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Fractional Quantum Hall States in a Ge Quantum Well.
O A Mironov1, N d'Ambrumenil2, A Dobbie2
1Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom and International Laboratory of High Magnetic Fields and Low Temperatures, 95 Gajowicka Street, 53-421 Wroclaw, Poland.
Physical Review Letters
|May 14, 2016
Summary
This study investigates carrier behavior in strained Germanium (Ge) quantum wells under quantum Hall conditions. Findings reveal thermally activated quantum tunneling across impurity potentials, aligning with theoretical predictions for energy gaps.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Semiconductor Physics
Background:
- Quantum Hall effect studies are crucial for understanding electron behavior in 2D systems.
- Strained Germanium (Ge) quantum wells on Silicon-Germanium (SiGe) offer unique electronic properties.
- Impurity potentials significantly influence carrier dynamics in low-dimensional structures.
Purpose of the Study:
- To measure and analyze Hall and dissipative conductivity in strained Ge quantum wells.
- To investigate carrier transport mechanisms, specifically quantum tunneling, in the quantum Hall regime.
- To compare experimental observations with theoretical models and electrostatic predictions.
Main Methods:
- Measurements of Hall and dissipative conductivity.
- Analysis of data within the quantum Hall regime.
- Characterization of strained Ge quantum wells on SiGe/(001)Si substrates.
Main Results:
- Observed thermally activated quantum tunneling between internal edge states.
- Demonstrated that energy gaps at different filling fractions match theoretical predictions.
- Found agreement between electrostatic model predictions and experimental estimates of edge state separation in the lowest spin-polarized Landau level (LL).
Conclusions:
- The study confirms theoretical predictions for energy gaps in strained Ge quantum wells.
- Discrepancies in spin-reversed LL suggest limitations in current electrostatic models for edge state separation.
- Highlights the importance of carrier density and quasiparticle states in understanding transport phenomena.
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