Scanning tunneling microscopy/spectroscopy study of graphene -- MoS$_{2}$ heterojunction

Atomic scale topographic fluctuations are relevant to a number of graphene applications including graphene / semiconductor Schottky diodes [1,2]. In this work, we investigate the atomic structures and electronic properties of~graphene-MoS$_{2}$ heterojunction fabricated by transferring chemical vapor deposited monolayer graphene onto mechanically exfoliated multilayer MoS$_{2}$. Scanning tunneling microscopy reveals the formation of Moir\'{e} patterns with corrugations $\sim$ 0.03 nm, but no ripples, in contrast to graphene-SiC junctions [1,2]. Scanning tunneling spectroscopy further indicates that the periodic modulations of the Moir\'{e} pattern do not influence the electronic properties of the junction. Additional states near the Fermi level are also observed, likely due to impurities trapped at the interface during graphene transfer. These results and their impact on the properties of the van der Waals graphene-MoS$_{2}$ heterojunction will be discussed at the meeting. \\[4pt] [1] S. Rajput \textit{et al.} Nat. Commun. \textbf{4,} 2752 (2013).\\[0pt] [2] D. Tomer \textit{et al.} Appl. Phys. Lett. \textbf{105,} 021607 (2014).