Print Email Facebook Twitter Hard superconducting gap in germanium Title Hard superconducting gap in germanium Author Tosato, A. Levajac, V. Wang, J.Y. Boor, C.J. Borsoi, F. Botifoll, M. Borja, C.N. Marti-Sánchez, S. Arbiol, J. Sammak, A. Veldhorst, M. Scappucci, G. Publication year 2023 Abstract The co-integration of spin, superconducting, and topological systems is emerging as an exciting pathway for scalable and high-fidelity quantum information technology. High-mobility planar germanium is a front-runner semiconductor for building quantum processors with spin-qubits, but progress with hybrid superconductor-semiconductor devices is hindered by the difficulty in obtaining a superconducting hard gap, that is, a gap free of subgap states. Here, we address this challenge by developing a low-disorder, oxide-free interface between high-mobility planar germanium and a germanosilicide parent superconductor. This superconducting contact is formed by the thermally-activated solid phase reaction between a metal, platinum, and the Ge/SiGe semiconductor heterostructure. Electrical characterization reveals near-unity transparency in Josephson junctions and, importantly, a hard induced superconducting gap in quantum point contacts. Furthermore, we demonstrate phase control of a Josephson junction and study transport in a gated two-dimensional superconductor-semiconductor array towards scalable architectures. These results expand the quantum technology toolbox in germanium and provide new avenues for exploring monolithic superconductor-semiconductor quantum circuits towards scalable quantum information processing. Subject GermaniumJosephson junction devicesPoint contactsQuantum chemistrySemiconductor junctionsSuperconducting materialsCointegrationHigh mobilityHigh-fidelityQuantum information technologiesSpin systemsSuperconducting gapsTopological systemsQuantum optics To reference this document use: http://resolver.tudelft.nl/uuid:9707a348-ceca-4e33-8762-b74f036f8a59 DOI https://doi.org/10.1038/s43246-023-00351-w TNO identifier 985704 Publisher Springer Nature ISSN 2662-4443 Source Communications Materials, 4 (4) Document type article Files To receive the publication files, please send an e-mail request to TNO Library.