Pulsed Laser Deposition (PLD) is a physical vapour deposition technique in which a high-power pulsed laser beam is focused onto a target material. This material vaporizes into a plasma plume which expands away from the target and condenses onto a substrate as a thin film. This process occurs in ultra-high vacuum or in the presence of a background gas. Oxygen is commonly used when depositing oxides to fully oxygenate the deposited films.
As PLD is based on material ablation with a high power laser, the technique has proven to be very useful for the deposition of high melting point ceramics or (complex) metal oxides, which opened up a wide field of thin film materials science research. In the beginning of the nineties PLD underwent a tremendous progress and gained much popularity with the thin film synthesis of high-Tc superconducting YBCO. Herewith it was shown that in PLD near stoichiometric transfer of the target composition occurs, even for multi-element oxides. In later years, the development of high pressure RHEED led to an improved control over single crystal surface termination and growth on atomic level, as well as new growth manipulation techniques like pulsed laser interval deposition. At present, highly epitaxial growth and atomically sharp interfaces can be achieved in the growth of complex oxide heterostructures.
While the basic setup is simple relative to many other deposition techniques, the physical phenomena of laser-target interaction and film growth are quite complex. When the laser pulse is absorbed by the target, energy is first converted to electronic excitation and then into thermal, chemical and mechanical energy resulting in evaporation, ablation, and the formation of the plasma plume consisting of many species including neutrals and ionized particles. Depending on the background gas environment, laser spot characteristics, substrate temperature etc, species thermalise, oxidise and form a thin film with specific structure, morphology and properties. These many growth parameters that can be set and tuned have been the focus of many fundamental studies focussing on improved understanding and optimisation of thin film growth. Besides these many optimisation studies, PLD is nowadays widely used for the growth of high quality thin films and heterostructures for investigation, thereby combining a wide range of interesting material properties.
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