Direct-Write X‑ray Nanopatterning: A Proof of Concept Josephson Device on Bi₂Sr₂CaCu₂O_8+δ Superconducting Oxide

We describe the first use of a novel photoresist-free X-ray nanopatterning technique to fabricate an electronic device. We have produced a proof-of-concept device consisting of a few Josephson junctions by irradiating microcrystals of the Bi₂Sr₂CaCu₂O_8+δ (Bi-2212) superconducting oxide with a 17.6 keV synchrotron nanobeam. Fully functional devices have been obtained by locally turning the material into a nonsuperconducting state by means of hard X-ray exposure. Nano-XRD patterns reveal that the crystallinity is substantially preserved in the irradiated areas that there is no evidence of macroscopic crystal disruption. Indications are that O ions have been removed from the crystals, which could make this technique interesting also for other oxide materials. Direct-write X-ray nanopatterning represents a promising fabrication method exploiting material/material rather than vacuum/material interfaces, with the potential for nanometric resolution, improved mechanical stability, enhanced depth of patterning, and absence of chemical contamination with respect to traditional lithographic techniques