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Titanium-boron-nitrogen (Ti-B-N) thin films were deposited by RF reactive magnetron sputtering using a titanium diboride (TiB2) target in an argon + nitrogen mixture. The argon mass flow rate was kept constant, whereas that of nitrogen was pulsed during the deposition. A constant pulsing period of P = 10 s was used, and the introduction time of the nitrogen gas (duty cycle (dc)) was systematically varied from dc = 0 to 100% of the pulsing period. This reactive gas pulsing process allowed the deposition of Ti-B-N thin films with various boron and nitrogen concentrations. Such adjustable concentrations in the films also led to changes in their electronic transport properties. Boron and nitrogen contents exhibited a reverse evolution as a function of the nitrogen duty cycle, which was correlated with the transition from a metallic to semiconducting-like behavior. A percolation model was applied to the electrical conductivity as a function of the nitrogen pulsing parameters, assuming some correlations with the evolution of the Ti-B-N thin film nanostructure.

A three-dimensional model enables the development of accurate solutions to have more information about the thickness, texture, and characteristics of small-size samples for education and metrology applications. This project proposes an idea to obtain a complete 3D surface reconstruction using the application of Pollen 3D for the scanning electron microscope (SEM) images with high magnification. The main objective is to have a set of images of the complete 360° rotation of the sample with a robot inside the chamber of the SEM. Simulation SEM images with Blender (open source application) are proposed for results validation.

Depositions of the dielectric thin-films at low temperatures without greenhouse gas, nitrous oxide (N $$_{2}$$ O) is one of the most critical challenges in modern technologies for microelectronics, optoelectronics, and nanoelectronics. The present study demonstrates that thin dielectric layers deposit by inductively-coupled plasma-enhanced chemical vapor deposition (ICPECVD) technology at lower temperatures ( $$< 300\,^{\circ }$$ C) can be successfully optimized and has the potential to reduce the environmental impact significantly. A particular focus is made on the improvement of the optical properties that are strongly correlated to the physicochemical bonds film properties. Typical deposition rates range from 10 to 20 nm/min, depending mainly on power, pressure, and gas flows. This study opens up large scale applications that require lower hydrogen content and a stable process. The presented results emphasize green manufacturing technologies and can be valuable for a wide range of applications using a complementary metal-oxide-semiconductor (CMOS)-compatible technology.

4D structures are tridimensional structures with time-varying abilities that provide high versatility, sophisticated designs, and a broad spectrum of actuation and sensing possibilities. The downsizing of these structures below 100 μm opens up exceptional opportunities for many disciplines, including photonics, acoustics, medicine, and nanorobotics. However, it requires a paradigm shift in manufacturing methods, especially for dynamic structures. A novel fabrication method based on ion-induced folding of planar multilayer structures embedding their actuation is proposed-the planar structures are fabricated in bulk through batch microfabrication techniques. Programmable and accurate bidirectional foldings (-70° - +90°) of Silica/Chromium/Aluminium (SiO2 /Cr/Al) multilayer structures are modeled, experimentally demonstrated then applied to embedded electrothermal actuation of controllable and dynamic 4D nanorobotic structures. The method is used to produce high-performances case-study grippers for nanorobotic applications in confined environments. Once folded, a gripping task at the nano-scale is demonstrated. The proposed fabrication method is suitable for creating small-scale 4D systems for nanorobotics, medical devices, and tunable metamaterials, where rapid folding and enhanced dynamic control are required.

International audience

A regenerator of a Stirling machine alternately absorbs and releases heat from and to the working fluid which allows to recycle rejected heat during theoretical isochoric processes. This work focuses on a milli-regenerator fabricated with a multiple jet molding process. The regenerator is a porous medium filled with a dense pillar matrix. The pillars have a geometrical lens shape. Two metallic layers (chromium and copper) are deposited on the polymer pillars to increase heat transfer inside the regenerator. We performed experiments on different milli-regenerators corresponding to three porosities (ε = 0.80, 0.85 and 0.90) under nitrogen steady and oscillating compressible flows (oscillating Reynolds number in the range 0 < Reω < 60 and Reynolds number based on the hydraulic diameter ReDh,maxT < 100°C). Temperature, velocity and pressure experimental measurements are performed with microthermocouples (type K with 7,6 µm diameter), hotwires and miniature pressure sensors, respectively. We identified a threeterm composite correlation equation for the friction factor based on a Darcy-Forchheimer flow model that best-fit the experimental data. In steady and oscillating flows permeabilities and inertial coefficients are of the same magnitude order. Inertial coefficients decrease when the porosities increase.

