Adjacent Devices Research Articles

Migrating Web Services in Mobile and Wireless Environments

Mobile devices enabled with Web services are being considered as equal participants of the Web services environment. The frequent mobility of devices and the intermittent disconnection of wireless network require migrating or replicating Web services onto adjacent devices appropriately. This article proposes an efficient method for migrating and replicating Web services among mobile devices through code splitting. Specifically, the proposed method splits the source code of a Web service into subcodes based on users’ preferences for its constituent operations. The subcode with a higher preference is migrated earlier than others. The proposed method also replicates a Web service to other devices to enhance its performance by considering context information such as network traffic or the parameter size of its operations. To evaluate the performance of the proposed method, the effect of the code splitting on migration was analyzed. Furthermore, to show the feasibility of the proposed migration method, three application scenarios were devised and implemented.

THE INVESTIGATION OF THE EFFECT OF VOLTAGE REGULATION DEVICES OF TRACTION SUBSTATION DC CONNECTING DEVICE

Research results of voltage autocontrol devices’ ifluence on adjacent devices are considered.

Investigation of Thermal Crosstalk Between SOI FETs by the Subthreshold Sensing Technique

Experimental-modeling investigation of the transient thermal crosstalk between the field-effect transistors implemented on a silicon-on-insulator substrate is reported. The measurements were performed using a high-speed electrical pulse-probe sampling technique, which allowed detection of thermally modulated subthreshold currents. The technique achieved a temperature resolution of ~50 mK, a time resolution of 5 ns, and a temperature sensitivity of ~0.6 muA/K. The finite-element method was used to solve the heat diffusion equation and to obtain the temperature profiles for the given device structures. The combined high-resolution experimental-simulation approach allowed the study of the thermal crosstalk between two adjacent devices and probe the local temperature at different locations of the structure. The effects of the interface quality, layer thickness, material selection, and interdevice spacing on the heat diffusion and device performance were investigated in detail.

Overcurrent Protection in Electrical Distribution Systems Through Probabilistic Approach

This work describes the study of distribution system overcurrent protection through a probabilistic approach. Conventional approaches for overcurrent protection do not consider the probabilistic nature of the main variables involved, such as fault location, fault type and fault impedance for faults involving the ground. In this case, for instance, it is very difficult to assess the impact of situations where full coordination cannot be attained for some reason. The probabilistic approach, on the other hand, allows quantifying the risk of two adjacent protective devices operating in a non-coordinated way. This information is extremely valuable for electrical engineers at design level. In this work, the proposed methodology is illustrated through a few detailed application studies, including various sensitivity analyzes for assessing the influence of model parameters on the coordination of protective devices.

IBM System z9 eFUSE applications and methodology

IBM System z9TM is the first zSeries® product to use electronic fuses (eFUSEs). The blowing of the fuse does not involve a physical rupture of the fuse element, but rather causes electromigration of the silicide layer, substantially increasing the resistance. The fuse is with the application of a higher-than-nominal voltage, eFUSEs provide several compelling advantages over the laser fuses they have replaced. The blow process does not risk damage to adjacent devices, eFUSEs can be blown by a logic process instead of a physical laser ablation method, eFUSEs are substantially smaller than laser fuses, and they scale better with process improvements. Finally, since no specialized equipment or separate product flow is required, eFUSEs can be blown at multiple test and application stages. We discuss circuit design, fuse programming, test considerations, and z9TM system applications. The physical and logical implementation of eFUSEs has resulted in improved yield at wafer, module, and final assembly test levels, and has provided additional flexibility in logic function and in system use.

Charge Collection and Charge Sharing in a 130 nm CMOS Technology

Charge sharing between adjacent devices can lead to increased Single Event Upset (SEU) vulnerability. Key parameters affecting charge sharing are examined, and relative collected charge at the hit node and adjacent nodes are quantified. Results show that for a twin-well CMOS process, PMOS charge sharing can be effectively mitigated with the use of contacted guard-ring, whereas a combination of contacted guard-ring, nodal separation, and interdigitation is required to mitigate the NMOS charge sharing effect for the technology studied

Modeling of the thermal effects of heat generating devices in close proximity on vertically oriented printed circuit boards for thermal management applications

The localized thermal interactions between adjacent devices on vertically orientated circuit boards in natural convection are predicted using experimentally validated computational fluid dynamics models. The effects of power density, device proximity, device geometry, circuit board material, board packing density and board separation distance on the steady state operating temperatures are investigated and incorporated into mathematical models which can be used to design packages which minimize thermal interactions. The separation distance beyond which the devices do not thermally influence each other is identified and the influence of various parameters on this distance is studied. The parametric study is designed using Design of Experiments methodology and therefore can be used to interpret the interaction between independent parameters. The developed models and methodology can easily and quickly be applied to other packaging situations to help minimize negative thermal interactions as one consideration in board layout design.

