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Semiconductor Devices (semiconductor + device)
Selected AbstractsThe Role of Strain in New Semiconductor DevicesADVANCED ENGINEERING MATERIALS, Issue 4 2009Alex Dommann HRXRD is a very sensitive and non destructive technique to determine the strain in thin layer materials such as electron guides or the strain induces by the second order package of SOCs. In reciprocal space mapping (RSM), it is possible to separate the elastic component of the scattered intensity from the diffuse one. As a consequence, it is possible to study diffuse scattering due to defects of the crystal lattice. As an example we show also RSM's of a high-speed SiGe pMOS structure. [source] Preface: phys. stat. sol. (c) 1/8PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2004Markus C. Amann In this special issue of physica status solidi (c) we have included 10 invited papers reviewing the current state-of-the-art and the progress achieved in materials science, semiconductor theory, novel physical mechanisms and advanced device concepts in the field of nanostructured electronic and optoelectronic semiconductor devices. All of these papers were written by previous members of the Collaborative Research Centre 348 "Nanometer-Halbleiterbauelemente: Grundlagen , Konzepte , Realisierungen" (Nanometer Semiconductor Devices: Fundamentals , Concepts , Realisations), which was funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) during the period from 1991 to 2003. In these twelve years, the researchers in this programme have carried an intense activity directed towards two main objectives. First of all, Fundamentals and Concepts of nanostructure devices and their technology were explored theoretically and experimentally including the effects of low-dimensional structures on carrier transport, optical properties and spin, as well as the enabling epitaxial and nanostructure technologies such as the cleaved-edge-overgrowth technique and the self-assembled growth of quantum dots. A second field of interest was focused towards the design and development of Novel Semiconductor Devices exploiting nanostructure technology. This comprises optical detectors and memories with nanometer lateral dimensions, microwave detectors and sources up to the 300 GHz regime, innovative tunable and surface-emitting semiconductor lasers for the wavelength range 0.9 to 2 ,m, and nitride-based resonant tunnelling diodes. Some of the device innovations have meanwhile become commercial products proving also the practical importance of this research area. The articles in this special issue relate to the projects of the last three-years' funding period from 2000 to 2003 and are organized along these two topical areas. We would like to thank the numerous reviewers for their valuable comments and the editorial staff of physica status solidi (c) for their extremely helpful support. The funding by the German Research Foundation over the full project time and the continued monitoring and advice by its representatives Dr. Klaus Wehrberger and Dr. Peter Heil are gratefully acknowledged by all previous members and co-workers of this Collaborative Research Centre. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Modification of upwind finite difference fractional step methods by the transient state of the semiconductor deviceNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 2 2008Yirang Yuan Abstract The mathematical model of the three-dimensional semiconductor devices of heat conduction is described by a system of four quasi-linear partial differential equations for initial boundary value problem. One equation of elliptic form is for the electric potential; two equations of convection-dominated diffusion type are for the electron and hole concentration; and one heat conduction equation is for temperature. Upwind finite difference fractional step methods are put forward. Some techniques, such as calculus of variations, energy method multiplicative commutation rule of difference operators, decomposition of high order difference operators, and the theory of prior estimates and techniques are adopted. Optimal order estimates in L2 norm are derived to determine the error in the approximate solution.© 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2008 [source] Functionalized Self-Assembled InAs/GaAs Quantum-Dot Structures Hybridized with Organic MoleculesADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Miaoxiang Chen Abstract Low-dimensional III,V semiconductors have many advantages over other semiconductors; however, they are not particularly stable under physiological conditions. Hybridizing biocompatible organic molecules with advanced optical and electronic semiconductor devices based on quantum dots (QDs) and quantum wires could provide an efficient solution to realize stress-free and nontoxic interfaces to attach larger functional biomolecules. Monitoring the modifications of the optical properties of the hybrid molecule,QD systems by grafting various types of air-stable diazonium salts onto the QD structures surfaces provides a direct approach to prove the above concepts. The InAs/GaAs QD structures used in this work consist of a layer of surface InAs QDs and a layer of buried InAs QDs embedded in a wider-bandgap GaAs matrix. An enhancement in photoluminescence intensity by a factor of 3.3 from the buried QDs is achieved owing to the efficient elimination of the dangling bonds on the surface of the structures and to the decrease in non-radiative recombination caused by their surface states. Furthermore, a narrow photoluminescence band peaking at 1620,nm with a linewidth of 49 meV corresponding to the eigenstates interband transition