Excimer laser sputtering of mica surfaces: Mechanisms and applications

The influence of excimer laser irradiation (193 nm, 20 ns pulses and 248 nm , 20 ns and 500 fs pulses) on the structure and morphology of plain and gol d-film coated mica surfaces has been investigated for fluences between 8 mJ /c(2) and 19 J/cm(2). Surfaces treated with laser fluences below the ablati on threshold (lambda=248 nm) are well suited for controlled growth of metal lic films, whereas above-threshold treated samples (lambda=193 nm) form rou ghened surfaces with close-packed arrays of cones. The cone generation can be suppressed by appropriate choice of laser parameters, resulting in the f ormation of ablation holes with micrometer precision. The same precision ca n be obtained in ultrathin metallic films without destroying the underlying mica surface. Low-energy electron diffraction is used to monitor laser-ind uced microscopic changes of the mica surface upon low-fluence irradiation. It is seen that the first step of the ablation process includes reorientati on of dipole domains on the surface. Thereafter, scanning electron microsco py reveals melting of the surface and the onset of explosive sputtering pro cesses. Studies of the ablated products by the use of quadrupole mass spect rometry, quartz microbalance, and photoimaging indicate large kinetic energ ies and a high directionality of the ablated products. (C) 1999 American In stitute of Physics. [S0021-8979(99)04617-4].