In this study, AlN films are deposited using reactive RF magnetron sputter on various bottom metals, such as Mo, Al and Pt. The orientation of piezoelectric AlN thin films on different bottom electrode materials are investigated. Moreover, the acoustic Bragg reflectors deposited by DC magnetron sputter are composed of alternating layers of high and low acoustic impedance materials. To improve the performance of the reflectors, rapid thermal anneal and deposition process control over roughness of the thin film are also investigated. The resonance characteristics are improved obviously by deposition process control over thin films. The roughness control is the key factor of good frequency responses of SMR. In addition, the more layer of the reflectors the better the frequency response we obtained. The frequency responses of SMR are slightly improved by rapid thermal annealing procsess. Although defects in the thin films would be eliminated, nevertheless the thin film roughness became worse after annealing. This phenomenon would limit the improvement of frequency responses.

Recently, there are great demands for RF band pass filters with smaller size/volume, lighter weight, and higher performance for advanced mobile/wireless communication system. However, fabricated RF filters using traditional lumped element, dielectric resonators, or surface acoustic wave¡]SAW¡^filters have difficulties in on-chip integration, power handling capability, and temperature compensation. Alternatively, thin-film bulk acoustic wave resonator¡]FBAR¡^filters are very suitable devices for MMIC¡¦s since they can be fabricated on Si or GaAs substrates at a lower magnitude than lumped elements or dielectric resonators, plus they have a much lower insertion loss and higher power handling capabilities than surface acoustic wave devices and full integration with other CMOS RF IC circuitry for realizing a goal of system on chip¡]SOC¡^. In their simplest form, practical FBARs consist of a sputtered piezoelectric thin film sandwiched between top and bottom electrodes onto which an electric field is then applied. An FBAR must have two acoustically reflecting surfaces in order to trap energy and produce resonating characteristics. For this purpose, the thin film bulk acoustic resonator has to be isolated acoustically from the substrate. In view of this, in order to obtain a high Q factor and reduce spurious responses, this paper proposed the air gap type resonator using the sacrificial layer etching. The thickness of the AlN thin film used for piezoelectric thin film of Air-gap FBAR is 1um. Pt/Ti with 3000Å/300Å thickness is used as the top and bottom electrode. The device has a resonance frequency of 1.2GHz, and S11-paparameter of -25dB is also obtained.

Aluminum nitride (AlN) thin films were deposited on SiO2/Si substrates using the reactive RF magnetron sputtering in this thesis. By means of the analysis of XRD, SEM, TEM and AFM, the optimal deposition conditions of highly C-axis oriented AlN films were obtained with RF power of 190W, sputtering pressure of 3mTorr, nitrogen concentration (N2/N2+Ar) of 30%, and substrate temperature of 400¢J. The characteristics of films annealed at temperature range from 600¢J to 1150¢J with N2 flow for 2 hours has been studied. Experimental results reveal that the films retain the high quality up to 800¢J. But when the temperature above 1000¢J, AlN films will be oxided to AlO:N. In addition, the interdigital transducers (IDTs) were fabricated on the films annealed at 800¢J for 2 hours to study the characteristics of SAW devices. The results show that the central frequency, insertion loss and phase velocity of SAW were 182.25 MHz, -12.95 dB and 5824 m/sec, respectively. At the same time, we try to match the impedence of devices and improve the frequency response by using a simulation program. After the impedence was matched, the insertion are not strongly improved but the frequency response and closed-in sidelobe rejection exhibit better. The effects of temperature on the SAW devices show that the central frequency almost does not shift when the temperature increases. But the insertion loss slightly increases with the temperature increased, the variation is about -0.02 dB/¢J.

