Hard superconducting gap in germanium

Hard superconducting gap in germanium

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.

2023

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.

Germanium
Josephson junction devices
Point contacts
Quantum chemistry
Semiconductor junctions
Superconducting materials
Cointegration
High mobility
High-fidelity
Quantum information technologies
Spin systems
Superconducting gaps
Topological systems
Quantum optics

http://resolver.tudelft.nl/uuid:9707a348-ceca-4e33-8762-b74f036f8a59

https://doi.org/10.1038/s43246-023-00351-w

985704

Springer Nature

2662-4443

Communications Materials, 4 (4)

article