Great reduction of particulates in pulsed laser deposition of Ag-Co films by using a shaded off-axis geometry

We have studied the possibility of depositing particulate-free metallic film (Ag-Co) by the pulsed laser deposition (PLD) by implementing the off-axis technique. In the case of PLD silver films, a great production from the target of molten metallic droplets was observed and surfaces of films deposited in the conventional off-axis geometry still presented a large particulate density also at 9 cm substrate-target distance and for a wide range of background gas pressure value, By placing a metallic screen perpendicularly to the substrate in order to intercept the trajectories of the micrometric droplets, a shaded region was created on the substrate holder and the deposit in such region had a particulate density of 0.04 X 10(6) particulates/cm(2), that is, five times lower than particulate density obtained by using an electromagnetic shutter. At the same time, we Verified that an acceptable deposition rate was maintained and that the presence of the screen did not induce undesirable variations of chemical composition. Chemical and thickness homogeneity of the films in the two geometries were compared. (C) 2000 Elsevier Science B.V. All rights reserved.