Self-generating nanogaps for highly effective surface-enhanced Raman spectroscopy

The fabrication of surface enhanced Raman spectroscopy (SERS) substrates with controlled high density hot spots still remains challenging. Herein, we report highly effective SERS substrates containing the self-generating (SG) nanogaps from polystyrene nanosphere monolayer through isotropic plasma etching. The emergence of multimode hot spots, i.e., metal film over nanosphere (MFON)-like hot spots (closed gaps, 0 nm), individual self-aligned hot spots (discrete gaps, > 20 nm) and three-dimensional (3D) hot spots (nanogaps, 1–10 nm), makes the SG SERS substrates superior as compared to the traditional MFON or the well-ordered self-aligned SERS substrates in terms of enhancement, uniformity, and reproducibility. The SG SERS substrates can function as the excellent SERS platforms for trace molecule detection in the practical application fields.