Mechanism of neutral cluster beam deposition

Pb cluster based films have been formed by the low energy neutral cluster beam deposition method and characterized by TEM. The deposits are rigid, uniform with the nanometer grain sizes, which are important for nanostructured material applications. The velocities of clusters in the beam obtained by gas aggregation method have been calculated based on the hydromechanic and thermodynamic principles. It is demonstrated that the deposition of the clusters on the substrate surface is a head-on collision and soft landing process, that is, low energy clusters land on the substrate surface without fragment and distortion. Based on these analyses, a physical model has been developed and computer simulations have been performed by assuming the random deposition as well as limited diffusion and coalescence process. The results indicate that the uniform and nearly random stacking properties of the cluster deposits can be described properly by the model. (C) 1998 Published by Elsevier Science B.V.