bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECTS OF GEOMETRY OF THE INTRAMEDULLARY STEM OF THE ULNA COMPONENT OF HINGED ELBOW JOINT PROSTHESES ON THE BONE AND IMPLANT BENDING STRESSES
Authors: AMARASINGHE R. S. , RUPASINGHE R. A. M. , ANURATHAN P. , HERATH S. R.
Published: April 2011

Cemented intramedullary stems are commonly used in total elbow arthroplasty and a considerable amount of time and money are spent for the design of such devices. In the endeavor of reducing production cost of implants, it is of particular interest as to how the geometry of the intramedullary stem can be altered in order to reduce the amount of raw material used in the manufacture of these components. The main aim of this study was to establish a simple mechanics model in preliminary designing of an elbow joint, so that the effects of the geometry of the intramedullary stem of the ulna component of hinged elbow joint prostheses on the bending stress distribution in the ulna bone and the prosthesis stem during static loading after cemented fixation of the implant can be readily estimated. Two mathematical models, namely (i) linear load transfer model and (ii) beams on elastic foundation model were used. The material considered is biocompatible stainless steel (316L). The locations of maximum bending stress occurrence were identified. Special attention was given toward identifying the locations of stress concentrations as well as the degree of stress shielding expected with various stem geometries. The results were compared to that obtained using well-established finite element analysis techniques and the beams on elastic foundation model were chosen to interpret the stresses. It was found that reducing the length of the intramedullary stem or alternatively tapering the distal end of the stem results in a considerable reduction of stress shielding and renders the bending stress distribution in the bone to be more natural. The use of a tapered stem of rectangular cross section showed a 50% reduction in material usage and a reduction of stress shielding compared to that for a stem of uniform circular cross section. Tapered rectangular sections gave the best results in terms of functionality and cost effectiveness. This observation agrees very well with the rationale of implant design that is practiced over the years. The stresses found using this study can be used for preliminary checks against yield and fracture of the stem material and bone material.
CLINICAL USE OF FUNCTIONAL ELECTRICAL STIMULATION FOR CORRECTION OF FOOT DROP: A COMPARISON BETWEEN SUBACUTE AND CHRONIC STROKE PATIENTS
Authors: SABUT SUKANTA K. , SIKDAR CHHANDA , KUMAR RATNESH , MAHADEVAPPA MANJUNATHA
Published: April 2011

Functional electrical stimulation (FES) allows active exercises for correction of foot drop in stroke patients. Our objective is to evaluate and compare the effects of FES therapy in walking ability, calf muscle spasticity, and lower-extremity motor recovery between subacute and chronic stroke patients. Twenty consecutive hemiplegic patients having foot drop were assigned either to subacute or chronic group. Both group subjects were treated with conventional rehabilitation program combined with FES therapy for 12 weeks. All subjects received the electrical stimulation to the peroneal nerve of paretic limb for 15–30 min while walking.

After being treated with FES-based rehabilitation program, subacute subjects showed a mean increase in walking speed of 31.3% and chronic subjects of 19.1% and the physiological cost index (PCI), with a reduction of 66.7% in subacute subjects and 46.4% in chronic subjects between the beginning and end of the trial. Improvement was also measured in gait parameters such as cadence, step and stride lengths, ankle joint range of motion (ROM), calf muscle spasticity, and lower-extremity motor recovery assessed by Fugl-Meyer score in both group subjects, but subacute subjects improved better compared with chronic subjects. In conclusion, early and intensive interventions of FES therapy combine with conventional rehabilitation program could significantly improve the waking ability and recovery of lower-extremity motor functions in stroke survivors.
FINITE ELEMENT MODELS FOR COMPUTER SIMULATION OF INTRASTROMAL PHOTOREFRACTIVE KERATECTOMY
Authors: HAMEED SAYED AHMED A. , SOLOUMA NAHED H. , EL-BERRY AMAL A. , KADAH YASSER M.
Published: April 2011

The main idea to correct sight disorders using lasers is to modify corneal curvature by applying laser to specific layers of the cornea. Intrastromal photorefractive keratectomy (ISPRK) is a laser technique used to correct sight disorders by evaporating corneal tissue from the stroma. Evaporating such tissue produces small cavities that may coincide to form a larger cavity. The composed big cavity is assumed to collapse to deform the overall curvature of the cornea. In this work, we provide finite element models to simulate the ISRPK procedure using a three-dimensional (3D) model of the cornea with typical parameters. The model outcome was compared with an earlier 2D model used for the same purpose, so as to determine its accuracy. In addition, a 3D finite element simulation of the procedure was made for a virtual astigmatic case to visualize the corneal curvature change. The results of this work show that this finite element models provide an accurate simulation of the corneal deformation expected after performing the procedure.
A MATHEMATICAL MODEL OF THE GROWTH PLATE
Authors: GARZÓN-ALVARADO DIEGO A. , NARVÁEZ-TOVAR CARLOS A. , SILVA OCTAVIO
Published: April 2011

The growth plate is a structure formed of cells called chondrocytes; these are arranged in columns and provide the elongation of bone due to their proliferation and hypertrophy. In each column, we can see chondrocytes in their proliferating state, which are constantly dividing, and in hypertrophic state, which grow in a nearly spherical shape. These cells express different proteins and molecules throughout their half-life and exhibit a special behavior depending on their local mechanical and biochemical environments. This article develops a mathematical model that describes the relationship of geometry, growth by proliferation and hypertrophy, and vascular invasion with biochemical and mechanical factors present during endochondral ossification.
NUMERICAL STUDY ON PERISTALTIC TRANSPORT OF FRACTIONAL BIO-FLUIDS
Authors: TRIPATHI DHARMENDRA
Published: April 2011

