Oxygen Switching of the Epitaxial Graphene-Metal Interaction
Oxygen Switching of the Epitaxial Graphene-Metal Interaction
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DOI：
10.1021/nn302729j
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发表时间：
2012-11-01
期刊：
影响因子：
17.1
通讯作者：
Lizzit, Silvano
中科院分区：
文献类型：
--
作者：
Larciprete, Rosanna;Ulstrup, Soren;Lizzit, Silvano
利用光电子能谱技术，我们...示出了在Ir（111）上的外延石墨烯的延伸层上实现氧嵌入，这导致石墨烯层的“提升”以及其与金属衬底的解耦。石墨烯下方的氧吸附与干净的Ir（111）上的一样进行，仅给出略高的氧覆盖率。在提升时，由于电荷从氧覆盖的金属表面转移到石墨烯，C1 s信号显示结合能的下移。此外，石墨烯-衬底相互作用在价带中的特征光谱特征被去除，并且观察到强空穴掺杂的、准独立的石墨烯的光谱，其在（K）过棒点周围具有单个狄拉克锥。氧可以通过退火脱嵌，并且该过程在T = 600 K左右以相当突然的方式发生。少量的碳原子丢失，这意味着石墨烯已经被蚀刻。脱嵌后，石墨烯恢复其与Ir（111）衬底的相互作用。在较低的氧剂量和温度下容易发生额外的嵌入/脱嵌循环，这与缺陷越来越多的晶格一致。我们的研究结果表明，氧插层是一种有效的方法，用于从金属衬底（如Ir（111））上完全解耦石墨烯的扩展层。它们为石墨烯的基础研究铺平了道路，其中延伸的、有序的自支撑石墨烯层非常重要，并且由于插层系统在宽温度范围内的稳定性，也有利于石墨烯电子学的进步。
Using photoemission spectroscopy techniques, we.. show that oxygen intercalation is achieved on an extended layer of epitaxial graphene on Ir(111), which results in the "lifting' of the graphene layer and In its decoupling from the metal substrate. The oxygen adsorption below graphene proceeds as on clean Ir(111), giving only a slightly higher oxygen coverage. Upon lifting, the C 1s signal shows a downshift In binding energy, due to the charge transfer to graphene from the oxygen-covered metal surface. Moreover, the characteristic spectral signatures of the graphene-substrate interaction In the valence band are removed, and the spectrum of strongly hole-doped, quasi free-standing graphene with a single Dirac cone around the (K) over bar point Is observed. The oxygen can be deintercalated by annealing, and this process takes place at around T = 600 K, in a rather abrupt way. A small amount of carbon atoms is lost, implying that graphene has been etched. After deintercalation graphene restores its interaction with the Ir(111) substrate. Additional intercalation/deintercalation cycles readily occur at lower oxygen doses and temperatures, consistently with an increasingly defective lattice. Our findings demonstrate that oxygen Intercalation is an efficient method for fully decoupling an extended layer of graphene from a metal substrate, such as Ir(111). They pave the way for the fundamental research on graphene, where extended, ordered layers of free-standing graphene are important and, due to the stability of the intercalated system In a wide temperature range, also for the advancement of graphene-based electronics.