Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 67: Ultrafast Electron Dynamics II
O 67.11: Vortrag
Mittwoch, 19. März 2025, 17:30–17:45, H11
Influence of carbon buffer layer on non-equilibrium carrier dynamics of epitaxial graphene on SiC(0001) — •Johannes Gradl1, Leornard Weigl1, Neeraj Mishra2,3, Stiven Forti2, Camilla Coletti2,3, and Isabella Gierz1 — 1University of Regensburg, Germany — 2Istituto Italiano di Tecnologia, Pisa, Italy — 3Istituto Italiano di Tecnologia, Genova, Italy
The carbon buffer layer resting at the interface between epitaxial graphene and SiC(0001) substrate is believed to be electronically dead with two non-dispersing bands located well below the Fermi level [1]. We use time- and angle-resolved photoemission spectroscopy (trARPES) to show that this picture breaks down away from thermal equilibrium and on ultrafast time scales. We find that photo-doping of the graphene - buffer layer heterostructure increases the carrier concentration inside the Dirac cone. Supported by pump fluence and pump wavelength dependent measurements we attribute this transient charging to direct electronic transitions between the buffer layer and the graphene layer and subsequent relaxation of the non-equilibrium charge carrier distribution. [1] Phys. Rev. B 77, 155303 (2008)
Keywords: ultrafast; graphene; trARPES; heterostructure