Two-dimensional semiconductors, specifically the broad class of transition metal dichalcogenides (TMDs), have attracted significant attention in the research community in recent years due to the wealth of interesting and potentially applicable phenomena observed in these materials. In order to control the performance of devices based on TMDs, it is important to characterize their properties at the scale relevant to the corresponding application, which in most cases today corresponds to a few tens of nanometres.
Conventional far-field photoluminescence (PL) and Raman imaging provide highly averaged information with spectral congestion. In contrast, the TEPL and TERS methods (tip-enhanced photoluminescence and tip-enhanced Raman spectroscopy) performed with an AFM–Raman system, not limited by diffraction, provide substantial information related to the nanoscale optical properties of 2D materials with resolution down to a few nanometres.
In this webinar, we report on the application of scanning-probe microscopy (SPM) cross-correlated with TERS and TEPL measurements. The techniques are used to image various TMD (MoS2, WS2, MoSe2, WSe2) alloys and heterostructures, revealing detailed nanoscale features and unexpected heterogeneities. These variations in the nanoscale optical and chemical properties, correlated with the structural information obtained with SPM, can provide a better understanding of 2D TMD materials for the future development of highly efficient, flexible, lightweight optoelectronic devices.