Epitaxial growth and structural characterization of Pb(Fe1/2Nb1/2)O3 thin films

TL;DR

This study reports the successful epitaxial growth of high-quality Pb(Fe1/2Nb1/2)O3 thin films on SrTiO3 substrates, optimizing deposition conditions to achieve phase purity and excellent crystalline quality for potential functional applications.

Contribution

It identifies the optimal pulsed laser deposition parameters for epitaxial, impurity-free PFN thin films with controlled thickness and surface morphology, advancing thin film fabrication techniques.

Findings

Achieved phase-pure, epitaxial PFN thin films with low mosaicity.

Established a correlation between film thickness, grain size, and surface roughness.

Demonstrated c-axis orientation and high crystalline quality of the films.

Abstract

We have grown lead iron niobate thin films with composition Pb(Fe1/2Nb1/2)O3 (PFN) on (0 0 1) SrTiO3 substrates by pulsed laser deposition. The influence of the deposition conditions on the phase purity was studied. Due to similar thermodynamic stability spaces, a pyrochlore phase often coexists with the PFN perovskite phase. By optimizing the kinetic parameters, we succeeded in identifying a deposition window which resulted in epitaxial perovskite-phase PFN thin films with no identifiable trace of impurity phases appearing in the X-ray diffractograms. PFN films having thicknesses between 20 and 200 nm were smooth and epitaxially oriented with the substrate and as demonstrated by RHEED streaks which were aligned with the substrate axes. X-ray diffraction showed that the films were completely c-axis oriented and of excellent crystalline quality with low mosaicity (X-ray rocking curve FWHM<0.09). The surface roughness of thin films was also investigated by atomic force microscopy. The root-mean-square roughness varies between 0.9 nm for 50-nm-thick films to 16 nm for 100-nm-thick films. We also observe a correlation between grain size, surface roughness and film thickness.