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Sample records for silicon controlled rectifier

  1. Automatic method of measuring silicon-controlled-rectifier holding current

    NASA Technical Reports Server (NTRS)

    Maslowski, E. A.

    1972-01-01

    Development of automated silicon controlled rectifier circuit for measuring minimum anode current required to maintain rectifiers in conducting state is discussed. Components of circuit are described and principles of operation are explained. Illustration of circuit is provided.

  2. Effects of 22 MeV protons on single junction and silicon controlled rectifiers

    NASA Technical Reports Server (NTRS)

    Beatty, M. E., III

    1972-01-01

    The effects of 22-MeV protons on various types of silicon single junction and silicon controlled rectifiers were investigated. The results show that low-leakage devices and silicon controlled rectifiers are the most susceptable to radiation damage. There are also differences noted between single junction rectifiers of the same type made by different manufacturers, which emphasizes the need for better selection of devices used in spacecraft.

  3. Understanding of self-terminating pulse generation using silicon controlled rectifier and RC load

    NASA Astrophysics Data System (ADS)

    Chang, Chris; Alves, Fabio; Karunasiri, Gamani

    2016-01-01

    Recently a silicon controlled rectifier (SCR)-based circuit that generates self-terminating voltage pulses was employed for the detection of light and ionizing radiation in pulse mode. The circuit consisted of a SCR connected in series with a RC load and DC bias. In this paper, we report the investigation of the physics underlying the pulsing mechanism of the SCR-based. It was found that during the switching of SCR, the voltage across the capacitor increased beyond that of the DC bias, thus generating a reverse current in the circuit, which helped to turn the SCR off. The pulsing was found to be sustainable only for a specific range of RC values depending on the SCR's intrinsic turn-on/off times. The findings of this work will help to design optimum SCR based circuits for pulse mode detection of light and ionizing radiation without external amplification circuitry.

  4. Road load simulator tests of the Gould phase 1 functional model silicon controlled rectifier ac motor controller for electric vehicles

    NASA Technical Reports Server (NTRS)

    Gourash, F.

    1984-01-01

    The test results for a functional model ac motor controller for electric vehicles and a three-phase induction motor which were dynamically tested on the Lewis Research Center road load simulator are presented. Results show that the controller has the capability to meet the SAE-J227a D cycle test schedule and to accelerate a 1576-kg (3456-lb) simulated vehicle to a cruise speed of 88.5 km/hr (55 mph). Combined motor controller efficiency is 72 percent and the power inverter efficiency alone is 89 percent for the cruise region of the D cycle. Steady state test results for motoring, regeneration, and thermal data obtained by operating the simulator as a conventional dynamometer are in agreement with the contractor's previously reported data. The regeneration test results indicate that a reduction in energy requirements for urban driving cycles is attainable with regenerative braking. Test results and data in this report serve as a data base for further development of ac motor controllers and propulsion systems for electric vehicles. The controller uses state-of-the-art silicon controlled rectifier (SCR) power semiconductors and microprocessor-based logic and control circuitry. The controller was developed by Gould Laboratories under a Lewis contract for the Department of Energy's Electric and Hybrid Vehicle program.

  5. Road load simulator tests of the Gould phase 1 functional model silicon controlled rectifier ac motor controller for electric vehicles

    NASA Astrophysics Data System (ADS)

    Gourash, F.

    1984-02-01

    The test results for a functional model ac motor controller for electric vehicles and a three-phase induction motor which were dynamically tested on the Lewis Research Center road load simulator are presented. Results show that the controller has the capability to meet the SAE-J227a D cycle test schedule and to accelerate a 1576-kg (3456-lb) simulated vehicle to a cruise speed of 88.5 km/hr (55 mph). Combined motor controller efficiency is 72 percent and the power inverter efficiency alone is 89 percent for the cruise region of the D cycle. Steady state test results for motoring, regeneration, and thermal data obtained by operating the simulator as a conventional dynamometer are in agreement with the contractor's previously reported data. The regeneration test results indicate that a reduction in energy requirements for urban driving cycles is attainable with regenerative braking. Test results and data in this report serve as a data base for further development of ac motor controllers and propulsion systems for electric vehicles. The controller uses state-of-the-art silicon controlled rectifier (SCR) power semiconductors and microprocessor-based logic and control circuitry. The controller was developed by Gould Laboratories under a Lewis contract for the Department of Energy's Electric and Hybrid Vehicle program.

  6. Design considerations and experimental analysis for silicon carbide power rectifiers

    NASA Astrophysics Data System (ADS)

    Khemka, V.; Patel, R.; Chow, T. P.; Gutmann, R. J.

    1999-10-01

    In this paper we present the investigation of properties of silicon carbide power rectifiers, in particular Schottky, PiN and advanced hybrid power rectifiers such as the trench MOS barrier Schottky rectifier. Analysis of the forward, reverse and switching experimental characteristics are presented and these silicon carbide rectifiers are compared to silicon devices. Silicon carbide Schottky rectifiers are attractive for applications requiring blocking voltage in excess of 100 V as the use of Si is precluded by its large specific on-resistance. Analysis of power dissipation indicates that silicon carbide Schottky rectifiers offer significant improvement over silicon counterparts. Silicon carbide junction rectifiers, on the other hand, are superior to silicon counterparts only for blocking voltage greater than 2000 V. Performance of acceptor (boron) and donor (phosphorus) implanted experimental silicon carbide junction rectifiers are presented and compared. Some of the recent developments in silicon carbide rectifiers have been described and compared with theory and our experimental results. The well established silicon rectifiers theory are often inadequate to describe the characteristics of the experimental silicon carbide junction rectifiers and appropriate generalization of these theories are presented. Experimental trench MOS barrier Schottky rectifiers (TMBS) have demonstrated significant improvement in leakage current compared to planar Schottky devices. Performance of current state-of-the-art silicon carbide rectifiers are far from theoretical predictions. Availability of high-quality silicon carbide crystals is crucial to successful realization of these performance projections.

  7. High holding voltage segmentation stacking silicon-controlled-rectifier structure with field implant as body ties blocking layer

    NASA Astrophysics Data System (ADS)

    Yen, Shiang-Shiou; Cheng, Chun-Hu; Lan, Yu-Pin; Chiu, Yu-Chien; Fan, Chia-Chi; Hsu, Hsiao-Hsuan; Chang, Shao-Chin; Jiang, Zhe-Wei; Hung, Li-Yue; Tsai, Chi-Chung; Chang, Chun-Yen

    2016-04-01

    High electrostatic discharge (ESD) protection robustness and good transient-induced latchup immunity are two important issues for high voltage integrate circuit application. In this study, we report a high-voltage-n-type-field (HVNF) implantation to act as the body ties blocking layer in segmented topology silicon-controlled-rectifier (SCR) structure in 0.11 µm 32 V high voltage process. This body ties blocking layer eliminate the elevated triggered voltage in segmented technique. Using a large resistance as shunt resistor in resistor assisted triggered SCRs stacking structure, the double snapback phenomenon is eliminate. The series SCR could be decoupled a sufficient voltage drop to turned-on when a very low current flow through the shunt resistor. The holding voltage and the failure current of 22 V and 3.4 A are achieved in the best condition of segmented topology SCR stacking structure, respectively. It improves the latchup immunity at high voltage ICs application. On the other hand, the triggered voltage almost keep the same value which is identical to SCR single cell without using segmented topology.

  8. PWM control techniques for rectifier filter minimization

    SciTech Connect

    Ziogas, P.D.; Kang, Y-G; Stefanovic, V.R.

    1985-09-01

    Minimization of input/output filters is an essential step towards manufacturing compact low-cost static power supplies. Three PWM control techniques that yield substantial filter size reduction for three-phase (self-commutated) rectifiers are presented and analyzed. Filters required by typical line-commutated rectifiers are used as the basis for comparison. Moreover, it is shown that in addition to filter minimization two of the proposed three control techniques improve substantially the rectifier total input power factor.

  9. Reliable Breakdown Obtained in Silicon Carbide Rectifiers

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.

    1997-01-01

    The High Temperature Integrated Electronics and Sensor (HTIES) Program at the NASA Lewis Research Center is currently developing silicon carbide (SiC) for use in harsh conditions where silicon, the semiconductor used in nearly all of today's electronics, cannot function. Silicon carbide's demonstrated ability to function under extreme high-temperature, high-power, and/or high-radiation conditions will enable significant improvements to a far-ranging variety of applications and systems. These range from improved high-voltage switching for energy savings in public electric power distribution and electric vehicles, to more powerful microwave electronics for radar and cellular communications, to sensor and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines.

  10. Silicon Carbide High-Temperature Power Rectifiers Fabricated and Characterized

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The High Temperature Integrated Electronics and Sensors (HTIES) team at the NASA Lewis Research Center is developing silicon carbide (SiC) for use in harsh conditions where silicon, the semiconductor used in nearly all of today's electronics, cannot function. Silicon carbide's demonstrated ability to function under extreme high-temperature, high power, and/or high-radiation conditions will enable significant improvements to a far ranging variety of applications and systems. These improvements range from improved high-voltage switching for energy savings in public electric power distribution and electric vehicles, to more powerful microwave electronics for radar and cellular communications, to sensors and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines. In the case of jet engines, uncooled operation of 300 to 600 C SiC power actuator electronics mounted in key high-temperature areas would greatly enhance system performance and reliability. Because silicon cannot function at these elevated temperatures, the semiconductor device circuit components must be made of SiC. Lewis' HTIES group recently fabricated and characterized high-temperature SiC rectifier diodes whose record-breaking characteristics represent significant progress toward the realization of advanced high-temperature actuator control circuits. The first figure illustrates the 600 C probe-testing of a Lewis SiC pn-junction rectifier diode sitting on top of a glowing red-hot heating element. The second figure shows the current-versus voltage rectifying characteristics recorded at 600 C. At this high temperature, the diodes were able to "turn-on" to conduct 4 A of current when forward biased, and yet block the flow of current ($quot;turn-off") when reverse biases as high as 150 V were applied. This device represents a new record for semiconductor device operation, in that no previous semiconductor electronic device has ever simultaneously demonstrated 600 C functionality

  11. Apparatus for controlling the firing of rectifiers in polyphase rectifying circuits

    DOEpatents

    Yarema, R.J.

    1979-09-18

    A polyphase rectifier is controlled with precision by a circuit that filters and shifts a reference signal associated with each phase and that starts a ramp signal at a zero crossing of the shifted reference signal. The difference between the ramp signal and an external trigger signal is used to generate a pulse that switches power rectifiers into conduction. The circuit reduces effects of variations that introduce subharmonics into a rectified signal and it can be used for constant or time-varying external trigger signals.

  12. An Inductorless Self-Controlled Rectifier for Piezoelectric Energy Harvesting.

    PubMed

    Lu, Shaohua; Boussaid, Farid

    2015-01-01

    This paper presents a high-efficiency inductorless self-controlled rectifier for piezoelectric energy harvesting. High efficiency is achieved by discharging the piezoelectric device (PD) capacitance each time the current produced by the PD changes polarity. This is achieved automatically without the use of delay lines, thereby making the proposed circuit compatible with any type of PD. In addition, the proposed rectifier alleviates the need for an inductor, making it suitable for on-chip integration. Reported experimental results show that the proposed rectifier can harvest up to 3.9 times more energy than a full wave bridge rectifier. PMID:26610492

  13. An Inductorless Self-Controlled Rectifier for Piezoelectric Energy Harvesting

    PubMed Central

    Lu, Shaohua; Boussaid, Farid

    2015-01-01

    This paper presents a high-efficiency inductorless self-controlled rectifier for piezoelectric energy harvesting. High efficiency is achieved by discharging the piezoelectric device (PD) capacitance each time the current produced by the PD changes polarity. This is achieved automatically without the use of delay lines, thereby making the proposed circuit compatible with any type of PD. In addition, the proposed rectifier alleviates the need for an inductor, making it suitable for on-chip integration. Reported experimental results show that the proposed rectifier can harvest up to 3.9 times more energy than a full wave bridge rectifier. PMID:26610492

  14. Analysis of junction-barrier-controlled Schottky (JBS) rectifier characteristics

    NASA Astrophysics Data System (ADS)

    Baliga, B. Jayant

    1985-11-01

    This paper provides analytical solutions for the forward conduction and reverse leakage characteristics of junction-barrier-controlled Schottky (JBS) rectifiers. Good agreement between the calculated output characteristics using these solutions and experimental measurements on devices fabricated with different junction depths and Schottky barrier heights is observed. These equations are valuable for the analysis and design of JBS power rectifiers.

  15. Improved control configuration of PWM rectifiers based on neuro-fuzzy controller.

    PubMed

    Acikgoz, Hakan; Kececioglu, O Fatih; Gani, Ahmet; Yildiz, Ceyhun; Sekkeli, Mustafa

    2016-01-01

    It is well-known that rectifiers are used widely in many applications required AC/DC transformation. With technological advances, many studies are performed for AC/DC converters and many control methods are proposed in order to improve the performance of these rectifiers in recent years. Pulse width modulation (PWM) based rectifiers are one of the most popular rectifier types. PWM rectifiers have lower input current harmonics and higher power factor compared to classical diode and thyristor rectifiers. In this study, neuro-fuzzy controller (NFC) which has robust, nonlinear structure and do not require the mathematical model of the system to be controlled has been proposed for PWM rectifiers. Three NFCs are used in control scheme of proposed PWM rectifier in order to control the dq-axis currents and DC voltage of PWM rectifier. Moreover, simulation studies are carried out to demonstrate the performance of the proposed control scheme at MATLAB/Simulink environment in terms of rise time, settling time, overshoot, power factor, total harmonic distortion and power quality. PMID:27504240

  16. Design, fabrication, and characterization of 4H-silicon carbide rectifiers for power switching applications

    NASA Astrophysics Data System (ADS)

    Sheridan, David Charles

    Silicon Carbide has received a substantial increase in research interest over the past few years as a base material system for high-frequency and high-power semiconductor devices. Of the over 1200 polytypes, 4H-SiC is the most attractive polytype for power devices due to its wide band gap (3.2eV), excellent thermal conductivity (4.9 W/cm·K), and high critical field strength (˜2 x 106 V/cm). Important for power devices, the 10x increase in critical field strength of SiC allows high voltage blocking layers to be fabricated significantly thinner than for comparable Si devices. For power rectifiers, this reduces device on-resistance, while maintaining the same high voltage blocking capability. In this work, 4H-SiC Schottky, pn, and junction barrier Schottky (JBS) rectifiers for use in high voltage switching applications have been designed, fabricated, and extensively characterized. First, a detailed review of 4H-SiC material parameters was performed and SiC models were implemented into a standard Si drift-diffusion numerical simulator. Using these models, a SiC simulation methodology was developed in order to enable predictive SiC device design. A wide variety of rectifier and edge termination designs were investigated and optimized with respect to breakdown efficiency, area consumption, resistance to interface charge, and fabrication practicality. Simulated termination methods include: field plates, floating guard rings, and a variety of junction termination extensions (JTE). Using the device simulation results, both Schottky and JBS rectifiers were fabricated with a novel self-aligned edge termination design, and fabricated with process elements developed at the Alabama Microelectronics Science and Technology Center facility. These rectifiers exhibited near-ideal forward characteristics and had blocking voltages in excess of 2.5kV. The SiC diodes were subjected to inductive switching tests, and were found to have superior reverse recovery characteristics compared

  17. Fast controller for a unity-power-factor PWM rectifier

    SciTech Connect

    Eissa, M.O.; Leeb, S.B.; Verghese, G.C.; Stankovic, A.M.

    1996-01-01

    This paper presents an analog implementation of a fast controller for a unity-power-factor (UPF) PWM rectifier. The best settling times of many popular controllers for this type of converter are on the order of a few line cycles, corresponding to bandwidths under 20 Hz. The fast controller demonstrated in this paper can exercise control action at a rate comparable to the switching frequency rather than the line frequency. In order to accomplish this while maintaining unity power factor during steady-state operation, the fast controller employs a ripple-feedback cancellation scheme.

  18. Temperature-gated thermal rectifier for active heat flow control.

    PubMed

    Zhu, Jia; Hippalgaonkar, Kedar; Shen, Sheng; Wang, Kevin; Abate, Yohannes; Lee, Sangwook; Wu, Junqiao; Yin, Xiaobo; Majumdar, Arun; Zhang, Xiang

    2014-08-13

    Active heat flow control is essential for broad applications of heating, cooling, and energy conversion. Like electronic devices developed for the control of electric power, it is very desirable to develop advanced all-thermal solid-state devices that actively control heat flow without consuming other forms of energy. Here we demonstrate temperature-gated thermal rectification using vanadium dioxide beams in which the environmental temperature actively modulates asymmetric heat flow. In this three terminal device, there are two switchable states, which can be regulated by global heating. In the "Rectifier" state, we observe up to 28% thermal rectification. In the "Resistor" state, the thermal rectification is significantly suppressed (<1%). To the best of our knowledge, this is the first demonstration of solid-state active-thermal devices with a large rectification in the Rectifier state. This temperature-gated rectifier can have substantial implications ranging from autonomous thermal management of heating and cooling systems to efficient thermal energy conversion and storage. PMID:25010206

  19. Modelling a single phase voltage controlled rectifier using Laplace transforms

    NASA Technical Reports Server (NTRS)

    Kraft, L. Alan; Kankam, M. David

    1992-01-01

    The development of a 20 kHz, AC power system by NASA for large space projects has spurred a need to develop models for the equipment which will be used on these single phase systems. To date, models for the AC source (i.e., inverters) have been developed. It is the intent of this paper to develop a method to model the single phase voltage controlled rectifiers which will be attached to the AC power grid as an interface for connected loads. A modified version of EPRI's HARMFLO program is used as the shell for these models. The results obtained from the model developed in this paper are quite adequate for the analysis of problems such as voltage resonance. The unique technique presented in this paper uses the Laplace transforms to determine the harmonic content of the load current of the rectifier rather than a curve fitting technique. Laplace transforms yield the coefficient of the differential equations which model the line current to the rectifier directly.

  20. Low-Loss Schottky Rectifier Utilizing Trench Sidewall as Junction-Barrier-Controlled Schottky Contact

    NASA Astrophysics Data System (ADS)

    Kim, Han-Soo; Kim, Seong-Dong; Han, Min-Koo; Choi, Yearn-Ik

    1995-02-01

    A novel junction barrier contolled Schottky (JBS) rectifier structure, which has increased the Schottky contact area by utilizing the trench sidewall, has been proposed. The proposed device consists of a JBS rectifier positioned vertically along the trench sidewall as well as laterally along the surface. The additional sidewall Schottky contact reduces the forward voltage drop by enlarging the Schottky active area. The new trench structure shifts the peak electric field from Schottky contact surface to the silicon bulk and the leakage current by the barrier height lowering effect is decreased. An intensive 2-dimensional numerical simulation by MEDICI shows that the leakage current of the trenched JBS rectifier is less than 60% of that of the conventional Schottky rectifier, while the forward voltage drop of the trenched JBS rectifier is almost the same as that of the conventional Schottky rectifier.

  1. A Novel Phase-Shift Control of Semibridgeless Active Rectifier for Wireless Power Transfer

    SciTech Connect

    Colak, Kerim; Asa, Erdem; Bojarski, Mariusz; Czarkowski, Dariusz; Onar, Omer C.

    2015-05-12

    We investigated a novel phase-shift control of a semibridgeless active rectifier (S-BAR) in order to utilize the S-BAR in wireless energy transfer applications. The standard receiver-side rectifier topology is developed by replacing rectifier lower diodes with synchronous switches controlled by a phase-shifted PWM signal. Moreover, theoretical and simulation results showthat with the proposed control technique, the output quantities can be regulated without communication between the receiver and transmitter. In order to confirm the performance of the proposed converter and control, experimental results are provided using 8-, 15-, and 23-cm air gap coreless transformer which has dimension of 76 cm x 76 cm, with 120-V input and the output power range of 0 to 1kW with a maximum efficiency of 94.4%.

  2. A Novel Phase-Shift Control of Semibridgeless Active Rectifier for Wireless Power Transfer

    DOE PAGESBeta

    Colak, Kerim; Asa, Erdem; Bojarski, Mariusz; Czarkowski, Dariusz; Onar, Omer C.

    2015-05-12

    We investigated a novel phase-shift control of a semibridgeless active rectifier (S-BAR) in order to utilize the S-BAR in wireless energy transfer applications. The standard receiver-side rectifier topology is developed by replacing rectifier lower diodes with synchronous switches controlled by a phase-shifted PWM signal. Moreover, theoretical and simulation results showthat with the proposed control technique, the output quantities can be regulated without communication between the receiver and transmitter. In order to confirm the performance of the proposed converter and control, experimental results are provided using 8-, 15-, and 23-cm air gap coreless transformer which has dimension of 76 cm xmore » 76 cm, with 120-V input and the output power range of 0 to 1kW with a maximum efficiency of 94.4%.« less

  3. Advanced Control Strategy for Single-Phase Voltage-Source Active Rectifier with Low Harmonic Emission

    NASA Astrophysics Data System (ADS)

    Blahník, Vojtĕch; Peroutka, Zdenĕk; Talla, Jakub

    2014-03-01

    This paper introduces the advanced control of single-phase voltage-source active rectifier. This control provide direct control of trolley-wire current and active damping of low-frequency disturbances at the converter ac side. Our proposed control strategy combines PR controller with feed-forward model and low-frequency harmonic compensator based on resonant controllers. Achieved experimental results show excellent converter behavior, where converter is fed by strongly distorted supply voltage.

  4. WASTE MINIMIZATION ASSESSMENT FOR A MANUFACTURER OF SILICON-CONTROLLED RECTIFIERS AND SCHOTTKY RECTIFIERS

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) has funded a pilot project to assist small- and medium-size manufacturers who want to minimize their generation of waste but who lack the expertise to do so. In an effort to assist these manufacturers Waste Minimization Assessment Ce...

  5. High-performance digital triggering system for phase-controlled rectifiers

    SciTech Connect

    Olsen, R.E.

    1983-01-01

    The larger power supplies used to power accelerator magnets are most commonly polyphase rectifiers using phase control. While this method is capable of handling impressive amounts of power, it suffers from one serious disadvantage, namely that of subharmonic ripple. Since the stability of the stored beam depends to a considerable extent on the regulation of the current in the bending magnets, subharmonic ripple, especially that of low frequency, can have a detrimental effect. At the NSLS, we have constructed a 12-pulse, phase control system using digital signal processing techniques that essentially eliminates subharmonic ripple.

  6. Structural basis of control of inward rectifier Kir2 channel gating by bulk anionic phospholipids.

    PubMed

    Lee, Sun-Joo; Ren, Feifei; Zangerl-Plessl, Eva-Maria; Heyman, Sarah; Stary-Weinzinger, Anna; Yuan, Peng; Nichols, Colin G

    2016-09-01

    Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP2) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL(-)) with a distinct second site is required for high PIP2 sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP2 sensitivity, even in the absence of PL(-) Furthermore, high-resolution x-ray crystal structures of Kir2.2[K62W], with or without added PIP2 (2.8- and 2.0-Å resolution, respectively), reveal tight tethering of the C-terminal domain (CTD) to the transmembrane domain (TMD) in each condition. Our results suggest a refined model for phospholipid gating in which PL(-) binding at the second site pulls the CTD toward the membrane, inducing the formation of the high-affinity primary PIP2 site and explaining the positive allostery between PL(-) binding and PIP2 sensitivity. PMID:27527100

  7. Combinational logic for generating gate drive signals for phase control rectifiers

    NASA Technical Reports Server (NTRS)

    Dolland, C. R.; Trimble, D. W. (Inventor)

    1982-01-01

    Control signals for phase-delay rectifiers, which require a variable firing angle that ranges from 0 deg to 180 deg, are derived from line-to-line 3-phase signals and both positive and negative firing angle control signals which are generated by comparing current command and actual current. Line-to-line phases are transformed into line-to-neutral phases and integrated to produce 90 deg phase delayed signals that are inverted to produce three cosine signals, such that for each its maximum occurs at the intersection of positive half cycles of the other two phases which are inputs to other inverters. At the same time, both positive and negative (inverted) phase sync signals are generated for each phase by comparing each with the next and producing a square wave when it is greater. Ramp, sync and firing angle controls signals are than used in combinational logic to generate the gate firing control signals SCR gate drives which fire SCR devices in a bridge circuit.

  8. Real-time multi-DSP control of three-phase current-source unity power factor PWM rectifier

    SciTech Connect

    Xiao Wang; Boon-Teck Ooi . Dept. of Electrical Engineering)

    1993-07-01

    The design of a real-time multi-DSP controller for a high-quality six-valve three-phase current-source unity power factor PWM rectifier is discussed in this paper. With the decoupler preprocessor and the dynamic trilogic PWM trigger scheme, each of the three input currents can be controlled independently. Based on the a-b-c frame system model and the fast parallel computer control, the pole-placement control method is implemented successfully to achieve fast response in the ac currents. The low-frequency resonance in the ac filter L-C networks has been damped effectively. The experimental results are obtained from a 1-kVA bipolar transistor current-source PWM rectifier with a real-time controller using three TMS320C25 DSP's.

  9. Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems.

    PubMed

    Okabe, Kenji; Jeewan, Horagodage Prabhath; Yamagiwa, Shota; Kawano, Takeshi; Ishida, Makoto; Akita, Ippei

    2015-01-01

    In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 μm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction. PMID:26694407

  10. Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems

    PubMed Central

    Okabe, Kenji; Jeewan, Horagodage Prabhath; Yamagiwa, Shota; Kawano, Takeshi; Ishida, Makoto; Akita, Ippei

    2015-01-01

    In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 μm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction. PMID:26694407

  11. Transformer-rectifier flux pump using inductive current transfer and thermally controlled Nb(3)Sn cryotrons.

    PubMed

    Atherton, D L; Davies, R

    1979-10-01

    Transformer-rectifier flux pumps using thermally switched Nb(3)Sn cryotrons are being investigated as a loss make-up device for the proposed isochorically operated (sealed) superconducting magnets for the Canadian Maglev vehicle. High currents (1000 A) were obtained in an experimental flux pump using inductive current transfer and operating at 2 Hz. PMID:18699368

  12. Rectifier cabinet static breaker

    DOEpatents

    Costantino, Jr, Roger A.; Gliebe, Ronald J.

    1992-09-01

    A rectifier cabinet static breaker replaces a blocking diode pair with an SCR and the installation of a power transistor in parallel with the latch contactor to commutate the SCR to the off state. The SCR serves as a static breaker with fast turnoff capability providing an alternative way of achieving reactor scram in addition to performing the function of the replaced blocking diodes. The control circuitry for the rectifier cabinet static breaker includes on-line test capability and an LED indicator light to denote successful test completion. Current limit circuitry provides high-speed protection in the event of overload.

  13. Rectifier cabinet static breaker

    SciTech Connect

    Costantino, R.A. Jr; Gliebe, R.J.

    1992-09-01

    A rectifier cabinet static breaker replaces a blocking diode pair with an SCR and the installation of a power transistor in parallel with the latch contactor to commutate the SCR to the off state. The SCR serves as a static breaker with fast turnoff capability providing an alternative way of achieving reactor scram in addition to performing the function of the replaced blocking diodes. The control circuitry for the rectifier cabinet static breaker includes on-line test capability and an LED indicator light to denote successful test completion. Current limit circuitry provides high-speed protection in the event of overload. 7 figs.

  14. Silicon-controlled-rectifier square-wave inverter with protection against commutation failure

    NASA Technical Reports Server (NTRS)

    Birchenough, A. G.

    1971-01-01

    The square-wave SCR inverter that was designed, built, and tested includes a circuit to turn off the inverter in case of commutation failure. The basic power stage is a complementary impulse-commutated parallel inverter consisting of only six components. The 400-watt breadboard was tested while operating at + or - 28 volts, and it had a peak efficiency of 95.5 percent at 60 hertz and 91.7 percent at 400 hertz. The voltage regulation for a fixed input was 3 percent at 60 hertz. An analysis of the operation and design information is included.

  15. Design and analysis of an automatic method of measuring silicon-controlled-rectifier holding current

    NASA Technical Reports Server (NTRS)

    Maslowski, E. A.

    1971-01-01

    The design of an automated SCR holding-current measurement system is described. The circuits used in the measurement system were designed to meet the major requirements of automatic data acquisition, reliability, and repeatability. Performance data are presented and compared with calibration data. The data verified the accuracy of the measurement system. Data taken over a 48-hr period showed that the measurement system operated satisfactorily and met all the design requirements.

  16. Silicon controlled rectifier polyphase bridge inverter commutated with gate-turn-off thyristor

    NASA Technical Reports Server (NTRS)

    Edwards, Dean B. (Inventor); Rippel, Wally E. (Inventor)

    1986-01-01

    A polyphase SCR inverter (10) having N switching poles, each comprised of two SCR switches (1A, 1B; 2A, 2B . . . NA, NB) and two diodes (D1B; D1B; D2A, D2B . . . DNA, DNB) in series opposition with saturable reactors (L1A, L1B; L2A, L2B . . . LNA, LNB) connecting the junctions between the SCR switches and diodes to an output terminal (1, 2 . . . 3) is commutated with only one GTO thyristor (16) connected between the common negative terminal of a dc source and a tap of a series inductor (14) connected to the positive terminal of the dc source. A clamp winding (22) and diode (24) are provided, as is a snubber (18) which may have its capacitance (c) sized for maximum load current divided into a plurality of capacitors (C.sub.1, C.sub.2 . . . C.sub.N), each in series with an SCR switch S.sub.1, S.sub.2 . . . S.sub.N). The total capacitance may be selected by activating selected switches as a function of load current. A resistor 28 and SCR switch 26 shunt reverse current when the load acts as a generator, such as a motor while braking.

  17. The inwardly rectifying K+ channel KIR7.1 controls uterine excitability throughout pregnancy

    PubMed Central

    McCloskey, Conor; Rada, Cara; Bailey, Elizabeth; McCavera, Samantha; van den Berg, Hugo A; Atia, Jolene; Rand, David A; Shmygol, Anatoly; Chan, Yi-Wah; Quenby, Siobhan; Brosens, Jan J; Vatish, Manu; Zhang, Jie; Denton, Jerod S; Taggart, Michael J; Kettleborough, Catherine; Tickle, David; Jerman, Jeff; Wright, Paul; Dale, Timothy; Kanumilli, Srinivasan; Trezise, Derek J; Thornton, Steve; Brown, Pamela; Catalano, Roberto; Lin, Nan; England, Sarah K; Blanks, Andrew M

    2014-01-01

    Abnormal uterine activity in pregnancy causes a range of important clinical disorders, including preterm birth, dysfunctional labour and post-partum haemorrhage. Uterine contractile patterns are controlled by the generation of complex electrical signals at the myometrial smooth muscle plasma membrane. To identify novel targets to treat conditions associated with uterine dysfunction, we undertook a genome-wide screen of potassium channels that are enriched in myometrial smooth muscle. Computational modelling identified Kir7.1 as potentially important in regulating uterine excitability during pregnancy. We demonstrate Kir7.1 current hyper-polarizes uterine myocytes and promotes quiescence during gestation. Labour is associated with a decline, but not loss, of Kir7.1 expression. Knockdown of Kir7.1 by lentiviral expression of miRNA was sufficient to increase uterine contractile force and duration significantly. Conversely, overexpression of Kir7.1 inhibited uterine contractility. Finally, we demonstrate that the Kir7.1 inhibitor VU590 as well as novel derivative compounds induces profound, long-lasting contractions in mouse and human myometrium; the activity of these inhibitors exceeds that of other uterotonic drugs. We conclude Kir7.1 regulates the transition from quiescence to contractions in the pregnant uterus and may be a target for therapies to control uterine contractility. PMID:25056913

  18. Control of Inward Rectifier K Channel Activity by Lipid Tethering of Cytoplasmic Domains

    PubMed Central

    Enkvetchakul, Decha; Jeliazkova, Iana; Bhattacharyya, Jaya; Nichols, Colin G.

    2007-01-01

    Interactions between nontransmembrane domains and the lipid membrane are proposed to modulate activity of many ion channels. In Kir channels, the so-called “slide-helix” is proposed to interact with the lipid headgroups and control channel gating. We examined this possibility directly in a cell-free system consisting of KirBac1.1 reconstituted into pure lipid vesicles. Cysteine substitution of positively charged slide-helix residues (R49C and K57C) leads to loss of channel activity that is rescued by in situ restoration of charge following modification by MTSET+ or MTSEA+, but not MTSES− or neutral MMTS. Strikingly, activity is also rescued by modification with long-chain alkyl-MTS reagents. Such reagents are expected to partition into, and hence tether the side chain to, the membrane. Systematic scanning reveals additional slide-helix residues that are activated or inhibited following alkyl-MTS modification. A pattern emerges whereby lipid tethering of the N terminus, or C terminus, of the slide-helix, respectively inhibits, or activates, channel activity. This study establishes a critical role of the slide-helix in Kir channel gating, and directly demonstrates that physical interaction of soluble domains with the membrane can control ion channel activity. PMID:17698595

  19. Noise Properties of Rectifying Nanopore

    SciTech Connect

    Vlassiouk, Ivan V

    2011-01-01

    Ion currents through three types of rectifying nanoporous structures are studied and compared: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by the power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer nanopores exhibit nonequilibrium 1/f noise; thus, the normalized power spectrum depends on the voltage polarity and magnitude. In contrast, 1/f noise in rectifying silicon nitride nanopores is of equilibrium character. Various mechanisms underlying the voltage-dependent 1/f noise are explored and discussed, including intrinsic pore wall dynamics and formation of vortices and nonlinear flow patterns in the pore. Experimental data are supported by modeling of ion currents based on the coupled Poisson-Nernst-Planck and Navier-Stokes equations. We conclude that the voltage-dependent 1/f noise observed in polymer and glass asymmetric nanopores might result from high and asymmetric electric fields, inducing secondary effects in the pore, such as enhanced water dissociation.

  20. Noise Properties of Rectifying Nanopores

    SciTech Connect

    Powell, M R; Sa, N; Davenport, M; Healy, K; Vlassiouk, I; Letant, S E; Baker, L A; Siwy, Z S

    2011-02-18

    Ion currents through three types of rectifying nanoporous structures are studied and compared for the first time: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer nanopores exhibit non-equilibrium 1/f noise, thus the normalized power spectrum depends on the voltage polarity and magnitude. In contrast, 1/f noise in rectifying silicon nitride nanopores is of equilibrium character. Various mechanisms underlying the voltage-dependent 1/f noise are explored and discussed, including intrinsic pore wall dynamics, and formation of vortices and non-linear flow patterns in the pore. Experimental data are supported by modeling of ion currents based on the coupled Poisson-Nernst-Planck and Navier Stokes equations. We conclude that the voltage-dependent 1/f noise observed in polymer and glass asymmetric nanopores might result from high and asymmetric electric fields inducing secondary effects in the pore such as enhanced water dissociation.

  1. Controlled Adhesion of Silicone Elastomer Surfaces

    NASA Astrophysics Data System (ADS)

    Owen, Michael

    2000-03-01

    Opportunities exist for controllably enhancing the adhesion of silicone surfaces, ranging from modest enhancement of release force levels of pressure-sensitive adhesive (PSA) release liners by incorporation of adhesion promoters known as high release additives (HRA), to permanent bonding of silicone elastomers using surface modification techniques such as plasma or corona treatment. Although only a part of the complex interaction of factors contributing to adhesion, surface properties such as wettability are a critical component in the understanding and control of release and adhesion phenomena. Surface characterization studies of low-surface-energy silicones before and after various adhesion modification strategies are reviewed. The silicones include polydimethylsiloxane (PDMS) and fluorosiloxane elastomers and coatings. Techniques used include contact angle, the Johnson, Kendall and Roberts (JKR) contact mechanics approach, scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). Topics addressed are: use of HRA in PDMS release liners, the interaction of PDMS PSAs with polytetrafluoroethylene (PTFE), and the effect of plasma treatment on PDMS and fluorosiloxane surfaces.

  2. Control of silicon nanoparticle size embedded in silicon oxynitride dielectric matrix

    SciTech Connect

    Ehrhardt, F.; Ferblantier, G.; Muller, D.; Slaoui, A.; Ulhaq-Bouillet, C.; Rinnert, H.

    2013-07-21

    In this study, silicon rich silicon oxynitride layers containing more than 15% nitrogen were deposited by electron cyclotron resonance assisted plasma enhanced vapor deposition in order to form silicon nanoparticles after a high temperature thermal annealing. The effect of the flows of the precursor gases on the composition and the structural properties of the layers was assessed by Rutherford backscattering spectroscopy, elastic recoil detection analysis, and infrared spectroscopic measurements. The morphological and crystallinity properties were investigated by energy filtered transmission electron microscopy and Raman spectroscopy. We show that the excess of silicon in the silicon oxynitride layer controls the silicon nanoparticles size. On the other hand, the crystalline fraction of particles is found to be strongly correlated to the nanoparticle size. Finally, the photoluminescence measurements show that it is also possible to tune the photoluminescence peak position between 400 and 800 nm and its intensity by changing the silicon excess in the silicon rich silicon oxynitride matrix.

  3. Silicon Sheet Quality is Improved By Meniscus Control

    NASA Technical Reports Server (NTRS)

    Yates, D. A.; Hatch, A. E.; Goldsmith, J. M.

    1983-01-01

    Better quality silicon crystals for solar cells are possible with instrument that monitors position of meniscus as sheet of solid silicon is drawn from melt. Using information on meniscus height, instrument generates feedback signal to control melt temperature. Automatic control ensures more uniform silicon sheets.

  4. Curvature Control of Silicon Microlens for THz Dielectric Antenna

    NASA Technical Reports Server (NTRS)

    Lee, Choonsup; Chattopadhyay, Goutam; Cooper, Ken; Mehdi, Imran

    2012-01-01

    We have controlled the curvature of silicon microlens by changing the amount of photoresist in order to microfabricate hemispherical silicon microlens which can improve the directivity and reduce substrate mode losses.

  5. Optically controlled quadrature coupler on silicon substrate

    NASA Astrophysics Data System (ADS)

    Bhadauria, Avanish; Sharma, Sonia; Sonania, Shikha; Akhtar, Jamil

    2016-03-01

    In this paper, we have proposed and studied an optically controlled quadrature coupler fabricated on silicon substrate. The optically controlled quadrature coupler can be realized by terminating its coupled or through ports by optically induced load. Simulation and experimental results show that by varying optical intensity, we can control the phase and amplitude of output RF signal and can realize optically controlled reflection type attenuator, reflection type phase-shifter and ultrafast switches. The new kind of proposed device can be useful for ultra-fast signal processing and modulation schemes in high speed communication especially in QPSK modulation. The optical control has several advantages over conventional techniques such as MEMS and other semiconductor switching, which have several inherent disadvantages and limitations like low response time, low power handling capacity, device parasitic and non-linearity.

  6. Solid state circuit controls direction, speed, and braking of dc motor

    NASA Technical Reports Server (NTRS)

    Hanna, M. F.

    1966-01-01

    Full-wave bridge rectifier circuit controls the direction, speed, and braking of a dc motor. Gating in the circuit of Silicon Controlled Rectifiers /SCRS/ controls output polarity and braking is provided by an SCR that is gated to short circuit the reverse voltage generated by reversal of motor rotation.

  7. 96. RECTIFIER NUMBER 1 AND RECTIFIER NUMBER 2 ON EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    96. RECTIFIER NUMBER 1 AND RECTIFIER NUMBER 2 ON EAST WALL OF LANDLINE INSTRUMENTATION ROOM (106), LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  8. Artificial neural networks for control of a grid-connected rectifier/inverter under disturbance, dynamic and power converter switching conditions.

    PubMed

    Li, Shuhui; Fairbank, Michael; Johnson, Cameron; Wunsch, Donald C; Alonso, Eduardo; Proaño, Julio L

    2014-04-01

    Three-phase grid-connected converters are widely used in renewable and electric power system applications. Traditionally, grid-connected converters are controlled with standard decoupled d-q vector control mechanisms. However, recent studies indicate that such mechanisms show limitations in their applicability to dynamic systems. This paper investigates how to mitigate such restrictions using a neural network to control a grid-connected rectifier/inverter. The neural network implements a dynamic programming algorithm and is trained by using back-propagation through time. To enhance performance and stability under disturbance, additional strategies are adopted, including the use of integrals of error signals to the network inputs and the introduction of grid disturbance voltage to the outputs of a well-trained network. The performance of the neural-network controller is studied under typical vector control conditions and compared against conventional vector control methods, which demonstrates that the neural vector control strategy proposed in this paper is effective. Even in dynamic and power converter switching environments, the neural vector controller shows strong ability to trace rapidly changing reference commands, tolerate system disturbances, and satisfy control requirements for a faulted power system. PMID:24807951

  9. Electrically controlled giant piezoresistance in silicon nanowires.

    PubMed

    Neuzil, Pavel; Wong, Chee Chung; Reboud, Julien

    2010-04-14

    Herein we demonstrate giant piezoresistance in silicon nanowires (NWs) by the modulation of an electric field-induced with an external electrical bias. Positive bias for a p-type device (negative for an n-type) partially depleted the NWs forming a pinch-off region, which resembled a funnel through which the electrical current squeezed. This region determined the total current flowing through the NWs. In this report, we combined the electrical biasing with the application of mechanical stress, which impacts the charge carriers' concentration, to achieve an electrically controlled giant piezoresistance in nanowires. This phenomenon was used to create a stress-gated field-effect transistor, exhibiting a maximum gauge factor of 5000, 2 orders of magnitude increase over bulk value. Giant piezoresistance can be tailored to create highly sensitive mechanical sensors operating in a discrete mode such as nanoelectromechanical switches. PMID:20192246

  10. Coherent control of Rydberg states in silicon.

    PubMed

    Greenland, P T; Lynch, S A; van der Meer, A F G; Murdin, B N; Pidgeon, C R; Redlich, B; Vinh, N Q; Aeppli, G

    2010-06-24

    Laser cooling and electromagnetic traps have led to a revolution in atomic physics, yielding dramatic discoveries ranging from Bose-Einstein condensation to the quantum control of single atoms. Of particular interest, because they can be used in the quantum control of one atom by another, are excited Rydberg states, where wavefunctions are expanded from their ground-state extents of less than 0.1 nm to several nanometres and even beyond; this allows atoms far enough apart to be non-interacting in their ground states to strongly interact in their excited states. For eventual application of such states, a solid-state implementation is very desirable. Here we demonstrate the coherent control of impurity wavefunctions in the most ubiquitous donor in a semiconductor, namely phosphorus-doped silicon. In our experiments, we use a free-electron laser to stimulate and observe photon echoes, the orbital analogue of the Hahn spin echo, and Rabi oscillations familiar from magnetic resonance spectroscopy. As well as extending atomic physicists' explorations of quantum phenomena to the solid state, our work adds coherent terahertz radiation, as a particularly precise regulator of orbitals in solids, to the list of controls, such as pressure and chemical composition, already familiar to materials scientists. PMID:20577211

  11. Current Control Method to Achieve Wide-Range Power Driving for Linear Synchronous Motor with Half-Wave-Rectified Self-Excitation

    NASA Astrophysics Data System (ADS)

    Hirayama, Tadashi; Higuchi, Tsuyoshi

    In a previous paper, we proposed a novel linear synchronous motor with half-wave-rectified self-excitation. The long-stator-type linear synchronous motor was built, and its performance was verified by performing experiments. This paper presents a new current control method for the linear synchronous motor for achieving a wide range of speeds and high-power operations. First, we propose the current control method for high-thrust operation in the constant-thrust region. This operation is realized by using a reluctance thrust resulting from the saliency of the linear synchronous motor. Furthermore, we propose a control method that maximizes the ratio of the thrust to the voltage; this method can be used to expand the operating range. Wide-range-speed operation can be achieved by applying this new control method along with field-weakening control. The thrust and operation characteristics of the proposed control methods are estimated by performing experiments and an electric and magnetic coupled analysis.

  12. Solid state thermal rectifier

    DOEpatents

    None

    2016-07-05

    Thermal rectifiers using linear nanostructures as core thermal conductors have been fabricated. A high mass density material is added preferentially to one end of the nanostructures to produce an axially non-uniform mass distribution. The resulting nanoscale system conducts heat asymmetrically with greatest heat flow in the direction of decreasing mass density. Thermal rectification has been demonstrated for linear nanostructures that are electrical insulators, such as boron nitride nanotubes, and for nanostructures that are conductive, such as carbon nanotubes.

  13. Unimolecular rectifiers: Present status

    NASA Astrophysics Data System (ADS)

    Metzger, Robert M.

    2006-07-01

    Many experimental issues presented here must be resolved before we can really understand unimolecular rectification. Nevertheless, at the University of Alabama six unimolecular rectifiers have been studied (Fig. 1, 1- 6). Langmuir-Blodgett (LB) or Langmuir-Schaefer (LS) monolayer films of these molecules show asymmetric electrical conductivity between Au and Al electrodes. When the films are very compact (LS of 4, LB of 5), and if there is finite intramolecular charge transfer (ICT, or intervalence transfer, IVT), then the electrical behavior persists for many cycles of measurement.

  14. Method of controlling defect orientation in silicon crystal ribbon growth

    NASA Technical Reports Server (NTRS)

    Leipold, M. H. (Inventor)

    1978-01-01

    The orientation of twinning and other effects in silicon crystal ribbon growth is controlled by use of a starting seed crystal having a specific (110) crystallographic plane and (112) crystallographic growth direction.

  15. Black silicon with controllable macropore array for enhanced photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Ao, Xianyu; Tong, Xili; Sik Kim, Dong; Zhang, Lianbing; Knez, Mato; Müller, Frank; He, Sailing; Schmidt, Volker

    2012-09-01

    Macroporous silicon with multiscale texture for reflection suppression and light trapping was achieved through a controllable electrochemical etching process. It was coated with TiO2 by atomic layer deposition, and used as the photoanode in photocatalytic water splitting. A conformal pn-junction was also built-in in order to split water without external bias. A 45% enhancement in photocurrent density was observed after black silicon etching. In comparison with nano-structured silicon, the etching process here has neither metal contamination nor requirement of vacuum facilities.

  16. Controllable deformation of silicon nanowires with strain up to 24%

    SciTech Connect

    Walavalkar, Sameer S.; Homyk, Andrew P.; Henry, M. David; Scherer, Axel

    2010-06-15

    Fabricated silicon nanostructures demonstrate mechanical properties unlike their macroscopic counterparts. Here we use a force mediating polymer to controllably and reversibly deform silicon nanowires. This technique is demonstrated on multiple nanowire configurations, which undergo deformation without noticeable macroscopic damage after the polymer is removed. Calculations estimate a maximum of nearly 24% strain induced in 30 nm diameter pillars. The use of an electron activated polymer allows retention of the strained configuration without any external input. As a further illustration of this technique, we demonstrate nanoscale tweezing by capturing 300 nm alumina beads using circular arrays of these silicon nanowires.

  17. A simple method to control nanotribology behaviors of monocrystalline silicon

    NASA Astrophysics Data System (ADS)

    Wang, X. D.; Guo, J.; Chen, C.; Chen, L.; Qian, L. M.

    2016-01-01

    A simple method was proposed to control the nanotribology behaviors of monocrystalline silicon against SiO2 microsphere by adjusting relative humidity (RH). Experimental results indicated that adhesion work, friction coefficient, and nanowear of silicon against SiO2 microsphere significantly varied between 60% and 90% RH. Under 60% RH, adhesion work was 119 mN/m, and friction coefficient was about 0.53. However, adhesion work and friction coefficient decreased to ˜70 mN/m and ˜0.3 under 90% RH, respectively. An apparent wear track ˜13 nm deep formed on the silicon surface under 60% RH, whereas no obvious wear scar was observed on the silicon surface under 90% RH. Analysis indicated that such tribological behaviors were due to different water condensations on the silicon surface under 60% and 90% RH. Under 60% RH, the water that condensed on the surfaces of the silicon sample and SiO2 tip mainly consisted of ice-like water. As a result, adhesion work was enlarged by the breaking force of the ice-like water bridge in the contact area. Given that a ≡Si-O-Si≡ bonding bridge easily formed between the silicon surface and the SiO2 tip with the help of water condensation under 60% RH instead of 90% RH, the friction coefficient was large and the nanowear of the silicon sample was severe under 60% RH. These results may help elucidate the nanotribology behaviors of silicon and facilitate the tribological design of dynamic microelectromechanical systems working under humid conditions.

  18. High-current, low-forward-drop JBS power rectifiers

    NASA Astrophysics Data System (ADS)

    Chang, H.-R.; Baliga, B. J.

    1986-03-01

    The junction- barrier-controlled Schottky (JBS) rectifier is a Schottky rectifier with a p- n junction grid structure integrated into the device structure to improve its reverse blocking characteristics. This paper reports the development of large area (0.5 cm 2), 30 V, JBS rectifiers capable of handling over 25 A of forward current while operating at up to 125°C with good reverse blocking characteristics. Trade-off curves between forward voltage drop and reverse leakage current are introduced to allow optimization of these devices.

  19. Controlled growth of nanocrystalline silicon within amorphous silicon carbide thin films

    NASA Astrophysics Data System (ADS)

    Kole, Arindam; Chaudhuri, Partha

    2014-04-01

    Controlled formation of nanocrystalline silicon (nc-Si) within hydrogenated amorphous silicon carbide (a-SiC:H) thin films has been demonstrated by a rf (13.56 MHz) plasma chemical vapour deposition (PECVD) method at a low deposition temperature of 200°C by regulating the deposition pressure (Pr) between 26.7 Pa and 133.3 Pa. Evolution of the size and the crystalline silicon volume fraction within the a-SiC:H matrix has been studied by XRD, Raman and HRTEM. The study reveals that at Pr of 26.7 Pa there are mostly isolated grains of nc-Si within the a-SiC:H matrix with average size of 4.5 nm. With increase of Pr the isolated nc-Si grains coalesce more and more giving rise to larger size connected nc-Si islands which appear as microcrystalline silicon in the Raman spectra. As a result net isolated nc-Si volume fraction decreases while the total crystalline silicon volume fraction increases.

  20. A current-type PWM rectifier with active damping function

    SciTech Connect

    Sato, Yukihiko; Kataoka, Teruo

    1996-05-01

    A new control method for current-type pulse-width modulation (PWM) rectifiers which can provide active damping function is presented. This damping function is effective only on the harmonic components of ac input current selectively. Thus steady-state waveform distortion and transient oscillation of the input current are reduced by the active damping effects. The active damping function can be realized by feedback control of an LC filter connected to the ac side of the rectifier, and it does not require any additional components in the main circuits, permitting a simple circuit configuration. The control system of the proposed PWM rectifier is analyzed by using a simple block diagram developed in the present paper. From the analytical results, the influence of the circuit parameters and control delay on the active damping effects and the stability of the operation are clarified to establish the design method. To confirm the effectiveness of the active damping function, some results of basic experiments are included. As an example of application of the active damping function, the proposed rectifier is applied to reduce the harmonic currents generated by conventional rectifiers operating in parallel with the proposed rectifier. Some experimental results in this application are also included.

  1. Analysis of Single Phase PWM Rectifier for Different Applications

    NASA Astrophysics Data System (ADS)

    Mitra, Arkendu; Chowdhuri, Sumana

    2016-06-01

    This research work investigates the various applications of a PWM rectifier based on its input power factor. Most of the cases, the papers describe the operation of the rectifier used for unity power factor (UPF) operation. Beside this mode of operation, this paper compiles the application of the rectifier as STATCOM also, where the rectifier deals only with reactive power exchange. In this work, the controller is implemented by inserting a loop for reference input of phase angle which will be compared with the actual one, so that user can operate the rectifier at any power factor. Some basic formulae are derived for the input current, active power and reactive power based on which the control circuit is to be designed. Here two Proportional-Integral (PI) controllers are used. A brief description of tuning these two PI controllers is incorporated in this paper. Also some calculations are given to determine the harmonic factors of the input line current from which it is found that the rectifier when operated in each mode operation, the order of the harmonics are very low.

  2. Diameter Controlled of Carbon Nanotubes Synthesized on Nanoporous Silicon Support

    NASA Astrophysics Data System (ADS)

    Asli, N. A.; Shamsudin, M. S.; Maryam, M.; Yusop, S. F. M.; Suriani, A. B.; Rusop, M.; Abdullah, S.

    2013-06-01

    Carbon nanotubes (CNTs) have been successfully synthesized on nanoporous silicon template (NPSiT) using botanical source, camphor oil. Diameter of CNTs synthesized was controlled by pore size of NPSiT prepared by photo-electrochemical anodization method. The diameter of CNTs grown on different NPSiT corresponded to the pore diameter of NPSiT. FESEM images showed self-organized bundles of fiber-like structures of CNTs with diameter of around 20nm which were successfully grown directly on nanoporous silicon while raman spectra obtained ratio of ID/IG at 0.67.

  3. Treatment to Control Adhesion of Silicone-Based Elastomers

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III; Puleo, Bernadette J.; Waters, Deborah L.

    2013-01-01

    Seals are used to facilitate the joining of two items, usually temporarily. At some point in the future, it is expected that the items will need to be separated. This innovation enables control of the adhesive properties of silicone-based elastomers. The innovation may also be effective on elastomers other than the silicone-based ones. A technique has been discovered that decreases the level of adhesion of silicone- based elastomers to negligible levels. The new technique causes less damage to the material compared to alternative adhesion mitigation techniques. Silicone-based elastomers are the only class of rubber-like materials that currently meet NASA s needs for various seal applications. However, silicone-based elastomers have natural inherent adhesive properties. This stickiness can be helpful, but it can frequently cause problems as well, such as when trying to get items apart. In the past, seal adhesion was not always adequately addressed, and has caused in-flight failures where seals were actually pulled from their grooves, preventing subsequent spacecraft docking until the seal was physically removed from the flange via an extravehicular activity (EVA). The primary method used in the past to lower elastomer seal adhesion has been the application of some type of lubricant or grease to the surface of the seal. A newer method uses ultraviolet (UV) radiation a mixture of UV wavelengths in the range of near ultraviolet (NUV) and vacuum ultraviolet (VUV) wavelengths.

  4. Low control-power wavelength conversion on a silicon chip.

    PubMed

    Zhao, Yun; Lombardo, David; Mathews, Jay; Agha, Imad

    2016-08-01

    We demonstrate controlled wavelength conversion on a silicon chip based on four-wave mixing Bragg scattering (FWM-BS). A total conversion efficiency of 5% is achieved with strongly unbalanced pumps and a controlling peak power of 55 mW, while the efficiency is over 15% when using less asymmetric pumps. The numerical simulation agrees with the experimental results. Both time domain and spectral domain noise measurements show as low as 2 dB signal-to-noise ratio (SNR) penalty because of the strong pump noise, two-photon absorption, and free-carrier absorption in silicon. We discuss how the scheme can be used to implement an all-optically controlled high-speed switch. PMID:27472641

  5. Controlled samples for silicon defect and impurity studies

    SciTech Connect

    Ciszek, T.F.

