Investigation of interaction between graphene and dielectrics

Abstract

The properties of micromechanically exfoliated graphene on different oxide dielectrics—SiO2,Al2O3, andHfO2—are investigated by Raman spectroscopy and AFM measurement. The pristine graphenehas stronger adhesion and a higher hole concentration when the dielectric constant of theunderlying oxide is higher. It is found that annealing under a high vacuum significantlyenhances the adhesion between graphene and the oxides and causes a shift of the Raman Gand 2D bands to a higher wavelength. The high vacuum annealing also causes an increasein carrier concentration of up to ten times with a corresponding Fermi level shift of ∼ 0.65 eV forgraphene on HfO2. On the other hand, the high vacuum annealing of graphene onSiO2 induces a biaxial compressive stress as high as 4 GPa on graphene. The results provideunderstanding on the interaction of graphene and oxides, which is essential for successfulrealization of graphene-based electronic devices.