WS2 nanotube formation by sulphurization : effect of precursor tungsten film thickness and stress

Abstract Transition metal dichalcogenides can exhibit as 2-dimensional layers, 1-dimensional nanotubes or 0-dimensional quantum dot structures. In general, dichalcogenide nanotubes are grown under stringent conditions, using high growth temperatures with tedious processes. Here, we report the controlled formation of tungsten disulphide (WS 2 ) nanostructures by manipulating the precursor film thickness, followed by a direct sulphurization process. WS 2 nanotubes were formed by ultra-thin tungsten precursor films, while particle-like WS 2 were obtained from thicker tungsten films under identical sulphurization conditions. To elucidate the origin of WS 2 nanostructure formation, micron-sized tungsten film tracks were prepared, and such patterned films were found to suppress the growth of WS 2 nanotubes. We attribute the suppression of nanotube formation to the relieving of film stress in patterned precursor films.