  Optical and electrical properties of two-dimensional transition metal
dichalcogenides (TMDCs) grown by chemical vapor deposition (CVD) are strongly
determined by their microstructure. Consequently, the visualization of spatial
structural variations is of paramount importance for future applications. Here
we demonstrate how grain boundaries, crystal orientation, and strain fields can
unambiguously be identified with combined lateral force microscopy (LFM) and
transverse shear microscopy (TSM) for CVD-grown tungsten disulfide (WS2)
monolayers, on length scales that are relevant for optoelectronic applications.
Further, angle-dependent TSM measurements enable us to acquire the fourth-order
elastic constants of monolayer WS2 experimentally. Our results facilitate
high-throughput and nondestructive microstructure visualization of monolayer
TMDCs, insights into their elastic properties, thus providing an accessible
tool to support the development of advanced optoelectronic devices based on
such two-dimensional semiconductors.
