Impact of the processing temperature on the laser-based crystallization of chemical solution deposited lead zirconate titanate thin films on short timescales

Abstract

In this work, the laser-based annealing process of sol-gel-derived piezoelectric PZT53/47 (lead zirconate titanate) thin films deposited on platinized silicon substrates is investigated. A temperature control closed loop is implemented to allow for the measurement and control of the annealing temperature. Samples are treated at temperatures of up to 900 °C and heating rates between 300 and 9000 K/s in ambient conditions. The results show that highly functional PZT thin films can be crystallized at interaction times of less than 1 s while exhibiting a remanent polarization of up to 28  μC/cm2 and a piezoelectric coefficient of up to 49 pm/V. X-ray diffraction analysis shows that an intermetallic Pt3Pb phase forms prior to the formation of phase pure PZT. With decreasing interaction time between the laser beam and the thin film, the temperature range in which this Pt3Pb phase is stable extends toward temperatures as high as 900 °C without the formation of phase pure PZT. Furthermore, a decrease in the interaction time requires higher annealing temperatures to form fully crystalline PZT thin films. Scanning electron microscope images reveal that short interaction times shift the nucleation of the PZT thin films from epitaxial to heterogeneous nucleation. Overall, it is demonstrated that the crystallization time of chemical solution deposited PZT thin films can be reduced significantly by using laser radiation.