    1995-08-01

    Because of the diverse defects and impurities that are present in any given sample of silicon material, it can be extremely difficult to conduct a controlled experiment to study the influence of any particular defect or impurity on photovoltaic properties such as minority charge carrier lifetime {tau} or solar cell efficiency q. For example, the influence of iron may be different if boron is present, or the influence of silicon self interstitial clusters may be different if oxygen is present. It thus becomes important to conduct such studies on controlled samples where the influence of secondary effects is minimized. At NREL, over the past several years, we have focused on using the high-purity float-zone (FZ) growth method to obtain controlled samples. Because the silicon melt is not in contact with a container, and no heated components are in the growth region, very high purities and low defect levels can be achieved in baseline material. The baseline can be controllably perturbed by introduction of specific defects or impurities. The chart shown below lists some of the types of defect and impurity. combinations that can be studied in this way. The boxes marked with an {open_quotes}x{close_quotes} represent combinations we have studied to some extent.

  6. Polarization-Independent Silicon Metadevices for Efficient Optical Wavefront Control.

    PubMed

    Chong, Katie E; Staude, Isabelle; James, Anthony; Dominguez, Jason; Liu, Sheng; Campione, Salvatore; Subramania, Ganapathi S; Luk, Ting S; Decker, Manuel; Neshev, Dragomir N; Brener, Igal; Kivshar, Yuri S

    2015-08-12

    We experimentally demonstrate a functional silicon metadevice at telecom wavelengths that can efficiently control the wavefront of optical beams by imprinting a spatially varying transmittance phase independent of the polarization of the incident beam. Near-unity transmittance efficiency and close to 0-2π phase coverage are enabled by utilizing the localized electric and magnetic Mie-type resonances of low-loss silicon nanoparticles tailored to behave as electromagnetically dual-symmetric scatterers. We apply this concept to realize a metadevice that converts a Gaussian beam into a vortex beam. The required spatial distribution of transmittance phases is achieved by a variation of the lattice spacing as a single geometric control parameter. PMID:26192100

  7. Polarization-independent silicon metadevices for efficient optical wavefront control

    SciTech Connect

    Chong, Katie E.; Staude, Isabelle; James, Anthony Randolph; Dominguez, Jason James; Liu, Sheng; Campione, Salvatore; Subramania, Ganapathi Subramanian; Luk, Ting S.; Decker, Manuel; Neshev, Dragomir N.; Brener, Igal; Kivshar, Yuri S.

    2015-07-20

    In this study, we experimentally demonstrate a functional silicon metadevice at telecom wavelengths that can efficiently control the wavefront of optical beams by imprinting a spatially varying transmittance phase independent of the polarization of the incident beam. Near-unity transmittance efficiency and close to 0–2π phase coverage are enabled by utilizing the localized electric and magnetic Mie-type resonances of low-loss silicon nanoparticles tailored to behave as electromagnetically dual-symmetric scatterers. We apply this concept to realize a metadevice that converts a Gaussian beam into a vortex beam. The required spatial distribution of transmittance phases is achieved by a variation of the lattice spacing as a single geometric control parameter.

  8. Polarization-independent silicon metadevices for efficient optical wavefront control

    DOE PAGESBeta

    Chong, Katie E.; Staude, Isabelle; James, Anthony Randolph; Dominguez, Jason James; Liu, Sheng; Campione, Salvatore; Subramania, Ganapathi Subramanian; Luk, Ting S.; Decker, Manuel; Neshev, Dragomir N.; et al

    2015-07-20

    In this study, we experimentally demonstrate a functional silicon metadevice at telecom wavelengths that can efficiently control the wavefront of optical beams by imprinting a spatially varying transmittance phase independent of the polarization of the incident beam. Near-unity transmittance efficiency and close to 0–2π phase coverage are enabled by utilizing the localized electric and magnetic Mie-type resonances of low-loss silicon nanoparticles tailored to behave as electromagnetically dual-symmetric scatterers. We apply this concept to realize a metadevice that converts a Gaussian beam into a vortex beam. The required spatial distribution of transmittance phases is achieved by a variation of the latticemore » spacing as a single geometric control parameter.« less

  9. Controllable nonlinear refraction characteristics in hydrogenated nanocrystalline silicon

    SciTech Connect

    Zheng, D. Q.; Ye, Q. H.; Shen, W. Z.; Su, W. A.

    2014-02-07

    Nonlinear refraction (NLR) of hydrogenated nanocrystalline silicon (nc-Si:H) has been investigated through the close aperture Z-scan method. We demonstrate a significant NLR and a unique feature of controllable NLR characteristics between saturable and Kerr NLR with the incident photon energy. We numerically evaluate the proportion of these two mechanisms in different wavelengths by a modified NLR equation. The band tail of nc-Si:H appears to play a crucial role in such NLR responses.

  10. Feedback loop compensates for rectifier nonlinearity

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Signal processing circuit with two negative feedback loops rectifies two sinusoidal signals which are 180 degrees out of phase and produces a single full-wave rectified output signal. Each feedback loop incorporates a feedback rectifier to compensate for the nonlinearity of the circuit.

  11. Controlled thinning and surface smoothening of silicon nanopillars.

    PubMed

    Kalem, S; Werner, P; Nilsson, B; Talalaev, V G; Hagberg, M; Arthursson, O; Södervall, U

    2009-11-01

    A convenient method has been developed to thin electron beam fabricated silicon nanopillars under controlled surface manipulation by transforming the surface of the pillars to an oxide shell layer followed by the growth of sacrificial ammonium silicon fluoride coating. The results show the formation of an oxide shell and a silicon core without significantly changing the original length and shape of the pillars. The oxide shell layer thickness can be controlled from a few nanometers up to a few hundred nanometers. While downsizing in diameter, smooth Si pillar surfaces of less than 10 nm roughness within 2 microm were produced after exposure to vapors of HF and HNO3 mixture as evidenced by transmission electron microscopy (TEM) analysis. The attempt to expose for long durations leads to the growth of a thick oxide whose strain effect on pillars can be assessed by coupled LO-TO vibrational modes of Si-O bonds. Photoluminescence (PL) of the pillar structures which have been downsized exhibits visible and infrared emissions, which are attributable to microscopic pillars and to the confinement of excited carriers in the Si core, respectively. The formation of smooth core-shell structures while reducing the diameter of the Si pillars has a potential in fabricating nanoscale electronic devices and functional components. PMID:19801781

  12. Nanostructured silicon membranes for control of molecular transport.

    PubMed

    Srijanto, Bernadeta R; Retterer, Scott T; Fowlkes, Jason D; Doktycz, Mitchel J

    2010-11-01

    A membrane that allows selective transport of molecular species requires precise engineering on the nanoscale. Membrane permeability can be tuned by controlling the physical structure and surface chemistry of the pores. Here, a combination of electron beam and optical lithography, along with cryogenic deep reactive ion etching, has been used to fabricate silicon membranes that are physically robust, have uniform pore sizes, and are directly integrated into a microfluidic network. Additional reductions in pore size were achieved using plasma enhanced chemical vapor deposition and atomic layer deposition of silicon dioxide to coat membrane surfaces. Cross sectioning of the membranes using focused ion beam milling was used to determine the physical shape of the membrane pores before and after coating. Functional characterization of the membranes was performed by using quantitative fluorescence microscopy to document the transport of molecular species across the membrane. PMID:24932436

  13. Realistic-contact-induced enhancement of rectifying in carbon-nanotube/graphene-nanoribbon junctions

    SciTech Connect

    Zhang, Xiang-Hua; Li, Xiao-Fei; Wang, Ling-Ling Xu, Liang; Luo, Kai-Wu

    2014-03-10

    Carbon-nanotube/graphene-nanoribbon junctions were recently fabricated by the controllable etching of single-walled carbon-nanotubes [Wei et al., Nat. Commun. 4, 1374 (2013)] and their electronic transport properties were studied here. First principles results reveal that the transmission function of the junctions show a heavy dependence on the shape of contacts, but rectifying is an inherent property which is insensitive to the details of contacts. Interestingly, the rectifying ratio is largely enhanced in the junction with a realistic contact and the enhancement is insensitive to the details of contact structures. The stability of rectifying suggests a significant feasibility to manufacture realistic all-carbon rectifiers in nanoelectronics.

  14. Single-switch 3{phi} PWM low harmonic rectifiers

    SciTech Connect

    Ismail, E.H.; Erickson, R.

    1996-03-01

    Existing 3{phi} ac-dc low-harmonic rectifiers are costly and require complex control schemes to minimize input current harmonics. Introduced here are two new classes of low cost 3{phi} ac-dc high power factor/low harmonic controlled rectifiers. These are derived from parent dc-dc converter topologies containing boost-type inputs and buck-type inputs. With a single active switch in addition to the diode bridge rectifier, the converters are capable of drawing a high-quality input current waveform naturally at nearly unit power factor. Thus, a simple 3{phi} ac-dc high power factor rectifier is obtained. Two algorithms are introduced in this paper for constructing a 3{phi} ac-dc high-quality rectifier. These algorithms depend on the simple switched-mode boost-type input converter and buck-type input converter modified by an input filter. For most known dc-dc converters which belong to these classes, there are corresponding 3{phi} ac-dc high power factor topologies, which use the same number of transistors and use six additional fast diodes. Analytical and simulation results are supplied to demonstrate the validity of the concept.

  15. Experimental investigation of radiative thermal rectifier using vanadium dioxide

    SciTech Connect

    Ito, Kota; Nishikawa, Kazutaka; Iizuka, Hideo; Toshiyoshi, Hiroshi

    2014-12-22

    Vanadium dioxide (VO{sub 2}) exhibits a phase-change behavior from the insulating state to the metallic state around 340 K. By using this effect, we experimentally demonstrate a radiative thermal rectifier in the far-field regime with a thin film VO{sub 2} deposited on the silicon wafer. A rectification contrast ratio as large as two is accurately obtained by utilizing a one-dimensional steady-state heat flux measurement system. We develop a theoretical model of the thermal rectifier with optical responses of the materials retrieved from the measured mid-infrared reflection spectra, which is cross-checked with experimentally measured heat flux. Furthermore, we tune the operating temperatures by doping the VO{sub 2} film with tungsten (W). These results open up prospects in the fields of thermal management and thermal information processing.

  16. Common rectifier diodes in temperature measurement applications below 50 K

    NASA Astrophysics Data System (ADS)

    Järvelä, J.; Stenvall, A.; Mikkonen, R.

    2010-06-01

    In this paper we studied the use of common electronic semiconductor diodes in temperature measurements at cryogenic atmosphere. The motivation for this is the high price of calibrated cryogenic temperature sensors since there are some applications, like quench detection, in which a cheaper and a less accurate sensor would suffice. We measured the forward voltage as a function of temperature, Vf(T), of several silicon rectifier diodes to determine the accuracy and interchangeability of the diodes. The experimental results confimed that Vf(T) of common rectifier diodes are similar to cryogenic sensor diodes, but the variability between two samples is much larger. The interchangeability of the diodes proved to be poor if absolute temperatures are to be measured. However for sensing changes in temperature they proved to be adequate and thus can be used to measure e.g. quench propagation or sense quench ignition at multiple locations with cheap price.

  17. Fast recovery, high voltage silicon diodes for AC motor controllers

    NASA Technical Reports Server (NTRS)

    Balodis, V.; Berman, A. H.; Gaugh, C.

    1982-01-01

    The fabrication and characterization of a high voltage, high current, fast recovery silicon diode for use in AC motor controllers, originally developed for NASA for use in avionics power supplies, is presented. The diode utilizes a positive bevel PIN mesa structure with glass passivation and has the following characteristics: peak inverse voltage - 1200 volts, forward voltage at 50 amperes - 1.5 volts, reverse recovery time of 200 nanoseconds. Characterization data for the diode, included in a table, show agreement with design concepts developed for power diodes. Circuit diagrams of the diode are also given.

  18. Characterization of Nanostructured Silicon Membranes for Control of Molecular Transport

    NASA Astrophysics Data System (ADS)

    Srijanto, Bernadeta; Retterer, Scott; Fowlkes, Jason; Doktycz, Mitchel

    2011-03-01

    Fabrication of nanoporous membranes for selective transport of molecular species requires precise engineering at the nanoscale. The membrane permeability can be tuned by controlling the physical structure and the surface chemistry of the pores. We use a combination of electron-beam and optical lithography, along with cryogenic deep reactive ion etching, to fabricate silicon membranes that are physically robust and have uniform pore sizes. Pore sizes are further reduced using plasma enhanced chemical vapor deposition and atomic layer deposition of silicon dioxide onto the membrane surfaces. Integrating nanoporous membranes within a microfluidic network provides a platform for tailoring molecular exchange between microchannels, independent of hydrodynamic effects. In enzymatic reactions, for example, tuning the pores size will allow smaller enzymatic substrates to traverse the membrane at controlled rates while larger enzymes remain spatially separated. Our results from membrane cross-sectioning using focused ion beam milling show that pore sizes can be controlled at dimensions below 10nm. Functional characterization was performed by quantitative fluorescence microscopy to observe the selective transport of molecular species of different sizes.

  19. Molecular rectifiers: a new design based on asymmetric anchoring moieties.

    PubMed

    Van Dyck, Colin; Ratner, Mark A

    2015-03-11

    The quest for a molecular rectifier is among the major challenges of molecular electronics. We introduce three simple rules to design an efficient rectifying molecule and demonstrate its functioning at the theoretical level, relying on the NEGF-DFT technique. The design rules notably require both the introduction of asymmetric anchoring moieties and a decoupling bridge. They lead to a new rectification mechanism based on the compression and control of the HOMO/LUMO gap by the electrode Fermi levels, arising from a pinning effect. Significant rectification ratios up to 2 orders of magnitude are theoretically predicted as the mechanism opposes resonant to nonresonant tunneling. PMID:25706442

  20. Control and data acquisition electronics for the CDF Silicon Vertex Detector

    SciTech Connect

    Turner, K.J.; Nelson, C.A.; Shaw, T.M.; Wesson, T.R.

    1991-11-01

    A control and data acquisition system has been designed for the CDF Silicon Vertex Detector (SVX) at Fermilab. The system controls the operation of the SVX Rev D integrated circuit (SVX IC) that is used to instrument a 46,000 microstrip silicon detector. The system consists of a Fastbus Sequencer, a Crate Controller and Digitizer modules. 11 refs., 6 figs., 3 tabs.

  1. Controlled skeletal progenitor cell migration on nanostructured porous silicon/silicon micropatterns

    NASA Astrophysics Data System (ADS)

    Torres-Costa, V.; Sánchez-Vaquero, V.; Muñoz-Noval, Á.; González-Méndez, L.; Punzón-Quijorna, E.; Gallach-Pérez, D.; Manso-Silván, M.; Martínez-Muñoz, G.; Climent-Font, A.; García-Ruiz, J. P.; Martín-Palma, R. J.

    2011-10-01

    In this work nanostructured porous silicon (nanoPS) was used for the fabrication of surface micropatterns aiming at controlling cell adhesion and migration. In particular, surface patterns of nanoPS and Si were engineered by high-energy ion-beam irradiation and subsequent anodization. It was found that human skeletal progenitor cells are sensitive to oneand two-dimensional patterns and that focal adhesion is inhibited on nanoPS areas. In spite of this anti-fouling characteristics, studies on patterns with reduced Si areas show that cells conform to nanoPS pathways favoring migration through cell protrusion, body translocation and tail retraction from two parallel Si traction rails. Moreover, migration can be blocked and cells tend to arrange when grid patterns with the appropriate dimensions are fabricated. The experimental results confirm that progenitor cells are able to exploit nanoPS anti-fouling designs by adapting to it for migration purposes.

  2. Electronic measurement and control of spin transport in silicon

    NASA Astrophysics Data System (ADS)

    Appelbaum, Ian; Huang, Biqin; Monsma, Douwe J.

    2007-05-01

    The spin lifetime and diffusion length of electrons are transport parameters that define the scale of coherence in spintronic devices and circuits. As these parameters are many orders of magnitude larger in semiconductors than in metals, semiconductors could be the most suitable for spintronics. So far, spin transport has only been measured in direct-bandgap semiconductors or in combination with magnetic semiconductors, excluding a wide range of non-magnetic semiconductors with indirect bandgaps. Most notable in this group is silicon, Si, which (in addition to its market entrenchment in electronics) has long been predicted a superior semiconductor for spintronics with enhanced lifetime and transport length due to low spin-orbit scattering and lattice inversion symmetry. Despite this promise, a demonstration of coherent spin transport in Si has remained elusive, because most experiments focused on magnetoresistive devices; these methods fail because of a fundamental impedance mismatch between ferromagnetic metal and semiconductor, and measurements are obscured by other magnetoelectronic effects. Here we demonstrate conduction-band spin transport across 10μm undoped Si in a device that operates by spin-dependent ballistic hot-electron filtering through ferromagnetic thin films for both spin injection and spin detection. As it is not based on magnetoresistance, the hot-electron spin injection and spin detection avoids impedance mismatch issues and prevents interference from parasitic effects. The clean collector current shows independent magnetic and electrical control of spin precession, and thus confirms spin coherent drift in the conduction band of silicon.

  3. Method for rapid, controllable growth and thickness, of epitaxial silicon films

    DOEpatents

    Wang, Qi; Stradins, Paul; Teplin, Charles; Branz, Howard M.

    2009-10-13

    A method of producing epitaxial silicon films on a c-Si wafer substrate using hot wire chemical vapor deposition by controlling the rate of silicon deposition in a temperature range that spans the transition from a monohydride to a hydrogen free silicon surface in a vacuum, to obtain phase-pure epitaxial silicon film of increased thickness is disclosed. The method includes placing a c-Si substrate in a HWCVD reactor chamber. The method also includes supplying a gas containing silicon at a sufficient rate into the reaction chamber to interact with the substrate to deposit a layer containing silicon thereon at a predefined growth rate to obtain phase-pure epitaxial silicon film of increased thickness.

  4. Recruitment of Gβγ controls the basal activity of G-protein coupled inwardly rectifying potassium (GIRK) channels: crucial role of distal C terminus of GIRK1

    PubMed Central

    Kahanovitch, Uri; Tsemakhovich, Vladimir; Berlin, Shai; Rubinstein, Moran; Styr, Boaz; Castel, Ruth; Peleg, Sagit; Tabak, Galit; Dessauer, Carmen W; Ivanina, Tatiana; Dascal, Nathan

    2014-01-01

    The G-protein coupled inwardly rectifying potassium (GIRK, or Kir3) channels are important mediators of inhibitory neurotransmission via activation of G-protein coupled receptors (GPCRs). GIRK channels are tetramers comprising combinations of subunits (GIRK1–4), activated by direct binding of the Gβγ subunit of Gi/o proteins. Heterologously expressed GIRK1/2 exhibit high, Gβγ-dependent basal currents (Ibasal) and a modest activation by GPCR or coexpressed Gβγ. Inversely, the GIRK2 homotetramers exhibit low Ibasal and strong activation by Gβγ. The high Ibasal of GIRK1 seems to be associated with its unique distal C terminus (G1-dCT), which is not present in the other subunits. We investigated the role of G1-dCT using electrophysiological and fluorescence assays in Xenopus laevis oocytes and protein interaction assays. We show that expression of GIRK1/2 increases the plasma membrane level of coexpressed Gβγ (a phenomenon we term ‘Gβγ recruitment’) but not of coexpressed Gαi3. All GIRK1-containing channels, but not GIRK2 homomers, recruited Gβγ to the plasma membrane. In biochemical assays, truncation of G1-dCT reduces the binding between the cytosolic parts of GIRK1 and Gβγ, but not Gαi3. Nevertheless, the truncation of G1-dCT does not impair activation by Gβγ. In fluorescently labelled homotetrameric GIRK1 channels and in the heterotetrameric GIRK1/2 channel, the truncation of G1-dCT abolishes Gβγ recruitment and decreases Ibasal. Thus, we conclude that G1-dCT carries an essential role in Gβγ recruitment by GIRK1 and, consequently, in determining its high basal activity. Our results indicate that G1-dCT is a crucial part of a Gβγ anchoring site of GIRK1-containing channels, spatially and functionally distinct from the site of channel activation by Gβγ. PMID:25384780

  5. Ordered silicon nanorod arrays with controllable geometry and robust hydrophobicity

    NASA Astrophysics Data System (ADS)

    Zi-Wen, Wang; Jia-Qi, Cai; Yi-Zhi, Wu; Hui-Jie, Wang; Xiao-Liang, Xu

    2015-01-01

    Highly ordered silicon nanorod (SiNR) arrays with controllable geometry are fabricated via nanosphere lithography and metal-assisted chemical etching. It is demonstrated that the key to achieving a high-quality metal mask is to construct a non-close-packed template that can be removed with negligible damage to the mask. Hydrophobicity of SiNR arrays of different geometries is also studied. It is shown that the nanorod structures are effectively quasi-hydrophobic with a contact angle as high as 142°, which would be useful in self-cleaning nanorod-based device applications. Project supported by the National Natural Science Foundation of China (Grant No. 51272246) and the Scientific and Technological Research Foundation of Anhui Province, China (Grant No. 12010202035).

  6. Controlled delivery of acyclovir from porous silicon micro- and nanoparticles

    NASA Astrophysics Data System (ADS)

    Maniya, Nalin H.; Patel, Sanjaykumar R.; Murthy, Z. V. P.

    2015-03-01

    In this work, micro- and nanoparticles of porous silicon (PSi) are demonstrated to act as effective carrier for the controlled delivery of acyclovir (ACV). PSi films prepared by electrochemical etching were fractured by ultrasonication to prepare micro- and nanoparticles. PSi native particles were thermally oxidized (TOPSi) and thermally hydrosilylated using undecylenic acid (UnPSi). PSi particles with three different surface chemistries were then loaded with ACV by physical adsorption and covalent attachment. Such particles were characterized by scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. In vitro ACV release experiments in phosphate buffered saline showed sustained release behaviour from both micro- and nanoparticles and order of release was found to be native PSi > TOPSi > UnPSi. Drug release kinetics study using Korsmeyer-Peppas model suggested a combination of both drug diffusion and Si scaffold erosion based drug release mechanisms.

  7. Silicon-on-insulator integrated tunable polarization controller (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sarmiento-Merenguel, Jose-Dario; Alonso-Ramos, Carlos; Halir, Robert; Le Roux, Xavier; Vivien, Laurent; Cheben, Pavel; Durán-Valdeiglesias, Elena; Molina-Fernández, Iñigo; Marris-Morini, Delphine; Xu, Danxia; Schmid, Jens H.; Janz, Siegfried; Ortega-Moñux, Alejandro

    2016-05-01

    Polarization management is a key functionality in many photonic applications, including optical communications, imaging or quantum information. Developing integrated devices capable of reliably controlling polarization state would result in compact and low cost circuits with improved stability compared with fiber or bulk optics solutions. However, stringent fabrication tolerances make the integration of polarization managing elements highly challenging. The main challenge in polarization controllers, composed by polarization rotators and polarization phase shifters, is to precisely control rotation angle in integrated polarization rotators. Proposed solutions typically require sophisticated fabrication processes or extremely tight fabrication tolerances, seriously hindering their practical application. Here we present a technology independent polarization controller scheme that relies on phase shifters to largely relax fabrication tolerances of polarization rotators. In addition, these phase shifters enable dynamic wavelength tuning. In our scheme, three polarization rotation elements are interconnected with two tunable phase shifters to adjust the polarization extinction ratio, while an output polarization phase shifter is used to select the relative phase. This way we can achieve any desired output state of polarization. We have implemented this scheme in the silicon-on-insulator platform, experimentally demonstrating a record polarization extinction range of 40 dB (± 20 dB) with a 98% coverage of the Poincaré sphere. Furthermore, the device is tunable in the complete C-band. These results constitute, to the best of our knowledge, the highest polarization extinction range achieved in a fully integrated device.

  8. Reliable 3-phase PWM boost rectifiers employing a stacked dual boost converter subtopology

    SciTech Connect

    Salmon, J.C.

    1996-05-01

    This paper describes circuit topologies for 3-phase pulse-width modulation (PWM) boost rectifiers that operate with a unity fundamental power factor and a low-distortion ac line current. Overlap delays between the switching of the upper and lower devices in a PWM rectifier leg are not critical and diodes eliminates the possibility of the dc-link capacitor discharging into short circuits and shoot-through fault conditions. The rectifiers are controlled using a stacked dual boost converter cell subtopology model that can be used in two current control modes. The dual current-control mode shapes two line currents and can achieve current distortion levels below 5%. The single current-control mode shapes one line current and can achieve current distortion levels close to 5% with the rectifier output dc voltage at the standard level associated with a rectified mains voltage. The per-unit current ratings for the switches in the 3-phase PWM switch networks are around 15--20% of the input rms line current as compared to 71% for a standard 3-phase PWM rectifier. Circuit simulations and experimental results are used to demonstrate the performance and feasibility of the rectifiers described.

  9. Control mechanisms for the oceanic distribution of silicon isotopes

    NASA Astrophysics Data System (ADS)

    Wischmeyer, André G.; de La Rocha, Christina L.; Maier-Reimer, Ernst; Wolf-Gladrow, Dieter A.

    2003-09-01

    Marine diatoms take up silicic acid for the buildup of their opaline shells and discriminate against the heavier silicon isotope. For the first time, the overall oceanic distribution of silicon isotopes has been estimated by integration of the Hamburg Model of the Ocean Carbon Cycle, version 4 (HAMOCC4). It is shown that the relationship between the silicic acid concentration and its silicon isotope composition is not a simple Rayleigh distillation curve. Only the Southern Ocean and the equatorial Pacific show a clear functional dependency similar to the Rayleigh distillation curve. Model results can be used to predict opal silicon isotope compositions in the sediment and constrain the use of silicon isotopes as a proxy for silicic acid utilization. Owing to the structure of the Pacific current system, it might be valid to apply a relationship between surface silicic acid concentrations and the silicon isotope signal in the equatorial Pacific sediments.

  10. Steric stabilization of nonaqueous silicon slips. I - Control of particle agglomeration and packing. II - Pressure casting of powder compacts

    NASA Technical Reports Server (NTRS)

    Kerkar, Awdhoot V.; Henderson, Robert J. M.; Feke, Donald L.

    1990-01-01

    The application of steric stabilization to control particle agglomeration and packing of silicon powder in benzene and trichloroethylene is reported. The results provide useful guidelines for controlling unfavorable particle-particle interactions during nonaqueous processing of silicon-based ceramic materials. The application of steric stabilization to the control and improvement of green processing of nonaqueous silicon slips in pressure consolidation is also demonstrated.

  11. Electric field control of donor pair diatomic molecules in silicon

    NASA Astrophysics Data System (ADS)

    Baena, Alejandra; Saraiva, Andre; Calderón, María J.; Koiller, Belita

    2015-03-01

    Single donors are well-established building blocks for engineering electronic properties of semiconductors, acting effectively as giant hydrogen atoms. Donor pairs, analogous to effective hydrogen molecules, were recently investigated in the strongly interacting regime in silicon. In this regime, electric field control renders timid results. Pairs that are more distant are more susceptible to external fields, and may harbour single electron charge control. Theoretically, the molecular quantum mechanics analogy between a donor pair and the H2 molecule in vacuum is not as straightforward as it may seem. A detailed understanding of the electronic structure of these molecular systems is a current challenge. We analyze the lowest energy states within effective mass theory, including central cell corrected donor potential effects and the conduction band multiplicity in Si. The spectrum of ionized donor pairs and its response to an external electric field will be presented. We contemplate possible advantages of heteropolar diatomic molecules, e.g, Sb -As pairs, as more efficient elements for such devices and applications.

  12. Microstructural control of silicon carbide via liquid phase sintering

    NASA Astrophysics Data System (ADS)

    Mrotek, Sharon Robinson

    Silicon carbide ceramics with various microstructures were fabricated by controlling the amount and composition of a Y2O3-Al 2O3 liquid phase, crystallographic phase of the starting powders, trace impurities in those powders, and time and temperature of sintering and post- sintering heat-treatments. Alpha and beta SiC "seeds" were used to control grain growth during sintering. The grain size distribution and aspect ratio of the grains were determined through microstructural analysis of polished and etched samples. TEM was used in conjunction with EDS to determine the distribution of the sintering aids in the grains and the grain boundaries. Additionally, the final phase content of the samples was determined via x-ray diffraction. The fracture toughness and hardness were measured to evaluate the relative effects of the microstructural variations on the mechanical properties. Alpha silicon carbide samples exhibited a fine grained, equiaxed microstructure. Under appropriate conditions, samples prepared from beta-SiC powders underwent a phase transformation to alpha-SiC accompanied by the growth of elongated platelet grains. The addition of alpha seeds to the beta powder reduced the size of the platelets compared to unseeded samples of the same composition. If the beta to alpha phase transformation did not occur, the beta samples developed an equiaxed microstructure. The grain size of all samples decreased with increasing amounts of sintering additives. The beta to alpha phase transformation, required to obtain an elongated grain microstructure, was catalyzed by the presence of sufficient amounts of aluminum. If insufficient Al impurity was present in the powder, purposeful additions of Al metal could induce the phase transformation. Examination of the sintering progression over time indicated that the phase transformation occurred late in the sintering process and appeared to occur via a solution/reprecipitation mechanism. Post-sintering heat treatments were also used

  13. High current JBS rectifiers and their impact on switching power supplies

    NASA Astrophysics Data System (ADS)

    Baliga, B. J.; Chang, H.-R.; Steigerwald, R. L.

    The junction barrier controlled Schottky (JBS) rectifier is a Schottky rectifier with a p-n junction grid structure integrated into the device structure to improve its reverse blocking characteristics. This paper reports the development of large area (0.5 sq cm), 30 V, JBS rectifiers capable of handling over 25 A of forward current while operating at up to 125 C with good reverse blocking characteristics. Trade-off curves between forward voltage drop and reverse leakage current are introduced to allow optimization of these devices. Evaluation of their impact on low voltage switching power supplies is presented.

  14. Control of carbon balance in a silicon smelting furnace

    DOEpatents

    Dosaj, V.D.; Haines, C.M.; May, J.B.; Oleson, J.D.

    1992-12-29

    The present invention is a process for the carbothermic reduction of silicon dioxide to form elemental silicon. Carbon balance of the process is assessed by measuring the amount of carbon monoxide evolved in offgas exiting the furnace. A ratio of the amount of carbon monoxide evolved and the amount of silicon dioxide added to the furnace is determined. Based on this ratio, the carbon balance of the furnace can be determined and carbon feed can be adjusted to maintain the furnace in carbon balance.

  15. ISGV Self-rectifying Turbine Design For Thermoacoustic Application

    NASA Astrophysics Data System (ADS)

    Sammak, Shervin; Asghary, Maryam; Ghorbanian, Kaveh

    2014-11-01

    Thermoacoustic engines produce the acoustic power from wasted heat and then electricity can be generated from acoustic power. Utilizing self-rectifying turbine after a thermoacoustic engine allows for deploying standard generators with high enough rotational speed that remarkably reduce abrasion, size and cost and significantly increase efficiency and controllability in comparison with linear alternators. In this paper, by evaluating all different type of self-rectifying turbine, impulse turbine with self-piched controlled (ISGV) is chosen as the most appropriate type for this application. This kind of turbine is designed in detail for a popular engine, thermoacoustic stirling heat engine (TASHE). In order to validate the design, a full scale size of designed turbine is modeled in ANSYS CFX. As a result, optimum power and efficiency gained based on numerical data.

  16. Electron beam quality control using an amorphous silicon EPID

    SciTech Connect

    Beck, J. A.; Budgell, G. J.; Roberts, D. A.; Evans, P. M.

    2009-05-15

    An amorphous silicon EPID has been investigated to determine whether it is capable of quality control constancy measurements for linear accelerator electron beams. The EPID grayscale response was found to be extremely linear with dose over a wide dose range and, more specifically, for exposures of 95-100 MU. Small discrepancies of up to 0.8% in linearity were found at 6 MeV (8-15 MeV showed better agreement). The shape of the beam profile was found to be significantly altered by scatter in air over the approximately 60 cm gap between the end of the applicator and the EPID. Nevertheless, relative changes in EPID-measured profile flatness and symmetry were linearly related to changes in these parameters at 95 cm focus to surface distance (FSD) measured using a 2D diode array. Similar results were obtained at 90 deg. and 270 deg. gantry angles. Six months of daily images were acquired and analyzed to determine whether the device is suitable as a constancy checker. EPID output measurements agreed well with daily ion chamber measurements, with a 0.8% standard deviation in the difference between the two measurement sets. When compared to weekly parallel plate chamber measurements, this figure dropped to 0.5%. A Monte Carlo (MC) model of the EPID was created and demonstrated excellent agreement between MC-calculated profiles in water and the EPID at 95 and 157 cm FSD. Good agreement was also found with measured EPID profiles, demonstrating that the EPID provides an accurate measurement of electron profiles. The EPID was thus shown to be an effective method for performing electron beam daily constancy checks.

  17. Chemical control of physical properties in silicon nitride films

    NASA Astrophysics Data System (ADS)

    Xu, Xiangdong; Zhou, Dong; He, Qiong; Jiang, Yadong; Fan, Taijun; Huang, Long; Ao, Tianhong; He, Shaowei

    2013-06-01

    Amorphous hydrogenated silicon nitride ( a-SiN x H y ) films were prepared by plasma-enhanced chemical vapor deposition (PECVD). The physical properties and chemical structures of the resulting materials were systematically investigated. Results reveal that the a-SiN x H y films similarly consist of four kinds of Si-N groups, including Si3N4, H-Si-N3, H2-Si-N2, and Si3-Si-N. Deposition at 13.56 MHz and 300 ∘C with flow ratio of SiH4/NH3=30/30 sccm leads to the yield of Si0.39N0.38H0.23 films that exhibit excellent properties of high uniformity, high elastic modulus, moderate refractive index and optical band gap, low UV absorption, and ultralow residual stress (-0.17 MPa). Such Si0.39N0.38H0.23 films hold considerable promise for applications in solar cells and infrared sensors. In contrast, an increase of Si or N content in a-SiN x H y films will cause the degradation of the properties, so that the films are unsuitable for solar cells. Moreover, a new conception of network degree was proposed to evaluate and explain the properties of a-SiN x H y films. Particularly, this work discloses the relationships between the chemical structures and physical properties, and suggests a basic approach to the yield of a-SiN x H y films with controlled physical properties.

  18. Sized controlled synthesis, purification, and cell studies with silicon quantum dots.

    PubMed

    Shiohara, Amane; Prabakar, Sujay; Faramus, Angelique; Hsu, Chia-Yen; Lai, Ping-Shan; Northcote, Peter T; Tilley, Richard D

    2011-08-01

    This article describes the size control synthesis of silicon quantum dots with simple microemulsion techniques. The silicon nanocrystals are small enough to be in the strong confinement regime and photoluminesce in the blue region of the visible spectrum and the emission can be tuned by changing the nanocrystal size. The silicon quantum dots were capped with allylamine either a platinum catalyst or UV-radiation. An extensive purification protocol is reported and assessed using (1)H NMR to produce ultra pure silicon quantum dots suitable for biological studies. The highly pure quantum dots were used in cellular uptake experiments and monitored using confocal microscopy. The results showed that the amine terminated silicon nanocrystals accumulated in lysosome but not in nuclei and could be used as bio-markers to monitor cancer cells over long timescales. PMID:21727983

  19. Sized controlled synthesis, purification, and cell studies with silicon quantum dots

    NASA Astrophysics Data System (ADS)

    Shiohara, Amane; Prabakar, Sujay; Faramus, Angelique; Hsu, Chia-Yen; Lai, Ping-Shan; Northcote, Peter T.; Tilley, Richard D.

    2011-08-01

    This article describes the size control synthesis of silicon quantum dots with simple microemulsion techniques. The silicon nanocrystals are small enough to be in the strong confinement regime and photoluminesce in the blue region of the visible spectrum and the emission can be tuned by changing the nanocrystal size. The silicon quantum dots were capped with allylamine either a platinum catalyst or UV-radiation. An extensive purification protocol is reported and assessed using 1H NMR to produce ultra pure silicon quantum dots suitable for biological studies. The highly pure quantum dots were used in cellular uptake experiments and monitored using confocal microscopy. The results showed that the amine terminated silicon nanocrystals accumulated in lysosome but not in nuclei and could be used as bio-markers to monitor cancer cells over long timescales.This article describes the size control synthesis of silicon quantum dots with simple microemulsion techniques. The silicon nanocrystals are small enough to be in the strong confinement regime and photoluminesce in the blue region of the visible spectrum and the emission can be tuned by changing the nanocrystal size. The silicon quantum dots were capped with allylamine either a platinum catalyst or UV-radiation. An extensive purification protocol is reported and assessed using 1H NMR to produce ultra pure silicon quantum dots suitable for biological studies. The highly pure quantum dots were used in cellular uptake experiments and monitored using confocal microscopy. The results showed that the amine terminated silicon nanocrystals accumulated in lysosome but not in nuclei and could be used as bio-markers to monitor cancer cells over long timescales. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10458f

  20. Controls on silicon cycling in Southeast Asian rice production systems

    NASA Astrophysics Data System (ADS)

    Klotzbücher, Thimo; Marxen, Anika; Vetterlein, Doris; Jahn, Reinhold

    2013-04-01

    Recent research suggests that silicon (Si) is beneficial for rice plants, i.e., a sufficient Si supply improves their resistance against pests and pathogens and increases the uptake of essential nutrients. Despite its potential importance for rice yields, cycling of Si in rice production systems is poorly studied. We assess plant-available Si (Sipa; determined using acetate extraction) in topsoils (Ap+Arp horizons) and Si uptake by plants at 70 paddy fields managed by local farmers in contrasting regions of Vietnam and the Philippines. First results show that Sipa contents are considerably larger in Philippine (217 ± 100 mg Sipa kg-1 ) than in Vietnamese (32 ± 19 mg Sipa kg-1) paddy soils. Rice straw from the Philippines contains 8.6 ± 0.9 % Si, straw from Vietnam 5.0 ± 1.2 % Si. Laboratory experiments showed that Si is limiting the growth of rice plants in some of the Vietnamese soils. We assume that differences in geo-/ pedologic conditions between Vietnam and the Philippines explain the data. Large Sipa contents in the Philippine soils are due to recent rock formation by active volcanism, hence, by a large Sipa input due to mineral weathering in recent geologic history. In contrast, parent materials of the Vietnamese paddy soils derive from old and highly weathered land surfaces. Hence, our data suggest that geo-/pedologic conditions are the main control for the availability of Si in paddy soils. Currently, we examine the relevance of agricultural practices for small-scale differences in the availability of Si within regions. Inadequate practices, such as removal of rice straw from the fields, might deplete Sipa in paddy soils causing a decrease in rice yields in some regions of Vietnam. We investigate the role of phytoliths (amorphous Si bodies contained in rice straw) as source of Sipa in paddy soils. Our methods include laboratory experiments and the assessment of turnover times of phytoliths in paddy soils; first results will be presented and discussed

  1. Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor

    NASA Technical Reports Server (NTRS)

    Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

    2001-01-01

    A process for producing polycrystalline silicon carbide by heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

  2. Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor

    NASA Technical Reports Server (NTRS)

    Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

    2000-01-01

    A process for producing polycrystalline silicon carbide includes heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

  3. Size control of erbium-doped silicon nanocrystals

    NASA Astrophysics Data System (ADS)

    John, John St.; Coffer, Jeffery L.; Chen, Yandong; Pinizzotto, Russell F.

    2000-09-01

    This work describes the effects of pyrolysis oven length and erbium precursor on the preparation of discrete erbium-doped silicon nanoparticles. These doped nanoparticles were prepared by the co-pyrolysis of disilane and the volatile complex Er(tmhd)3 (tmhd=2,2,6,6-tetramethyl-3,5-heptanedionato). The particle sizes and size distributions were determined using high resolution and conventional transmission electron microscopy. Erbium-doped silicon nanoparticles exhibit a selected area electron diffraction pattern consistent with the diamond cubic phase and a distinctive dark contrast in the transmission electron microscope. The presence of erbium is confirmed by x-ray energy dispersive spectroscopy. In general, the mean diameter of the individual nanoparticles increases as the length of the pyrolysis oven used during their preparation is increased.

  4. Analysis of parametric transformer with rectifier load

    SciTech Connect

    Ichinokura, O.; Jinzenji, T. ); Tajima, K. )

    1993-03-01

    This paper describes a push-pull parametric transformer constructed using a pair of orthogonal-cores. The operating characteristics of the parametric transformer with a rectifier load were analyzed based on SPICE simulations. The analysis results show good agreement with experiment. It was found that the input surge current of the full-wave rectifier circuit with a smoothing capacitor can be compensated by the parametric transformer. Use of the parametric transformer as a power stabilizer is anticipated owing to its various functions such as for voltage regulation and overload protection.

  5. Pharmacological Conversion of a Cardiac Inward Rectifier into an Outward Rectifier Potassium Channel.

    PubMed

    Moreno-Galindo, Eloy G; Sanchez-Chapula, Jose A; Tristani-Firouzi, Martin; Navarro-Polanco, Ricardo A

    2016-09-01

    Potassium (K(+)) channels are crucial for determining the shape, duration, and frequency of action-potential firing in excitable cells. Broadly speaking, K(+) channels can be classified based on whether their macroscopic current outwardly or inwardly rectifies, whereby rectification refers to a change in conductance with voltage. Outwardly rectifying K(+) channels conduct greater current at depolarized membrane potentials, whereas inward rectifier channels conduct greater current at hyperpolarized membrane potentials. Under most circumstances, outward currents through inwardly rectifying K(+) channels are reduced at more depolarized potentials. However, the acetylcholine-gated K(+) channel (KACh) conducts current that inwardly rectifies when activated by some ligands (such as acetylcholine), and yet conducts current that outwardly rectifies when activated by other ligands (for example, pilocarpine and choline). The perplexing and paradoxical behavior of KACh channels is due to the intrinsic voltage sensitivity of the receptor that activates KACh channels, the M2 muscarinic receptor (M2R). Emerging evidence reveals that the affinity of M2R for distinct ligands varies in a voltage-dependent and ligand-specific manner. These intrinsic receptor properties determine whether current conducted by KACh channels inwardly or outwardly rectifies. This review summarizes the most recent concepts regarding the intrinsic voltage sensitivity of muscarinic receptors and the consequences of this intriguing behavior on cardiac physiology and pharmacology of KACh channels. PMID:27247338

  6. Novel plasma control method in PECVD for preparing microcrystalline silicon

    SciTech Connect

    Nishimiya, T.; Kondo, M.; Matsuda, A.

    1997-07-01

    A novel plasma enhanced vapor deposition (PECVD) technique employing biased wall (BW) method has been developed for the enhanced growth rate of the hydrogenated microcrystalline silicon ({micro}c-Si:H) films. Using this method, the authors have achieved a growth rate of more than 6{angstrom}/sec for the formation of {micro}c-Si:H having an average grain size of 200{angstrom} at 350 C.

  7. PWM rectifier with low dc voltage ripple for magnet supply

    SciTech Connect

    Ciscato, D. ); Malesani, L.; Rosetto, L.; Tenti, P. ); Basile, G.L.; Pasti, M. ); Voelker, F. )

    1992-04-01

    PWM bridge rectifiers with GTO switches are considered for application to particle accelerator magnet power supplies, where two-quadrant operation and extremely low dc current ripple are required. Different control strategies, with both preprogrammed and variable switching patterns, are examined and compared in view of optimization of the system performance. In particular, optimum digital PWM, multilevel delta modulation, and hybrid PWM/delta techniques are analyzed. In this paper the validity of the control methods is verified by simulation and experimental tests on a 60-kW prototype.

  8. Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer

    DOEpatents

    Carlson, David E.

    1980-01-01

    Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

  9. RF sputtering for controlling dihydride and monohydride bond densities in amorphous silicon hydride

    DOEpatents

    Jeffery, F.R.; Shanks, H.R.

    1980-08-26

    A process is described for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicone produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous solicone hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

  10. Controlling the dopant dose in silicon by mixed-monolayer doping.

    PubMed

    Ye, Liang; Pujari, Sidharam P; Zuilhof, Han; Kudernac, Tibor; de Jong, Michel P; van der Wiel, Wilfred G; Huskens, Jurriaan

    2015-02-11

    Molecular monolayer doping (MLD) presents an alternative to achieve doping of silicon in a nondestructive way and holds potential for realizing ultrashallow junctions and doping of nonplanar surfaces. Here, we report the mixing of dopant-containing alkenes with alkenes that lack this functionality at various ratios to control the dopant concentration in the resulting monolayer and concomitantly the dopant dose in the silicon substrate. The mixed monolayers were grafted onto hydrogen-terminated silicon using well-established hydrosilylation chemistry. Contact angle measurements, X-ray photon spectroscopy (XPS) on the boron-containing monolayers, and Auger electron spectroscopy on the phosphorus-containing monolayers show clear trends as a function of the dopant-containing alkene concentration. Dynamic secondary-ion mass spectroscopy (D-SIMS) and Van der Pauw resistance measurements on the in-diffused samples show an effective tuning of the doping concentration in silicon. PMID:25607722

  11. Thermal system design and modeling of meniscus controlled silicon growth process for solar applications

    NASA Astrophysics Data System (ADS)

    Wang, Chenlei

    The direct conversion of solar radiation to electricity by photovoltaics has a number of significant advantages as an electricity generator. That is, solar photovoltaic conversion systems tap an inexhaustible resource which is free of charge and available anywhere in the world. Roofing tile photovoltaic generation, for example, saves excess thermal heat and preserves the local heat balance. This means that a considerable reduction of thermal pollution in densely populated city areas can be attained. A semiconductor can only convert photons with the energy of the band gap with good efficiency. It is known that silicon is not at the maximum efficiency but relatively close to it. There are several main parts for the photovoltaic materials, which include, single- and poly-crystalline silicon, ribbon silicon, crystalline thin-film silicon, amorphous silicon, copper indium diselenide and related compounds, cadmium telluride, et al. In this dissertation, we focus on melt growth of the single- and poly-crystalline silicon manufactured by Czochralski (Cz) crystal growth process, and ribbon silicon produced by the edge-defined film-fed growth (EFG) process. These two methods are the most commonly used techniques for growing photovoltaic semiconductors. For each crystal growth process, we introduce the growth mechanism, growth system design, general application, and progress in the numerical simulation. Simulation results are shown for both Czochralski and EFG systems including temperature distribution of the growth system, velocity field inside the silicon melt and electromagnetic field for the EFG growth system. Magnetic field is applied on Cz system to reduce the melt convection inside crucible and this has been simulated in our numerical model. Parametric studies are performed through numerical and analytical models to investigate the relationship between heater power levels and solidification interface movement and shape. An inverse problem control scheme is developed to

  12. Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens

    SciTech Connect

    Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

    2012-11-06

    Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test

  13. Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens

    NASA Astrophysics Data System (ADS)

    Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

    2012-11-01

    Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test

  14. An evaluation system for experimental silicon and silicon carbide super gate turn off thyristors.

    PubMed

    Bayne, Stephen; Lacouture, Shelby; Lawson, Kevin; Giesselmann, Michael; Scozzie, Charles J; O'Brien, Heather; Ogunniyi, Aderinto A

    2014-07-01

    This paper describes the design and implementation of a small-scale pulsed power system specifically intended to evaluate the suitability of experimental silicon and silicon carbide high power Super Gate Turn Off thyristors for high action (500 A(2) s and above) pulsed power applications where energy is extracted from a storage element in a rapid and controlled manner. To this end, six of each type of device was placed in a controlled three phase rectifier circuit which was in turn connected to an aircraft ground power motor-generator set and subjected to testing protocols with varying power levels, while parameters such as offset firing angle were varied. PMID:25085173

  15. 46 CFR 129.360 - Semiconductor-rectifier systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS ELECTRICAL INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have...

  16. 46 CFR 120.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 120.360 Section...

  17. 46 CFR 129.360 - Semiconductor-rectifier systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a... 46 Shipping 4 2014-10-01 2014-10-01 false Semiconductor-rectifier systems. 129.360 Section...

  18. 46 CFR 129.360 - Semiconductor-rectifier systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a... 46 Shipping 4 2011-10-01 2011-10-01 false Semiconductor-rectifier systems. 129.360 Section...

  19. 46 CFR 120.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a... 46 Shipping 4 2011-10-01 2011-10-01 false Semiconductor rectifier systems. 120.360 Section...

  20. 46 CFR 129.360 - Semiconductor-rectifier systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor-rectifier systems. 129.360 Section...

  1. 46 CFR 129.360 - Semiconductor-rectifier systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a... 46 Shipping 4 2012-10-01 2012-10-01 false Semiconductor-rectifier systems. 129.360 Section...

  2. 46 CFR 120.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a... 46 Shipping 4 2012-10-01 2012-10-01 false Semiconductor rectifier systems. 120.360 Section...

  3. 46 CFR 120.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a... 46 Shipping 4 2014-10-01 2014-10-01 false Semiconductor rectifier systems. 120.360 Section...

  4. Etching anisotropy mechanisms lead to morphology-controlled silicon nanoporous structures by metal assisted chemical etching.

    PubMed

    Jiang, Bing; Li, Meicheng; Liang, Yu; Bai, Yang; Song, Dandan; Li, Yingfeng; Luo, Jian

    2016-02-01

    The etching anisotropy induced by the morphology and rotation of silver particles controls the morphology of silicon nanoporous structures, through various underlying complex etching mechanisms. The level of etching anisotropy can be modulated by controlling the morphology of the silver catalyst to obtain silicon nanoporous structures with straight pores, cone-shaped pores and pyramid-shaped pores. In addition, the structures with helical pores are obtained by taking advantage of the special anisotropic etching, which is induced by the rotation and revolution of silver particles during the etching process. An investigation of the etching anisotropy during metal assisted chemical etching will promote a deep understanding of the chemical etching mechanism of silicon, and provide a feasible approach to fabricate Si nanoporous structures with special morphologies. PMID:26785718

  5. D0 Silicon Upgrade: Control Dewar Valve Calculations

    SciTech Connect

    Rucinski, Russ; /Fermilab

    1995-10-20

    This engineering note documents the calculations that were done to support the valve size selection for the magnet flow control valve, EVMF in the solenoid control dewar. The size selected was a control valve with a Cv = 0.32.

  6. Control carrier recombination of multi-scale textured black silicon surface for high performance solar cells

    NASA Astrophysics Data System (ADS)

    Hong, M.; Yuan, G. D.; Peng, Y.; Chen, H. Y.; Zhang, Y.; Liu, Z. Q.; Wang, J. X.; Cai, B.; Zhu, Y. M.; Chen, Y.; Liu, J. H.; Li, J. M.

    2014-06-01

    We report an enhanced performance of multi-scale textured black silicon solar cell with power conversion efficiency of 15.5% by using anisotropic tetramethylammonium hydroxide etching to control the recombination. The multi-scale texture can effectively reduce the surface reflectance in a wide wavelength range, and both the surface and Auger recombination can be effectively suppressed by etching the samples after the n++ emitter formed. Our result shows that the reformed solar cell has higher conversion efficiency than that of conventional pyramid textured cell (15.3%). This work presents an effective method for improving the performance of nanostructured silicon solar cells.

  7. Optimal locomotion of mechanical rectifier systems

    NASA Astrophysics Data System (ADS)

    Blair, Justin T.

    Vehicles utilizing animal locomotion mechanisms may possess increased performance parameters and the ability to overcome more difficult terrain than conventional wheel or propeller driven vehicles. The essential mechanism underlying animal locomotion can be viewed as mechanical rectification that converts periodic body movements to thrust force through interactions with the environment. This dissertation defines a general class of mechanical rectifiers as multi-body systems equipped with such thrust generation mechanisms. A general model is developed from the Euler-Lagrange equation and simplified by assuming small body oscillations around a given nominal posture. The model reveals that the rectifying dynamics can be captured by a bilinear (but not linear) term of body shape variables. An optimal gait problem is formulated for the bilinear rectifier model as a minimization of a quadratic cost function over the set of periodic functions subject to a constraint on the average locomotion velocity. We prove that a globally optimal solution is given by a harmonic gait that can be found by generalized eigenvalue computation with a line search over cycle frequencies. We verify the solution method through case studies of a two dimensional chain of links for which snake-like undulations and jellyfish-like flapping gaits are found to be optimal, and obtain analytical insights into determinants of optimal gaits from a simple disk-mass rectifier system. Lastly, we develop a dynamic model for batoid swimming featuring a 6 degree-of-freedom main body (position and orientation), with independent wing deformation (described as the motion of many discrete points in the body-fixed coordinate frame), and calculate various gaits. Multiple wing shapes and optimality criteria are considered, such as the maximum thrust to deflection ratio or minimum input power, and the resulting gaits are compared.

  8. Multi-crystalline silicon solidification under controlled forced convection

    NASA Astrophysics Data System (ADS)

    Cablea, M.; Zaidat, K.; Gagnoud, A.; Nouri, A.; Chichignoud, G.; Delannoy, Y.

    2015-05-01

    Multi-crystalline silicon wafers have a lower production cost compared to mono-crystalline wafers. This comes at the price of reduced quality in terms of electrical properties and as a result the solar cells made from such materials have a reduced efficiency. The presence of different impurities in the bulk material plays an important role during the solidification process. The impurities are related to different defects (dislocations, grain boundaries) encountered in multi-crystalline wafers. Applying an alternative magnetic field during the solidification process has various benefits. Impurities concentration in the final ingot could be reduced, especially metallic species, due to a convective term added in the liquid that reduces the concentration of impurities in the solute boundary layer. Another aspect is the solidification interface shape that is influenced by the electromagnetic stirring. A vertical Bridgman type furnace was used in order to study the solidification process of Si under the influence of a travelling magnetic field able to induce a convective flow in the liquid. The furnace was equipped with a Bitter type three-phase electromagnet that provides the required magnetic field. A numerical model of the furnace was developed in ANSYS Fluent commercial software. This paper presents experimental and numerical results of this approach, where interface markings were performed.

  9. Controlling leakage losses in subwavelength grating silicon metamaterial waveguides.

    PubMed

    Sarmiento-Merenguel, J Darío; Ortega-Moñux, Alejandro; Fédéli, Jean-Marc; Wangüemert-Pérez, J Gonzalo; Alonso-Ramos, Carlos; Durán-Valdeiglesias, Elena; Cheben, Pavel; Molina-Fernández, Íñigo; Halir, Robert

    2016-08-01

    Subwavelength gratings (SWG) are photonic structures with a period small enough to suppress diffraction, thereby acting as artificial dielectric materials, also called all-dielectric metamaterials. This property has been exploited in many high-performance photonic integrated devices in the silicon-on-insulator (SOI) platform. While SWG waveguides are theoretically lossless, they may exhibit leakage penalty to the substrate due to a combination of reduced modal confinement and finite thickness of the buried oxide (BOX) layer. In this Letter, for the first time, to the best of our knowledge, we analyze substrate leakage losses in SWG waveguides. We establish a direct relation between the effective index of the waveguide mode and the leakage losses which, remarkably, is independent of the geometric parameters of the SWG waveguide. This universal relation is demonstrated both numerically and experimentally, and it provides practical design guidelines to mitigate leakage losses. For BOX thicknesses of 2 and 3 μm, we find negligible leakage losses when the mode effective index is higher than 1.65 and 1.55, respectively. PMID:27472589

  10. Coherent control of single spins in silicon carbide at room temperature.

    PubMed

    Widmann, Matthias; Lee, Sang-Yun; Rendler, Torsten; Son, Nguyen Tien; Fedder, Helmut; Paik, Seoyoung; Yang, Li-Ping; Zhao, Nan; Yang, Sen; Booker, Ian; Denisenko, Andrej; Jamali, Mohammad; Momenzadeh, S Ali; Gerhardt, Ilja; Ohshima, Takeshi; Gali, Adam; Janzén, Erik; Wrachtrup, Jörg

    2015-02-01

    Spins in solids are cornerstone elements of quantum spintronics. Leading contenders such as defects in diamond or individual phosphorus dopants in silicon have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems: it has a large bandgap with deep defects and benefits from mature fabrication techniques. Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology. PMID:25437256

  11. Control of back surface reflectance from aluminum alloyed contacts on silicon solar cells

    SciTech Connect

    Cudzinovic, M.; Sopori, B.

