Isotopic study on metalorganic chemical vapor deposition of manganite films

Abstract

Isotopic labeling experiments using 18O2 were carried out to understand the decomposition and oxidation reactions of source molecules in the metalorganic chemical vapor deposition (MOCVD) of strontium-doped lanthanum manganite films. The isotopic ratios of oxygen incorporated in the deposited films were determined by time-of-flight secondary ion mass spectrometry (TOF-SIMS) in both negative and positive secondary ion detection modes. The obtained M18O+/M16O+ (M=La, Sr, Mn) ratios showed good agreement with the corresponding 18O−/16O− ratios. The oxygen incorporation from the oxidant gas (18O2) to the strontium oxide films is dominant under typical deposition conditions, while the majority of oxygen in the lanthanum oxide films originates from the ligands of the source molecules. In the complex oxide film deposition, an interaction occurred with another metal source molecules in the film deposition reaction. As a result, about three quarters of MO bonds of the original source molecules were preserved in the La0.7Sr0.3MnO3 film formation.