ALBERT

Notes: In this work, the solid-phase crystallization kinetics of amorphous SiGe films deposited by low-pressure chemical-vapor deposition on oxidized Si wafers has been studied by x-ray diffraction, Raman spectroscopy, and ultraviolet reflectance. The microstructure of the fully crystallized films has also been analyzed using these techniques in combination with transmission electron microscopy. The Ge fraction of the films (x) was in the 0–0.38 interval. The samples were crystallized at temperatures ranging from 525 to 600 °C. The crystallization monitored by all techniques was found to follow the Avrami model. Different crystallization behaviors are distinguished depending on the Ge content of the films and the crystallization temperature. The results are discussed in terms of the identification of the nucleation site location and the dimensionality of the grain growth, taking into account the probe depth of the different techniques and the values of the Avrami exponent derived from the crystallization curves. The preferred orientations of the grains, the grain morphology, the lateral grain size, the presence of inter- and intragrain defects, the surface roughness, and the overall crystallinity of the fully crystallized films have also been studied and related to the observations concerning the crystallization process. © 2001 American Institute of Physics.

Notes: As-deposited iridium-silicon interface structures have been characterized by cross-section high-resolution transmission electron microscopy. Iridium films were deposited by an e-beam gun on (100) Si wafers heated at 200 °C during the deposition. A planar polycrystalline interfacial layer, 2–3 nm thick, was formed between the iridium and the silicon substrate. Thermodynamic calculations are presented which describe the development of the interfacial layer. Correlation between the observed structure and that proposed by thermodynamic calculations is discussed. © 1995 American Institute of Physics.

Notes: RESUME.Après résorption des structures buccales du protomonte, la stomatogenèse ne commence que sur les produits de l'avant-dernière division du tomonte. Elle se poursuit et se complète sur les tomites individualisés de la dernière division. Au niveau des extrémités antérieures des cinéties somatiques intercalaires et des extrémités rompues de cinéties bipolaires, une lère vague de proliferation des cinétosomes produit de courtes lignes, obliques, de cinétosomes isolés. Elles se transforment en lignes d'une double rangèe de cinétosomes, à la suite d'une 2ème vague de multiplication de cinétosomes. Un alignement de ces segments, procédant de gauche à droite et d'avant en arrière, constitue successivement les 3 membranelles longitudinales en doublets (M1 puis M2 et M3) ainsi que la membrane parorale, également en doublet. Une 3ème vague de proliferation cinétosomienne juxtapose une rangée de cinétosomes à droite des doublets (sauf à l'extrémité postérieure de M1 et au niveau de la parorale) transformant les promembranelles en triplets. Cette proliferation cinétosomienne se prolonge par addition d'une 4ème rangée de cinétosomes au trajet médian et postérieur de M2 et peut-ětre à M3 et par juxtapositions successives de nouvelles rangées supplémentaires à l'extrémité postérieure de M2 (flamme). Les cinétosomes des rangées droites de promembranelles portent de larges rideaux de nombreuses fibres postciliaires. Les cinétosomes des autres rangées de M2, au moins, ont également des fibres postciliaires. Entre les cils de promembranelles il n'y a pas de couche alvéolaire, ni d'épiplasme. Une résorption des cinétosomes commence à se manifester par disparition des cinétosomes de la rangée gauche de la parorale dont subsistent les cinétosomes droits porteurs de fibres postciliaires. A vec le raccourcissement de l'aire buccale la résorption s'étend aux cinétosomes postérieurs des 2 rangées droites de M1, et des extrémités antérieures des 2 (ou 3?) rangées droites dc M3. Une invagination de la dépression buccale entraǐne vers la gauche les organelles buccaux et enfonce les cinéties vestibulaires en remontant en avant et à gauche leurs extrémités postérieures tronquées. Il y a régression postéro-antérieure totale des cinétosomes de la parorale. M1 reste constituée au départ de 3 rangées ciliaires; M2 est également formée de 3 rangées ciliaires doublées postérieurement de nombreuses rangées constituant la flamme; M3 n'est finalement constituée que d'une seule rangée ciliaire. Une ultime proliferation cinétosomienne aux extrémités antérieures de cinéties vestibulaires serait peut-ětre à l'origine d'un champ allongé de nouveaux cinétosomes vestibulaires.〈section xml:id="abs1-1"〉〈title type="main"〉ABSTRACTAfter resorption of the buccal structures of the protomont, stomatogenesis begins only in the products of the penultimate division of the tomont. It continues to completion in the individualized tomites of the last division. At the anterior ends of the intercalary somatic kineties and the broken ends of bipolar kineties, a first wave of kinetosome proliferation produces short streak lines of isolated kinetosomes. These develop into lines formed of double rows of kinetosomes following a second wave of kinetosome multiplication. An alignment of these segments, proceeding from left to right and from front to rear, constitutes successively the three longitudinal membranelles in doublets (M1 then M2 and M3), and the paroral membrane, also a doublet. A third wave of kinetosome proliferation juxtaposes a row of kinetosomes to the right of the doublets (except at the posterior end of M1 and at the level of the paroral membrane) to give triplets. This proliferation is extended by addition of a fourth row of kinetosomes on the median and posterior path of M2 and perhaps M3, and by successive juxtaposition of further rows at the posterior end of M2 (flare). The kinetosomes of the right hand rows of promembranelles bear wide ribbons of numerous postciliary fibers. There is no alveolar layer nor epiplasm between the cilia of the promembranelles. Resorption of kinetosomes begins by disappearance of the kinetosomes of the left hand row of the paroral membrane; the right hand kinetosomes carrying postciliary fibers remain. With shortening of the buccal zone, resorption extends to the kinetosomes of the two posterior rows of M1 and the anterior ends of the two (or three?) left hand rows of M3. An invagination of the buccal cavity draws the buccal organelles to the left and pushes in the vestibular kineties while raising forward and to the left their truncated posterior ends. Total postero-anterior regression of the kinetosomes of the paroral membrane occurs. Membranelle 1 remains composed of three rows of cilia; M2 is also composed of three rows of cilia edged posteriorly by numerous rows constituting the flare; M3 is composed of a single row of cilia. A final kinetosome proliferation at the anterior ends of the vestibular kineties might be responsible for the extended field of new vestibular kinetosomes.

