bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ferroelectric Properties of a-Axis Textured BaTiO3 Thin Films
Authors: Lu H. A. , Wills L. A. , Wessels B. W. , Zhan X. , Helfrich J. A. , Ketuerson J. B. 
Published: March 2011

AbstractFerroelectric and dielectric properties were measured for BaTiO3 thin films prepared by metalorganic chemical vapor deposition which were highly a-axis textured. No ferroelectric hysteresis was observed from the as-deposited BaTiO3 films on Pt coated MgO. Upon applying an electric field exceeding a threshold electric field, Et, ∼ 50 - 100 kV/cm, a ferroelectric hysteresis was observed. A spontaneous polarization Ps ≥ 15 μC/cm2 was measured for the textured films.
Preparation and Characterization of Epitaxial KNBO3 Thin Films by a Sol-Gel Method
Authors: Endo Hidehiro , Cima M. J. 
Published: March 2011

AbstractEpitaxial formation of KNbO3 films on several substrates was examined. The films were prepared by a sol-gel process using potassium ethoxide and niobium pentaethoxide. Hetero-epitaxial KNbO3 films with (100) orientation were successfully obtained both on MgO (100) and SrTiO3 (100) substrates by heat treatments above 700°C, while polycrystalline KNbO3 were formed on Si (111) substrates. Higher temperatures and extended soaking time promoted the grain growth of KNbO3 and KNbO3 films with improved surface morphologies (smoother surfaces) could be obtained by controlling heat treatment parameters.
Microstructural Changes Due to Process Conditions in Sol-Gel Derived KNbO3 Thin Films
Authors: Derderian G.J. , Barrie J.D. , Aitchison K.A. , Adams P.M. , Mecartney M.L. 
Published: March 2011

AbstractKNbO3 thin films have been deposited from K(OMe)/Nb(OMe)5 sols onto (100) MgO substrates. Microstructural changes were observed relative to stoichiometry, aging, and the hydrolysis temperature. The production of single phase, oriented films has been demonstrated, and was found to be strongly dependent on process conditions. The films were characterized by XRD, TEM, SEM, EDS, and Raman spectroscopy.
Ferroelectric Thin Films Via Sol-Gel Processing of Singlesource Precursors
Authors: Chandler C.D. , Hampden-Smith M.J. , Schwartz R.W. 
Published: March 2011

AbstractThe use of single-source mixed metal-organic precursors specifically designed for the formation of crystalline perovskite phase mixed metal oxide powders has been investigated. Pyridine solutions of divalent metal α-hydroxycarboxylates of general empirical formula A(O2CCMe2OH)2 where A = Pb, Ca, Sr, Ba; Me = methyl, were designed to react with metal alkoxides, for example, Ti(O-i-Pr)4, with the elimination of two equivalents of alcohol to form species with fixed A:B stoichiometry of 1:1 according to the equation: A(O2CCMe2OH)2 + B(OR)4 → A(O2CCMe2O)2B(OR)2 + 2HOR. Hydrolysis of these compounds in pyridine produces clear solutions which on removal of the solvent in vacuo, yield yellow powders. These powders readily dissolve in ethanol to give solutions from which thin films can be formed either by dip-coating or spin coating. The crystallization behavior, composition and ferroelectric properties of these films is discussed. The crystallization of the films generally required substantially higher temperatures compared to powders obtained from the same precursor solutions.
Transmission Electron Microscopy of Pzt Thin-Films Prepared by A Sol-Gel Technique
Authors: Seraphin Supapan , Zhou Dan , Teowee G. , Boulton J.M. , Uhlmann D.R. 
Published: March 2011

AbstractThe microstructure of lead zirconate titanate (PZT) thin films prepared by a sol-gel technique was investigated using transmission electron microscopy (TEM) and transmission electron diffraction. We investigated the microstructure of three sets of thin films with different chemical compositions: PZT 53/47 films with no excess PbO; with excess PbO; and PZT 65/35 with no excess PbO. All samples were fired for 30 minutes at temperatures ranging from 400C to 700C. Incorporation of excess PbO in the 53/47 film fired at 450C resulted in polycrystalline perovskite grains with an average grain size of less than 0.1 μm. Grain boundaries are decorated by 5-10 nm diameter precipitates possibly caused by the segregation of remnant pyrochlore or excess PbO. The films have high values of dielectric constant (up to 2500) when fired at 700C. PZT 65/35 fired at 700C consists of two distinct phases: a fine-grained matrix of pyrochlore, and 10-μm diameter rosettes of perovskite. The correlations between the compositions, the microstructure of the films, and their processing conditions on the one hand, and ferroelectric properties on the other are discussed.
Piezoelectric and Capacitative Microactuators and Devices
Authors: Sayer M. , Barrow D. , Zou L. , Kumar C.V.R. Vasant , Noteboom R. , Knapik D.A. , Schindel D.W. , Hutchins D.A. 
Published: March 2011

