Role of Defect-Induced Interfacial States in Molecular Sensing: Ultrahigh-Sensitivity Region for Molecular Interaction

Defect-induced interfacial states are created in an atomically thin two-dimensional molybdenum-disulfide channel by underlying a narrow pattern of a graphene layer in a field effect transistor. A nondestructive method for the generation of charge states allowed a highly sensitive molecular interaction with sensitivity of nearly 3 orders of magnitude at room temperature. The presence of interfacial states in the channel leads to a conductance fluctuation and its magnitude is modulated using nitrogen-dioxide gas molecules in the subthreshold region. The study provides a systematic approach to establish 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 molecular interaction.