---
title: "Researchers study density-driven scattering and valley splitting in undoped Si/SiGe 2DEG; valley splitting ~100 mu-eV, temperature-limited"
sdDatePublished: "2026-08-07T11:29:00Z"
source: "https://www.hzdr.de/publications/Publ-42614"
topics:
  - name: "physics"
    identifier: "medtop:20000731"
locations:
  - "Dresden"
---


Researchers study density-driven scattering and valley splitting in undoped Si/SiGe 2DEG; valley splitting ~100 mu-eV, temperature-limited

Density-driven scattering and valley splitting in undoped Si/SiGe two-dimensional electron system - Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf, HZDR

Density-driven scattering and valley splitting in undoped Si

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Donald Lyngdoh Kynshi, L.; Soni, U.; Sharma, C. H.; Cheng, Y. ; Deneke, K.; Zierold, R.; Zhou, S. ; Blick, R. H.; Shaji, A.; Thalakulam, M.

SiGe two-dimensional electron gas (2DEG) provide an ideal platform for hosting quantum-dot spin-qubits owing enhanced spin dephasing times and compatibility with standard CMOS technology. The strained Si quantum well reduces the valley degeneracy into two closely spaced ones. The existence of a near-degenerate valley state act as a leakage channel and compromises gate fidelity. A robust and uniform valley splitting across the entire chip is crucial for achieving scalability in the architecture and reliability in operation. Imperfections such as broadened interfaces, alloy disorders and atomic steps significantly compromise the valley splitting. The associated scattering mechanisms play detrimental roles in the performance of the qubits. In this manuscript, exploiting low-temperature magnetotransport measurements, we investigate the scattering mechanisms and valley splitting in a high-mobility (mu = 1.6 x 10^6 cm2V-1s-1) undoped Si

SiGe 2DEG. At lower carrier densities, transport is limited by remote impurity scattering, whereas at higher densities, background impurity scattering near the quantum well dominates. Both the transport and quantum lifetimes of the charge carriers increase with carrier concentration, due to the enhancement in the impurity screening. Magnetic-field-induced confinement effect also is found to improve the valley splitting. Visibility of both the spin and valley splitting is influenced by the level broadening due to electron–impurity scattering and temperature. Current-biasing measurements reveals the role of carrier heating in the visibility of valley splitting and reveal a temperature limited valley splitting of delta_V - 100 mu-eV. These results provide critical insight into scattering-dominated regimes and valley splitting in undoped Si

SiGe, advancing its potential for silicon-based quantum devices.

Ion Beam Center DOI: 10.17815

jlsrf-3-159 is cited by this (Id 42614) publication

Journal of Physics: Condensed Matter 38(2026), 315001 DOI: 10.1088

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