In this research, selective and bottom-up manufacturing of silica nanowires on silicon (Si) and its applications has been investigated. Localized synthesis of these nanowires on Si was achieved by metal thin film catalysis and metal ion implantation based seeding approach. The growth mechanism of the nanowires followed a vapor-liquid-solid (VLS) mechanism. Mass manufacturing aspects such as growth rate, re-usability of the substrate and experimental growth model were also investigated. Further, silica nanowires were explored as surface enhanced Raman (SER) substrate and immunoassay templates towards optical and electrochemical detection of cancer biomarkers respectively. Investigating their use in photonic applications, optically active silica nanowires were synthesized by erbium implantation after nanowire growth and implantation of erbium as a metal catalyst in Si to seed the nanowires. Ion implantation of Pd in Si and subsequent annealing in Ar at 1100° C for 60 mins in an open tube furnace resulted in silica nanowires of diameters ranging from 15 to 90 nm. Similarly, Pt was sputtered on to Si and further annealed to obtain silica nanowires of diameters ranging from 50 to 500 nm. Transmission electron microscopy studies revealed the amorphous nature of the wires. In addition, nano-sized Pd catalyst was found along the body of the nanowires seeded by Pd implantation into Si. After functionalization of the wires with 3-AminoPropylTriMethoxySilane (APTMS), the Pd decorated silica nanowires served as an SER substrate exhibiting a sensitivity of 107 towards the detection of interleukin-10 (IL-10, a cancer biomarker) with higher spatial resolution. Voltammetric detection of IL-10 involved silica nanowires synthesized by Pd thin film catalysis on Si as an immunoassay template. Using the electrochemical scheme, the presence of IL-10 was detected down to 1fg/mL in ideal pure solution and 1 pg/mL in clinically relevant samples. Time resolved photoluminescence (PL) results from the Er doped silica nanowires indicate a sharp emission around 1.54 µm representative of the I13/2 to I15/2 transition in Erbium. Also, a five-fold increase in the PL intensity and 30% augment in luminescence life time have been observed in nanowires when compared to fused silica sample prepared under similar conditions. The experimental results indicate the potential of silica nanowires in a wide variety of applications such as the development of orthogonal biosensors, fabrication of metallic nanowires, and environmental sensing probes.

In this research, novel high resolution reinforced diaphragm MEMS piezoresistive pressure sensors were designed, fabricated and tested to measure physical phenomena (such as depth/pressure variations) in the ocean. To complement the physical sensing elements, a microfluidic electrochemical nitrate sensor, was also developed to detect chemical fluxes. The electrochemical sensor was designed and packaged to conform to a flow through system. The multisensor approach will enable better measurement quality compared to the current ocean sensors. This, in turn, will potentially improve the current understanding of physical and biogeochemical processes from coastal to deep-sea environment. The pressure sensor element utilized a reinforced bulk micromachined diaphragm to achieve both higher sensitivity (27% higher, model data) and wider linear pressure operating range (> 400 psi, from combination of inner and outer bridge) compared to the conventional single diaphragm design. A temperature compensation bridge was incorporated on the sensor die to account for temperature drifts. A two-level packaging (wafer and system-level) scheme with protective coatings were developed to test the sensor in "simulated" ocean conditions. Finally, the reinforced diaphragm edge and the bossed structures were designed and fabricated using the masked-maskless etching process and their sensor performance were evaluated against the single diaphragm design. A nanowire-based Electrochemical detection-on-Chip (EoC) system was also developed to detect chemical/biological markers, especially nitrate fluxes. Different sensing modalities,involving a variety of nanosensor electrodes and different assembly techniques were investigated for suitability as electrochemical nitrate sensor. These architectures were also evaluated for robustness as a sensing platform. Enzyme-modified Au nanowires based electrochemical sensor showed excellent sensitivity (µM level) to biomarkers (cholesterol) in biological fluids (blood).These sensors, however, exhibited poor detection limits towards nitrate ions. Doped polypyrrole nanowire electrodes proved to be effective as nitrate sensors. A detection limit of 4.5±1 µM,sensitivity of 1.65 nAµM and stability of <15% variation from interfering ions were achieved on testing in a flow through environment. The nitrate sensor performance was at par with the current state of the art. Additionally, these sensors are batch fabricated (as arrays) reducing cost, require smaller sample volume, lesser space, power and are less prone to contamination problems.

