PRESSURE EFFECTS DURING PULSED-LASER DEPOSITION OF BARIUM-TITANATE THIN-FILMS

The composition and homogeneity of barium titanate films grown by puls ed-laser deposition at different substrate temperatures (room temperat ure, 700 degrees C) and gas environments (O-2, Ar) in a broad pressure range (10(-7)-1 mbar) are correlated to the plasma expansion dynamics . It is found that the deposited films present an excess of Ba in the intermediate pressure range (10(-2) < P < 10(-1) mbar) and a peaked di stribution of Ba to Ti atoms ratio, that is not related to either the substrate temperature or the nature of the gas environment. The result s are discussed in terms of the dependence of the plume length (L-P) O n the gas pressure and the existence of scattering processes for dista nces (d) from the target lower than L-P and the diffusion of the eject ed species for L-P < d.