The lateral material distribution of laser-deposited YBa2Cu3O7−δ films and the density of droplets coming from the target were studied by varying the laser pulse energy, the laser spot size and the target-to-substrate distance. Silicon wafers at ambient temperature were used as substrates to guarantee a large sticking coefficient of the particles. The deposition rate is found to depend linearly on the laser energy density E and quadratically on the spot size S at the target, whereas the droplet density is slightly dependent on E and increases linearly with 1/S, yielding a threshold energy of 0.9 J cm−2. With a laser spot size of 7.15 mm2 and a laser energy density of 1.2 J cm−2, we were able to reduce the number of droplets to one to two per 500 μm2 for a high quality high film with a typical thickness of 100 nm.
Blank, D. H. A., IJsselsteijn, R. P. J., Out, P. G., Kuiper, H. J. H., Flokstra, J., & Rogalla, H. (1992). High-Tc thin films prepared by laser ablation: material distribution and droplet problem. Materials science & engineering B, 13(1), 67-74. https://doi.org/10.1016/0921-5107(92)90106-J