Dans les technologies CMOS avancées, les défauts microscopiques localisées à l'interface Si (Nit) ou dans l'oxyde de grille (Nox) dégradent les performances des transistors CMOS, en augmentant le bruit de basse fréquence (LFN). Ces défauts sont généralement induits par le processus de fabrication ou par le vieillissement de l'appareil sous tension électrique (BTI, porteurs chauds). Dans des transistors canal SiGe ou III-V, leur densité est beaucoup plus élevé que dans le silicium et leur nature microscopique est encore inconnue. En outre, en sub 10 nm 3D comme nanofils, ces défauts répartis spatialement induisent des effets stochastiques typiques responsables de la "variabilité temporelle" de la performance de l'appareil. Cette nouvelle composante dynamique de la variabilité doit maintenant être envisagée en plus de la variabilité statique bien connu pour obtenir circuits fonctionnels et fiables. Aujourd'hui donc, il devient essentiel de bien comprendre les mécanismes de piégeage induites par ces défauts afin de concevoir et fabriquer des technologies CMOS robustes et fiables pour les nœuds de sub 10 nm. / In advanced CMOS technologies, microscopic defects localized at the Si interface (Nit) or within the gate oxide (Nox) degrade the performance of CMOS transistors, by increasing the low frequency noise (LFN). These defects are generally induced by the fabrication process or by the ageing of the device under electrical stress (BTI, Hot Carriers). In SiGe or III-V channel transistors, their density is much higher than in silicon and their microscopic nature still is unknown. In addition, in sub 10nm 3D like nanowires, these spatially distributed defects induce typical stochastic effects responsible for “temporal variability” of the device performance. This new dynamic variability component must now be considered in addition of the well-known static variability to obtain functional and reliable circuits. Therefore today it becomes essential to well understand the trapping mechanisms induced by these defects in order to design & fabricate robust and reliable CMOS technologies for sub 10nm nodes.

One-dimensional (1D) nanomaterial self-assembly offers an excellent approach to the fabrication of highly complex nanodevices. Despite considerable effort and research, precisely controlling the orientation and positioning of nanowires (NWs) on a large-scale area and assembling into a functional device is still a state of the art problem. This thesis focuses on the dimensionally controlled copper nanowires (Cu NWs) synthesis, and magnetic field assisted self-assembly of cupronickel nanowires (Cu/Ni NWs) into interconnect structures on a carbon doped silicon dioxide (CDO) wafer. CDO is a low dielectric constant (k) material used for copper interconnects in multilayered complex integrated circuits (ICs). Here, a strong affinity of copper (Cu) and nickel (Ni) to thiol (-SH) functional groups were exploited to strongly adhere the nanowires (Cu/Ni NWs) onto the CDO substrate. Thiol (-SH) functionalization of the CDO surface was achieved via a series of reactions involving (1) esterification of the surface exposed ≡Si-OH functional group to its triflate (≡Si-O-Tf), (2) reduction of triflate to ≡Si-H using DIBAL-H, and (3) hydrosilylation of ≡Si-H using 2-propene thiol (≡Si-(CH2)3-SH) in a photochemical reaction. The thiol functionalization of CDO surface enhances the interaction of Cu/Ni NWs with strong chemical bonds. The same reaction scheme was also used in the functionalization of the hydrophilic (Si-OH) surface to the hydrophobic long alkyl chain derivatized (≡Si-CH2-(CH2)16-CH3) surface. This long alkyl chain modified surface acts as an excellent moisture resistant film, which helps to maintain the low-k value of CDO. The dimensionally controlled Cu NWs were synthesized by a wet chemical approach. Optimization of the reducing agent, hydrazine (N2H4), controlled the surface morphology of nanowires (NWs). Interestingly, the high concentration of reducing agent produced particle decorated and/or with a rough NW surface, and conversely decreasing its concentration resulted in a comparatively thin, particle-free and smooth surface. The reaction temperature affected the aspect ratio (Length/Diameter) of the NWs. As the reaction temperature increased from 60 to 90 °C, the aspect ratio decreased from 140 to 21. Controlling the orientation of Cu NWs in a magnetic field was accomplished by coating them with a thin layer (~20 nm) of ferromagnetic nickel (Ni). This Ni-coated NWs showed an excellent degree of alignment (half-width ≈10 degrees) in the direction of an applied magnetic field over a large surface area at field strength as low as 2500 Gauss. Also, the Ni coating helped in protecting the copper core from oxidation resulting in better electrical wire-to-wire contacts. A nanowire-based interconnect channel was fabricated by combining magnetic field assisted alignment and deposition of aligned NWs on a thiol-modified and photolithography patterned CDO substrate. The NWs, deposited in the trenches, strongly bonded to the thiol-derivatized CDO substrate while an acetone wash removed loosely bound NWs on the photoresist surface. In electrical characterization, the directionally well-aligned Cu/Ni NWs channel displayed surprisingly two-fold higher conductivity than randomly arranged NWs channel.

