Oral: Enhancing Valley Splitting in Si Quantum Dots Using TiN Stressors for Shear Strain in Wiggle Well Heterostructures

Silicon quantum dots are a promising platform for quantum computing, but the energy splitting of the conduction band valley states presents a challenge for creating well-behaved qubits. The recently developed Wiggle Well, a heterostructure with an oscillating concentration of Ge within a predominantly Si quantum well, offers a potential solution [1]. Theoretical studies suggest that introducing shear strain into this structure can lead to significantly larger valley splitting energies [2]. In this work, we propose a novel design to implement shear strain in the quantum well by depositing TiN stressors along the [110] direction. Our theoretical calculations indicate that with a reasonable deposition stress of approximately -2.6 GPa, it is possible to induce up to 0.15% shear strain in the quantum well, which is expected to enhance the valley splitting energy to ~200 μeV. This approach offers a promising path toward scalable quantum dot implementation in Wiggle Well heterostructures.



1. "SiGe quantum wells with oscillating Ge concentrations for quantum dot qubits.” Thomas McJunkin, et al., Nat Commun 13, 7777 (2022).

2. “Coupling conduction-band valleys in SiGe heterostructures via shear strain and Ge concentration oscillations.” Benjamin D. Woods, et al., npj Quantum Inf 10, 54 (2024).