bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non-Equilibrium Wetting at Aluminium-Sapphire Interfaces
Authors: Levi George , Kaplan Wayne D. 
Published: April 2011

AbstractUnder most experimental conditions, the wetting of Al2O3 by liquid Al is a non-equilibrium phenomenon characterised by the continuous oxidation of Al. While the effect of oxygen at the liquid Al-vapour interface appears to be well understood, less is known about the influence of oxygen at the liquid Al-sapphire interface, due to a lack of microstructural evidence. Sessile drop experiments of liquid Al on sapphire (α-Al2O3) were conducted under a low pressure (10-3Torr) controlled Ar atmosphere as a function of oxygen partial pressure, temperature and/or time. Microstructural investigations of the samples from the wetting experiments indicated that two different dominant processes occur at the liquid Al-sapphire interface: epitaxial growth of new α-Al2O3 layers on the sapphire substrate at temperatures below ≍1100°C and dissolution of the sapphire substrate at temperatures above ≍1100°C.The microstructural evidence indicates possible mechanisms by which oxygen is involved in the non-equilibrium wetting and adhesion of liquid Al on sapphire. The non-wetting to wetting transition in this system may be explained by the formation of an oxygen-rich interphase at the liquid Al-sapphire interface.
Sol-Gel Derived Pyroelectric Barium Strontium Titanate Thin films for Infrared Detector Applications
Authors: Cheng Jian-Gong , Tang Jun , Guo Shao-Ling , Chu Jun-Hao 
Published: April 2011

AbstractBa0.8Sr0.2TiO3 thin films that are suitable for infrared detector applications have been prepared with a sol-gel process using a highly diluted precursor solution. Columnar structure with grain size close to 200 nm was obtained with layer-by-layer homoepitaxy due to a very small thickness of individual layer. The measured pyroelecrtic coefficient is larger than 3.1×10划4 C/m2K at the temperatures ranging from 10 to 26 °C and reaches the maximum value of 4.1×10划4 C/m2K at 16.8 °C. The infrared detectivity of 4.6×107 cmHz1/2W划1 has been obtained at 19 °C and 10 Hz in the Ba0.8Sr0.2TiO3 films deposited on thick (500 μm) platinum coated silicon substrates. The better infrared response can be expected by the improvement in the thermal isolation of pyroelectric element and the electrode materials.
A Modified SBN System for Pyroelectric Sensors
Authors: Amorín H. , Guerrero F. , Portelles J. , Venet M. , Fundora A. , Siqueiros J. M. 
Published: April 2011

AbstractThe Thermally Stimulated Depolarization Current (TSDC) and pyroelectric properties of the modified SBN ferroelectric ceramic system were studied for different lanthanum and titanium doping concentrations. The TSDC measurements show the pyroelectric peak for all compositions while a second smaller peak at higher temperature, possibly associated to induced vacancy-impurity dipoles, is also observed in all cases. The second peak contribution was experimentally and mathematically eliminated to determine the remanent polarization and pyroelectric coefficient, both associated only to permanent ferroelectric dipoles. The figures of merit for sensor devices are determined for all compositions and compared with those of other pyroelectric systems. The La0.03Sr0.255Ba0.7 Nb1.95Ti0.05O5.975 sample, in particular, has excellent pyroelectric response, making this material very suitable for pyroelectricity-derived applications.
Piezoresponse Measurement and Imaging of Electromechanical PZT and PZN-BT thin Films
Authors: Morros C. , Corbett M.H. , Catalan G. , Gregg J.M. , Bowman R.M. 
Published: April 2011

AbstractPulsed laser deposition (PLD) was used to growth thin films of lead zirconium titanate (PZT) and lead zinc niobate-barium titanate (PZN-BT). The PZT films were prepared from commercial PZT-5H ceramic target and the PZN-BT made from target made using a modified Columbite method. The PZT films had dielectric constants of 300 and loss of 0.03 at 10kHz, whilst for the PZN-BT films they were 350 and 0.03 respectively at 300K. Hysteresis measurements confirmed their switching propertiesA piezoresponse microscope based on a modified atomic force microscope was developed to determine electromechanical response at a sub-micrometer resolution. The PZT films yielded d33 ∼100pm/V. Mapping measurements on the PZT demonstrated local switching of individual grains. First measurements of piezoresponse of PZN-BT yielded values in the region 150-200 pm/V.
Ferroelectric and Fatigue Properties of Alkoxy-Derived CaBi2Ta2O9 Thin Films
Authors: Kato Kazumi , Suzuki Kazuyuki , Nishizawa Kaori , Miki Takeshi 
Published: April 2011

