A case study with a novel geometry for pulsed laser deposition

Aluminium thin films were deposited by a laser ablation technique from solid cylindrical targets rotated on a lead screw. Both smooth-surfaced targets and targets with screw threads cut into the area to be irradiated were used. The targets were irradiated with a focused circular spot size of 2.5 mm in diameter, at a power density equal to 5.4?0.2 ? 108 W cm-2 . The polar distribution of the ablated atomic material was found to vary as a function of the target screw thread pitch, with the exponent n , in the polar distribution f ( ) = cosn , varying from 13.5?1.3 for no pitch to a minimum of 5?0.7 for a screw thread pitch of 0.2 mm. The use of such novel target geometries forms a possible basis for increasing thickness uniformity during the pulsed laser deposition of thin films.