bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoluminescence and Raman Spectra of Flux Processed Bulk Single Crystal GaN
Authors: Cho Chae Ryong , Park Sang Eon , Cho Yong Chan , Jeong Se-Young 
Published: April 2011

ABSTRACTBulk wurtzite-GaN crystal was obtained with a size more than 3 mm along the length of the crystal and with a thickness 200 ∼ 300 µm at around 750°C and 100 bar for 24 hrs in the flux growth method. The structural and compositional property of the GaN bulk single crystal was also studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. Photoluminescence, cathodoluminescence and micro-Raman measurements at room temperature are investigated for bulk single crystals of wurtzite GaN. The cathodoluminescence peak of near band-to-band transition at 365.5 nm and the E2(high energy, 568 cm−1) and A1(LO, 737 cm−1) Raman phonon modes were obtained according to the different position of the (0001) surface of GaN grown by flux method. Sharp line shape for the strain-sensitive E2 (high) mode is considered to be due to the high crystalline quality of the crystal.
Design of Metal-Semiconductor-Metal Ultra-Violet Detector on Gallium Nitride
Authors: Gu Wenhua , Chua Soo Jin , Zhang Xin Hai 
Published: April 2011

ABSTRACTThe design of Gallium Nitride based Metal-Semiconductor-Metal Ultra-Violet detector is discussed. We introduce a simulation model using Medici to describe the performances of such detectors. Structure parameters, such as the inter-digitated electrode dimension and the GaN layer thickness, are optimized for response current and time using this model. The simulation results can be explained by the variation of depletion region. We introduce the “effective electric field intensity” to describe the depletion region. The relationship between the “effective electric field intensity” and structure parameters are simulated and discussed.
Single domain structure of 2H-AlN films on Si(001) substrates
Authors: Jinschek Joerg , Lebedev Vadim , Kaiser Ute , Richter Wolfgang 
Published: April 2011

ABSTRACTAluminum nitride (2H-AlN) films were grown by plasma-assisted molecular beam epitaxy (MBE) on Si(001). By conventional (CTEM) and high resolution transmission electron microscopy (HRTEM) investigations the influence of the off-axis angle of the substrate surface on the film structure was studied. Three types of Si(001) substrates were used: on-axis, ∼1°, and ∼5° off-axis. The 2H-AlN layer on an exact oriented Si(001) substrates consists of 3 AlN film domains: two main film domains, AlNI and AlNII, and a small domain AlNIII at substrate surface defects. Their c-axis orientations are parallel to the c-axis of the substrate: [0001]AlNI,II,III ∥ [001]Si. The a-axes of AlNI and AlNII rotated by 30° to each other: [11 20]AlNII∥[01 10]AlNII ∥ [1 1 0]Si. The orientation of AlNIII is [01 10]AlNIII ∥ [100]Si. In 2H-AlN films grown on off-axis Si(001) substrates (∼1° and ∼5°) the ratio between the AlNI and AlNII film domains changes dramatically as far as a single domain film structure consisting of mainly AlNI is reached. The AlN c-axes of all domains on the off-axis substrates are not parallel to the Si c-axis but tilted by the off-axis angle of the Si(001) substrate (∼1° respectively ∼5°), i.e. [0001]AlN is parallel to the Si(001) substrate surface orientation. Determination of the AlNI domain / Si(001) interface structure by HRTEM illuminates the origin of the preference of this domain in the 2H-AlN film by using off-axis Si(001) substrates. On the on-axis substrate a regular array of misfit dislocations causes a 5:4 fit between the (1 1 00)AlN and ( 1 1 0)Si lattice planes. The off-axis Si(001) leads to a rotation of the AlN lattice in respect of the Si lattice. An array of misfit dislocations with a 4:3 fit between (1 1 01)AlN and ( 1 1 1)Si lattice planes decreases the residual lattice misfit from -1.6% to -0.8%.
Material System for Packaging 500°C SiC Microsystems
Authors: Chen Liang-Yu , Okojie Robert S. , Neudeck Philip G. , Hunter Gary W. , T. Lin Shun-Tien 
Published: April 2011

