bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct-Write E-beam Submicron Domain Engineering in LiNbO3 Thin Films Grown by Liquid Phase Epitaxy
Authors: Son Ji-Won , Yuen Yin , Orlov Sergei S. , Phillips Bill , Galambos Ludwig , Shur Vladimir Ya. , Hesselink Lambertus 
Published: April 2011

ABSTRACTWe demonstrate submicron ferroelectric domain engineering in liquid phase epitaxy (LPE) LiNbO3 thin films grown on LiNbO3 and LiTaO3 substrates using a direct-write electron beam poling for waveguide applications. LiNbO3 thin films of several-micron thickness were grown using a flux melt of 20 mol% LiNbO3-80 mol% LiVO3. To engineer domain structures in Z- oriented LPE LiNbO3 films, a direct-write electron beam poling was implemented. It is shown that we can engineer the domain structure of LPE LiNbO3 films by using direct e-beam poling, even though the domain orientations of the film and the substrate are opposite. We also compared e-beam poling behavior in a congruent LiNbO3 single crystal and a LPE LiNbO3 film. Using the same e-beam scan parameters, a much enhanced domain structure is obtained in LPE films. Defect structure and composition effects are also discussed.
PZT Thick Films Deposited by Improved Hydrothermal Method for Thickness Mode Ultrasonic Transducer
Authors: Ishikawa Mutsuo , Kurosawa Minoru , Katsura Naoki , Takeuchi Shinichi 
Published: April 2011

ABSTRACTThe purpose of this study was to improve deposition rate of the hydrothermal method for lead zirconate titanate (PZT) thick film on titanium substrate. We developed a high-speed rotaion substrate holder at a tangential velocity of about 0.8m/s in autoclave. A titanium substrate was fixed by the holder on the surface of a stirring bar. For the film deposition, powder of TiO2 was used instead of the liquid TiCl4. The deposition rate on titanium substrate was improved up to 7μm/24h. Piezoelectric constant d31 of the hydrothermal PZT film was -2.6 × 1011 V/m. This result was lower than that of PZT ceramics. However, this hydrothermal method obtained thick film and this film was confirmed to be polycrystalline PZT analyses of XRD and SEM. In addition, performance of thickness mode vibration of hydrothermal PZT 50μm thick film was investigated by radiating in water. The phase velocity of dilatational wave of the thickness mode vibration of the hydrothermal PZT film was 1800m/s and the electromechanical coupling factor was 47%.
Frequency-Dependent Electromechanical Response in Ferroelectric Materials Measured via Piezoresponse Force Microscopy
Authors: Bdikin I. K. , Shvartsman V. V. , Kim S-H. , Herrero J. Manuel , Kholkin A. L. 
Published: April 2011

ABSTRACTLocal piezoelectric signal is measured via Piezoresponse Force Microscopy (PFM) in PbZr0.3Ti0.7O3 films and PbZr1/3Nb2/3O3-0.045PbTiO3 single crystals. It is observed that the amplitude of piezoelectric response is almost independent on frequency for vertical (out of plane) signal and strongly decreases with increasing frequency in the range 10–100 kHz for lateral (in-plane) response. Moreover, the in-plane piezoelectric contrast is reversed when the measurements are done at high enough frequency (phase shift exceeds 90°). As a result, the inplane polarization direction can be misinterpreted if the driving frequency exceeds certain level. For the explanation of observed effect a simple model is proposed that takes into account a possible slip between the conductive PFM tip and moving piezoelectric surface. The implications of the observed frequency-dependent contrast for the domain imaging in ferroelectric materials are discussed.
Growth Reorientation with the Annealing Temperature of SrBi2Ta2O9 Films Deposited by PLD
Authors: Cruz Ma. P. , Portelles Jorge J. , Siqueiros Jesús M. 
Published: April 2011

