Van der Waals heterostructures of MoS2and Janus MoSSe monolayers on graphitic boron-carbon-nitride (BC3,C3N,C3N4andC4N3) nanosheets: a first-principles study

In this work, we extensively investigate the structural and electronic properties of van der Waals heterostructures (HTs) constructed by MoS${_2}$/$BC_{3}$, MoS${_2}$/$C_{3}N$, MoS${_2}$/$C_{3}N_{4}$, MoS${_2}$/$C_{4}N_{3}$ and those using Janus MoSSe instead of MoS$_2$ by performing density functional theory calculations. The electronic band structure calculations and the corresponding partial density of states reveal that the significant changes are driven by quite strong layer-layer interaction between the constitutive layers. Our results show that although all monolayers are semiconductors as free-standing layers, the MoS${_2}$/$C_{3}N$ and MoS${_2}$/$C_{4}N_{3}$ bilayer HTs display metallic behavior as a consequence of transfer of charge carriers between two constituent layers. In addition, it is found that in MoSSe/$C_{3}N$ bilayer HT, the degree of metallicity is affected by the interface chalcogen atom type when Se atoms are facing to $C_{3}N$ layer, the overlap of the bands around the Fermi level is smaller. Moreover, the half-metallic magnetic $C_{4}N_{3}$ is shown to form magnetic half-metallic trilayer HT with MoS$_2$ independent of the stacking sequence, i.e. whether it is sandwiched or two $C_{4}N_{3}$ layer encapsulate MoS$_2$ layer. We further analyze the trilayer HTs in which MoS$_2$ is encapsulated by two different monolayers and it is revealed that at least with one magnetic monolayer, it is possible to construct a magnetic trilayer. While the trilayer of $C_{4}N_{3}$/MoS${_2}$/$BC_{3}$ and $C_{4}N_{3}$/MoS${_2}$/$C_{3}N_{4}$ exhibit half-metallic characteristics, $C_{4}N_{3}$/MoS${_2}$/$C_{3}$N possesses a magnetic metallic ground state. Overall, our results reveal that holly structures of BCN crystals are suitable for heterostructure formation even over van der Waals type interaction which significantly changes electronic nature of the constituent layers.