Growth and Quantum Transport in sGe/GeO ₂ Quantum Wells

Achieving precise, fully electrically controlled gate operation with high-density gate spacing and long-range strong coupling in microwave resonant cavities is one of the key paths to silicon-based spin qubits. Conventional Si–MOS and Si/SiGe heterostructures are limited by the intrinsic properties of electrons in Si, making it difficult to dispense with micromagnets, whereas Ge/SiGe heterostructure structures, while suppressing interface noise, weaken the gate’s control over the channel and the coupling strength between the cavity field and the channel. To address these challenges and support spin-qubit operation and scaling, we develop a strained germanium (Ge) quantum well on a silicon substrate, integrated into a high-performance MOS platform via a GeO 2 /SiO 2 gate dielectric. This device exhibits a hole mobility of 1.8 × 10 5 cm 2 V –1 s –1 at a percolation threshold of 1.95 × 10 11 cm –2, alongside a large, strain-enhanced effective g -factor up to 8.2─all key metrics relevant for high-performance spin qubits. By combining a high-mobility Ge channel with a MOS-type quantum well architecture, this work provides a promising material platform for the development of fully electrically controlled and microwave cavity-coupled spin qubits.