ABSTRACTFilms of SrBi2Ta2O9 (SBT) were grown on Pt/TiO2/SiO2/Si substrates by the pulsed laser deposition (PLD) technique. The deposits were made at temperatures between 570°C and 715°C, and post-annealed at 750°C. The films grown at 610°C show a (115) preferentially orientation with a small peaks associated to (00l) planes. At higher deposition temperatures, the (00l) peaks increase their intensity, a tendency that is intensified after the heat treatment at 750°C. However, when the films grown at 590–610°C are heat-treated at 750°C, there is a reduction of the crystallites oriented in the (00l) direction, leading to an enhancement of the polarization, reflected in the maximum value of 2Pr = 9.1 μC/cm2 and a coercive field, Ec, of 52.0 KV/cm.
Nanoelectromechanics of Piezoresponse Force Microscopy: Contact Properties, Fields Below the Surface and Polarization Switching
Authors: Kalinin S. V. , Shin Junsoo , Kachanov M. , Karapetian E. , Baddorf A. P. 
Published: April 2011

ABSTRACTTo achieve quantitative interpretation of Piezoresponse Force Microscopy (PFM), including resolution limits, tip bias- and strain-induced phenomena and spectroscopy, knowledge of elastic and electrostatic field distributions below the tip is required. The exact closed form solution of the coupled electroelastic problem for piezoelectric indentation is derived and used to obtain the tip-induced electric field and strain distribution in the ferroelectric material. This establishes a complete continuum mechanics description of the PFM imaging mechanism. These solutions are reduced to the point charge/force behavior for large separations from contact, and the applicability limits and charge/force magnitude for these models are established. The implications of these results for ferroelectric polarization switching processes are analyzed.
Interface states of laser ablated BaTiO3 and Ba0.9Ca0.1TiO3 thin films in MFS structure determined by DLTS and C – V technique
Authors: Victor P. , Saha S. , Krupanidhi S. B. 
Published: April 2011

ABSTRACTBaTiO3 and Ba0.9Ca0.1TiO3 thin films were deposited on the p – type Si substrate by pulsed excimer laser ablation technique. The Capacitance – Voltage (C-V) measurement measured at 1 MHz exhibited a clockwise rotating hysteresis loop with a wide memory window for the Metal – Ferroelectric – Semiconductor (MFS) capacitor confirming the ferroelectric nature. The low frequency C – V measurements exhibited the response of the minority carriers in the inversion region while at 1 MHz the C – V is of a high frequency type with minimum capacitance in the inversion region. The interface states of both the MFS structures were calculated from the Castagne – Vaipaille method (High – low frequency C – V curve). Deep Level Transient Spectroscopy (DLTS) was used to analyze the interface traps and capture cross section present in the MFS capacitor. There were distinct peaks present in the DLTS spectrum and these peaks were attributed to the presence of the discrete interface states present at the semiconductor – ferroelectric interface. The distribution of calculated interface states were mapped with the silicon energy band gap for both the undoped and Ca doped BaTiO3 thin films using both the C – V and DLTS method. The interface states of the Ca doped BaTiO3 thin films were found to be higher than the pure BaTiO3 thin films.
Raman Spectra of Srm-3Bi4TimO3m+3 Thin Films
Authors: Wang Jia , Cheng Guangxu , Zhang Shantao , Cheng Hongwei , Chen Yanfeng 
Published: April 2011

ABSTRACTA series of bismuth layer-structured ferroelectrics thin films Srm-3Bi4TimO3m+3(m=3, 4, 5, and 6) were deposited by pulsed laser deposition (PLD) on (001) LaAlO3 single crystal substrate. XRD and Raman studies have been performed. The more sensitive Raman spectra lead to a different understanding on the layer structure of Sr3Bi4Ti6O21 from XRD. This can be attributed to the lager c-axis constant of Sr3Bi4Ti6O21 due to more layers. More layers lead to increasing disorder in the local scale of the average grain.
A Novel Iridium Precursor for MOCVD
Authors: Kawano Kazuhisa , Takamori Mayumi , Yamakawa Tetsu , Watari Soichi , Fujisawa Hironori , Shimizu Masaru , Niu Hirohiko , Oshima Noriaki 
Published: April 2011

