Showing papers by "NEC published in 2009"

Semiconductor device and manufacturing method thereof

Abstract: A semiconductor device includes: a silicon substrate; and a field effect transistor including a gate insulating film over the silicon substrate, a gate electrode on the gate insulating film, and source and drain regions. The gate electrode includes, in part in contact with the gate insulating film, a crystallized Ni silicide region containing an impurity element of a conductivity type opposite to a conductivity type of a channel region in the field effect transistor.

Availability Modeling and Analysis of a Virtualized System

Abstract: This paper develops an availability model of a virtualized system. We construct non-virtualized and virtualized two hosts system models using a two-level hierarchical approach in which fault trees are used in the upper level and homogeneous continuous time Markov chains (CTMC) are used to represent sub-models in lower level. In the models, we incorporate not only hardware failures (e.g., CPU, memory, power, etc) but also software failures including Virtual Machine Monitor (VMM), Virtual Machine (VM), and application failures. We also incorporate high availability (HA) service and VM live migration in the virtualized system. Metrics we use are system steady state availability, downtime in minutes per year and capacity oriented availability.

Method of controlling wireless communication system and wireless communication system

Abstract: A method of controlling a wireless communication system including a plurality of communication devices is disclosed. In the method, firstly, one of the communication devices establishes a fixed beam pattern and transmits a training signal, and another communication device receives the training signal while scanning a beam direction by changing the AWVs of an antenna array. Next, it obtains a data string describing a relation between an incoming direction and a received-signal characteristic at the other communication device based on a reception result of the training signal. Then, it obtains first AWVs with which a beam is formed in a plurality of incoming directions of the received signal based on the data string. The roles of these two communication devices are interchanged and similar processes are performed in order to obtain second AWVs, and then one of AWV combinations combining first and second AWVs are used for wireless communication between these communication devices.

In situ and real-time monitoring of oxide growth in a few monolayers at surfaces of platinum nanoparticles in aqueous media.

Abstract: The electrochemical oxidation behaviors of the surfaces of platinum nanoparticles, one of the key phenomena in fuel cell developments, were investigated in situ and in real time, via time-resolved hard X-ray diffraction and energy dispersive X-ray absorption spectroscopy. Combining two complementary structural analyses, dynamical and inhomogenous structural changes occurring at the surfaces of nanoparticles were monitored on an atomic level with a time resolution of less than 1 s. After oxidation at 1.4 V vs RHE (reversible hydrogen electrode) in a 0.5 M H(2)SO(4) solution, longer Pt-O bonds (2.2-2.3 A that can be assigned to OHH and/or OH species) were first formed on the surface through the partial oxidation of water molecules. Next, these species turned to shorter Pt-O bonds (2.0 A, adsorbed atomic oxygen), and atomic oxygen was incorporated into the inner part of the nanoparticles, forming an initial monolayer oxide that had alpha-PtO(2)-like local structures with expanded Pt-Pt bonds (3.1 A). Finally, quasi-three-dimensional oxides with longer Pt-(O)-Pt bonds (3.5 A, precursor for beta-PtO(2)) grew on the surface, at almost 100 s after oxidation. Despite the very complex oxidation mechanism on the atomic level, XANES analysis indicated that the charge transfer from platinum to the adsorbed oxygen species was almost constant and rather small, that is, about 0.5 electrons per oxygen, up to two monolayers of oxygen. This means that ionic polarization hardly develops at this stage of the surface platinum's "oxide" growth.

Nonvolatile Magnetic Flip-Flop for Standby-Power-Free SoCs

Abstract: This paper presents a new nonvolatile magnetic flip-flop (MFF) for standby-power-critical applications. An MFF primitive cell for design libraries has been developed using 150 nm, 1.5 V CMOS and 240 nm MRAM processes. It has advantages over other nonvolatile flip-flops in high-speed store operations without endurance limitations. It also has high design compatibility with conventional CMOS LSI designs because it does not include any additional power lines and special transistors. A toggle frequency of 3.5 GHz was achieved by a SPICE simulation, which is comparable to that of a normal CMOS DFF in the same generation. The maximum frequency in a store operation was also estimated to be 500 MHz with 1-ns current width for the data backup. An MFF test chip, which includes 16-stage 8-bit shift register using MFFs, was fabricated with these processes. A 333 MHz store operation was measured without failed bits. The functional performance was sufficiently high to demonstrate the potential of MFFs, which helps to reduce the power dissipation of systems on chips (SoCs) dramatically.

