Domain evolution in ferroelectric thin films during fatigue process

Abstract

A combination of piezoresponse force microscopy and x-ray diffraction ${\sin }^2\Psi$ stress measurement have been used to investigate domain evolutions in (111)-oriented $\mathrm{Pb}\left({\mathrm{Zr}}_{0.55}{\mathrm{Ti}}_{0.45}\right){\mathrm{O}}_3$ (PZT) and (115)-oriented $\mathrm{Sr}{\mathrm{Bi}}_2{\mathrm{Ta}}_2{\mathrm{O}}_9$ (SBT) thin films with the repeated switching cycles (fatigue process). In the PZT film, it has been found that 90° $a\text{-}c$ domain walls form at the beginning of fatigue process and increase in amount with accumulation of switching cycles, accompanied by increase of stress. However, domain pattern and stress in the SBT film seem to be unchanged as the fatigue process is going on. The increase in stress with the repeated switching cycles in the PZT film can be attributed to the lattice distortion caused by polarization rotation. On the contrary, polarization switching in SBT involves little lattice distortion and lets it in a nearly stress-free status during the fatigue process. The difference in domain evolution during the fatigue process suggests the important role of stress in fatigue behaviors of PZT and SBT films.