Ferroelectric properties of nano-size PZT grains determined by surface potential utilizing Kelvin force microscopy

An attempt has been made in this work to evaluate the ferroelectric properties of PZT grains by monitoring their surface potential using scanning probe microscopy (SPM). The variations of hysteretic and retention properties were compared as a function of grain size. The smaller grain yields lower value of the surface potential than the larger grain does at the same write voltage. However, the normalized surface potential plot with respect to write voltages shows that the smaller grain tends to be saturated earlier as the writing voltage increases. The surface potential hysteretic loop obtained from the small grain shows a similar shape that can be obtained from Ti-rich PZT film, whereas that obtained from the larger grain shows a similar shape of Zr-rich PZT film. The time-dependent behavior of the surface potentials was measured as a function of an elapsed time. The utilization of SPM would provide a useful characterizing method for the nano-scaled PZT and BLT ferroelectric films.