bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integration and Performance Improvements of Silicon Nanocrystal Memories
Authors: Hiramoto T. , Kim I. , Saitoh M. , Yanagidaira K. 
Published: April 2011

ABSTRACTThe silicon nanocrystal memory, that is one of the most promising devices for future non-volatile memory, is extensively investigated by experiments and simulation. The silicon nanocrystal memory cells are successfully integrated using the state-of-the-art 0.13 μm DRAM technology. The mechanism of the two-bit-per-cell operation, that is one of the unique features of silicon nanocrystal memory, is investigated and it is shown that the degree of DIBL determines the read scheme of the two-bit-per-cell operation. Moreover, the dependences of memory characteristics on device structures are examined by fabrication and measurements and it is found that the ultra-thin-body SOI and double-gate structures have better memory characteristics.
Optimisation and Simulation of an Alternative nano-flash Memory: the SASEM device.
Authors: Krzeminski C. , Dubois E. , Tang X. , Reckinger N. , Crahay A. , Bayot V. 
Published: April 2011

ABSTRACTProcess simulation are performed in order to simulate the full fabrication process of an alternative nano-flash memory in order to optimise it and to improve the understanding of the dot storage formation. The influence of various parameters (oxidation temperature, nanowire shape) have been investigated.
Improvement of Ferroelectric Properties of Lead Zirconate Titanate Thin Films by Ion-substitution using Rare-earth Cations
Authors: Nakaki Hiroshi , Uchida Hiroshi , Okamoto Shoji , Yokoyama Shintaro , Funakubo Hiroshi , Koda Seiichiro 
Published: April 2011

ABSTRACTRare-earth-substituted tetragonal lead zirconate titanate thin films were synthesized for improving the ferroelectric property of conventional lead zirconate titanate. Thin films of Pb1.00REx (Zr0.40Ti0.60)1-(3x /4)O3 (x = 0.02, RE = Y, Dy, Er and Yb) were deposited on (111)Pt/Ti/SiO2/(100)Si substrates by a chemical solution deposition (CSD). B-site substitution using rare-earth cations described above enhanced the crystal anisotropy, i.e., ratio of PZT lattice parameters c/a. Remanent polarization (Pr) of PZT film was enhanced by Y3+-, Dy3+- and Er3+-substitution from 20 μC/cm2 up to 26, 25 and 26 μC/cm2 respectively, while ion substitution using Yb3+ degraded the Pr value down to 16 μC/cm2. These films had similar coercive fields (Ec) of around 100 kV/cm. Improving the ferroelectric property of PZT film by rare-earth-substitution would be ascribed to the enhancement of the crystal anisotropy. We concluded that ion substitution using some rare-earth cations, such as Y3+, Dy3+ or Er3+, is one of promising technique for improving the ferroelectric property of PZT film.
Semiconductor Nanocrystal Floating-gate Memory Devices
Authors: Dimitrakis P. , Normand P. 
Published: April 2011

ABSTRACTCurrent research directions and recent advances in the area of semiconductor nanocrystal floating-gate memory devices are herein reviewed. Particular attention is placed on the advantages, limitations and perspectives of some of the principal new alternatives suggested for improving device performance and reliability. The attractive option of generating Si nanocrystal memories by ion-beam-synthesis (IBS) is discussed with emphasis on the ultra-low-energy (ULE) regime. Pertinent issues related to the fabrication of low-voltage memory cells and the integration of the ULE-IBS technique in manufactory environment are discussed. The effect on device performance of parasitic transistors that form at the channel corner of shallow trench isolated transistors is described in details. It is shown that such parasitic transistors lead to a substantial degradation of the electrical properties of the intended devices and dominates the memory behavior of deep submicronic cells.
A Model of Silicon Nanocrystal Nucleation and Growth on SiO2 by CVD
Authors: Stoker M. W. , Merchant T. P. , Rao R. , Muralidhar R. , Straub S. , White B. E. 
Published: April 2011

