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Epitaxial Graphene and Graphene–Based Devices Studied by Electrical Scanning Probe Microscopy
National Physical Laboratory, Teddington TW11 0LW, UK
Royal Holloway University of London, Egham TW20 0EX, UK
Material Science Centre, University of Manchester, Manchester M1 7HS, UK
* Author to whom correspondence should be addressed.
Received: 10 December 2012; in revised form: 17 February 2013 / Accepted: 26 February 2013 / Published: 13 March 2013
(This article belongs to the Special Issue Graphenes
Abstract: We present local electrical characterization of epitaxial graphene grown on both Si- and C-faces of 4H-SiC using Electrostatic Force Microscopy and Kelvin Probe Force Microscopy in ambient conditions and at elevated temperatures. These techniques provide a straightforward identification of graphene domains with various thicknesses on the substrate where topographical determination is hindered by adsorbates and SiC terraces. We also use Electrostatic Force Spectroscopy which allows quantitative surface potential measurements with high spatial resolution. Using these techniques, we study evolution of a layer of atmospheric water as a function of temperature, which is accompanied by a significant change of the absolute surface potential difference. We show that the nanoscale wettability of the material is strongly dependent on the number of graphene layers, where hydrophobicity increases with graphene thickness. We also use micron-sized graphene Hall bars with gold electrodes to calibrate work function of the electrically conductive probe and precisely and quantitatively define the work functions for single- and double-layer graphene.
Keywords: epitaxial graphene; SiC; adsorbates; Kelvin Probe Force Microscopy (KPFM); Electrostatic Force Microscopy (EFM); surface potential; work function; wettability
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MDPI and ACS Style
Kazakova, O.; Panchal, V.; Burnett, T.L. Epitaxial Graphene and Graphene–Based Devices Studied by Electrical Scanning Probe Microscopy. Crystals 2013, 3, 191-233.
Kazakova O, Panchal V, Burnett TL. Epitaxial Graphene and Graphene–Based Devices Studied by Electrical Scanning Probe Microscopy. Crystals. 2013; 3(1):191-233.
Kazakova, Olga; Panchal, Vishal; Burnett, Tim L. 2013. "Epitaxial Graphene and Graphene–Based Devices Studied by Electrical Scanning Probe Microscopy." Crystals 3, no. 1: 191-233.