Robust Contact by Direct Formation of CAu Bond in Suspended Armchair Graphene Nanoribbon

Abstract

The Schottky contact between metal electrode and armchair graphene nanoribbon (AGNR) plays a fundamental role in limiting the current flow as well as the overall device characteristics. To improve device performance, the metal electrode must be engineered to lower barrier height and allow low‐resistance ohmic contact. Nevertheless, in most cases, this gives rise to interfacial states which dictate the contact properties and induce Fermi level pinning. Herein, another strategy to form robust and transparent 7‐atom‐wide‐AGNR (7‐AGNR)/Au contacts in which a direct CAu σ bond is initialized by the tip of scanning tunneling microscope (STM) on a dehydrogenated terminus is demonstrated. This process has led to a total lift‐off of 7‐AGNR from the Au(111) substrate and allowed us to visualize the details of the band structure. Furthermore, it is found that GNR is useful as an STM tip for high‐resolution selective imaging of edge states showing a unique interference pattern with a periodicity that coincides with half of Fermi wavelength of GNR lattice. The combination of imaging and tunneling spectroscopy with GNR‐tip is promising for unraveling intrinsic details in the band structure which are of fundamental importance to understand the transport properties of GNRs devices.