    1996-05-01

    A process for forming highly reflective aluminum back contacts with low contact resistance to silicon solar cells is described. By controlling the process conditions, it is possible to vary the silicon/aluminum interface from a specular to a diffuse reflector while maintaining a high interface reflectance. The specular interface is found to be a uniform silicon/aluminum alloy layer a few angstroms thick that has epitaxially regrown on the silicon. The diffuse interface consists of randomly distributed (111) pyramids produced by crystallographic out-diffusion of the bulk silicon. The light trapping ability of the diffuse contact is found to be close to the theoretical limit. Both types of contacts are found to have specific contact resistivities of 10{sup {minus}5} {Omega}-cm{sup 2}. The process for forming the contacts involves illuminating the devices with tungsten halogen lamps. The process is rapid (under 100 s) and low temperature (peak temperature < 580{degrees}C), making it favorable for commercial solar cell fabrication.

  12. Balanced ternary addition using a gated silicon nanowire

    NASA Astrophysics Data System (ADS)

    Mol, J. A.; van der Heijden, J.; Verduijn, J.; Klein, M.; Remacle, F.; Rogge, S.

    2011-12-01

    Ternary logic has the lowest cost of complexity, here, we demonstrate a CMOS hardware implementation of a ternary adder using a silicon metal-on-insulator single electron transistor. Gate dependent rectifying behavior of a single electron transistor (SET) results in a robust three-valued output as a function of the potential of the single electron transistor island. Mapping logical, ternary inputs to the three gates controlling the potential of the single electron transistor island allows us to perform complex, inherently ternary operations, on a single transistor.

  13. Three phase six-switch PWM buck rectifier with power factor improvement

    NASA Astrophysics Data System (ADS)

    Zafarullah Khan, M.; Mohsin Naveed, M.; Akbar Hussain, D. M.

    2013-06-01

    Conventional Phase Controlled Rectifier injects low order current harmonics into the AC mains. Large size filtering components are required to attenuate these harmonics. In this paper, three phase six-switch PWM buck rectifier is presented which operates at nearly unity power factor and provides variable output voltage. Small size energy storing components are required depending upon switching frequency. MATLAB simulation is performed and modified Sinusoidal Pulse Width Modulation (SPWM) switching technique is used in 3kW prototype converter to demonstrate low input current THD, nearly unity displacement factor, well regulated output voltage and reduced switching losses compared to conventional SPWM.

  14. Controlled Fluxes of Silicon Nanoparticles By Extraction from a Pulsed RF Plasma

    NASA Astrophysics Data System (ADS)

    Girshick, Steven; Larriba-Andaluz, Carlos

    2015-09-01

    Deposition of silicon nanoparticles onto substrates may be a means of growing monocrystalline silicon films at low substrate temperature if the nanoparticles' impact energy and size can be controlled to provide melting or amorphization of the nanoparticle without damaging the underlying film. In order to explore conditions that could produce such controlled fluxes of nanoparticles we numerically model a pulsed RF argon-silane plasma, with a positive DC bias applied during the afterglow phase of each pulse so as to extract and accelerate negatively charged silicon particles. Operating parameters studied include pulse on time, pulse off time, DC bias voltage, RF voltage and pressure. This set of parameters is tested to find conditions under which one can achieve a periodic steady state with repeatable pulse-to-pulse conditions that maximize silicon film growth rates while maintaining nanoparticle impact energies in the range 0.5-2.0 eV/atom. We utilize a previously developed 1-D dusty plasma numerical model, modified to consider pulsing and applied substrate bias. This model self-consistently solves for the coupled behavior of plasma, chemistry, and aerosol. Results show that it is possible by this method to produce nanoparticle fluxes that are tailored with respect to their distribution of impact energies and mass deposition rates. Partially supported by US Dept. of Energy Office of Fusion Energy Science (DE-SC0001939), US National Science Foundation (CHE-124752), and Minnesota Supercomputing Institute.

  15. Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz

    NASA Technical Reports Server (NTRS)

    Wong, Alden; Larocca, Tim; Chang, M. Frank; Samoska, Lorene A.

    2011-01-01

    A group at UCLA, in collaboration with the Jet Propulsion Laboratory, has designed a voltage-controlled oscillator (VCO) created specifically for a compact, integrated, electronically tunable frequency generator useable for submillimeter- wave science instruments operating in extreme cold environments.

  16. Development of high temperature gallium phosphide rectifiers

    NASA Technical Reports Server (NTRS)

    Craford, M. G.; Keune, D. L.

    1972-01-01

    Large area high performance, GaP rectifiers were fabricated by means of Zn diffusion into vapor phase epitaxial GaP. Devices with an active area of 0.01 sq cm typically exhibit forward voltages of 3 volts for a bias current of 1 ampere and have reverse breakdown voltages of 300 volts for temperatures from 27 C to 400 C. Typical device reverse saturation current at a reverse bias of 150 volts is less than 10 to the minus 9th power amp at 27 C and less than 0.000050 amp at 400 C.

  17. Polyamine Block of Inwardly Rectifying Potassium Channels

    PubMed Central

    Kurata, Harley T.; Cheng, Wayland W.L.; Nichols, Colin G.

    2011-01-01

    Polyamine blockade of inwardly rectifying potassium (Kir) channels underlies their steep voltage-dependence observed in native cells. The structural determinants of polyamine blockade and the structure-activity profile of endogenous polyamines requires specialized methodology for characterizing polyamine interactions with Kir channels. Recent identification and growing interest in the structure and function of prokaryotic Kir channels (KirBacs) has driven the development of new techniques for measuring ion channel activity. Several methods for measuring polyamine interactions with prokaryotic and eukaryotic Kir channels are discussed. PMID:21318869

  18. Controlling magnetic and electric dipole modes in hollow silicon nanocylinders.

    PubMed

    van de Haar, Marie Anne; van de Groep, Jorik; Brenny, Benjamin J M; Polman, Albert

    2016-02-01

    We propose a dielectric nanoresonator geometry consisting of hollow dielectric nanocylinders which support geometrical resonances. We fabricate such hollow Si particles with an outer diameter of 108-251 nm on a Si substrate, and determine their resonant modes with cathodo-luminescence (CL) spectroscopy and optical dark-field (DF) scattering measurements. The scattering behavior is numerically investigated in a systematic fashion as a function of wavelength and particle geometry. We find that the additional design parameter as a result of the introduction of a center gap can be used to control the relative spectral spacing of the resonant modes, which will enable additional control over the angular radiation pattern of the scatterers. Furthermore, the gap offers direct access to the enhanced magnetic dipole modal field in the center of the particle. PMID:26906780

  19. Improving Memory Characteristics of Hydrogenated Nanocrystalline Silicon Germanium Nonvolatile Memory Devices by Controlling Germanium Contents.

    PubMed

    Kim, Jiwoong; Jang, Kyungsoo; Phu, Nguyen Thi Cam; Trinh, Thanh Thuy; Raja, Jayapal; Kim, Taeyong; Cho, Jaehyun; Kim, Sangho; Park, Jinjoo; Jung, Junhee; Lee, Youn-Jung; Yi, Junsin

    2016-05-01

    Nonvolatile memory (NVM) with silicon dioxide/silicon nitride/silicon oxynitride (ONO(n)) charge trap structure is a promising flash memory technology duo that will fulfill process compatibility for system-on-panel displays, down-scaling cell size and low operation voltage. In this research, charge trap flash devices were fabricated with ONO(n) stack gate insulators and an active layer using hydrogenated nanocrystalline silicon germanium (nc-SiGe:H) films at a low temperature. In this study, the effect of the interface trap density on the performance of devices, including memory window and retention, was investigated. The electrical characteristics of NVM devices were studied controlling Ge content from 0% to 28% in the nc-SiGe:H channel layer. The optimal Ge content in the channel layer was found to be around 16%. For nc-SiGe:H NVM with 16% Ge content, the memory window was 3.13 V and the retention data exceeded 77% after 10 years under the programming condition of 15 V for 1 msec. This showed that the memory window increased by 42% and the retention increased by 12% compared to the nc-Si:H NVM that does not contain Ge. However, when the Ge content was more than 16%, the memory window and retention property decreased. Finally, this research showed that the Ge content has an effect on the interface trap density and this enabled us to determine the optimal Ge content. PMID:27483856

  20. Control of silicon oxynitrides refractive index by reactive-assisted ion beam sputter deposition

    NASA Astrophysics Data System (ADS)

    Ida, Michel; Chaton, Patrick; Rafin, B.

    1994-11-01

    This paper presents the properties of silicon oxynitrides obtained by reactive ion beam sputter deposition: Dual Ion Beam System. Control of refractive index was achieved by adjusting the process parameters as ion beam current, ion beam energy and reactive gas partial pressure of oxygen and nitrogen. The main difficulty was to achieve stoichiometric nitride, it has been shown that energetic ionized nitrogen was needed to obtain silicon nitride. The major parameter, to obtain variable compositions between silica and silicon nitride, was the oxygen partial pressure with a fixed nitrogen partial pressure. Optical constants in the visible range, refractive index and extinction coefficient, have been measured by spectrophotometry and spectroscopic ellipsometry. Stoichiometry, contamination and packing density have been measured by Rutherford Backscattering and Nuclear Reaction Analysis. The correlation between the film composition and optical constants is shown. Various test results indicate that silicon oxynitrides obtained by reactive assisted ion beam sputtering are high quality optical materials. These films are homogeneous isotropic, with a high packing density. The extinction coefficient is in the order of 10-4 after 300 degree(s)C annealing. All values of refractive index between 1.49 and 2.1 can be chosen.

  1. Temperature Dependent Spin Transport in Silicon Controlled by an Electrostatic Gate

    NASA Astrophysics Data System (ADS)

    Li, Jing; Appelbaum, Ian

    2011-03-01

    Long-distance (~ 500 μ m) lateral spin polarized electron transport in undoped silicon under the control of an electrostatic gate is studied from 40K to 120K. The temperature dependence of average spin polarization, transport time, and spin dephasing during coherent precession can be largely attributed to reduction of finite spin lifetime at higher temperatures. Measurements on devices with different transport lengths are shown to modify the effect of electrostatic gating. Support from ONR is acknowledged.

  2. Quantum entanglement and spin control in silicon nanocrystal.

    PubMed

    Berec, Vesna

    2012-01-01

    Selective coherence control and electrically mediated exchange coupling of single electron spin between triplet and singlet states using numerically derived optimal control of proton pulses is demonstrated. We obtained spatial confinement below size of the Bohr radius for proton spin chain FWHM. Precise manipulation of individual spins and polarization of electron spin states are analyzed via proton induced emission and controlled population of energy shells in pure (29)Si nanocrystal. Entangled quantum states of channeled proton trajectories are mapped in transverse and angular phase space of (29)Si <100> axial channel alignment in order to avoid transversal excitations. Proton density and proton energy as impact parameter functions are characterized in single particle density matrix via discretization of diagonal and nearest off-diagonal elements. We combined high field and low densities (1 MeV/92 nm) to create inseparable quantum state by superimposing the hyperpolarizationed proton spin chain with electron spin of (29)Si. Quantum discretization of density of states (DOS) was performed by the Monte Carlo simulation method using numerical solutions of proton equations of motion. Distribution of gaussian coherent states is obtained by continuous modulation of individual spin phase and amplitude. Obtained results allow precise engineering and faithful mapping of spin states. This would provide the effective quantum key distribution (QKD) and transmission of quantum information over remote distances between quantum memory centers for scalable quantum communication network. Furthermore, obtained results give insights in application of channeled protons subatomic microscopy as a complete versatile scanning-probe system capable of both quantum engineering of charged particle states and characterization of quantum states below diffraction limit linear and in-depth resolution.PACS NUMBERS: 03.65.Ud, 03.67.Bg, 61.85.+p, 67.30.hj. PMID:23028884

  3. Quantum Entanglement and Spin Control in Silicon Nanocrystal

    PubMed Central

    Berec, Vesna

    2012-01-01

    Selective coherence control and electrically mediated exchange coupling of single electron spin between triplet and singlet states using numerically derived optimal control of proton pulses is demonstrated. We obtained spatial confinement below size of the Bohr radius for proton spin chain FWHM. Precise manipulation of individual spins and polarization of electron spin states are analyzed via proton induced emission and controlled population of energy shells in pure 29Si nanocrystal. Entangled quantum states of channeled proton trajectories are mapped in transverse and angular phase space of 29Si axial channel alignment in order to avoid transversal excitations. Proton density and proton energy as impact parameter functions are characterized in single particle density matrix via discretization of diagonal and nearest off-diagonal elements. We combined high field and low densities (1 MeV/92 nm) to create inseparable quantum state by superimposing the hyperpolarizationed proton spin chain with electron spin of 29Si. Quantum discretization of density of states (DOS) was performed by the Monte Carlo simulation method using numerical solutions of proton equations of motion. Distribution of gaussian coherent states is obtained by continuous modulation of individual spin phase and amplitude. Obtained results allow precise engineering and faithful mapping of spin states. This would provide the effective quantum key distribution (QKD) and transmission of quantum information over remote distances between quantum memory centers for scalable quantum communication network. Furthermore, obtained results give insights in application of channeled protons subatomic microscopy as a complete versatile scanning-probe system capable of both quantum engineering of charged particle states and characterization of quantum states below diffraction limit linear and in-depth resolution. PACS numbers: 03.65.Ud, 03.67.Bg, 61.85.+p, 67.30.hj PMID:23028884

  4. Coherent control of single spins in a silicon carbide pn junction device at room temperature

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Yun; Widmann, Matthias; Booker, Ian; Niethammer, Matthias; Ohshima, Takeshi; Gali, Adam; Son, Nguyen T.; Janzén, Erik; Wrachtrup, Joerg

    Spins in single defects have been studied for quantum information science and quantum metrology. It has been proven that spins of the single nitrogen-vacancy (NV) centers in diamond can be used as a quantum bit, and a single spin sensor operating at ambient conditions. Recently, there has been a growing interest in a new material in which color centers similar to NV centers can be created and whose electrical properties can also be well controlled, thus existing electronic devices can easily be adapted as a platform for quantum applications. We recently reported that single spins of negatively charged silicon vacancies in SiC can be coherently controlled and long-lived at room temperature. As a next step, we isolated single silicon vacancies in a SiC pn junction device and investigated how the change in Fermi level, induced by applying bias, alters the charge state of silicon vacancies, thus affects the spin state control. This study will allow us to envision quantum applications based on single defects incorporated in modern electronic devices.

  5. Theoretical Study of Donor - Spacer - Acceptor Structure Molecule for Molecular Rectifier

    NASA Astrophysics Data System (ADS)

    Mizuseki, Hiroshi; Kenji, Niimura; Belosludov, Rodion; Farajian, Amir; Kawazoe, Yoshiyuki

    2003-03-01

    Recently, the molecular electronics has attracted strong attention as a ``post-silicone technology'' to establish a future nanoscale electronic devices. To realize this molecular device, unimolecular rectifiering function is one of the most important constituents in nanotechnology [C. Majumder, H. Mizuseki, and Y. Kawazoe, Molecular Scale Rectifier: Theoretical Study, J. Phys. Chem. A, 105 (2001) 9454-9459.]. In the present study, the geometric and electronic structure of alkyl derivative C37H50N4O4 (PNX) molecule, (donor - spacer - acceptor), a leading candidate of molecular rectifying device, has been investigated theoretically using ab initio quantum mechanical calculation. The results suggest that in such donor-acceptor molecular complexes, while the lowest unoccupied orbital concentrates on the acceptor subunit, the highest occupied molecular orbital is localized on the donor subunit. The approximate potential differences for optimized PNX molecule have been estimated at the B3PW91/6-311g++(d,p) level of theory, which achieves quite good agreement with experimentally reported results. This study was performed through Special Coordination Funds for Promoting Science and Technology of the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government.

  6. High Voltage GaN Schottky Rectifiers

    SciTech Connect

    CAO,X.A.; CHO,H.; CHU,S.N.G.; CHUO,C.-C.; CHYI,J.-I.; DANG,G.T.; HAN,JUNG; LEE,C.-M.; PEARTON,S.J.; REN,F.; WILSON,R.G.; ZHANG,A.P.

    1999-10-25

    Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V{sub RB}) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R{sub ON}, was 6m{Omega}{center_dot} cm{sup 2} and 0.8{Omega}cm{sup 2}, respectively, producing figure-of-merit values for (V{sub RB}){sup 2}/R{sub ON} in the range 5-48 MW{center_dot}cm{sup -2}. At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high biases the current was proportional to the area of this contact. These results suggest that at low reverse biases, the leakage is dominated by the surface component, while at higher biases the bulk component dominates. On-state voltages were 3.5V for the 550V diodes and {ge}15 for the 2kV diodes. Reverse recovery times were <0.2{micro}sec for devices switched from a forward current density of {approx}500A{center_dot}cm{sup -2} to a reverse bias of 100V.

  7. Formation of size controlled silicon nanocrystals in nitrogen free silicon dioxide matrix prepared by plasma enhanced chemical vapor deposition

    SciTech Connect

    Laube, J. Gutsch, S.; Hiller, D.; Zacharias, M.; Bruns, M.; Kübel, C.; Weiss, C.

    2014-12-14

    This paper reports the growth of silicon nanocrystals (SiNCs) from SiH4–O{sub 2} plasma chemistry. The formation of an oxynitride was avoided by using O{sub 2} instead of the widely used N{sub 2}O as precursor. X-ray photoelectron spectroscopy is used to prove the absence of nitrogen in the layers and determine the film stoichiometry. It is shown that the Si rich film growth is achieved via non-equilibrium deposition that resembles a interphase clusters mixture model. Photoluminescence and Fourier transformed infrared spectroscopy are used to monitor the formation process of the SiNCs, to reveal that the phase separation is completed at lower temperatures as for SiNCs based on oxynitrides. Additionally, transmission electron microscopy proves that the SiNC sizes are well controllable by superlattice configuration, and as a result, the optical emission band of the Si nanocrystal can be tuned over a wide range.

  8. Indium growth and island height control on silicon submonolayer phases

    NASA Astrophysics Data System (ADS)

    Chen, Jizhou

    The quantum size effects (QSE) make it possible to control the dimensions of self-assembled nanostructures. An important goal in present day surface science is to grow uniform sized self-assembled nanostructures. One system which has displayed a number of interesting surface structures is Pb/In grown on a Si(111) substrate. The first part of the thesis discussed Pb islands grown on the anisotropic Si(111)-In(4x1) substrate. In addition to a preferred height of 4 monolayers due to QSE, these islands grow as nanowires with a preferred width of 660nm due to strain driven growth from the anisotropic substrate. Islands grown on the In(4x1) substrate also retain their preferred height to room temperature in contrast to previously observed critical temperatures of 250 K or less for islands grown on other substrates. Then In islands were grown on Si(111)-Pb-alpha-sqrt3 x sqrt3 substrate. The In islands in face-centered cubic (FCC) structure were found to have a preferred height of 4 monolayers due to QSE. With further depositions, an FCC to body-centered tetragonal(BCT) structure transition is observed. The In bct islands was found to have unexpected fast growth rate compared to FCC structure, which indicate the extra high mobility of In atoms. In the last part In islands were grown on varies of In phases at low temperature. Conversion between submonolayer In phases are observed. Due to the highly mobility of In atoms, the QSE effects observed on the Pb alpha phase is not observed.

  9. Control of valley dynamics in silicon quantum dots in the presence of an interface step

    NASA Astrophysics Data System (ADS)

    Boross, Péter; Széchenyi, Gábor; Culcer, Dimitrie; Pályi, András

    2016-07-01

    Recent experiments on silicon nanostructures have seen breakthroughs toward scalable, long-lived quantum information processing. The valley degree of freedom plays a fundamental role in these devices, and the two lowest-energy electronic states of a silicon quantum dot can form a valley qubit. In this paper, we show that a single-atom high step at the silicon/barrier interface induces a strong interaction of the qubit and in-plane electric fields and that the strength of this interaction can be controlled by varying the relative position of the electron and the step. We analyze the consequences of this enhanced interaction on the dynamics of the qubit. The charge densities of the qubit states are deformed differently by the interface step, allowing nondemolition qubit readout via valley-to-charge conversion. A gate-induced in-plane electric field together with the interface step enables fast control of the valley qubit via electrically driven valley resonance. We calculate single- and two-qubit gate times, as well as relaxation and dephasing times, and present predictions for the parameter range where the gate times can be much shorter than the relaxation time and dephasing is reduced.

  10. FAST TRACK COMMUNICATION: Nanocrystalline silicon film growth morphology control through RF waveform tailoring

    NASA Astrophysics Data System (ADS)

    Johnson, Erik V.; Verbeke, Thomas; Vanel, Jean-Charles; Booth, Jean-Paul

    2010-10-01

    We demonstrate the application of RF waveform tailoring to generate an electrical asymmetry in a capacitively coupled plasma-enhanced chemical vapour deposition system, and its use to control the growth mode of hydrogenated amorphous and nanocrystalline silicon thin films deposited at low temperature (150 °C). A dramatic shift in the dc bias potential at the powered electrode is observed when simply inverting the voltage waveform from 'peaks' to 'troughs', indicating an asymmetric distribution of the sheath voltage. By enhancing or suppressing the ion bombardment energy at the substrate (situated on the grounded electrode), the growth of thin silicon films can be switched between amorphous and nanocrystalline modes, as observed using in situ spectroscopic ellipsometry. The effect is observed at pressures sufficiently low that the collisional reduction in average ion bombardment energy is not sufficient to allow nanocrystalline growth (<100 mTorr).

  11. Surface photovoltage method for the quality control of silicon epitaxial layers on sapphire

    SciTech Connect

    Yaremchuk, A. F.; Starkov, A. V.; Zaikin, A. V.; Alekseev, A. V.; Sokolov, E. M.

    2014-12-15

    The surface photovoltage method is used to study “silicon-on-sapphire” epitaxial layers with a thickness of 0.3–0.6 μm, which are used to fabricate p-channel MOS (metal—oxide-semiconductor) transistors with improved radiation hardness. It is shown that the manner in which the photoconductivity of the epitaxial layer decays after the end of a light pulse generated by a light-emitting diode (wavelength ∼400 nm) strongly depends on the density of structural defects in the bulk of the structure. This enables control over how a “silicon-on-sapphire” structure is formed to provide the manufacturing of MOS structures with optimal operating characteristics.

  12. Gate-controlled-diodes in silicon-on-sapphire: A computer simulation

    NASA Technical Reports Server (NTRS)

    Gassaway, J. D.

    1974-01-01

    The computer simulation of the electrical behavior of a Gate-Controlled Diode (GCD) fabricated in Silicon-On-Sapphire (SOS) was described. A procedure for determining lifetime profiles from capacitance and reverse current measurements on the GCD was established. Chapter 1 discusses the SOS structure and points out the need of lifetime profiles to assist in device design for GCD's and bipolar transistors. Chapter 2 presents the one-dimensional analytical formula for electrostatic analysis of the SOS-GCD which are useful for data interpretation and setting boundary conditions on a simplified two-dimensional analysis. Chapter 3 gives the results of a two-dimensional analysis which treats the field as one-dimensional until the silicon film is depleted and the field penetrates the sapphire substrate. Chapter 4 describes a more complete two-dimensional model and gives results of programs implementing the model.

  13. 46 CFR 183.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier...) Meet Sections 35.84.2 and 35.84.4 of the ABS Steel Vessel Rules (incorporated by reference; see 46 CFR... 46 Shipping 7 2013-10-01 2013-10-01 false Semiconductor rectifier systems. 183.360 Section...

  14. 46 CFR 183.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier...) Meet Sections 35.84.2 and 35.84.4 of the ABS Steel Vessel Rules (incorporated by reference; see 46 CFR... 46 Shipping 7 2011-10-01 2011-10-01 false Semiconductor rectifier systems. 183.360 Section...

  15. 46 CFR 183.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier...) Meet Sections 35.84.2 and 35.84.4 of the ABS Steel Vessel Rules (incorporated by reference; see 46 CFR... 46 Shipping 7 2012-10-01 2012-10-01 false Semiconductor rectifier systems. 183.360 Section...

  16. 46 CFR 183.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each...

  17. 46 CFR 183.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier...) Meet Sections 35.84.2 and 35.84.4 of the ABS Steel Vessel Rules (incorporated by reference; see 46 CFR... 46 Shipping 7 2014-10-01 2014-10-01 false Semiconductor rectifier systems. 183.360 Section...

  18. High-Efficiency Harmonically Terminated Diode and Transistor Rectifiers

    SciTech Connect

    Roberg, M; Reveyrand, T; Ramos, I; Falkenstein, EA; Popovic, Z

    2012-12-01

    This paper presents a theoretical analysis of harmonically terminated high-efficiency power rectifiers and experimental validation on a class-C single Schottky-diode rectifier and a class-F-1 GaN transistor rectifier. The theory is based on a Fourier analysis of current and voltage waveforms, which arise across the rectifying element when different harmonic terminations are presented at its terminals. An analogy to harmonically terminated power amplifier (PA) theory is discussed. From the analysis, one can obtain an optimal value for the dc load given the RF circuit design. An upper limit on rectifier efficiency is derived for each case as a function of the device on-resistance. Measured results from fundamental frequency source-pull measurement of a Schottky diode rectifier with short-circuit terminations at the second and third harmonics are presented. A maximal device rectification efficiency of 72.8% at 2.45 GHz matches the theoretical prediction. A 2.14-GHz GaN HEMT rectifier is designed based on a class-F-1 PA. The gate of the transistor is terminated in an optimal impedance for self-synchronous rectification. Measurements of conversion efficiency and output dc voltage for varying gate RF impedance, dc load, and gate bias are shown with varying input RF power at the drain. The rectifier demonstrates an efficiency of 85% for a 10-W input RF power at the transistor drain with a dc voltage of 30 V across a 98-Omega resistor.

  19. Inward rectifier current noise in frog skeletal muscle.

    PubMed Central

    DeCoursey, T E; Dempster, J; Hutter, O F

    1984-01-01

    Inwardly rectifying K+ currents were studied in cut muscle fibres from frogs using the Vaseline-gap voltage-clamp method. Both faces of the membrane were exposed to 120 mM-K+ methylsulphate solution. At small negative potentials, -10 and -21 mV, the current noise spectrum, after subtraction of a control spectrum at the zero current potential, could be fitted by a Lorentzian spectral component, usually with an additional 1/f component, where f is the frequency. At more negative potentials the 1/f component predominated. The zero frequency amplitude of the Lorentzian averaged 2.6 X 10(-24) A2 Hz-1 at -10 mV and 4.6 X 10(-24) A2 Hz-1 at -21 mV, with a mean half-power frequency, fc, of 34 Hz and 45 Hz, respectively. The time constant of the K+ current activation upon hyperpolarization agrees with that calculated from fc, and the Lorentzian disappears upon replacement of external K+ by tetraethylammonium (TEA+) or Rb+. Thus, the Lorentzian component appears to be ascribable to fluctuations originating in the inwardly rectifying mechanism. The noise spectra and macroscopic currents were interpreted by assuming that the inwardly rectifying K+ conductance is proportional to the product of two parameters: ps representing the state of the mechanism that gives rise to the observable macroscopic current relaxations and to the current fluctuations resulting in the observed Lorentzian spectra, and pf describing the instantaneous rectification of the single-channel conductance. Alternatively, pf may represent another mechanism in series with ps, but which fluctuates too rapidly to measure. Using this model the limiting single-channel conductance, gamma, was found to be approximately 9 pS. The corresponding specific density of channels is about 1 micron-2, assuming uniform distribution over all regions of the membrane. A preliminary value for gamma ( DeCoursey & Hutter , 1982) was derived without consideration of instantaneous rectification. Systematic errors in these results due

  20. Neural induction suppresses early expression of the inward-rectifier K+ channel in the ascidian blastomere.

    PubMed Central

    Okamura, Y; Takahashi, K

    1993-01-01

    gastrula stage was sensitive to alpha-amanitin, a highly specific transcription inhibitor. In both induced and uninduced cells, injection of alpha-amanitin at the 32-cell stage reduced the current density of the inward-rectifier K+ channel to about 2 nA/nF, corresponding to 13% of that recorded from uninjected cells. By contrast, the expression of the fast-inactivating-type Na+ current, which transiently increased along with the inward-rectifier K+ channel, was resistant to alpha-amanitin injection. 6. The dose of alpha-amanitin injected was controlled by monitoring co-injected fluorescent dye, fura-2.(ABSTRACT TRUNCATED AT 400 WORDS) Images Fig. 6 Fig. 8 Fig. 11 PMID:8246182

  1. Costs of controlling emissions from the manufacture of silicon photovoltaic cells using dendritic web technology

    SciTech Connect

    Wilenitz, I.

    1983-11-01

    Detailed analyses were conducted to determine environmental control costs associated with the production of silicon dendritic web photovoltaic (PV) cells. In these analyses (i) likely manufacturing processing steps were identified, (ii) material inputs and uncontrolled material outputs were estimated, (iii) need for and capability of environmental control equipment were examined, and (iv) capital and operation and maintenance costs for environmental controls for integrated and disaggregated plant designs were estimated. These estimates were developed for a hypothetical facility with a yearly output of PV cells capable of producing 10 MWp. Analysis suggested that the annualized incremental environmental control costs, based on capital recovery over a 10 year plant life, would be 1.4 cents and 2.8 cents per watt for integrated and disaggregated plant designs, respectively. Capital costs ranged from 50% to 55% (integrated) and 36% to 40% (disaggregated) of the estimated costs; the ranges reflected differences in assumed real discount rates. Because of the small emission flows projected, treatment equipment to be used, for the most part, represents the smallest size readily available from equipment manufacturers. Consequently, larger emission flows could be accommodated without additional capital costs. Total control costs are small in comparison with current production costs for silicon photovoltaic devices ($5/watt), but may be of greater importance at projected production cost of $0.5 to 1.0/watt. These conclusions may not apply to other material or process options.

  2. Candidate locations for SPS rectifying antennas

    NASA Technical Reports Server (NTRS)

    Eberhardt, A. W.

    1977-01-01

    The feasibility of placing 120 Satellite Power System (SPS) rectifying antenna (rectenna) sites across the U.S. was studied. An initial attempt is made to put two land sites in each state using several land site selection criteria. When only 69 land sites are located, it is decided to put the remaining sites in the sea and sea site selection criteria are identified. An estimated projection of electrical demand distribution for the year 2000 is then used to determine the distribution of these sites along the Pacific, Atlantic, and Gulf Coasts. A methodology for distributing rectenna sites across the country and for fine-tuning exact locations is developed, and recommendations on rectenna design and operations are made.

  3. Triple quantum dots as charge rectifiers.

    PubMed

    Busl, M; Platero, G

    2012-04-18

    We theoretically analyze electronic spin transport through a triple quantum dot in series, attached to electrical contacts, where the drain contact is coupled to the central dot. We show that current rectification is observed in the device due to current blockade. The current blocking mechanism is originated by a destructive interference of the electronic wavefunction at the drain dot. There, the electrons are coherently trapped in a singlet two-electron dark state, which is a coherent superposition of the electronic wavefunction in the source dot and in the dot isolated from the contacts. Its formation gives rise to zero current and current rectification as the voltage is swept. We analyze this behavior analytically and numerically for both zero and finite magnetic dc fields. On top of that, we include phenomenologically a finite spin relaxation rate and calculate the current numerically. Our results show that triple dots in series can be designed to behave as quantum charge rectifiers. PMID:22442135

  4. Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures

    SciTech Connect

    Sharp, Ian D.; Bracht, Hartmut A.; Silvestri, Hughes H.; Nicols, Samuel P.; Beeman, Jeffrey W.; Hansen, John L.; Nylandsted Larsen, Arne; Haller, Eugene E.

    2002-04-01

    Isotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. {sup 30}Si was used as a tracer through a multilayer structure of alternating natural Si and enriched {sup 28}Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850 C and 1100 C. A specially designed ion- implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

  5. Control of single-electron charging of metallic nanoparticles onto amorphous silicon surface.

    PubMed

    Weis, Martin; Gmucová, Katarína; Nádazdy, Vojtech; Capek, Ignác; Satka, Alexander; Kopáni, Martin; Cirák, Július; Majková, Eva

    2008-11-01

    Sequential single-electron charging of iron oxide nanoparticles encapsulated in oleic acid/oleyl amine envelope and deposited by the Langmuir-Blodgett technique onto Pt electrode covered with undoped hydrogenated amorphous silicon film is reported. Single-electron charging (so-called quantized double-layer charging) of nanoparticles is detected by cyclic voltammetry as current peaks and the charging effect can be switched on/off by the electric field in the surface region induced by the excess of negative/positive charged defect states in the amorphous silicon layer. The particular charge states in amorphous silicon are created by the simultaneous application of a suitable bias voltage and illumination before the measurement. The influence of charged states on the electric field in the surface region is evaluated by the finite element method. The single-electron charging is analyzed by the standard quantized double layer model as well as two weak-link junctions model. Both approaches are in accordance with experiment and confirm single-electron charging by tunnelling process at room temperature. This experiment illustrates the possibility of the creation of a voltage-controlled capacitor for nanotechnology. PMID:19198289

  6. Gate-controlled diode structure based electro-optical interfaces in standard silicon-CMOS integrated circuitry.

    PubMed

    Xu, Kaikai; Liu, Haitao; Zhang, Zhengyuan

    2015-07-20

    In this paper, we discuss the emission of visible light by a monolithically integrated silicon gate-controlled diode with the p-n junction reverse-biased. Since the MOS-like diode utilizes the field effect to modulate the optical output, the modulation speed will benefit from this mechanism. Hence, a silicon gate-controlled diode structure for optical modulation analyzed its modulation principle, its dynamic characteristics are presented, and the bandwidth of the device is considered to approach GHz in theory due to the field-induced emission mechanism. The prototype MOS-like diode opens up the design of multiterminal silicon light emitting devices (LEDs), where gate electrodes with more than one gate contact overlap several junctions with different junction intersection geometries. The device appears as a good candidate for optical modulation within silicon technology. PMID:26367823

  7. Electrically conductive, black thermal control coatings for space craft application. II - Silicone matrix formulation

    NASA Technical Reports Server (NTRS)

    Hribar, V. F.; Bauer, J. L.; O'Donnell, T. P.

    1986-01-01

    Five black electrically conductive thermal-control coatings have been formulated and tested for application on the Galileo spacecraft. The coatings consisted of organic and inorganic systems applied on titanium and aluminum surfaces. The coatings were tested under simulated space environment conditions. Coated specimens were subjected to thermal radiation and convective and conductive heating from -196 to 538 C. Mechanical, physical, thermal, electrical, and optical characteristics, formulation, mixing, application, surface preparation of substrates, and a method of determining electrical resistance are presented for the silicone matrix formulation designated as GF-580.

  8. Pore Size Control of Ultra-thin Silicon Membranes by Rapid Thermal Carbonization

    PubMed Central

    Fang, David Z.; Striemer, Christopher C.; Gaborski, Thomas R.; McGrath, James L.; Fauchet, Philippe M.

    2010-01-01

    Rapid thermal carbonization in a dilute acetylene (C2H2) atmosphere has been used to chemically modify and precisely tune the pore size of ultrathin porous nanocrystalline silicon (pnc-Si). The magnitude of size reduction was controlled by varying the process temperature and time. Under certain conditions, the carbon coating displayed atomic ordering indicative of graphene layer formation conformal to the pore walls. Initial experiments show that carbonized membranes follow theoretical predictions for hydraulic permeability and retain the precise separation capabilities of untreated membranes. PMID:20839831

  9. Hydrogenated amorphous silicon formation by flux control and hydrogen effects on the growth mechanism

    NASA Astrophysics Data System (ADS)

    Toyoda, H.; Sugai, H.; Kato, K.; Yoshida, A.; Okuda, T.

    1986-06-01

    The composition of particle flux to deposit hydrogenated amorphous silicon films in a glow discharge is controlled by a combined electrostatic-magnetic deflection technique. As a result, the films are formed firstly without hydrogen ion flux, secondly by neutral flux only, and thirdly by all species fluxes. Comparison of these films reveals the significant role of hydrogen in the surface reactions. Hydrogen breaks the Si-Si bond, decreases the sticking probability of the Si atom, and replaces the SiH bond by a SiH2 bond to increase the hydrogen content of the films.

  10. Band-Structure Engineering of Gold Atomic Wires on Silicon by Controlled Doping

    NASA Astrophysics Data System (ADS)

    Choi, Won Hoon; Kang, Pil Gyu; Ryang, Kyung Deuk; Yeom, Han Woong

    2008-03-01

    We report on the systematic tuning of the electronic band structure of atomic wires by controlling the density of impurity atoms. The atomic wires are self-assembled on Si(111) by substitutional gold adsorbates and extra silicon atoms are deposited as the impurity dopants. The one-dimensional electronic band of gold atomic wires, measured by angle-resolved photoemission, changes from a fully metallic to semiconducting one with its band gap increasing above 0.3 eV along with an energy shift as a linear function of the Si dopant density. The gap opening mechanism is suggested to be related to the ordering of the impurities.

  11. Controlling the spectrum of photons generated on a silicon nanophotonic chip

    PubMed Central

    Kumar, Ranjeet; Ong, Jun Rong; Savanier, Marc; Mookherjea, Shayan

    2014-01-01

    Directly modulated semiconductor lasers are widely used, compact light sources in optical communications. Semiconductors can also be used to generate nonclassical light; in fact, CMOS-compatible silicon chips can be used to generate pairs of single photons at room temperature. Unlike the classical laser, the photon-pair source requires control over a two-dimensional joint spectral intensity (JSI) and it is not possible to process the photons separately, as this could destroy the entanglement. Here we design a photon-pair source, consisting of planar lightwave components fabricated using CMOS-compatible lithography in silicon, which has the capability to vary the JSI. By controlling either the optical pump wavelength, or the temperature of the chip, we demonstrate the ability to select different JSIs, with a large variation in the Schmidt number. Such control can benefit high-dimensional communications where detector-timing constraints can be relaxed by realizing a large Schmidt number in a small frequency range. PMID:25410792

  12. Open Air Silicon Deposition by Atmospheric Pressure Plasma under Local Ambient Gas Control

    NASA Astrophysics Data System (ADS)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2015-09-01

    In this paper, we report open air silicon (Si) deposition by combining a silane free Si deposition technology and a newly developed local ambient gas control technology. Recently, material processing in open air has been investigated intensively. While a variety of materials have been deposited, there were only few reports on Si deposition due to the susceptibility to contamination and the hazardous nature of source materials. Since Si deposition is one of the most important processes in device fabrication, we have developed open air silicon deposition technologies in BEANS project. For a clean and safe process, a local ambient gas control head was designed. Process gas leakage was prevented by local evacuation, and air contamination was shut out by inert curtain gas. By numerical and experimental investigations, a safe and clean process condition with air contamination less than 10 ppm was achieved. Si film was deposited in open air by atmospheric pressure plasma enhanced chemical transport under the local ambient gas control. The film was microcrystalline Si with the crystallite size of 17 nm, and the Hall mobility was 2.3 cm2/V .s. These properties were comparable to those of Si films deposited in a vacuum chamber. This research has been conducted as one of the research items of New Energy and Industrial Technology Development Organization ``BEANS'' project.

  13. Study of charge control and gate tunneling in a ferroelectric-oxide-silicon field effect transistor: Comparison with a conventional metal-oxide-silicon structure

    NASA Astrophysics Data System (ADS)

    Lin, Yih-Yin; Zhang, Yifei; Singh, Jasprit; York, Robert; Mishra, Umesh

    2001-02-01

    It is known that conventional metal-oxide-silicon (MOS) devices will have gate tunneling related problems at very thin oxide thicknesses. Various high-dielectric-constant materials are being examined to suppress the gate currents. In this article we present theoretical results of a charge control and gate tunneling model for a ferroelectric-oxide-silicon field effect transistor and compare them to results for a conventional MOS device. The potential of high polarization charge to induce inversion without doping and high dielectric constant to suppress tunneling current is explored. The model is based on a self-consistent solution of the quantum problem and includes the ferroelectric hysteresis response self-consistently. We show that the polarization charge associated with ferroelectrics can allow greater controllability of the inversion layer charge density. Also the high dielectric constant of ferroelectrics results in greatly suppressed gate current.

  14. Controllable electrical and physical breakdown of poly-crystalline silicon nanowires by thermally assisted electromigration

    NASA Astrophysics Data System (ADS)

    Park, Jun-Young; Moon, Dong-Il; Seol, Myeong-Lok; Jeon, Chang-Hoon; Jeon, Gwang-Jae; Han, Jin-Woo; Kim, Choong-Ki; Park, Sang-Jae; Lee, Hee Chul; Choi, Yang-Kyu

    2016-01-01

    The importance of poly-crystalline silicon (poly-Si) in semiconductor manufacturing is rapidly increasing due to its highly controllable conductivity and excellent, uniform deposition quality. With the continuing miniaturization of electronic components, low dimensional structures such as 1-dimensional nanowires (NWs) have attracted a great deal of attention. But such components have a much higher current density than 2- or 3- dimensional films, and high current can degrade device lifetime and lead to breakdown problems. Here, we report on the electrical and thermal characteristics of poly-Si NWs, which can also be used to control electrical and physical breakdown under high current density. This work reports a controllable catastrophic change of poly-Si NWs by thermally-assisted electromigration and underlying mechanisms. It also reports the direct and real time observation of these catastrophic changes of poly-Si nanowires for the first time, using scanning electron microscopy.

  15. Controllable electrical and physical breakdown of poly-crystalline silicon nanowires by thermally assisted electromigration

    PubMed Central

    Park, Jun-Young; Moon, Dong-Il; Seol, Myeong-Lok; Jeon, Chang-Hoon; Jeon, Gwang-Jae; Han, Jin-Woo; Kim, Choong-Ki; Park, Sang-Jae; Lee, Hee Chul; Choi, Yang-Kyu

    2016-01-01

    The importance of poly-crystalline silicon (poly-Si) in semiconductor manufacturing is rapidly increasing due to its highly controllable conductivity and excellent, uniform deposition quality. With the continuing miniaturization of electronic components, low dimensional structures such as 1-dimensional nanowires (NWs) have attracted a great deal of attention. But such components have a much higher current density than 2- or 3- dimensional films, and high current can degrade device lifetime and lead to breakdown problems. Here, we report on the electrical and thermal characteristics of poly-Si NWs, which can also be used to control electrical and physical breakdown under high current density. This work reports a controllable catastrophic change of poly-Si NWs by thermally-assisted electromigration and underlying mechanisms. It also reports the direct and real time observation of these catastrophic changes of poly-Si nanowires for the first time, using scanning electron microscopy. PMID:26782708

  16. Controllable electrical and physical breakdown of poly-crystalline silicon nanowires by thermally assisted electromigration.

    PubMed

    Park, Jun-Young; Moon, Dong-Il; Seol, Myeong-Lok; Jeon, Chang-Hoon; Jeon, Gwang-Jae; Han, Jin-Woo; Kim, Choong-Ki; Park, Sang-Jae; Lee, Hee Chul; Choi, Yang-Kyu

    2016-01-01

    The importance of poly-crystalline silicon (poly-Si) in semiconductor manufacturing is rapidly increasing due to its highly controllable conductivity and excellent, uniform deposition quality. With the continuing miniaturization of electronic components, low dimensional structures such as 1-dimensional nanowires (NWs) have attracted a great deal of attention. But such components have a much higher current density than 2- or 3-dimensional films, and high current can degrade device lifetime and lead to breakdown problems. Here, we report on the electrical and thermal characteristics of poly-Si NWs, which can also be used to control electrical and physical breakdown under high current density. This work reports a controllable catastrophic change of poly-Si NWs by thermally-assisted electromigration and underlying mechanisms. It also reports the direct and real time observation of these catastrophic changes of poly-Si nanowires for the first time, using scanning electron microscopy. PMID:26782708

  17. Cardiac Delayed Rectifier Potassium Channels in Health and Disease.

    PubMed

    Chen, Lei; Sampson, Kevin J; Kass, Robert S

    2016-06-01

    Cardiac delayed rectifier potassium channels conduct outward potassium currents during the plateau phase of action potentials and play pivotal roles in cardiac repolarization. These include IKs, IKr and the atrial specific IKur channels. In this article, we will review their molecular identities and biophysical properties. Mutations in the genes encoding delayed rectifiers lead to loss- or gain-of-function phenotypes, disrupt normal cardiac repolarization and result in various cardiac rhythm disorders, including congenital Long QT Syndrome, Short QT Syndrome and familial atrial fibrillation. We will also discuss the prospect of using delayed rectifier channels as therapeutic targets to manage cardiac arrhythmia. PMID:27261823

  18. Electrical detection of dengue virus (DENV) DNA oligomer using silicon nanowire biosensor with novel molecular gate control.

    PubMed

    Nuzaihan M N, M; Hashim, U; Md Arshad, M K; Kasjoo, S R; Rahman, S F A; Ruslinda, A R; Fathil, M F M; Adzhri, R; Shahimin, M M

    2016-09-15

    In this paper, a silicon nanowire biosensor with novel molecular gate control has been demonstrated for Deoxyribonucleic acid (DNA) detection related to dengue virus (DENV). The silicon nanowire was fabricated using the top-down nanolithography approach, through nanostructuring of silicon-on-insulator (SOI) layers achieved by combination of the electron-beam lithography (EBL), plasma dry etching and size reduction processes. The surface of the fabricated silicon nanowire was functionalized by means of a three-step procedure involving surface modification, DNA immobilization and hybridization. This procedure acts as a molecular gate control to establish the electrical detection for 27-mers base targets DENV DNA oligomer. The electrical detection is based on the changes in current, resistance and conductance of the sensor due to accumulation of negative charges added by the immobilized probe DNA and hybridized target DNA. The sensitivity of the silicon nanowire biosensors attained was 45.0µAM(-1), which shows a wide-range detection capability of the sensor with respect to DNA. The limit of detection (LOD) achieved was approximately 2.0fM. The demonstrated results show that the silicon nanowire has excellent properties for detection of DENV with outstanding repeatability and reproducibility performances. PMID:27107147

  19. Precision control of thermal transport in cryogenic single-crystal silicon devices

    NASA Astrophysics Data System (ADS)

    Rostem, K.; Chuss, D. T.; Colazo, F. A.; Crowe, E. J.; Denis, K. L.; Lourie, N. P.; Moseley, S. H.; Stevenson, T. R.; Wollack, E. J.

    2014-03-01

    We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1 K. It is shown that the phonon mean-free-path ℓ is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than ℓ, even when the surface is fairly smooth, 5-10 nm rms, and the peak thermal wavelength is 0.6 μm. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30 nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order ℓ, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of ±8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

  20. Valley-enhanced fast relaxation of gate-controlled donor qubits in silicon

    NASA Astrophysics Data System (ADS)

    Boross, Péter; Széchenyi, Gábor; Pályi, András

    2016-08-01

    Gate control of donor electrons near interfaces is a generic ingredient of donor-based quantum computing. Here, we address the question: how is the phonon-assisted qubit relaxation time T 1 affected as the electron is shuttled between the donor and the interface? We focus on the example of the ‘flip-flop qubit’ (Tosi et al arXiv:1509.08538v1), defined as a combination of the nuclear and electronic states of a phosphorus donor in silicon, promising fast electrical control and long dephasing times when the electron is halfway between the donor and the interface. We theoretically describe orbital relaxation, flip-flop relaxation, and electron spin relaxation. We estimate that the flip-flop qubit relaxation time can be of the order of 100 μs, 8 orders of magnitude shorter than the value for an on-donor electron in bulk silicon, and a few orders of magnitude shorter (longer) than the predicted inhomogeneous dephasing time (gate times). All three relaxation processes are boosted by (i) the nontrivial valley structure of the electron–phonon interaction, and (ii) the different valley compositions of the involved electronic states.

  1. Valley-enhanced fast relaxation of gate-controlled donor qubits in silicon.

    PubMed

    Boross, Péter; Széchenyi, Gábor; Pályi, András

    2016-08-01

    Gate control of donor electrons near interfaces is a generic ingredient of donor-based quantum computing. Here, we address the question: how is the phonon-assisted qubit relaxation time T 1 affected as the electron is shuttled between the donor and the interface? We focus on the example of the 'flip-flop qubit' (Tosi et al arXiv:1509.08538v1), defined as a combination of the nuclear and electronic states of a phosphorus donor in silicon, promising fast electrical control and long dephasing times when the electron is halfway between the donor and the interface. We theoretically describe orbital relaxation, flip-flop relaxation, and electron spin relaxation. We estimate that the flip-flop qubit relaxation time can be of the order of 100 μs, 8 orders of magnitude shorter than the value for an on-donor electron in bulk silicon, and a few orders of magnitude shorter (longer) than the predicted inhomogeneous dephasing time (gate times). All three relaxation processes are boosted by (i) the nontrivial valley structure of the electron-phonon interaction, and (ii) the different valley compositions of the involved electronic states. PMID:27334425

  2. Precision control of thermal transport in cryogenic single-crystal silicon devices

    SciTech Connect

    Rostem, K.; Chuss, D. T.; Colazo, F. A.; Crowe, E. J.; Denis, K. L.; Lourie, N. P.; Moseley, S. H.; Stevenson, T. R.; Wollack, E. J.

    2014-03-28

    We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1 K. It is shown that the phonon mean-free-path ℓ is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than ℓ, even when the surface is fairly smooth, 5–10 nm rms, and the peak thermal wavelength is 0.6 μm. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30 nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order ℓ, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of ±8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

  3. Control of the Pore Texture in Nanoporous Silicon via Chemical Dissolution.

    PubMed

    Secret, Emilie; Wu, Chia-Chen; Chaix, Arnaud; Galarneau, Anne; Gonzalez, Philippe; Cot, Didier; Sailor, Michael J; Jestin, Jacques; Zanotti, Jean-Marc; Cunin, Frédérique; Coasne, Benoit

    2015-07-28

    The surface and textural properties of porous silicon (pSi) control many of its physical properties essential to its performance in key applications such as optoelectronics, energy storage, luminescence, sensing, and drug delivery. Here, we combine experimental and theoretical tools to demonstrate that the surface roughness at the nanometer scale of pSi can be tuned in a controlled fashion using partial thermal oxidation followed by removal of the resulting silicon oxide layer with hydrofluoric acid (HF) solution. Such a process is shown to smooth the pSi surface by means of nitrogen adsorption, electron microscopy, and small-angle X-ray and neutron scattering. Statistical mechanics Monte Carlo simulations, which are consistent with the experimental data, support the interpretation that the pore surface is initially rough and that the oxidation/oxide removal procedure diminishes the surface roughness while increasing the pore diameter. As a specific example considered in this work, the initial roughness ξ ∼ 3.2 nm of pSi pores having a diameter of 7.6 nm can be decreased to 1.0 nm following the simple procedure above. This study allows envisioning the design of pSi samples with optimal surface properties toward a specific process. PMID:26135844

  4. Precision Control of Thermal Transport in Cryogenic Single-Crystal Silicon Devices

    NASA Technical Reports Server (NTRS)

    Rostem, K.; Chuss, D. T.; Colazo, F. A.; Crowe, E. J.; Denis, K. L.; Lourie, N. P.; Moseley, S. H.; Stevenson, T. R.; Wollack, E. J.

    2014-01-01

    We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1 K. It is shown that the phonon mean-free-path is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than, even when the surface is fairly smooth, 510 nm rms, and the peak thermal wavelength is 0.6 microns. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30 nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of +/-8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

  5. Silicon-based current-controlled reconfigurable magnetoresistance logic combined with non-volatile memory

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaozhong; Luo, Zhaochu

    2015-03-01

    Silicon-based complementary metal-oxide-semiconductor (CMOS) transistors have achieved great success. However, the traditional development pathway is approaching its fundamental limits. Magnetoelectronics logic, especially magnetic-field-based logic, shows promise for surpassing the development limits of CMOS logic. Existing proposals of magnetic-field-based logic are based on exotic semiconductors and difficult for further technological implementation. We proposed a kind of diode-assisted geometry-enhanced low-magnetic-field magnetoresistance (MR) mechanism. It couples p-n junction's nonlinear transport characteristic and Lorentz force by geometry, and shows extremely large low-magnetic-field MR (>120% at 0.15 T) Further, it is applied to experimentally demonstrate current-controlled reconfigurable MR logic on the silicon platform at room temperature. This logic device could perform Boolean logic AND, OR, NAND and NOR in one device. Combined with non-volatile magnetic memory, this logic architecture has the advantages of current-controlled reconfiguration, zero refresh consumption, instant-on performance and would bridge the processor-memory gap.

  6. Robust Two-Qubit Gates for Donors in Silicon Controlled by Hyperfine Interactions

    NASA Astrophysics Data System (ADS)

    Kalra, Rachpon; Laucht, Arne; Hill, Charles D.; Morello, Andrea; CentreQuantum Computation; Communication Technology, Australia Team

    2015-03-01

    The electron spin of a single atom in silicon is an excellent candidate for the building-block of a quantum computer. Recent breakthrough experiments have shown an individual phosphorus impurity atom can be used to store and elaborate one bit of quantum information. To continue along this exciting path, it is necessary to couple multiple phosphorus atoms in a controllable way and demonstrate quantum logic operations between pairs of qubits. This was thought to require exquisite control of their mutual interaction, and atomically-precise placement of the spins. Our work shows that the nuclei, to which the electrons are bound, can be exploited to enable a logic operation based on selective resonant excitation. This operation has the enormous advantage that the inter-qubit interaction does not require any modification. Our calculations show that high-fidelity operations can be performed while tolerating a rather wide range of distances between atoms. This drastically reduces the demands posed on device fabrication, paving the way forward for large-scale quantum-information processing in silicon. Funded by the Australian Research Council (CE11E000127) and the U.S. Army Research Office (W911NF-13-1-0024).

  7. Precision envelope detector and linear rectifier circuitry

    DOEpatents

    Davis, Thomas J.