Temperature-Dependent Transfer Characteristics of Amorphous InGaZnO4 Thin-Film Transistors

Abstract: The transfer characteristics of amorphous InGaZnO4 thin-film transistors (a-IGZO TFTs) were measured at temperatures ranging from 298 to 523 K in order to analyze the behavior of the above-threshold (ON state) and subthreshold regions. For comparison, the transfer characteristics of a hydrogenated amorphous silicon TFT (a-Si:H TFT) were measured in the same temperature range. We developed a simple analytical model that relates the threshold voltage (Vt) decrease due to increasing temperature to the formation of point defects in a-IGZO. It is well known that the formation of point defects results in the generation of free carriers in oxide semiconductors. Incorporating the analytical model with the experimental transfer characteristics data taken at high temperatures over 423 K, we estimated the formation energy to be approximately 1.05 eV. The Vt decrease because of the generation of point defects is peculiar to a-IGZO TFTs, which is not observed in a-Si:H TFTs. The results for the ON-current activation energy suggested that the density of tail states for a-IGZO is much lower than that for a-Si:H.

Presence system and information processing equipment, dynamic buddy list generation method in presence system, and presence notification destination controlling method and its program for use with presence system

Abstract: A presentity service client has a presentity that issues presence information to a presence service and a watcher which observes presence information for other presentities; a presence change rule holding part holds a presence change rule; and a presence calculating part changes the presence information for the presentity, using as a trigger a change in presence information of other presentities, based on the presence information of other presentity acquired by the watcher and in accordance with the presence change rule held by a presence change rules holding part.

Communication system, node device, communication method in the communication system, and program

Abstract: A communication system comprises: failure detection means that detects a failure on a first transmission path over which data transmission is being performed; transmission path setting means that, when the failure exists in a link or a node that is located immediately before its own node, sets a second transmission path as far as a transmission terminal node, the second transmission path that excludes a path from the transmission terminal node to a node that has detected the failure within the first transmission path; first failure notification means that transmits a failure notification signal as far as the transmission terminal node over the second transmission path; new path switching means that, upon receipt of the failure notification signal, switches a switch for data transmission so that a path for new data transmission is the same path as a transmission path for the failure notification signal; and data transmission means that, upon the transmission terminal node receiving the failure notification signal, switches the switch to the second transmission path and performs a new data transmission over the second transmission path.

Semiconductor device and manufacturing method thereof

Abstract: PROBLEM TO BE SOLVED: To provide a semiconductor device having a high-breakdown-voltage field effect transistor by alleviating an electric field concentration between a drain region and a gate electrode. SOLUTION: The semiconductor device 100 has, on a silicon substrate 110, an N well source region 170 and an N well drain region 160 formed apart from each other, and a gate electrode 130 provided while a gate insulating film 131 formed from above the N well source region 170 toward on the N well drain region 160 is interposed therebetween. Furthermore, a LOCOS oxide film 180a is formed on the surface of the silicon substrate 110 in the N well drain region 160, and the LOCOS oxide film 180a has a constricted portion in a sectional view and the gate electrode 130 is formed straddling the constricted portion. COPYRIGHT: (C)2009,JPO&INPIT

Comparison of Ultraviolet Photo-Field Effects between Hydrogenated Amorphous Silicon and Amorphous InGaZnO4 Thin-Film Transistors

Abstract: We discuss the ultraviolet (UV) photo-field effects in amorphous InGaZnO4 thin-film transistors (a-IGZO TFTs) compared with those in hydrogenated amorphous silicon (a-Si:H) TFTs. It is shown that the UV illumination induces a much more significant threshold voltage (Vt) decrease and OFF-current increase for the a-IGZO TFTs than for the a-Si:H TFTs. The significant Vt decrease is found to take several tens of min to return to the initial state after switching off the UV light. A qualitative model is introduced to explain the photoresponse unique to the a-IGZO TFTs.

