Quantum transport properties of industrial ${}^{28}$Si/${}^{28}$SiO${}_2$

Abstract

We investigate the structural and quantum transport properties of isotopically enriched ${}^{28}$Si/${}^{28}$SiO${}_2$ 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 $1.75\times 10^{11}$ cm${}^{-2}$ and a peak mobility of 9800 cm${}^2$/Vs are measured at a temperature of 1.7 K. The ${}^{28}$Si/${}^{28}$SiO${}_2$ interface is characterized by a roughness of $\hat{I}”=0.4$ nm and a correlation length of $\hat{I}›=3.4$ nm. An upper bound for valley splitting energy of 480 $\hat{I}¼$eV is estimated at an effective electric field of 9.5 MV/m. These results support the use of wafer-scale ${}^{28}$Si/${}^{28}$SiO${}_2$ as a promising material platform to manufacture industrial spin qubits.

5 pages, 3 figures