**1. Introduction**

Graphene is a single layer of carbon atoms arranged in a hexagonal lattice. It is one of the few structures that are stable in two dimensions as a free-standing crystal [1, 2]. Its extraordina‐ ry properties, such as unconventional two-dimensional (2D) electron gas, high carrier mobility, half-integer quantum Hall effect at room temperature, and spin transport [1], have made graphene a very promising candidate for the design of the new generation of devices, such as ultrafast electronic circuits and photodetectors. Despite significant progress in its synthesis, the development of production methods warranting fine control over film mor‐ phology and thickness, which are both crucial to determine its electronic properties, re‐ mains a considerable challenge.

Epitaxial graphene layers on silicon carbide (SiC) have been extensively studied due to their potential for large-scale production with a high crystalline quality [3, 4]. It is now well established that, in this system, the interaction between the graphene and its supporting substrate (SiC) can affect considerably the electronic properties of graphene. Indeed, it is known that the first carbon layer onto a SiC substrate is covalently bonded to the Si atoms of the substrate, and this "buffer layer" does not display graphitic electronic properties [5–8]. Moreover, the remaining unsaturated Si dangling bonds, at the buffer layer/SiC interface, induce a high intrinsic n-doping in graphene, which degrades the carrier mobility. These drawbacks pose a major obstacle to the integration of graphene/SiC in future electronic devices. A solution to this problem is provided by the passivation of the Si dangling bonds using dopants and/or decoupling the graphene layer from the SiC substrate. Recently, decoupling of graphene has been achieved by depositing molecules [9, 10] or atomic layers of Bi [11], Ge [12], F [13], and Li [14, 15]. Furthermore, Riedl et al. [16] have shown that hydrogen intercala‐ tion can induce such desired decoupling. More recently, it was demonstrated that the oxygen can partially decouple the buffer layer from the substrate and reduce the intrinsic electron doping [17]. Moreover, the intercalation of metal clusters or molecules between the graphene layers may serve to functionalize graphene.

Numerous studies have been performed to understand the intercalation of transition metals [18–20]. The study by Gierz et al. [21] claimed that the strongly interacting first carbon layer was decoupled from the SiC(0 0 0 1) substrate via gold intercalation. The shift of Dirac points due to gold intercalation was then theoretically studied by Chuang et al. [22]. A similar study performed by Premlal et al. [23], using scanning tunneling microscopy and spectroscopy (STM/ STS), concluded that the intercalated gold cluster displays a new surface reconstruction and induces a possible hole-doping effect. Nonetheless, further investigations are needed to better clarify the effects on the electronic structure of graphene induced by intercalated Au.

In this chapter, we discuss the properties of Au-intercalated epitaxial graphene grown on 6H-SiC(0 0 0 1). Low-energy electron diffraction (LEED), low-energy electron microscopy (LEEM), transmission electron microscopy (TEM), X-ray photoemission electron microscopy (XPEEM), microspot angle-resolved photoemission spectroscopy (µ-ARPES), and micro-Raman spec‐ troscopy allowed us to study the structural and electronic properties of epitaxial graphene on SiC. In particular, we focused on the effect of Au adsorption on the local morphology, structure, and electronic properties of few layers graphene on SiC(0 0 0 1); as it will be shown, our work provides also information about the local distribution of Au at the interface.