The solidly mounted resonator (SMR) is constructed of a Bragg reflector and a piezoelectric layer AlN. In order to obtain an appropriate SMR for the high frequency communication applications and high sensitivity bio-sensor applications, the Bragg reflector, the AlN, and the loading effect have been investigated thoroughly. The thesis presents the influences of surface roughness of the Bragg reflector and materials¡¦ selection on the resonance characteristics of an SMR. Three combinations of thin films, AlN/Al, Mo/Ti, and Mo/SiO2, are adopted. Originally, an AlN/Al multi-layer is used as the Bragg reflector. The poor surface roughness of this Bragg reflector results in a poor SMR frequency response. To improve the surface roughness of Bragg reflectors, a Mo/Ti multi-layer with a similar coefficient of thermal expansion is adopted. By controlling deposition parameters, the surface roughness of the Bragg reflector is improved. Finally, a material combination of Mo/SiO2 with high acoustic impedance ratio of 4.7 is adopted. Better resonance characteristics of SMR are obtained. The experimental results show a distinct resonance phenomenon around 2.5 GHz and excellent noise restraint. Afterwards, a ¼£f mode SMR is experimentally realized. The selection of high and low acoustic impedance for the first layer beneath piezoelectric layer results in the ¼£f mode and ½ £f mode resonance configurations, respectively. The coupling coefficient Keff2 of 6.9% is obtained, which is in agreement with the theoretical analysis. Following, the theoretical analysis upon the dual mode frequency-shift was characterized, and a modified formula was carried out. The c-axis tilted angle of AlN was altered as well as the various mass loading on the SMR. Based on the experimental results, the dual resonance frequencies showed a nonlinear decreasing trend with a linear increase of the mass loading. Furthermore, the ratio of the longitudinal resonant frequency to the shear resonant frequency remained at a range around 1.76 despite the various c-axis tilted angles of AlN and gradual mass loading on the SMR. The electromechanical coupling coefficient, keff2, of the shear resonance rose with the increase of the c-axis tilted angle of AlN. However, the longitudinal resonance fades away with the AlN c-axis tilted angle, and the quality factor of the longitudinal resonance decreases. Finally, the dual mode resonances are improved by tilting the off-center substrates toward the sputtering source and successfully enhance the longitudinal resonance while preserve the shear resonance at the same time. Not only the shear resonance for the liquid-based sensing application, but also an outstanding longitudinal resonance could be obtained. The practicability of the dual-mode resonator is extended for the applications of high frequency wireless communication and high sensitivity bio-chemical sensors.

R??sum?? : INTRODUCTION : Il a ??t?? d??montr?? que la ventilation assist??e nasale (AIn) provoque la fermeture laryng??e active chez les agneaux nouveau-n??s sans s??dation. Ceci pourrait limiter la ventilation alv??olaire, entrainer l???air insuffl?? dans l???appareil digestif et provoquer des cons??quences d??l??t??res graves. Le neuro-asservissement de la ventilation assist??e nasale (NAVAn) et la ventilation nasale par oscillations ?? haute fr??quence (VOHFn) sont des modes de ventilation attractifs. La NAVA semble ??tre plus physiologique que l???AIn, car elle est synchronis??e avec le contr??le neural. Cependant, la VOHF ne n??cessite pas de synchronisation et diminue les l??sions pulmonaires provoqu??es par la ventilation m??canique conventionnelle. Le but de mon projet est d?????tudier l???effet de la NAVAn et de la VOHFn sur la dynamique laryng??e chez les agneaux nouveau-n??s sans s??dation, en testant l???hypoth??se que, contrairement ?? l???AIn, la fermeture laryng??e active n???apparait pas durant la NAVAn et la VOHFn. M??THODES : deux groupes d???agneaux n??s ?? terme (NAVAn : 8 agneaux ; et VOHFn : 7 agneaux) ont ??t?? instrument??s chirurgicalement ?? 2 jours de vie, afin de recueillir l?????lectromyogramme des muscles constricteur et dilatateur laryng??s, du diaphragme, les pressions au masque, trach??ale, pression de CO[indice inf??rieur 2] en fin d???expiration (P[indice inf??rieur ET]CO[indice inf??rieur 2]) et des gaz sanguins art??riels. 48h suivant l???instrumentation, un enregistrement polysomnographique a ??t?? r??alis?? pour chaque groupe (AIn / VOHFn et AIn / NAVAn) dans un ordre randomis??. La pression inspiratoire (AIn & NAVAn) et la puissance des oscillations (VOHFn) ont ??t?? progressivement augment??es. R??SULTATS : Les r??sultats d??montrent que l???augmentation des niveaux de NAVAn et de la puissance de VOHFn n???entraine pas de fermeture laryng??e active, contrairement ?? l???AIn. De plus, la diminution du PaCO[indice inf??rieur 2] provoqu??e par l???hyperventilation en AIn pourrait contribuer ?? la fermeture laryng??e active. En VOHFn, la diminution progressive de la fr??quence des oscillations jusqu????? 4 Hz induit des apn??es centrales. En revanche, aucune fermeture laryng??e active n???a ??t?? observ??e ?? 4 Hz. CONCLUSION : La NAVAn et la VOHFn ne provoquent pas la fermeture laryng??e active chez l???agneau nouveau-n??, et pourraient constituer des nouvelles alternatives dans le traitement des pathologies respiratoires en p??riode n??onatale. //Abstract : INTRODUCTION : We have previously shown that nasal pressure support ventilation (nPSV) can lead to an active laryngeal closure in non-sedated newborn lambs. This, in turn, can limit lung ventilation and divert air into the digestive system, with potentially deleterious consequences. Nasal neurally adjusted ventilator assist (nNAVA) and nasal high frequency oscillatory ventilation (nHFOV) are new attractive non-invasive ventilation modalities in newborns. Neurally adjusted ventilator assist (NAVA) seems to be a more physiological ventilator mode than PSV: it is more synchronized with neural control. However, HFOV is associated with less lung injury and does not require synchronization. Thus, the aim of the present study was to assess the effects of nNAVA and nHFOV on laryngeal dynamics in non-sedated newborn lambs, testing the hypothesis that active laryngeal closure does not develop during both nHFOV and nNAVA. METHODS : Polysomnographic recordings were performed in two groups of non-sedated chronically instrumented lambs (nHFOV, 7 lambs) and (nNAVA, 8 lambs), which were ventilated with progressively increased levels of nPSV and nHFOV or nNAVA, in random order. States of alertness, diaphragm and glottal muscle electrical activity, mask and tracheal pressure, tracheal end tidal CO[subscript 2] (P[subscript ET]CO[subscript 2]) and blood gases were continuously recorded in each group. RESULTS: While active laryngeal closure appeared with increasing levels of nPSV, it was never observed at any nHFOV power or nNAVA levels in any lamb. In addition, a decrease in PaCO[subscript 2] was neither necessary nor sufficient for the development of active laryngeal closure. nHFOV at 4Hz dramatically inhibited central respiratory drive. However, no active laryngeal closure was observed at 4 Hz. CONCLUSION: nHFOV and nNAVA does not induce active laryngeal closure in inspiration in non-sedated newborn lambs, in contrast to nPSV. nNAVA and nHFOV could be an alternatives in the treatment of neonatal respiratory disorders.

