MODELING OF ORGANOMETALLIC CHEMICAL-VAPOR-DEPOSITION OF LEAD TITANATE

The growth of lead titanate by organometallic chemical vapour depositi on using the precursors tetraethyllead, tetraisopropoxidetitanium and oxygen, is modelled. An initial partial decomposition of the precursor s is postulated to take place in the gas phase. These partial decompos ed species then diffuse to the surface followed by a dissociative adso rption. The Pb and Ti adsorbates make use of the same sort of adsorpti on site thereby introducing a competitive adsorption mechanism. In a n ext step the adsorbates decompose further and react with adsorbed oxyg en, leading to the formation of intermediate compounds of lead oxide, and titanium dioxide. These individual oxides then either react to for m the lead titanate or are incorporated in the film as such. Desorptio n of the intermediate lead oxide compound is included in the model. Th e model may be used to describe the dependence of the growth rate and the composition of the layer as a function of the deposition temperatu re, precursor and oxygen partial pressures. A reasonable agreement bet ween the model predictions and experimental results is obtained.