Ces travaux de thèse portent sur l’étude d’un générateur de nanoparticules (NPs) en phase gazeuse basé sur la pulvérisation cathodique magnétron. La mise en oeuvre d’un spectromètre d’émission optique et d’une microbalance à quartz a permis d’observer l’influence des paramètres du procédé (nature et débit des gaz, courant cathodique, configuration magnétique) sur les espèces présentes dans le plasma et la vitesse de dépôt des NPs. Ceci a conduit à une meilleure compréhension du procédé et à l’établissement d’un point de fonctionnement. Des analyses par microscopique électronique en transmission (MET) ont mis en évidence des NPs d’argent cristallisées en vol dont la taille augmente (de 2,5 ± 0,5 nm à 5,2 ± 0,5 nm de diamètre) avec la longueur d’agrégation. L’association de cette source à un réacteur de pulvérisation magnétron conventionnelle a permis la synthèse de nanocomposites constitués de nanoparticules métalliques (Cu ou Ag) dans une matrice céramique diélectrique amorphe et transparente (nitrure ou oxyde d’aluminium). Un décalage de la Résonance Plasmon de Surface (RPS) vers le rouge a été observé avec l’augmentation de la permittivité de la matrice ainsi qu’un élargissement de la RPS avec la diminution de la taille des NPs. Enfin, les propriétés électriques des nanocomposites ont été étudiés au sein de capacités de type Métal/Isolant/Métal (MIM) permettant une modulation de la permittivité avec le taux de dopage en NPs d’argent (5% et 10% vol.). / This thesis is dedicated to the study of free nanoparticles (NPs) source based on magnetron sputtering. Setting up an optical emission spectrometer and a quartz microbalance allowed to observe the influence of the process parameters (gas composition and flow rate, cathodic current, magnetic configuration) on the plasma species and the NPs deposition rate. This lead to a better understanding of the process and the establishment of a process operating windows. Transmission Electron Microscopy (TEM) analysis revealed crystallized silver NPs whose size increased (from 2.5 ± 0.5 nm to 5.2 ± 0.5 nm in diameter) when the aggregation length increased. The free NPs source coupled to a conventional magnetron sputtering chamber allowed the deposition of nanocomposites thin films consisting of metallic NPs (Cu ou Ag) embedded in dielectric transparent amorphous matrix (aluminum nitride or oxide). A red shift of the Surface Plasmon Resonance (SPR) was observed with the increase of the matrix permittivity value. A broadening of the SPR with the decrease of the NPs size was also evidenced. Finally, the electrical properties of the nanocomposites have been studied by means of a Metal/Insulator/Metal capacitor pointing out a modulation of the permittivity with the silver NPs content (5% and 10% vol.).

Metal oxides have recently come under study thanks to their physical and electrical properties for different applications such as MOS devices, i.e. substituting the silicon oxide with a high-k material, or as MIM (Metal Insulator Metal) capacitors, to increase capacitance per unit area and circuit integration. One oxide of interest in this field is aluminum oxide since it features good electrical insulation and high dielectric constant. In-depth studies are presented here on the use of non-porous anodic Al2O3. Major physical and electrical parameters have been obtained, i.e. dielectric constant, stress, deformation, resistance, surface quality. Constant, low anodizing current density results in a denser oxide, with a thickness of around 100 nm. Performances such as capacitance, breakdown voltage, etc. can be improved when compared to other Al2O3 obtained by other methods. Results are also comparable to other high-k oxides. Fair performance is maintained for temperature raised up to 200°C, which opens new possible applications. Its mechanical and physical properties make it candidate in biological and MEMS devices. DNA re-association or hybridization is the underlining principle of DNA sensors. Different electrical Al structures protected by a thin anodic Al2O3 are tested. Interdigitated capacitors, the most promising electrical structure, were selected and process characterization performed. Three electrical extraction procedures are performed on the same device lying on a passivated silicon substrate: inter-electrodes capacitance, the self-resonance frequency, and the equivalent MOS capacitance between the short-circuited electrodes and the substrate. This study is the first of its kind to open the way for correlation studies and noise reduction techniques based on multiple electrical measurements of the same DNA hybridization event. The hybridization of concentrations as low as 50 pM target DNA has been successfully electrically detected using silver enhancement over gold nano-particles labeled DNA.

