Reduction in particle density of laser-deposited YBa₂Cu ₃O₇ thin films by low-energy ultraviolet radiation

The effect of nanosecond pulsed excimer laser irradiation on the particle distribution and density of laser-deposited YBa₂Cu₃O ₇ thin films was investigated. High-T_C YBa ₂Cu₃O₇ superconducting thin films with thicknesses varying from 800 to 2000 Å were deposited on (100) LaAlO ₃ and (100) yttria stabilized zirconia substrates. The as-deposited films were characterized by a distribution of particles on the film's surface. The effect of controlled low energy density pulses (fluence, E=50-250 mJ/cm ², wavelength λ=248-308 nm, and pulse duration τ=20-45×10^-9 s) on these films was investigated. A significant reduction of particles was observed in films after single pulse irradiation at fluences below 150 mJ/cm². Multiple pulses did not have any further change on the surface morphology. The possible mechanisms for particle removal are also discussed.