    1980-01-01

    Disclosed is a method and apparatus for the precise linear rectification and envelope detection of oscillatory signals. The signal is applied to a voltage-to-current converter which supplies current to a constant current sink. The connection between the converter and the sink is also applied through a diode and an output load resistor to a ground connection. The connection is also connected to ground through a second diode of opposite polarity from the diode in series with the load resistor. Very small amplitude voltage signals applied to the converter will cause a small change in the output current of the converter, and the difference between the output current and the constant current sink will be applied either directly to ground through the single diode, or across the output load resistor, dependent upon the polarity. Disclosed also is a full-wave rectifier utilizing constant current sinks and voltage-to-current converters. Additionally, disclosed is a combination of the voltage-to-current converters with differential integrated circuit preamplifiers to boost the initial signal amplitude, and with low pass filtering applied so as to obtain a video or signal envelope output.

  8. Children rectify inequalities for disadvantaged groups.

    PubMed

    Elenbaas, Laura; Killen, Melanie

    2016-08-01

    Children's decisions regarding the allocation of societal resources in the context of preexisting inequalities were investigated. African American and European American children ages 5 to 6 years (n = 91) and 10 to 11 years (n = 94) judged the acceptability of a medical resource inequality on the basis of race, allocated medical supplies, evaluated different resource allocation strategies, and completed a measure of status awareness based on race. With age, children were increasingly aware of wealth status disparities between African Americans and European Americans, and judged a medical resource inequality between groups more negatively. Further, with age, children rectified the resource inequality over perpetuating it, but only when African American children were disadvantaged. With age, children also referenced rights when reasoning about their judgments concerning the disadvantaged African American group. When European American children were disadvantaged, children did not systematically allocate more resources to one group over another. The results are discussed in terms of social inequalities, disadvantaged status, moral judgments, and intergroup attitudes. (PsycINFO Database Record PMID:27455190

  9. Nitrate-Dependent Control of Shoot K Homeostasis by the Nitrate Transporter1/Peptide Transporter Family Member NPF7.3/NRT1.5 and the Stelar K+ Outward Rectifier SKOR in Arabidopsis1[OPEN

    PubMed Central

    Drechsler, Navina; Zheng, Yue; Nobmann, Barbara; Rausch, Christine

    2015-01-01

    Root-to-shoot translocation and shoot homeostasis of potassium (K) determine nutrient balance, growth, and stress tolerance of vascular plants. To maintain the cation-anion balance, xylem loading of K+ in the roots relies on the concomitant loading of counteranions, like nitrate (NO3−). However, the coregulation of these loading steps is unclear. Here, we show that the bidirectional, low-affinity Nitrate Transporter1 (NRT1)/Peptide Transporter (PTR) family member NPF7.3/NRT1.5 is important for the NO3−-dependent K+ translocation in Arabidopsis (Arabidopsis thaliana). Lack of NPF7.3/NRT1.5 resulted in K deficiency in shoots under low NO3− nutrition, whereas the root elemental composition was unchanged. Gene expression data corroborated K deficiency in the nrt1.5-5 shoot, whereas the root responded with a differential expression of genes involved in cation-anion balance. A grafting experiment confirmed that the presence of NPF7.3/NRT1.5 in the root is a prerequisite for proper root-to-shoot translocation of K+ under low NO3− supply. Because the depolarization-activated Stelar K+ Outward Rectifier (SKOR) has previously been described as a major contributor for root-to-shoot translocation of K+ in Arabidopsis, we addressed the hypothesis that NPF7.3/NRT1.5-mediated NO3− translocation might affect xylem loading and root-to-shoot K+ translocation through SKOR. Indeed, growth of nrt1.5-5 and skor-2 single and double mutants under different K/NO3− regimes revealed that both proteins contribute to K+ translocation from root to shoot. SKOR activity dominates under high NO3− and low K+ supply, whereas NPF7.3/NRT1.5 is required under low NO3− availability. This study unravels nutritional conditions as a critical factor for the joint activity of SKOR and NPF7.3/NRT1.5 for shoot K homeostasis. PMID:26508776

  10. Maximal rectification ratios for idealized bi-segment thermal rectifiers

    PubMed Central

    Shih, Tien-Mo; Gao, Zhaojing; Guo, Ziquan; Merlitz, Holger; Pagni, Patrick J.; Chen, Zhong

    2015-01-01

    Thermal rectifiers whose forward heat fluxes are greater than reverse counterparts have been extensively studied. Here we have discovered, idealized, and derived the ultimate limit of such rectification ratios, which are partially validated by numerical simulations, experiments, and micro-scale Hamiltonian-oscillator analyses. For rectifiers whose thermal conductivities (κ) are linear with the temperature, this limit is simply a numerical value of 3. For those whose conductivities are nonlinear with temperatures, the maxima equal κmax/κmin, where two extremes denote values of the solid segment materials that can be possibly found or fabricated within a reasonable temperature range. Recommendations for manufacturing high-ratio rectifiers are also given with examples. Under idealized assumptions, these proposed rectification limits cannot be defied by any bi-segment thermal rectifiers. PMID:26238970

  11. 99. POWER DISTRIBUTION UNITS FOR BATTERIES AND RECTIFIERS, NORTHEAST SIDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    99. POWER DISTRIBUTION UNITS FOR BATTERIES AND RECTIFIERS, NORTHEAST SIDE OF LANDLINE INSTRUMENTATION ROOM (106), LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  12. Accurate control of oxygen level in cells during culture on silicone rubber membranes with application to stem cell differentiation.

    PubMed

    Powers, Daryl E; Millman, Jeffrey R; Bonner-Weir, Susan; Rappel, Michael J; Colton, Clark K

    2010-01-01

    Oxygen level in mammalian cell culture is often controlled by placing culture vessels in humidified incubators with a defined gas phase partial pressure of oxygen (pO(2gas)). Because the cells are consuming oxygen supplied by diffusion, a difference between pO(2gas) and that experienced by the cells (pO(2cell)) arises, which is maximal when cells are cultured in vessels with little or no oxygen permeability. Here, we demonstrate theoretically that highly oxygen-permeable silicone rubber membranes can be used to control pO(2cell) during culture of cells in monolayers and aggregates much more accurately and can achieve more rapid transient response following a disturbance than on polystyrene and fluorinated ethylene-propylene copolymer membranes. Cell attachment on silicone rubber was achieved by physical adsorption of fibronectin or Matrigel. We use these membranes for the differentiation of mouse embryonic stem cells to cardiomyocytes and compare the results with culture on polystyrene or on silicone rubber on top of polystyrene. The fraction of cells that are cardiomyocyte-like increases with decreasing pO(2) only when using oxygen-permeable silicone membrane-based dishs, which contract on silicone rubber but not polystyrene. The high permeability of silicone rubber results in pO(2cell) being equal to pO(2gas) at the tissue-membrane interface. This, together with geometric information from histological sections, facilitates development of a model from which the pO(2) distribution within the resulting aggregates is computed. Silicone rubber membranes have significant advantages over polystyrene in controlling pO(2cell), and these results suggest they are a valuable tool for investigating pO(2) effects in many applications, such as stem cell differentiation. PMID:20039374

  13. Wireless power transmission for biomedical implants: The role of near-zero threshold CMOS rectifiers.

    PubMed

    Mohammadi, Ali; Redoute, Jean-Michel; Yuce, Mehmet R

    2015-01-01

    Biomedical implants require an electronic power conditioning circuitry to provide a stable electrical power supply. The efficiency of wireless power transmission is strongly dependent on the power conditioning circuitry specifically the rectifier. A cross-connected CMOS bridge rectifier is implemented to demonstrate the impact of thresholds of rectifiers on wireless power transfer. The performance of the proposed rectifier is experimentally compared with a conventional Schottky diode full wave rectifier over 9 cm distance of air and tissue medium between the transmitter and receiver. The output voltage generated by the CMOS rectifier across a 1 KΩ resistive load is around twice as much as the Schottky rectifier. PMID:26737525

  14. Controlled Release of Dexamethasone From an Intravitreal Delivery System Using Porous Silicon Dioxide

    PubMed Central

    Hou, Huiyuan; Wang, Chengyun; Nan, Kaihui; Freeman, William R.; Sailor, Michael J.; Cheng, Lingyun

    2016-01-01

    Purpose The current study aims to evaluate a porous silicon-based drug delivery system meant for sustained delivery of dexamethasone (Dex) to the vitreous and retina. Methods Dexamethasone was grafted covalently into the pore walls of fully oxidized porous silicon particles (pSiO2-COO-Dex), which then was evaluated for the pharmacological effect of the payload on cultured ARPE19 cells before intravitreal injection. The Dex release profile was investigated in a custom designed dynamic dissolution chamber to mimic the turnover of vitreous fluid in rabbit eyes. Ocular safety, in vivo release, and pharmacodynamics were evaluated in rabbit eyes, and the human VEGF-induced rabbit retinal vascular permeability model. Results Loading efficiency of Dex was 69 ± 9 μg per 1 mg of the pSiO2-COO-Dex particles. Dynamic in vitro release demonstrated a sustained mode when compared to free Dex, with the drug half-life extended by 5 times. The released Dex was unaltered and biologically active. In vivo drug release in rabbit eyes revealed a mode similar to the release seen in vitro, with a vitreous half-life of 11 days. At 2 and 4 weeks after a single intravitreal injection of pSiO2-COO-Dex particles (mean 2.71 ± 0.47 mg), intravitreal 500 ng of VEGF did not induce significant retinal vessel dilation or fluorescein leakage, while these events were observed in the eyes injected with empty pSiO2 particles or with free Dex. The retinal vessel score from fluorescein angiography for the control eyes was double the score for the eyes injected with pSiO2-COO-Dex. No adverse reaction was observed for the eyes injected with drug-loaded pSi particles during the course of the study. Conclusions The porous silicon-based Dex delivery system (pSiO2-COO-Dex) can be administered safely into vitreous without toxicity. Dex release from the porous silicon particles was sustained for 2 months and was effective against VEGF-induced retinal vessel reaction. PMID:26882530

  15. Formation of composite polyacrylamide and silicone substrates for independent control of stiffness and strain

    PubMed Central

    Simmons, Chelsey S.; Ribeiro, Alexandre J. S.; Pruitt, Beth L.

    2013-01-01

    Cells that line major tissues in the body such as blood vessels, lungs and gastrointestinal tract experience deformation from mechanical strain with our heartbeat, breathing, and other daily activities. Tissues also remodel in both development and disease, changing their mechanical properties. Taken together, cells can experience vastly different mechanical cues resulting from the combination of these interdependent stimuli. To date, most studies of cellular mechanotransduction have been limited to assays in which variations in substrate stiffness and strain were not combined. Here, we address this technological gap by implementing a method that can simultaneously tune both substrate stiffness and mechanical strain. Substrate stiffness is controlled with different monomer and crosslinker ratios during polyacrylamide gel polymerization, and strain is transferred from the underlying silicone platform when stretched. We demonstrate this platform with polyacrylamide gels with elastic moduli at 6 kPa and 20 kPa in combination with two different silicone formulations. The gels remain attached with up to 50% applied strains. To validate strain transfer through the gels into cells, we employ particle-tracking methods and observe strain transmission via cell morphological changes. PMID:23287818

  16. Dopant and self-diffusion in extrinsic n-type silicon isotopically controlled heterostructures

    SciTech Connect

    Silvestri, Hughes H.; Sharp, Ian D.; Bracht, Hartmut A.; Nicols, Sam P.; Beeman, Jeff W.; Hansen, John; Nylandsted-Larsen, Arme; Haller, Eugene E.

    2002-04-01

    We present experimental results of dopant- and self-diffusion in extrinsic silicon doped with As. Multilayers of isotopically controlled {sup 28}Si and natural silicon enable simultaneous analysis of {sup 30}Si diffusion into the {sup 28}Si enriched layers and dopant diffusion throughout the multilayer structure. In order to suppress transient enhanced self- and dopant diffusion caused by ion implantation, we adopted a special approach to dopant introduction. First, an amorphous 250-nm thick Si layer was deposited on top of the Si isotope heterostructure. Then the dopant ions were implanted to a depth such that all the radiation damage resided inside this amorphous cap layer. These samples were annealed for various times and temperatures to study the impact of As diffusion and doping on Si self-diffusion. The Si self-diffusion coefficient and the dopant diffusivity for various extrinsic n-type conditions were determined over a wide temperature range. We observed increased diffusivities that we attribute to the increase in the concentration of the native defect promoting the diffusion.

  17. VSI-PWM rectifier/inverter system with a reduced switch count

    SciTech Connect

    Kim, G.T.; Lipo, T.A.

    1995-12-31

    A current controlled VSI-PWM rectifier and inverter with capacitor dc link is regarded as one of the most promising structures for three-phase to three-phase power conversion. This type of converter normally requires twelve switches for a rectifier and inverter composed of self turn-off switch such as a bi-polar transistor or IGBT with an antiparallel diode. In this paper, a new three-phase to three-phase converter for ac motor drives is proposed. The proposed converter employs only eight switches and has the capability of delivering sinusoidal input currents with unity power factor and bidirectional power flow. This paper describes the feasibility and the operational limitations of the proposed structure. A mathematical model of the system is derived using generalized modulation theory and experimental results for steady state and dynamic behavior are presented to verify the developed model.

  18. In situ nanoscale refinement by highly controllable etching of the (111) silicon crystal plane and its influence on the enhanced electrical property of a silicon nanowire

    NASA Astrophysics Data System (ADS)

    Yibin, Gong; Pengfei, Dai; Anran, Gao; Tie, Li; Ping, Zhou; Yuelin, Wang

    2011-12-01

    Nanoscale refinement on a (100) oriented silicon-on-insulator (SOI) wafer was introduced by using tetra-methyl-ammonium hydroxide (TMAH, 25 wt%) anisotropic silicon etchant, with temperature kept at 50 °C to achieve precise etching of the (111) crystal plane. Specifically for a silicon nanowire (SiNW) with oxide sidewall protection, the in situ TMAH process enabled effective size reduction in both lateral (2.3 nm/min) and vertical (1.7 nm/min) dimensions. A sub-50 nm SiNW with a length of microns with uniform triangular cross-section was achieved accordingly, yielding enhanced field effect transistor (FET) characteristics in comparison with its 100 nm-wide pre-refining counterpart, which demonstrated the feasibility of this highly controllable refinement process. Detailed examination revealed that the high surface quality of the (111) plane, as well as the bulk depletion property should be the causes of this electrical enhancement, which implies the great potential of the as-made cost-effective SiNW FET device in many fields.

  19. Microscopic control of 29Si nuclear spins near phosphorus donors in silicon

    NASA Astrophysics Data System (ADS)

    Järvinen, J.; Zvezdov, D.; Ahokas, J.; Sheludyakov, S.; Vainio, O.; Lehtonen, L.; Vasiliev, S.; Fujii, Y.; Mitsudo, S.; Mizusaki, T.; Gwak, M.; Lee, SangGap; Lee, Soonchil; Vlasenko, L.

    2015-09-01

    We demonstrate an efficient control of 29Si nuclear spins for specific lattice sites near 31P donors in silicon at temperatures below 1 K and in a high magnetic field of 4.6 T. Excitation of the forbidden electron-nuclear transitions leads to a pattern of well-resolved holes and peaks in the electron spin resonance (ESR) lines of 31P . The pattern originates from dynamic polarization (DNP) of the 29Si nuclear spins near the donors via the solid effect. DNP of 29Si is demonstrated also with the Overhauser effect where the allowed ESR transitions are excited. In this case mostly the remote 29Si nuclei having weak interaction with the donors are polarized, which results in a single hole and a sharp peak pair in the ESR spectrum. Our work shows that the solid effect can be used for initialization of 29Si nuclear spin qubits near the donors.

  20. Isolation and Control of Spins in Silicon Carbide with Millisecond-Coherence Times

    NASA Astrophysics Data System (ADS)

    Christle, David J.; Falk, Abram L.; Andrich, Paolo; Klimov, Paul V.; Awschalom, David D.; Hassan, Jawad Ul; Son, Nguyen T.; Janzén, Erik; Ohshima, Takeshi

    2015-03-01

    The elimination of defects from silicon carbide (SiC) has facilitated its move to the forefront of the optoelectronics and power-electronics industries. Nonetheless, because the electronic states of SiC defects can have sharp optical and spin transitions, they are increasingly recognized as a valuable resource for quantum-information and nanoscale-sensing applications. We demonstrate that individual electronic spin states of the divacancy defect in highly purified monocrystalline 4H-SiC can be isolated and coherently controlled. This defect has analogous behavior to the prominent nitrogen-vacancy center in diamond, yet exists in a material amenable to modern growth and microfabrication techniques. We spectroscopically identify the different forms of divacancies, and show that divacancy spins exhibit an exceptionally long ensemble Hahn-echo coherence time that exceeds one millisecond. Funding by NSF, AFOSR MURI, and the Knut & Alice Wallenberg Foundation is gratefully acknowledged.

  1. "Thunderstruck": Plasma-Polymer-Coated Porous Silicon Microparticles As a Controlled Drug Delivery System.

    PubMed

    McInnes, Steven J P; Michl, Thomas D; Delalat, Bahman; Al-Bataineh, Sameer A; Coad, Bryan R; Vasilev, Krasimir; Griesser, Hans J; Voelcker, Nicolas H

    2016-02-01

    Controlling the release kinetics from a drug carrier is crucial to maintain a drug's therapeutic window. We report the use of biodegradable porous silicon microparticles (pSi MPs) loaded with the anticancer drug camphothecin, followed by a plasma polymer overcoating using a loudspeaker plasma reactor. Homogenous "Teflon-like" coatings were achieved by tumbling the particles by playing AC/DC's song "Thunderstruck". The overcoating resulted in a markedly slower release of the cytotoxic drug, and this effect correlated positively with the plasma polymer coating times, ranging from 2-fold up to more than 100-fold. Ultimately, upon characterizing and verifying pSi MP production, loading, and coating with analytical methods such as time-of-flight secondary ion mass spectrometry, scanning electron microscopy, thermal gravimetry, water contact angle measurements, and fluorescence microscopy, human neuroblastoma cells were challenged with pSi MPs in an in vitro assay, revealing a significant time delay in cell death onset. PMID:26836366

  2. Interfacial Layer Control by Dry Cleaning Technology for Polycrystalline and Single Crystalline Silicon Growth.

    PubMed

    Im, Dong-Hyun; Kong-Soo Lee; Kang, Yoongoo; Jeong, Myoungho; Park, Kwang Wuk; Lee, Soon-Gun; Ma, Jin-Won; Kim, Youngseok; Kim, Bonghyun; Im, Ki-Vin; Lim, Hanjin; Lee, Jeong Yong

    2016-05-01

    Native oxide removal prior to poly-Si contact and epitaxial growth of Si is the most critical technology to ensure process and device performances of poly-Si plugs and selective epitaxial growth (SEG) layers for DRAM, flash memory, and logic device. Recently, dry cleaning process for interfacial oxide removal has attracted a world-wide attention due to its superior passivation properties to conventional wet cleaning processes. In this study, we investigated the surface states of Si substrate during and after dry cleaning process, and the role of atomic elements including fluorine and hydrogen on the properties of subsequent deposited silicon layer using SIMS, XPS, and TEM analysis. The controlling of residual fluorine on the Si surface after dry cleaning is a key factor for clean interface. The mechanism of native oxide re-growth caused by residual fluorine after dry cleaning is proposed based on analytical results. PMID:27483844

  3. Electrical control of interfacial trapping for magnetic tunnel transistor on silicon

    SciTech Connect

    Lu, Y. Lacour, D.; Lengaigne, G.; Le Gall, S.; Suire, S.; Montaigne, F.; Hehn, M.; Wu, M. W.

    2014-01-27

    We demonstrate an electrical control of an interfacial trapping effect for hot electrons injected in silicon by studying a magnetic tunnel transistor on wafer bonded Si substrate. Below 25 K, hot electrons are trapped at the Cu/Si interface, resulting in collector current suppression through scattering in both parallel and antiparallel magnetic configurations. Consequently, the magneto-current ratio strongly decreases from 300% at 27 K to 30% at 22 K. The application of a relatively small electric field (∼333 V/cm) across the Cu/Si interface is enough to strip the trapped electrons and restore the magneto-current ratio at low temperature. We also present a model taking into account the effects of both electric field and temperature that closely reproduces the experimental results and allows extraction of the trapping binding energy (∼1.6 meV)

  4. Large-area silica nanotubes with controllable geometry on silicon substrates

    NASA Astrophysics Data System (ADS)

    Hu, Mingzhe; Yu, Rong; MacManus-Driscoll, Judith L.; Robinson, Adam P.

    2009-01-01

    The synthesis of a highly uniform, large-scale nanoarrays consisting of silica nanotubes above embedded nanohole arrays in silicon substrates is demonstrated. In situ anodized aluminium oxide (AAO) thin film masks on Si substrates were employed, and the nanotubes were fabricated by Ar ion milling through the masks. The geometries of the nanoarrays, including pore diameter, interpore distance and the length of both nanopores and nanotubes could be controlled by the process parameters, which included that the outer pore diameter of silica tube was tuned from ˜80 nm to ˜135 nm while the inner tube diameter from ˜40 nm to ˜65 nm, the interpore distance of the nanotube arrays was from 100 nm to 180 nm and the length of silica tube changed from ˜90 nm to ˜250 nm. The presented nanostructure fabrication method has strong potential for application in intensity and frequency adjustable high luminescence efficiency optoelectronic devices.

  5. Controllable surface-plasmon resonance in engineered nanometer epitaxial silicide particles embedded in silicon

    NASA Technical Reports Server (NTRS)

    Fathauer, R. W.; Ksendzov, A.; Iannelli, J. M.; George, T.

    1991-01-01

    Epitaxial CoSi2 particles in a single-crystal silicon matrix are grown by molecular-beam epitaxy using a technique that allows nanometer control over particle size in three dimensions. These composite layers exhibit resonant absorption predicted by effective-medium theory. Selection of the height and diameter of disklike particles through a choice of growth conditions allows tailoring of the depolarization factor and hence of the surface-plasmon resonance energy. Resonant absorption from 0.49 to 1.04 eV (2.5 to 1.2 micron) is demonstrated and shown to agree well with values predicted by the Garnett (1904, 1906) theory using the bulk dielectric constants for CoSi2 and Si.

  6. High-fidelity readout and control of a nuclear spin qubit in silicon.

    PubMed

    Pla, Jarryd J; Tan, Kuan Y; Dehollain, Juan P; Lim, Wee H; Morton, John J L; Zwanenburg, Floris A; Jamieson, David N; Dzurak, Andrew S; Morello, Andrea

    2013-04-18

    Detection of nuclear spin precession is critical for a wide range of scientific techniques that have applications in diverse fields including analytical chemistry, materials science, medicine and biology. Fundamentally, it is possible because of the extreme isolation of nuclear spins from their environment. This isolation also makes single nuclear spins desirable for quantum-information processing, as shown by pioneering studies on nitrogen-vacancy centres in diamond. The nuclear spin of a (31)P donor in silicon is very promising as a quantum bit: bulk measurements indicate that it has excellent coherence times and silicon is the dominant material in the microelectronics industry. Here we demonstrate electrical detection and coherent manipulation of a single (31)P nuclear spin qubit with sufficiently high fidelities for fault-tolerant quantum computing. By integrating single-shot readout of the electron spin with on-chip electron spin resonance, we demonstrate quantum non-demolition and electrical single-shot readout of the nuclear spin with a readout fidelity higher than 99.8 percent-the highest so far reported for any solid-state qubit. The single nuclear spin is then operated as a qubit by applying coherent radio-frequency pulses. For an ionized (31)P donor, we find a nuclear spin coherence time of 60 milliseconds and a one-qubit gate control fidelity exceeding 98 percent. These results demonstrate that the dominant technology of modern electronics can be adapted to host a complete electrical measurement and control platform for nuclear-spin-based quantum-information processing. PMID:23598342

  7. Room temperature coherent control of defect spin qubits in silicon carbide.

    PubMed

    Koehl, William F; Buckley, Bob B; Heremans, F Joseph; Calusine, Greg; Awschalom, David D

    2011-11-01

    Electronic spins in semiconductors have been used extensively to explore the limits of external control over quantum mechanical phenomena. A long-standing goal of this research has been to identify or develop robust quantum systems that can be easily manipulated, for future use in advanced information and communication technologies. Recently, a point defect in diamond known as the nitrogen-vacancy centre has attracted a great deal of interest because it possesses an atomic-scale electronic spin state that can be used as an individually addressable, solid-state quantum bit (qubit), even at room temperature. These exceptional quantum properties have motivated efforts to identify similar defects in other semiconductors, as they may offer an expanded range of functionality not available to the diamond nitrogen-vacancy centre. Notably, several defects in silicon carbide (SiC) have been suggested as good candidates for exploration, owing to a combination of computational predictions and magnetic resonance data. Here we demonstrate that several defect spin states in the 4H polytype of SiC (4H-SiC) can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin. Using optical and microwave techniques similar to those used with diamond nitrogen-vacancy qubits, we study the spin-1 ground state of each of four inequivalent forms of the neutral carbon-silicon divacancy, as well as a pair of defect spin states of unidentified origin. These defects are optically active near telecommunication wavelengths, and are found in a host material for which there already exist industrial-scale crystal growth and advanced microfabrication techniques. In addition, they possess desirable spin coherence properties that are comparable to those of the diamond nitrogen-vacancy centre. This makes them promising candidates for various photonic, spintronic and quantum information applications that merge quantum degrees of freedom with classical

  8. Beds of reconfigurable angled hairs rectify Stokes flows

    NASA Astrophysics Data System (ADS)

    Alvarado, Jose; Comtet, Jean; Hosoi, Anette Peko

    2015-11-01

    Biological tissues such as intestines, blood vessels, kidneys, and tongues are coated with beds of passive, elongated, hair-like protrusions such as microvilli, hyaluronans, primary cilia, and papillae. Stresses from fluid flows can bend deformable hairs, but this reconfiguration can in turn affect confined fluid flows. We investigate this elastoviscous coupling by developing a biomimetic model system of elastomer hair beds subject to shear-driven Stokes flows in a Taylor-Couette geometry. We characterize this system with a theoretical model which shows that reconfiguration of hair beds is controlled by a single elastoviscous number. Hair bending results in an apparent shear thinning because the hair tip lowers toward the base and thus widens the gap through which fluid flows. When hairs are cantilevered at an angle subnormal to the surface, flow against the grain bends hairs away from the base and thus narrows the gap. Beds of reconfigurable angled hairs can thus give rise to an asymmetric flow impedance at arbitrarily low Reynolds number and could therefore function as a microfluidic rectifier.

  9. Rectifying thermal fluctuations: Minimal pumping and Maxwell's demon

    NASA Astrophysics Data System (ADS)

    Mandal, Dibyendu

    Molecular complexes with movable components form the basis of nanoscale machines. Their inherent stochastic nature makes it a challenge to generate any controllable movement. Rather than fighting these fluctuations, one can utilize them by the periodic modulation of system parameters, or stochastic pumping. For the no-pumping theorem (NPT), which establishes minimal conditions for directed pumping, we present a simplified proof using an elementary graph theoretical construction. Motivated by recent experiments, we propose a new class of "hybrid" models combining elements of both the purely discrete and purely continuous descriptions prevalent in the field. We formulate the NPT in this hybrid framework to give a detailed justification of the original experiment observation. We also present an extension of the NPT to open stochastic systems. Next we consider the paradox of "Maxwell's demon," an imaginary intelligent being that rectifies thermal fluctuations in a manner that seems to violate the second law of thermodynamics. We present two exactly solvable, autonomous models that can reproduce the actions of the demon. Of necessity, both of these models write information on a memory device as part of their operation. By exposing their explicit, transparent mechanisms, our models offer simple paradigms to investigate the autonomous rectification of thermal fluctuations and the thermodynamics of information processing.

  10. Development of open air silicon deposition technology by silane-free atmospheric pressure plasma enhanced chemical transport under local ambient gas control

    NASA Astrophysics Data System (ADS)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2016-07-01

    Open air silicon deposition was performed by combining silane-free atmospheric pressure plasma-enhanced chemical transport and a newly developed local ambient gas control technology. The effect of air contamination on silicon deposition was investigated using a vacuum chamber, and the allowable air contamination level was confirmed to be 3 ppm. The capability of the local ambient gas control head was investigated numerically and experimentally. A safe and clean process environment with air contamination less than 1 ppm was achieved. Combining these technologies, a microcrystalline silicon film was deposited in open air, the properties of which were comparable to those of silicon films deposited in a vacuum chamber.

  11. An ultra-low-voltage rectifier for PE energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Jingmin, Wang; Zheng, Yang; Zhangming, Zhu; Yintang, Yang

    2016-02-01

    An ultra low voltage rectifier with high power conversion efficiency (PCE) for PE energy harvesting applications is presented in this paper. This is achieved by utilizing the DTMOS which the body terminal is connected to the gate terminal in a diode connected transistor. This implementation facilitates the rectifier with dynamic control over the threshold voltage. Moreover, we use input powered to take the place of output powered to reduce the power loss and thereby increasing the power conversion efficiency. Based on standard SMIC 0.18 μm CMOS technology, the simulation results show that the voltage conversion efficiency and the power conversion efficiency can reach up to 90.5% and 95.5% respectively, when the input voltage equals to 0.2 V @ 100 Hz with load resistance 50 kω. Input voltages with frequencies in the range of 10 Hz-1 kHz can be rectified. Project supported by the National Natural Science Foundation of China (Nos. 61234002, 61322405, 61306044, 61376033) and the National High-Tech Program of China (No. 2013AA014103).

  12. Stress control of silicon nitride films deposited by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Li, Dong-ling; Feng, Xiao-fei; Wen, Zhi-yu; Shang, Zheng-guo; She, Yin

    2016-07-01

    Stress controllable silicon nitride (SiNx) films deposited by plasma enhanced chemical vapor deposition (PECVD) are reported. Low stress SiNx films were deposited in both high frequency (HF) mode and dual frequency (HF/LF) mode. By optimizing process parameters, stress free (-0.27 MPa) SiNx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited SiNx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit (IC), micro-electro-mechanical systems (MEMS) and bio-MEMS.

  13. Role of silicone derivative plus onion extract gel in presternal hypertrophic scar protection: a prospective randomized, double blinded, controlled trial.

    PubMed

    Jenwitheesuk, Kamonwan; Surakunprapha, Palakorn; Jenwitheesuk, Kriangsak; Kuptarnond, Chusak; Prathanee, Sompop; Intanoo, Worawit

    2012-08-01

    Use of silicone derivative and onion extract had been reported in the prevention of hypertrophic scarring. Our experience showed the preventive use of silicone derivative plus onion extract gel on hypertrophic scars after median sternotomy. In a randomized, double blinded, placebo-controlled study, 60 patients after median sternotomy incisions were separated into two groups. All patients were treated either with silicone derivative plus onion extract gel (Cybele(®) scagel) or placebo gel twice daily for a total treatment period of 12 weeks. During each visit, pain and itching scores were graded by the patients and scar characteristics were observed by surgeons using the Vancouver scar scale. Pain and itch score values from patients' who applied silicone derivative plus onion extract gel was less than another group (P < 0·05). Pigmentation was significantly different between two groups (P < 0·05) and the reduction of scores on vascularity, pliability, height in treated group was not superior to the untreated group. No adverse events were reported by any of the patients. A silicone derivative plus onion extract gel is safe and effective for the preventing the hypertrophic scarring after median sternotomy. PMID:22168750

  14. Implementation of Statistical Process Control: Evaluating the Mechanical Performance of a Candidate Silicone Elastomer Docking Seal

    NASA Technical Reports Server (NTRS)

    Oravec, Heather Ann; Daniels, Christopher C.

    2014-01-01

    The National Aeronautics and Space Administration has been developing a novel docking system to meet the requirements of future exploration missions to low-Earth orbit and beyond. A dynamic gas pressure seal is located at the main interface between the active and passive mating components of the new docking system. This seal is designed to operate in the harsh space environment, but is also to perform within strict loading requirements while maintaining an acceptable level of leak rate. In this study, a candidate silicone elastomer seal was designed, and multiple subscale test articles were manufactured for evaluation purposes. The force required to fully compress each test article at room temperature was quantified and found to be below the maximum allowable load for the docking system. However, a significant amount of scatter was observed in the test results. Due to the stochastic nature of the mechanical performance of this candidate docking seal, a statistical process control technique was implemented to isolate unusual compression behavior from typical mechanical performance. The results of this statistical analysis indicated a lack of process control, suggesting a variation in the manufacturing phase of the process. Further investigation revealed that changes in the manufacturing molding process had occurred which may have influenced the mechanical performance of the seal. This knowledge improves the chance of this and future space seals to satisfy or exceed design specifications.

  15. Dynamic nuclear polarization of {sup 29}Si nuclei in isotopically controlled phosphorus doped silicon

    SciTech Connect

    Hayashi, Hiroshi; Itahashi, Tatsumasa; Itoh, Kohei M.; Vlasenko, Leonid S.; Vlasenko, Marina P.

    2009-07-15

    Dynamic nuclear polarization (DNP) of {sup 29}Si nuclei in isotopically controlled silicon single crystals with the {sup 29}Si isotope abundance f{sub 29Si} varied from 1.2% to 99.2% is reported. It was found that both the DNP enhancement and {sup 29}Si nuclear spin-lattice relaxation time under saturation of the electron paramagnetic resonance transitions of phosphorus donors increase with the decrease in the {sup 29}Si abundance. A remarkably large steady-state DNP enhancement, E{sup ss}=2680 which is comparable to the theoretical upper limit of 3310, has been achieved through the ''resolved'' solid effect that has been identified clearly in the f{sub 29Si}=1.2% sample. The DNP enhancement depends not only on the {sup 29}Si abundance but also on the electron spin-lattice relaxation time that can be controlled by temperature and/or illumination. The linewidth of {sup 29}Si NMR spectra after DNP shows a linear dependence on f{sub 29Si} for f{sub 29Si}{<=}10% and changes to a square-root dependence for f{sub 29Si}{>=}50%. Comparison of experimentally determined nuclear polarization time with nuclear spin diffusion coefficients indicates that the rate of DNP is limited by the polarization transfer rather than by spin diffusion.

  16. Vertically aligned crystalline silicon nanowires with controlled diameters for energy conversion applications: Experimental and theoretical insights

    SciTech Connect

    Razek, Sara Abdel; Swillam, Mohamed A.; Allam, Nageh K.

    2014-05-21

    Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters are fabricated via a metal-assisted chemical etching method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H{sub 2}O{sub 2} electrolytes. The fabricated SiNWs have diameters ranging from 117 to 650 nm and lengths from 8 to 18 μm. The optical measurements showed a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670 nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ∼670 nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ∼660 nm. The x-ray diffraction patterns confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse band toward lower frequencies compared to that usually seen for c-Si. Finite difference time domain simulations have been performed to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results showed good agreement with the experimental results for the SiNWs of different diameters.

  17. Single C59N molecule as a molecular rectifier.

    PubMed

    Zhao, Jin; Zeng, Changgan; Cheng, Xin; Wang, Kedong; Wang, Guanwu; Yang, Jinlong; Hou, J G; Zhu, Qingshi

    2005-07-22

    We report a new kind of experimental realization of a molecular rectifier, which is based on a single azafullerene C59N molecule in a double-barrier tunnel junction via the single electron tunneling effect. An obvious rectifying effect is observed. The positive onset voltage is about 0.5-0.7 V, while the negative onset voltage is about 1.6-1.8 V. Theoretical analyses show that the half-occupied molecular orbital of the C59N molecule and the asymmetric shift of the molecular Fermi level when the molecule is charged are responsible for the molecular rectification. PMID:16090819

  18. Tunable electronic transport properties of silicon-fullerene-linked nanowires: Semiconductor, conducting wire, and tunnel diode

    NASA Astrophysics Data System (ADS)

    Nishio, Kengo; Ozaki, Taisuke; Morishita, Tetsuya; Mikami, Masuhiro

    2010-03-01

    We explore the possibility of controllable tuning of the electronic transport properties of silicon-fullerene-linked nanowires by encapsulating guest atoms into their cages. Our first-principles calculations demonstrate that the guest-free nanowires are semiconductors, and do not conduct electricity. The iodine or sodium doping improves the transport properties, and makes the nanowires metallic. In the junctions of I-doped and Na-doped NWs, the current travels through the boundary by quantum tunneling. More significantly, the junctions have asymmetric I-Vb curves, which could be used as rectifiers. The current-voltage curves are interpreted by band-overlapping models. Tunable electronic transport properties of silicon-fullerene-linked nanowires could find many applications such as field-effect transistors, conducting wires, and tunnel diodes.

  19. Numerically controlled atmospheric-pressure plasma sacrificial oxidation using electrode arrays for improving silicon-on-insulator layer uniformity

    NASA Astrophysics Data System (ADS)

    Takei, Hiroyasu; Yoshinaga, Keinosuke; Matsuyama, Satoshi; Yamauchi, Kazuto; Sano, Yasuhisa

    2015-01-01

    Silicon-on-insulator (SOI) wafers are important semiconductor substrates in high-performance devices. In accordance with device miniaturization requirements, ultrathin and highly uniform top silicon layers (SOI layers) are required. A novel method involving numerically controlled (NC) atmospheric-pressure plasma sacrificial oxidation using an electrode array system was developed for the effective fabrication of an ultrathin SOI layer with extremely high uniformity. Spatial resolution and oxidation properties are the key factors controlling ultraprecision machining. The controllability of plasma oxidation and the oxidation properties of the resulting experimental electrode array system were examined. The results demonstrated that the method improved the thickness uniformity of the SOI layer over one-sixth of the area of an 8-in. wafer area.

  20. PLGA-Mesoporous Silicon Microspheres for the in Vivo Controlled Temporospatial Delivery of Proteins.

    PubMed

    Minardi, Silvia; Pandolfi, Laura; Taraballi, Francesca; De Rosa, Enrica; Yazdi, Iman K; Liu, Xeuwu; Ferrari, Mauro; Tasciotti, Ennio

    2015-08-01

    In regenerative medicine, the temporospatially controlled delivery of growth factors (GFs) is crucial to trigger the desired healing mechanisms in the target tissues. The uncontrolled release of GFs has been demonstrated to cause severe side effects in the surrounding tissues. The aim of this study was to optimize a translational approach for the fine temporal and spatial control over the release of proteins, in vivo. Hence, we proposed a newly developed multiscale composite microsphere based on a core consisting of the nanostructured silicon multistage vector (MSV) and a poly(dl-lactide-co-glycolide) acid (PLGA) outer shell. Both of the two components of the resulting composite microspheres (PLGA-MSV) can be independently tailored to achieve multiple release kinetics contributing to the control of the release profile of a reporter protein in vitro. The influence of MSV shape (hemispherical or discoidal) and size (1, 3, or 7 μm) on PLGA-MSV's morphology and size distribution was investigated. Second, the copolymer ratio of the PLGA used to fabricate the outer shell of PLGA-MSV was varied. The composites were fully characterized by optical microscopy, scanning electron microscopy, ζ potential, Fourier transform infrared spectroscopy, and thermogravimetric analysis-differential scanning calorimetry, and their release kinetics over 30 days. PLGA-MSV's biocompatibility was assessed in vitro with J774 macrophages. Finally, the formulation of PLGA-MSV was selected, which concurrently provided the most consistent microsphere size and allowed for a zero-order release kinetic. The selected PLGA-MSVs were injected in a subcutaneous model in mice, and the in vivo release of the reporter protein was followed over 2 weeks by intravital microscopy, to assess if the zero-order release was preserved. PLGA-MSV was able to retain the payload over 2 weeks, avoiding the initial burst release typical of most drug delivery systems. Finally, histological evaluation assessed the

  1. 35 GHz integrated circuit rectifying antenna with 33 percent efficiency

    NASA Astrophysics Data System (ADS)

    Yoo, T.-W.; Chang, K.

    1991-11-01

    A 35 GHz integrated circuit rectifying antenna (rectenna) has been developed using a microstrip dipole antenna and beam-lead mixer diode. Greater than 33 percent conversion efficiency has been achieved. The circuit should have applications in microwave/millimeter-wave power transmission and detection.

  2. 37. VIEW OF SIX GAP ROTARY RECTIFIER FOR MAINTAINING CORONA ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. VIEW OF SIX GAP ROTARY RECTIFIER FOR MAINTAINING CORONA DISCHARGE IN THE COTTRELL ELECTROSTATIC GENERATORS. THE SYSTEM WAS CAPABLE OF PROVIDING 88,000 VOLTS TO THE ELECTRODES WITHIN THE PRECIPITATOR CHAMBER THE UNIT WAS LOCATED TO THE REAR OF BOILER 904 IN AN ENCLOSED ROOM. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

  3. 125. JOB NO. LINE 5044, INTERNATIONAL RECTIFIER CORP., RACHELLE LABORATORIES, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    125. JOB NO. LINE 5044, INTERNATIONAL RECTIFIER CORP., RACHELLE LABORATORIES, INC., LONG BEACH, CA, BY J.C. FULTON, SEPTEMBER 1982, LINE 5044, CLIFTON AND CO., ON FILE ENGINEERS DEPARTMENT, PORT OF LONG BEACH - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  4. Comparison of Rectified and Unrectified Sockets for Transtibial Amputees

    PubMed Central

    Engsberg, Jack R.; Sprouse, S. Wayne; Uhrich, Mary L.; Ziegler, Barbara R.; Luitjohan, F. Daniel

    2008-01-01

    The current method for fabricating prosthetic sockets is to modify a positive mold to account for the non-homogeneity of the residual limb to tolerate load (i.e., rectified socket). We tested unrectified sockets by retaining the shape of the residual limb, except for a distal end pad, using an alginate gel process instead of casting. This investigation compared rectified and unrectified sockets. Forty-three adults with unilateral transtibial amputations were tested after randomly wearing both rectified and unrectified sockets for at least 4 weeks. Testing included a gait analysis, energy expenditure and Prosthesis Evaluation Questionnaire (PEQ). Results indicated no differences between sockets for gait speed and timing, gait kinematics and kinetics, and gait energy expenditure. There were also no differences in the Prosthetic Evaluation Questionnaire and 16 subjects selected the rectified socket, 25 selected the unrectified socket, and 2 subjects selected to use both sockets as their exit socket. Results seemed to indicate that more than one paradigm exists for shaping prosthetic sockets, and this paradigm may be helpful in understanding the mechanisms of socket fit. The alginate gel fabrication method was simpler than the traditional method. The method could be helpful in other countries where prosthetic care is lacking, may be helpful with new amputees, and may be helpful in typical clinics to reduce costs and free the prosthetist to focus more time on patient needs. PMID:18776945

  5. 46 CFR 120.360 - Semiconductor rectifier systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Semiconductor rectifier systems. 120.360 Section 120.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150 PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS ELECTRICAL INSTALLATION Power Sources and Distribution Systems...

  6. 35 GHz integrated circuit rectifying antenna with 33 percent efficiency

    NASA Technical Reports Server (NTRS)

    Yoo, T.-W.; Chang, K.

    1991-01-01

    A 35 GHz integrated circuit rectifying antenna (rectenna) has been developed using a microstrip dipole antenna and beam-lead mixer diode. Greater than 33 percent conversion efficiency has been achieved. The circuit should have applications in microwave/millimeter-wave power transmission and detection.

  7. Controllable light-induced conic structures in silicon nanowire arrays by metal-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Zhang, Shenli; Wang, Xinwei; Liu, Hong; Shen, Wenzhong

    2014-01-01

    Silicon nanowires (SiNWs) have long been considered a promising material due to their extraordinary electrical and optical properties. As a simple, highly efficient fabrication method for SiNWs, metal-assisted chemical etching (MACE) has been intensively studied over recent years. However, effective control by modulation of simple parameters is still a challenging topic and some key questions still remain in the mechanistic processes. In this work, a novel method to manipulate SiNWs with a light-modulated MACE process has been systematically investigated. Conic structures consisting of inclined and clustered SiNWs can be generated and effectively modified by the incident light while new patterns such as ‘bamboo shoot’ arrays can also be formed under certain conditions. More importantly, detailed study has revealed a new top-down ‘diverting etching’ model of the conic structures in this process, different from the previously proposed ‘bending’ model. As a consequence of this mechanism, preferential lateral mass transport of silver particles occurs. Evidence suggests a relationship of this phenomenon to the inhomogeneous distribution of the light-induced electron-hole pairs beneath the etching front. Study on the morphological change and related mechanism will hopefully open new routes to understand and modulate the formation of SiNWs and other nanostructures.

  8. Interface control and mechanical property improvements in silicon carbide/titanium composites

    NASA Technical Reports Server (NTRS)

    Brewer, W. D.; Unnam, J.

    1982-01-01

    Several composite systems made of titanium matrix reinforced with silicon carbide fiber were investigated to obtain a better understanding of composite-degradation mechanisms and to develop techniques to minimize loss of mechanical properties during fabrication and in service. Emphasis was on interface control by fiber or matrix coatings. X-ray diffraction studies on planar samples showed that the formation of titanium silicides was greatly inhibited by the presence of aluminum or Ti3A1 layers at the fiber-matrix interface, with the Ti3A1 being more effective in reducing the reactions. Fiber studies showed that coating the fiber with a 1-micron-thick layer of aluminum improved the as-fabricated strength of a stoichiometric SiC fiber and reduced the fiber degradation during exposure to composite-fabrication conditions. Applying an interfacial barrier by coating the matrix foils instead of the fibers was found to be an effective method for improving composite strength. Reducing the fabrication temperature also resulted in significant improvements in composite strengths. Good-quality, well-consolidated composites were fabricated at temperatures well below those currently used for SiC-Ti composite fabrication.

  9. Erbium-doped slot waveguides containing size-controlled silicon nanocrystals

    SciTech Connect

    Hoffmann, R.; Beyer, J. Heitmann, J.; Klemm, V.; Rafaja, D.; Johnson, B. C.; McCallum, J. C.

    2015-04-28

    Silicon based slot waveguides with a slot containing Si nanocrystals (Si-nc) and Erbium ions (Er{sup 3+}) inside a silica matrix were prepared using sputter deposition and low-energy ion implantation. This sequence enabled independent optimization of nanocrystal formation and Er{sup 3+} incorporation parameters. Using a superlattice approach, the size of the Si-nc inside the slot could be controlled and optimized for maximum Er{sup 3+} luminescence yield at 1.54 μm. Er{sup 3+} is found to be efficiently pumped by Si-nc of sizes around 3 to 4 nm. Increasing Er{sup 3+} photoluminescence at 1.54 μm with increasing post-implantation annealing temperatures up to 1000 °C is attributed to annealing of matrix or Si-nc interface defects mainly. Additionally, a dependence of the Er{sup 3+} luminescence intensity on both the excitation and emission linear polarization orientation is shown, which demonstrates efficient field enhancement in sputtered slot waveguide structures.

  10. Silicon as Reducing Agent for Controlled Production of Plasmonic Copper Nanocomposite Glasses: A Spectroscopic Study

    NASA Astrophysics Data System (ADS)

    Jiménez, José A.

    2015-11-01

    The use of silicon to produce metal nanocomposite phosphate glasses with plasmonic properties is proposed. It is demonstrated how the reducing properties of Si powder allow for producing Cu nanocomposite glasses in a controlled manner during heat treatment (HT). Cu/Si-codoped glasses were prepared in a 50BaO-50P2O5 matrix by a simple melt-quench method in ambient atmosphere. The worst-case scenario is considered by having the noble metal introduced in its higher oxidation state as copper(II) oxide, i.e., instead of using monovalent copper. Optical absorption and photoluminescence (PL) spectroscopy, including emission decay dynamics, were employed for characterization of the melt-quenched glass, and for investigating the influence of HT on material optical properties. Remarkably, increasing amounts of Si powder were observed to suppress and ultimately remove the Cu2+ visible absorption band in the CuO-containing glasses. Moreover, subsequent HT of the glass with the highest Si content resulted in progressive development of the surface plasmon resonance of Cu nanoparticles with increasing holding time. PL spectroscopy analysis is further employed towards elucidating the Cu2+ → Cu+ → Cu0 valence state changes likely occurring during the melting and subsequent thermal processing.

  11. Photoresponse enhancement in graphene/silicon infrared detector by controlling photocarrier collection

    NASA Astrophysics Data System (ADS)

    Tang, Xin; Zhang, Hengkai; Tang, Xiaobing; Lai, King W. C.

    2016-07-01

    Graphene/silicon junction based photodetectors have attracted great interest due to their superior characteristics like large photosensitive area, fast photocarrier collection and low dark current. Currently, the weak optical absorption and short photocarrier lifetime of graphene remain major limitations for detection of infrared light with wavelengths above 1.2 μm. Here, we elucidate the mechanism of photocarrier transport in graphene/silicon junction based photodetector and propose a theoretical model to study the design and effect of finger-electrode structures on the photocurrent in graphene. We demonstrate that the top finger-like electrode in graphene/silicon photodetector can be designed to enhance the photocarrier collection efficiency in graphene by reducing the average transport distance of photocarriers. Therefore, the photoresponsivity of the graphene/silicon junction based photodetector can be increased. Our results have successfully demonstrated that by optimizing the design of finger electrodes, 4 times enhancement of photocurrents in graphene can be obtained at room temperature.

  12. Method of purifying metallurgical grade silicon employing reduced pressure atmospheric control

    NASA Technical Reports Server (NTRS)

    Ingle, W. M.; Thompson, S. W.; Chaney, R. E. (Inventor)

    1979-01-01

    A method in which a quartz tube is charged with chunks of metallurgical grade silicon and/or a mixture of such chunks and high purity quartz sand, and impurities from a class including aluminum, boron, as well as certain transition metals including nickel, iron, and manganese is described. The tube is then evacuated and heated to a temperature within a range of 800 C to 1400 C. A stream of gas comprising a reactant, such as silicon tetrafluoride, is continuously delivered at low pressures through the charge for causing a metathetical reaction of impurities of the silicon and the reactant to occur for forming a volatile halide and leaving a residue of silicon of an improved purity. The reactant which included carbon monoxide gas and impurities such as iron and nickel react to form volatile carbonyls.

  13. Control of silicon solidification and the impurities from an Al-Si melt

    NASA Astrophysics Data System (ADS)

    Wang, Panpan; Lu, Huimin; Lai, Yuanshi

    2014-03-01

    The investigation on purification of metallurgical grade silicon by solidification of hypereutectic Al-Si melt under the temperature gradient as an intensified separation way was carried out. Based on the available thermodynamic parameters and experimental data, the thermodynamic behavior and chemical composition of metallic impurities was studied in the solidification process. The principle for the silicon growth in the Al-Si melts was investigated. The results indicated that the refined silicon grains were successfully enriched at the top of the Al-Si alloy. Then the top part refined silicon was collected by aqua regia leaching. Electrorefining of the bottom part (Al-22%Si) was investigated effectively in view of recovering pure Si and Al. Additionally, according to previous investigation, the optimized technical process for SOG-Si production was proposed.

  14. Junction barrier Schottky rectifier with an improved P-well region

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Li, Ting; Cao, Fei; Shao, Lei; Chen, Yu-Xian

    2012-12-01

    A junction barrier Schottky (JBS) rectifier with an improved P-well on 4H—SiC is proposed to improve the VF—IR trade-off and the breakdown voltage. The reverse current density of the proposed JBS rectifier at 300 K and 800 V is about 3.3×10-8 times that of the common JBS rectifier at no expense of the forward voltage drop. This is because the depletion layer thickness in the P-well region at the same reverse voltage is larger than in the P+ grid, resulting in a lower spreading current and tunneling current. As a result, the breakdown voltage of the proposed JBS rectifier is over 1.6 kV, that is about 0.8 times more than that of the common JBS rectifier due to the uniform electric field. Although the series resistance of the proposed JBS rectifier is a little larger than that of the common JBS rectifier, the figure of merit (FOM) of the proposed JBS rectifier is about 2.9 times that of the common JBS rectifier. Based on simulating the values of susceptibility of the two JBS rectifiers to electrostatic discharge (ESD) in the human body model (HBM) circuits, the failure energy of the proposed JBS rectifier increases 17% compared with that of the common JBS rectifier.

  15. Parameter Plane Synthesis and Performance Investigation of a Three-Phase Three-Level Bidirectional Rectifier

    NASA Astrophysics Data System (ADS)

    Bhat, Abdul Hamid; Langer, Nitin

    2014-12-01

    In this paper, parameter plane synthesis of a three-phase neutral-point clamped bidirectional rectifier has been performed. The converter involves one outer-loop PI voltage controller and two inner-loop PI current controllers for the closed-loop control. D-partition technique has been employed for the precise design of the voltage controller. An experimental prototype of the converter has been developed, and the experimental investigation of the converter performance in closed loop has been carried out. DSP DS1104 of dSPACE has been used for real-time implementation of the designed controller. The converter gives a very good performance in steady state and dynamic state (for rectification as well as inversion modes of operation) using the designed controller parameters.

  16. Two-photon indirect optical injection and two-color coherent control in bulk silicon

    NASA Astrophysics Data System (ADS)

    Cheng, J. L.; Rioux, J.; Sipe, J. E.

    2011-12-01

    Using an empirical pseudopotential description of electron states and an adiabatic bond charge model for phonon states in bulk silicon, we theoretically investigate two-photon indirect optical injection of carriers and spins and two-color coherent control of the motion of the injected carriers and spins. For two-photon indirect carrier and spin injection, we identify the selection rules of band edge transitions, the injection in each conduction band valley, and the injection from each phonon branch at 4 and 300 K. At 4 K, the TA-phonon-assisted transitions dominate the injection at low photon energies and the TO-phonon-assisted transitions at high photon energies. At 300 K, the former dominates at all photon energies of interest. The carrier injection shows anisotropy and linear-circular dichroism with respect to the light propagation direction. For light propagating along the <001> direction, the carrier injection exhibits valley anisotropy, and the injection into the Z conduction band valley is larger than that into the X and Y valleys. For σ- light propagating along the <001> (<111>) direction, the degree of spin polarization gives a maximum value about 20% (6%) at 4 K and -10% (20%) at 300 K, and at both temperature shows abundant structure near the injection edges due to contributions from different phonon branches. For two-color coherent current injection with an incident optical field composed of a fundamental frequency and its second harmonic, the response tensors of the electron (hole) charge and spin currents are calculated at 4 and 300 K. We show the current control for three different polarization scenarios: For cocircularly polarized beams, the direction of the charge current and the polarization direction of the spin current can be controlled by a relative-phase parameter; for the collinearly and cross-linearly polarized beams, the current amplitude can be controlled by that parameter. The spectral dependence of the maximum swarm velocity shows that

  17. Process for the controlled growth of single-crystal films of silicon carbide polytypes on silicon carbide wafers

    NASA Technical Reports Server (NTRS)

    Larkin, David J. (Inventor); Powell, J. Anthony (Inventor)

    1992-01-01

    A method for the controlled growth of single-crystal semiconductor-device-quality films of SiC polytypes on vicinal (0001) SiC wafers with low tilt angles is presented. Both homoepitaxial and heteroepitaxial SiC films can be produced on the same wafer. In particular, 3C-SiC and 6H-SiC films can be produced within selected areas of the same 6H-SiC wafer.

