In this thesis, the growth mechanism of graphene on a transition metal support is determined, and the epitaxial relationship investigated. The main technique used is low- temperature scanning tunnelling microscopy (STM), which is introduced in Chapter 2. Epitaxial graphene synthesised on copper (foil and (110) single crystal), from the dehydrogenation of ethene, is investigated by STM and low energy electron diffraction (LEED) in Chapter 4. Despite the weak epitaxial relationship that exists, LEED uncovers two preferred orientations of the graphene over the copper. Further investigation reveals restructuring of the copper foil from a predominantly (100) orientation to (n10) facets. Structural feedback is found to exist, with the graphene growth inducing and stabilising faceting of the copper surface, and the facets in-turn playing an important role in the graphene growth mechanism. The preferred orientations, which are also seen on the single crystal, are most likely determined during nucleation and early stage growth, where it is expected that the interaction is stronger. The growth mechanism for the formation of graphene from ethene is studied on a Rh(111) surface in Chapter 5. This is found to consist of two regimes, with the first revolving around the transformation from aliphatic hydrocarbons to aromatic intermediates. This occurs through the decomposition and condensation of ethene, resulting in the formation of one-dimensional polyaromatic hydrocarbons (1D-PAHs). The second regime is characterised by the transition from these 1D-PAHs, to the 2D graphene. The previously produced 1D-PAHs, decompose to form size-selective carbon clusters, with these clusters being the precursors to graphene condensation. In Chapter 6, the conclusions of Chapter 5 are built upon through investigation into the effect of different hydrocarbon feedstocks on the graphene growth pathway. Benzene, tetracene, and perylene are the feedstocks examined. In all cases 1D-PAHs are formed, which decompose to clusters that subsequently condense to form graphene.

The focus of this work was to examine the direct plating of Cu on Ru diffusion barriers for use in interconnect technology and the substrate mediated growth of graphene on boron nitride for use in advanced electronic applications. The electrodeposition of Cu on Ru(0001) and polycrystalline substrates (with and without pretreatment in an iodine containing solution) has been studied by cyclic voltammetry (CV), current-time transient measurements (CTT), in situ electrochemical atomic force microscopy (EC-AFM), and X-ray photoelectron spectroscopy (XPS). The EC-AFM data show that at potentials near the OPD/UPD threshold, Cu crystallites exhibit pronounced growth anisotropy, with lateral dimensions greatly exceeding vertical dimensions. XPS measurements confirmed the presence and stability of adsorbed I on the Ru surface following pre-treatment in a KI/H2SO4 solution and following polarization to at least −200 mV vs. Ag/AgCl. CV data of samples pre-reduced in I-containing electrolyte exhibited a narrow Cu deposition peak in the overpotential region and a UPD peak. The kinetics of the electrodeposited Cu films was investigated by CTT measurements and applied to theoretical models of nucleation. The data indicated that a protective I adlayer may be deposited on an air-exposed Ru electrode as the oxide surface is electrochemically reduced, and that this layer will inhibit reformation of an oxide during the Cu electroplating process. A novel method for epitaxial graphene growth directly on a dielectric substrate of systematically variable thickness was studied. Mono/multilayers of BN(111) were grown on Ru(0001) by atomic layer deposition (ALD), exhibiting a flat (non-nanomesh) R30(3x3) structure. BN(111) was used as a template for growth of graphene by chemical vapor deposition (CVD) of C2H4 at 1000 K. Characterization by LEED, Auger, STM/STS and Raman indicate the graphene is in registry with the BN substrate, and exhibits a HOPG-like 0 eV bandgap density-of-states (DOS).

