Codeposition on hot CVD surfaces: Particle dynamics and deposit roughness interactions

To capture in a tractable manner essential coupling effects in CVD systems when particles generated in thermal boundary layers also deposit, a film theory was developed that predicts simultaneous vapor and particle deposition rates at a hot deposition surface. The codeposition rate prediction method also calculates for the first time the corresponding solid deposit roughness using recently published results of particle-level simulations. For the numerical illustrations, the growth of TiO2(s) films by the codeposition of titanium tetra-isopropoxide vapor and film-nucleated/grown TiO2 particles (generated in the thermal boundary layer) was considered. Experimental rate data for this system are available. The continuum and particle-level simulation methods provide: the interplay of vapor precursor kinetics, particle nucleation, growth, coagulation and division in determining the complex ''structure'' of such multiphase chemically reacting boundary layers; wall deposition rates of both surviving vapors and film-nucleated particles; and the ''self-consistent'' microstructure (surface roughness) of the resulting solid deposit timely and tractable generalizations are discussed in the light of recent results for the transport properties and stability of ''fractal-like'' aggregated particles.