Ri. Tomov et al., EXPERIMENTAL AND THEORETICAL INVESTIGATION OF CUMULATIVE LASER IRRADIATION EFFECTS IN YBCO THIN-FILM PULSED-LASER DEPOSITION, Physica. C, Superconductivity, 274(3-4), 1997, pp. 187-196
Compositional and morphological modifications of superconducting YBCO
targets under prolonged laser irradiation were investigated by EDS and
SEM. Rotated and fixed targets were ablated at different process para
meters - laser fluence and oxygen environment. Optical emission spectr
oscopy was employed for investigation of the evolution of the laser-in
duced plasma plume. The deposited film thickness distribution over the
substrate surface area was examined through the film absorbance. The
results can be consistently explained by assuming the existence of an
additional effective ablation threshold imposed by the modified surfac
e relief. A one-dimensional theoretical model of the laser beam-target
interaction was developed involving temperature-dependent thermophysi
cal parameters and the laser-induced plasma absorption. Reasonable agr
eement between the experimental and theoretical dependencies of the er
oded depth per shot on the pulse energy is found. The model results sh
ow a possible influence of the post-pulse evaporation on the target su
rface stoichiometric deviation found in the experiments.