Study Of Properties And Devices Based On Sr-doped PZT Thin Films

Lead zirconate titanate (PZT) has broad applications in micro devices such as micro sensors, micro actuators, ferroelectric memory etc. Element doping can change the properties of PZT thin films. In this paper, Sr-doped PZT thin films have been prepared and their properties have been studied, which include the effects of etching solutions, dielectric properties, leakage current and ferroelectric properties. Microcantilevers with Sr-doped PZT thin films have been fabricated. The sensitivities and the acting capacities of the microcantilevers have been measured.Four different concentrations of Sr-doped Pb_1-xSr_xZr_0.53TiO₃ (x=0, 0.02, 0.04, 0.06) have been prepared by sol-gel method combined with a rapid thermal annealing process on Pt/Ti/SiO₂/Si substrates. Comparing with other four etching solutions, a better etching solution has been obtained which has a modest etching rate and minimized undercut.The XRD patterns show that a single perovskite phase are obtained in four types of the Sr-doped PZT thin films; preferred orientation is changed with the Sr-doping concentration. The surface morphology of Sr-doped PZT thin film is obtained by AFM. The impacts of Sr-doping and electrode areas to the dielectric properties of the PZT thin films are studied. Sr-doping reduces the dielectric constant and the dissipation factor of the PZT thin films. Sr-doping decreases leakage current of the PZT thin films. There are P-E hysteresis loops in all four types of the Sr-doped PZT thin films, and larger remanent polarization and coercive field are obtained at x=0 and x=0.02.Based on the previous work, microcantilevers with Sr-doped PZT thin films are fabricated. The sensitivities of the microcantilevers are obtained by static and quasistatic measurements. It is indicates that Sr-doping decreases the sensitivity of microcantilevers. The displacements of the microcantilever according to different voltage values are measured and the acting capacity of the microcantilever is obtained. The transverse piezoelectric constant e₃₁ of PZT thin film are calculated.