Exploring the surface-enhanced Raman scattering (SERS) activity of gold nanostructures embedded around nanogaps at wafer scale: Simulations and experiments

•We have fabricated symmetric and asymmetric Au gaps templated over silicon nano-wedges.•Au nanogaps were formed on the nano-wedges by means of ion beam etching (IBE) of sputter-deposited Au (Au) films.•Highly controllable nanogaps with a size in the order of 6 nm for symmetric gaps and 8 nm for asymmetric gaps.•Finite-difference time-domain (FDTD) simulations: the Raman enhancement arises at the narrow gap due to plasmonic resonances, yielding a maximum AEF of 6.9 × 106.