Synthesis of transition metal dichalcogenides

Two-dimensional (2D) materials are often called van der Waals materials because they typically have strong in-plane covalent bonds and weak out-of-plane van der Waals forces. For the unique structure of the van der Waals materials, they can form a stable structure as the materials are reducing to an atomically thin monolayer. Single-layer graphite called graphene has been produced by mechanical exfoliation method from highly ordered pyrolytic graphite. Since the discovery of graphene, many unique and superior properties of the material have been revealed. However, it has some limitations in the semiconductor applications due to its semimetallic character. The success of graphene research and lack of semiconductor property have led scientists to find other inorganic 2D materials beyond graphene. Researchers have revealed several different types of 2D semiconductor materials, such as transition metal dichalcogenides (TMDs), phosphorene, and MXene. TMDs among the 2D semiconductor materials have attracted considerable attention as core materials of next-generation semiconductor devices due to their unique electrical, mechanical, chemical, and optical properties. This chapter discusses various methods to synthesize and to manipulate the properties of TMDs.