A numerical study is presented to examine the peristaltic transport of fractional bio-fluids (viscoelastic fluids with fractional Oldroyd-B model) through the channel. Analysis is carried out under the assumptions of long wavelength and low Reynolds number. Numerical and analytical approximate solutions of problem are obtained by using homotopy analysis method. It is assumed that the cross section of the channel varies sinusoidally along the length of channel. The effects of fractional parameters, material constants (relaxation time and retardation time), time and amplitude on the pressure and frictional force across one wavelength are studied with particular emphasis. The computational results are presented in graphical form. It is found that the effect of both fractional parameters on pressure is opposite to each other i.e., pressure reduces with increasing magnitude of the first fractional parameter whereas it increases with increasing magnitude of the second fractional parameter. The effects of relaxation time and retardation time on pressure are similar to that of first and second fractional parameters, respectively.
SENSING OF PATHOLOGICAL TREMOR USING SURFACE ELECTROMYOGRAPHY AND ACCELEROMETER FOR REAL-TIME ATTENUATION
Authors: WIDJAJA FERDINAN , SHEE CHENG YAP , ANG WEI TECH , AU WING LOK , POIGNET PHILIPPE
Published: April 2011

Tremor is the most common movement disorder and it is affecting more and more people as the world is aging. The cost involved is big considering the financial and social impact. This paper explores an assistive technology solution for upper limb pathological tremor compensation. Using both surface electromyography (SEMG) and accelerometer (ACC), a real-time pathological tremor compensation with functional electrical stimulation (FES) is proposed. One advantage of using SEMG is the electromechanical delay (SEMG data precedes the ACC data by 20–100 ms). Hence by detecting the tremor in advance, there is enough time window to do the necessary computation and to actuate the antagonist muscle by FES. This is also possible because the time taken for FES to actuate the muscle is significantly less than that of the neural signal, as detected by SEMG. For estimation of tremor parameters and separation between voluntary motion and tremor, an algorithm based on extended Kalman filter (EKF) is proposed. Experimental result from one essential tremor patient has shown 57% reduction in tremor power as measured by the ACC.
A SHORT-TERM FREE-FALL LANDING ENHANCES BONE FORMATION AND BONE MATERIAL PROPERTIES
Authors: LIN HSIN-SHIH , HUANG TSANG-HAI , MAO SHIH-WEI , TAI YUH-SHIOU , CHIU HUNG-TA , CHENG KUANG-YOU B. , YANG RONG-SEN
Published: April 2011

To investigate the effects of a short-term free-fall landing course on local bone metabolism and biomaterial properties, 32 female Wistar rats (7 week old) were randomly assigned to three groups: L30 (n = 11), L10 (n = 11) and CON (n = 10). Animals in the L30 and L10 groups were subjected to 30 and 10 free-fall landings per day, respectively, from a height of 40 cm for five consecutive days. Animals' ulnae were studied using methods of dynamic histomorphometry, tissue geometry, biomaterial measurements and collagen fiber orientation (CFO) analysis. In dynamic histomorphometry analysis, periosteal as well as endosteal mineral apposition rates (MAR, μm/day) were significantly higher in L30 group than in the CON group (p < 0.05). In addition, the periosteal bone formation rate (BFR/BS, μm2/μm3/year) was significantly higher in the L10 and L30 groups (p < 0.05). The ulnae of the animals in the two landing groups were higher in post-yield energy without significant changes in CFO, tissue size or tissue weight measurements. In conclusion, a short-term free-fall landing training produced a slight, but significant, higher bone formation in the ulnae of young female rats. Enhanced tissue biomaterial properties did not accompany size-related changes, suggesting that bone adapting to mechanical loading begins with changes in tissue-level properties.
EXISTENCE RESULT FOR NONLINEAR PARABOLIC EQUATIONS WITH LOWER ORDER TERMS
Authors: DI NARDO ROSARIA , FEO FILOMENA , GUIBÉ OLIVIER
Published: April 2011

In this paper, we prove, the existence of a renormalized solution for a class of nonlinear parabolic problems whose prototype is [Formula: see text] where QT = Ω × (0, T), Ω is an open and bounded subset of ℝN, N ≥ 2, T > 0, Δp is the so called p-Laplace operator, [Formula: see text], c ∈ (Lr(QT))N with [Formula: see text], [Formula: see text], b ∈ LN+2, 1(QT), f ∈ L1(QT), g ∈ (Lp'(QT))N and u0 ∈ L1(Ω).
PERIODIC SOLUTIONS OF SECOND-ORDER DIFFERENTIAL INCLUSIONS SYSTEMS WITH (q, p)-LAPLACIAN
Authors: PAŞCA DANIEL
Published: April 2011

Some existence results are obtained for periodic solutions of nonautonomous second-order differential inclusions systems with (q, p)-Laplacian.
CONSTRUCTING NON-MSF WAVELETS FROM GENERALIZED JOURNÉ WAVELET SETS
Authors: SHUKLA N. K. , YADAV G. C. S.
Published: April 2011

Dai and Larson [Mem. Amer. Math. Soc.134 (1998), no. 640] obtained a family of wavelet sets using the Journé wavelet set. In this paper, we expand this family and call its members to be generalized Journé wavelet sets. Furthermore, with the help of these wavelet sets, we provide a class of non-MSF wavelets which includes the one constructed by Vyas [Bull. Polish Acad. Sci. Math.57 (2009) 33–40]. Most of these non-MSF wavelets are found to be non-MRA.
SYNTHESIZING A WELL-ALIGNED CARBON NANOTUBE FOREST WITH HIGH QUALITY VIA THE NEBULIZED SPRAY PYROLYSIS METHOD BY OPTIMIZING ULTRASONIC FREQUENCY
Authors: YANG ZHI , NIE HUAGUI , ZHOU XUEMEI , YAO ZHEN , HUANG SHAOMING , CHEN XIAOHUA
Published: April 2011

