Well-width dependence of valley splitting in Si/SiGe quantum wells

TL;DR

This study investigates how the width of Si/SiGe quantum wells affects valley splitting, revealing that narrower wells exhibit significantly larger energy gaps, which is crucial for quantum computing applications.

Contribution

It provides experimental evidence of the well-width dependence of valley splitting in Si/SiGe quantum wells, linking well width to energy gap magnitudes.

Findings

Narrower wells (4-5.3 nm) have larger valley splitting energy gaps.

Larger gaps are consistent with estimates from Zeeman splitting analysis.

Valley splitting decreases with increasing well width.

Abstract

The valley splitting in Si two-dimensional electron systems is studied using Si/SiGe single quantum wells (QWs) with different well widths. The energy gaps for 4 and 5.3 nm QWs, obtained from the temperature dependence of the longitudinal resistivity at the Landau level filling factor $\nu=1$, are much larger than those for 10 and 20 nm QWs. This is consistent with the well-width dependence of the bare valley splitting estimated from the comparison with the Zeeman splitting in the Shubnikov-de Haas oscillations.