ABSTRACTSilicon nanocrystals can be used in non-volatile memory devices to reduce susceptibility to charge loss via tunnel oxide defects, allowing scaling to smaller sizes than possible with conventional Flash memory technology. In order to optimize device performance, it is desirable to maximize the nanocrystal density and surface coverage, while maintaining sufficient inter-crystallite separation to limit electron tunneling between adjacent crystallites. Ideally, crystallite densities in excess of 1012cm-2 with relatively narrow particle size distributions must be obtained, posing a significant challenge for process development and control. In order to facilitate development of such a process, a rate-expression-based model has been developed for the nucleation and growth of silicon nanocrystals on SiO2 in a CVD process. The model addresses the phenomena of nucleation, growth, and coalescence and includes the effects of exclusion zones surrounding the growing nuclei. The model uses a phenomenological expression to describe the nucleation rate and assumes that following nucleation, crystallite growth is dominated by gas-phase deposition processes, analogous to CVD of polycrystalline silicon. The model-predicted time-evolutions of crystallite densities and crystallite size distributions are consistent with experimental distributions as measured by Scanning Electron Microscopy (SEM). By coupling the model to a reactor-scale model of polysilicon CVD, it is possible to predict variations in the crystallite size distributions at various locations across a wafer as a function of reactor settings (temperature, pressure, flow rates, etc…). This in turn can be used for process control and optimization in order to ensure uniform deposition of nanocrystals in a large-scale manufacturing environment.
Oxidation of Si nanocrystals fabricated by ultra-low energy ion implantation in thin SiO2 layers
Authors: Coffin H. , Bonafos C. , Schamm S. , Cherkashin N. , Respaud M. , Ben Assayag G. , Dimitrakis P. , Normand P. , Tencé M. , Colliex C. , Claverie A. 
Published: April 2011

ABSTRACTThe effect of annealing in diluted oxygen on the structural characteristics of thin silicon dioxide layers with embedded Si nanocrystals fabricated by ultra-low energy ion implantation (1 keV) is reported. The nanocrystal characteristics (size, density, coverage) have been measured by spatially resolved Electron Energy Loss Spectroscopy using the spectrum-imaging mode of a Scanning Transmission Electron Microscope. Their evolution has been studied as a function of the annealing duration under N2+O2 at 900°C. An extended spherical Deal-Grove model for the self-limiting oxidation of embedded silicon nanocrystals has been carried out. It shows that stress effects, due to the deformation of the oxide, slows down the chemical oxidation rate and leads to a self-limiting oxide growth. The model predictions show a good agreement with the experimental results.
A novel copper damascene technique for power loaded SAW structures
Authors: Menzel S. B. , Albert M. , Reitz D. , Wendrock H. , Schmidt H. , Weihnacht M. , Wetzig K. , Bartha J. W. 
Published: April 2011

ABSTRACTThe damage of finger electrodes of surface acoustic wave (SAW) structures due to material transport (acoustomigration) forming voids and hillocks is strongly associated with the SAW stress field, the temperature and properties of the fingers material and their configuration. By application of Cu thin films a significant higher performance of SAW structures with respect to power durability, reliability and lifetime is obtained. In the present paper Cu finger electrodes of a special power SAW test structure were fabricated in trenches of STX quartz substrates using the copper damascene technique. In comparison with conventional finger electrodes located on the substrate surface, such an embedded structure enables some new features regarding their acoustical and acoustomigration behavior. So high power SAW load cannot cause fatal failures by shorts between adjacent fingers. This fact is specially important for SAW devices in the GHz range. The trench structuring into the substrate was carried out by reactive ion (RIE) or ion beam etching (IBE) technique using a metallic hard mask. Etched trenches were filled with a conductive Ta-Si-N / Cu-layer system by magnetron sputtering in a cluster tool, and structured by a chemical-mechanical polishing (CMP) process. Subsequently, after cleaning an insulating Ta-based barrier (system Ta-Si-O / Ta-Si-N) layer was deposited on the wafer surface. This covering layer also acts as a protective coating. Such a metallization system enables sufficient bonding properties using Al-wires. First results of electrical measurements show that travelling SAW could be excited in quartz substrates.
Epitaxial Aluminum Electrodes on Theta Rotated Y-X LiTaO3 Piezoelectric Substrate for High Power Durable SAW Duplexers.
Authors: Nakagawara Osamu , Suzuki Hironori , Yamato Shuji , Hasegawa Masayuki , Ieki Hideharu 
Published: April 2011

ABSTRACTHigh power durable electrodes have been successfully grown on 38.5° rotated Y-X LiTaO3 piezoelectric substrates featuring epitaxial Al films with a pseudo-homoepitaxial Ti intermediate layer. We found that a two-step process sequence in the deposition temperature of an intermediate layer could make it possible for an Al/Ti structure to grow epitaxially on low-cut-angle Y-X LiTaO3. Specified epitaxial relationship was Al(111)<011>//Ti(001)<100>//LiTaO3(001)<100>. Duplexers with epitaxial Al electrodes had a breakdown power above 6 W and more than ten times longer lifetime in contrast to filters with polycrystalline electrodes of which the breakdown power is 3.4 W. Epitaxial electrodes with extremely less grain boundary can improve power durability because self-diffusion of Al atoms occurs mainly in the grain boundary of the film. Material variation of epitaxial electrodes will be discussed as well.
Three Dimensional Integration with Benzocyclobutene as the Wafer-Bonding Medium
Authors: Kim Sang Kevin , Xue Lei , Tiwari Sandip 
Published: April 2011

