Silicene-graphene heterostructure fabrication via interface epitaxy*

Graphene (Gr) remains a material of special interest since its discovery three decades ago, even though the two-dimensional quantum materials (2DQM) research has recently evolved beyond Gr and its analogs (called xenes), as these materials have potential for technological applications, including quantum computing and quantum information. However, xenes other than Gr, such as silicene, antimonene, borophene are generally unstable in atmospheric conditions. In order to protect these reactive xenes, the Gr can be used as a protective, inert coating. In the present study we employed in-situ, real-time low-energy electron microscopy/photoemission electron microscopy (LEEM/PEEM) for the investigation of interface chemistry of silicon allotropes and 2D silica structures grown at the Gr-ruthenium interface. Our results show that the Si epitaxial layer can decouple Gr electronically from the ruthenium substrate. Moreover, these experiments prove that a successful scalable synthesis of Gr/√3-Silicene and Gr/Si/SiO₂ heterostructures can be realized. Tuning the growth conditions also provides means to control the growth of 2DQM at a large scale. The strategy of interface epitaxy is a promising avenue for fabricating  other atomically thin 2D materials with desired structures.