Corrigendum to “Influence of nitrogen incorporation on the electrical properties of MPCVD diamond films growth in CH4–CO2–N2 and CH4–H2–N2 gas mixtures” [Thin Solid Films 374 (2000) 27–33] O. Elmazria , J. Bougdira , H. Chatei , L. De Poucques , M. Remy ⁎, P. Alnot a a Laboratoire de Physique des Milieux Ionises & Application (CNRS UPRES A 7040) Universite Henri Poincare, Nancy I, France b Laboratoire de Physique Theorique et des Particules, Faculte des Sciences, Universite Mohamed I, Oujda, Morocco

Surface acoustic wave (SAW) devices based on waveguide modes with shear-horizontal polarization (Love modes) are very promising for sensor applications, especially in liquid media. We present here the realization of a 2 GHz operating frequency sensor based on the SiO2/36YX LiTaO3 structure with an integrated PDMS micro-flow channel and using electron beam lithography to realize the submicronic interdigital transducers. Using our developed sensor operating at 2 GHz, we carried out alternate cycles of nitrogen and water circulating in the PDMS micro-flow channel. We measured an absolute sensitivity of ?19?001?Hz?mm2?ng?1 due to the interaction of the sensor with water. This sensitivity is higher than that of other devices operating at lower frequencies. The detection mechanism, including gravimetric and permittivity effects at high frequency, will be discussed.

The non-equilibrium process of polymerization of reactive polymers can be accompanied by transition phenomena like gelation or the chemical glass transition. The sensitivity of the mechanical properties at hypersonic frequencies-including the generalized Cauchy relation-to these transition phenomena is studied for three different polyurethanes using Brillouin spectroscopy. As for epoxies, the generalized Cauchy relation surprisingly holds true for the non-equilibrium polymerization process and for the temperature dependence of polyurethanes. Neither the sol-gel transition nor the chemical and thermal glass transitions are visible in the representation of the generalized Cauchy relation. Taking into account the new results and combining them with general considerations about the elastic properties of the isotropic state, an improved physical foundation of the generalized Cauchy relation is proposed.

A new kind of surface acoustic wave (SAW) sensor has been developed in order to measure sub-atmospheric pressure below 100 mTorr with accuracy better than 0.1 mTorr. It provides an efficient measuring solution in a pressure range inaccessible in past by conventional diaphragm-based SAW sensors. Indeed, due to the small bending force in low pressure and limited sensitivity, diaphragm-based SAW sensors are only suited to monitor relatively high pressure with a precision hardly better than 0.5 Torr. In order to reach precision level better than 1 mTorr at sub-atmospheric pressure for vacuum technology applications, a radically different SAW-based solution is desired. Our device aims to measure sub-atmospheric pressure less than 100 mTorr with a threshold resolution better than 0.1 mTorr. The concept is similar to the one used by Pirani pressure gauges. However, it is claimed that a heated and suspended SAW device may have better sensitivity. A theoretical model based on the basic concepts of gas kinetic theory and thermodynamics is presented. The validity of the model is checked by comparison between theoretical and experimental results.

High performance Brillouin microscopy has been used as a versatile method in order to characterize the spatial distribution of piezoelectrically induced acoustic fields excited at microwave frequencies in a ZnO film deposited on silicon. Filtering properties and acoustic field distribution emitted by inter-digital transducers as well as propagation losses are investigated by μ-Brillouin spectroscopy. It turns out that the acoustic field intensity decreases dramatically outside the immediate excitation area situated below the inter-digital finger structure.

Very high frequency surface acoustic wave (SAW) devices based on the AlN/diamond layered structure are fabricated by direct writing using e-beam lithography on the nucleation side of nanocrystalline diamond (NCD) films deposited by microwave plasma assisted chemical vapor deposition process. The NCD nucleation side is characterized from the point of view of microstructure, morphology and surface topography. Surface roughness as low as 6 nm is reached, which enhances the deposition of AlN film on this flat surface. The interdigital transducers IDTs made in aluminum with lateral resolution down to 600 nm are successfully patterned on the AlN/NCD layered structure with an adapted technological process. Experimental results show that the Rayleigh wave and the higher mode are generated. A high frequency around 4 GHz (mode 1) is obtained for the considered layered structure SAW device, exhibiting a phase velocity of 9200 m/s taking into account the wavelength of 2.4 μm. This value agrees well with calculated values determined from dispersion curves of phase velocity.

