Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 52: Graphene II
O 52.4: Talk
Wednesday, March 24, 2010, 15:45–16:00, H31
Defect-induced electron scattering and metal-insulator transition in graphene — Aaron Bostwick1, Jessica McChesney1,2, Konstantin Emtsev3, Thomas Seyller3, •Karsten Horn2, Stephen D. Kevan4, and Eli Rotenberg1 — 1Advanced Light Source, Lawrence Berkeley Lab, California USA — 2Fritz-Haber-Institut der MPG, Berlin — 3Institut für Physik der Kondensierten Materie, Universität Erlangen — 4Department of Physics, University of Oregon, USA
The influence of adsorbate-induced defects on the electronic properties of graphene are of great current interest. Here we show, using angle-resolved photoemission and conductivity measurements, that potassium and hydrogen adsorption on graphene induce very different types of defects in graphene prepared on SiC(0001). Whereas potassium acts as an electron donor, but causes only weak defect scattering, hydrogen locally saturates a carbon bond. This acts as a lattice defect, leading to a sharp reduction in conductivity, by several orders of magnitude even for coverages below 1 % of a monolayer. Angle-resolved photoemission spectra reveal a concomitant change in the electron scattering rate and the dispersion of the graphene bands near the Fermi level. These changes are interpreted in terms of a breakdown of the quasiparticle picture and strong charge carrier localization through the hydrogen-induced defects.