Pulsed Laser Deposition History and Laser-Target Interactions

Abstract

The laser, as a source of “pure” energy in the form of monochromatic and coherent photons, is enjoying ever increasing popularity in diverse and broad applications from drilling micron-sized holes on semiconductor devices to guidance systems used in drilling a mammoth tunnel under the English Channel. In many areas such as metallurgy, medical technology, and the electronics industry, it has become an irreplaceable tool.Like many other discoveries, the various applications of the laser were not initially defined but were consequences of natural evolution led by theoretical studies. Shortly after the demonstration of the first laser, the most intensely studied theoretical topics dealt with laser beam-solid interactions. Experiments were undertaken to verify different theoretical models for this process. Later, these experiments became the pillars of many applications. Figure 1 illustrates the history of laser development from its initial discovery to practical applications. In this tree of evolution, Pulsed Laser Deposition (PLD) is only a small branch. It remained relatively obscure for a long time. Only in the last few years has his branch started to blossom and bear fruits in thin film deposition.Conceptually and experimentally, PLD is extremely simple, probably the simplest among all thin film growth techniques. Figure 2 shows a schematic diagram of this technique. It uses pulsed laser radiation to vaporize materials and to deposit thin films in a vacuum chamber. However, the beam-solid interaction that leads to evaporation/ablation is a very complex physical phenomenon. The theoretical description of the mechanism is multidisciplinary and combines equilibrium and nonequilibrium processes. The impact of a laser beam on the surface of a solid material, electromagnetic energy is converted first into electronic excitation and then into thermal, chemical, and even mechanical energy to cause evaporation, ablation, excitation, and plasma formation.

Film growth mechanisms in pulsed laser deposition

“…In the proper ablation regime, ionized and neutral ablation products having kinetic energies in the range from less than one to a few hundred eV can be produced [4][5][6]. The variable kinetic energy can be used to study a variety of phenomena such as enhanced lowtemperature epitaxy and surface segregation/incorporation reactions.…”

Elastic Behaviour and Internal Friction Studies on Ni-Zn Ferrite Films Prepared by Using the Pulsed Laser Ablation Method

“…But, the advantages of laser ablation techniques [8,9] include the high kinetic energy of the emitted particles and good stoichiometry of the fabricated film. The Pulsed Laser deposition (PLD) method was successfully used to deposit thin films of Li-Zn ferrites [10], YIG [11], nickel ferrites [12][13][14], Dy iron garnet [15], zinc ferrite [16], and Ni-Zn ferrites [15,17], Liferrite [18], MnFe 2 O 4 [19], barium ferrites [20], Cd 1Àx Mn x Te [21] and high temperature superconducting YBCO [22,23].…”

Ultrasmooth Gold Films via Pulsed Laser Deposition

“…[16][17][18] The instantaneous deposition fl ux can be controlled independently by varying the kinetic energy of the ablated species, the average growth rate, or the average atomic mobility. A relatively high deposition rate, typically hundreds of Å/min, can be achieved at moderate laser fl uencies ranging from laser energies of 100-150 milli-Joules (mJ); fi lm thickness is controlled in real time by dictating the number of laser pulses that hit the target.…”