Controlling the morphology of MBE-grown WSe$_{\mathrm{2}}$ on epitaxial graphene/SiC(0001).

Controlling the morphology of transition metal dichalcogenides (TMDs) during molecular beam epitaxy is critical for their potential device applications. In this work, by systematically changing the substrate temperature and W/Se flux ratio, the growth of sub-monolayer to few layers WSe$_{\mathrm{2}}$ on graphene/SiC(0001) is investigated by in situ scanning tunneling microscopy, x-ray photoelectron spectroscopy, and Raman spectroscopy. The results indicate that the morphology of the WSe$_{\mathrm{2}}$ films can be controlled from fractal to compact triangular. These findings and their implication for the controlled growth of TMD heterostructures will be discussed at the meeting.