We present Kelvin probe force microscopy measurements of single-and few-layer graphene resting on SiO2 substrates. We compare the layer thickness dependency of the measured surface potential with ab initio density functional theory calculations of the work function for substrate-doped graphene. The ab initio calculations show that the work function of single-and bilayer graphene is mainly given by a variation of the Fermi energy with respect to the Dirac point energy as a function of doping, and that electrostatic interlayer screening only becomes relevant for thicker multilayer graphene. From the Raman G-line shift and the comparison of the Kelvin probe data with the ab initio calculations, we independently find an interlayer screening length in the order of four to five layers. Furthermore, we describe in-plane variations of the work function, which can be attributed to partial screening of charge impurities in the substrate, and result in a nonuniform charge density in single-layer graphene.

Variations in the work function of doped single- and few-layer graphene assessed by Kelvin probe force microscopy and density functional theory / Ziegler, D.; Gava, P.; Guettinger, J.; Molitor, F.; Wirtz, L.; Lazzer, M.; Saitta, A. M.; Stemmer, A.; Mauri, F.; Stampfer, C.. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 83:23(2011). [10.1103/PhysRevB.83.235434]

Variations in the work function of doped single- and few-layer graphene assessed by Kelvin probe force microscopy and density functional theory

Mauri F.;
2011

Abstract

We present Kelvin probe force microscopy measurements of single-and few-layer graphene resting on SiO2 substrates. We compare the layer thickness dependency of the measured surface potential with ab initio density functional theory calculations of the work function for substrate-doped graphene. The ab initio calculations show that the work function of single-and bilayer graphene is mainly given by a variation of the Fermi energy with respect to the Dirac point energy as a function of doping, and that electrostatic interlayer screening only becomes relevant for thicker multilayer graphene. From the Raman G-line shift and the comparison of the Kelvin probe data with the ab initio calculations, we independently find an interlayer screening length in the order of four to five layers. Furthermore, we describe in-plane variations of the work function, which can be attributed to partial screening of charge impurities in the substrate, and result in a nonuniform charge density in single-layer graphene.
2011
fisica
01 Pubblicazione su rivista::01a Articolo in rivista
Variations in the work function of doped single- and few-layer graphene assessed by Kelvin probe force microscopy and density functional theory / Ziegler, D.; Gava, P.; Guettinger, J.; Molitor, F.; Wirtz, L.; Lazzer, M.; Saitta, A. M.; Stemmer, A.; Mauri, F.; Stampfer, C.. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 83:23(2011). [10.1103/PhysRevB.83.235434]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1335996
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