ABSTRACTIn order to establish a material system for packaging 500°C SiC microsystems, aluminum nitride (AlN) and aluminum oxide (Al2O3) were selected as packaging substrates, and gold (Au) thick-film materials were selected as substrate metallization material for electrical interconnection system (thick-film printed wires and thick-film metallization based wire-bond) and conductive die-attach interlayer. During a 1500-hour test in atmospheric oxygen with and without electrical bias, the electrical resistance of Au thick-film based interconnection system demonstrated low and stable electrical resistance at 500°C. The electrical interconnection system was also tested in extreme dynamic thermal environment. A silicon carbide (SiC) Schottky diode was attached to ceramic substrate using Au thick-film material as the conductive bonding layer and was successfully tested at 500°C in air for more than 1000 hours. In addition to the electrical test of die-attach in static thermal environments, nonlinear finite element analysis (FEA) was used for thermal mechanical evaluation and optimization of the die-attach in a wide temperature range.
A Dimple-Array Interconnect Technique for Power Semiconductor Devices
Authors: Wen Simon S. , Huff Daniel , Lu Guo-Quan 
Published: April 2011

ABSTRACTThis paper describes a wireless-bond interconnect technique, termed Dimple-Array Interconnect (DAI) technique for packaging power devices. Electrical connections onto the devices are established by soldering arrays of dimples pre-formed on a metal sheet. Preliminary experimental and analytical results demonstrated potential advantages of this technique such as reduced parasitic noises, improved heat dissipation, as well as lowered processing complexity, compared to the conventional wire bonding technology in power module manufacturing. Thermomechanical analysis using thermal cycling test and FEM were also performed to evaluate the reliability characteristics of this interconnect technique for power devices.
An Investigation of Lead Free and Bromine Free Technologies for Medium Power Semiconductor Packaging
Authors: Adamson Philip , Dugdale Pamela 
Published: April 2011

ABSTRACTOver recent years there has been a growing interest in the removal or substitution of Lead, Bromine and other hazardous chemicals from electronic and electrical equipment. This relates primarily to products whose end of life disposal relies on the use of landfill sites or increasingly on recycling. The driving force for these changes come from both legislation such as that proposed by the European Union [1] and also from consumer awareness. The implications of the move towards more environmentally friendly electronics extend right down the level of discrete component packages including those produced in large numbers by the power semiconductor industry. In the present paper the technical challenges associated with the development of a lead and bromine free medium power packaging are discussed and the results of ongoing investigations are presented. The major challenges in this area relate not only to the substitution of key elements but also to ensuring compatibility with the higher reflow temperatures which may be associated with Pb-free surface mount processing. This raises particular issues with respect to the die attach material, which is often a high Pb soft solder; the encapsulation compounds which tend to rely on Bromine and Antimony compounds for their flame retardant properties; and the device plating which must be compatible with Pb-free board attach solders.
Adhesion Mechanisms of Silane Adhesion Promoters in Microelectronic Packaging
Authors: Jenkins Maura , Snodgrass Jeffrey , Chesterman Aaron , DeVries Gretchen , Dauskardt Reinhold H. , Bravman John C. 
Published: April 2011

ABSTRACTSilane adhesion promoters are seeing increasing use in microelectronic packaging applications. For example, they are currently used to adhere the passivating polymer overlayer to oxide. In this paper, we present detailed studies of silane adhesion promoters on the silicon oxide surface. Two common promoters (aminopropyltriethoxysilane and vinyltriethoxysilane) as well as non-functional silanes are investigated. It was found that without a functional end group, long carbon chain silanes can severely degrade adhesion, resulting in interfaces weaker than if no silane is used. Several spin coat solution formulations are used in depositing these films. The resulting surface coverage is examined and quantified using XPS, and the adhesion behavior of various promoter films is tested in sandwich structures using a fracture mechanics approach. Finally, spin-coat solution concentration, surface coverage, and interface fracture energy are compared for the amine functional promoter.
Dielectric Properties and Morphology of Ferroelectric Ceramic-Polymer Composite Films
Authors: Chiang C. K. , Popielarz R. , Sung L. P. 
Published: April 2011

ABSTRACT!Dielectric constant and morphology of BaTiO3-polymer composite films were studied as a function of the filler concentration. The morphology of the films was examined using laser scanning confocal microscopy, which is capable to measure small particle distributions in more details than conventional microscopy. The thin-slice images allowed us to visualize the micron-size particles and the polymer between them nondestructively. We have found that, although BaTiO3 particles appear to form clusters at low filler concentrations, the cluster formation does not affect the dielectric constant of the composites.
Aspects of Grain Size Strengthening in Polycrystals
Authors: Chandrasekaran Dilip , Pettersson Kjell 
Published: April 2011

