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SUMMARY: Novel Graphene Nanodevices for Electronics and Magnetic Sensing- 
  Vishal Panchal - National Physical Laboratory\, in London - Speaker to be
  confirmed
DTSTART:20130228T143000Z
DTEND:20130228T160000Z
UID:TALK43831@talks.cam.ac.uk
CONTACT:Kimberly Cole
DESCRIPTION:Graphene is a two-dimensional material comprised of only carbo
 n atoms closely packed in a honeycomb crystal structure. Local layer thick
 ness\, substrate defects and environmental doping heavily influence electr
 onic properties of graphene and need to be fully understood to make the ma
 terial commercially viable. We present systematic and comprehensive studie
 s of room temperature transport measurements and nanoscale functional mapp
 ing of micron-scale Hall devices fabricated out of nominally single-layer 
 epitaxial graphene on 4H-SiC substrate. Transport measurements revealed th
 e minimum detectable field of a typical 10-µm graphene sensor to be ~2.5 
 µT/√Hz\, making them comparable with state-of-the-art semiconductor dev
 ices [1]. Surface potential measurements were used to study the graphene-e
 lectrode contact resistances and the effect of photochemical and substrate
  doping on the work function of 1-2 layer graphene [2]. The performance of
  graphene Hall sensors was tested by reliably detecting the stray magnetic
  field of a single 1-μm size magnetic particle [3] and magnetic force mic
 roscopy (MFM) probes [4]. Single particle detection is essential for count
 ing magnetically labelled molecules in the biomedical industry\, while the
  accurate determination of the MFM probes stray field is critical for quan
 titative MFM measurements. We demonstrate that epitaxial graphene Hall sen
 sors exceed the performance of conventional semiconductor devices due to t
 he robustness to larger biasing currents and increased coupling between th
 e stray field and the active sensing layer of graphene.\n\n[1] V. Panchal\
 , K. Cedergren\, R. Yakimova\, A. Tzalenchuk\, S. Kubatkin\, and O. Kazako
 va\, “Small epitaxial graphene devices for magnetosensing applications\,
 ” Journal of Applied Physics\, vol. 111\, no. 7\, p. 07E509\, 2012. [2] 
 V. Panchal\, T. L. Burnett\, R. Pearce\, K. Cedergren\, R. Yakimova\, A. T
 zalenchuk\, and O. Kazakova\, “Surface potential variations in epitaxial
  graphene devices investigated by Electrostatic Force Spectroscopy\,” 20
 12 12th IEEE Conference on Nanotechnology (IEEE-NANO)\, pp. 1–5\, 2012. 
 [3] V. Panchal\, D. Cox\, R. Yakimova\, and O. Kazakova\, “Epitaxial Gra
 phene Sensors for Detection of Small Magnetic Moments\,” IEEE Transactio
 ns on Magnetics\, Submitted\, 2013. [4] V. Panchal\, O. Iglesias-Freire\, 
 A. Lartsev\, R. Yakimova\, and A. Asenjo\, “Magnetic scanning probe cali
 bration using graphene Hall sensor\,” IEEE Transactions on Magnetics\, I
 n Press\, 2013.
LOCATION:Mott Seminar Room\, Cavendish Laboratory
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