Analysis Of The Energy Quantization Effects On Single Electron Inverter Performance Through Noise Margin Modeling

Possible integration of Single Electron Transistor (SET) with CMOS technology is making the study of semiconductor SET more important than the metallic SET and consequently, the study of energy quantization effects on semiconductor SET devices and circuits is gaining significance. In this paper, for the first time, the effects of energy quantization on SET inverter performance are examined through analytical modeling and Monte Carlo simulations. It is observed that the primary effect of energy quantization is to change the Coulomb Blockade region and drain current of SET devices and as a result affects the noise margin, power dissipation, and the propagation delay of SET inverter. A new model for the noise margin of SET inverter is proposed which includes the energy quantization effects. Using the noise margin as a metric, the robustness of SET inverter is studied against the effects of energy quantization. It is shown that SET inverter designed with CT : CG = 1/3 (where CT and CG are tunnel junction and gate capacitances respectively) offers maximum robustness against energy quantization.

Electrical Characterization of Airborne Vehicle Exhaust Plume

he induced current and voltage on the skin of an airborne vehicle due to the coupling of external electromagnetic field could be altered in the presence of ionized exhaust plume. So in the present work, a theoretical analysis is done to estimate the electrical parameters such as electrical conductivity and permittivity and their distribution in the axial and radial directions of the exhaust plume of an airborne vehicle. The electrical conductivity depends on the distribution of the major ionic species produced from the propellant combustion. In addition it also depends on temperature and pressure distribution of the exhaust plume as well as the generated shock wave. The chemically reactive rocket exhaust flow is modeled in two stages. The first part is simulated from the combustion chamber to the throat of the supersonic nozzle by using NASA Chemical Equilibrium with Application (CEA) package and the second part is simulated from the nozzle throat to the downstream of the plume by using a commercial Computational Fluid Dynamics (CFD) solver. The contour plots of the exhaust parameters are presented. Eight barrel shocks which influence the distribution of the vehicle exhaust parameters are obtained in this simulation. The computed peak value of the electrical conductivity of the plume is 0.123 S/m and the relative permittivity varies from 0.89 to 0.99. The attenuation of the microwave when it is passing through the conducting exhaust plume has also been presented.

Concept of Crossover point and its application on Threshold Voltage definition for Undoped-Body Transistors

As the conventional MOSFETs scaling is approaching the limit imposed by short channel effects, Double Gate (DG) MOS transistors are appearing as the most feasible andidate in terms of technology in sub-45nm technology nodes. As the short channel effect in DG transistor is controlled by the device geometry, undoped or lightly doped body, is used to sustain the channel. There exits a disparity in threshold voltage calculation criteria of undoped-body symmetric double gate transistors which uses two definitions, one is potential based and the another is charge based definition. In this paper, a novel concept of "crossover point" is introduced, which proves that the charge-based definition is more accurate than the potential based definition. The change in threshold voltage with body thickness variation for a fixed channel length is anomalous as predicted by, potential based definition while it is monotonous for change based definition. The threshold voltage is then extracted from drain currant versus gate voltage characteristics using linear extrapolation and "Third Derivative of Drain-Source Current" method or simply "TD" method. The trend of threshold voltage variation is found some in both the cases which support charge-based definition.

Load-Commutated SCR Current-Source-Inverter-Fed Induction Motor Drive With Sinusoidal Motor Voltage and Current