ABSTRACTA successful wafer-scale device layering process for fabricating three-dimensional integrated circuits (3D ICs) using Benzocyclobutene (BCB) is described. In the reported embodiment of the method, a sub-micron thick “donor” device layer is transplanted onto a fully fabricated “host” wafer with BCB as the intervening medium. Experimental results, including RIE study and planarization of BCB processed through the 3D fabrication procedure are reported. We conclude with an approach to alleviate BCB and fabrication induced wafer bowing, which leads to poor wafer to wafer alignment in 3D integration.
Die-on-Wafer and Wafer-Level Three-Dimensional (3D) Integration of Heterogeneous IC Technologies for RF-Microwave-Millimeter Applications
Authors: Lu J.-Q. , Devarajan S. , Zeng A. Y. , Rose K. , Gutmann R. J. 
Published: April 2011

ABSTRACTDie-on-wafer and wafer-level three-dimensional (3D) integrations of heterogeneous IC technologies are briefly described, emphasizing a specific 3D hyper-integration platform using dielectric adhesive wafer bonding and Cu damascene inter-wafer interconnects to provide a perspective on wafer-level 3D technology processing. Wafer-level 3D partitioning of high Q passive components, analog-to-digital (A/D) converters, RF transceivers, digital processors, and memory is discussed for high-performance RF-microwave-millimeter applications, especially where high manufacturing quantities are anticipated. Design and simulation results of 3D heterogeneous integration are presented. This 3D technology is applicable to smart wireless terminals, millimeter phased array radars, and smart imagers.
Evaluation of Dielectric Permittivity of Barium Titanate Fine Powders
Authors: Tsurumi Takaaki , Sekine Takashi , Kakemoto Hirofumi , Hoshina Takuya , Nam Song-Min , Yasuno Hiroaki , Wada Satoshi 
Published: April 2011

ABSTRACTDielectric permittivity (εr) of BaTiO3(BTO) powders was determined by measuring εr of slurries prepared from BTO powder and propylene carbonate as dispersion medium, followed by analyzing with a finite element methods (FEM). The εr of powders depended on their characters such as tetragonality (c/a ratio), density, particle size and specific surface area. In order to extract the effect of each character, a statistical analysis was carried out to represent the εr of powders with an empirical formula, where the c/a ratio, density and particle size were used as parameters. A fairly good agreement between observed data and those expected from the formula was obtained and the contribution of each character to the εr could be determined.
New Garnet Films for Magneto-Optical Photonic Crystals
Authors: Khartsev S.I. , Grishin A.M. 
Published: April 2011

ABSTRACTEpitaxial La3Ga5O12 (LGG) garnet films and Bi3Fe5O12/La3Ga5O12 (BIG/LGG) heteroepitaxial structures have been synthesized on Gd3Ga5O12(GGG, 111) single crystal. LGG films were grown by Pulsed Laser Deposition (PLD) technique whereas rf-magnetron sputtering was used to grow BIG films. We demonstrate LGG is a promising material to be integrated with a giant Faraday rotator Bi3Fe5O12 in magneto-optical photonic crystals. LGG has a lattice constant 12.772 Å that is bigger than that in GGG (12.384 Å) and closer to that in BIG (12.626 Å). Heteroepitaxial Bi3Fe5O12(2μm)/La3Ga5O12(300nm) structures grown on the GGG(111) single crystal show the Faraday rotation as high as 5.74 deg/μm compared to 5.46 deg/μm in BIG/GGG at λ = 655 nm. Fitting LGG reflectivity spectra to Fresnel formulas yields LGG refractive index n = 1.981 compared to 1.963 in GGG at 655 nm. Dispersion of LGG refraction index follows Sellmeier formula n2 = 1 + 2.78/ [1 – (138nm/λ)2] in the range from 400 nm to 1000 nm.
Nonlinear magneto-optics in garnet magnetophotonic crystals
Authors: Aktsipetrov O.A. , Dolgova T.V. , Fedyanin A.A. , Kapra R.V. , Murzina T.V. , Inoue M. , Yoshida T. , Kobayashi D. , Nishimura K. , Uchida H. 
Published: April 2011

