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.

*NSF NIRT \# ECS 06-09243

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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