Domain Wall Motion Induced by Electric Current in a Perpendicularly Magnetized Co/Ni Nano-Wire

Abstract: The authors show experimental results on domain wall motion induced by electric current in a Co/Ni nano-wire with perpendicular magnetic anisotropy. The motion was detected electrically by using the anomalous Hall effect. Threshold current density for the domain wall motion was found to decrease with decreasing the wire width, where the minimum threshold current density of approximately 5×1011 A/m2 was observed for the wire width of 70 nm.

Quantum teleportation scheme by selecting one of multiple output ports

Abstract: The scheme of quantum teleportation, where Bob has multiple $(N)$ output ports and obtains the teleported state by simply selecting one of the $N$ ports, is thoroughly studied. We consider both the deterministic version and probabilistic version of the teleportation scheme aiming to teleport an unknown state of a qubit. Moreover, we consider two cases for each version: (i) the state employed for the teleportation is fixed to a maximally entangled state and (ii) the state is also optimized as well as Alice's measurement. We analytically determine the optimal protocols for all the four cases and show the corresponding optimal fidelity or optimal success probability. All these protocols can achieve the perfect teleportation in the asymptotic limit of $N\ensuremath{\rightarrow}\ensuremath{\infty}$. The entanglement properties of the teleportation scheme are also discussed.

Compact, lower-power-consumption wavelength tunable laser fabricated with silicon photonic wire waveguide micro-ring resonators

Abstract: A wavelength tunable laser with an SOA and external double micro-ring resonator, which is fabricated with silicon photonic-wire waveguides, is demonstrated. To date, it is the first wavelength tunable laser fabricated with silicon photonic technology. The device is ultra compact, and its external resonator footprint is 700 x 450 microm, which is about 1/25 that of conventional tunable lasers fabricated with SiON waveguides. The silicon resonator shows a wide tuning range covering the C or L bands for DWDM optical communication. We obtained a maximum tuning span of 38 nm at a tuning power consumption of 26 mW, which is about 1/8 that of SiON-type resonators.

The Stanford OpenRoads deployment

Abstract: We have built and deployed OpenRoads [11], a testbed that allows multiple network experiments to be conducted concurrently in a production network. For example, multiple routing protocols, mobility managers and network access controllers can run simultaneously in the same network. In this paper, we describe and discuss our deployment of the testbed at Stanford University. We focus on the challenges we faced deploying in a production network, and the tools we built to overcome these challenges. Our goal is to gain enough experience for other groups to deploy OpenRoads in their campus network.

New analysis methods for comprehensive understanding of Random Telegraph Noise

Abstract: New analysis methods useful for understanding both complex waveforms and statistical behaviors of Random Telegraph Noise (RTN) are proposed. Complex waveforms are clearly visualized using Time Lag Plots. Bias dependence of statistically extracted average trap number is discussed, with emphasis on the importance of undetectable traps on product reliability.

Information processing device, display control method, and recording medium

Abstract: An information processing terminal (100) includes: a plurality of display parts (10, 20); a display control part (41) controlling the display operation of the display parts (10, 20); and an operation reception part (42) receiving an operation on display data displayed on the display parts (10, 20) The operation reception part (42) receives the entry of selection of a given area within the display data displayed on one (first) of the display parts The display control part (41) displays data associated in advance with the data within the selected area indicated by the entry of selection received by the operation reception part (42) on the other (second) display part that is different from the first display part

Language model creation apparatus, language model creation method, speech recognition apparatus, speech recognition method, and recording medium

Abstract: A frequency counting unit ( 15 A) counts occurrence frequencies ( 14 B) in input text data ( 14 A) for respective words or word chains contained in the input text data ( 14 A). A context diversity calculation unit ( 15 B) calculates, for the respective words or word chains, diversity indices ( 14 C) each indicating the context diversity of a word or word chain. A frequency correction unit ( 15 C) corrects the occurrence frequencies ( 14 B) of the respective words or word chains based on the diversity indices ( 14 C) of the respective words or word chains. An N-gram language model creation unit ( 15 D) creates an N-gram language model ( 14 E) based on the corrected occurrence frequencies ( 14 D) obtained for the respective words or word chains.

