bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of Low-Cost Multi-Watt Yellow Lasers Using InGaAs/GaAs Vertical External-Cavity Surface-Emitting Lasers
Authors: Fallahi Mahmoud , Fan Li , Hessenius Chris , hader Jorg , Li Hongbo , Moloney Jerome , Stolz Wolfgang , Koch Stephan , Murray James 
Published: April 2011

ABSTRACTWe demonstrate a highly strained InGaAs/GaAs VECSEL operating at 1173 nm with more than 8.5 W output power and tunable over 40 nm. High-efficiency yellow-orange emission is then achieved by intra-cavity frequency doubling. Over 5 W of CW output power in the 585-589 nm spectral regions is achieved. This compact low-cost high-power yellow-orange laser provides an innovative alternative for sodium guidestar lasers or other medical / communication applications.
Quantum Design of Active Semiconductor Materials for Targeted Wavelengths
Authors: Moloney Jerome , Hader Joerg , Koch Stephan W. 
Published: April 2011

ABSTRACTPerformance metrics of every class of semiconductor amplifier or laser system depend critically on semiconductor QW optical properties such as photoluminescence (PL), gain and recombination losses (radiative and nonradiative). Current practice in amplifier or laser design assumes phenomenological parameterized models for these critical optical properties and has to rely on experimental measurement to extract model fit parameters. In this tutorial, I will present an overview of a powerful and sophisticated first-principles quantum design approach that allows one to extract these critical optical properties without relying on prior experimental measurement. It will be shown that an end device L-I characteristic can be predicted with the only input being intrinsic background losses, extracted from cut-back experiments. We will show that textbook and literature models of semiconductor amplifiers and lasers are seriously flawed.
The Effect of Plasma Treatment on the SiO2 film fabricated without Substrate Heating for Flexible Electronics
Authors: Kim Sun-Jae , Han Sang-Myeon , Kuk Seung-Hee , Kang Dong-Won , Han Min-Koo 
Published: April 2011

ABSTRACTSilicon dioxide (SiO2) films were deposited on crystalline silicon substrate by inductively coupled plasma chemical vapor deposition (ICP-CVD). In this paper, various process parameter-gas flow rate, ICP RF power, Process pressure were discussed for the investigation of refractive index. And some properties of the SiO2 film are investigated. Since there was no external substrate heating during the deposition, the SiO2 film showed poor electrical characteristics, such as shifted flat-band voltage and high effective charge density. We have proposed He plasma pre-treatment in order to reduce the interface fixed charge and some post-treatment. Our experimental results shows that He plasma pre-treatment supply thermal energy for decomposition of reactant gas and to remove effective charges. Hydrogen post-treatment also enhances electrical characteristics. We measured the effect of the plasma treatment using FT-IR spectrum and C-V characteristics.
Self-formation of Ti-rich Layers at Cu(Ti)/low-k Interfaces
Authors: Kohama Kazuyuki , Ito Kazuhiro , Tsukimoto Susumu , Mori Kenichi , Maekawa Kazuyoshi , Murakami Masanori 
Published: April 2011

ABSTRACTIn our previous studies, thin Ti-rich diffusion barrier layers were found to be formed at the interface between Cu(Ti) films and SiO2/Si substrates after annealing at elevated temperatures. This technique was called “self-formation of the diffusion barrier,” which is attractive for fabrication of ultra-large scale integrated (ULSI) interconnects. In the present study, we investigated the applicability of this technique to Cu(Ti) alloy films which were deposited on the four low dielectric constant (low-k) dielectric layers which are potential dielectric layers of future ULSI-Si devices. The microstructures were analyzed by transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS), and correlated with the electrical properties of the Cu(Ti) films. It was concluded that the Ti-rich interface layers were formed in all the Cu(Ti)/dielectric-layer samples. The primary factor to control composition of the self-formed Ti-rich interface layers was the C concentration in the dielectric layers rather than the formation enthalpy of the Ti compounds (TiC and TiSi). Crystalline TiC was formed on the dielectric layers with a C concentration higher than 17 at.%.
Al Diffusion in Polycrystalline Cu
Authors: Gstrein Florian , Kennel Harold , Budrevich Andre , Miner Barbara , Plombon John , Andideh Ebrahim 
Published: April 2011

