bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication of Prototype Magnetic Coupled Spin-torque Devices for Non-volatile Logic Applications
Authors: Leem Larkhoon , Harris James S. , Rettner Charles , Hughes Brian , Jiang Xin , Yang See-hun , Parkin Stuart 
Published: August 2010

AbstractA Magnetic Coupled Spin-torque Device (MCSTD) is a collective system of three interacting magnetic tunnel junctions (MTJs) that forms a novel magnetic logic gate. The fundamental principle of the MCSTD is the modification of the energy barrier for spin-torque magnetization switching of a central (output) MTJ device arising from changes in the magnetic state of two input MTJ devices. The input MTJs are placed in close proximity of a few tens of nm of the output MTJ such that their magnetic fringing fields are strong enough (> 10 Oersted) to modulate the switching characteristics of the output device. By changing the magnetic states of the two input MTJs four possible net magnetic fields at the center MTJ can be generated. A single MCSTD thereby enables NAND, NOR and XOR operations. In this paper, the fabrication of a prototype MCSTD device is described and preliminary experiment results are reported.
Size-dependent Temperature Instability in NiO–based Resistive Switching Memory
Authors: Ielmini Daniele , Nardi Federico , Cagli Carlo , Lacaita Andrea L. 
Published: August 2010

AbstractResistive switching memory (RRAM) is attracting a strong interest as novel nonvolatile memories for high-density storage. Anyway this technology has to overcome two main issues before its use in real applications which are the high current needed for program operations and data retention stability. These two problems are here investigated from experimental and theoretical points of view to clarify the possibilities of NiO RRAMs to become a real competitive alternative to mainstream Flash technology.
CVD Growth and Passivation of W and TiN Nanocrystals for Non-volatile Memory Applications
Authors: Gay Guillaume , Belhachemi Djamel , Colonna Jean-Philippe , Minoret Stéphane , Beaurain Arnaud , Pelissier Bernard , Roure Marie-Christine , Lafond Dominique , Jalaguier Eric , Molas Gabriel , Baron Thierry , De Salvo Barbara 
Published: August 2010

AbstractIn this paper, we present CVD (Chemical Vapor Deposition) growth and passivation of tungsten (W) and titanium nitride (TiN) nanocrystals (NCs) on silicon dioxide and silicon nitride for use as charge trapping layer in floating gate memory devices. NCs are deposited in an 8 inches industrial CVD Centura tool. W and TiN are chosen for being compatible with MOSFET memory fabrication process. For protecting NCs from oxidation, a silicon shell is selectively deposited on them. Moreover, for a better passivation, TiN NCs are encapsulated in silicon nitride (Si3N4) in order to get rid of oxidation issues. After high temperature annealing (1050°C under N2 during 1 minute) XPS measurements point out that NCs are still metallic, which makes them good candidates for being used as charge trapping layer in floating gate memories.
Low Temperature Growth of Silicon Structures for Application in Flash Memory Devices
Authors: Mih Thomas Attia , Paul Shashi , Cross Richard BM 
Published: August 2010

AbstractAn in-depth study of the structural and electrical properties of silicon (Si) films deposited by a novel low temperature technique at temperatures less than 400°C in a 13.56 MHz RF PECVD reactor is reported. The method is based on substrates having to undergo some initial preparatory steps (IPS) before the deposition of Si films in the PECVD chamber. The optical band gap of Si films deposited using this novel technique narrowed to 1.25 eV from 1.78 eV using the traditional a-Si:H deposition recipe. No annealing of any form was performed on the films to attain this band gap. Furthermore, photosensitivities for these films under various deposition conditions were of order 100 compared to 104 for a-Si:H films deposited under like conditions. Using metal-insulator-semiconductor devices, the Si films grown by this novel technique exhibit charge storage and memory behaviour unlike their amorphous counterparts. However, device endurance has been found to be inadequate, probably due to the presence of some contaminants - notably interstitial oxygen - which has been found elsewhere to have adverse effects on the electrical characteristics of Si films. If well harnessed, we suggest Si structures grown by this novel growth technique could be well-suited for flash memory applications, particularly 3-D flash which requires process temperatures to be less than 400 °C.
Fabrication of IGZO and In2O3-channel Ferroelectric-gate Thin Film Transistors
Authors: Oiwa tomohiro , Tokumitsu Eisuke 
Published: August 2010

