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By an extensive investigation of the principal growth parameters on the deposition process, we realized the epitaxial growth of crystalline wurtzite GaN thin films on single crystal (001) diamond substrates by metal organic chemical vapor deposition. From the influence of pressure, V/III ratio, and temperature, it was deduced that the growth process is determined by the mass-transport of gallium precursor material toward the substrate. The highest temperature yielded an improved epitaxial relationship between grown layer and substrate. X ray diffraction (XRD) pole figure analysis established the presence of two domains of epitaxial layers, namely (0001) < 101 0> GaN∥ (001)[110] diamond and (0001) < 101 0> GaN∥ (001) [110] diamond, which are 90° rotated with respect to each other. The presence of these domains is explained by the occurrence of areas of (2×1) and (1×2) surface reconstruction of the diamond substrate. When applying highly misoriented diamond substrates toward the [110] diamond direction, one of the growth domains is suppressed and highly epitaxial GaN on (001) diamond is realized. [ABSTRACT FROM AUTHOR]

A method for the nucleation enhancement of nanocrystalline diamond (NCD) films on silicon substrates at low temperature is discussed. A sputter deposition of a Mo seed layer with thickness 50 nm on Si substrates was applied followed by an ultrasonic seeding step with nanosized detonation diamond powders. Hot-filament chemical vapor deposition (HF-CVD) was used to nucleate and grow NCD films on substrates heated up at 550 °C. The nucleation of diamond and the early stages of NCD film formation were investigated at different methane percentages in methane/hydrogen gas mixtures by atomic force microscopy, micro-Raman spectroscopy, scanning electron microscopy, and grazing incidence x-ray analyses in order to gain specific insight in the nucleation process of NCD films. The nucleation kinetics of diamond on the Mo-coated Si substrates was found to be up to ten times higher than on blank Si substrates. The enhancement of the nucleation of diamond on thin Mo interlayers results from two effects, namely, (a) the nanometer rough Mo surface shows an improved embedding of ultrasonically introduced nanosized diamond seeds that act as starting points for the diamond nucleation during HF-CVD and (b) the rapid carbonization of the Mo surface causes the formation of Mo2C onto which diamond easily nucleates. The diamond nucleation density progressively increases at increasing methane percentages and is about 5×1010 cm-2 at 4.0% methane. The improved nucleation kinetics of diamond on Mo interlayers facilitates the rapid formation of NCD films possessing a very low surface roughness down to ∼6 nm, and allows a submicron thickness control. [ABSTRACT FROM AUTHOR]

Fine-crystalline diamond particles are grown on standard Si atomic force microscopy tips, using hot filament-assisted chemical vapor deposition. To optimize the conditions for diamond deposition, first a series of experiments is carried out using silicon substrates covered by point-topped pyramids as obtained by wet chemical etching. The apexes and the edges of the silicon pyramids provide favorable sites for diamond nucleation and growth. The investigation of the deposited polycrystallites is done by means of optical microscopy, scanning electron microscopy and micro-Raman spectroscopy. The resulting diamond-terminated tips are tested in ultra high vacuum using contact-mode atomic force microscope on a stepped surface of sapphire showing high stability, sharpness, and hardness. [ABSTRACT FROM AUTHOR]

Analyzes the asymmetry between growth and dissociation using Monte Carlo simulations of flat and vicinal surfaces of a Kossel crystal. Production of very anisotropic and nearly anatomically flat surfaces at a high driving force dissolution; Role of the chemical-etch reaction in determining the annihilation rate constants.

The lattice Monte Carlo (MC) model for binary crystal growth is considered to induce a freedom of choice in the transition probabilities, as the thermodynamic properties of the system does not ensure an agreement between MC simulations and the thermodynamic constraints. The analysis confirms that the kinetics have an extremely strong effect on the segregation of such models and hence also enables a straightforward determination of the optimal set of transition probabilities.

Analyzes the distribution of grown-in nitrogen-vacancy pairs in synthetic IB diamond crystals by means of a photoluminescence tomographic technique. Operating principle of the technique; Details on the specimens; Advantages of the technique.

Presents information on a study which examined the growth of fiber textured diamond films with the addition of nitrogen. Experimental procedure; Influence of the nature of substrates on fiber texturing; Comparison of hot-filament and flame-grown chemical-vapor deposition diamonds.