Doping monolayer graphene with single atom substitutions.

Functionalized graphene has been extensively studied with the aim of tailoring properties for gas sensors, superconductors, supercapacitors, nanoelectronics, and spintronics. A bottleneck is the capability to control the carrier type and density by doping. We demonstrate that a two-step process is an efficient way to dope graphene: create vacancies by high-energy atom/ion bombardment and fill these vacancies with desired dopants. Different elements (Pt, Co, and In) have been successfully doped in the single-atom form. The high binding energy of the metal-vacancy complex ensures its stability and is consistent with in situ observation by an aberration-corrected and monochromated transmission electron microscope.