PHYSICAL REVIEW APPLIED 12 , 014013 ( 2019 ) Quantum Transport Properties of Industrial 28 Si / 28 SiO

We investigate the structural and quantum transport properties of isotopically enriched Si/SiO2 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 oxide stack comprising 10 nm of SiO2 and 17 nm of Al2O3 (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 Si/SiO2 interface is characterized by a roughness of = 0.4 nm and a correlation length of = 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 Si/SiO2 as a promising material platform to manufacture industrial spin qubits.