Recyclable shape-memory polymer: Poly(lactic acid) crosslinked by a thermoreversible Diels–Alder reaction

Abstract: An intelligent shape-memory polymer was made through the synthesis of poly(lactic acid) macromonomers with furanyl groups and crosslinking with linkers with maleimidyl groups. The thermoreversible covalent bonds formed by the Diels–Alder reaction between these groups made this polymer recyclable (i.e., environmentally friendly). The structure of the polymer was also studied. A defect of the structure, a dissociated moiety of the thermoreversible bonding, was strongly affected by the reaction conditions and was investigated with UV spectroscopy, which was used to monitor the concentration of the maleimidyl groups. The relation between the flexibility of the linker and the strength and inner stress of the polymer was also evaluated. Reducing the number of defects and relaxing the inner stress were found to increase the strength of the shape-memory polymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A normally-off GaN FET with high threshold voltage uniformity using a novel piezo neutralization technique

Abstract: In this paper, we successfully demonstrate a recessed gate normally-off GaN FET on a silicon substrate with high threshold voltage (V th ) uniformity and low on-resistance. In order to realize high V th uniformity, a novel V th control technique is proposed, which we call “piezo neutralization technique”. This technique includes a piezo neutralization (PNT) layer formed at the bottom of the gate recess. Since the PNT layer neutralizes the polarization charges under the gate, the V th comes to be independent of the gate-to-channel span. The fabricated normally-off GaN FET with PNT structure exhibits an excellent V th uniformity (σ(V th )=18 mV) and a state-of-the-art combination of the specific on-resistance (R on A=500 mΩmm2) and the breakdown voltage (V B ≫1000 V). The normally-off GaN FETs wtih PNT structure show great promise as power devices.

Semiconductor memory device

Abstract: The present invention provides a semiconductor memory device that includes: a fuse circuit having multiple fuse elements; and a fuse selection circuit connected to an internal address signal line that receives an address signal externally inputted. The fuse circuit is connected to the fuse selection circuit to receive an output from the fuse selection circuit, is supplied with an externally inputted trigger signal that permits nonvolatile recording of the fuse elements, and, in response to the output and the trigger signal, records the fuse element corresponding to the internal address signal line among the plurality of fuse elements while recording at least one of the plurality of fuse elements other than the fuse element thus recorded.

Method for manufacturing a semiconductor integrated circuit device circuit device

Abstract: When a natural oxide film is left at the interface between a metal silicide layer and a silicon nitride film, in various heating steps (steps involving heating of a semiconductor substrate, such as various insulation film and conductive film deposition steps) after deposition of the silicon nitride film, the metal silicide layer partially abnormally grows due to oxygen of the natural oxide film occurring on the metal silicide layer surface. A substantially non-bias (including low bias) plasma treatment is performed in a gas atmosphere containing an inert gas as a main component on the top surface of a metal silicide film of nickel silicide or the like over source/drain of a field-effect transistor forming an integrated circuit. Then, a silicon nitride film serving as an etching stop film of a contact process is deposited. As a result, without causing undesirable cutting of the metal silicide film, the natural oxide film over the top surface of the metal silicide film can be removed.

Virtual appliance deploying system

Abstract: In deployment of a virtual appliance to a physical server, a setting file required for the virtual appliance to operate is automatically generated based on a configuration of the physical server and a network configuration, and connection relation between the virtual appliances. Specifically, resource data assigned to the virtual appliance and connection data are registered on a configuration data database, and a template of the setting file is set in advance to a virtual machine image for the virtual appliance. In the deployment of the virtual appliance to the physical server, optional attributes described in the template of the setting file are replaced by specific setting values (actual data) by using the resource data and the connection data stored in the configuration data database, to generate the setting file.

