Customization of Nanogap Arrays Using Stereolithography and Nanoskiving for Surface-Enhanced Raman Scattering

Nanoskiving has been utilized in the fabrication of plasmonic nanogaps. It is imperative to develop a cost-effective and highly adjustable method for the manipulation of predetermined models, as the fabrication of nanogaps by nanoskiving relies on predetermined models. Here, a method is proposed that leverages stereolithography to design and fabricate predetermined models, coupled with nanoskiving to fabricate various patterned nanogaps for surface-enhanced Raman scattering. Four different patterned arrays (rod-shaped nanogap arrays, striped nanogap arrays, square-arranged crescent-shaped nanogap arrays, and hexagon-arranged crescent-shaped nanogap arrays) with 5 nm nanogaps are successfully fabricated. The strong plasmon coupling is excited within nanogaps, leading to a several-fold increase in Raman intensity, higher than that of structures without a nanogap. Furthermore, it is also observed that the Raman intensity varies with the morphologies of nanogap arrays. The crescent-shaped nanogap arrays exhibit a 1.8-fold higher intensity compared to that of linear-shaped nanogap arrays. Through the theoretical analysis, this phenomenon is related to the distinct oscillating propagation of light between parallel or nonparallel noble metals. The innovative combination of stereolithography and nanoskiving paves the way for the fabrication of patterned nanogaps, holding significant potential for plasmonic sensors, nonlinear optics, and molecule detection.