SAW devices based on waveguide modes with shear-horizontal polarization (Love modes) are very promising for sensor applications, especially in liquid media. We present here the realization of a 2GHz operating frequency sensor based on SiO2/36Y-X LiTaO3 structure with integrated PDMS micro flow channel and using electron beam lithography to realize the submicronic interdigital transducers. Using our developed sensor operating at 2 GHz, we carried out alternate cycles of nitrogen and water circulating in the PDMS micro flow channel. We measured an absolute sensitivity of -19001 Hz.mm(2)/ng due to the interaction of the sensor with the water. This sensitivity is higher than that of other devices operating at lower frequencies. The detection mechanism, including gravimetric and permittivity effects at high frequency will be discussed.

Many phenomenological properties of reactive polymers like polyurethanes increase or decrease continuously in the course of the curing process before saturating at the end of the chemical reaction. This holds true for instance for the mass density, the refractive index, the chemical turnover and the hypersonic properties. The reason for this monotone behaviour is that the chemical reaction behaves like a continuous succession of irreversible phase transitions. These transitions are superposed by the sol-gel transition and possibly by the chemically induced glass transition, with the drawback that the latter two highlighted transitions are often hidden by the underlying curing process. In this work we propose generalized mode Gruneisen parameters as an alternative probe for elucidating the polymerization process itself and the closely related transition phenomena. As a model system we use polyurethane composed of a diisocyanate and varying ratios of difunctional and trifunctional alcohols.

Reactive network forming polymer systems like epoxies are of huge technological interest because of their adhesive properties based on specific interactions with a large variety of materials. These specific interactions alter the morphology of the epoxy within areas determined by the correlation length of these interactions. The changed morphology leads to interphases with altered (mechanical) properties. Besides these surface-induced interphases, bulk interphases do occur due to segregation, crystallization, diffusion, etc. A new experimental technique to characterize such mechanical interphases is μ-Brillouin spectroscopy (μ-BS). With μ-BS, we studied interphases and their formation in epoxies due to segregation of the constituent components and due to selective diffusion of one component. In the latter case, we will demonstrate the influence of changing the boundary conditions of the diffusion process on the shape of the interphase.

We report in this paper, the fabrication process of surface acoustic wave (SAW) devices by direct writing using electron beam lithography on very high resistivity materials, and the frequency characterization of the high frequency devices realized using this technologic process. Various experimental parameters relative to lithography system, resist deposition and lift-off process were studied and optimized. We have realized SAW devices on 36degYX LiTa03 substrates by structuring the interdigital transducers (IDTs), using a MMA/PMMA bilayer resist combined with lift-off process. The problem consisting in proximity effects was resolved by electron dose adjusting and non-uniformity exposure of the structure. The IDTs made in aluminum with resolutions down to 400 nm were successfully patterned on LiTaO3 with an adapted technological process. The analysis of the IDTs' periodicity and of the homogeneity of their thickness was carried out using atomic force microscopy and field emission scanning electron microscopy. A very regular thickness and regular lateral resolution was obtained. The frequency characterization performed by network analyzer shows that the realized SAW device operates at 5.1 GHz when the 3rd harmonic of the filter is considered. The different propagation modes, GSAW, PSAW and HVPSAW, relative to the 36degYX LiTaO3, were identified.

In this work, we report about the study of electromechanical coupling coefficient (K 2 ) and temperature coefficient of frequency (TCF) of SAW devices based on AIN/diamond layered structure intended for the X band (8 GHz). SAW devices operating in the range of 8 GHz were realized by the combination of the high velocity of the AIN/diamond layered structure and the high lateral resolution obtained using e-beam lithography (EBL). Due to high electrical resistivity of the AlN film, interdigital transducers with sub-micronic resolution were patterned by an adapted technological EBL process. The analyses of structural and morphological of the diamond and AlN layers by X-ray diffraction, atomic force microscopy (AFM) were carried out. They showed the highly (002) preferential orientation of AlN film deposited on diamond layer and a very weak surface roughness of less than 1 nm measured on the surface of AIN/diamond layered structure. The analysis of device performances in terms of K 2 and temperature stability were carried out and discussed. The dispersion of both parameters as a function of normalized thickness of AlN layer (kh AlN ) was experimentally determined, and showed the obtaining of electromechanical coupling coefficient up to 1.4% for normalized thickness kh AlN varying between 3 and 5. Concerning the TCF, the recorder values show a quasi- parabolic behavior. This TCF behavior in such high frequencies will discussed taking into account the nature of the TCF of AlN and diamond layers separately.

