Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 3: Graphene: Magnetic Fields (jointly with DS, HL, MA, and TT)

O 3.6: Vortrag

Montag, 11. März 2013, 10:45–11:00, H17

Quantum Hall measurements on epitaxial graphene with oxygen adsorption — •Emiliano Pallecchi¹, Mohamed Ridene¹, Dimitris Kazazis¹, Felicien Schopfer², Wilfrid Poirier², Mark Goergig³, and Abdelkarim Ouerghi¹ — ¹Laboratoire de Photonique et de Nanostructures (LPN-CNRS), 91460 Marcoussis, France — ²Laboratoire National de Métrologie et d’Essais, 78197 Trappes — ³Laboratoire des Physique de Solides, F-91505, Orsay

In this contribution we present quantum transport, ARPES, and LEED investigations of molecular oxygen-adsorbed epitaxial graphene grown on SiC. We show that the carrier concentration can be significantly reduced by exposing the sample to molecular oxygen. From Hall measurements we obtain a carrier concentration on the order of 1.2 x 10¹² cm⁻², about one order of magnitude smaller than typical values of intrinsic epitaxial graphene. The reduction of electron doping is consistent with estimates from ARPES measurements. At high magnetic field, we find a fully developed quantum Hall effect, with a plateau at filling factor around 2, and a vanishing longitudinal resistance. Such a plateau is the hallmark of single layer graphene and suggests that the buffer layer is not fully decoupled from the substrate. This is further confirmed by LEED study. We then discuss the intermediate field regime, where we analyze the transition between a localized state observed at low fields and the quantum Hall regime at high fields. Finally, we compare these findings to the results obtained on epitaxial graphene exposed to atomic oxygen. We find that atomic oxygen is a more violent process that can damage significantly the graphene flake.