Self-assembling ferroelectric Na0.5K0.5NbO3 thin films by pulsed-laser deposition

Highly [100]-axis oriented single-phase Na0.5K0.5NbO3 (NKN) thin films have been grown on polycrystalline Pt80Ir20 (Pt) and SiO2 (native oxide)/Si (111) substrates using KrF excimer laser ablation of a stoichiometric ceramic target. X-ray diffraction theta-2 theta scan and rocking curve data are evidence of the strong effect of film self-assembling along the [100] direction regardless of the substrate texture. Furthermore, multiple-cell structuring along the polar axis has been observed in NKN films grown onto the Pt substrate. Ferroelectric measurements yield remnant polarization P-r of 10 mu C/cm(2) and spontaneous polarization P-s of 17.5 mu C/cm(2) at 80 kV/cm. The electrical resistivity of the Na0.5K0.5NbO3 film was in the order of 10(10) Ohm cm at 10 kV/cm. Dielectric permittivity epsilon(') and dissipation factor tan delta have been found to vary 480-440 and 0.028-0.024, respectively, in the frequency range 0.4-100 kHz. (C) 1999 American Institute of Physics. [S0003-6951(99)03428-2].