AbstractUltrasonic transducers, microactuators and resonators using sol gel PZT films, polymer membranes and silicon machining techniques can take the form of cantilevers, membranes, and array sensors. Static deflections in simple electrode configurations for PZT films supported on silicon or silicon nitride membranes are of the order of 1 μm, while larger deflections can be developed under ac and resonant excitation. High frequency acoustic actuators using capacitative excitation of polymer films have been used to evaluate the performance of piezoelectric sensors.
Current Status of and Recent Results on Group 2 Source Compounds for Vapor Phase Epitaxy of Ferroelectric Thin Films
Authors: Rees William S. , Luten Henry A. , Carris Michael W. , Caballero Celia R. , Hesse Werner , Goedken Virgil L. 
Published: March 2011

AbstractMuch interest in the area of ferroelectric thin films has been generated by the recent developments in unique property observation for these materials. As deposition methods move toward potential commercialization, the importance of chemically and thermally stable at use temperature, high vapor pressure and purity, readily available and economically competitive sources for the requisite group 2 elements will emerge. This presentation entails an initial overview of the presently utilized compounds, their advantages and disadvantages. New group 2 CVD precursors have been developed based both on inter- and intramolecular stabilization of cyclopentadienides, alkoxides and β-diketonates. Recent results on the coordination environment around the central metal atom have offered insight into the next generation of polydentate, monoanionic ligand design. Specific details are discussed for the metal complexes of “scorpion-tail” β-diketoethers. Results of comparison studies between these new precursors and earlier compounds are presented as a model for designing future sources.
The Defect Structure of BaTiO3 Thin Films
Authors: Wills L.A. , Wessels B.W. 
Published: March 2011

AbstractThe defect structure of BaTiO3 thin films grown on (100) Si was examined using transient photocapacitance spectroscopy. The concentration, optical cross section and associated energy levels of both native and impurity defects in as-grown and annealed BaTiO3 films were evaluated. Deep level defects withpeak energies of Ev+1.8, Ev+2.4, Ev+2.7, Ev+3.0-3.1 and Ev+3.2-3.3 eV were observed in the as-grown films. Upon vacuum annealing, the concentration of the traps at Ev+3.0 and Ev+3.2 eV increased while the concentration of the traps at Ev+ 1.8 and Ev+2.4 eV decreased. The levels at Ev+3.0-3.1 and Ev+3.2-3.3 eV are attributed to oxygen vacancies. The other levels are tentatively ascribed to Fe and Fe related defects.
A Model of The Metal-Ferroelectric-Metal Capacitor
Authors: Teowee G. , Uhlmann D.R. 
Published: March 2011

AbstractFerroelectric (FE) films, especially PZT films, have received increasing attention for microelectronic applications such as ferroelectric memory and high density DRAM. There has been significant progress in the preparation of high quality PZT films involving wet chemical and physical vapor deposition techniques. Metal-FE-metal structures, typified by Pt-PZT-Pt capacitors, are the basic building blocks for the ferroelectric devices. The leakage currents of the capacitors are known to be non-ohmic and exhibit an exponential dependence on applied voltage.The present paper presents a model based on totally depleted back-to-back Shottky barriers. Predictions based on the model can provide significant new understanding of the FE behavior of thin films. For example, the assumption of total depletion leads to the presence of a built-in field within the film which can explain the ubiquitously higher values of coercive field in FE films than found in bulk ceramics. It will be shown that the agreement between model predictions and actual device I-V characteristics of Pt-PZT-Pt capacitors is very close. Further, the model can also explain the observed hysteresis loop asymmetry and low dielectric constants of films of relaxor FE's, whose dielectric constants are much smaller than those of bulk materials.
Effect of Zr/Ti Ratio on The Fatigue and Retention Behavior of Sol-Gel Derived Pzt Films
Authors: Teowee G. , Boulton J.M. , Orr M.N. , Baertlein C.D. , Wade R.K. , Birnie D.P. , Uhlmann D.R. 
Published: March 2011

