Effect of oxide overlayer formation on the growth of gold catalyzed epitaxial silicon nanowires

Abstract

A direct dependence between the inadvertent formation of SiO2 on gold films deposited on silicon 111 substrates, and the nucleation and yield of epitaxial, gold catalyzed, silicon nanowires grown on such substrates is reported. The unintended SiO2 layer formed due to the diffusion of silicon from the underlying substrate through the gold film is observed to be 0.5 nm with medium energy ion scattering after brief exposures of 10–15 min in air. Silicon nanowires grown at 500 °C on such samples show reduced nucleation and growth. A remarkable improvement in nanowire nucleation density and epitaxy is observed on removing the SiO2 overlayer prior nanowire growth.