ABSTRACTIn this paper the results of our recent studies of the magnetization-induced nonlinear optical second-order and third-order effects in magnetophotonic crystals and magnetophotonic microcavities are surveyed.Nonlinear magneto-optical Kerr effect (NOMOKE) both in magnetization-induced second-harmonic generation (MSHG) and magnetization-induced third-harmonic generation (MTHG) is observed in garnet MMC at wavelengths of the resonant microcavity modes. Magnetization-induced variations of MSHG and MTHG intensity as well as magnetization-induced shift of phase and rotation of polarization of second-harmonic and third-harmonic waves are observed in proper - transversal, longitudinal or polar - NOMOKE configurations.Nonlinear magneto-optical Kerr effect in MSHG intensity is observed in garnet magnetophotonic crystals in the spectral range of photonic band gap (PBG) edges of MPC.The MSHG intensity reveals enhancement by a factor of more than 102 if the fundamental wavelength is tuned in the vicinity of the PBG edge. This enhancement is attributed to the fulfilment of the phase matching conditions for MSHG effect in layered structures with periodic modulation of both optical (magneto-optical) and nonlinear optical parameters.
High-Density Magneto-Optical Recording with DWDD and DTE
Authors: Miyakoshi Toshimori , Shiratori Tsutomu , Miyaoka Yasuyuki , Hozumi Yasushi 
Published: April 2011

ABSTRACTWe have developed a new light intensity modulation recording method called Domain Tail Erasing (DTE). This new recording method enables high-density recording far beyond the optical resolution limit with a medium combining the layer structure of Domain Wall Displacement Detection (DWDD) with that of Light Intensity Modulation Direct Overwrite (LIMDOW). Recording performance nearly identical to that with Magnetic Field Modulation (MFM) was confirmed with this method, using conventional optics with a wavelength of 660 nm and an NA of 0.60. However, the DTE method still requires a bias magnet, which remains a disadvantage in cases in which a thinner drive apparatus is required.We have therefore also made the bias magnets unnecessary by introducing a device to generate a magnetic field as a magnetic film included inside the medium.
Condenser-Transducer Configuration for Improving Radiation Efficiency of Near-Field Optical Transducers
Authors: Sendur Kursat , Peng Chubing , Challener William 
Published: April 2011

ABSTRACTNear-field radiation efficiency of the ridge waveguide transducer is investigated in the vicinity of a recording magnetic medium. Near-field radiation from a ridge waveguide transducer is expressed in terms of power density quantities. This allows us to quantify the near-field radiation efficiency from the near-field transducer with respect to the input optical power. Finite element method (FEM), which is capable of modeling focused beams, is used to simulate various geometries involving ridge waveguides. The incident electric field near the focal region is determined using a Gaussian beam expression and Richards-Wolf vector field equations for low NA and high NA beams, respectively. First, the ridge waveguide transducer is placed at the focal point of an optical lens system. The maximum value of the absorbed optical power in the recording medium is 1.6*10-4 mW/nm3 for a 100 mW input optical power. Finally, the ridge waveguide is placed adjacent to a solid immersion lens but separated by a low-index dielectric layer. For this case, the maximum value of the absorbed optical power in the recording medium is 7.5*10-4 mW/nm3 for a 100 mW input optical power. The improvement in the transmission efficiency is a result of two factors: 1. Increased incident electric field over the transducer surface due to increased NA of the optical system, 2. Surface plasmon enhancement obtained by placing a low-index dielectric material between the solid immersion lens and ridge waveguide.
The Dependence of the Magnetic Properties of GaMnN on Codoping by Mg and Si
Authors: Reed Mason J. , Oliver Luen M. , Reed Meredith L. , Bedair Salah M. , Arkun Fevzi Erdem , Berkman Erkan Acar , Elmasry Nadia A. , Zavada John 
Published: April 2011

ABSTRACTThe magnetic properties of GaMnN, grown by metalorganic chemical vapor deposition, depend on the addition of dopants; where undoped materials are ferromagnetic, and n -type (Si-doped) and p -type (Mg-doped) films are either ferromagnetic or paramagnetic depending on dopant concentration. The ferromagnetism of this material system seems correlated to Fermi level position, and is observed only when the Fermi level is within or close to the Mn energy band. This allows ferromagnetism-mediating carriers to be present in the Mn energy band. The current results exclude precipitates or clusters as the origin of room temperature ferromagnetism in GaMnN.
Neutron diffraction and electrochemical studies of LixNi1/3Mn1/3Co1/3O2
Authors: Yin Shih-Chieh , Rho Young-Ho , Swainson Ian , Nazar Linda F. 
Published: April 2011

