Effect of Ag nanoparticles on wafer-scale quasi-free-standing graphene characterization by surface enhanced Raman spectroscopy

Quasi-free-standing graphene (QFSG) obtained by H intercalation on SiC (0001) substrate paves a new way for widening the applications in microelectronics field. In this work, the direct and efficient characterization of wafer-scale quasi-free-standing graphene on SiC was presented by Ag-assisting Raman spectroscopy. The Si-H peak existing at the interface between graphene and substrate was tested unambiguously. The effects of Ag distribution and particle size on Raman enhancement were clarified both theoretically and experimentally. It was found that relative larger Ag particles at aggregation area were accompanied with the better enhancement. Moreover, Raman mapping with Ag assisting was executed on QFSG obtained under different growth conditions and the corresponding QFSG coverages were evaluated effectively. The optimum H intercalation temperature was determined to be around 1000 °C with the coverage being 73%. This study would supply a new approach for uniform and wafer-scale QFSG fabrication.