ABSTRACTA novel liquid iridium precursor (1,3-cyclohexadiene)(ethylcyclopentadienyl)iridium, Ir(EtCp)(CHD), was synthesized and its physical properties were examined. Ir(EtCp)(CHD) exhibited enough vapor pressure (0.1 Torr/75°C), excellent volatility and adequate decomposition temperature. Characteristics of the Ir films deposited using Ir(EtCp)(CHD) and the conventional Ir precursor (1,5-cyclooctadiene)(ethylcyclopentadienyl)iridium, Ir(EtCp)(COD), by metal-organic chemical vapor deposition (MOCVD) method were compared. Ir films grown using Ir(EtCp)(CHD) showed shorter incubation time and higher nucleation density than those of films using Ir(EtCp)(COD).
TEM and Electrical Analysis of Sputtered Barium Strontium Titanate (BST) Thin Films on Flexible Copper Substrates
Authors: Laughlin Brian , Ihlefeld Jon , Maria Jon-Paul 
Published: April 2011

ABSTRACTBa0.6Sr0.4TiO3 (BST) films were deposited on copper foils by radio frequency magnetron sputtering. These films will be an integral part of flexible capacitor sheets intended for space borne re-configurable antenna arrays. By the use of controlled pO2 high temperature anneals, the films were fully crystallized in the absence of substrate oxidation. X-ray diffraction and transmission electron microscopy (TEM) showed no existence of copper oxidation (i.e. Cu2O or CuO phases). The deposited BST films exhibit a high permittivity (625) and a low tan δ (0.020) at zero bias and room temperature. A pronounced electrical tunability ratio of 3.5:1 is observed on these devices. Devices show loss tangents as low as 0.003 in fields approaching 400 kV/cm. Electrical field calculations are based on cross-sectional atomic force microscopy (AFM) images that reveal a film thickness of 800 nm. Temperature dependent measurements show a Tmax ∼ 230 K with a diffuse dielectric anomaly. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) analyses indicate a conformal film with a mixed grain morphology and an abrupt Cu/BST interface.
Enhanced Dielectric Properties Of Compositionally Modified BST Based Thin Films For Voltage Tunable Microwave Devices
Authors: Cole M. W. , Nothwang W. D. , Hubbard C. , Ngo E. , Ervin M. 
Published: April 2011

ABSTRACTIn this work, material compositional design and optimized film processing methods, were employed to simultaneously lower the dielectric loss and enhance the dielectric tunability of Ba0.6Sr0.4TiO3 (BST) based thin films without compromising the device impedance matching (εr<500) and device control voltage (<10 V) requirements. The films compositional design was achieved by Mg doping BST from 3 to 10 mol % via the metalorganic solution deposition (MOSD) technique and post-deposition annealing in an oxygen ambience. The films dielectric loss at these doping levels was identical, tanδ ∼0.007 and the permittivity values ranged from 339 to 220. Device quality values of tunability, 40 and 32 %, for the 3 and 7 mol% doped BST films, respectively, were achieved by elevating the applied bias to 474 kV/cm. This device quality tuning is compatible with voltage requirements of current semiconductor based systems. The results suggest that the low level acceptor doping from 3 to 7 mol%, optimized precursor solution concentration (0.43 M), and oxygenated post-deposition thermal processing were found to work in concert to lower dielectric loss, limit defect density concentration, optimize film microstructure, and eliminate undesirable film/electrode interfacial phases. The enhanced dielectric and insulating properties of the 3–7 mol% Mg doped BST thin films make them excellent candidates for integration into tunable devices.
Polarization Reversal Anti-parallel to the Applied Electric Field Observed Using a Scanning Nonlinear Dielectric Microscopy
Authors: Morita Takeshi , Cho Yasuo 
Published: April 2011