Nebulized spray pyrolysis (NSP) offers ease of scaling into an industrial scale process method for large-scale CNT synthesis. In the method, ultrasonic frequency plays an important role in the formation of well-aligned carbon nanotubes (CNTs). In this work, we obtain well-aligned CNTs with high quality by optimizing ultrasonic frequency via the NSP method. SEM, TEM and HRTEM results show that the aligned CNTs obtained under an ultrasonic frequency of 1.8 MHz have good alignment, uniform nanotube length (~200 μm), high density and no trace of other carbon nanoparticles. The Raman spectra result further confirms that the aligned CNTs have a high graphitization degree. Furthermore, we find that ultrasonic frequency is an important factor in determining the nanotube diameter. The higher the ultrasonic frequency, the smaller the nanotube diameter. This rule may be very helpful in the preparation of large-scale well-aligned CNTs with high quality and diameter-controlled at low cost.
New insights into the cone sheet structure of the Cuillin Complex, Isle of Skye, Scotland
Authors: Tibaldi A. , Pasquarè A.F. , Rust D.
Published: April 2011

Structural data were collected on 1100 cone sheets and dykes with the aim of reconstructing the geometry of the complex, recognizing emplacement phases, and contributing to understanding this classical area and the evolution of cone sheets in general. Mean sheet dip angles are 40°, 43°, 47° and 50° in four sections transecting the complex. Sheet thickness ranges from a few centimetres to 5 m, with a dominant thickness of <1 m. Intrusion intensity ranges from 1% to 35%, increasing towards the central zone. Initial cone sheet emplacement occurred within a gabbroid pluton that was hot enough to amalgamate the sheets. Dykes striking N155–165° were then emplaced, followed by shallow-dipping cone sheets, dykes striking N135–145°, steep-dipping cone sheets, dykes striking roughly east–west and, finally, dykes striking N150–165°. The NW–SE-striking dykes were emplaced during re-establishment of regional stresses, after perturbation by local magma-induced stresses when cone sheets were emplaced, interspersed with magma escaping horizontally from the volcano conduit to feed local dykes. Two successive magma chambers at different depths, with flat geometries and different volumes, may explain sheet architecture and location. The whole cone sheet system consists of a stack of parallel concentric sheets, rather than a model of convergence towards a single focus.
Isotope geochemistry and revised geochronology of the Purrido Ophiolite (Cabo Ortegal Complex, NW Iberian Massif): Devonian magmatism with mixed sources and involved Mesoproterozoic basement
Authors: Martínez Sonia Sánchez , Arenas Ricardo , Gerdes Axel , Castiñeiras Pedro , Potrel Alain , Fernández-Suárez Javier
Published: April 2011

In the Purrido Ophiolite (Cabo Ortegal Complex), new U–Pb zircon dating of the amphibolite G03-8 (by laser ablation inductively coupled plasma mass spectrometry) confirms the existence of a dominant Mesoproterozoic zircon population with a refined age of 1155 ± 14 Ma. However, the U–Pb zircon dating of two more amphibolite samples (by sensitive high-resolution ion microprobe) has provided new ages of 395 ± 3 Ma and 395 ± 2 Ma, respectively, interpreted as the crystallization age. Hf isotope data for zircon show that most of the Devonian zircons crystallized from a juvenile depleted mantle source. The Mesoproterozoic zircons have relatively juvenile Hf isotopic composition reflecting some influence of an older component. A few Devonian zircon crystals show evidence of mixing with an older component represented by the Mesoproterozoic zircons. The whole-rock Sm–Nd isotope data indicate an important heterogeneity in the composition of the Purrido amphibolites, only compatible with the generation of their protoliths from two sources. We interpret these puzzling data as resulting from the mixing of a Devonian mantle-derived magma with a Mesoproterozoic basement. These new data provide new perspectives in the interpretation of the most common ophiolites across the Variscan suture in Europe.

Supplementary material:

Analytical methods, zircon U–Th–Pb SHRIMP analytical data, zircon U–Th–Pb LA-ICP-MS analytical data, zircon Lu–Hf LA-MC-ICPMS analytical data and whole-rock Sm–Nd isotope data are available at
http://www.geolsoc.org.uk/SUP18449
.
The 3D reconstruction of geological structures based on remote sensing data: example from the Anaran anticline, Lurestan province, Zagros fold and thrust belt, Iran
Authors: Snidero M. , Amilibia A. , Gratacos O. , Blanc E.J.-P. , Muñoz J.A.
Published: April 2011

This work presents a methodological workflow for the 3D reconstruction of geological surfaces at regional scale, based on remote sensing data and geological maps. This workflow was tested on the reconstruction of the Anaran anticline, located in the Lurestan province, Iran. The remote sensing dataset used is a combination of Aster and Spot images as well as a high-resolution digital elevation model. The Aster images were processed using the Optimum Index Factor technique and pansharpened with the Spot technique for an easier 3D mapping. Structural dip data were acquired through analysis of the 3D mapped geological traces and analysed to divide the structure into cylindrical domains. Related plunge line orientation was used to project data along the structure, covering those areas where little or no information was available. Following the dip-domain concept a selected horizon is reconstructed and manually adjusted to the mapped traces. The reconstruction of the Anaran anticline demonstrates the applicability of this workflow when attempting to remotely reconstruct a reliable geological surface. The reconstructed surfaces clearly show the geometry of the Ilam and Asmari top horizons and the main faults affecting the anticline, allowing a consistent structural interpretation of the deeper structures.
Hydrothermal origin of elevated iron, manganese and redox-sensitive trace elements in the
c
. 635 Ma Doushantuo cap carbonate
Authors: Huang Jing , Chu Xuelei , Jiang Ganqing , Feng Lianjun , Chang Huajin
Published: April 2011

