IMPRINT OF ORIENTED PB(ZR, TI)O-3 THIN-FILMS WITH OXYGEN ATMOSPHERE IN COOLING PROCESS

Imprint properties of reactively sputtered Pb(Zr, Ti)O-3 [PZT] thin fi lms were studied as a function of oxygen pressure during cooling after deposition. The well-oriented PZT films had a perovskite phase withou t any second phase regardless of the oxygen cooling ambient. The surfa ce morphology of the PZT films became somewhat rough with decreasing o xygen pressure because of the evaporation from the surface of the PZT films. Grain size, however, did not change significantly. As the oxyge n cooling pressure increased, the hysteresis property of the PZT thin films improved and attained good squareness. The decrease of remanent polarization, retained polarization and the coercive field was observe d with decreasing oxygen pressure. It was observed that as the atmosph ere in the cooling process of PZT films becomes a reducing one, the P- E hysteresis loop shifts to a positive voltage asymmetrically. The dir ection of internal bias field was from the bottom to top electrode, wh ich was confirmed by a field-accelerated retention test. In addition, this field could be diminished by thermal treatment in oxygen atmosphe re.