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Abstract: This work is a contribution towards the understanding of the properties of hydrogenated silicon nitride (SiN x :H) that lead to efficient surface and bulk passivation of the silicon substrate. Considering the deposition system used (low-frequency plasma-enhanced chemical vapour deposition (PECVD)), we report very low values of surface recombination velocity S eff. As-deposited Si-rich SiN x :H leads to the best results (n-type Si: S eff=4cm/s – p-type Si: S eff=14cm/s). After annealing, the surface passivation quality is drastically deteriorated for Si-rich SiN x :H whereas it is lightly improved for low refractive index SiN x :H (n∼2–2.1). The chemical analysis of the layers highlighted a high hydrogen concentration, regardless the SiN x :H stoichiometry. However, the involved H-bond types as well as the hydrogen desorption kinetics are strongly dependent on the SiN x :H composition. Furthermore, “N-rich” SiN x :H appears to be denser and thermally more stable than Si-rich SiN x :H. When subjected to a high-temperature treatment, such a layer is believed to induce the release of hydrogen in its atomic form, which consequently leads to an efficient passivation of surface and bulk defects of the Si substrate. The results are discussed and compared with the literature data reported for the different configurations of PECVD reactors. [Copyright &y& Elsevier]

Abstract: Hydrogenated silicon nitride SiN x :H films are largely used as antireflective coating as well as passivation layer for industrial crystalline and multicrystalline silicon solar cells. This work is focused on the optical and photoluminescence (PL) properties of SiN x :H deposited by either Plasma-Enhanced Chemical Vapour Deposition (PECVD) or UltraViolet photo-assisted CVD (UVCVD). Photoluminescence phenomena were investigated in SiN x :H having different stoechiometries. On the other hand, spectroscopic ellipsometry was carried out in order to obtain the optical properties of the films, from which the optical gap could be determined. The evolution of the photoluminescence with stoechiometry was correlated to the evolution of the optical properties, and especially the absorption within the SiN x :H layer. A good agreement was found considering the confinement of excitons in strongly absorbing silicon nanostructures (ns-Si) formed in the SiN x matrix, with different sizes according to the NH3 /SiH4 gas flow ratio and the deposition technique. The main PL peak showed an increase of the emission intensity along with a blueshift as silicon concentration decreases. These observations indicate a radiative recombination mechanism dominated by confined excitons within ns-Si rather than emission related to defects. Furthermore, these ns-Si are supposed to be responsible of the global higher absorption, and hence lower optical gap, of the near-stoechiometric SiN x :H films in comparison with the stoechiometric Si3N4 ones. These assumptions were confirmed thanks to transmission electron microscopy (TEM) images performed on one of the samples, showing crystalline silicon quantum dots (c-Si QDs) embedded in the SiN x matrix. [Copyright &y& Elsevier]

The authors have observed three cases of fractures at the thoraco-lumbar level which did not unite after ten to twelve months - Dynamic X-rays demonstrated persisting mobility of about 20 degrees. The fracture line of the vertebral bodies was situated in a frontal plane and fragments were separated by the antero-inferior edge of the above vertebral body. The authors conclude that such fractions ought to be treated by internal fixation when recent, internal fixation and grafting when ancient.

A relatively frequent diagnosis, made however with difficulty. It concerns young women presenting morning attacks of headaches, subcutaneous eyelids and hands edema preventing the easy removal of rings and feet edema causing a difficult fitting of shoes. The weight fluctuates quite rapidly: several kilos from one day to another, sometimes even during the same day. This is accompanied by an oliguria aggravated by stress and orthostatism. After eliminating all other causes of edema, one must also rule out a cause of hyperaldosteronemia secondary to long-term intake of Thiazidic diuretics or laxatives. The physiological defect disturbing water metabolism remains to be identified. The Landis test offers an essential contribution.

The authors have devised a new type of saw which makes it possible to cut bone spherically. This type of osteotomy is useful when correction is required in more than one plane and provides good bone contact between bone ends. The technique is described. It has been used at the upper end of the tibia or femur and in the calcaneus and forefoot.

A plate designed from the model used by R. Judet for fractures of femoral neck is presented. It is adapted to the fixation of high femoral osteotomy with internal translation, affected or not with valgus or varus. The screwing of the plate, when in place, realizes systematically a compression at the level of the osteotomy. The system is very stable and enables the begining of reeducation without delay.

Hallux varus hypercorrection is reduced and maintained by a medial osteoplastic ridge fixed by screws in the head of the first metacarpal bone. It can be indicated to associate an extensor Hallucis longus lengthening.