AbstractWe have fabricated and characterized ferroelectric-gate TFTs using In-Ga-Zn-O (IGZO) or In2O3 as a channel material. The ferroelectric gate insulator used in this work is (Bi,La)4Ti3O12 (BLT). We observed normal n-channel transistor operation for both IGZO and In2O3-channel TFTs. However, a charge injection type hysteresis was observed for IGZO channel TFTs in drain current – gate voltage (ID-VG) characteristics. Post fabrication anneal at 300oC reduced the charge-injection-tyoe hystereesis and the subthreshold swing was also improved from 0.27 to 0.19 V/decade. On the other hand, when the In2O3 was used as a channel, hysteresis due to the ferroelectric gate insulator was clearly observed in ID-VG characteristics. A memory window of 2V, a subthreshold voltage swing of 0.35V/decade, a field-effect mobility of 1.6 cm2/Vs, and a on/off drain current ratio of more than 10^6 were obtained.
Phase Change Memory with Chalcogenide Selector (PCMS): Characteristic Behaviors, Physical Models and Key Material Properties
Authors: Karpov Ilya V. , Kencke David , Kau Derchang , Tang Stephen , Spadini Gianpalo 
Published: August 2010

AbstractWe present a novel scalable and stackable nonvolatile solid state memory. Each cell consists of a storage element, based on phase change memory (PCM) element, and an integrated selector, using an Ovonic threshold switch (OTS). The cell is implemented to enable a true cross-point array. The main device characteristics and behaviors, corresponding physical processes in different operation modes, and key material properties are discussed.
Memory retention of doped SbTe phase change line cells measured isothermally and isochronally
Authors: Oosthoek Jasper L.M. , Kooi Bart J. , Attenborough Karen , Hurkx Fred A.M. , Gravesteijn Dirk J. 
Published: August 2010

AbstractDoped SbTe phase change (PRAM) line cells produced by e-beam lithography were cycled for at least 100 million times. The memory retention of the PRAM cell was measured both isothermally and isochronally which showed excellent agreement. An activation energy for growth of 1.7 eV was found (after 100 million cycles) for both measurements. Similar isothermal and isochronal measurements were performed on PRAM cells produced by optical lithography which yielded activation energies of 3.0 eV and 3.3 eV, respectively. Our results show that the same phase-change material can show large differences in retention behavior depending on the way the cells are produced.
Charge Transport in Nanoglasses of Phase-Change Memory
Authors: Simon Mark Alexander , Nardone Marco , Kostylev sergey , Karpov Ilya V. , Karpov Victor G. 
Published: August 2010

AbstractWe discuss possible mechanisms for Poole-Frenkel type of non-ohmic conduction in chalcogenide glasses in the range of room temperatures. Overall, we list 8 such mechanisms, only one of which (Schottky emission) can be ruled out as inconsistent with the observations. Seven others can give more or less satisfactory fits of the observed non-linear IV curves. Our analysis calls upon indicative facts that would enable one to discriminate between the various alternative models.
Amorphization of Crystalline Phase Change Material by Ion Implantation
Authors: Raoux Simone , Cohen Guy , Shelby Robert M. , Cheng Huai-Yu , Jordan-Sweet Jean L 
Published: August 2010

AbstractGermanium ion implantation at an energy of 30 keV was used as a different method to re-amorphize thin films of crystalline phase change material Ge2Sb2Te5 (GST). It was found that rather low doses of 5×1013 cm-2 were sufficient to re-amorphize GST. Amorphization was determined by X-ray diffraction (XRD) as well as reflectivity measurements. Re-crystallization characteristics of ion-implantation-amorphized samples was studied using time-resolved XRD. It showed that samples re-crystallize at an increased crystallization temperature with increasing dose compared to as-deposited material. A static laser tester was applied to measure the crystallization times of material that was (1) as–deposited amorphous; (2) crystallized by annealing and re-amorphized by melt-quenching using a laser pulse; and (3) crystallized by annealing and re-amorphized by ion implantation. It was found that as-deposited amorphous and high-dose ion implanted samples had longer crystallization times while melt-quenched amorphous and low-dose ion implanted samples had shorter crystallization times.
Local Order and Crystallization of Laser Quenched and Ion Implanted Amorphous Ge1-xTex Thin Films
Authors: Carria Egidio , De Bastiani Riccardo , Gibilisco Santo , Mio Antonio Massimiliano , Miritello Maria , Pennisi Agata Roberta , Bongiorno Corrado , Grimaldi MariaGrazia , Rimini Emanuele 
Published: August 2010

