Context. Within the framework of the second-generation instrumentation of the Very Large Telescope Interferometer of the European Southern Observatory we have developed the four-telescope beam combiner in integrated optics. Aims. We optimized the performance of such beam combiners, for the first time in the near-infrared K band, for the GRAVITY instrument dedicated to the study of the close environment of the galactic centre black hole by precision narrow-angle astrometry and interferometric imaging. Methods. We optimized the design of the integrated optics chip and the manufacturing technology as well, to fulfil the very demanding throughput specification. We also designed an integrated optics assembly able to operate at 200 K in the GRAVITY cryostat to reduce thermal emission. Results. We manufactured about 50 beam combiners by silica-on-silicon etching technology. We glued the best combiners to single-mode fluoride fibre arrays that inject the VLTI light into the integrated optics beam combiners. The final integrated optics assemblies have been fully characterized in the laboratory and through on-site calibrations: their global throughput over the K band is higher than 55% and the instrumental contrast reaches more than 95% in polarized light, which is well within the GRAVITY specifications. Conclusions. While integrated optics technology is known to be mature enough to provide efficient and reliable beam combiners for astronomical interferometry in the H band, we managed to successfully extend it to the longest wavelengths of the K band and to manufacture the most complex integrated optics beam combiner in this specific spectral band.

In this work, we report on the PAS characterization of sintered HfO2 bulk ceramic and HfO2 layers deposited with various methods on a silicon substrate with a layer thickness ranging from 25 to 100 nm. PAS measurements are sensitive to the deposition process type and the post-deposition annealing. Chemical and structural characterisations have been performed on the same samples. The PAS results are discussed regarding to the material defects of the different layers. In addition, a built-in electrical field induced by charged defects located at the HfO2/Si interface as well as in the HfO2 layer must be taken into account in the PAS data fitting. Both non-contact internal electrical field measurements and internal electrical field simulations support the PAS finding.

A full automated NIR polariscope has been specially built for residual stress measurement in crystal silicon wafers for solar applications. The multiple configurations of the instrument allow measuring both the isoclinic and the isochromatic parameters on a full field. A new algorithm has also been developed to extract the maximal shear stress inside the silicon wafers without linking the isoclinic parameter to the isochromatic parameter. Hence, it is straightforward to use and the extraction errors are reduced. Coupling this improved data analysis with the comprehensive capabilities of the test rig, allowed to show that the effect of the cutting process on the residual stress inside the silicon wafers is predominant compared with the effect of the cast process, related to the thermal gradient and impurities.

We present a new set of brittle microtectonic measurements carried out in the Pliocene and Quaternary rocks outcropping in several key sectors of the western Betic and Rif orogen, the so-called Gibraltar orogenic arc. This data set, along with available earthquake focal mechanisms and borehole breakouts, allowed us to compile the Pliocene and Quaternary stress map of this area. This map provides new constraints for tectonic models and the present-day tectonic activity of the proposed active eastward subduction of oceanic lithosphere beneath the Gibraltar Arc and roll-back. The horizontal maximum compressive stress (S-Hmax) is NW-SE in the Betic Orogen and N-S/NNW-SSE in the southern Rif Cordillera. There is a significant consistency between S-Hmax and the displacement field deduced from GPS measurements with respect to the African plate: both appear to reflect the NW-SE convergence between the African and the European plates that is perturbed in the Rif. We propose that part of the eastern Rif behaves as a quasi-rigid block welded to the stable African plate. This block is bounded by important faults that localized most of the deformation disturbing the stress and surface displacement field. Pliocene to Quaternary N-S to NW-SE Africa-Europe plate convergence seem to be associated to the reorganization of the remnant Early Miocene subduction system in a continental-continental collision framework. Three-dimensional reconstruction of available seismic tomography plotted against the intermediate seismicity shows that only part of the old subduction system, whose orientation ranges from N20 degrees E to N100 degrees E, remains active: the portion ranging from N30 degrees E to N40 degrees E, orthogonal to the regional convergence. (C) 2011 Elsevier Ltd. All rights reserved.

Seismic hazard is associated with recent and present fault activity in mountain ranges. In the Betic-Rif alpine mountain chain, tectonic activity started in the Cretaceous, and topographic uplift continues since Tortonian times as a consequence of the NW-SE oblique convergence between Africa and Eurasia. The deformation is active and produces seismicity that sometimes has catastrophic consequences. The Al Hoceima earthquake (February 24, 2004), considered one of the largest earthquakes ever recorded instrumentally in the westernmost Mediterranean (M=6.3), caused great damage in the region. Seismological studies agree that the main shock was situated on land, at the limit between the External and Internal Zones of the Rif, at a depth of 10-14 km. The focal mechanism points to a strike-slip solution with a NW-SE oriented P axis. quite similar to those of the significant 1994 earthquake swarm located to the north. The epicenter aftershocks distribution would signal the presence of a N-S oriented sinistral fault, activated by the NW-SE regional compression associated to plate boundary convergence. In this setting, the seismogenic fault ruptures related to these seismic events are expected to have reached the Earth's surface. However, detailed field work carried out 1 month after the earthquake does not evidence any N-S strike-slip coseismic fault in the epicentral area. The main observed effects were landslides, damages to constructions, and locally open cracks indicating an unexpected NW-SE extension. Scarce N-S faults are normal, the main ones being located several kilometers away from the epicentral area. To explain this apparent contradiction between geological and seismological observations, we propose a decoupled tectonic model with crustal detachments that separate a deep brittle crust from an upper crust undergoing uplift, and the development of large folds and normal faults. This geological setting, common to internal zones of cordilleras, may need to be taken into account in future paleoseismicity studies and in the assessment of seismic hazard. (C) 2008 Elsevier B.V. All rights reserved.

