Since the observation of carbon nanotubes (CNTs), a window to new technological areas has been opened. Lots of interests have been manifested because of their outstanding properties and the future applications they can provide. That's the reason why the ?Edifices Nanométriques ? group in Laboratoire Francis Perrin has developped research activities based on developpement of the aerosol-assisted CCVD method for the synthesis of long and aligned carbon nanotubes. The aim of this work is focused on the improvement of the aerosol-assisted CCVD method for the synthesis of aligned nanotubes exhibiting smaller diameters leading to aligned SWNT carpets formation while keeping a high growth rate. In a first part, to achieve this goal a better control of the gas phase homogeneous nucleation step should be performed. Synthesis temperature, catalyst precursor concentration or nature of the gas will be examinated. Moreover, in-situ experiments will be carried using the specific furnace developped during the ANR Alucinan for the use of different light beams analyses techniques