Dresden 2017 – scientific programme
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O: Fachverband Oberflächenphysik
O 86: Graphene: Electronic Properties, Structure and Substrate Interaction I
O 86.8: Talk
Thursday, March 23, 2017, 12:15–12:30, WIL A317
Lifting Graphene by Alkali Intercalation — •Caio Silva1, Jiaqi Cai1, Wouter Jolie2, Daniela Dombrowski1,2, Ferdinand Farwick zum Hagen2, Antonio Martínez-Galera2, Christoph Schlueter3, Tien-Lin Lee3, and Carsten Busse1,2 — 1Institut für Materialphysik, Münster, Germany — 2II. Physikalisches Institut, Köln, Germany — 3Diamond Light Source Ltd, Didcot, United Kingdom
Intercalation is a versatile tool to tune the properties of graphene grown epitaxially on metal surfaces. Especially alkali metals are efficient to decouple graphene from its substrate and, in addition, induce a strong n-doping on graphene.
In the present work, we used the x-ray standing wave (XSW) techinique to compare the structures resulting from intercalation of a small (Li) and a rather large (Cs) alkali metal between graphene and Ir(111). We noted an opposing behavior during deintercalation: In the case of Cs, different phases [(√3 × √3)R30Ir∘, (2 × 2)gr] coexist, each with a characteristic height of graphene with respect to Ir(111), as revealed by XSW. In the case of Li, however, we find just a single phase of gr/Li/Ir(111) for a wide range of intercalant coverage (1 - 0.2 ML), with a distance between the graphene sheet and the metal surface that is independent on the amount of Li intercalated in between. We explain the contrast between Li and Cs by differences in the delamination energy that has to be paid in order to intercalate the different species.