SIMS of thin films grown by pulsed laser deposition on isotopically labeled substrates

The oxygen diffusion kinetics in a strontium titanate (STO)–yttria stabilized zirconia (YSZ) heterostructure were investigated by secondary ion mass spectrometry (SIMS) depth profiling of pulsed laser deposited thin films grown on 18 O enriched single crystalline substrates. By annealing for 100 h at 1100 °C in an 18 O 2 enriched atmosphere 18 O concentrations of ~ 81% and ~ 63% were reached in the YSZ, and STO substrates, respectively. The film depositions were performed at different substrate temperatures up to 750 °C and different oxygen background pressures in a range from 1.5 × 10 − 5 mbar to 0.1 mbar to observe differences in the diffusion of the oxygen ions from the substrate into the films. Flat profiles of 18 O were obtained for the YSZ thin films implying a very fast diffusion that determines the isotope distribution during the deposition. For the STO films pronounced concentration profiles were obtained at 650 °C allowing estimations of the diffusion constant. Elemental mapping of the YSZ films revealed pinholes of micron size which are hardly detectable by other techniques.