Anomalous Conductance near Percolative Metal-Insulator Transition in Monolayer MoS₂ at Low Voltage Regime.

Abstract

Conductivity of the insulating phase increases generally at an elevated drain-source voltage due to the field-enhanced hopping or heating effect. Meanwhile, a transport mechanism governed by percolation in a low compensated semiconductor gives rise to the reduced conductivity at a low-field regime. Here, in addition to this behavior, we report the anomalous conductivity behavior to transform from a percolative metallic to an insulating phase at the low voltage regime in monolayer molybdenum disulfide (MoS₂). Percolation transport at low source-drain voltage is governed by inhomogeneously distributed potential in strongly interacting monolayer MoS₂ with a substrate, distinct from the quantum phase transition in multilayer MoS₂. At a high source-drain voltage regime, the insulating phase is transformed further to a metallic phase, exhibiting multiphases of metallic-insulating-metallic transitions in monolayer MoS₂. These behaviors highlight MoS₂ as a model system to study various classical and quantum transports as well as metal-insulator transition in two-dimensional systems.