Growth, microstructure, and ferroelectric properties of Pb(Zr0.4Ti0.6)O3∕PbZrO3 superlattices prepared on SrTiO3 (100) substrates by pulsed laser deposition

Artificially designed Pb(Zr,Ti)O3 (PZT)∕PbZrO3 (PZ) superlattices were grown on (100)-oriented SrTiO3 (STO) substrates with and without SrRuO3 bottom electrodes by pulsed laser deposition. Their microstructure was characterized using x-ray diffraction and transmission electron microscopy. Different from single PZT films having a c-axis orientation on STO (100) substrates, during growth the PZT and PZ layers in the superlattices turn to an a-axis orientation from the c-axis orientation of the first PZT layer. This growth behavior is explained by minimization of the respective interfacial lattice mismatch. The superlattices have a rather smooth morphology and sharp PZT/PZ interfaces. At the latter, misfit dislocations have been found occasionally. There are indications for the absence of the orthorhombic, antiferroelectric phase in part of the PZ layers, possibly due to strain hindering the phase transition. An elongated, “linearized” shape of the ferroelectric hysteresis loop has been found, with a remanent polarization (2Pr) of 17μC∕cm2 and a coercive field of about 110kV∕cm, which seems to be the result of a superposition of ferroelectric and antiferroelectric switching.