  18. Process for the controlled growth of single-crystal films of silicon carbide polytypes on silicon carbide wafers

    NASA Technical Reports Server (NTRS)

    Powell, J. Anthony (Inventor)

    1991-01-01

    This invention is a method for the controlled growth of single-crystal semiconductor device quality films of SiC polytypes on vicinal (0001) SiC wafers with low tilt angles. Both homoepitaxial and heteroepitaxial SiC films can be produced on the same wafer. In particular, 3C-SiC and 6H-SiC films can be produced within selected areas of the same 6H-SiC wafer.

  19. Improving the stability of nanostructured silicon thin film lithium-ion battery anodes through their controlled oxidation.

    PubMed

    Abel, Paul R; Lin, Yong-Mao; Celio, Hugo; Heller, Adam; Mullins, C Buddie

    2012-03-27

    Silicon and partially oxidized silicon thin films with nanocolumnar morphology were synthesized by evaporative deposition at a glancing angle, and their performance as lithium-ion battery anodes was evaluated. The incorporated oxygen concentration was controlled by varying the partial pressure of water during the deposition and monitored by quartz crystal microbalance, X-ray photoelectron spectroscopy. In addition to bulk oxygen content, surface oxidation and annealing at low temperature affected the cycling stability and lithium-storage capacity of the films. By simultaneously optimizing all three, films of ~2200 mAh/g capacity were synthesized. Coin cells made with the optimized films were reversibly cycled for ~120 cycles with virtually no capacity fade. After 300 cycles, 80% of the initial reversible capacity was retained. PMID:22372404

  20. Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures

    NASA Astrophysics Data System (ADS)

    Hilali, Mohamed M.; Yang, Shuqiang; Miller, Mike; Xu, Frank; Banerjee, Sanjay; Sreenivasan, S. V.

    2012-10-01

    In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent.

  1. Size Control of Porous Silicon-Based Nanoparticles via Pore-Wall Thinning.

    PubMed

    Secret, Emilie; Leonard, Camille; Kelly, Stefan J; Uhl, Amanda; Cozzan, Clayton; Andrew, Jennifer S

    2016-02-01

    Photoluminescent silicon nanocrystals are very attractive for biomedical and electronic applications. Here a new process is presented to synthesize photoluminescent silicon nanocrystals with diameters smaller than 6 nm from a porous silicon template. These nanoparticles are formed using a pore-wall thinning approach, where the as-etched porous silicon layer is partially oxidized to silica, which is dissolved by a hydrofluoric acid solution, decreasing the pore-wall thickness. This decrease in pore-wall thickness leads to a corresponding decrease in the size of the nanocrystals that make up the pore walls, resulting in the formation of smaller nanoparticles during sonication of the porous silicon. Particle diameters were measured using dynamic light scattering, and these values were compared with the nanocrystallite size within the pore wall as determined from X-ray diffraction. Additionally, an increase in the quantum confinement effect is observed for these particles through an increase in the photoluminescence intensity of the nanoparticles compared with the as-etched nanoparticles, without the need for a further activation step by oxidation after synthesis. PMID:26796986

  2. The properties of polycrystalline silicon solar cells with controlled titanium additions

    NASA Technical Reports Server (NTRS)

    Rohatgi, A.; Hopkins, R. H.; Davis, J. R., Jr.

    1981-01-01

    By coupling the results of electrical measurements, such as spectral response, lighted and dark I-V determinations, and deep-level-transient spectroscopy with optical and laser scan photomicroscopy, the effects of grain boundaries and impurities on silicon solar cells were evaluated. Titanium, which produces two deep levels in silicon, degrades cell performance by reducing bulk lifetime and thus cell short-circuit current. Electrically active grain boundaries induce carrier recombination in the bulk and depletion regions of the solar cell. Experimental data imply a small but measurable segregation of titanium into some grain boundaries of the polycrystalline silicon containing high Ti concentration. However, for the titanium-contaminated polycrystalline material used in this study, solar cell performance is dominated by the electrically active titanium concentration in the grains. Microstructural impacts on the devices are of secondary importance

  3. Ultrafast optical control using the Kerr nonlinearity in hydrogenated amorphous silicon microcylindrical resonators

    PubMed Central

    Vukovic, N.; Healy, N.; Suhailin, F. H.; Mehta, P.; Day, T. D.; Badding, J. V.; Peacock, A. C.

    2013-01-01

    Microresonators are ideal systems for probing nonlinear phenomena at low thresholds due to their small mode volumes and high quality (Q) factors. As such, they have found use both for fundamental studies of light-matter interactions as well as for applications in areas ranging from telecommunications to medicine. In particular, semiconductor-based resonators with large Kerr nonlinearities have great potential for high speed, low power all-optical processing. Here we present experiments to characterize the size of the Kerr induced resonance wavelength shifting in a hydrogenated amorphous silicon resonator and demonstrate its potential for ultrafast all-optical modulation and switching. Large wavelength shifts are observed for low pump powers due to the high nonlinearity of the amorphous silicon material and the strong mode confinement in the microcylindrical resonator. The threshold energy for switching is less than a picojoule, representing a significant step towards advantageous low power silicon-based photonic technologies. PMID:24097126

  4. Electrical Control of g-Factor in a Few-Hole Silicon Nanowire MOSFET.

    PubMed

    Voisin, B; Maurand, R; Barraud, S; Vinet, M; Jehl, X; Sanquer, M; Renard, J; De Franceschi, S

    2016-01-13

    Hole spins in silicon represent a promising yet barely explored direction for solid-state quantum computation, possibly combining long spin coherence, resulting from a reduced hyperfine interaction, and fast electrically driven qubit manipulation. Here we show that a silicon-nanowire field-effect transistor based on state-of-the-art silicon-on-insulator technology can be operated as a few-hole quantum dot. A detailed magnetotransport study of the first accessible hole reveals a g-factor with unexpectedly strong anisotropy and gate dependence. We infer that these two characteristics could enable an electrically driven g-tensor-modulation spin resonance with Rabi frequencies exceeding several hundred mega-Hertz. PMID:26599868

  5. SiC MOSFET Based Single Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications

    SciTech Connect

    Onar, Omer C; Tang, Lixin; Chinthavali, Madhu Sudhan; Campbell, Steven L; Miller , John M.

    2014-01-01

    Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.

  6. Rectifying behaviour of spin coated pn hetero-junction

    SciTech Connect

    Yogamalar, N. Rajeswari; Bose, A. Chandra

    2015-06-24

    Rectifying pn hetero- junction is fabricated with an acceptor p-type organic semiconductor namely tetra- chloro dihydroxy tetra-iodo fluorescein (Rose Bengal (RB)) followed by an inorganic n-type ZnO semiconductor on indium tin oxide (ITO) substrate. The n-type ZnO films are formed by unintentional doping and doping with aluminium (Al) and yttrium (Y) donors. The surface morphology and the distribution of grains are observed from scanning electron microscopy (SEM) and atomic force microscopy (AFM). The current-voltage (I-V) characteristic of the rectifying diode is measured to characterize the junction properties. The I-V plots obtained from the hetero- junction with electric contact shows a diode characteristic different from that of an ideal behavior. The overall efficiency of the diode exhibits a greater dependency on the film crystallinity, carrier concentration, and reverse saturation current.

  7. Development of a Thermal Rectifier Usable at High Temperature

    NASA Astrophysics Data System (ADS)

    Takeuchi, Tsunehiro; Goto, Hiroki; Toyama, Yasuhiro; Itoh, Takashi; Mikami, Masashi

    2011-05-01

    By using Al-based metallic alloys characterized by a disordered structure and a narrow pseudogap of a few hundred meV in energy width persisting at the Fermi level, we succeeded in preparing materials possessing a large increase of thermal conductivity with increasing temperature. This unusual increase of thermal conductivity is caused by the electronic structure effect known as the bipolar diffusion effect (BDE) in the context of the two-band model. A thermal rectifier was constructed using materials exhibiting the BDE. By showing the thermal rectification of the bulk sample prepared in this study, we demonstrate that our newly proposed idea of a thermal rectifier using the BDE is applicable for practical use.

  8. Rectifying behaviour of spin coated pn hetero-junction

    NASA Astrophysics Data System (ADS)

    Yogamalar, N. Rajeswari; Bose, A. Chandra

    2015-06-01

    Rectifying pn hetero- junction is fabricated with an acceptor p-type organic semiconductor namely tetra- chloro dihydroxy tetra-iodo fluorescein (Rose Bengal (RB)) followed by an inorganic n-type ZnO semiconductor on indium tin oxide (ITO) substrate. The n-type ZnO films are formed by unintentional doping and doping with aluminium (Al) and yttrium (Y) donors. The surface morphology and the distribution of grains are observed from scanning electron microscopy (SEM) and atomic force microscopy (AFM). The current-voltage (I-V) characteristic of the rectifying diode is measured to characterize the junction properties. The I-V plots obtained from the hetero- junction with electric contact shows a diode characteristic different from that of an ideal behavior. The overall efficiency of the diode exhibits a greater dependency on the film crystallinity, carrier concentration, and reverse saturation current.

  9. Voltage-controlling mechanisms in low-resistivity silicon solar cells - A unified approach

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

    1986-01-01

    An experimental technique is used to determine the relative values of the base and emitter components of the dark saturation current of six types of high-voltage low-resistivity silicon solar cells. One of the surprising findings is the suggestion that the magnitude of the minority-carrier mobility may be process-dependent.

  10. High reliability megawatt transformer/rectifier

    NASA Technical Reports Server (NTRS)

    Zwass, Samuel; Ashe, Harry; Peters, John W.

    1991-01-01

    The goal of the two phase program is to develop the technology and design and fabricate ultralightweight high reliability DC to DC converters for space power applications. The converters will operate from a 5000 V dc source and deliver 1 MW of power at 100 kV dc. The power weight density goal is 0.1 kg/kW. The cycle to cycle voltage stability goals was + or - 1 percent RMS. The converter is to operate at an ambient temperature of -40 C with 16 minute power pulses and one hour off time. The uniqueness of the design in Phase 1 resided in the dc switching array which operates the converter at 20 kHz using Hollotron plasma switches along with a specially designed low loss, low leakage inductance and a light weight high voltage transformer. This approach reduced considerably the number of components in the converter thereby increasing the system reliability. To achieve an optimum transformer for this application, the design uses four 25 kV secondary windings to produce the 100 kV dc output, thus reducing the transformer leakage inductance, and the ac voltage stresses. A specially designed insulation system improves the high voltage dielectric withstanding ability and reduces the insulation path thickness thereby reducing the component weight. Tradeoff studies and tests conducted on scaled-down model circuits and using representative coil insulation paths have verified the calculated transformer wave shape parameters and the insulation system safety. In Phase 1 of the program a converter design approach was developed and a preliminary transformer design was completed. A fault control circuit was designed and a thermal profile of the converter was also developed.

  11. Crystal structure of the eukaryotic strong inward-rectifier K+ channel Kir2.2 at 3.1 A resolution.

    PubMed

    Tao, Xiao; Avalos, Jose L; Chen, Jiayun; MacKinnon, Roderick

    2009-12-18

    Inward-rectifier potassium (K+) channels conduct K+ ions most efficiently in one direction, into the cell. Kir2 channels control the resting membrane voltage in many electrically excitable cells, and heritable mutations cause periodic paralysis and cardiac arrhythmia. We present the crystal structure of Kir2.2 from chicken, which, excluding the unstructured amino and carboxyl termini, is 90% identical to human Kir2.2. Crystals containing rubidium (Rb+), strontium (Sr2+), and europium (Eu3+) reveal binding sites along the ion conduction pathway that are both conductive and inhibitory. The sites correlate with extensive electrophysiological data and provide a structural basis for understanding rectification. The channel's extracellular surface, with large structured turrets and an unusual selectivity filter entryway, might explain the relative insensitivity of eukaryotic inward rectifiers to toxins. These same surface features also suggest a possible approach to the development of inhibitory agents specific to each member of the inward-rectifier K+ channel family. PMID:20019282

  12. An Experimental Verification of a Simplified Five-Level PWM Rectifier with Twelve Switches for Use in High-Frequency Power Supply Systems

    NASA Astrophysics Data System (ADS)

    Noge, Yuichi; Itoh, Jun-Ichi

    In this paper evaluates a reduced switch count five-level PWM rectifier in a high frequency power supply system. The rectifier is combined a diode clump type topology with a flying capacitor type topology. Moreover, it uses only four switches per leg in spite of being a five-level converter. This paper describes the features of the proposed circuit topology and the corresponding methods of the high input frequency. Finally, the performance of the input current control of the proposed circuit is confirmed using the experimental setup. In addition, the operation of the proposed circuit at a high frequency of 800Hz is confirmed experimentally.

  13. Single-Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications

    SciTech Connect

    Chinthavali, Madhu Sudhan; Onar, Omer C; Miller, John M; Tang, Lixin

    2013-01-01

    Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance. To understand the power flow through the system this paper presents a novel approach to the system model and the impact of different control parameters on the load power. The implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation is also discussed.

  14. RF rectifiers for EM power harvesting in a Deep Brain Stimulating device.

    PubMed

    Hosain, Md Kamal; Kouzani, Abbas Z; Tye, Susannah; Kaynak, Akif; Berk, Michael

    2015-03-01

    A passive deep brain stimulation (DBS) device can be equipped with a rectenna, consisting of an antenna and a rectifier, to harvest energy from electromagnetic fields for its operation. This paper presents optimization of radio frequency rectifier circuits for wireless energy harvesting in a passive head-mountable DBS device. The aim is to achieve a compact size, high conversion efficiency, and high output voltage rectifier. Four different rectifiers based on the Delon doubler, Greinacher voltage tripler, Delon voltage quadrupler, and 2-stage charge pumped architectures are designed, simulated, fabricated, and evaluated. The design and simulation are conducted using Agilent Genesys at operating frequency of 915 MHz. A dielectric substrate of FR-4 with thickness of 1.6 mm, and surface mount devices (SMD) components are used to fabricate the designed rectifiers. The performance of the fabricated rectifiers is evaluated using a 915 MHz radio frequency (RF) energy source. The maximum measured conversion efficiency of the Delon doubler, Greinacher tripler, Delon quadrupler, and 2-stage charge pumped rectifiers are 78, 75, 73, and 76 % at -5 dBm input power and for load resistances of 5-15 kΩ. The conversion efficiency of the rectifiers decreases significantly with the increase in the input power level. The Delon doubler rectifier provides the highest efficiency at both -5 and 5 dBm input power levels, whereas the Delon quadrupler rectifier gives the lowest efficiency for the same inputs. By considering both efficiency and DC output voltage, the charge pump rectifier outperforms the other three rectifiers. Accordingly, the optimised 2-stage charge pumped rectifier is used together with an antenna to harvest energy in our DBS device. PMID:25600671

  15. Electronic transport properties of silicon clusters

    NASA Astrophysics Data System (ADS)

    Matsuura, Yukihito

    2016-02-01

    The electronic transport properties of silicon clusters were examined via theoretical calculations using the first-principles method. Additionally, p-type doping and n-type doping were analyzed by calculating conductance and current of boron- and phosphorus-doped silicon clusters. The p-type doping and n-type doping provided a new transmission peak at an energy level around the Fermi level to increase conductance. Furthermore, simultaneous boron and phosphorus doping resulted in noticeable rectifying characteristics, with the current drive in forward bias being three times higher than that in the reverse bias. A p-n junction was achieved even on a molecular scale.

  16. Design and implementation of a novel synchronous-rectifier forward converter with improved performance

    NASA Astrophysics Data System (ADS)

    Liu, Tian-Hua; Wang, Kuan-Sheng

    2010-08-01

    This article proposes two new methods for improving the performance of a synchronous-rectifier forward converter. A synchronous-rectifier converter produces a reverse current in the inductor due to the bidirectional characteristic of MOSFETs while the converter is turned off. This reverse current causes voltage spikes which may damage the power devices. This article proposes two methods to reduce the voltage spikes: method 1 and method 2. Method 1 uses the enable signal detection method. An enable signal is generated from the remote control of the system when the main power is turned off. Then, the proposed circuit of method 1 turns off the free-wheeling switch before the reverse current is produced. As a result, the voltage spike can be avoided. Method 2 uses a transformer winding to detect the turn-off time of the input power. Then, the circuit turns off the free-wheeling switch to break the resonant loop and end the reverse current. The cost analysis of method 1 and 2 is included. In addition, several experimental results are provided to validate the correctness and feasibility of the theoretical analysis.

  17. Process for fabricating device structures for real-time process control of silicon doping

    DOEpatents

    Weiner, Kurt H.

    2001-01-01

    Silicon device structures designed to allow measurement of important doping process parameters immediately after the doping step has occurred. The test structures are processed through contact formation using standard semiconductor fabrication techniques. After the contacts have been formed, the structures are covered by an oxide layer and an aluminum layer. The aluminum layer is then patterned to expose the contact pads and selected regions of the silicon to be doped. Doping is then performed, and the whole structure is annealed with a pulsed excimer laser. But laser annealing, unlike standard annealing techniques, does not effect the aluminum contacts because the laser light is reflected by the aluminum. Once the annealing process is complete, the structures can be probed, using standard techniques, to ascertain data about the doping step. Analysis of the data can be used to determine probable yield reductions due to improper execution of the doping step and thus provide real-time feedback during integrated circuit fabrication.

  18. Controlled release of theophylline from poly(vinyl alcohol) hydrogels/porous silicon nanostructured systems

    NASA Astrophysics Data System (ADS)

    Cervantes-Rincón, N.; Medellín-Rodríguez, F. J.; Escobar-Barrios, V. A.; Palestino, G.

    2013-03-01

    In this research, hybrid hydrogels of poly (vinyl alcohol)/ porous silicon (PSi)/theophylline were synthesized by the freezing and thawing method. We evaluated the influence of the synthesis parameters of the poly (vinyl alcohol) (PVA) hydrogels in relation to their ability to swell and drug released. The parameters studied (using an experimental design developed in Minitab 16) were the polymer concentration, the freezing temperature and the number of freezing/thawing (f/t) cycles. Nanostructured porous silicon particles (NsPSi) and theophylline were added within the polymer matrix to increase the drug charge and the polymer mechanical strength. The hybrid hydrogels were characterized by Infrared Spectroscopy Fourier Transform (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC), drug delivery kinetics were engineered according to the desired drug release schedule.

  19. Donor ionization in size controlled silicon nanocrystals: The transition from defect passivation to free electron generation

    NASA Astrophysics Data System (ADS)

    Crowe, I. F.; Papachristodoulou, N.; Halsall, M. P.; Hylton, N. P.; Hulko, O.; Knights, A. P.; Yang, P.; Gwilliam, R. M.; Shah, M.; Kenyon, A. J.

    2013-01-01

    We studied the photoluminescence spectra of silicon and phosphorus co-implanted silica thin films on (100) silicon substrates as a function of isothermal annealing time. The rapid phase segregation, formation, and growth dynamics of intrinsic silicon nanocrystals are observed, in the first 600 s of rapid thermal processing, using dark field mode X-TEM. For short annealing times, when the nanocrystal size distribution exhibits a relatively small mean diameter, formation in the presence of phosphorus yields an increase in the luminescence intensity and a blue shift in the emission peak compared with intrinsic nanocrystals. As the mean size increases with annealing time, this enhancement rapidly diminishes and the peak energy shifts further to the red than the intrinsic nanocrystals. These results indicate the existence of competing pathways for the donor electron, which depends strongly on the nanocrystal size. In samples containing a large density of relatively small nanocrystals, the tendency of phosphorus to accumulate at the nanocrystal-oxide interface means that ionization results in a passivation of dangling bond (Pb-centre) type defects, through a charge compensation mechanism. As the size distribution evolves with isothermal annealing, the density of large nanocrystals increases at the expense of smaller nanocrystals, through an Ostwald ripening mechanism, and the majority of phosphorus atoms occupy substitutional lattice sites within the nanocrystals. As a consequence of the smaller band-gap, ionization of phosphorus donors at these sites increases the free carrier concentration and opens up an efficient, non-radiative de-excitation route for photo-generated electrons via Auger recombination. This effect is exacerbated by an enhanced diffusion in phosphorus doped glasses, which accelerates silicon nanocrystal growth.

  20. Controlled Prelithiation of Silicon Monoxide for High Performance Lithium-Ion Rechargeable Full Cells.

    PubMed

    Kim, Hye Jin; Choi, Sunghun; Lee, Seung Jong; Seo, Myung Won; Lee, Jae Goo; Deniz, Erhan; Lee, Yong Ju; Kim, Eun Kyung; Choi, Jang Wook

    2016-01-13

    Despite the recent considerable progress, the reversibility and cycle life of silicon anodes in lithium-ion batteries are yet to be improved further to meet the commercial standards. The current major industry, instead, adopts silicon monoxide (SiOx, x ≈ 1), as this phase can accommodate the volume change of embedded Si nanodomains via the silicon oxide matrix. However, the poor Coulombic efficiencies (CEs) in the early period of cycling limit the content of SiOx, usually below 10 wt % in a composite electrode with graphite. Here, we introduce a scalable but delicate prelithiation scheme based on electrical shorting with lithium metal foil. The accurate shorting time and voltage monitoring allow a fine-tuning on the degree of prelithiation without lithium plating, to a level that the CEs in the first three cycles reach 94.9%, 95.7%, and 97.2%. The excellent reversibility enables robust full-cell operations in pairing with an emerging nickel-rich layered cathode, Li[Ni0.8Co0.15Al0.05]O2, even at a commercial level of initial areal capacity of 2.4 mAh cm(-2), leading to a full cell energy density 1.5-times as high as that of graphite-LiCoO2 counterpart in terms of the active material weight. PMID:26694703

  1. Novel synthetic methodology for controlling the orientation of zinc oxide nanowires grown on silicon oxide substrates.

    PubMed

    Cho, Jinhyun; Salleh, Najah; Blanco, Carlos; Yang, Sungwoo; Lee, Chul-Jin; Kim, Young-Woo; Kim, Jungsang; Liu, Jie

    2014-04-01

    This study presents a simple method to reproducibly obtain well-aligned vertical ZnO nanowire arrays on silicon oxide (SiOx) substrates using seed crystals made from a mixture of ammonium hydroxide (NH4OH) and zinc acetate (Zn(O2CCH3)2) solution. In comparison, high levels of OH(-) concentration obtained using NaOH or KOH solutions lead to incorporation of Na or K atoms into the seed crystals, destroying the c-axis alignment of the seeds and resulting in the growth of misaligned nanowires. The use of NH4OH eliminates the metallic impurities and ensures aligned nanowire growth in a wide range of OH(-) concentrations in the seed solution. The difference of crystalline orientations between NH4OH- and NaOH-based seeds is directly observed by lattice-resolved images and electron diffraction patterns using a transmission electron microscope (TEM). This study obviously suggests that metallic impurities incorporated into the ZnO nanocrystal seeds are one of the factors that generates the misaligned ZnO nanowires. This method also enables the use of silicon oxide substrates for the growth of vertically aligned nanowires, making ZnO nanostructures compatible with widely used silicon fabrication technology. PMID:24584438

  2. Rapid thermal processing of high-efficiency silicon solar cells with controlled in-situ annealing

    SciTech Connect

    Doshi, P.; Rohatgi, A.; Ropp, M.; Chen, Z.; Ruby, D.; Meier, D.L.

    1995-01-01

    Silicon solar cell efficiencies of 17.1%, 16.4%, 14.8%, and 14.9% have been achieved on FZ, Cz, multicrystalline (mc-Si), and dendritic web (DW) silicon, respectively, using simplified, cost-effective rapid thermal processing (RTP). These represent the highest reported efficiencies for solar cells processed with simultaneous front and back diffusion with no conventional high-temperature furnace steps. Appropriate diffusion temperature coupled with the added in-situ anneal resulted in suitable minority-carrier lifetime and diffusion profiles for high-efficiency cells. The cooling rate associated with the in-situ anneal can improve the lifetime and lower the reverse saturation current density (J{sub 0}), however, this effect is material and base resistivity specific. PECVD antireflection (AR) coatings provided low reflectance and efficient front surface and bulk defect passivation. Conventional cells fabricated on FZ silicon by furnace diffusions and oxidations gave an efficiency of 18.8% due to greater short wavelength response and lower J{sub 0}.

  3. Descending vasa recta endothelia express inward rectifier potassium channels.

    PubMed

    Cao, Chunhua; Lee-Kwon, Whaseon; Payne, Kristie; Edwards, Aurélie; Pallone, Thomas L

    2007-10-01

    Descending vasa recta (DVR) are capillary-sized microvessels that supply blood flow to the renal medulla. They are composed of contractile pericytes and endothelial cells. In this study, we used the whole cell patch-clamp method to determine whether inward rectifier potassium channels (K(IR)) exist in the endothelia, affect membrane potential, and modulate intracellular Ca(2+) concentration ([Ca(2+)](cyt)). The endothelium was accessed for electrophysiology by removing abluminal pericytes from collagenase-digested vessels. K(IR) currents were recorded using symmetrical 140 mM K(+) solutions that served to maximize currents and eliminate cell-to-cell coupling by closing gap junctions. Large, inwardly rectifying currents were observed at membrane potentials below the equilibrium potential for K(+). Ba(2+) potently inhibited those currents in a voltage-dependent manner, with affinity k = 0.18, 0.33, 0.60, and 1.20 microM at -160, -120, -80, and -40 mV, respectively. Cs(+) also blocked those currents with k = 20, 48, 253, and 1,856 microM at -160, -120, -80, and -40 mV, respectively. In the presence of 1 mM ouabain, increasing extracellular K(+) concentration from 5 to 10 mM hyperpolarized endothelial membrane potential by 15 mV and raised endothelial [Ca(2+)](cyt). Both the K(+)-induced membrane hyperpolarization and the [Ca(2+)](cyt) elevation were reversed by Ba(2+). Immunochemical staining verified that both pericytes and endothelial cells of DVR express K(IR)2.1, K(IR)2.2, and K(IR)2.3 subunits. We conclude that strong, inwardly rectifying K(IR)2.x isoforms are expressed in DVR and mediate K(+)-induced hyperpolarization of the endothelium. PMID:17670900

  4. Rectifying calibration error of Goldmann applanation tonometer is easy!

    PubMed

    Choudhari, Nikhil S; Moorthy, Krishna P; Tungikar, Vinod B; Kumar, Mohan; George, Ronnie; Rao, Harsha L; Senthil, Sirisha; Vijaya, Lingam; Garudadri, Chandra Sekhar

    2014-11-01

    Purpose: Goldmann applanation tonometer (GAT) is the current Gold standard tonometer. However, its calibration error is common and can go unnoticed in clinics. Its company repair has limitations. The purpose of this report is to describe a self-taught technique of rectifying calibration error of GAT. Materials and Methods: Twenty-nine slit-lamp-mounted Haag-Streit Goldmann tonometers (Model AT 900 C/M; Haag-Streit, Switzerland) were included in this cross-sectional interventional pilot study. The technique of rectification of calibration error of the tonometer involved cleaning and lubrication of the instrument followed by alignment of weights when lubrication alone didn't suffice. We followed the South East Asia Glaucoma Interest Group's definition of calibration error tolerance (acceptable GAT calibration error within ±2, ±3 and ±4 mm Hg at the 0, 20 and 60-mm Hg testing levels, respectively). Results: Twelve out of 29 (41.3%) GATs were out of calibration. The range of positive and negative calibration error at the clinically most important 20-mm Hg testing level was 0.5 to 20 mm Hg and -0.5 to -18 mm Hg, respectively. Cleaning and lubrication alone sufficed to rectify calibration error of 11 (91.6%) faulty instruments. Only one (8.3%) faulty GAT required alignment of the counter-weight. Conclusions: Rectification of calibration error of GAT is possible in-house. Cleaning and lubrication of GAT can be carried out even by eye care professionals and may suffice to rectify calibration error in the majority of faulty instruments. Such an exercise may drastically reduce the downtime of the Gold standard tonometer. PMID:25494251

  5. Silicon nanocrystals in SiN{sub x}/SiO{sub 2} hetero-superlattices: The loss of size control after thermal annealing

    SciTech Connect

    Zelenina, A. Zacharias, M.; Sarikov, A.; Zhigunov, D. M.; Weiss, C.; Zakharov, N.; Werner, P.; López-Conesa, L.; Peiró, F.

    2014-06-28

    Superlattices containing 3 nm thick silicon rich silicon nitride sublayers and 3 nm and 10 nm thick SiO{sub 2} barriers were prepared by plasma enhanced chemical vapor deposition. Despite the as-prepared samples represented a well-kept multilayer structure with smooth interfaces, the high temperature annealing resulted in the total destruction of multilayer structure in the samples containing 3 nm SiO{sub 2} barriers. Energy-filtered transmission electron microscopy images of these samples indicated a silicon nanoclusters formation with sizes of 2.5–12.5 nm, which were randomly distributed within the structure. Although in the sample with 10 nm SiO{sub 2} barriers some fragments of the multilayer structure could be still observed after thermal annealing, nevertheless, the formation of large nanocrystals with diameters up to 10 nm was confirmed by dark field transmission electron microscopy. Thus, in contrast to the previously published results, the expected size control of silicon nanocrystals was lost. According to the FTIR results, the thermal annealing of SiN{sub x}/SiO{sub 2} superlattices led to the formation of silicon nanocrystals in mostly oxynitride matrix. Annealed samples demonstrated a photoluminescence peak at 885 nm related to the luminescence of silicon nanocrystals, as confirmed by time-resolved photoluminescence measurements. The loss of nanocrystals size control is discussed in terms of the migration of oxygen atoms from the SiO{sub 2} barriers into the silicon rich silicon nitride sublayers. A thermodynamic mechanism responsible for this process is proposed. According to this mechanism, the driving force for the oxygen migration is the gain in the configuration entropy related to the relative arrangements of oxygen and nitrogen atoms.

  6. Silicone metalization

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2006-12-05

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  7. Silicone metalization

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2008-12-09

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  8. Electro-magnetic transport and rectifying property of Fe2.5Mn0.5O4/p-Si heterojunction

    NASA Astrophysics Data System (ADS)

    Aireddy, H.; Das, A. K.

    2016-05-01

    Fe2.5Mn0.5O4/p-Si heterojunction was fabricated using a pulsed laser deposition technique and investigated it's structural and electrical transport properties. The high-resolution transmission electron microscopy results reveal the formation of a polycrystalline film on silicon substrate. The heterojunction shows good rectifying property and giant negative junction magnetoresistance especially in reverse bias condition at room temperature. The origin of this giant negative junction magnetoresistance may be attributing to the injection of electrons to the majority spin-up band of the Fe2.5Mn0.5O4 film.

  9. Wavelength-controlled external-cavity laser with a silicon photonic crystal resonant reflector

    NASA Astrophysics Data System (ADS)

    Gonzalez-Fernandez, A. A.; Liles, Alexandros A.; Persheyev, Saydulla; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of an alternative design of external-cavity hybrid lasers consisting of a III-V Semiconductor Optical Amplifier with fiber reflector and a Photonic Crystal (PhC) based resonant reflector on SOI. The Silicon reflector comprises a polymer (SU8) bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and sidemode suppression ratio of more than 25 dB.

  10. Control of interface fracture in silicon nitride ceramics: influence of different rare earth elements

    SciTech Connect

    Sun, E.Y.; Becher, P.F.; Waters, S.B.; Hsueh, Chun-Hway; Plucknett, K.P.; Hoffmann, M.J.

    1996-10-01

    The toughness of self-reinforced silicon nitride ceramics is improved by enhancing crack deflection and crack bridging mechanisms. Both mechanisms rely on the interfacial debonding process between the elongated {Beta}-Si{sub 3}N{sub 4} grains and the intergranular amorphous phases. The various sintering additives used for densification may influence the interfacial debonding process by modifying the thermal and mechanical properties of the intergranular glasses, which will result in different residual thermal expansion mismatch stresses; and the atomic bonding structure across the {Beta}-Si{sub 3}N{sub 4} glass interface. Earlier studies indicated that self-reinforced silicon nitrides sintered with different rare earth additives and/or different Y{sub 2}O{sub 3}:AI{sub 2}0{sub 3} ratios could exhibit different fracture behavior that varied from intergranular to transgranular fracture. No studies have been conducted to investigate the influence of sintering additives on the interfacial fracture in silicon nitride ceramics. Because of the complexity of the material system and the extremely small scale, it is difficult to conduct quantitative analyses on the chemistry and stress states of the intergranular glass phases and to relate the results to the bulk properties. The influence of different sintering additives on the interfacial fracture behavior is assessed using model systems in which {Beta}-Si{sub 3}N{sub 4}whiskers are embedded in SIAIRE (RE: rare-earth) oxynitride glasses. By systematically varying the glass composition, the role of various rare-earth additives on interfacial fracture has been examined. Specifically, four different additives were investigated: Al{sub 2}0{sub 3}, Y{sub 2}0{sub 3}, La{sub 2}O{sub 3}, and Yb{sub 2}O{sub 3}. In addition, applying the results from the model systems, the R- curve behavior of self-reinforced silicon nitride ceramics sintered with different Y{sub 2}0{sub 3}:AI{sub 2}0{sub 3} ratios was characterized.

  11. Rectifying social inequalities in a resource allocation task.

    PubMed

    Elenbaas, Laura; Rizzo, Michael T; Cooley, Shelby; Killen, Melanie

    2016-10-01

    To investigate whether children rectify social inequalities in a resource allocation task, participants (N=185 African-American and European-American 5-6year-olds and 10-11year-olds) witnessed an inequality of school supplies between peers of different racial backgrounds. Assessments were conducted on how children judged the wrongfulness of the inequality, allocated new resources to racial ingroup and outgroup recipients, evaluated alternative allocation strategies, and reasoned about their decisions. Younger children showed ingroup favorability; their responses differed depending on whether they had witnessed their ingroup or an outgroup at a disadvantage. With age, children increasingly reasoned about the importance of equal access to school supplies and correcting past disparities. Older children judged the resource inequality negatively, allocated more resources to the disadvantaged group, and positively evaluated the actions of others who did the same, regardless of whether they had seen their racial ingroup or an outgroup at a disadvantage. Thus, balancing moral and social group concerns enabled individuals to rectify inequalities and ensure fair access to important resources regardless of racial group membership. PMID:27423813

  12. Etched profile control in anisotropic etching of silicon by TMAH+Triton

    NASA Astrophysics Data System (ADS)

    Pal, Prem; Gosálvez, M. A.; Sato, K.

    2012-06-01

    The adverse effect of mechanical agitation (magnetic bead stirring) as well as galvanic interaction between the evolving facets of the etch front on the amount of undercutting during anisotropic etching of Si{1 0 0} wafers in surfactant-added tetramethylammonium hydroxide (TMAH) is studied by etching different mask patterns in magnetically stirred and nonstirred solutions. Triton X-100, with formula C14H22O(C2H4O)n, where n = 9-10, is used as the surfactant. The stirring results conclude that the adsorption of the surfactant on the etched silicon surfaces is predominantly physical in nature rather than chemical (physisorption versus chemisorption). The proposed model to account for the galvanic interaction between the evolving facets indicates that the underlying chemical etching process can be significantly surpassed by the onset of an electrochemical etching contribution when the relative area of the exposed {1 0 0} surface becomes relatively small in comparison to that of the developed {1 1 1} sidewalls. This study is useful for engineering applications where surfactant-added TMAH is used for the fabrication of silicon MEMS structures that should contain negligible undercutting.

  13. Controlling the shape and gap width of silicon electrodes using local anodic oxidation and anisotropic TMAH wet etching

    NASA Astrophysics Data System (ADS)

    Rouhi, Jalal; Mahmud, Shahrom; Derita Hutagalung, Sabar; Naderi, Nima; Kakooei, Saeid; Johar Abdullah, Mat

    2012-06-01

    A simple method for fabricating silicon electrodes with various shapes and gap widths was designed using the special properties of anisotropic tetramethylammonium hydroxide (TMAH) wet etching and local anodic oxidation (LAO). A statistical system was used for the optimization of the parameters of the LAO process to facilitate a better understanding and precise analysis of the process. Analyses of the interaction effects among the significant factors of LAO showed that the relative humidity and applied voltage were interdependent. They had the strongest interaction effect on the dimensions of the oxide mask. TMAH with a concentration of 25% was used as an etchant solution in (1 0 0) silicon with a rectangular oxide mask. The observed undercutting at convex corners, tip shape of emitters and gap widths of electrodes were exactly consistent with theoretical studies. Combination of the LAO method and anisotropic TMAH wet etching was successfully used to fabricate Si nano-gap electrodes. This fabrication method of sharp and round tip emitters was simple, controllable and faster than common techniques. These results indicate that the method can be a new approach for studying the electrical properties of nano-gap electrodes.

  14. Highly sensitive silicon nanowire biosensor with novel liquid gate control for detection of specific single-stranded DNA molecules.

    PubMed

    Adam, Tijjani; Hashim, U

    2015-05-15

    The study demonstrates the development of a liquid-based gate-control silicon nanowire biosensor for detection of specific single-stranded DNA (ssDNA) molecules. The sensor was fabricated using conventional photolithography coupled with an inductively coupled plasma dry etching process. Prior to the application of DNA to the device, its linear response to pH was confirmed by serial dilution from pH 2 to pH 14. Then, the sensor surface was silanized and directly aminated with (3-aminopropyl) triethoxysilane to create a molecular binding chemistry for biofunctionalization. The resulting Si‒O‒Si‒ components were functionalized with receptor ssDNA, which interacted with the targeted ssDNA to create a field across the silicon nanowire and increase the current. The sensor shows selectivity for the target ssDNA in a linear range from target ssDNA concentrations of 100 pM to 25 nM. With its excellent detection capabilities, this sensor platform is promising for detection of specific biomarkers and other targeted proteins. PMID:25453738

  15. A novel solid-state thermal rectifier based on reduced graphene oxide.

    PubMed

    Tian, He; Xie, Dan; Yang, Yi; Ren, Tian-Ling; Zhang, Gang; Wang, Yu-Feng; Zhou, Chang-Jian; Peng, Ping-Gang; Wang, Li-Gang; Liu, Li-Tian

    2012-01-01

    Recently, manipulating heat transport by phononic devices has received significant attention, in which phonon--a heat pulse through lattice, is used to carry energy. In addition to heat control, the thermal devices might also have broad applications in the renewable energy engineering, such as thermoelectric energy harvesting. Elementary phononic devices such as diode, transistor and logic devices have been theoretically proposed. In this work, we experimentally create a macroscopic scale thermal rectifier based on reduced graphene oxide. Obvious thermal rectification ratio up to 1.21 under 12 K temperature bias has been observed. Moreover, this ratio can be enhanced further by increasing the asymmetric ratio. Collectively, our results raise the exciting prospect that the realization of macroscopic phononic device with large-area graphene based materials is technologically feasible, which may open up important applications in thermal circuits and thermal management. PMID:22826801

  16. Rectifying filamentary resistive switching in ion-exfoliated LiNbO3 thin films

    NASA Astrophysics Data System (ADS)

    Pan, Xinqiang; Shuai, Yao; Wu, Chuangui; Luo, Wenbo; Sun, Xiangyu; Zeng, Huizhong; Zhou, Shengqiang; Böttger, Roman; Ou, Xin; Mikolajick, Thomas; Zhang, Wanli; Schmidt, Heidemarie

    2016-01-01

    In this letter, we report the resistive switching properties of ion-exfoliated LiNbO3 thin films. After annealing in Ar or in vacuum, electro-forming has been observed on the thin films, and the oxygen gas bubbles can be eliminated by tuning the annealing conditions in order to prevent the destruction of top electrodes. The thin films show rectifying filamentary resistive switching after forming, which is interpreted by a simplified model that the local filament does not penetrate throughout the LiNbO3 thin film, resulting in asymmetric contact barriers at the two interfaces. The well controlled electro-forming step and the highly reproducible switching properties are attributed to the more homogeneous distribution of defects in single crystalline materials and the specific geometry of filament.

  17. Logical Stochastic Resonance with a Coulomb-Coupled Quantum-Dot Rectifier

    NASA Astrophysics Data System (ADS)

    Pfeffer, P.; Hartmann, F.; Höfling, S.; Kamp, M.; Worschech, L.

    2015-07-01

    Noise is mostly considered to be an adverse factor in electronics. Yet, effects like logical stochastic resonance (LSR) can render electronic fluctuations useful. Here, we study LSR in a system consisting of two Coulomb-coupled quantum dots (QDs). We observe that voltage fluctuations applied to one of the QDs lead to a rectified and controllable current in the other QD. The interplay between applied noise and gate voltages enables our system to offer logic and, or, nand, and nor gate functionalities, which can be switched by either a variation of the noise or of a single gate voltage. For an optimal amount of noise, all four functionalities can be toggled by changing solely one single gate voltage. The presented results may prove beneficial for future autonomous, noise-tolerant, and energy-efficient electronics.

  18. High-stroke silicon-on-insulator MEMS nanopositioner: Control design for non-raster scan atomic force microscopy

    SciTech Connect

    Maroufi, Mohammad Fowler, Anthony G. Bazaei, Ali Moheimani, S. O. Reza

    2015-02-15

    A 2-degree of freedom microelectromechanical systems nanopositioner designed for on-chip atomic force microscopy (AFM) is presented. The device is fabricated using a silicon-on-insulator-based process and is designed as a parallel kinematic mechanism. It contains a central scan table and two sets of electrostatic comb actuators along each orthogonal axis, which provides displacement ranges greater than ±10 μm. The first in-plane resonance modes are located at 1274 Hz and 1286 Hz for the X and Y axes, respectively. To measure lateral displacements of the stage, electrothermal position sensors are incorporated in the design. To facilitate high-speed scans, the highly resonant dynamics of the system are controlled using damping loops in conjunction with internal model controllers that enable accurate tracking of fast sinusoidal set-points. To cancel the effect of sensor drift on controlled displacements, washout controllers are used in the damping loops. The feedback controlled nanopositioner is successfully used to perform several AFM scans in contact mode via a Lissajous scan method with a large scan area of 20 μm × 20 μm. The maximum scan rate demonstrated is 1 kHz.

  19. High-stroke silicon-on-insulator MEMS nanopositioner: control design for non-raster scan atomic force microscopy.

    PubMed

    Maroufi, Mohammad; Fowler, Anthony G; Bazaei, Ali; Moheimani, S O Reza

    2015-02-01

    A 2-degree of freedom microelectromechanical systems nanopositioner designed for on-chip atomic force microscopy (AFM) is presented. The device is fabricated using a silicon-on-insulator-based process and is designed as a parallel kinematic mechanism. It contains a central scan table and two sets of electrostatic comb actuators along each orthogonal axis, which provides displacement ranges greater than ±10 μm. The first in-plane resonance modes are located at 1274 Hz and 1286 Hz for the X and Y axes, respectively. To measure lateral displacements of the stage, electrothermal position sensors are incorporated in the design. To facilitate high-speed scans, the highly resonant dynamics of the system are controlled using damping loops in conjunction with internal model controllers that enable accurate tracking of fast sinusoidal set-points. To cancel the effect of sensor drift on controlled displacements, washout controllers are used in the damping loops. The feedback controlled nanopositioner is successfully used to perform several AFM scans in contact mode via a Lissajous scan method with a large scan area of 20 μm × 20 μm. The maximum scan rate demonstrated is 1 kHz. PMID:25725850

  20. Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

    SciTech Connect

    Lee, Seok Woo; Lee, Hyun -Wook; Ryu, Ill; Nix, William D.; Gao, Huajian; Cui, Yi

    2015-06-26

    Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Here, we demonstrate physical and mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of lithiated Si by lessening the tensile stress concentrations in Si structures. Lastly, this study will contribute to improved design of Si structures at the electrode level for high-performance Li-ion batteries.

  1. Voltage controlling mechanisms in low resistivity silicon solar cells - A unified approach

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

    1984-01-01

    An experimental technique capable of resolving the dark saturation current into its base and emitter components is used as the basis of an analysis in which the voltage limiting mechanisms were determined for a variety of high voltage, low resistivity silicon solar cells. The cells studied include the University of Florida hi-low emitter cell, the NASA and the COMSAT multi-step diffused cells, the Spire Corporation ion-implanted emitter cell, and the University of New South Wales MINMIS and MINP cells. The results proved to be, in general, at variance with prior expectations. Most surprising was the finding that the MINP and the MINMIS voltage improvements are due, to a considerable extent, to a previously unrecognized optimization of the base component of the saturation current. This result is substantiated by an independent analysis of the material used to fabricate these devices.

  2. Voltage controlling mechanisms in low resistivity silicon solar cells: A unified approach

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

    1984-01-01

    An experimental technique capable of resolving the dark saturation current into its base and emitter components is used as the basis of an analysis in which the voltage limiting mechanisms were determined for a variety of high voltage, low resistivity silicon solar cells. The cells studied include the University of Florida hi-low emitter cell, the NASA and the COMSAT multi-step diffused cells, the Spire Corporation ion-implanted emitter cell, and the University of New South Wales MINMIS and MINP cells. The results proved to be, in general, at variance with prior expectations. Most surprising was the finding that the MINP and the MINMIS voltage improvements are due, to a considerable extent, to a previously unrecognized optimization of the base component of the saturation current. This result is substantiated by an independent analysis of the material used to fabricate these devices.

  3. Nuclear magnetic resonance linewidth and spin diffusion in {sup 29}Si isotopically controlled silicon

    SciTech Connect

    Hayashi, Hiroshi; Itoh, Kohei M.; Vlasenko, Leonid S.

    2008-10-15

    A nuclear magnetic resonance (NMR) study was performed with n-type silicon single crystals containing {sup 29}Si isotope abundance f ranges from 1.2% to 99.2%. The nuclear spin diffusion coefficient D has been determined from the linewidth of significantly enhanced {sup 29}Si NMR signals utilizing a developed dynamic nuclear polarization (DNP) method. The {sup 29}Si NMR linewidth depends linearly on f, at least when f<10%, and approaches {proportional_to}f{sup 1/2} dependence when f>50%. The estimated {sup 29}Si nuclear spin diffusion time T{sub sd} between phosphorus atoms used for DNP is more than ten times shorter than the nuclear polarization time T{sub 1}{sup p} of {sup 29}Si nuclei around phosphorus. Therefore, the regime of 'rapid spin diffusion' is realized in the DNP experiments.

  4. Visible Absorption Properties of Retinoic Acid Controlled on Hydrogenated Amorphous Silicon Thin Film

    NASA Astrophysics Data System (ADS)

    Tsujiuchi, Yutaka; Masumoto, Hiroshi; Goto, Takashi

    2008-02-01

    Langmuir-Blodgett (LB) films of retinoic acid and LB films of retinoic acid mixed with a peptide that contains an alanine-lysine-valine (AKV) amino acid sequence deposited on a hydrogenated amorphous silicon (a-Si:H) film prepared by electron cyclotron resonance (ECR) plasma sputtering were fabricated, and their light absorption spectrums were compared. A specific visible light absorption at approximately 500 nm occurred in a film that had a film thickness of more than 80 nm and a hydrogen concentration of more than 20% in the sputtering process gas. Mixing the AKV sequence peptide with retinoic acid caused a 6 nm blueshift, from 363 to 357 nm, of the absorption maximum of the composite LB film on a SiO2 substrate. Using the same peptide, a large 30 nm blueshift, from 500 to 470 nm, was induced in the composite LB film on the a-Si:H film.

  5. Controlled in situ boron doping of short silicon nanowires grown by molecular beam epitaxy

    SciTech Connect

    Das Kanungo, Pratyush; Zakharov, Nikolai; Bauer, Jan; Breitenstein, Otwin; Werner, Peter; Goesele, Ulrich

    2008-06-30

    Epitaxial silicon nanowires (NWs) of short heights ({approx}280 nm) on Si <111> substrate were grown and doped in situ with boron on a concentration range of 10{sup 15}-10{sup 19} cm{sup -3} by coevaporation of atomic Si and B by molecular beam epitaxy. Transmission electron microscopy revealed a single-crystalline structure of the NWs. Electrical measurements of the individual NWs confirmed the doping. However, the low doped (10{sup 15} cm{sup -3}) and medium doped (3x10{sup 16} and 1x10{sup 17} cm{sup -3}) NWs were heavily depleted by the surface states while the high doped (10{sup 18} and 10{sup 19} cm{sup -3}) ones showed volume conductivities expected for the corresponding intended doping levels.

  6. Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

    PubMed Central

    Lee, Seok Woo; Lee, Hyun-Wook; Ryu, Ill; Nix, William D.; Gao, Huajian; Cui, Yi

    2015-01-01

    Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Here, we demonstrate physical and mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of lithiated Si by lessening the tensile stress concentrations in Si structures. This study will contribute to improved design of Si structures at the electrode level for high-performance Li-ion batteries. PMID:26112834

  7. Characterization of a controlled electroless deposition of copper thin film on germanium and silicon surfaces

    NASA Astrophysics Data System (ADS)

    Scudiero, Louis; Fasasi, Ayuba; Griffiths, Peter R.

    2011-02-01

    Nanofilms of copper were deposited on silicon and, for the first time, on polycrystalline germanium substrates by electroless deposition. Germanium or silicon disks were immersed in a 10 mM copper sulfate solution containing dilute hydrofluoric acid at room temperature. This simple one-step deposition does not require the use of laborious operations or expensive equipment, that the reaction medium be degassed, or that the film be annealed. The copper film grows in a few minutes, producing a film on both Ge and Si that covers a very large area of the substrate in contrast to other metals such as Au, Ag, Pt and Pd for which deposition on Ge and Si produces islands or dendrites. Atomic force microscopy, X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (PXRD) were used to characterize the microstructure and confirmed the formation of elemental copper nanofilms. The AFM micrographs reveal a Stranski-Krastanov type of film growth (layers + islands) that varies with the length of time the Ge or Si substrate is immersed in the CuSO4 solution. Thicker films were observed on the Ge than on the Si substrate resulting in larger particles and rougher surface than on Si. XPS analysis shows that the elemental copper is deposited on both Ge and Si substrates and that the films oxidize over a period of weeks with air exposure at room temperature. Finally, PXRD data reveal two preferential orientations (1 1 1) and (2 0 0) for the copper crystallites grown on both Ge and Si. The same intensity of the (1 1 1)-texture was measured on both Ge and Si substrate which is an important result because it has been shown that the (1 1 1) texture reduces stress-induced voiding and increases resistance to electromigration in metal interconnects.

  8. 27 CFR 1.21 - Domestic producers, rectifiers, blenders, and warehousemen.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Domestic producers, rectifiers, blenders, and warehousemen. 1.21 Section 1.21 Alcohol, Tobacco Products and Firearms ALCOHOL AND... BOTTLING OF DISTILLED SPIRITS Basic Permits When Required § 1.21 Domestic producers, rectifiers,...

  9. TEC rectifier-A new possible terrestrial application of the thermionic converters

    NASA Astrophysics Data System (ADS)

    Martsinovsky, Artemy M.

    1999-01-01

    In this paper the idea is considered to use the thermionic converters for rectifying of low alternative voltages at high currents. The TEC-Rectifier ensures practically 100% electrical efficiency at any low voltages and can serve a great amount of electrical energy in galvanoplating. It is shown the possibility of such device creation at present and its advantages are discussed.

  10. Semiconductor-metal phase transition of vanadium dioxide nanostructures on silicon substrate: Applications for thermal control of spacecraft

    NASA Astrophysics Data System (ADS)

    Leahu, G. L.; Li Voti, R.; Larciprete, M. C.; Belardini, A.; Mura, F.; Fratoddi, I.; Sibilia, C.; Bertolotti, M.

    2014-06-01

    We present a detailed infrared study of the semiconductor-to-metal transition (SMT) in a vanadium dioxide (VO2) film deposited on silicon wafer. The VO2 phase transition is studied in the mid-infrared (MIR) region by analyzing the transmittance and the reflectance measurements, and the calculated emissivity. The temperature behaviour of the emissivity during the SMT put into evidence the phenomenon of the anomalous absorption in VO2 which has been explained by applying the Maxwell Garnett effective medium approximation theory, together with a strong hysteresis phenomenon, both useful to design tunable thermal devices to be applied for the thermal control of spacecraft. We have also applied the photothermal radiometry in order to study the changes in the modulated emissivity induced by laser. Experimental results show how the use of these techniques represent a good tool for a quantitative measurement of the optothermal properties of vanadium dioxide based structures.

  11. Study of radial growth rate and size control of silicon nanocrystals in square-wave-modulated silane plasmas

    SciTech Connect

    Nguyen-Tran, Th.; Roca i Cabarrocas, P.; Patriarche, G.

    2007-09-10

    The growth of silicon nanocrystals in high pressure and high dilution silane plasmas is investigated by using the temporal evolution of the self-bias on the radio frequency electrode and transmission electron microscopy. A square-wave-modulated plasma was used in order to control the growth of monodispersed nanoparticles with sizes smaller than 12 nm. To this end, the plasma on time was kept below 1 s. The radial growth rate of nanoparticles was varied in the range from 7.5 to 75 nm/s by changing silane partial pressure. Nanoparticles grown in silane-helium discharges have been found amorphous while they are crystalline in silane-hydrogen-argon discharges. Surprisingly, the crystallization in the gaseous phase does not depend on how slow or fast the particles grow but on the presence of atomic hydrogen.

  12. Semiconductor-metal phase transition of vanadium dioxide nanostructures on silicon substrate: Applications for thermal control of spacecraft

    SciTech Connect

    Leahu, G. L. Li Voti, R. Larciprete, M. C. Belardini, A. Mura, F. Sibilia, C.; Bertolotti, M.; Fratoddi, I.

    2014-06-19

    We present a detailed infrared study of the semiconductor-to-metal transition (SMT) in a vanadium dioxide (VO2) film deposited on silicon wafer. The VO2 phase transition is studied in the mid-infrared (MIR) region by analyzing the transmittance and the reflectance measurements, and the calculated emissivity. The temperature behaviour of the emissivity during the SMT put into evidence the phenomenon of the anomalous absorption in VO2 which has been explained by applying the Maxwell Garnett effective medium approximation theory, together with a strong hysteresis phenomenon, both useful to design tunable thermal devices to be applied for the thermal control of spacecraft. We have also applied the photothermal radiometry in order to study the changes in the modulated emissivity induced by laser. Experimental results show how the use of these techniques represent a good tool for a quantitative measurement of the optothermal properties of vanadium dioxide based structures.

  13. Input Power Quality Improvement in Switched Reluctance Motor Drive using Minnesota Rectifier

    NASA Astrophysics Data System (ADS)

    Singh, B.; Rajesh, M.

    2013-09-01

    This paper deals with an input power quality improvement in a midpoint converter based switched reluctance motor (SRM) drive at ac mains using Minnesota rectifier. Normally a midpoint converter is used as a power converter for SRM drive. Conventionally three phase ac mains fed bridge rectifier is used as a dc source to feed this power converter which produces high content of harmonics at ac mains with a very low power factor. The proposed Minnesota rectifier with a midpoint converter fed SRM drive improves the power factor at ac mains with low current harmonics. This method provides constant dc link voltage and balanced capacitor voltages of the midpoint converter. The Minnesota rectifier fed SRM drive is modelled and its performance is simulated in Matlab/Simulink environment. The performance of Minnesota rectifier is compared with a conventional bridge topology for SRM drive to demonstrate improved power quality at ac mains.

