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Inhibition of negative differential resistance in modulation-doped n-type GaxIn1−xNyAs1−y∕GaAs quantum wells

Physical Review B 2007年第20期75卷 205316-205316页

作者： Y. Sun M. P. Vaughan A. Agarwal M. Yilmaz B. Ulug A. Ulug N. Balkan M. Sopanen O. Reentilä M. Mattila C. Fontaine A. Arnoult Department of Electronic System Engineering University of Essex Wivenhoe Park Colchester CO4 3SQ United Kingdom Faculty of Arts & Science Department of Physics Akdeniz University Antalya Turkey Micro and Nanosciences Laboratory Helsinki University of Technology P.O. Box 3500 Helsinki 02015 Finland Laboratory for Analysis and Architecture of System 7 Avenue du Colonel Roche 31077 Toulouse Cedex 4 France

We present the results of hot-electron momentum relaxation studies for longitudinal transport in modulation doped GaxIn1−xNyAs1−y∕GaAs quantum wells. Experimental results show that the high field drift velocity saturates at a value close to 1×107cm∕s with no evidence for negative differential resistance or instabilities. Experimental results are compared with a simple theoretical model for transport taking into account the effect of nonequilibrium phonon production. Model calculations indicate that enhanced momentum scattering for electrons with nondrifting hot phonons may be the cause for the reduction in drift velocity.

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Size of Defect Clusters in Lithium Niobate Single Crystals

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Journal of Rare Earths 2006年第z1期24卷 253-256页

作者： He Xiangke Xue Dongfeng State Key Laboratory of Fine Chemicals Department of Materials Science and Chemical Engineering School of Chemical Engineering Dalian University of Technology Dalian 116012 China Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian 116023 China State Key Laboratory of Fine Chemicals Department of Materials Science and Chemical Engineering Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian 116023 China

On the basis of the Li-site vacancy model, the non-stoichiometric defects in LN crystals, i.e., anti-site defects NbLi and corresponding lithium vacancy defects VLi, were investigated by the bond valence model. According to the valence sum rule, 4 VLi sites must emerge in the nearest lattices of NbLi, and thus form a neutral cluster with the center, NbLi(VLi)4Nb5O15. The bond graph of the defect cluster was given, which reveals the ideal chemical bonding characteristics of defect clusters. Combining the possible configuration of defect clusters and the ideal bond lengths in the bond graph, the size of defect clusters in the LN crystallographic frame is estimated as 0.9～1.2 nm in diameter.

关键词： lithium niobate defect cluster defect size bond valence model

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Dopant Occupancy in MgO-Codoped Lithium Niobate Crystals

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Journal of Rare Earths 2006年第z1期24卷 276-280页

作者： He Xiangke Xue Dongfeng State Key Laboratory of Fine Chemicals Department of Materials Science and Chemical Engineering School of Chemical Engineering Dalian University of Technology Dalian 116012 China Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian 116023 China State Key Laboratory of Fine Chemicals Department of Materials Science and Chemical Engineering School of Chemical Engineering Dalian University of Technology Dalian 116012 China Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology Dalian 116023 China

On the basis of the bond valence model, the preferential occupancy of various dopant such as Mn2+, Eu3+, Er3+, Nd3+, Lu3+, Yb3+, In3+, Cr3+, Fe3+ and Ti4+ in the ideal stoichiometric lithium niobate (SLN) crystallographic frame was investigated in a viewpoint of chemical bonds. Theoretical analysis indicates that the dopant occupancy is significantly influenced by the anti-site Nb4+Li. Our work also shows that Mg-like ions (Mg2+, Zn2+, In3+, Sc3+) have a repulsive effect on Nb4+Li ions. When removing Nb4+Li ion by codoping Mg-like ions, the dopant occupancy in the LN crystallographic frame is determined by the natural characteristics of dopant, which is consistent well with the result in the ideal SLN crystals.

关键词： lithium niobate bond valence model codoping dopant occupancy

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Improvement of Electrical Properties of the Ge2Sb2Te5 Film by Doping Si for Phase-Change Random Access Memory

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Chinese Physics Letters 2006年第1期23卷 172-174页

作者：乔保卫冯洁赖云锋凌云林殷茵汤庭鳌蔡炳初陈邦明 National Key Laboratory of Nano/Micro Fabrication Technology Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education Institute of Micro and Nano Science and Technology Shanghai Jiaotong University Shanghai 200030 State Key Laboratory of ASIC & System Fudan University Shanghai 200433 Silicon Storage Technology Inc. 1171 Sonora Court Sunnyvale CA94086 USA

Si-doped Ge2Sb2Te5 films have been prepared by dc magnetron co-sputtering with Ge2Sb2Te5 and Si targets. The addition of Si in the Ge2Sb2Te5 film results in the increase of both crystallization temperature and phasetransition temperature from face-centred-cubic （fcc） phase to hexagonal （hex） phase. The resistivity of the Ge2Sb2Te5 film shows a significant increase with the Si doping. When doping 11.8 at.% of Si in the film, the resistivity after 460℃ annealing increases from 1 to 11 mΩ.cm and dynamic resistance increase from 64 to 99Ω compared to the undoped Ge2Sb2Te5 film. This is very helpful to writing current reduction of phase-change random access memory.

