**4. Conclusions**

be estimated to be ~5 nm. By scanning several areas of the surface, all of these three scenarios have been observed several times, confirming that the Au deposition on the graphene layer is

**Figure 6.** Cross-sectional STEM images recorded in the HAADF (top) and bright field (middle) mode, respectively. The substrate, the Au, and graphene layers can clearly be observed. A scheme of the area is also represented (bottom). The substrate is represented by a gray square shape. The Au and carbon atoms are represented by yellow and gray

The lateral distances between the gold atoms in the first layer are exactly the ones found for the silicon (or carbon) atoms of the SiC substrate underneath. Indeed, the distance measured between two adjacent Au atoms is 0.265 nm, while it is of 0.267 nm for two adjacent Si atoms in a (0 0 0 2) plane. These distances are obtained with the same value in measurements performed on numerous STEM images. The distance between two adjacent Au atoms in the second layer systematically decreases to 0.236 nm. Moreover, the distance between two adjacent gold layers is 0.255 nm, considering that the *d*0 0 0 2 inter-reticular distance measured in the SiC substrate close to the surface is 0.266 nm. This value has to be compared to the experimental value of 0.252 nm [31] for the SiC bulk. Therefore, we can conclude that the strain in the SiC substrate beneath the surface is small, even when layer or nanoclusters of gold are

not a uniform process.

14410 Recent Advances in Graphene Research

spheres.

observed.

In summary, we have demonstrated that the Au deposition on graphene epitaxially grown on SiC is an inhomogeneous process. The LEEM and XPEEM measurements have demonstrated that the Au nanoclusters nucleate all over the surface, independently of the surface chemistry (substrate, mono-, and bilayers of graphene). The STEM experiments have shown that the gold can diffuse under one or more graphene layers and can spread as one or two gold layers. Moreover, the gold mainly nucleates to form Au nanoclusters, which are spread all over the sample, independently of the surface chemistry. Therefore, the µARPES experiments have highlighted that the gold deposition does not induce a significant change in the electronic properties of this material and showed that the Fermi velocity of graphene remained intact in comparison with pristine graphene.
