Cumulative laser irradiation effects on ions in the plume of YBa2Cu3O7−δ and particulates at the film surface

Direct observations of ions in the laser plume of YBa2Cu3O7−δ impinging onto a substrate surface revealed the increase of heavy species in the plume after multiple laser pulses on the YBa2Cu3O7−δ target. The beginning of heavy species emission from the target was observed at around 100 laser beam pulses (1 J/cm2) in our experiments. Particulate formation at the film surface was observed in the film deposited under this condition.