In situ photoemission spectroscopy study on formation of $HfO2$ dielectrics on epitaxial graphene on SiC substrate

High quality $HfO2$ dielectrics have been grown on epitaxial graphene on 4H-SiC substrates and have been studied by using in situ x-ray photoemission spectroscopy. The in situ thermal treatment shows that the $HfO2$/graphene/4H-SiC heterojunctions have good thermal stability up to $650°C$⁠. A shift of core-level spectra from graphene layer implies that charge transfer takes place at the interface. The high thermal stability and sufficient barrier heights between $HfO2$ and graphene indicate that high-$k$ dielectric grown on graphene is very promising for the development of graphene-based electronic devices.