Piano mems micromirror

A micro-electro-mechanical (MEMs) mirror device for use in an optical switch is disclosed. A “piano”-style MEMs device includes an elongated platform pivotally mounted proximate the middle thereof by a torsional hinge. The middle portion of the platform and the torsional hinge have a combined width less than the width of the rest of the platform, whereby several of these “piano” MEMs devices can be positioned adjacent each other pivotally mounted about the same axis with only a relatively small air gap therebetween. In a preferred embodiment of the present invention specially designed for wavelength switching applications, a greater range of arcuate motion for a mirror mounted thereon is provided by enabling the platform to rotate about two perpendicular axes. The MEMs mirror device according to the preferred embodiment of the present invention enables the mirror to tilt about two perpendicular axes, by the use of an “internal” gimbal ring construction, which ensures that a plurality of adjacent mirror devices have a high fill factor, without having to rely on complicated and costly manufacturing processes.

AlGaAs buffer structure grown by metalorganic vapor phase epitaxy for GaAs-based field-effect transistors

A buffer structure made of two different AlGaAs layers for the GaAs-based field-effect transistors grown by metalorganic vapor phase epitaxy (MOVPE) has been demonstrated. The two AlGaAs layers that are grown in different conditions were developed to provide the demanded quality for buffer structure. The first AlGaAs layer on the substrate was grown at relatively low temperature to incorporate oxygen atoms. Thereby, the oxygen ions form the deep impurity level in the AlGaAs layer and this layer shows a high resistivity. By adjusting the growth condition, the second AlGaAs layer with high purity was deposited. To effectively suppress the leakage current between two adjacent devices formed on the two-AlGaAs-layer buffer structure has been proved. By using the two-AlGaAs-layer buffer structure and optimizing the growth condition, we have obtained the typical InGaAs/AlGaAs pseudomorphic high electron mobility transistors (PHEMTs) with sharp pinch-off characteristics and low output conductance. In addition, the minimization of side-gating effect has been achieved.

Microarrays of silicon-based light emitters for novel biosensor and lab-on-a-chip applications

Abstract We have demonstrated intense violet electroluminescence (EL) from thermally-grown SiO2 films containing Ge nanocrystals produced by ion beam synthesis. An outline is given of the electrical and optical characteristics of ITO/SiO2/Al light-emitting devices incorporating Ge nanocluster-rich oxide films. Optimization schemes based on the use of local oxidation of Si (LOCOS) have been developed and tested successfully. Arrays of 4 × 6 light-emitting devices with a diameter of 300 μm and spacing of 500 μm between the adjacent devices have been formed using standard lithography patterning. Bioanalyses have been carried out following fluorescent-based detection procedures. As distinct from the standard case of diagnostics in which the light source is typically a laser and the necessary spatial resolution is provided by a CCD camera, our light sources are small enough to immediately ensure high resolution while permitting their light emission to be detected by single inexpensive Si diodes. The relevance of the all-Si light sources to microarray, miniaturized sensor and lab-on-a-chip systems for point-of-care diagnostics is discussed. Finally, first EL spectra of Si-based light sources containing Tb are shown.

Radiated fields of capacitive micromachined ultrasonic transducers in air.

This paper presents a study of the radiated ultrasonic fields of capacitive micromachined ultrasonic transducers (often referred to as cMUTs) in air. These fields were modeled theoretically and then compared to the experimental near-field amplitude variations and directivity patterns of square cMUTs. The good agreement between theory and experiment indicates that the devices can be approximated to plane piston radiators. The fields of multiple elements driven in phase on the same silicon substrate are presented, where again comparison is made to theory. The results indicate that individual elements are unaffected by radiation through the silicon substrate from adjacent devices. It will also be demonstrated that it is possible to use the knowledge of these fields to develop air-coupled ultrasonic surface imaging systems.

