Pulsed laser ablation and deposition of thin films

Abstract

Pulsed laser ablation is a simple, but versatile, experimental method that finds use as a means of patterning a very diverse range of materials, and in wide areas of thin film deposition and multi-layer research. Superficially, at least, the technique is conceptually simple also, but this apparent simplicity hides a wealth of fascinating, and still incompletely understood, chemical physics. This overview traces our current physico-chemical understanding of the evolution of material from target ablation through to the deposited film, addressing the initial laser-target interactions by which solid material enters the gas phase, the processing and propagation of material in the plume of ejected material, and the eventual accommodation of gas phase species onto the substrate that is to be coated. It is intended that this Review be of interest both to materials scientists interested in thin film growth, and to chemical physicists whose primary interest is with more fundamental aspects of the processes of pulsed laser ablation and deposition.

Comparing the short and ultrashort pulsed laser ablation of LiF

“…The long time ͑t = 800 ns͒ attenuation profile is much closer to the shifted Maxwellian velocity distribution that is characteristic of most ablation plumes. 3 Figure 10 shows a plot of the centers of gravity ͑͗x͒͘ of the deduced attenuation profiles as a function of t. Such a plot of propagation distance versus time should pass through the origin; the long time measurements thus correspond to a mean propagation velocity ͗v͘ϳ8.5 km/ s but, clearly, the deduced ͗x͘ values at early t appear to be too large. This apparent deviation from the (expected) constant expansion velocity, and the seemingly unphysical nature of the ground state velocity distribution implied by the attenuation profiles derived at short t, both highlight a shortcoming of the preceding analysis-namely the assumption that the Li a emission is immune to the effects of self-absorption.…”

“…However, a detailed understanding of the ablation process has proved elusive due to the plethora of mechanisms for the removal of target material, the complex nature of the initial laser-target interaction, and the dynamic nature of the interaction between the plume and the laser pulse. [1][2][3] This complexity is further increased when considering the ablation of materials that are nominally transparent to the laser photons.…”

Infrared Laser Ablation Sample Transfer for MALDI and Electrospray

“…All of these ejected materials could be captured by the suspended droplet and contribute to the resulting MALDI or ESI signal. Microscopy studies of material collected as thin films on solid targets could help to quantify the ratio of free to particulate material ejected from samples by laser ablation [51].…”

Phosphorus carbides: theory and experiment

“…T sub , of course, cannot affect the ablation event, but it can affect the surface mobility of particles that impact on the substrate, and the relative propensities of their, for example, accommodating, bonding and/or re-bounding back into the gas phase. 29, 30 The observed decrease in P : C ratio in P-DLC films grown at higher T sub may indicate that P atoms are accommodated less efficiently than C during the film growth process. 17 Fig .…”