A case study with a novel geometry for pulsed laser deposition

Aluminium thin films were deposited by a laser ablation technique from soli d cylindrical targets rotated on a lead screw. Both smooth-surfaced targets and targets with screw threads cut into the area to he irradiated were use d. 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 x 10(8) W cm(-2). The polar distribution of the ablated atomic material was found to vary as a fu nction of the target screw thread pitch, with the exponent n, in the polar distribution f(theta) = cos(n) theta, varying from 13.5 +/- 1.3 for no pitc h 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 thicknes s uniformity during the pulsed laser deposition of thin films.