Major and trace element, including REE, concentrations of the Doushantuo cap carbonate (
c
. 635 Ma) in South China show enrichment in Fe, Mn and redox-sensitive elements and slightly negative Ce anomalies, indicating anoxic environments during cap carbonate precipitation. High Fe
T
/Al ratios but very low concentration of extractable pyrites suggest ferruginous rather than euxinic conditions. The REE + Y patterns of samples show enrichment of heavy REE (HREE), positive Eu anomalies and positive Y anomalies, implying a hydrothermal origin for elevated concentration of Fe, Mn and redox-sensitive elements. The results suggest that ferruginous Ediacaran oceans may have rooted from hydrothermally induced iron accumulation in severely glaciated Cryogenian oceans.
Crustal–lithospheric structure and continental extrusion of Tibet
Authors: Searle M.P. , Elliott J.R. , Phillips R.J. , Chung S.-L.
Published: April 2011

Crustal shortening and thickening to
c
. 70–85 km in the Tibetan Plateau occurred both before and mainly after the
c
. 50 Ma India–Asia collision. Potassic–ultrapotassic shoshonitic and adakitic lavas erupted across the Qiangtang (
c
. 50–29 Ma) and Lhasa blocks (
c
. 30–10 Ma) indicate a hot mantle, thick crust and eclogitic root during that period. The progressive northward underthrusting of cold, Indian mantle lithosphere since collision shut off the source in the Lhasa block at
c
. 10 Ma. Late Miocene–Pleistocene shoshonitic volcanic rocks in northern Tibet require hot mantle. We review the major tectonic processes proposed for Tibet including ‘rigid-block', continuum and crustal flow as well as the geological history of the major strike-slip faults. We examine controversies concerning the cumulative geological offsets and the discrepancies between geological, Quaternary and geodetic slip rates. Low present-day slip rates measured from global positioning system and InSAR along the Karakoram and Altyn Tagh Faults in addition to slow long-term geological rates can only account for limited eastward extrusion of Tibet since Mid-Miocene time. We conclude that despite being prominent geomorphological features sometimes with wide mylonite zones, the faults cut earlier formed metamorphic and igneous rocks and show limited offsets. Concentrated strain at the surface is dissipated deeper into wide ductile shear zones.
(Invited) Electrochemical Formation of Nanoporosity in n-InP Anodes in KOH
Authors: Buckley D. Noel , O'Dwyer C. , Lynch Robert , Quill Nathan
Published: April 2011

We review our recent work on anodic formation of nanoporosity in n-InP in aqueous KOH. Typically, a nanoporous sub-surface region is formed beneath a thin, dense near-surface layer. Atomic force microscopy (AFM) shows pit formation on the surface in the earlier stages of etching, and transmission electron microscopy (TEM) shows individual nanoporous domains separated from the surface by a thin InP layer. Each domain develops from a surface pit. We developed a model based on propagation of pores along the <111>A directions. The model predicts porous domains with a truncated tetrahedral shape and this was confirmed by scanning electron microscopy (SEM) and TEM. Pores are cylindrical and have well-developed facets only near their tips. No porous layers are observed at a KOH concentration of 1.1 mol dm-2 or lower. Linear sweep voltammograms (LSVs) show a pronounced anodic peak corresponding to the formation of the porous region
(Invited) Modeling Some "Meta" Aspects of Pore Growth in Semiconductors
Authors: Föll Helmut , Leisner Malte , Carstensen Jürgen
Published: April 2011

A "meta" model for electrochemical pore growth in semiconductors is presented which is essentially based on two assumptions: i) current flow at the etching interface occurs in current bursts and not by constant current flow and ii) current flow depends on the passivation behavior at the etching interface. The meta model is thus not sensitive to factors like the semiconductor material or the detailed dissolution chemistry. In order to demonstrate the concept of the meta model a number of recent results in InP will be discussed. The treatise includes the mechanism of currentline and crystallographical pore growth, as well as the reasons for the characteristic transition between both pore growth modes. A numerical Monte Carlo model for pore growth based on the meta model, which is capable of closely simulating a number of pore structures, will also be presented.
Raman Scattering Spectroscopy of Metal-Assisted Chemically Etched Rough Si Nanowires
Authors: Glynn Colm , Lotty Olan , McSweeney William , Holmes Justin D. , O'Dwyer C.
Published: April 2011

We have shown that SiNWs formed on (100) Si substrates by metal-assisted chemical etching can exhibit different Raman scattering processes that are dependent on the orientation of examined NWs to the incident excitation light. The SiNWs retain the single crystal orientation and doping from the original bulk substrate and form as rough and mesoporous NWs with a SiOx shell surrounding the NW. The Raman scattering spectra of vertical and horizontally lying SiNWs showed quantum confined phonon scattering processes from narrow and roughened NWs, whose spectral resolution was increased by orienting NW horizontal to the beam to maximize probe cross-section. SiOx contributions were not evident and specific substrate Raman modes were suppressed for horizontal NWs. Beam induced heating to 425 K showed pronounced red-shifting and asymmetry of the TO, 2TO and 2TA phonon modes consistent with phonon quantum confinement effects not observable when the NW were parallel to incident excitation.
(Invited) Functionalization of Germanium Nanowires
Authors: Collins Gillian , Fleming Peter , O'Dwyer C. , Morris Michael , Holmes Justin D.
Published: April 2011

