Strain, electric-field and functionalization induced widely tunable electronic properties in MoS2/BC3 , /C3N and /C3N4 van der Waals heterostructures.

In this paper, the effect of BC3, C3N and C3N4 substrates on the atomic and electronic properties of MoS2 were systematically investigated using first-principles calculations. Our result shows that the MoS2/BC3 and MoS2/C3N4 heterostructures are a direct semiconductor with band gaps of 0.4 and 1.74 eV, respectively, while MoS2/C3N is a metal. Furthermore, we study the influence of strain and electric field on the electronic structure of these van der Waals heterostructures. The MoS2/BC3 heterostructure under -2% strain is a semiconductor with a direct band gap of 0.3 eV and under compressive strains larger than -4%, it transforms into a metal where the metallic character is maintained up to strains larger than -6%. The direct band gap decreases with increasing tensile strain to 0.35 eV (at +2%) and 0.3 eV (at +4%), 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/C3N 4 are modified and its band gap decreases as the electric field increases. The band gaps are calculated to be 1.3 eV (at +0.2 V/Å), 0.8 eV (at +0.4 V/Å), 0.4 eV (at +0.6 V/Å). Interestingly, the band gap reaches 30 meV at +0.8 V/Å, and with increasr to +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. The approaches of strain, electric field and hydrogenation are an effective way to tune the band gap and transition of electronic states through band gap control which could lead to potential applications in future nanoelectronic devices.