Narrow photoluminescence and Raman peaks of epitaxial MoS2 on graphene/Ir(1 1 1)

We report on the observation of photoluminescence (PL) with a narrow 18 meV peak width from molecular beam epitaxy grown on graphene/Ir(1 1 1). This observation is explained in terms of a weak graphene-MoS2 interaction that prevents PL quenching expected for a metallic substrate. The weak interaction of MoS2 with the graphene is highlighted by angle-resolved photoemission spectroscopy and temperature dependent Raman spectroscopy. These methods reveal that there is no hybridization between electronic states of graphene and MoS2 as well as a different thermal expansion of both materials. Molecular beam epitaxy grown MoS2 on graphene is therefore an important platform for optoelectronics which allows for large area growth with controlled properties.