bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization Of Technology And Design Parameters Of IGBT Using TWB
Authors: Fatemizadehl B. , Granik Y. 
Published: April 2011

AbstractThis paper presents a methodology to optimize the design of different types of IGBT using TWB (TMA WorkBench). Using RSM (Response Surface Modeling) and DOE (Design of Experiment) in TWB we have developed a methodology, which can be applied to explore the impact of design modifications on the speed improvement and study the trade-off between speed, on-resistance, and breakdown voltage of IGBT. This method is a rapid and cost-effective approach for studying design alternatives. Two-dimensional simulations were used to determine the influence of technology and design parameter on device characteristics.
Influence Of Silicon Defects On The Electrical Behavior Of Semiconductor Power Devices
Authors: Schulze H.-J. , Kolbesen B.O. 
Published: April 2011

AbstractSince power devices require a thick electrically active n-type silicon layer with high resistivity and a large area, their electrical characteristics are extremely sensitive to contamination. If heavy metals diffuse into the silicon wafers during the high-temperature steps, an uncontrolled increase in the leakage current and the on-state voltage can be observed. Furthermore, current filamentation and instabilities of the electrical data can occur. It turned out that the optimization of the cleaning processes, high-temperature steps and gettering treatments alone is not sufficient to avoid such effects. It is also important to avoid silicon crystal defects by proper processing. A dramatic increase in the leakage current was correlated with the appearance of silicon defects decorated with heavy metals. As a consequence of the low doping level of the n-base, the blocking voltage and the failure rate due to cosmic radiation are sensitive to contaminating atoms acting as donors.
Thermo-Mechanical Simulation Of A Multichip Press-Packed Igbt
Authors: Pirondi A. , Nicoletto G. , Cova P. , Pasqualetti M. , Portesine M. , Zani P. E. 
Published: April 2011

AbstractThe reliability of press-packed integrated gate bipolar transistors (IGBT) depends on satisfactory contact conditions applied at assembly stage and mantained throughout the service life. The objective of this work is the simulation of the thermo-structural behavior of a multichip IGBT during initial assembly and subsequent uniform thermal cycling using the Finite Element method. A detailed axisymmetric FE model of the 3D-device is developed to assess multi-zone contact conditions. Elastic-plastic material behavior and Coulombian friction on contact surfaces are prescribed. The role of dimensional tolerances on contact conditions is discussed. The thermal cycling associated to accelerated testing is then introduced to determine the contact pressure evolution as well as local stick/slip conditions. The device sensitivity to potential damage initiation due to thermo-mechanical fatigue and/or fretting is addressed.
High Resistivity Oxygen-Doped AlGaAs For Power Devices
Authors: Sasajima Yuichj , Fukuhara Noboru , Hata Masahiko , Maeda Takayoshi , Okushi Hideyo 
Published: April 2011

AbstractWe have succeeded in making high resistive AlxGa1−xAs by oxygen doping (AlxGa1−xAs:O) and applying them to buffer layer for power metal-semiconductor field effect transistor (MESFET). Samples of Al0.3Ga0.7As:O were prepared by metalorganic vapor phase epitaxy (MOVPE). Oxygen-related levels in A10.3Ga0.7As:O were investigated by applying isothermal capacitance transient spectroscopy (107S) to MIS (Al/Al0.3Ga0.7As:O/n-GaAs) diodes. A breakdown voltage and a two terminal gate breakdown voltage of the MESFET with the Al0.3Ga0.7As:O buffer layer became higher as increasing in the intensity of oxygen related peak in the ICTS spectra. These results indicate that the electrically active oxygen in the Al1−xGa1−xAs:O is an important factor for the device characteristics.
Localized Lifetime Control In Silicon Bipolar Power Devices By Voids Induced By He Ion Implantation
Authors: Saggio M. , Raineri V. , Frisina F. , Rimini E. 
Published: April 2011

AbstractLocalized lifetime control in silicon bipolar devices is presented and discussed. It was achieved by formation of a void layer by He ion implantation. The void formation is reviewed and the void properties are described and carefully considered. Simulations demonstrate the advantages of using localized lifetime control, while the innovative method is applied to fabrication of high speed Insulated Gate Bipolar Transistors.
Power Limitation Due To Premature Breakdown In Algan/Gan Hfets
Authors: Gradinaru G. , Kao N. C. , Yang J. , Chen Q. , Khan M. A. , Sudarshan T. S. 
Published: April 2011

