MODELING OF PULSED LASER ETCHING OF HIGH-TC SUPERCONDUCTORS

Modeling of pulsed laser ablation has been applied to investigate the etching of high-Tc superconducting films of YBa2Cu 3O7-δ and Bi2Sr2CaCu 2O8. Calculations based on solutions to the one-dimensional heat equation and using parameters characteristic of the experiments indicate that diffusion does not play a major role and the dominant process is an evaporation mechanism taking place at the surface. Hence the ablation is modeled by solving the dynamical equations for a very thin heated layer in local equilibrium with the ablated material. With reasonable assumptions for the heat of evaporation (sublimation) and the phase equilibrium curve, the etch depth per pulse can be determined along with a number of other parameters. The results are in accord with observation.