组合多量阱的发光特性研究

通过在７７Ｋ时对ＺｎＣｄＳｅ－ＺｎＳｅ组合多量子阱结构的发光特性的测量,我们观测到了分别来自两组量子阱的激光发光,其跃迁能量与采用包络函数法计算的结果相符。由于两组量子阱之间注入效应的存在,使得两组量子阱在变密度激发和时间分辨光谱中表现出不同的发光特性。     

ZnCdSe/ZnSe单量子阱中的双激子发光谱

在分子束外延生长的ＺｎＣｄＳｅ／ＺｎＳｅ单量子阱结构中,观察到了双激子发光谱．采用不同宽度的量子阱,得出了双激子束缚能与量子阱宽度的依赖关系．研究了双激子发光谱与激发光波长和激发功率的关系．发现在阱内激发的条件下,自由激子更容易由于相互作用而形成双激子,在～１ｍＷ／ｃｍ２的激发功率密度下即可观察到明显的双激子发光．     

ZnSe/ZnCdSe多量子阱激子光学非线性

本文采用泵浦－探测技术研究了ＺｎＳｅ／ＺｎＣｄＳｅ多量子阱室温激子饱和吸收，并根据Ｋ－Ｋ关系计算得到５２１．６ｎｍ至５４４ｎｍ的光学非线性折射率的变化．观测到由折射率变化引起的ＺｎＳｅ／ＣｄＺｎＳｅ多量子阱光双稳器件的室温激子光双稳．根据ＺｎＳｅ／ＺｎＣｄＳｅ多量子阱的激子吸收谱及激子的非线性理论，归结其主要非线性机制为激子态的相空间填充和激子带展宽．     

杂质对生长SiGe／Si量子阱发光材料的影响

发现Ｓｉ源和Ｇｅ源中的深能级杂质是影响ＳｉＧｅ／Ｓｉ量子阱带边激子发光的主要因素，研究了在低阻衬底上外延，在量子阱中重掺Ｓｂ或顶层中重掺Ｂ都将减弱甚至淬灭量子阱的带边激子发光。     

ZnCdSe—ZnSe／CaF2多量子阱中的三阶非线性

我们首次利用Ｚ－扫描技术在室温下研究了ＺｎＣｄＳｅ－ＺｎＳｅ／ＣａＦ２多量子了进中的三阶非线性，得到非线性系数ｎ２为－４．４６×１０＾－８ｅｓｕ。其主要非线性机理归结为ＺｎＣｄＳｅ－ＺｎＳｅ／ＣａＦ２多量子阱中的带填充效应。     

Zn_(1-x)Cd_xSe/ZnSe量子限制Stark效应光调制器

研究了Ｚｎ１－ｘＣｄｘＳｅ／ＺｎＳｅ多量子阱Ｓｔａｒｋ效应光调制器的研制及其在室温下的光学特性,包括透射谱、反射谱以及在不同外场作用下的微分透射谱和微分反射谱,指出了这类调制器目前可以达到的调制幅度,及可能的应用前景．     

ZnSe多量子阱横向磁阻的无接触测量

用微波无接触法测量了ＺｎＳｅ外延层和两种ＺｎＳｅ多量子阱样品的横向磁阻,在低磁场时,这三种样品都表现为负磁阻,并且也可以用Ｋｈｏｓｌａ和Ｆｉｓｃｈｅｒ的半经验表示式进行拟合,实验还发现了在两层ＺｎＳｅ超晶格之间的Ｚｎ＋Ｇａ单原子层也呈现为较大的负磁阻     

