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

基于石墨烯的器件的发展依赖于高质量石墨烯层的可用性。在中心项目石墨烯中，对几种合成石墨烯的竞争方法进行了研究。其中包括碳化硅表面的热激活生长、金属表面的化学气相沉积(CVD)、自组装单分子膜的热转化和分子束外延(MBE)。成功的先决条件是对所得到的层的结构和电子性质进行彻底的表征。光电子能谱(XPS，ARPES)、低能电子衍射(LEED)、扫描隧道显微镜(STM)和光谱学(STS)等表面科学技术非常适合于在大尺度或原子尺度上研究石墨烯的性质。低能电子显微镜(LEEM)是一种适合研究石墨烯薄膜结构和电子性质的方法，其长度范围从几十微米到几十纳米，空间分辨率为5 nm。与STM相比，LEEM速度更快，也可用于石墨烯生长的原位研究。最近的工作表明，LEEM是开发石墨烯生长过程中不可或缺的方法。因此，在战略计划的第一个供资期间安装了LEEM系统。我们在这里为这个项目的继续寻求资金。在该项目中，我们将继续研究石墨烯在碳化硅表面的生长和操纵，并为用户提供从SP到LEEM装置的途径。在石墨烯在碳化硅表面上的生长方面，我们将重点关注在硅面碳化硅上外延石墨烯的生长条件的优化，石墨烯中位错的分析，C面碳化硅上多层石墨烯的旋转无序，以及非极性碳化硅表面上石墨烯的生长。此外，我们还将研究石墨烯在碳化硅上的分子覆盖层的生长，这是精确控制石墨烯中载流子类型和密度的一个有趣的工具。我们将提供使用LEEM仪器的机会，并向几个小组提供支持。我们将与U·斯塔克(MPI für FestkörPersonschung)一起研究在有图案的碳化硅表面上石墨烯的形成。与J·温特林(LMU München)合作，我们将研究石墨烯在金属衬底上的生长。我们将与C.Busse一起研究石墨烯/h-BN异质结构的生长，我们将与J.M.Lope和A.Hernandez-Mguez(PDI柏林)合作，通过分子束外延和碳化硅的热分解来生长石墨烯。最后，我们将与C.Nebel(弗劳恩霍夫宇航联合会，弗赖堡)合作，研究石墨烯在钻石表面的生长。

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).