Origami structures have a wide range of applications in robotics and have been intensively investigated by researchers in recent years.However, enabling sub-millimeter structures is an open question especially because of the lack of small enough joints. In this paper, compliant joints made of Silica by Focused Ion Beam (FIB) folding are proposed to achieve continuous, highly repeatable large motions. A polyarticulated structure including 3 joints is especially studied following a series of robotic analyses and experimentations to quantify the performances. The size of the structure firstly appears disruptive because smaller than 50 ${\mu }{\rm m}$ in typical overall length, i.e. less than the radius of an optical fiber. Secondly, the structure can achieve a planar workspace of 57 ${\mu }{\rm m}$ squared, which is significantly large compared to the structure dimension. Thirdly, repetitive movements performed at randomly selected positions, demonstrate an excellent repeatability standard deviations of 227 nm and 216 nm in x and y directions, respectively. These results together state the interest of novel polyarticulated structures resulting from the FIB folding as a basis for the next tethered nanorobotics generation.

International audience; In this paper, we study the influence of annealing on the performance of Resistive Temperature Detectors made from Nickel thin films. The aimed application is heat flux sensing. The substrate is made of Borofloat glass with a Chromium adhesive layer. Several annealing temperatures between 150°C and 300°C are applied to this assembly. The thin films as deposited and after annealing are analyzed through SEM images. The evolution of the resistance and the temperature coefficient of the sensor are discussed. An annealing temperature is selected that ensures the repeatability of measurements.

International audience; Résumé - Cette étude se situe dans le cadre du développement de fluxmètres thermiques en microtechnologie. Ces fluxmètres consistent en deux résistances de platine déposées sur un substrat en verre. Dans une première partie, nous présentons le principe du fluxmètre et de la mesure de température. Dans une deuxième partie, nous présentons également les étapes de fabrication en salle blanche et les différentes températures de recuits étudiées. Nous présentons des résultats expérimentaux sur la variation de résistance observée selon les différentes températures de recuit et une analyse par Diffraction de Rayons X complétée par des images au microscope à balayage. Nous proposons comme hypothèse que la baisse de résistivité observée pour les faibles températures de recuit est due à l’amélioration du réseau cristallin et que la hausse observée pour les températures les plus élevées est due à la diffusion de la couche d’accroche en chrome dans le platine.

Tungsten oxide WO3 thin films are deposited by DC reactive magnetron sputtering. The Reactive Gas Pulsing Process (RGPP) associated with the GLancing Angle Deposition method (GLAD) are implemented to produce zigzag columnar structures. The oxygen injection time (tON time) and the pulsing period are kept constant. Three tilt angles α are used: 75, 80, and 85° and the number of zigzags N is progressively changed from N = 0.5, 1, 2, 4, 8 to 16. For each film, refractive index, extinction coefficient, and absorption coefficient are calculated from optical transmission spectra of the films measured in the visible region from wavelength values only. Absorption and extinction coefficients monotonously drop as the number of zigzags increases. Refractive indices are the lowest for the most grazing tilt angle α = 85°. The highest refractive index is nevertheless obtained for a number of zigzags close to four. This optimized optical property is directly correlated to changes of the microstructure, especially a porous architecture, which is favored for high tilt angles, and tunable as a function of the number of zigzags.

International audience; In this paper, we present an experimental study on the pressure, pressure drop, velocity and friction factor in a regenerator made from an array of pillars in reciprocating flow conditions. The fluid used in the experiment is air. We show that the pressure drop depends on the porosity, frequency and stroke. We observe a phase shift between the crank angle sinusoidal variation of the piston and the pressure variation that increases with frequency. We also observe that the instantaneous friction factor is higher in the discharge phase than in the suction phase, and higher in the acceleration than in the deceleration phase. Friction factor in oscillating flow appears to be higher than friction factor in steady unidirectional flow for the highest porosity. For the lower porosities, we observe that the pressure drop and friction factors are similar for maximum Reynolds numbers lower than 5000. An experimental correlation for the friction factor of the regenerator is derived in order to design a millimetric Stirling engine. The friction factor is compared with friction factors reported for woven screens, metal felts and involute foil regenerators.

This paper presents a method to determine the mechanical properties of piezoelectric thin films. The vibrational behavior of microcantilevers and clamped–clamped beams actuated by aluminum nitride (AlN) piezoelectric films were analyzed in order to investigate the suitability of these devices as characterization tools. Different geometries of resonators composed of a free-standing structure made up of a TiPt/AlN/TiPt piezoelectric stack were tested. The out-of-plane motion of the resonators was assessed by laser Doppler vibrometry. An AlN Young’s modulus of about 200GPa was extracted from resonance-frequency measurements by means of Comsol software simulations that allow taking into account AlN underetching. This value of Young’s modulus was compared to the one measured by a nanoindentationtechnique. The quality of crystallinity was also assessed using X-ray diffraction (XRD) measurements. We then estimated the residual stress (about 200MPa) using an interferometry measurement.

