Laterally Modulated Composition Profiles in AlAs/InAs Short-Period Superlattices

S. P. Ahrenkiel, A. G. Norman, M. M. Al-Jassim, A. Mascarenhas, J. Mirecki-Millunchick, R. D. Twesten, S. R. Lee, D. M. Follstaedt, E. D. Jones

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Laterally modulated composition profiles in AlAs/InAs short-period superlattices grown by molecular-beam epitaxy under tensile strain on (001) InP are examined by transmission electron microscopy (TEM) and x-ray diffraction K mapping. Weak, one-dimensional modulation with a wavelength of λm=110 Å is observed for a period of 1 ML. At 2 ML, the composition profile is irregular, while a two-dimensional network of wire and dot structures with λm=130 Å occurs at 3 ML. At a high growth rate, 4-ML samples exhibit smooth modulated profiles with λm=220 Å. When the growth rate is reduced with beam interrupts, sharp profiles develop that show strong alignment in the substrate plane with λm=270 Å. TEM dark-field image contrast of the modulated profiles is simulated using dynamical diffraction theory to reproduce features observed in experiment.

Original languageAmerican English
Pages (from-to)6088-6094
Number of pages7
JournalJournal of Applied Physics
Issue number11
StatePublished - 1998

NREL Publication Number

  • NREL/JA-520-24623


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