Influence of particle adsorption probability on the stoichiometry of thin films grown by pulsed laser deposition

An expansion of a bicomponent laser plume into a dilute ambient gas is simu lated using a combined direct simulation-random trajectory Monte Carlo meth od. The stoichiometry of thin films deposited from laser-desorbed material on a flat substrate is examined. In the case of energy-dependent particle a dsorption probability, the dependencies of deposition rate on the backgroun d pressure are shown to be nonmonotonic with maximums at low gas pressure. In addition, an increase in the ratio of light to heavy species was obtaine d at low pressure. We demonstrate that these results can be attributed to t he interplay between the effects of collisions with the background gas on t he fluxes of particles arriving at the substrate and on the adsorption prob ability of the species. The calculation results are consistent with recent experiments. The study is of interest for the optimization of the experimen tal conditions during pulsed laser deposition of multicomponent materials. (C) 2001 American Institute of Physics.