Synthesis of cobalt nanoparticles by DC magnetron sputtering and the effects of electron bombardment

Dispersive cobalt nanoparticles are fabricated during deposition on SiO₂/Si (001) substrates by direct current (DC) magnetron sputtering at room temperature. It is found that Co nanoparticles ranging from a few nanometers to some tens of nanometers in diameter can be fabricated by applying positive substrate biases. Larger polycrystalline cobalt nanoparticles are formed by the coalescence from smaller single-crystalline ones which may exist in fcc or hcp phase. Size reduction and uniformity of the nanoparticle array can be further enhanced by applying larger positive biases due to electron charging effects. Under the charging effects, the growth kinetics can be altered from VW to SK-like growth mode.