ABSTRACTAmongst solid solutions of the Li-Ni-Mn-Co-O series, LiNi1/3Mn1/3Co1/3O2 has received much attention owing to its high capacity and thermal stability. A major issue in these ordered rock salt structures is the irreversibility on the first cycle, and degree of Li+/Ni2+ cation disorder which inhibits the rate capability. To examine these factors, different synthesis methods were employed which led to LiNi1/3Mn1/3Co1/3O2 that exhibited varying degrees of cation disorder. Neutron diffraction studies were carried out on samples (LixNi1/3Mn1/3Co1/3O2, x = 1.00 → 0.04) prepared by chemical oxidation. The studies reveal that the extent of Ni2+/Li+ disorder between the 3b and 3a sites was preserved on Li extraction and re-insertion. Complete extraction of lithium to form the O1 phase was achieved in some materials. However, reformation of the O3 phase on chemical relithiation does not occur in these cases, whereas materials that only partly convert to the Ol phase exhibit complete conversion back to the O3 phase on relithiation. The differences are attributed to lithium site occupancy/stoichiometry and crystallite size effects.
Fe/Mn-based Perovskite-Type Oxides with Excellent Oxygen Permeability and Reduction Tolerance
Authors: Teraoka Yasutake , Shimokawa Hironobu , Kusaba Hajime , Sasaki Kazunari 
Published: April 2011

ABSTRACTA family of Co-free, Fe/Mn-based perovskite-type oxides, (Sr, A')(Fe, Mn)O3-δ (A'=La, Ba, Ca), was synthesized, and their oxygen permeability and phase stability in reducing atmosphere were investigated. The substitution of Mn at B site caused the decrease in oxygen permeability. As for the effect of A-site substitution, prominent promotion was observed by the substitution of Ba for 30% of Sr, and Ba0.3Sr0.7FeO3-δ was found to be one of most excellent oxygen permeable materials with the permeation flux of 3.0 cm3(STP) cm−2 min−1 at 900 °C. Reduction tolerance was evaluated by TG measurements in a 5%H2/N2 stream up to 1000 °C. After the TG measurements, crystal structures of La-Sr-Co-Fe-O and Sr-Fe-(Mn)-O perovskites were decomposed or transformed into low oxygen permeable phases, but the perovskite-type structure of Ba-Sr-Fe-(Mn)-O survived. The Fe/Mn-based perovskites with high oxygen permeability and exceeding reduction tolerance could be used as stable membrane materials for membrane reactors catalyzing NO-CH4 reaction and the partial oxidation of CH4 into synthesis gas.
Metastable Phase Evolution in TiO2-YO3/2-ZrO2
Authors: Schaedler Tobias , Girma Solome , Gandhi Ashutosh S. , Sampath Sanjay , Levi Carlos G. 
Published: April 2011

ABSTRACTThe metastable-to-equilibrium phase evolution over a wide range of compositions in the TiO2-YO3/2-ZrO2 system was investigated. The competing phases are all derivatives of the fluorite structure and compositions within the fluorite and pyrochlore fields exhibit technologically interesting ionic and mixed ionic-electronic conductivity. Powders of various compositions were synthesized by precursor routes, pyrolyzed and subsequently heat-treated in a stepwise manner at progressively higher temperatures to explore the sequence of phase evolution. Extended solid solutions with amorphous, fluorite and ordered pyrochlore structures were produced over significant composition ranges within the ternary. The study also sheds new light on the correct form of the phase equilibria at 1300°C.
Development and characterization of thin-film perovskite membranes with oxygen permeability.
Authors: Muydinov R. , Popova M. , Kaul A. , Stiens D. , Wahl G. 
Published: April 2011

ABSTRACTTwo conceptions of oxygen selective membrane's development, ceramic and thin film ones were considered using perovskite Ba0.5Sr0.5Co0.8Fe0.2O3−δ(BSCF) with mixed oxygen ionic and electronic conductivity. The films of BSCF (2–3mkm thick) were deposited by a MOCVD technique on the porous substrates (YSZ, Al2O3). Gas tightness, selective oxygen flux at 750–950°C and stability of the asymmetric film membranes in working conditions were investigated in comparison with ceramic ones. Sufficiently gas tight films can be directly obtained only on the substrates with submicron pores and at Tdep< 600°C. New alternative approach of large-pore substrates modification for obtaining gas-tight oxygen selectively permeable membranes was developed. To avoid the chemical interaction between BSCF and YSZ or Al2O3the intermediate layer of BaO was pre-deposited. Resulting permeation through asymmetric membranes was thought to be dependent on oxygen exchange surface reaction and gas permeability of the porous supports.