Low disorder and high valley splitting in silicon

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)$\times$10${}^5$ cm${}^2$/Vs and low percolation density of 6.9(1)$\times$10${}^{10}$ cm${}^{-2}$. These low disorder quantum wells support quantum dots with low charge noise of 0.9(3) $\mu$eV/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.

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Cited by in corpus (20)

• Mapping of valley-splitting by conveyor-mode spin-coherent electron shuttling
• High-fidelity spin qubit shuttling via large spin-orbit interaction
• Atomistic compositional details and their importance for spin qubits in isotope-purified silicon-germanium quantum wells
• Industrially fabricated single-electron quantum dots in Si/Si-Ge heterostructures
• Theory of Valley Splitting in Si/SiGe Spin-Qubits: Interplay of Strain, Resonances and Random Alloy Disorder
• Reducing disorder in Ge quantum wells by using thick SiGe barriers
• Artificial Intelligence-Assisted Workflow for Transmission Electron Microscopy: From Data Analysis Automation to Materials Knowledge Unveiling
• Leveraging Off-the-Shelf Silicon Chips for Quantum Computing
• Valley Splitting Correlations Across a Silicon Quantum Well Containing Germanium
• Annual-modulation fingerprint of the axion wind induced sideband triplet in quantum dot spin qubit sensors
• Bound state-continuum resonance transition in a shallow quantum well
• Variability of hole spin qubits in planar Germanium
• The effects of alloy disorder on strongly-driven flopping mode qubits in Si/SiGe
• Fabrication, characterization and mechanical loading of Si/SiGe membranes for spin qubit devices
• Proposed Five-Electron Charge Quadrupole Qubit
• Towards Utilizing Scanning Gate Microscopy as a High-Resolution Probe of Valley Splitting in Si/SiGe Heterostructures
• Omnidirectional shuttling to avoid valley excitations in Si/SiGe quantum wells
• Micromagnet-free operation of electron spin qubits in Si/Si${}_{1-x}$Ge${}_x$ vertical double quantum dots
• Effects of valley splitting on resonant-tunneling readout of spin qubits
• Exact Multi-Valley Envelope Function Theory of Valley Splitting in Si/SiGe Nanostructures