In this study, the authors have demonstrated that it is possible to realize several three-dimensional (3D) micro- and nanostructures, by the fabrication of the smallest microhouse using a dual beam scanning electron microscope (SEM)/focused ion beam (FIB) Auriga 60 from Zeiss together with a six degree of freedom robot built with SmarAct components. In this new type of nanolab, cutting, etching, folding, assembling, and then welding thin membranes of silica on top of a cleaved optical fiber SMF28, or production of micro- and nanostructures, like the microhouse, are possible. The authors have experimentally shown that FIB can be used, in this new generation of micro/nanofactory, in combination with SEM, and gas injection system, in order to fabricate three-dimensional microstructures: a microhouse in this study, with ultrahigh accuracy assembly down to 10 nm. By using the theory of sputtering, the authors are able to propose a model of folding thin membranes of numerous materials such as metals, polymers, or crystals, i.e., silica, silicon, potassium tantalite, or lithium niobate. This method is usually described as origami in the literature [W. J. Aroa, H. I. Smith, and G. Barbastathis, Microelectron. Eng. 84, 1454 (2007); W. J. Aroa et al., J. Vac. Sci. Technol., B 25, 2184 (2007); and K. Chalapat et al., Adv. Mater. 25, 91 (2013)]. The experimental results indicate that the introduction of a microrobot inside the SEM vacuum chamber will provide the means to enlarge the scope of clean room facilities to build complex and smart 3D microsystems with heterogeneous materials, especially on the facet of an optical fiber in the lab on fiber new field. The authors propose a new way to easily manufacture many kinds of optical functions for light trapping based on nanoantennas, nanophotonic crystal, axicon or lattice, 3D biosensor with origami, and nanopatterning surfaces or carbon nanotubes, etc.In this study, the authors have demonstrated that it is possible to realize several three-dimensional (3D) micro- and nanostructures, by the fabrication of the smallest microhouse using a dual beam scanning electron microscope (SEM)/focused ion beam (FIB) Auriga 60 from Zeiss together with a six degree of freedom robot built with SmarAct components. In this new type of nanolab, cutting, etching, folding, assembling, and then welding thin membranes of silica on top of a cleaved optical fiber SMF28, or production of micro- and nanostructures, like the microhouse, are possible. The authors have experimentally shown that FIB can be used, in this new generation of micro/nanofactory, in combination with SEM, and gas injection system, in order to fabricate three-dimensional microstructures: a microhouse in this study, with ultrahigh accuracy assembly down to 10 nm. By using the theory of sputtering, the authors are able to propose a model of folding thin membranes of numerous materials such as metals, polymers, ...

Although titanium dental implants are biocompatible, exhibit excellent corrosion resistance and high mechanical resistance, the material fails in providing resistance to infection because it exhibits poor antimicrobial activity. To address these issues, we deposited silver onto titanium abutments (Grade 5 titanium discs) using direct current (DC) sputtering and assessed the antimicrobial activity and biocompatibility of the modified implant material. Atomic absorption spectrometry and X-ray photoelectron spectroscopy were employed to investigate the concentration and elemental composition of the deposited silver. As expected, silver deposited using DC plasma was uniform and good control over the deposition could be achieved by varying the sputtering time. Moderate biocompatible responses (up to 69% viability) were observed in primary human gingival fibroblast cells incubated in the presence of Ti sputtered with Ag for 5min. Silver deposited titanium (Ti-Ag) showed excellent antibacterial effects on Pseudomonas aeruginosa and Streptococcus mutans at a very low concentration (Ag content 1.2 and 2.1μg/mm2). However, higher concentration of silver (6μg/mm2) was required to achieve a reduction in cell viability of Staphylococcus aureus and Candida albicans. The silver sputtered Ti abutments could maintain a long-term antibacterial activity as evidenced by the release of silver up to 22days in simulated body fluid. Our study illustrates that silver deposited titanium is indeed a promising candidate for soft tissue integration on dental abutments and prevents initial microbial adhesion.

Tungsten oxide WO 3 thin films were prepared by dc reactive magnetron sputtering. The GLancing Angle Deposition (GLAD) technique was implemented to transform the typical dense microstructure into an inclined columnar and porous architecture. The incident angle α of the sputtered particles was 0° and 70° leading to a column tilt angle β of 0° and 40°, respectively. Conventional and inclined WO 3 films were sputter deposited on a commercial hotplate system. Ozone gas was periodically injected from 0 to 220 ppb and the variation of electrical conductance of the system was measured vs. time at 250 °C. The conventional WO 3 films exhibited a significant change of electrical conductance as a function of the ozone injection. GLAD WO 3 films with a columnar angle β =40° were even more sensitive to the ozone pulses and the speed of response or recovery was significantly enhanced. This ozone detection improvement was mainly attributed to the more porous structure of WO 3 films produced by the GLAD method.

