Metal catalyzed synthesis of graphene for the preparation of membranes with highest perfection at the atomic scale

自从石墨烯通过微机械裂解分离以来，这种新材料不仅因为其独特的电子特性，而且因为其巨大的弹性模量和固有强度等机械特性而引起了人们的极大关注。石墨烯优异的机械稳定性允许构建超强膜，当厚度充分减小时，即使对于低能电子，也可以变成电子透明窗口。由于对于这样的应用，需要大尺寸和最高结晶质量的石墨烯薄片，我们将探索如何通过金属催化制备路线以合理的生长速度生长无缺陷石墨烯。特别是，我们将使用原位STM、基于UHV的技术（LEED、AES和最终的XPS）和原位LEEM / SPELEEM测量来跟踪和优化Ru（0001）和Cu衬底（单晶和多晶箔）上的石墨烯生长。在这里，我们特别强调了衬底重构效应，以及通过增加准备步骤来优化CVD工艺，从而修复石墨烯层内部存在的缺陷。我们将进一步探索剥离技术，这将使我们能够轻轻地将石墨烯膜从支撑表面分离。在这里，原位LEEM研究计划。Cu的原位生长实验将结合我们建立的石墨烯生长CVD工艺，该工艺在自制反应器中进行，并在mbar范围内的压力下运行。在未来的实验中，我们希望调整CVD工艺，以便在Cu衬底上生长大的单晶石墨烯薄片。对于生长的石墨烯膜的质量控制，我们将应用几种额外的非原位技术（拉曼光谱、SEM、非原位XPS和光学显微镜）。我们将进一步研究的增长，在一个联合的高压-特高压为基础的LEEM研究。最后，生长的石墨烯将用于构建电子透明窗口，其将通过同步加速器研究中的光谱光电发射和低能电子显微镜（SPELEEM）和扫描光电子显微镜（SPEM）进行表征。由于结晶质量和两者的密切关系，所产生的电子和机械性质，用于形成无缺陷石墨烯的改进的制备方案对于其他基础研究或未来基于石墨烯的应用将是令人感兴趣的。

Since the isolation of graphene by micromechanical cleavage this new material has attracted tremendous attention not only because of its unique electronic but also because of its mechanical properties, such as the huge elastic module and intrinsic strength. The exceptional mechanical stability of graphene allows the construction of ultra strong membranes which, when sufficiently reduced in thickness, can be turned into electron transparent windows even for low energy electrons. Since for such an application, graphene flakes of large size and highest crystalline quality are required, we will explore how defect free graphene can be grown via metal catalyzed preparation routes at reasonable growth speed. In particular, we will follow and optimize the graphene growth on Ru(0001) and on Cu substrates (single crystals and polycrystalline foils) using in situ STM, UHV based techniques (LEED, AES and eventually XPS) and in situ LEEM / SPELEEM measurements. Here, especially substrate restructuring effects are addressed as well as the optimization of the CVD process by adding preparation steps that allow the healing of defects present inside the graphene layer.We will further explore lift-off techniques, which will enable us to gently detach the graphene films from the support surface. Here, in situ LEEM studies are planned.The in situ growth experiments on Cu will be combined to our established CVD process for graphene growth, which is performed in a home built reactor and which is run at pressures in in the mbar range. In future experiments we want to tune the CVD process in order to grow large, single crystalline graphene flakes on Cu substrates. For the quality control of the grown graphene films we will apply several additional ex situ techniques (Raman spectroscopy, SEM, ex situ XPS and optical microscopy). We will further study the growth in a combined high pressure - UHV based LEEM study. Finally, the grown graphene will be used to construct electron transparent windows, which will be characterized by Spectroscopic Photoemission and Low Energy Electron Microscopy (SPELEEM) and Scanning Photoelectron Microscopy (SPEM) in synchrotron studies. Due to the close relation of crystalline quality and both, the resulting electronic and mechanical properties, an improved preparation protocol for the formation of defect free graphene will be interesting for other fundamental studies or future graphene based applications.