Lower crystallization temperature of sol-gel PbTiO3 on Ti/Pt-coated substrates

PbTiO3 (PT) thin films have been deposited by sol-gel on Pt/Si, SiO2/Si, Pt/Ti/SiO2/Si, and Ti/Pt/Ti/SiO2/Si and annealed for 45 min in the 400-670 degrees C range. Analysis by x-ray diffraction (XRD) and spectroscopic ellipsometry shows that the Ti overlayer promotes early crystallization in the tetragonal perovskite phase, reducing the presence of a second phase, tentatively identified as pyrochlore, starting by 450 degrees C. The refractive index and extinction coefficient (n, k) of the PT film increase rapidly with the sintering temperature in the range of 450-570 degrees C and saturate by 570 degrees C to values of It varying from 2.4 to 2.9, and k from 0.03 to 0.3, over the 1.65-2.95 eV range. Most of the increase of n is related to thin film densification.