Dependence of Graphene Properties on Dielectric Under-layers

Abstract

The micromechanically exfoliated monolayer graphene on SiO2, Al2O3, and HfO2 are investigated by Raman spectroscopy and AFM measurement. The pristine graphene seems to have stronger adhesion and higher carrier concentration when the dielectric constant of the underlying oxide is higher. It is found that high vacuum annealing significantly increases the interaction between graphene and the oxides and Raman G and 2D bands shift to higher wavelength. The high vacuum annealing for graphene on HfO2 increases carrier concentration of up to ∼10 times with a corresponding Fermi level shift of ∼0.65 eV although that of graphene on SiO2 induces a biaxial compressive stress as high as 4 GPa on graphene. As the three dielectrics evaluated in this work are the most commonly used gate dielectrics in field‐effect transistors, these findings will be useful in fabrication of graphene based field‐effect transistors.