Enriching 28Si beyond 99.9998% for semiconductor quantum computing

Using a laboratory-scale apparatus, we enrich Si-28 and produce material with 40 times less residual Si-29 than previously reported. Starting from natural abundance silane gas, we offer an alternative to industrial gas centrifuges for providing materials critical for long spin coherence times in quantum information devices. Using a mass spectrometry approach, silicon ions are produced from commercial silane gas and the isotopes are separated in a magnetic sector analyzer before deposition onto a Si(1 0 0) substrate. Isotope fractions for Si-29 and Si-30 of < 1 x 10(-6) are found in the deposited films using secondary ion mass spectrometry. Additional assessments of the deposited films are also presented as we work to develop substrates and source material to support the growing silicon quantum computing community. Finally, we demonstrate modulation of the Si-29 concentration in a deposited film as a precursor to dual enrichment of heterostructures and compound materials such as (SiGe)-Si-28-Ge-74.