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作者： Qin, Qi Reno, John L Hu, Qing Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA 02139 United States Sandia National Laboratories Center of Integrated Nanotechnologies MS 1303 Albuquerque NM 87185-1303 United States

We demonstrate a fast frequency tuning of a terahertz wire-laser. Using a piezo-actuator and a MEMS-plunger enables a tuning speed up to 15 KHz. Improved bonding-pad design of wire-lasers leads to larger fabrication y... 详细信息

ISBN: (纸本)9781557529107

关键词： Wire

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Preparation and Properties of Hydrogenated Amorphous Silicon Produced by Plasma-Enhanced Chemical Vapor Decomposition of Silane

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MRS Online Proceedings Library 2011年第1期95卷 255-260页

作者： K. L. Tokuda D. Adler R. Reif AT&T Bell Laboratories Rm. 7C-108 Whippany USA Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge USA

We have investigated the properties of several hydrogenated amorphous silicon (a-Si:H) films prepared by the plasma-enhanced chemical vapor decomposition (PECVD) of silane. This reactor is singular because it operates at pressures as low as 10 mTorr and uses infrared lamps to heat the growth environment. Structural characterization showed that all the samples were amorphous. Most films had hydrogen concentrations about 5%, optical gaps near 1.6 eV, and neutral dangling-bond concentrations of the order of 5 × 1016 Cm−3. electrical activation energies were typically in the range 0.5 – 0.6 eV and the photoconductivity under ∼100 mW/cm2 white light was 10−4 (Ω-cm)−1. The dark conductivity was near 10−8(Ω-cm)−1. No significant change in dark conductivity or photoconductivity occurred after several hours of exposure to light.

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Magnetoreflection in Ion-Implanted Graphite*

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MRS Online Proceedings Library (OPL) 2011年第1期27卷 493-493页

作者： L.E Mcneil B.S. Elman M.S Dresselhaus G. Dresselhaus T. Venkatesan Department of Physics Department of Electrical Engineering and Computer Science Francis Bitter National Magnet Laboratory Massachusetts Institute of Technology Cambridge MA 02139 Bell Laboratories Murray Hill NJ 07974

The use of a hot stage (T ∼ 600°C) for ion implantation into graphite permits the introduction of foreign species into the host material while eliminating most of the lattice damage associated with ion implantation at room temperature. This permits the use of the magnetoreflection technique for examination of changes in the electronic band structure induced by implantation Samples of graphite implanted with 31P and 11B at various energies and fluences are examined, and the in-plane and c-axis disorder are characterized using Raman spectroscopy and Rutherford Backscattering Spectrometer (RBS) techniques. Implantation-induced changes in the electronic band structure are interpreted in terms of the Slonczewski-Weiss- McClure band model. Small changes are found relative to the band parameters that describe pristine graphite.

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Finite element thermal/mechanical analysis for microscale laser joining of ultrathin coatings of titanium on glass/polyimide system

Finite element thermal/mechanical analysis for microscale la...

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作者： Mayeed, M.S. Lubna, N.J. Auner, G.W. Patwa, R. Herfurth, H. Newaz, G.M. Mechanical Engineering Division of Engineering Southern Polytechnic State University Marietta 30060 GA United States Department of Chemical Engineering and Material Science Wayne State University Detroit MI United States Smart Sensors and Integrated Microsystems Department of Electrical and Computer Engineering Wayne State University Detroit MI United States Fraunhofer Center for Laser Technology Plymouth MI United States Department of Mechanical Engineering Wayne State University Detroit MI United States

Finite element (FE) thermal/mechanical analysis of microscale laser joining of biocompatible materials, polyimide (PI) and nanoscale coating of titanium (Ti) on glass (Gl), is important for the long-term application of bio-implants and the applications of nanoscale solid coatings. In this study, a comprehensive three-dimensional (3D) transient simulation for thermal/ mechanical analysis of transmission laser microjoining of dissimilar materials has been performed using the FE code ABAQUS, along with a moving Gaussian laser heat source. The laser beam (wavelength of 1100nm and diameter of 0.2 mm), moving at an optimized velocity (100 mm/min), passes through the transparent PI, gets absorbed by the absorbing Ti, and eventually melts the PI to form the bond. The laser bonded joint area is 6.5mmlong on three different Ti coating thicknesses of 400, 200, and 50nm on Gl surface. Non-uniform mixed meshes have been used and optimized to formulate the 3D FE model and ensure very refined meshing around the bond area. During the microscale laser heating, FE modelling shows that the widths of PI surface experiencing temperatures above the glass transition temperature are similar to the widths of bonds observed in experiments for coating thicknesses of 400 and 200nm of Ti on Gl. However, for the case of 50nm coating, bond width using FE analysis cannot produce and is lower than the bond width observed experimentally. After these verifications, the residual stress profile of the laser microjoint (200nm of Ti on Gl) has been calculated using the developed model with the system cooling down to room temperature. The transverse (to the laser travel direction) stress profiles on Ti surface have shown high tensile stress near the centre-line of laser travel, decreased to lower values from the centre-line symmetrically at both sides, and to the contrary, have shown compressive stresses near the centre-line on Gl surface. Maximum von-Mises residual stresses on PI and Gl surfaces are obta