International audience; Emphasis on effect of oxygen on structural and ferroelectric properties of lead zirconia titanate thin film is reported. The thin film is prepared using RF sputtering and annealed in air atmosphere to introduce oxygen vacancies. The photoelectron spectroscopy data reveal lead rich film, which decreases with annealing temperature, while oxygen content decreases from 59.32–55.82% after annealing. The decrease in oxygen causes pyrochlore formation along with perovskite phase in annealed film. The polarization graph shows reduction in domain wall mobility and film polarization due to oxygen vacancy. The pure perovskite phase is achieved using CFA by inserting O2 in annealing chamber.

International audience; The article presents the design, fabrication and characterization of platinum thin-film Resistance Temperature Detectors (RTDs)for heat flux sensing applications. The microfabrication process is described and the thin films are analysed by several methodsincluding SEM, XRD and profilometry. Estimation of experimental uncertainties is performed. The influence of annealing, selfheating,2-wire and 4-wire connections are studied. The analysis and experimental results show that the RTDs have a goodrepeatability when an annealing process is performed and a maximal injected current are used. A measurement uncertainty of0.14°C is achieved. The observed Temperature Coefficient Ratio is sufficient to ensure variation of the resistance in thetemperature range. The heat flux measurements made with the sensor are validated in a dedicated test bench and present agood repeatability.

International audience; A metal-containing polymer has been prepared by electropolymerization of an homoleptic Ru(II)-terpyridine complex bearing pyrrole heterocycles. The polymer is obtained as a thinfilm at the surface ofelectrodes, and has been characterized by electrochemical measurements, XPS and microscopy. It hasbeen shown that this polymer acts as an active gas sensitive layer since it enables the detection of anammonia gasflow through layer’s resistivity measurements.

We propose the use of a prism with nonlinear optical properties to improve the prism-coupling method. The principle is based on the inscription of an adapted waveguide inside this prism by beam self-trapping to enhance the coupling efficiency and stability. The experimental demonstration is realized with a prism diced from a LiNbO3 wafer to couple light into a resonator.

International audience; The present study demonstrates that thin layers of amorphous silicon oxide (SiOx) grown by inductively-coupled plasma enhanced chemical vapor deposition (ICPECVD) technology at lower temperatures can be successfully combined with biosensors. In particular, gold-amorphous silica (Au/SiOx) interfaces were investigated for their potential applications as a low-cost Surface Plasmon Resonance (SPR) sensor chip. We report here on the fabrication and characterization of stable and good reliabilities of SiOx deposited at 80°C at different pressures. The refractive index (n) of SiOx varied from 1.456 to 1.462. The results show that the sensitivity and minimum light reflectivity at the resonance angle is extremely sensitive to any changes in the index of refraction and any changes in optical thickness.

Diamond-like carbon and carbon nitride films were deposited on high speed steel substrates by plasma enhanced chemical vapour deposition technique. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to investigate the different bondings. Adhesion of the films to the substrate was investigated by the scratch test technique. The mechanical properties were investigated by nano-indentation and the tribological behaviours were tested using a ball-on-disk tribometer. Effect of annealing on adhesion and mechanical properties was also investigated.

International audience; The DC reactive magnetron sputtering of a metallic tungsten target was performed in an argon + oxygen atmosphere for depositing tungsten oxide thin films. In order to control the oxygen concentration in the films, the reactive gas pulsing process, namely RGPP, was implemented. Rectangular pulses were used with a constant pulsing period T = 16 s whereas the duty cycle α (time of oxygen injection to pulsing period T ratio) was systematically changed from 0 to 100% of T. This pulsing injection of the reactive gas allowed a gradual evolution of the films composition from pure metallic to over-stoichiometric WO3+ɛ’ compounds. These WOx films were sputter deposited on commercial MSP 769 Heraeus platforms so as to be used as a sensor for the dodecane gas. It is shown that the sensing performances carried out at 573 K can be adjusted as a function of the duty cycle used during the deposition stage. The relationship between sensing properties and physic-chemical behaviours of the films was especially discussed.

An original composite target configuration with various STi/(STi+SAl) area ratios was used to prepare hard TixAl1−xN thin films by r.f. reactive magnetron sputtering. The crystallographic structure of the films deposited on high-speed steel and glass substrates was determined by X-ray diffraction. Homogeneity was investigated from compositions and depth profile measurements carried out by Rutherford backscattering spectroscopy, electron probe microanalysis and glow discharge optical emission spectroscopy. The modulation of the Ti and Al area ratios of the target produced changes of the structure from the fcc TiN to the hexagonal AlN phase and simultaneously, a gradual modification of the TixAl1−xN metal concentration from x=0 to 1. The mechanical behaviours such as hardness and scratch tests were also determined and correlated with the evolution of the structural and compositional properties.

