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Electrical Characterizationon Commercially Available Chemical Vapor Deposition (CVD) Graphene
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Electron microscopy & Nanoengineering)
2016 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Field-effect transistors (FET) based on graphene as channel has extraordinaryproperties in terms of charge mobility, charge carrier density etc. However, there aremany challenges to graphene based FET due to the fact graphene is a monolayer ofatoms in 2-dimentional space that is strongly influenced by the operating conditions.One issue is that the Dirac point, or K-point, shifts to higher gate voltage whengraphene is exposed to atmosphere. In this study graphene field-effect transistors(GFET) based on commercially available CVD graphene are electrically characterizedthrough field effect gated measurements. The Dirac point is initially unobservable andlocated at higher gate voltages (>+42 V), indicating high p-doping in graphene.Different treatments are tried to enhance the properties of GFET devices, such astransconductance, mobility and a decrease of the Dirac point to lower voltages, thatincludes current annealing, vacuum annealing, hot plate annealing, ionized water bathand UV-ozone cleaning. Vacuum annealing and annealing on a hot plate affect thegated response; they might have decreased the overall p-doping, but also introducedDirac points and non-linear features. These are thought to be explained by localp-doping of the graphene under the electrodes. Thus the Dirac point of CVDgraphene is still at higher gate voltages. Finally, the charge carrier mobility decreasedin all treatments except current – and hot plate annealing, and it is also observed that charge carrier mobilities after fabrication are lower than the manufacturer estimatesfor raw graphene on SiO2/Si substrate.

Place, publisher, year, edition, pages
2016. , 37 p.
UPTEC Q, ISSN 1401-5773 ; 16008
Keyword [en]
GFET, Graphene, Dirac point shift, Charge carrier mobility
National Category
Nano Technology
URN: urn:nbn:se:uu:diva-298357OAI: oai:DiVA.org:uu-298357DiVA: diva2:945880
Educational program
Master Programme in Materials Engineering
2016-06-13, Å2003, Regementsvägen 1, Uppsala, 15:15 (English)
Available from: 2016-07-05 Created: 2016-07-04 Last updated: 2016-07-05Bibliographically approved

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Anttila-Eriksson, Mikael
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