Monodispersive Cr cluster formation by plasma-gas-condensation method

Nanometer-sixed Cr clusters in the size rage of 8.5-13 nm have been produce d by a plasma gas condensation-type cluster deposition apparatus, which com bines a glow-discharge sputtering technique with an inert gas condensation technique. We have studied the effects of sputter power, Ar gas pressure, P -Ar, and Ar gas flow rate, V-Ar, on the size distribution of Cr clusters by transmission electron microscopy. The cluster size is insensitive to the s putter power, while the nucleation process is promoted when the sputter pow er is increased. Monodispersive Cr clusters are formed at both low P-Ar and low V-Ar, where the nucleation and growth processes are definitely separat ed, and the coagulation of growing particles is prohibited. In the present experiments, these conditions are effectively attained by the use of a carr ier gas flow and liquid nitrogen cooling of the cluster growth region.