Fabrication of 100-Oriented (Na0.5K0.5)NbO3–BaZrO3–(Bi0.5Li0.5)TiO3 Films on Si Substrate Using LaNiO3 Layer

Abstract

0.92(Na0.5K0.5)NbO3–0.06BaZrO3–0.02(Bi0.5Li0.5)TiO3 (NKN–BZ–BLT) thin films were fabricated by pulsed laser deposition (PLD) on a (100)Si substrate on which a 100-oriented LaNiO3 (LNO) bottom layer was fabricated by the chemical solution deposition method. The NKN–BZ–BLT films were characterized by X-ray diffraction (XRD) analysis, θ/2θ scan and ψ–2θ/ω scan, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The properties were compared with those of the NKN–BZ–BLT film deposited on the (111)Pt/Ti/SiO2/(100)Si substrate. We demonstrated that the LNO layer plays an important role in obtaining 100-oriented NKN–BZ–BLT films on the Si substrate. SEM surface and cross-sectional images showed that the NKN–BZ–BLT films fabricated at a substrate temperature of 800 °C had a high density and a relatively smooth surface. From the TEM image, this NKN–BZ–BLT film fabricated at 800 °C was composed of the columnar grains and some vertical-long pores could be observed. The energy dispersive X-ray (EDX) analysis showed that the LNO layer is decomposed to La2NiO4 by its reaction with Nb. The dielectric properties showed that the NKN–BZ–BLT film on the LNO electrode had a small dielectric constant of 82, compared with the NKN–BZ–BLT film (εr = 3127) on the (111)Pt/Ti/SiO2/(100)Si substrate. This difference is due to the polarization direction of the film and the polarization axis of the NKN–BZ–BLT film on the LNO electrode exists in a direction perpendicular to the surface of the substrate. However, the NKN–BZ–BLT film on LNO showed a small Pr value. This is due to the dispersion of Ni from the LNO layer.