We investigate the growth of the recently demonstrated composite material
composed of vertically aligned carbon nanotubes capped by few graphene layers.
We show that the carbon nanotubes grow epitaxially under the few graphene
layers. By using a catalyst and gaseous carbon precursor different from those
used originally we establish that such unconventional growth mode is not
specific to a precise choice of catalyst-precursor couple. Furthermore, the
composite can be grown using catalyst and temperatures compatible with CMOS
processing (T < 450\degree C).Comment: 4 pages, 4 figure