Targeted enrichment of ²⁸Si thin films for quantum computing

Area of Science:

• Materials Science
• Quantum Computing
• Semiconductor Physics

Background:

• Isotopically enriched silicon-28 (²⁸Si) is a promising host for quantum computing due to its nuclear spin-free nature.
• Understanding quantum decoherence mechanisms and required enrichment levels in ²⁸Si is critical for advancing quantum technologies.
• Precise control over isotopic composition is essential for fabricating high-performance quantum devices.

Purpose of the Study:

• To report on the growth of isotopically enriched ²⁸Si epitaxial films with precisely controlled enrichment levels.
• To investigate the feasibility of achieving ultra-high purity ²⁸Si for quantum computing applications.
• To develop and validate a predictive model for residual silicon-29 (²⁹Si) concentration.

Main Methods:

• Epitaxial growth of ²⁸Si films using hyperthermal energy ion beam deposition with silane gas.
• Mass-selective magnetic field switching to precisely control ²⁹Si concentration during deposition.
• Development of a predictive model correlating deposition parameters with residual ²⁹Si fraction.
• Secondary Ion Mass Spectrometry (SIMS) for accurate measurement of ²⁹Si concentration in deposited films.

Main Results:

• Successfully grew ²⁸Si epitaxial films with enrichment levels ranging from natural abundance to 99.99987% purity.
• Achieved precise control over ²⁹Si concentration, a key factor for quantum decoherence mitigation.
• The developed predictive model showed excellent agreement with SIMS measurements, with an average deviation of only 10%.

Conclusions:

• The ion beam deposition technique allows for highly controlled isotopic enrichment of ²⁸Si films.
• This method provides a pathway to produce the ultra-pure ²⁸Si required for advanced quantum computing.
• The validated predictive model facilitates the optimization of deposition parameters for desired isotopic compositions.