  The 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. Nondestructive method for the
generation of charge-state allowed a highly sensitive molecular interaction
with the sensitivity of nearly three-order of magnitude at room temperature.
The presence of interfacial states in the channel lead to a conductance
fluctuation and its magnitude is modulated using the 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 upto 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.
