Size effects on Pb0.5Ca0.5TiO3 thin films

Pb0.5Ca0.5TiO3 thin films with thickness between 80 and 700 nm have been prepared by deposition of sol-gel precursor solutions onto Pt/TiO2/SiO2/(1 0 0)Si substrates and crystallized by rapid thermal processing (RTP). Dielectric measurements with temperature and frequency, and atomic force microscopy (AFM) micrographs have been performed. Two maxima are detected in the curve of variation of permittivity with temperature (K′-T). The AFM images of the films surfaces show a non-dependence of the mean grain size (∼50 nm) with the film thickness. However, relaxor-like properties of the films are dependent on the films thickness. Experimental results and dielectric anomalies observed are discussed in terms of the possible existence of a morphotropic phase boundary (MPB) and the formation of a dead-layer in the films during their processing.