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

自石墨烯被微机械解理分离以来，这种新材料不仅因其独特的电子特性，而且因其巨大的弹性模量和固有强度等力学性能而受到广泛关注。石墨烯优异的机械稳定性使其能够制造出超强的薄膜，当其厚度充分减小时，即使对于低能电子，也可以变成电子透明窗口。由于这种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的石墨烯。特别是，我们将跟踪和优化石墨烯在Ru（0001）和Cu衬底（单晶和多晶箔）上的生长，使用原位STM，基于特高压的技术（LEED， AES和最终的XPS）和原位LEEM / SPELEEM测量。在这里，特别是衬底重组效应，以及通过增加制备步骤来优化CVD工艺，使石墨烯层内的缺陷得以愈合。我们将进一步探索升空技术，这将使我们能够轻轻地从支撑表面分离石墨烯薄膜。在这里，就地LEEM研究计划。铜的原位生长实验将与我们建立的石墨烯生长CVD工艺相结合，该工艺在自制反应器中进行，压力在毫巴范围内。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片。对于生长的石墨烯薄膜的质量控制，我们将应用几种额外的非原位技术（拉曼光谱、扫描电镜、非原位XPS和光学显微镜）。我们将进一步研究高压-特高压联合LEEM研究的增长。最后，生长的石墨烯将用于构建电子透明窗口，并将在同步加速器研究中使用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）对其进行表征。由于晶体质量与两者的密切关系，由此产生的电子和机械性能，形成无缺陷石墨烯的改进制备方案将对其他基础研究或未来基于石墨烯的应用产生兴趣。

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.