Lattice deformation at the sub-micron scale: X-ray nanobeam measurements of elastic strain in electron shuttling devices

Abstract

The lattice strain induced by metallic electrodes can impair the functionality of advanced quantum devices operating with electron or hole spins. Here we investigate the deformation induced by CMOS-manufactured titanium nitride electrodes on the lattice of a buried, 10 nm-thick Si/SiGe Quantum Well by means of nanobeam Scanning X-ray Diffraction Microscopy. We were able to measure TiN electrode-induced local modulations of the strain tensor components in the range of $2-8\times 10^{-4}$ with ~60 nm lateral resolution. We have evaluated that these strain fluctuations are reflected into local modulations of the potential of the conduction band minimum larger than 2 meV, which is close to the orbital energy of an electrostatic quantum dot. We observe that the sign of the strain modulations at a given depth of the quantum well layer depends on the lateral dimensions of the electrodes. Since our work explores the impact of device geometry on the strain-induced energy landscape, it enables further optimization of the design of scaled CMOS-processed quantum devices.

16 pages, 6 figures

References in corpus (4)

• Scalable gate architecture for densely packed semiconductor spin qubits
• PyNX: high performance computing toolkit for coherent X-ray imaging based on operators
• Electrical control of uniformity in quantum dot devices
• Non-destructive X-ray imaging of patterned delta-layer devices in silicon

Cited by in corpus (5)

• Mapping of valley-splitting by conveyor-mode spin-coherent electron shuttling
• Utilizing multimodal microscopy to reconstruct Si/SiGe interfacial atomic disorder and infer its impacts on qubit variability
• Atomistic compositional details and their importance for spin qubits in isotope-purified silicon-germanium quantum wells
• Theory of Valley Splitting in Si/SiGe Spin-Qubits: Interplay of Strain, Resonances and Random Alloy Disorder
• Numerical simulation of coherent spin-shuttling in a QuBus with charged defects