Electron Scattering Mechanisms in Low-Dimensional Transport Physics

Qin Wang

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)

Sammanfattning

Electron scattering mechanisms in low-dimensional semiconductor systems have been investigated at low temperatures.

The influence of scatterers on magnetotransport in a high-mobility, GaAs/AlGaAs two-dimensional electron gas (2DEG) system was studied. A certain number of scattering centres are introduced into the 2DEGs by proton irradiation and can be removed by annealing. The transport properties were compared before and after irradiation and subsequent annealing.

The Coulomb scattering and alloy scattering in modulation-doped GaInAs/InP quantum wells (QWs) have been studied. To modify the Coulomb scattering, the self-assembled InAs quantum dots located just above the QWs were produced by MOVPE. A top gate was used to control the charging and decharging of the InAs dots. The experimental results show that the Coulomb field from the trapped electrons is important for inter-channel scattering processes between edge channels formed in magnetic fields. Also, the fractional quantum Hall effect (FQHE) is observed in the GaInAs/InP QWs. To the best of our knowledge, this is the first observation of the FQHE in GaInAs/InP quantum wells.

The fabrication and characterization of regrown GaInAs/InP electron waveguides are presented. In particular, the conductance oscillations induced by the formation of longitudinal resonant electron states in the waveguide are observed and analysed.
Originalspråkengelska
KvalifikationDoktor
Tilldelande institution
  • Fasta tillståndets fysik
Handledare
  • [unknown], [unknown], handledare, Extern person
Tilldelningsdatum1999 maj 4
Förlag
ISBN (tryckt)91-628-3436-3
StatusPublished - 1999
Externt publiceradJa

Bibliografisk information

Defence details

Date: 1999-05-04
Time: 10:15
Place: Fysiska institutionens föreläsningssal A

External reviewer(s)

Name: Lindelof, Poul Erik
Title: Prof
Affiliation: Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark

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I. Transport Properties of Proton-Irradiated AlGaAs/GaAs Two-Dimensional Electron Gas StructuresQin Wang, Hongqi Xu, P. Omling, C. Yang and K.G. MalmqvistSubmitted to Nucl. Instr. and Meth. in Phys. Res. B
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II. Defect-Induced Overshoot of Quantum Hall PlateausQin Wang, Hongqi Xu, P. Omling, C. Yang and K.G. MalmqvistSubmitted to J. Appl. Phys.
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III. Ga0.25In0.75As/InP Quantum Wells with Extremely High and Anisotropic Two-Dimensional Electron Gas MobilitiesP. Ramvall, N. Carlsson, P. Omling, L. Samuelson, W. Seifert, M. Stolze and Q.WangAppl. Phys. Lett. 68 (1996) 1111
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IV. Tuning of the Single-Particle Relaxation Time of a High-Mobility Electron Gas in aGa0.25In0.75As/InP Quantum WellP. Ramvall, N. Carlsson, P. Omling, L. Samuelson, W. Seifert and Q. WangAppl. Phys. Lett. 70 (1997) 243
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V. Effects of Charged Self-Assembled Quantum Dots on Two-Dimensional Quantum TransportQin Wang, N. Carlsson, P. Omling, L. Samuelson and W. SeifertTo be submitted to Appl. Phys. Lett.
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VI. Observation of Fractional Quantum Hall Effect in Ga0.25In0.75As/InP Quantum WellsQin Wang, N. Carlsson, P. Omling, L. Samuelson and W. SeifertManuscript
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VII. Quantized Conductance in a Heterostructurally Defined Ga0.25In0.75As/InP QuantumWireP. Ramvall, N. Carlsson, I. Maximov, P. Omling, L. Samuelson, W. Seifert, Q.Wang and S. LourdudossAppl. Phys. Lett. 71 (1997) 918
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VIII. Conductance Oscillations Induced by Longitudinal Resonant States in Hetero- epitaxially Defined Ga0.25In0.75As/InP Electron WaveguidesQin Wang, N. Carlsson, I. Maximov, P. Omling, L. Samuelson, W. Seifert,Weidong Sheng, I. Shorubalko and Hongqi XuSubmitted to Appl. Phys. Lett.

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  • Den kondenserade materiens fysik

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