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We have determined the complex dielectric tensor components of the chalcopyrite semiconductor CuAlSe2 in the energy range between 1.4 and 5.2 eV, at room temperature, using spectroscopic ellipsometry. We present results obtained on two single crystals grown by the traveling-heater method using In solvent. Values of refractive indices n, extinction coefficients k and normal-incidence reflectivity R in the two independent polarizations are reported. The structures observed in the energy region studied are analyzed by fitting the second-derivative spectra d2ε(ω)/dω2 to analytic critical-point line shapes. The obtained energies are assigned to certain electronic interband transitions by comparison with existing band structure calculations.

Resonant Raman scattering and luminescence have been examined for CuInS2 crystals grown by the traveling heater method (THM) and the iodine vapor transport method (IT). Resonant Raman spectra of CuInS2 have been observed, and the spectra show seven single-phonon peaks and one two-phonon peak. Among them, three single-phonon modes have been found in the low-Raman-shift region because of resonant enhancement of phonon modes. The enhancement of these phonon modes is caused by incoming resonance mediated by bound excitons on the THM crystal, while it is attributed to outgoing resonance due to intermediate states of free excitons on the IT crystal.

The ternary layered Tl-contained semiconductor ferroelectrics TlInS2, TlGaS2, and TlGaSe2, exhibiting an incommensurate phase and a relaxor state with temperature, were approached down to 0.76eV at room temperature by spectroscopic phase modulated ellipsometry in a region below the energy gap of each material. By using both coherent and incoherent reflection modes on only the layer-plane surfaces, the refractive indices in the parallel- and perpendicular-to-the-layers directions of the light propagation were determined. Sellmeier single-oscillator form was used to fit the model data to the experimental intensities. The discrepancy between the model and experimental data was shown to be negligible. Besides, a self-consistent picture of the obtained refraction indices was emerging after the discussion based on the available data for the studied materials. The applied experimental approach was thus found to be quite effective for layered materials, and the obtained refractive indices might be used for database with high degree of confidence.