Microstructure and interfaces of thin film capacitors on base metal foils

Abstract

The microstructure and interface quality of chemical solution deposited barium titanate thin films on Ni foil were studied. Cross-sectional transmission electron microscopy shows that a ∼200 nm thick barium titanate film annealed in a controlled oxygen partial pressure consists of equiaxed grains with grain size range of 24-75 nm (∼ 42 nm average). NiO was detected after re-oxidation by X-ray diffraction, but not by transmission electron microscopy, suggesting that the oxide is not a continuous barrier layer, but is spatially distributed in the films. Oxygen non-stoichiometry and the existence of C in barium titanate films were observed by electron energy loss spectrometry. In addition, it was found that there is a 5-8 nm thick Ni-Ba alloy developed at the interface between the barium titanate film and Ni foil. © 2008 Trans Tech Publications, Switzerland.