Search

Abstract: Highly (001) oriented (K,Na)NbO3 lead-free piezoelectric films were fabricated on SrRuO3 buffered SrTiO3(001) single crystal substrates by RF magnetron sputtering. The films showed a stable frequency dependence of dielectric permittivity and loss tangent in the range of 1kHz–1MHz. A fairly high tunability of 69.7% (@400kV/cm) was obtained in the films. Well saturated P–E hysteresis loops were obtained at E=250kV/cm, the remnant polarization P r was 8μC/cm2, and coercive field E c was only 40kV/cm. These films showed a fatigue-free behavior up to 1010 switching cycles. The decreased coercive field, improved dielectric and fatigue properties may be related to SRO bottom electrodes, which can efficiently suppress the “dead layer” near the ferroelectric-electrode interface. The leakage current density of the films was only 3.48×10−6 A/cm2 at the electric field of 250kV/cm, which is even lower than that of Mn-doped KNN films. In addition, the piezoelectric constant d 33 was estimated to be 36pm/V. [Copyright &y& Elsevier]

Abstract: (K,Na)NbO3 ferroelectric films were grown on LaNiO3 coated silicon substrates by RF magnetron sputtering. The conductive LaNiO3 films acted as seed layers and induced the highly (001) oriented perovskite (K,Na)NbO3 films. Such films exhibit saturated hysteresis loops and have a remnant polarization (2P r) of 23μC/cm2, and coercive field (2E c) of 139kV/cm. The films showed a fatigue-free behavior up to 109 switching cycles. A high tunability of 65.7% (@300kV/cm) was obtained in the films. The leakage current density of the films is about 6.0×10−8 A/cm2 at an electric field of 50kV/cm. [Copyright &y& Elsevier]

Crack-free Yttrium iron garnet (Y 3 Fe 5 O 12 , YIG) thin films were successfully deposited on Si/SiO 2 substrates by RF magnetron sputtering, through controlling the annealing temperature and cooling rate during post-annealing process. The annealing condition dependences of crystallinity, microstructures and magnetic properties of YIG films were investigated. With the increase of the annealing temperature, the saturation magnetization of YIG films increases and the coercive field decreases, while the ferromagnetic resonance (FMR) linewidth becomes wider. The films annealed at 750 °C with cooling rate of 1 °C/min are crack-free and present excellent comprehensive performances, the corresponding coercive field is 32 Oe and the FMR linewidth is 57 Oe at 9.4 GHz. These results indicate that high-quality crack-free YIG films with excellent magnetic properties can be achieved on Si/SiO 2 substrates by controlling the annealing process, which makes it more convenient to fabricate low-loss microwave integrated devices. [ABSTRACT FROM AUTHOR]

SrRuO 3 (SRO) thin films were grown on SiO 2 /Si substrates with different thickness of LaNiO 3 (LNO) seed layers by RF magnetron sputtering. Effects of LNO thickness on the grain orientation, surface morphology, magnetic behavior and electrical transport properties of SRO films were investigated. The orientation of SRO films transformed from (110) pc to (001) pc and the residual stress was released gradually with increasing the thickness (pc refers to the pseudo-cubic unit cell of SrRuO 3 ). SRO films with higher orientation grown on LNO exhibited more flat surface, higher saturation magnetization, and lower coercive field. The magnetic anisotropy was enhanced on thicker LNO due to the different states of residual stress. In addition, the temperature dependence of resistivity was promoted by the microstructural disorder. (110) pc -oriented SRO monolayer electrode and (001) pc -oriented SRO/LNO300 bilayer electrode own low room temperature sheet resistance of 0.38 Ω/□ and 0.26 Ω/□, respectively. The results indicate that the controllable SRO films can be used as not only good bottom electrodes but also promising templates to control the crystallographic orientations of various other perovskite-based functional materials. [ABSTRACT FROM AUTHOR]

Abstract: We report the fabrication of Pb0.4Sr0.6TiO3 thin films with different microstructures and dielectric responses deposited on LaNiO3 buffered silicon substrate via the RF magnetron sputtering method with various deposition powers from 40W to 120W. Effects of the power on deposition rate, orientation, surface morphology and dielectric response were investigated. X-ray diffraction patterns indicated that the crystal orientation of thin films changes from (110) preferential orientation to random orientation with decreasing power, and finally to perfect (100) orientation. Moreover, the thin films prepared at lower power show more homogeneous grain size distribution and denser microstructure. The capacitance–voltage analysis revealed that the films deposited at lower powers show larger dielectric response and better tunability performance. Especially, large dielectric constant and tunability of 947 and 80.88% (@400kV/cm), respectively, were obtained under a deposition power of 40W. [Copyright &y& Elsevier]