Electroplated and Self-Assembled Helical Slow-Wave Structures obtained by Wet and Dry Release Methods

We show two routes to fabricate self-assembled helical ribbons with microscale diameter and pitch. These helices may serve as slow-wave structures in millimeter-through-THz vacuum electronic devices. The focus is on releasing metal strips by H
2
O
2
etching and XeF
2
etching of a Ge sacrificial layer. We show how the two etching methods affect the geometry of the fabricated helices and the structure of electroplated gold films on the helical ribbons.