Particulate distributions in Pt films prepared by pulsed laser deposition

A quantitative statistical analysis of micron-sized particulates on the 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 relative to the center of the ablation plume, and areal density. The latter quantity is defined as the number of particulates per cm(2) of him surface per nanometer of film thickness. The particulate shape was generally 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 plume center outwards suggesting that particulate reduction by growing films in off-axis regions may be problematic. Increasing the laser fluence from 0.75 to 3.00 J/cm(2) however, resulted in a two order of magnitude reduction in the areal density, although an increase in the average particulate diameter from 0.26 to 0.47 mu m occurred. This result implies that, at least with metals, increasing laser fluence is a pragmatic approach to particulate reduction in laser deposited thin films. (C) 1998 American Institute of Physics.