Preparation and application of lead zirconate titanate (PZT) films deposited by hybrid process: Sol-gel method and laser ablation

Among the many ferroelectric film fabrication techniques, the sol-gel process provides high purity, large deposition area and easy composition control. However, the thickness limit of a crack-free single-layer film is about 0.2 μm and about 10 times of coating and thermal treatment processing are needed to deposit 1.5 μm-thick films. In laser ablation, the deposition rate is expected to be 1-2 μm/h, but the film quality is lower than that deposited by the sol-gel method. In this work, the hybrid process, involving the sol-gel method and laser ablation, was used to make 1.65 μm-thick lead zirconate titanate (PZT) films with well-crystallized perovskite phase at the (111) orientation. We deposited (111)-oriented 0.15μm-thick PZT film on Pt/Ti/SiO₂/Si substrates using the sol-gel method and then deposited 1.5 μm-thick PZT films by laser ablation. The remanent polarization of 28.6μC/cm² and the coercive field of 58.0kV/cm were obtained while the dielectric constant and loss values measured at 1 kHz were approximately 1050 and 0.045, respectively. The piezoelectric coefficient d₃₁ was also investigated and found to be 16.65 ± 4pC/N. In the application, a micromirror actuated by the hybrid PZT films was designed and fabricated successfully by a three-mask lithography process. The scanning angle of 6 ± 2 degrees was demonstrated, while resonating with 5 V_p-p at the resonance frequency (1975 Hz).