AbstractCaBi2Ta2O9 (CBT) thin films were successfully prepared on Pt-passivated quartz glass substrates using a triple-alkoxide solution. The thin film crystallized to a single phase of perovskite at 750°C via a mixture of fluorite and perovskite phases. The 750°C-annealed thin film showed random orientation and consisted of fine grains with a diameter of about 80 nm. The dielectric constant and loss factor were 124 and 0.04, respectively, and were constant in the frequency range of 10 kHz to 1 MHz. The thin film exhibited P-E hysteresis loops at relatively high voltages. The remanent polarization and coercive electric field were 6.9 μC/cm2 and 170 kV/cm at 13 V, respectivey. The fatigue behaviors against various electric pulse sequences were examined. The polarization did not change when the pulse width was short such as 10-6 s, however, it increased gradually with number of switching cycles when the pulse width was relatively long such as 10-3 s.
Preparation and Characterization of (Bi,La)4Ti3O12 Films by the Sol-Gel Technique
Authors: Tokumitsu Eisuke , Isobe Takeaki , Kijima Takeshi , Ishiwara Hiroshi 
Published: April 2011

Abstract(BiLa)4Ti3O12 (BLT) films have been fabricated by the sol-gel technique and characterized. It is shown that the partially replacing Bi with La can promote the crystallization, hence can reduce the crystallization temperature of the film. It is also demonstrated that crystalline orientations of sol-gel derived ferroelectric BLT films can be controlled by the growth conditions.
Degradation of Ferroelectric Capacitors during Metal Etching and Ashing Processes
Authors: Park Chanro , Kwon O Sung , Seol Yeo Song , Kim Jin Woong , Yoon Hee Koo 
Published: April 2011

AbstractPolarization degradation due to metal etch and/or photoresist(PR) strip processes has been investigated for Pt/SrBi2Ta2O9(SBT)/Pt ferroelectric capacitors. Interconnect metal line consisting of TiN/Al/Ti/TiN/Ti layers has been patterned by normal photolithography and plasma etch processes. We used two different sources for metal etcher, helicon or electron cyclotron resonance(ECR) source, and stripped the PR with either microwave or helicon source stripper. Polarization degradation was evaluated by measuring switching and non-switching polarization of the ferroelectric capacitors.Neither etch machine nor etch parameters played an important role for determining polarization of the ferroelectric capacitors. Photoresist strip process, however, significantly affected the polarization of the ferroelectric capacitors. Factors affecting polarization of the ferroelectric capacitors were presence of hydrogen and plasma density during the strip process. Hydrogen atoms and protons produced by H2O or NH3 plasma penetrated through the dielectric layer and caused hydrogen induced damage. Thus the hydrogen damage was dependent on strip temperature and time. Photoresist strip with high density plasma results in charging damage to ferroelectric capacitors. It is believed that charges from the plasma are trapped at domain boundaries and interfaces, leading to polarization degradation. Damage free metal etching process for the ferroelectric capacitor was applied for the fabrication of the fully working ferroelectric random access memory.
Preparation and Characterization of MFM and MFIS Structures Using Sr2(Ta1划x, Nbx)2O7 Thin Film by Pulsed Laser Deposition
Authors: Okuyama Masanori , Nakaiso Toshiyuki , Noda Minoru 
Published: April 2011

AbstractSr2(Ta1划x, Nbx)2O7(STN) ferroelectric thin films have been prepared on SiO2/Si(100) substrates by the pulsed laser deposition (PLD) method. Preferential (110) and (151)-oriented STN thin films are deposited at a low temperature of 600°C in N2O ambient gas at 0.08 Torr. A counterclockwise C-V hysteresis was observed in the metal-ferroelectric-insulator-semiconductor (MFIS) structure using Sr2(Ta0.7, Nb0.3)2O7 on SiO2/Si deposited at 600°C. Memory window in the C-V curve spreads symmetrically towards both positive and negative directions when applied voltage increases and the window does not change in sweep rates ranging from 0.1 to 4.0×103 V/s. The C-V curve of the MFIS structure does not degrade after 1010 cycles of polarization reversal. The gate retention time is about 3.0×103 sec when the voltages and time of write pulse are ±15V and 1.0 sec, respectively, and hold bias was -0.5 V.
Ferroelectric Properties of La-doped Bi4Ti3O12 Thin Films deposited directly on Si by pulse-injection MOCVD
Authors: Kim Joon Hyeong , Kim Jin Young , Kim Hyeong Joon 
Published: April 2011