  14. Shape- and dimension-controlled single-crystalline silicon and SiGe nanotubes: toward nanofluidic FET devices.

    PubMed

    Ben Ishai, Moshit; Patolsky, Fernando

    2009-03-18

    We report here on the formation of robust and entirely hollow single-crystalline silicon nanotubes, from various tubular to conical structures, with uniform and well-controlled inner diameter, ranging from as small as 1.5 up to 500 nm, and controllable wall thickness. Second, and most important, these nanotubes can be doped in situ with different concentrations of boron and phosphine to give p/n-type semiconductor nanotubes. Si(x)Ge(1-x)-alloy nanotubes can also be prepared. This synthetic approach enables independent and precise control of diameter, wall thickness, shape, taper angle, crystallinity, and chemical/electrical characteristics of the nanotubular structures obtained. Notably, diameter and wall thickness of nearly any size can be obtained. This unique advantage allows the achievement of novel and perfectly controlled high-quality electronic materials and the tailoring of the tube properties to better fit many biological, chemical, and electrical applications. Electrical devices based on this new family of electrically active nanotubular building-block structures are also described with a view toward the future realization of nanofluidic FET devices. PMID:19226180

  15. The use of acoustoelectrochemistry to investigate rectified diffusion.

    PubMed

    Birkin, Peter R; Leighton, Timothy G; Watson, Yvonne E

    2004-05-01

    This paper describes the approach to bubble related phenomena using a novel 'acoustoelectrochemical' technique designed to investigate the physical and chemical effects of the acoustically induced motion of the bubble wall. In particular it describes the behaviour of a suspended gas bubble irradiated with sound of an appropriate frequency and pressure to induce bubble wall oscillation. The first electrochemical measurement of the growth of a bubble through rectified diffusion is demonstrated. The technique employed relies on the sensitivity of a scanning electrochemical microscope (SECM) deployed close to the gas/liquid interface of a bubble. The growth rate of the bubble (<0.1 microms(-1)) is reported. It will be also demonstrated that gas exchange across the phase boundary at the bubble wall, can be successfully probed when the bubble is stationary. PMID:15081984

  16. Quantum rectifier in a one-dimensional photonic channel

    NASA Astrophysics Data System (ADS)

    Mascarenhas, E.; Santos, M. F.; Auffèves, A.; Gerace, D.

    2016-04-01

    By using a fully quantum approach based on an input-output formulation of the stochastic Schrödinger equation, we show rectification of radiation fields in a one-dimensional waveguide doped with a pair of ideal two-level systems for three topical cases: classical driving, under the action of noise, and single-photon pulsed excitation. We show that even under the constant action of unwanted noise the device still operates effectively as an optical isolator, which is of critical importance for noise resistance. Finally, harnessing stimulated emission allows for nonreciprocal behavior for single-photon inputs, thus showing purely quantum rectification at the single-photon level. The latter is a considerable step towards the ultimate goal of devising an unconditional quantum rectifier for arbitrary quantum states.

  17. Hot electron pump: a plasmonic rectifying antenna (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Yanik, Ahmet A.; Hossain, Golam I.

    2015-09-01

    Plasmonic nanostructures have been widely explored to improve absorption efficiency of conventional solar cells, either by employing them as a light scatterer, or as a source of local field enhancement. Unavoidable ohmic loss associated with the plasmonic metal nanostructures in visible spectrum, limits the efficiency improvement of photovoltaic devices by employing this local photon density of states (LDOS) engineering approach. Instead of using plasmonic structures as efficiency improving layer, recently, there has been a growing interest in exploring plasmoinc nanoparticle as the active medium for photovoltaic device. By extracting hot electrons that are created in metallic nanoparticles in a non-radiative Landau decay of surface plasmons, many novel plasmonic photovoltaic devices have been proposed. Moreover, these hot electrons in metal nanoparticles promises high efficiency with a spectral response that is not limited by the band gap of the semiconductors (active material of conventional solar cell). In this work, we will show a novel photovoltaic configuration of plasmonic nanoparticle that acts as an antenna by capturing free space ultrahigh frequency electromagnetic wave and rectify them through an ultrafast hot electron pump and eventually inject DC current in the contact of the device. We will introduce a bottom-up quantum mechanical approach model to explain fundamental physical processes involved in this hot electron pump rectifying antenna and it's ultrafast dynamics. Our model is based on non-equilibrium Green's function formalism, a robust theoretical framework to investigate transport and design nanoscale electronic devices. We will demonstrate some fundamental limitations that go the very foundations of quantum mechanics.

  18. Factors controlling the silicon isotope distribution in waters and surface sediments of the Peruvian coastal upwelling

    NASA Astrophysics Data System (ADS)

    Ehlert, Claudia; Grasse, Patricia; Mollier-Vogel, Elfi; Böschen, Tebke; Franz, Jasmin; de Souza, Gregory F.; Reynolds, Ben C.; Stramma, Lothar; Frank, Martin

    2012-12-01

    We present the first systematic study of the silicon isotope composition in the water column (δ30Si) and in diatoms (δ30Sidiatom) from the underlying surface sediments in a coastal upwelling region. The surface waters upwelling on the shelf off Peru are mainly fed by southward flowing subsurface waters along the coast, which show a mean δ30Si of +1.5‰. The concentration of dissolved silicic acid (Si(OH)4) increases towards the south in these waters and with increasing water depth, suggesting lateral mixing with water masses from the south and intense remineralisation of particulate biogenic silica (bSiO2) in the water column and in the surface sediments. Surface waters in the realm of the most intense upwelling between 5°S and 15°S have only marginally elevated δ30Si values (δ30Si = +1.7‰) with respect to the source Si isotope composition, whereas further north and south, where upwelling is less pronounced, surface waters are more strongly fractionated (δ30Si up to +2.8‰) due to the stronger utilisation of the smaller amounts of available Si(OH)4. The degree of Si(OH)4 utilisation in the surface waters along the shelf estimated from the Si(OH)4 concentration data ranges from 51% to 93%. The δ30Sidiatom values of hand-picked diatoms in the underlying surface sediments vary from +0.6‰ to +2.0‰, which is within the range of the expected fractionation between surface waters and diatoms. The fractionation signal in the surface waters produced during formation of the diatoms is reflected by the δ30Sidiatom values in the underlying sediments, with the lowest δ30Sidiatom values in the main upwelling region. The silicon isotope compositions of bSiO2 (δ30Si) from the same surface sediment samples are generally much lower than the δ30Sidiatom signatures indicating a significant contamination of the bSiO2 with biogenic siliceous material other than diatoms, such as sponge spicules. This shift towards lighter δ30Si values by up to -1.3‰ compared to

  19. Effects of trimebutine maleate on delayed rectifier K+ currents in guinea-pig ventricular myocytes.

    PubMed

    Morisawa, T; Hasegawa, J; Tanabe, K; Watanabe, A; Kitano, M; Kishimoto, Y

    2000-04-01

    The effects of trimebutine maleate, a drug commonly used to regulate motility in the gastrointestinal tract, on the delayed rectifier K+ current (I(K)) were evaluated in guinea-pig ventricular myocytes to determine whether the drug has a proarrhythmic effect through blockade of I(K). Trimebutine decreased I(K) in a concentration-dependent manner. To investigate the effects of trimebutine on two components of I(K) (I(Kr) and I(Ks); rapidly activated and slowly activated components, respectively), we performed the envelope-of-tails test. Trimebutine-sensitive I(K) was determined by digital subtraction of I(K) during exposure to trimebutine from control I(K) for each duration of the test pulse over the range 50 ms-2 s. The ratio of deltaI(K,tail)/deltaI(K) plotted against pulse duration for trimebutine-sensitive I(K) gradually decreased to a steady-state value as the duration of the test pulse was lengthened. This finding suggested a weak inhibitory effect of trimebutine on both I(Kr) and I(Ks). The effects of trimebutine on the inward rectifier K+ current (I(K1)) responsible for the resting potential and final repolarization phase of the action potential were investigated by applying voltage clamp ramps over a broad range of potentials. No significant effects were observed at 10 or 100 microM. We next investigated the effects of the drug on the L-type Ca2+ current (I(Ca)). Significant inhibition of I(Ca) was observed at trimebutine concentrations greater than 10 microM. These results suggested that trimebutine maleate has weak inhibitory effects on I(Kr), I(Ks) and I(Ca) at concentrations much higher than those in clinical use. PMID:10813550

  20. Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

    SciTech Connect

    Lee, Seok Woo; Lee, Hyun-Wook; Ryu, Ill; Nix, William D.; Gao, Huajian; Cui, Yi; /Stanford U., Materials Sci. Dept. /SLAC

    2015-06-01

    Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Herein, we demonstrate physical/mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Contract No. DE-AC02-76SF00515. SLAC-PUB-16300 2 lithiated Si by lessening the tensile stress concentrations in Si structures. This study will contribute to improved design of Si structures at the electrode level for high performance Li-ion batteries.

  1. Hierarchical porous silicon carbide with controlled micropores and mesopores for electric double layer capacitors

    NASA Astrophysics Data System (ADS)

    Kim, Myeongjin; Oh, Ilgeun; Kim, Jooheon

    2015-05-01

    Three-dimensional hierarchical micro and mesoporous silicon carbide spheres (MMPSiC) are prepared by the template method and carbonization reaction via the aerosol spray drying method. The mesopores are generated by the self-assembly of the structure-directing agents, whereas the micropores are derived from the partial evaporation of Si atoms during carbonization. To investigate the effect of mesopore size on electrochemical performance, three types of MMPSiC with different mesopore size were fabricated by using three different structure directing agents (cetyltriethylammonium bromide (CTAB), Polyethylene glycol hexadecyl ether (Brij56), and Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123)). The MMPSiC electrode prepared with Brij56 exhibits the highest charge storage capacity with a specific capacitance of 253.7 F g-1 at a scan rate of 5 mV s-1 and 87.9% rate performance from 5 to 500 mV s-1 in 1 M Na2SO4 aqueous electrolyte. The outstanding electrochemical performance might be because of the ideal mesopore size, which effectively reduces the resistant pathways for ion diffusion in the pores and provides a large accessible surface area for ion transport/charge storage. These encouraging results demonstrate that the MMPSiC prepared with Brij56 is a promising candidate for high performance electrode materials for supercapacitors.

  2. Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

    DOE PAGESBeta

    Lee, Seok Woo; Lee, Hyun -Wook; Ryu, Ill; Nix, William D.; Gao, Huajian; Cui, Yi

    2015-06-26

    Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Here, we demonstrate physical and mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics somore » that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of lithiated Si by lessening the tensile stress concentrations in Si structures. Lastly, this study will contribute to improved design of Si structures at the electrode level for high-performance Li-ion batteries.« less

  3. Glass frit bonding with controlled width and height using a two-step wet silicon etching procedure

    NASA Astrophysics Data System (ADS)

    Yifang, Liu; Daner, Chen; Liwei, Lin; Gaofeng, Zheng; Jianyi, Zheng; Lingyun, Wang; Daoheng, Sun

    2016-03-01

    A simple and versatile two-step silicon wet etching technique for the control of the width and height of the glass frit bonding layer has been developed to improve bonding strength and reliability in wafer-level microelectromechanical systems (MEMS) packaging processes. The height of the glass frit bonding layer is set by the design of a vertical reference wall which regulates the distance between the silicon wafer and the encapsulation capping substrate. On the other hand, the width of the bonding layer is constrained between two micro grooves which are used to accommodate the spillages of extra glass frit during the bonding process. An optimized thermal bonding process, including the formation of glass liquid, removal of gas bubbles under vacuum and the filling of voids under normal atmospheric condition has been developed to suppress the formation of the bubbles/voids. The stencil printing and pre-sintering processes for the glass frit have been characterized before the thermal bonding process under different magnitudes of bonding pressure. The bonding gap thickness is found to be equal to the height of the reference wall of 10 μm in the prototype design. The bubbles/voids are found to be suppressed effectively and the bonding strength increases from 10.2 to 19.1 MPa as compared with a conventional thermal annealing process in air. Experimentally, prototype samples are measured to have passed the high hermetic sealing leakage tests of 5  ×  10-8 atm cc s-1.

  4. Ultrafast active control of localized surface plasmon resonances in silicon bowtie antennas.

    PubMed

    Berrier, Audrey; Ulbricht, Ronald; Bonn, Mischa; Rivas, Jaime Gómez

    2010-10-25

    Localized surface plasmon polaritons (LSPPs) provide an efficient means of achieving extreme light concentration. In recent years, their active control has become a major aspiration of plasmonic research. Here, we demonstrate direct control of semiconductor bowtie antennas, enabling active excitation of LSPPs, at terahertz (THz) frequencies. We modify the LSPPs by ultrafast optical modulation of the free carrier density in the plasmonic structure itself, allowing for active control of the semiconductor antennas on picosecond timescales. Moreover, this control enables the manipulation of the field intensity enhancements in ranges of four orders of magnitude. PMID:21164664

  5. Femtosecond laser-controlled self-assembly of amorphous-crystalline nanogratings in silicon.

    PubMed

    Puerto, Daniel; Garcia-Lechuga, Mario; Hernandez-Rueda, Javier; Garcia-Leis, Adianez; Sanchez-Cortes, Santiago; Solis, Javier; Siegel, Jan

    2016-07-01

    Self-assembly (SA) of molecular units to form regular, periodic extended structures is a powerful bottom-up technique for nanopatterning, inspired by nature. SA can be triggered in all classes of solid materials, for instance, by femtosecond laser pulses leading to the formation of laser-induced periodic surface structures (LIPSS) with a period slightly shorter than the laser wavelength. This approach, though, typically involves considerable material ablation, which leads to an unwanted increase of the surface roughness. We present a new strategy to fabricate high-precision nanograting structures in silicon, consisting of alternating amorphous and crystalline lines, with almost no material removal. The strategy can be applied to static irradiation experiments and can be extended into one and two dimensions by scanning the laser beam over the sample surface. We demonstrate that lines and areas with parallel nanofringe patterns can be written by an adequate choice of spot size, repetition rate and scan velocity, keeping a constant effective pulse number (N eff) per area for a given laser wavelength. A deviation from this pulse number leads either to inhomogeneous or ablative structures. Furthermore, we demonstrate that this approach can be used with different laser systems having widely different wavelengths (1030 nm, 800 nm, 400 nm), pulse durations (370 fs, 100 fs) and repetition rates (500 kHz, 100 Hz, single pulse) and that the grating period can also be tuned by changing the angle of laser beam incidence. The grating structures can be erased by irradiation with a single nanosecond laser pulse, triggering recrystallization of the amorphous stripes. Given the large differences in electrical conductivity between the two phases, our structures could find new applications in nanoelectronics. PMID:27199344

  6. Femtosecond laser-controlled self-assembly of amorphous-crystalline nanogratings in silicon

    NASA Astrophysics Data System (ADS)

    Puerto, Daniel; Garcia-Lechuga, Mario; Hernandez-Rueda, Javier; Garcia-Leis, Adianez; Sanchez-Cortes, Santiago; Solis, Javier; Siegel, Jan

    2016-07-01

    Self-assembly (SA) of molecular units to form regular, periodic extended structures is a powerful bottom-up technique for nanopatterning, inspired by nature. SA can be triggered in all classes of solid materials, for instance, by femtosecond laser pulses leading to the formation of laser-induced periodic surface structures (LIPSS) with a period slightly shorter than the laser wavelength. This approach, though, typically involves considerable material ablation, which leads to an unwanted increase of the surface roughness. We present a new strategy to fabricate high-precision nanograting structures in silicon, consisting of alternating amorphous and crystalline lines, with almost no material removal. The strategy can be applied to static irradiation experiments and can be extended into one and two dimensions by scanning the laser beam over the sample surface. We demonstrate that lines and areas with parallel nanofringe patterns can be written by an adequate choice of spot size, repetition rate and scan velocity, keeping a constant effective pulse number (N eff) per area for a given laser wavelength. A deviation from this pulse number leads either to inhomogeneous or ablative structures. Furthermore, we demonstrate that this approach can be used with different laser systems having widely different wavelengths (1030 nm, 800 nm, 400 nm), pulse durations (370 fs, 100 fs) and repetition rates (500 kHz, 100 Hz, single pulse) and that the grating period can also be tuned by changing the angle of laser beam incidence. The grating structures can be erased by irradiation with a single nanosecond laser pulse, triggering recrystallization of the amorphous stripes. Given the large differences in electrical conductivity between the two phases, our structures could find new applications in nanoelectronics.

  7. Controlled Synthesis of Millimeter-Long Silicon Nanowires with Uniform Electronic Properties

    PubMed Central

    Park, Won Il; Zheng, Gengfeng; Jiang, Xiaocheng; Tian, Bozhi; Lieber, Charles M.

    2009-01-01

    We report the nanocluster-catalyzed growth of ultra-long and highly-uniform single-crystalline silicon nanowires (SiNWs) with millimeter-scale lengths and aspect ratios up to ca. 100,000. The average SiNW growth rate using disilane (Si2H6) at 400 °C was 31 µm/min, while the growth rate determined for silane (SiH4) reactant under similar growth conditions was 130 times lower. Transmission electron microscopy studies of millimeter-long SiNWs with diameters of 20–80 nm show that the nanowires grow preferentially along the <110> direction independent of diameter. In addition, ultra-long SiNWs were used as building blocks to fabricate one-dimensional arrays of field-effect transistors (FETs) consisting of ca. 100 independent devices per nanowire. Significantly, electrical transport measurements demonstrated that the millimeter-long SiNWs had uniform electrical properties along the entire length of wires, and each device can behave as a reliable FET with an on-state current, threshold voltage, and transconductance values (average ± 1 standard deviation) of 1.8 ± 0.3 µA, 6.0 ± 1.1 V, 210 ± 60 nS, respectively. Electronically-uniform millimeter-long SiNWs were also functionalized with monoclonal antibody receptors, and used to demonstrate multiplexed detection of cancer marker proteins with a single nanowire. The synthesis of structurally- and electronically-uniform ultra-long SiNWs may open up new opportunities for integrated nanoelectronics, and could serve as unique building blocks linking integrated structures from the nanometer through millimeter length scales. PMID:18710294

  8. Controlled synthesis of millimeter-long silicon nanowires with uniform electronic properties.

    PubMed

    Park, Won Il; Zheng, Gengfeng; Jiang, Xiaocheng; Tian, Bozhi; Lieber, Charles M

    2008-09-01

    We report the nanocluster-catalyzed growth of ultralong and highly uniform single-crystalline silicon nanowires (SiNWs) with millimeter-scale lengths and aspect ratios up to approximately 100,000. The average SiNW growth rate using disilane (Si 2H 6) at 400 degrees C was 31 microm/min, while the growth rate determined for silane (SiH 4) reactant under similar growth conditions was 130 times lower. Transmission electron microscopy studies of millimeter-long SiNWs with diameters of 20-80 nm show that the nanowires grow preferentially along the 110 direction independent of diameter. In addition, ultralong SiNWs were used as building blocks to fabricate one-dimensional arrays of field-effect transistors (FETs) consisting of approximately 100 independent devices per nanowire. Significantly, electrical transport measurements demonstrated that the millimeter-long SiNWs had uniform electrical properties along the entire length of wires, and each device can behave as a reliable FET with an on-state current, threshold voltage, and transconductance values (average +/-1 standard deviation) of 1.8 +/- 0.3 microA, 6.0 +/- 1.1 V, 210 +/- 60 nS, respectively. Electronically uniform millimeter-long SiNWs were also functionalized with monoclonal antibody receptors and used to demonstrate multiplexed detection of cancer marker proteins with a single nanowire. The synthesis of structurally and electronically uniform ultralong SiNWs may open up new opportunities for integrated nanoelectronics and could serve as unique building blocks linking integrated structures from the nanometer through millimeter length scales. PMID:18710294

  9. D0 Silicon Strip Detector Upgrade Project SVX Sequencer Controller Board

    SciTech Connect

    Utes, M.; /Fermilab

    2001-05-29

    The Sequencer Controller boards are 9U by 340mm circuit boards that will reside in slot 1 of each of eight Sequencer crates in the D0 detector platform. The primary purpose is to control the Sequencers during data acquisition based on trigger information from the D0 Trigger Framework. Functions and features are as follows: (1) Receives the Serial Command Link (SCL) from the D0 Trigger System and controls the operation of the Sequencers by forming a custom serial control link (NRZ/Clock) which is distributed individually to each Sequencer via the 11 Backplane; (2) Controllable delays adjust NRZ control link phasing to compensate for the various cable-length delays between the Sequencers and SVX chips, delay control is common for slots 2-11, and for slots 12-21 of the crate; (3) Each NRZ control link is phase controlled so that commands reach each Sequencer in a given half-crate simultaneously, i.e., the link is compensated for backplane propagation delays; (4) External communication via MIL-STD-1553; (5) Stand-alone operation via 1553 trigger commands in absence of an SCL link; (6) 1553-writeable register for triggering a laser, etc. followed by an acquisition cycle; (7) TTL front panel input to trigger an acquisition cycle, e.g. from a scintillator; (8) Synch Trig, Veto, Busy and Preamp Reset TTL outputs on front panel LEMOs; (9) On-board 53.104 MHz oscillator for stand-alone operation; (10) 1553 or SCL-triggerable Cal-inject cycle; (11) Front-panel inputs to accept NRZ/Clock link from the VRB Controller; (12) Front panel displays and LEDs show the board status at a glance; and (13) In-system programmable EPLDs are programmed via Altera's 'Byteblaster'.

  10. Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

    SciTech Connect

    Yu, Zhongwei; Lu, Jiawen; Qian, Shengyi; Xu, Jun; Xu, Ling; Wang, Junzhuan; Shi, Yi; Chen, Kunji; Yu, Linwei E-mail: linwei.yu@polytechnique.edu

    2015-10-19

    Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs.

  11. Inward rectifier potassium currents in mammalian skeletal muscle fibres.

    PubMed

    DiFranco, Marino; Yu, Carl; Quiñonez, Marbella; Vergara, Julio L

    2015-03-01

    Inward rectifying potassium (Kir) channels play a central role in maintaining the resting membrane potential of skeletal muscle fibres. Nevertheless their role has been poorly studied in mammalian muscles. Immunohistochemical and transgenic expression were used to assess the molecular identity and subcellular localization of Kir channel isoforms. We found that Kir2.1 and Kir2.2 channels were targeted to both the surface and the transverse tubular system membrane (TTS) compartments and that both isoforms can be overexpressed up to 3-fold 2 weeks after transfection. Inward rectifying currents (IKir) had the canonical features of quasi-instantaneous activation, strong inward rectification, depended on the external [K(+)], and could be blocked by Ba(2+) or Rb(+). In addition, IKir records show notable decays during large 100 ms hyperpolarizing pulses. Most of these properties were recapitulated by model simulations of the electrical properties of the muscle fibre as long as Kir channels were assumed to be present in the TTS. The model also simultaneously predicted the characteristics of membrane potential changes of the TTS, as reported optically by a fluorescent potentiometric dye. The activation of IKir by large hyperpolarizations resulted in significant attenuation of the optical signals with respect to the expectation for equal magnitude depolarizations; blocking IKir with Ba(2+) (or Rb(+)) eliminated this attenuation. The experimental data, including the kinetic properties of IKir and TTS voltage records, and the voltage dependence of peak IKir, while measured at widely dissimilar bulk [K(+)] (96 and 24 mm), were closely predicted by assuming Kir permeability (PKir) values of ∼5.5 × 10(-6 ) cm s(-1) and equal distribution of Kir channels at the surface and TTS membranes. The decay of IKir records and the simultaneous increase in TTS voltage changes were mostly explained by K(+) depletion from the TTS lumen. Most importantly, aside from allowing an accurate

  12. Spin Transport in Silicon

    NASA Astrophysics Data System (ADS)

    Appelbaum, Ian

    2008-03-01

    Silicon has been broadly viewed as the ideal material for spintronics due to its low atomic weight, lattice inversion symmetry, and near lack of nuclear spin, resulting in exceptionally long spin lifetime. Despite this appeal, however, the experimental difficulties of achieving coherent spin transport in silicon were overcome for the first time only recently, by using unique spin-polarized hot-electron injection and detection techniques. [1] Our subsequent observations of very long spin lifetimes and transit lengths [2] have impact on prospects for Silicon spintronics as the basis for a new paradigm of information processing. [1] Ian Appelbaum, Biqin Huang, and Douwe J. Monsma, ``Electronic measurement and control of spin transport in silicon,'' Nature 447, 295 (2007). [2] Biqin Huang, Douwe J. Monsma, and Ian Appelbaum, ``Coherent spin transport through a 350-micron-thick silicon wafer,'' Phys. Rev. Lett. 99, 177209 (2007).

  13. Intravitreal Controlled Release of Dexamethasone from Engineered Microparticles of Porous Silicon Dioxide

    PubMed Central

    Wang, Chengyun; Hou, Huiyuan; Nan, Kaihui; Sailor, Michael J; Freeman, William R.; Cheng, Lingyun

    2014-01-01

    Dexamethasone is a glucocorticoid that is widely used in the ophthalmic arena. The recent FDA approved dexamethasone implant can provide a three month efficacy but with high rate of drug related cataract and high intraocular pressure (IOP). It seems that higher steroid in aqueous humor and around lens may be associated with these complications based on clinical fact that higher IOP was observed with intravitreal triamcinolone acetonide (TA) than with subtenon TA. We hypothesize that placing a sustained dexamethasone release system near back of the eye through a fine needle can maximize efficacy while mitigate higher rate of IOP rise and cataract. To develop a sustained intravitreal dexamethasone delivery system, porous silicon dioxide (pSiO2) microparticles were fabricated and functionalized with amines as well as carboxyl groups. Dexamethasone was conjugated to pSiO2 through the Steglich Esterificaion Reaction between hydroxyl of dexamethasone and carboxyl groups on the pSiO2. The drug loading was confirmed by Fourier transform infrared spectroscopy (FTIR) and loading efficiency was quantitated using thermogravimetric analysis (TGA). In vitro release was conducted for three months and dexamethasone was confirmed in the released samples using liquid chromatography-tandem mass spectrometry (LC/MS/MS). A pilot ocular safety and determination of vitreous drug level was performed in rabbit eyes. The drug loading study demonstrated that loading efficiency was from 5.96% to 10.77% depending on the loading reaction time, being higher with longer loading reaction time before reaching saturation around 7 days. In vitro drug release study revealed that dexamethasone release from pSiO2 particles was sustainable for over 90 days and was 80 days longer than free dexamethasone or infiltration-loaded pSiO2 particle formulation in the same setting. Pilot in vivo study demonstrated no sign of ocular adverse reaction in rabbit eyes following a single 3 mg intravitreal injection and

  14. Intravitreal controlled release of dexamethasone from engineered microparticles of porous silicon dioxide.

    PubMed

    Wang, Chengyun; Hou, Huiyuan; Nan, Kaihui; Sailor, Michael J; Freeman, William R; Cheng, Lingyun

    2014-12-01

    Dexamethasone is a glucocorticoid that is widely used in the ophthalmic arena. The recent FDA approved dexamethasone implant can provide a three month efficacy but with high rate of drug related cataract and high intraocular pressure (IOP). It seems that higher steroid in aqueous humor and around lens may be associated with these complications based on clinical fact that higher IOP was observed with intravitreal triamcinolone acetonide (TA) than with subtenon TA. We hypothesize that placing a sustained dexamethasone release system near back of the eye through a fine needle can maximize efficacy while mitigate higher rate of IOP rise and cataract. To develop a sustained intravitreal dexamethasone delivery system, porous silicon dioxide (pSiO2) microparticles were fabricated and functionalized with amines as well as carboxyl groups. Dexamethasone was conjugated to pSiO2 through the Steglich Esterification Reaction between hydroxyl of dexamethasone and carboxyl groups on the pSiO2. The drug loading was confirmed by Fourier transform infrared spectroscopy (FTIR) and loading efficiency was quantitated using thermogravimetric analysis (TGA). In vitro release was conducted for three months and dexamethasone was confirmed in the released samples using liquid chromatography-tandem mass spectrometry (LC/MS/MS). A pilot ocular safety and determination of vitreous drug level was performed in rabbit eyes. The drug loading study demonstrated that loading efficiency was from 5.96% to 10.77% depending on the loading reaction time, being higher with longer loading reaction time before reaching saturation around 7 days. In vitro drug release study revealed that dexamethasone release from pSiO2 particles was sustainable for over 90 days and was 80 days longer than free dexamethasone or infiltration-loaded pSiO2 particle formulation in the same setting. Pilot in vivo study demonstrated no sign of ocular adverse reaction in rabbit eyes following a single 3 mg intravitreal injection and

  15. Direct and Indirect Two-color Coherent Control in Bulk Silicon

    NASA Astrophysics Data System (ADS)

    Cheng, Jinluo; Rioux, Julien; Sipe, John

    2012-02-01

    Using an empirical pseudopotential model for electron states and an adiabatic bond charge model for phonon states, we investigate the two-color direct and indirect coherent current injection with an incident optical field composed of a fundamental frequency and its second harmonic, and calculate the response tensors of the electron (hole) charge and spin currents. We show the current control for three different polarization scenarios: For co-circularly polarized beams, the direction of the charge current and the polarization direction of the spin current can be controlled by a relative-phase parameter; for the co-linearly and cross-linearly polarized beams, the current amplitude can be controlled by that parameter. For the indirect gap injection, the spectral dependence of the maximum swarm velocity shows that the direction of charge current reverses under an increase in photon energy.

  16. Graphene ballistic nano-rectifier with very high responsivity

    NASA Astrophysics Data System (ADS)

    Auton, Gregory; Zhang, Jiawei; Kumar, Roshan Krishna; Wang, Hanbin; Zhang, Xijian; Wang, Qingpu; Hill, Ernie; Song, Aimin

    2016-05-01

    Although graphene has the longest mean free path of carriers of any known electronic material, very few novel devices have been reported to harness this extraordinary property. Here we demonstrate a ballistic nano-rectifier fabricated by creating an asymmetric cross-junction in single-layer graphene sandwiched between boron nitride flakes. A mobility ~200,000 cm2 V-1 s-1 is achieved at room temperature, well beyond that required for ballistic transport. This enables a voltage responsivity as high as 23,000 mV mW-1 with a low-frequency input signal. Taking advantage of the output channels being orthogonal to the input terminals, the noise is found to be not strongly influenced by the input. Hence, the corresponding noise-equivalent power is as low as 0.64 pW Hz-1/2. Such performance is even comparable to superconducting bolometers, which however need to operate at cryogenic temperatures. Furthermore, output oscillations are observed at low temperatures, the period of which agrees with the lateral size quantization.

  17. Graphene ballistic nano-rectifier with very high responsivity.

    PubMed

    Auton, Gregory; Zhang, Jiawei; Kumar, Roshan Krishna; Wang, Hanbin; Zhang, Xijian; Wang, Qingpu; Hill, Ernie; Song, Aimin

    2016-01-01

    Although graphene has the longest mean free path of carriers of any known electronic material, very few novel devices have been reported to harness this extraordinary property. Here we demonstrate a ballistic nano-rectifier fabricated by creating an asymmetric cross-junction in single-layer graphene sandwiched between boron nitride flakes. A mobility ∼200,000 cm(2) V(-1) s(-1) is achieved at room temperature, well beyond that required for ballistic transport. This enables a voltage responsivity as high as 23,000 mV mW(-1) with a low-frequency input signal. Taking advantage of the output channels being orthogonal to the input terminals, the noise is found to be not strongly influenced by the input. Hence, the corresponding noise-equivalent power is as low as 0.64 pW Hz(-1/2). Such performance is even comparable to superconducting bolometers, which however need to operate at cryogenic temperatures. Furthermore, output oscillations are observed at low temperatures, the period of which agrees with the lateral size quantization. PMID:27241162

  18. Remote electrical stimulation by means of implanted rectifiers.

    PubMed

    Ivorra, Antoni

    2011-01-01

    Miniaturization of active implantable medical devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants--batteries and inductive couplers--comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. Here, for overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, it is proposed to make those implants act as rectifiers of high frequency bursts supplied by remote electrodes. In this way, low frequency currents will be generated locally around the implant and these low frequency currents will perform stimulation of excitable tissues whereas the high frequency currents will cause only innocuous heating. The present study numerically demonstrates that low frequency currents capable of stimulation can be produced by a miniature device behaving as a diode when high frequency currents, neither capable of thermal damage nor of stimulation, flow through the tissue where the device is implanted. Moreover, experimental evidence is provided by an in vivo proof of concept model consisting of an anesthetized earthworm in which a commercial diode was implanted. With currently available microelectronic techniques, very thin stimulation capsules (diameter <500 µm) deliverable by injection are easily conceivable. PMID:21850274

  19. Remote Electrical Stimulation by Means of Implanted Rectifiers

    PubMed Central

    Ivorra, Antoni

    2011-01-01

    Miniaturization of active implantable medical devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants – batteries and inductive couplers – comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. Here, for overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, it is proposed to make those implants act as rectifiers of high frequency bursts supplied by remote electrodes. In this way, low frequency currents will be generated locally around the implant and these low frequency currents will perform stimulation of excitable tissues whereas the high frequency currents will cause only innocuous heating. The present study numerically demonstrates that low frequency currents capable of stimulation can be produced by a miniature device behaving as a diode when high frequency currents, neither capable of thermal damage nor of stimulation, flow through the tissue where the device is implanted. Moreover, experimental evidence is provided by an in vivo proof of concept model consisting of an anesthetized earthworm in which a commercial diode was implanted. With currently available microelectronic techniques, very thin stimulation capsules (diameter <500 µm) deliverable by injection are easily conceivable. PMID:21850274

  20. Graphene ballistic nano-rectifier with very high responsivity

    PubMed Central

    Auton, Gregory; Zhang, Jiawei; Kumar, Roshan Krishna; Wang, Hanbin; Zhang, Xijian; Wang, Qingpu; Hill, Ernie; Song, Aimin

    2016-01-01

    Although graphene has the longest mean free path of carriers of any known electronic material, very few novel devices have been reported to harness this extraordinary property. Here we demonstrate a ballistic nano-rectifier fabricated by creating an asymmetric cross-junction in single-layer graphene sandwiched between boron nitride flakes. A mobility ∼200,000 cm2 V−1 s−1 is achieved at room temperature, well beyond that required for ballistic transport. This enables a voltage responsivity as high as 23,000 mV mW−1 with a low-frequency input signal. Taking advantage of the output channels being orthogonal to the input terminals, the noise is found to be not strongly influenced by the input. Hence, the corresponding noise-equivalent power is as low as 0.64 pW Hz−1/2. Such performance is even comparable to superconducting bolometers, which however need to operate at cryogenic temperatures. Furthermore, output oscillations are observed at low temperatures, the period of which agrees with the lateral size quantization. PMID:27241162

  1. Finite element modeling of electrically rectified piezoelectric energy harvesters

    NASA Astrophysics Data System (ADS)

    Wu, P. H.; Shu, Y. C.

    2015-09-01

    Finite element models are developed for designing electrically rectified piezoelectric energy harvesters. They account for the consideration of common interface circuits such as the standard and parallel-/series-SSHI (synchronized switch harvesting on inductor) circuits, as well as complicated structural configurations such as arrays of piezoelectric oscillators. The idea is to replace the energy harvesting circuit by the proposed equivalent load impedance together with the capacitance of negative value. As a result, the proposed framework is capable of being implemented into conventional finite element solvers for direct system-level design without resorting to circuit simulators. The validation based on COMSOL simulations carried out for various interface circuits by the comparison with the standard modal analysis model. The framework is then applied to the investigation on how harvested power is reduced due to fabrication deviations in geometric and material properties of oscillators in an array system. Remarkably, it is found that for a standard array system with strong electromechanical coupling, the drop in peak power turns out to be insignificant if the optimal load is carefully chosen. The second application is to design broadband energy harvesting by developing array systems with suitable interface circuits. The result shows that significant broadband is observed for the parallel (series) connection of oscillators endowed with the parallel-SSHI (series-SSHI) circuit technique.

  2. Mitigating impact of rectified RF sheath potential on the ELMs

    NASA Astrophysics Data System (ADS)

    Gui, Bin; Xu, Xueqiao; Xia, Tianyang

    2014-10-01

    Here we report on the BOUT++ simulation results for the mitigating impact of rectified RF sheath potential on the peeling-ballooning modes. The limiter and the RF wave antenna are placed at the outer middle plane in the scrape-off-layer (SOL) in shift-circle geometry. The external shear flow is induced by the limiter and the RF wave. Besides this, the sheath boundary conditions are imposed on the perturbed potential and parallel current. From the three-field simulations, it is found that the energy loss is suppressed by the external shear flow in the nonlinear phase. The external shear flow due to the RF wave leads to a broad turbulence spectrum. The wider spectrum leads to a weaker turbulence transport and results in a smaller energy loss. The perturbed electric potential and the parallel current near the sheath region are also suppressed locally due to the sheath boundary condition. Based on this work, this effect of limiter will also be applied in six-field which includes more physics effects. The effect of sheath boundary conditions on the thermal conductivities and heat flux will be studied. This work was performed for USDOE by LLNL under DE-AC52-07NA27344, LLNL LDRD project 12-ERD-022 and the China Natural Science Foundation under Contract No. 10721505. LLNL-ABS-657008.

  3. Bubble growth by rectified diffusion at high gas supersaturation levels.

    PubMed

    Ilinskii, Yurii A; Wilson, Preston S; Hamilton, Mark F

    2008-10-01

    For high gas supersaturation levels in liquids, on the order of 300% as predicted in capillaries of marine mammals following a series of dives [D. S. Houser, R. Howard, and S. Ridgway, J. Theor. Biol. 213, 183-195 (2001)], standard mathematical models of both static and rectified diffusion are found to underestimate the rate of bubble growth by 10%-20%. The discrepancy is demonstrated by comparing predictions based on existing mathematical models with direct numerical solutions of the differential equations for gas diffusion in the liquid and thermal conditions in the bubble. Underestimation of bubble growth by existing mathematical models is due to the underlying assumption that the gas concentration in the liquid is given by its value for a bubble of constant equilibrium radius. This assumption is violated when high supersaturation causes the bubble to grow too fast in relation to the time scale associated with diffusion. Rapid bubble growth results in an increased gas concentration gradient at the bubble wall and therefore a growth rate in excess of predictions based on constant equilibrium bubble radius. PMID:19062834

  4. On the Control of the Fixed Charge Densities in Al2O3-Based Silicon Surface Passivation Schemes.

    PubMed

    Simon, Daniel K; Jordan, Paul M; Mikolajick, Thomas; Dirnstorfer, Ingo

    2015-12-30

    A controlled field-effect passivation by a well-defined density of fixed charges is crucial for modern solar cell surface passivation schemes. Al2O3 nanolayers grown by atomic layer deposition contain negative fixed charges. Electrical measurements on slant-etched layers reveal that these charges are located within a 1 nm distance to the interface with the Si substrate. When inserting additional interface layers, the fixed charge density can be continuously adjusted from 3.5 × 10(12) cm(-2) (negative polarity) to 0.0 and up to 4.0 × 10(12) cm(-2) (positive polarity). A HfO2 interface layer of one or more monolayers reduces the negative fixed charges in Al2O3 to zero. The role of HfO2 is described as an inert spacer controlling the distance between Al2O3 and the Si substrate. It is suggested that this spacer alters the nonstoichiometric initial Al2O3 growth regime, which is responsible for the charge formation. On the basis of this charge-free HfO2/Al2O3 stack, negative or positive fixed charges can be formed by introducing additional thin Al2O3 or SiO2 layers between the Si substrate and this HfO2/Al2O3 capping layer. All stacks provide very good passivation of the silicon surface. The measured effective carrier lifetimes are between 1 and 30 ms. This charge control in Al2O3 nanolayers allows the construction of zero-fixed-charge passivation layers as well as layers with tailored fixed charge densities for future solar cell concepts and other field-effect based devices. PMID:26618751

  5. D0 Silicon Upgrade: Cryolab Control Valve Modification Information for D0-EVMF-H

    SciTech Connect

    Rucincki, Russ; /Fermilab

    1995-10-26

    This engineering note documents some information regarding the solenoid magnet flow valve, EVMF. See also EN-437 'Control Dewar valve sizing' also for further information on this valve. This note documents the modification done to the valve to change it to a Cv = 0.32.

  6. Low temperature synthesis of silicon quantum dots with plasma chemistry control in dual frequency non-thermal plasmas.

    PubMed

    Sahu, Bibhuti Bhusan; Yin, Yongyi; Han, Jeon Geon; Shiratani, Masaharu

    2016-06-21

    The advanced materials process by non-thermal plasmas with a high plasma density allows the synthesis of small-to-big sized Si quantum dots by combining low-temperature deposition with superior crystalline quality in the background of an amorphous hydrogenated silicon nitride matrix. Here, we make quantum dot thin films in a reactive mixture of ammonia/silane/hydrogen utilizing dual-frequency capacitively coupled plasmas with high atomic hydrogen and nitrogen radical densities. Systematic data analysis using different film and plasma characterization tools reveals that the quantum dots with different sizes exhibit size dependent film properties, which are sensitively dependent on plasma characteristics. These films exhibit intense photoluminescence in the visible range with violet to orange colors and with narrow to broad widths (∼0.3-0.9 eV). The observed luminescence behavior can come from the quantum confinement effect, quasi-direct band-to-band recombination, and variation of atomic hydrogen and nitrogen radicals in the film growth network. The high luminescence yields in the visible range of the spectrum and size-tunable low-temperature synthesis with plasma and radical control make these quantum dot films good candidates for light emitting applications. PMID:27226277

  7. Operation and test of hybridized silicon p-i-n arrays using open-source array control hardware and software

    NASA Astrophysics Data System (ADS)

    Moore, Andrew C.; Ninkov, Zoran; Burley, Gregory S.; Forrest, William J.; McMurtry, Craig W.; Avery, Lars E.

    2003-05-01

    A system for controlling and testing high-resolution non-destructive astronomical imagers was constructed using open-source components, both hardware and software. The open-source electronics design, originated by Carnegie Observatories (OCIW) for CCD cameras, was modified, assembled, and augmented with new circuitry which facilitates monitoring of voltages and currents. The electronics was run from Python user interface software based on a design from the University of Rochester. This new software utilized the Numarray and pyFITS modules developed at the Space Telescope Science Institute (STScI). Interfacing to the "dv" FITS image analysis package from the NASA IRTF was also implemented. Python (the STScI language of choice) was used as the primary language for systems integration, scripts for data acquisition, and scripts for data analysis. The DSP clocking software was a mixture of C and Motorola 56303 assembly. An interrupt-driven kernel-mode PCI device driver for Red Hat Linux was written in C, and used the PC processor and memory for image processing and acquisition. Two 1Κ × 1Κ Raytheon SB226-based hybridized silicon p-i-n arrays were operated and tested with the new system at temperatures as low as 10K. Signal path gain, node capacitance, well depth, dark current, and MTF measurements were made and are presented here.

  8. Improvement of the voltage-controlled negative resistance of a porous silicon emitter using cathode reduction and electro-pretreatment

    NASA Astrophysics Data System (ADS)

    He, Li; Zhang, Xiaoning; Wang, Wenjiang; Zhao, Xiaoning

    2016-09-01

    A new composite treatment method combining cathode reduction (CR) and electro-pretreatment (EP) is proposed to improve the voltage-controlled negative resistance (VCNR) of porous silicon (PS) emitters. Four groups of PS emitters were treated, with nothing, CR, EP, and a combination of CR and EP, during different preparation stages. The experimental results indicate that both CR and EP improved the VCNR property and the emission characteristics of the PS emitter. The most favorable results occurred for the electron emitter treated with a combination of CR–EP. A peak-to-valley current ratio of 1.06 and an emission current density of 150 µA cm‑2, which are the lowest value and approximately twice that of other samples, respectively, were obtained. In addition, the operating stability of the PS emitter also improved significantly compared with the two methods alone. Scanning electron microscopy, atomic force microscopy, and energy dispersive x-ray spectrometry results demonstrate that the improvements of the VCNR and the emission characteristics of PS emitters are due to the content variation of defects, impurities, and unstable microstructures in the PS layer under the influence of CR and EP. The mechanism of VCNR behavior is explained by a proposed energy band model, which is consistent with the experimental results.

  9. Controlled aluminum-induced crystallization of an amorphous silicon thin film by using an oxide-layer diffusion barrier

    NASA Astrophysics Data System (ADS)

    Hwang, Ji-Hyun; Kwak, Hyunmin; Kwon, Myeung Hoi

    2014-03-01

    Aluminum-induced crystallization (AIC) of amorphous silicon with an Al2O3 diffusion barrier was investigated for controlling Si crystallization and preventing layer exchange during the annealing process. An Al2O3 layer was deposited between the a-Si and the Al films (a-Si/Al2O3/Al/Glass) and was blasted with an air spray gun with alumina beads to form diffusion channels between the Si and the Al layers. During the annealing process, small grain Si x Al seeds were formed at the channels. Then, the Al2O3 diffusion barrier was restructured to close the channels and prevent further diffusion of Al atoms into the a-Si layer. A polycrystalline Si film with (111), (220) and (311) crystallization peaks in the X-ray diffraction pattern was formed by annealing at 560 °C in a conventional furnace. That film showed a p-type semiconducting behavior with good crystallinity and a large grain size of up to 14.8 µm. No layer conversion occurred between the Si and the Al layers, which had been the fundamental obstacle to the applications in the crystallization of a-Si films by using the AIC method.

  10. Design and test of a 2.25-MW transformer rectifier assembly

    NASA Technical Reports Server (NTRS)

    Cormier, R.; Daeges, J.

    1989-01-01

    A new 2.25-MW transformer rectifier assembly was fabricated for DSS-13 at Goldstone, California. The transformer rectifier will provide constant output power of 2.25 MW at any voltage from 31 kV to 125 kV. This will give a new capability of 1 MW of RF power at X-band, provided appropriate microwave tubes are in the power amplifier. A description of the design and test results is presented.

  11. New Analysis and Design of a RF Rectifier for RFID and Implantable Devices

    PubMed Central

    Liu, Dong-Sheng; Li, Feng-Bo; Zou, Xue-Cheng; Liu, Yao; Hui, Xue-Mei; Tao, Xiong-Fei

    2011-01-01

    New design and optimization of charge pump rectifiers using diode-connected MOS transistors is presented in this paper. An analysis of the output voltage and Power Conversion Efficiency (PCE) is given to guide and evaluate the new design. A novel diode-connected MOS transistor for UHF rectifiers is presented and optimized, and a high efficiency N-stage charge pump rectifier based on this new diode-connected MOS transistor is designed and fabricated in a SMIC 0.18-μm 2P3M CMOS embedded EEPROM process. The new diode achieves 315 mV turn-on voltage and 415 nA reverse saturation leakage current. Compared with the traditional rectifier, the one based on the proposed diode-connected MOS has higher PCE, higher output voltage and smaller ripple coefficient. When the RF input is a 900-MHz sinusoid signal with the power ranging from −15 dBm to −4 dBm, PCEs of the charge pump rectifier with only 3-stage are more than 30%, and the maximum output voltage is 5.5 V, and its ripple coefficients are less than 1%. Therefore, the rectifier is especially suitableto passive UHF RFID tag IC and implantable devices. PMID:22163968

  12. New analysis and design of a RF rectifier for RFID and implantable devices.

    PubMed

    Liu, Dong-Sheng; Li, Feng-Bo; Zou, Xue-Cheng; Liu, Yao; Hui, Xue-Mei; Tao, Xiong-Fei

    2011-01-01

    New design and optimization of charge pump rectifiers using diode-connected MOS transistors is presented in this paper. An analysis of the output voltage and Power Conversion Efficiency (PCE) is given to guide and evaluate the new design. A novel diode-connected MOS transistor for UHF rectifiers is presented and optimized, and a high efficiency N-stage charge pump rectifier based on this new diode-connected MOS transistor is designed and fabricated in a SMIC 0.18-μm 2P3M CMOS embedded EEPROM process. The new diode achieves 315 mV turn-on voltage and 415 nA reverse saturation leakage current. Compared with the traditional rectifier, the one based on the proposed diode-connected MOS has higher PCE, higher output voltage and smaller ripple coefficient. When the RF input is a 900-MHz sinusoid signal with the power ranging from -15 dBm to -4 dBm, PCEs of the charge pump rectifier with only 3-stage are more than 30%, and the maximum output voltage is 5.5 V, and its ripple coefficients are less than 1%. Therefore, the rectifier is especially suitable to passive UHF RFID tag IC and implantable devices. PMID:22163968

  13. Characteristics of degenerately doped silicon for spectral control in thermophotovoltaic systems

    SciTech Connect

    Ehsani, H.; Bhat, I.; Borrego, J.; Gutmann, R.; Brown, E.; Dzeindziel, R.; Freeman, M.; Choudhury, N.

    1995-07-01

    Heavily doped Si was investigated for use as spectral control filter in thermal photovoltaic (TPV) system. These filters should reflect radiation at 4 {micro}m and above and transmit radiation at 2 {micro}m and below. Two approaches have been used for introducing impurities into Si to achieve high doping concentration. One was the diffusion technique, using spin-on dopants. The plasma wavelength ({lambda}{sub p}) of these filters could be adjusted by controlling the diffusion conditions. The minimum plasma wavelength achieved was 4.8 {micro}m. In addition, a significant amount of absorption was observed for the wavelength 2 {micro}m and below. The second approach was doping by ion implantation followed by thermal annealing with a capped layer of doped glass. Implantation with high dosage of B and As followed by high temperature annealing (> 1,000 C) resulted in a plasma wavelength that could be controlled between 3.5 and 6 {micro}m. The high temperature annealing (> 1,000 C) that was necessary to activate the dopant atoms and to heal the implantation damage, also caused significant absorption at 2 {micro}m. For phosphorus implanted Si, a moderate temperature (800--900 C) was sufficient to activate most of the phosphorus and to heal the implantation damage. The position of the plasma turn-on wavelength for an implantation dose of 2 {times} 10{sup 16} cm{sup {minus}2} of P was at 2.9 {micro}m. The absorption at 2 {micro}m was less than 20% and the reflection at 5 {micro}m was about 70%.

  14. Commissioning of the control and data acquisition electronics for the CDF Silicon Vertex Detector

    SciTech Connect

    Tkaczyk, S.M.; Turner, K.J.; Nelson, C.A.; Shaw, T.M.; Wesson, T.R.; Bailey, M.W.; Kruse, M.C.; Castro, A.

    1991-11-01

    The SVX data acquisition system includes three components: a Fastbus Sequencer, an SVX Rabbit Crate Controller and a Digitizer. These modules are integrated into the CDF DAQ system and operate the readout chips. The results of the extensive functional tests of the SVX modules are reported. We discuss the stability of the Sequencers, systematic differences between them and methods of synchronization with the Tevatron beam crossings. The Digitizer ADC calibration procedure run on the microsequencer is described. The microsequencer code used for data taking and SVX chip calibration modes is described. Measurements of the SVX data scan time are discussed.

  15. Polarization beam splitters, converters and analyzers based on a metasurface composed of regularly arranged silicon nanospheres with controllable coupling strength.

    PubMed

    Xiang, Jin; Li, Jinxiang; Li, Hui; Zhang, Chengyun; Dai, Qiaofeng; Tie, Shaolong; Lan, Sheng

    2016-05-30

    A metasurface composed of regularly arranged silicon (Si) nanospheres (NSs) with coupling was investigated both theoretically and numerically based on the Mie theory, the simple Lorentz line shape model and the finite-difference time-domain technique. By deliberately controlling the coupling strength between Si NSs through the design of the lattice constants of a rectangular lattice, polarization beam splitters, converters and analyzers with good performance can be successfully constructed. A square lattice as well as a large incidence angle was employed to build the polarization beam splitters and converters. At an incidence angle of 80°, the polarization beam splitters can completely reflect the s-polarized light and transmit the p-polarized light in a wavelength region of 510-620 nm. For a circularly polarized light incident on the polarization converters, one can get s-polarized light in the reflection direction and p-polarized light in the transmission direction. For the polarization beam analyzers, a rectangular lattice with deliberately chosen lattice constants was employed and the transmissivity of a linearly polarized light can be continuously adjusted from 0 to ~0.90 by simply rotating the metasurface. We revealed that the broadening of either the electric dipole resonance or the magnetic dipole resonance or both of them, which is induced by the asymmetric coupling of Si NSs, is responsible for the modification in the transmissivity spectrum of the metasurface. Our findings provide a guideline for designing photonic devices based on the metasurfaces composed of Si NSs with controllable coupling strength. PMID:27410070

  16. Formation mechanism and control of MgO·Al2O3 inclusions in non-oriented silicon steel

    NASA Astrophysics Data System (ADS)

    Sun, Yan-hui; Zeng, Ya-nan; Xu, Rui; Cai, Kai-ke

    2014-11-01

    On the basis of the practical production of non-oriented silicon steel, the formation of MgO·Al2O3 inclusions was analyzed in the process of "basic oxygen furnace (BOF) → RH → compact strip production (CSP)". The thermodynamic and kinetic conditions of the formation of MgO·Al2O3 inclusions were discussed, and the behavior of slag entrapment in molten steel during RH refining was simulated by computational fluid dynamics (CFD) software. The results showed that the MgO/Al2O3 mass ratio was in the range from 0.005 to 0.017 and that MgO·Al2O3 inclusions were not observed before the RH refining process. In contrast, the MgO/Al2O3 mass ratio was in the range from 0.30 to 0.50, and the percentage of MgO·Al2O3 spinel inclusions reached 58.4% of the total inclusions after the RH refining process. The compositions of the slag were similar to those of the inclusions; furthermore, the critical velocity of slag entrapment was calculated to be 0.45 m·s-1 at an argon flow rate of 698 L·min-1, as simulated using CFD software. When the test steel was in equilibrium with the slag, [Mg] was 0.00024wt%-0.00028wt% and [Al]s was 0.31wt%-0.37wt%; these concentrations were theoretically calculated to fall within the MgO·Al2O3 formation zone, thereby leading to the formation of MgO·Al2O3 inclusions in the steel. Thus, the formation of MgO·Al2O3 inclusions would be inhibited by reducing the quantity of slag entrapment, controlling the roughing slag during casting, and controlling the composition of the slag and the MgO content in the ladle refractory.

