Low-pressure crystallization of sol-gel-derived PbZr _0.52 Ti _0.48 O ₃ thin films at low temperature for low-voltage operation

The properties of sol-gel-derived 120-nm PbZr _0.52 Ti _0.48 O ₃ thin films crystallized in low-pressure O ₂ ambient at 500 °C have been investigated. It is found that PbZr _0.52 Ti _0.48 O ₃ films crystallized in low-pressure oxygen ambient exhibit higher remanent polarization as well as a lower coercive field, compared to those annealed in O ₂ atmosphere. The remanent polarization (i.e., 2P _r ) for samples annealed in 60 mbar O ₂ ambient is as high as 36 μC/cm ² , and the coercive field (2E _C ) is 99.9 kV/cm at an applied voltage of 2 V. The improvement of P-E hysteresis loops by low-pressure oxygen annealing is ascribed to less incorporation of oxygen and other residues in the resultant PbZr _0.52 Ti _0.48 O ₃ films, since the reductions in the amount of these residual species are beneficial for the complete transformation of the perovskite structure. The reductions in oxygen content and amounts of other residues such as CO ₂ and H ₂ O are confirmed based on Auger depth profiles and thermal desorption spectra (TDS), respectively.