关键词： NONVOLATILE MEMORY THIN-FILMS RESISTANCE ALLOYS

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A dual axis accelerometer utilizing low doped silicon thermistor

A dual axis accelerometer utilizing low doped silicon thermi...

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作者： Van Dau, Thanh Dao, Dzung Viet Hayashida, Masahiro Dinh, Thien Xuan Sugiyama, Susumu Ritsumeikan University 1-1-1 Noji Higashi Kusatsu Shiga 525-8577 Japan Faculty of Mechanical Engineering HUT Ritsumeikan University Japan Micro Nano Integrated Devices Laboratory Ritsumeikan University Ritsumeikan University Ritsumeikan University Shiga Japan College of Science and Engineering Department of Micro System Technology Research Institute for Micro System Technology Ritsumeikan University

This paper presents the development of a dual axis convective microaccelerometer, whose working principle is based on the convective heat transfer and thermo-resistive effect of lightly-doped silicon. Different with developed convective accelerometer, the sensor utilizes a novel structure of the sensing element which can reduce 93% of thermal-induced stress. Moreover, the thermistors are made from low-doped p-type silicon, which has the TCR higher than that of metals and poly-silicon convective accelerometer. By using numerical method, the chip dimensions and the package size arc optimized. The sensitivity of the sensor was simulated;other characteristics such as frequency response, shock resistance, noise problem are also deeply investigated. The sensor has been fabricated by MEMS process and characterized by experiments.

关键词： Thermistors

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Multi-rate transmissions on SAC-OCDMA system using new enhancement double-weight (EDW) codes 2

Multi-rate transmissions on SAC-OCDMA system using new enhan...

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2nd International Conference on Information and Communication Technologies: From Theory to Applications, ICTTA 2006

作者： Hasoon, Feras N. Aljunid, S.A. Abdullah, Mohamad Khazani Shaari, Sahbudin Faculty of Information Science and Technology Multimedia Universit Melaka Malaysia Department of Computer and Communication System Faculty of Engineering University Putra Malaysia UPM Serdang43400 Malaysia Photonics Technology Laboratory Institute of Micro Engineering and Nanoelectronics Universiti Kebangsaan Malaysia UKM Bangi Selangor43600 Malaysia

ISBN: (纸本)0780395212

This paper presents a new code structure and its ability in supporting multiple transmission rates in point to point Spectral Amplitude Coding- Optical Code Division Multiple Access (SAC-OCDMA) links. The Double-Weight (DW) code family that has a basic fixed weight of 2 was proposed. Enhancement Double Weight (EDW) Code is a DW code family variation that has variable weight of greater than one. The ability of EDW codes to support simultaneous transmissions at different bit rates is shown through simulated results of the bit error rate (BER) and the eye patterns. Three EDW encoded channels were used at the bit rates of 2.5Gbps and 10Gbps. EDW code shown here significantly performs better than Hadamard and Modified Frequency Hopping (MFH) codes. © 2006 IEEE.

关键词： Bit error rate

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Continuous-flow polymerase chain reaction microfluidics based on polytetrafluoethylene capillary

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Chinese Journal of Analytical Chemistry 2006年第8期34卷 1197-1203页

作者： Chunsun, Zhang Jinliang, Xu Jianqin, Wang Hanping, Wang Micro Energy System Laboratory Guangzhou Institute of Energy Conversion the Chinese Academy of Sciences Guangzhou 510640 China Department of Thermal Science and Energy Engineering University of Science and Technology of China Hefei 230026 China Department of Dermatology Guangzhou First Municipal People's Hospital Guangzhou 510180 China Core Laboratory Guangzhou First Municipal People's Hospital Guangzhou 510180 China

The polytetrafluoroethylene (PTFE) capillary-based continuous-flow polymerase chain reaction (PCR) microfluidics were constructed by the flexible thin film heaters to form three constant temperature zones necessary for a PCR amplification, in which the PCR mixture could flow through the capillary mcirochannel continuously, thus leading to the successful completion of PCR exponential amplification. The effects of various concentrations of bovine serum albumin (BSA) in a 25-μl PCR mixture and flow rates of PCR mixture in the capillary microchannel, on continuous-flow PCR amplification, had been discussed in detail, where a PCR amplification of 249-bp human β-actin gene fragments was successfully performed within 15 and even 10 minutes, which is several times faster than the reaction time required (1-2 hours) with the conventional PCR machine. © 2006 Changchun Institute of Applied Chemistry, Chinese Academy of sciences.

关键词： Capillary Continuous-flow polymerase chain reaction microfluidics

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Development of electrostatic actuated nano tensile testing device for mechanical and electrical characteristics of FIB deposited carbon nanowire

Development of electrostatic actuated nano tensile testing d...

