Very fast growth of millimeter-tall aligned carbon nanotubes between two stacked substrates coated with a metal catalyst

A simple method is reported for the fast growth of millimeter-tall aligned carbon nanotubes (CNTs). Two silicon substrates were stacked with catalyst layers face to face and CNT growth occurred between them. Based on in situ monitoring, the growth rate of aligned CNTs in stacked area was found to be much (over one magnitude) higher than that in the area with a single substrate. The phenomenon was also valid for different catalyst layers and cap substrate materials. This provided an easy way to improve the efficiency of CNT synthesis without changing catalyst compositions and growth parameters.