Halogen-termination and organic functionalization of germanium (Ge) nanowires is described. X-ray photoelectron spectroscopy (XPS), X-ray photoemission electron spectroscopy (XPEEM), infrared spectroscopy (IR) and transmission electron spectroscopy (TEM) were used to characterize the modified nanowire surfaces. The stability of alkyl and alkanethiol monolayers formed on Cl, Br and I-terminated surfaces are compared. The direct covalent attachment of aryl ligands onto H-Ge nanowires can be achieved by the decomposition of arenediazonium salts in acetonitrile solutions. The influence of the ring substituent on the thickness and uniformity of the functionalization layer was investigated.
In-Situ Electrochemical Comparisons between GaAs and InP Regarding a Promising Anodic Process in Liquid Ammonia
Authors: Goncalves Anne-Marie , Mathieu Charles , Seitz Oliver , Mezailles Nicolas , Etcheberry Arnaud
Published: April 2011

A protective monolayer "phosphazene" like film on InP has been already successfully evidenced by a controlled anodic process in liquid ammonia (NH3 Liq.). In order to understand the formation mechanism of this passivating film, in-situ comparisons of electrochemical interface responses are performed as well on InP as GaAs. Current-voltage and interfacial capacity measurements are explored on both semiconductors. Similarities of electrochemical behaviours between these two semiconductors are striking. But contrary to InP, the initial surface state is electrochemically recovered by an in-situ cathodic treatment on GaAs. This absolute reversible electrochemical behaviour is definitively significant for GaAs.
Electroless Oxidation of Diamond Surfaces: Relevance of Concepts Developed for Classical SC Electrochemistry
Authors: Charrier Gaelle , Vigneron Jacki , Etcheberry Arnaud , Simon Nathalie
Published: April 2011

"Electroless" oxidation has been widely studied on III-V and II-VI semiconductor (SC) interfaces. These works showed that using oxidizing agents with standard potentials close to the valence band (VB) position of the material, the reduction of the oxidizing specie (Ox+) by holes injection in the valence band and the oxidation of the SC can take place simultaneously on the same surface. In the present work, we study the relevance of these concepts in the oxidation of a non conventional wide gap SC: Boron Doped Diamond (BDD). Therefore, we used two different oxidizing agents (Ce4+ and Fe(CN)63-) and studied the possibility to produce "C-O" moieties on diamond electrodes in an "electroless" way.
Electrochemical Passivation of Homoepitaxial InP (100) Thin Films for Light Induced Hydrogen Evolution: A Synchrotron Radiation Photoelectron Spectroscopy Study
Authors: Muñoz Andres G. , Heine Christian , Klemm Hagen W. , Hannappel Thomas , Szabo Nadine , Lewerenz Hans-Joachim
Published: April 2011

Recent synchrotron radiation photoelectron spectroscopy (SRPES) investigations on the surface chemistry of electrochemically conditioned surfaces of homo-epitaxial p-InP(100) layers deposited by MOVPE are described. The electrochemical conditioning, consisting in a voltammetric cycling in an HCl solution under illumination and a subsequent photo-electrochemical deposition of Rh, yields efficient photoelectrodes for light induced hydrogen evolution. The deconvolution of the In 3d5/2 and P 2p lines reveals that the oxide film consists of InPO3, In2(PO3)3 and In2O3. The presence of In2O3, with a band gap of 2.6 eV and an affinity of 4.3 eV can explain the conductivity of the oxide film, of about 7 nm thickness, by resonance tunneling. The detection of minute amounts of adsorbed Cl-atoms, presumably at the InP-oxide interface, is in agreement with the formation of interfacial dipoles responsible for the photoelectrochemical activation as confirmed by ultraviolet photoelectron spectroscopy (UPS)-measurements.
Dye-Sensitized Hole Injection at p-type III-V Electrode Interfaces
Authors: Price Michelle , Maldonado Stephen
Published: April 2011

Single crystalline, non-degenerately doped p-type gallium phosphide (GaP) electrodes were examined for the purpose of constructing aqueous-based dye-sensitized systems featuring light-stimulated hole injection. Features including the relevant semiconductor-sensitizer energetics, surface conditioning, and redox mediator are examined to define system aspects that most strongly affect internal quantum yields for charge injection. The present findings indicate that the preparation of GaP electrode interfaces strongly influences charge injection yields.
Study of Cu Bimetallic Corrosion in CMP Chemical Environments Using Optical Scanning and Micropattern Corrosion Screening
Authors: Yu Kyle , Thomas Nicole , Venkataraman Shyam S. , Pillai Karthikeyan S. , Hurd Trace , Boggs Karl , Chyan Oliver
Published: April 2011

On-chip corrosion within Cu interconnect microstructures can result in increased defectivity that causes serious reliability issues and decreases production yield. This active bimetallic corrosion is especially of concern when Cu/barrier contacts are directly exposed to corrosive chemicals during CMP and post CMP clean processes. In this paper, a new, rapid, corrosion screening metrology was developed using both micropattern corrosion testing and high resolution 3-D optical profilometry. Micropattern screening revealed that gallic acid, often perceived as anti-oxidant, is actually rather corrosive to Cu at pH ≥ 9. Increased Cu corrosion rates were found in oxygen rich ambients and with direct contact to nobler barriers like Ru. Efficient micropattern screening also enabled the discovery of new Cu corrosion inhibitors. The initial inhibition activation on the Cu surface was studied by 3-D optical profilometry.
Potential of a Sensitive Silicon Mechanical Stress Sensor Based on a Change in Gate-Induced-Drain Leakage Current
Authors: Lau Wai S. , Yang Peizhen , Ho V. , Siah S.Y. , Chan L.
Published: April 2011

