Ultralow frequency nanoimaging of 2D materials

Semiconducting layered 2D materials have recently attracted interest due to their fascinating properties and potential applications. Imaging and control of interlayer interactions provides tunability of optical and electric properties. Ultralow frequency Raman spectroscopy is sensitive to interlater interactions. In this work, ultralow frequency tip-enhanced Raman scattering (ULF-TERS) is used for nanoscale characterization of complex lateral/vertical/twisted transition metal dichalcogenide heterostructures. Spatial resolution and signal enhancement of low and high frequency modes is compared. The corresponding enhancement mechanisms are elucidated. These results may be used to design novel quantum optoelectronic nanodevices.