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Thin films of Sb2Te2Se were prepared by conventional thermal evaporation of the presynthesized material on Corning glass substrates. The chemical composition of the samples was determined by means of energy-dispersive X-ray spectrometry. X-ray diffraction studies on the as-deposited and annealed films revealed an amorphous-to-crystalline phase transition. The as-deposited and annealed films at Ta = 323 and 373 K are amorphous, while those annealed at Ta= 423 and 473 K are crystalline with a single-phase of a rhombohedral crystalline structure as that of the source material. The unit-cell lattice parameters were determined and compared with the reported data. The optical constants (n , k ) of the investigated films were determined from the transmittance and reflectance data at normal incidence in the spectral range 400–2500 nm. The analysis of the absorption spectra revealed non-direct energy gaps, characterizing the amorphous films, while the crystalline films exhibited direct energy gaps. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Nearly stoichiometric thin films of CdGa2Se4 were deposited, by conventional thermal evaporation of presynthesized ingot material, onto quartz and Corning glass substrates. The chemical composition of the samples was determined by means of energy-dispersive X-ray spectrometry. X-ray diffraction studies revealed that the as-deposited and annealed films at Ta = 473 and 573 K have an amorphous phase, while those annealed at Ta ≥ 673 K are crystalline with a single phase of a defective chalcopyrite structure similar to that of the synthesized material. The unit cell lattice parameters of both the synthesized material and the crystalline films were determined and compared with reported data. The optical constants (n, k) and the film thickness (t) of the films were determined from optical transmittance data using the Swanepoel method. The dispersion parameters were determined from an analysis of the refractive index. An analysis of the optical absorption spectra revealed a non-direct energy gap characterizing the amorphous films, while a direct energy gap characterized the crystalline films. The annealing temperature dependence of the corresponding energy gaps was found to fit a polynomial equation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The influence of the Cu-content in the quaternary compounds CuxAg1-xInTe2 (0 ≤ x ≤1) on the structural properties of the bulk material was discussed. Bulk ingot materials of CuxAg1-xInTe2 solid solutions (x = 0.0, 0.25, 0.50, 0.75 and 1.0) have been synthesized by fusion of the constituent elements in the stoichiometric ratios in vacuum-sealed silica tubes. The materials compositions were confirmed by using energy dispersive analysis of X-rays (EDAX). X-ray powder diffraction measurements were performed for all the prepared samples at 300 K in step scanning mode. The analysis of X-ray data has indicated that the crystal structure of the prepared materials with different compositions is single-phase polycrystalline materials corresponding to the tetragonal chalcopyrite structure with space group I$ \bar 4 $2d. The crystal structural parameters were refined by Rietveld method using the Full Prof program. The refined lattice constants (a and c), anion positional parameter, u, and the determined bond distances and angles were found to vary with composition, x, attaining zero tetragonal distortion at x ≈ 0.75, which corresponds to an ideal tetragonal unit cell. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Polycrystalline ingot of AgGa0.5In0.5Te2 was synthesized. Thin films of AgGa0.5In0.5Te2 were prepared by thermal evaporation of the prereacted material on Corning glass substrates. Chemical composition of the starting material as well as thin films has been revealed that they are nearly stoichiometric. The crystal structure and the unit cell lattice parameters of both the starting material and thin films were determined from X-ray diffraction (XRD) studies. It has been revelead that the as-deposited and annealed films at 373, 423 K are amorphous, while those annealed at 473 and 523 K are polycrystalline with single-phase of a tetragonal chalcopyrite structure as that of bulk material. The optical absorption, of the annealed films at 523 K, was determined from the optical transmittance data. Three characteristics energy gaps of 1.142, 1.213 and 1.907 eV were obtained from an analysis of the optical absorption spectrum. The band structure of AgGa0.5In0.5Te2 at the center of the Brillouin zone was investigated and the d-like character was determined to be 19.87%. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Thin films of CuxAg1–xInTe2 solid solutions (x = 0.25, 0.50 and 0.75) were deposited by thermal evaporation of prereacted materials on glass substrates. X-ray diffraction (XRD) studies has revealed that the as-deposited and thermally annealed films are polycrystalline with single-phase of a tetragonal chalcopyrite structure as that of bulk material with (112) predominant reflecting plane. The films compositions were confirmed by using energy dispersive analysis of X-rays (EDAX). The refractive index, n, and the extinction coefficient, k, of the annealed films with different compositions were determined in the spectral range, 400–2500 nm. Three characteristic energy gaps have been determined from the analysis of optical absorption spectrum for each composition. The three energy gaps are attributed to the optical transitions from the valence sub-bands to the conduction band minimum. Besides, a fourth energy gap has also been obtained for each composition, which may be attributed to the transition from the copper 3d-level to the conduction band minimum. However, the band gaps showed linear variation with the value of x.

In this paper, we report the effect of sulfur doping on the electrical and dielectric properties of semiconducting Sb2Se2S over wide ranges of temperatures (298–473K) and frequencies (42–106Hz). Sb2Se2S system has been prepared by the direct fusion and cooling cycle of a mixture of the constituent elements, in stoichiometric ratio and purity 99.999%, in vacuum-sealed silica tubes. X-ray analysis showed a decrease in the cell parameters a, band cupon doping with sulfur. However, the pure and doped Sb2Se3showed the single orthorhombic phase structure. The permittivity of Sb2Se2S showed a decrease with increasing frequency due to a decrease in the average bond strength. While, ac conductivity increased with the frequency increase, obeying the Jonscher’s universal dynamic law. The conductivity temperature dependence is well described by the correlated barrier hopping model. The activation energy calculated from DC conductivity is found at higher value (0.79eV) as compared to that reported in the literature for other antimony selenide compounds. Accordingly, a new Sb2Se2S compound is suggested which may be useful for electronic devices.

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