Central facility for investigations of growth, structure, and electronic properties of graphene using low-energy electron microscopy (LEEM)

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The development of graphene-based devices is dependent on the availability of high quality graphene layers. Several competing methods for the synthesis of graphene are investigated within the central project Graphene. Among them are the thermally activated growth on silicon carbide surfaces, chemical vapor deposition (CVD) on metal surfaces, thermal conversion of self-assembled monolayers, and molecular beam epitaxy (MBE). A prerequisite for success is a thorough characterization of structural and electronic properties of the resulting layers. Surface science techniques such as photoelectron spectroscopy (XPS, ARPES), low-energy electron diffraction (LEED), and scanning tunneling microscopy (STM) and spectroscopy (STS) are excellently suited for studying the properties of graphene on either large scale or atomic scale. Low-energy electron microscopy (LEEM) is a suitable method to study structural and electronic properties of graphene layers on length scales ranging from a few tens of micrometers down to a few tens of nanometers with a spatial resolution of 5 nm. LEEM is fast compared to STM and can also be used for in-situ studies of the growth of graphene. Recent work shows that LEEM is an indispensable method for the development of growth processes for graphene. A LEEM system was consequently installed during the first funding period of the SPP. Here we seek funds for a continuation of this project. In that project we will continue to investigate the growth and manipulation of graphene on SiC surfaces, and provide access to the LEEM setup to users from the SPP.In the field of graphene on SiC we will focus on the optimization of growth conditions for epitaxial graphene on Si-face SiC, on the analysis of dislocations in graphene, on the rotational disorder in multilayer graphene on C-face SiC, and on the growth of graphene on non-polar SiC surfaces. In addition we will study the growth of molecular overlayers on graphene on SiC which is an interesting tool for the precise control over the charge carrier type and density in graphene. We will provide access to the LEEM instrument and support to several groups. Together with U. Starke (MPI für Festkörperforschung) we will study the formation of graphene ribbons on patterned SiC surfaces. In collaboration with J. Wintterlin (LMU München) we will investigate the growth of graphene on metal substrates. The growth of graphene/h-BN heterostructures will be investigated together with C. Busse (Universität Köln) and we will collaborate with J. M. Lopes and A. Hernandez-Minguez (PDI Berlin) on the growth of graphene by MBE and by thermal decomposition of SiC. Finally, we will investigate the growth of graphene on diamond surfaces in collaboration with C. Nebel (Fraunhofer IAF, Freiburg).