Growth carbon nanotubes directly on pristine silicon substrates

It is believed that carbon nanotubes were not able to grow on silicon substrates by chemical vapor deposition from a mixture of ferrocene and xylene. This is because iron particles (formed by the decomposition of ferrocene) reacted quickly with silicon to form a discontinuous layer (> 100 nm) of FeSi2 and Fe2SiO4 particles. We report, in this letter, that by controlling the growth kinetics, aligned carbon nanotubes could be grown on pristine silicon substrates. The reason is that appropriate growth conditions could slow down and suppress the reaction within the very surface region to form an almost continuous thin layer (< 10 nm) of Fe2SiO4 particles; thus preventing further reaction and leaving a number of iron particles still active to catalyze the growth of carbon nanotubes. The structure and field emission properties of the nanotubes were also investigated.