Highly 28Si enriched silicon by localised focused ion beam implantation
R. Acharya, Maddison Coke, Mason Adshead, Kexue Li, Barat Achinuq, Rongsheng Cai, A. Baset Gholizadeh, Janet Jacobs, Jessica L. Boland, Sarah J. Haigh, Katie L. Moore, David N. Jamieson, Richard J. Curry
Abstract
Abstract Solid-state spin qubits within silicon crystals at mK temperatures show great promise in the realisation of a fully scalable quantum computation platform. Qubit coherence times are limited in natural silicon owing to coupling to the 29 Si isotope which has a non-zero nuclear spin. This work presents a method for the depletion of 29 Si in localised volumes of natural silicon wafers by irradiation using a 45 keV 28 Si focused ion beam with fluences above 1 × 10 19 ions cm −2 . Nanoscale secondary ion mass spectrometry analysis of the irradiated volumes shows residual 29 Si concentration down to 2.3 ± 0.7 ppm and with residual C and O comparable to the background concentration in the unimplanted wafer. After annealing, transmission electron microscopy lattice images confirm the solid phase epitaxial re-crystallization of the as-implanted amorphous enriched volume extending over 200 nm in depth.