3D Nanoprinting of Functional Nanowires via Focused Electron Beams

Quasi 1D nanostructures exhibit outstanding properties, making them highly interesting for integration in optical, magnetic, electronic, thermal or multifunctional applications. Especially the latter, however, has very high demands on related fabrication as it not only requires local precision but also should allow the fabrication of different materials and / or the localized modification to tune functionalities. A highly interesting technology class in that respect are direct-write methods, although available techniques are only a few at that scale. One of them is focused electron beam induced deposition (FEBID), which relies on the highly localized nano-synthesis of surface adsorbed precursor molecules, which are introduced by gas injection system in the vacuum chamber. Therefore, this technology has only very little demands on substrate materials and, even more important, on surface morphologies as long as relevant regions are accessible by the focused electron beam. Due to the small beam diameter and spatially confined secondary processes, nanowires in the sub 20 nm range can be directly fabricated. As a currently unique possibility, FEBID allows for the fabrication of even complex, freestanding 3D nano-objects by the controlled movement of the electron beam. Together with specific software packages for an upfront design and an increasing reliability due to improved process understanding, this technology leveraged into the status of a true 3D nano-printer. In this presentation, we will shed light on the basic concept of 3D-FEBID with strong focus on meshed objects, consisting of individually arranged and interconnected nanowires. We then focus on structural, chemical and functional properties of selected nanowires and discuss further modification possibilities by different post-processing approaches. This rather unconventional strategy for nanowire deposition will be illustrated by specific examples and is complemented by a view on current activities to further expand the flexibility of this generic approach.