Structure Development Study of Pb (Zr, Ti)O3 Thin Films by an Optical Method

Lead zirconate titanates (Pb (Zr_xTi_1–x)O₃ or PZT) are well-known materials with useful ferroelectric properties for nonvolatile memory applications. The device applications usually require processes which form the ferroelectric perovskite phase at low temperatures. Understanding the various aspects of structure development of PZT films is the key to develop low-temperature processes. An effective, versatile, and nondestructive optical method was developed for the study of the structure development in PZT films. Also, models for the structure development were proposed and were verified by this optical method. Using this method, the characteristic temperatures at which both pyrochlore phase and perovskite phase are initiated and completed were identified. The pyrochloreperovskite transformation was initiated at lower temperature and completed faster for the films on the titanium-rich side than those on the zirconium-rich side. In addition, the volume fractions of the perovskite phase were obtained as a function of annealing temperature by this optical method.