Three-dimensional cavity nanoantenna coupled plasmonic nanodots for ultrahigh and uniform surface-enhanced Raman scattering over large area

We propose and demonstrate a new SERS substrate architecture that couples a dense three-dimensional (3-D) cavity nanoantenna array, through nano-gaps, with dense plasmonic nanodots; and a new nanofabrication that combines nanoimprint, guided self-assembly and self-alignment and has fabricated the architecture precisely, simply, inexpensively and over large area (4-inch wafer). We experimentally achieved not only high area-average SERS enhancement (1.2 × 10⁹) but also excellent uniformity (22.4% variation) at the same time over the entire large-area sample by measuring 90 points with a regular mapping distance. The best uniformity achieved is 15% variation over 1.6 mm by 1.6 mm area at slightly lower enhancement factor and is independent of the excitation laser probe size, which had an area varying from ∼1 to 10,000 μm².