Dependence of ablation threshold and LIPSS formation on copper thin films by accumulative UV picosecond laser shots

Abstract

International audienceThe ablation threshold and Laser-induced periodic surface structure (LIPSS) formation on copper thin film were investigated using a picosecond laser (Nd:YAG laser: 266 nm, 42 ps, 10 Hz). We show that the ablation threshold varies with respect to the number of laser shots (N) on two different substrates. The single-shot ablation threshold was estimated to be close to 170 ± 20 mJ/cm2. The incubation coefficient was estimated to be 0.68 ± 0.03 for copper thin films on silicon and glass substrates. In addition, morphology changes of the ablated regions, in the same spot area, were studied as a function of fluence and number of laser shots. An intermediate structure occurred with a mix of low spatial frequency LIPSS (LSFL), high spatial frequency LIPSS (HSFL) and regular spikes at a fluence F \ 250 mJ/cm2 and 1,000 \ N B 10.000 shots. LSFL was observed with a spatial period close to the irradiation wavelength and an orientation perpendicular to the laser polarization, and HSFL with a spatial period of *120 nm and a parallel orientation. Lastly, the global relationship between the laser parameters (i.e. fluence and number of shots) and LIPSS formation was established in the form of a 2D map

Membrane patterned by pulsed laser micromachining for proton exchange membrane fuel cell with sputtered ultra-low catalyst loadings

“…The period of the observed structures is much smaller that the laser beam wavelength (from 265 to 500 nm, against 790 nm for the beam wavelength). Such a small period has already been reported in the literature [31,32] for metal surfaces Dark periodic circular areas (diameter of about 15 µm) appear on this micrograph and correspond to the laser spots but no visible craters were produced after a single laser pulse. No laser scanning was carried out here, a single area was irradiated.…”

SERS Studies Of Explosive Molecules With Diverse Copper Nanostructures Fabricated Using Ultrafast Laser Ablation

“…It was confirmed that the electron-phonon coupling constant is directly related the electron and lattice temperatures, and these temperatures in turn depend on the fluence incident on the target surface. The input laser fluence should be more than the ablation threshold fluence that could melt the sample surface to generate periodic structures and the earlier reported ablation threshold fluence for Cu was 1.7±0.2 J/cm 2 [40]. Following some of the previous reports we understand that the shape of the periodic surface structures change with respect to laser fluence and number of pulses.…”

Advanced laser scanning for highly-efficient ablation and ultrafast surface structuring: experiment and model

“…A calculation by Equation ( 9 ) yields the accumulation coefficient S = 0.70 ± 0.01. The literature values for the accumulation coefficient are: S = 0.77 (1064 nm, 10 ps, 50 kHz) 42 ; S = 0.79 (1064 nm, 10 ps, 50 kHz) 33 ; S = 0.68 (266 nm, 42 ps, 10 Hz) 59 ; S = 0.75 (800 nm, 30 fs, 1 kHz) 60 . The accumulation coefficient measured in our work coincides well with the results from other groups.…”