AbstractA systematic investigation of high field prebreakdown and breakdown phenomena of AlGaN/GaN Heterojunction Field Effect Transistors (HFETs) is presented. The breakdown process was studied as a function of various parameters such as applied electric field, material layer structure, semiconductor surface conditions, ambient dielectric, and test conditions. Experimental evidence of a breakdown mechanism, distinct from the bulk/subsurface breakdown, namely on-surface breakdown or surface flashover is presented. A practical, unambiguous way of identifying device failure by surface flashover is proposed. Surface flashover between gate and drain contact edges is proposed as the main mechanism initiating premature breakdown in these devices leading to a significant reduction of their power capability.
Phase and Interface Stability Issues in Chalcopyrite-Based Thin Film Solar Cells
Authors: Guillemoles Jean-Francois , Haalboom Thomas , Gödecke Tilo , Ernst Frank , Cahen David 
Published: April 2011

AbstractHow stable are Cu(In,Ga)Se2 solar cells? CuInSe2 is known also as an ionic Cu conductor and the Cu-In-Se system has a rich phase diagram. Two stability-related problems are treated from a thermodynamic point of view: -a- Cu migration, -b- phase segregation. We show how Cu migration imparts self-stabilization on the system. Based on recently reported results on the room temperature phase diagram of CuInSe2, we explain why an overlayer of an ordered vacancy compound (OVC) is not to be expected to appear as a separate phase, even though the surface composition corresponds to that of the I-III3V5 OVC compound.
Na Impurity Chemistry in Photovoltaic Cigs thin-Films: An Investigation with Photo- and Auger Electron Spectroscopies
Authors: Niles D. W. , Ramanathan K. , Granata J. , Hasoon F. , Noufi R. , Tielsch B. J. , Fulghum J. E. 
Published: April 2011

AbstractThe incorporation of Na into Cu(Inl-xGax)Se2 thin-films is known to lead to an improvement in device performance. The authors use X-ray photoelectron and Auger electron spectroscopies to determine the chemical nature of Na in Cu(Inl-xGax)Se2 thin-films. The Na concentration is determined to be ∼ 0.1 atomic percent in the bulk of Cu(In1-xGax)Se2 thin-films. The Na is chemically bonded to Se. The authors propose a model invoking the replacement of column III elements by Na during the growth of Cu(Inl-xGax)Se2 thin-films. These Nain and NaGa defects act as acceptor states to increase the p-type conductivity of Cu(In1-xGax)Se2 thin-films.
Ultra Thin Indium Tin Oxide Films On Various Substrates By Pulsed Laser Deposition
Authors: Sun X. W. , Kim D. H. , Kwok H. S. 
Published: April 2011

AbstractIndium Tin Oxide (ITO) thin films with low resistivities of 0.1 ∼0.2 mΩ-cm were deposited on various substrates such as YSZ, glass, and ZnO buffered glass by pulsed laser deposition (PLD). The X-ray rocking curve of crystalline (200) ITO films grown on (100) YSZ had a FWHM as narrow as 0.08°. ITO films grown on ZnO (0001) buffered glass had an single (222) orientation and the X-ray rocking curve had a FWHM of 2. 1°. Ultrathin ITO films of 3.6nm were fabricated on YSZ and their electrical properties were measured from 10K-300K. ITO films fabricated on ZnO buffered glass and bare glass were characterized by Hall effect measurements as a function of temperature. The results indicate that the resistivity of ITO films grown by PLD does not depend on the orientation or the structure of the thin film. The resistivity is dominated by impurity scattering in the range of 10K-300K. We show that ZnO/glass is a good alternative to bare glass for producing commercial ITO films.
The Characterization Of Chemical Bath Deposited Cds On Single Crystal InP Substrates
Authors: Riker G. M. , Al-Jassim M. M. , Hasoon F. S. 
Published: April 2011