Una de las mayores limitaciones para lograr el rendimiento y la calidad deseada de los cultivos en la mayoría de los sistemas agronómicos del mundo es la presencia de malezas. Para mitigar su propagación e influencia, en los últimos años se comenzó a implementar el Manejo Integrado de Malezas (MIM), que pretende evitar los efectos negativos resultantes del uso exclusivo de herbicidas como único mecanismo de control al combinar diferentes técnicas de prevención y control que también incluyen rotaciones de cultivos, prácticas mecánicas y medidas culturales. Motivados por esta realidad, en esta tesis se planteó, primeramente, extender las prestaciones de un modelo de simulación desarrollado en el ámbito del grupo de investigación. El objetivo del mismo fue estimar los efectos de diferentes estrategias de manejo sobre la dinámica demográfica de una maleza anual (Avena fatua L.) en competencia con cereales de invierno (trigo y cebada) en un plan de rotación multianual, y proporcionar suficiente detalle agronómico, económico y medioambiental para orientar la toma de decisiones. Adicionalmente, con el propósito de explorar sistemáticamente la gran cantidad de posibles estrategias de MIM que se pueden representar con el modelo desarrollado e identificar automáticamente aquellas que resultan más prometedoras, se implementó un optimizador que proporciona un conjunto de soluciones en la frontera de los objetivos de desempeño considerados. Este se basó en un algoritmo estocástico no-lineal por enjambre de partículas (PSO), al que se le incorporaron técnicas para el manejo de restricciones, de manipulación de variables binarias y de consideración de objetivos múltiples. Así, el optimizador desarrollado permite identificar los mejores esquemas de rotación de cultivos y de tratamientos para controlar la maleza teniendo en cuenta, simultáneamente, el beneficio económico y el impacto ambiental. La herramienta desarrollada se considera de potencial utilidad para guiar el complejo proceso de toma de decisiones de la actividad agrícola. / One of the greatest limitations to achieve the desired yields and quality of crops in most agronomic systems around the world is the presence of weeds. To prevent their spread and influence, in recent years Integrated Weed Management (IWM) practices began to be implemented, which aims at avoiding the negative effects of the sole use of herbicides as control mechanism by combining different prevention and control techniques that also include rotations, mechanical practices and cultural measures. Motivated by this reality, in this thesis it was firstly proposed to extend the features of a simulation model developed in our research group. It aimed at estimating the effects of different management strategies on the demographic dynamics of an annual weed (Avena fatua L.) in competition with winter cereals (wheat and barley) in a multi-year rotation plan, providing sufficient agronomic, economic and environmental detail to guide decision making. Additionally, in order to systematically explore the large number of possible IWM strategies that can be represented with the developed model and automatically identify the most promising ones, an optimizer that provides a set of solutions on the frontier of the considered performance objectives was implemented. It was based on a non-linear stochastic particle swarm algorithm (PSO), enhanced with techniques for constraint management, binary variables handling and multiple objectives consideration. In this way, the developed optimizer allows identifying the best crop rotation and treatment schemes for weeds control, simultaneously considering the economic benefit and the environmental impact. The developed tool is considered of potential utility to guide the complex decisionmaking process of the agricultural activity.

The motivation of this study is based on integrated passive filter dielectric thin films with thin layers. Reducing the area of integrated passive filter in a circuit by enhancing dielectric constant with same capacitance and thickness is the purpose which has been expected. To fabricate the thin film MIM structure capacitors, RF magnetron sputtering method was selected and BaNd2Ti5O14 composed materials treated as the target to grow the thin film dielectric layer in MIM structure capacitors. In this study the MIM structure capacitors were deposited on alumina substrates with Pt electrodes. In the thin film experiments, various operation parameters of sputtering deposition and post thermal process at different temperature were used to perform the desired thin film dielectric layers. In order to obtain the optimal performance of the dielectric thin films, ¡§Taguchi Method¡¨ was used as a experimental tool. The primary investigation focused on the electric characteristics of the thin film capacitors in this article. In the arranged ranges of the parameters, the optimal dielectric thin films were deposited under RF power 100W with deposition temperatures at 400¢J, chamber pressure is 10mtorr. The dielectric constant of deposited thin films is 39.2 at 1MHz, the dissipation factor is 1.38¢H at 10kHz, leakage current is 2.61X10-7A/cm2 at 5V operating voltage and breakdown electric field of 0.29MV/cm is observed. The crystalline structures of deposited thin films were characterized by XRD and found amorphous structure. Film roughness was measured by Atomic Force Microscope (AFM) with 0.263 nm.

A Metal-Insulator-Metal (MIM) diode is a device that can achieve rectification at high frequencies. The main objective of this research work is designing, fabricating, and characterizing thin film MIM diodes with single and multi-insulator layers. 
Cr/Al₂O₃/Cr and Pt/Al₂O₃/Al MIM diodes have been fabricated to show the impact of the materials on the current-voltage (I-V) curve. It is illustrated that the Cr/Al₂O₃/Cr MIM diode has a symmetrical I-V curve while the Pt/Al₂O₃/Al MIM diode has a very asymmetrical I-V curve. 
MIM diodes with single and multi-insulator layers have been fabricated to demonstrate the impact of the number of insulators on a MIM diode’s performance. It is found that by repeating two insulator layers with different electron affinities and keeping the total insulator thickness the same, the asymmetry and nonlinearity values show a significant improvement in a MIM diode. While the asymmetry of the diode with a double insulator layer (MI²M) is 3, it is 90 for the diode with a quadra insulator layer (MI⁴M), which 30 times greater than that of the MI²M diode.

