Influences of Co Doping Effect on the Structural Properties of a Single Graphene Film

The effect of cobalt doping on the structural properties of a single graphene film were determined by use of SEM, temperature-dependent Raman technique, XRD and XPS measurements. XRD and SEM measurements revealed that Co nanoparticles formed on the surface of the single layer of graphene. The XPS results also revealed the existence of bivalent Cobalt ions. Raman spectroscopy revealed enhanced disorder effects, and a large red shift in the 2D peak after the Co deposition process. With decreasing temperature of the pristine single graphene film, the G peak stiffened and sharpened. In contrast, the G peak of the graphene film after Co deposition was not dependent on temperature. This phenomenon indicates that the inhomogeneous local disorder effect is induced by the Co atoms embedded in the graphene film. Moreover, a larger disorder effect induced by Co deposition can be found in single graphene films with higher original vacancies, suggesting the possible formation of Co atom-vacancy complexes. The magnetic Co nanoparticles and magnetic Co atom-vacancy complexes in graphene produced in this experiment could be used in graphene-based spintronic device applications.