Thermal analysis for low temperature synthesis of oxide thin films from chemical solutions

Abstract

The possibility of synthesizing functional oxide thin films at low temperature via combustion synthesis is analyzed both experimentally and numerically. To this aim, the decomposition of several oxide precursors [copper and cerium acetates, yttrium trifluoroacetate, and In2O3 and La0.7Sr0.3MnO3 (LSMO) nitrate based precursors] has been analyzed by thermal analysis techniques. It is shown that, although these precursors decompose via combustion when they are in the form of powders, their corresponding films show no evidence of combustion. The reason for this different behavior is clearly revealed with numerical simulations. Thin films will hardly experience combustion because the precursor front extinguishes before reaching the precursor-substrate interface leaving a "cool zone" hundreds of micrometers thick. In contrast, it is argued that thin oxide films can be obtained at temperatures lower than powders because of the enhanced gas transport mechanisms that usually limit the decomposition rate