Mechanical stress sensors based on silicon piezoresistance have limited sensitivity. Mechanical stress sensors based on the on-current or off-current or threshold voltage of silicon MOS transistors also have limited sensitivity. In this paper, we report that the sensitivity of a silicon-based mechanical sensor can be significantly improved by simply monitoring the gate-induced-drain leakage (GIDL) current of an n-channel MOS transistor with tensile mechanical stress bias and the underlying principle will also be discussed.
Catalytic CVD Growth of Nanomaterials for Advanced Interconnects: Si Nanowires and Few Graphene Layers/Carbon-Nanotubes Composites
Authors: Jousseaume Vincent , Renard Vincent T.
Published: April 2011

Despite the promising potential of nanomaterials, their co-integration with CMOS, especially in interconnection levels, remains challenging because their fabrication has to be done within severe constrains. These nanomaterials can be grown by catalytic Chemical Vapor Deposition but the catalyst should be compatible with Back-End-Of-Line (BEOL) processes. Moreover, synthesis temperatures have to be lower than 450°C. This paper discusses two examples of CVD grown nanomaterials using BEOL compatible processes. First, we investigate the growth of a composite made of carbon nanotubes capped by few graphene layers. By using appropriate catalyst and gaseous carbon precursor, we show that carbon nanotubes can grow epitaxially under the graphene layers at compatible temperatures. Then, we describe a method to grow silicon nanowires using BEOL-compatible copper-based catalysts. In this case, oxidation of copper prior to growth allows reducing silicon nanowire synthesis temperature below 450°C.
(Invited) 3D Integration in Silicon Technology
Authors: Farooq Mukta G.
Published: April 2011

3Di (3D integration) refers to a family of technologies which enable the stacking of active Si layers with vertical connections between them. 3Di has the ability to enhance chip performance by increasing bandwidth, reducing wire delay, and enabling better power management. Several researchers have investigated TSV (Through Silicon Via) fabrication, insulation, metallization, integration, the impact of TSVs on devices, thermo-mechanical integrity and reliability of TSVs. This paper presents a review of some of these publications in order to understand the options and challenges in 3Di.
Sub-Atmospheric Chemical Vapor Deposition of SiO2 for Dielectric Layers in High Aspect Ratio TSVs
Authors: Lisker Marco , Marschmeyer Steffen , Kaynak Mehmet , Tekin Ibrahim
Published: April 2011

The formation of TSVs includes a deep Si trench etching and a formation of a dielectric layer along the high-aspect-ratio Si trench to isolate the filling conductive material from the bulk Si. The isolation of the filling conductor from the silicon substrate becomes more important for higher frequencies due to the high coupling to the silicon. The importance of the oxide thickness on the wall can be verified using electromagnetic simulators, such as HFSS®. A SA-CVD with a pulsed flow of ozone is developed and used to deposit an isolation oxide to the walls of deep silicon trenches. The technique provides a good coating of the 100µm depth silicon trenches with the high aspect ratio of 20. Developed technique allows covering the deep silicon trenches by oxide and makes the high isolation of TSVs from silicon substrate feasible which is the key for performance of TSVs for mm-wave 3D packaging.
Direct Copper Electrochemical Deposition on Ru-Based Substrates for Advanced Interconnects Target 30 nm and 1/2 Pitch Lines: From Coupon to Full-Wafer Experiments
Authors: Armini Silvia , Demuynck Steven , El-mekki Zaid , Swerts Johan , Nagar Magi , Radisic Alex , Heylen Nancy , Beyer Gerald , Leunissen Leonardus , Vereecken Philippe
Published: April 2011

Extending copper electrochemical deposition to 3x nm nodes and beyond requires a new plating approach that is not constrained by typical PVD copper seed step coverage performance. To this purpose, we propose a copper direct plating process on Plasma Enhanced Atomic Layer Deposition (PEALD) Ru -based resistive substrates, where the Cu seed is deposited in-situ during the front propagation from the edge to the center of the wafer. In order to understand the full-wafer copper direct plating process that occurs on these liners, the effect of plating tool advanced features, applied waveform, plating chemistry and substrate surface activation on the subsequent plated copper nucleation behavior are studied.
Room Temperature Copper Seed Layer Deposition by Plasma-Enhanced Atomic Layer Deposition
Authors: Mao Jiajun , Eisenbraun Eric , Omarjee Vincent , Korolev Andrey , Dussarrat Christian
Published: April 2011

AbaCus, a newly developed fluorine-free precursor has been used for room temperature copper deposition using plasma enhanced chemical vapor deposition (PEALD). This process has been characterized and the film properties investigated in term of composition, deposition rate, resistivity, grain size and platability. Integration results with completely filled structures obtained demonstrate a high potential for use in advanced interconnect technologies.
Edge Bonding Void Free Low Temperature Oxide-Oxide Direct Bonding Process
Authors: Castex Arnaud , Broekaart Marcel , Thieffry Stephane , Landry Karine , Fontanière Richard , Lagahe Chrystelle
Published: April 2011

This paper presents a new wafer bonding process used for back side illuminated (BSI) image sensors manufacturing, with high bonding energy of 2 J/m2, without peripheral edge bonding voids that occur with the standard process.
Die/Wafer Sub-Micron Alignment Strategies for Semiconductor Device Integration
Authors: Shea-Rohwer Lauren , Martin James E. , Chu Dahwey
Published: April 2011