（ZnSe／Cdse）ZnSe／GaAs（001）多量子阱材料的X射线双晶衍

给出了通过测量３条Ｘ射线双晶衍射摇摆曲线计算多层外延材料各层成份、界面共格度及晶向偏角的方法，并对（ＣｄＳｅ／ＺｎＳｅ）ＺｎＳｅ／ＧａＡｓ（００１）多量子阱材料的结构、应变及界面进行了研究．结果表明：ＺｎＳｅ缓冲层与衬底之间的界面共格度接近干零，而多量子阱部分与缓冲层之间的界面接近完全共格，表明多量子阱结构有较好的结构完整性．缓冲层与衬底之间有晶向偏角，而多量子阱结构与缓冲层之间无晶向偏角．在复杂多量子阱材料的摇摆曲线上未见内周期的卫星衍射峰．多量子阱实际的生长厚度比设计厚度小２０％～３０％，说明生长过程中存在表面原子的逃逸，致使样品的不同部位存在组份、厚度的不均匀和局部的应变。还讨论了Ｘ射线衍射仪与双晶衍射仪在测定多量子阱结构时的差别．     

稀磁半导体Zn1—xMnxSe外延薄膜与超晶格的光学特性的研究

用分子束外管生长了不同组分ｘ的Ｚｎ１－ｘＭｎｘＳｅ外延膜和Ｚｎ１－ｘＭｎｘＳｅ／ＺｎＳｅ超晶格，由于Ｚｎ１－ｘＭｎｘＳｅ的能隙Ｅｇ随组分变化在爸组分区形成弓形，且弓形的范围随温度变化的反常特性，首次在光致发光谱（ＰＬ）中观测到当温度升高时，Ｚｎ１－ｘＭｎｘＳｅ／ＺｎＳｅ超晶格中由ＺｎＳｅ为阱、Ｚｎ１－ｘＭｎｘＳｅ为垒转换成Ｚｎ－１ｘＭｎｘＳｅ为阱，ＺｎＳｅ为垒，瞬态光致发光结果表明，Ｚｎ１－ｘＭｎ     

静压下（CdSe）m／（ZnSe）n—ZnSe超短周期超晶格量子阱的共振…

在静压和液氮温度下观察到（ＣｄＳｅ）ｍ／（ＺｎＳｅ）ｎ短周期超晶格中重空穴激子的复合发光和多达４阶的类ＺｎＳｅＬＯ多声子喇曼散射，并观察到厚ＺｎＳｅ势垒层的带边发光和限制在厚势垒层中的类ＺｎＳｅＬＯ声子散射。结果表明，加压后（ＣｄＳｅ）ｍ／（ＺｎＳｅ）ｎ短周期超晶格中的类ＺｎＳｅ的１ＬＯ和２ＬＯ声子模频率分别以３．７６和７．１１ｃｍ＾－１／ＧＰａ的速率向高频方向移动，超晶格阱层光致发光峰的压力系数     

X-ray metrology for high-k atomic layer deposited HfxZr1−xO2 films

Hafnium-based dielectrics are the most promising material for SiO₂ replacement in future nodes of CMOS technology. While devices that utilize HfO₂ gate dielectrics suffer from lower carrier mobility and degraded reliability, our group has recently reported improved device characteristics with a modified Hf_xZr_1−xO₂ [R.I. Hegde, D.H. Triyoso, P.J. Tobin, S. Kalpat, M.E. Ramon, H.-H. Tseng, J.K. Schaeffer, E. Luckowski, W.J. Taylor, C.C. Capasso, D.C. Gilmer, M. Moosa, A. Haggag, M. Raymond, D. Roan, J. Nguyen, L.B. La, E. Hebert, R. Cotton, X.-D. Wang, S. Zollner, R. Gregory, D. Werho, R.S. Rai, L. Fonseca, M. Stoker, C. Tracy, B.W. Chan, Y.H. Chiu, B.E. White, Jr., in: Technical Digest - International Electron Devices Meet, vol. 39, 2005, D.H. Triyoso, R.I. Hegde, J.K. Schaeffer, D. Roan, P.J. Tobin, S.B. Samavedam, B.E. White, Jr., R. Gregory, X.-D. Wang, Appl. Phys. Lett. 88 (2006) 222901]. These results have lead to evaluation of X-ray reflectivity (XRR) for monitoring high-k film thickness and control of Zr addition to HfO₂ using measured film density. In addition, a combination of XRR and spectroscopic ellipsometry (SE) is shown to be a fast and non-intrusive method to monitor thickness of interfacial layer between high-k and the Si substrate.     

