NEUTRAL AND NEGATIVE-ION CLUSTER EMISSION DURING SPUTTERING

There is a lack of a generally accepted model for polyatomic cluster formation under ion bombardment. A series of correlated investigations of cluster formation during graphite, silicon, and aluminum sputtering by alkali metal ions is carried out to obtain new information concerning cluster formation mechanisms. The relative distribution of polyatomic negative and neutral clusters was investigated and the cluster yield determined as a function of the primary ion energy. The ionization coefficients beta(n) for sputtered carbon, silicon, and aluminum clusters were determined through post ionization of the neutral components. The effect of work function changes on the negative ion cluster yields was also studied. The results show that clusters mainly leave the sputtered surface as such.