This Thesis concerns the development of fullerene-like (FL) carbon nitride (CNx) thin films and the discovery of phosphorus-carbide (CPx) compounds. The work dedicated to CPx include first-principles theoretical simulations of the growth and properties of FL-CPx structures. I have employed DC magnetron sputtering methods to synthesize both CNx and CPx thin films. The deposition conditions for CPx films were chosen on the basis of the theoretical results as well as from the experience from the deposition of FL-CNx thin films. The characterization of the CPx films is divided into three main directions: structural characterization by transmission electron microscopyand scanning electron microscopy, analysis of the amount of elements and chemical bonds presentin the structure by X-ray photoelectron spectroscopy and Auger spectroscopy, and mechanicalproperty analysis by nanoindentation. The CPx films exhibit a short range orderedstructure with FL characteristics for substrate temperature of 300 °C and for a phosphorus content of 10-15 at.%, which isconsistent with the theoretical findings. These films also displayed the best mechanical properties in terms of hardness and resiliency, which are better than those of the corresponding FL-CNx films. For the FL-CNx thin film material, I find that the surface water adsorption is lower compared to commercial computer hard disk top coatings. Following that line the dangling bonds in FL-CNx coatings have been investigated  by electron spin resonance (ESR). The absence of ESR signal for FL-CNx indicates very low density of dangling bonds in the material, which explains the low water adsorption tendency. The potential for using highly elastic FL-CNx coatings in an automotive valve-train environment has also been investigated. CNx coatings of different nitrogen content were investigated using microscopy, wear testing, nanoindentation testing, and in an experimental cam-tappet testing rig. The FL-CNx coating with the higher value of hardness/elastic modulus showed greater durability in cam-tappet wear testing.

Ag is a widely used electrical contact material due to its excellent electrical properties. The problems with Ag are that it is soft and has poor tribological properties (high friction and wear in Ag/Ag sliding contacts). For smart grid applications, friction and wear became increasingly important issues to be improved, due to much higher sliding frequency in the harsh operation environment. The aim of this thesis is to explore several different concepts to improve the properties of Ag electrical contacts for smart grid applications. Bulk Ag-X (X=Al, Sn In) alloys were synthesized by melting of metals. An important result was that the presence of a hcp phase in the alloys significantly reduced friction coefficients and wear rates compared to Ag. This was explained by a sliding-induced reorientation of easy-shearing planes in the hexagonal structure. The Ag-In system showed the best combination of properties for potential use in future contact applications.  This thesis has also demonstrated the strength of a combinatorial approach as a high-throughput method to rapidly screen Ag-based alloy coatings. It was also used for a rapid identification of optimal deposition parameters for reactive sputtering of a complex AgFeO2 oxide with narrow synthesis window. A new and rapid process was developed to grow low frictional AgI coatings and a novel designed microstructure of nanoporous Ag filled with AgI (n-porous Ag/AgI) using a solution chemical method was also explored. The AgI coatings exhibited low friction coefficient and acceptable contact resistance. However, under very harsh conditions, their lifetime is too short. The initial tribotests showed high friction coefficient of the n-porous Ag/AgI coating, indicating an issue regarding its mechanical integrity. The use of graphene as a solid lubricant in sliding electrical contacts was investigated as well. The results show that graphene is an excellent solid lubricant in Ag-based contacts. Furthermore, the lubricating effect was found to be dependent on chemical composition of the counter surface. As an alternative lubricant, graphene oxide is cheaper and easier to produce. Preliminary tests with graphene oxide showed a similar frictional behavior as graphene suggesting a potential use of this material as lubricant in Ag contacts.