We show that the near-field coupling between a photonic crystal microlaser and a nano-antenna can enable hybrid photonic systems that are both physically compact (free from bulky optics) and efficient at transferring optical energy into the nano-antenna. Up to 19% of the laser power from a micron-scale photonic crystal laser cavity is experimentally transferred to a bowtie aperture nano-antenna (BNA) whose area is 400-fold smaller than the overall emission area of the microlaser. Instead of a direct deposition of the nano-antenna onto the photonic crystal, it is fabricated at the apex of a fiber tip to be accurately placed in the microlaser near-field. Such light funneling within a hybrid structure provides a path for overcoming the diffraction limit in optical energy transfer to the nanoscale and should thus open promising avenues in the nanoscale enhancement and confinement of light in compact architectures, impacting applications such as biosensing, optical trapping, local heating, spectroscopy, and nanoimaging.

Transducer on Periodically Poled Lithium Niobate (PPLN) exhibiting an electromechanical coupling about 20% and an equivalent phase velocity about 10 km.s−1 were shown in [1]. These transducers are 3D structured to overcome Surface Acoustic Wave (SAW) and Bulk Acoustic Wave (BAW) technological limits, such as short circuit between electrodes for SAW and precise thickness control for BAW. The present work shows the use of these 3D structured transducers for Radio Frequency (RF) filtering. An acoustic filter showing a band pass of about 5MHz has been realized on Lithium Niobate at 250MHz. This filter is made of PPLN exhibiting a poling period of 14.9μm.

(Ti1−xAlx)N films were deposited by radio frequency reactive magnetron sputtering on a high speed steel substrate. The structure and composition of the coatings were analysed by various techniques. Hardness and adhesion of the films were investigated using Vickers micro-indentation and scratch test respectively, whereas their tribological properties were studied using a pin-on-disk tribometer. The results show that increasing aluminium content leads to increase hardness of the films and to decrease their wear resistance when sliding against a magnesia-stabilized zirconia ball. On the contrary, no clear dependence of the film adhesion on the aluminium concentration was detected.

Titanium and titanium oxide thin films have been deposited on (100) silicon wafers and glass substrates by r.f. reactive sputtering magnetron. Substrates have been r.f. biased during the growth of the film and the influence of the bias power on some properties of the coatings has been investigated. The results of the deposition rate measurements show that this is weakly affected when bias power is low. As the r.f. bias power increases, the deposition rate decreases strongly due to an increase of the layer density and resputtering phenomena. Atomic force microscopy showed that the surface morphology of metallic and oxide films can be modified using bias treatment. Roughness analyses exhibited a similar evolution as the deposition rate and surface topography when bias power changes. Optical properties like refractive index followed the same variations as previous results. So, when r.f. bias power increases, various phenomena take place and different zones can be defined from these investigations. Argon ion to atom arrival rate ratio and average energy per deposited atom have been calculated from experimental values of current density applied to the substrate and energy of argon ions impinging on the growing film. Their evaluations have been discussed for metallic and oxide materials.

b Universite de Franche-Comte, FEMTO-ST, Besancon 25030, France Abstract. We present an optimization process to improve the rejection ratio in integrated beam combiners by locking the dark fringe and then monitoring its intensity. The method proposed here uses the electro-optic effect of lithium niobate in order to lock the dark fringe and to real-time balance the photometric flux by means of a two- stage Mach-Zehnder interferometer waveguide. By applying a control voltage on the output Y-junction, we are able to lock the phase and stay in the dark fringe, while an independent second voltage is applied on the first- stage intensity modulator, to finely balance the photometries. We have obtained a rejection ratio of 4600 (36.6 dB) at 3.39 μm in transverse electric polarization, corresponding to 99.98% fringe contrast, and shown that the system can compensate external phase perturbations (a piston variation of 100 nm) up to around 1 kHz. We also show the preliminary results of this process on wide-band modulation, where a contrast of 38% in 3.25- to 3.65-μm spectral range is obtained. These preliminary results on wide-band need to be opti- mized, in particular, for reducing scattered light of the device at the Y-junction. We expect this active method to be useful in high-contrast interferometry, in particular, for astronomical spatial projects actually under study.

Surface Acoustic Wave (SAW) and Bulk Acoustic Wave (BAW) devices are largely used in telecommunication for radio Frequency (RF) signal processing. Nevertheless, these devices are limited by various factors such as short-circuit between electrodes for SAW and precise thickness control for BAW. This paper shows the interest of a new kind of transducer using Periodically Poled Lithium Niobate (PPLN) developed to overcome SAW and BAW technological limits. A former PPLN-based wave-guide was presented some years ago exploiting planar technologies. The novelty of the present work lies in the 3D structuring of the transducer allowing for very high aspect ratio structures exhibiting a theoretical electromechanical coupling about 20% and a phase velocity up to 20 km.s-1.

