Modification of electronic properties of top-gated graphene devices by ultrathin yttrium-oxide dielectric layers

Abstract

We report the structure characterization and electronic property modification of single layer graphene (SLG) field-effect transistor (FET) devices top-gated using ultrathin Y₂O₃ as dielectric layers. Based on the Boltzmann transport theory within variant screening, Coulomb scattering is confirmed quantitatively to be dominant in Y₂O₃-covered SLG and a very few short-range impurities have been introduced by Y₂O₃. Both DC transport and AC capacitance measurements carried out at cryogenic temperatures demonstrate that the broadening of Landau levels is mainly due to the additional charged impurities and inhomogeneity of carriers induced by Y₂O₃ layers.