of the surface InAs QDs is for the first time clearly observed at room temperature, which is something that has rarely been achieved without the use of such engineered surfaces. The experimental results demonstrate that the hybrid molecule,QD systems possess a high stability, and both the surface and buried QDs are very sensitive to changes in their surficial conditions, indicating that they are excellent candidates as basic sensing elements for novel biosensor applications. [source] Cover Picture: Fabrication of Multicomponent Microsystems by Directed Three-Dimensional Self-Assembly (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 5 2005Mater. Abstract Directed three-dimensional self-assembly to assemble and package integrated semiconductor devices is demonstrated by Jacobs and Zheng on p.,732. The self-assembly process uses geometrical shape recognition to identify different components and surface-tension between liquid solder and metal-coated areas to form mechanical and electrical connections. The components (top left) self-assemble in a turbulent flow (center) and form functional multi-component microsystems (bottom right) by sequentially adding parts to the assembly solution. The technique provides, for the first time, a route to enable the realization of three-dimensional heterogeneous microsystems that contain non-identical parts, and connecting them electrically. We have developed a directed self-assembly process for the fabrication of three-dimensional (3D) microsystems that contain non-identical parts and a statistical model that relates the process yield to the process parameters. The self-assembly process uses geometric-shape recognition to identify different components, and surface tension between liquid solder and metal-coated areas to form mechanical and electrical connections. The concept is used to realize self-packaging microsystems that contain non-identical subunits. To enable the realization of microsystems that contain more than two non-identical subunits, sequential self-assembly is introduced, a process that is similar to the formation of heterodimers, heterotrimers, and higher aggregates found in nature, chemistry, and chemical biology. The self-assembly of three-component assemblies is demonstrated by sequentially adding device segments to the assembly solution including two hundred micrometer-sized light-emitting diodes (LEDs) and complementary metal oxide semiconductor (CMOS) integrated circuits. Six hundred AlGaInP/GaAs LED segments self-assembled onto device carriers in two minutes, without defects, and encapsulation units self-assembled onto the LED-carrier assemblies to form a 3D circuit path to operate the final device. The self-assembly process is a well-defined statistical process. The process follows a first-order, non-linear differential equation. The presented model relates the progression of the self-assembly and yield with the process parameters,component population and capture probability,that are defined by the agitation and the component design. [source] Characteristics of CVD silicon oxide films: Effect of discharge form on formation and properties of filmsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2004Kazuhiro Ishimaru Abstract A silent discharge is one of the simplest methods for realizing a nonequilibrium plasma condition at atmospheric pressure. In this study, nonequilibrium plasma chemical reactions by this discharge have been applied to a remote plasma chemical vapor deposition (CVD) of silicon oxide films using tetraethylorthosilicate (TEOS) and oxygen. Film characteristics obtained by this CVD have been investigated for applications to advanced semiconductor devices. Conditions for depositing films with high quality have been investigated minutely. From these results, it has been clarified that silicon oxide films with high quality and excellent step coverage can be obtained by plasma excitation using pulsed silent discharge. It has also been clarified that films with similar characteristics can be obtained by plasma excitation using low-frequency AC silent discharge at subatmospheric pressure. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(2): 106,116, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20000 [source] Numerical simulation of thermal runaway phenomena in silicon semiconductor devicesHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2002Kazanori Shioda Abstract A mathematical model for heat production due to thermal excitation of conductive electrons and positive holes in a semiconductor pn junction is derived and discussed. The model is applied to simulate the thermal runaway phenomena in power electronics semiconductor devices. Our discussion focuses especially on the modeling of unexpected huge currents due to an excessive temperature increase. Calculated dynamics of temperature distributions of a silicon wafer while cooling performance decreases proved it is possible for a silicon wafer to be heated over its melting point in a few milliseconds. Our results indicate that if a local hot spot arises in a wafer, the thermal intrinsic excitation carries an increased diffusion current of minor carriers and a recombination current in the depletion layer of a pn junction. Also it appears to be important that cooling performance should be uniform on the wafer to avoid the growth of hot spots and thermal-runaway itself. