TY - GEN A1 - Ferbel, Letizia A1 - Veronesi, Stefano A1 - Mentes, Tevfik Onur A1 - Buß, Lars A1 - Rossi, Antonio A1 - Mishra, Neeraj A1 - Coletti, Camilla A1 - Flege, Jan Ingo A1 - Locatelli, Andrea A1 - Heun, Stefan T1 - Rubidium intercalation in epitaxial monolayer graphene T2 - Nanoscale N2 - Alkali metal intercalation of graphene layers has been of particular interest due to potential applications in electronics, energy storage, and catalysis. Rubidium (Rb) is one of the largest alkali metals and among the least investigated as an intercalant. Here, we report a systematic investigation, with a multi-technique approach, of the phase formation of Rb under epitaxial monolayer graphene on SiC(0001). We explore a wide phase space with two control parameters: the Rb density (i.e., deposition time) and sample temperature (i.e., room and low temperature). We reveal the emergence of (2 × 2) and [sqrt(3) x (sqrt3)] R30° structures formed by a single alkali metal layer intercalated between monolayer graphene and the interfacial C-rich reconstructed surface, also known as the buffer layer. Rb intercalation also results in strong n-type doping of the graphene layer. Upon progressively annealing to higher temperatures, we first reveal the diffusion of Rb atoms, which results in the enlargement of intercalated areas. As desorption sets in, intercalated regions progressively shrink and fragment. Eventually, at approximately 600 °C, the initial surface is retrieved, indicating the reversibility of the intercalation process. KW - Graphene KW - N-type doping KW - Micro-spot low-energy electron diffraction (µLEED) KW - Scanning tunneling microscopy (STM) KW - Low-energy electron microscopy (LEEM) KW - Density functional theory (DFT) Y1 - 2025 U6 - https://doi.org/10.1039/D5NR00417A SN - 2040-3364 VL - 17 IS - 19 SP - 12465 EP - 12472 PB - Royal Society of Chemistry (RSC) CY - London ER -