Mobility and Saturation Velocity in Graphene on Silicon Dioxide
Dorgan, Vincent E.
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https://hdl.handle.net/2142/16801
Description
Title
Mobility and Saturation Velocity in Graphene on Silicon Dioxide
Author(s)
Dorgan, Vincent E.
Issue Date
2010-08-20T17:58:10Z
Director of Research (if dissertation) or Advisor (if thesis)
Pop, Eric
Department of Study
Electrical & Computer Eng
Discipline
Electrical & Computer Engr
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
graphene
mobility
high-field
Abstract
Transport properties of exfoliated graphene samples on SiO2 are examined from four-probe electrical measurements combined with electrical and thermal modeling. Data are analyzed with practical models including gated carriers, thermal generation, “puddle” charge, and Joule heating. Graphene mobility is characterized as a function of carrier density at temperatures from 300 to 500 K. In addition, electron drift velocity is obtained at high electric fields up to 2 V/μm, at both 80 K and 300 K. Mobility displays a peak vs. carrier density and decreases with rising temperature above 300 K. The drift velocity approaches saturation at fields >1 V/μm, shows an inverse dependence on carrier density (~n^-1/2), and decreases slightly with temperature. Saturation velocity is >3×10^7 cm/s at low carrier density, and remains greater than in Si up to 1.2×10^13 cm^-2 density. Transport appears primarily limited by the SiO2 substrate, but results suggest intrinsic graphene saturation velocity could be more than twice that observed here.
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