Kastorp Claus F P, Duncan David A, Scheffler Martha, Thrower John D, Jørgensen Anders L, Hussain Hadeel, Lee Tien-Lin, Hornekær Liv, Balog Richard
Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
Nanoscale. 2020 Oct 14;12(38):19776-19786. doi: 10.1039/d0nr04788k. Epub 2020 Sep 23.
Interesting electronic properties arise in vertically stacked graphene sheets, some of which can be controlled by mutual orientation of the adjacent layers. In this study, we investigate the MBE grown multilayer graphene on Ir(111) by means of STM, LEED and XPS and we examine the influence of the substrate on the geometric and electronic properties of bilayer graphene by employing XSW and ARPES measurements. We find that the MBE method does not limit the growth to two graphene layers and that the wrinkles, which arise through extended carbon deposition, play a crucial role in the multilayer growth. We also find that the bilayer and trilayer graphene sheets have graphitic-like properties in terms of the separation between the two layers and their stacking. The presence of the iridium substrate imposes a periodic potential induced by the moiré pattern that was found to lead to the formation of replica bands and minigaps in bilayer graphene. From tight-binding fits to our ARPES data we find that band renormalization takes place in multilayer graphene due to a weaker coupling of the upper-most graphene layer to the iridium substrate.
垂直堆叠的石墨烯片会呈现出有趣的电子特性，其中一些特性可通过相邻层的相互取向来控制。在本研究中，我们借助扫描隧道显微镜（STM）、低能电子衍射（LEED）和X射线光电子能谱（XPS）研究了在铱（111）上通过分子束外延（MBE）生长的多层石墨烯，并通过X射线驻波（XSW）和角分辨光电子能谱（ARPES）测量来考察衬底对双层石墨烯几何和电子特性的影响。我们发现，MBE方法并不将生长限制在两层石墨烯，并且通过长时间碳沉积产生的褶皱在多层生长中起着关键作用。我们还发现，双层和三层石墨烯片在两层之间的间距及其堆叠方面具有类似石墨的特性。铱衬底的存在施加了由莫尔图案诱导的周期性势，这被发现会导致双层石墨烯中形成复制带和微带隙。通过对我们的ARPES数据进行紧束缚拟合，我们发现由于最上层石墨烯层与铱衬底的耦合较弱，多层石墨烯中发生了能带重整化。
