The role of an interface on Ni film removal and surface roughness after irradiation by femtosecond laser pulses

Abstract

We have observed thin film removal from glass substrates after the irradiation of Ni films with femtosecond laser pulses in air. It was found that the material removal threshold and laser-induced morphology are dependent on film thickness. With decreasing thickness, material removal transitions from intra-film separation to removal at the Ni-glass interface. The Gaussian energy distribution of the laser pulse allows for intra-film separation in the annular region of the crater and interface separation in the center. We propose a model to explain these data as well as the observed increased surface roughness in the interfacial removal regions.