Regensburg 2019 – scientific programme

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O: Fachverband Oberflächenphysik

O 14: Graphene II: Excitations and Nanoribbons (joint session O/TT)

O 14.1: Talk

Monday, April 1, 2019, 15:00–15:15, H24

Altering the lattice dynamics of graphene by hot-electron injection — •Marcel Weinhold, Sangam Chatterjee, and Peter J. Klar — Institute of Experimental Physics I and Center for Materials Research (LaMa), Justus Liebig University Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen

Graphene is discussed as material for next-generation (opto-)electronic devices. Among others, this is due to its exceptional properties including a large electron mobility, vast mechanical flexibility and durability, and its matchless linear and gap-less band structure. By combining graphene with metallic nanostructures that feature plasmonic characteristics its intrinsic properties can be tuned significantly. Those nanostructures lead to a near-field confinement of the incident light due to the excitation of localized surface plasmons (LSP). Further, LSPs decay non-radiatively into energy-rich electron-hole pairs. These ’hot-carriers’ may be injected into the graphene and lead to a doping. However, plasmonic properties are very sensitive to geometry and dielectric environment. Therefore, single particle measurements are crucial for gaining further insights into the underlying physics. Here, we study the injection of hot-electrons in a model system, i.e., a single gold nanoparticle on a monolayer graphene substrate. We show that the injection of hot-electrons into graphene induces a quantifiable altering of graphene’s phonon dispersion relation using specially resolved micro-Raman spectroscopy. In addition, we present an analysis procedure yielding further information on occurring temperature and strain distributions solely from the measured Raman shift maps.