Surface and trapped charge characterization of epitaxial oxides for applications in graphene electronics$^{1}$

ORAL

Abstract

Trapped charges have been shown to play an important role in the transport properties of graphene supported on SiO$_{2}$, and surface roughness may also play a role. Alternative substrate materials, Sc$_{2}$O$_{3}$ ($\varepsilon \sim $ 14, $n\sim $ 1.9) and Gd$_{2}$O$_{3}$ ($\varepsilon \sim $ 22, $n\sim $ 2) were grown epitaxially by molecular beam epitaxy on Si(111) over a range of thicknesses from 2 nm to 100 nm. AFM measurements yield rms roughness, and correlation function analysis reveals the nature of the long range order. For Sc$_{2}$O$_{3}$, the roughness is strongly thickness dependent, with root-mean-square height 0.26 nm$^{2}$ for a 20 nm thick film and 0.55 nm$^{2}$ for a 65 nm thick film; however, the correlation exponent (2$H\sim $ 1) and correlation length ($\xi \sim $ 20 nm) are the same. The roughness characterization for the full range of thicknesses of both oxides will be presented. In addition, frequency-dependent CV measurements are underway to determine the trapped charge densities. [1] supported by a NRI supplement to the UMD-NSF-MRSEC grant {\#} DMR 0520471.

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Authors

  • Blake Riddick

    • University of Maryland, College Park
    • Physics Department, University of Maryland, College Park, MD 20742

  • Brad Conrad

    • Department of Physics and University of Maryland Materials Research Science and Engineering Center, University of Maryland, College Park, MD 20742
    • Physics Department, University of Maryland, College Park, MD 20742
    • University of Maryland College Park

  • William Minshew

    • Physics Department, University of Maryland, College Park, MD 20742

  • William G. Cullen

    • University of Maryland
    • Physics Department, University of Maryland, College Park, MD 20742
    • Materials Research Science and Engineering Center, Center for Nanophysics and Advanced Materials, Dept of Physics, Univ. of Maryland, College Park, MD
    • University of Maryland College Park
    • Dept. of Physics, U. of Maryland - College Park

  • Ellen Williams

    • University of Maryland, College Park
    • Department of Physics and University of Maryland Materials Research Science and Engineering Center, University of Maryland, College Park, MD 20742
    • University of Maryland
    • LPS, CNAM, and the DOP, UM
    • Physics Department, University of Maryland, College Park, MD 20742
    • Materials Research Science and Engineering Center, Center for Nanophysics and Advanced Materials, Dept of Physics, Univ. of Maryland, College Park, MD
    • University of Maryland College Park
    • Dept. of Physics, U. of Maryland - College Park
    • Department of Physics and Center for Nanophysics and Advanced Materials, University of Maryland, College Park, MD 20742-4111, USA

  • Tassilo Heeg

    • Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853; currently at Pennsylvania State University

  • D. Schlom

    • Cornell University
    • Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853; currently at Pennsylvania State University