Visualizing In‐Plane Junctions in Nitrogen‐Doped Graphene

Controlling the spatial distribution of dopants in graphene is the gateway to the realization of graphene‐based electronic components. Here, it is shown that a submonolayer of self‐assembled physisorbed molecules can be used as a resist during a post‐synthesis nitrogen doping process to realize a nanopatterning of nitrogen dopants in graphene. The resulting formation of domains with different nitrogen concentrations allows obtaining n–n’ and p–n junctions in graphene. A scanning tunneling microscopy is used to measure the electronic properties of the junctions at the atomic scale and reveal their intrinsic width that is found to be ≈7 nm corresponding to a sharp junction regime. Single layer C60 islands are used as a mask during the exposure of graphene to activated nitrogen, allowing the formation of in‐plane junctions separating domains with different levels of doping. Scanning tunneling microscopy is used to measure the structure and electronic properties of the junctions. Sharp junctions are obtained with a typical width of 7 nm.