LASER ABLATION PROCESS FOR FABRICATION OF Y1Ba2Cu3Ox THIN FILM

Abstract

For understanding the laser ablation process, the interaction between the laser beam and the target, the motion of plasma species under the various conditions, and the correlation between the film properties and the behavior of plasma species are investigated. It is suggested that by laser irradiation an energetic plasma is formed above a target and an expansion of the plasma species continuously occurs converting thermal energy to translational energy. Plasma species expand forward, colliding with ambient oxygen and lead to a formation of a shock front far from the target. Plasma temperature and the density are drastically increased due to the shock front formation. These phenomena affect film properties such as film growth orientation and surface morphology. Preferential orientation of thin films can be related with the kinetic energy of species impinging the substrate and it is found that the nucleation of outgrowths on film surfaces increases at higher oxygen pressures at which the shock front is generated above the target.