ABSTRACTThe diffusion of aluminum (Al) from a source sandwiched between polycrystalline copper (Cu) thin films was investigated as a function of time and temperature through secondary ion mass spectroscopy (SIMS) and continuum simulations. Extracted diffusion coefficients for the bulk were in line with literature values. In order to simulate the experimentally derived diffusion profiles at temperatures where bulk diffusion is not the dominant diffusion mechanism (room temperature to 350 °C), it was necessary to explicitly include the re-distribution of Al as a result of Cu grain growth during anneal. Aluminum has the tendency to segregate to the Cu/liner and Cu/etch stop (ES) interface. The tendency of Al to segregate to the liner is ten times stronger for ruthenium (Ru) than for tantalum (Ta). In 100 nm wide dual damascene structures lined with Ru, this segregation behavior was responsible for the Al depletion in bulk Cu and for the Al depletion at the Cu/ES interface.
In-situ early stage electromigration study in Al line using synchrotron polychromatic X-ray microdiffraction
Authors: Chen Kai , Tamura N. , Tu K. N. 
Published: April 2011

ABSTRACTElectromigration is a phenomenon that has attracted much attention in the semiconductor industry because of its deleterious effects on electronic devices (such as interconnects) as they become smaller and current density passing through them increases. However, the effect of the electric current on the microstructure of interconnect lines during the very early stage of electromigration is not well documented. In the present report, we used synchrotron radiation based polychromatic X-ray microdiffraction for the in-situ study of the electromigration induced plasticity effects on individual grains of an Al (Cu) interconnect test structure. Dislocation slips which are activated by the electric current stressing are analyzed by the shape change of the diffraction peaks. The study shows polygonization of the grains due to the rearrangement of geometrically necessary dislocations (GND) in the direction of the current. Consequences of these findings are discussed.
Sacrificial Passivation of Nanoscale Metal Powders for Transient Liquid Phase Bonding
Authors: Bosco Nick , Manhat Beth , Janczak-Rusch Jolanta 
Published: April 2011

ABSTRACTDifferential scanning calorimetry (DSC) was used to evaluate the extent of liquid phase formation in particle compacts (compressed dry powders) comprised of organically capped nano-scale Ag particles and Sn. The Ag nanoparticles employed where synthesized with various organic molecules and procedures to produce particles with a range of capping thicknesses and decomposition temperatures (Td), as measured by thermogravimetric analysis (TGA). A baseline sample containing commercially available un-capped micrometer scale Ag was also investigated for comparison. Results indicate that all of the Sn initially present formed a liquid phase when heated through its melting point when combined with Ag particles exhibiting a comparatively thick cap of low Td. Slightly smaller fractions of Sn liquid were obtained when the Ag's cap was thin and of a high Td while particles with thin-low Td caps exhibited the highest levels of Sn consumption and similar to that observed with the un-capped micron-scale Ag particles. The reduction in the amount of Sn liquid formed is attributed to solid state reaction between the Ag and Sn particles resulting in the formation of a more refractory phase. The extent of the subsequent liquid phase reaction was also evaluated and is demonstrated to not necessarily be adversely effected by the presence of the organics. The significance of this work is the demonstration that organic molecules may be employed to prevent solid state reaction in particle compacts at elevated temperatures, yet allow the subsequent liquid phase reaction proceed uninhibited.
Modelling and Characterization of Ultrasonic Consolidation Process of Aluminium Alloys
Authors: Ghassemieh Elaheh , Ghassemieh Elaheh 
Published: April 2011

ABSTRACTUltrasonic consolidation process is a rapid manufacturing process used to join thin layers of metal at low temperatures and low energy consumption. In this work, finite element method has been used to simulate the ultrasonic consolidation of Aluminium alloys 6061 (AA-6061) and 3003 (AA-3003). A thermomechanical material model has been developed in the framework of continuum cyclic plasticity theory which takes into account both volume (acoustic softening) and surface (thermal softening due to friction) effects. A friction model based on experimental studies has been developed, which takes into account the dependence of coefficient of friction upon contact pressure, amount of slip, temperature and number of cycles. Using the developed material and friction model ultrasonic consolidation process has been simulated for various combinations of process parameters involved. Experimental observations are explained on the basis of the results obtained in the present study. The current research provides the opportunity to explain the differences of the behaviour of AA-6061 and AA-3003 during the ultrasonic consolidation process. Finally, trends of the experimentally measured fracture energies of the bonded specimen are compared to the predicted friction work at the weld interface resulted from the simulation at similar process condition. Similarity of the trends indicates the validity of the developed model in its predictive capability of the process.
Numerical Analysis of Packaging-Induced Failures in Cu/Low-k Interconnects
Authors: Karmarkar Aditya Pradeep , Xu Xiaopeng , Lin Xiao , Rollins Greg , Moroz Victor , Lin Xi-Wei 
Published: April 2011

