Imprint of Oriented Pb(Zr, Ti)O 3 Thin Films with Oxygen Atmosphere in Cooling Process

Abstract

Imprint properties of reactively sputtered Pb(Zr, Ti)O3 [PZT] thin films were studied as a function of oxygen pressure during cooling after deposition. The well-oriented PZT films had a perovskite phase without any second phase regardless of the oxygen cooling ambient. The surface morphology of the PZT films became somewhat rough with decreasing oxygen pressure because of the evaporation from the surface of the PZT films. Grain size, however, did not change significantly. As the oxygen 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 observed with decreasing oxygen pressure. It was observed that as the atmosphere in the cooling process of PZT films becomes a reducing one, the P–E hysteresis loop shifts to a positive voltage asymmetrically. The direction of internal bias field was from the bottom to top electrode, which was confirmed by a field-accelerated retention test. In addition, this field could be diminished by thermal treatment in oxygen atmosphere.