关键词： Residual stresses

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Neural probes integrated with optical mixer/splitter waveguides and multiple stimulation sites

Neural probes integrated with optical mixer/splitter wavegui...

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IEEE International Conference on Micro Electro Mechanical Systems

作者： Maesoon Im Il-Joo Cho Fan Wu Kensall D. Wise Euisik Yoon Center of Wireless Integrated Microsystems Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA Korea Institute of Science and Technology Seoul South Korea

ISBN: (纸本)9781424496327

This paper reports new neural probe schemes incorporating various optical waveguides for optogenetic applications. A photodefinable polymer (SU-8) has been patterned to form optical mixer and splitter waveguides for advanced optical functions with multiple light sources and easy delivery of light to multiple shanks, respectively. Also, multiple stimulation sites have been implemented by step-wise patterning in a single waveguide. In addition to SU-8 waveguides, iridium electrodes have been integrated for recording of neural signals from optically stimulated neurons with light of specific wavelengths. Single mode optical fibers have been coupled in grooves etched in the probe body. We have successfully demonstrated transmissions of blue light, 473 nm in wavelength, through the waveguides that are integrated on the fabricated devices.

关键词： Optical fibers Probes Optical device fabrication Stimulated emission Optical mixing

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Wafer Level Modeling of Electrochemical-Mechanical Polishing (ECMP)

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MRS Online Proceedings Library (OPL) 2011年第1期991卷 0991-C11-04-0991-C11-04页

作者： Daniel Truque Xiaolin Xie Duane Boning truque@mit.edu Massachusetts Institute of Technology Electrical Engineering and Computer Science 70 Pacific St Apt. 902A Cambridge MA 02139 United States *** xiaolin@alum.mit.edu Massachusetts Institute of Technology Microsystems Technology Laboratories Cambridge MA 02139 United States boning@mtl.mit.edu Massachusetts Institute of Technology Microsystems Technology Laboratories Cambridge MA 02139 United States

In this work, we propose a wafer level dynamic ECMP model based on time-evolving current density distributions across the wafer. The copper layer on the wafer surface is discretized, and the potential and current density distributions are calculated based on the applied voltage zones and metal film thicknesses across the wafer. The copper removal rate is proportional to the current density, and thus the copper thickness (and conductance) can be calculated as a function of position on the wafer and polish time. Using a time-stepping simulation, the model is able to capture the wafer level non-uniformity and time-dependence of ECMP removal. The model is also able to capture the time-varying voltage zones used in ECMP, and can be used to find optimal voltage zone control schemes to achieve improved wafer-level uniformity.

关键词： CMP Cu electrochemical synthesis

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High Temperature Implantation in Graphite

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MRS Online Proceedings Library (OPL) 2011年第1期27卷 475-475页

作者： G. Braunstein B.S. Elman M.S. Dresselhaus G. Dresselhaus T. Venkatesan Department of Physics Department of Electrical Engineering and Computer Science Francis Bitter National Magnet Laboratory Massachusetts Institute of Technology Cambridge MA 02139 USA Bell Laboratories Murray Hill NJ 07974 USA

In previous studies it was found that when highly oriented pyrolytic graphite (HOPG) is implanted at room temperature, the damage caused by the implantation could be completely annealed by heating the sample to temperatures higher than ∼ 2500°C. However at these high temperatures, the implanted species was found to diffuse out of the sample, as evidenced by the disappearance of the impurity peak in the Rutherford backscattering (RBS) spectrum. If, on the other hand, the HOPG crystal was held at a high temperature (≥ 600°C) during the implantation, partial annealing could be observed. The present work further shows that it is possible to anneal the radiation damage and simultaneously to retain the implants in the graphite lattice by means of high temperature implantation (Ti ≥ 450°C) followed by annealing at 2300°C.