  17. Single delayed rectifier channels in frog atrial cells. Effects of beta-adrenergic stimulation.

    PubMed Central

    Duchatelle-Gourdon, I; Hartzell, H C

    1990-01-01

    The patch-clamp technique with two pipettes was used to record single delayed K+ channels (cell-attached electrode) and to control the potential and the composition of the intracellular compartment (whole-cell electrode). With 30 microM cAMP in the cell and physiological potassium concentrations inside and outside the patch, a channel carrying an outward current was characterized. Its open probability was very low and the channel was recorded in only 5% of patches under control conditions. Increasing intracellular cAMP increased the probability of finding a channel in a patch 10-fold. The channel had the characteristics expected of a delayed rectifier channel. The time-course of its ensemble average resembled the whole-cell current in the same cell. The current-voltage relationship exhibited inward rectification, with a slope conductance of 20 pS in the linear portion and a reversal potential close to EK. Both the open- and the closed-time distributions were described by the sum of two exponentials, suggesting a complicated gating scheme involving two closed states and two open states. The beta-adrenergic stimulation did not change the conductance of the channel, but increased its probability of opening. Images FIGURE 1 FIGURE 2 FIGURE 4 PMID:2160847

  18. Innovative Switching Sequences for Sensorless Capacitor Voltage Balancing of Three-Phase NPC Rectifier

    NASA Astrophysics Data System (ADS)

    Langer, Nitin; Bhat, Abdul Hamid; Agarwal, Pramod

    2014-01-01

    This paper presents a modulation strategy for self-balancing of capacitor voltages of three-phase neutral-point clamped bi-directional rectifier (without feedback controller and sensors). It is identified that regions within a sector are divided into two categories: (a) One small vector among three selected vectors and (b) Two small vectors among three selected vectors. For category (a) positive and negative commutation state of small vector is implemented for equal duty cycle but for category (b) positive and negative commutation state of small vectors is implemented for unequal duty cycle. Based on this observation, an innovative idea is executed to remove these discrepancies. The innovative optimized space vector switching sequences negative and positive commutation state of both the small vectors are implemented for equal duty cycle during each sampling period resulting in self-balancing of DC-bus capacitors with much reduced ripples under steady-state and dynamic load conditions for both rectification and inversion mode of operation. The converter exhibits excellent performance in terms of other critical parameters like unity input power factor, low input current THD, minimum possible switching losses, reduced-rippled and well-regulated DC voltage. The proposed control algorithm is tested through exhaustive simulation of converter using MATLAB Simulink software.

  19. Operational research on a high-T c rectifier-type superconducting flux pump

    NASA Astrophysics Data System (ADS)

    Geng, Jianzhao; Matsuda, K.; Fu, Lin; Shen, Boyang; Zhang, Xiuchang; Coombs, T. A.

    2016-03-01

    High-T c superconducting (HTS) flux pumps are capable of injecting flux into a superconducting circuit, which can achieve persistent current operation for HTS magnets. In this paper, we studied the operation of a rectifier-type HTS flux pump. The flux pump employs a transformer to generate high alternating current in its secondary winding, which is connected to an HTS load shorted by an HTS bridge. A high frequency ac field is intermittently applied perpendicular to the bridge, thus, generating flux flow. The dynamic resistance caused by the flux flow ‘rectifies’ the secondary current, resulting in a direct current in the load. We have found that the final load current can easily be controlled by changing the phase difference between the secondary current and the bridge field. The bridge field of frequency ranging from 10 to 40 Hz and magnitude ranging from 0 to 0.66 T was tested. Flux pumping was observed for field magnitudes of 50 mT or above. We have found that both higher field magnitude and higher field frequency result in a faster pumping speed and a higher final load current. This can be attributed to the influence of dynamic resistance. The dynamic resistance measured in the flux pump is comparable with the theoretical calculation. The experimental results fully support a first order circuit model. The flux pump is much more controllable than the traveling wave flux pumps based on permanent magnets, which makes it promising for practical use.

  20. BOREAS TE-18, 30-m, Radiometrically Rectified Landsat TM Imagery

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Knapp, David

    2000-01-01

    The BOREAS TE-18 team used a radiometric rectification process to produce standardized DN values for a series of Landsat TM images of the BOREAS SSA and NSA in order to compare images that were collected under different atmospheric conditions. The images for each study area were referenced to an image that had very clear atmospheric qualities. The reference image for the SSA was collected on 02-Sep-1994, while the reference image for the NSA was collected on 21-Jun-1995. the 23 rectified images cover the period of 07-Jul-1985 to 18 Sep-1994 in the SSA and from 22-Jun-1984 to 09-Jun-1994 in the NSA. Each of the reference scenes had coincident atmospheric optical thickness measurements made by RSS-11. The radiometric rectification process is described in more detail by Hall et al. (199 1). The original Landsat TM data were received from CCRS for use in the BOREAS project. The data are stored in binary image-format files. Due to the nature of the radiometric rectification process and copyright issues, these full-resolution images may not be publicly distributed. However, a spatially degraded 60-m resolution version of the images is available on the BOREAS CD-ROM series. See Sections 15 and 16 for information about how to possibly acquire the full resolution data. Information about the full-resolution images is provided in an inventory listing on the CD-ROMs. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  1. BOREAS TE-18, 60-m, Radiometrically Rectified Landsat TM Imagery

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Knapp, David

    2000-01-01

    The BOREAS TE-18 team used a radiometric rectification process to produce standardized DN values for a series of Landsat TM images of the BOREAS SSA and NSA in order to compare images that were collected under different atmospheric conditions. The images for each study area were referenced to an image that had very clear atmospheric qualities. The reference image for the SSA was collected on 02-Sep-1994, while the reference image for the NSA was collected on 2 1 Jun-1995. The 23 rectified images cover the period of 07-Jul-1985 to 18-Sep-1994 in the SSA and 22-Jun-1984 to 09-Jun-1994 in the NSA. Each of the reference scenes had coincident atmospheric optical thickness measurements made by RSS-11. The radiometric rectification process is described in more detail by Hall et al. (1991). The original Landsat TM data were received from CCRS for use in the BOREAS project. Due to the nature of the radiometric rectification process and copyright issues, the full-resolution (30-m) images may not be publicly distributed. However, this spatially degraded 60-m resolution version of the images may be openly distributed and is available on the BOREAS CD-ROM series. After the radiometric rectification processing, the original data were degraded to a 60-m pixel size from the original 30-m pixel size by averaging the data over a 2- by 2-pixel window. The data are stored in binary image-format files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  2. Control of the micrometric scale morphology of silicon nanowires through ion irradiation-induced metal dewetting

    NASA Astrophysics Data System (ADS)

    Lo Savio, R.; Repetto, L.; Guida, P.; Angeli, E.; Firpo, G.; Volpe, A.; Ierardi, V.; Valbusa, U.

    2016-08-01

    We propose ion-induced dewetting of Au thin films as a mechanism to modify and control the morphology of Si nanowires formed through metal-assisted chemical etching. We show that the patterns formed upon irradiation resemble those typical of dewetting phenomena, with a characteristic length in the nanometer range. Irradiated Au films are then used as a template for the fabrication of Si nanowires, and we show that a long-range order exists also in etched substrates, although at much longer length scales in the micrometer range. Investigation of the optical properties reveals that the Si nanowires emit broadband photoluminescence peaked at 700 nm. The proposed synthesis method allows tuning the morphological features of the nanowire bundles at the nanoscale without affecting the optical properties. This approach can be exploited for the engineering of nanowires-based devices where the morphological features become important.

  3. Silicon control of strontium and cesium partitioning in hydroxide-weathered sediments

    NASA Astrophysics Data System (ADS)

    Chorover, Jon; Choi, Sunkyung; Rotenberg, Paula; Serne, R. Jeff; Rivera, Nelson; Strepka, Caleb; Thompson, Aaron; Mueller, Karl T.; O'Day, Peggy A.

    2008-04-01

    Cation partitioning and speciation in an aqueous soil suspension may depend on the coupling of reaction time, sorbate amount and mineral weathering reactions. These factors were varied in sediment suspension experiments to identify geochemical processes that affect migration of Sr 2+ and Cs + introduced to the subsurface by caustic high level radioactive waste (HLRW). Three glacio-fluvial and lacustrine sediments from the Hanford Site (WA, USA) were subjected to hyperalkaline (pH > 13), Na-Al-NO 3-OH solution conditions within a gradient field of (i) sorptive concentration (10 -5-10 -3 m) and (ii) reaction time (0-365 d). Strontium uptake ( qSr) exceeded that of cesium at nearly all reaction times. Sorbent affinity for both Cs + and Sr 2+ increased with clay plus silt content at early times, but a prolonged slow uptake process was observed over the course of sediment weathering that erased the texture effect for Sr 2+; all sediments showed similar mass normalized uptake after several months of reaction time. Strontium became progressively recalcitrant to desorption after 92 d, with accumulation and aging of neoformed aluminosilicates. Formation of Cs + and Sr 2+-containing cancrinite and sodalite was observed after 183 d by SEM and synchrotron μ-XRF and μ-XRD. EXAFS data for qSr ≈ 40 mmol kg -1 showed incorporation of Sr 2+ into both feldspathoid and SrCO 3(s) coordination environments after one year. Adsorption was predominant at early times and low sorbate amount, whereas precipitation, controlled largely by sediment Si release, became increasingly important at longer times and higher sorbate amount. Kinetics of contaminant desorption at pH 8 from one year-weathered sediments showed significant dependence on background cation (Ca 2+ versus K +) composition. Results of this study indicate that co-precipitation and ion exchange in neoformed aluminosilicates may be an important mechanism controlling Sr 2+ and Cs + mobility in siliceous sediments impacted by

  4. Iodine 125 Brachytherapy With Vitrectomy and Silicone Oil in the Treatment of Uveal Melanoma: 1-to-1 Matched Case-Control Series

    SciTech Connect

    McCannel, Tara A. McCannel, Colin A.

    2014-06-01

    Purpose: We initially reported the radiation-attenuating effect of silicone oil 1000 centistokes for iodine 125. The purpose of this report was to compare the clinical outcomes in case patients who had iodine 125 brachytherapy with vitrectomy and silicone oil 1000 centistokes with the outcomes in matched control patients who underwent brachytherapy alone. Methods and Materials: Consecutive patients with uveal melanoma who were treated with iodine 125 plaque brachytherapy and vitrectomy with silicone oil with minimum 1-year follow-up were included. Control patients who underwent brachytherapy alone were matched for tumor size, location, and sex. Baseline patient and tumor characteristics and tumor response to radiation, final visual acuity, macular status, central macular thickness by ocular coherence tomography (OCT), cataract progression, and metastasis at last follow-up visit were compared. Surgical complications were also determined. Results: Twenty case patients met the inclusion criteria. The average follow-up time was 22.1 months in case patients and 19.4 months in control patients. The final logMAR vision was 0.81 in case patients and 1.1 in control patients (P=.071); 8 case patients and 16 control patients had abnormal macular findings (P=.011); and the average central macular thickness by OCT was 293.2 μm in case patients and 408.5 μm in control patients (P=.016). Eleven case patients (55%) and 1 control patient (5%) had required cataract surgery at last follow-up (P=.002). Four patients in the case group and 1 patient in the control group experienced metastasis (P=.18). Among the cases, intraoperative retinal tear occurred in 3 patients; total serous retinal detachment and macular hole developed in 1 case patient each. There was no case of rhegmatogenous retinal detachment, treatment failure, or local tumor dissemination in case patients or control patients. Conclusions: With up to 3 years of clinical follow-up, silicone oil during brachytherapy

  5. Surface trimming of silicon photonics devices using controlled reactive ion etching chemistry

    NASA Astrophysics Data System (ADS)

    Chandran, S.; Das, B. K.

    2015-06-01

    Surface trimming of rib waveguides fabricated in 5-μm SOI substrate has been carried out successfully without any significant increase of propagation losses. A reactive ion etching chemistry has been optimized for trimming and an empirical model has been developed to obtain the resulting waveguide geometries. This technique has been used to demonstrate smaller footprint devices like multimode interference based power splitters and ring resonators after defining them photolithographically with relatively large cross-section rib waveguides. We have been also successful to fabricate 2D tapered spot-size converter useful for monolithic integration of waveguides with varying heights and widths. The taper length is again precisely controlled by photolithographic definition. Minimum insertion loss of such a spot-size converter integrated between waveguides with 3-μm height difference has been recorded to be ∼2 dB. It has been also shown that the overall fiber-to-chip coupling loss can be reduced by >3 dB by using such spot-size converters at the input/output side of the waveguides.

  6. Characterization and properties of controlled nucleation thermochemical deposited (CNTD) silicon carbide

    NASA Technical Reports Server (NTRS)

    Dutta, S.; Rice, R. W.; Graham, H. C.; Mendiratta, M. C.

    1978-01-01

    The microstructure of controlled nucleation thermochemical deposition (CNTD) - SiC material was studied and the room temperature and high temperature bend strength and oxidation resistance was evaluated. Utilizing the CNTD process, ultrafine grained (0.01-0.1 mm) SiC was deposited on W - wires (0.5 mm diameter by 20 cm long) as substrates. The deposited SiC rods had superior surface smoothness and were without any macrocolumnar growth commonly found in conventional CVD material. At both room and high temperature (1200 - 1380 C), the CNTD - SiC exhibited bend strength approximately 200,000 psi (1380 MPa), several times higher than that of hot pressed, sintered, or CVD SiC. The excellent retention of strength at high temperature was attributed to the high purity and fine grain size of the SiC deposit and the apparent absence of grain growth at elevated temperatures. The rates of weight change for CNTD - SiC during oxidation were lower than for NC-203 (hot pressed SiC), higher than for GE's CVD - SiC, and considerably below those for HS-130 (hot pressed Si3N4). The high purity, fully dense, and stable grain size CNTD - SiC material shows potential for high temperature structural applications; however problem areas might include: scaling the process to make larger parts, deposition on removable substrates, and the possible residual tensile stress.

  7. D0 Silicon Upgrade: Control Dewar Venturi Calibration Explanation for Toshiba

    SciTech Connect

    Kuwazaki, Andrew; /Fermilab

    1997-01-24

    This document is intended to explain the calibration data for the venturi, FE-3253H, which is installed in the control dewar. Further, this document will help explain how to use the venturi to make mass flow measurements during typical operating conditions. The purpose of the calibration data enclosed from the Colorado Engineering Experiment Station Inc. is to experimentally show that the venturi follows the flow equation which is enclosed as Eq. 7-36 on page 155, from the Applied Fluid Dynamics Handbook. The calibration data serves to show that the Subsonic Venturi, Serial Number 611980-18, produces results predicted by the compressible subsonic flow mass flow rate equation above and to experimentally determine the discharge coefficient C. Colorado Engineering Experiment Station Inc. ran tests at 15 independent differential pressures to conclude that use of this venturi will perform according to the mass flow rate equation. In order to verify the results from the Colorado Engineering Experiment Station Inc. we have provided you with a step-by-step procedure using the values they have chosen.

  8. A Novel Approach of Daunorubicin Application on Formation of Proliferative Retinopathy Using a Porous Silicon Controlled Delivery System: Pharmacodynamics

    PubMed Central

    Hou, Huiyuan; Huffman, Kristyn; Rios, Sandy; Freeman, William R.; Sailor, Michael J.; Cheng, Lingyun

    2015-01-01

    Purpose. Proliferative vitreoretinopathy (PVR) is the most common cause of poor visual outcomes in association with retinal detachment surgeries and ocular trauma. Daunorubicin (DNR) has shown the strongest efficacy in proliferation inhibition in vitro. However, clinical studies have shown only mild effect owing to limitations of narrow therapeutic window and short vitreous half-life. Methods. Three milligrams of DNR-loaded particles were intravitreally injected into 18 pigmented rabbits, and vitreous samples were collected up to 84 days for analysis. Thirty-seven rabbits were used for a dose-escalation (1, 3, 6 mg) safety and efficacy study in a rabbit PVR model using a pretreatment design. Results. Loading efficiency of DNR was 108.55 ± 12 μg per 1 mg particles. Eighty-four days of follow-up did not reveal any adverse reaction. Pharmacokinetic analysis demonstrated a vitreous half-life of 29 days with a maximum DNR concentration of 178 ng/mL and a minimum concentration of 29 ng/mL at day 84. Daunorubicin-loaded porous silicon (pSi) particles were dosed 8 to 9 weeks before PVR induction, and PVR severity score was dose dependent (Spearman ρ = −0.25, P = 0.0005). Proliferative vitreoretinopathy with tractional retinal detachment was 88% in the control group, 63% in the low-dose group, 14% in the medium-dose group, and 0% in the high-dose group (Cochran-Armitage Trend Test, Z = 8.99, ρ = −0.67, P < 0.0001). Conclusions. Daunorubicin-loaded pSi particles can safely reside in the vitreous for at least 3 months. The pSi-based delivery expanded the therapeutic window of DNR by a factor of 862 and drove down the minimum effective concentration by a factor of 175. PMID:25829415

  9. Controlled Directional Motions of Molecular Vehicles, Rotors, and Motors: From Metallic to Silicon Surfaces, a Strategy to Operate at Higher Temperatures.

    PubMed

    Chérioux, Frédéric; Galangau, Olivier; Palmino, Frank; Rapenne, Gwénaël

    2016-06-17

    In the last decade, many nanomachines with controlled molecular motions have been studied, mainly on metallic surfaces, which are easy to obtain very clean, and are stable over months. However, the studies of mechanical properties of nanomachines are mainly performed at very low temperatures, usually between 5 and 80 K, which prevents any kind of applications. In this Minireview, we will present our strategy to operate at higher temperatures, in particular through the use of semiconducting silicon surfaces. We also review our best achievements in the field through some examples of rotating molecular machines that have been designed, synthesized, and studied in our groups. On metallic surfaces, the nanovehicles are molecules with two or four triptycenes as wheels and the molecular motor is built around a ruthenium organometallic center with a piano-stool geometry and peripheric ferrocenyl groups. On semiconducting silicon surfaces, vehicles are also made from triptycene fragments and the rotor is a pentaphenylbenzene molecule. PMID:26604073

  10. A Benchtop Closed-loop System Controlled by a Bio-Inspired Silicon Implementation of the Pancreatic β Cell

    PubMed Central

    Oliver, Nick; Georgiou, Pantelis; Johnston, Desmond; Toumazou, Christofer

    2009-01-01

    The normal pancreatic β-cell membrane depolarizes in response to increasing concentrations of glucose in a bursting pattern. At <7 mM (126 mg/dl), the cell is electrically silent. The bursting pulse width increases as glucose rises >7 mM (126 mg/dl) until a continuous train of bursting is seen at >25 mM (450 mg/dl). A bio-inspired silicon device has been developed using analogue electronics to implement membrane depolarization of the β cell. The device is ultralow powered, miniaturized (5 × 5 mm), and produces a bursting output identical to that characterized in electrophysiological studies. Objective The goal of this study was to demonstrate the ability of silicon implementation of β-cell electrophysiology to respond to a simulated glucose input and to drive an infusion pump in vitro. Method The silicon device response to a current source was recorded at varying simulated glucose concentrations. Subsequently, the bursting response to a changing analyte concentration measured by an amperometric enzyme electrode was converted to a voltage, driving a syringe pump loaded with a 50-ml syringe containing water. Results Bursting responses are comparable to those recorded in electrophysiology. Silicon β-cell implementation bursts with a pulse width proportional to concentration and is able to drive an infusion pump. Conclusion This is the first in vitro demonstration of closed loop insulin delivery utilizing miniaturized silicon implementation of β-cell physiology in analogue electronics. PMID:20144397

  11. The fabrication of highly ordered block copolymer micellar arrays: control of the separation distances of silicon oxide dots.

    PubMed

    Yoo, Hana; Park, Soojin

    2010-06-18

    We demonstrate the fabrication of highly ordered silicon oxide dotted arrays prepared from polydimethylsiloxane (PDMS) filled nanoporous block copolymer (BCP) films and the preparation of nanoporous, flexible Teflon or polyimide films. Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) films were annealed in toluene vapor to enhance the lateral order of micellar arrays and were subsequently immersed in alcohol to produce nano-sized pores, which can be used as templates for filling a thin layer of PDMS. When a thin layer of PDMS was spin-coated onto nanoporous BCP films and thermally annealed at a certain temperature, the PDMS was drawn into the pores by capillary action. PDMS filled BCP templates were exposed to oxygen plasma environments in order to fabricate silicon oxide dotted arrays. By addition of PS homopolymer to PS-b-P2VP copolymer, the separation distances of micellar arrays were tuned. As-prepared silicon oxide dotted arrays were used as a hard master for fabricating nanoporous Teflon or polyimide films by spin-coating polymer precursor solutions onto silicon patterns and peeling off. This simple process enables us to fabricate highly ordered nanoporous BCP templates, silicon oxide dots, and flexible nanoporous polymer patterns with feature size of sub-20 nm over 5 cm x 5 cm. PMID:20498523

  12. Length dependence of rectification in organic co-oligomer spin rectifiers

    NASA Astrophysics Data System (ADS)

    Gui-Chao, Hu; Zhao, Zhang; Ying, Li; Jun-Feng, Ren; Chuan-Kui, Wang

    2016-05-01

    The rectification ratio of organic magnetic co-oligomer diodes is investigated theoretically by changing the molecular length. The results reveal two distinct length dependences of the rectification ratio: for a short molecular diode, the charge-current rectification changes little with the increase of molecular length, while the spin-current rectification is weakened sharply by the length; for a long molecular diode, both the charge-current and spin-current rectification ratios increase quickly with the length. The two kinds of dependence switch at a specific length accompanied with an inversion of the rectifying direction. The molecular ortibals and spin-resolved transmission analysis indicate that the dominant mechanism of rectification suffers a change at this specific length, that is, from asymmetric shift of molecular eigenlevels to asymmetric spatial localization of wave functions upon the reversal of bias. This work demonstrates a feasible way to control the rectification in organic co-oligomer spin diodes by adjusting the molecular length. Project supported by the National Natural Science Foundation of China (Grant No. 11374195), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2014AM017), the Taishan Scholar Project of Shandong Province, China, and the Excellent Young Scholars Research Fund of Shandong Normal University, China.

  13. Surprise signals in the supplementary eye field: rectified prediction errors drive exploration-exploitation transitions.

    PubMed

    Kawaguchi, Norihiko; Sakamoto, Kazuhiro; Saito, Naohiro; Furusawa, Yoshito; Tanji, Jun; Aoki, Masashi; Mushiake, Hajime

    2015-02-01

    Visual search is coordinated adaptively by monitoring and predicting the environment. The supplementary eye field (SEF) plays a role in oculomotor control and outcome evaluation. However, it is not clear whether the SEF is involved in adjusting behavioral modes based on preceding feedback. We hypothesized that the SEF drives exploration-exploitation transitions by generating "surprise signals" or rectified prediction errors, which reflect differences between predicted and actual outcomes. To test this hypothesis, we introduced an oculomotor two-target search task in which monkeys were required to find two valid targets among four identical stimuli. After they detected the valid targets, they exploited their knowledge of target locations to obtain a reward by choosing the two valid targets alternately. Behavioral analysis revealed two distinct types of oculomotor search patterns: exploration and exploitation. We found that two types of SEF neurons represented the surprise signals. The error-surprise neurons showed enhanced activity when the monkey received the first error feedback after the target pair change, and this activity was followed by an exploratory oculomotor search pattern. The correct-surprise neurons showed enhanced activity when the monkey received the first correct feedback after an error trial, and this increased activity was followed by an exploitative, fixed-type search pattern. Our findings suggest that error-surprise neurons are involved in the transition from exploitation to exploration and that correct-surprise neurons are involved in the transition from exploration to exploitation. PMID:25411455

  14. A refined cellular automaton model to rectify impractical vehicular movement behavior

    NASA Astrophysics Data System (ADS)

    Lan, Lawrence W.; Chiou, Yu-Chiun; Lin, Zih-Shin; Hsu, Chih-Cheng

    2009-09-01

    When implementing cellular automata (CA) into a traffic simulation, one common defect yet to be rectified is the abrupt deceleration when vehicles encounter stationary obstacles or traffic jams. To be more in line with real world vehicular movement, this paper proposes a piecewise-linear movement to replace the conventional particle-hopping movement adopted in most previous CA models. Upon this adjustment and coupled with refined cell system, a new CA model is developed using the rationale of Forbes’ et al. car-following concept. The proposed CA model is validated on a two-lane freeway mainline context. It shows that this model can fix the unrealistic deceleration behaviors, and thus can reflect genuine driver behavior in the real world. The model is also capable of revealing Kerner’s three-phase traffic patterns and phase transitions among them. Furthermore, the proposed CA model is applied to simulate a highway work zone wherein traffic efficiency (maximum flow rates) and safety (speed deviations) impacted by various control schemes are tested.

  15. New filter media development for effective control of trimethysilanol (TMS) and related low molecular weight silicon containing organic species in the photobay ambient

    NASA Astrophysics Data System (ADS)

    Grayfer, Anatoly; Belanger, Frank V.; Cate, Phillip; Ruede, David

    2007-03-01

    The authors present results of extensive studies on the chemical behavior of low molecular weight silicon-containing species (LMWS) and associated challenges of their analytical determination and control to prevent adverse influence on critical optical elements of exposure tools. In their paper the authors describe a non-traditional approach to the creation of a TMS gaseous source for filter media development and an engineering solution to the challenge of controlling LMWS - a solution that shows a significant advantage over currently existing approaches.

  16. Composition Comprising Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Mehregany, Mehran (Inventor); Zorman, Christian A. (Inventor); Fu, Xiao-An (Inventor); Dunning, Jeremy L. (Inventor)

    2012-01-01

    A method of depositing a ceramic film, particularly a silicon carbide film, on a substrate is disclosed in which the residual stress, residual stress gradient, and resistivity are controlled. Also disclosed are substrates having a deposited film with these controlled properties and devices, particularly MEMS and NEMS devices, having substrates with films having these properties.

  17. Size control, quantum confinement, and oxidation kinetics of silicon nanocrystals synthesized at a high rate by expanding thermal plasma

    SciTech Connect

    Han, Lihao E-mail: A.H.M.Smets@tudelft.nl; Zeman, Miro; Smets, Arno H. M. E-mail: A.H.M.Smets@tudelft.nl

    2015-05-25

    The growth mechanism of silicon nanocrystals (Si NCs) synthesized at a high rate by means of expanding thermal plasma chemical vapor deposition technique are studied in this letter. A bimodal Gaussian size distribution is revealed from the high-resolution transmission electron microscopy images, and routes to reduce the unwanted large Si NCs are discussed. Photoluminescence and Raman spectroscopies are employed to study the size-dependent quantum confinement effect, from which the average diameters of the small Si NCs are determined. The surface oxidation kinetics of Si NCs are studied using Fourier transform infrared spectroscopy and the importance of post-deposition passivation treatments of hydrogenated crystalline silicon surfaces are demonstrated.

  18. Crystal Structure of the Eukaryotic Strong Inward-Rectifier K[superscript +] Channel Kir2.2 at 3.1 Å Resolution

    SciTech Connect

    Tao, Xiao; Avalos, Jose L.; Chen, Jiayun; MacKinnon, Roderick

    2010-03-29

    Inward-rectifier potassium (K{sup +}) channels conduct K{sup +} ions most efficiently in one direction, into the cell. Kir2 channels control the resting membrane voltage in many electrically excitable cells, and heritable mutations cause periodic paralysis and cardiac arrhythmia. We present the crystal structure of Kir2.2 from chicken, which, excluding the unstructured amino and carboxyl termini, is 90% identical to human Kir2.2. Crystals containing rubidium (Rb{sup +}), strontium (Sr{sup 2+}), and europium (Eu{sup 3+}) reveal binding sites along the ion conduction pathway that are both conductive and inhibitory. The sites correlate with extensive electrophysiological data and provide a structural basis for understanding rectification. The channel's extracellular surface, with large structured turrets and an unusual selectivity filter entryway, might explain the relative insensitivity of eukaryotic inward rectifiers to toxins. These same surface features also suggest a possible approach to the development of inhibitory agents specific to each member of the inward-rectifier K{sup +} channel family.

  19. Reconfigurable Resonant Regulating Rectifier With Primary Equalization for Extended Coupling- and Loading-Range in Bio-Implant Wireless Power Transfer.

    PubMed

    Li, Xing; Meng, Xiaodong; Tsui, Chi-Ying; Ki, Wing-Hung

    2015-12-01

    Wireless power transfer using reconfigurable resonant regulating (R(3)) rectification suffers from limited range in accommodating varying coupling and loading conditions. A primary-assisted regulation principle is proposed to mitigate these limitations, of which the amplitude of the rectifier input voltage on the secondary side is regulated by accordingly adjusting the voltage amplitude Veq on the primary side. A novel current-sensing method and calibration scheme track Veq on the primary side. A ramp generator simultaneously provides three clock signals for different modules. Both the primary equalizer and the R(3) rectifier are implemented as custom integrated circuits fabricated in a 0.35 μm CMOS process, with the global control implemented in FPGA. Measurements show that with the primary equalizer, the workable coupling and loading ranges are extended by 250% at 120 mW load and 300% at 1.2 cm coil distance compared to the same system without the primary equalizer. A maximum rectifier efficiency of 92.5% and a total system efficiency of 62.4% are demonstrated. PMID:26742141

  20. Crystal Structure of the Eukaryotic Strong Inward-Rectifier K+ Channel Kir2.2 at 3.1 Å Resolution

    PubMed Central

    Tao, Xiao; Avalos, Jose L.; Chen, Jiayun; MacKinnon, Roderick

    2010-01-01

    Inward-rectifier potassium (K+) channels conduct K+ ions most efficiently in one direction, into the cell. Kir2 channels control the resting membrane voltage in many electrically excitable cells and heritable mutations cause periodic paralysis and cardiac arrhythmia. We present the crystal structure of Kir2.2 from chicken, which, excluding the unstructured amino and carboxyl termini, is 90% identical to human Kir2.2. Crystals containing rubidium (Rb+), strontium (Sr2+), and europium (Eu3+) reveal binding sites along the ion conduction pathway that are both conductive and inhibitory. The sites correlate with extensive electrophysiological data and provide a structural basis for understanding rectification. The channel’s extracellular surface, with large structured turrets and an unusual selectivity filter entryway, might explain the relative insensitivity of eukaryotic inward rectifiers to toxins. These same surface features also suggest a possible approach to the development of inhibitory agents specific to each member of the inward-rectifier K+ channel family. PMID:20019282

  1. Direct Production of Silicones From Sand

    SciTech Connect

    Larry N. Lewis; F.J. Schattenmann: J.P. Lemmon

    2001-09-30

    Silicon, in the form of silica and silicates, is the second most abundant element in the earth's crust. However the synthesis of silicones (scheme 1) and almost all organosilicon chemistry is only accessible through elemental silicon. Silicon dioxide (sand or quartz) is converted to chemical-grade elemental silicon in an energy intensive reduction process, a result of the exceptional thermodynamic stability of silica. Then, the silicon is reacted with methyl chloride to give a mixture of methylchlorosilanes catalyzed by cooper containing a variety of tract metals such as tin, zinc etc. The so-called direct process was first discovered at GE in 1940. The methylchlorosilanes are distilled to purify and separate the major reaction components, the most important of which is dimethyldichlorosilane. Polymerization of dimethyldichlorosilane by controlled hydrolysis results in the formation of silicone polymers. Worldwide, the silicones industry produces about 1.3 billion pounds of the basic silicon polymer, polydimethylsiloxane.

  2. Patterned porous silicon photonic crystals with modular surface chemistry for spatial control of neural stem cell differentiation.

    PubMed

    Huang, Tiffany H; Pei, Yi; Zhang, Douglas; Li, Yanfen; Kilian, Kristopher A

    2016-06-01

    We present a strategy to spatially define regions of gold and nanostructured silicon photonics, each with materials-specific surface chemistry, for azide-alkyne cycloaddition of different bioactive peptides. Neural stem cells are spatially directed to undergo neurogenesis and astrogenesis as a function of both surface properties and peptide identity. PMID:27173986

  3. Theoretical study on the rectifying performance of organoimido derivatives of hexamolybdates.

    PubMed

    Wen, Shizheng; Yang, Guochun; Yan, Likai; Li, Haibin; Su, Zhongmin

    2013-02-25

    We design a new type of molecular diode, based on the organoimido derivatives of hexamolybdates, by exploring the rectifying performances using density functional theory combined with the non-equilibrium Green's function. Asymmetric current-voltage characteristics were obtained for the models with an unexpected large rectification ratio. The rectifying behavior can be understood by the asymmetrical shift of the transmission peak observed under different polarities. It is interesting to find that the preferred electron-transport direction in our studied system is different from that of the organic D-bridge-A system. The results show that the studied organic-inorganic hybrid systems have an intrinsically robust rectifying ratio, which should be taken into consideration in the design of the molecular diodes. PMID:23303530

  4. Microrectenna: A Terahertz Antenna and Rectifier on a Chip

    NASA Technical Reports Server (NTRS)

    Siegel, Peter

    2007-01-01

    A microrectenna that would operate at a frequency of 2.5 THz has been designed and partially fabricated. The circuit is intended to be a prototype of an extremely compact device that could be used to convert radio-beamed power to DC to drive microdevices (see Figure 1). The microrectenna (see Figure 2) circuit consists of an antenna, a diode rectifier and a DC output port. The antenna consists of a twin slot array in a conducting ground plane (denoted the antenna ground plane) over an enclosed quarter-wavelength-thick resonant cavity (denoted the reflecting ground plane). The circuit also contains a planar high-frequency low-parasitic Schottky-barrier diode, a low-impedance microstrip transmission line, capacitors, and contact beam leads. The entire 3-D circuit is fabricated monolithically from a single GaAs wafer. The resonant cavity renders the slot radiation pattern unidirectional with a half-power beam width of about 65. A unique metal mesh on the rear of the wafer forms the backplate for the cavity but allows the GaAs to be wet etched from the rear surface of the twin slot antennas and ground plane. The beam leads protrude past the edge of the chip and are used both to mount the microrectenna and to make the DC electrical connection with external circuitry. The antenna ground plane and the components on top of it are formed on a 2- m thick GaAs membrane that is grown in the initial wafer MBE (molecular beam epitaxy) process. The side walls of the antenna cavity are not metal coated and, hence, would cause some loss of power; however, the relatively high permittivity (epsilon=13) of the GaAs keeps the cavity modes well confined, without the usual surface-wave losses associated with thick dielectric substrates. The Schottky-barrier diode has the usual submicron dimensions associated with THz operation and is formed in a mesa process above the antenna ground plane. The diode is connected at the midpoint of a microstrip transmission line, which is formed on 1- m

  5. Reversible Cycling of Silicon and Silicon Alloys

    NASA Astrophysics Data System (ADS)

    Obrovac, Mark

    2012-02-01

    Lithium ion batteries typically use a graphite negative electrode. Silicon can store more lithium than any other element and has long been considered as an attractive replacement for graphite. The theoretical lithium storage capacity of silicon is nearly ten times higher than graphite volumetrically and three times higher gravimetrically. The equilibrium Si-Li binary system is well known. Completely new phase behaviors are observed at room temperature. This includes the formation of a new phase, Li15Si4, which is the highest lithium containing phase at room temperature [1]. The formation of Li15Si4 is accompanied by a 280 percent volume expansion of silicon. During de-alloying this phase contracts, forming amorphous silicon. The volume expansion of alloys can cause intra-particle fracture and inter-particle disconnection; leading to loss of cycle life. To overcome issues with volume expansion requires a detailed knowledge of Li-Si phase behavior, careful design of the composition and nanostructure of the alloy and the microstructure of the negative electrode [2]. In this presentation the phase behavior of the Li-Si system will be described. Using this knowledge alone, strategies can be developed so that silicon can be reversibly cycled in a battery hundreds of times. Further increases in energy density and efficiency can be gained by alloying silicon with other elements, while controlling microstructure [2]. Coupled with negative electrode design strategies, practical negative electrodes for lithium ion cells can be developed based on bulk materials, with significant energy density improvement over conventional electrodes. [4pt] [1] M.N. Obrovac and L.J. Krause, J. Electrochem. Soc., 154 (2007) A103. [0pt] [2] M.N. Obrovac, Leif Christensen, Dinh Ba Le, and J.R. Dahn, J. Electrochem. Soc., 154 (2007) A849

  6. Revisiting the Rectifier: New Observations of Covariance Between Terrestrial Carbon Cycling and Boundary Layer Depth (Invited)

    NASA Astrophysics Data System (ADS)

    Denning, S.; McGrath-Spangler, E. L.

    2013-12-01

    Covariance between land-surface carbon fluxes and vertical mixing in the atmosphere is among the strongest determinants of the spatial distribution of atmospheric CO2 in the lower troposphere. Differences in the magnitude of this "CO2 rectifier effect" among different tracer transport models has been shown to explain most of the variability in estimates of terrestrial carbon sinks over the northern (vs tropical) continents. We present a new analysis of the magnitude of the CO2 rectifier using a climatology of PBL depth estimated using vertical profiles of LIDAR backscatter from the CALIPSO satellite. Millions of separate soundings of PBL depth were matched with hourly estimates of photosynthesis and ecosystem respiration from the Simple Biosphere Model (SiB3) at the same locations and times over more than 6 years. Strong covariance between net carbon flux and atmospheric mixing were observed over the northern continents, especially over Boreal Asia. Negative covariance is observed over monsoon regions, which is especially strong over India. Covariance of net carbon flux with the reciprocal of PBL depth has the units of CO2 tendency (ppm per month), and can be expressed as rectifier forcing. Satellite sampling of this quantity reveals spatially-coherent patterns as strong as +/- 10 ppm per month over Siberia and India. We computed rectifier forcing with NASA's Modern Era Reanalysis (MERRA) for the same locations and times sampled by CALIPSO from 2006-2012. Comparison of the MERRA and CALIPSO data reveal that the spatial patterns and magnitudes are similar over the northern continents, but much weaker in MERRA than CALIPSO over the tropics. Using MERRA to compute the rectifier effect for SiB fluxes in GEOS-Chem allows us to establish a quantitative relationship between rectifier forcing and response that is evaluated against the CALIPSO boundary layer data. We propose a framework for model intercomparison and evaluation that can leverage the rich new data set.

  7. Preventing Freezeup in Silicon Ribbon Growth

    NASA Technical Reports Server (NTRS)

    Mackintosh, B.

    1983-01-01

    Carefully-shaped heat conductor helps control thermal gradients crucial to growth of single-crystal silicon sheets for solar cells. Ends of die through which silicon sheet is drawn as ribbon from molten silicon. Profiled heat extractor prevents ribbon ends from solidifying prematurely and breaking.

  8. Recovery Act: High-Efficiency, Wideband Three-Phase Rectifiers and Adaptive Rectifier Management for Telecomm Central Office and Large Data Center Applications

    SciTech Connect

    Mark A. Johnson

    2012-06-29

    Lineage Power and Verizon teamed up to address a DOE funding opportunity focused on improving the power conversion chain in telecommunications facilities and data centers. The project had three significant elements: the design and development of high efficiency and high power three-phase rectifiers by Lineage Power, design and development of software to optimize overall plant energy efficiency by Lineage Power, and a field trial in active Verizon telecommunications facilities where energy consumption was measured before and after efficiency upgrades.

  9. Molecular Basis of Cardiac Delayed Rectifier Potassium Channel Function and Pharmacology.

    PubMed

    Wu, Wei; Sanguinetti, Michael C

    2016-06-01

    Human cardiomyocytes express 3 distinct types of delayed rectifier potassium channels. Human ether-a-go-go-related gene (hERG) channels conduct the rapidly activating current IKr; KCNQ1/KCNE1 channels conduct the slowly activating current IKs; and Kv1.5 channels conduct an ultrarapid activating current IKur. Here the authors provide a general overview of the mechanistic and structural basis of ion selectivity, gating, and pharmacology of the 3 types of cardiac delayed rectifier potassium ion channels. Most blockers bind to S6 residues that line the central cavity of the channel, whereas activators interact with the channel at 4 symmetric binding sites outside the cavity. PMID:27261821

  10. Rectifying properties of magnetite-based Schottky diode and the effects of magnetic field

    NASA Astrophysics Data System (ADS)

    Chen, Y. Z.; Sun, J. R.; Xie, Y. W.; Wang, D. J.; Lu, W. M.; Liang, S.; Shen, B. G.

    2007-04-01

    Rectifying properties, with and without magnetic field, of a high quality Fe3O4/SrTiO3:Nb Schottky diode have been experimentally studied. The junction exhibits an excellent rectifying behavior both below and above the Verwey temperature (TV) of Fe3O4. Magnetic field has a weak but visible effect on the transport process of the junction, producing a negative magnetoresistance for T TV. Based on an analysis of the current-voltage characteristics, the spin polarization of Fe3O4 has been deduced. It is a strong function of temperature, varying between -78% and 18%.

  11. Patterned porous silicon photonic crystals with modular surface chemistry for spatial control of neural stem cell differentiation

    NASA Astrophysics Data System (ADS)

    Huang, Tiffany H.; Pei, Yi; Zhang, Douglas; Li, Yanfen; Kilian, Kristopher A.

    2016-05-01

    We present a strategy to spatially define regions of gold and nanostructured silicon photonics, each with materials-specific surface chemistry, for azide-alkyne cycloaddition of different bioactive peptides. Neural stem cells are spatially directed to undergo neurogenesis and astrogenesis as a function of both surface properties and peptide identity.We present a strategy to spatially define regions of gold and nanostructured silicon photonics, each with materials-specific surface chemistry, for azide-alkyne cycloaddition of different bioactive peptides. Neural stem cells are spatially directed to undergo neurogenesis and astrogenesis as a function of both surface properties and peptide identity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08327c

  12. Design and Modelling of a Silicon Optical MEMS Switch Controlled by Magnetic Field Generated by a Plain Coil

    NASA Astrophysics Data System (ADS)

    Golebiowski, J.; Milcarz, Sz

    2014-04-01

    Optical switches can be made as a silicon cantilever with a magnetic layer. Such a structure is placed in a magnetic field of a planar coil. There is a torque deflecting the silicon beam with NiFe layer depending on a flux density of the magnetic field. The study shows an analysis of ferromagnetic layer parameters, beam's dimensions on optical switch characteristics. Different constructions of the beams were simulated for a range of values of magnetic field strength from 100 to 1000 A/m. An influence of the actuators parameters on characteristics was analysed. The loss of stiffness of the beam caused by specific constructions effected in displacements reaching 85 nm. Comsol Multiphysics 4.3b was used for the simulations.

  13. A novel inward-rectifying K+ current with a cell-cycle dependence governs the resting potential of mammalian neuroblastoma cells.

    PubMed Central

    Arcangeli, A; Bianchi, L; Becchetti, A; Faravelli, L; Coronnello, M; Mini, E; Olivotto, M; Wanke, E

    1995-01-01

    1. Human and murine neuroblastoma cell lines were used to investigate, by the whole-cell patch-clamp technique, the properties of a novel inward-rectifying K+ current (IIR) in the adjustment of cell resting potential (Vrest), which was in the range -40 to -20 mV. 2. When elicited from a holding potential of 0 mV, IIR was completely inactivated with time constants ranging from 13 ms at -140 mV to 4.5 s at -50 mV. The steady-state inactivation curve (h(V)) was found to be independent of [Na+]o and [K+]o (2-80 mM) and could be fitted to a Boltzmann curve with a steep slope factor of 5-6, and a V1/2 around Vrest. Divalent ion-free extracellular solutions shifted h(V) to the left by about 28 mV. 3. Peak chord conductance, whose maximal value was approximately proportional to the square root of [K+]o, could be fitted to a Boltzmann curve independently of [K+]o, with a V1/2 value around -48 mV and a slope factor of 18. Extracellular Cs+ and Ba2+ blocked the IIR in a concentration- and voltage-dependent manner, but Ba2+ was less effective than it is on classical inward-rectifier channels. 4. Under control culture conditions the values of Vrest and V1/2 of h(V) varied widely among cells. The knowledge of V1/2 proved crucial or the theoretical prediction of Vrest. After cell synchronization in the G0-G1 phase of the cell cycle, or at the G1-S boundaries, the cells reduced their variability of h(V). The same occurred after cell synchronization in G1 by treatment with retinoic acid. 5. The experimental data could be fitted to a classical model of an inward rectifier, after removing the dependence of conductance activation on (V-EK), and incorporating an inactivation with an intrinsic voltage dependence. Moreover, the model predicts, for this novel inward rectifier and in contrast with the classical inward rectifier, the incapacity of maintaining, in physiological media, a Vrest more negative than -35 to -40 mV, which is an important feature of cancer cells. PMID:8847640

  14. Differential dopaminergic regulation of inwardly rectifying potassium channel mediated subthreshold dynamics in striatal medium spiny neurons.

    PubMed

    Zhao, Bo; Zhu, Junling; Dai, Dongqing; Xing, Junling; He, Jiahou; Fu, Zhanyan; Zhang, Lei; Li, Zhuyi; Wang, Wenting

    2016-08-01

    The dorsal striatum plays a key role in motor control and cognitive processes. Proper functioning of the striatum relies on the fine dynamic balance between the direct pathway projection medium spiny neurons (MSNs) that express D1 dopamine receptor (D1 MSNs) and indirect pathway projection MSNs that express D2 dopamine receptor (D2 MSNs). The inwardly rectifying K(+) channels (Kir), which express on both D1 and D2 MSNs, participate in the subthreshold dynamics including the membrane resonance and dendritic integration. However, it remains unclear whether dopamine differentially regulates Kir mediated subthreshold dynamics in two subtypes MSNs. Using transgenic mice that express either tdTomato in D1 MSNs or eGFP in D2 MSNs, we explored the Kir mediated subthreshold dynamics in D1 or D2 MSNs with whole cell patch clamp recording in acute brain slices. We found that D1 receptor agonist increased the Kir current while D2 receptor activation decreased the Kir conductance. The dopamine regulation of the Kir enhanced the resonant frequency and reduced the resonant impedance of D1 MSNs. The converse is ture for D2 MSNs. It also caused an opposing effect on dendritic integration between D1 and D2 MSNs, which can promote stability of the two pathways. The D1 receptor activation modulated Kir through cAMP-PKA signaling, whereas the D2 receptor modulated Kir through PLC-PKC signaling. Our findings demonstrated the differential dopaminergic regulation role of Kir, which mediates distinct subthreshold dynamics, and thus, contributes to the role of dopamine in fine tuning the balance of the striatal direct and indirect pathway activities. PMID:27018450

  15. Involvement of inward rectifier and M-type currents in carbachol-induced epileptiform synchronization.

    PubMed

    Cataldi, Mauro; Panuccio, Gabriella; Cavaccini, Anna; D'Antuono, Margherita; Taglialatela, Maurizio; Avoli, Massimo

    2011-03-01

    Exposure to cholinergic agonists is a widely used paradigm to induce epileptogenesis in vivo and synchronous activity in brain slices maintained in vitro. However, the mechanisms underlying these effects remain unclear. Here, we used field potential recordings from the lateral entorhinal cortex in horizontal rat brain slices to explore whether two different K(+) currents regulated by muscarinic receptor activation, the inward rectifier (K(IR)) and the M-type (K(M)) currents, have a role in carbachol (CCh)-induced field activity, a prototypical model of cholinergic-dependent epileptiform synchronization. To establish whether K(IR) or K(M) blockade could replicate CCh effects, we exposed slices to blockers of these currents in the absence of CCh. K(IR) channel blockade with micromolar Ba(2+) concentrations induced interictal-like events with duration and frequency that were lower than those observed with CCh; by contrast, the K(M) blocker linopirdine was ineffective. Pre-treatment with Ba(2+) or linopirdine increased the duration of epileptiform discharges induced by subsequent application of CCh. Baclofen, a GABA(B) receptor agonist that activates K(IR), abolished CCh-induced field oscillations, an effect that was abrogated by the GABA(B) receptor antagonist CGP 55845, and prevented by Ba(2+). Finally, when applied after CCh, the K(M) activators flupirtine and retigabine shifted leftward the cumulative distribution of CCh-induced event duration; this effect was opposite to what seen during linopirdine application under similar experimental conditions. Overall, our findings suggest that K(IR) rather than K(M) plays a major regulatory role in controlling CCh-induced epileptiform synchronization. PMID:21144855

  16. Improving point registration in dental cephalograms by two-stage rectified point translation transform

    NASA Astrophysics Data System (ADS)

    Tam, W. K.; Lee, H. J.

    2012-02-01

    Cephalometric analysis requires to detect landmarks on cephalograms. Current registration techniques, such as that use scale-invariant feature descriptor (SIFT), perform poorly on cephalograms. We proposed to improve the registration technique for detecting the landmarks on cephalograms. The results were compared with the landmark identified by dental professionals. Twenty digital cephalograms were collected from a dental clinic. Twenty orthodontic landmarks were identified by dental professionals on each image; one of them was used as a template image. We automatically locate the landmarks using a two stages approach, the global registration of the interest points between two images and a local registration of the landmarks. In the first stage, SIFT was employed to establish point-to-point matching pairs. The matched points on the input image were treated as a set of translation transforms from the original template image. The consistence of the translation was controlled by applying a rectification factor defined in this study. In the second stage, we localized the search within the suspected regions around the landmarks derived by the translations in the first stage. Local registrations were rectified and fine-tuned until the translations close to the identified landmarks were obtained. Our method could detect all the landmarks with error distances less than the 2mm standard set forth by previous researcher. By improving the consistence of the translations, the performance of registration between two images was greatly improved. This method can be used as an initial step to locate the regions around the landmarks for improving detection in the future work.

  17. CMOS-Compatible Room-Temperature Rectifier Toward Terahertz Radiation Detection

    NASA Astrophysics Data System (ADS)

    Varlamava, Volha; De Amicis, Giovanni; Del Monte, Andrea; Perticaroli, Stefano; Rao, Rosario; Palma, Fabrizio

    2016-08-01

    In this paper, we present a new rectifying device, compatible with the technology of CMOS image sensors, suitable for implementing a direct-conversion detector operating at room temperature for operation at up to terahertz frequencies. The rectifying device can be obtained by introducing some simple modifications of the charge-storage well in conventional CMOS integrated circuits, making the proposed solution easy to integrate with the existing imaging systems. The rectifying device is combined with the different elements of the detector, composed of a 3D high-performance antenna and a charge-storage well. In particular, its position just below the edge of the 3D antenna takes maximum advantage of the high electric field concentrated by the antenna itself. In addition, the proposed structure ensures the integrity of the charge-storage well of the detector. In the structure, it is not necessary to use very scaled and costly technological nodes, since the CMOS transistor only provides the necessary integrated readout electronics. On-wafer measurements of RF characteristics of the designed junction are reported and discussed. The overall performances of the entire detector in terms of noise equivalent power (NEP) are evaluated by combining low-frequency measurements of the rectifier with numerical simulations of the 3D antenna and the semiconductor structure at 1 THz, allowing prediction of the achievable NEP.

  18. CMOS-Compatible Room-Temperature Rectifier Toward Terahertz Radiation Detection

    NASA Astrophysics Data System (ADS)

    Varlamava, Volha; De Amicis, Giovanni; Del Monte, Andrea; Perticaroli, Stefano; Rao, Rosario; Palma, Fabrizio

    2016-03-01

    In this paper, we present a new rectifying device, compatible with the technology of CMOS image sensors, suitable for implementing a direct-conversion detector operating at room temperature for operation at up to terahertz frequencies. The rectifying device can be obtained by introducing some simple modifications of the charge-storage well in conventional CMOS integrated circuits, making the proposed solution easy to integrate with the existing imaging systems. The rectifying device is combined with the different elements of the detector, composed of a 3D high-performance antenna and a charge-storage well. In particular, its position just below the edge of the 3D antenna takes maximum advantage of the high electric field concentrated by the antenna itself. In addition, the proposed structure ensures the integrity of the charge-storage well of the detector. In the structure, it is not necessary to use very scaled and costly technological nodes, since the CMOS transistor only provides the necessary integrated readout electronics. On-wafer measurements of RF characteristics of the designed junction are reported and discussed. The overall performances of the entire detector in terms of noise equivalent power (NEP) are evaluated by combining low-frequency measurements of the rectifier with numerical simulations of the 3D antenna and the semiconductor structure at 1 THz, allowing prediction of the achievable NEP.

  19. Silicon nitride/silicon carbide composite powders

    DOEpatents

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1996-06-11

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  20. Inward rectifier potassium channels in the HL-1 cardiomyocyte-derived cell line.

    PubMed

    Goldoni, Dana; Zhao, YouYou; Green, Brian D; McDermott, Barbara J; Collins, Anthony

    2010-11-01

    HL-1 is a line of immortalized cells of cardiomyocyte origin that are a useful complement to native cardiomyocytes in studies of cardiac gene regulation. Several types of ion channel have been identified in these cells, but not the physiologically important inward rectifier K(+) channels. Our aim was to identify and characterize inward rectifier K(+) channels in HL-1 cells. External Ba(2+) (100 µM) inhibited 44 ± 0.05% (mean ± s.e.m., n = 11) of inward current in whole-cell patch-clamp recordings. The reversal potential of the Ba(2+)-sensitive current shifted with external [K(+)] as expected for K(+)-selective channels. The slope conductance of the inward Ba(2+)-sensitive current increased with external [K(+)]. The apparent Kd for Ba(2+) was voltage dependent, ranging from 15 µM at -150  mV to 148 µM at -75  mV in 120  mM external K(+). This current was insensitive to 10 µM glybenclamide. A component of whole-cell current was sensitive to 150 µM 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), although it did not correspond to the Ba(2+)-sensitive component. The effect of external 1 mM Cs(+) was similar to that of Ba(2+). Polymerase chain reaction using HL-1 cDNA as template and primers specific for the cardiac inward rectifier K(ir)2.1 produced a fragment of the expected size that was confirmed to be K(ir)2.1 by DNA sequencing. In conclusion, HL-1 cells express a current that is characteristic of cardiac inward rectifier K(+) channels, and express K(ir)2.1 mRNA. This cell line may have use as a system for studying inward rectifier gene regulation in a cardiomyocyte phenotype. PMID:20568224

  1. The electrophotonic silicon biosensor.

    PubMed

    Juan-Colás, José; Parkin, Alison; Dunn, Katherine E; Scullion, Mark G; Krauss, Thomas F; Johnson, Steven D

    2016-01-01

    The emergence of personalized and stratified medicine requires label-free, low-cost diagnostic technology capable of monitoring multiple disease biomarkers in parallel. Silicon photonic biosensors combine high-sensitivity analysis with scalable, low-cost manufacturing, but they tend to measure only a single biomarker and provide no information about their (bio)chemical activity. Here we introduce an electrochemical silicon photonic sensor capable of highly sensitive and multiparameter profiling of biomarkers. Our electrophotonic technology consists of microring resonators optimally n-doped to support high Q resonances alongside electrochemical processes in situ. The inclusion of electrochemical control enables site-selective immobilization of different biomolecules on individual microrings within a sensor array. The combination of photonic and electrochemical characterization also provides additional quantitative information and unique insight into chemical reactivity that is unavailable with photonic detection alone. By exploiting both the photonic and the electrical properties of silicon, the sensor opens new modalities for sensing on the microscale. PMID:27624590

  2. Simple evaporation controller for thin-film deposition from a resistively heated boat

    NASA Astrophysics Data System (ADS)

    Scofield, John H.; Bajuk, Lou; Mohler, William

    1990-07-01

    A simple, inexpensive circuit is described for switching the current through a resistively heated evaporation boat during thin-film deposition. The circuit uses a silicon-controlled rectifier (SCR) to switch the 0-15-A current in the primary of a 2-kV A step-down transformer that supplies the 0-200-A current to an evaporation boat. The circuit is controlled by a 0-10 V-dc signal similar to that furnished by an Inficon XTC deposition-rate controller. This circuit may be assembled from a handful of parts for a cost of about $400, nearly one-tenth the cost of similar commercial units. Minimum construction is required, since the circuit is built around an off-the-shelf, self-contained SCR unit.

