Characterization of Edge Contact: Atomically Resolved Semiconductor-Metal Lateral Boundary in MoS2

Abstract: Despite recent efforts for the development of transition metal dichalcogenide-based high-performance thin film transistors, device performance has not improved much, mainly because of the high contact resistance at the interface between the 2D semiconductor and the metal electrode. The edge contact was proposed for the fabrication of a high-quality electrical contact. However, the complete electronic properties for the contact resistance have not been elucidated in detail. Using scanning tunneling microscopy/spectroscopy (STM/STS) and scanning transmission electron microcopy (STEM) techniques, in this work we investigate the edge contact as well as the lateral boundary between the 2D semiconducting layer and the metalized interfacial layer in this work, and show their electronic properties and the energy band profile across the boundary. Our results demonstrate a possible mechanism for the formation of an ohmic contact in homojunctions of the TMD semiconductor-metal layers and suggests a new device scheme utilizing the low-resistance edge contact.