Many physical properties, for example structural or magnetic, of a material are directly dependent on elemental composition. Tailoring of properties through highly accurate composition control is possible in thin films. This work exemplifies such tailoring. A short review is given of the current status for research in the area of permanent magnets, focusing on rare earth element free alternatives, where FeNi in the L10 phase is a possible candidate. Epitaxial FeNi L10 thin films were successfully synthesized by magnetron sputtering deposition of monoatomic layers of Fe and Ni on HF-etched Si(001) substrates with Cu or Cu100-xNix/Cu buffers. The in-plane lattice parameter aCuNi of the Cu100-xNix buffer layer was tuned by the Ni content. Through matching of aFeNi to aCuNi, the strain state (c/a)FeNi was controlled, where c is the out-of-plane lattice parameter. The 001 reflection indicative of chemical order, as measured by resonant x-ray diffraction, was in most cases split in two peaks due to a composition modulation of Fe and Ni. This chemical disorder contributed to that the uniaxial magnetocrystalline anisotropy energy, KU≈0.35 MJ/m3, was smaller than predicted. In later experiments the composition modulation could partly be compensated for. Remaining discrepancies with respect to predicted KU values were attributed to additional disorder induced by surface roughness of the buffer layer. The interface sharpness between Fe and Ni was explored by producing epitaxial symmetric multilayers with individual layer thicknesses n = 4-48 monolayers (ML). For n ≤ 8 ML the films had pure fcc structure, with antiferromagnetic Fe layers. For n ≥ 8 ML the Fe layers relaxed to bcc structure. A combinatorial sputter chamber, which has the capability to deposit samples with composition and thickness gradients, was assembled. A model for simulation of composition and thickness across large substrates, for the conditions in this chamber, is presented. The model is verified by comparison to experimental data. Some challenges inherent in combinatorial sputtering are discussed, and two experimental studies employing the technique are presented as examples. These investigated magnetic and structural properties of Tb-Co films, with 7-95 at.% Tb, and of amorphous and crystalline ternary gradient Co-Fe-Zr films, respectively.

This thesis describes the development of a fast rate method for the deposition of high quality CdS and CdTe thin films. The technique uses Pulsed DC Magnetron Sputtering (PDCMS). Surprisingly, the technique produces highly stable process conditions. CREST is the first laboratory worldwide to show that pulsed DC power may be used to deposit CdS and CdTe thin films. This is a very promising process technology with potential for eventual industrial deployment. The major advantage is that the process produces high deposition rates suitable for use in solar module manufacturing. These rates are over an order of magnitude faster than those obtained by RF sputtering. In common with other applications it has also been found that the energetics of the pulsed DC process produce excellent thin film properties and the power supply configuration avoids the need for complex matching circuits. Conventional deposition methodologies for CdS, Chemical Bath Deposition (CBD) and CdTe thin films, Electrodeposition (ED), have been chosen as baselines to compare film properties with Pulsed DC Magnetron Sputtering (PDCMS). One of the issues encountered with the deposition of CdS thin films (window layers) was the presence of pinholes. A Plasma cleaning process of FTO-coated glass prior to the deposition of the CdS/CdTe solar cell has been developed. It strongly modifies and activates the TCO surface, and improves the density and compactness of the deposited CdS thin film. This, in turn, improves the optical and morphological properties of the deposited CdS thin films, resulting in a higher refractive index. The pinhole removal and the increased density allows the use of a much thinner CdS layer, and this reduces absorption of blue spectrum photons and thereby increases the photocurrent and the efficiency of the thin film CdTe cell. Replacing the conventional magnetic stirrer with an ultrasonic probe in the chemical bath (sonoCBD) was found to result in CdS films with higher optical density, higher refractive index, pinhole and void-free, more compact and uniform along the surface and through the thickness of the deposited material. PDCMS at 150 kHz, 500 W, 2.5 μs, 2 s, results in a highly stable process with no plasma arcing. It allows close control