Students’ thoughts about the importance and costs of their mobile devices’ features and services

In recent years, handheld devices have become one of the fastest growing communication gadgets. Mobile technology is becoming widespread and research in this area is urgently needed. Using a survey instrument, the thoughts of male and female students regarding the importance and costs of mobile devices were investigated. It was found that students tend to consider the following features important: battery life, mp3 player, video camera, photo camera, storage memory, Bluetooth, design and elegance, clock, calendar, organizer and reminder. Also, they are eager to spend an amount of money so as their mobile device to support them. On average, both genders would pay extra money for such features. However, the majority of females think less of the price than males do. On the contrary, most of the respondents do not consider the following important: touch screen, voice commands, chat, teleconference, encryption and cryptography, common use of files, printing. Therefore, they would not spend any money for these features. Interested decision makers would try to increase their interest on such features. Moreover, all respondents appear to own a mobile phone while most of them do not have Internet connection at home. In general, some gender differences are found in the importance and costs of the mobile devices, but they are not statistically significant.     

Job schedulers for Big data processing in Hadoop environment: testing real-life schedulers using benchmark programs

At present, big data is very popular, because it has proved to be much successful in many fields such as social media, E-commerce transactions, etc. Big data describes the tools and technologies needed to capture, manage, store, distribute, and analyze petabyte or larger-sized datasets having different structures with high speed. Big data can be structured, unstructured, or semi structured. Hadoop is an open source framework that is used to process large amounts of data in an inexpensive and efficient way, and job scheduling is a key factor for achieving high performance in big data processing. This paper gives an overview of big data and highlights the problems and challenges in big data. It then highlights Hadoop Distributed File System (HDFS), Hadoop MapReduce, and various parameters that affect the performance of job scheduling algorithms in big data such as Job Tracker, Task Tracker, Name Node, Data Node, etc. The primary purpose of this paper is to present a comparative study of job scheduling algorithms along with their experimental results in Hadoop environment. In addition, this paper describes the advantages, disadvantages, features, and drawbacks of various Hadoop job schedulers such as FIFO, Fair, capacity, Deadline Constraints, Delay, LATE, Resource Aware, etc, and provides a comparative study among these schedulers.     

Progress in ZnO materials and devices

ZnO is a wide-band-gap semiconductor material that is now being developed for many applications, including ultraviolet (UV) light-emitting diodes, UV photodetectors, transparent thin-film transistors, and gas sensors. It can be grown as boules, as thin films, or as nanostructures of many types and shapes. However, as with any useful semiconductor material, its electrical and optical properties are controlled by impurities and defects. Here, we consider various important donor-type impurities, such as H, Al, Ga, and In, and acceptor-type impurities, such as N, P, As, and Sb. We also examine the effects of a few common point defects, including Zn interstitials, Zn vacancies, O vacancies, and complexes of each. The main experimental techniques of interest here include temperature-dependent Hall-effect and low-temperature photoluminescence measurements, because they alone can provide donor and acceptor concentrations and donor energies. The important topic of p-type ZnO is also considered in some detail.     

