bluuebunny/crossref_metadata_2025_split huggingface dataset:
Osteocompatibility of Photopolymerizable Anhydride Networks
Authors: Shastri V.R. , Marini R.P. , Padera R.F. , Kirchain S. , Tarcha P. , Langer R. 
Published: April 2011

AbstractA new family of polyanhydrides has been developed which can be cured photochemically to produce degradable networks. These degradable polyanhydride networks can be useful in orthopedics as bone cements and for drug delivery. This system, which is a semi-interpenetrating network (semi-IPN), has been evaluated for tissue compatibility in subcutaneous sites in rats and shown to undergo degradation by surface erosion. It was observed that the inflammatory response to the semi-IPN implants was minimal at both short (3, 6 weeks) and long (28 weeks) time points and the fibrotic response was largely absent throughout the duration of this study. Furthermore, excellent tissue infiltration and integration with good neovascularization was observed around the semi-IPN implants. The osteocompatibility and osteoconductive properties of this system have been evaluated in a longitudinal defect model in the articular surface of the distal femur in adult rabbits. This study compared the semi-IPN implants to control groups consisting of unfilled defects and PLA implants. Histological evaluation (H&E and Trichrome Masson staining) of the implant site revealed that the semi-IPN implant is osteocompatible and well tolerated by the surrounding cancellous bone and marrow constituents. The tissue reaction to the implant is characterized by an ingrowth of vascularized connective tissue and a mild fibrous capsule. Furthermore, partial to complete closure of the articular surface with fibrocartilage and fibrous tissue was observed in all experimental animals containing the semi-IPN polymer implants.
Moment-based Modeling of Extended Defects for Simulation of TED: What Level of Complexity is Necessary?
Authors: Gencer Alp H. , Dunham Scott T. 
Published: April 2011

ABSTRACTAccurate modeling of extended defect kinetics is of primary importance for predictive modeling of transient enhanced diffusion (TED). Our previously developed model accurately accounts for extended defects and can be used predictively for TED. Using some experimental knowledge about the distribution of the extended defect population we can simplify our model. We demonstrate that reducing the number of solution variables by one doesn't affect the predictive capabilities of the model for extended defect kinetics and TED. However, some caution has to be used when applying the same principles to modeling of dopant deactivation.
Computer Simulation of Channeling Profile Analysis of Implantation Damage
Authors: Posselt Matthias 
Published: April 2011

ABSTRACTChanneling profile analysis is simulated using the dynamic binary collision code Crystal- TRIM. A good agreement between theoretical and experimental data is found for silicon targets which were predamaged by Si+ ions of different energies and analyzed by 140 keV B+ ions. For each example the depth profile of the defects relevant for the dechanneling of the analyzing ions is given. An estimate of the annealing of such defects is obtained by comparison of results for as-implanted and annealed samples.
Surface Science Studies of NF3 Plasma and Ion Beam Interactions with Silicon
Authors: Little T. W. , Briggs S. C. , Ohuchi F. S. 
Published: April 2011

ABSTRACTThe interaction of nitrogen trifluoride (NF3) with silicon (Si) surfaces has been investigated by x-ray photoelectron spectroscopy (XPS). Si (100) surfaces were subjected to plasmas created by NF3 gas mixtures and ion bombardment from NF3-generated ion beams as a means of approximating the ion component of plasma processing under controlled conditions. NF 3 plasma processing has lead to the appearance of an interesting high binding energy component in F 1s XPS spectra. Investigation into the mechanism responsible for the high binding energy component suggests that the unusual component is directly influenced by diluent gas ions in the gas mixtures. It is postulated that the high binding energy component is the result of neutral fluorine incorporated in the Si lattice as a result of an ion damage mechanism.
On the «A Symmetrical» Behavior of Transient Enhanced Diffusion in Pre-Amorphised SI Wafers
Authors: Alquier D. , Cowern N. E. B. , Pichler P. , Armand C. , Martinez A. , Mathiot D. , Omri M. , Claverie A. 
Published: April 2011

