Silicene nanosheets intercalated in slightly defected epitaxial graphene on a 4H-SiC (0001) substrate

In the last years, epitaxial graphene (epi-Gr) demonstrated to be an excellent substrate for the epitaxial or intercalated synthesis of two dimensional (2D) materials. Among 2D materials, silicene has been for a long time a dream for the scientific community, for its importance both from fundamental and application point of view. Despite the theoretical prediction of silicene energetic viability, experimentally it is not so simple to induce silicon to hybridize in sp2 configuration. In this respect, the substrate proved to play a fundamental role in the Si atom absorption process, leading in case of metal substrates to a mixed phase formation. For van der Waals chemical inert substrates, instead, like highly oriented pyrolytic graphite and MoS2, Si atom intercalation even at room temperature has been reported and associated to non-ideality of their surfaces. Interestingly, very recently it has been shown that hundreds of nanometer area quasi-free standing silicene can be grown on top an almost ideal epi-Gr layer synthesized on 6H-SiC substrate. In the present paper, using scanning tunneling microscopy and spectroscopy and Raman analysis, we demonstrate that a non-ideal (slightly defected) epi-Gr network obtained by thermal decomposition of Si-terminated 4H-SiC(0001) enables the Si atoms penetration forming intercalated silicene nanosheets at RT, thus opening a path toward controlling intercalated silicene nanosheet formation through pristine graphene defect concentration managing and silicene application in nanotechnology.