Large area synthesis, characterization, and anisotropic etching of two dimensional tungsten disulfide films

• Large-scale synthesis of WS2 films is achieved via sulfurization of W films.
• Annealing of W films leads to a substantial improvement in the quality of WS2 films.
• WS2 films show laser power dependent photoluminescence characteristics.
• WS2 films are etched with well-oriented triangular pits upon annealing in air.
• Anisotropic oxidative etching is greatly affected by the thickness of WS2 films.

Emergent properties of tungsten disulfide at the quantum confinement limit hold promise for electronic and optoelectronic applications. Here we report on the large area synthesis of atomically thin tungsten disulfide films with strong photoluminescence properties via sulfurization of the pre-deposited tungsten films. Detailed characterization of the pre-deposited tungsten films and tungsten disulfide films are performed using microscopy and spectroscopy methods. By directly heating tungsten disulfide films in air, we have shown that the films tend to be etched into a series of triangular shaped pits with the same orientations, revealing the anisotropic etching behavior of tungsten disulfide edges. Moreover, the dimensions of the triangular pits increase with the number of layers, suggesting a thickness dependent behavior of etching in tungsten disulfide films. This method offers a promising new avenue for engineering the edge structures of tungsten disulfide films.