A predictive approach to CVD of crystalline layers of TMDs: The case of MoS₂

Layered transition metal dichalcogenides (TMDs), such as MoS₂, are candidate materials for next generation 2-D electronic and optoelectronic devices. The ability to grow uniform, crystalline, atomic layers over large areas is the key to developing such technology. We report a chemical vapor deposition (CVD) technique which yields n-layered MoS₂ on a variety of substrates. A generic approach suitable to all TMDs, involving thermodynamic modeling to identify the appropriate CVD process window, and quantitative control of the vapor phase supersaturation, is demonstrated. All reactant sources in our method are outside the growth chamber, a significant improvement over vapor-based methods for atomic layers reported to date. The as-deposited layers are p-type, due to Mo deficiency, with field effect and Hall hole mobilities of up to 2.4 cm² V^-1 s^-1 and 44 cm² V^-1 s^-1 respectively. These are among the best reported yet for CVD MoS₂.