La determinacion de la actividad tectonica reciente y actual en la Cordillera del Rif tiene gran interes, ya que esta asociada a la actividad de las fallas que determinan la peligrosidad sismica de la region. El objetivo de este trabajo es describir las caracteristicas de la actividad tectonica sismogenetica en la region de Alhucemas situada en el interior de la Cordillera del Rif, para discutir algunos factores geologicos que no suelen tenerse en cuenta habitualmente en los estudios de peligrosidad sismica, desarrollados con tecnicas aplicables a zonas frontales de cordilleras

The Rif Cordillera is a part of the Alpine orogenic arc in the Western Mediterranean, which was developed by the interaction of the westward motion of the Alboran Domain between the converging Eurasian and African plates. The Prerif Ridges, located along the southwestern front of the Rif, are south-vergent folds that are in places associated with faults affecting Jurassic to Quaternary sedimentary rocks and slope breccias that evidence the deformations that were active over the Neogene-Quaternary period. The different southward or southwestward displacement of each Prerif Ridge is related to the development of frontal and lateral ramps, which may or may not reach the surface. Oblique shortening may be explained by southwestward escape of large tectonic wedges, bounded by large strike-slip faults: the North-Middle Atlas fault which extends northward into the Alboran Sea, the Fez-Tissa-Taineste fault, the Bou Draa-Sidi Fili fault, the Jebha fault and the Fatties fault. The relative displacement of these tectonic wedges toward the SW may explain the NNE-SSW to ENE-WSW compression observed in the Rif front and in the northern part of its Meseta-Atlas foreland.

10 paginas, 5 figuras, 1 tabla.-- Trabajo presentado en: The Atlantic Neogene in the XXIth Century: State of The Art.

4 paginas.-- Trabajo presentado en el VI Congreso Geologico de Espana, Zaragoza, 12-15 julio, 2004.

Prerif Ridges are located at the frontal part of the Rif Cordillera, which develops at the Eurasian-African plate boundary. The ridges are formed by recent tectonic structures that also deform foreland basins (Saïss and Gharb basins) and the foreland (Moroccan Meseta). The position of the ridges is the consequence of inversion tectonics undergone in the area. The ENE-WSW trend of the northern edge of the Neogene Saïss basin is determined by the location of Mesozoic basins. Although Prerif ridges probably started to develop since the Early Miocene, the most active deformation phase affecting Pliocene rocks consisted of N-S to NW-SE oriented compression. Striated pebbles show that this compression has prolate stress ellipsoids. The deformation produces southwards vergent folds and NNW-SSE striae on reverse faults at the base of the ridges. The flexure of the Paleozoic basement by the emplacement of the Ridges produced extensional deformation and the development of the Saïss foreland basin. The extension in this basin is oblate and features a well determined NNE-SSW trend near the Ridges, whereas it becomes prolate and pluridirectional near the foreland edge represented by the Rabat region. This part of the Moroccan Meseta, commonly considered to be stable, is deformed by sets of orthogonal joints and faults with short slip that affect up to Quaternary sediments. Southwestward, the Meseta rocks are also deformed by transcurrent faults, which indicate NW-SE and N-S trends of compression. The NW-SE approximation of Eurasia and Africa determines a regional stress field with the same trend of compression. Regional stresses are notably disturbed by the development of the active structures in the Rif, which exhibit alternating trends of compression and extension. The clearest evidence of the relationship between the local deformation and the general plate motion is found at the deformation front of the Cordillera, that is, the Prerif Ridges.

Attenuated total reflection (ATR) spectroscopy and spectroscopic ellipsometry (SE) have been used to characterize oxides used for the scanning capacitance microscopy (SCM) technique. SCM has been used to study boron and phosphorous doped Si test structures epitaxially grown on (100) Si substrates. SCM samples have one-dimensional (1D) doping profiles with sub-micron features, with staircase-like steps in the unipolar sample and a smoother profile in the bipolar sample, as obtained by secondary ion mass spectrometry (SIMS) profiling. Cross-sectional SCM results obtained on samples oxidized by the standard low-temperature UV-ozone method are presented, discussed and compared to results obtained on cleaved samples oxidized by a simple exposure to air. The results show that the native oxide covering a (110) cleaved section may yield SCM images of sufficient quality, with no contrast reversal on a wide range of doping levels, as well as observed on sections prepared with the UV-ozone technique. However, the long-term stability of the SCM signal on native oxides is poor, and UV-ozone oxidation can be used to recover a valid SCM signal. Realistic ultrathin oxide thickness data obtained by SE on (110) substrates are presented together with ATR results, which confirm the superior quality of UV-ozone oxides with respect to other kinds of oxides.