of film thickness using time only. The CdS films exhibited a high level of texture in the <001> direction. The grain size was typically ~50 nm. Pinholes and voids could be avoided by reducing the working gas pressure using gas flows ii below 20 sccm. The deposition rate was measured to be 1.33 nm/s on a rotating substrate holder. The equivalent deposition rate for a static substrate is 8.66 nm/s, which is high and much faster than can be achieved using a chemical bath deposition or RF magnetron sputtering. The transmission of CdS can be improved by engineering the band gap of the CdS layer. It has been shown that by adding oxygen to the working gas pressure in an RF sputtering deposition process it is possible to deposit an oxygenated CdS (CdS:O) layer with an improved band gap. In this thesis, oxygenated CdS films for CdTe TF-PV applications have been successfully deposited by using pulsed DC magnetron sputtering. The process is highly stable using a pulse frequency of 150 kHz and a 2.5 μs pulse reverse time. No plasma arcing was detected. A range of CdS:O films were deposited by using O2 flows from 1 sccm to 10 sccm during the deposition process. The deposition rates achieved using pulsed DC magnetron sputtering with only 500 W of power to the magnetron target were in the range ~1.49 nm/s ~2.44 nm/s, depending on the oxygen flow rate used. The properties of CdS thin films deposited by pulsed DC magnetron sputtering and chemical bath deposition have been studied and compared. The pulsed DC magnetron sputtering process produced CdS thin films with the preferred hexagonal <001> oriented crystalline structure with a columnar grain growth, while sonoCBD deposited films were polycrystalline with a cubic structure and small grainy crystallites throughout the thickness of the films. Examination of the PDCMS deposited CdS films confirmed the increased grain size, increased density, and higher crystallinity compared to the sonoCBD CdS films. The deposition rate for CdS obtained using pulsed DC magnetron sputtering was 2.86 nm/s using only 500 W power on a six inch circular target compared to the much slower (0.027 nm/s) for the sonoChemical bath deposited layers. CdTe thin films were grown on CdS films prepared by sonoCBD and Pulsed DC magnetron sputtering. The results showed that the deposition technique used for the CdS layer affected the growth and properties of the CdTe film and also determined the deposition rate of CdTe, being 3 times faster on the sputtered CdS. PDCMS CdTe layers were deposited at ambient temperature, 500 W, 2.9 μs, 10 s, 150 kHz, with a thickness of approximately 2 μm on CdS/TEC10 coated glass. The layers appear iii uniform and smooth with a grain size less than 100 nm, highly compact with the morphology dominated by columnar grain growth. Stress analysis was performed on the CdTe layers deposited at room temperature using different gas flows. Magnetron sputtered thin films deposited under low gas pressure are often subject to compressive stress due to the high mobility of the atoms during the deposition process. A possible way to reduce the stress in the film is the post-deposition annealing treatment. As the lattice parameter increased; the stress in the film is relieved. Also, a changing the deposition substrate temperature had an effect on the microstructure of CdTe thin films. Increasing the deposition temperature increased the grain size, up to ~600 nm. CdTe thin films with low stress have been deposited on CdS/TEC10 coated glass by setting the deposition substrate temperature at ~200°C and using high argon flows ~ 70 sccm Ar. Finally, broadband multilayer ARCs using alternate high and low refractive index dielectric thin films have been developed to improve the light transmission into solar cell devices by reducing the reflection of the glass in the extended wavelength range utilised by thin-film CdTe devices. A four-layer multilayer stack has been designed and tested, which operates across the wavelength range used by thin-film CdTe PV devices (400 850 nm). Optical modelling predicts that the MAR coating reduces the WAR (400-850 nm) from the glass surface from 4.22% down to 1.22%. The application of the MAR coating on a thin-film CdTe solar cell increased the efficiency from 10.55% to 10.93% or by 0.38% in absolute terms. This is a useful 3.6% relative increase in efficiency. The increased light transmission leads to improvement of the short-circuit current density produced by the cell by 0.65 mA/cm2. The MAR sputtering process developed in this work is capable of scaling to an industrial level.

