Observations of sol-gel deposited lead zirconium titanate films using transmission electron microscopy and X-ray diffraction

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Abstract
The microstructure of sol-gel PbZr x Ti1-x O3 (PZT) thin films has been reported to depend strongly-upon deposition and thermal processing conditions. In this paper we describe two systematic series in which the thermal treatment of PbZr0.3Ti0.7O3 films on Pt/Ti/SiO2/Si substrates is varied. The films are deposited by repeated spin depositions and anneals, and consist of eleven individual layers of PZT. We find that we can obtain single phase perovskite layers at processing temperatures above 500°C. At 500°C and a 150s anneal for each depositions only partial transformation of the layer occurs. Some regions have nucleated or transformed more readily than others, leading to the formation of ‘rosettes'. Small changes in the temperature ramp have a large effect on the degree of crystallographic texture of the films. This is correlated with changes in the structure of the Ti layer below the Pt, and is a result of changes in the nucleation rate of different crystallographic orientations of PZT on the Pt. Evidence for an interfacial phase, with lattice parameter approx 10 Å, is presented.