ABSTRACTWe have studied by SIMS the diffusion of boron in Ge-preamorphised silicon over a range of anneal temperatures and times, focusing on the influence of the depth of the boron profile relative to the crystalline-amorphous (c/a) interface. It is shown that, for all durations, transient enhanced diffusion (TED) occurs on both sides of the c/a interface. For short annealing times, the amplitude of TED varies by about two orders of magnitude between the surface and the end-of-range (EOR) defect band, formed just below the original c/a interface. We propose a model in which TED arises from the coupling between a Si-interstitial supersaturated « box », the EOR defect region, whose supersaturation decreases with time as the EOR defects grow, and a surface whose recombination efficiency is close to that of a perfect sink. The model successfully describes the different behavior of deep and shallow boron profiles, without requiring the existence of a diffusion barrier.
In Situ Deep Level Transient Spectroscopy of Defect Evolution in Silicon Following Ion Implantation at 80 K
Authors: Cho C. R. , Brown R. A. , Kononchuk O. , Yarykin N. , Rozgonyi G. , Zuhr R. 
Published: April 2011

ABSTRACTThe evolution of defects in Czochralski and epitaxial p- and n-type silicon wafers following irradiation with He. Si or Ge ions at 80 K has been investigated by in situ deep level transient spectroscopy (DLTS). Defect annealing and formation reactions have been observed over the temperature range 80–350 K. In p-type silicon, new species-dependent levels are observed immediately after implantation, but these levels anneal out at or below room temperature. The wellknown divacancy and interstitial defects, usually reported after room temperature implantation, are revealed in the DLTS spectra only upon annealing at 160–200 K. In n-type silicon, vacancy-oxygen pairs are observed immediately after implantation. However, vacancy-related defects continue to form over a broad temperature range in samples implanted with Si or Ge. These observations are consistent with a model whereby vacancies and interstitials are released from defect clusters at temperatures >200 K to form divacancies and other defect pairs which are stable at room temperature.
Ge-Quantum Dots on SI(001) Tailored by Carbon Predeposition
Authors: Leifeld O. , Grützmacher D. , Müller B. , Kern K. 
Published: April 2011

AbstractThe morphology of Si(001) after carbon deposition of 0.05 to 0.11 monolayers (ML) was investigated in situ by ultrahigh vacuum scanning tunneling microscopy (UHV-STM). The carbon induces a c(4×4)-reconstruction of the surface. In addition, carbon increases the surface roughness compared to clean Si(001) (2×1). In a second step, the influence of the carbon induced restructuring on Ge-island nucleation was investigated. The 3D-growth sets in at considerably lower Ge coverage compared to the clean Si(001) (2×1) surface. This leads to a high density of small though irregularly shaped dots, consisting of stepped terraces, already at 2.5 ML Ge. Increasing the Ge-coverage beyond the critical thickness for facet formation, the dots show { 105 }- facets well known from Ge-clusters on bare Si(001) (2×1). However, they are flat on top with a (001)-facet showing the typical buckled Ge rows and missing dimers. This indicates that the compressive strain is not fully relaxed in these hut clusters.
Epitaxial Growth And Electronic Characterization Of Carboncontaining Silicon-Based Heterostructures
Authors: Hoyt J. L. , Mitchell T. O. , Rim K. , Singh D. V. , Gibbons J. F. 
Published: April 2011

AbstractEpitaxial Si1-x-yGexCy and Si1-yCy layers grown on Si are opening up new possibilities for bandstructure engineering of electronic devices. Thin Si1-yCy layers containing a few atomic percent substitutional carbon, grown on Si substrates, experience biaxial tensile strain, which produces a conduction band energy splitting that is expected to be favorable for in-plane electron transport. For other applications, C may be useful as a means of compensating the compressive strain of Ge in ternary Si1-x-yGexCy alloys. Although the understanding of the electronic properties of these materials is still at an early stage, interesting trends are emerging.A key issue for synthesis of these alloys is the low equilibrium solubility of carbon in silicon. However, a number of non-equilibrium methods have been employed to grow these materials. This work focuses on the properties of Si1-yCy and Si1-x-yGexCy grown by chemical vapor deposition. There is a strong influence of the growth conditions on the fraction of the total carbon concentration which is substitutional on the silicon lattice. Using low temperatures (e.g. 550°C) and very high silane partial pressures for Si1-yCy growth, good agreement is obtained between the carbon contents determined by x-ray diffraction and secondary ion mass spectrometry, for carbon concentrations up to about 1.8 atomic percent. Metal-oxidesemiconductor capacitors fabricated on Si1-x-yGexCy and Si/Si1-yCy epitaxial layers show wellbehaved electrical characteristics. Temperature dependent capacitance-voltage analysis is used to extract the band offsets, and indicates that the conduction band energy is lowered as carbon is added to Si. Complementary to the case of strained Si1-xGex grown on Si, for which most of the energy offset is in the valence band, the band offset appears primarily in the conduction band for Si1-yCy/Si heterojunctions.
Carbon Incorporation in Si1-yCy Alloys Grown by Ultrahigh Vacuum Chemical Vapor Deposition
Authors: Mocuta A. C. , Greve D. W. 
Published: April 2011

