2/C3N heterostructure, the metallic character persists for all strains considered. On applying an electric field, the electronic properties of MoS2/C3N4 are modified and its band gap decreases as the electric field increases. Interestingly, the band gap reaches 30 meV at +0.8 V/Å, and with increase above +0.8 V/Å, a semiconductor-to-metal transition occurs. Furthermore, we investigated effects of semi- and full-hydrogenation of MoS2/C3N and we found that it leads to a metallic and semiconducting character, respectively.