Ferroelectric Properties of (Na_0.5K_0.5)NbO₃-Based Thin Films Deposited on Pt/(001)MgO Substrate by Pulsed Laser Deposition with NaNbO₃Buffer Layer

Abstract

O 3 (NKLNTS) thin films with a thickness of about 1.4 mm were fabricated on Pt/(001)MgO substrate, on which an NaNbO 3 buffer layer was introduced, by pulsed laser deposition (PLD). The X-ray diffraction pattern (XRD) showed that the 001 orientated NKLNTS thin films were grown on Pt/(001)MgO substrate. A rocking curve measurement revealed that the fluctuation of the crystalline orientation of the 001 orientated NKLNTS thin films is very small. The lattice parameters of the 001 orientated NKLNTS thin films were a ¼ 0:3911 nm and c ¼ 0:3942 nm, determined by reciprocal space map. The dielectric constant, " r , and the dielectric loss, tan , of the NKLNTS thin film were 398 and 0.22 at 1 kHz, respectively. The large tan is due to NKLNTS having a morphotropic phase boundary region around room temperature. The P-E hysteresis loops of the NKLNTS thin films showed clear ferroelectricity. The remanent polarization, P r , and coercive electric field, E c , were 26.3 mC/cm 2 and 28.6 kV/cm, respectively. The NKLNTS thin films exhibited larger P r value than NKLNTS ceramic. #

Leakage current behavior in lead-free ferroelectric (K,Na)NbO3-LiTaO3-LiSbO3 thin films

“…3,11 Alternatively, Yamazoe et al recently reported a lower leakage current in pure KNN-based thin films by periodic lattice distortion, utilizing a NaNbO 3 buffer layer to enhance the resistivity as well as polarization. 12 As a result of a largely reduced conductivity, the polarization in Mn-doped thin films was significantly enhanced. Leakage current in such thin films was found to drop by over two orders of magnitude.…”

Lead-Free KNN-Based Piezoelectric Materials

“…The hardening effect of Mn has been also confirmed by the measurement of the piezoelectric coefficient (d 33 ) of base and Mn-doped films which shows that Mn-addition is accompanied by a decline in the d 33 value from 53 pm V À1 in an undoped film to 45 pm V À1 in an Mn-doped film [107]. Yamazoe et al [109] reported that the introduction of a NN buffer layer (150 nm thick) on Pt/(001)MgO substrates had a noticeable effect on the improvement of the ferroelectric properties of KNN-LT-LS films. As illustrated in Fig.…”

“…Poole-Frenkel (P-F) model: This mechanism, which operates through the bulk of the material, is a thermal emission of charge carriers from trapped centers under , and the E c of 28.6 kV cm À1 were obtained at applied electric field of 93 kV cm À1 (film thickness ¼ 1.4 mm) [109] high electric fields [111][112][113]. The quantitative equation for current density created via this mechanism can be expressed by the following equation:…”

Fabrication of (K,Na)NbO<inf>3</inf> thin films on Si substrate by pulsed laser deposition

“…The P-E loop of the NKN films deposited in O 2 gas pressure of 50 mTorr was small. We previously reported that 110-orientated NN thin film on STO substrate (NN has orthorhombic perovskite structure and 110 polarization direction as does NKN) exhibited the largest P r value among 001-, 110-, and 111-orientated NN films, and the 001-orientated NN thin film showed the smallest P r value [8]. NKN also has the orthorhombic perovskite structure.…”

“…We reported fabrication of NKN-based thin films with excellent ferroelectric properties on SrRuO 3 (SRO)/SrTiO 3 (STO) [6,7] and Pt/(001)MgO [8,9] substrates by pulsed laser deposition (PLD). We also reported the relationship between the orientation of NN thin films and electric (dielectric and ferroelectric) properties [10].…”