Celis A, Nair M N, Sicot M, Nicolas F, Kubsky S, Taleb-Ibrahimi A, Malterre D, Tejeda A
Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France.
Nanotechnology. 2020 Apr 24;31(28):285601. doi: 10.1088/1361-6528/ab866a. Epub 2020 Apr 3.
Superlattice induced minigaps in graphene band structure due to underlying one-dimensional nanostructuration has been demonstrated. A superperiodic potential can be introduced in graphene if the substrate is periodically structured. The successful preparation of a periodically nanostructured substrate in large scale can be obtained by carefully studying the electronic structure with a spatial averaging technique such as high-energy resolution photoemission. In this work, we present two different growth methods such as temperature programmed growth (TPG) and chemical vapor deposition (CVD) studied by scanning tunnelling microscopy (STM) and low energy electron diffraction (LEED). In both methods, we show that the original steps of Ir(332) have modified with (111) terraces and step bunching after graphene growth. Graphene grows continuously over the terrace and the step bunching areas. We observe that while TPG growth does not give rise to a well-defined surface periodicity required for opening a bandgap, the CVD growth does. By combining with angle-resolved photoemission spectroscopy (ARPES) measurements, we correlate the obtained spatial periodicity to observed band gap opening in graphene.
已经证明，由于底层的一维纳米结构，超晶格会在石墨烯能带结构中诱导出微带隙。如果衬底是周期性结构的，那么就可以在石墨烯中引入超周期势。通过使用诸如高能分辨率光电子能谱等空间平均技术仔细研究电子结构，能够大规模成功制备周期性纳米结构衬底。在这项工作中，我们展示了两种不同的生长方法，即程序升温生长（TPG）和化学气相沉积（CVD），并通过扫描隧道显微镜（STM）和低能电子衍射（LEED）进行了研究。在这两种方法中，我们都表明，在石墨烯生长后，Ir(332)的原始台阶已被(111)平台和台阶聚集所改变。石墨烯在平台和台阶聚集区域上连续生长。我们观察到，虽然程序升温生长不会产生打开带隙所需的明确表面周期性，但化学气相沉积生长会产生。通过结合角分辨光电子能谱（ARPES）测量，我们将获得的空间周期性与石墨烯中观察到的带隙打开相关联。
