Single-shot fabrication of semiconducting-superconducting nanowire devices*

Semiconducting-superconducting nanowires attract widespread interest owing to the presence of elusive Majorana zero modes, which hold promise for topological quantum computation. The systematic search for Majoranas signatures is challenging because it requires reproducible hybrid devices and reliable fabrication methods. Here, we exploit a fabrication platform based on shadow walls that enables the in-situ, selective and consecutive depositions of superconductors and normal metals to form normal-superconducting junctions. Crucially, this method allows realizing devices in a single shot, eliminating fabrication steps after the synthesis of the fragile semiconductor/superconductor interface. At the atomic level, all investigated devices reveal a sharp and defect-free semiconducting-superconducting interface and, correspondingly, we measure electrically a hard induced superconducting gap. While the cleanliness of our technique enables systematic studies of topological superconductivity in nanowires, it also allows for the synthesis of advanced nano-devices based on a wide range of material combinations and geometries while maintaining an exceptionally high interface quality.