bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation on the Work Function of Tungsten and Thermal stability of W/SiO2/Si, W/SiON/Si and W/HfO2/Si Gate Stacks
Authors: Jiang Pei-Chuen , Chen Jen-Sue , Cheng K. H. , Hu T. J. , Huang K. B. , Lee F. S. 
Published: April 2011

AbstractReplacement of poly-Si and SiO2with new gate electrode and high k gate oxide is an inevitable trend for next-generation CMOS integrated circuits. Therefore, work function (£Xm) of gate electrodes as well as the thermal stability and electrical behaviors of MOS capacitors should be understood. In this study, tungsten (W) is applied as the gate electrode and the gate dielectric materials are SiO2, SiON and HfO2. £Xm of W and electrical properties of the MOS structures are investigated. £Xm,measuredof W is calculated from the flat-band voltage (VFB) of MOS capacitors with dielectrics of various thicknesse. For W/SiO2/Si structure, the £Xm,measuredof W is 4.67 V; however, the £Xm,measuredof W in W/SiON/Si and W/HfO2/Si structures is 4.60 V and 4.84 V, respectively. The result means that the £Xm,measuredof W in W/HfO2/Si structures has extrinsic contributions to Fermi level pinning. The phase of as-deposited W is £]-W (or £]-W+£\-W) phase and transfers to £\-W+WO3 mix phase after annealing at 500°C in N2+H2 ambient for 30 min. The trapped charges and oxide charges of dielectric are reduced after annealing. However, the EOT of W/SiO2/Si increases significantly after annealing, indicating the thermal stability of this capacitor is poor.
Electrical and Material Evaluation of the MOCVD TiN as Metal Gate Electrode for Advanced CMOS Technology
Authors: Singanamalla Raghunath , Lisoni Judit , Ferain Isabelle , Richard Olivier , Carbonell Laure , Schram Tom , Yu HongYu , Kubicek Stefan , de Gendt Stefan , Jurczak Malgorzata , de Meyer Kristin 
Published: April 2011

AbstractThe electrical and material characterization of Ti(C)N deposited by metal organic chemical vapor deposition (MOCVD) technique, as metal gate electrode for advanced CMOS technology is investigated. The effects of the plasma treatment, post anneal treatment and the thickness variation of the Ti(C)N film on the flat band voltage (VFB) and effective work function (WF) of the Poly-Si/Ti(C)N/SiO2 Poly-Si/Ti(C)N/SiO2 gate stack s are reported. We found that both the in-situ plasma treatment and post anneal treatment help in reducing the carbon content (organic) in the film making it more metallic compared to the as-deposited films. However, the post anneal treatment was found to be a better option for getting rid of hydrocarbons as compared to plasma treatment from the gate dielectric integrity point of view. The thickness variation of post annealed Ti(C)N film ranged from 2.5 nm to 10 nm lead to WF shift of upto ~350 mV for both Poly-Si/Ti(C)N/SiO2 and Poly-Si/Ti(C)N/HfO2 gate stacks.
Electronic and Atomic Structure of Ge2Sb2Te5 phase change memory material
Authors: Robertson John , Xiong Ka , Peacock Paul 
Published: April 2011

AbstractElectronic structure calculations are presented for various model structures of the crystalline and amorphous phases of Ge2Sb2Te5 (GST). The structures are all found to possess a band gap of order 0.5 eV, indicating closed shell behaviour. It is pointed out that structural vacancies in A7-like GST are not electronically active. In addition, A7-like structures do not support valence alternation pair (VAP) defects, which are one model of the conduction processes in the glassy phase in non-volatile memories.
Photo-oxidation and the Absence of Photodarkening in Ge2Sb2Te5 Phase Change Material
Authors: Lee Bong-Sub , Xiao Ying , Bishop Stephen G. , Abelson John R. , Raoux Simone , Deline Vaughn R. , Kwon Min-Ho , Kim Ki-Bum , Cheong Byung-ki , Li Heng , Taylor P. Craig 
Published: April 2011

