Polarization Switching Current Characteristic And Nonlinear Current-voltage Characteristic In PZT Thin Films

Lead Zirconate titanate(PbZr_0.52Ti_0.48O₃,PZT)has been widely valued for its excellent dielectric properties,ferroelectric properties,piezoelectric properties and compatibility with semiconductor processes.As an important ferroelectric material,PZT is widely used in non-volatile memory,dynamic random memory,infrared sensor,and micro actuators.The current characteristics of PZT films were mainly studied in this paper,including polarization switching current characteristics and nonlinear ?-? characteristics.It is of great significance to study polarization switching current for application in FeRAM.Study the nonlinear ?-? characteristics of PZT thin films can promote the applications in the field of varistor materials.The PZT film was prepared by sol-gel method in this paper.In terms of the performance test,the X-ray diffraction and field emission scanning electron microscope were used to analyze the phase composition of the film and the surface morphology,the ferroelectric parameter tester were used to test ferroelectric properties of film tests,the semiconductor parameter analyzer were used to test film ?-? characteristics.In order to study the polarization switching current characteristics of different preferred orientation PZT films,we use an improved annealing technology to prepare PZT films with different preferred orientation.The results showed that PZT films with PbTiO₃?PT?seed layer were randomly and the PZT thin films prepared directly on platinum substrate were?111?preferred orientation.With the improved annealing process,the PZT thin films were directly put into muffle furnace at 400^oC,and heat up to 650^oC,the annealing time is 1 hour.The PZT thin films prepared by this method were highly?111?preferred orientation.?111?-oriented PZT thin film has a large polarization switching current,and the polarization switching current increases with the degree of?111?preferred orientation.The polarization temperature can also influence the polarization switching current of PZT films,the higher the polarization temperature,the larger the polarization switching current.In this paper,the mechanism of the polarization switching current characteristics of PZT is analyzed by the space charge current model?SCLC?combined with ferroelectric domain switching mechanism.As for nonlinear ?-? characteristics of PZT,the PZT threshold voltages are lower than conventional varistor materials and can be easily controlled by process.It is significance for the application in varistor materials of PZT thin film.The experimental results show that the threshold voltages of PZT films increase with the decrease of grain size and the increase of the film thickness.The double schottky barrier model?DSB?and tunneling effect were used to interpret nonlinear ?-? characteristics of PZT thin films.