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Materials based on gallium nitride are characterized by a wide bandgap. The excellent chemical, physical and electronic properties give them a place in various fields: electronics, optoelectronics, photovoltaics, military, biological and medical. The use of biosensors based III-N has been confirmed for the detection of biological substances in cells, blood or in solutions. This effect of detection results in various chemical and electric changes in a medium that is contacted with the devices without gate metallization of a high electron mobility transistor (HEMT). HEMT sensors can thus be used to detect gases, ions, pH values, proteins and DNA. In this work, we are interested in HEMT-based heterostructure AlGaN/GaN used in the construction of biosensors. The principle of operation of the HEMT is based on the properties of a high-mobility two-dimensional gas (2DEG) and high-speed saturation channel of a 2DEG AlGaN HEMT is very close to the surface that is very sensitive to absorption of analytes. We use this microsystem for detection of substances found in biological solutions. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this work, we are interesting in the measurement of thermal conductivity (on the surface and in-depth) of Porous silicon by the micro-Raman spectroscopy. This direct method (micro-Raman spectroscopy) enabled us to develop a systematic means of investigation of the morphology and the thermal conductivity of Porous silicon oxidized or no. The thermal conductivity is studied according to the parameters of anodization and fraction of silicon oxidized. Thermal transport in the porous silicon layers is limited by its porous nature and the blocking of transport in the silicon skeleton what supports its use in the thermal sensors.

We investigate the application of porous silicon (PS) in the field of the photovoltaic. In first step we realise a double porous silicon layer by electrochemical anodisation using two different current densities. The low current leads to a low porosity and during annealing, the recrystallisation of this layer allows epitaxial growth. The second current leads to a high porosity which permits the transfer onto a low cost substrate. During high temperature onto hydrogenation treatments of to passivate the structure and epitaxy in liquid phase, porous silicon is recristallized partially. In this work, a characterization by scanning electron microscopy informs us about the morphology of these porous layers.

Knowledge of the chemical composition of plasma is required for calculations and modeling in thermal plasmas. Indeed, from the knowledge of this composition can be calculated thermodynamic properties, transport coefficients and the radiative properties of a plasma environment. In this work, we propose to study the influence of thermodynamic equilibrium concentration of oxygen in a gas mixture N2/O2. Particularly we study the evolution of the species density in the plasma created according to the temperature and pressure variables for O2 mixtures. A thermodynamic equilibrium, when you want to take into account a large number of species, two main methods are usually employed, one is based on the law of mass action and the other on minimization of the Gibbs. We decided in our study to the law of mass action and the method of Newton-Raphson. The results show that when the plasma is in thermodynamic equilibrium densities of the different species present in plasma that are functions of temperature and pressure. They are not independent because they are bound by certain laws of thermodynamic equilibrium

We propose to install a balance at the surface of Mars. In this paper we present a survey on tasks which could be accomplished by means of a balance. The determination of the specific surface area and porosity of Martian soil and other sorption experiments are discussed. Criteria for the choice of a suitable balance type are given.

The thin-film SiGe is considered as promising candidate to meet the outstanding need for photovoltaic applications with enhanced adsorption characteristics and improved conversion efficiency [1-6]. In this paper, we simulated a solar cell type SiGe using AMPS1D (Analysis of Microelectronic and photonic structure) developed at Pennsylvania State University, to analyze emitter layer (thickness, doping) and we studied their influence on the photovoltaic solar cell. The simulation result shows that the maximum efficiency of 16.181 % has been achieved, with short circuit current density of 32.657 mA/cm2, open circuit voltage of 0.61 V and fill factor of 0.809. The obtained results show that the proposed design can be considered as a potential candidate for high performance photovoltaic applications.

Le silicium meso-poreux, obtenu par attaque électrochimique du silicium monocristallin, présente une conductivité thermique proche de celle de l'oxyde de silicium. C'est donc un excellent candidat pour assurer l'isolation thermique des microcapteurs sur silicium tout en garantissant la stabilité mécanique de la micro-structure. Néanmoins, avant de mettre en oeuvre le capteur sur silicium poreux, la compréhension du transport thermique dans une telle nano-structure et l'étude expérimentale de sa conductivité thermique, en fonction de ses paramètres caractéristiques, sont nécessaires. Dans ce travail nous nous intéressons à l'anodisation du silicium pour dégager les principaux facteurs, agissant sur la morphologie en profondeur de la couche. Cette dernière est évaluée par l'analyse de la répartition en surface et en profondeur de la taille des cristallites composant le matériau, au moyen de la spectroscopie micro-Raman. La stabilisation par oxydation de la couche de silicium poreux nécessite un double traitement pour garantir une faible conductivité thermique tout en assurant une bonne tenue mécanique.