The current transport across the graphene/$4H\text{-SiC}$ interface has been investigated with nanometric lateral resolution by scanning current spectroscopy on both epitaxial graphene (EG) grown on (0001) $4H\text{-SiC}$ and graphene exfoliated from highly oriented pyrolytic graphite deposited on the same substrate [deposited graphene (DG)]. This study reveals that the Schottky barrier height (SBH) of $\text{EG}/4H\text{-SiC}$ $\left(0.36\pm 0.1\text{eV}\right)$ is $\sim 0.49\text{eV}$ lower than the SBH of $\text{DG}/4H\text{-SiC}$ $\left(0.85\pm 0.06\text{eV}\right)$. This result is discussed in terms of the Fermi-level pinning $\sim 0.49\text{eV}$ above the Dirac point in EG due to the presence of positively charged states at the interface between the Si face of $4H\text{-SiC}$ and the carbon-rich buffer layer, which is the precursor for EG formation.

• Received 12 October 2009

DOI:https://doi.org/10.1103/PhysRevB.80.241406