ABSTRACTWith decreasing feature sizes for every technology node, multi-level metallization schemes that employ copper interconnects and low-k dielectrics are required to achieve the requisite circuit performance. Here, the effects of the mechanical stresses originating from the packaging process on Cu/Low-k interconnects are assessed. The impact of package defects on interconnect reliability is also analyzed. It is seen that the package reliability varies with underfill mechanical properties. The packaging process introduces global level stresses that propagate to the local, i.e. interconnect, level. Moreover, the package defects also have an adverse impact on the mechanical stresses in the metallization structure. The package defects alter the mechanical stresses in the metal lines and affect the reliability. The complex interaction between packaging process induced stresses, package level defects and mechanical properties of various materials is analyzed in order to create robust interconnect designs.
Organization of Magnetic/Noble Metal Heterostructures by an Applied External Magnetic Field
Authors: Pazos-Pérez Nicolás , Baranov Dmitry , Hilgendorff Michael , Pérez-Juste Jorge , Liz-Marzán Luis. M. , Giersig Michael 
Published: April 2011

ABSTRACTThis paper describes the synthesis of binary nanoparticles consisting of a noble metal and a magnetic component. These heterostructures were produced by a seeded-growth approach in aqueous solution. FePt nanoparticles, as the magnetic component, were first synthesized in an organic medium, subsequently transferred into water, and finally used as seeds for the growth of the noble metal Au. This procedure results in FePt-Au heterostructures. Moreover, the synthesized heterodimers were organized into mesoscopic lines under the influence of an externally applied magnetic field. The produced heterostructures were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV-vis spectroscopy.
Nanoscale Characterization of Metal/Semiconductor Nanocables
Authors: Vidu Ruxandra , McCandless Brian E , Berkheimer Jeff , Duval David J , Stroeve Pieter 
Published: April 2011

ABSTRACTComprehensive characterization at nanoscale is needed to create novel nanostructures for high efficiency solar cells. To produce consistent results, wide-ranging characterization procedures for integrated nanostructures have been developed. Characterization of a novel nanowire, nanotube and nanocable system includes: chemical, electrochemical, structural, optical and electrical characterization of nanostructures in relation with growth conditions. We present here results on Au and CdTe/Au system that help understanding how surface composition and properties are modified in this system. New challenges in structural characterization were also identified and improved sample preparation techniques were developed.
Synthesis of GaN Nanostructures at Low Temperatures by Chemical Vapor Deposition
Authors: Chow Christopher Y. , Raghothamachar Balaji , Carvajal Joan J. , Chen Hui , Dudley Michael 
Published: April 2011

ABSTRACTIn this study, we report on the synthesis of gallium nitride (GaN) nanopowders on boron nitride (BN) substrates both with and without the use of metal catalyst by chemical vapor deposition (CVD). The synthesis process is based on the reaction between gallium (Ga) atoms from the decomposition of gallium acetylacetonate and ammonia (NH3) gas molecules. Using this process, gallium nitride (GaN) nanopowders have been synthesized at temperatures as low as 400°C, lower than previously reported. The grown nanopowders were characterized by SEM, EDX and TEM. Analysis reveals that higher yields were obtained by treating the BN substrates with Ni catalyst. Experiments to study the effect of growth conditions on the morphology of the nanopowders and analyze the growth mechanism are ongoing.
Proper Combination of Catalyst Materials and Ethanol for High Yield in CVD Growth of Carbon Nanotubes
Authors: Maeda Fumihiko , Kobayashi Yoshihiro 
Published: April 2011