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2006 MRS Spring Meeting

作者： Kiuchi, Mario Matsui, Shinji Isono, Yoshitada Graduate School of Science and Engineering Ritsumeikan University 1-1-1 Nojihigashi Kusatsu Shiga 525-8577 Japan Laboratory of Advanced Science and Technology for Industry University of Hyogo 3-1-2 Koto Kamigori Ako Hyogo 678-1201 Japan CREAST JST Japan Science and Technology Agency Kawaguchi Center Building 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan Department of Micro System Technology Faculty of Science and Engineering Ritsumeikan University 1-1-1 Nojihigashi Kusatsu Shiga 5258577 Japan

ISBN: (纸本)1558998810

This research develops Electrostatic Actuated NAno Tensile testing devices (EANATs) to evaluate mechanical and electrical properties of carbon nanowires fabricated by focus ion beamassisted chemical vapor deposition (FIB-CVD). This research carried out nanoscale uniaxial tensile tests for 90 nm- to 150 nm-diametric carbon nanowires using EANATs. Young's modulus of cabon nanowires averaged 58 GPa, which was close to that of hydrogenated diamond-like carbon films. On average, fracture stress and strain of carbon nanowires reached values of 4.2 GPa and 0.08, respectively. This research also measured I-V characteristics of 100 nm-diametric carbon nanowires under tensile loading to reveal the piezo resistivity of nanowires. The piezoresistive effect of carbon nanowire was observed. The tensile load was about 0.75 GPa at maximum value of the resistance change. © 2006 Materials Research Society.

关键词： Nanowires

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Development of Electrostatic Actuated Nano Tensile Testing Device for Mechanical and Electrical Characteristics of FIB Deposited Carbon Nanowire

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MRS Online Proceedings Library 2006年第1期924卷 1-6页

作者： Mario Kiuchi Shinji Matsui Yoshitada Isono Graduate School of Science and Engineering Ritsumeikan University Kusatsu Shiga Japan Laboratory of Advanced Science and Technology for Industry University of Hyogo Kamigori Ako Hyogo Japan CREAST JST Japan Science and Technology Agency Honcho Kawaguchi Saitama Japan Department of Micro System Technology Faculty of Science and Engineering Ritsumeikan University Kusatsu Shiga Japan

This research develops Electrostatic Actuated NAno Tensile testing devices (EANATs) to evaluate mechanical and electrical properties of carbon nanowires fabricated by focus ion beam-assisted chemical vapor deposition (FIB-CVD). This research carried out nanoscale uniaxial tensile tests for 90 nm- to 150 nm-diametric carbon nanowires using EANATs. Young’s modulus of cabon nanowires averaged 58 GPa, which was close to that of hydrogenated diamond-like carbon films. On average, fracture stress and strain of carbon nanowires reached values of 4.2 GPa and 0.08, respectively. This research also measured I-V characteristics of 100 nm-diametric carbon nanowires under tensile loading to reveal the piezo resistivity of nanowires. The piezoresistive effect of carbon nanowire was observed. The tensile load was about 0.75 GPa at maximum value of the resistance change.

关键词： piezoelectric nanoscale ion-beam assisted deposition

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Design and fabrication of polymer electrostatic comb-drive actuators for micro conveyer systems

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IEEJ Transactions on Sensors and micromachines 2006年第7期126卷 306-311页

作者： Pham, Phuc Hong Dao, Dzung Viet Amaya, Satoshi Kitada, Ryoji Li, Yigui Sugiyama, Susumu Ritsumeikan University 1-1-1 Nojihigashi Kusatsu Shiga 525-8577 Japan TOWA Corporation 122-2 Megawa Makisima Uji Kyoto 611-0041 Japan Graduate School of Science and Engineering Ritsumeikan University TOWA Corporation Faculty of Mechanical Engineering HUT Micro Nano Integrated Devices Laboratory Ritsumeikan University Japan Micro Nano Integrated Devices Laboratory Ritsumeikan University Ritsumeikan University Ritsumeikan University Shiga Japan College of Science and Engineering Department of Micro System Technology Research Institute for Micro System Technology Ritsumeikan University

We propose the design, simulation and preliminary fabrication of micro Conveyer systems (MCS) based on polymer electrostatic comb-drive actuators using polymethylmethacrylate (PMMA). This MCS consists of linear comb actuators, rotational comb actuators, micro containers, and a ratchet mechanism. micro containers, used for carrying micro and nano samples such as protein, cells, are moved by comb-actuators through the ratchet mechanism. The silicon MCS was fabricated and checked to confirm characteristics and working principles. Each PMMA MCS, which has dimension of 1×1 cm2, will be fabricated by using hot embossing technique or X-ray lithography. A silicon mold has to be fabricated first by using silicon wafer and ICP-RIE process. Salient advantages of PMMA comb-drive actuators are low cost, high throughput and consuming less energy compared with the counterpart using silicon because PMMA has a lower Young's modulus.

关键词： microactuators

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