Surface transfer hole doping of epitaxial graphene using $MoO3$ thin film

Synchrotron-based in situ photoelectron spectroscopy investigations demonstrate effective surface transfer p-type doping of epitaxial graphene (EG) thermally grown on 4H–SiC(0001) via the deposition of $MoO3$ thin film on top. The large work function difference between EG and $MoO3$ facilitates electron transfer from EG to the $MoO3$ thin film. This leads to hole accumulation in the EG layer with an areal hole density of about $1.0×1013cm−2$⁠, and places the Fermi level 0.38 eV below the graphene Dirac point.