ABSTRACTThe strengthening effect of grain boundaries is well established and observed experimentally as the Hall-Petch relationship. In this paper different mechanisms proposed in the literature to explain the observed Hall-Petch effect are reviewed critically. The fundamental implications of the different approaches are discussed with reference to experimental data for two different classes of materials;-Materials with locked dislocations, i.e. with a sharp yield point behaviour.-Materials without locked dislocations, i.e. with a smooth yielding behaviour.It is shown that a simple model (Bergström) can be used to understand the grain size strengthening in the latter class of materials while more work is needed to quantitatively understand the behaviour of materials showing a sharp yield point.
Dislocation patterning and conservative recovery in single slip
Authors: Veyssière Patrick , Grégori Fabienne 
Published: April 2011

ABSTRACTPrismatic loops generated by cross-slip are organised in staircase-like strings such that the beginning of a loop corresponds in the screw orientation with the end of its neighbour. Strings constitute nucleation sites for dislocation tangles thus offering an explanation for spontaneous patterning in single glide. A loop string can be partially and even totally eliminated by a single impacting dislocation. In dense walls, loop refinement can also take place conservatively by mutual annihilation of loops of opposite signs.
Microelectronics Process Engineering: A Non-Traditional Approach to MS&E
Authors: Allen E. , Gleixner S. , Young G. , Parent D. , Dessouky Y. , Vanasupa L. 
Published: April 2011

ABSTRACTMaterials Science and Engineering straddles the fence between engineering and science. In order to produce more work-ready undergraduates, we offer a new interdisciplinary program to educate materials engineers with a particular emphasis on microelectronics-related manufacturing. The bachelor's level curriculum in Microelectronics Process Engineering (μProE)is interdisciplinary, drawing from materials, chemical, electrical and industrial engineering programs and tied together with courses, internships and projects which integrate thin film processing with manufacturing control methods. Our graduates are prepared for entry level engineering jobs that require knowledge and experience in microelectronics-type fabrication and statistics applications in manufacturing engineering. They also go on to graduate programs in materials science and engineering. The program objectives were defined using extensive input from industry and alumni. We market our program as part of workforce development for Silicon Valley and have won significant support from local industry as well as federal sources. We plan to offer a vertical slice of workforce development, from lower division engineering and community college activities to industry short courses. We also encourage all engineering majors to take electives in our program. All our course and program development efforts rely on clearly defined learning objectives.
Teaching General Chemistry Through Materials Science
Authors: Douglas Elliot P. 
Published: April 2011

ABSTRACTWe have developed a new Materials Chemistry course for freshmen with the goal of improving retention in the engineering program. This Materials Chemistry course is fundamentally different from other introductory materials courses in that it does not cover the standard introductory materials curriculum (diffusion, strengthening mechanisms, eutectic phase diagrams, etc.). Rather, its goal is to teach engineering applications of fundamental chemistry concepts. This course consists of four basic units: atomic, molecular and supermolecular structures; chemical reactions; physical chemistry; and biological materials. Each of these units consists of topics designed to show how fundamental concepts in chemistry can be applied to engineering problems. For example, liquid crystal display technology is used to teach the concept of molecular shape. The course also contains a laboratory section. This paper will describe the detailed contents of the course and its relation to the engineering curriculum.
A Curriculum Resource for Materials Science and Engineering Education - Elementary School Through College
Authors: Jacobs James A , Mckenney Alfred E 
Published: April 2011

