Tip-Enhanced Raman Spectroscopy Studies of Defects in Few-Layer MoS­₂

Tip-enhanced Raman spectroscopy (TERS) has become a powerful technique for studying chemical information on the nanoscale [1]. In recent years, it has been applied to study a variety of two-dimensional materials, in particular graphene and transition metal dichalcogenides (TMDs) [2-5]. As these 2D materials have seen increased use in electronic and optoelectronic devices and device performance can be heavily influenced by defects and other types of inhomogeneities in these materials, it becomes vital to probe these local variations and understand their correlation with device performance. Here we apply TERS to study inhomogeneities and defects in mechanically exfoliated few-layer MoS­_2­, including edges, bubbles, and wrinkles. By identifying respective features in the TERS spectra, we aim to understand the variations in the chemical bonds caused by each type of defect. These structures will also be used to build heterostructure devices, and the relation between defects and device performance will be explored.