  3. Simple evaporation controller for thin-film deposition from a resistively heated boat

    NASA Technical Reports Server (NTRS)

    Scofield, John H.; Bajuk, Lou; Mohler, William

    1990-01-01

    A simple, inexpensive circuit is described for switching the current through a resistively heated evaporation boat during thin-film deposition. The circuit uses a silicon-controlled rectifier (SCR) to switch the 0-15-A current in the primary of a 2-kV A step-down transformer that supplies the 0-200-A current to an evaporation boat. The circuit is controlled by a 0-10 V-dc signal similar to that furnished by an Inficon XTC deposition-rate controller. This circuit may be assembled from a handful of parts for a cost of about $400, nearly one-tenth the cost of similar commercial units. Minimum construction is required, since the circuit is built around an off-the-shelf, self-contained SCR unit.

  4. Lithographic wavelength control of an external cavity laser with a silicon photonic crystal cavity-based resonant reflector.

    PubMed

    Liles, Alexandros A; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of a new design for external cavity hybrid lasers consisting of a III-V semiconductor optical amplifier (SOA) with fiber reflector and a photonic crystal (PhC)-based resonant reflector on SOI. The silicon reflector is composed of an SU8 polymer bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and side-mode suppression ratios of more than 25 dB. PMID:26974073

  5. Controlling the reproducibility of Coulomb blockade phenomena for gold nanoparticles on an organic monolayer/silicon system.

    PubMed

    Caillard, L; Sattayaporn, S; Lamic-Humblot, A-F; Casale, S; Campbell, P; Chabal, Y J; Pluchery, O

    2015-02-13

    Two types of highly ordered organic layers were prepared on silicon modified with an amine termination for binding gold nanoparticles (AuNPs). These two grafted organic monolayers (GOMs), consisting of alkyl chains with seven or 11 carbon atoms, were grafted on oxide-free Si(111) surfaces as tunnel barriers between the silicon electrode and the AuNPs. Three kinds of colloidal AuNPs were prepared by reducing HAuCl4 with three different reactants: citrate (Turkevich synthesis, diameter ∼16 nm), ascorbic acid (diameter ∼9 nm), or NaBH4 (Natan synthesis, diameter ∼7 nm). Scanning tunnel spectroscopy (STS) was performed in a UHV STM at 40 K, and Coulomb blockade behaviour was observed. The reproducibility of the Coulomb behavior was analysed as a function of several chemical and physical parameters: size, crystallinity of the AuNPs, influence of surrounding surfactant molecules, and quality of the GOM/Si interface (degree of oxidation after the full processing). Samples were characterized with scanning tunneling microscope, STS, atomic force microscope, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), and high resolution transmission electronic microscope. We show that the reproducibility in observing Coulomb behavior can be as high as ∼80% with the Natan synthesis of AuNPs and GOMs with short alkyl chains. PMID:25611611

  6. Ultrafast UV-laser-induced oxidation of silicon - Control and characterization of the Si-SiO2 interface

    NASA Astrophysics Data System (ADS)

    Richter, H.; Orlowski, T. E.; Kelly, M.; Margaritondo, G.

    1984-10-01

    A new low-temperature method of rapidly forming (greater than 100 A/sec) high-quality patterned silicon dioxide (SiO2) layers up to a thickness of 1 micron on silicon substrates is presented. Ultraviolet pulsed laser excitation in an oxygen environment is utilized. Infrared absorption spectroscopy, capacitance-voltage measurements, and soft X-ray photoemission are employed to characterize the oxide films and the Si-SiO2 interface. No shift, but a significant broadening of the Si-O stretching mode compared with thermally grown oxides is found, indicating that the laser-grown oxide is stoichiometric but with a higher degree of disorder. Similar results are obtained from soft X-ray photoemission data: the bulk of the laser-grown SiO2 shows no sign of SiO(x) suboxides, while at the interface a layer of SiO(x) is found of comparable thickness as in thermally grown SiO2. From capacitance-voltage measurements, a fixed oxide charge near the Si-SiO2 interface of 6 x 10 to the 10th/sq cm is deduced for oxides that have been thermally annealed following the laser-induced growth, making this material a candidate for applications in semiconductor devices.

  7. An RF Energy Harvester System Using UHF Micropower CMOS Rectifier Based on a Diode Connected CMOS Transistor

    PubMed Central

    Shokrani, Mohammad Reza; Hamidon, Mohd Nizar B.; Rokhani, Fakhrul Zaman; Shafie, Suhaidi Bin

    2014-01-01

    This paper presents a new type diode connected MOS transistor to improve CMOS conventional rectifier's performance in RF energy harvester systems for wireless sensor networks in which the circuits are designed in 0.18 μm TSMC CMOS technology. The proposed diode connected MOS transistor uses a new bulk connection which leads to reduction in the threshold voltage and leakage current; therefore, it contributes to increment of the rectifier's output voltage, output current, and efficiency when it is well important in the conventional CMOS rectifiers. The design technique for the rectifiers is explained and a matching network has been proposed to increase the sensitivity of the proposed rectifier. Five-stage rectifier with a matching network is proposed based on the optimization. The simulation results shows 18.2% improvement in the efficiency of the rectifier circuit and increase in sensitivity of RF energy harvester circuit. All circuits are designed in 0.18 μm TSMC CMOS technology. PMID:24782680

  8. An RF energy harvester system using UHF micropower CMOS rectifier based on a diode connected CMOS transistor.

    PubMed

    Shokrani, Mohammad Reza; Khoddam, Mojtaba; Hamidon, Mohd Nizar B; Kamsani, Noor Ain; Rokhani, Fakhrul Zaman; Shafie, Suhaidi Bin

    2014-01-01

    This paper presents a new type diode connected MOS transistor to improve CMOS conventional rectifier's performance in RF energy harvester systems for wireless sensor networks in which the circuits are designed in 0.18  μm TSMC CMOS technology. The proposed diode connected MOS transistor uses a new bulk connection which leads to reduction in the threshold voltage and leakage current; therefore, it contributes to increment of the rectifier's output voltage, output current, and efficiency when it is well important in the conventional CMOS rectifiers. The design technique for the rectifiers is explained and a matching network has been proposed to increase the sensitivity of the proposed rectifier. Five-stage rectifier with a matching network is proposed based on the optimization. The simulation results shows 18.2% improvement in the efficiency of the rectifier circuit and increase in sensitivity of RF energy harvester circuit. All circuits are designed in 0.18 μm TSMC CMOS technology. PMID:24782680

  9. Properties of the K+ inward rectifier in the plasma membrane of xylem parenchyma cells from barley roots: effects of TEA+, Ca2+, Ba2+ and La3+.

    PubMed

    Wegner, L H; De Boer, A H; Raschke, K

    1994-12-01

    Xylem parenchyma cells are situated around the (apoplastic) xylem vessels and are involved in the control of the composition of the xylem sap by exporting and resorbing solutes. We investigated properties of the K+ inward rectifier in the plasma membrane of these cells by performing patch clamp experiments on protoplasts in the whole-cell configuration. Inward currents were sensitive to the K+ channel blocker TEA+ at a high concentration (20 mM). Barium, another "classical" K+ channel blocker, inhibited K+ currents with a Ki of about 1.3 mM. In contrast to guard cells, the cytosolic Ca2+ level proved to be ineffective in regulating the K+ conductance at hyperpolarization. External Ca2+ blocked currents weakly in a voltage-dependent manner. From instantaneous current-voltage curves, we identified a binding site in the channel pore with an electrical distance of about 0.2 to 0.5. Lanthanum ions reduced the inward current in a voltage-dependent manner and simultaneously displaced the voltage at which half of the channels are in the open state to more positive values. This finding was interpreted as resulting from a sum of two molecular effects, an interaction with the mouth of the channel that causes a reduction of current, and a binding to the voltage sensor, leading to a shielding of surface charges and, subsequently, a modulation of channel gating. A comparison between the K+ inward rectifier in xylem parenchyma cells, guard cells and KAT1 from Arabidopsis leads to the conclusion that these rectifiers form subtypes within one class of ion channels. The ineffectiveness of Ca2+ to control K+ influx in xylem parenchyma cells is interpreted in physiological terms. PMID:7707363

  10. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    SciTech Connect

    Black, Marcie

    2014-10-30

    This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

  11. Hydrogen-silicon carbide interactions

    NASA Technical Reports Server (NTRS)

    Eckel, Andrew J.; Jacobson, Nathan S.; Misra, Ajay K.; Humphrey, Donald L.

    1989-01-01

    A study of the thermochemistry and kinetics of hydrogen environmental attack of silicon carbide was conducted for temperatures in the range from 1100 C to 1400 C. Thermodynamic maps based on the parameters of pressure and oxygen/moisture content were constructed. With increasing moisture levels, four distinct regions of attack were identified. Each region is defined by the thermodynamically stable solid phases. The theoretically stable solid phases of Region 1 are silicon carbide and silicon. Experimental evidence is provided to support this thermodynamic prediction. Silicon carbide is the single stable solid phase in Region 2. Active attack of the silicon carbide in this region occurs by the formation of gases of SiO, CO, CH4, SiH4, and SiH. Analysis of the kinetics of reaction for Region 2 at 1300 C show the attack of the silicon carbide to be controlled by gas phase diffusion of H2O to the sample. Silicon carbide and silica are the stable phases common to Regions 3 and 4. These two regions are characterized by the passive oxidation of silicon carbide and formation of a protective silica layer.

  12. Hydrogen-silicon carbide interactions

    NASA Technical Reports Server (NTRS)

    Eckel, Andrew J.; Misra, Ajay K.; Humphrey, Donald L.; Jacobson, Nathan S.

    1990-01-01

    A study of the thermochemistry and kinetics of hydrogen environmental attack of silicon carbide was conducted for temperatures in the range from 1100 C to 1400 C. Thermodynamics maps based on the parameters of pressure and oxygen/moisture content were constructed. With increasing moisture levels, four distinct regions of attack were identified. Each region is defined by the thermodynamically stable solid phases. The theoretically stable solid phases of region 1 are silicon carbide and silicon. Experimental evidence is provided to support this thermodynamic prediction. Silicone carbide is the single stable solid phase in region 2. Active attack of the silicon carbide in this region occurs by the formation of gases of SiO, CO, CH4, SiH4 and SiH. Analyses of the kinetics of reaction for region 2 at 1300 C show the attack of the silicon carbide to be controlled by gas phase diffusion of H2O to the sample. Silicon carbide and silica are the stable phases common to regions 3 and 4. These two regions are characterized by the passive oxidation of silicon carbide and formation of a protective silica layer.

  13. Front-end circuit for position sensitive silicon and vacuum tube photomultipliers with gain control and depth of interaction measurement

    NASA Astrophysics Data System (ADS)

    Herrero, Vicente; Colom, Ricardo; Gadea, Rafael; Lerche, Christoph W.; Cerdá, Joaquín; Sebastiá, Ángel; Benlloch, José M.

    2007-06-01

    Silicon Photomultipliers, though still under development for mass production, may be an alternative to traditional Vacuum Photomultipliers Tubes (VPMT). As a consequence, electronic front-ends initially designed for VPMT will need to be modified. In this simulation, an improved architecture is presented which is able to obtain impact position and depth of interaction of a gamma ray within a continuous scintillation crystal, using either kind of PM. A current sensitive preamplifier stage with individual gain adjustment interfaces the multi-anode PM outputs with a current division resistor network. The preamplifier stage allows to improve front-end processing delay and temporal resolution behavior as well as to increase impact position calculation resolution. Depth of interaction (DOI) is calculated from the width of the scintillation light distribution, which is related to the sum of voltages in resistor network input nodes. This operation is done by means of a high-speed current mode scheme.

  14. Low-temperature linear thermal rectifiers based on Coriolis forces

    NASA Astrophysics Data System (ADS)

    Suwunnarat, Suwun; Li, Huanan; Fleischmann, Ragnar; Kottos, Tsampikos

    2016-04-01

    We demonstrate that a three-terminal harmonic symmetric chain in the presence of a Coriolis force, produced by a rotating platform that is used to place the chain, can produce thermal rectification. The direction of heat flow is reconfigurable and controlled by the angular velocity Ω of the rotating platform. A simple three-terminal triangular lattice is used to demonstrate the proposed principle.

  15. TOPICAL REVIEW: Black silicon method X: a review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment

    NASA Astrophysics Data System (ADS)

    Jansen, H V; de Boer, M J; Unnikrishnan, S; Louwerse, M C; Elwenspoek, M C

    2009-03-01

    An intensive study has been performed to understand and tune deep reactive ion etch (DRIE) processes for optimum results with respect to the silicon etch rate, etch profile and mask etch selectivity (in order of priority) using state-of-the-art dual power source DRIE equipment. The research compares pulsed-mode DRIE processes (e.g. Bosch technique) and mixed-mode DRIE processes (e.g. cryostat technique). In both techniques, an inhibitor is added to fluorine-based plasma to achieve directional etching, which is formed out of an oxide-forming (O2) or a fluorocarbon (FC) gas (C4F8 or CHF3). The inhibitor can be introduced together with the etch gas, which is named a mixed-mode DRIE process, or the inhibitor can be added in a time-multiplexed manner, which will be termed a pulsed-mode DRIE process. Next, the most convenient mode of operation found in this study is highlighted including some remarks to ensure proper etching (i.e. step synchronization in pulsed-mode operation and heat control of the wafer). First of all, for the fabrication of directional profiles, pulsed-mode DRIE is far easier to handle, is more robust with respect to the pattern layout and has the potential of achieving much higher mask etch selectivity, whereas in a mixed-mode the etch rate is higher and sidewall scalloping is prohibited. It is found that both pulsed-mode CHF3 and C4F8 are perfectly suited to perform high speed directional etching, although they have the drawback of leaving the FC residue at the sidewalls of etched structures. They show an identical result when the flow of CHF3 is roughly 30 times the flow of C4F8, and the amount of gas needed for a comparable result decreases rapidly while lowering the temperature from room down to cryogenic (and increasing the etch rate). Moreover, lowering the temperature lowers the mask erosion rate substantially (and so the mask selectivity improves). The pulsed-mode O2 is FC-free but shows only tolerable anisotropic results at -120 °C. The

  16. Semiconductor-to-metal Transition Control in Novel Vanadium Dioxide/Silicon and Vanadium Dioxide/Sapphire Epitaxial Thin Film Heterostructures for Device Applications

    NASA Astrophysics Data System (ADS)

    Gupta, Alok

    Novel functionalities of Vanadium dioxide (VO2), such as, several orders of magnitude transition in resistivity and IR transmittance, provide an exciting opportunity for the development of next generation memory, sensor, and field-effect based devices. A critical issue in the development of practical devices based on metal oxides is the integration of high quality epitaxial oxide thin films with the existing silicon technology which is based on silicon (100) substrates. However, silicon is not suitable for epitaxial growth of oxides owing to its tendency to readily form an amorphous oxide layer or silicide at the film-substrate interface. The oxide films deposited directly on silicon exhibit poor crystallinity and are not suitable for device applications. To overcome this challenge, appropriate substrate templates must be developed for the growth of oxide thin films on silicon substrates. The primary objective of this dissertation was to develop an integration methodology of VO2 with Si (100) substrates so they could be used in "smart" sensor type of devices along with other multifunctional devices on the same silicon chip. This was achieved by using yttria-stabilized zirconia (YSZ) template layer deposited in situ. It will be shown that if the deposition conditions are controlled properly, YSZ can be grown epitaxially on silicon substrates even if the native oxide is not etched completely prior to deposition. I have used this approach to integrate VO2 thin films with Si (100) substrates using pulsed laser deposition (PLD) technique. The deposition methodology of integrating VO2 thin films on silicon using various other template layers will also be discussed. The detailed x-ray diffraction, transmission electron microscopy (TEM), electrical characterization results for the deposited films will be presented. In the framework on domain matching epitaxy, epitaxial growth of VO2 (tetragonal crystal structure at growth temperature) on both tetragonal and cubic YSZ has

  17. Growth and characterization of aligned ultralong and diameter-controlled silicon nanotubes by hot wire chemical vapor deposition using electrospun poly(vinyl pyrrolidone) nanofiber template

    NASA Astrophysics Data System (ADS)

    Zhou, Ming; Li, Ruishan; Zhou, Jinyuan; Guo, Xiaosong; Liu, Bin; Zhang, Zhenxing; Xie, Erqing

    2009-12-01

    Using aligned suspended polyvinyl pyrrolidone nanofibers array as template, aligned ultralong (about 4 mm) silicon nanotubes have been prepared by a hot wire chemical vapor deposition process. Scanning electron microscopy and transmission electron microscopy demonstrate that the inner diameter (35-200 nm) and wall thickness (20-400 nm) of Si tubes are controlled, respectively, by baking the electrospun nanofibers and by coating time. The tube wall is composed of nanoparticle or nanopillar, and the inner surface of the wall is smoother than the outer surface of the wall. The microphotoluminescence spectra of the thinner Si nanotubes show three light emission bands in the red, green, and blue regions. And the luminescence mechanism is explained according to the quantum-confinement-luminescence center process and radiative recombination from the defect centers.

  18. Preparation of Aligned Ultra-long and Diameter-controlled Silicon Oxide Nanotubes by Plasma Enhanced Chemical Vapor Deposition Using Electrospun PVP Nanofiber Template

    NASA Astrophysics Data System (ADS)

    Zhou, Ming; Zhou, Jinyuan; Li, Ruishan; Xie, Erqing

    2010-02-01

    Well-aligned and suspended polyvinyl pyrrolidone (PVP) nanofibers with 8 mm in length were obtained by electrospinning. Using the aligned suspended PVP nanofibers array as template, aligned ultra-long silicon oxide (SiO x) nanotubes with very high aspect ratios have been prepared by plasma-enhanced chemical vapor deposition (PECVD) process. The inner diameter (20-200 nm) and wall thickness (12-90 nm) of tubes were controlled, respectively, by baking the electrospun nanofibers and by coating time without sacrificing the orientation degree and the length of arrays. The micro-PL spectrum of SiO x nanotubes shows a strong blue-green emission with a peak at about 514 nm accompanied by two shoulders around 415 and 624 nm. The blue-green emission is caused by the defects in the nanotubes.

  19. Highly controllable and stable quantized conductance and resistive switching mechanism in single-crystal TiO2 resistive memory on silicon.

    PubMed

    Hu, Chengqing; McDaniel, Martin D; Posadas, Agham; Demkov, Alexander A; Ekerdt, John G; Yu, Edward T

    2014-08-13

    TiO2 is being widely explored as an active resistive switching (RS) material for resistive random access memory. We report a detailed analysis of the RS characteristics of single-crystal anatase-TiO2 thin films epitaxially grown on silicon by atomic layer deposition. We demonstrate that although the valence change mechanism is responsible for the observed RS, single-crystal anatase-TiO2 thin films show electrical characteristics that are very different from the usual switching behaviors observed for polycrystalline or amorphous TiO2 and instead very similar to those found in electrochemical metallization memory. In addition, we demonstrate highly stable and reproducible quantized conductance that is well controlled by application of a compliance current and that suggests the localized formation of conducting Magnéli-like nanophases. The quantized conductance observed results in multiple well-defined resistance states suitable for implementation of multilevel memory cells. PMID:25072099

  20. Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves

    NASA Astrophysics Data System (ADS)

    Shinohara, Naoki; Hatano, Ken

    2014-11-01

    In this paper, we show experimental results of RF-DC conversion with modulated 24GHz waves. We have already developed class-F MMIC rectenna with resonators for higher harmonics at no modulated 24GHz microwave for RF energy transfer. Dimensions of the MMIC rectifying circuit is 1 mm × 3 mm on GaAs. Maximum RF-DC conversion efficiency is measured 47.9% for a 210 mW microwave input of 24 GHz with a 120 Ω load. The class-F rectenna is based on a single shunt full-wave rectifier. For future application of a simultaneous energy and information transfer system or an energy harvesting from broadcasting waves, input microwave will be modulated. In this paper, we show an experimental result of RF-DC conversion of the class-F rectenna with 24GHz waves modulated by 16QAM as 1st modulation and OFDM as 2nd modulation.

  1. Hydrogen Sulfide Regulates Inward-Rectifying K+ Channels in Conjunction with Stomatal Closure1[OPEN

    PubMed Central

    Papanatsiou, Maria; Scuffi, Denisse; Blatt, Michael R.; García-Mata, Carlos

    2015-01-01

    Hydrogen sulfide (H2S) is the third biological gasotransmitter, and in animals, it affects many physiological processes by modulating ion channels. H2S has been reported to protect plants from oxidative stress in diverse physiological responses. H2S closes stomata, but the underlying mechanism remains elusive. Here, we report the selective inactivation of current carried by inward-rectifying K+ channels of tobacco (Nicotiana tabacum) guard cells and show its close parallel with stomatal closure evoked by submicromolar concentrations of H2S. Experiments to scavenge H2S suggested an effect that is separable from that of abscisic acid, which is associated with water stress. Thus, H2S seems to define a unique and unresolved signaling pathway that selectively targets inward-rectifying K+ channels. PMID:25770153

  2. A High Power Density Single-Phase PWM Rectifier With Active Ripple Energy Storage

    SciTech Connect

    Wang, Ruxi; Wang, Fei; Boroyevich, Dushan; Burgos, Rolando; Lai, Rixin; Ning, Puqi; Rajashekara, Kaushik

    2011-01-01

    It is well known that single-phase pulse width modulation rectifiers have second-order harmonic currents and corresponding ripple voltages on the dc bus. The low-frequency harmonic current is normally filtered using a bulk capacitor in the bus, which results in low power density. However, pursuing high power density in converter design is a very important goal in the aerospace applications. This paper studies methods for reducing the energy storage capacitor for single-phase rectifiers. The minimum ripple energy storage requirement is derived independently of a specific topology. Based on theminimum ripple energy requirement, the feasibility of the active capacitor s reduction schemes is verified. Then, we propose a bidirectional buck boost converter as the ripple energy storage circuit, which can effectively reduce the energy storage capacitance. The analysis and design are validated by simulation and experimental results.

  3. Characterization of deep electron traps in 4H-SiC Junction Barrier Schottky rectifiers

    NASA Astrophysics Data System (ADS)

    Gelczuk, Ł.; Dąbrowska-Szata, M.; Sochacki, M.; Szmidt, J.

    2014-04-01

    Conventional deep level transient spectroscopy (DLTS) technique was used to study deep electron traps in 4H-SiC Junction Barrier Schottky (JBS) rectifiers. 4H-SiC epitaxial layers, doped with nitrogen and grown on standard n+-4H-SiC substrates were exposed to low-dose aluminum ion implantation process under the Schottky contact in order to form both JBS grid and junction termination extension (JTE), and assure good rectifying properties of the diodes. Several deep electron traps were revealed and attributed to impurities or intrinsic defects in 4H-SiC epitaxial layers, on the basis of comparison of their electrical parameters (i.e. activation energies, apparent capture cross sections and concentrations) with previously published results.

  4. Effect of surfactants on the rate of growth of an air bubble by rectified diffusion.

    PubMed

    Lee, Judy; Kentish, Sandra; Ashokkumar, Muthupandian

    2005-08-01

    The rectified diffusion growth of a single air bubble levitated in an acoustic field (frequency = 22.35 kHz) in water and in aqueous solutions containing surfactants (sodium dodecyl sulfate and sodium dodecylbenzene sulfonate) was investigated. As reported by Crum (J. Acoust. Soc. Am. 1980, 68, 203), the presence of surfactants at the bubble/liquid interface enhanced the growth rate of the bubble by rectified diffusion. It is suggested in this paper that in addition to the effect of surfactants on the surface tension and interfacial resistance to mass transfer, the effect of surface rheological properties may also contribute to the cause of the enhancement observed in the bubble growth rate. PMID:16852840

  5. Expression and purification of recombinant human inward rectifier K+ (KCNJ) channels in Saccharomyces cerevisiae

    PubMed Central

    D’Avanzo, Nazzareno; Cheng, Wayland W.L.; Xia, Xiaobing; Dong, Liang; Savitsky, Pavel; Nichols, Colin G.; Doyle, Declan A.

    2011-01-01

    The inward rectifier family of potassium (KCNJ) channels regulate vital cellular processes including cell volume, electrical excitability, and insulin secretion. Dysfunction of different isoforms have been linked to numerous diseases including Bartter’s, Andersen-Tawil, Smith-Magenis Syndromes, Type II diabetes mellitus, and epilepsy, making them important targets for therapeutic intervention. Using a family-based approach, we succeeded in expressing 10 of 11 human KCNJ channels tested in Saccharomyces cerevisiae. GFP-fusion proteins showed that these channels traffic correctly to the plasma-membrane suggesting that the protein is functional. A 2-step purification process can be used to purify the KCNJ channels to >95% purity in a mono-dispersed form. After incorporation into liposomes, 86Rb+ flux assays confirm the functionality of the purified proteins as inward rectifier potassium channels. PMID:20064617

  6. Silicon microdosimetry.

    PubMed

    Agosteo, Stefano; Pola, Andrea

    2011-02-01

    Silicon detectors are being studied as microdosemeters since they can provide sensitive volumes of micrometric dimensions. They can be applied for assessing single-event effects in electronic instrumentation exposed to complex fields around high-energy accelerators or in space missions. When coupled to tissue-equivalent converters, they can be used for measuring the quality of radiation therapy beams or for dosimetry. The use of micrometric volumes avoids the contribution of wall effects to the measured spectra. Further advantages of such detectors are their compactness, cheapness, transportability and a low sensitivity to vibrations. The following problems need to be solved when silicon devices are used for microdosimetry: (i) the sensitive volume has to be confined in a region of well-known dimensions; (ii) the electric noise limits the minimum detectable energy; (iii) corrections for tissue-equivalency should be made; (iv) corrections for shape equivalency should be made when referring to a spherical simulated site of tissue; (v) the angular response should be evaluated carefully; (vi) the efficiency of a single detector of micrometric dimensions is very poor and detector arrays should be considered. Several devices have been proposed as silicon microdosemeters, based on different technologies (telescope detectors, silicon on insulator detectors and arrays of cylindrical p-n junctions with internal amplification), in order to satisfy the issues mentioned above. PMID:21112892

  7. Application of Resonant Snubber Switch Cell to Single-Phase Buck Rectifier

    NASA Astrophysics Data System (ADS)

    Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Matsumoto, Hirokazu; Miyamoto, Katsuhiko

    Application of resonant snubber switch cell to a single-phase buck rectifier is studied. The resonant snubber switch cell consists of an only active power switching device and a LC resonant circuit. The active power switching device is then turned on and off under the soft switching conditions. The experimental results under the sinusoidal pulse-width modulation (PWM) confirm that the input current can nearly be wave-shaped sinusoidally with a near-unity power factor.

  8. Vacuolar malate uptake is mediated by an anion-selective inward rectifier.

    PubMed

    Hafke, Jens B; Hafke, Yuliya; Smith, J Andrew C; Lüttge, Ulrich; Thiel, Gerhard

    2003-07-01

    Electrophysiological studies using the patch-clamp technique were performed on isolated vacuoles from leaf mesophyll cells of the crassulacean acid metabolism (CAM) plant Kalanchoë daigremontiana to characterize the malate transport system responsible for nocturnal malic acid accumulation. In the presence of malate on both sides of the membrane, the current-voltage relations of the tonoplast were dominated by a strongly inward-rectifying anion-selective channel that was active at cytoplasmic-side negative voltages. Rectification of the macroscopic conductance was reflected in the voltage-dependent gating of a 3-pS malate-selective ion channel, which showed a half-maximal open probability at -43 mV. Also, the time-averaged unitary currents following a step to a negative voltage corresponded to the time-dependent kinetics of the macroscopic currents, suggesting that the activity of this channel underlies the anion-selective inward rectifier. The inward rectifier showed saturation kinetics with respect to malate (apparent Km of 2.5 mm malate2- activity), a selectivity sequence of fumarate2- > malate2- > Cl- > maleate2- approximately citrate3-, and greater activity at higher pH values (with an apparent pK of 7.1 and maximum activity at around pH 8.0). All these properties were in close agreement with the characteristics of malate transport observed in isolated tonoplast vesicles. Further, 100 microM niflumate reversibly blocked the activity of the 3-pS channel and inhibited both macroscopic currents and malate transport into tonoplast vesicles to the same extent. The macroscopic current densities recorded at physiological voltages and the estimated channel density of 0.2 microm-2 are sufficient to account for the observed rates of nocturnal malic acid accumulation in this CAM plant, suggesting that the 3-pS, inward-rectifying, anion-selective channel represents the principal pathway for malate influx into the vacuole. PMID:12834407

  9. A novel recovery of silicon nanoparticles from a waste silicon sludge.

    PubMed

    Jang, Hee Dong; Kim, Hyekyoung; Kil, Dae Sup; Chang, Hankwon

    2013-03-01

    As the semiconductor and photovoltaic industry undergo rapid growth, a large amount of silicon sludge is generated from the cutting process of silicon ingots. However, it is not effectively recycled. Recovery of nanometer-sized silicon (Si) particles from the sludge has become an important concern because the silicon sludge contains valuable resources including high purity silicon. In the present study, we investigated the novel recovery of Si nanoparticles from waste silicon sludge. The waste silicon sludge also contained surfactant, silicon carbide particles and metallic fragments. After removal of the surfactant by distillation, the Si nanoparticles were recovered by applying controlled ultrasonic waves and centrifugation in series. Metallic impurities in the recovered Si nanoparticles were purified by HCl treatment. The overall maximum yield and purity of the Si nanoparticles were about 80% and 99.7%, respectively. PMID:23755688

  10. Silicon surface passivation by silicon nitride deposition

    NASA Technical Reports Server (NTRS)

    Olsen, L. C.

    1984-01-01

    Silicon nitride deposition was studied as a method of passivation for silicon solar cell surfaces. The following three objectives were the thrust of the research: (1) the use of pecvd silicon nitride for passivation of silicon surfaces; (2) measurement techniques for surface recombination velocity; and (3) the importance of surface passivation to high efficiency solar cells.

  11. Multi-service highly sensitive rectifier for enhanced RF energy scavenging.

    PubMed

    Shariati, Negin; Rowe, Wayne S T; Scott, James R; Ghorbani, Kamran

    2015-01-01

    Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478-496 and 852-869 MHz) and exhibits favorable impedance matching over a broad input power range (-40 to -10 dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8 mV is achieved for a multi-tone input power of -10 dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860 MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments. PMID:25951137

  12. Effect of temperature on rectifying Schottky barriers formed from fingerprint sweat corrosion of brass.

    PubMed

    Bond, John W

    2011-09-01

    Corrosive electrochemical processes of brass, including those resulting from fingerprint sweat, continue to be studied because of the widespread industrial use of brass. Here, we examine how increased temperature affects the relative abundance of fingerprint sweat corrosion products and the rectifying Schottky barrier formed between p-type copper (I) oxide corrosion and brass. X-ray photoelectron spectroscopy confirms increasing dezincification with increasing temperature. This leads to n-type zinc oxide replacing copper (I) oxide as the dominant corrosion product, which then forms a rectifying Schottky barrier with the brass, instead of copper oxide, when the temperature reaches c. 600°C. Using X-ray diffraction, resulting diodes show polycrystalline oxides embedded in amorphous oxidation products that have a lower relative abundance than the diode forming oxide. Conventional current/voltage (I/V) characteristics of these diodes show good rectifying qualities. At temperatures between c. 100 and c. 600°C, when neither oxide dominates, the semiconductor/brass contact displays an absence of rectification. PMID:21595693

  13. UV/ozone assisted local graphene (p)/ZnO(n) heterojunctions as a nanodiode rectifier

    NASA Astrophysics Data System (ADS)

    Sahatiya, Parikshit; Badhulika, Sushmee

    2016-07-01

    Here we report the fabrication of a novel graphene/ZnO nanodiode by UV/ozone assisted oxidation of graphene and demonstrate its application as a half-wave rectifier to generate DC voltage. The method involves the use of electrospinning for one-step in situ synthesis and alignment of single Gr/ZnO nanocomposite across metal electrodes. On subsequent UV illumination, graphene oxidizes, which induces p type doping and ZnO being an n type semiconductor, thus resulting in the formation of a nanodiode. The as-fabricated device shows strong non-linear current–voltage characteristic similar to that of conventional semiconductor p–n junction diodes. Excellent rectifying behavior with a rectification ratio of ~103 was observed and the nanodiodes were found to exhibit long-term repeatability in their performance. Ideality factor and barrier height, as calculated by the thermionic emission model, were found to be 1.6 and 0.504 eV respectively. Due to the fact that diodes are the basic building blocks in the electronics and semiconductor industry, the successful fabrication of these nanodiodes based on UV assisted p type doping of graphene indicates that this approach can be used for developing highly scalable and efficient components for nanoelectronics, such as rectifiers and logic gates that find applications in numerous fields.

  14. Low cost, p-ZnO/n-Si, rectifying, nano heterojunction diode: Fabrication and electrical characterization

    PubMed Central

    Kabra, Vinay; Malik, M M

    2014-01-01

    Summary A low cost, highly rectifying, nano heterojunction (p-ZnO/n-Si) diode was fabricated using solution-processed, p-type, ZnO nanoparticles and an n-type Si substrate. p-type ZnO nanoparticles were synthesized using a chemical synthesis route and characterized by XRD and a Hall effect measurement system. The device was fabricated by forming thin film of synthesized p-ZnO nanoparticles on an n-Si substrate using a dip coating technique. The device was then characterized by current–voltage (I–V) and capacitance–voltage (C–V) measurements. The effect of UV illumination on the I–V characteristics was also explored and indicated the formation of a highly rectifying, nano heterojunction with a rectification ratio of 101 at 3 V, which increased nearly 2.5 times (232 at 3 V) under UV illumination. However, the cut-in voltage decreases from 1.5 V to 0.9 V under UV illumination. The fabricated device could be used in switches, rectifiers, clipper and clamper circuits, BJTs, MOSFETs and other electronic circuitry. PMID:25551049

  15. Mitigating impact of thermal and rectified radio-frequency sheath potentials on edge localized modes

    SciTech Connect

    Gui, B.; Xu, X. Q.; Myra, J. R.; D'Ippolito, D. A.

    2014-11-15

    The mitigating impact of thermal and rectified radio frequency (RF) sheath potentials on the peeling-ballooning modes is studied non-linearly by employing a two-fluid three-field simulation model based on the BOUT++ framework. Additional shear flow and the Kelvin-Helmholtz effect due to the thermal and rectified RF sheath potential are induced. It is found that the shear flow increases the growth rate while the K-H effect decreases the growth rate slightly when there is a density gradient, but the energy loss of these cases is suppressed in the nonlinear phase. The stronger external electrostatic field due to the sheaths has a more significant effect on the energy loss suppression. From this study, it is found the growth rate in the linear phase mainly determines the onset of edge-localized modes, while the mode spectrum width in the nonlinear phase has an important impact on the turbulent transport. The wider mode spectrum leads to weaker turbulent transport and results in a smaller energy loss. Due to the thermal sheath and rectified RF sheath potential in the scrape-off-layer, the modified shear flow tears apart the peeling-ballooning filament and makes the mode spectrum wider, resulting in less energy loss. The perturbed electric potential and the parallel current near the sheath region is also suppressed locally due to the sheath boundary condition.

  16. Mitigating impact of thermal and rectified radio-frequency sheath potentials on edge localized modes

    NASA Astrophysics Data System (ADS)

    Gui, B.; Xu, X. Q.; Myra, J. R.; D'Ippolito, D. A.

    2014-11-01

    The mitigating impact of thermal and rectified radio frequency (RF) sheath potentials on the peeling-ballooning modes is studied non-linearly by employing a two-fluid three-field simulation model based on the BOUT++ framework. Additional shear flow and the Kelvin-Helmholtz effect due to the thermal and rectified RF sheath potential are induced. It is found that the shear flow increases the growth rate while the K-H effect decreases the growth rate slightly when there is a density gradient, but the energy loss of these cases is suppressed in the nonlinear phase. The stronger external electrostatic field due to the sheaths has a more significant effect on the energy loss suppression. From this study, it is found the growth rate in the linear phase mainly determines the onset of edge-localized modes, while the mode spectrum width in the nonlinear phase has an important impact on the turbulent transport. The wider mode spectrum leads to weaker turbulent transport and results in a smaller energy loss. Due to the thermal sheath and rectified RF sheath potential in the scrape-off-layer, the modified shear flow tears apart the peeling-ballooning filament and makes the mode spectrum wider, resulting in less energy loss. The perturbed electric potential and the parallel current near the sheath region is also suppressed locally due to the sheath boundary condition.

  17. Gating mechanism of the cloned inward rectifier potassium channel from mouse heart.

    PubMed

    Ishihara, K; Hiraoka, M

    1994-10-01

    The complementary DNA encoding the inward rectifier potassium channel was cloned from the adult mouse heart by using the polymerase chain reaction. The clone had the nucleotide sequence identical to that of the IRK1 gene cloned from a mouse macrophage cell line. Northern blot analysis revealed that the transcript of this gene was mainly expressed in the ventricle, where the inward rectifier K+ channel plays a predominant role in maintaining the high negative value of the resting membrane potential. The current expressed by injection of the complementary RNA of the cloned gene into Xenopus oocytes showed a marked inward rectification that depends on the driving force of K+. A region of negative slope conductance was observed in the current-voltage relationship at potentials positive to the reversal potential. When the extracellular K+ concentration was raised, the increase in outward current amplitude resulted in the "crossover" of outward current-voltage relations. The fast time-dependent increase in current amplitude was recorded upon membrane repolarization from a potential positive to the reversal potential. The kinetics of the time-dependent current was very similar to that of the intrinsic gating mechanism of the native cardiac inward rectifier K+ channel. Our results suggest the existence of the intrinsic gating mechanism, accounting for the extent of rectification in the current-voltage relationship in the expressed channel. PMID:7707353

  18. Microfluidic rectifier based on poly(dimethylsiloxane) membrane and its application to a micropump

    PubMed Central

    Wang, Yao-Nan; Tsai, Chien-Hsiung; Fu, Lung-Ming; Lin Liou, Lung-Kai

    2013-01-01

    A microfluidic rectifier incorporating an obstructed microchannel and a PDMS membrane is proposed. During forward flow, the membrane deflects in the upward direction; thereby allowing the fluid to pass over the obstacle. Conversely, during reverse flow, the membrane seals against the obstacle, thereby closing the channel and preventing flow. It is shown that the proposed device can operate over a wide pressure range by increasing or decreasing the membrane thickness as required. A microfluidic pump is realized by integrating the rectifier with a simple stepper motor mechanism. The experimental results show that the pump can achieve a vertical left height of more than 2 m. Moreover, it is shown that a maximum flow rate of 6.3 ml/min can be obtained given a membrane thickness of 200 μm and a motor velocity of 80 rpm. In other words, the proposed microfluidic rectifier not only provides an effective means of preventing reverse flow but also permits the realization of a highly efficient microfluidic pump. PMID:24404051

  19. Multi-Service Highly Sensitive Rectifier for Enhanced RF Energy Scavenging

    PubMed Central

    Shariati, Negin; Rowe, Wayne S. T.; Scott, James R.; Ghorbani, Kamran

    2015-01-01

    Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478–496 and 852–869 MHz) and exhibits favorable impedance matching over a broad input power range (−40 to −10 dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8 mV is achieved for a multi-tone input power of −10 dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860 MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments. PMID:25951137

  20. Rectifying Properties of Oligo(Phenylene Ethynylene) Heterometallic Molecular Junctions: Molecular Length and Side Group Effects

    PubMed Central

    Fu, Xiao-Xiao; Zhang, Rui-Qin; Zhang, Guang-Ping; Li, Zong-Liang

    2014-01-01

    The rectifying properties of α,ω-dithiol terminated oligo(phenylene ethynylene) molecules sandwiched between heterometallic electrodes, including the molecular length and side group effects, are theoretically investigated using the fully self-consistent nonequilibrium Green's function method combined with density functional theory. The results show nonlinear variation with changes in molecule length: when the molecule becomes longer, the current decreases at first and then increases while the rectification shifts in the opposite direction. This stems from the change in molecular eigenstates and the coupling between the molecule and electrodes caused by different molecular lengths. The rectifying behavior of heterometallic molecular junctions can be attributed to the asymmetric molecule-electrode contacts, which lead to asymmetric electronic tunneling spectra, molecular eigenvalues, molecular orbitals, and potential drop at reversed equivalent bias voltages. Our results provide a fundamental understanding of the rectification of heterometallic molecular junction, and a prediction of rectifiers with different rectification properties from those in the experiment, using electrodes with reduced sizes. PMID:25220880

  1. Damage Mechanisms and Controlled Crack Propagation in a Hot Pressed Silicon Nitride Ceramic. Ph.D. Thesis - Northwestern Univ., 1993

    NASA Technical Reports Server (NTRS)

    Calomino, Anthony Martin

    1994-01-01

    The subcritical growth of cracks from pre-existing flaws in ceramics can severely affect the structural reliability of a material. The ability to directly observe subcritical crack growth and rigorously analyze its influence on fracture behavior is important for an accurate assessment of material performance. A Mode I fracture specimen and loading method has been developed which permits the observation of stable, subcritical crack extension in monolithic and toughened ceramics. The test specimen and procedure has demonstrated its ability to generate and stably propagate sharp, through-thickness cracks in brittle high modulus materials. Crack growth for an aluminum oxide ceramic was observed to be continuously stable throughout testing. Conversely, the fracture behavior of a silicon nitride ceramic exhibited crack growth as a series of subcritical extensions which are interrupted by dynamic propagation. Dynamic initiation and arrest fracture resistance measurements for the silicon nitride averaged 67 and 48 J/sq m, respectively. The dynamic initiation event was observed to be sudden and explosive. Increments of subcritical crack growth contributed to a 40 percent increase in fracture resistance before dynamic initiation. Subcritical crack growth visibly marked the fracture surface with an increase in surface roughness. Increments of subcritical crack growth loosen ceramic material near the fracture surface and the fracture debris is easily removed by a replication technique. Fracture debris is viewed as evidence that both crack bridging and subsurface microcracking may be some of the mechanisms contributing to the increase in fracture resistance. A Statistical Fracture Mechanics model specifically developed to address subcritical crack growth and fracture reliability is used together with a damaged zone of material at the crack tip to model experimental results. A Monte Carlo simulation of the actual experiments was used to establish a set of modeling input

  2. Production of electronic grade lunar silicon by disproportionation of silicon difluoride

    NASA Technical Reports Server (NTRS)

    Agosto, William N.

    1993-01-01

    Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

  3. Production of electronic grade lunar silicon by disproportionation of silicon difluoride

    NASA Astrophysics Data System (ADS)

    Agosto, William N.

    1993-03-01

    Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

  4. Controlled translocation of DNA through nanopores in carbon nano-, silicon-nitride- and lipid-coated membranes.

    PubMed

    Sischka, Andy; Galla, Lukas; Meyer, Andreas J; Spiering, Andre; Knust, Sebastian; Mayer, Michael; Hall, Adam R; Beyer, André; Reimann, Peter; Gölzhäuser, Armin; Anselmetti, Dario

    2015-07-21

    We investigated experimentally and theoretically the translocation forces when a charged polymer is threaded through a solid-state nanopore and found distinct dependencies on the nanopore diameter as well as on the nano membrane material chemistry. For this purpose we utilized dedicated optical tweezers force mechanics capable of probing the insertion of negatively charged double-stranded DNA inside a helium-ion drilled nanopore. We found that both the diameter of the nanopore and the membrane material itself have significant influences on the electroosmotic flow through the nanopore and thus on the threading force. Compared to a bare silicon-nitride membrane, the threading of DNA through only 3 nm thin carbon nano membranes as well as lipid bilayer-coated nanopores increased the threading force by 15% or 85%, respectively. This finding was quantitatively described by our recently developed theoretical model that also incorporates hydrodynamic slip effects on the translocating DNA molecule and the force dependence on the membrane thickness. The additional measurements presented in this paper further support our model. PMID:25768647

  5. Versatile control of metal-assisted chemical etching for vertical silicon microwire arrays and their photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Um, Han-Don; Kim, Namwoo; Lee, Kangmin; Hwang, Inchan; Hoon Seo, Ji; Yu, Young J.; Duane, Peter; Wober, Munib; Seo, Kwanyong

    2015-06-01

    A systematic study was conducted into the use of metal-assisted chemical etching (MacEtch) to fabricate vertical Si microwire arrays, with several models being studied for the efficient redox reaction of reactants with silicon through a metal catalyst by varying such parameters as the thickness and morphology of the metal film. By optimizing the MacEtch conditions, high-quality vertical Si microwires were successfully fabricated with lengths of up to 23.2 μm, which, when applied in a solar cell, achieved a conversion efficiency of up to 13.0%. These solar cells also exhibited an open-circuit voltage of 547.7 mV, a short-circuit current density of 33.2 mA/cm2, and a fill factor of 71.3% by virtue of the enhanced light absorption and effective carrier collection provided by the Si microwires. The use of MacEtch to fabricate high-quality Si microwires therefore presents a unique opportunity to develop cost-effective and highly efficient solar cells.

  6. Versatile control of metal-assisted chemical etching for vertical silicon microwire arrays and their photovoltaic applications.

    PubMed

    Um, Han-Don; Kim, Namwoo; Lee, Kangmin; Hwang, Inchan; Hoon Seo, Ji; Yu, Young J; Duane, Peter; Wober, Munib; Seo, Kwanyong

    2015-01-01

    A systematic study was conducted into the use of metal-assisted chemical etching (MacEtch) to fabricate vertical Si microwire arrays, with several models being studied for the efficient redox reaction of reactants with silicon through a metal catalyst by varying such parameters as the thickness and morphology of the metal film. By optimizing the MacEtch conditions, high-quality vertical Si microwires were successfully fabricated with lengths of up to 23.2 μm, which, when applied in a solar cell, achieved a conversion efficiency of up to 13.0%. These solar cells also exhibited an open-circuit voltage of 547.7 mV, a short-circuit current density of 33.2 mA/cm(2), and a fill factor of 71.3% by virtue of the enhanced light absorption and effective carrier collection provided by the Si microwires. The use of MacEtch to fabricate high-quality Si microwires therefore presents a unique opportunity to develop cost-effective and highly efficient solar cells. PMID:26060095

  7. Versatile control of metal-assisted chemical etching for vertical silicon microwire arrays and their photovoltaic applications

    PubMed Central

    Um, Han-Don; Kim, Namwoo; Lee, Kangmin; Hwang, Inchan; Hoon Seo, Ji; Yu, Young J.; Duane, Peter; Wober, Munib; Seo, Kwanyong

    2015-01-01

    A systematic study was conducted into the use of metal-assisted chemical etching (MacEtch) to fabricate vertical Si microwire arrays, with several models being studied for the efficient redox reaction of reactants with silicon through a metal catalyst by varying such parameters as the thickness and morphology of the metal film. By optimizing the MacEtch conditions, high-quality vertical Si microwires were successfully fabricated with lengths of up to 23.2 μm, which, when applied in a solar cell, achieved a conversion efficiency of up to 13.0%. These solar cells also exhibited an open-circuit voltage of 547.7 mV, a short-circuit current density of 33.2 mA/cm2, and a fill factor of 71.3% by virtue of the enhanced light absorption and effective carrier collection provided by the Si microwires. The use of MacEtch to fabricate high-quality Si microwires therefore presents a unique opportunity to develop cost-effective and highly efficient solar cells. PMID:26060095

  8. Inverse agonist-like action of cadmium on G-protein-gated inward-rectifier K{sup +} channels

    SciTech Connect

    Inanobe, Atsushi; Matsuura, Takanori; Nakagawa, Atsushi; Kurachi, Yoshihisa

    2011-04-08

    Highlights: {yields} We examined allosteric control of K{sup +} channel gating. {yields} We identified a high-affinity site for Cd{sup 2+} to inhibit Kir3.2 activity. {yields} The 6-coordination geometry supports the binding. {yields} Cd{sup 2+} inhibits Kir3.2 by trapping the conformation in the closed state. -- Abstract: The gate at the pore-forming domain of potassium channels is allosterically controlled by a stimulus-sensing domain. Using Cd{sup 2+} as a probe, we examined the structural elements responsible for gating in an inward-rectifier K{sup +} channel (Kir3.2). One of four endogenous cysteines facing the cytoplasm contributes to a high-affinity site for inhibition by internal Cd{sup 2+}. Crystal structure of its cytoplasmic domain in complex with Cd{sup 2+} reveals that octahedral coordination geometry supports the high-affinity binding. This mode of action causes the tethering of the N-terminus to CD loop in the stimulus-sensing domain, suggesting that their conformational changes participate in gating and Cd{sup 2+} inhibits Kir3.2 by trapping the conformation in the closed state like 'inverse agonist'.

  9. Large area silicon sheet by EFG

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Some hypotheses to explain both of these features are advanced and the possible implications for solar cell performance are touched upon. The multiple ribbon growth system has shown a number of flaws with respect to the reliability of the basic furnace design. These definitely need to be rectified before any significant demonstration of multiple ribbon growth can proceed. The cartridges, however, have performed quite well. The work on 3" cartridge design and automatic controls has proceeded nearly on schedule and the report contains a detailed description of the approach and the equipment to be used for automatic control of ribbon growth.

  10. Silicon Nanowire Devices

    NASA Astrophysics Data System (ADS)

    Kamins, Theodore

    2006-03-01

    Metal-catalyzed, self-assembled, one-dimensional semiconductor nanowires are being considered as possible device elements to augment and supplant conventional electronics and to extend the use of CMOS beyond the physical and economic limits of conventional technology. Such nanowires can create nanostructures without the complexity and cost of extremely fine scale lithography. The well-known and controllable properties of silicon make silicon nanowires especially attractive. Easy integration with conventional electronics will aid their acceptance and incorporation. For example, connections can be formed to both ends of a nanowire by growing it laterally from a vertical surface formed by etching the top silicon layer of a silicon-on-insulator structure into isolated electrodes. Field-effect structures are one class of devices that can be readily built in silicon nanowires. Because the ratio of surface to volume in a thin nanowire is high, conduction through the nanowire is very sensitive to surface conditions, making it effective as the channel of a field-effect transistor or as the transducing element of a gas or chemical sensor. As the nanowire diameter decreases, a greater fraction of the mobile charge can be modulated by a given external charge, increasing the sensitivity. Having the gate of a nanowire transistor completely surround the nanowire also enhances the sensitivity. For a field-effect sensor to be effective, the charge must be physically close to the nanowire so that the majority of the compensating charge is induced in the nanowire and so that ions in solution do not screen the charge. Because only induced charge is being sensed, a coating that selectively binds the target species should be added to the nanowire surface to distinguish between different species in the analyte. The nanowire work at Hewlett-Packard Laboratories was supported in part by the Defense Advanced Research Projects Agency.

  11. Distinct pharmacological and molecular properties of the acid-sensitive outwardly rectifying (ASOR) anion channel from those of the volume-sensitive outwardly rectifying (VSOR) anion channel.

    PubMed

    Sato-Numata, Kaori; Numata, Tomohiro; Inoue, Ryuji; Okada, Yasunobu

    2016-05-01

    Expressed by many cell types, acid-sensitive outwardly rectifying (ASOR) anion channels are known to be activated by extracellular acidification and involved in acidotoxic necrotic cell death. In contrast, ubiquitously expressed volume-sensitive outwardly rectifying (VSOR) anion channels are activated by osmotic cell swelling and involved in cell volume regulation and apoptotic cell death. Distinct inhibitors to distinguish ASOR from VSOR anion channels have not been identified. Although leucine-rich repeats containing 8A (LRRC8A) was recently found to be an essential component of VSOR anion channels, the possibility of an LRRC8 family member serving as a component of ASOR anion channels has not been examined. In this study, we explored the effects of 12 known VSOR channel inhibitors and small interfering RNA (siRNA)-mediated knockdown of LRRC8 family members on ASOR and VSOR currents in HeLa cells. Among these inhibitors, eight putative VSOR blockers, including 4-(2-butyl-6,7-dichlor-2-cyclopentylindan-1-on-5-yl) oxobutyric acid (DCPIB) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), were totally ineffective at blocking ASOR channel activity, whereas suramin, R-(+)-[(2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy] acetic acid (DIOA), arachidonic acid, and niflumic acid were found to be effective ASOR anion channel antagonists. In addition, gene-silencing studies showed that no LRRC8 family members are essentially involved in ASOR anion channel activity, whereas LRRC8A is involved in VSOR anion channel activity in HeLa cells. PMID:26743872

  12. Control of optical bandgap energy and optical absorption coefficient by geometric parameters in sub-10 nm silicon-nanodisc array structure

    NASA Astrophysics Data System (ADS)

    Fairuz Budiman, Mohd; Hu, Weiguo; Igarashi, Makoto; Tsukamoto, Rikako; Isoda, Taiga; Itoh, Kohei M.; Yamashita, Ichiro; Murayama, Akihiro; Okada, Yoshitaka; Samukawa, Seiji

    2012-02-01

    A sub-10 nm, high-density, periodic silicon-nanodisc (Si-ND) array has been fabricated using a new top-down process, which involves a 2D array bio-template etching mask made of Listeria-Dps with a 4.5 nm diameter iron oxide core and damage-free neutral-beam etching (Si-ND diameter: 6.4 nm). An Si-ND array with an SiO2 matrix demonstrated more controllable optical bandgap energy due to the fine tunability of the Si-ND thickness and diameter. Unlike the case of shrinking Si-ND thickness, the case of shrinking Si-ND diameter simultaneously increased the optical absorption coefficient and the optical bandgap energy. The optical absorption coefficient became higher due to the decrease in the center-to-center distance of NDs to enhance wavefunction coupling. This means that our 6 nm diameter Si-ND structure can satisfy the strict requirements of optical bandgap energy control and high absorption coefficient for achieving realistic Si quantum dot solar cells.

  13. Microfluidic assembly of monodisperse multistage pH-responsive polymer/porous silicon composites for precisely controlled multi-drug delivery.

    PubMed

    Liu, Dongfei; Zhang, Hongbo; Herranz-Blanco, Bárbara; Mäkilä, Ermei; Lehto, Vesa-Pekka; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2014-05-28

    We report an advanced drug delivery platform for combination chemotherapy by concurrently incorporating two different drugs into microcompoistes with ratiometric control over the loading degree. Atorvastatin and celecoxib were selected as model drugs due to their different physicochemical properties and synergetic effect on colorectal cancer prevention and inhibition. To be effective in colorectal cancer prevention and inhibition, the produced microcomposite contained hypromellose acetate succinate, which is insoluble in acidic conditions but highly dissolving at neutral or alkaline pH conditions. Taking advantage of the large pore volume of porous silicon (PSi), atorvastatin was firstly loaded into the PSi matrix, and then encapsulated into the pH-responsive polymer microparticles containing celecoxib by microfluidics in order to obtain multi-drug loaded polymer/PSi microcomposites. The prepared microcomposites showed monodisperse size distribution, multistage pH-response, precise ratiometric controlled loading degree towards the simultaneously loaded drug molecules, and tailored release kinetics of the loaded cargos. This attractive microcomposite platform protects the payloads from being released at low pH-values, and enhances their release at higher pH-values, which can be further used for colon cancer prevention and treatment. