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 $40000{\text{cm}}^2/\text{Vs}$ in a device with a $21\text{nm}$ oxide layer, and a peak hole mobility of about $2000{\text{cm}}^2/\text{Vs}$ 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 band-edge mass of $0.22m_0$. Finally, we perform magnetotransport measurements to extract electron momentum and quantum scattering lifetimes.

Close

PrevNext

View figure in article

• Electrical conductivity
• Electrical properties
• Electronic structure
• Transport phenomena