Spectroscopic ellipsometry studies on ion beam sputter deposited Pb(Zr, Ti)O 3 films on sapphire and Pt-coated silicon substrates

Abstract

Spectroscopic ellipsometry has been utilized to non-destructively depth profile multi-ion beam reactively sputtered lead zirconate titanate films. Some degree of inhomogeneity (in the form of low density layers or surface roughness) was found in all of the films examined. The evolution in the structure and microstructure of such films during post-deposition annealing was investigated with in situ spectroscopic ellipsometry. It was found that the onset of microstructural inhomogeneities was associated with the crystallization of the perovskite phase, and that the final film microstructure was dependent on the details of the annealing process. A model was developed to approximate the effect that local density variations play in determining the net electrical properties of ferroelectric films. Depending on the configuration of the embedded porosity, it was demonstrated that microstructural inhomogeneities can significantly change the net dielectric constant, coercive field, and remanent polarization of ferroelectric films. It has also been shown that low density regions near the film/substrate interface can result in apparent size effects in ferroelectric films.