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O: Fachverband Oberflächenphysik
O 74: Focus Session: Growth, Properties and Application of Epitaxial Graphene (joint session DS/HL/O)
O 74.2: Vortrag
Donnerstag, 4. April 2019, 10:00–10:15, H32
Uniform large-scale quasi-freestanding monolayer and bilayer graphene on SiC — Davood Momeni Pakdehi1, •Klaus Pierz1, Stefan Wundrack1, Johannes Aprojanz2, T.T. Nhung Nguyen3, Thorsten Dziomba1, Frank Hohls1, Andrey Bakin4,5, Rainer Stosch1, Christoph Tegenkamp2,3, Franz J Ahlers1, and Hans. W. Schumacher1 — 1Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig — 2Institut für Festkörperphysik, LU Hannover, Appelstraße 2, 30167 Hannover — 3Institut für Physik, TU Chemnitz, Reichenhainer Straße 70, 09126 Chemnitz — 4Institut für Halbleitertechnik, TU Braunschweig, 38106 Braunschweig, — 5Laboratory of Emerging Nanometrology, TU Braunschweig, 38106 Braunschweig
Epitaxial graphene growth is often accompanied by step bunching of the underlying SiC substrate and graphene bilayer formation which can deteriorate the quality of graphene-based devices, e.g., the resistance quantization of the quantum Hall effect. We show AFM, STM, Raman and electronic transport data which indicate that improved buffer layer growth is the key to obtain homogenous large-area monolayer graphene. Particularly, the substantial impact of the so-far less regarded Ar flow rate on the graphene quality is investigated in this study and explained by a quasi-equilibrium model at the growing surface. The quality of our ultra-smooth graphene layers is proven by the high uniformity of quasi-freestanding graphene sheets obtained by hydrogen intercalation which is underlined by the very small resistance anisotropy of such samples on um and mm scales.