Current source inverter (CSI) is an attractive solution in high-power drives. The conventional gate turn-off thyristor (GTO) based CSI-fed induction motor drives suffer from drawbacks such as low-frequency torque pulsation, harmonic heating, and unstable operation at low-speed ranges. These drawbacks can be overcome by connecting a current-controlled voltage source inverter (VSI) across the motor terminal replacing the bulky ac capacitors. The VSI provides the harmonic currents, which results in sinusoidal motor voltage and current even with the CSI switching at fundamental frequency. This paper proposes a CSI-fed induction motor drive scheme where GTOs are replaced by thyristors in the CSI without any external circuit to assist the turning off of the thyristors. Here, the current-controlled VSI, connected in shunt, is designed to supply the volt ampere reactive requirement of the induction motor, and the CSI is made to operate in leading power factor mode such that the thyristors in the CSI are autosequentially turned off. The resulting drive will be able to feed medium-voltage, high-power induction motors directly. A sensorless vector-controlled CSI drive based on the proposed configuration is developed. The experimental results from a 5 hp prototype are presented. Experimental results show that the proposed drive has stable operation throughout the operating range of speeds.

Influence of Filler Loading on Dielectric Properties of Epoxy-ZnO Nanocomposites

Experimental investigations into the dielectric properties of epoxy-ZnO nanocomposites at different filler loadings reveal few unique behaviors (at certain filler loadings) and also advantageous characteristics in contrast to the properties obtained for the corresponding microcomposites. Results demonstrate that in nanocomposites, it is possible to achieve lower values of permittivity and tan delta with respect to unfilled epoxy over a wide frequency range. Analysis of the results attributes this interesting observation to the interaction dynamics between the epoxy chains and the ZnO nanoparticles at the interfacial area. The dc volume resistivities and ac dielectric strengths of nanocomposites were also experimentally determined in the present study and the obtained characteristics are found to be different as compared to the results obtained for microcomposites. The volume fraction and nature of the interfaces in the bulk of the composites seem to influence this difference in the examined dielectric properties of the nanocomposites.

Justifying threshold voltage definition for undoped body transistors through ``crossover point'' concept

Two different definitions, one is potential based and the other is charge based, are used in the literatures to define the threshold voltage of undoped body symmetric double gate transistors. This paper, by introducing a novel concept of crossover point, proves that the charge based definition is more accurate than the potential based definition. It is shown that for a given channel length the potential based definition predicts anomalous change in threshold voltage with body thickness variation while the charge based definition results in monotonous change. The threshold voltage is then extracted from drain current versus gate voltage characteristics using linear extrapolation, transconductance and match-point methods. In all the three cases it is found that trend of threshold voltage variation support the charge based definition.

A Unique Filter-Preserver Device for Digital Photonic Circuits

We discuss micro ring resonator based optical logic gates using Kerr-type nonlinearity. Resonant wavelength selectivity is one key factor in achieving the desired gate. Based on basic gates like AND gate, OR gate etc. We proceed to propose a 3-bit binary adder circuit.Due to the presence of more than a single wavelength, the system gets complicated as we increase the number of components in the circuit. Hence it has been observed that for efficient designing and functioning of digital circuits in optical domain, we need a device which can give single wavelength output, filtering out all other wavelengths and at the same time preserve the digital characteristics of the output. We propose such filter-preserver device based on micro ring resonator.

Ways and Means for Disposal of Surplus Water in Storage Reservoirs and other Irrigation and Flood Protective Works

In the paper new way of classifying spillways have been suggested. The various types, merits and demerits or existing spillway devices have been discussed. The considerations governing the choice of a design of a spillway have been mention. A criteria for working out the economics of spillway design has been suggested. An efficient surplus sing device has next been described and compared with other devices. In conclusion it has been suggested that the most efficient and at the same time economical arrangement will be a combination of devices. In conclusion it has been suggested will be a combination of crest gate, volute siphons and high head gates. The appendix gives a list of devices used in dams in various parts of the world.

