Polarization-dependent low-frequency off-resonant Raman scattering has been studied from various commercially available filter glass samples, which contain CdS x Se 1Ϫx nanoparticles embedded in a glass matrix. In order to distinguish the confined acoustic phonons from the glass background, the spectra have been compared with those obtained from the base material, which does not contain nanoparticles. Polarized and depolarized scattering from confined acoustic phonons was distinctly resolved near the laser line and overtones of the polarized modes were observed. A theoretical treatment, which establishes a relation between the particle size, the frequencies, and the widths of various phonons, taking into account the matrix influence on the vibrational spectrum and on its damping, is presented. The material-dependent generalized form of this model enables one to use it for any given combination of particle and matrix materials. A good agreement between the experimental and the theoretical results is found. The nanoparticle sizes obtained from Raman scattering agree well with those obtained from transmission electron microscope and anomalous small angle x-ray scattering experiments. ͓S0163-1829͑99͒07231-8͔

Electrochemical etching techniques were used to fabricate semiconductor sieves of gallium phosphide, i.e., two-dimensionally nanostructured membranes exhibiting an enhanced optical second harmonic generation (SHG) in comparison with the bulk material. The SHG rotational and fundamental polarization dependencies studied under sample excitation by a 1064-nm Nd-YAG laser beam indicate optical homogeneity and uniaxial symmetry of the membranes. The artificial anisotropy and the enhanced nonlinear optical response induced by nanotexturization make semiconductor sieves very promising for use in all-optical devices.

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(b), and J. MONECKE (a) The band structure of the chalcopyrite semiconductor CdSiP, is calculated using the empirical pseudopotential method applied successfully already in the case of ZnSiP,. The band structure is in good agreement with recent experimental data, especially with the inverse crystal field splitting found by Shileika e t al. The influence of the three contributions to the deviation of the chalcopyrite structure from a cubic one (antisymmetric cation potential, tetragonal compression and distortion of the anion sublattice) on the band structure and the optical transition energies is investigated in detail for both ZnSiP, and CdSiP,.Die Bandstruktur der halbleitenden Chalkopyritverbindung CdSiP, wird mittels der empirischen Pseudopotentialmethode berechnet, die bereits erfolgreich auf ZnSiP, angewendet wurde. Die erhaltene Bandstruktur steht in guter ifbereinstimmung mit experimentellen Ergebnissen, insbesondere mit der von Shileika und Mitarbeitern gefundenen inversen Kristallfeldaufspaltung. Der EinfluB der drei nichtkubischen Potentialanteile der Chalkopyritstruktur (antisymmetrisches Kationenpotential, tetragonale Stauchung und Verzerrung des Anionenuntergitters) auf die Bandstruktur und die optischen ubergange wird fur ZnSiP, und CdSiP? detailliert untersucht.

The band structures of the chalcopyrite semiconductors ZnGeP, and ZnSiAs, are calculated using the empirical pseudopotential method as applied successfully already to ZnSiP, and CdSiP,. The band structures are in good agreement with experimental data. The influences of all three tetragonal parts of the crystal potentials (antisymmetric cation potentials, tetragonal compressions, and distortions of the anion sublattices) on the band structures and on optical transition energies are investigated in detail.Die Bandstrukturen der halbleitenden Chalkopyritverbindungen ZnGeP, und ZnSiAs, werden mittels der empirischen Pseudopotentialmethode berechnet, die bereits erfolgreich auf ZnSiP, und CdSiP, angewendet wurde. Die gewonnenen Bandstrukturen stimmen mit experimentellen Ergebnissen gut iiberein. Die Einfliisse aller drei tetragonalen Anteile der Kristallpotentiale (antisymmetrische Kationenpotentiale, tetragonale Stauchungen und Verzerrungen der Anionengitter) auf die Bandstrukturen und auf optische Ubergangsenergien werden detailliert untersucht.

The force constants of a Keating model are calculated for CuInS, and AgInTe, from spectral moments by means of the traces of powers of the dynamical matrix. The spectral moments are derived from measurements of specific heat given in the literature. By diagonalizing the dynamical matrix composed with the calculated force constants the phonon frequencies in the centre of Brillouin zone are obtained. The comparison with published data from measurements on CoInS, shows reasonable agreement.Die Kraftkonstimten eiiies Keating-Modells werden fur CuInS, und AgInTe, aus den spektralen Momenten mit Hilfe der Spuren von Potenzen der dynamischen Matrix berechnet. Die spelitralen Noniente werden aus in der Literatur gegebenen Messungen der spezifischen Wirmeknpazitiit abgeleitet. Durrh Diagonalisierung der aus den berechneten Kraftkonstanten aufgestellten dynamischen Matrix werden die Phononenfrequenzen im Zentrum der Brillouinzone bestimmt. Der Vergleicli mit publizierten MeBwerten an CuInS, ergibt eine ziemlich gute ubereinstimmung.

The band structure of ZnSiP, is calculated using the empirical pseudopotential method. The form factors are deduced from those of ZnS, Si, AIP, and Gap. The band structure obtained is in good agreement with recent experimental data. The influence of the distortion of the anion sublattice on the energy levels at r is examined and the optical transitions in the region from 3 to 6 eV are discussed.Die Bandstruktur von ZnSiP, wird mit Hilfe des empirischen Pseudopotentials berechnet. Die Formfaktoren werden a m denen fur ZnS, Si, AIP und GaP gewonnen. Die erhaltene Bandstruktur ist in guter fjbereinstimmung mit experimentellen Ergebnissen. Es werden der EinfluD der Verzerrung des Anion-Untergitters auf die Energieniveaus am I?-Punkt untersucht und die moglichen optischen Vbergilnge im Bereich von 3 bis 5 eV diskutiert .

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