80 research outputs found
Ion distribution preferences in ternary crystals Zn xCd 1−x Te, Zn 1−x Hg xTe and Cd 1−x Hg xTe
No full textSimilar ternary semiconductors are sometimes associated with widely different structures characterized by different site occupation preferences. We have used far-infrared (FIR) spectra to determine the site occupation preference coefficients for three ternary semiconductor alloys: ZnCdTe, ZnHgTe and CdHgTe and, in the case of ZnHgTe, have validated it by X-ray absorption fine structure (EXAFS) analysis. While ZnCdTe spectra exhibit the canonical configuration with eight phonon lines free of vibrational defect lines and only a slight departure from a random ion distribution, CdHgTe spectra show the eight canonical phonon modes plus an additional vibrational defect line and constant preference coefficients. In contrast, two defect lines and only four modes characterize ZnHgTe spectra, as extreme preferences prevent the formation of two of the five expected tetrahedral configuration arrangements. Moreover, for this system, comparison with EXAFS data points out the vibrational nature of both the extra lines. The analysis clearly shows that assuming a Bernoulli distribution of the component configurations of semiconductors may lead to wrong assessments of the evolution of its properties with relative content.JRC.D.5 - Food Safety and Qualit
Statistical model structure of A1−xZxB2 Laves phase C15 system—the superconducting alloy Ce1−xLaxRu
No full textThe local structure of the Ce1−xLaxRu2 system measured by EXAFS is re-examined and correlated to the statistical ad hoc model recently applied to the sphalerite, wurtzite, and other intermetallic ternary alloys. Deconvolution of the EXAFS data shows that the Ce1−xLaxRu2 ternary system is essentially a mixture of CeRu2 and LaRu2 binary alloys with a small proportion of the Ce0.5La0.5Ru2 ternary configuration, which is maximum for the intermediate concentration. Moreover, the analysis reveals that while the LaRu2 configuration exhibits a Bernoulli random distribution, the presence of a Ce atom affects both the CeRu2 and Ce0.5La0.5Ru2 distributions, strongly favoring the configuration with the CeCe pair, while keeping rare that with a single Ce ion
High resolution spectra of defects in CdTe obtained in far-infrared region using synchrotron radiation
No full textThe present work analyses the lattice deformations induced in the crystals with tetrahedral coordination by the presence of impurity hydrogen and oxygen atoms. Such deformations can be monitored by analyzing of far-infrared (FIR) vibration spectra. FIR experiments carried out on hydrogenated CdTe crystals that successfully revealed the presence and localization of hydrogen atoms within the lattice. (c) 2006 Elsevier B.V. All rights reserved
Vibrational spectra of hydrogenated CdTe
No full textInfrared spectroscopy may deliver important information on defects created in CdTe monocrystals grown from Cd and Te components purified in a hydrogen atmosphere before the crystallization process. Reflectivity spectra on different CdTe samples were collected with a FTIR spectrometer using a standard Hg lamp and the IR synchrotron radiation source of the DAFNE synchrotron facility at Frascati. In the 500-2000 cm(-1) frequency region, the characteristic vibrational spectra of oxygen and hydrogen bounded to Cd and Te in the monocrystalline CdTe were observed. Moreover the rich fine structure around the CdTe phonon frequency range has been resolved and the preliminary assignment of several lines has been performed. (c) 2005 WILEY-VCH Verlag GmbH I Co. KGaA, Weinheim
Effect of band inversion on the phonon spectra of Hg1-xZnxTe and Hg1-xCdxTe semiconductor alloys
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Etude de la topographie du champ magnétique et optique des trajectoires de sortie des particules dans un accélérateur FFAG du type Ohkawa
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Etude de l'optique des trajectoires de sortie des particules dans un accélérateur FFAG du type Ohkawa
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