Hydrothermal phase equilibria in Ln2O3-H2O-CO2 systems : I. The lighter lanthanides

Phase diagrams for Nd2O3-H2O-CO2 and Gd2O3-H2O-CO2 systems at 1500 atm are given along with the results of selected runs in La, Sm and Eu systems. The stable phases in systems of La and Nd, are Ln(OH)CO3-B, Ln2O2CO3-II and LnOOH, in addition to the Ln(OH)3 phase at extremely low partial pressures of CO2 in the system. The systems become more and more complex with decreasing ionic radi and the number of stable carbonate phases increases. Ln2(CO3)3 · 3H2O orthorhombic (tengerate-like phase) is stable from Sm to Gd in addition to the other phases. The Gd(OH)CO3-A (ancylite-like phase) is hydrothermally stable at XCO2 greater-or-equal, slanted 0.5 while its hexagonal polymorph, Gd(OH)CO3-B is stable at low partial pressures of CO2 in the system.

Nonlinear transport in semiconducting polymers at high carrier densities

Conducting and semiconducting polymers are important materials in the development of printed, flexible, large-area electronics such as flat-panel displays and photovoltaic cells. There has been rapid progress in developing conjugated polymers with high transport mobility required for high-performance field-effect transistors (FETs), beginning(1) with mobilities around 10(-4) cm(2) V-1 s(-1) to a recent report(2) of 1 cm(2) V-1 s(-1) for poly(2,5-bis(3-tetradecylthiophen-2-yl) thieno[3,2-b] thiophene) (PBTTT). Here, the electrical properties of PBTTT are studied at high charge densities both as the semiconductor layer in FETs and in electrochemically doped films to determine the transport mechanism. We show that data obtained using a wide range of parameters (temperature, gate-induced carrier density, source-drain voltage and doping level) scale onto the universal curve predicted for transport in the Luttinger liquid description of the one-dimensional `metal'.

Evaluation of a remote drafting system for regulating sheep access to supplement

Remote drafting technology now available for sheep makes possible targeted supplementation of individuals within a grazing flock. This system was evaluated by using 68 Merino wethers grazing dry-season, native Mitchell grass pasture (predominantly Astrebla spp.) as a group and receiving access to lupin grain through a remote drafter 0, 1, 2, 4 or 7 days/week for 8 weeks. The sole paddock watering point was separately fenced and access was via a one-way flow gate. Sheep exited the watering point through a remote drafter operated by solar power and were drafted by radio frequency identification (RFID) tag, according to treatment, either back into the paddock or into a common supplement yard where lupins were provided ad libitum in a self-feeder. Sheep were drafted into the supplement yard on only their first time through the drafter during the prescribed 24-h period and exited the supplement yard via one-way flow gates in their own time. The remote drafter operated with a high accuracy, with only 2.1% incorrect drafts recorded during the experimental period out of a total of 7027 sheep passes through the remote drafter. The actual number of accesses to supplement for each treatment group, in order, were generally less than that intended, i.e. 0.02, 0.69, 1.98, 3.35 and 6.04 days/week. Deviations from the intended number of accesses to supplement were mainly due to sheep not coming through to water on their allocated day of treatment access, although some instances were due to incorrect drafts. There was a non-linear response in growth rate to increased frequency of access to lupins with the growth rate response plateauing at similar to 3 actual accesses per week, corresponding to a growth rate of 72.5 g/head. day. This experiment has demonstrated the application of the remote drafting supplementation system for the first time under grazing conditions and with the drafter operated completely from solar power. The experiment demonstrates a growth response to increasing frequency of access to supplement and provides a starting point with which to begin to develop feeding strategies to achieve sheep weight-change targets.

Implementation of parallel tridiagonal solvers for a heterogeneous computing environment

Tridiagonal diagonally dominant linear systems arise in many scientific and engineering applications. The standard Thomas algorithm for solving such systems is inherently serial forming a bottleneck in computation. Algorithms such as cyclic reduction and SPIKE reduce a single large tridiagonal system into multiple small independent systems which can be solved in parallel. We have developed portable cyclic reduction and SPIKE algorithm OpenCL implementations with the intent to target a range of co-processors in a heterogeneous computing environment including Field Programmable Gate Arrays (FPGAs), Graphics Processing Units (GPUs) and other multi-core processors. In this paper, we evaluate these designs in the context of solver performance, resource efficiency and numerical accuracy.

