title: Modification of graphene/SiO2 interface by UV-irradiation: effect on electrical characteristics.
abstract: Graphene is a promising material for next-generation electronic devices. The effect of UV-irradiation on the graphene devices, however, has not been fully explored yet. Here we investigate the UV-induced change of the field effect transistor (FET) characteristics of graphene/SiO2. UV-irradiation in a vacuum gives rise to the decrease in carrier mobility and a hysteresis in the transfer characteristics. Annealing at 160 °C in a vacuum eliminates the hysteresis, recovers the mobility partially, and moves the charge neutrality point to the negative direction. Corresponding Raman spectra indicated that UV-irradiation induced D band relating with defects and the annealing at 160 °C in a vacuum removed the D band. We propose a phenomenological model for the UV-irradiated graphene, in which photochemical reaction produces dangling bonds and the weak sp(3)-like bonds at the graphene/SiO2 interface, and the annealing restores the intrinsic graphene/SiO2 interface by removal of such bonds. Our results shed light to the nature of defect formation by UV-light, which is important for the practical performance of graphene based electronics.
authors.affiliation: Department of Complexity Science and Engineering, The University of Tokyo , Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8561, Japan.
authors.forename: Gaku
authors.initials: G
authors.lastname: Imamura
authors.forename: Koichiro
authors.initials: K
authors.lastname: Saiki
keywords: Raman spectroscopy; carrier doping; defect formation; field effect transistors; graphene; photochemical reactions