GROWTH AND CHARACTERIZATION OF PZT FILMS WITH DIFFERENT GRAIN SIZES

Abstract

ABSTRACT Pb(Zr0.55Ti0.45)O3 (PZT) thin films with different grain size have been fabricated by controlling the post-annealing process. PZT thin films nucleated at 550°C and the grains began growing above 650°C. Long nucleation process time but relatively short growth process time resulted in small grain. In contrast, long growth process time but short nucleation process time resulted in large grain size. PZT thin films with different grain size show different electrical properties. The polarization increases with the increase of grain size. However, the coercive field exhibites a paraboliclike relationship with grain size. The coercive field increases with the increase of grain size below 70 nm, whereas decreases as the grain size increases above 70 nm. The grain size of 70 nm is thought to be the critical size for the domain structure transition. While increasing the grain size, PZT thin films experience a transition from single domain state to multi domain state, which is related to the polarization switching. It is well known that the polarization of ferroelectric thin films with multi domain structure switches much easier than that with single domain structure. Obviously, the coercive field dependence on the grain size is interpreted.