Rf-magnetron sputtered ferroelectric (Na,K)NbO/sub 3/ films

Sodium potassium niobate (Na,K)NbO/sub 3/ (NKN) thin films were grown by rf-magnetron sputtering from stoichiometric Na/sub 0.5/K/sub 0.5/NbO/sub 3/ target on LaAlO/sub 3/ (LAO) single crystals and polycrystalline Pt/sub 80/Ir/sub 20/ (PtIr) substrates. NKN films on polycrystalline PtIr substrates were found to be preferentially (00l) oriented while XRD measurements reveal epitaxial quality of NKN/LaAlO/sub 3/ film structures. The ferroelectric state in NKN/PtIr films at room temperature is indicated by polarization loops with polarization as high as 33.4 /spl mu/C/cm/sup 2/ at 700 kV/cm remnant polarization of 9.9 /spl mu/C/cm/sup 2/, and coercive field of 91 kV/cm. I-V characteristics of vertical Au/NKN/PtIr capacitive cells and planar Au/NKN/LAO interdigital capacitors (IDCs) showed very good insulating properties. For NKN IDC the leakage current density was in the order of 30 nA/cm/sup 2/ at 400 kV/cm. Rf dielectric spectroscopy demonstrates low loss, low frequency dispersion, and high voltage tunability both for vertical Au/NKN/PtIr and planar interdigital Au/NKN/LAO capacitors.