Low disorder and high valley splitting in silicon

Davide Degli Esposti, Lucas E.A. Stehouwer, Önder Gül, Nodar Samkharadze, Corentin Déprez, Marcel Meyer, Ilja N. Meijer, Larysa Tryputen, Saurabh Karwal, Lieven M.K. Vandersypen, Amir Sammak, Menno Veldhorst, Giordano Scappucci*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

The electrical characterisation of classical and quantum devices is a critical step in the development cycle of heterogeneous material stacks for semiconductor spin qubits. In the case of silicon, properties such as disorder and energy separation of conduction band valleys are commonly investigated individually upon modifications in selected parameters of the material stack. However, this reductionist approach fails to consider the interdependence between different structural and electronic properties at the danger of optimising one metric at the expense of the others. Here, we achieve a significant improvement in both disorder and valley splitting by taking a co-design approach to the material stack. We demonstrate isotopically purified, strained quantum wells with high mobility of 3.14(8) × 105 cm2 V−1 s−1 and low percolation density of 6.9(1) × 1010 cm−2. These low disorder quantum wells support quantum dots with low charge noise of 0.9(3) μeV Hz−1/2 and large mean valley splitting energy of 0.24(7) meV, measured in qubit devices. By striking the delicate balance between disorder, charge noise, and valley splitting, these findings provide a benchmark for silicon as a host semiconductor for quantum dot qubits. We foresee the application of these heterostructures in larger, high-performance quantum processors.

Original languageEnglish
Article number32
Number of pages9
JournalNPJ Quantum Information
Volume10
Issue number1
DOIs
Publication statusPublished - 2024

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