Effect of Quantum Hall Edge Strips on Valley Splitting in Silicon Quantum Wells
Brian Paquelet Wuetz (Kavli institute of nanoscience Delft, TU Delft - QCD/Scappucci Lab, TU Delft - QuTech Advanced Research Centre)
Merritt P. Losert (University of Wisconsin-Madison)
Alberto Tosato (Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre, TU Delft - QCD/Scappucci Lab)
Mario Lodari (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - QCD/Scappucci Lab)
Peter L. Bavdaz (Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre, TU Delft - QCD/Scappucci Lab)
Lucas Stehouwer (Kavli institute of nanoscience Delft, Student TU Delft)
Amir Sammak (TU Delft - Business Development, TNO)
Menno Veldhorst (Kavli institute of nanoscience Delft, TU Delft - QCD/Veldhorst Lab, TU Delft - QuTech Advanced Research Centre)
Giordano Scappucci (TU Delft - QCD/Scappucci Lab, Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre)
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Abstract
We determine the energy splitting of the conduction-band valleys in two-dimensional electrons confined to low-disorder Si quantum wells. We probe the valley splitting dependence on both perpendicular magnetic field B and Hall density by performing activation energy measurements in the quantum Hall regime over a large range of filling factors. The mobility gap of the valley-split levels increases linearly with B and is strikingly independent of Hall density. The data are consistent with a transport model in which valley splitting depends on the incremental changes in density eB/h across quantum Hall edge strips, rather than the bulk density. Based on these results, we estimate that the valley splitting increases with density at a rate of 116 μeV/1011 cm-2, which is consistent with theoretical predictions for near-perfect quantum well top interfaces.