Abstract(Bi,La)4Ti3O12(BLT) thin films were prepared on Si(100) substrates by the pulse injection metalorganic chemical vapor deposition (MOCVD) process, in which Ti and La precursors were injected with periodic pauses while Bi precursor was supplied continuously. In case of the pulse injection method, the film composition was relatively uniform and the Bi content at the interface was relatively uniform and the Bi content at the interface was increased. The BLT films, which were deposited by the pulse injection MOCVD, showed better crystallinity and thinner ionterfacial amorphous layer than the continuous BLT films. The continuous BLT films, although measured at 1 MHz showed similar C-V characteristics to those measured at low frequency region, and their flatband voltages also shifted severely to the negative voltage direction. On the other hand, the pulse BLT films exhibited clockwise ferroelectric hysteresis in the C-V curves. The memory window and the leakage current density were about 2V and 1.46×10−7 A/cm2 at 9V (180 kV/cm), respectively.
Suppression of Oxidation of an Epitaxial (100)ZrN Film on Si During the Deposition of Ir Film
Authors: Horii Sadayoshi , Horita Susumu 
Published: April 2011

AbstractThe epitaxial (100)ZrN film on the (100)Si substrate is oxidized during Ir film sputtering deposition on (100)ZrN/(100)Si structure. Although the oxidation could be suppressed somewhat by increasing the deposition rate of the Ir film, it was not enough. In order to suppress the oxidation completely, 10 pieces of 10 × 10 mm2 Zr metallic plates were circularly placed on the non-erosion area of the Ir disc target. Using this target, the oxidation of the ZrN film was suppressed perfectly. Also, by adjusting of the diameter of the placed Zr circle, the contamination caused by Zr to the Ir film is avoided.
MOCVD Kinetics of Precursors for Ferroeletric SBT film
Authors: Baeri A. , Condorelli G.G. , Fragalà I.L. 
Published: April 2011

AbstractThe metal organic chemical vapour deposition kinetics of Sr(hfa)2(tet) (H-hfa =1,1,1,5,5,5-hexafluoroacetylacetone and tet= tetraglyme) and Bi(C6H5)3 single precursors have been studied upon varying operational deposition parameters, namely temperature and precursor partial pressure. These precursors are of interest for the MOCVD of SBT ferroeletric thin films. Depending upon experimental conditions, deposition processes occur either in the reaction rate limited regime or in the mass transport regime. Kinetics controlled by reaction rates (T deposition< 673 K) gives insights on the process mechanisms. The activation energies of the Sr and Bi deposition processes have been determined from the Arrhenius plots.SrBi2Ta2O9 films were grown on industrial Pt/Ti/SiO2/Si substrates and perovskite phase films were obtained after annealing in O2 environment at 1073K.
Manufacturability Study for Etching High-Density BST/Pt Capacitors
Authors: Hwang Jay 
Published: April 2011

AbstractProfile control, process repeatability and productivity concerns in etching Pt electrodes are reviewed specifically for application in fabricating high-density BST/Pt capacitors. The approach of using a high temperature cathode in a high-density reactive plasma chamber has produced a repeatable >85° Pt profile, stable etch rate and low particle results over a 500-wafer marathon test. A “corrosion-like” BST defect can be prevented by adding a post etch treatment to remove any corrosive residue from the wafer surface. A feasible manufacturing solution for etching BST/Pt capacitors for future high-density DRAM application is demonstrated.
Imaging Mechanism and Quantification of Scanning Probe Microscopies on Ferroelectric Surfaces
Authors: Kalinin Sergei V. , Bonnell Dawn A. 
Published: April 2011

AbstractIn the last few years a wide spectrum of non-contact, intermittent contact and contact scanning probe microscopies have been applied to imaging ferroelectric surfaces. The imaging mechanism in non-contact SPM is ultimately related to the total charge distribution on the ferroelectric surface, including both polarization and screening charges. Contact voltage modulation (piezoresponse) force microscopy (PFM) is sensitive to both local polarization via electromechanical coupling and surface charge via capacitive interactions. In the present research we analyze the electrostatic and electromechanical contrast in PFM using analytical solutions for the electrostatic sphere-dielectric plane problem and for the piezoelectric indentation problem. The contribution of electrostatic forces to the image is estimated. Variable-temperature PRI imaging of domain structures in BaTiO3 is performed and the temperature dependence of the piezoresponse is compared with the Ginzburg - Devonshire theory.
Self-polarization Mechanism in Textured Pyroelectric Pb(Ti1-xZrx)O3 films
Authors: Suchaneck G. , Gerlach G. , Poplavko Yu. , Kosarev A. I. , Andronov A. N. 
Published: April 2011

