Novel Graphene Nanodevices for Electronics and Magnetic Sensing- Vishal Panchal - National Physical Laboratory, in London

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• Speaker to be confirmed
• Thursday 28 February 2013, 14:30-16:00
• Mott Seminar Room, Cavendish Laboratory.

If you have a question about this talk, please contact Kimberly Cole.

Graphene is a two-dimensional material comprised of only carbon atoms closely packed in a honeycomb crystal structure. Local layer thickness, substrate defects and environmental doping heavily influence electronic properties of graphene and need to be fully understood to make the material commercially viable. We present systematic and comprehensive studies of room temperature transport measurements and nanoscale functional mapping of micron-scale Hall devices fabricated out of nominally single-layer epitaxial graphene on 4H-SiC substrate. Transport measurements revealed the 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 devices [1]. Surface potential measurements were used to study the graphene-electrode 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 microscopy (MFM) probes [4]. Single particle detection is essential for counting magnetically labelled molecules in the biomedical industry, while the accurate determination of the MFM probes stray field is critical for quantitative MFM measurements. We demonstrate that epitaxial graphene Hall sensors exceed the performance of conventional semiconductor devices due to the robustness to larger biasing currents and increased coupling between the stray field and the active sensing layer of graphene.

[1] V. Panchal, K. Cedergren, R. Yakimova, A. Tzalenchuk, S. Kubatkin, and O. Kazakova, “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. Tzalenchuk, and O. Kazakova, “Surface potential variations in epitaxial graphene devices investigated by Electrostatic Force Spectroscopy,” 2012 12th IEEE Conference on Nanotechnology (IEEE-NANO), pp. 1–5, 2012. [3] V. Panchal, D. Cox, R. Yakimova, and O. Kazakova, “Epitaxial Graphene Sensors for Detection of Small Magnetic Moments,” IEEE Transactions on Magnetics, Submitted, 2013. [4] V. Panchal, O. Iglesias-Freire, A. Lartsev, R. Yakimova, and A. Asenjo, “Magnetic scanning probe calibration using graphene Hall sensor,” IEEE Transactions on Magnetics, In Press, 2013.

This talk is part of the Thin Film Magnetic Talks series.

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• Mott Seminar Room, Cavendish Laboratory
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