Transport characterization of CMOS-based devices fabricated with isotopically-enriched ²⁸Si for spin qubit applications

Both from a scalability and integration perspective, CMOS-based qubits hold great potential for quantum computing applications. However, current fabrication processes must be adapted to fit qubit requirements, implying a need for controlled process monitoring to compare technological splits as well as to guarantee future process quality. The switch to isotopically-enriched Si-28 as a channel material is one such adaptation that requires deeper study. Here, we fabricate identical devices with Si-28 and natural Si and present a comparison of their variable-temperature transport characteristics using the Hall effect and split C-V. Once validated, we use the same 300mm process flow to fabricate Si-28 quantum dots which, despite the addition of a second gate level, display state-of-the-art charge noise at 400mK.