University of South Florida, USA
Title: Interfaces betweentransferred, CVD-grown graphene and MoS2 probed with STM and ARPES
Matthias Batzill is a Professor of physics at University of South Florida. He completed his PhD in 1999 from University of Newcastle upon Tyne, UK. His research interests include: Research Interests: Surface science, Gas-surface interactions, Structure and electronic properties of metal oxide surfaces, Nanoclusters and quantum dots, Solid state gas sensors, Photocatalysis and photovoltaic for sustainable and renewable energy
Heterostructures made of different van der Waals materials are of increasing interest because of potential applications in energy harvesting and combination of spin- and valley-tronics. However, the interface properties of these materials are not yet well characterized. One challenge for their characterization is the preparation of large-area high quality materials that enable employment of surface characterization techniques such as scanning probe microscopy and photoemission spectroscopy. Here we demonstrate the transfer of CVD-grown graphene to bulk MoS2 substrates and report the first STM and ARPES studies of such a system. As expected for weakly interacting materials STM studies only exhibit a very weak moire-superstructure and (nano) ARPES measurements show that the Dirac cone of graphene is maintained. However, (nano) ARPES also shows the formation of band-gaps in the pi-band of graphene where the out-of-plane molecular orbitals of MoS2 intersect with the electronic-states of graphene. This modification of the electronic structure of graphene in the graphene/MoS2heterostructure is contrary to expectations of simple van-der Waals stacked materials. The high quality of the samples will enable further studies of the spin state of the graphene and MoS2 substrate as well as enable preparation of other heterostructure materials and thus will give a detailed description of the interaction in these heterostructure systems.
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