Radio frequency magnetron sputtering has been used for the synthesis of aligned carbon nanotubes (CNTs) on SiO2/Si substrate. The results were obtained by depositing catalytic nano-particles in advance (ex situ) or simultaneously to the C deposition (in situ), which have been compared showing that the oxidation of the metal catalyst deposited in advance is detrimental for the good outcome of the CNTs growth. An in situ catalyst deposition allows to get rid of the contamination problem and to grow aligned CNTs on a substrate, as shown by scanning electron microscopy. Transmission electron microscopy shows that the so-achieved CNTs own a bamboo-like structure and the catalytic Ni nanoparticle is on the tip of the CNTs. Our method allows to perform catalyst deposition and growth of CNT on a SiO2/Si substrate simultaneously and its use can be extended to a variety of catalytic elements and substrates, in …