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An evaluation of silicon epitaxial thin film growth using the SiHCl3-H2system in a horizontal chemical vapor deposition (CVD) reactor is discussed. The transport equations for gas velocity, temperature and concentration of chemical species are solved, taking account of the dependence of gas properties on temperature and composition. By comparing the measured and predicted growth rates under atmospheric pressure, the increase in growth rate with temperature and SiHCl3concentration can be explained by assuming an Arrhenius-type expression for the chemical reaction of SiHCl3and H2on a substrate. The calculated growth rate of the Si film increases nonlinearly with SiHCl3concentration because the flow, temperature, and concentration distributions in the reactor depend on the SiHCl3concentration. Suppression of the growth rate due to thermal diffusion, which transports SiHCl3gas away from the hot surface, is found to become significant as the SiHCl3concentration in the reactor increases.

Deposition of ultrafine aerosol particles by Brownian diffusion and thermophoresis in a nonisothermal laminar pipe flow is investigated theoretically and experimentally. The deposition rates of Ag and TiO2particles of 8-30 nm in diameter suspended either in N2, Ar or He gas are measured using a circular pipe with a nonuniform wall temperature distribution. The numerical calculation results considering the gas flow, temperature and particle distributions in the pipe show good agreement with the measured values. The particle deposition is enhanced with the increase of the wall temperature variation, but does not depend on the particle material. The difference in the deposition rates among the carrier gases is mostly attributable to the values of the Brownian diffusion coefficient. The enhancement of deposition by thermophoresis is of a similar magnitude among the carrier gases, which is explained in terms of the temperature distribution of the gases in the pipe.