This study explores self-aligning patterns to achieve sub-micron alignment of die/wafers. We have patterned 2-d arrays of gold lines, whose width is half the periodicity, onto substrates. When commensurate patterns are brought into contact, the surface interactions between the Au lines enables high-resolution alignment, manually. Self-assembled monolayers of alkanethiols on the Au, further enhance the surface interactions, enabling alignment in less than half the time as for the uncoated die. A computation of the alignment force and torque between two featured surfaces illustrates how best to pattern surfaces to maximize the tendency to align. An array of lines with a sinusoidal modulation in their spacing is more tolerant of initial misalignment, yet retains the high registration force of periodic line arrays. The optimal registration pattern might be a single spiral, as it generates both a radial force and a torque. Such patterns on die/wafers would enable precision device integration.
(Invited) Advances in Si and Ge Millisecond Processing: From SOI to Superconductivity and Carrier-Mediated Ferromagnetism
Authors: Skorupa Wolfgang
Published: April 2011

This paper reviews the advances that millisecond thermal processing using flash lamps and lasers brings to the processing of the most advanced semiconductor materials, namely silicon and germanium, thus enabling the fabrication of novel microelectronic structures and materials. It will be demonstrated how such developments can translate into important practical applications leading to a wide range of technological benefits. Opportunities in ultra-shallow junction formation for silicon-on-insulator, superconducting Ge and Si, and diluted ferromagnetic Ge, along with the technical reasons for using annealing times in the ms range are discussed in the context of state-of-the-art materials processing. Whereas these examples are based on solid phase processing, the more sophisticated approach regards on working with the liquid phase at the surface of solid substrates. As a recent example the controlled surface melting of a Ge enriched silicon substrate is reported.
Evaluation of Very High Resolution Multi-Wavelength Raman Spectroscopy for In-Line Characterization of Patterned Epitaxial Si1-xGex Layers on Si(100) Wafers
Authors: Vartanian Victor , Ueda Takeshi , Ishigaki Toshikazu , Kang Kitaek , Yoo Woo Sik
Published: April 2011

Micro-Raman spectroscopy is a very attractive non-destructive in-line technique for characterizing stress/strain of the crystal, as well as crystallinity and Ge content in Si1-xGex. Additionally it requires no sample preparation, provides sub-micron spatial resolution, and requires relatively short measurement time. A polychromator-based, high resolution, multi-wavelength Raman spectroscopy system was evaluated from a manufacturing perspective as a candidate for in-line stress/strain monitoring equipment. Short-term and long-term measurement repeatability and system stability were extensively evaluated using five patterned Si1-xGex/Si(100) wafers with nominal Ge content in the range of 15~35 at% (in 5 at% increments). Three major spectral lines (457.9, 488.0 and 514.5 nm) from a multi-wavelength Ar ion laser were used as the excitation source. The short-term and long-term measurement repeatability was evaluated for three months. A very small range of total variation, less than 0.05cm-1, was measured under all three excitation wavelengths.
(Invited) Site-Specific and High-Spatial-Resolution Scanning Spreading Resistance Microscopy and Its Applications in Si Technology
Authors: Zhang Li , Koike Mitsuo , Takeno Shiro
Published: April 2011

Scanning spreading resistance microscopy (SSRM) is an powerful technique for 2D-carrier profiling of scaled silicon devices, with its wide dynamic range of carrier concentration and high spatial resolution. We achieved the 1-nm high spatial resolution of SSRM in carrier profiling by decreasing the contact resistance between sample and probe while measuring in a high vacuum. In this paper, we demonstrate SSRM applications to Si devices. Direct observation of (110)/(100) CMOSFETs clarified significant differences between pMOSs and nMOSs on (100)/(110) Si substrate. Furthermore, our sample-making breakthrough enables site-specific characteristics of both narrow devices and failure analysis of real SRAM devices, showing the high potential of SSRM technology for further device scaling.
Si CMOS Contacts to III-V Materials for Monolithic Integration of III-V and Si Devices
Authors: Pacella Nan Y. , Bulsara Mayank T. , Fitzgerald Eugene A.
Published: April 2011

Si CMOS-based contact metallurgies to III-V compounds will allow parallel interconnection of Si CMOS and III-V devices and promote monolithic integration. In this study, we report the use of nickel silicides to contact n++ GaAs encapsulated with n++ Si. The structure and electrical properties of contacts with varying reaction depths is correlated. Specific contact resistivities lower than 5e-7 ohm-cm2 are measured on NiSi/Si/GaAs structures.
(Invited) Vanadium Oxide as a Memory Material
Authors: Radu Iuliana P. , Martens Koen , Mertens Sofie , Adelmann Cristoph , Shi Xiaoping , Tielens Hilde , Schaekers Marc , Pourtois Geoffrey , Van Elshocht Sven , De Gendt Stefan , Heyns Marc , Kittl Jorge A.
Published: April 2011

In the framework of Resistive RAM we are investigating if the metal to insulator transition in vanadium dioxide can be used for memory applications. We investigate vanadium dioxide production by low pressure oxidation of metallic vanadium and demonstrate samples with 4 orders of magnitude transition in resistivity. We show that the relaxation times to the coexistence state are compatible with non-volatile memory requirements being longer than 10 years. We also investigate how metal doping influences the transition temperature.
Material and Electrical Properties of Hole-Trapping Memory Capacitors Composed of nc-ITO Embedded ZrHfO High-k Films
Authors: Lin Chen-Han , Kuo Yue
Published: April 2011

