The successful isolation of two-dimensional (2D) graphene has stimulated research on a broad range of other 2D materials, among which layered transition metal dichalcogenides (TMDs) have attracted particular attention. The semiconducting members of the TMD family including MoS2, MoSe2 and WSe2 have not only demonstrated many of the "graphene like" properties desirable for electronic applications such as a relatively high mobility, mechanical flexibility, chemical and thermal stability, and the absence of dangling bonds, but also have a substantial band gap (1 ~ 2 eV depending on the material and its thickness), which is absent in 2D graphene but required for mainstream logic applications. However, a major bottleneck in electronic applications of TMDs is their tendency to form a substantial Schottky barrier with most electrode metals, which severely limits their performance. In this talk, I will discuss our recent work aiming to overcome this fundamental challenge and subsequently explore the intrinsic transport properties of TMDs. Particularly, we have used heavily doped graphene and 2D semiconductors to fabricate low-resistance ohmic contacts for a variety of TMDs.1, 2

1. Chuang, H.-J.; Chamlagain, B.; Koehler, M.; Perera, M. M.; Yan, J.; Mandrus, D.; Tománek, D.; Zhou, Z. Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe2, MoS2, and MoSe2 Transistors. Nano Letters 2016, 16, 1896-1902.
2. Chuang, H.-J.; Tan, X.; Ghimire, N. J.; Perera, M. M.; Chamlagain, B.; Cheng, M. M.-C.; Yan, J.; Mandrus, D.; Tománek, D.; Zhou, Z. High Mobility WSe2 p- and n-Type Field-Effect Transistors Contacted by Highly Doped Graphene for Low-Resistance Contacts. Nano Letters 2014, 14, 3594-3601.