Thyristor Input-Protection Device Suitable for CMOS RF IC’s

Based on simulation results and accompanying analysis, we suggest a thyristor-type ESD protection device structure suitable for implementation in standard CMOS processes to reduce the parasitic capacitances added to the input nodes, which is very important in CMOS RF ICs. We compare DC breakdown characteristics of the suggested device to those of a conventional NMOS protection device to show the benefits of using the suggested device for ESD protection. The characteristic improvements are demonstrated and the corresponding mechanisms are explained based on simulations. Structure dependencies are also examined to define the optimal structure. AC simulation results are introduced to estimate the magnitude of reduction in the added parasitic capacitance when using the suggested device for ESD protection. The analysis shows a possibility of reducing the added parasitic capacitance down to about 1/45 of that resulting with a conventional NMOS protection transistor, while maintaining robustness against ESD.Jin-Young Choi was born in Seoul, Korea in 1956. He received the B.S. degree in electrical engineering from the Seoul National University, Korea, in 1979, and the M.S. and Ph.D. degrees in electrical engineering from the University of Florida, USA, in 1986 and 1991, respectively. In 1991, he joined Samsung Electronics Memory Division, Korea, where he was engaged in high-speed SRAM development. In 1992, he moved to the Hongik University, Jochiwon, Korea, where he is now an associate professor. His recent research interests include the high-frequency modeling of CMOS devices, CMOS RF circuit design, and analysis & design for ESD protection.Woo Suk Yang was born in Seoul, Korea in 1957. He received the B.S. degree in electrical engineering from the Seoul National University, Korea, in 1979, and the Ph.D. degree in electrical and computer engineering from the North Calorina State University, USA, in 1990. His doctorial research was in the area of signal processing. In 1990, he joined LG Electronics Co. Korea. In 1991, he moved to the Hongik University, Jochiwon, Korea, where he is now a professor. His recent research interests include the high-frequency modeling and various topics in signal processing area.Dongmin Kim was born in Korea in 1956. He received the B.S. and M.S. degrees in electrical engineering from the Seoul National University, Korea, in 1979 and 1984, respectively and the Ph.D. degree in ECE from the University of Michigan, USA, in 1996. Now, he is an assistant professor of the Hongik University, Jochiwon, Korea. His recent research interests include circuit design and analysis.Youngju Kim was born in Seoul, Korea in 1957. He received the B.S. and M.S. degrees in electrical engineering from the Seoul National University, Korea in 1980 and 1985, respectively and the Ph.D. degree in electrical engineering from the Polytechnic University of New York, USA, in 1995, respectively. In 1996, he joined the Hongik University, Jochiwon, Korea, where he is now an assistance professor. His recent research interests include the RF circuit design and LIN wireless systems.     

智能语音操控在广电端到端的系统设计及应用

在数字化中国的大背景下,在公司个人宽带与互动电视在线交费用户均突破300万户的情况下,为解决我们的用户总找不到自己喜欢看的节目,记不住频道名称和喜欢的节目,提升公司竞争力。通过对前端的点播系统、AAA系统、EPG系统、PORTAL系统、ISMP系统、媒资系统、机顶盒终端的功能进行剥离、整合和详细设计,最后完成终端用户语音操控电视直播、点播、时移、回看、页面操控、系统设置,并支持普通话和四川话方言的目的。达到提升用户体验,增加公司竞争力,促进业务的发展。系统试运行后,用户体验效果得到很大提升,完全达到预期设计目的。     

谈对电子元器件企业设计开发过程中“六性”的审核

通过对电子元器件企业＂可靠性、维修性、保障性、测试性、安全性和环境适应性＂的审核,帮助企业识别＂可靠性、维修性、保障性、测试性、安全性和环境适应性＂,认识＂可靠性、维修性、保障性、测试性、安全性和环境适应性＂在产品设计开发中的重要性,实现产品的＂可靠性、维修性、保障性、测试性、安全性和环境适应性＂指标。     

A Progress Report on Metal–Sulfur Batteries

Nonaqueous conversion‐reaction sulfur chemistry has been attracting increasing attention over the past decade for the development of next‐generation lithium‐based batteries. Li–S batteries are currently approaching a nexus stage from lab‐scale experiments to possible pragmatic applications. Inspired by the success of Li–S chemistry, other metal–sulfur batteries with a variety of metallic anodes, such as sodium, potassium, magnesium, calcium, and aluminum, have also started to attract attention. In comparison to lithium, Na, Mg, Al, K, and Ca are naturally more abundant and affordable. The Na‐S, Mg‐S, Al‐S, K‐S, and Ca‐S battery systems provide a great potential for improving the volumetric energy density of sulfur‐based batteries. The multivalent metal‐sulfur systems, Mg‐S, Al‐S, and Ca‐S, offer better safety features as well. However, the research and development on Na‐S, Mg‐S, Al‐S, K‐S, and Ca‐S batteries is far behind the Li–S system due to many critical challenges. In this progress report, the fundamental principles of various metal–sulfur chemistries are first presented and compared. Then, the historical progress, recent advances, and key challenges of the Li–S, Na‐S, Mg‐S, Al‐S, K‐S, and Ca‐S systems are summarized and discussed. Finally, future efforts and directions for both the fundamental and practical research are prospected.     

