Barrier layer mechanism engineering in calcium copper titanate thin film capacitors through microstructure control

Abstract

A peak permittivity greater than 10 000 has been achieved for calcium copper titanate (CCT) thin films by engineering a thin film microstructure that maximizes space charge contributions to polarizability. This permittivity is an order of magnitude greater than previous polycrystalline thin film efforts. This unique microstructure control is accomplished using a chemical solution deposition process flow that produces highly dense parallel layers ∼100 nm in thickness. We observe a thickness dependent permittivity where the entire film thickness constitutes the conducting region of a barrier layer capacitor despite the presence of multiple grain boundaries within that thickness. The model predictions are in good agreement with experimental data and are consistent with existing literature reports. These trends in permittivity with dielectric thickness raise new questions regarding the nature of barrier layers in CCT—and specifically, these results suggest that grain boundaries may not always participate as high resistance interlayers.