Over the past several years, rapid advances in the field of integrated photonics coupled with nanofabrication capabilities have enabled studies of the interaction of light with the mechanics of a variety of physical structures. Concurrently, mechanical resonators have been extensively studied in the MEMS community due to their high quality factors, and have been implemented in a variety of RF filters and oscillators. The combination of MEMS with integrated optomechanical structures can generate a variety of novel devices that can be used for applications in RF-Photonics, timing and optical switching. While there are several demonstrations of electrostatic devices integrated with optomechanical structures, fewer examples exist in the piezoelectric domain. In particular, photonic integration in a piezoelectric material can benefit from some of the traditional strengths associated with this type of actuation, such as the ability to easily scale to higher frequencies of operation by patterning lateral features, the ability to interface with 50Ω electronics and strong electromechanical coupling. In addition, it enables a platform to produce new architectures for photonic-based electronic frequency reference oscillators that incorporate multiple degrees of freedom. This thesis presents the development of a piezoelectrically-actuated acousto-optic modulator in the aluminum nitride (AlN) material system. The process of implementing this device is carried out in five principal stages. First, light coupling from optical fibers to the AlN thin film is demonstrated with the use of on-chip grating couplers, exhibiting a peak insertion loss of -6.6 dB and a high 1 dB bandwidth of 60 nm for operation in the telecommunications C- and L-bands. This is followed by characterization of photonic whispering gallery mode microdisk and microring resonators with optical quality factors on the order of 104. Next, a robust fabrication method combining optical and electron-beam lithography is developed to produce a fully-integrated device preserving the critical features for acoustic and photonic resonators to be colocalized in the same platform. Acousto-optic modulation is demonstrated with the use of a contour mode resonator which drives displacements in the photonic resonator at 653 MHz, corresponding to the mechanical resonance of the composite structure. The modulator is then implemented in an opto-acoustic oscillator loop, for which an initial phase noise of -72 dBc/Hz at 10 kHz offset from the carrier is recorded with a large contribution from thermal noise at the photodetector. Finally, some possibilities to improve the modulator efficiency and oscillator phase noise are provided along with prospects for future work in this area.