AbstractGe2Sb2Te5 is under intense investigation for phase-change memory devices, including rewriteable DVDs where optical illumination is used to switch between the glassy and crystalline states. We investigate the influence of optical irradiation on amorphous phase. Many chalcogenides display photo-oxidation, photodarkening or photo-bleaching, but little has been reported on the Ge-Sb-Te system. Using spectroscopic ellipsometry (SE) and secondary ion mass spectrometry, we determine that the samples have a strong tendency to photo-oxidize; if this is not accounted for, then the analysis of SE data appears to show photodarkening. Other authors recently reported photodarkening in nonstoichiometric GexSb20-xTe80 [Pamukchieva et al., Proc. SPIE 5581, 608 (2004); Pamukchieva et al., J. Optoelectron. Adv. Mater 7, 1277 (2005)], but our analysis suggests that the changes were also the result of photo-oxidation. The oxide has lower value of (n, k) than Ge2Sb2Te5, and can be etched by hydrofluoric acid or water. The photo-oxidation is presumably the result of free carrier generation in the Ge2Sb2Te5. Our observation of negligible photodarkening is consistent with previous works that found less photodarkening in tellurides compared with selenides or sulfides, and that an increase in the mean coordination number, here by Ge addition, further reduces the photodarkening effect.
Photo-induced Metastable State of S8Clusters in Liquid Sulfur
Authors: Sakaguchi Yoshifumi , Tamura Kozaburo 
Published: April 2011

AbstractIt is well known that liquid sulfur undergoes a polymerization transition from S8 rings to the mixture of S8 rings and polymeric chains at Tp=159°C. In addition to the transition, it has been known that there is a transformation from S8ring to a molecular species other than S8ring and polymeric chain below Tpsince 19thcentury. Such molecular species can also be obtained by the illumination of light. Several models of the molecular form have been presented. However, the conclusive model which explains all experimental results has not been settled yet. Recently we measured transient photo-induced optical absorption in liquid sulfur and Munejiri et al. performed first-principles molecular-dynamics simulations to clarify the microscopic origin of the experimental results. The results of the simulations presented a plausible molecular form as the molecular species, which is a tadpole-shaped S8 cluster. We show that the molecular form clearly explains the previous experimental results. A possibility of the formation of an intimate valence alternation pair in the small cluster is also discussed.
Investigation on Ultra-high Density and High Speed Non-volatile Phase Change Random Access Memory (PCRAM) by Material Engineering
Authors: Yeo E.G. , Shi L.P , Zhao R , Chong T.C. 
Published: April 2011

AbstractIn this paper, ultra-high memory density and high speed non-volatile phase change random access memory (PCRAM) was investigated by material engineering. The melting point, crystallization point and activation energy of crystallization of the Bismuth (Bi) doped Germanium-Antimony-Tellurium (GeSbTe) compound was measured using differential scanning calorimetry (DSC) and compared to other GeSbTe ternary compounds. It was observed that the melting temperature of Bi-doped GeSbTe was lower than that of GeSbTe. On the other hand, its activation barrier was found to be reduced, which in turn increased the speed of crystallization of Bi-doped GeSbTe. Bi-doped GeSbTe was then used as a phase change material in the fabrication of PCRAM devices. The properties of PCRAM fabricated using this material were then compared to those using GeSbTe, with emphasis on the programming current required. The results obtained revealed that lower programming current of up to 40% has been achieved for PCRAM with Bi-doped GeSbTe compared to those with other GeSbTe compounds. Bi-doped GeSbTe also has low RESET current and fast speed of crystallization with scaling, making it a suitable material for high speed, ultra-high density PCRAM fabrication in the future.
Laser Synthesis of Sn-Ge-Sb-Te Phase Change Materials
Authors: Song Wendong , Shi L.P. , Miao X.S. , Chong T.C. 
Published: April 2011

AbstractSn-doped Ge-Sb-Te films on Si substrates were prepared by laser synthesis at the different growth temperatures. The compositions of Sn-doped Ge-Sb-Te films were analysized by X-ray photoelectron spectroscopy. The crystal structures of Sn-doped Ge-Sb-Te thin films with a Sn content of less than 30 at% are close to Ge2Sb2Te5. The crystallization behaviors of Sn-doped Ge-Sb-Te films were analyzed by self-developed phase change temperature tester. The crystallization temperatures of Sn4.3Ge32.9Sb28.1Te34.6, Sn9.8Ge20.3Sb28.4Te41.5 and Sn18.8Ge19.5Sb25.3Te36.4 are 141.5, 137.3 and 135.0 °C at a ramp rate of 20 °C/min, respectively. Doping Sn into Ge-Sb-Te will result in a decrease of crystallization temperature. It was also found that crystallization temperature increases with an increase of ramp rate for a phase change material. The activity energy Ea and frequency factor ¦Ô for Sn9.8Ge20.3Sb28.4Te41.5 thin films are 2.42 eV and 1.7 × 1026 Hz, respectively. The crystallization speed of Sn-doped Ge-Sb-Te is estimated to be faster than Ge2Sb2Te5.
Realization of 3D Isotropic Negative Index Materials using Massively Parallel and Manufacturable Microfabrication and Micromachining Technology
Authors: VJ Logeeswaran , Islam M. Saif , Chan Mei Lin , Horsley David A , Wu Wei , Wang Shih-Yuan , Stanley Williams R. 
Published: April 2011

