Laser ablation of a Cu–Al–Ni combinatorial thin film library: analysis of crater morphology and geometry

Abstract

The conventional approach to studying laserworkpiece interaction in the ablation regime is to vary beam parameters used on a specimen of uniform chemical composition. The current work instead utilises a pulsed laser beam of constant parameters to ablate a ternary alloy thin film where the chemical composition of the sample varies continuously; this will enhance the understanding of pulsed laser ablation by means of a combinatorial approach. The analysis of the studied workpiece (a Cu-AlNi thin film deposited by magnetron sputtering) revealed the presence of both compositional and morphological gradients. Variation in the surface morphology was correlated with aluminium content. Single-pulse laser ablation (Nd:YAG, 1064 nm, 30 ns, 4.54 J/cm 2 ) of the surface resulted in different crater features, geometry and volume. Two characteristic regions separated by a transition zone were identified based on the craters' geometrical and morphological characteristics. The ablated volume increases with the atomic percentage of aluminium up to a threshold value of roughly 30 at.% after which the ablation volume slowly declines. This phenomenon may be attributed to plasma absorption and heat dissipation in the thin film.

Prediction of Crater Size in Drilling and Texturing by Pulsed Laser Ablation

“…Crater dimensions have been studied using analytical models [7], but repetitive application of successive pulses is relatively scarcely studied [8]. The material is molten and ejected from the region of interaction with the laser due to reaction pressure and/or to the auxiliary gas flow [9].…”