1. Holes in silicon are heavier than expected: transport properties of extremely high mobility electrons and holes in silicon MOSFETs
- Author
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Wendoloski, J. P., Hillier, J., Liles, S. D., Rendell, M., Ashlea-Alava, Y., Raes, B., Li, R., Kubicek, S., Godfrin, C., Jussot, J., Beyne, S., Wan, D., Rahman, Md. M., Yianni, S., Chan, K. W., Hudson, F. E., Lim, W. H., De Greve, K., Dzurak, A. S., and Hamilton, A. R.
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
The quality of the silicon-oxide interface plays a crucial role in fabricating reproducible silicon spin qubits. In this work we characterize interface quality by performing mobility measurements on silicon Hall bars. We find a peak electron mobility of nearly $40,000\,\text{cm}^2/\text{Vs}$ in a device with a $21\,\text{nm}$ oxide layer, and a peak hole mobility of about $2,000\,\text{cm}^2/\text{Vs}$ in a device with $8\,\text{nm}$ oxide, the latter being the highest recorded mobility for a p-type silicon MOSFET. Despite the high device quality, we note an order-of-magnitude difference in mobility between electrons and holes. By studying additional n-type and p-type devices with identical oxides, and fitting to transport theory, we show that this mobility discrepancy is due to valence band nonparabolicity. The nonparabolicity endows holes with a density-dependent transverse effective mass ranging from $0.6m_0$ to $0.7m_0$, significantly larger than the usually quoted bend-edge mass of $0.22m_0$. Finally, we perform magnetotransport measurements to extract momentum and quantum scattering lifetimes.
- Published
- 2025