Thermal oxidation of AlgaAs: modeling and process control

A simple physical model is developed for the thermal oxidation process of AlGaAs using the continuity equation. The model is based on the principle of oxidant mass conservation. Theoretical calculations are compared with experimental data to a good agreement. The model is then applied to the study of VCSEL batch fabrication. Several control parameters are discussed including AlGaAs layer thickness, aluminum composition, initial mesa size, spacing between two adjacent devices, oxidation time, and oxidation temperature.

All-optical excitation and detection of microelectrical-mechanical systems

The radiation pressure of a chopped, 3 mW optical beam is used to excite angular motion of a Microelectrical-mechanical-systems’ (MEMS) mirror at its resonant frequencies. The modes are identified with a scanning interferometer, providing an all-optical excitation/detection scheme. The resonant frequencies, mode distributions, spring constants, and coupling between adjacent MEMS devices can, therefore, be studied without the use of electrostatic or other types of actuation. Within the experimental error of ∼30%, the amplitude of angular oscillation is equal to the theoretical value expected for radiation pressure.

Performance of a Scalable Multimedia Server with Shared-Storage Clusters

The existing SCSI parallel bus has been widely used in various multimedia applications. However, due to the unfair bus accesses the SCSI bus may not be able to fully utilize the potential aggregate throughput of disks. The number of disks that can be attached to the SCSI bus is limited, and link level fault tolerance is not provided. The serial storage interfaces such as Serial Storage Architecture (SSA) provide high data bandwidth, fair accesses, long transmission distance between adjacent devices (disks or hosts) and link level fault tolerance. The fairness algorithm of SSA ensures a fraction of data bandwidth to be allocated to each device. In this paper we would like to know whether SSA is a better alternative in supporting continuous media than SCSI. The scalability of a multimedia server is very important since the storage requirement may grow incrementally as more contents are created and stored. SSA in a shared-storage cluster environment also supports concurrent accesses by different hosts as long as their access paths are not overlapped. This feature is called spatial reuse. Therefore, the effective bandwidth over an SSA can be higher than the raw data bandwidth and the spatial reuse feature is critical to the scalability of a multimedia server. This feature is also included in FC-AL3 with a new mode called Multiple Circuit Mode (MCM). Using MCM, all devices can transfer data simultaneously without collision. In this paper we have investigated the scalability of shared-stroage clusters over an SSA environment.

Nanotechnology-based molecular test equipment (MTE)

This paper describes original research efforts in the design, simulation, and development of nanotechnology-based molecular test equipment (MTE). This is a research effort for testing printed circuit boards independent of traditional automatic test equipment (ATE) through the fabrication of MTE within integrated circuits (ICs). The MTE is embedded within the IC substrate and encapsulated within nanoprobes that connect between the surface and the substrate of the IC at various functional areas. A process is followed whereby IC device simulation is performed to assess the electrical, chemical, and structural properties of integrated and adjacent substrate devices. Through this approach the nominal and failed device performance parameters of interest to substrate-based MTE are found. Discussion of the development and application of MTE within IC architectures is provided, including such topics as the effect of substrate composition on the design and realization of MTE, interfaces between MTE and IC devices, and reporting of MTE results to the IC surface and technician. Potential application areas within different device functions will also be identified. A chemical structure diagram is also provided to illustrate the implementation of MTE using discrete device configurations with MTE-augmented logic.

Reduction of the parasitic charge generation during silicon nitride deposition in a LOCOS isolation without field implant

MOS integrated circuits use the Local oxidation of silicon to isolate laterally adjacent devices (LOCOS isolation). The insulation structure is typically formed by a semiconductor region doped by ion implantation (field implant) and covered by a thick thermal oxide (field oxide). Other insulators (plasma enhanced chemical vapor deposited (PECVD) silicon oxides and LPCVD silicon nitride) and metal interconnection are subsequently deposited on the field oxide. The ion implant together with the thick insulator ensure a high threshold voltage value of the parasitic MOS transistor formed by source and drain of the adjacent active devices and by the insulator/interconnection gate.However, economical purpose leads to the extension of the application field of lower cost technology, addressing the problem of LOCOS isolation without any field implant. As already shown in a previous work [Fay JL, Beluch J, Allirand L, Brosset D, Despax B, Bafleur M, Sarrabayrose G. Jpn J Appl Phys 38(9A):5012–7] for inter-layer dielectric applications, our PECVD oxides suffer from excessive concentration of fixed positive charges brought about by the silicon nitride deposition, and causing the N-channel field threshold voltage to decrease.Characterization reveals that these charges are generated by diffusion of species coming from the gas phase during the silicon nitride process. These generated charges can be reduced either by increasing the O2/tetra-ethyl orthosilicate ratio or by doping the oxide with boron and phosphorus. To avoid diffusion and generation of charges, we minimized the thermal budget using a PECVD silicon nitride. With this process, we have achieved a high threshold voltage and an acceptably low leakage current of the NMOS parasitic transistor.