AbstractA series of sol-gel derived PZT films with various Zr/Ti ratios - namely PT, 0/100 - 20/80, 35/65, 53/47, 65/35, 80/20, 94/6 and PZ, 100/0 - were prepared on platinized Si wafers. Excess PbO was added to the precursor chemistries to compensate for eventual PbO loss and also to aid in obtaining the desired perovskite phase.It was found that the phase assembly, namely the presence of tetragonal or rhombohedral perovskite phases, plays an important role in determining the fatigue and retention behavior. PT-rich (or tetragonal) films offer better retention characteristics than those observed in PZ-rich (or rhombohedral) or PZT 53/47 films. Films with PZrich compositions tend to exhibit superior fatigue behavior compared with PT-rich films.
A Novel Method for Determining the Curie Temperature of Ferroelectric Films
Authors: Kwok Chi Kong , Desu Seshu B. 
Published: March 2011

AbstractA novel technique to measure the Curie temperature of ferroelectric thin films has been developed. The method is based on identifying changes in slope of film stress vs temperature plot. At the Curie temperature, ferroelectric films undergo a phase transition from ferroelectric phase to paraelectric phase. Due to this phase transformation, physical properties of films such as elastic constants and coefficients of thermal expansion also change at the Curie temperature. Consequently, at this temperature the temperature coefficient of film stress changes since it is related to elastic constants and thermal expansion coefficient. Thus, by measuring the film stress as a function of temperature, the Curie temperature can be determined. The Curie temperatures measured by this method are in good agreement with the literature values. Small discrepancies that were observed can be attributed to the intrinsic stresses present in the films.
Tunable Dielectric and Piezoelectric Characteristics of Lead Magnesium Niobate Titanate Relaxor Thin Films
Authors: Chen J. , Zhang Q. , Cross L.E. 
Published: March 2011

AbstractFerroelectric relaxor thin films Pb[(Mg1/3Nb2/3)0.9Ti0.1]O3 (90PMNIOPT) have been fabricated by the sol-gel technique. The dielectric, piezoelectric and electrostrictive characteristics have been investigated. Experimental results show that the dielectric permittivity and effective piezoelectric coefficients of the films can be tuned by varying dc bias fields which offers the useful features in designing smart micro transducer and actuator systems. Dielectric constants of the films are in the range of 5000 to 6000. The electric field induced strain is on the order of 10−3, and the maximum effective d33 coefficient of 90PMINI0PT films is as large as 265 pC/N at 31 kV/cm. The electrostrictive coefficient Q11 is on the order of 1.2 c×10−2 m4/C2 and M11 is 3.5 c×10−16 m2/V2.
Ultra-Thin Sputtered Pzt Films for Ulsi Drams
Authors: Kim Jiyoung , Sudhama C. , Khamankar Rajesh , Lee Jack 
Published: March 2011

AbstractIn this work, a high-temperature deposition technique has been developed for ultra-thin sputtered PZT films for ULSI DRAM (<256Mb) storage capacitor applications. In contrast to the previously developed low-temperature (200°C) deposition, deposition at high-temperature (400°C) yields a desirable reduction in grain size of the perovskite phase. The thickness of PZT films has been reduced to less than 30nm with high charge storage density (∼30μC/cm2) and low leakage current density. An optimized 65nm PZT thin film was found to have an equivalent SiO2 thickness of 1.9Å and a leakage current density of less than 10−6 A/cm2 under 2V operation.
Pyroelectric Properties of Lead Based Ferroelectric thin Films
Authors: Patel A. , Tossell D.A. , Shorrocks N.M. , Whatmore R. W. , Watton R. 
Published: March 2011

AbstractLead based thin ferroelectric films have been prepared using both sol-gel and dual ion beam sputtering (DIBS) processes. Material compositions within the PbTiO3 and PLZT system have been deposited by both techniques onto metallised silicon. By using a standard sol-gel prepared solution, modified with acetylacetone and spin-coating, lµm thick fully perovskite layers, were obtained at low temperature (450°) with some preferred orientation. The grain size was in the range 0.2-0.4µm. A dielectric constant of 400 and a reversible pyroelectric coefficient of 1.2 × 10−4Cm−2K−1 were obtained. In contrast, a range of capping layers (SiO2, A12O3, BPSG) on silicon have been investigated using the DIBS process. Highly crystalline (100) and (111) films were readily produced at temperatures in excess of 550°, at a growth rate of 0.3µm/hour. Control of stoichiometry has also been studied in detail, by sputtering of a composite metal-ceramic target with a high energy Kr beam and by bombarding the growing film with a low energy oxygen ion-beam. Dielectric constants of 200-300, losses below 0.015 and resistivities above 1010Ωm have been achieved. A pyroelectric coefficient of the order of 2.5 × 10−4Cm−2K-1, pre-poled for a La-doped film on BPSG capped Si was obtained, which did not increase significantly on poling.
Materials Characterization of Nondestructive Readout Nonvolatile Memory Devices
Authors: Tuttle Bruce A. , McIntyre Dale C. , Seager Carleton H. , Garino Terry J. , Warren William L , Evans Joseph T. , Waldman Robert W. 
Published: March 2011