Notes: The electrical properties of the photochemical vapor-deposited silicon nitride/silicon interface are presented as a function of deposition temperature (70 to 200 °C). High values of interface state density Nss (about 3×1012 cm−2 eV−1), an equivalent charge at the interface Qss (about 5×1011 cm−2), and an important injection-type hysteresis of the capacitance voltage C-V curves are observed in the as-grown material. Most defects are found to be generated during the deposition process by the ultraviolet illumination used to activate the chemical reaction of the gases. Low-temperature (250 °C) and short-time (30 min) annealings eliminate part of the defects, resulting in lower values of Nss (about 1×1012 cm−2 eV−1), Qss (about 5×1010 cm−2), and reduced injection-type hysteresis.

Notes: The temperature dependence of the differential resistance by area product at zero bias (R0 A) of boron-implanted n-on-p infrared photodiodes made in x≈0.20 Hg1−xCdxTe has been measured and characterized as a function of the implanted dose assuming a simple model of the junction. The R0 A product and its functional dependence in the different temperature ranges are found to be dependent on the implanted dose in n+p as-implanted abrupt junctions. The best performance diodes are found at the lowest implanted dose. The results indicate that there is an upper limit of the R0 A, in the range where the current is controlled by a minority-carrier diffusion mechanism, that is determined in n+p junctions by the p-side contribution. However, the indicated behavior of R0 A and its functional dependence at low temperatures supports the hypothesis defended by some workers in the literature indicating that the n-side contribution to the current-voltage characteristics may be important under some conditions, such as is the case when the current is controlled by conduction mechanisms through traps in the depletion region which are related to the heavily damaged n+ layer caused by the implantation process in this material.

Notes: A new, fast, and very sensitive semiconductor bolometer has been designed and developed for the measurement of radiative energy losses in fusion devices in which the hard radiation level is not too high. Special care was taken in the design of the bolometer to simplify both the construction technology and the installation in fusion devices. The major novelty of this bolometer is the use of a low thermal conductivity rigid substrate, instead of the typical thin foil stretched on a rigid frame. In spite of large detector-substrate contact area, the cooling time constant reaches values as high as 150 ms. The rigid substrate allows the detector to be very robust and reliable; moreover, the monolithic integration of array structures is straightforward. The detector has been fabricated with a thin-film multilayer technology achieving very low thermal capacitance (〈2 mJ/K) and very low response time (〈5 μs). High responsivity (20 V/W) is obtained using GeOx thin film with a high thermal coefficient of the electrical resistance (−4.5%/K) as sensing thermistor.

Notes: A main drawback of bolometers is their low responsivity resulting in very poor time and/or spatial resolutions. Improvement of detectors responsivity would serve to solve this problem and bolometers could be useful in studies of fast-developing phenomena in plasmas. We are searching for the development of new detectors based on a standard multilayer design and having as sensitive material amorphous germanium. The chosen detector structure is rigid substrate (low conductivity glass)/interdigitated electrodes (Ti-Au defined by photo- lithographic techniques)/resistor layer (amorphous oxygen-doped germanium evaporated by electron beam)/insulation layer (photo-CVD deposited Si3N4)/absorber foil (evaporated + electrolytic gold layers). The detector performance has been compared with pyroelectric detectors and germanium bolometers in the TJ-I tokamak under the same experimental conditions. Also, the design and construction of monolithic miniaturized detector arrays, based on this concept, are in progress.