AbstractAmorphous films of Ge1-xTex (x=0.37, 0.51, 0.64) prepared by sputtering, by melt quenching or by ion irradiation were annealed up to 450°C. Different phase stability, i.e. crystallization temperature, was observed varying the amorphous status in stoichiometric and Te-rich alloys while no variation was obtained in the Ge-rich alloy. Laser and ion irradiated stoichiometric alloy exhibits lower stability with respect to the sputtered film while irradiated amorphous Te-rich samples are more stable than the as deposited amorphous sample. An enhancement of edge-sharing GeTe4 tetrahedra Raman signal at the expenses of Ge-rich tetrahedra signal occurs in the irradiated samples with respect to the as-deposited amorphous layers both in the stoichiometric and in the Te-rich alloy. The crystallization temperature decreases in GeTe since the system during irradiation is promoted to a state closer to the crystalline phase while in Te-rich alloy the stability increases with the density of Ge-Te bonds since this local rearrangement delays Te precipitation and the subsequent GeTe crystallization. Irradiation does not affect the stability of Ge rich alloy in which crystallization is limited by the Ge mobility and the induced local rearrangements is probably prevented by the low atomic diffusivity.
Influence of Bottom Contact Material on the Selective Chemical Vapor Deposition of Crystalline GeSbTe Alloys
Authors: Schrott Alejandro , Chen Chieh-Fang , Breitwisch Matthew J. , Joseph Eric A. , Dasaka Ravi K , Cheek Roger W. , Zhu Yu , Lam Chung H 
Published: August 2010

AbstractSelective Chemical Vapor Deposition of Crystalline Ge-Sb-Te alloys initiating at the bottom metal contact of vias of various sizes has been accomplished. The method is based on selecting Sb and Te precursors which do not decompose on dielectric surfaces in the utilized temperature range.
Investigation of the Thermal Stability of Strained Ge Layers Grown at Low Temperature by Reduced-pressure Chemical Vapour Deposition on Si0.2Ge0.8 Relaxed Buffers
Authors: Dobbie Andy , Myronov Maksym , Liu Xue-Chao , Nguyen Van Huy , Parker Evan , Leadley David 
Published: August 2010

AbstractHigh quality strained Ge (s-Ge) epitaxial layers are a promising candidate to achieve high mobility channel MOSFETs suitable for the 22 nm technology node and beyond, due to the intrinsically higher mobility of Ge compared to Si, and the additional performance enhancements from strain [1]. In order to achieve an s-Ge channel more than a few monolayers thick it is necessary to engineer a relaxed Si1-xGex buffer with a high Ge content (x > 0.5). We have recently reported high quality s-Ge layers grown by RP-CVD at low temperature (T ≤ 450 °C), on a fully relaxed Si0.2Ge0.8 buffer [2]. By using a reverse-grading approach, we achieved a high Ge composition in the buffer, with a smooth surface (rms surface roughness of ~2 nm), low threading dislocations density (~ 4 x 106 cm-2) and much thinner (~ 2.1 μm) than can be achieved with conventional linear grading [3].In this work, the thermal stability of s-Ge epilayers (up to 80 nm thick) grown on relaxed Si0.2Ge0.8 buffers has been investigated by in-situ annealing in H2 ambient at temperatures up to 650 °C. These temperatures are similar to those currently used during fabrication of advanced CMOS devices. All s-Ge layers were grown at 400 °C using GeH4 gaseous precursor. The relaxation of the annealed layers has been studied using high-resolution XRD reciprocal space maps (RSMs), and was found to depend strongly on both annealing temperature and thickness of the Ge epilayer. Strained Ge layers up to 50 nm thick remained fully strained after annealing at 450 °C, whereas after annealing at 550 °C s-Ge layers thicker than 20 nm were on the onset of relaxation; after annealing at 650 °C all s-Ge layers showed significant relaxation with defects clearly visible at the Si0.2Ge0.8/Ge interface. All annealed s-Ge layers exhibited higher surface roughness than s-Ge control samples without annealing (rms ~ 2 nm). Annealing at 450 °C resulted in only a slight increase in surface roughness (rms ~ 3 nm), almost independent of s-Ge thickness. However, annealing at 550 °C and 650 °C resulted in significant surface roughening (with maximum rms values of 5 nm and 35 nm, respectively) due to the formation of Ge islands, which were observed by AFM. At these higher temperatures, the surface roughness of the s-Ge layers was found to be thickness dependent, with a Ge smoothing effect observed for layers greater than 50 nm.These results are particularly important for the fabrication of s-Ge MOSFETs, for which the surface passivation prior to gate stack formation is critical to the performance of the device. Based on the results presented here, the thermal budget should be kept below 550 °C to avoid relaxation and roughening of the s-Ge epilayer, which could degrade the device performance.
Novel Solid Nanohybrids that Stabilize Oil/Water Emulsions and Catalyze Reactions at the Interface
Authors: Faria Jimmy Alexander , Shen Min , Resasco Daniel E 
Published: August 2010

