Characteristics of sol-gel derived PZT thin films with lead oxide cover layers and lead titanate interlayers

The set-gel derived PbZr0.53Ti0.47O3 (PZT) films were fabricated on the bare Pt/Ti/SiO2/Si substrates or the same substrates coated by the PbTiO3 (PT) interlayers. The post-deposition annealing temperature and time were optimized when the PbO cover layers and PbO vapour-containing atmosphere were compared with each other and adopted as the method to diminish the lead-loss problem during the high-temperature post-deposition annealing. The X-ray diffraction patterns, microstructures, and electrical properties such as relative permittivity, epsilon(r), remanent polarization, P-r, and coercive electrical field, E(c), were investigated in relation to the annealing conditions. The PZT films deposited on the bare Pt/Ti/SiO2/Si substrates under the PbO vapour-containing atmosphere showed better electrical properties. This indicates that the PbO vapour-containing atmosphere may be the better method of lead-loss-prevention to process the lead-containing films rather than the PbO cover layer method. The electrical characteristics of the PZT films, epsilon(r) = 1150, a dissipation factor of 0.039, P-r = 26 mu C cm(-2), and E(c) = 40.5 kV cm(-1), were measured at 1 kHz. When PZT films were deposited on substrates coated by the PT layers, PZT-PT films with single perovskite phase were derived by post-deposition annealing at 500 degrees C for 1 h. However, the relative electrical properties are very poor, i.e. E(r) = 160, P-r = 2.0 mu C cm(-2) and E(c) = 75 kV cm(-1). The optimum combination for preparing PZT-PT films is a 40 nm PbTiO3 interlayer and annealing conditions of 6 h at 550 degrees C in a PbO vapour-containing atmosphere; the derived films exhibit electrical properties of E(r) = 885, P-r = 21.5 mu C cm(-2) and E(c) = 64 kV cm(-1). The combination of inserting a PT interlayer and annealing in a PbO vapour-containing atmosphere can prevent the formation of electrical short paths. In this case, nearly pin-hole-free PZT films can be grown on the PT (interlayer)/Pt/Ti/SiO2/Si substrates. It is believed that it is possible to prepare the PZT films with nano-scale uniformity, reproducible quality, which may be worth considering for commercial applications.