Max C. LemmeUniversity of Siegen, Germany
Max C. Lemme is Heisenberg-Professor for Graphene-based Nanotechnology at the University of Siegen, Germany. The main focus of his group is the investigation of electronic, optoelectronic and nanoelectromechanical devices made from graphene and 2D materials, with a strong emphasis on applications. He is also Affiliated Professor at KTH Royal Institute of Technology, Sweden, and Visiting Professor at CEA LETI, France. From 2010-2013 he was Guest Professor at KTH Royal Institute of Technology, Sweden and he was a research fellow at Harvard University, USA from 2008-2010. From 1998-2008 he worked at nanotechnology start-up AMO GmbH, Germany, as Head of Technology Department. He is the coordinator of the FP7 project GRADE (Graphene-based Devices and Circuits for RF Applications). Lemme was awarded with an ERC grant for Integrating Graphene Devices (InteGraDe) in 2012 and a “NanoFutur” award of the German Ministry for Education and Research in 2006. He is the speaker of the recently established academic/industrial expert group on “Graphene and 2D Materials“ in North-Rhine Westphalia, Germany and a Senior Member of IEEE.
Title：High Sensitivity of Graphene-based Sensors – Opportunities and Challenges; Laser Annealing of 2D Material-based Inks
SymposiumB04 Others Sensors&B18 Conductive Inks
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Abstract
High Sensitivity of Graphene-based Sensors – Opportunities and Challenges
The two-dimensional nature of graphene leads to an extremely high surface-to-volume ratio, which promises ultrahigh sensitivity of graphene-based sensors. The ultimate thinness and high Young’s modulus of graphene may be utilized in membrane-based devices with very high resonant frequencies for mass sensing applications. In combination with an impressive stretchability, this may further lead to applications as piezoresistive graphene membrane-based sensors. While the fundamental properties of graphene apparently make it an ideal candidate for such applications, in reality one has to deal with a number of parasitic effects that can influence and falsify the response of a graphene sensor. This talk aims to carefully balance the discussion about the merits and disadvantages of graphene-based sensors based on experimental data.
Laser Annealing of 2D Material-based Inks
Time: 2015.10.28 16:25-16:50
This presentation will discuss a laser annealing technique for the fabrication of large-area graphene-based transparent thin film conductors. The graphene ink was produced by a liquid phase exfoliation (LPE) method through exfoliating graphite powders in dimethylformamide (DMF), stabilizing the obtained graphene flakes with polymers, and finally exchanging DMF by terpineol to increase graphene concentration, adjust ink viscosity, and reduce solvent toxicity. The ink was deposited on substrates by drop casting and then annealed to remove stabilizing polymers. Subsequently, a laser beam was scanned across the film. While the drop casted films are highly resistive, the laser treatment results in sheet resistances on the order of 30kΩ/sq. Meanwhile, the transmittance of the films increases from 60% to more than 85% (at λ = 550 nm). Furthermore, Raman data indicate that by laser annealing the films, both the FWHM of the Raman G band and the integrated intensity ratio of the D band to the G band decrease significantly. This confirms that the laser treatment reduces structural disorder within the graphene flakes. AFM and SEM images show topography changes in the films after laser treatment, which have a significantly more homogenous and smooth surface on the order of 10 nm roughness. The method also improves the resistivity and transparency of inkjet printed graphene films. The final part of the presentation will be dedicated to laser annealing of 2D materials other than graphene.
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