Optical studies of implanted bismuth impurities in silicon towards single/few impurity devices.

Steven Clowes, University of Surrey

Group V donors in silicon is a potential scalable qubit platform for quantum technologies due the compatibility with existing microelectronic fabrication. Bismuth donors are particularly interesting due to their large nuclear spin and strong hyperfine coupling, manifesting as a 20-dimensional Hilbert space with a hyperfine splitting of 30.5 µeV which can be resolved without the application of a magnetic field. Fully scalable manufacturing of deterministically positioned donors can only be achieved through single ion implantation. Here we will present a review of our recent optical characterisation studies of implanted Bi donors which address the challenges presented by the implantation route for the delivery of usable materials for quantum technologies. Namely, the repair to damage caused by the implanted ion and the assessment of the single/few implanted impurities. Annealing studies have demonstrated the repair of lattice defects in high concentration of implanted Bi in Si, and show using resonant donor bound, D0X, photoconductivity the observation of the presence of hyperfine splitting. To assess the quality of implanted Bi impurities we have used photoassisted ionization spectroscopy of a few implanted donors in an silicon-on-insulator device. Under THz illumination, we have optically detected 6×105 substitutional Bi centres by tuning to the 1s(A1)-2p± orbital transition. We are currently working to reduce the number of detected impurities down to the tens and hundreds, with the aim of electrical detection of single impurities