Isotopically Selected Co‐Doping of 121Sb and 123Sb Pairs in Silicon

TL;DR

Scientists developed a method to precisely place pairs of antimony isotopes in silicon, which could help build quantum computing systems.

Contribution

A new method for deterministic doping of isotopically defined antimony pairs in silicon is demonstrated.

Findings

Pairs of 121Sb and 123Sb atoms are substitutionally incorporated into silicon with ≈2 nm separation.

Molecular dynamics simulations confirm lattice site preference and fast self-annealing at room temperature.

Single ion cluster detection efficiencies of 94% are achieved with compatibility to low 29Si silicon processing.

Abstract

A reliable route to the deterministic fabrication of impurity ion donors in silicon is required to advance quantum computing architectures based upon such systems. This paper reports the ability to dope isotopically‐defined unique (121Sb123Sb)2+ molecular ions into silicon with measured detection efficiencies of 94% being obtained. Atomically resolved imaging of the doped Sb ions reveals substitutionally incorporated atoms with a Sb‐to‐Sb separation of ≈2 nm post‐implantation, thus indicating suitability to form coupled qudit systems. Molecular dynamics simulations support the preference for doped Sb atoms to occupy lattice sites, driven by fast (≈1s) re‐crystallization of localized ion implantation induced damage at 300 K. The Sb doping method used is fully compatible with integration into processing that includes pre‐enrichment of the silicon host to sub‐3 ppm 29Si levels. As such, we present a potential pathway to the creation of scaled qudit arrays within silicon platforms for quantum computing.

Pairs of 121Sb and 123Sb atoms are doped into silicon using single cluster implantation and found to reside substitutionally within the crystal lattice due to self‐annealing with a Sb‐to Sb separation of ≈2 nm. Molecular dynamics simulations reproduce the observed experimental results and single ion cluster detection efficiencies of 94% are demonstrated.

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