Synergetic effect of electrostatic gating and interfacial states in molecular switching operation in molybdenum disulfide based thin hetero interfaces

Abstract

Nowadays, two-dimensional (2D) materials have stimulated intensive research due to their intriguing physical properties and excellent electronic application. van der Waals (vdW) semiconductors are attractive for electrically controllable carrier confinement, combined with the diverse nature of 2D materials that enable superior electrostatic control. Molecular interaction in two-dimensional van der Waals interfaces has drawn tremendous attention for extraordinary materials characteristics. This work encompasses molecular responses study of various atomically thin heterostructures made of molybdenum disulfide (MoS2), graphene, and hexagonal boron nitride (h-BN). The defect induced interfacial states are created in an atomically thin two-dimensional MoS2 channel by underlying a narrow pattern of a graphene layer in a field-effect transistor. The presence of interfacial states in the channel leads to a conductance fluctuation. Its magnitude is modulated nearly three-order of magnitude at room temperature using the nitrogen dioxide gas molecules in the subthreshold region. The study provides a systematic approach to establishing a correlation between modulated conductance fluctuation and the molecular concentration up to parts-per-billion. First-principles density functional theory further explains the role of unique interfacial configuration on conductance fluctuation. Therefore, our study demonstrates an experimental approach to induce charge-state for the modulation of carrier concentration and exploits the role of defect induced interfacial states in atomically thin interfaces for the molecular interaction. So far, sensing molecular interaction characteristics have been exploited extensively to reach detection limit to a few parts-per-billion (ppb) of molecules. Far less attention is given to the evolution of persistent current state due to molecular exposure. Our study focuses on the molecular memory operation of MoS2-graphene heterostructure based field-effect transistor. The metastable resistance state ...