Investigation of interfacial charge transfer in hybrid system of Graphene-MoS₂

Heterostructures of two dimensional layered materials have exciting optical properties that encourage scientists to further study of their photodetector applications. Interactions and, in particular, charge transfer between the constituting layers plays a critical role in the electronic and optical properties. Heterostructure of a few layers of graphene/MoS₂ has been demonstrated as a promising candidate for diverse unique optoelectronic devices owing to the high transparency of graphene, the tunability of its Fermi level and, the magnificent optical properties of MoS₂. Here, the magnitude and the direction (i.e. electron or hole) of the charge transfer was investigated in a graphene/MoS₂ heterostructure. Confocal Raman microscopy and photoluminescence were used to study doping and strain configuration. The surface morphologies of MoS₂ and graphene were investigated by scanning electron microscopy. To correlate work function difference to charge-related phenomena, KPFM and EFM were carried out. We speculate that the tunable Fermi level in graphene allows excellent work-function match with MoS₂, resulting in low contact resistance.