Applied Surface Science, Vol.252, No.13, 4642-4646, 2006
Pulsed reactive crossed beam laser ablation of La0.6Ca0.4CoO3 using O-18 - Where does the oxygen come from?
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: O-18(2) was used during the deposition process as background gas with O-16 anions in the target and O-16(2) gas pulse, and a O-18(2) gas pulse with O-16 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 O-16/O-18 ratio. Experiments with different oxidizing species in the gas pulse (N2O and O-2) confirm that the oxidizing potential (N2O > O-2) as well as the number of molecules are important. (c) 2005 Elsevier B.V. All rights reserved.