Abstract
Across solid state quantum information, materials deficiencies limit performance through enhanced relaxation, charge defect motion or isotopic spin noise. While classical measurements of device performance provide cursory guidance, specific qualifying metrics and measurements applicable to quantum devices are needed. For quantum applications, new materials metrics, e.g., enrichment, are needed, while existing, classical metrics like mobility might be relaxed compared to conventional electronics. In this work, we examine locally grown silicon superior in enrichment, but inferior in chemical purity compared to commercial-silicon, as part of an effort to underpin the materials standards needed for quantum grade silicon and establish a standard approach for intercomparison of these materials. We use a custom, mass-selected ion beam deposition technique, which has produced isotopic enrichment levels up to 99.99998 % 28Si, to isotopically enrich 28Si, but with chemical purity > 99.97% due the MBE techniques used. From this epitaxial silicon, we fabricate top-gated Hall bar devices simultaneously on the 28Si and on the adjacent natural abundance Si substrate for intercomparison. Using standard-methods, we measure maximum mobilities of at an electron density of cm-2 and at an electron density of cm-2 at K for devices fabricated on 28Si and natSi, respectively. For magnetic fields T, both devices demonstrate well developed Shubnikov-de Haas (SdH) oscillations in the longitudinal magnetoresistance. This provides transport characteristics of isotopically enriched 28Si, and will serve as a benchmark for classical transport of 28Si at its current state, and low temperature, epitaxially grown Si for quantum devices more generally.
Highlights
Nuclei with nonzero spin in the host lattice act as a source of decoherence for spin based qubits,[7] as they interact with the electron spin through hyperfine interactions.[8,9] by placing a spin qubit in an isotopically enriched 99.995% 28Si environment,[10] the development of silicon based quantum devices has gained considerable momentum, with reports of exceptionally long quantum coherence times.[11,12]
We examine locally grown silicon that is superior in enrichment, but inferior in chemical purity compared to commercial-silicon, as part of an effort to underpin the material standards needed for quantum grade silicon and establish a standard approach for the intercomparison of these materials
As part of a larger program to identify and quantify “quantum grade” silicon, we are identifying (1) properties beyond those considered for semiconductor grade silicon critical to quantum; (2) the relevance and priority of properties currently considered critical for semiconductors; and (3) standard methods that may be used for new properties or provide a general indicator for challenging properties, e.g., coherence time, as three main goals that are paramount for the development of metrics for “quantum grade” silicon
Summary
Nuclei with nonzero spin in the host lattice act as a source of decoherence for spin based qubits,[7] as they interact with the electron spin through hyperfine interactions.[8,9] by placing a spin qubit in an isotopically enriched 99.995% 28Si environment,[10] the development of silicon based quantum devices has gained considerable momentum, with reports of exceptionally long quantum coherence times.[11,12].
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call