Triple-walled gold surfaces with small-gaps for nonresonance surface enhanced Raman scattering of rhodamine 6G molecules

To increase the intensity of Raman scattering with surface enhanced Raman scattering (SERS) effect, the authors proposed the triple-walled gold (Au) structures on silicon (Si) substrate. High aspect ratio Au nanowalls with nanogaps were realized by two different techniques. One is layer by layer technique. The other is standing high aspect ratio Au wall fabrication technique. Finally, 50 nm-thick Au standing walls and 50 nm gaps were obtained. Through the comparison of bare Si substrate, Au film, single-walled Au structures, and triple-walled Au structures in SERS intensity with 0.020 wt. % rhodamine 6G molecules, it was revealed that the SERS intensity from triple-walled Au structure was 50 times higher than that from Au film. The enhancement factor (EF) of our proposed SERS chip was estimated as 4.7 × 10⁶. The proposed method will allow us to realize multiwalled Au structure, which can increase EF efficiently.