Switchable graphene-substrate coupling through formation/dissolution of an intercalated Ni-carbide layer

Abstract

Control over the film-substrate interaction is key to the exploitation of graphene’s unique electronic properties. Typically, a buffer layer is irreversibly intercalated “from above” to ensure decoupling. For graphene/Ni(111) we instead tune the film interaction “from below”. By temperature controlling the formation/dissolution of a carbide layer under rotated graphene domains, we reversibly switch graphene’s electronic structure from semi-metallic to metallic. Our results are relevant for the design of controllable graphene/metal interfaces in functional devices.

Key role of rotated domains in oxygen intercalation at graphene on Ni(1 1 1)

“…We then performed simulations with different values of φ 0 and determined the contribution of rotated domains by calculating the value of the R-factor vs the a and b coefficients (Figure 6). For the diffraction pattern in Figure 5-(e), the minimum R-factor of 0.38 was found for a value of φ 0 of 18 • , which is in excellent agreement with our LEED measurements and comparable to what observed in earlier literature [38,39,63]. In this pattern the rotated domains are dominating (75%) over the aligned domains, as shown in Figure 6-(d).…”

“…The expected (1×1) pattern typical of graphene on Ni(111) (framed with black circles) coexists with streaky features disposed symmetrical to the main LEED spots, (indicated by red arrows). Such features can be assigned to the presence of a small amount of rotated graphene domains in the overlayer, as shown by earlier literature [38,39]. By acquiring a line profile as shown in Figure 4-(b) we could observe that this distribution of rotated domains is centred at an azimuthal angle of ±18 • with respect to the main orientation.…”

“…On the other hand, we attribute the modulation of peak C 5 , Figure 5-(f), to graphene domains which are azimuthally rotated with respect to the layer associated with the component C 1 . Recent publications [38,39,63] have reported about samples of CVD-grown graphene on Ni(111) displaying a small fraction of rotated domains. We then assumed that such rotated domains could produce the pattern displayed in Figure 5-(d), by including in the corresponding simulated pattern contributions sourcing both from graphene aligned with the substrate (φ = 0) and from domains oriented with an azimuthal offset ±φ 0 .…”

Doping of epitaxial graphene by direct incorporation of nickel adatoms

“…A typical STM image of an epitaxial graphene (EG) layer grown on Ni(111) at 400°C, using ethylene as carbon source, 17 is shown in Figure 1. Under these conditions, surface carbide, if present, readily converts to graphene and it is possible to obtain extended graphene domains (up to few hundreds of nm wide) 18 with a low concentration of domain boundaries. 19 However, at this low growth temperature, the layer is not perfect: a sizable number (about 1% of graphene C atoms) of point-like bright defects are created, both as isolated features and short chain structures.…”

Spin‐Resolved PES and IPES Investigation of the Graphene/Ni(111) Interface

“…From a more application‐oriented point of view, the crystalline quality of Gr grown on either thin films or bulk Ni and the influence of Ni surface features and defects on Gr electronic properties has been recently scrutinized, together with the structure of Gr edges and their role in charge scattering from the substrate . The Gr/Ni(111) system was found adequate for the growth of ultra‐flat and scalable devices with high performances . Despite the many proposed applications, however, some data are still missing to sketch an overall picture of the Gr/Ni interface.…”