Mimicking nature gives rise to many important facets of biomaterials. This study is inspired by nature and reports on the fabrication of an intercalated polymer-NiTi nanocomposite that mimics the structural order of urethral tissue performing micturition. PTFE is chosen due to its hydrophobicity, low surface energy, and thermal and chemical stability. NiTi has been selected as a prime candidate for this research due to its excellent mechanical stability, corrosion resistance, energy absorbance, shape memory and biocompatibility. Nanoscale engineering of intercalated nanocomposites is done by PVD sputtering PTFE and NiTi. FTIR spectroscopy confirms that PTFE reforms as polymer chains after sputtering. Suitable PVD sputtering parameters were selected by investigating their influence on deposition rates, microstructure and properties of PTFE and NiTi thin films. PTFE forms stable nanocomposite coatings with NiTi and displays favourable surface interactions, known as ‘intercalation’. Intercalated PTFE-NiTi films were fabricated as layered and co-sputtered thin films. Co-sputtered nanocomposites contained nearly one-third vacant sites within its internal microstructure because of intercalation while intercalation introduced minute pits in fibrous NiTi columns of layered nanocomposites. These pits allow PTFE to extend their chains and crosslinks, resulting in microstructural and functional changes in the thin films. Intercalated PTFE-NiTi nanocomposites offer a close match to the natural tissue in terms of responding to the fluid contact (wetting angle modifications), and allow the soft and hard matter to incorporate in one framework without any chemical reactions (intercalation). An intercalated microstructure in co-sputtered and layered nanocomposites was verified by EDS-SEM and EDS-TEM techniques. The functional responses were witnessed by changes in water contact angle (WCA) and coefficient of friction (CoF) values measured on the film surface. The WCA (99°) and CoF (0.1 – 0.2) of the intercalated nanocomposite (sample PNT12) were different to the NiTi (top layer). WCA and CoF indicate the internal microstructural interactions because of intercalation. Although the pseudoelastic behaviour of NiTi can provide additional fluid response but the difficulty is an absence of crystallinity in as-deposited NiTi, and the heat treatment that melts PTFE. However, DSC and XRD techniques were employed to find the optimum NiTi composition and transition temperatures for phase transformation related to pseudoelasticity. This study provides the basis to incorporate the shape memory (pseudoelasticity or thermal shape memory effect (shape memory effect)) features of NiTi into the intercalated nanocomposite in future. The intercalated PTFE-NiTi nanocomposite reveals a fascinating research precinct, having the response generating characteristics similar to that of natural tissue.

Ce travail porte sur la préparation de couches minces et sur des dispositifs flexibles à base de CoSb₃ performant et à faible coût par pulvérisation cathodique pour des applications thermoélectriques. Dans un premier temps, La pulvérisation cathodique et la co-pulvérisation ainsi que le procédé de traitement thermique ont été étudiés et optimisés pour améliorer la microstructure et surtout les propriétés thermoélectriques de couches minces. Ces deux techniques de dépôt ont donné un facteur de puissance respectivement de 1,47 × 10-4 Wm-1K-2 et de 0,98 × 10-4 Wm-1K-2. Deuxièmement, Ag et Ti ont été utilisés pour doper les couches minces de CoSb3 via un dépôt par pulvérisation magnétron. La microstructure, la morphologie, la composition et les propriétés thermoélectriques des couches minces de CoSb3 dopés ou co-dopeés sont fortement dépendantes de la teneur de dopage. Une amélioration simultanée du coefficient de Seebeck et de la conductivité électrique grâce au dopage par Ag, a été obtenue, indiquant que Ag est un dopant efficace avec un facteur de puissance maximal de 2,97 × 10-4 Wm-1K-2, plusieurs fois celui de l'échantillon non dopé. Des résultats similaires peuvent être obtenus pour des couches minces dopées au Ti, avec une amélioration simultanée du coefficient de Seebeck et de la conductivité électrique. En particulier, la conductivité thermique de la couche mince a été considérablement réduite en contrôlant soigneusement la nanostructure et la teneur en dopage Ti par optimisation du procédé de dépôt, ce qui a entraîné une augmentation de la figure de mérite ZT de 0,15 à 0,90. Troisièmement, des études détaillées sur des couches minces de CoSb₃ co-dopées Ag/(Sn, Ti ou In) ont été réalisées. L'influence de la nature et de la concentration du co-dopant sur les propriétés des couches minces de CoSb₃ a été étudiée. Le coefficient de Seebeck et la conductivité