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Predicting Missing Provenance Using Semantic Associations in Reservoir engineering

Predicting Missing Provenance Using Semantic Associations in...

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International Conference on Semantic Computing

作者： Jing Zhao Karthik Gomadam Viktor Prasanna Computer Science Department University of Southern California USA Accenture Technology Laboratories USA Ming Hsieh Department of Electrical Engineering University of Southern California USA

Provenance is becoming an important issue as a reliable estimator of data quality. However, provenance collection mechanisms in the reservoir engineering domain often result in missing provenance information. In this paper, we address the problem of predicting missing provenance information in reservoir engineering. Based on the observation that data items with specific semantic "connections" may share the same provenance, our approach annotates data items with domain entities defined in a domain ontology, and represent these "connections" as sequences of relationships (also known as semantic associations) in the ontology graph. By analyzing annotated historical datasets with complete provenance information, we capture semantic associations that may imply identical provenance. A statistical analysis is applied to assign confidence values to the discovered associations, which indicate the trust of each association when it is used for future provenance prediction. The semantic associations, along with their confidence measures, are then used by a voting algorithm to predict the missing provenance information. Our evaluation shows that the average precision of our approach is above 85% when one third of the provenance information is missing.

关键词： Reservoirs Semantics Ontologies Data models Production Prediction algorithms Predictive models

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A $\beta$-${\rm Ga}_{2} {\rm O} _{3}$/GaN Hetero-Structured Solar-Blind and Visible-Blind Dual-Band Photodetector

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IEEE Sensors Journal 2011年第6期11卷 1491-1492页

作者： W. Y. Weng T. J. Hsueh S. J. Chang G. J. Huang H. T. Hsueh Institute of Microelectronics & Department of Electrical Engineering National Cheng Kung University Tainan County Taiwan National Nano Device Laboratories Tainan County Taiwan Institute of Microelectronics & Department of Electrical Engineering Institute of Nanotechnology Microsystems Engineering Advanced Optoelectronic Technology Center Center of Micro/Nano Science and Technology National Cheng Kung University Tainan County Taiwan Institute of Nanotechnology Microsystems Engineering National Cheng Kung University Tainan County Taiwan

The authors report the fabrication of a β-Ga 2 O 3 /GaN solar-blind and visible-blind dual-band photodetector (PD). It was found that we could control the depletion depth of the device and thus switch the operation mode between solar-blind and visible-blind by simply changing the applied bias. It was also found that we could achieve a deep-UV to near-UV contrast ratio of 4.6 × 10 3 when the device was biased at 1 V. Furthermore, it was found that near-UV to visible contrast ratio of the fabricated β-Ga 2 O 3 /GaN PD was 8.5 × 10 2 when biased at 10 V.

关键词： Gallium nitride Photodetectors Dual band Current measurement Furnaces Absorption

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Spatial inefficiency of MaxWeight scheduling

Spatial inefficiency of MaxWeight scheduling

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International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks

作者： Van De Ven, Peter Borst, Sem Ying, Lei Department of Mathematics and Computer Science Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven Netherlands EURANDOM P.O. Box 513 5600 MB Eindhoven Netherlands Bell Laboratories Alcatel-Lucent Murray Hill NJ 07974 United States Department of Electrical and Computer Engineering Iowa State University Ames IA 50011 United States

ISBN: (纸本)9781612848242

MaxWeight scheduling has gained enormous popularity as a powerful paradigm for achieving queue stability and maximum throughput in a wide variety of scenarios. The maximum-stability guarantees however rely on the fundamental premise that the system consists of a fixed set of flows with stationary ergodic traffic processes. In the present paper we examine networks where the population of active flows varies over time, as flows eventually end while new flows occasionally start. We show that MaxWeight policies may fail to provide maximum stability due to persistent inefficient spatial reuse. The intuitive explanation is that these policies tend to serve flows with large backlogs, even when the resulting spatial reuse is not particularly efficient, and fail to exploit maximum spatial reuse patterns involving flows with smaller backlogs. These results indicate that instability of MaxWeight scheduling can occur due to spatial inefficiency in networks with fixed transmission rates, which is fundamentally different from the inability to fully exploit time-varying rates shown in prior work. We discuss how the potential instability effects can be countered by spatial traffic aggregation, and describe some of the associated challenges and performance trade-offs. © 2011 IEEE.

关键词： Scheduling

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