Metal-Organic Molecular Beam Epitaxy of WTe₂

Monolayer transition metal dichalcogenides (TMDs) are strong candidates for future technological applications. Such applications require controlled means of ultra-high purity synthesis, as provided by molecular beam epitaxy (MBE). So far, MBE-synthesized TMD monolayers have been limited to islands with lateral sizes on the order of tens of nanometers, due to the large difference of surface diffusivity of the transition metal and chalcogen species. Here, we introduce a molecular beam epitaxy method, based on the metal-organic precursor W(CO)₆, for growing monolayer WTe₂ [1]. We characterize our growth using x-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. We observe one-dimensional nanostructures of non-stoichiometric WTe_x localized at the substrate step edges, and two-dimensional islands on the substrate terraces.

[1] S. Tiefenbach et. al., Surf Sci. 318, L1161 (1994)