Electron transport in coupled double quantum wells and wires

Technical Report · Tue Apr 01 04:00:00 EST 1997

DOI:https://doi.org/10.2172/477761· OSTI ID:477761

Harff, N E; Simmons, J A; Lyo, S K ^[1]

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1. and others

Due to inter-quantum well tunneling, coupled double quantum wells (DQWs) contain an extra degree of electronic freedom in the growth direction, giving rise to new transport phenomena not found in single electron layers. This report describes work done on coupled DQWs subject to inplane magnetic fields B{sub {parallel}}, and is based on the lead author`s doctoral thesis, successfully defended at Oregon State University on March 4, 1997. First, the conductance of closely coupled DQWs in B{sub {parallel}} is studied. B{sub {parallel}}-induced distortions in the dispersion, the density of states, and the Fermi surface are described both theoretically and experimentally, with particular attention paid to the dispersion anticrossing and resulting partial energy gap. Measurements of giant distortions in the effective mass are found to agree with theoretical calculations. Second, the Landau level spectra of coupled DQWs in tilted magnetic fields is studied. The magnetoresistance oscillations show complex beating as Landau levels from the two Fermi surface components cross the Fermi level. A third set of oscillations resulting from magnetic breakdown is observed. A semiclassical calculation of the Landau level spectra is then performed, and shown to agree exceptionally well with the data. Finally, quantum wires and quantum point contacts formed in DQW structures are investigated. Anticrossings of the one-dimensional DQW dispersion curves are predicted to have interesting transport effects in these devices. Difficulties in sample fabrication have to date prevented experimental verification. However, recently developed techniques to overcome these difficulties are described.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Office of Financial Management and Controller, Washington, DC (United States)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 477761
• Report Number(s): SAND--97-0910; ON: DE97006217
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CHARGED-PARTICLE TRANSPORT
ELECTRON TRANSFER
FERMI LEVEL
GALLIUM ARSENIDES
HALL EFFECT
MAGNETIC FIELDS
QUANTUM MECHANICS
SEMICONDUCTOR MATERIALS