électrique de toutes les couches minces co-dopées sont simultanément augmentés par rapport à la couche mince non dopée. Le facteur de puissance a été ainsi nettement augmentée et une valeur d'environ 0,32 mWm-1K-2 a été obtenue pour des couches minces co-dopées Ag/Sn. Le facteur de puissance maximal pour des couches co-dopées Ag/Ti et Ag/In est également proche d cette valeur. De plus, une faible conductivité thermique a aussi été obtenue pour ces couches co-dopées, en particulier avec le co-dopage Ag/In, conduisant à une valeur ZT beaucoup plus élevée que les autres couches minces. Enfin, un dispositif à base de nano-couches de CoSb₃ a été fabriqué et une structure des électrodes en multicouche a été mise au point afin d'améliorer la stabilité thermique du dispositif à l'air. Une tension de sortie supérieure à 90 mV et une densité de puissance élevée de 0,46 mWcm-2 peuvent être obtenues à partir du dispositif fabriqué. De plus, ce dispositif a également été testé en tant que capteur thermique et il présente une réponse rapide, avec un temps de réaction de quelques centaines de millisecondes avec une grande stabilité. Il a été également démontré la possibilité d'obtenir une tension de sortie relativement élevée d'environ 7 V avec une intensité de courant d'environ 0,35 mA grâce à ces dispositifs thermoélectriques à couches minces. Ces résultats permettent d'envisager des applications réelles, notamment pour alimenter des équipements électroniques/électriques portatifs. / This work was focused on the preparation of low-cost and high performance CoSb₃ thin films by magnetron sputtering deposition, and on the preparation of efficient flexible thin film devices based on CoSb₃ thin films for thermoelectric application. Firstly, two methods, co-sputtering and single target sputtering, for preparing CoSb₃ thin films by using magnetron sputtering deposition were studied and the heat-treatment process was optimized for the improvement of the micro-structure and thermoelectric properties of the films. Thin films prepared by co-sputtering method or using a single alloy target deposition method have a maximum power factor value of 1.47 × 10-4 Wm-1K-2 and 0.98 × 10-4 Wm-1K-2 respectively. Secondly, Ag and Ti were used for doping the CoSb₃ thin films via magnetron sputtering deposition. The microstructure, morphology, composition, and thermoelectric properties of the single doped CoSb₃ films are found to strongly dependent on the doping content. The results demonstrate a simultaneous improvement of the Seebeck coefficient and the electrical conductivity through Ag doping, indicating that Ag is an efficient dopant for CoSb₃ thin film. Maximal power factor value of 2.97×10-4 Wm-1K-2 has been obtained after Ag doping, which is several times of the value for the un-doped sample. Similar results have been obtained from the single Ti doped CoSb₃ thin films. Interestingly, the thermal conductivity of the film has also been dramatically reduced by carefully controlling the nano-structure and Ti doping content, resulting in an enhanced ZT value from 0.15 to 0.90. Thirdly, detailed studies on magnetron sputtering deposition Ag/(Sn, Ti or In) co-doped CoSb3 thin films have been performed. The influence of the co-doped element type and content on the properties of CoSb₃ thin films has been demonstrated. The Seebeck coefficient and the electrical conductivity of all the co-doped thin films have been simultaneously increased comparing to the un-doped thin film, leading to distinctly enhanced power factor. A maximum power factor value of about 0.32 mWm-1K-2 can be obtained from Ag/Sn co-doped thin film, and similar results have been obtained also from Ag/Ti and Ag/In co-doped films. Additionally, lower thermal conductivity has been obtained from the co-doped thin films, especially with the Ag/In co-doping, leading to much higher room temperature ZT value for the co-doped films, compared to the un-doped or Ag-doped thin films. Lastly, CoSb₃ based nano thin film device has been fabricated and a multilayer structure of the electrodes was used in order to improve the thermal stability of the device in air. A relatively high output voltage of above 90 mV and a high power density of 0.46 mWcm-2 can be obtained with this device. Moreover, this device has also been tested as thermal sensor and it exhibits a fast responsivity, with a reaction time of a few hundreds of millisecond, as well as a high stability. It has also been demonstrated the possibility of obtaining relatively high output voltage of about 7 V at a current intensity of about 0.35 mA by connecting several thin film thermoelectric devices. These results are highly encouraging for achieving practical applications such as power supply for portable electronic devices and sensor.

