ELUCIDATION OF THE SWITCHING PROCESSES IN TETRAGONAL PZT BY HYSTERESIS LOOP AND IMPEDANCE ANALYSIS

The switching process in tetragonal PZT films is studied. The ferroele ctric capacitors show rectangular P-E hystersis loops with very abrupt switching characteristics. Small signal impedance measurements as fun ction of DC bias voltage reveal an abrupt drop of the parallel capacit ance C near the switching field E(c), coinciding with a sharp peak of the equivalent parallel conductance G, different from the more gradual variation of C and G with broad peaks near Ec as typically observed i n materials with MPB composition. This behavior is correlated to stron g 180 degrees switching in this tetragonal material. This is further c orroborated by the effects of the film orientation and of electrical a nd stress poling.