Low-temperature processing of ferroelectric Pb(Zr0.53Ti0.47)O-3 thin film from molecular-designed alkoxide precursor solution

A novel method is developed for the sol-gel preparation of Pb(Zr0.53Ti0.47)O-3 (PZT) thin films. This method involves the insertion of an in situ crystallizing interlayer film of perovskite lead titanate (PT) as a seeding layer that offers nucleation sites which lower the activation energy for crystallization. Highly crystallized PZT films with the perovskite structure were successfully obtained on Pt-coated silicon wafers and even on silica-glass substrate. The formation temperature of a perovskite single phase in the PZT thin film was effectively lowered to 500 degrees C in air and 450 degrees C in a mixture of water vapor and oxygen. Relative permittivity, epsilon(r), of the resultant films annealed below 500 degrees C increased with increasing film thickness and levelled off at around 1.5 mu m thickness. epsilon(r), saturated at around 500 at 1 kHz. This behavior was compared with those of films prepared by other methods at relatively high temperatures. It was concluded that the molecular design of the alkoxide precursor solution and the use of an in situ crystallizing PT seeding layer were essential for lowering the crystallization temperature as well as for obtaining good electrical properties of the resultant PZT thin films.