Large-Area Sub-5nm Plasmonic Nanogap Arrays: Advanced Fabrication, Characterization and Applications

In recent years, there has been a growing interest in the study of plasmonic nanogaps, specifically in understanding the fundamental physics of localized surface plasmon resonances (LSPR) and of their interplay with optically induced electron transitions through these tiny gaps. Accordingly, many efforts have been made in fabricating nanogaps with precise control over their thickness and shape. While there are several established methods to achieve such a delicate task, many of them struggle with achieving sub-5nm resolution, reproducibility, and/or scalability over wide areas [1]. However, recent technological advancements in the atomic layer deposition (ALD) technique have brought us closer to realizing metasurfaces featuring extremely thin nanogaps down to single-nanometer widths and fulfilling all the demanding requirements listed above [2].