For an increasing number of application (energy production, car industry, space, etc.), hydrogen appears as a solution of the future as it is the most common body in the Universe (and therefore on Earth). However, due to its unstable properties, a particular care must be dedicated to control possible gaseous leaks close to facilities using this resource. Here we propose surface acoustic wave sensors for detecting gaseous hydrogen in standard environmental conditions (atmospheric pressure and room temperature). The proposed SAW sensors consists in two Rayleigh-wave delay lines built on Quartz. One equipped with a Palladium overlay and the other exhibiting a free path between the two interdigitated transducers. A dedicated hermetical gas test cell has been developed to test the efficiency of the sensor when exposed to hydrogen-composed atmospheres. A particular care was paid to avoid hydrogen leakage in the working environment and to perform the regeneration of the gas absorbing layer. The developed SAW devices exploiting hydrogen absorption capabilities of palladium layers exhibiting different thicknesses have been here used to make the detection and the identification of hydrogen concentrations (in the 0.25-2% range) diluted in nitrogen and is also able to make detection in current atmosphere. The effect of the palladium thickness variations along with the influence of an Yttrium doping of the palladium layer on the sensor behavior will be studied here.

Titanium thin films were deposited by DC magnetron sputtering. The glancing angle deposition (GLAD) method was implemented to prepare two series of titanium films: perpendicular and oriented columnar structures. The first series was obtained with a conventional incident angle α of the sputtered particles (α = 0°), whereas the second one used a grazing incident angle α = 85°. Afterwards, the films were annealed in air using six cycles of temperature ranging from 293 K to 773 K. DC electrical conductivity was measured during the annealing treatment. Films deposited by conventional sputtering (α = 0°) kept a typical metallic-like behavior versus temperature (σ300 K = 2.0 × 106 S m-1 and TCR293 K = 1.52 × 10-3 K-1), whereas those sputtered with α = 85° showed a gradual transition from metal to dielectric. Such a transition was mainly attributed to the high porous structure, which favors the oxidation of titanium films to tend to the TiO2 compound.

National audience; La surface d'un substrat de cuivre a été fonctionnalisée grâce à une technique d'auto-assemblage d'une monocouche d'acide phosphonique. Après caractérisation de ce film, un excellent comportement tribologique est noté lorsqu'aucun nettoyage ultrasonore n'est effectué, pour des conditions de sollicitation de pression de 133 MPa et de vitesse de glissement de 1mm/s sur un tribomètre alternatif linéaire utilisant un frotteur en Si3N4 (μ = 0.12, durée de vie multipliée par 100). Des espèces physisorbées, sous formes d'amas de plusieurs μm3, présentes sur la monocouche semblent responsables de ce bon comportement. De premiers essais sur un tribomètre d'étirage-plan ont montré un réel potentiel de ce type de fonctionnalisation en emboutissage.

The development of transducers alternative to usual surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices for RF signal processing is strongly motivated by the need for improved operating characteristics to face modern telecommunication challenges. This paper shows the interest of a new concept of periodically poled transducers (PPT) on Lithium Niobate (LiNbO 3 ). This new kind of transducer has been developed to overcome technological limits of SAW inter-digitated transducers (short-circuits between electrodes for instance) or precise thickness control of BAW devices piezoelectric material. The novelties of the structure compared to already achieved work on PPT lies in the 3D structuring of the transducer. High aspect ratio ridges are achieved on PPT plates and an adapted metallization allows for the excitation of modes exhibiting theoretical electromechanical coupling in excess of 20% with predicted phase velocities close to 18000m.s−1.

Optimization of RF sputtered piezoelectric PZT thin films for thickness and stoichiometry for use in MEMS application is discussed in this paper. The effect of sputtering parameters on PZT film stoichiometry is studied using EDS and XPS techniques. 600 nm thin PZT film with Zr:Ti ratio of 52∶48 is achieved in single sputtering cycle. The film is annealed using conventional furnace annealing technique and the effect of annealing process on phase formation is studied using XRD technique. The optimized PZT thin film shows sufficiently good stoichiometry. A piezoelectric coefficient (d33) value for PZT thin film deposited at optimum parameters is 450pm/V. Optimized PZT thin film parameters are used for successful fabrication of cantilever using silicon bulk micromachining.

