(Invited) Contacts to and Contact-Less Characterization of Transition Metal Dichalcogenides: Challenges Abound

Abstract

Transition metal dichalcogenides (TMD) such as MoS2 or WSe2 have often been billed as the semiconducting counterpart – or even successor - of graphene. While the semiconducting nature of the corresponding bulk materials is beyond doubt, the understanding of what semiconducting means for a 2 dimensional material is emerging only slowly. In this presentation I will talk about the formation of contacts to TMD materials and the associate shift of the Fermi level. Experimental techniques used to obtain the data includes X-ray photoelectron spectroscopy and transport measurements. The results shed light on fundamental challenges of transport and devices utilizing these materials. In addition, I will also talk about surface acoustic wave measurements that reveal photogenerated carrier concentrations in TMD materials. These measurements can be performed without the need for metal contacts and, thus, do conceptually not suffer from the limitations described above.