AbstractA novel system has been developed to catalyze reactions at the oil/water interface of a biphasic liquid system. Stabilization of emulsions was accomplished through the use of nanohybrids composed of hydrophilic oxide particles and hydrophobic Single-Walled Carbon Nanotubes (SWNT), generated in the CoMoCAT process. These nanohybrids are inherently amphiphilic, and tend to adsorb at the interface of a biphasic water/oil liquid system. When enough energy is added to the system, these particles stabilize emulsions by suppressing the coalescence of the droplets and increasing the viscoelastic or pseudoplastic character of the liquid film between droplets. , Depending on contact angle of the particles at the liquid-liquid interface it was possible to stabilize water-in-oil or oil-in-water emulsions. The resulting emulsions are remarkably stable against coalescence and sedimentation, and can be easily separated by filtration or centrifugation, which make them suitable for applications in interfacial catalytic processes in which the catalyst can be easily recovered after reaction. Catalytic activity was imparted by transition metal clusters supported onto the nanohybrids. These metals selectively catalyze reactions at the Oil/Water interface. The proof-of-concept of the biphasic hydrogenation and condensation catalysis was obtained with three reactions of interest in biorefining. The first example was the hydrodeoxygenation of vanillin (4-hydroxy-3-methoxybenzaldehyde). The second example was the conversion of molecules that were exclusively soluble in the aqueous or the organic phase, like glutaraldehyde (water phase) and octanal (oil phase). In the third example we explored a tandem reaction sequence in which Pd-catalyzed hydrogenation was paired with a preceding Aldol-condensation of 5- methylfurfural and acetone. It was demonstrated that with these nanohybrids it is possible to selectively accomplish hydrodeoxygenation and condensation reactions at the water/oil interface of a biphasic system, followed by migration of the products to the oil phase. This contribution provides a proof-of-concept for a promising catalytic system with many potential applications in the liquid phase, such as bio-oil upgrading, production of specialty chemicals, and pharmaceutical applications in which selective reaction and product separations, based on water solubility can be desirable.
Structural and magnetic properties of pure and cobalt doped Gallium Nitride nanocrystals
Authors: Ganesh Vottikondala , Sundaram Suresh , Baskar Krishnan 
Published: August 2010

AbstractIn the present study pure and doped gallium nitride (GaN) nanocrystals were synthesized using gallium trichloride (GaCl3), ethylene diamine tetra acetic acid (EDTA) and cobalt chloride as raw materials at a temperature of 900 °C in ammonia (NH3) atmosphere. The XRD spectrum for pure and cobalt doped GaN nanocrystals shows the formation of single phase wurtzite structure. No impurity phases were observed in the X-ray diffraction pattern for 5% Co doped sample whereas secondary phases were observed when the doping concentration exceeds 5 %. Shift in X-ray diffraction peaks were observed in Co doped samples towards lower angle side compared to pure GaN, it confirms that the Co atoms introduces in to the GaN lattice. Transmission electron microscopy images were taken for pure and Co doped GaN. Hexagonal morphology was observed in pure GaN samples. The average size of the particle was found to be ˜20 nm for pure and Co doped GaN. The magnetic measurements were carried out for the Co (5% & 10%) doped samples both at 10K and 300K. Clear hysteresis loop in the magnetization curve suggest the presence of ferromagnetic behavior in cobalt doped GaN. Temperature dependent magnetization (M-T) measurements were also carried out for doped samples using Super Conducting Quantum Interface Device (SQUID) from 10K to 300K The results have been discussed and correlated to structural and magnetic properties of the materials.
Polymeric/Inorganic Multifunctional Nanoparticles for Simultaneous Drug Delivery and Visualization
Authors: Fornara Andrea , Recalenda Alberto , Qin Jian , Sugunan Abhilash , Ye Fei , Laurent Sophie , Muller Robert N , Zou Jing , Usama Abo-Ramadan , Toprak Muhammet S , Muhammed Mamoun 
Published: August 2010