In this work nanocrystalline diamond (NCD) was investigated as high velocity and low propagation loss substrate for SAW devices. The considered layered structure is AIN/NCD/Silicon. First the 16 mum of (110)-oriented NCD films were grown on <100>-oriented silicon substrates of approximately 2.5 cm2 in size. Smooth piezoelectric AIN films with columnar structure and (002) orientation were then deposited on the NCD surface. The AIN film thickness was fixed to 1 mum and the spatial periodicity of IDT to 20 mum. The operating frequency of the realized device was measured at 645 MHz. This shows that surface acoustic waves being propagated at the velocity of 13 km/s were generated in this structure. The obtained velocity value is a quite higher than the value obtained by calculation when elastic constants of polycrystalline are used.

AlN films with c-axis oriented perpendicular to the surface were deposited on silicon substrates by reactive RF magnetron sputtering method, at various temperatures ( without heating -400 degrees C). The structural, morphological and optical properties of AlN films were investigated by X-ray diffraction, scanning electron microscope, atomic force microscopy and Fourier transform infrared absorbance spectroscopy. It was found that the AlN films showed the same highly ( 002) preferred orientation with low full with of half maximum of rocking curve, which is about 2 degrees for all the deposited films. The surface roughness of AlN films determined by AFM is less than 1nm for the film grown at low temperature. This result is very important and means that films with good crystalline quality, low surface roughness can be processed at low temperature. Elastic properties of deposited AlN films were evaluated by realization and characterization of AlN/silicon SAW device.

Optical properties of the fluorocarbon (FC) films plasma deposited on Si substrates are evaluated in this work using multiple sample analysis (MSA)-based spectroscopic ellipsometry (SE) with representing the film optical constants by the Forouhi-Bloomer (FB) and Tauc-Lorentz (TL) optical dispersions. This SE analysis supported also with other film investigations results in a two-layer optical model consisting of an interface assimilated to FC species-permeated Si layer beneath a surface smooth, homogeneous, and isotropic FC bulk film. Both dispersions yield a low-dielectric constant quality visible range refractive index of 1.39 and almost identical model layer thicknesses. Deposition-dominated linear film growth is thus asserted. Specifically, the FB dispersion better describes the region near absorption cutoff with taking up a lower optical band gap (OBG) than that of the TL dispersion, indicating thereby that particular FC film absorptions included in the FB dispersion are excluded in the other. Also, the FB index spectrum tends to peak towards a broad maximum in the ultraviolet (UV) wavelength range, whereas this trend is absent in the TL index spectrum probably removed by the TL parameter cross correlations although reduced by MSA. Sample to sample analysis further shows that the TL parameter correlation is accentuated by the instrument-limited UV range. The FB parameters are much less affected by cross correlation such that even the sample to sample analysis may be readily used in conjuncture with the FB dispersion for thicker FC films above 150nm to monitor their index and OBG in tailoring desired film physical properties through deposition conditions.

In this paper we present potassium niobate elastic and piezoelectric constants measurements. These experiments have been performed by Brillouin spectroscopy which gives a direct access to the elastic coefficient by measuring the acoustic velocity. To avoid problems related to the angle precision on Brillouin spectroscopy, three different samples corresponding to X-cut, Y-cut and Z-cut have been used. The complete set Of elastic constants is given and results are compared with those obtained previously by other authors. A discussion around the accuracy of the results is developed to explain discrepancy between previous results given in the literature.

