Gas phase equilibrium limitations on the vapor–liquid–solid growth of epitaxial silicon nanowires using SiCl 4

Epitaxially oriented silicon nanowires (SiNWs) were grown on (111) Si substrates by the vapor–liquid–solid technique in an atmospheric-pressure chemical vapor deposition (APCVD) system using Au as the catalyst and SiCl 4 as the source gas. The dependencies of SiNW growth rate on the growth temperature and SiCl 4 partial pressure (P SiCl4 ) were investigated, and the experimental results were compared with calculated supersaturation curves for Si obtained from a gas phase equilibrium model of the SiCl 4 –H 2 system. The SiNW growth rate was found to be weakly dependent on temperature but strongly dependent on the P SiCl4 , exhibiting a maximum value qualitatively similar to that predicted from the equilibrium model. The results indicate that SiNW growth from SiCl 4 is limited by gas phase chemistry and transport of reactant species to the growth surface under APCVD conditions. The experimental results are discussed within the context of a gas phase mass transport model that takes into account changes in equilibrium partial pressure due to curvature-related Gibbs–Thomson effects.