AbstractNanoparticles consisting of different biocompatible materials are attracting a lot of interest in the biomedical area as useful tools for drug delivery, photo-therapy and contrast enhancement agents in MRI, fluorescence and confocal microscopy. This work mainly focuses on the synthesis of polymeric/inorganic multifunctional nanoparticles (PIMN) based on biocompatible di-block copolymer poly(L,L-lactide-co-ethylene glycol) (PLLA-PEG) via an emulsion-evaporation method. Besides containing a hydrophobic drug (Indomethacin), these polymeric nanoparticles incorporate different visualization agents such as superparamagnetic iron oxide nanoparticles (SPION) and fluorescent Quantum Dots (QDs) that are used as contrast agents for Magnetic Resonance Imaging (MRI) and fluorescence microscopy together. Gold Nanorods are also incorporated in such nanostructures to allow simultaneous visualization and photodynamic therapy. MRI studies are performed with different loading of SPION into PIMN, showing an enhancement in T2 contrast superior to commercial contrast agents. Core-shell QDs absorption and emission spectra are recorded before and after their loading into PIMN. With these polymeric/inorganic multifunctional nanoparticles, both MRI visualization and confocal fluorescence microscopy studies can be performed. Gold nanorods are also synthesized and incorporated into PIMN without changing their longitudinal absorption peak usable for lased excitation and phototherapy. In-vitro cytotoxicity studies have also been performed to confirm the low cytotoxicity of PIMN for further in-vivo studies.
Facile Alignment of Carbon Nanotubes Mediated by Tethered Maghemite Nanoparticles
Authors: Kim Il Tae , Nunnery Grady A , Jacob Karl I , Schwartz Justin , Liu Xiaotao , Tannenbaum Rina 
Published: August 2010

AbstractWe describe a novel, facile method for the alignment of multi-walled carbon nanotubes (MWNTs) in a magnetic field facilitated by the decoration of the MWNTs with monodisperse γ-Fe2O3 magnetic (maghemite) nanoparticles. The tethering of the nanoparticles was achieved by the attachment of γ-Fe2O3 nanoparticles that were synthesized using a modified sol-gel process, onto the carboxylate-activated MWNTs. Sodium dodecylbenzene sulfonate (NaDDBS) was used to prevent the formation of an iron oxide 3D network. Various characterization methods were employed to confirm the formation of homogeneously-distributed and nearly-monodispersed iron oxide nanoparticles, and show that they were indeed tethered to the walls of the MWNTs. The γ-Fe2O3 nanoparticles imparted magnetic characteristics to the MWNTs, which in turn, were oriented parallel to the direction of an externally-applied magnetic field. This facile alignment of MWNT could promote the enhancement of various properties, e.g. mechanical and electrical properties, of the resulting composites. Moreover, this facile alignment at low magnetic fields, made possible by the magnetization of the carbon nanotubes through the tethering of maghemite nanoparticles, may be applied to a variety of other useful nanofillers, such a glass fibers, clay nanoparticles and cellulose nanowhiskers.
Carbon Nanomaterials in Silica Aerogel Matrices
Authors: Hamilton Christopher E. , Chavez Manuel E , Duque Juan G. , Gupta Gautam , Doorn Stephen , Dattelbaum Andrew M. , DeFriend Obrey Kimberly A. 
Published: August 2010

AbstractSilica aerogels are ultra low-density, high surface area materials that are extremely good thermal insulators and have numerous technical applications. However, their mechanical properties are not ideal, as they are brittle and prone to shattering. Conversely, single-walled carbon nanotubes (SWNTs) and graphene-based materials, such as graphene oxide, have extremely high tensile strength and possess novel electronic properties. By introducing SWNTs or graphene-based materials into aerogel matrices, it is possible to produce composites with the desirable properties of both constituents. We have successfully dispersed SWNTs and graphene-based materials into silica gels. Subsequent supercritical drying results in monolithic low-density composites having improved mechanical properties. These nanocomposite aerogels have great potential for use in a wide range of applications.
Strength and Electrical Conductivity of Carbon Nanotube Yarns
Authors: Schauer Mark W , Lashmore David , Lewis Diana , Lewis Benjamin M. , Towle Erick C. 
Published: August 2010

AbstractThe strength and electrical conductivity of Carbon Nanotube (CNT) yarns is dramatically affected by the handling of the material after the nanotubes are produced. Our nanotube production process involving Chemical Vapor Deposition (CVD) using the floating catalyst method produces a mass of entangled bundles of single-walled nanotubes in a gas suspension. Simply collecting and spinning this material produces a yarn with strength and electrical conductivity far less than the properties of the individual nanotubes due to the poor alignment of the bundles on the microscopic scale. We have developed methods of aligning the CNT material that are analogous to the techniques used in the textile industry for spinning staple yarns, but modified to be appropriate for nano-scale material. The result is a dramatic improvement in strength and electrical conductivity of our CNT yarns.