N-Doped Graphene Field-Effect Transistors with Enhanced Electron Mobility and Air-Stability

Authors

  • Wentao Xu,

    1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea
    Search for more papers by this author
    • [+]W. Xu and T.-S. Lim contributed equally to this work.

  • Tae-Seok Lim,

    1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea
    Search for more papers by this author
    • [+]W. Xu and T.-S. Lim contributed equally to this work.

  • Hong-Kyu Seo,

    1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea
    Search for more papers by this author
  • Sung-Yong Min,

    1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea
    Search for more papers by this author
  • Himchan Cho,

    1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea
    Search for more papers by this author
  • Min-Ho Park,

    1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea
    Search for more papers by this author
  • Young-Hoon Kim,

    1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea
    Search for more papers by this author
  • Tae-Woo Lee

    Corresponding author
    1. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea
    Search for more papers by this author

Abstract

Although graphene can be easily p-doped by various adsorbates, developing stable n-doped graphene that is very useful for practical device applications is a difficult challenge. We investigated the doping effect of solution-processed (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine (N-DMBI) on chemical-vapor-deposited (CVD) graphene. Strong n-type doping is confirmed by Raman spectroscopy and the electrical transport characteristics of graphene field-effect transistors. The strong n-type doping effect shifts the Dirac point to around -140 V. Appropriate annealing at a low temperature of 80 ºC enables an enhanced electron mobility of 1150 cm2 V−1 s−1. The work function and its uniformity on a large scale (1.2 mm × 1.2 mm) of the doped surface are evaluated using ultraviolet photoelectron spectroscopy and Kelvin probe mapping. Stable electrical properties are observed in a device aged in air for more than one month.

Ancillary