Abstract :
The composition of thin perovskite films, especially the oxygen content, is a crucial parameter which influences many physical properties, such
as conductivity and catalytic activity. Films produced by pulsed laser deposition are normally annealed in an oxygen atmosphere after deposition to
achieve a desired oxygen content. In pulsed reactive crossed beam laser ablation, no annealing step is necessary, but a fundamental question
regarding this deposition technique is still open: where does the oxygen in the films come from?
There are three possibilities, i.e. from the target, from the gas background, or from the gas pulse. To answer this question two experiments were
performed: 18O2 was used during the deposition process as background gas with 16O anions in the target and 16O2 gas pulse, and a 18O2 gas pulse
with 16O from the target and background. These experiments revealed that the quantification of the oxygen origin is only possible, when no oxygen
exchange occurs at the deposition temperature. The films are characterized after deposition by elastic recoil detection analysis (ERDA) to
determine the 16O/18O ratio. Experiments with different oxidizing species in the gas pulse (N2O and O2) confirm that the oxidizing potential
(N2O > O2) as well as the number of molecules are important
