Tremendous interest in two-dimensional (2D) nanomaterials derived from graphene has extended to transition metal dichalcogenide (TMDC), an atomically thin semiconductor with one layer of transition metal atoms sandwiched between two layers of chalcogen atoms. With direct band gaps in the visible portion of the electromagnetic spectrum, large exciton binding energies, and strong photoluminescence, monolayer semiconducting TMDCs are promising for optoelectronic applications.