AbstractPrototype ferroelectric thin film, nonvolatile memory, nondestructive readout (NDRO), semiconductor devices have been fabricated. The “1” and “0” logic states of these prototype devices are in principle determined by the modulation of the conductivity of a semiconductor film channel by the polarization state of the underlying ferroelectric thin film layer. Programmed resistance ratios of the two logic states of 5:1 are demonstrated. While the best performance to date has been achieved for devices that have a 40 nm ln2O3 film covering a 300 nm thick PZT 20/80 layer, we also develop criteria for selecting semiconductor films that will improve performance for this NDRO device design. Among the other semiconductor films that are characterized with respect to this criteria are boron doped Ge, ZnO and aluminum doped ZnO. It is demonstrated that by appropriate donor doping of ZnO films the effects of intrinsic defects are masked and that process temperatures can be extended by 300×C.
Integrated Pyroelectric Infrared Sensor Using Pvdf thin Film Deposited by Electro-Spray Method
Authors: Asahi Ryouji , Sakata Jiro , Tabata Osamu , Mochizuki Midori , Sugiyama Susumu , Taga Yasunori 
Published: March 2011

AbstractA pyroelectric infrared sensor using a poly(vinylidene fluoride) (PVDF) thin film has been integrated with a read-out circuit on a silicon substrate. The PVDF thin film with a thickness of 1-2 µm was deposited on the sensing area by an electro-spray (ESP) method. A form I crystal and a large pyroelectric coefficient of 4 nCcm−2K−1 were observed just after the deposition without any poling treatments. The fabrication process of the sensor was based on a standard MOS LSI process and a polysilicon sacrificial layer etching technique. In order to reduce the heat capacitance and the thermal conduction, the PVDF thin film was supported on a thin Si3N4 membrane structure formed by etching a part of the silicon substrate under the sensing area. The sensor with a sensing area of 400x400 µm2 had a responsivity of 98 V/W, a detectivity of l.4× 107 cmHz1/2W−1, an NEP of 2.9× 10−99 Hz1/2W at a frequency of 100 Hz and a time constant of 1.3 msec.
Photo-Induced and Electrooptic Properties of (Pb,La)(Zr,Ti)O3 Films
Authors: Dimos D. , Warren W.L. , Tuttle B.A. 
Published: March 2011

AbstractPhoto-induced changes in the hysteresis behavior of sol-gel derived Pb(Zr,Ti)O3 (PZT) and (Pb,La)(Zr,Ti)03 (PLZT) films have been characterized. The film photosensitivity has been evaluated with respect to the magnitude of the effects, the time response and the spectral dependence. Photo-induced hysteresis changes exhibit a stretched-exponential time dependence, which implies a dispersive mechanism. The spectral dependence is strongly peaked at the band edge (∼3.4 eV), which indicates that generation of electron-hole pairs in the material is critical. The photo-induced hysteresis changes are reproducible and stable, which indicates that the controlling charge traps are stable. However, improvements in film photosensitivity will be required to develop these materials for optical memory applications.
Effect of Elastic Stress on Phase Selection in a Binary System
Authors: Huh Joo-Youl , Johnson William C. 
Published: March 2011

ABSTRACTElastic stress arising from differences in lattice parameters between phases is known to alter both qualitatively and quantitatively the characteristics of phase equilibria in coherent systems. One important consequence of misfit or epitaxial strain is the possible existence of several linearly stable equilibrium states: For a given composition, temperature and applied stress, different combinations of volume fraction and corresponding phase compositions render the free energy of the system a minimum. Here, we examine how epitaxial stresses influence phase equilibria in a binary alloy when the system can select from three different phases. In particular, we show the existence of several equilibrium states with different combinations of phases that minimize the system free energy.
The Formation of Epitaxial Eutectic Modulated Structures
Authors: Roytburd Alexander L. , Sung Gisuk 
Published: March 2011

ABSTRACTThe thermodynamics of the formation of a coherent epitaxial two-phase modulated structures from a liquid solution is considered. It is shown that elastic interactions in the epitaxial system change the topologic features of the eutectic phase diagram. As a consequence an eutectic point splits into two eutectic points or it is transformed into a consolute point.
Analysis of Structural Transformations in High Fluence Nitrogen Ion Implanted Aluminium
Authors: Calvo L. , Perez-Rodriguez A. , Romano-Rodriguez A. , Moranteand J.J. , Montserrat J. 
Published: March 2011