AbstractWe have investigated CdS thin films as possible passivating window layers for InP. The films were deposited on single crystal InP by chemical bath deposition (CBD). The film thickness, as optically determined by ellipsometry, was varied from 500 to 840Å. The film morphology was investigated by high resolution scanning electron microscopy (SEM), whereas the film microstructure was studied by X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM). Most of the films were fine-grained polycrystalline CdS, with some deposition conditions resulting in epitaxial growth. Cross-sectional TEM examination revealed the presence of interface contaminants. The effect of such contaminants on the film morphology and microstructure was studied, and various approaches for InP surface cleaning/treatment were investigated. The epitaxial films were determined to be hexagonal on both the (111) and (100) InP substrates; however, they were heavily faulted.
Investigations of Oxidation Dependence on Type of Porous Silicon Near Room Temperature by Isothermal Microcalorimeter
Authors: Salonen J. , Lehto V-P. , Laine E. 
Published: April 2011

AbstractOxidation of porous silicon has been studied using thermal activity monitoring, i.e. isothermal microcalorimeter. It was found that, at room temperature (25 °C) the micro-calorimetric signal from the oxidation of the p+-type porous silicon (PS) reduces exponentially, while in the case of n-type PS, the signal starts to increase slowly, reaching its highest value after some hours. This kind of behaviour is typical of autocatalytic reactions. To clarify the origin of the difference, we varied the preparation parameters of the porous silicon. We determined the activation energy from the measurements near the room temperature (25–70 °C). The results of this research have been compared with the previous observations and the possible origin of the difference has been discussed.
Performances Of Porous Silicon Optical Waveguides
Authors: Araki M. , Takahashi M. , Koyama H. , Koshida N. 
Published: April 2011

AbstractTo verify the availability of a porous silicon (PS) technology for applications to photonic devices, fundamental chracteristics of PS waveguides are investigated. An edge-emitting device with an optical waveguide is fabricated by current modulation technique during anodization. The net internal loss for prepared samples is measured by varying the length of excitation beam. The experimental results show that the internal loss increases with decreasing the operation wavelength, possibly due to self-absorption and Rayleigh scattering. Besides the step-index PS waveguides, buried-type waveguides can be fabricated based on a doping modulation technique. A theoretical analysis about a bending loss is also carried out. The results of experimental and theoretical analyses suggest that a curveture radius capable of guiding lightwave can be significantly minimized, owing to a difinitely different refractive indedices between the core and cladding region.
Controllability And Homogeneity Of Optical Properties Of Thin Porous Silicon Films
Authors: Uehara S. , Kubo T. , Ogata S. , Sato T. , Hosono J. , Matsubara T. 
Published: April 2011

AbstractReflection spectroscopy was applied to evaluate the optical homogeneity and the refractive index of thin porous silicon (PS) layer. Variation in PS layer optical thickness was evaluated by measuring and mapping the reflectance over the surface area. For the circular anodization area of 17 mm diameter, the measured variation was less than 5 % on an area of 11 mm diameter. The anodization electrode position was found to have little influence on the homogeneity. A method to derive refractive index from a reflection spectrum is studied. The wavelength dependence of PS index measured by the method showed fair coincidence with the calculation based on effective medium approximation. In the two layer PS formation, optical thickness was found to change whether high porosity or low porosity layer is formed first.
Blue, Yellow-Green and Red Simultaneous Emission from SiO2 Matrices Co-Implanted with Si and C
Authors: López M. , Garrido B. , Bonafos C. , González-Varona O. , Pérez-Rodríguez A. , Rodríguez R. , Ruterana P. , Morante J. .R. 
Published: April 2011

AbstractDual Si+C implantations at high doses (3×1017 cm−2) were performed in thermal SiO2 layers. The C implantation energy was fixed at 60 keV while the Si ones were performed at different energies (150 keV and 60 keV) with the aim of synthetizing carbon rich luminescent centers. Annealings up to 1100 °C were performed in an inert N2 atmosphere either for short times in a rapid thermal processing furnace and up to two hours in a conventional furnace. Evidence of the formation of silicon and carbon-rich clusters was provided by XPS, SIMS, Raman and TEM experiments. Photoluminescence experiments under blue and ultraviolet excitations showed intense emission bands peaking at 1.5–1.7 eV (red), 2.20 eV (yellowgreen) and 2.75 eV (blue). The relative intensity and spectral shape of the emission bands was found to depend strongly upon implantation and annealing conditions and offered the possibility of tuning the desired dominant emission wavelength. The possible formation of SiC clusters and even SiC crystallites at the SiO2/Si interface could explain the origin of the highly intense blue emission band found for these samples.
Control of Sizes and Optical Emission of Sige Quantum Dots Prepared on Ordered Mesoporous Silica Coated Si Wafer
Authors: Tang Y. S. , Cai S. , Wang D. , Jin G. , Duan J. , Wang K. L. , Soyez H. M. , Dunn B. S. 
Published: April 2011

