Phonon modes and photonic excitation transitions of MoS2 induced by top-deposited graphene revealed by Raman spectroscopy and photoluminescence

Abstract

Although the MoS2/graphene 2D stack achieved a lot of attention in recent research on 2D semiconductor devices, the interface interaction between perfect MoS2 and graphene and its effects on the electronic properties are rarely studied. Here, we report our recent studies on Raman spectroscopy and photoluminescence of the MoS2/graphene heterostructure. A nearly perfect interface between these two materials was achieved with a dry transfer and forming gas annealing. Raman spectroscopy of the heterostructure shows that the strong interface interaction leads to blue-shifts of Raman modes in MoS2 and graphene. Moreover, indicated by the photoluminescene of the heterostructure, the photon excitation and electronic dynamics of MoS2 are significantly influenced by the additional graphene layer on top. Our results reveal that the interface of heterostructures plays an important role in determining the physical properties, and it is better to view the heterostructure as a newly emerging material rather than a simple physical combination of the two materials.