Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 38: Materials and Devices for Quantum Technology II

HL 38.1: Vortrag

Donnerstag, 12. März 2026, 09:30–09:45, POT/0051

Shadow masks for all-in-situ fabrication of InAs nanowire Josephson junctions — •Christian Schäfer, Lennart Grosch, Yurii Kutovyi, Nils von den Driesch, Thomas Schäpers, and Alexander Pawlis — PGI 9 / PGI 10 / JARA-FIT, Forschungszentrum Jülich, 52428 Jülich, Germany

Josephson junctions based on semiconductor/superconductor hybrid structures offer unique features for quantum circuits, such as gate-controllable supercurrent and quantized Andreev bound states. Clean interfaces between nanowire and superconductor are essential to leverage both effects, driving the development of in-situ contact fabrication. Shadow wall epitaxy offers both, a scalable and all-in-situ solution for nanowire growth and contact formation. Micrometer-high pre-fabricated walls shadow the molecular beams of In and As depending on their relative orientation. Since As on its own has a low sticking coefficient and In forms isolated droplets, partially shadowed regions are insulating and do not form InAs crystals. Despite the significant lattice mismatch between InAs and the GaAs substrate, we observe growth of lateral 1D-nanowires between walls spaced less than one micrometer. The same mask can additionally be used to perform selective deposition of any superconductor. We explore different mask designs to optimize electrical device isolation, nanowire growth, and junction geometry. Since no transfer or post-processing after growth is necessary, associated defects and degradation are avoided. Shadow wall epitaxy enables scalable in-situ fabrication of InAs nanowire junctions.

Keywords: shadow epitxay; nanowire; InAs; Josephson junction