ABSTRACTCarbon nanotubes (CNTs) were grown by using a combination of ethanol and metallic Fe, which was not exposed to air before the growth. CNTs were also grown using intentionally oxidized Fe. The reaction products by these growths were analyzed by in situ photoelectron spectroscopy. We found that the oxidized Fe partially remained and did not completely reduce, resulting in low CNT yields. At higher growth temperature, oxide formation was found even when metallic Fe was used. These oxides induced a lowering of the decomposition efficiency of ethanol, resulting in difficulty of CNT growth by the combination of pure ethanol and Fe.
Influences of Hydrogen Gas on Carbon Nanotube Growth
Authors: Ohashi Fumitaka , Chen Guan Yow , Stolojan Vlad , Silva S. Ravi P. 
Published: April 2011

AbstractFor practical deployment of carbon nanotubes, an understanding of their growth mechanism is required in order to obtain better control over their crystallinity, chirality and other structural properties. In this study, we focus on the influences of gas species on carbon nanotube synthesis using thermal chemical vapour deposition. The influence of methane, hydrogen, and helium gases was investigated from the viewpoint of gas chemistry in relation to the nanotube structural change, by varying the growth pressure, the gas-flow ratio and the growth temperature. Simple changes in the hydrogen gas concentration during different growth stages have been found to induce surprising changes to the nanotube formation. The structure of the tubular carbon growth changed from amorphous to graphitic as the growth temperature and the concentration of hydrogen in the initial periods of growth decreases. The excess hydrogen tends to give rise to poor crystalline carbon nanofibres but has the effect of increasing the yields. Hydrogen gas is typically used in reducing metal catalyst particles during the pre-treatment and the carbon nanotube growth periods. We show that while hydrogen species can improve yield, it can also result in the degradation of the nanotube's crystallinity. The use of hydrogen in the growth process is one of the key parameters for enhanced control of carbon nanotube/nanofibre growth and their resulting crystallinity.
Vertically Aligned Carbon Nanotubes Formed Using dc PECVD as Switching Elements for Extreme Environment Space Electronics
Authors: Kaul Anupama B , Kowalczyk Robert , Megerian Krikor , Allmen Paul von , Baron Richard L 
Published: April 2011

AbstractVertically aligned carbon nanotube (CNT) nano-electro-mechanical (NEM) switches are currently being investigated for their application in radiation-hard, high temperature space electronics. Carbon nanotubes are attractive for switching applications since electrostatically-actuated CNT switches have low actuation voltages and power requirements, while allowing GHz switching speeds that stem from the inherently high elastic modulus and low mass of the CNT. Our NEM structure consists of CNTs that are grown using dc plasma-enhanced (PE) chemical-vapor-deposition (CVD) for forming vertically aligned, rigid tubes. A gas mixture of acetylene and ammonia were used for tube growth at a total pressure of a few Torr and temperatures up to 700 °C. We have formed arrays of single, vertically aligned tubes directly on Si, which was enabled by this first report of an optical lithography approach used to generate isolated tubes compared to e-beam lithography that is conventionally used. Vertical NEM switch devices were formed where single, vertically aligned tubes were seen within deep trenches, in close proximity to conducting electrodes.
Towards Development and Characterization of Ionic Junction via Microcontact Printing
Authors: Yadav Yamini , Prasad Shalini 
Published: April 2011

AbstractThe paper presents an evaluation of the feasibility of developing ionic surfactant coated single walled carbon nanotube (SWCNTs) (P-N) junction clusters via microcontact printing using intrinsic semi conducting SWCNTs. These SWCNTs are doped with anionic and cationic surfactant molecules respectively, thereby altering the Fermi energy levels of and its electrical properties. Two types of surfactants were used for doping the SWCNTs to develop extrinsically doped P and N type SWCNTs. Sodium dodecyl sulfate (SDS) having Na+ positive ionic charge (anions) and Cetyl trimethylammonium bromide (CTAB), having Br- negative ionic charge (cations) on its hydrophilic ends have been used to generate anionic SWCNTs (P type) and cationic SWCNTs( N- type respectively.
Using, dual level patterning process, these extrinsically doped anionic and cationic semiconducting SWCNTs clusters are alternatively symmetrically patterned in a parallel array to form crossbar P-N junctions onto a standard microfabricated platform using flexible polymeric poly-dimethylsiloxane (PDMS) stamps. Ink-based transfer of the nanomaterial from the relief structures achieves parallel alignment of SWCNTs clusters. The electrical device characterization is achieved by measuring I-V characteristics from the base micro fabricated platform.
Functionality of the nanodevice is demonstrated by studying the rectifying current – voltage (I-V) characteristics that shows promise towards the formation of a junction diode array, which can be used for integrating complex logic devices for high-end applications such as memory module and addressable logic. Lastly, we believe that the chemical modulation method and microcontact printing techniques will have a wide scope for development of nanomaterial-based devices.
Understanding Degradation of Doped Electroluminescent ZnS Phosphors
Authors: Jiang Yu , Stanley Jacob , Ruhlen Laurel , France Chris , Willey John , Bezryadina Anna , Bridges Frank , Carter Sue 
Published: April 2011

