2025/02/28 by Wendoloski, J. P., Hillier, J., Liles, S. D. +17
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · doi:10.48550/arxiv.2502.21173
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 cm2/Vs in a device with a 21 nm oxide layer, and a peak hole mobility of about 2,000 cm2/Vs in a device with 8 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 0.6m0 to 0.7m0, significantly larger than the usually quoted bend-edge mass of 0.22m0. Finally, we perform magnetotransport measurements to extract momentum and quantum scattering lifetimes.