SAMOP 2021 – wissenschaftliches Programm

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SYAD: Symposium SAMOP Dissertation Prize 2021

SYAD 1: SAMOP Dissertation Prize

SYAD 1.1: Hauptvortrag

Dienstag, 21. September 2021, 10:45–11:15, Audimax

Attosecond-fast electron dynamics in graphene and graphene-based interfaces — •Christian Heide — Friedrich-Alexander Universität Erlangen-Nürnberg, D-91058 Erlangen

’How fast can one turn on a current?’ is an important question behind boosting up the speed of electronics. Graphene is a promising material for light-field-driven electronics. Under the influence of a strong optical field, intraband motions and interband transitions in graphene are intricately coupled. In the extreme case, this leads to Landau-Zener transitions from the valence to the conduction band. In the reciprocal space, the momentum of an electron changes due to acceleration by the electric field. When the electron passes the Dirac point, where both bands are strongly coupled, the wave function of the electron is coherently split into a superposition of the two band states. After half an optical cycle of about 1.3 femtoseconds, these parts of the wave function meet again and interfere, turning on a current. Within my dissertation, we have measured this current and demonstrated that its amplitude and phase is controllable by the waveform of the laser pulse.

Furthermore, we show that graphene, grown on silicon carbide exhibits charge transfer from one material to another within 300 attoseconds. The reason for the extremely short charge transfer time is the combination of the materials used: the atomically thin graphene with excited electrons directly at the interface and the extended semiconductor, which is ideally suited to capture excited electrons.

Both results are important steps towards light-field-driven electronics.

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