ABSTRACTThe structural analysis of Al layers on Si obtained by sputtering at different conditions and implanted with nitrogen (with doses of 2.5×10'17 and 5×1017 N2+ ions/cm2, energy 150 keV, room temperature) is performed by SRP, SIMS and TEM measurements. The correlation between these measurements shows the formation of AIN crystalline precipitates already at the substoichiometric dose. SRP and TEM reveal the presence of a buried layer with resistivity higher than the Al matrix, with a high concentration of AIN precipitates. The morphology of this layer is affected by surface roughness. For the higher dose, a buried continuous AIN polycrystalline dielectric layer is formed. Moreover, the SIMS measurements suggest a gettering effect of Si in the buried layer.
Amorphization of Fe/Zr Multilayers by Ar-Ion-Beam-Mixing
Authors: Kopcewicz M. , Jagielski J. , Stobiecki T. , Stobiecki F. , RÖLL K. 
Published: March 2011

ABSTRACTThe Ar-ion-beam-mixing of the FeZr multilayer system is studied by conversion electron Mdssbauer spectroscopy. The dependence of the amorphization process on the layer thickness and ion dose is studied in detail for samples with Fe to Zr ratio of 1 and 0.5 and modulation wavelength of 5 to 90 nm.
Temperature Dependence of Ion Beam Mixing of Ingaas Marker Layers in GaAs
Authors: Forbes D.D. , Coleman J.J. , Klatt J.J. , Averback R.R. 
Published: March 2011

ABSTRACTIon beam mixing of In0.20Ga0.80As quantum well marker layers in GaAs following 1 MeV Kr ion irradiation has been measured as a function of irradiation temperature and fluence. Secondary Ion Mass Spectrometry (SIMS) was used to measure the diffusion of the In0.20Ga0.80As layer following irradiation at various temperatures. Rutherford Backscattering (RBS) and channeling methods were used to determine the extent of the amorphization as a result of the implantation. The mixing parameter of the In0.20Ga0.80As in the GaAs matrix increased from σ120 Å5/eV at 77K to σ160Å5/eV in the temperature range of 300K–450K, but decreased somewhat at 573K. This behavior of In0.20Ga0.80As marker layers will be compared to AlAs marker layers which show similar temperature dependence. These results are interpreted on the basis of thermal spikes and crystal structure.
Ion Bombardment Effects on the Growth of Rutile Phase of Reactively Sputtered TiO2 Thin Films
Authors: Wicaksana D. , Tsujikawa T. , Kobayashi A. , Ono K. , Kinbara A. 
Published: March 2011

ABSTRACTTitania thin films grown by reactive bias sputtering were characterized. In order to investigate the role of energetic ion on the growth of crystalline phases of TiO2 thin films, we applied substrate biases during deposition. The structural properties were analyzed using X-ray diffractometry (XRD), and related to the optical properties of the films. The atomic composition was determined using Rutherford backscattening spectrometry (RBS).Negative substrate bias, Vb, showed a significant influence on the phase formed composition and microstructure: Vb in the range of 15 and 60 V enhanced the growth of crystalline phases and the rutile dominated the phase composition. However, the quantity of rutile decreased when Vb was raised to 100 V. The excess of oxygen was shown in the films by RBS.
Phase Transformation of Co Silicidation in the Co/Ti- and Ti/Co-Si(100) Systems
Authors: Hong Feng , Patnaik Bijoy K. , Li Bingzong , Liu Ping , Sun Zen , Rozgonyi George A. 
Published: March 2011

ABSTRACTCo silicide formed via selective diffusion of Co through a Ti interfacial layer has been reported by several groups. In this report, phase identification of the silicide has been further studied for both Co/Ti and Ti/Co multi- and bilayers deposited on p(100)-Si substrates. The samples were either vacuum furnace or RTA annealed from 550°C to 900°C. The Co silicide formation sequence in the Co/Ti-Si systems follows CoSi2→Co2Si→CoSi→CoSi2 with the formation temperature increasing for each phase. The Co/Ti bilayer CoSi to CoSi2 transformation temperature was lower than that for the six layer Co/Ti system. For the multilayer sample with Co as the first layer in contact with the Si substrate, CoSi2 formed at 550°C and then CoSi was observed at higher temperatures due to the effect of Co supply on disilicide phase instability. Epitaxial CoSi2 growth occured at higher temperatures after the removal of the unreacted upper layers. A 15 μΩ-cm film resistivity was obtained from 50 nm epitaxial CoSi2.