ABSTRACTThis paper presents a new CD-ROM, (EMSET2, ISBN 0-13-030534-0) [1] which provides useful resources for courses in engineering and technology. A product of a fifteen-year effort, this CD contains hundreds of demonstrations and experiments which have been classroom tested and peer reviewed. These resources are available in the popular Adobe Acrobat PDF format, accessible thorough the Acrobat Reader, which is included. The contents are useful for such courses as materials science, materials technology, mechanics and strength of materials, as well as for pre-college level course and school visitations. Additional PDF-formatted resources on the CD-ROM include a short course on Microscopy of Fiber-Reinforced Polymer Composites, an Image Gallery showing materials, applications photos, photomicrographs of a wide range of materials, a structural models gallery, and related web site hyperlinks. There is also a section on how we made the PDFs. The manner in which the demonstrations and experiments are written provides useful tips on securing supplies and construction of devices. Topics include Structure, Testing & Evaluation, Metals, Polymers, Ceramics, Composites, Electronic & Optical Materials, as well as ideas for Materials Curriculum development.
Teaching Materials Characterization Techniques: An Interdisciplinary Approach to Develop Interactive Web-Based Multimedia Teaching/Learning Software
Authors: Prüßner Karin , Pingel Klaus , Dressel Horst-Peter , Becker Jens , Reiner Christof , Schlosser Marc , Christ Hans-Jürgen 
Published: April 2011

ABSTRACTIn a first step of a larger project to develop software to teach materials characterization techniques, we have developed a module on scanning electron microscopy (SEM) to be used mainly in a Department of Mechanical Engineering. The goal is to use the unique capabilities of the computer to develop a platform-independent interactive web-based software package which can be used as a stand-alone application or as support in existing “traditional” classes and improve the quality of teaching. Commercial development tools like Macromedia Dreamweaver for HTML pages, Macromedia Flash and JBuilder to create animations and visualizations of basic concepts and simulations of microscope operations are used for improved teaching quality.
Low Temperature Preparation of High-Quality Pb(Zr,Ti)O3 Films by Metal Organic Chemical Vapor Deposition with High Reproducibility
Authors: Funakubo Hiroshi , Nagashima Kuniharu , Aratani Masanori , Tokita Kouji , Oikawa Takahiro , Ozeki Tomohiko , Asano Gouji , Saito Keisuke 
Published: April 2011

AbstractPb(Zr,Ti)O3 (PZT) is one of the most promising materials for ferroelectric random access memory (FeRAM) application. Among the various preparation methods, metalorganic chemical vapor deposition (MOCVD) has been recognized as a most important one to realize high density FeRAM because of its potential of high-step-coverage and large-area-uniformity of the film quality.In the present study, pulsed-MOCVD was developed in which a mixture of the source gases was pulsed introduced into reaction chamber with interval. By using this deposition technique, simultaneous improvements of the crystallinity, surface smoothness, and electrical property of the film have been reached by comparing to the conventional continuous gas-supplied MOCVD. Moreover, this film had larger remanent polarization (Pr) and lower leakage current density. This is owing to reevaporation of excess Pb element from the film and increase of migration on the surface of substrate during the interval time.This process is also very effective to decrease the deposition temperature of the film having high quality. In fact, the Pr and the leakage current density of polycrystalline Pb(Zr0.35Ti0.65)O3 film deposited at 415 °C were 41.4 μC/cm2 and on the order of 10−7 A/cm2 at 200 kV/cm. This Pr value was almost the same as that of the epitaxially grown film deposited at 415 °C with the same composition corrected for the orientation difference. This suggests that the polycrystalline PZT film prepared by pulsed-MOCVD had the epitaxial-grade ferroelectric properties even through the deposition temperature was as low as 415 °C. Moreover, large “process window” comparable to the process window at 580 °C, above 150 °C higher temperature and was widely used condition, was achieved even at 395°C by the optimization of the deposition condition.
Low-Temperature Crystallization of Pb(Zr0.4,Ti0.6)O3 Thin Films by Chemical Solution Deposition
Authors: Maki Kazunari , Soyama Nobuyuki , Nagamine Kaoru , Mori Satoru , Ogi Katsumi 
Published: April 2011

AbstractWe studied the crystallization of sol-gel derived Pb(Zr0.4Ti0.6)O3 [PZT(40/60)] thin films at 400 down to 390°C on Pt/SiO2/Si substrates by combination of diol-based solutions and modified film preparation processes. It was found that PZT films could be crystallized at 390°C and that PZT films crystallized at 400°C had microstructures with perovskite-single-phase columnar grains and good ferroelectric characteristics such as switched polarization (2 Pr) of 20 μC/cm2 and relative permittivity (εr) of 740. Next, we evaluated annealing temperature dependence of PZT(40/60) thin films crystallized at 390 to 435°C. The results indicated that (111)-orientation of perovskite phases became weaker, (100)-orientation of those became stronger, and the perovskite grain size increased with decreasing in annealing temperature.
Probing the Dead Layer in Barium Strontium Titanate Capacitors Made by Pulsed Laser Deposition
Authors: Sinnamon L. J. , Bowman R. M. , Gregg J. M. 
Published: April 2011