AbstractSelf-polarization of Pb(Ti1−xZrx)O3 (PZT) thin films is explained on the basis of the formation of a TiO2−x-enriched interlayer close to the bottom electrode. Electrons provided by oxygen vacancies generate a n-type interface layer in the PZT at the electrode. A graded ferroelectric layer is then formed by electron injection from the bottom electrode and electron trapping on Ti4+ ions. A “built-in” difference in free energy forms which acts to pole the ferroelectric. Band bending was observed by contact potential difference measurements at a distance of 70 to 90 nm from the bottom electrode.
Near field Optical second Harmonic Imaging of the Polydomain Structure of Epitaxial PbZrxTi1−xO3 thin films
Authors: Liang H.Y. , Smolyaninov I.I. , Lee C.H. , Davis C.C. , Nagarajan V. , Ramesh R. 
Published: April 2011

AbstractNear field optical second harmonic microscopy has been applied to imaging of the c/a/c/a polydomain structure of epitaxial PbZrxTi1−xO3 thin films in the 0<x<0.4 range. An uncoated adiabatically tapered fiber tip was employed in our microscope which, according to our previous research [5] could yeild a resolution of up to 80 nm. Experimentally measured nearfield second harmonic images have been compared with the results of theoretical calculations. Good agreement between theory and experiment has been demonstrated. Thus, novel optical technique for nanometer scale ferroelectric domain imaging has been developed.
Magnetic Losses in Thick Barium-Hexaferrite Films on MgO (111)
Authors: Yoon S.D. , Oliver S.A. , Shi P. , Zuo X. , Vittoria C. 
Published: April 2011

ABSTRACTBarium hexaferrite films having thickness from 3 to 30 μm were deposited onto 0.5 mm Magnesium Oxide (111) substrates, and were examined by vibrating sample magnetometry, torque magnetometry, x-ray diffraction, and scanning electron microscope measurements. Ferrimagnetic resonance measurements were taken with the magnetic field applied perpendicular to the film plane. The FMR linewidth values for as-produced 3 - 30 μm films was 0.45 - 0.70 kOe, and was reduced to 0.06 - 0.45 kOe after annealing at 1000 °C for 2 hours. Further annealing increased the linewidth. The FMR linewidth for the 30 μm thick film was also found to decrease upon mechanically removing 55 ∼ 77 % of the substrate thickness. A 6-fold in-plane anistropy symmetry in the anisotropy energy was observed in torque magnetometry measurements for films thicker than 30 μm. These results can be interpreted as due to film inhomogeneity, stress, and the growth of small regions of non c-axis textured material.
Elastic and Inelastic Properties of Electroplated Nickel Used in LIGA Techniques
Authors: Skandar Basrour , Patrick Delobelle 
Published: April 2011

ABSTRACTThe aim of this paper is a wide investigation at the micro scale of the elastic and inelastic properties of electroplated Nickel, which is extensively used in the LIGA techniques. Using a nano-indentation set-up, we have obtained the Berkovitch's hardness HB and the Young's modulus E. These mechanical properties are affected by the current densities used during the electroplating as well as the nature of the substrates. The roughness Ra was obtained thanks to confocal microscopy and a linear behavior of HB versus 1/ Ra corresponds to a Hall and Petch relation. The yield stress Y0 and the ultimate strength Q have been deduced from the experimental measurements using a Finite Element Method (FEM).Q has been found sensitive to the deposition conditions. Moreover (Y0+Q) has shown a linear dependence versus the hardness HB. Finally, Nickel microbeams fabricated by LIGA technique have been characterized with a bending test. The data deduced from this method, i.e. E and Y0+Q, are in good agreement with the results obtained by nano-indentation.
Dielectric and Pulsed Spectroscopy of Shear Mode PZT Microactuator
Authors: Brünahl Jürgen , Grishin Alex , Khartsev Sergey 
Published: April 2011

ABSTRACTFerroelectric lead zirconate titanate (PZT) is the main industrial product in piezoelectric ceramic materials used for sensor and actuator applications. High precision in manufacturing of microelectromechanical systems is essential to get demanded performance accuracy. An adequate and preferably non-destructive measurement technique is desired to characterize the materials properties at various stages of device fabrication as well as to find correlation between the processing parameters, microstructure and functional properties. We report on a new pulsed technique, which has been employed to characterize all relevant properties of special machined array of PZT channels quickly, reliably and reproducibly: dielectric constant, loss factor tan σ, electromechanical coupling coefficient, resonance frequency and mechanical quality factor Q as well as temperature dependencies of these parameters.
Multilayer Materials for Electrostatic Switches
Authors: Phillips Mark A , Peterson Brennan L , Esber Christine M , Hwang Jesse , Clemens Bruce M 
Published: April 2011

ABSTRACTMetal multilayers are a unique way to manufacture reliable conductive members for MEMS devices. These members are particularly suited for electrostatic switches. Unlike elemental Al, which experiences curvature problems during processing, the residual stress in these beams can be controlled and calibrated during stress measurements to have repeatable shapes and stresses upon release. In this study, curvature experiments were performed to determine the optimal deposition parameters (pressure, thickness) to produce metal multilayer beams with zero average stress and zero bending moment, which can be obtained by alternating tensile and compressive layers within. Resistivity measurements were made to determine the effect of interfaces on resistivity.
Effect of La on the Growth of Cu6Sn5 Intermetallic Compound for Improved Sn-Pb Solder Joints
Authors: Ma Xin , Fang Hongyuan , Qian Yiyu , Yoshida Fusahito 
Published: April 2011

ABSTRACTSmall amount of rare earth element La were added into the traditional Sn60-Pb40 solder alloy in order to improve the reliability of solder joints. The results of aging tests of solder joints showed that, the growth of interface Cu6Sn5 intermetallic compound was depressed by La addition. Furthermore, the thermal fatigue life of solder joints was improved by 3 times. Thermodynamic analysis indicated that La had higher affinity with Sn in the Sn-Pb-La system, and then the driving force for Cu6Sn5formation was reduced since the activity of Sn was lowered.
Measurements of Residual Stress in the Layers of Thin Film Micro-Gas Sensors
Authors: Kim Youngman , Choo Sung-Ho 
Published: April 2011

ABSTRACTThe mechanical properties of thin film materials are known to be different from those of bulk materials, which are generally overlooked in practice. The difference in mechanical properties can be misleading in the estimation of residual stress states in micro-gas sensors with multi-layer structures during manufacturing and in service.In this study the residual stress of each film layer in a micro-gas sensor was measured according to the five difference sets of film stacking structure used for the sensor. The Pt thin film layer was found to have the highest tensile residual stress, which may affect the reliability of the micro-gas sensor. For the Pt layer the changes in residual stress were measured as a function of processing variables and thermal cycling.
Control of Stress with Growth Conditions and Mechanical Parameters Determination of 3C-SiC Heteroepitaxial Thin Films
Authors: Gourbeyre C. , Chassagne T. , Berre M. Le , Ferro G. , Malhaire C. , Monteil Y. , Barbier D. 
Published: April 2011

ABSTRACTWe report here on the influence of the epitaxial growth conditions on the residual stress of heteroepitaxial 3C-SiC grown on silicon using atmospheric-pressure chemical vapour deposition (APCVD) and on the determination of its mechanical properties. 3C-SiC films were grown on (100) Si substrates in a vertical reactor by APCVD. SiH4 and C3H8 are used as precursor gases and H2 as carrier gas. The growth procedure involves the formation of a carburization buffer layer at 1150°C under a mixture of H 2 and C3H8. The epitaxial growth occurs then at 1350°C by adding SiH 4.For as-deposited films the measurement techniques implemented are substrate curvature measurements, AFM, and nano-indentation. For micromachined self-suspended SiC membranes, load deflection measurements were used. The substrate curvature measurement leads to the determination of the residual stress in the deposited SiC film. We show that we can achieve 3C-SiC layers with a compressive or a tensile state having equivalent crystallinity. Whereas thermal mismatch just accounts for tensile stresses, we demonstrate that 3C-SiC thin films may have compressive stresses by using specific conditions for the formation of the buffer layer. The early stage of growth is indeed of major importance.Regarding the mechanical properties, the 3C-SiC Young's modulus was determined using nano-indentation. Its mean value reaches 378 GPa comparable to the calculated value of 307 GPa. As test structures, we have processed self-suspended SiC membranes. Load deflection measurements enable the determination of the Young's modulus and the residual stress of the self-suspended films. For self-suspended SiC membranes, the absolute value of the residual stress in the SiC thin films decreases compared to the as-deposited films and takes a mean value of 170 MPa in a tensile state.