Electric-field tuning of the valley splitting in silicon corner dots

• Published in: Applied physics letters Vol. 113; no. 5
• Main Authors: Ibberson, D. J., Bourdet, L., Abadillo-Uriel, J. C., Ahmed, I., Barraud, S., Calderón, M. J., Niquet, Y.-M., Gonzalez-Zalba, M. F.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 30-07-2018
• Subjects: Applied physics; Condensed Matter; Dependence; Electric fields; Excitation spectra; Field effect transistors; Materials Science; Nanowires; Physics; Quantum dots; Qubits (quantum computing); Semiconductor devices; Silicon; Splitting; Surface roughness; Tuning
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5040474

We perform an excited state spectroscopy analysis of a silicon corner dot in a nanowire field-effect transistor to assess the electric field tunability of the valley splitting. First, we demonstrate a back-gate-controlled transition between a single quantum dot and a double quantum dot in parallel which allows tuning the device into corner dot formation. We find a linear dependence of the valley splitting on back-gate voltage, from 880 μeV to 610 μeV with a slope of −45 ± 3 μeV/V (or equivalently a slope of −48 ± 3 μeV/(MV/m) with respect to the effective field). The experimental results are backed up by tight-binding simulations that include the effect of surface roughness, remote charges in the gate stack, and discrete dopants in the channel. Our results demonstrate a way to electrically tune the valley splitting in silicon-on-insulator-based quantum dots, a requirement to achieve all-electrical manipulation of silicon spin qubits.