DETERMINATION OF ZINC CLUSTER-SIZE IN IONIZED CLUSTER BEAM FILM DEPOSITION

Ionized cluster beam deposition uses a beam of ionized, accelerated at om clusters to grow thin films. Earlier unsuccessful attempts at formi ng such cluster beams by homogeneous nucleation used 1 mm X 1 mm nozzl es at crucible pressures around 2 Torr. Recently, Gspann [Proc. German Phys. Soc. 3, 387 (1992)] and the authors [Appl. Phys. Lett. 61, 1180 (1992)] produced significant numbers of large zinc clusters by increa sing the crucible pressure to the 1000 Torr range and using a convergi ng-diverging nozzle 18 mm long and 0.4 mm in diameter at the throat. T he cluster distribution for a crucible temperature of 1180-degrees-C p eaked around an average of 2200 atoms per cluster. This distribution w as measured by extending the previous deflected deposition method for average size to apply for the entire ionized fraction of the beam. Clu ster velocity was nearly constant over the entire distribution in agre ement with what would be expected for a homogeneous nucleation process . Over 99% of the ionized beam was in the form of clusters.