Isotopic study of metalorganic chemical vapor deposition of (Ba, Sr)TiO3 films on Pt

Isotopic labeling experiments (18O2) have been carried out to understand the film-formation reactions in the metalorganic chemical vapor deposition of (Ba, Sr)TiO3 (BST) films. Time-of-flight secondary ion mass spectrometry reveals both M 18O and M 16O (M=Ba, Sr, Ti) in the BST films, indicating that the oxygen in the BST films originates from both the gas phase oxidants (18O), and the precursor ligands (16O). Use of a 50% 18O2-50% N2 16O mixture results in a reduction of 18O incorporation in the BST film, indicating direct involvement of N2O in the film-formation reactions. Addition of N2O in O2 also appears to improve film surface morphology and step coverage.