VoIP技术--语音和数据的集成

介绍了VoIP(Voice over IP)的基本组成构件即网关(Gateway)、网守(Gatekeeper)的概念和用途。讲述了语音在IP网上传输的基本原理，语音和数据、数据和IP包之间的转换和传送过程。在H．323协议栈的基础上详细讲述了H．248，H．225，H．245等通信协议和语音编码G．729，G．23l，G．7ll等协议。最后对VoIP的语音服务质量作了较为详细的阐述。     

An Integrated Model to Design PCS Networks

An integrated model is proposed that comprises essentially, an Enhanced Profile-Based Strategy (EPBS) for small-scale roaming and a Caching Two-Level Forwarding Pointer (C2LFP) strategy for large-scale roaming. The idea behind the integrated model is how those two location management solutions are applied, and what is the suitable approach to specify the physical parameters of PCS networks from mobility management’s point of view so that our solutions can be more cost effective for location management. An evolutionary method, using a constrained Genetic Algorithm (GA) has been used to achieve network parameters optimization. For convenience, we selected the underlying planning problem with an appropriate set of parameters so that it can be treated, in what follows, both genetically and analytically. Thus one can easily verify the accuracy and efficiency of the evolutionary solution that would be obtained from the genetic algorithm. For more realistic environments, GA could be used reliably to build up sophisticated models that integrate the small-scale and large-scale roaming parameters of PCS networks. The results that have been obtained from a case study are presented in order to provide a deep explanation for the proposed integration approach. Salah M. Ramadan (samohra@yahoo.com) received the BS and MS degrees from Computers Engineering Department, Al-Azhar University, Cairo, Egypt, in 1995 and 2002, respectively. From 2002, he was a PhD student in Computers Engineering Department at Al-Azhar University and is currently pursuing the PhD degree, where he is a research assistant in the Wireless Networks Branch. His research interests include traffic management in ATM networks, routing protocols, mobility management in PCS networks, and mobile computing. He is currently an instructor in Cisco Academy, Egypt. Ahmed M. El-Sherbini (Sherbini@mcit.gov.eg) received the Ph.D. in Electrical and Communication Engineering, Case Western University, U.S.A. March 1983 and M.Sc. in Communication Engineering, Cairo University, Giza, Egypt, June 1980. (M.Sc. Research Studies at the Ecole Nationale Superieure des Telecommunications (ENST), Paris, France) He is the Director, National Telecommunication Institute – Ministry of Communications and Information Technology, Egypt and Professor of Electrical and Communication Engineering Dept. Faculty of Engineering, Cairo University, Egypt. M. I. Marie(azhar@mailer.scu.eun.eg) received his B.Sc, M.Sc and PhD in electronic and communication engineering from Cairo University on 1972, 1981, 1985, respectively. Now he is a professor of communications at Computer and System Engineering Department Al-Azhar University, Cairo, Egypt. His fields of interest includes digital communication, computer networks and protocols development. M. Zaki is the professor of software engineering, Computer and System Engineering Department, Faculty of Engineering, Al-Azhar University at Cairo. He received his B.Sc. and M.Sc. degrees in electrical engineering from Cairo University in 1968 and 1973 respectively. He received his Ph.D. degrees in computer engineering from Warsaw Technical University, Poland in 1977. His fields of interest include artificial intelligence, soft computing, and distributed system.