Vertical Dielectric of Conducting Functionalized Few-Layer MoS₂

In electrostatics, the electric field inside a classical conductor is zero because there are no free charges inside the conductor. Our first-principles linear response theory calculations found that conducting (metallic) one-side-hydrogenated MoS₂ with thin thickness exhibits dielectric screening behavior because it has electric polarization like a dielectric. Moreover, the screening of one-side-hydrogenated MoS₂ remained unchanged as the hydrogenated concentration varied. In contrast, metallic both-side-hydrogenated MoS₂ bilayers exhibit metallic screening behavior. We also showed that functionalized MoS₂ bilayers with -SH groups give consistent results with those of hydrogenated ones. Our results indicate that thin materials with small thicknesses can function as dielectrics, and functionalization can effectively adjust their dielectric constants in a manner similar to their distribution. This can be utilized for developing novel devices relying on dielectric screening.