Surface plasmon waves have been widely utilized to enhance the light-matter interaction near the surface of the structures for a broad range of sensing methods, including surface plasmon spectroscopy, [1][2][3][4] plasmon-controlled fl uorescence [ 5,6 ] and surface-enhanced Raman scattering (SERS). [7][8][9] In particular, SERS has been demonstrated as one of the most important and promising approaches for various applications [10][11][12][13][14] (e.g., high-sensitivity bio-sensing down to a single-molecule level [ 7,15 ] ), because of its effective identifi cation of chemical bonds. Numerous nanostructures have been investigated to effectively improve the electromagnetic enhancement, a predominant mechanism contributing to the total enhancement in light-matter interaction. [ 16,17 ] Among these nanostructures, periodic metal nanostructures fabricated by e-beam lithography (EBL) or focused ion beam (FIB) patterning, [18][19][20] have been widely utilized to investigate the light-matter interaction mechanism, especially coupling effects such as nearfi eld dipole and long-range interactions, because of the merit of adjustable nanostructure dimensions in these methods. In addition, a few disordered nanostructures (e.g., gold nanoparticle dimers and trimers, [ 7,21,22 ] silver (Ag) nanowires, [23][24][25][26] Ag nanoparticles decorated nanotrees [ 27 ] or nanorods [ 28 ] ) fabricated by various methods (e.g., chemical reduction process, [ 29,30 ] Langmuir-Blodgett technique, [ 23,24 ] self-assembled synthesis [31][32][33] ) have attracted considerable attention. In contrast to the periodic nanostructures, disordered aggregates of metal nanostructures also can result in extremely high fi eld enhancement, which is typically observed on the so-called "hot spot" sites. [ 34 ] Indeed, these periodic and disordered nanostructures have been extensively investigated, addressing their potential for various applications. [ 35,36 ] However, the aforementioned fabrication methods have their drawbacks. For example, the nanofabrication methods such as EBL [ 18,19 ] and FIB [ 20 ] require expensive equipments and are typically time-consuming for large-scale applications. The chemical methods (e.g., chemical reduction process, [ 29,30 ] Langmuir-Blodgett technique [ 23,24 ] ) usually are inapplicable due to the challenges of repeatability control in these fabrication processes for applications, where high fi eld enhancement is required. Therefore, novel fabrication methods for simple, cost-effective, large-area nanostructure devices with high enhancement factors (e.g., >10 9 ) [ 37 ] are thus of great importance for various practical applications (e.g., SERS, [ 38 ] plasmon-enhanced fl uorescence [ 39 ] ).Black silicon (BS) is a nano-roughened silicon (Si) surface, which can be produced by a wide variety of dry and wet etching techniques. Initially discovered as an unwanted side-effect of dry etching, it has gathered a lot of attention lately due to the low-cost and simple process to achieve nanostructures on a large scale. The na...