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(6): 438,455, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10044 [source] Discrete duality finite volume schemes for two-dimensional drift-diffusion and energy-transport modelsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2009C. Chainais-Hillairet Abstract The drift-diffusion and the energy-transport models appear in the modelling of semiconductor devices. The main difficulty arising in the approximation of the energy transport model by finite volume schemes is the discretization of the Joule heating term in the equation on the density of energy. Following some recent ideas by Domelevo and Omnčs for the discretization of the Laplace equation on almost general meshes, we construct a finite volume approximation of the 2-D drift-diffusion and energy transport models. These schemes still hold on almost general meshes. Finally, we present numerical simulations of semiconductor devices. Copyright © 2006 John Wiley & Sons, Ltd. [source] Fabrication of a Multilayered Low-Temperature Cofired Ceramic Micro-Plasma-Generating DeviceINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 6 2006Amanda Baker Plasma technology is currently being used in innumerable industrial applications. Some of the common uses of this technology include surface cleaning and treatment, sputtering and etching of semiconductor devices, excitation source for chemical analyses, cutting, environmental cleanup, sterilization, and phototherapy. The harsh conditions that these devices must endure require robust refractory materials systems for their fabrication and reliability. Low-temperature cofired ceramic (LTCC) material systems provide a durable and cost-effective platform for the manufacture of such devices, and allow for possible integration into meso-scale microsystems. Our designs are based on RF microstriplines that capacitively couple and ionize small gas discharge sites over the top electrode. In this paper, we have built several iterations of this micro-plasma generating device using LTCC material systems. The impact of electrode ink selection and processing, lamination methods, dielectric layer thickness, and electrode design has been investigated. Several micro-plasma-generating devices were then evaluated for power requirements, output stability, and long-term reliability. [source] Simultaneous IR Material Recognition and Conductivity Mapping by Nanoscale Near-Field Microscopy,ADVANCED MATERIALS, Issue 17 2007J. Huber IR scattering-type near-field microscopy is applied to simultaneously map material composition and conduction properties in cross-sectional samples of industrial bipolar and metal-oxide- semiconductor devices with nanoscale spatial resolution. Within a single mid-IR image, all relevant materials such as metals, Si, Si3N4, and oxides can be identified by material-specific amplitude and phase contrasts. [source] Investigations of the usefulness of average models for calculations characteristics of buck and boost converters at the steady stateINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 1 2010Krzysztof Górecki Abstract This paper deals with the problem of the analysis of boost and buck converters at the steady state with the use of the method of average models. The usefulness of this method is examined by comparing the boost and buck converters characteristics at the steady-state obtained both with the transient analysis with physical models of semiconductor devices and the examined method as well. The accuracy of the method of the average models is investigated with respect to the values of the circuit load resistance, the pulse-duty factor and the frequency of the signal controlling the power switch. Copyright © 2009 John Wiley & Sons, Ltd. [source] Integral evaluation in semiconductor device modelling using simulated annealing with Bose,Einstein statisticsINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 4 2007E.A.B. Cole Abstract Fermi integrals arise in the mathematical and numerical modelling of microwave semiconductor devices. In particular, associated Fermi integrals involving two arguments arise in the modelling of HEMTs, in which quantum wells form at the material interfaces. The numerical evaluation of these associated integrals is time consuming. In this paper, these associated integrals are replaced by simpler functions which depend on a small number of optimal parameters. These parameters are found by optimizing a suitable cost function using a genetic algorithm with simulated annealing. A new method is introduced whereby the transition probabilities of the simulated annealing process are based on the Bose,Einstein distribution function, rather than on the more usual Maxwell,Boltzmann statistics or Tsallis statistics. Results are presented for the simulation of a four-layer HEMT, and show the effect of the approximation for the associated Fermi integrals. A comparison is made of the convergence properties of the three different statistics used in the simulated annealing process. Copyright © 2007 John Wiley & Sons, Ltd. [source] Study of parallel numerical methods for semiconductor device simulationINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 1 2006Natalia Seoane Abstract Simulators of semiconductor devices have to solve systems of equations generated by the discretization of partial differential equations, which are the most time-consuming part of the simulation process. Therefore, the use of an effective method to solve these linear systems is essential. In this work we have evaluated the efficiency of different parallel direct and iterative solvers used for the solution of the drift,diffusion equations in semiconductor device simulation. Several preconditioning techniques have been applied in order to minimize the execution times. We have found that FGMRES and BCGSTAB solvers preconditioned with Additive Schwarz are the most suitable for these types of problems. The results were obtained in an HP Superdome cluster with 128 Itanium2 1.5 GHz. Copyright © 2005 John Wiley & Sons, Ltd. [source] A fast power loss calculation method for long real time thermal simulation of IGBT modules for a three-phase inverter systemINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 1 2006Z. Zhou Abstract A fast power losses calculation method for long real time thermal simulation of IGBT module for a three-phase inverter system is presented in this paper. The speed-up is obtained by simplifying the representation of the three-phase inverter at the system modelling stage. This allows the inverter system to be simulated predicting the effective voltages and currents whilst using large time-step. An average power losses is calculated during each clock period, using a pre-defined look-up table, which stores the switching and on-state losses generated by either direct measurement or automatically based upon compact models for the semiconductor devices. This simulation methodology brings together accurate models of the electrical systems performance, state of the art-device compact models and a realistic simulation of the thermal performance in a usable period of CPU time and is suitable for a long real time thermal simulation of inverter power devices with arbitrary load. Thermal simulation results show that with the same IGBT characteristics applied, the proposed model can give the almost same thermal performance compared to the full physically based device modelling approach. Copyright © 2006 John Wiley & Sons, Ltd. [source] Role of the temperature distribution on the PN junction behaviour in the electro-thermal simulationINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 6 2004Hatem Garrab Abstract Electro-thermal simulations of a PIN-diode based on the finite-element method, show a non-uniform temperature distribution inside the device during switching transients. Hence, the implicit assumption of a uniform temperature distribution when coupling an analytical electrical model and a thermal model yields inaccurate electro-thermal behaviour of the PIN-diode so far. The idea of including non-uniform temperature distribution into power semiconductor device models is not new, as accurate electro-thermal simulations are required for designing compact power electronic systems (as IC or MCM). Instead of using a one-dimensional finite difference or element method, the bond graphs and the hydrodynamic method are utilized to build an electro-thermal model of the PIN-diode. The results obtained by this original technique are compared with those obtained by a commercial finite-element simulator. The results are similar but the computation effort of the proposed technique is a fraction of that required by finite-element simulators. Moreover, the proposed technique may be applied easily to other power semiconductor devices. Copyright © 2004 John Wiley & Sons, Ltd. [source] An adaptive remeshing technique based on hierarchical error estimates for simulation of semiconductor devicesINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 1 2004Geng Yang Abstract We discuss first hierarchical error estimates and a criterion for mesh refinement. Then we describe briefly the hydrodynamic model of semiconductor model. Based on artificial viscosity technique about electron velocity, we propose to solve a Poisson equation to obtain a correction about mesh optimization. Finally, we simulate a GaAs MESFET's device with a gate of 0.3 µm length and give some discussions about numerical results. Copyright © 2004 John Wiley & Sons, Ltd. [source] Numerical modelling of equilibrium charge separation in poled devicesINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 6 2001A. De Francesco Abstract We describe an efficient numerical procedure for the equilibrium solution of the internal electric field distribution resulting from poling of photo-refractive materials. This technique has been developed to model the equilibrium state in poled bulk devices requiring bulk charge neutrality to facilitate the modelling of blocking boundaries for a high externally applied voltage (bias) in the kV range for a small number of points. This technique is an improvement on existing conventional numerical techniques employed for modelling semiconductor devices that are intended for low bias. This method can also accommodate the modelling of planar insulators and organic optical materials. We develop an algorithm incorporating the existing Newton,Raphson method for solving Kukhtarev's equations that enforces conservation of charge within the modelled system. We apply this technique to model one-dimensional charge separation in ultraviolet (UV) excited poling of glass and, report numerical equilibrium electric field distribution for a 2 kV bias. The convergence behaviour of the algorithm is investigated and compared against the Newton,Raphson method. Copyright © 2001 John Wiley & Sons, Ltd. [source] Off-axis electron holography of electrostatic potentials in unbiased and reverse biased focused ion beam milled semiconductor devicesJOURNAL OF MICROSCOPY, Issue 3 2004A. C. TWITCHETT Summary Off-axis electron holography in the transmission electron microscope (TEM) is used to measure two-dimensional electrostatic potentials in both unbiased and reverse biased silicon specimens that each contain a single p,n junction. All the specimens are prepared for examination in the TEM using focused ion beam (FIB) milling. The in situ electrical biasing experiments make use of a novel specimen geometry, which is based on a combination of cleaving and FIB milling. The design and construction of an electrical biasing holder are described, and the effects of TEM specimen preparation on the electrostatic potential in the specimen, as well as on fringing fields beyond the specimen surface, are assessed. [source] On spherical harmonics expansion type modelsfor electron,phonon collisionsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 3 2003J.