ABSTRACTIt is well known that spontaneous polarization of ferroelectric material is an intrinsic property applied for nonvolatile memory devices. Poling direction can be reversed in a nanometer size area using the conductive cantilever of a scanning probe microscope. In order to detect nanodots patterns, scanning nonlinear dielectric microscope (SNDM) is superior to piezore-sponse microscope in terms of resolution. In this paper, a real-time measuring method of a poling direction is proposed. Using this method, the domain reversal process was observed and an unexpected phenomenon was found, namely, that the poling directions were aligned antiparallel to the poling electric field. This antiparallel poling reversal took place when the film thickness was more than 350 nm in the case of lithium tantalate. At present, the reason and mechanism of the antiparallel poling reversal are uncertain, although it might be related to the concentrated electric field near the cantilever tip.
Effective Orientation Control of Pb(Zr0.4Ti0.6)O3 Thin Films Using A New Ti/Pb(Zr0.4Ti0.6)O3 Seeding Layer
Authors: Moon B. K. , Arisumi O. , Hornik K. , Bruchhaus R. , Itokawa H. , Hilliger A. , Zhuang H. , Egger U. , Nakazawa K. , Yamazaki S. , Ozaki T. , Nagel N. , Kunishima I. , Yamakawa K. , Beitel G. 
Published: April 2011

ABSTRACTThe effect of thin Ti/PbZr0.4Ti0.6O3 seed layers on the properties of PbZr0.4Ti0.6O3 (PZT) capacitors has been investigated. The seed layer is based on a bi-layer of thin Ti and thin PZT with a total thickness ranging from 10 to 25 nm, which was deposited on Ir/Pt or Ir/IrO2/Pt by sputtering. After crystallization of the seed layers the main 130-nm-thick PZT film was deposited and crystallized. As a result, a highly preferred (111)-orientation of the PZT was obtained on a 10-nm-thick seed layer, where the peak intensity ratios of (111)/{100} and (111)/{110} are about 100 and 20, respectively. The 10-nm-thick seed forms a pyrochlore phase with a very smooth surface, where the formation of the pyrochlore phase is attributed to Pb diffusion, resulting in a Pb deficient stoichiometry. The seed layer transformed to the perovskite phase during the main PZT crystallization. It is shown that an IrO2 layer beneath the Pt can prevent Pt layer degradation related to the volume expansion due to the oxidation of Ir during the main PZT crystallization. Capacitors with the 10-nm-thick seed layer fabricated on the Ir/Pt and Ir/IrO2/Pt substrates showed typical 2 Pr values of 44.0 μC/cm2 and 41.2 μC/cm2, respectively. The voltage found for 90%-polarization saturation is about 3.0 V, and the capacitors are fatigue-free at least up to 1010 switching cycles.
RF Magnetron Sputtering Process for (Ba,Sr)TiO3 Thin Films with Higher Dielectric Constant
Authors: Jimbo T. , Kimura I. , Nishioka Y. , Suu K. 
Published: April 2011

ABSTRACT(Ba,Sr)TiO3 (BST) films were deposited by RF magnetron sputtering using BST sintered ceramic targets and an approach to deposit BST films with higher permittivity by sputtering deposition was explored aiming to the application of thin film capacitor, RF tunable components and so on.Basic sputtering conditions such as RF power, deposition temperature and so on were varied in this study. BST films and Pt/BST/Pt capacitors were investigated by electrical properties, XRD analysis and SEM observation. It became clear that deposition temperature, deposition rate, and BST film thickness were important parameters for optimization of the dielectric constant. From the non-linearly relationship between dielectric constant and BST film thickness, we could also find that the interfacial layer between BST and Pt bottom electrode was important for controlling the BST film properties. Furthermore, an approach to enhance the crystalline quality has to be explored for further improvement of BST film properties. Dielectric constant could be raised up to 10% by just changing the gas flow sequence of BST sputtering process.
Dielectric and Ferroelectric Properties of Modified BiFeO3-PbTiO3 Thin Films Derived from Sol-gel Processing
Authors: Cheng JinRong , Eric Cross L. 
Published: April 2011

