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An alternative approach to synthesizing effective-mass lateral superlattices is proposed. We show theoretically that the coherency strain associated with spontaneous lateral composition modulation provides a negative feedback which results in a band-gap locking phenomenon but that the resulting longitudinal strain wave breaks the symmetry of the valence bands, thereby generating an effective-mass lateral superlattice.

Low-temperature polarized photoluminescence and polarized photoluminescence-excitation spectroscopies are used to probe the electronic structure of GaInP& epilayers grown by organometallic vaporphase epitaxy. The epilayers were grown at various sample temperatures and exhibit difFerent degrees of ordering. A systematic study of the absorption edge and luminescence line shapes provides evidence for a distribution of order parameters, g, within the more ordered samples of this study.

Epitaxial growth of the ordered vacancy compound CuIn3Se5 has been achieved on GaAs (100) by molecular beam epitaxy from Cu2Se and In2Se3 sources. Electron probe microanalysis and x-ray diffraction have confirmed the composition for the 1-3-5 phase and that the films are single-crystal CuIn3Se5 (100). Transmission electron microscopy characterization of the material also showed it to be single crystalline. Structural defects in the layer consisted mainly of stacking faults. Photoluminescence measurements performed at 7.5 K indicate that the band gap is 1.28 eV. Raman spectra reveal a strong polarized peak at 152 cm−1, which is believed to arise from the totally symmetric vibration of the Se atoms in the lattice.

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We have measured the temperature dependence of the Raman frequency and linewidth of the GaPlike LO phonon of random and spontaneously ordered GaInP2 alloys. The width of the asymmetric Raman band is strongly influenced by disorder and the anharmonicity of the lattice. The half-width towards the high-energy side of the Raman band of the GaP-like phonon is independent of temperature, while the half-width on the low-energy side does depend on temperature. Though no obvious differences are observed in the temperature dependence of the Raman spectra of the random and the ordered alloys, the GaP-like Raman band of the ordered samples narrows for incident photon energies near the fundamental gap of the alloy. We attribute the narrowing of the Raman band to the inhomogeneities in the material caused by the existence of a statistical distribution of partially ordered domains with different order parameters g. From the observed width of the dispersion of the Raman linewidth as a function of incident photon energies under resonance conditions, it is concluded that samples grown at higher temperatures possess a narrower distribution of domains.