Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 19: Graphene: Structural properties
O 19.5: Vortrag
Montag, 31. März 2014, 17:00–17:15, WIL C107
Ion Irradiation of Metal-Supported Graphene: Exploring the Role of the Substrate — •Charlotte Herbig1, Harriet Åhlgren2, Sabina Simon1, Carsten Busse1, Jani Kotakoski2, 3, Arkady V. Krasheninnikov2, 4, and Thomas Michely1 — 1II. Phys. Inst., Universität zu Köln, Germany — 2Dept. of Phys., University of Helsinki, Finland — 3Faculty of Phys., University of Vienna, Austria — 4Dept. of Appl. Phys., Aalto University, Finland
Ion irradiation effects on 2D materials are an emerging subject, triggered by graphene's (Gr) potentials in applications. For supported Gr the effect of the substrate on ion beam damage and annealing is important. We investigate the behavior of high quality Gr, weakly coupled to Ir(111), to low energy noble gas ion irradiation by scanning tunneling microscopy (STM), molecular dynamics simulations, and density functional theory (DFT). For a freestanding layer, sputtered atoms leave the layer either in forward or backward direction. For metal-supported Gr, only C atoms carrying backward momentum are sputtered while atoms carrying forward momentum are trapped. As evident from STM and DFT, trapped C atoms form nm-sized Gr platelets at the interface upon annealing at 1000K, assisted by substrate defects. The incorporation into the Gr layer is suppressed due to high migration barriers, while diffusion into the Ir is energetically unfavorable. By measuring the area fraction of the platelets, we obtain the trapping yield, i.e., the number of trapped C atoms per incident ion. Interestingly, compared to the sputtering yield, the trapping yield for Gr on Ir(111) displays a distinctly different dependence on the ion beam angle of incidence.