10 May 1984 Magneto-Raman And Magneto-Photoluminescence Characterization Of MQW Heterostructures
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Raman scattering and photoluminescence spectroscopy in the presence of high magnetic fields (0-19 Tesla) have proved to be sensitive and fruitful techniques for investigating the behaviour of two dimensional (2D) electrons in multiquantum well (MQW) heterostructures. A systematic study of MQW GaAs-AlxGa1-xAs samples, grown by MBE and modulation doped with Si to give electron areal densities in the range of 2-7x10" cm-2 has been undertaken. Two kinds of field dependent excitations are observed in the Raman spectra that are characteristic of clean, well defined 2D layers. One corresponds to transitions between Landau levels (cyclotron resonance); the other is a collective magneto-plasma mode.The effect of magnetic field on the luminescence spectra from the recombination of 2D electrons with photo injected holes is marked at fields as low as 2 Tesla. The electron continuum breaks in Landau levels related to electron exchange energy and competition for dominance in the valence band between confinement and magnetic field effects. At higher fields, the peak luminescence efficiencies increase with a concomitant decrease in the individual line widths. Discrete slope changes are observed and the lowest Landau transitions split into circularly polarized doublets. The magnetic field dependent luminescence spectra in the Si modulation doped MQW heterostructures is manifestly different from the behavior of free excitons and electronic transitions associated with ionized donor, acceptor or neutral impurities. Consequently both magneto-Raman and -photoluminescence techniques offer a non-destruc-tive method of characterizing these materials.
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A. Petrou, A. Petrou, C. H. Perry, C. H. Perry, M. C. Smith, M. C. Smith, J. M. Worlock, J. M. Worlock, R. L. Aggarwal, R. L. Aggarwal, A. C. Gossard, A. C. Gossard, W. Wiegmann, W. Wiegmann, "Magneto-Raman And Magneto-Photoluminescence Characterization Of MQW Heterostructures", Proc. SPIE 0452, Spectroscopic Characterization Techniques for Semiconductor Technology I, (10 May 1984); doi: 10.1117/12.939289; https://doi.org/10.1117/12.939289

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