PARTICULATE DISTRIBUTIONS IN PT FILMS PREPARED BY PULSED-LASER DEPOSITION

A quantitative statistical analysis of micron-sized particulates on th e surface of oriented platinum thin films prepared on [100] MgO at 450 degrees C was made. The particulates, resulting from nanosecond laser ablation, were evaluated as a function of laser fluence (0.75-3.00 J/ cm(2)) to determine the average diameter, spatial distribution relativ e to the center of the ablation plume, and areal density. The latter q uantity is defined as the number of particulates per cm(2) of him surf ace per nanometer of film thickness. The particulate shape was general ly spherical with a diameter range of similar to 0.05-1.0 mu m. For a given laser fluence, the areal density was roughly constant from the p lume center outwards suggesting that particulate reduction by growing films in off-axis regions may be problematic. Increasing the laser flu ence from 0.75 to 3.00 J/cm(2) however, resulted in a two order of mag nitude reduction in the areal density, although an increase in the ave rage particulate diameter from 0.26 to 0.47 mu m occurred. This result implies that, at least with metals, increasing laser fluence is a pra gmatic approach to particulate reduction in laser deposited thin films . (C) 1998 American Institute of Physics.