26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Deterministic ion implantation of low energy donor ions in isotopically enriched 28-Silicon

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Poster AIP | Quantum Science and Technology (QST)

Speaker

Nikhil Niranjan Maka (University of New South Wales)

Description

High-nuclear-spin group-V donors in isotopically enriched 28-Si offer access to a higher-dimensional Hilbert space and long coherence times for quantum information processing.
Ion implantation provides a reliable method for introducing donors into enriched Si. To date, donor spin-qubit devices have typically been fabricated using timed implants through exposed mask windows, resulting in random donor distributions. However, deterministic implantation is required to scale, operate, and couple ordered arrays of hundreds or thousands of donor qubits for future fault-tolerant quantum computers. For this purpose, on-chip detector electrodes enable implantation of individually counted donors with high placement precision through a movable cantilever nanostencil. The resulting ion-beam-induced charge (IBIC) is detected under strong reverse bias with high confidence. Previously, a detection confidence of 99.85% was demonstrated for single low-energy 14 keV phosphorus (P) ions implanted into natural Si. However, implantation of single donor ions into isotopically enriched 28-Si with high detection confidence, has not yet been demonstrated. This is a crucial step before such detectors can be integrated with qubit devices in enriched 28-Si.
In this work, single-ion detectors were fabricated on an isotopically enriched 28-Si epilayer deposited on natural Si by chemical vapour deposition. Shallow 10 keV H₂ implants were used to quantify the fraction of ion-beam-induced charge collected by the detectors, expressed as the charge collection efficiency (CCE). A consistently high CCE of 95% was obtained across multiple detectors. This indicates that the interface between natural and isotopically enriched Si does not cause significant charge-carrier recombination, allowing carriers to contribute to the IBIC signal. The next step is to implant antimony (Sb) donors and determine the corresponding detection confidence. This provides a clear pathway towards the first deterministically implanted Sb donor-qubit device in enriched 28-Si.