Layer-decoupling of multi-layered graphene by electride-based electron injection

Graphene has been extensively explored due to its promising intrinsic characteristics such as high mobility and thermal conductivity, which inspired applications in nano-scale electrical devices. The Fermi level of graphene that affects its electrical performance can be largely modulated by (chemical) doping. To realize the doping of carriers in graphene, physical deposition of N, B or H molecules on graphene have been tried. However, these studies showed inevitable deformation of graphene lattices, which could be observed as D peak in Raman spectrum. Clean methods for an efficient doping without defects have been demanded.
Here, we report an electron doping method without forming defects in multi-layered graphene by building an interface between 2D electride Ca₂N and graphene. The doping was confirmed by Raman spectroscopy that is sensitive to the change of the Fermi level and formation of defects. The G and 2D peak and P1 and P2 of 2D peak ratio were dramatically changed after making the interface. We also discovered that the interaction between stacked graphene layers became weaker by the electron injection. Despite such efficient carrier injection, the D peak in Raman doesn't appear, which demonstrates our electron doping of graphene without making defects in graphene lattice.