Fabricating Quasi-Free-Standing Graphene on a SiC(0001) Surface by Steerable Intercalation of Iron

Graphene has been granted with appealing attributes for new-generation electronics due to its unique electronic properties. However, the interaction between graphene and the supporting substrate substantially limits its technological application. Here, we demonstrate the transformation of epitaxial monolayer graphene on SiC(0001) into decoupled bilayer graphene using steerable iron intercalation manipulated by thermal annealing. By means of Raman scattering and photoemission measurements, we have performed an in-depth investigation of the intercalation procedure and shown the quasi-free-standing nature of the decoupled bilayer graphene afterward, as characterized by its unique structural and electronic properties. The intercalation of Fe atoms can be manipulated through temperature-driven processes after adsorption on top of the graphene layer, and this substantially modifies the interfacial interaction between the buffer layer and SiC substrate and, correspondingly, the doping level of the pristine graphene, ultimately resulting in the decoupling of buffer layer from the substrate. Although the decoupling of epitaxial graphene grown on silicon carbide has previously been a critical issue, our study highlights a feasible approach for producing high-quality quasi-free-standing graphene on SiC in a well-controlled manner, and for tuning the intrinsic electronic properties of lateral graphene/SiC lateral structure by ferromagnetic element intercalation.