Colloque avec actes et comité de lecture. Internationale.; International audience; L'étude vise à modifier les propriétés de perméation au gaz d'un polymère par dépôt d'une couche mince. Le substrat impose des techniques de dépôt en basse température afin d'assurer son intégrité. Il convient de relever deux défis : le premier est de parvenir à réaliser un dépôt à porosité réduite afin d'en garantir la fonctionnalité. La perméation à l'hydrogène permet de l'étudier. Le second réside dans la tenue mécanique: l'adhésion sous sollicitations sévères est un paramètre critique. Une des applications visées est la conception de liner de type 4 pour le stockage hydrogène.

We report the development of a quick process for fabricating lithium niobate ridge waveguides with smooth walls, aspect ratios larger than 500 and side-wall verticality of 88°. The method is based on optical grade dicing, and allows the fabrication of ridges with a top width of 1 µm and a depth of more than 500 µm. Smart-cut ridge waveguides and strongly confined proton exchanged ridge waveguides are demonstrated. We show that the method enables the fabrication of ridge waveguides with propagation losses as low as 0.5 dB cm−1. A new fabrication process is thus proposed for the fabrication of optical components with enhanced acousto-optic, electro-optic or nonlinear interactions. The high aspect ratios open opportunities towards the development of 3D photonic components in thin films of LiNbO3, and towards hybrid integration of LiNbO3 components.

A 3 : 1 composition of functional monomer (FM)-multifunctional acrylate was spin-coated and later crosslinked under the influence of oxygen plasma on the surface of poly(dimethyl siloxane) (PDMS) to generate a surface-anchored crosslinked network bearing functional moieties. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and wetting angle measure- ments were used to analyze the crosslinked monomer surfa- ces. Scanning electron microscopy was used to visualize the surface of the film after modification. The results of the sur- face reconstruction of the FM surfaces and plasma-treated PDMS reveal that long-term hydrophilic surfaces were achieved. Thus, the surface architecture could be favorably manipulated with this remarkable technique with a suitable combination of FMs and crosslinkers. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1426-1430, 2011

International audience; We present the development and study of a single bowtie nano-aperture (BNA) at the end of a monomode optical fiber as an interface between near-fields/nano-optical objects and the fiber mode. To optimize energy conversion between BNA and the single fiber mode, the BNA is opened at the apex of a specially designed polymer fiber tip which acts as an efficient mediator (like a horn optical antenna) between the two systems. As a first application, we propose to use our device as polarizing electric-field nanocollector for scanning near-field optical microscopy (SNOM). However, this BNA-on-fiber probe may also find applications in nanolithography, addressing and telecommunications as well as in situ biological and chemical probing and trapping

International audience; The anodic oxidation of concentrated glycine based aqueous electrolyte on smooth platinum electrode leads to a strongly grafted polyglycine-like coating on the surface in an irreversible way. Due to the proton affinity towards amino groups of polyglycine (PG), the electrodeposited thin film was used as receptor for solid potentiometric pH sensor. In order to reach local pH measurement, we developed miniaturized microelectrodes on glass substrate thanks to photolithography process. We used silver chloride on silver as the reference electrode. The couple (silver chloride, PG based platinum electrode) of microelectrodes gives linear potentiometric response vs. pH in the range [2–12], reversibly and with a sensitivity of 52.4 mV/pH (for 1 mm electrode size). PG based pH electrode is compared to other organic polymer based pH receptor such as linear polyethylenimine (L-PEI), polyaniline (PANI) and glass membrane.

International audience; We report on two approaches to achieve ultra-smooth structures on lithium niobate (LiNbO3) substrates. The first method relies on ICP-RIE (inductively coupled-reactive ionic etching) or on RIE, and is exploited here for the fabrication of rods with smooth etched surfaces. A series of tests have been performed with fluorine gases. Nanometric rods with 200, 400 or 600 nm diameters, with a periodicity of 400, 800 and 1200 nm respectively and etched angles close to 68 for the RIE process and 75 for the ICP-RIE process have been fabricated. The second process is based on ''optical grade dicing'' and is dedicated to the fabrication of deep-etched ridge waveguides. First optical characterization results are reported. They show optical propagation losses value close to 0.1 dB/cm.

International audience; We present LiNbO3 nanostructures with ultra-smoothed walls realized by FIB or ICP-RIE. Besides, we de-scribe an original approach based on "optical grade dicing" for fabricating ridges dedicated to the coupling of light into photonic (PhC) cavities. Experimental transmissions responses through PhC cavities are finally presented.

