Optical Hall effect studies on modulation-doped AlxGa 1-xAs:Si/GaAs quantum wells

T. Hofmann, C. Von Middendorff, V. Gottschalch, M. Schubert

Research output: Contribution to journalConference articlepeer-review

2 Scopus citations


We study the temperature (10 K . . . 293 K) dependence of the optical Hall effect (OHE) in modulation-doped AlxGa1-xAs:Si / GaAs (x = 0.45) superlattice structures with different quantum well thickness (d GaAs = 16.9 nm and dGaAs = 3.7 nm) using generalized magnetooptic ellipsometry at far-infrared wavelengths. Free electrons are identified within the wells, but not within the doped barriers. The observed OHE can be fully explained within the Drude model and thermionic rate equations. The quantum-well free electron density (N = 1.3 x 1017 cm -3) increases five times upon sample cooling within the wells with dGaAs = 3.7 nm, and remains constant within the wells with d GaAs = 16.9 nm. We describe this behavior as a steady state of three quantum well electron condensation processes: Coulomb-activation of electron states at the AlxGa1-xAs/GaAs interface, quantum-well-barrier reservoir interaction, and irreversible electron emission into the host crystal. (Graph Presented) Temperature-dependent free electron density within modulation-doped AlxGa1-xAs:Si/GaAs quantum well superlattices. The insert depicts the proposed rate model, which includes reservoir (ER), barrier (B) and host (EG) levels for electron emission or capture by the GaAs well.

Original languageEnglish (US)
Pages (from-to)1386-1390
Number of pages5
JournalPhysica Status Solidi (C) Current Topics in Solid State Physics
Issue number5
StatePublished - 2008
Event4th International Conference on Spectroscopic Ellipsometry, ICSE4 - Stockholm, Sweden
Duration: Jun 11 2007Jun 15 2007

ASJC Scopus subject areas

  • Condensed Matter Physics


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