Phase transition in ferroelectric Pb(Zr_0.52Ti_0.48)O₃ epitaxial thin films

Qiang Liu (1, 2) , O. Marconot (2) , M. Piquemal (2) , C. Eypert (3) , Alexis Borowiak (4, 2) , Nicolas Baboux (4, 2) , B. Gautier (2) , A. Benamrouche (2) , Pédro Rojo Romeo (5, 2) , Yves Robach (1, 2) , Jose Penuelas (1, 2) , Bertrand Vilquin (1, 2)

1 INL - H&N - INL - Hétéroepitaxie et Nanostructures
2 INL - Institut des Nanotechnologies de Lyon
3 HORIBA Scientific [France]
4 INL - DE - INL - Dispositifs Electroniques
5 INL - Photonique - INL - Nanophotonique

PbZr1−xTixO3 (PZT) has been intensively studied for various ferroelectric applications. Its promising application for micro-electro-mechanical system has reignited the interests due to its outstanding ferroelectric and piezoelectric properties.Most PZT ceramics employed in devices are synthesized with a Zr/Ti ratio close to the tetragonal– rhombohedral morphotropic phase boundary (x = 0.48) due to its high electro-mechanical coupling at this composition. Morphotropic phase boundary is particularly interesting to study for the investigation of phase transition. In this work, we report the epitaxial growth and electrical characterization of epitaxial PZT (Zr/Ti = 52/48) thin films on Nb-doped SrTiO3. PZT films, with thickness from30 nmto 65 nm, were deposited by sol–gelmethod and eventually crystallized at 700 °C by rapid thermal annealing in oxygen. Filmferroelectricity was confirmed by Sawyer–Tower circuit measurement. X-ray diffraction analysis indicates a thicknessdependent structural phase, i.e., a phase transition from tetragonal phase for the thinner film to a biphasic (tetragonal + pseudo-cubic) structure for the thicker film, which is characterized by ellipsometry as a phase separation from the bottom surface of the film to the top one. This phase transition is related to a composition gradient within the film thickness.

Domaines: Sciences de l'ingénieur [physics]; Optique / photonique; Micro et nanotechnologies/Microélectronique; Matériaux

Qiang Liu, O. Marconot, M. Piquemal, C. Eypert, Alexis Borowiak, et al.. Phase transition in ferroelectric Pb(Zr_0.52Ti_0.48)O₃ epitaxial thin films. Thin Solid Films, 2014, 553, pp.85-88. ⟨10.1016/j.tsf.2013.12.042⟩. ⟨hal-01489882⟩