Pulsed Laser Deposition (PLD)

Pulsed laser deposition (PLD) is a physical vapor deposition technique, where laser ablation of the target is used to deposit material from the target on the substrate. When the laser pulse from excimer or solid state laser hits the target, it causes the melting and evaporation of the material from the target. The evaporated material is then in the form of plasma plume transferred onto the surface of the substrate. The kinetics and diffusion properties of the species in the plasma and substrate surface define the adsorption of particles and consequently the film formation. In contrast to molecular beam epitaxy or atomic layer deposition, where the film preparation is slow due to variety of intermediate steps, which ensure the chemical reactions needed for film formation to happen, the PLD method is much faster since the chemical composition of material is transferred from the target onto the substrate, meaning for the film growth we need only the target with desired stoichiometry. For these reasons, the PLD method is attractive for industrial uses also.

Additionally, due to the pulsed laser ablation, where the frequency of the pulses can be controlled, it is fairly easy to precisely control the growth rate of deposited material, which gives us deposition precision on atomic level, constructing few nm thick heterostructures of films, with atomically sharp interfaces. Furthermore, the parameters like substrate temperature, mixture of gases of the background atmosphere and pressure can be adjusted, giving plenty possibilities for synthesis of complex oxide materials and heterostructures, where the film crystal quality can be fine-tuned based on desired functional properties. This offers endless possibilities for first principles scientific research of materials and their properties.

One field in materials science, where PLD has great possibility to exceed in is oxide integration on semiconductors, which is important part of semiconductor industry. Due to the high vacuum in PLD chamber, air sensitive and fast oxidizing materials, such as Si, can be used and oxide thin films can be deposited without formation of silicon oxide at the interface. On top of that the PLD method offers extreme control over the interfaces in heterostructures, defining the electronic and ferroelectric properties, which can be improved with controlled thickness of the films. Furthermore, light and sensitive elements like Li and Li compounds can be successfully deposited in the form of thin film, which is especially promising in manufacturing solid state electrolyte batteries.