AbstractThin heteroepitaxial Si1-yCy films have been grown on Si (100) by Ultrahigh Vacuum Chemical Vapor Deposition (UHV/CVD) using silane and methylsilane as silicon and carbon precursors. Carbon incorporation has been studied in the growth temperature range of 550°C to 650°C. The layers have been characterized using high resolution X-ray diffraction and secondary ion mass spectrometry. The total carbon content of the alloys increases linearly with the methylsilane partial pressure and a methylsilane sticking coefficient approximately 2 times higher than that of silane was extracted. Layers with up to 1.34 % substitutional carbon have been obtained at the lowest growth temperature. Fully substitutional carbon can be obtained for levels up to 0.65%. Variations of the growth rate with temperature and carbon content are also discussed.
Investigation of Plastic Relaxation in Si1-xGex/Si Deposited by Selective Epitaxy
Authors: Wickenhäuser S. , Vescan L. 
Published: April 2011

AbstractSi1-xGex/Si heterostructures with different layer thicknesses grown by selective LPCVD epitaxy at different growth temperatures were investigated with regard to plastic relaxation. AFM and optical micrograph were performed to determine the dislocation density. From the analysis of the misfit dislocations at the initial stage of relaxation of the samples grown at 700°C it was possible to determine the nucleation site density and an activation energy of 2.8 eV for the heterogeneous nucleation of misfit dislocations. While the critical thickness hc for a given Ge content increases with decreasing growth temperature between 800°C-680°C one observes a dramatic decay of hc, at a growth temperature of 625°C. For growth at 625°C it was found that this activation barrier is drastically decreased.
Mosaic Crystal Tilts and Their Relationship to Dislocation Structure, Surface Roughness and Growth Conditions in Relaxed SiGe Layers
Authors: Wallis D. J. , Robbins D. J. , Pidduck A. J. , Williams G. M. , Churchill A. , Newey J. 
Published: April 2011

AbstractIn recent years the growth of virtual substrates using graded SiGe buffer layers has shown great promise for the development of high performance devices. Whilst significant progress has been made in the control of growth conditions to produce low threading dislocation densities of the order suitable for commercial exploitation, several technological problems still have to be overcome. An example of such problems are cosmetic surface defects such as pits and the cross hatched surface roughness associated with mosaic crystal tilts. The work described here utilises a variety of techniques, including X-ray diffraction reciprocal space maps, TEM, AFM and SIMS to provide a comparison between several SiGe virtual substrates grown using low pressure-CVD at high (≈800°C) and low (≈6000°C) temperatures, and at different grade rates (5–50% Ge μm−1). The growth conditions are seen to have a strong effect on the crystal tilts present in the layers with the low temperature layers showing a much larger spread of mosaic tilts. The origin of these tilts is seen to occur during the early stages of the relaxation process irrespective of growth temperature and at similar Ge fractions for all samples. TEM imaging close to the initial growth interface shows that dislocation pileups occur in this region and also suggest that the pileups have a characteristic spacing of 1–2μm. A similar characteristic length scale is also observed in the surface roughness by AFM, the form of which is seen to depend upon the growth conditions.
Characterization of Single-Crystal 3C-SIC Epitaxial Layers on SI Substrates
Authors: Saddow S. E. , Okhusyen M. E. , Mazzola M. S. , Dudley M. , Huang X. R. , Huang W. , Su H. , Shamsuzzoha M. , Lo Y. H. 
Published: April 2011