Les ondes acoustiques, démontrées théoriquement en 1885 par le scientifique anglais Lord Rayleigh, constituent de nos jours un sujet de recherches très intéressant. Elles sont devenues indispensables à la fabrication des systèmes de télécommunication miniatures et performants, tels que par exemple les filtres, les oscillateurs ou encore les capteurs. Les dispositifs fonctionnant grâce aux ondes acoustiques sont connus sous le nom de « dispositifs piézoélectriques » puisqu’ils transforment les signaux RF en ondes acoustiques, et vice versa, grâce au phénomène piézoélectrique direct. Le développement de ces dispositifs piézoélectriques a été indispensable pour répondre aux exigences particulières et extrêmes des systèmes de télécommunication actuels (sélectivité, miniaturisation, faible coût, facilité de fabrication et d’intégration). Cette thèse s’inscrit dans une démarche générale de développement des dispositifs piézoélectriques, notamment des micro-résonateurs piézoélectriques qui en constituent la dernière génération. Deux axes principaux ont été développés au cours de ces travaux de recherches : l’étude théorique des micro-résonateurs piézoélectriques à travers une modélisation électrique d’une part, et, d’autre part, la description des procédés de fabrication réalisés en salle blanche du laboratoire d’XLIM. / The acoustic waves, theoretically demonstrated in 1885 by the English scientist Lord Rayleigh, are nowadays an interesting research subject. It became essential to the fabrication of miniature and efficient systems of telecommunication, such as filters, oscillators or sensors. Devices using the acoustic waves are known as piezoelectric devices, because they transform RF signal into acoustic waves, and vice versa, thanks to the direct piezoelectric phenomenon. The development of these piezoelectric devices was essential to meet the particular and extreme requirements of the current systems of telecommunication (selectivity, miniaturization, low cost, ease of manufacturing and integration). This thesis is part of a global approach to develop the piezoelectric devices, notably the piezoelectric micro-resonators which constitute the latest generation. Two main axes have been developed during the research work: the theoretical study of piezoelectric micro-resonators through an electric modelling, on one hand, and, on the other hand, the description of the manufacturing processes accomplished in clean room of XLIM’s laboratory.

This paper compares two approaches for deriving subsumption algorithms for the description logic ALN: structural subsumption and an automata-theoretic characterization of subsumption. It turns out that structural subsumption algorithms can be seen as special implementations of the automata-theoretic characterization.

Aus der Einleitung: „In this paper, we reuse the representation formalism `description graph' in order to characterize subsumption of ALN-concepts. The description logic ALN allows for conjunction, valuerestrictions, number restrictions, and primitive negation. Since Classic allows for more constructors than ALN, e.g., equality restrictions an attribute chains by the constructor SAME-AS,we can confine the notion of description graphs from [BP94]. On the other hand, ALN explicitly allows for primitive negation which yields another possibility { besides conflicting number restrictions { to express inconsistency. Thus, we have to modify the notion of canonical description graphs in order to cope with inconsistent concepts in the structural characterization of subsumption. It turns out that the description graphs obtained from ALN-concepts are in fact trees. A canonical graph is a deterministic tree. The conditions required by the structural characterization of subsumption on these trees can be tested by an eficient algorithm, i.e., we obtain an algorithm deciding subsumption of C and D in time polynomial in the size of C and D. The report is structured as follows. In the preliminaries, we define syntax and semantics of the description logic ALN as well as the inference problem of subsumption. In Section 3, we introduce description graphs, the data structure our structural subsumption algorithm is working on. Besides syntax and semantics also an algorithm for translating ALN-concepts into description graphs is given. Thereafter, we present the main result of this report in Section 6, a characterization of subsumption of ALN-concepts by a structural comparison of corresponding description graphs. Furthermore, a structural subsumption algorithm can be found in Section 6.2. In the last section we summarize our results and give an outlook to further applications of structural subsumption in terminological knowledge representation systems.

Aus der Einleitung: „Equational unification is a generalization of syntactic unification in which semantic properties of function symbols are taken into account. For example, assume that the function symbol '+' is known to be commutative. Given the unication problem x + y ≐ a + b (where x and y are variables, and a and b are constants), an algorithm for syntactic unification would return the substitution {x ↦ a; y ↦ b} as the only (and most general) unifier: to make x + y and a + b syntactically equal, one must replace the variable x by a and y by b. However, commutativity of '+' implies that {x ↦ b; y ↦ b} also is a unifier in the sense that the terms obtained by its application, namely b + a and a + b, are equal modulo commutativity of '+'. More generally, equational unification is concerned with the problem of how to make terms equal modulo a given equational theory, which specifies semantic properties of the function symbols that occur in the terms to be unified.”