Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 33: Poster Graphene: Electronic Structure and Excitations
O 33.20: Poster
Dienstag, 18. März 2025, 13:30–15:30, P3
Influence of doping on non-equilibrium carrier dynamics in graphene — •Leonard Weigl1, Johannes Gradl1, Peter Richter2, Thomas Seyller2, Camilla Coletti3, and Isabella Gierz1 — 1University of Regensburg, Germany — 2Technical University of Chemnitz, Germany — 3Instituto Italiano di Tecnologia, Pisa, Italy
The understanding of non-equilibrium charge carrier dynamics in the quasi-relativistic dispersion of graphene is a key ingredient for the design of future ultrafast electronic devices. Despite its crucial importance for device operation, the role of the doping level remains controversial. Here, we use time- and angle-resolved photoemission spectroscopy (tr-ARPES) to study the energy-resolved photo-carrier relaxation in epitaxial graphene for different doping levels. In contrast to previous studies on the same material [1], we find the energy-resolved relaxation times to be independent of doping. We attribute this to the fact that - with increasing doping level - the peak electronic temperature is found to decrease, making the phase space for carrier relaxation doping-independent. Therefore, we speculate that the previously observed differences in carrier dynamics between graphene resting on C- and H-terminated SiC substrates, respectively, originate from the different interfaces to the substrate rather than the doping level. [1] J. C. Johannsen et al., Nano Lett. 15, 326-331 (2014)
Keywords: Graphene; tr-ARPES; Doping; Relaxation; Dynamics