The narrowest feature on current integrated circuits is the gate oxide—the thin dielectric layer that forms the basis of field effect device structures. Silicon dioxide is the dielectric of choice and, if the present miniaturization trend continues, the projected oxide thickness will be <1 nm in 2005. Therefore, ultrathin silicon oxide layers using various preparation conditions have been studied by angle‐resolved x‐ray photoemission spectroscopy (ARXPS) and Fourier transform infrared attenuated total reflection (FTIR‐ATR).

Interests in infrared spectroscopy (IRS) have been stimulated by the increasing need for non-destructive surface characterization providing structural and chemical informations about the new materials used in microelectronic devices. Standard infrared spectroscopy of thin layers is limited because of its lack of sensitivity. The use of optical configurations such as the attenuated total reflection (ATR) allows to characterize nanometric layers. This paper will present the results of a study conducted for a better understanding of the capabilities and limitations of this technique. A theoretical analysis based on a perturbation method is used to elucidate the results of ATR measurements performed on silicon oxide layers of different thickness on silicon substrates. This analysis shows that the absorbance ATR spectrum in p polarization is the image of the layer energy loss function, under specific conditions. The exact ATR spectrum simulation using a matrix formalism showed that the straightforward interpretation in terms of the layer dielectric function is limited to a very narrow layer thickness range. The fitting process of the ATR spectrum is evaluated for the interpretation of experimental spectra obtained for the growth of chemical silicon oxide layers.

Ultraslow single- and multicharged ions (USMCI) have small kinetic energy compared with their potential energies. They can be used for surface preparation at room temperature, to engineer the top atomic layers of surfaces without modifying the substrate below, in processes such as ultrathin film growths, etching, deposition, or nanostructures fabrication. The energy for the reaction is brought to the surface through the USMCI potential energy, which can be controlled by varying the ion charge. The USMCI kinetic energy is so small that they do not penetrate below the surface. We have used various USMCI under low pressures of O2 (between 10−9 and 5×10−6 Torr) to grow ultrathin films of SiO2 on Si wafers, from 0.3 to 2.3 nm with a resolution of 0.1 nm and a uniformity of ±0.1 nm. To evaluate the layers and optimise this process, we have analysed the surfaces by Fourier transform infrared spectroscopy, Auger electron spectroscopy, spectroscopic ellipsometry, transmission electron microscopy, X-ray photoelectron spectroscopy and surface charge analysis.

For a better understanding of the physical and electronic properties of emissive carbon films, one of the best ways is to compare the results obtained with several surface and structural analysis techniques. In this article, different types of carbon film depositions for developing large flat panel displays by field emission displays are analysed and the results are correlated with their emissivity. Pulse laser ablation films, high-temperature plasma-enhanced chemical vapour deposition (PECVD) films and low-temperature PECVD films are characterized by XPS, Raman spectroscopy, X-ray diffraction (XRD), specular X-ray reflectivity, transmission electron microscopy (TEM) and elastic recoil detection analysis (ERDA). The analyses lead us to conclude that the sp(2)/sp(3) ratio is not a crucial parameter for carbon film emissivity. Crystalline structure seems more important. The presence of graphite grains is essential for good and uniform emission. Combination of XPS, TEM, XRD, Raman spectroscopy and ERDA is necessary for the study of carbon film emission. Copyright (C) 2001 John Wiley & Sons, Ltd.

A multiple internal reflection (MIR) infrared monitoring system based on the two prism coupling geometry has been developed for the measurement of silicon wafer surfaces and interfaces. The new set-up we describe here increases the sensitivity of IR spectrometry by at least two orders of magnitude. It is shown that the MIR technique allows chemical analysis of ultra thin layers, surface contaminations and embedded interfaces in a non-destructive way.

The Rabat region, located in the northern border of the Moroccan Meseta, is generally considered as a present-day stable region. However, the fluvial and marine sedimentary rocks, with Pliocene and Quaternary ages, are deformed by joints, generally tensional, and by normal and strike-slip faults. The brittle structures indicate N-S compressional deformations, probably related to the present-day regional stresses in the crust, and extensional deformations related to the proximity to the Gharb basin

We discuss the usefulness of the two-prism coupling geometry to perform non-destructive multiple internal reflection (MIR) measurements on 200 mm silicon wafers. Application to the determination of the Si-H and N-H bond concentrations in LPCVD SiN ultra-thin films, is presented. It is shown that an appropriate annealing reduces significantly the Si-H content.