Indiana University-Purdue University Indianapolis (IUPUI) / Systemic inflammation is one potential mechanism underlying the depression to cardiovascular disease (CVD) relationship. In addition, somatic rather than cognitive/affective symptoms of depression may be more predictive of poorer CVD outcomes due to systemic inflammation. However, the small existing literature in this area has yielded mixed results. Therefore, the present study aimed to examine longitudinal associations between depressive symptom clusters and inflammatory biomarkers implicated in CVD (i.e., interleukin-6, IL-6; and C-reactive protein, CRP) using data from the eIMPACT trial. In addition, race was examined as a moderator given findings from two previous studies. The eIMPACT trial was a phase II, single-center randomized controlled trial comparing 12 months of the eIMPACT intervention to usual primary care for depression. Participants were 216 primary care patients aged ≥ 50 years with a depressive disorder and CVD risk factors but no clinical CVD from a safety net healthcare system (Mage = 58.7 years, 78% female, 50% Black, Meducation = 12.8 years). Depressive symptoms clusters (i.e., somatic and cognitive/affective clusters) were assessed using the Patient Health Questionnaire-9 (PHQ-9). IL-6 and high-sensitivity CRP were assessed by the local clinical research laboratory using R&D Systems ELISA kits. Change variables were modeled in MPlus using a latent difference score approach. The results of this study were largely null. Very few associations between depressive symptom clusters and inflammatory biomarkers implicated in CVD were observed, and the detected relationships may be due to type I error. Similarly, only one association was observed for race as a moderator, and the detected relationship may be due to type I error. The present findings do not provide strong support for the longitudinal associations between depressive symptom clusters and inflammatory biomarkers implicated in CVD nor the moderating effects of race. However, the present findings do not rule out the possibility of these relationships given important study limitations, such as study design and power. Future prospective cohort studies with multiple waves of data collection are needed to determine the longitudinal associations between depression facets and various inflammatory biomarkers implicated in CVD. In addition, a biologically-based approach to identifying facets of depression – e.g., the endophenotype model – may provide a clearer understanding of the depression-inflammation relationship.

Graphene receives enormous attention owing to its distinctive physical and chemical prosperities. Growing and transferring graphene to different substrates have been investigated. The graphene growing on the copper substrate has an advantage of low solubility of carbon on the copper which allow us to grow mostly monolayer graphene. Graphene sheet of few centimeters can be transferred to 300nm silicon oxide and quartz crystal pre-deposited with metal like Cu and Ru. Characterization of the graphene has been done with Raman and contact angle measurement and recently quartz crystal microbalance (QCM) has been employed. The underpotential deposition (UPD) process of Bi on Ru metal surface is studied using electrochemical quartz crystal microbalance (EQCM) and XPS techniques. Both Bi UPD and Bi bulk deposition are clearly observed on Ru in 1mM Bi (NO3)3/0.5M H2SO4. Bi monolayer coverage calculated from mass (MLMass) and from charge (MLCharge) were compared with respect to the potential scanning rates, anions and ambient controls. EQCM results indicate that Bi UPD on Ru is mostly scan rate independent but exhibits interesting difference at the slower scan. Bi UPD monolayer coverage calculated from cathodic frequency change (ΔfCathodic) is significantly smaller than the monolayer coverage derived from integrated charge under the cathodic Bi UPD peak when scan rate is at least 5 mV/s. XPS is utilized to explore the detailed chemical composition of the observed interfacial process of Bi UPD on Ru.

La thèse porte sur cette couche de nitrure ou d’oxynitrure de silicium. Le déroulé prévoit l’élaboration des deux types de dépôts par voie gazeuse (par Chemical Vapor Infiltration CVI), la caractérisation de ces dépôts (par tous les moyens scientifiques à disposition et jugés utiles), ainsi que des essais en conditions proches de l’application visée (haute température, présence de phases liquides) pour juger de l’efficacité de ces dépôts et notamment effectuer une comparaison entre le nitrure et l’oxynitrure. Une étude complète des paramètres modifiables lors de l’élaboration et de leur effet sur la chimie (et par conséquent l’influence sur le comportement du matériau en conditions d’utilisation) représente le cœur du travail considéré. / Ceramics are usually used at high temperature because of their refractory nature. However, they are too brittle to be submitted to high stresses, such as in the rotating parts of aircraft engines. One way to reduce the brittleness of ceramics is to design them as composites. The fiber/matrix architecture displays a damageable character thanks to a suitable interfacial layer, which is deposited on the fiber cloths before the infiltration with molten silicon. The aim of the thesis is to propose and evaluate a solution to protect the fiber reinforcement during the impregnation step with liquid silicon. This solution involves the deposition of a protective layer made of silicon nitride or oxynitride.

