Fatigue resistance in lead zirconate titanate thin ferroelectric films: Effect of cerium doping and frequency dependence

Abstract

We demonstrate improvement in fatigue resistance and other ferroelectric properties through cerium doping in sol–gel derived lead zirconate titanate thin films. We have studied frequency dependence of fatigue behavior and show that the loss of polarization due to fatigue follows a universal scaling behavior with N/f2, where N is the number of switching cycles and f the frequency. The origin of the scaling is attributed to the drift of oxygen vacancies, which is the rate limiting process in the growth of the interface layer responsible for fatigue. Empirical fits for both undoped and cerium-doped samples show that switchable polarization follows stretched exponential decay with time or N/f. Cerium doping is shown to improve fatigue resistance by impeding the motion of oxygen vacancies.

Simulation of oxygen vacancy induced phenomena in ferroelectric thin films

“…Consequently, the mobility of charged defects plays an important role in the enhancement of a coercive field. The experimental result performed by Majumder et al 32 also supports this conclusion. They observed the increase in the coercive field in an undoped PZT film, but a decrease in a cerium-doped film after a number of switching cycles.…”

“…However, they did not explain how this relation was derived. Majumder et al 32 have obtained a similar fitted relation from the experimental result. For comparison, we have derived the switching cycle and frequency-dependent space charge density from the imbalance of trapping and detrapping rates from oxygen vacancies.…”

“…On the other hand, an explanation on the reduction of a coercive field during the polarization fatigue is rare, even though it has been observed in some experiments. 30,32,35 This demands further investigation.…”

“…10, with symbols representing the experimental result from Majumder et al 32 and curves showing our simulated result. The agreement between theory and experiment is quite good for both 100 Hz and 1 kHz.…”

Fatigue effect in ferroelectric crystals: Growth of the frozen domains

“…The empirical fit of fatigue profile by stretched exponent was also used. 16 Only small part of the publications contains the information about reconstruction of the domain structure during fatigue cycling. It was shown by direct observations using scanning probe microscope that fatigue in PZT thin films manifested itself through arising and growth of complicated a)…”