AbstractThin film capacitors with structures Au/Ba0.5Sr0.5TiO3/SrRuO3 were fabricated by pulsed laser deposition onto {001}-oriented MgO single crystal substrates. As part of an overall programme to investigate the so-called ‘dead-layer’ effect, polarisation loops were taken from the capacitors and analysed as a function of BST film thickness. Analysis was done within a Landau-Ginzburg-Devonshire (LGD) framework, and showed that for film thickness greater than ∼100nm, changes in the dielectric behaviour of the BST were dominated more by epitaxial mismatch strain, than by the conventional notion of the dead-layer.
Fabrication of V-Substituted (Bi,M)4Ti3O12 [M = Lanthanoids] Thin Films by Chemical Solution Deposition Method
Authors: Uchida H. , Yoshikawa H. , Okada I. , Matsuda H. , Iijima T. , Watanabe T. , Funakubo H. 
Published: April 2011

AbstractBismuth titanate (Bi4Ti3O12; BIT) -based ferroelectric materials are proposed from the view of the “Site-engineering”, where the Bi-site ions are substituted by lanthanoid ions (La3+ and Nd3+) and Ti-site ions by other ions with higher charge valence (V5+). In the present study, influences of vanadium (V) - substitution for (Bi,M)4Ti3O12 thin films [M = lanthanoid] on the ferroelectric properties are evaluated. V-substituted (Bi,M)4Ti3O12 films have been fabricated using a chemical solution deposition (CSD) technique on the (111)Pt/Ti/SiO2/(100)Si substrate. Remnant polarization of (Bi,La)4Ti3O12 and (Bi,Nd)4Ti3O12 films has been improved by the V-substitution independent of the coercive field. The processing temperature of BLT and BNT films could also be lowered by the V-substitution.
Crystallization Behavior and Ferroelectric Properties of YMnO3 Thin Films on Si (100) Substrates
Authors: Yoo Dong Chul , Lee Jeong Yong , Kim Ik Soo , Kim Yong Tae 
Published: April 2011

AbstractYMnO3 thin films were sputtered on Si (100) substrates under different ambient conditions. After rapid thermal annealing process at 850 °C, the YMnO3 film deposited in Ar ambient had random orientations and the YMnO3 film deposited in Ar+O2 ambient was crystallized with distinct two layers, i.e., c-axis oriented layer in top region and random oriented layer in bottom region. Relations between the microstructure and the electrical properties of Pt/YMnO3/Si capacitor were investigated. Memory window and leakage current depended on the orientation of the YMnO3 thin films and the interfacial microstructure of the YMnO3/Si, respectively
Preparation and Characterization of a- and b-Axis-Oriented Epitaxially Grown Bi4Ti3O12-Based Thin Films on Rutile-Type Oxides
Authors: Watanabe Takayuki , Saito Keisuke , Osada Minoru , Funakubo Hiroshi 
Published: April 2011

Abstracta- and b-axis-oriented epitaxial Bi4Ti3O12 films were prepared on (101)TiO2 substrates (rutile) at 600°C by metalorganic chemical vapor deposition (MOCVD). Subsequently, the same films were similarly prepared on (101)-oriented conductive materials with the same rutile structure and similar lattice parameters as TiO2, such as RuO2 and IrO2. Their perfect epitaxial growth was confirmed by several X-ray diffraction measurements. RuO2 and IrO2 were deposited on not only structurally equivalent (101)RuO2//(101)TiO2 and (101)IrO2//(101)TiO2 structures, but were also successfully deposited on the corundum (012)Al2O3 and (110)Al2O3 single crystals by the MOCVD and rf-sputtering method, respectively. A well-saturated P-E hysteresis with a remanent polarization above 20 μC/cm2 was observed for a- and b-axis-oriented Bi4Ti3O12-based materials, (Bi4−xNdx)(Ti3−yVy)O12 (BNTV), that were epitaxially grown on rutile-rutile and rutile-corundum stacking structures. These results should enable broader application of the bismuth layer-structured ferroelectrics.