The successful preparation of graphene led to a growing number of other two-dimensional materials being reported. Similar to graphene, transition metal dichalcogenides (TMDs) have been studied for some time, with the structure of TMDs first reported by Linus and colleagues as early as 1923. By the 1960s, about 60 TMDs materials had been reported, of which at least 40 exhibit layered structures, for example MoS2, MoSe2, WS2 and WSe2, among others. These layered crystals not only have a thickness comparable to that of graphene, but additionally have an intrinsic band gap, which gives them the potential to be used in a new generation of small, low energy-consuming transistor materials. The semiconductor industry is driven by the continued reduction in transistor size, with Moore's law stating that the number of transistors that can fit on an integrated circuit doubles approximately every eighteen months. These days, the state-ofthe-art silicon-based transistor has all but reached its fundamental limit and, to further break through the gate length of silicon-based field-effect transistors, materials that can achieve smaller sizes than silicon are sought. Two-dimensional (2D) materials have an inherent advantage for transistor applications because they are intrinsically stable at atomic thicknesses and still have robust and well-characterized electrostatic properties. In a study by Xie et al. it was noted that in field effect transistors prepared from MoS2, channel lengths of down to 4 nm could be reliably achieved; owing to the planar confinement of the 2D material effectively