ABSTRACTWe have shown recently that the degradation of AC electroluminescence (EL) in ZnS:Cu,Cl and similar phosphors can be significantly reversed by a short anneal near 200°C. To better understand the degradation/rejuvenation processes, we investigated EL degradation and rejuvenation under different conditions. To probe for changes in the local atomic structure about the Cu sites, we collected Extended X-ray Absorption Fine Structure (EXAFS) data at the Cu K-edge EXAFS data for several as-made, thermally degraded (240°C anneal), and EL degraded powders.
Accelerated Molecular Dynamics Simulation of AFM Experiments Using the Bond-Boost Method
Authors: Kim Woo Kyun , Falk Michael L. 
Published: April 2011

ABSTRACTAccelerated molecular dynamics (MD) simulations of recent Atomic Force Microscope (AFM) experiments on oxidized silicon surfaces demonstrate a nontrivial dependence of frictional force on sliding velocity as well as temperature. By implementing hyper dynamics (HD) via the bond-boost method these simulations achieve sliding velocities in the range of real experimental values. Moreover, an analysis of the effects of temperature and sliding velocity on friction provide evidence for a systematic deviation from the modified Tomlinson model. We hypothesize regarding the origin of these deviations, and use the simulations to analyze the atomic processes that accompany sliding.
Solid Lubrication with Carbon Onions at High Temperature in Vacuum
Authors: Hirata Atsushi , Saito Shinji 
Published: April 2011

ABSTRACTSolid lubricant properties of carbon onions prepared from diamond nanoparticles through a heat treatment at 1700°C have been examined at high temperatures up to 300°C in air and vacuum. Sliding friction between a silicon disk on which carbon onions were dispersed and a stainless steel ball was measured by means of ball-on-disk type friction testing. Friction coefficients in vacuum decreased with temperatures and became stable above 100°C for longer service lives. On the contrary to this, friction coefficients in air increased with temperatures despite Raman spectroscopic analysis showed that the structure of carbon onions were stable in dry air up to 300°C.
Micromachined Lateral Force Sensors for Characterization of Microscale Surface Forces During Chemical Mechanical Polishing
Authors: Gauthier Douglas , Mueller Andrew , White Robert David , Manno Vincent , Rogers Chris , Hooper Donald , Anjur Sriram , Moinpour Mansour 
Published: April 2011

ABSTRACTMicromachined structures with diameters ranging from 50 — 100 μm have been applied to the measurement of the microscale shearing forces present at the wafer-pad interface during chemical mechanical polishing (CMP). The structures are 80 μm high poly-dimethyl-siloxane posts with bending stiffnesses ranging from 1.6 to 14 μN/μm. The structures were polished using a stiff, ungrooved pad and 3 wt% fumed silica slurry at relative velocities of approximately 0.5 m/s and downforces of approximately 1 psi. Observed lateral forces on the structures were on the order of 5–500 μN, and highly variable in time.
Mechanics of a Novel Shear-activated Microfiber Array Adhesive
Authors: Majidi Carmel , Fearing Ronald S 
Published: April 2011

AbstractElastic rod theory and principles of contact mechanics motivate the development of a novel, shear-activated, microfiber array adhesive. Unlike with conventional Pressure Sensitive Adhesives (PSAs), the microfiber array and backing are composed entirely of a stiff, glassy polymer (polypropylene, elastic modulus E = 1 GPa) and an externally applied shear load is required to achieve contact with a substrate. Previously, results from a Shear Power Test on glass indicated a maximum interfacial shear strength of 10 kPa over 4 sq. cm, a factor of 1000 greater than with a smooth polypropylene sheet of similar thickness. Here we present a theoretical model that describes the mechanism for shear-activated adhesion and predicts a shear strength of 27 kPa, on the order of the experimental measurement.