AbstractIn this paper, we present a method to realize a three dimensional (3D) homogeneous and isotropic negative index materials (3D-NIMs) fabricated using a low cost and massively parallel manufacturable microfabrication and microassembly technique. The construction of self-assembled 3D-NIM array was realized through two dimensional (2-D) planar microfabrication techniques exploiting the as-deposited residual stress imbalance between a bi-layer consisting of e-beam evaporated metal (650nm of chromium) and a structural layer of 500nm of low stress silicon nitride deposited by LPCVD on a silicon substrate.A periodic continuation of a single rectangular unit cell consisting of split-ring resonators (SRR) and wires were fabricated to generate a 3D assembly by orienting them along all three Cartesian axes. The thin chromium and silicon nitride bi-layer is formed as hinges. The strain mismatch between the two layers curls the structural layer (flap) containing the SRR upwards. The self-assembled out-of-plane angular position depends on the thickness and material composing the bi-layer. This built-in stress-actuated assembly method is suitable for applications requiring a thin dielectric layer for the SRR. The split-ring resonators and other structures are created on the membrane which is then assembled into the 3-D configuration.
Wireless-based Monitoring of Body Movements Using Wearable Sensors
Authors: Brady Sarah , Coyle Shirley , Wu Yanzhe , Wallace Gordon , Diamond Dermot 
Published: April 2011

AbstractThe world is becoming more health conscious and as a result healthcare is evolving in many ways. Wearable computing is assisting with this evolution, finding its place in many biomedical applications where real-time monitoring of general health indicators is required. However, the inconvenience of connecting sensors through wires, which not only incurs high maintenance, limits the freedom of the person therefore hampering a true reflection of the person's actions. By using sensors attached to wireless sensor nodes, this constraint is removed. Also in order to be “wearable” the sensors must be comfortable, a factor often overlooked by traditional sensors, where functionality and robustness are of higher importance. This work is focused on the use of foam-based pressure sensors and similar textile-based sensors for monitoring the ambulatory movements of the wearer. Characterization of the molecular nature of the materials and their environment are presented. We find these sensors to be successful in detecting the movement events without imposing on the daily activity of the wearer.
Prediction of Fiber Die Coating Thickness
Authors: Yang An , Tao XiaoMing , Chen XiaoYin 
Published: April 2011

AbstractFiber coating is an effective way to impart smartness to a fiber. Die coating is a process that utilizes a die to control the thickness and concentricity of the coating layer. In the present work the die coating mechanism is studied numerically. A mathematical model for the fiber coating thickness has been developed. Compared with the previous work, the proposed model considers the effect of gravity force to get the general solution. The shear rate acting on the fiber surface is proportional to the fiber draw speed in an unpressurized applicator and can be minimized in a pressurized applicator through the applied external pressure. A serials of experiments using open-cup and pressurized applicators have been designed and conducted to measure simultaneously the coating speed and coating thickness in the coating process. It was found that the gravity may be an important driving force for the coating flow when the drawing velocity is small and the viscous force decreases, but may be relatively insignificant for high speed coating process. The calculated results were compared with the experimental data and a good agreement was obtained.
Self-cleaning Cotton Fabrics
Authors: Qi Kaihong , Daoud Walid A , Xin John , Mak C.L. 
Published: April 2011

AbstractNanocrystalline anatase titanium dioxide films were successfully produced on cotton fabrics from alkoxide solutions under ambient pressure using the low temperature sol-gel process. At a temperature as low as 40°C, only anatase phase formed from X-ray diffraction spectroscopy (XRD). Field scanning electron microscopy (FESEM) images show the formation of uniform continuous films of titanium dioxide on cotton fabrics. The self-cleaning properties of these fabrics were evaluated by measuring anti-bacterial activities and the decomposition of a colorant Neolan Blue 2G. The results indicated that anatase treated cotton fabrics exhibited good self-cleaning performance.
Synthesis and Electrochemical Properties of InVO4 Nanotube Arrays
Authors: Wang Ying , Cao Guozhong 
Published: April 2011

