Exploring the Interface Landscape of Noble Metals on Epitaxial Graphene

Understanding the interaction between noble metals (NMs) and epitaxial graphene is essential for the design and fabrication of novel devices. Within this framework, a combined experimental and theoretical investigation of the effect of vapor-deposited NM (silver [Ag] and gold [Au]) nanostructures on the vibrational and electronic properties of monolayer epitaxial graphene (MLG) on 4H-SiC is presented. Large sets of Raman scattering data are analyzed using supervised classification and statistical methods. This analysis enables identification of the specific Raman fingerprints of Au- and Ag-decorated MLG originating from different dispersion interactions and charge transfer at the metal nanostructure/MLG interface. It is found that Raman scattering spectra of Au-decorated MLG feature a set of allowed phonon modes similar to those in pristine MLG, whereas the stronger Ag physisorption triggers an activation of defect-related phonon modes and electron doping of MLG. A principal component analysis (PCA) and linear discriminant analysis (LDA) are leveraged to highlight the features in phonon dispersion of MLG that emanate from the NM deposition process and to robustly classify large-scale Raman spectra of metal-decorated graphene. The present results can be advantageous for designing highly selective sensor arrays on MLG patches decorated with different metals.

Automated summary

This study investigates the effect of noble metal nanostructures on the vibrational and electronic properties of monolayer epitaxial graphene through a combination of experimental and theoretical approaches. Results show that Au-decorated MLG exhibits Raman scattering spectra similar to pristine MLG, while stronger Ag physisorption triggers activation of defect-related phonon modes. The use of PCA and LDA can robustly classify large-scale Raman spectra of metal-decorated graphene, potentially useful for designing highly selective sensor arrays on MLG patches decorated with different metals.