Fabrication and mechanism of Pb-intercalated graphene on SiC

Revealing the detailed mechanism of metal intercalation on epitaxial graphene on SiC (EG/SiC) is difficult due to the complicacy and randomness of thermal decomposition of SiC substrate. In this context, the fabrication and mechanism of Pb-intercalated graphene (PbG) produced on SiC are investigated by scanning tunneling microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS). It is reported that Pb intercalation prefers to happen at the interface between buffer layer and SiC substrate. Pb atoms penetrate into buffer layer through point defects on buffer layer or graphene edges during annealing, making the buffer layer transferred into an additional graphene layer. PbG regions are mainly exhibited as regular ordered moiré pattern because of the mismatch between Pb atoms and graphene layer. Some irregular PbG regions with scattered moiré pattern are also formed due to the insufficient intercalation of Pb atoms underneath. In addition, the intercalated Pb atoms arrange as two dimensional (2D) ultrathin structure underneath the newly formed PbG, and the thickness of PbG layer will increase by one after Pb intercalation. This study benefits to the modification of electronic properties of graphene on SiC, promoting the development of new 2D materials protected by graphene layer.