Influence of carrier gas on the nucleation and growth of Nb nanoclusters formed through plasma gas condensation

Niobium nanoclusters with an average diameter from 2 nm to 10 nm were produced using a plasma gas condensation process. Cluster size and concentration can be tuned by controlling the sputter source current, aggregation length, and gas flow rate. In this paper, the effects of the addition of helium to the cluster growth process will be examined. Process parameters do not affect the cluster formation and growth independently; their influence on cluster formation can be either cumulative or competing. The results from the helium flow rate dependence study emphasize the competing mechanism present during these processes. Examining the nucleation and growth over a wide combination of parameters provided insight into their interactions and the impact on the growth process. This knowledge will enhance the ability to create nanoclusters with desired size dispersions. (C) 2014 American Vacuum Society.