-P. Bourgade Abstract In this paper, we give the rigorous derivation of a diffusion model for semiconductor devices, the starting point being a microscopic description of electron transport by means of a kinetic equation of Boltzmann type. The limit of a small mean free path at a large time leads to a diffusion equation of ,SHE' type (spherical harmonics expansion). We deal with a collision operator that models interactions between electron and phonons. This induces a peculiar form for the diffusion tensor: electron,phonon collisions happen to be discontinuous in energy and inelastic, and, as a consequence, the diffusion tensor appears as an infinite dimensional matrix. Copyright © 2003 John Wiley & Sons, Ltd. [source] Stationary solutions to an energy model for semiconductor devices where the equations are defined on different domainsMATHEMATISCHE NACHRICHTEN, Issue 12 2008Annegret Glitzky Abstract We discuss a stationary energy model from semiconductor modelling. We accept the more realistic assumption that the continuity equations for electrons and holes have to be considered only in a subdomain ,0 of the domain of definition , of the energy balance equation and of the Poisson equation. Here ,0 corresponds to the region of semiconducting material, , \ ,0 represents passive layers. Metals serving as contacts are modelled by Dirichlet boundary conditions. We prove a local existence and uniqueness result for the two-dimensional stationary energy model. For this purpose we derive a W1,p -regularity result for solutions of systems of elliptic equations with different regions of definition and use the Implicit Function Theorem. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Iterative versus direct parallel substructuring methods in semiconductor device modellingNUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 1 2005L. Giraud Abstract The numerical simulation of semiconductor devices is extremely demanding in term of computational time because it involves complex embedded numerical schemes. At the kernel of these schemes is the solution of very ill-conditioned large linear systems. In this paper, we present the various ingredients of some hybrid iterative schemes that play a central role in the robustness of these solvers when they are embedded in other numerical procedures. On a set of two-dimensional unstructured mixed finite element problems representative of semiconductor simulation, we perform a fair and detailed comparison between parallel iterative and direct linear solution techniques. We show that iterative solvers can be robust enough to solve the very challenging linear systems that arise in those simulations. Copyright © 2004 John Wiley & Sons, Ltd. [source] Modification of upwind finite difference fractional step methods by the transient state of the semiconductor deviceNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 2 2008Yirang Yuan Abstract The mathematical model of the three-dimensional semiconductor devices of heat conduction is described by a system of four quasi-linear partial differential equations for initial boundary value problem. One equation of elliptic form is for the electric potential; two equations of convection-dominated diffusion type are for the electron and hole concentration; and one heat conduction equation is for temperature. Upwind finite difference fractional step methods are put forward. Some techniques, such as calculus of variations, energy method multiplicative commutation rule of difference operators, decomposition of high order difference operators, and the theory of prior estimates and techniques are adopted. Optimal order estimates in L2 norm are derived to determine the error in the approximate solution.© 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2008 [source] Silicon-on-insulator based thin film resistors for quantitative biosensing applicationsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 14 2006Petra A. Neff Abstract Field-effect based semiconductor devices for the label-free detection of molecular interactions represent a promising development for biosensor applications. Recently, several such devices have been presented for the direct electrical detection of nucleic acids and proteins. However, a detailed and quantitative understanding of experimental observations is still elusive in most cases. Here we employ a recently introduced Silicon-on-Insulator (SOI) based field-effect sensor for the label-free detection of molecules by their intrinsic charge. We present a theoretical description for the quantitative analysis of the sensor response. A capacitor model was developed which accounts for dielectric effects as well as for Debye screening by mobile ions within the layers of molecules bound to the surface. We successfully applied the model to the detection of charged peptides and multilayers at the functionalized sensor surfaces. The electrical detection of the adsorption of bovine serum albumin (BSA) to the sensor surface is demonstrated and can be explained in terms of a dipolar orientation of the bound molecules. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Special issue: Physics of Organic SemiconductorsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2004Wolfgang Brütting This special issue of physica status solidi (a) gives an overview of our present-day knowledge of the physics behind organic semiconductor devices, ranging from the growth of organic layers and crystals, their electronic properties at interfaces, their photophysics and electrical transport properties to the application in organic field-effect transistors, photovoltaic cells and organic light-emit-ting diodes. Guest Editor of the present issue is Wolfgang Brütting, professor at the University of Augsburg, where he leads a research group working on organic semiconductors, their physical and materials properties, and the understanding of the basic processes in these materials and devices. The cover picture is an angular plot of the anisotropy of the charge carrier mobility , in the a,b plane of a rubrene single crystal, probed on an elastomeric rubber stamp field-effect transistor device. The black and red squares correspond to the values of , extracted from the linear and saturation regimes of the transistor operation, respectively. More information can be found in the Review Article by R. W. I. de Boer et al. [1]. [source] Spin-dependent tunneling in modulated structures of (Ga,Mn)AsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007P. Sankowski Abstract The spin-dependent tunneling in layered structures based on (Ga,Mn)As, in particular the dependence of the tunneling current on magnetization direction, is studied theoretically. To capture the complexity of the tunneling effects in these semiconductor devices we combine a multi-orbital tight-binding approach with Landauer-Büttiker formalism. This theory allows us to reproduce the tunneling anisotropic magnetoresistance effects observed in (Ga,Mn)As/GaAs Esaki-Zener diodes. The model is also used to describe the in-plane and out-of-plane anisotropy of tunneling magnetoresistance in (Ga,Mn)As-based trilayers. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Preface: phys. stat. sol. (c) 1/8PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2004Markus C. Amann In this special issue of physica status solidi (c) we have included 10 invited papers reviewing the current state-of-the-art and the progress achieved in materials science, semiconductor theory, novel physical mechanisms and advanced device concepts in the field of nanostructured electronic and optoelectronic semiconductor devices. All of these papers were written by previous members of the Collaborative Research Centre 348 "Nanometer-Halbleiterbauelemente: Grundlagen , Konzepte , Realisierungen" (Nanometer Semiconductor Devices: Fundamentals , Concepts , Realisations), which was funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) during the period from 1991 to 2003. In these twelve years, the researchers in this programme have carried an intense activity directed towards two main objectives. First of all, Fundamentals and Concepts of nanostructure devices and their technology were explored theoretically and experimentally including the effects of low-dimensional structures on carrier transport, optical properties and spin, as well as the enabling epitaxial and nanostructure technologies such as the cleaved-edge-overgrowth technique and the self-assembled growth of quantum dots. A second field of interest was focused towards the design and development of Novel Semiconductor Devices exploiting nanostructure technology. This comprises optical detectors and memories with nanometer lateral dimensions, microwave detectors and sources up to the 300 GHz regime, innovative tunable and surface-emitting semiconductor lasers for the wavelength range 0.9 to 2 ,m, and nitride-based resonant tunnelling diodes. Some of the device innovations have meanwhile become commercial products proving also the practical importance of this research area. The articles in this special issue relate to the projects of the last three-years' funding period from 2000 to 2003 and are organized along these two topical areas. We would like to thank the numerous reviewers for their valuable comments and the editorial staff of physica status solidi (c) for their extremely helpful support. The funding by the German Research Foundation over the full project time and the continued monitoring and advice by its representatives Dr. Klaus Wehrberger and Dr. Peter Heil are gratefully acknowledged by all previous members and co-workers of this Collaborative Research Centre. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Yield stress and rheological characterization of the low shear zone of an epoxy molding compound for encapsulation of semiconductor devicesPOLYMER ENGINEERING & SCIENCE, Issue 4 2008Masaki Yoshii In encapsulation molding of IC packages, the melt flow inside the cavity is generally controlled in a low shear to prevent wire sweep, and other molding defects. Therefore, it is important to evaluate the rheological properties of epoxy molding compounds (EMC) in a low shear zone including determining the yield stress. In this study, a newly specialized Parallel-Plate Plastometer for EMCs was built up. Using this plastometer, the yield stress and its temperature dependence were clarified, and the rheological properties in the low shear zone were evaluated. As a result, the rheological properties in a low shear zone of 0.1,10 s,1 were characterized using the Herschel,Bulkley viscosity model which introduced the yield stress, the Castro,Macosko equation as a dependency model of cure, and the WLF equation as a dependency model for temperature. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Reliability qualification of semiconductor devices based on physics-of-failure and risk and opportunity assessmentQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 2 2002W. H. Gerling Abstract Qualification frequently is a time-critical activity at the end of a development project. As time-to-market is a competitive issue, the most efficient qualification efforts are of interest. A concept is outlined, which proactively integrates qualification into the development process and provides a systematic procedure as a support tool to development and gives early focus on required activities. It converts requirements for a product into measures of development and qualification in combination with a risk and opportunity assessment step and accompanies the development process as a guiding and recording tool for advanced quality planning and confirmation. The collected data enlarge the knowledge database for DFR/BIR (designing for reliability/building-in reliability) to be used for future projects. The procedure challenges and promotes teamwork of all the disciplines involved. Based on the physics-of-failure concept the reliability qualification methodology is re-arranged with regard to the relationships between design, technology, manufacturing and the different product life phases at use conditions. It makes use of the physics-of-failure concept by considering the potential individual failure mechanisms and relates most of the reliability aspects to the technology rather than to the individual product design. Evaluation of complex products using common reliability models and the definition of sample sizes with respect to systematic inherent product properties and fractions of defects are discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] The Influence of Knowledge Accumulation on Buyer-Supplier Codevelopment ProjectsTHE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 5 2003Melissa M. Appleyard This article investigates innovation across a supply chain and considers how knowledge accumulation as a consequence of buyer-supplier codevelopment projects can influence the projects' specifications. The setting is the semiconductor industry, and the players are chip producers who cooperate with their suppliers to modify their manufacturing equipment used to produce new semiconductor devices. Two detailed case studies were undertaken to determine the tradeoffs encountered by the buyer and supplier when setting the parameters that govern codevelopment projects. The findings from the case studies inform a conceptual framework that outlines the net payoffs to buyers when deciding whether to "make" or "buy" their production equipment. If buyers pursue the "make" option, they then have to decide the degree to which they sponsor modifications tailored to their production processes or modifications more generally applicable across the industry. More generally applicable modifications likely would prompt suppliers to invest relatively more in follow-on knowledge creation for upgrades and field support while leading to lower equipment costs due to economies of scale from larger production runs of the new equipment. The framework suggests that when making this sequence of decisions, an innovative buyer also weighs the importance of codevelopment for securing intellectual property rights, guaranteeing early access to new equipment enabling early product launch, and achieving high production yields quickly due to "previewing" the equipment. The conceptual framework leads to a multi-period model that focuses on the importance of knowledge accumulation for project parameterization. As captured by the model, buyers may prefer generally applicable modifications to customized ones, because generally applicable modifications may lead to greater knowledge accumulation at the supplier. This knowledge accumulation may be either "embodied" in equipment upgrades or "unembodied" in improved field support. In addition to shaping the nature of particular codevelopment projects, knowledge accumulation also may have profound implications for long-run industry structure. As seen in the semiconductor industry, knowledge accumulation at equipment suppliers has contributed to the rise of contract manufacturers, because these manufacturers can outfit their production facilities with equipment that embodies the accumulated knowledge. These findings suggest that for both short-run and long-run reasons, the dynamics of knowledge accumulation merit thorough attention when members of a supply chain cooperate during the course of new product development. [source] MOCVD of Hafnium Silicate Films Obtained from a Single-Source Precusor on Silicon and Germanium for Gate-Dielectric Applications,CHEMICAL VAPOR DEPOSITION, Issue 2-3 2007M. Lemberger Abstract In this work, hafnium silicate layers on Si and Ge wafers for gate dielectric application in metal,oxide,semiconductor devices are investigated. Films are deposited by metal,organic (MO)CVD using the single-source precursor Hf(acac)2(OSitBuMe2)2. This precursor exhibits good properties in terms of hydrolysis stability, volatility, and deposition. However, precursor decomposition is affected by surface conditions. Films deposited on Si wafers reveal high C contamination (up to 20,at,%) and low Si content (up to 20,at,%). In contrast, for film deposition on Ge wafers, no C contamination can be detected and Si incorporation is delayed until after about 15,nm HfO2 dielectric growth. Post-deposition rapid thermal annealing in an O2 atmosphere causes crystallization of deposited films, Si and Ge redistribution in the dielectric, respectively, and interfacial layer growth. However, oxygen annealing was also found to reduce effective oxide thickness (EOT) significantly compared to as-deposited films, which is attributed to crystallization effects. However, scaling of EOT is limited by that interfacial layer growth. Leakage currents are mainly caused by trap-related conduction mechanisms. Energy levels of involved traps decrease with increasing crystallization and/or Hf content, and values of 0.5,eV and 1,eV related to Hf and Si bonds, respectively, are obtained. [source] | ||||||||||||||||||||||