The effect of a modulated flux on the growth of thin films

Thin films are usually obtained by depositing atoms with a continuous flux. We show that using a chopped flux changes the growth and morphology of the film. A simple scaling analysis predicts how the island densities change as a function of the frequency of the chopped flux in simple cases where aggregation is irreversible. These predictions are confirmed by computer simulations. We show that the model can be used to obtain information on the diffusion or evaporation of the adatoms. The model is also useful for understanding the growth of thin films prepared by pulsed sources. (C) 1997 Elsevier Science B.V.