Ion Implantation & Irradiation
 Ella Schneider

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Ella Schneider and Jonathan England; ACS Applied Materials & Interfaces 2023 15 (17), 21609-21617 DOI: 10.1021/acsami.3c01112

Isotopically Enriched Layers for Quantum Computers Formed by 28Si Implantation and Layer Exchange

☐  28Si enrichment is crucial for production of group IV semiconductor-     based quantum computers. Cryogenically cooled, monocrystalline           28Si is a spin-free, vacuum-like environment where qubits are                 protected from sources of decoherence that cause loss of quantum         information.

☐  Here we report on a novel enrichment process involving ion                     implantation of 28Si into Al films deposited on native-oxide free Si         substrates followed by layer exchange crystallization. We measured       continuous, oxygen-free epitaxial 28Si enriched to 99.7%. Increases         in isotopic enrichment are possible, and improvements in crystal             quality, aluminum content, and thickness uniformity are required           before the process can be considered viable.

☐  Required implant fluences are an order of magnitude lower than             those required for enrichment by direct 28Si implants into Si and             can be chosen to control the final thickness of the enriched layer. We       show that implanted layer exchange could potentially produce                 quantum grade 28Si using conventional semiconductor foundry               equipment within production-worthy time scales.

☐  Currently, 28Si enrichment techniques rely on deposition of  centrifuged SiF4 gas, the source of which is not widely available, or bespoke ion implantation methods. Previously, conventional ion implantation into naturalSi substrates has produced heavily oxidized 28Si layers.