Le diamant monocristallin est un candidat prometteur pour les applications en électronique de puissance et l'hétéroépitaxie est une alternative crédible à la synthèse de ce matériau. Lors de ce travail de thèse, chacune des étapes de la synthèse de films de diamant hétéroépitaxié sur des pseudo-substrats de Ir/SrTiO₃/Si(001) a été finement étudiée afin de progresser dans la reproductibilité et la qualité cristalline de ces films. Ainsi, un système de réflectométrie laser a été installé sur le bâti d'épitaxie d'iridium afin de caractériser in situ l'épaisseur des films réalisés. Une nouvelle méthode basée sur traitement plasma permettant la recristallisation de l'iridium à des températures comprises entre 800°C et 900°C a été mise au point et brevetée. Ensuite, une caractérisation de la surface de l'iridium après l'étape de nucléation du diamant (BEN) par ellipsométrie spectroscopique a été réalisée en bâtissant un modèle ellipsométrique à partir d'une étude séquentielle en MEB, AFM et XPS. Cette étude démontre que l’ellipsométrie est sensible à la formation des domaines qui contiennent les cristaux de diamant épitaxiés. L'étape de nucléation a été étendue à des pseudo-substrats Ir/SrTiO₃/Si(001) de 10x10 mm². Une stratégie d'épaississement des films de diamant reposant sur deux étapes a été adoptée. La structure cristalline des films épaissis à plusieurs centaines de microns a été caractérisée par DRX et Raman. Des diodes Schottky latérales ont été fabriquées sur l'un des substrats épaissis. Les mesures électriques réalisées démontrent l'homogénéité du substrat de diamant hétéroépitaxié. Afin de mieux contrôler les premiers stades de la croissance, une nouvelle méthode de nucléation sélective a été mise au point et brevetée. Son application permettrait dans l'avenir d'obtenir une croissance latérale (ELO) dès la coalescence des premiers cristaux de diamant. / Single crystal diamond is a promising candidate for power electronics applications and heteroepitaxy is a credible alternative for the synthesis of this material. During this PhD, each step from the synthesis of heteroepitaxial diamond films on Ir/SrTiO₃/Si(001) pseudo-substrates was studied in details to progress in the reproducibility and the crystalline quality of films. Thus, a laser reflectometry system was installed on the iridium epitaxy reactor to characterize in situ the thickness of these films. A new approach based on plasma treatment leading to the iridium recrystallization at temperatures between 800°C and 900°C was developed and patented. Then, a characterization of the iridium surface after diamond nucleation (BEN) by spectroscopic ellipsometry was done by building an ellipsometric model based on a sequential study by SEM, AFM and XPS. Results demonstrate that ellipsometry is sensitive to the formation of domains including epitaxial diamond crystals. The nucleation step was extented to Ir/SrTiO₃/Si(001) pseudo-substrates with a size of 10x10 mm². A strategy for the thickening of diamond films based on two steps was adopted. The crystalline structure of films, few hundreds of microns thick, was characterized by XRD and Raman. Lateral Schottky diodes were built on one of the thick substrates. Electrical measurements demonstrate the homogeneity of the heteroepitaxial diamond substrate. To better control the growth early stages, a new method of selective nucleation was developed and patented. Its application in the future would make possible a lateral growth (ELO) from the coalescence of the first diamond crystals.

Des nouveaux précurseurs non fluorés de cuivre (I) de la famille (b-dicétonate)Cu(L) (où L= BTMSA (Bis(triméthylsilyl) acétylène) ou TMSP (1-(triméthyl silyl) propyne)) ont été synthétisés par réaction acide-base et caractérisés. Parmi les précurseurs synthétisés, (5-méthyle-2,4-hexanedionate)Cu(BTMSA) et (5,5-diméthyle-2,4-hexanedionate)Cu(BTMSA) sont les précurseurs les plus prometteurs; ils sont liquides à température ambiante, très volatils et assez stables. A partir des précurseurs, les films adhérents, continus, purs et conducteurs électriques de cuivre métallique ont été déposés à partir de 170°C sur Ta/TaN. L'AuCl(PF3) a été évalué, dans ce travail de thèse, comme précurseur pour déposer de films minces d'or par CVD thermique. Ce précurseur inorganique a été utilisé sous forme solide pur (à l'aide d'un bulleur) ainsi que dissout dans une solution avec le toluène comme solvant (utilisant un système d'injection direct). En utilisant H2 comme gaz co-réactif, les films minces continus, purs d'or ont été déposés sur Ta/TaN à partir de 110°C. Nous avons étudié l'influence de la nature de gaz vecteurs (N2, H2), de la température de dépôt sur la réaction de décomposition du précurseur ainsi que sur les caractéristiques des films obtenus. L'utilisation de [IrCl(PF3)2]2 comme précurseur pour le dépôt CVD d'iridium a été réalisée, pour la première fois, dans ce travail de thèse. Ce précurseur inorganique est très volatil mais sensible. Nous l'avons généré "in-situ" dans le réacteur de dépôt CVD à partir de IrCl(PF3)4, le produit plus stable et manipulable. Sous N2, [IrCl(PF3)2]2 se décompose à partir de 240°C donnant des films compacts, extrêmement purs d'Ir sur SiO2/Si. Dans le cadre de ce travail, l'influence de la nature de gaz vecteurs (N2, H2 ou O2) et de la température de dépôt sur la croissance des films déposés a été également examinée.

