The ‘‘kinetic theory’’ of homogeneous nucleation developed by Katz and Wiedersich is extended to derive a new expression for the rate from an ideal supersaturated vapor. Compared classical rate, has slightly different dependence on supersaturation, substantially temperature. A comparison with experimental data rates several organic liquids indicates that in some but not all cases gives much closer agreement than does expression. Discrepancies between theory are ascribed mainly physical...

Product contamination by particles nucleated within the processing environment often limits deposition rate during chemical vapor processes. A fundamental understanding of how these nucleate could allow higher growth rates while minimizing particle contamination. Here we present an extensive kinetic mechanism for silicon hydride cluster formation silane pyrolysis. This includes detailed information about relative stability and reactivity different possible clusters. It provides a means...

Two types of numerical models for homogeneous nucleation and particle growth are compared: in which the time rate change stable aerosol population is given by an analytical expression rate, discrete models, not required nor explicitly calculated. The classical coupled to a moment model, found produce poor agreement with discrete-sectional model except very low values dimensionless surface tension. A new proposed, when produces excellent over wide range tensions. also consistent experimental...

Individual nanoparticles of silicon and titanium having diameters in the range $40--140\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ have been repeatedly compressed by a nanoindenter. Even at low loads, small tip-particle particle-substrate contacts generate extreme pressures within confined particle, influencing its stiffness fracture toughness. The effect these high on measured modulus is taken into account invoking Murnaghan equation-of-state-based analysis. Fracture toughness particles found...

A new silicon hydride clustering model was developed to study the nucleation of particles in a low-temperature silane plasma. The contains neutral silanes, silylenes, silenes and silyl radicals as well silylene anions. Reaction rates were estimated from available data. Simulations carried out for typical discharge parameters capacitive It shown that main pathway leading governed by anion-neutral reactions. SiH2 radical insertion found be important only initial stages clustering, whereas...

In a previous paper [S. L. Girshick and C.-P. Chiu, J. Chem. Phys. 93, 1273 (1990)] modified expression for the homogeneous nucleation rate was obtained, which multiplied classical by an often large, temperature-dependent factor. This result had been derived as extension of kinetic theory [J. Katz H. Wiedersich, Colloid Interface Sci. 61, 351 (1977)]. It is shown that same could be directly from theory, modification in consequence writing equilibrium cluster distribution self-consistently,...

Nanocrystalline silicon carbide films were deposited by thermal plasma chemical vapor deposition, with film growth rates on the order of 10μm∕min. Films molybdenum substrates, substrate temperature ranging from 750-1250 °C. The are composed primarily β-SiC nanocrystallites. Film mechanical properties investigated nanoindentation. As increased average grain size, crystalline fraction in film, and hardness all increased. For temperatures above 1200 °C size equaled 10-20 nm, 80-85 %,...

Abstract We have developed a numerical simulation methodology that is able to accurately characterize the focusing performance of aerodynamic lens systems. The commercial computational fluid dynamics (CFD) software FLUENT was used simulate gas flow field. Particle trajectories were tracked using Lagrangian approach. Brownian motion nanoparticles successfully incorporated in our simulations. This tool then evaluate an assembly designed focus 3 nm spherical unit density particles following...

A method was developed for fabricating nanocrystalline microstructures. This involves synthesizing nanoparticles in a thermal plasma expanded through nozzle, and then focusing the to collimated beam by means of aerodynamic lenses. High-aspect-ratio structures silicon carbide titanium were deposited on stationary substrates, lines two-dimensional patterns translated substrates. Linewidths equalled approximately 50 μm. approach allows use much larger nozzles than previously micronozzle...

A detailed surface chemistry mechanism is proposed for chemical vapor deposition of diamond films, which extends the growth-by-methyl by Harris to treat any CHm radical, m=0–3, as a growth monomer. Numerical computations were performed in was coupled model boundary layer above substrate, conditions typical an atmospheric-pressure thermal plasma. The predicted linear rate increases strongly thickness δ decreased, and results indicate strong dependence on δ. For relatively thick layers (modest...

Coagulation of nanoparticles in a low-pressure radio frequency plasma was studied by means detailed numerical model for the spatiotemporal evolution nanoparticle-plasma system. Simulation results indicate that occurrence coagulation to any significant degree such systems requires existence two effects: first, gas-phase nucleation is not limited brief burst, but rather continues regions are sufficiently free nanoparticles; and second, coefficients collisions between neutral negatively charged...

Gas-phase silver nanoparticles were coated with silicon dioxide (SiO2) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced inert gas condensation, and a SiO2 precursor, tetraethylorthosilicate (TEOS), exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure varying temperatures. The VUV photons dissociate the TEOS initiating reaction that forms coatings on particle surfaces. Coating thicknesses measured for variety of operation parameters using...

Sectional models of the dynamics aerosol populations are well established in literature but have received relatively less attention numerical dusty plasmas, where most modeling studies assumed existence monodisperse dust particles. In case plasmas which nanoparticles nucleate and grow, significant polydispersity can exist particle size distributions, stochastic charging cause particles given to a broad distribution charge states. models, while computationally expensive, suited treating such...