Additive, Direct-Write Fabrication of Plasmonic Nano-Antennas: a 3D Nanoprinting Approach

While the general interest in nano-plasmonics is still unbroken, there is an increasing trend towards the integration in real applications such as direct nano-emitters or high performance sensors [1]. Aside of novel concepts, versatile fabrication methods are in demand, which provide a high degree of flexibility concerning design and manufacturing possibilities. Although traditional methods, such as e-beam lithography, are very powerful, well established and reliable, they are often limited in their applicability (e.g. flat surfaces). In contrast, additive direct-write manufacturing may overcome such limitations, although techniques for reliable sub-100 nm fabrication are only a few [2]. In that respect, focused electron beam induced deposition (FEBID) is one of the promising candidates, which not only meets resolution requirements, but also allows true 3D nano-printing on a broad range of materials and almost any surface morphology [3]. As FEBID materials notoriously suffer from high carbon contents, chemical post-growth transfer into pure materials is indispensably needed, which can severely harm or even destroy FEBID-based 3D nano-architectures. Following that challenge, we have dissected FEBID growth characteristics and combined individual advantages via advanced patterning approaches. That allows direct-write fabrication of high-fidelity shapes with nanoscale features in the sub-10 nm range, which allow a shape-stable chemical transfer into plasmonically active Au nano-antennas. Consequently, this contribution ranges from initial 3D-FEBID fabrication over purification towards confirmation of the originally intended plasmonic functionality [4]. The latter is compared to theoretical modelling, which reveals very good agreement and underlines the reliability of 3D-FEBID as generic approach towards more complex 3D nano-concepts for future applications.
[1] Plank et al., Micromachines, 11, 1 (2020)
[2] Hirt et al., Adv. Mater., 29, 17 (2017)
[3] Winkler et al., J. Appl. Phys., 125, 21 (2019)
[4] Kuhness et al., ACS Appl. Mater. Interfaces, 13, 1, 1178 (2021)