Ce projet est consacré à l'étude des propriétés optiques des films minces en nitrure d'aluminium dopé par des terres rares. Plus particulièrement, le travail est orienté pour étudier les mécanismes de luminescence des éléments RE sélectionnés incorporés dans des films minces AlN pour être utilisés comme candidats aux dispositifs d'éclairage. Au cours de cette thèse, la technique de pulvérisation de magnétron réactif est utilisée pour synthétiser les films minces AlN non dopés et dopés. La technique et le traitement des films sont discutés en détail. L'effet des conditions de pulvérisation sur la structure et les propriétés optiques des films préparés est étudié. La corrélation entre les conditions de pulvérisation cathodique, l'orientation cristallographique, la morphologie, la microstructure et les propriétés optiques sont établies. Les analyses de structure et de composition des échantillons préparés ont été étudiées par plusieurs moyens, tels que la microscopie électronique à transmission, la spectroscopie à rayons X à énergie dispersive et la spectrométrie de rétrodiffusion Rutherford. Les propriétés optiques des films sont caractérisées par une transmission UV-Visible, une spectroscopie d'Ellipsometry et une spectroscopie de photoluminescence / This project is dedicated to study the optical properties of rare earth-doped aluminum nitride thin films. More particularly, the work is oriented to investigate the luminescence mechanisms of selected RE elements incorporated in AlN thin films to be used as a candidate for lighting devices. During this thesis, reactive magnetron sputtering (RMS) technique is used to synthesize the undoped and doped AlN thin films. The technique and films processing are discussed in details. The effect of sputtering conditions on the structure and optical properties of the prepared films are investigated. The correlation between the sputtering conditions, the crystallographic orientation, the morphology, the microstructure and the optical properties are established. The structure and composition analyses of the prepared samples have been investigated by several means, such as transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), and Rutherford backscattering spectrometry (RBS). The optical properties of the films are characterized by UV-Visible transmission, Ellipsometry spectroscopy, and Photoluminescence spectroscopy

This thesis report presents a new design of a synchronization unit for high power impulse magnetron sputtering (HiPIMS) applications used for depositing thin films. The proposed system is composed of two major hardware parts: a microcontroller unit (MCU) and a field-programmable gate array (FPGA). The control range of the new system is increased by at least ten times compared to existing synchronization unit designed by Ionautics AB.In order to verify the system and benchmark its innovations, several batches of the thin film have been deposited using the new technology. It is shown that HiPIMS with synchronized pulsed substrate bias can effectively improve coating performance. Pulsed substrate bias with user-defined pulse width and delay time is possible to use in the new control mode proposed by this master thesis work; Bias mode. As a result, this master thesis work enables users to flexibly control the HiPIMS processes.

L'objectif de cette thèse était d'étudier les propriétés thermoélectriques de couches minces d'oxyde de type delafossite déposées par pulvérisation cathodique magnétron. Pour cela, les oxydes CuCrO2:3%Mg, CuFeO2:3%Mg et CuCr0,84Fe0,16O2:3%Mg ont été déposés avec différentes épaisseurs sur des substrats de silice amorphe puis traités sous vide à différentes températures afin d'obtenir la structure delafossite. La température de traitement thermique optimale permettant d'obtenir les meilleures propriétés thermoélectriques est de 550°C pour CuCrO2:Mg et CuCr0,84Fe0,16O2:Mg et de 700°C pour CuFeO2:Mg. L'épaisseur optimale des couches minces est de 100 nm pour la delafossite au chrome et de 300 nm pour celle au fer. La conductivité électrique des couches augmente avec la température tout en conservant un coefficient Seebeck positif et constant pour les trois compositions données impliquant un mécanisme par saut de polarons. Le facteur de puissance des couches minces CuCrO2:Mg, CuFeO2:Mg et CuCr0,84Fe0,16O2:Mg dont l'épaisseur et la température de recuit ont été optimisées atteint respectivement 59 µW.m-1K-2, 84 µW.m-1K-2 et 36 µW.m-1K-2 à 200°C. Les études microstructurales et structurales ont permis de comprendre la variation du facteur de puissance avec la température de recuit et l'épaisseur. Elles ont notamment montré que la décroissance de la conductivité électrique des films traités à haute température est due à des phénomènes concomitants de fissuration de la couche et de ségrégation du magnésium. Une étude thermique utilisant la modélisation avec la méthode des éléments finis a permis de démontrer que dans le cas des couches minces, la conductivité thermique du substrat peut se substituer à celle du film dans le calcul de facteur de mérite. La validité du facteur de mérite modifié ((ZT)* = S2σ/ksubstrat) a été énoncée en fonction de l'épaisseur, l'émissivité et la conductivité thermique de la couche mince. L'utilisation de la méthode 3ω a permis de déterminer une valeur de conductivité thermique de 4,82 W.m-1k-1 à 25°C pour le film mince CuFeO2:Mg, qui se situe dans le domaine de validité établi pour l'utilisation de (ZT)*.