Adsorption of Ammonia on Graphene

ORAL

Abstract

We report on experimental studies of NH$_{3}$ adsorption/desorption kinetics on graphene surfaces. The study employs bottom-gated graphene field effect transistors (FETs) supported on Si/SiO$_{2}$ substrates. Detection of NH$_{3}$ occurs through the shift of the source-drain resistance maximum (``Dirac peak'') with gate voltage. The observed shift of the Dirac peak toward negative gate voltages in response to NH$_{3}$ exposure is attributed to the charge transfer from adsorbed NH$_{3}$, with the amount of charge estimated to be $\sim $ 0.06 electrons per molecule. The desorption kinetics of our FET devices is well described by the sum of two exponential terms corresponding to a fast and a much slower process, whose time constants differ by a factor of $\sim $ 9. The two-time constant desorption kinetics is consistent with Fickian-type diffusion of NH$_{3}$ from the interstitial pockets formed at the interface between the graphene and the supporting SiO$_{2}$ gate dielectric.

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Authors

  • Parsoon Joshi

    Electrical Engineering Department, Pennsylvania State University, Electrical Engineering Department, Penn State University

  • Hugo Romero

    Dept. of Physics, Penn State, Physics Department, Pennsylvania State University, Physics Department, Penn State University

  • Awnish Gupta

    Department of Physics, The Pennsylvania State University, Department of Physics, Pennsylvania State University, University Park, PA 16802, Physics Department, Pennsylvania State University, Department of Physics, Pennsylvania State University, Department of Physics, Penn State University

  • Humberto Gutierrez

    Department of Physics, The Pennsylvania State University, Physics Department, Pennsylvania State University, Department of Physics, Pennsylvania State University, Physics Department, Penn State University

  • Milton Cole

    Physics Department, Pennsylvania State University, Pennsylvania State University

  • Srinivas Tadigadapa

    Electrical Engineering Department, Pennsylvania State University, Electrical Engineering Department, Penn State University

  • Peter Eklund

    Physics Department, Penn State University, Dept. of Physics, Penn State, Department of Physics, The Pennsylvania State University, Department of Physics, Department of Materials Science and Engeering, The Pennsylvania State University, Department of Physics, Department of Material Science and Engineering, Pennsylvania State University, University Park, PA 16802, Physics Department, Material Science \& Engineering Department, Department of Physics, Department of Material Sciece and Engineering, Pennsylvania State University, Department of Physics, Department of Materials Science \& Engineering and Materials Research Institute, Penn State University, Physics Department,Materials Science \& Engineering Department, Pennsylvania State University