Coulomb screening and scattering in atomically thin transistors across dimensional crossover
Layered two-dimensional dichalcogenides are potential candidates for post-silicon electronics. Here, we report insightfully experimental and theoretical studies on the fundamental Coulomb screening and scattering effects in these correlated systems, in response to the changes of three crucial Coulomb factors, including electric permittivity, interaction length, and density of Coulomb impurities. We systematically collect and analyze the trends of electron mobility with respect to the above factors, realized by synergic modulations on channel thicknesses and gating modes in dual-gated MoS2 transistors with asymmetric dielectric cleanliness. Strict configurative form factors are developed to capture the subtle parametric changes across dimensional crossover. A full diagram of the carrier scattering mechanisms, in particular on the pronounced Coulomb scattering, is unfolded. Moreover, we clarify the presence of up to 40% discrepancy in mobility by considering the permittivity modification across dimensional crossover. The understanding is useful for exploiting atomically thin body transistors for advanced electronics.