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Magnetotransport in highly enriched 28Si for quantum information processing devices



Aruna N. Ramanayaka, Ke Tang, Joseph A. Hagmann, Hyun Soo Kim, Curt A. Richter, Joshua M. Pomeroy


Elimination of unpaired nuclear spins can result in low error rates for quantum computation; therefore, isotopically enriched 28Si is regarded as an ideal environment for quantum information processing devices. Using mass selected ion beam deposition technique, we in-situ enrich and deposit epitaxial 28Si achieving better than 99.99998 % 28Si isotope fractions [1]. To explore the electrical properties and optimize the growth conditions of in-situ enriched 28Si, we fabricate top gated Hall bar devices, and investigate the magnetotransport in this material at magnetic fields as high as 12 T and temperatures ranging from 10 K to 1.2 K. A schematic of the cross-sectional view and an optical micrograph of the fabricated device is shown in fig.1 (a) and (b), respectively. At a temperature 1.9 K, we measure maximum mobilities of approximately (1740±2) cm^2/(V⋅s) and (6040±3) cm^2/(V⋅s) at an electron density of ≈1.2×〖10〗^12 cm^(-2) for devices fabricated on 28Si and natural Si, respectively. For magnetic fields B>2 T, both types of devices demonstrate well developed Shubnikov-de Haas oscillations on the longitudinal magnetoresistance (see fig2 and fig3). In contrast to the device on isotopically enriched 28Si epi-layer, the device on natural Si demonstrates spin- splitting for B>3 T (see fig2). Furthermore, relative to the device on nat:Si, the weak- localization is stronger for the device fabricated on isotopically enriched 28Si. Based on the T dependence of the Shubnikov-de Haas oscillations and weak-localization, the dominant scattering mechanism in these devices appears to be background impurity scattering and/or interface roughness scattering. We believe that the relatively lower mobility and stronger weak-localization observed for the devices fabricated on 28Si may be due to the dilute adventitious C, N and O in deposited 28Si.
Proceedings Title
2018 Workshop on Innovative Nanoscale Devices and Systems,
WINDS Book of Abstracts
Conference Dates
November 25-30, 2018
Conference Location
Kohala Coast, HI
Conference Title
2018 Workshop on Innovative Nanoscale Devices and Systems


enriched silicon, quantum information, semicondcutors
Created November 25, 2018, Updated January 27, 2020