Nanostructures were formed on diced specimens of several silicon carbide polytypes and silicon using electron beam lithography. A general introduction to nanostructure synthesis and electron beam lithography,are presented. A scanning electron microscope was retrofitted with a commercially available electron beam lithography package and an electrostatic beam blanker to permit nanoscale lithography to be performed. A process was first developed and optimized on silicon substrates to expose, poly-methyl-methacrylate (PMMA) resist with an electron beam to make nanoscale nickel masks for reactive ion etching. The masks consist of an array of nickel dots that range in size from 20 to 100 nm in diameter. Several nanoscale structures were then fabricated in silicon carbide using electron beam lithography. The structures produced are characterized by field emission Scanning Electron Microscopy.

Ce travail de thèse est issu d’une collaboration entre les laboratoires de recherche FEMTO-ST de l’université technologique de Belfort-Montbéliard et IRCELYON de l’université Claude Bernard à Villeurbanne. Les objectifs de cette étude portent sur la faisabilité d’élaborer par pulvérisation cathodique magnétron des films minces de cobaltite de lanthane nanostructurés. En effet, ces films présentent des propriétés catalytiques intéressantes pour l’oxydation des composés organiques volatiles comme le propène (C3H6) ou le monoxyde de carbone (CO) qui constituent la principale source de pollution de l’air. Il sera montré dans un premier temps que les cobaltites de lanthane de formule LaCoO3 ne sont pas efficaces pour ce type d’application. La composition chimique de ce matériau sera donc modifiée en y incorporant de l’argent de manière à faire varier les propriétés physico-chimiques des films et d’augmenter leurs performances catalytiques. La morphologie des films est directement impactée par l’introduction de Ag puisqu’elle évolue d’un système dense à un système « nanofilaire ». Une autre série de dépôts sera également élaborée et testée en catalyse constituée de cobaltites de lanthane dopées avec de l’argent mais aussi du cérium. On retiendra alors que les films de LaCoO3 + Ag sont plutôt efficaces et prometteurs puisqu’ils présentent des performances catalytiques se rapprochant de celles du platine (catalyseur de référence). Néanmoins, bien que les films aient toujours cette morphologie nanofilaire, les compositions chimiques des films élaborés à base de LaCoO3 + Ag + Ce doivent être optimisées afin d’augmenter leurs activités catalytiques. / This work was made in the frame of a scientific research relationships between the laboratory FEMTO-ST of the Technological University of Belfort-Montbéliard and the laboratory IRCELYON of the Claude Bernard University of Villeurbanne. This study aims at characterizing the feasibility of nanostructured lanthanum cobaltite thin films via magnetron sputtering. Indeed, it is well known these materials have interesting catalytic properties regarding the oxidation of volatile organic compounds such as propene (C3H6) or carbon monoxide (CO), the latter being the main source of air pollution. First, it has been shown that lanthanum cobaltites of formula LaCoO3 are not efficient for this type of application. The chemical composition of this material was then modified by incorporating silver so as to vary the physicochemical properties of the films and increase their catalytic performance. In consequence, the morphology of the films was directly impacted by the introduction of Ag since it evolved from a dense system to a "nanowire" system. Another series of deposits based on cobaltite modified by both silver and cerium additions have been also developed and tested during catalytic tests. It should be noted that the Ag containing thin films of LaCoO3 are rather efficient and then promising since they have catalytic performances close to those of platinum (the reference catalyst). Concerning the Ag and Ce containing perovskite films, although they still have this peculiar nanowired morphology, their chemical compositions have to be optimized in order to increase their catalytic activities.

