Microcharacterization of Composition Modulations in Epitaxial ZnSe1-xTex

S. P. Ahrenkiel, M. H. Bode, M. M. Al-Jassim, H. Luo, S. H. Xin, J. K. Furdyna

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Abstract

Molecular beam epitaxial growth of the ZnSe1-xTex (x=0.44-0.47) alloy on vicinal (001) GaAs substrates tilted four, six, and nine degree-[111]A or B results in partial phase separation of the alloy with a vertical modulation between different compositions. Transmission electron microscopy images of samples grown on four degree-tilted substrates showed superlattice-like structures, with periods in the range 13.4-28.9Â. Lattice images reveal diffuse interfaces between light and dark bands. Period variations were detected in isolated regions of some samples. We present evidence that the modulation develops at the growth surface, and remains stable in the bulk at temperatures up to 450°C. Satellite spot pairs with approximate indices (h k 1 + δ) were present near the zinc-blende spots in electron diffraction patterns and x-ray diffraction data, as expected from material with a sinusoidal composition profile. The orientation of the spots reveals that the modulation vector is parallel to the growth direction, rather than to [001]. The [111]A- and B-tilted samples showed significant modulation, while the five degree-[110] and on-axis material showed no detectable modulation. The modulation wavelength did not strongly depend on growth temperature in the range examined (285-335°C). Samples showing composition modulation did not exhibit significantly altered low-temperature luminescence spectra from material with no modulation.

Original languageAmerican English
Pages (from-to)319-325
Number of pages7
JournalJournal of Electronic Materials
Volume24
Issue number4
DOIs
StatePublished - 1995

NREL Publication Number

  • NREL/JA-412-7176

Keywords

  • Composition modulation
  • molecular beam epitaxy (MBE)
  • transmission electron microscopy (TEM)
  • ZnSeTe

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