The material and electrical properties of MOS memory capacitors composed of single- and dual-layer nc-ITO embedded ZrHfO high-k films have been investigated. The dual-layer nc-ITO embedded sample shows a higher charge trapping density than the single-layer nc-ITO embedded sample does. The formation of an interface layer at the nc-ITO and ZrHfO contact region is confirmed by XPS analysis. The memory function is mainly based on trapping holes at both the bulk and interface of the nc-ITO site. The frequency-dependent C-V and G-V results indicate that parts of holes are loosely trapped at the nc-ITO/ZrHfO interfaces. The hole-trapping and -detrapping phenomena are also confirmed from the J-V measurements.
Enhanced Data Retention Characteristic on SOHOS-Type Nonvolatile Flash Memory with CF4-Plasma-Induced Deep Electron Trap Level
Authors: Hsieh Chih Ren , Chen Yung-Yu , Lin Wen-Sin , Lin Gray , Lou Jen-Chung
Published: April 2011

The improved data retention characteristics of Polysilicon-oxide-hafnium oxide-oxide-silicon (SOHOS) type nonvolatile memory were obtained by post-HfOB2B trapping layer deposition tetrafluoromethane (CFB4B) plasma treatment. The memory characteristics such as program/erase speed, retention and endurance were studied comprehensively. That fluorine atoms incorporated into Hf-based high-k material eliminate shallow trap defect level effectively and remain deeper trap level. Although the shallow traps of the HfOF trapping layer SOHOS memory have passivated, it doesn't deteriorate the program/erase speed obviously and retention characteristic was then improved because of deeper electron storage level. The results clearly indicate CFB4B plasma treatment-induced deep electron storage level is a feasible technology for future SOHOS-type nonvolatile flash memory application.
(Invited) Impact of Stacked AlON/SiO2 Gate Dielectrics for SiC Power Devices
Authors: Watanabe Heiji , Kirino Takashi , Uenishi Yusuke , Chanthaphan Atthawut , Yoshigoe Akitaka , Teraoka Yuden , Mitani Shuhei , Nakano Yuki , Nakamura Takashi , Hosoi Takuji , Shimura Takayoshi
Published: April 2011

We propose the use of an aluminum oxynitride (AlON) gate insulator for SiC-based MOS power devices. Although direct deposition of AlON on 4H-SiC substrate causes electrical degradation, the fabricated MOS capacitor with AlON/SiO2 stacked gate dielectric shows no flatband voltage (VFB) shift and negligible capacitance-voltage (C-V) hysteresis. Owing to the high dielectric constant of AlON, as compared to single SiO2 insulator, significant gate leakage reduction was achieved even at high-temperatures, especially in high electric field condition. Moreover, in order to improve electrical properties of thermally grown SiO2/SiC interfaces, the impact of a combination treatment of nitrogen plasma exposure and forming gas annealing (FGA) was investigated. We found that channel mobility enhancement of SiC-MOSFETs was consistent with the reduction in interface state density (Dit) depending on the process conditions of the combination treatment, and obtained 50% mobility enhancement, while maintaining low gate leakage current.
(Invited) MEMS on LSI
Authors: Esashi Masayoshi , Tanaka Shuji
Published: April 2011

Three kinds of MEMS on LSI are described. Lamb wave resonators are fabricated for multi-frequency oscillators by surface micromaching on a LSI wafer. Multi-band filters are formed by a MEMS process after bonding a Si wafer to a LSI wafer. SAW filters are made by bonding a MEMS wafer to a LSI wafer. Wafer level packaging techniques are developed to encapsulate the MEMS on LSI. Open collaboration as shared LSI, prototyping facility and hands-on access fab. are discussed to reduce a cost and a risk in the development of the MEMS on LSI.
(Invited) CMOS MEMS Integration
Authors: Fedder Gary K.
Published: April 2011

The "More than Moore" trend in the microelectronics industry is driving a renewed interest in mixed-physics CMOS MEMS integration. Integration becomes a necessity for multi-component microsystems, where interconnect issues are significant. Integration also drives down parasitic capacitances and provides opportunities for ultra-low-power microsystems. Several monolithic approaches exist that create MEMS from the layers in the back-end-of-line CMOS stack or by adding materials on top of the CMOS stack. These processes have been used to create a variety of microsystems including inertial sensors, RF tunable capacitors and probe manipulators. Process extensions include addition of sensitizing polymers by inkjet for gravimetric gas chemical sensors, etch of intermediate metal layers followed by polymers fill for capacitive chemical sensors, and plasma polymer deposition on micro-meshes to form diaphragms. The chip-stacking approach to integration is still in its infancy but benefits from the rapid maturation of technologies for chip thinning and for through-silicon vias.
The Effect of Self Assembled Monolayer(SAM) on the Back Interface of a-IGZO TFT
Authors: Cho Seung-Hwan , Lee Yong-Uk , Lee Jeong-Soo , Jo Kang-Moon , Kim Do-Hwan , Kim Bo-Sung , Han Min-Koo
Published: April 2011

We have investigated the effects of Self Assembled Monolayer(SAM) on the back interface of amorphous indium-gallium-zinc oxide(a-IGZO) TFT. In order to investigate chemical induced changes of a-IGZO TFT by solvent molecules in the process of solution passivation, we have employed widely used solution based PMMA passivation. Von shift in TFT with SAM is small(from -0.8V to -6.6V) while the TFT without any SAM exhibited large negative turn-on voltage(Von(10pA)) shift(from -2.0V to -12.6V). It has been reported that gaseous molecules are absorbed or desorbed on the oxide semiconductor and they change electric properties of oxide semiconductor TFT. Our experimental results show that SAM successfully blocked moisture from ambient environments and suppressed the exposure to solvents caused by solution process.