AbstractA capillary-enforced template-based method is described for the preparation of InVO4 nanotube arrays. Nanotube arrays of InVO4 were prepared by filling the InVO4 sol into pores of polycarbonate membranes and pyrolyzing through sintering. Another type of InVO4 nanotube arrays (InVO4/acac) are obtained from the sol with the addition of acetylene acetone (acac). For comparison purposes, InVO4 films were prepared by drop casting from InVO4 same sol. Films and the two types of nanotube arrays of InVO4 annealed at 500°C consist of mixed monoclinic (InVO4-I) and orthorhombic (InVO4-III) phases. Scanning electron microscopy (SEM) characterizations indicate that the nanotubes are well-aligned, perpendicular to substrate surface with the outer diameter of ~200 nm for short InVO4 nanotubes and ~170 nm for long InVO4 nanotubes. Chronopotentiometry results reveal that InVO4/acac nanotube array has the highest charge capacity (790 mAh/g), followed by InVO4 nanotube array (600 mAh/g) then InVO4 film (290 mAh/g). Such enhanced lithium-ion intercalation properties are ascribed to the large surface area and short diffusion distance offered by nanostructures and amorphisation caused by acetylene acetone in the case of InVO4/acac nanotube arrays.
Nanotubes in Low Temperature Spray Deposited Nanocrystalline HgSe: I thin films
Authors: Arnepalli Ranga Rao , Dutta Viresh 
Published: April 2011

AbstractHgSe nanotubes have been prepared by spray deposition of solvothermally synthesized HgSe: Iodine nanoparticles on glass substrates at low temperature (200°C). Spray deposition was done without voltage and with an externally applied voltage (700V) to the nozzle and it is found from TEM studies that the average length of the nanotubes increases in case of the films deposited with applied voltage compared to that of without voltage. But there is no change in the average diameter (~ 35 nm). The nanotubes are found to have cubic crystal structure. Iodine is found to act as a catalyst and helps in the growth of nanotubes. The growth mechanism of the nanotubes is analogous to the well known solution-liquid-solid/vapor-liquid-solid (SLS/VLS) mechanism. The EDAX analysis of the tip of the nanotube reveals the presence of Hg, Se and Iodine in the ratio of 73:2:24 for the spot size of <1μm.
Tailoring of Carbon Nanotube Microstructure Using Poly(acrylic acid) and Poly(allylamine hydrochloride)
Authors: Liu Lei , Grunlan Jaime C. 
Published: April 2011

AbstractPoly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) were used to tailor the microstructure of single-walled carbon nanotubes (SWNTs) in both aqueous solutions and dry composite films. Microstructural changes were achieved as the pH of aqueous suspensions were changed, as evidenced by elevated suspension viscosity, scanning electron microscopy and electrical conductivity measurements. The ability to tailor microstructure is useful for aqueous SWNT processing and solid polymer nanocomposites.
Relatively Low Temperature Growth of Carbon Nanotubes by Thermal Chemical Vapor Deposition using Novel Catalysts
Authors: Tai Han-Chung , Lin Kao-Chao , Chuang Tsung-Ying , Chang Yao-Ren , Lai Rui-Ling , Shiu Jiun-Kai , Cheng Huang-Chung 
Published: April 2011

AbstractWe found out the promising catalyst materials(NiPd). The NiPd not only has the low melting point but also has the Pd enhancing the surface diffusion at low temperatures(<500'c ). With the Pd film thickness increasing, we could control the CNT density and synthesize more aligned and uniform CNTs. We also obtained the better electrical properties including lower turn-on field (3.4 V/um) and higher current density (34.3 mA/cm2) for NiPd as catalyst. For the advantages described above, we believe that the difficulty of low temperature on FED can be overcome. Further, the large area field emission display might be fabricated in the future.
Microwave Synthesis of Fe-filled Carbon Nanotubes
Authors: Kharissova Oxana Vasilievna , Ortiz Ubaldo , Hinojosa Moises 
Published: April 2011

AbstractA highly efficient one-step technique was developed in order to obtain long and aligned carbon nanotubes with or without Fe filling. The aligned carbon nanotubes (CNTs) were synthesized by heating ferrocene Fe(C5H5)2 using microwave (MW) irradiation. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to study the growth process of the aligned multi-layer carbon nanotubes. It was found that CNTs have a metal particle at the tip of each tube. This carbon nanostructures promise to become important in fuel cells and in nanoscale engineering of other systems.
Electron Transport in Semiconducting Chiral Carbon Nanotubes
Authors: Kauser M. Z. , Verma A. , Ruden P. P. 
Published: April 2011