AbstractIn this paper we discuss the growth and characterization of 3C-SiC epitaxial layers grown on both a Si substrate as well as on a novel substrate. The growth uses a typical three step process. First an etch of the Si surface is performed, second the surface of the Si is carbonized and third 3C-SiC is grown on the carbonized surface. Several characterization techniques were used to verify the quality of the 3C-SiC film. Microscopy was used to investigate the surface morphology, X-ray and electron diffraction were used to determine crystal structure, cross section TEM was used to verify crystal structure and highlight twinning, and x-ray topography was used to measure the strain fields induced in Si substrate at the 3C-SiC/Si interface.
Photonic Bandgap Formation by Wafer Bonding and Delamination
Authors: Wada Kazumi , Chen Thomas , Michel Jurgen , Kimerling Lionel C. , Aga Hiroshi , Mitani Kiyoshi , Abe Takao , Suezawa Masashi 
Published: April 2011

AbstractA new approach for one-dimensional photonic bandgap formation is introduced. The method consists of wafer bonding and delamination, which is capable of stacking single crystalline semiconductor layers on non-crystalline insulator layers. Si and SiO2 layers with sub-wavelength periodicity are successfully stacked to form photonic crystals consisting of 3 pairs without a defect layer and of 4.5 pairs with a defect layer. The transmittance spectra are well reproduced by transfer matrix calculations. This clearly verifies the potential of the wafer bonding and delamination method.
A Model of Wafer Bonding by Elastic Accommodation
Authors: YU H. H. , SUO Z. 
Published: April 2011

AbstractTwo clean and flat wafers can adhere spontaneously. The technique has recently led to novel electronic and optoelectronic devices. The adhesion arises from short-range interatomic forces between wafer surfaces, which can be represented by a reduction in surface energy associated with the transformation of two surfaces into one interface. The wafers, however, are seldom perfectly flat; the misfit has to be accommodated by elastic distortion, plastic deformation, or mass transport. We model elastic accommodation in this paper. The distortion causes the wafers to gain elastic energy. If the surface energy reduction dominates over the elastic energy gain, the wafers will bond. We solve the three dimensional elastic field in the misfit wafers analytically. The conditions for bonding are established, and practical implications discussed.
Integration of Silicon and Diamond, Aluminum Nitride or Aluminum Oxide for Electronic Materials
Authors: Bengtsson Stefan , Bergh Mats , Söderbärg Anders , Edholm Bengt , Olsson Jörgen , Ericsson Per , Tiensuu Stefan 
Published: April 2011

AbstractMaterial integration for the formation of advanced silicon-on-insulator materials by wafer bonding and etch-back will be discussed. Wafer bonding allows combining materials that may not be possible to grow on top of each other by any other technique. In our experiments, polycrystalline diamond, aluminum nitride or aluminum oxide films with thickness of 0.1-5 µm were deposited on silicon wafers. Bonding experiments were made with these films to bare silicon wafers with the goal of forming silicon-on-insulator structures with buried films of polycrystalline diamond, aluminum nitride or aluminum oxide. These silicon-on-insulator structures were aimed to address self-heating effects in conventional silicon-on-insulator materials with buried layers of silicon dioxide. The surfaces of the deposited diamond films were, by order of magnitude, too rough to allow direct bonding to a silicon wafer. In contrast the deposited aluminum nitride and aluminum oxide films did allow direct bonding to silicon. Bonding of the diamond surface to silicon was instead made through a deposited and polished layer of polycrystalline silicon on top of the diamond. In the case of the aluminum nitride electrostatic bonding was also demonstrated. Further, the compatibility of these insulators to silicon process technology was investigated.
Dynamics of Wet Oxidation of High-Al-Content III-V Materials
Authors: Ashby Carol I. H. 
Published: April 2011

AbstractOxidation of layers of high-Al-content III-V materials by water vapor has become the enabling process for high-efficiency vertical cavity surface emitting lasers (VCSELs) and has potential applications for reducing substrate current leakage in GaAs-on-insulator (GOI) MESFETs. Because of the established importance of wet oxidation in optoelectronic devices and its potential applications in electronic devices, it has become increasingly important to understand the mechanism of wet oxidation and how it might be expected to affect both the fabrication and subsequent operation of devices that have been made using this technique. The mechanism of wet oxidation and the consequence of this mechanism for heterostructure design and ultimate device operation are discussed here.
Fermi-Level effect and junction carrier concentration effect on p-Type dopant distribution in IlI-V Compound superlattices
Authors: Chen Chang-Ho , Gösele Ulrich M. , Tan Teh Y. 
Published: April 2011

