ABSTRACT
Shortly after the discovery of the laser, researchers began focusing their lasers at materials to observe the interaction. Smith and Turner [1] were amongst the very first to irradiate materials for the purpose of thin film growth. In their study they observed some of the qualities that make pulsed laser deposition (PLD) one of the main advances of the last two decades in the field of laser material processing. A review of the PLD technique and examples of selected applications are presented in this section. Due to the inherently short duration of pulsed lasers, even modest energies of the order of hundreds of mJ, when focused, correspond to enormous peak power levels from megawatts cm−2 for nanosecond lasers to gigawatts cm−2 and terrawatts cm−2 for picosecond and femtosecond laser pulses, respectively. Any material, even those that absorb poorly at the wavelength of the incoming photons, when irradiated at such high laser intensities will be almost instantaneously heated beyond their boiling temperature and a vaporization process will subsequently be initiated from the surface. The interaction of the laser pulse with the vaporized particles can even create a dense plasma plume containing highly energetic ions, neutral atoms and electrons. Regardless of the incoming direction of the initial laser pulse, the plume expansion will be highly forward-directed with the distribution centred normal to the local target surface. The ejected material contained in the plume (predominantly atoms, ions and small molecules) is then incident on a substrate located typically between 3 and 10 cm in front of the target. Figure D1.8.1 presents a photograph and schematic diagram of the basic components in the laser-solid interaction for pulsed laser deposition.
