Abstract
We investigate the structural and quantum transport properties of isotopically enriched ²⁸Si/²⁸SiO₂ stacks deposited on 300 mm Si wafers in an industrial CMOS fab. Highly uniform films are obtained with an isotopic purity greater than 99.92\%. Hall-bar transistors with an equivalent oxide thickness of 17 nm are fabricated in an academic cleanroom. A critical density for conduction of 1.75×10¹¹ cm⁻² and a peak mobility of 9800 cm²/Vs are measured at a temperature of 1.7 K. The ²⁸Si/²⁸SiO₂ interface is characterized by a roughness of Δ=0.4 nm and a correlation length of Λ=3.4 nm. An upper bound for valley splitting energy of 480 μeV is estimated at an effective electric field of 9.5 MV/m. These results support the use of wafer-scale ²⁸Si/²⁸SiO₂ as a promising material platform to manufacture industrial spin qubits.