Targeted enrichment of <sup>28</sup>Si thin films for quantum computing
Ke Tang, Hyun Sik Kim, Aruna Ramanayaka, David S. Simons, J. M. Pomeroy
Abstract
Abstract We report on the growth of isotopically enriched 28 Si epitaxial films with precisely controlled enrichment levels, ranging from natural abundance ratio of 92.2% all the way to 99.99987% (0.832 × 10 −6 mol mol −1 29 Si). Isotopically enriched 28 Si is regarded as an ideal host material for semiconducting quantum computing due to the lack of 29 Si nuclear spins. However, the detailed mechanisms for quantum decoherence and the exact level of enrichment needed for quantum computing remain unknown. Here we use hyperthermal energy ion beam deposition with silane gas to deposit epitaxial 28 Si. We switch the mass selective magnetic field periodically to control the 29 Si concentration. We develop a model to predict the residual 29 Si isotope fraction based on deposition parameters and measure the deposited film using secondary ion mass spectrometry (SIMS). The measured 29 Si concentrations show excellent agreement with the prediction, deviating on average by only 10%.