In-situ Studies of High-κ Dielectrics for Graphene-Based Device

Abstract

The deposition and subsequent oxidation of metallic Al and Hf on graphite has been studied as a route to the formation of a high-κ dielectric on graphene. We employ in-situ x-ray photoelectron spectroscopy (XPS), ex-situ atomic force microscopy (AFM) and Raman spectroscopy to study reactions with the substrate and dielectric film morphology. We show that Al2O3 can be formed on the freshly cleaved graphene surface by annealing the deposited metallic Al in ozone or oxygen. HfO2 is also formed in this manner, but we demonstrate that in the case of Hf, defects are created on the graphene surface unless physisorbed H2O is removed by vacuum annealing prior to deposition and the deposition performed under ultra high vacuum (UHV) conditions.