Fabrication of a uniform Au nanodot array/monolayer graphene hybrid structure for high-performance surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for sensing, which can detect a broad range of chemical and biological analytes at the single-molecule level. In this work, a hybrid structure of Au nanodot array and high-quality graphene monolayer is used as SERS substrate, which integrates the electromagnetic enhancement from Au nanodots and chemical enhancement from monolayer graphene. The fabricated SERS substrates consist of uniform round top shape Au nanodot array with coverage of 36.9% where their diameter and gap distribution ranges from ~ 33 to ~ 42 nm and from ~ 22 to ~ 28 nm. The hybrid Au nanodot array/monolayer Gr SERS substrate exhibited a 4.67 times enhanced Raman signal compared to Au nanodots without Gr at the R6G concentration of 10⁻⁶ M. The detection limit of R6G is achieved as low as 4.69 × 10⁻⁹ M on the Au nanodot array/Gr SERS substrate. These experiments demonstrate a facile approach to fabricate hybrid metal nanostructure/2D materials SERS substrate for biomedical and environmental sensing and provide a clue for high-performance optoelectronic devices.