ABSTRACTIn this paper, thin films of La- modified (Bi,La)FeO3-PbTiO3 (BLF-PT) morphotropic phase boundary (MPB) solid solutions have been prepared by using sol-gel processing. A thin Pb(Zr,Ti)O3 (PZT) template layer was introduced to make BLF-PT thin films adhere tightly to the platinized silicon (Pt/Ti/SiO2/Si) substrate. X-ray diffraction (XRD) analysis revealed that BLF-PT thin films were of the perovskite structure without detectable pyrochlore phase annealing at 650–750°C. The cross sectional and plain view images of or our specimen were observed by using the scan electrical microscope (SEM). The room temperature dielectric constant K and tanδ were of ∼800 and 4% respectively, for BLF-PT thin films using a measurement frequency of 1 kHz. Our preliminary experiments indicated that the sol-gel derived BLF-PT thin films have good insulation resistance and measurable dielectric and ferroelectric responses.
Microstructural and Electrical Characterization of (Ba,Sr)TiO3 Thin Films Prepared by a New Carboxylate Free Chemical Solution Deposition (CSD) route
Authors: Halder Sandip , Schneller Theodor , Waser Rainer 
Published: April 2011

ABSTRACTA new type of alkoxide precursor was developed to avoid the formation of the oxo-carbonate phase as an intermediate phase during crystallization. The precursors were synthesized from Ba metal, Sr metal and aminoethanol. The new precursors were found to be quite stable and soluble in a number of organic solvents. Films were prepared by depositing the precursor solution on Pt coated Silicon wafers and crystallized between 550 and 700°C. The films were found to crystallize only above 600°C. After crystallization Pt top electrodes were deposited by sputtering and lift off processing. FT-IR studies were performed on the films to check for any oxo-carbonate phase. Microstructural studies involving XRD, SEM and AFM were performed on the films. The films were found to have a dielectric constant of around 400 with a tunability of around 37%. The frequency and temperature dependence of the dielectric constant were also studied. In addition leakage studies were performed on the films at various temperatures.
Growth and study of BaZrO3 thin films by pulsed excimer laser ablation
Authors: Rajasekarakumar V. , Victor P. , Ranjith R. , Saha S. , Rajagopalan S. , Tyagi A. K. , Krupanidhi S. B. 
Published: April 2011

ABSTRACTThin films of BaZrO3 (BZ) were grown using a pulsed laser deposition technique on platinum coated silicon substrates. Films showed a polycrystalline perovskite structure upon different annealing procedures of in-situ and ex-situ crystallization. The composition analyses were done using Energy dispersive X-ray analysis (EDAX) and Secondary ion mass spectrometry (SIMS). The SIMS analysis revealed that the ZrO2 formation at the right interface of substrate and the film leads the degradation of the device on the electrical properties in the case of ex-situ crystallized films. But the in-situ films exhibited no interfacial formation. The dielectric properties have been studied for the different temperatures in the frequency regime of 40 Hz to 100kHz. The response of the film to external ac stimuli was studied at different temperatures, and it showed that ac conductivity values in the limiting case are correspond to oxygen vacancy motion. The electrical modulus is fitted to a stretched exponential function and the results clearly indicate the presence of the non-Debye type of dielectric relaxation in these materials.
Liquid Injection MOCVD of Rare-Earth Oxides Using New Alkoxide Precursors
Authors: Williams Paul A. , Jones Anthony C. , Aspinall Helen C. , Gaskell Jeffrey M. , Chalker Paul R. , Marshall Paul A. , Loo Yim F. , Smith Lesley M. 
Published: April 2011