[...] / The aim of this thesis was to study the thermoelectric properties of delafossite type oxides thin-films deposited by RF-magnetron sputtering. Several thicknesses of CuCrO2:3%Mg, CuFeO2:3%Mg and CuCr0,84Fe0,16O2:3%Mg oxides were deposited on fused silica then annealed under vacuum at different temperatures in order to obtain delafossite structure. The optimal annealing temperature which leads to an acceptable thermoelectric properties is 550°C for CuCrO2:Mg and CuCr0,84Fe0,16O2:Mg thin films and 700°C for CuFeO2:Mg thin film. The optimal thickness is 100 nm for the delafossite with chrome and 300 nm for delafossite with iron. The electrical conductivity of the studied thin films increases with the temperature, while maintaining a positive and constant Seebeck coefficient for the three given compositions that implies a hopping mechanism. The power factor of CuCrO2:Mg, CuFeO2:Mg and CuCr0,84Fe0,16O2:Mg thin films for which the annealing temperature and the thickness were optimized, reached 59 µW.m-1K-2, 84 µW.m-1K-2 and 36 µW.m-1K-2 respectively at 200°C. The microstructural and structural analysis allowed to understand the variation of the power factor with the annealing temperatures and the thicknesses. In particular, they showed that the decrease in the electrical conductivity of the thin films annealed at high temperature is due to concomitant phenomena of film cracking and magnesium segregation. A thermal analysis using modeling with the finite element method has demonstrated that in the case of thin films, the thermal conductivity of the substrate can be substituted for the thermal conductivity of the film in the calculation of figure of merit. The validity of the modified figure of merit ((ZT)* = S2σ/ksubstrate) was given as a function of the film thickness, emissivity and thermal conductivity. The thermal conductivity of CuFeO2:Mg was measured using the 3ω method and it was 4.82 W.m-1k-1 at 25°C which is within the range of validity established for the use of (ZT)*[...]

Cette étude porte sur l’élaboration et la caractérisation des propriétés de revêtements de phases Magnéli de titane (TinO2n-1) en vue de leur application tribologique. Les dépôts ont été élaborés par pulvérisation cathodique magnétron en condition réactive à partir de cible métallique de titane dans une atmosphère O2/Ar sur un porte substrat rotatif chauffant.La première partie de l’étude appuie sur la synthèse de monocouches de phases Magnéli de titane. L’influence des principaux paramètres d’élaboration (débit d’oxygène, température du porte substrat) a été analysé au regard de la structure et de la morphologie des revêtements synthétisés. Ensuite, des bicouches TinO2n-1/AlTiN ont été synthétisées par la technique de pulvérisation cathodique magnétron et de l’arc électrique sous basse pression, respectivement. Cependant, la phase et l’épaisseur de la couche de surface d’oxyde de titane ainsi que l’épaisseur de la sous-couche AlTiN ont été choisies comme les paramètres à étudier.La deuxième partie concerne les propriétés mécaniques (nano dureté instrumenté, module d’élasticité, test Mercedes et scratch test) et tribologiques (test pion disque) des revêtements monocouches et bicouches. Une attention particulière a été portée à l’influence de la température du test de frottement sur le taux d’usure des revêtements duplex. / The present work deals with the synthesis and the structural, mechanical and tribological characterization of titanium Magnéli phases (TinO2n-1) coatings for tribological application. The thin films were prepared by reactive magnetron sputtering from titanium target in a reactive O2/Ar gas mixture using a rotating and heating substrate holder.The first part of the study is based on the synthesis of titanium Magneli phase monolayers. The influence of the main synthesis parameters (oxygen flow rate, temperature of the substrate holder) was analyzed in relation with the structure and the morphology of the synthesized coatings. Then TinO2n-1/AlTiN bilayers were synthesized by the reactive magnetron sputtering and the low pressure electric arc techniques, respectively. The phase and the thickness of the top layer of titanium oxide and the thickness of the under layer AlTiN were selected as the parameters to be studied.The second part concerns the mechanical properties (nano hardness instrumented, elasticity modulus, Mercedes test and scratch test) and tribological properties (pin on disc test) of the monolayer and bilayer coatings. Particular attention was paid to the influence of the friction test temperature on the bilayer coatings wear rates.