A liga de FeRh apresenta uma transição de fase magneto-estrutural de primeira ordem próxima da temperatura ambiente, fazendo deste material um forte candidato para aplicações de gravação magnética termicamente assistida ou em refrigeradores magnéticos. Em baixas temperaturas o FeRh apresenta uma fase antiferromagnética enquanto em altas temperaturas apresenta uma fase ferromagnética. Cientes disto, neste trabalho foram analisados as transições de fase de filmes de FeRh, porém quando na presença de nanofios de Ni. Para isso foram fabricados filmes de FeRh, próximos da composição equiatômica, sobre uma matriz nanoporosa de Al 2 O 3 com nanofios de Ni. A matriz nanoposora foi produzida por um processo de anodização em dois passos, sendo preenchido os poros com Ni via eletrodeposição. O filme de FeRh foi crescido por deposição via magnetron sputtering, em duas temperaturas distintas, 525 e 600 o C. Um tratamento térmico in situ a 600 o C, por uma hora, foi feito no filme depositado na mesma temperatura. Curvas de magnetização em função de campo magnético aplicado, em temperaturas fixas, mostraram comportamentos característicos de filmes ou nanofios quando medidos nas direções preferenciais de cada componente, respectivamente, sugerindo um forte acoplamento via magnetoestrição entre os elementos. Foi analisada a dependência da transição de fase com relação a condições de magnetização dos nanofios de Ni, sendo observado clara dependência do comportamento da transição de fase com relação à estas condições. A transição de fase do FeRh é dada por nucleações e, posteriormente, por um deslocamento das paredes de domínio adjacentes a nucleação. Este comportamento é bem descrito pela somatória de duas distribuições gaussianas, sendo ajustadas na primeira derivada da magnetização em função da temperatura. Estes ajustes mostraram um claro comportamento da distribuição de nucleação com relação a magnetização remanente dos nanofios. Tal comportamento não tinha sido relatado até este momento. O filme depositado em 525 o C se mostrou mais suscetível a magnetização remanente dos nanofios do que o filme depositado em 600 o C. Posteriormente, medidas de transição de fase sob campo magnético intenso mostraram uma forte relação entre as temperaturas críticas de transição e a intensidade de campo aplicado, sendo deslocada a curva de transição para temperaturas mais baixas devido o incremento do campo. O filme depositado em 525 o C apresentou uma transição mais larga e uma menor magnetização em altas temperaturas do que o filme depositado em 600 o C. / The FeRh alloy presents a first order magnetic-structural phase transition close the room temperature, making this material a strong candidate to heat-assisted magnetic recording or magnetic refrigerators. At low temperaturas the FeRh the FeRh shows a antiferromagnetic phase while at high temperatures shows a ferromagnetic phase. Aware of this, in this work were analyzed the FeRh films phase transition, but under the Ni nanowires presence. For this were maked FeRh films, close the equiatomic composition, over a nanoporous matrix of Al 2 O 3 with Ni nanowires. The nanoporou matrix were produced by a two-step anodization process and the nanoporou fille with Ni via eletrodeposition. The FeRh film were grown by deposition via magnetron sputtering at two different temperatures, 525 e 600 o C. Annealing in situ at 600 o C for one hour was done in the film deposited at same temperature. Magnetization curves as function of applied magnetic field, at fixed temperatures, showed characteristic behaviors of the films or nanowires where measured in the preferential direction of each componente, respectively, suggest a strong magnetostriction coupling between elements. The phase transition dependence was analyzed with respect to magnetization conditions of Ni nanowires, been observed a clear dependence of the phase transition behavior with these conditions. The FeRh phase transition is given by nucleations and followed by a displacement of domain walls adjacents to the nucleation. This behavior is well defined for the sum of two gaussians distributions, been fitted to the first derivative of magnetization as function of temperature. These fittings showed a clear behavior of the nucleation distribution with repect to a nanowires remanent magnetization. Such behavior has never been reported before. The film deposited at 525 o C showed more susceptible to nanowires remanentc magnetization than film deposited at 600 o C. Subsequently meadures of phase transition under high magnetic fields showed a strong relation between the critical temperatures of depostion and the field intensity, being displaced to lower temperatures the transition curve with the field increment. The film deposited at 525 o C presented a broader transition with lower magnetization at high temperatures than film deposited at 600 o C.

This dissertation involves the study of epitaxial behavior of one-dimensional nanomaterials like single-walled carbon nanotubes and Indium Arsenide nanowires grown on metallic catalyst surfaces. It has been previously observed in our novel microplasma based CVD growth of SWCNTs on Ni-Fe bimetallic nanoparticles that changes in the metal catalyst composition was accompanied by variations in the average metal-metal bond lengths of the nanoparticle and that in turn, affected nanotube chirality distributions. In this dissertation, we have developed a very simplistic model of the metal catalyst in order to explain the nanotube growth of specific nanotube chiralities on various Ni-Fe catalyst surfaces. The metal catalyst model is a two-dimensional flat surface with varying metal-metal bond lengths and comprising of constituent metal atoms. The effect of the composition change was modeled as a change in the bond length of the model catalyst surface and density functional theory based calculations were used to study specific nanotube caps. Our results indicated that nanotube caps like (8,4) and (6,5) show enhanced binding with increased metal-metal bond lengths in the nanoparticle in excellent agreement with the experimental observations. Later, we used this epitaxial nucleation model and combined with a previously proposed chirality-dependent growth rate model to explore better catalysts that will preferentially grow an enhanced chirality distribution of metallic nanotubes. From our DFT calculations and other geometrical considerations for nanotube growth, we demonstrated that the pure Ni0.5Cu0.5 metal nanoparticles and its lattice-strained surfaces can serve as a promising catalyst for enhanced growth of metallic nanotubes. Finally, we extended this model of epitaxial growth to study the growth of,andoriented nanowires on gold metal nanoparticles where a faster growth rate ofnanowires was previously observed in experiments on shaped nanoparticles than that on spherical nanoparticles. The DFT calculations indicated an enhanced growth selectivity of theoriented nanowires on the Au(111) surfaces. However, the DFT results also show that theandNWs will preferentially grow on the Au(100) surface than on the Au(100) surface. The epitaxial model based DFT calculations of nanotube and nanowire growth on metal catalyst surfaces presented in this dissertation, provide a deep insight into their epitaxial growth mechansims and, can be easily exploited to layout better design principles of synthesizing catalysts that helps in growing these one-dimensional nanomaterials with desired material properties.