A Metal-Insulator-Metal (MIM) diode is a device that can achieve rectification at high frequencies. The main objective of this research work is designing, fabricating, and characterizing thin film MIM diodes with single and multi-insulator layers. 
Cr/Al₂O₃/Cr and Pt/Al₂O₃/Al MIM diodes have been fabricated to show the impact of the materials on the current-voltage (I-V) curve. It is illustrated that the Cr/Al₂O₃/Cr MIM diode has a symmetrical I-V curve while the Pt/Al₂O₃/Al MIM diode has a very asymmetrical I-V curve. 
MIM diodes with single and multi-insulator layers have been fabricated to demonstrate the impact of the number of insulators on a MIM diode’s performance. It is found that by repeating two insulator layers with different electron affinities and keeping the total insulator thickness the same, the asymmetry and nonlinearity values show a significant improvement in a MIM diode. While the asymmetry of the diode with a double insulator layer (MI²M) is 3, it is 90 for the diode with a quadra insulator layer (MI⁴M), which 30 times greater than that of the MI²M diode.

The objective of this thesis is to successfully design, fabricate, and characterize an optimum metal-insulator-metal diode that can be used as a fast switching diode in various applications such as solar energy conversion. The improvements of this type of diode will result in rectification of a wider spectrum of AC signals to usable electricity. In this project, several proposed designs of MIM diodes were successfully fabricated and characterized. Pt-Al2O3-Al metal-insulator-metal diode was fabricated to have high asymmetry in I-V curve. Additionally, in an attempt to study the effect of material properties on MIM diode???s performance, four different combinations of MIIIIM diode were compared and discussed. Many processes were involved in the fabrication of these diodes such as E-beam evaporation, photolithography, reactive ion etching RIE, and Atomic Layer Deposition (ALD) technique. The fabricated tunneling diodes are intended to operate in the GHz regime and can also operate at higher frequencies (THz) by changing and scaling the dimensions. In addition to MIM diode work, this project attempted to engineer the contrast curve of polystyrene as a negative resist used for E-beam lithography using multi layer resist stack. If the resist stack has a very high contrast and its sensitivity differs between the various layers, it can be ideal for the fabrication of multi-level zone-plate/Fresnel lens.

Metal Insulator Metal (MIM) diodes that work on fast mechanism of tunneling have been used in a number of very high frequency applications such as (Infra-Red) IR detectors and optical Rectennas for energy harvesting. Their ability to operate under zero bias condition as well as the possibility of realizing them through printing makes them attractive for (Radio Frequency) RF applications. However, MIM diodes have not been explored much for RF applications. One reason preventing their widespread RF use is the requirement of a very thin oxide layer essential for the tunneling operation that requires sophisticated nano-fabrication processes. Another issue is that the reliability and stable performance of MIM diodes is highly dependent on the surface roughness of the metallic electrodes. Finally, comprehensive RF characterization has not been performed for MIM diodes reported in the literature, particularly from the perspective of their integration with antennas as well as their rectification abilities. In this thesis, various metal deposition methods such as sputtering, electron beam evaporation, and Atomic Layer Deposition (ALD) are compared in pursuit of achieving low surface roughness. It is worth mentioning here that MIM diodes realized through ALD method have been presented for the first time in this thesis. Amorphous metal alloy have also been investigated in terms of their low surface roughness. Zinc-oxide has been investigated for its suitability as a thin dielectric layer for MIM diodes. Finally, comprehensive RF characterization of MIM diodes has been performed in two ways: 1) by standard S-parameter methods, and 2) by investigating their rectification ability under zero bias operation. It is concluded from the Atomic Force Microscopy (AFM) imaging that surface roughness as low as sub 1 nm can be achieved reliably from crystalline metals such as copper and platinum. This value is comparable to surface roughness achieved from amorphous alloys, which are non-crystalline structures and have orders of magnitude lower conductivities. Relatively lower resistances of the order of 1 k ohm with a sensitivity of 1.5 V-1 have been obtained through DC testing of these devices. Finally, RF characterization reveals that input impedances in the range of 300 Ω to 25 Ω can be achieved in the low GHz frequencies (from 1-10 GHz). From the rectification measurements at zero bias, a DC voltage of 4.7 mV has been obtained from an incoming RF signal of 0.4 W at 2.45 GHz, which indicates the suitability of these diodes for RF rectenna devices without providing any bias. It is believed that with further optimization, these devices can play an important role in RF energy harvesting without the need to bias them.

No description available.

A Metal-Insulator-Metal (MIM) diode is a high frequency device used for energy harvesting purpose in the RECTENNA. The main objective of this thesis work is to design, fabricate and characterize a thin-film MIM diode. A key issue associated in this research work is the development MIM diode with nanometer thin insulator region. The reason for the development of MIM diode is to rectify a wide spectrum of AC signal to usable DC power. In this thesis work, a planar MIM diode with Aluminum/Aluminum-Oxide/Gold has been fabricated. The thickness of the insulator region obtained was about 3nm. The Metal and insulator depositions were done by sputtering and plasma oxidation, respectively. I-V Characteristics of the diode was measured by making use of in-house set-up and 70% of the devices on a single wafer yielded with better result. Most of the I-V curves obtained were highly non-linear and asymmetric. Based on the I-V measurement, the logarithmic derivative of I vs. V was plotted and the tunneling behavior was also observed.