AbstractA new way of preparing wafer sized SiGe and Ge quantum dots at extremely low cost is presented. The results show that two different controlled nanometer sizes of the quantum dots can be formed simultaneously into two layers on the same wafer with good dot size uniformity. Our initial experiments on SiGe and Ge system suggest that it is possible to squeeze the SiGe dots for much improved optical emission. The advantages of this dot preparation method are its fully compatibility with the Sitechnology, its simplicity in dot preparation and extremely low cost.
Luminescent Amorphous Silicon Layers
Authors: Allan G. , Delerue C. , Lannoo M. 
Published: April 2011

AbstractThe electronic structure of amorphous silicon layers has been calculated within the empirical tight binding approximation using the Wooten-Winer-Weaire atomic structure model. We predict an important blue shift due to the confinement for layer thickness below 3 nm and we compare with crystalline silicon layers. The radiative recombination rate is enhanced by the disorder and the confinement but remains quite small. The comparison of our results with experimental results shows that the density of defects and localized states in the studied samples must be quite small.
Effect Of High Concentration Of Defect States At PS/c-Si Heterointerface On Transport Properties Of Al/PS/c-Si Photodiode Structures
Authors: Balagurov L. A. , Orlov A. F. , Petrova E. A. , Yarkin D. G. , Andryushin S. Ya. 
Published: April 2011

AbstractCurrent-voltage characteristics, photosensitivity, frequency dependence of impedance, and electron beam induced current were measured for Al/porous silicon/c-Si structures with porous silicon (PS) layers of 60 and 80% porosity. Al/PS/c-Si structures have photosensitivity spectra typical for Al/c-Si structures. The sign of open circuit voltage changes in these structures when the wavelength becomes less than approximately 0.4 μm. It was shown that photosensitivity of Al/PS/c-Si structures and impedance dependence on the frequency, reverse bias and thickness of PS layer are completely determined by the PS layer of high resistivity and by the space charge region in c-Si substrate on PS/c-Si heterojunction. The annealing at above 100° C leads to a decrease of the forward current at a small bias. The photosensitivity of annealed structures reaches 10 A/W for some of the structures. The experimental results lead to inevitable conclusion about opposite band bending from the two sides of the heterojunction which is caused by high concentration of charged defects at PS/c-Si heterointerface. PS photodetectors with improved device parameter were obtained.
The Properties of Silicon Clusters in Zeolite
Authors: Muramatsu Shinya , Hirao Masahiko 
Published: April 2011

AbstractNanometer-sized silicon clusters show photoluminescence, but some technique to embed them in bulk materials is needed to enable practical device applications. Thus we calculated the properties of silicon clusters in zeolite, whose framework constitutes cages as large as the clusters. We chose the hydrogenated silicon cluster Si10H16 embedded in dehydrated all-silica zeolite-A. We first performed molecular mechanics simulation to obtain a thermodynamically stable structure. The cluster was located near the center of the cage. Then we calculated the electronic structure and optical properties for this stable structure by density functional method. The absorption spectrum of this material was nearly equal to the superposition of the spectra of Si10H16 and zeolite-A, which indicates that the properties of silicon clusters are retained even in zeolite cages. These results suggest that silicon clusters in zeolite may have the potential to be used as optoelectronic materials.
Porous Silicon as a Sacrificial Material for Micromachining of Silicon Optical Platforms
Authors: Guendouz M. , Joubert P. , Pedrono N. , Rouzic J. Le 
Published: April 2011

AbstractPorous silicon obtained by the anodization of heavily doped n+-type silicon wafers was used as a sacrificial layer to micromachine silicon platforms. The effect of experimental parameters, such as the nature of the masking layer, current density and anodization time, on the geometry of the porous Si formed in patterned substrate is shown. Advantages of this method on the orientation-dependent chemical etching (ODCE), which is classically used for optical fiber alignment, are discussed.
Strain Evaluation of GaAs Layers Grown on Ultrahigh-Pressure-Annealed Strain-Free GaAs-On-Si Structures
Authors: Jimbo Takehito , Ishiwara Hiroshi 
Published: April 2011

