Growth of highly oriented MoS2via an intercalation process in the graphene/SiC(0001) system

Abstract

A method of growing highly oriented MoS₂ is presented. First, a Mo film is deposited on a graphene/SiC(0001) substrate and the subsequent annealing of it at 750 °C leads to intercalation of Mo underneath the graphene layer, which is confirmed by secondary ion mass spectrometry (SIMS) measurements. Formation of highly oriented MoS₂ layers is then achieved by sulfurization of the graphene/Mo/SiC system using H₂S gas. X-ray diffraction reveals that the MoS₂ layers are highly oriented and parallel to the underlying SiC substrate surface. Further SIMS experiments reveal that the intercalation process occurs via the atomic step edges of SiC and Mo and S atoms gradually diffuse along SiC atomic terraces leading to the creation of the MoS₂ layer. This observation can be explained by a mechanism of highly oriented growth of MoS₂: nucleation of the crystalline MoS₂ phase occurs underneath the graphene planes covering the flat parts of SiC steps and Mo and S atoms create crystallization fronts moving along terraces.