"Etude des propriétés structurales de matériaux semiconducteurs finement cristallisés incorporés dans des matrices hôtes"

Abstract

"In this work we have developed by the Czochralski methode, single crystals of KBr and KCl pure and doped respectively, by semiconductors CdS and CdSe. The structural properties of the prepared materials were identified by the X-ray diffraction and by Raman and infrared spectroscopy. The effect of confinement of semiconductor crystallites on the lattice parameters of the host matrices of KBr and KCl and on those of CdS and CdSe was studied. The X-ray diffraction on powder and pellets of composites KBr / CdS and KCl / CdSe has allowed to show the incorporation of the semi-conductors CdS and CdSe into matrices KBr and KCl, to know the evolution of the cell parameters of different phases as well as the sizes of the crystallites of the semiconductors contained in the hosts matrices. The crystallite sizes were calculated, using the Scherrer method and the Williamson-Hall method, by measuring, in both methods, the width at half peaks height of X-ray diffraction. The study of μ-Raman and FI-IR spectra, has confirmed the incorporation of cristallites of CdS and CdSe, respectively, in the matrices of KBr and KCl. In the structural characterization by powder diffraction, we have adopted a new software (I.C.G) to index the powder patterns and to find the lattice parameters from experimental data. This new indexing software, is based on an approach which use classical geometry. The effectiveness of the software has been verified by treating several compounds. This study has allowed to highlight the peculiarities of the structural state of composites studied, which have some consequences on the physical properties of composites prepared having regard to the correlation structure-properties of materials."