Analysis of crosstalk in HgCdTe p-on-n heterojunction photovoltaic infrared sensing arrays

In this paper, an experimental and theoretical study is carried out of crosstalk between nearest-neighbor devices within a backside-illuminated linear HgCdTe photovoltaic infrared sensing array. The dominant form of crosstalk that occurs in high performance photovoltaic arrays is associated with photogenerated minority carriers that diffuse laterally between adjacent devices within the array. To measure crosstalk, a scanning laser microscope is used to obtain a spatial map of spot-scan photoresponse at a temperature of 80K for individual p-on-n photovoltaic devices within the linear array. These experimental results are compared to calculations performed on a commercial two-dimensional device simulation package. The crosstalk measurements and calculations presented in this paper include results on mid-wavelength infrared planar device structures, as well as long-wavelength infrared mesa-isolated devices, which give measured crosstalk values of 6.2 and 8.3%, respectively. The results indicate that the device simulations are in good agreement with experimental results. Further simulations are carried out to determine the sensitivity of crosstalk to various material and device parameters such as epitaxial layer thickness (7 to 25 µm), illumination wavelength (1.047 to 11.0 µm), minority carrier diffusion length (8 to 90 µm), and diode pitch. It is found that the dominant feature influencing the value of crosstalk is the distance between the region of photogeneration and the collecting p-n junction.

Molecular Sensors and Sensor Arrays Based on Polyaniline Microtubules

This paper describes the fabrication of microtubular biosensors and sensor arrays based on polyaniline with superior transducing ability. These sensors have been tested for the estimation of glucose, urea, and triglycerides. As compared to that of a macro sensor, the response of the microtubular sensor for glucose is higher by a factor of more than 10(3). Isoporous polycarbonate membranes have been used to fabricate inexpensive devices by simple thermal evaporation of gold using appropriate machined masks. Polyaniline deposition and enzyme immobilization have been done electrochemically. Electrochemical potential control has been used to direct enzyme immobilization to the chosen membrane device and avoid cross talk with adjacent devices. This has enabled the immobilization of a set of three different enzymes on three closely spaced devices, resulting in a microtubule array that can analyze a sample containing a mixture of glucose, urea, and triglycerides in a single measurement. This, in essence, is an "electronic tongue".

An Isoplanar Isolation Technology for SiC Devices Using Local Oxidation

This article presents the feasibility of extending the well‐known Si LOCOS (localized oxidation of Si) technology to. Two isolation processes have been structurally evaluated to find an optimal, isoplanar isolation technology for device integration. The first is an extension of the conventional LOCOS process which exploits the differential oxidation ratio between and . The second technique, called the “field‐poly” process, uses a selective oxidation of polysilicon over to form the isolating field region. Scanning electron micrographs show the typical bird's beak around the active area border with a width of 0.92 μm per side for the LOCOS process and 0.55μm per side for the field‐poly process . Compared to the mesa isolation currently used for , the new technologies improve structural planarity while allowing self‐aligned field threshold implants for isolation between adjacent devices.

Vertical-cavity ring laser

A new type of laser diode structure is proposed, in which a ring type structure is implemented with the plane of the ring perpendicular to the surface of the semiconductor. Emitting beams both parallel and perpendicular to the surface, this structure could be useful for coupling into fiber or adjacent optoelectronic devices. By injection-locking a series of these lasers, a phased array of surface emitting lasers is made possible. Losses are expected to be significantly less than those reported for grating-coupled surface emitting arrays, with from 8% to 31% coupling plus absorption loss compared to 50%-73% refraction plus absorption loss for grating coupled arrays. >