The growth of TiN on cemented carbide, deposited by chemical vapour deposition (CVD), was studied. Today TiN is used as a seeding layer between the cemented carbide and the following layer. Previous experiments have shown that the coverage is uneven on the cemented carbide surface showing pits with a different growth than the main part of the surface. These pits most likely occur on some of the WC surfaces. Therefore the growth and orientation relation between the two phases were examined. Cemented carbide specimens were deposited with TiN under two different pressures and with different deposition time to give a layer as thick as the seeding layer used in the production and one about ten times thicker to study growth after the whole surface had been covered. Two pre-treatments where used on the specimens; one which were polishing with diamond and the other where the specimens were boiled in acid to remove the binder phase and expose the WC surfaces. The specimens were studied using XRD and a SEM equipped with EDS and EBSD detectors. The pictures taken with SEM showed that initial growth occurred at grain boundaries and polishing scratches. It also showed that growth occurred on all surfaces, which were confirmed by EDS. Both processes showed about the same appearance in the thinner layers but very different appearance in the thicker. This was confirmed by XRD were the thinner layers showed about the same result while the thicker ones differ from one another. Thus further growth is dependent on the parameters of the CVD process and not the surface beneath. EBSD showed an orientation relation between TiN and WC crystals in both processes. The process at lower pressure gave much finer grains which were difficult to index with EBSD, giving results in only three points. The process at higher pressure gave coarser grains which were more easily indexed. The relations WC{0001}-TiN{110}, giving WC{101̅0}-TiN{100}, and WC{0001}-TiN{111}, giving WC{101̅0}-TiN{211}, could be seen in more than one point. These results are consistent with previous studies of the growth of TiC on WC. This comparison between TiC and TiN makes it possible to draw the conclusion that also Ti(C,N) should behave the same. It also shows an orientation relation that is consistent no matter what WC plane is on the surface. The poor growth and the pits depend on the growth orientation of TiN on each specific WC surface.

In this work, Nitridated b-LiGaO2 substrates have been used to grow nonpolar a-plane ZnO epitaxial films by a homemade thermal chemical vapor deposition. We control the quality of the films by adjusting the deposition position, growth temperature and oxygen partial pressure. The properties of the ZnO films was investigated by x-ray diffraction(XRD), scanning electron microscopy(SEM), atomic force microscopy(AFM), photoluminescence spectra(PL), Raman spectra(Raman) and transmission electron microscopy(TEM). The results show that the crystal quality, surface morphology and optical properties of a-plane ZnO films are strongly related to the deposition position and growth temperature. It is also found that the surface roughness of the ZnO films gets more smoothly with increasing the oxygen partial pressure. Up to now, ZnO films grown at 700¢J diplay the best crystal quality, the full width at half maximum values of (11-20)ZnO omega scan rocking curve is 0.5¢X. In comparison with above growth condition, it demonstrate better optical properties by shortening deposition position and increasing growth temperature to 750¢J. Room temperature PL spectra exhibit a strong near band edge emission and a negligible green band. Furthermore, low temperature PL spectra is dominated by neutral donor-bound excitons and free electron-to-bound emission. From the TEM selected area diffraction patterns and the XRD phi angle scan, the epitaxy relationship between ZnO and LGO is determined as [001]LGO//[0001]ZnO and [100]LGO//[10-10]ZnO. XRD omega-two theta scan and Raman spectra analysis are carried out to characterize the status of the strain in ZnO film is compressive, the reason is illustrate in detail.

Abstract In this work, H2, CH4, and O2 are used as gas sources and C3H903B is used as the doping source, microwave plasma chemical vapor deposition and a two-steps deposition process will be applied to the growth of boron-doped diamond on p-type(111) silicon substrate. In this work, nucleation and growth of diamond film have been studied. A series of experiments are focused on the depenence of experimental pressure, temperature, power, dc bias, flow rates of O2, and doping concentration of C3H903B. The samples are examined by SEM, Raman, XRD, FTIR, and I-V. The results show that if nucleation is assisted by a negative dc bias, it can reach high density. The growth of diamond and the boron-doped diamond film is in multi steps. After 90 minutes of growth, the mechanism of deposition will be changed.