Effects of excess PbO and Zr/Ti ratio on microstructure and electrical properties of PZT films

Lead zirconate titanate films with different Zr/Ti ratios were fabricated on a platinized silicon substrate using radio frequency magnetron sputtering. Crack-free films with a rhombohedral, morphotropic phase boundary and tetragonal compositions were deposited using single oxide targets containing various amounts of excess PbO. When the films showed a (111) preferred orientation, there were no cracks, regardless of the phase, and their microstructures were similar to one another. As the Zr/Ti ratio was changed, the amount of excess PbO necessary for the stoichiometry of the films also changed. When they had a stoichiometric composition, the films had a small grain size and similar microstructures. Moreover, their structural stability increased when the grains had an equiaxed morphology. The ferroelectric and piezoelectric properties of the films were characterized and correlated with their phase and microstructure.