AbstractIn order to form strain-free GaAs films on Si substrates, GaAs-on-Si structures have been formed by molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD) and subsequently annealed under ultrahigh pressure at 2 GPa. The samples were then reannealed at atmospheric pressure in order to investigate the regeneration effect of strain in the GaAs films. It was found from X-ray diffraction (XRD) analysis and photoluminescence (PL) measurement that in the reannealed samples the strain near the surface of GaAs film was smaller than that near the interface with Si. Finally, additional GaAs layers were grown using MBE on both as-grown and strain-free GaAs-on-Si structures and it was found that the residual strain in the GaAs layer on strain-free GaAs-on-Si structure was smaller than in the as-grown case.
Progress on 850 nm Flip Chip Bondable VCSEL for Optical Interconnects
Authors: Cunningham J. E. , Jan W. Y. , Goossen K. W. , Krishnamoorthy A. , Walker J. A. , Tseng B. , Giaritta G. , Lothian J. , Kropf R. , Brenner I. , Sciortino P. , Chu G. , Leibenguth R. 
Published: April 2011

AbstractWe report here efforts to advance 850 nm VCSELs designed specifically for integration to Si- CMOS. Our VCSEL design is based on an oxidized current aperture and oxidized top mirror with the intent that the device operate as a bottom emitter after integration. Our design also employs intercavity contacts and the first non-alloyed buried contact have been realized. The devices produce resonantly enhanced light emission with record output of 70 μW/st.rad.
Electro-Optics of Unilamellar Vesicles
Authors: Asgharian N. , Meline R. L. , Schelly Z. A. 
Published: April 2011

AbstractElectric field-induced transient birefringence and light scattering are reported for aqueous suspensions of synthetic unilamellar bilayer vesicles, prepared from the lipid dioleoylphosphatidylcholine (DOPC). The multiexponential birefringence relaxations observed on the microsecond and millisecond timescales are interpreted in terms of elongation and reorientation of induced dipolar vesicles, their linear chain formation, and electrofusion (and possibly electroporation) of the vesicles. Above certain threshold values of vesicle concentration, field-induced light scattering occurs concomitant with the birefringence. The corresponding transient signals corroborate the linear chain formation and subsequent fusion of the induced dipolar vesicles.
Structural Studies on Equimolar Suspensions of Palmitic Acid and 1-Lyso-Palmitoyl-Phosphatidylcholine
Authors: Lemmich J. , Richter F. , Callisen T. H. 
Published: April 2011

AbstractAn equimolar mixture of palmitic acid (PA) and 1-lyso-palmitoyl-phosphatidylcholine (Lyso-PPC) has been studied by time-resolved small angle and wide angle X-ray scattering during temperature cycles between room temperature and 53.5 °C. In addition to the X-ray experiments, differential scanning calorimetry (DSC) with a similar temperature vs. time course was performed. At room temperature we observe a coexistence of two different lamellar phases. Our results indicate that in one of these lamellar phases, Lyso-PPC and PA associate in lamellar structures resembling di-palmitoyl-phosphatidylcholine (DPPC) bilayers, whereas the other phase is an interdigitated lamellar phase, where the acyl chains of both Lyso-PPC and PA extend across the entire hydrocarbon width of the bilayer. Upon heating, the latter phase disappears at 42 °C, corresponding to the chain-melting temperature for DPPC bilayers. At a higher temperature the remaining lamellar phase undergoes a phase transition into an isotropic micellar phase. In the cooling scans a particular slow kinetics of the regeneration of the two lamellar phases is observed. Our experiments provide new information about this system where only the DPPC-like mesophase has been reported before.
A Phenomenological Model of the LS2 Ion Channel
Authors: Zhong Qingfeng , Newns Dennis M. , Klein Michael L. 
Published: April 2011

AbstractA molecular dynamics simulation has been performed on a synthetic membrane-spanning ion channel, consisting of four α-helical peptides, each of which is composed of the sequence Ac-(LSLLLSL)3-CONH2. In the present simulation, the channel was initially assembled dynamically as a parallel bundle in the octane portion of a phase separated water/octane system, which provided a membrane-mimetic environment, without imposing any structural constraints. After more than one nanosecond, the four helices were found to adopt an associated dimer state with two-fold symmetry, which after a further 3 ns evolved to a coiled-coil tetrameric structure with a left-handed twist. Based on the simulation, we proposed a phenomenological model to describe the two-states of the channel.