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Fabrication of Size-Controlled Metallic Nanogaps down to the Sub 3-Nm Level
preprintsubmitted on 28.10.2020, 23:23 and posted on 30.10.2020, 10:43 by Sihai Luo, Andrea Mancini, Rodrigo Berté, Bård H. Hoff, Stefan A. Maier, John de Mello
Metallic nanogaps are fundamental components of nanoscale photonic and electronic devices. However, the lack of reproducible high-yield fabrication methods with nanometric control over the gap-size has hindered practical applications. Here, we report a patterning technique based on molecular self-assembly and physical peeling that allows the gap-width to be tuned over the range 3 – 30 nm and enables the fabrication of massively parallel nanogap arrays containing hundreds of millions of ring-shaped nanogaps (RSNs). The method is used here to prepare molecular diodes across sub-3-nm metallic nanogaps and to fabricate visible-light-active plasmonic substrates based on large-area, gold-based RSN arrays. The substrates are applicable to a broad range of optical applications, and are used here as substrates for surface-enhanced Raman spectroscopy (SERS), providing high enhancement factors of up to 3e8 relative to similar, gap-free thin gold films.