Controlling surface effects in extremely high aspect ratio gold plasmonic electrodes.

Nanofabrication is key to many technological advances, especially the challenge of merging nanophotonics with electronics. Here, we investigate the fabrication process of plasmonic interdigitated gold electrodes having a very high aspect ratio (i.e. long and thin geometries) and a large surface area. Stringent stability issues that arise when these structures are fabricated using inorganic adhesion layers, such as titanium or chromium, on silica substrates are highlighted. We ascribe these problems to thermodynamical non-equilibrium states of freshly deposited gold and, in particular, discuss the role of surface energy in determining the structural properties of high aspect ratio gold nanostructures. We then show that the use of organic silane self-assembled monolayers improves the long term stability of these structures and, finally, characterize the fabricated electrodes. This technology can unleash the potential of hybrid optoelectronic circuits where current and light are manipulated with the same component. [Display omitted] • The stability of elongated gold structures is dominated by their surface properties. • Fabricating gold nanostructures on glass substrates requires an adhesion layer. • The use of metallic adhesion layers leads to a deterioration of the structures. • Organosilane adhesion layers improve the stability of elongated gold structures. [ABSTRACT FROM AUTHOR]