Beyond-Birthday-Bound Security Based on Tweakable Block Cipher

Abstract: This paper studies how to build a 2n-bit block cipher which is hard to distinguish from a truly random permutation against attacks with q ≈ 2 n/2 queries, i.e., birthday attacks. Unlike previous approaches using pseudorandom functions, we present a simple and efficient proposal using a tweakable block cipher as an internal module. Our proposal is provably secure against birthday attacks, if underlying tweakable block cipher is also secure against birthday attacks. We also study how to build such tweakable block ciphers from ordinary block ciphers, which may be of independent interest.

Operation management device, operation management method, and operation management program

Abstract: An operation management device includes: an information collection module which collects, from a managed device, first and second performance information showing a time series change in the performance information; a correlation model generation module which derives a correlation function between the first and second performance information and creates a correlation model based on the correlation function; a correlation change analysis module which judges whether or not the current first and second performance information acquired by the information collection module satisfy the relation shown by the conversion function between the first and second performance information of the correlation model within a specific error range; and a failure period extraction module which, when the first and second performance information does not satisfy the relation shown by the conversion function of the correlation model , extracts a period of that state as a failure period.

Light emitting device

Abstract: It is enabled to provide that a light emitting device have an electron blocking layer (106) positioned between tunnel junctions (107, 108) and an active layer (104). The electron blocking layer (106) has an energy of conduction band edge higher than that of the active layer (605), and is composed of a material containing substantially no aluminum. It suppresses leakage of electrons from an n-type layer through a p-layer to an n-type layer. It is also enabled to provide that a light emitting device is capable of preventing the electron blocking layer (106) from being oxidized in the process of manufacturing by using a layer containing no aluminum for the electron blocking layer (106).

Network anomaly detection based on Eigen equation compression

Abstract: This paper addresses the issue of unsupervised network anomaly detection. In recent years, networks have played more and more critical roles. Since their outages cause serious economic losses, it is quite significant to monitor their changes over time and to detect anomalies as early as possible. In this paper, we specifically focus on the management of the whole network. In it, it is important to detect anomalies which make great impact on the whole network, and the other local anomalies should be ignored. Further, when we detect the former anomalies, it is required to localize nodes responsible for them. It is challenging to simultaneously perform the above two tasks taking into account the nonstationarity and strong correlations between nodes.We propose a network anomaly detection method which resolves the above two tasks in a unified way. The key ideas of the method are: (1)construction of quantities representing feature of a whole network and each node from the same input based on eigen equation compression, and (2)incremental anomalousness scoring based on learning the probability distribution of the quantities.We demonstrate through the experimental results using two benchmark data sets and a simulation data set that anomalies of a whole network and nodes responsible for them can be detected by the proposed method.

Slide bar display control device and slide bar display control method

Abstract: The slide bar display control device according to the present invention includes, a display means which indicates a first slide bar including a first slider and a first bar, an input means which can select an arbitrary part of the first slide bar shown on the display means based on touch operation, and a control means which controls the display means and the input means, wherein, when the control means detects that a first operation has been performed in a state that the first slider shown on the display means is being touched in the input means, the display means indicates a second slide bar including a second slider and a second bar, and wherein the second slider is a slider different in a variation amount of a set value per unit moving distance from the first slider.

Battery charging system for electric vehicle

Abstract: A battery charging system includes: an electric vehicle; a network termination unit connectable to the electric vehicle through a power line cable for supplying electric power to the electric vehicle; and a first server that transmits a control signal indicative of permission or forbiddance of power supply from the network termination unit to the electric vehicle to the electric vehicle through the network termination unit. The electric vehicle transmits identification information for identifying the electric vehicle and the user thereof to the first server through the network termination unit. The network termination unit transmits position information concerning the position of the network termination unit to the first server. The first server determines permission or forbiddance of the power supply based on the identification information and the position information.