AbstractWe report on electron transport characteristics for semiconducting, single wall, chiral carbon nanotubes. The Boltzmann transport equation is solved indirectly by the Ensemble Monte Carlo method. The basis for the transport calculations is provided by electronic structure calculations within the framework of a simple tight binding model. Scattering mechanisms considered are due to the electron-phonon interactions involving longitudinal acoustic, longitudinal optic, and radial breathing mode phonons. Results show significantly increased Umklapp scattering processes due to the reduced Brillouin zone compared to zigzag nanotubes. This results in increased transient velocity oscillation and negative differential mobility.
A Study of the Use of Novel Self-ordering Functionalized Polymers to Control Crystal Growth
Authors: Heywood Brigid R. , Ovens Adam C. D. 
Published: April 2011

ABSTRACTIn this research, the ability of a series of novel oligomeric organic species to control crystal nucleation and growth of inorganic crystals was investigated. The issues under consideration were (i) the relative balance of hydrophobicity and hydrophilicity which might be programmed into a polymer; (ii) the impact metal binding, or bridging on its activity in a crystallization reaction; (iii) the mode of self organisation. An homologous series of alkyl substituted sulphonated calixarenes were used to probe these issues.The ability of a metal cation to either bridge adjacent calix[4]arenes or to adsorb into the molecular cavity had an impact upon the interaction of these molecules with the nascent crystals; selective and specific adsorption behaviours were revealed by the expression of smooth well defined new faces in the equilibrium morphology of the crystals. When the hydrophobicity index was high (increased molecular weight of alkyl substituent) these compounds segregated at the gas/liquid interface and, as a consequence of cation-induced ordering, were able to induce the oriented nucleation of crystals. When the metal ion was preferentially adsorbed into the molecular cavity the complex induced twinning in the crystal form. These studies have revealed that, in contrast to earlier studies which argued for the only for an epitaxial relationship between the polymer and crystal, a tunable range of several chemical characteristics can be programmed into a polymeric substrates if they are to be used to control nucleation and growth.
Mechanical Behavior and Microstructure of Nanoporous Gold Films
Authors: Sun Ye Sun , Balk T. John 
Published: April 2011

ABSTRACTNanoporous gold (NPG) thin films offer an opportunity to investigate the effects of nanoscale geometric confinement on the mechanical properties of metals. In the present study, NPG films supported by substrates were fabricated by dealloying Au-Ag films on Kapton and silicon. The microstructural evolution of NPG at various stages of dealloying was observed and analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Cracking occurred at grain boundaries during dealloying and is believed to result from pre-existing tensile stress in the film. Stress evolution of NPG films on silicon substrates during dealloying was measured with the wafer curvature technique and revealed an overall shift toward compressive stress.
Insitu Observation of the Formation Dynamics of Nanohelices
Authors: Yeoh Terence , Mason Maribeth , Feinberg Zack , Leung Martin , Tasci Mehmet , Elarde Victor , Coleman James J 
Published: April 2011

ABSTRACTStrained InGaAs/GaAs bridges were released by a focused ion beam in order to observe the relaxation dynamics of the structure. Releasing the bridges resulted in the formation of chiral nanotubes with diameter of 920 nm and length 8.5 microns. The total time required for nanoscroll formation took > 20 minutes. From observing the scrolling action through time, it was found that the strain relief process differed from traditional wet etched nanoscrolls due to the simultaneous relief of strain from the released structures.
The Role of Nanoscale Confinement of Adhesion Promoting Molecules on the Adhesion and Resistance to Moisture Attack at the Polymer/Silicon Nitride Interface
Authors: Sharratt Bree M. , Dauskardt Reinhold H. 
Published: April 2011

ABSTRACTThe interface between a highly-crosslinked polymer film and a thin silicon nitride layer can be regulated using adhesion promoting molecules. This work compares the effects of both indirect polymer/inorganic interface chemistry modification by blending organosilane adhesion promoting molecules into the polymer layer, and direct modification by confining the organosilane molecules to the substrate surface. Of particular interest are the effects of these modifications on the occurrence of an anomalous subcritical debonding phenomenon previously observed for the unmodified interface. While significantly different adhesion values were measured, the influence of the blended organosilanes was limited to moderating moisture diffusion through the polymer layer, which correllates with moderated near-threshold growth rates. Conversely, nanoscale confinement of the adhesion promoting molecules did not result in expected universal increases in adhesion energy but did inhibit anomalous near-threshold behavior.