Speaker
Description
Hybrid superconductor-semiconductor devices are of interest for various applications in quantum physics – they can host different types of qubits or can be used for compact, low-noise, cryogenic electronics elements such as parametric amplifiers [1]. As semiconductor, we employ strained germanium quantum wells embedded in planar silicon-germanium heterostructures. Germanium was shown to be a suitable platform for spin qubit applications due to its small effective mass, suppressed hyperfine interaction, and high mobility [2]. Due to the proximity effect, germanium inherits superconducting properties when contacted by a superconductor and is thus also a promising host for superconducting spin qubits.
Aiming at a pristine super-semi interface, we developed a complete hybrid super-semi heterostructure stack, with an in-situ grown superconducting film of aluminum on top of the semiconductor. We characterise four different hybrid super/semi heterostructure stacks in terms of their structural, transport and microwave [3] properties, enabling a choice of a suitable heterostructure design for specific future applications.
References
1. Phan, D. et al. Gate-Tunable Superconductor-Semiconductor Parametric Amplifier.
Physical Review Applied 19, 064032 (June 9, 2023).
2. Nigro, A. et al. Demonstration of Microwave Resonators and Double Quantum Dots on
Optimized Reverse-Graded Ge/SiGe Heterostructures. ACS Applied Electronic Materials 6,
5094–5100 (June 26, 2024).
3. Ruggiero, L. et al. High-Quality and Field Resilient Microwave Resonators on Ge Quantum
Well Heterostructures. npj Quantum Information 12, 118 (June 11, 2026).