International audience; Two dry subtractive techniques for the fabrication of microchannels in borosilicate glass were investigated, plasma etching and laser ablation. Inductively coupled plasma reactive ion etching was carried out in a fluorine plasma (C4F8/O2) using an electroplated Ni mask. Depth up to 100 μm with a profile angle of 83°-88° and a smooth bottom of the etched structure (Ra below 3 nm) were achieved at an etch rate of 0.9 μm/min. An ultrashort pulse Ti:sapphire laser operating at the wavelength of 800 nm and 5 kHz repetition rate was used for micromachining. Channels of 100 μm width and 140 μm height with a profile angle of 80-85° were obtained in 3 min using an average power of 160 mW and a pulse duration of 120 fs. A novel process for glass-glass anodic bonding using a conductive interlayer of Si/Al/Si has been developed to seal microfluidic components with good optical transparency using a relatively low temperature (350°C).

International audience; Polyethyleneimine films have been deposited on platinum electrode surfaces by electrochemical oxidation of ethylenediamine H2N-CH2-CH2-NH2 (EDA) in acetonitrile solutions. This electrochemical synthesis was realized by cyclic voltammetry and gravimetry techniques. Then, the characterization of the thin solid polyethyleneimine film was performed using X-ray photoelectron spectroscopy and infrared spectroscopy. It was also shown, using atomic force microscopy, that the solid polymeric coating has a granular and homogeneous structure. The influence of EDA concentration on the electropolymerization process was studied leading to the conclusion that the reaction is easier for high EDA concentration. Then, the influence of the nature and concentration of the supporting salt was investigated, showing that its nature is not very important, contrary to its concentration.

International audience; In this paper, we report the realization of a double Bragg gratings (BG) structure based on titanium-diffused optical waveguides in lithium niobate Ti:LiNbO3 by using Focused Ion Beam (FIB) technique. A double filtering function in wavelengths around the bands 1200nm and 1550nm has thereby been achieved

International audience; In this paper we have studied effect of depth etching on the Bragg gratings (BGs) realized by Focused Ions Beam. This technique has the advantage to induce a direct waveguide structuring without intermediate media, comparing to traditional methods. A reflectivity of 96% within a window centred at 1550 nm is obtained. The effect of the depth etching on the transmittance and the bandwidth at half maximum is demonstrated.

International audience; A simple method to prepare flat gold terraces on mica for atomic force microscopy biomolecular characterisation is described. The procedure includes preheating of the substrate, metal deposition and an annealing step. All of these steps are at elevated temperatures (300–420°C). This approach allows one to prepare large flat gold terraces (200– 500 nm), which constitute ideal substrates for visualisation and characterisation of a self-assembly monolayer of biomolecules at the nanoscale. The authors illustrated this potential of characterisation with the reconstitution of a protein monolayer.

Nowadays, almost all the cutting tools in metal machining are protected with a surface treatment. Nevertheless, this is not the case in woodmachining where no tools are protected, except by thermal treatments, and so they present a previous wear because of the use of steel or carbide materials in milling, sawing, routing, etc. During these processes, the tools are particularly exposed to abrasive and shock wear. To enhance their wear resistance, one solution is to protect them with hard coatings. The present study deals with the development of ternary systems (CrAlN and CrSiN) obtained by two PVD different magnetron sputtering systems [‘A’ (laboratory where CrAlN layers have been obtained) and ‘B’ (laboratory where CrSiN layers have been obtained) in the following text] on carbide WC–Co tools used in second transformation of wood to be compared to the binary CrN one. CrAlN and CrSiN films were deposited with different Al and Si contents, respectively, in order to check the effect of the additive element (Al or Si) on the different properties of the Cr–N system. The different coatings were characterized by SEM and EDS for thickness measurements, morphology and composition analyses, respectively, by nanoindentation for hardness and Young’s modulus measurements and by pin-on-disc to determine their friction coefficient. Routing of medium density fibreboard (MDF) was realized employing untreated or modified carbide WC–Co tools in order to compare their wear resistance. We observed that the Al and the Si addition improved the hardness and the Young’s modulus of the Cr–N system (‘A’: 29 and 410 GPa, respectively, ‘B’: 18 and 280 GPa, respectively). Indeed, the hardness values are 15–36GPa for CrAlN and 15–24 GPa for CrSiN coatings. Besides, the Young’s modulus values are 331–520GPa for CrAlN and 260–320 GPa for CrSiN coatings. The friction coefficient of the CrAlN layers varied between 0.6 and 0.7 and it increased slightly with the Al content. For the CrSiN coatings, the friction coefficient was lower and about 0.4. In both cases, the CrN layers ‘A’ and ‘B’ presented similar friction coefficient than CrAlN and CrSiN, respectively. During the routing of MDF, the CrN ‘A’ coating has a similar wear behaviour than the optimized CrAlN one (5 at.% of Al) while the optimized CrSiN coating (1.2 at.% of Si) showed a better behaviour against wear than the CrN ‘B’ one. The wear resistance of CrAlN- and CrSiN-coated carbide tools ecreased when the Al and Si contents increased. Regional Council of Burgundy Regional Council of Franche-Comté ISOROY France