In this study, Surface Acoustic Waves (SAW)/Liquid interaction (SAW streaming) was used to heat small droplet (few mu l). SAW devices were designed on a 128 degrees rotated Y-cut X-propagating LiNbO3 2 '' wafer with center frequency of 39,92 MHz. When the droplet is placed on the acoustic path, a longitudinal wave is radiated into the liquid. When SAW amplitude is sufficient, several phenomena can happen such as droplet actuation, internal flow into the droplet, atomisation. Recently, Kondoh et al. have demonstrate that irradiation of droplet by SAW is a powerful technique for heat small amount of liquid. Here, we want to quantify this effect (in static mode) in a wide range of viscosity as a function of SAW power which is correlated with SAW amplitude. We have worked with a non-contact infrared thermometer to measure droplet temperature and in order to explore wide range of viscosity Water-Glycerol mixture has been used. We notice that more droplet viscosity increase, more higher is the temperature. Finally, the liquid temperature can be controlled by the SAW power A droplet can be consider as a micro-reactor because, it act both as a efficient mixer and fluidic thermocycler This can be interesting for lab on chip.

In this paper we present the fabrication and characterization of nanocomposite materials based on crystalline nanoparticles dispersed in an oligomer matrix (DGEBA, used in epoxy resin). Two types of nanoparticles are used. Al2O3 nanoparticles, commercially available, allow us to carry out the fabrication process of the nanocomposites. This system (DGEBA+Al2O3) is considered as a reference for the second one based on iron iodate nanoparticles fabricated by co-precipitation. The nanocomposite fabrication process is described. The dispersion step and the problems inherent to clusters destruction are underlined. Iron iodate nanoparticles are characterized by TEM, SEM, X-ray diffraction, Raman spectroscopy and EDX. Results point out that the nanoparticles have dimensions between 20 and 30 nm and present two different morphologies (ball and needle). Mechanical properties of the nanocomposite based on Al2O3 are explored by Brillouin spectroscopy. An enhancement of the Young's modulus is observed with a very weak mass percentage of nanoparticles (3%), the glass transition is also shifted from 247 K to 251 K. X-ray diffraction measurement on iron iodate nanocomposite demonstrates that nanoparticles remain in the same phase (P63) after the nanocomposite preparation process. This result is of great importance in order to achieve piezoelectric and ferroelectric applications.

The nature of the glassy state and of the glass transition of structural glasses is still a matter of debate. This debate stems predominantly from the kinetic features of the thermal glass transition. However the glass transition has at least two faces: the kinetic one which becomes apparent in the regime of low relaxation frequencies and a static one observed in static or frequency- clamped linear and non-linear susceptibilities. New results concerning the so-called alpha-relaxation process show that the historical view of an unavoidable cross-over of this relaxation time with the experimental time scale is probably wrong and support instead the existence of an intrinsic glass transition. In order to prove this, three different experimental strategies have been applied: studying the glass transition at extremely long time scales, the investigation of properties which are not sensitive to the kinetics of the glass transition and studying glass transitions which do not depend at all on a forced external time scale.

We report in this paper on the study and the realization of surface acoustic wave devices based on an AlN/diamond layered structure intended for the X band (8 GHz). Both x-ray diffraction and transmission electronic microscopy, used for characterization of the structural properties of the AlN/diamond structure, have shown (002) highly oriented sputtered AlN films on free-standing chemical vapor deposition diamond films. Surface roughness of the AlN/diamond structure was measured by atomic force microscopy and showed a very low surface roughness, less than 1 nm. Low surface roughness is very important to reduce the acoustic propagation losses. SAW devices operating in the range of 8 GHz were realized by the combination of the high velocity of the AlN/diamond layered structure and the high lateral resolution obtained using e-beam lithography (EBL). Due to high electrical resistivity of the AlN film, interdigital transducers with submicronic resolution were patterned by an adapted technological EBL process. The analysis of device performances in terms of electromechanical coupling coefficient and temperature stability was carried out and discussed. The dispersion of both parameters as a function of wavelength was experimentally determined, and showed the obtention of an electromechanical coupling coefficient up to 1.4% and a temperature coefficient of frequency varying between 9 and 20 ppm/°C. The dispersion curves of phase velocity were also analyzed and experimental results show a good agreement with theoretical calculations.