Van der Waals Epitaxy of the Transition Metal Dichalcogenide WTe₂

Thin film transition metal dichalcogenides (TMD) are strong candidates for future technological application, which 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 metals and chalcogen species. Here, we adopt a van der Waals epitaxy method [1], based on the metal-organic precursor W(CO)6, with the goal to develop a growth recipe for WTe₂ monolayer films. Employing surface-sensitive measurement techniques, we characterized the as-grown films and observed WTe_x-based, one-dimensional nanostructures at the step edges and two-dimensional islands on the substrate terraces. From these results, we investigate the growth dynamics of WTe₂ few-layer thin films.

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