Melting and damage of aluminum surfaces by 80 ps KrF laser pulses

Abstract The melting and damage of aluminum films, coated onto silicon wafers, by 80 ps krypton fluoride laser pulses has been experimentally and numerically investigated. Scanning electron microscope pictures of the damaged surface show that it was covered with small hemispherical-like structures which may be related to expansion of the rapidly heated solid and liquid states. Density perturbations of the liquid layer may result as a consequence of its rapid acceleration and deceleration caused by rapid heating and cooling. In addition, experimental measurements of time resolved and time integrated specular reflectivity from the surface during irradiation are reported. A significant change in specular reflectivity was observed that can be identified with the onset of melting and damage.

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