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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.

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.

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Raman and resonance Raman spectroscopic techniques have been utilized to study the phenomenon of spontaneous ordering in epitaxial Gao»Ino 48P grown on (001) GaAs substrates at difterent temperatures. Raman selection rules suggest larger deviations from cubic zinc-blende symmetry for samples exhibiting a greater degree of ordering. Raman excitation profiles show a redshift and broadening of the resonance peak as the samples become more ordered. In addition, the anisotropy of the absorption coefficients along the [110] and [110]crystallographic directions in the rhombohedral phase of the ordered material enables us to estimate the crystal-field splitting. Our results support the recently proposed microstructural model for ordering in these alloys.

We present a Raman scattering study of optical phonons in α-Sn1−xGex alloys (x≤0.08) grown by molecular beam epitaxy on CdTe (100) substrates. The Raman spectra provide strong evidence for the growth of high quality films in the diamond-structure phase. The composition dependence of the Raman modes shows some qualitative differences with results from the isomorphic Ge1−xSix system. We show that these differences can be understood in terms of a simple model that considers confinement and strain effects.