Diamond is a unique material with many exceptional properties. It has therefore been proven to be an important material for many applications. Moreover, the introduction of dopant species into the gas phase during the CVD growth process has been shown to strongly influence not only the properties and morphology of diamond, but also the growth rate. The purpose with the theoretical part of the present study has been to support and explain the experimental observations regarding the effect of various dopants (nitrogen, phosphorous, sulphur, and boron) on the diamond growth rate. Commonly observed H-terminated diamond surfaces [(111), (110) and (100)-2×1], were thereby carefully investigated using density functional theory under periodic boundary conditions. Based on the assumption that the hydrogen abstraction reaction is the growth rate-limiting step, both the thermodynamic and kinetic aspects of the diamond growth process were found to be severely affected by various dopants. More specifically, the results showed that nitrogen and phosphorous dopants (positioned within the 2nd, 3rd or 4th carbon layer) will cause an enhancement in the growth rate (as compared with non-doped situations). On the other hand, any growth rate improvement does only occur when positioning boron in the 2nd, and sulphur in the 4th, atomic carbon layer. With boron, and sulphur, positioned within the other atomic carbon layers, the growth rates were observed to decrease. In addition, the main purpose with the experimental part of the present study has been to investigate the effect of one specific dopant precursor (TMB) on the boron-doped diamond growth process. The result has shown that the increasing mass flow of TMB will not affect the mechanism of the HFCVD growth process of boron doped diamond. However, a linear boron carrier concentration in the diamond film vs. mass flow rate of TMB was observed.

The studies covered in this dissertation concentrate on the various forms of diamond films synthesized by chemical vapor deposition (CVD) method, including microwave CVD and hot filament CVD. According to crystallinity and grain size, a variety of diamond forms primarily including microcrystalline (most commonly referred to as polycrystalline) and nanocrystalline diamond films, diamond-like carbon (DLC) films were successfully synthesized. The as-grown diamond films were optimized by changing deposition pressure, volume of reactant gas hydrogen (H2) and carrier gas argon (Ar) in order to get high-quality diamond films with a smooth surface, low roughness, preferred growth orientation and high sp3 bond contents, etc. The characterization of diamond films was carried out by metrological and analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and Raman spectroscopy. The results of characterization served as feedback to optimize experimental parameters, so as to improve the quality of diamond films. A good understanding of the diamond film properties such as mechanical, electrical, optical and biological properties, which are determined by the qualities of diamond films, is necessary for the selection of diamond films for different applications. The nanocrystalline diamond nanowires grown by a combination of vapor-liquid-solid (VLS) method and CVD method in two stages, and the graphene grown on silicon substrate with nickel catalytic thin film by single CVD method were also investigated in a touch-on level.

La microscopie à force atomique (AFM) permet d’étudier à l’échelle nanométrique la surface d’échantillons. Elle offre de nombreux avantages par rapport aux microscopes optiques et aux microscopes électroniques, tout en évitant des étapes de préparation particulières : pas de nécessité de congeler, de métalliser ou de teinter l’échantillon ni de travailler sous vide. La résolution de l'imagerie AFM est principalement déterminée par la morphologie de la sonde utilisée et peut atteindre la résolution moléculaire. Toutefois, les sondes en silicium sont très fragiles. De plus, leur forme pyramidale ou conique génère des artefacts sur l’image résultante. Parmi les sondes actuellement en développement, les sondes à nanotubes de carbone mono-paroi offrent de bonnes caractéristiques en termes de qualité d'imagerie et de longévité. Ces sondes sont plus résistantes et de plus petite taille que les sondes traditionnelles.Cette thèse s’intéresse à la fabrication directe de sondes à nanotubes mono-paroi sur des extrémités de pointes AFM commerciales par la méthode de dépôt chimique en phase vapeur assistée par filament chaud dans un réacteur développé au CBMN. En jouant sur les paramètres de synthèse, tels que la quantité de catalyseur ou la température, nous optimisons le protocole de synthèse originel en collaboration avec son auteur Anne-Marie Bonnot afin de l’adapter à notre réacteur. Les nanotubes obtenus sont caractérisés par les microscopies Raman, électronique à balayage et transmission et à force atomique. La caractérisation montre que les nanotubes obtenus ont une structure mono-paroi. Le rendement d’obtention de sondes nanotubes utilisables est de 30%.Les courbes d’approche-retrait d'AFM nous donnent des informations sur la sonde à nanotube utilisée, telles que sa raideur, le nombre de nanotubes en contact avec la surface. Ces courbes nous permettent de sélectionner les paramètres d’imagerie. Deux échantillons sont testés avec les sondes produites : du graphite pyrolytique haute orientation et des origamis d’ADN rectangulaires. Nous réalisons des expériences d’imagerie avec des sondes à nanotube dans l’air en mode dynamique FM et en milieu liquide en mode Peak Force. Les résultats montrent des images à haute résolution de l’origami d’ADN où la période de 5,8 nm est observable. Les sondes à nanotube présentent également une plus longue durée de vie que les pointes AFM en silicium. / Atomic force microscopy (AFM) is used to study at nanometer scale samples on surfaces. It offers many advantages over conventional optical microscopes and electron microscopes: no freezing, metal coating, vacuum or dye is needed to prepare the sample. The AFM imaging resolution is mostly determined by the sharpness of the used probe and can reach molecular resolution. However, silicon probes are brittle. Additionally, their pyramidal or conical shape generates artifacts on the resulting image. Among the probes currently under development, single-walled carbon nanotube probes offer good characteristics in terms of imaging quality and longevity. These probes are more resistant and smaller in size than traditional probes.This thesis focuses on the direct fabrication of single-wall nanotube probes at the apex of commercial AFM tips by the hot-filament chemical vapor deposition method in a reactor developed at CBMN. By playing on the synthesis parameters, such as the amount of catalyst or the temperature of synthesis, we optimize the original synthesis protocol in collaboration with its author Anne-Marie Bonnot in order to adapt it to our reactor. The nanotubes obtained are characterized by Raman, scanning electron microscopy and transmission electron microscopy and AFM. The characterization shows that the nanotubes obtained have a single-wall structure. The yield of nanotube probes for AFM is 30%.AFM approach-retract curves give us information about the nanotube probe used, such as its stiffness or the number of nanotubes in contact with the surface. These curves allow us to select the imaging parameters. Two samples are tested with the produced probes: highly oriented pyrolytic graphite and rectangular DNA origamis. We image the samples with nanotube probes in both air with dynamical FM mode and in liquid medium with Peak Force mode. The results show high resolution images of DNA origami where the 5.8 nm period is observable. Nanotube probes also have longer life than silicon AFM tips.