Renormalization of the phonon spectrum in semiconducting single-walled carbon nanotubes studied by Raman spectroscopy

In situ Raman experiments together with transport measurements have been carried out in single-walled carbon nanotubes as a function of electrochemical top gate voltage (Vg). We have used the green laser (EL=2.41 eV), where the semiconducting nanotubes of diameter ~1.4 nm are in resonance condition. In semiconducting nanotubes, the G−- and G+-mode frequencies increase by ~10 cm−1 for hole doping, the frequency shift of the G− mode is larger compared to the G+ mode at the same gate voltage. However, for electron doping the shifts are much smaller: G− upshifts by only ~2 cm−1 whereas the G+ does not shift. The transport measurements are used to quantify the Fermi-energy shift (EF) as a function of the gate voltage. The electron-hole asymmetry in G− and G+ modes is quantitatively explained using nonadiabatic effects together with lattice relaxation contribution. The electron-phonon coupling matrix elements of transverse-optic (G−) and longitudinal-optic (G+) modes explain why the G− mode is more blueshifted compared to the G+ mode at the same Vg. The D and 2D bands have different doping dependence compared to the G+ and G− bands. There is a large downshift in the frequency of the 2D band (~18 cm−1) and D (~10 cm−1) band for electron doping, whereas the 2D band remains constant for the hole doping but D upshifts by ~8 cm−1. The doping dependence of the overtone of the G bands (2G bands) shows behavior similar to the dependence of the G+ and G− bands.

Quest for new materials: Inorganic chemistry plays a crucial role

There is an endless quest for new materials to meet the demands of advancing technology. Thus, we need new magnetic and metallic/semiconducting materials for spintronics, new low-loss dielectrics for telecommunication, new multi-ferroic materials that combine both ferroelectricity and ferromagnetism for memory devices, new piezoelectrics that do not contain lead, new lithium containing solids for application as cathode/anode/electrolyte in lithium batteries, hydrogen storage materials for mobile/transport applications and catalyst materials that can convert, for example, methane to higher hydrocarbons, and the list is endless! Fortunately for us, chemistry - inorganic chemistry in particular - plays a crucial role in this quest. Most of the functional materials mentioned above are inorganic non-molecular solids, while much of the conventional inorganic chemistry deals with isolated molecules or molecular solids. Even so, the basic concepts that we learn in inorganic chemistry, for example, acidity/basicity, oxidation/reduction (potentials), crystal field theory, low spin-high spin/inner sphere-outer sphere complexes, role of d-electrons in transition metal chemistry, electron-transfer reactions, coordination geometries around metal atoms, Jahn-Teller distortion, metal-metal bonds, cation-anion (metal-nonmetal) redox competition in the stabilization of oxidation states - all find crucial application in the design and synthesis of inorganic solids possessing technologically important properties. An attempt has been made here to illustrate the role of inorganic chemistry in this endeavour, drawing examples from the literature its well as from the research work of my group.

Modeling and analysis of energy quantization effects on single electron inverter performance

In this paper, for the first time, the effects of energy quantization on single electron transistor (SET) inverter performance are analyzed through analytical modeling and Monte Carlo simulations. It is shown that energy quantization mainly changes the Coulomb blockade region and drain current of SET devices and thus affects the noise margin, power dissipation, and the propagation delay of SET inverter. A new analytical model for the noise margin of SET inverter is proposed which includes the energy quantization effects. Using the noise margin as a metric, the robustness of SET inverter is studied against the effects of energy quantization. A compact expression is developed for a novel parameter quantization threshold which is introduced for the first time in this paper. Quantization threshold explicitly defines the maximum energy quantization that an SET inverter logic circuit can withstand before its noise margin falls below a specified tolerance level. It is found that SET inverter designed with CT:CG=1/3 (where CT and CG are tunnel junction and gate capacitances, respectively) offers maximum robustness against energy quantization.