Janus Type Monolayers of S-MoSiN(2) Family and Van Der Waals Heterostructures with Graphene: DFT-Based Study

Novel representative 2D materials of the Janus type family X-M-ZN [Formula: see text] are studied. These materials are hybrids of a transition metal dichalcogenide and a material from the MoSi [Formula: see text] N [Formula: see text] family, and they were constructed and optimized from the MoSi [Formula: see text] N [Formula: see text] monolayer by the substitution of SiN [Formula: see text] group on one side by chalcogen atoms (sulfur, selenium, or tellurium), and possibly replacing molybdenum (Mo) to tungsten (W) and/or silicon (Si) to germanium (Ge). The stability of novel materials is evaluated by calculating phonon spectra and binding energies. Mechanical, electronic, and optical characteristics are calculated by methods based on the density functional theory. All considered 2D materials are semiconductors with a substantial bandgap (>1 eV). The mirror symmetry breaking is the cause of a significant built-in electric field and intrinsic dipole moment. The spin–orbit coupling (SOC) is estimated by calculations of SOC polarized bandstructures for four most stable X-M-ZN [Formula: see text] structures. The possible van der Waals heterostructures of considered Janus type monolayers with graphene are constructed and optimized. It is demonstrated that monolayers can serve as outer plates in conducting layers (with graphene) for shielding a constant external electric field.