Nous avons étudié par diverses techniques de photoluminescence les propriétés optiques d'hétérostructures à base de composés III-N de structure wurtzite. Des expériences de photoluminescence résolues en polarisation nous ont permis de mettre en évidence l'influence des contraintes et du confinement sur la structure de bande d'une hétérostructure. L'étude de boites quantiques uniques GaN/AlN a pu être réalisée sur un système original : une boite quantique comme tranche d'un nanofil. Ce nouveau système nous a ainsi permis d'identifier les émissions de l'exciton et du biexciton. Nous avons également démontré le caractère d'émetteur de photon unique d'une boite quantique insérée dans un nanofil grâce à une expérience de corrélation de photon fonctionnant dans l'ultraviolet. Nous nous sommes également intéressés aux propriétés optiques de microdisques III-N et avons mesuré des facteurs de qualité atteignant 11000, ouvrant la porte à l'étude de l'effet Purcell dans ces structures. Finalement nous nous sommes penchés sur la dynamique des porteurs et du spin dans les hétérostructures GaN/AlN. Les boites quantiques se révèlent extrêmement efficaces pour éviter les recombinaisons non radiatives, les temps de déclin de la luminescence étant indépendants de la température même pour des boites présentant des déclins de l'ordre de la microseconde. Les boites quantiques semblent aussi être très efficientes pour supprimer les effets de diffusion sur le spin d'un exciton localisé. En effet des expériences d'alignement optique en pompage quasi résonnant nous ont permis de montrer que la polarisation induite était conservée sur la durée de vie de l'exciton et ce jusqu'à température ambiante.

This thesis studies the intrinsic disorder effects and the transport and magnetic properties of ring-shaped epitaxial thin films and superconducting tunnel junctions (STJs) of the high temperature superconductor YBa$_2$Cu$_3$O$_{7-delta}$. We used an unconventional contactless technique that allows us to directly measure the persistent current of superconducting rings. In order to study the disorder effects on the persistent current, we slowly increased oxygen vacancies in YBa$_2$Cu$_3$O$_{7-delta}$ by changing $delta$ from 0.03 to 0.55 in steps of $sim$0.021. Monitoring the corresponding changes in the temperature dependence of the persistent current revealed an anomaly in its flow within a certain range of disorder. We found that this anomaly is directly related to the occurrence of a spinodal decomposition of oxygen vacancies in YBCO, which we explain as a competition between two coexisting phases, oxygen rich and oxygen deficient. The analysis of the time dependence of the persistent current revealed that increasing oxygen vacancies transforms the vortex structure from quasi-lattice into a glass and subsequently into a pinned liquid phase. Our results also exhibited the first evidence of self-organization of the vortex structure with increasing disorder. We also performed the first direct measurement of the temperature dependence of the $c$-axis persistent current ($J_c$) that is purely due to tunnelling Cooper-pairs through intrinsic Josephson junctions (IJJs) of YBCO. This is made possible by incorporating IJJs of YBCO into ring-shaped films. Then, we studied the temperature dependence of the persistent current of YBCO nanowires embedded in SrTiO$_3$-barrier integrated between two semi-ring-shaped YBCO thin films and systematically varied the nanowires length. Our observations revealed that $J_c$ has two different temperature dependences: a GL-dependence ($J_c propto (T_c - T)^{3/2}$) at low temperatures which we found the same in all studied samples, and another power law dependence ($J_c propto (T_c - T)^{alpha > 3/2}$) at high temperatures which turned out to depend on the length of the nanowires. We attribute the cross-over between these two temperature dependences to the depinning and the dissipative motion of vortices. These experimental approaches and findings not only provide new information, but more importantly open new avenues of investigating the transport and magnetic properties of superconducting films, junctions, and nanowires.