Magnetic sensors are widely used in the field of mineral, navigational, automotive, medical, industrial, military, and consumer electronics. Many magnetic sensors have been developed that are generated by specific laws or phenomena: such as search-coil, fluxgate, Hall Effect, anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR), magnetoelectric (ME), magnetodiode, magnetotransictor, fiber-optic, optical pump, superconducting quantum interference device (SQUID), etc. Each of these magnetic field sensors has their merits and application areas. For low power consumption (<10uW), quasi-static frequency (<10Hz) and high sensitivity (<nT) application, magnetoelectric laminate sensors offer the best potential capability and thus are the topic of my dissertation. Here, in this thesis, I have focused on designs and optimizations of magnetoelectric sensor units (i.e., sensors and circuit). To achieve my goals, I have developed some useful rules for ME sensor and detection circuit design. For ME sensor optimization, designs should consider both frequencies far away from resonance and at resonance. For the former one, both internal and external noise contribution must be considered, as one of them will limit practical applications. With regards to the internal noise sources, I have developed two design optimization methods, designated as ”'scale effect” and “ME array”. I showed that they have the ability to increase the magnetic field detection sensitivity, which was verified by experiments. With regard to external noise consideration, I have investigated how the fundamental extrinsic noise sources (temperature fluctuation, vibration, etc) affect ME laminate sensors. A concept of separating signal and noise modes into difference is put forward. Optimization with this concept in mind required us to redesign the internal structure of ME laminate sensors. At the resonant frequency, the ME voltage coefficient α_ME is the most important parameter. To enhance resonant gain in α_ME, I have developed a three phase laminate concept, which is based on increasing the effective mechanical factor Q while reducing the resonant frequency. A ME voltage coefficient of α_ME ~40V/cm.Oe has been achieved at resonance, which is about 2x higher than that of a conventional bending mode. Investigations of detection circuit optimization were also performed. Component selection strategies and a new charge topology were considered. Proper component values were required to optimize the charge detection scheme. It was also found, under some specific conditions to satisfy the circuit stability, that if the lowest required measurement frequency of the charge source was f1, then that it was not necessary to make the high corner frequency <i>f</i>_p of the charge amplifier lower than <i>f</i>₁: as doing so would decrease the system's signal-to-noise ratio (SNR). A high pass, high order filter placed behind the charge amplifier was found to increase the charge sensitivity, as it narrows the intrinsic noise bandwidth and decreases the output noise contribution, while only slightly affecting the signal's output amplitude. Prototype ME unit were also constructed, and their noise level simulated by Pspice. Experimental results showed that prototypes ME unit can reach their detection limit. In addition, a new magneto-electric coupling mechanism was also found, which had a giant ME effect. / Ph. D.

Afin de permettre de développer un modèle de mémoire non-volatile basée sur le transistor à nanotube de carbone à commande optique qui est utilisée dans des circuits électroniques neuromorphiques, il est nécessaire de comprendre les physiques électroniques et optoélectroniques des nanotubes de carbone, en particulier l’origine de l'effet mémoire que présente ces transistors. C’est dans ce contexte général que cette thèse s'intègre. Le travail est mené sur trois plans :• Caractériser électriquement et optoélectroniquement des structures de test des CNTFETs et des OG-CNTFETs.• Développer un modèle compact pour les contacts Schottky dans les transistors à nanotube de carbone de la façon auto-cohérente basé sur le diamètre et la nature du métal d’électrode en utilisant la méthode de la barrière effective avec les paramètres nécessaires calibrés.• Modéliser l'OG-CNTFET selon les régimes de fonctionnement, lecture, écriture, effacement ou programmation pour application à une mémoire non-volatile en intégrant le mécanisme de piégeage et dépiégeage à l’interface polymère/oxyde. / This PhD thesis presents a computationally efficient physics-based compact model for optically-gated carbon nanotube field effect transistors (OG-CNTFETs), especially in the non-volatile memory application. This model includes memory operations such as “read”, “write”, “erase” or “program”, and “reset” which are modeled using trapping and detrapping mechanisms at the polymer/oxide interface. The relaxation of the memory state is taken into account. Furthermore, the self-consistent modeling of Schottky barriers at contacts between the carbon nanotube channel and metal electrodes is integrated in this model applying the effective Schottky barrier method. The Schottky contact model can be included in CNTFET based devices for a typical biasing range of carbon nanotube transistors. This compact model is validated by the good agreement between simulation results and experimental data (I-V characteristics). In the non-volatile memory application, this model can fully reproduce device behaviors in transient simulations. A prediction study of the key technological parameter, the CNT diameter variety is established to expect its impact on the transistor performance, and more importantly, on the memory operation. In the other hand, this thesis presents a preliminary electric characterization (I-V) of CNTFETs and OG-CNTFETs for the device modeling database. A preliminary optoelectronic characterization method is proposed.

Afin de permettre le développement de modèles manipulables par les concepteurs, il est nécessaire de pouvoir comprendre le fonctionnement des nanotubes, en particulier le transport des électrons et leurs propriétés électroniques. C’est dans ce contexte général que cette thèse s’intègre. Le travail a été mené sur quatre plans : développement de modèles permettant la description des phénomènes physiques importants au niveau des dispositifs, expertise sur le fonctionnement des nano-composants permettant de dégager les ordres de grandeurs pertinents pour les dispositifs, les contraintes, la pertinence de quelques procédés de fabrication (reproductibilité, taux de défauts, collection de caractéristiques mesurées et développement éventuel d'expériences spécifiques, expertise et conception des circuits innovatifs pour l’électronique numérique avec ces nano-composants. / This PhD work presents a computationally efficient physics-based compact model for the Schottky barrier (SB) carbon nanotube field-effect transistor (CNTFET). This compact model includes a new analytical formulation of the channel charge, taking into account the influence of the source and drain SBs. Compact model simulation results (I–V characteristic and channel density of charge) as well as Monte Carlo simulation results, which are provided by a recent work, will be given and compared to each other and also to experimental data to validate the used approximations. Good agreement is observed over a large range of gate and drain biases. Furthermore, a scaling study is presented to examine the impact of technological parameters on the device figure of merit. Then, for the assessment of the SB on circuit performances, traditional logical circuits are designed using the SB-CNTFET compact model, and results are compared with a conventional CNTFET with zero-SB height. Finally, exploiting the particular properties of SB-CNTFETs, a three-valued static memory that is suitable for high density integration is presented.