2D Ag-induced interfacial electronic modulation in graphene via oxygen-assisted intercalation

Metal-catalyzed etching provides an effective route to create well-defined channels in graphene, where controlling the competition between etching and intercalation is crucial for determining the surface morphology. By annealing Ag-deposited epitaxial graphene at 500 °C under an oxygen pressure of 8.0 × 10^-5 Torr, oxygen-terminated etched channels form on the surface, facilitating rapid and tunable Ag intercalation. We demonstrate an Ag-catalyzed oxygen etching method that enables intercalation of Ag beneath epitaxial graphene on 4H-SiC(0001). The intercalation process exhibits an oxygen pressure threshold of 1.0 × 10^-5 Torr, thus providing direct control over its initiation. X-ray photoelectron spectroscopy measurements confirm that a 2D Ag layer is intercalated through oxygen-etched pits between buffer layers and the SiC substrate, effectively relieving substrate-induced strain and decoupling the buffer layer/substrate interface. Scanning tunneling microscopy and spectroscopy reveal oxygen-terminated edge states localized near the Dirac point at the boundaries of etched pits. Spatially resolved spectroscopy further shows the well-defined Landau levels originating from a pseudo-magnetic field of ∼87 T, observed at the interfaces of Ag-intercalated regions. This strategy provides a potentially general approach for achieving effective intercalation of diverse species beneath the graphene layer while preserving surface structural integrity.