AbstractThe pronounced segregation phenomenon in the distribution of p-type dopants Zn and Be in GaAs and related III-V compound heterostructures has been explained quantitatively by treating simultaneously the processes of dopant atom diffusion, segregation, and the effect of heterojunction carrier concentrations on these two aspects. Segregation of a dopant species between two semiconductor heterostructure layers is described by a model incorporating (i) a chemical effect on the neutral species; and (ii) in addition, a Fermi-level effect on the ionized species. The process of Zn and Be diffusion in GaAs and related compounds is governed by the doubly-positively-charged group III element self-interstitials whose thermal equilibrium concentration and hence also the Zn and Be diffusivities exhibit also a Fermi-level dependence, i.e., in proportion to p2.A heterojunction is consisting of a space charge region with an electric field, in which the hole concentration is different from those in the bulk layers. This influences the junction region concentrations of and of Zn− or Be−, which in turn influence the distribution of the ionized acceptor atoms. The overall process involves diffusion and segregation of holes, , Zn− or Be−, and an ionized interstitial acceptor species. The junction electric field also changes with time and position.
Peak Voltage Insensitivity to Quantum Well Width in Resonant Interband Tunneling Diodes
Authors: Kitabayashi H. , Waho T. , Yamamoto Masafumi 
Published: April 2011

AbstractWe have investigated the peak voltage (Vp) in InAs/A1Sb/GaSb/A1Sb/InAs double-barrier resonant interband tunneling (DBRIT) diodes with various GaSb well widths (Lw). After eliminating the voltage drop resulting from parasitic resistance included in the measured peak voltage (Vpm), we found that the intrinsic peak voltage (Vpint) was almost insensitive to Lw and had a small, and virtually constant value (∼ 60 mV) at Lw, ranging from 10 to 30 monolayers. This insensitivity contrasts with the peak voltage of the conventional resonant tunneling diodes with intraband tunneling, which is sensitive to changes in Lw. This insensitivity can be explained by the fact that Vpint in Sb-based BDRIT diodes is affected by the occupied states in the collector rather than by the resonance level itself in the interband tunneling process.
High Performance CuMetallized GaAs HEMTs Processing and Reliability
Authors: Feng T. , Dimoulas A. , Strifas N. , Christou A. 
Published: April 2011

AbstractAlGaAs/GaAs based high electron mobility transistors (HEMTs) with Cu/Ti metallized gates have been fabricated. Copper gates were used to achieve low gate resistance and to minimize the hydrogen induced device degradation. The DC measurement of the processed AlGaAs/GaAs HEMTs with Cu/Ti gates shows comparable performance to similar Au based GaAs HEMTs. The Cu-based HEMTs were also subjected to elevated temperature testing under 5% H2 –N2 forming gas up to 250°C and 8 hours and no degradation due to hydrogen effects was found.
Application of SiO2 Films deposited by TICS/O2 PECVD to InSb MISFET
Authors: Sugiura O. , Akiba T. , Idris I. 
Published: April 2011

AbstractWe have fabricated n-channel InSb MISFETs using SiO2 films as gate insulators. The insulator was deposited by PECVD using tetra-isocyanate-silane (TICS) and oxygen (O2) as source gases. Threshold voltage and carrier mobility at 77K were 0.5V and 4200cm2/Vs, respectively.
Optimization of Microstructure and Dislocation Dynamics in InxGa1-xP Graded Buffers Grown on GaP by Movpe
Authors: Kim A.Y. , Fitzgerald E.A. 
Published: April 2011

AbstractTo engineer high-quality InxGal-xP graded buffers on GaP substrates (InxGa1-xP/GaP), we have explored the evolution of microstructure and dislocation dynamics in these materials. We show that the primarily limiting factor in obtaining high-quality InxGa1-xP/GaP is a new defect microstructure that we call branch defects. Branch defects pin dislocations and result in dislocation pileups that cause an escalation in threading dislocation density with continued grading. The morphology of branch defects is dominated by growth temperature, which can be used to suppress the strength or density of branch defects. In the absence of branch defects, we observe nearly ideal dislocation dynamics that are controlled by the kinetics of dislocation glide. This new understanding results in two primary design rules for achieving high-quality materials: 1) control branch defects, and 2) maximize dislocation glide kinetics. Combining these design rules into optimization strategies, we develop and demonstrate processes based on single and multiple growth temperatures. With optimization, threading dislocation densities below 5 × 106 cm−2 are achieved out to x = 0.39 and a nearly steady-state relaxation process is recovered.