ABSTRACTHigh purity lanthanum oxide and praseodymium oxide thin films (C< 1 at.-%) have been deposited by liquid injection MOCVD using the volatile alkoxide precursos [La(mmp)3] and [Pr(mmp)3] in toluene-solution (mmp = OCMe2CH2OMe). 1H NMR solution studies have shown that the addition of donor species, such as tetraglyme (CH3O(CH2CH2O)4CH3) or mmpH prevent molecular aggregation and help stabilise the precursors.
Vanadium Dioxide Thin Films for Thermo-Optical Switching Applications
Authors: Jiang Lijun , Carr William N. 
Published: April 2011

ABSTRACTVanadium dioxide (VO2) thin films were fabricated by e-beam evaporation of vanadium thin films followed by thermal oxidation in oxygen ambient. The properties of the VO2 films were investigated for thermo-optical switching applications. Synthesized VO2 film displays a phase transition at 65 – 68 °C. It exhibits an abrupt change in optical reflectivity over the phase transition temperature range. Results for VO2 on a highly reflective metal layer are strongly dependent on the VO2 thickness. The optical switching has a major hysteresis of about 15 °C between the heating and cooling branches. The evolution of the surface morphology with the oxidation time was studied with a SEM. The VO2 film was patterned on microplatforms by metal lift-off technique. We conclude that the evaporation followed by oxidation is an effective method to produce active VO2 film for thermo-optical switching devices.
Mîcromagnetic Modeling of the Behavior of Magnetostrictive Films under Stress
Authors: Shu Y. C. , Yen J. H. 
Published: April 2011

ABSTRACTWe study the effect of stress on the behavior of magnetostrictive films. Our approach is different from the conventional one which neglects the strain compatibility. Here, we include the kinematic constraint in our micromagnetic model and proposed to use the average to calculate the stress-induced magnetic field. The analytic formulation of magnetostrictive energy is derived which enables us to perform simulation at a large scale with few iteration steps. The simulation results show that the conventional approach is insufficient to predict magnetic domain patterns for materials with large magnetostriction, and the effect of intrinsic stress cannot be neglected.
Multiscale Computational Model of Soft Elasticity and Director Reorientation in Nematic Gels
Authors: DeSimone Antonio 
Published: April 2011

ABSTRACTA coarse-grained model of soft elasticity of nematic elastomers is presented, in which fine-scale spatial oscillations are carefully accounted for in the definition of an effective energy density, and then averaged out from the kinematics. Algorithmically, this amounts to taking a suitable convex envelope of the original free-energy of the system. The resulting finite element simulations of stretching experiments on thin sheets of nematic elastomers enable us to resolve simultaneously the macroscopic mechanical response (e.g., deformed shape, stress-strain curves) and the underlying microscopic mechanisms (e.g., evolution of domain structures, local reorientation of the nematic director).
Fabrication of Lead Zirconate Titanate Thick Film Disks for Micro Transducer Devices
Authors: Iijima Takashi , Ito Sachiko , Matsuda Hirofumi 
Published: April 2011

ABSTRACTA combination of the preparation techniques for the ferroelectric films and the micro machining of Si is considered to be an effective way to fabricate microelectromechanical systems (MEMS), such as piezoelectric micro-transducer devices for the electrical and medical fields. In this study, 10-μm-thick disk shape lead zirconate titanate (PZT) thick films were successfully fabricated using a chemical solution deposition (CSD) process. Pt top electrode and PZT layer were etched by reactive ion etching (RIE) process, and 100 to 500-μm-diameter PZT micro disks were fabricated on Pt/SiO2/Si substrate. The relative dielectric constant, dissipation factor, remnant polarization and coercive field were εr = 1130, tanδ = 0.02, Pr = 14 μC/cm2 and Ec = 25 kV/cm, respectively. This means that the ferroelectric and dielectric properties of the PZT micro disks were comparable with that of the bulk PZT ceramics. The PZT micro disk showed the butterfly-shaped displacement curve, related with piezoelectric response, in the case of bipolar measurement. The piezoelectric constant of the PZT disks poled at 80Vfor 10 min was estimated to be AFM d33 = 221 pm/V. A resonance frequency of the radial oscillation was evaluated to apply for micro transducer devices.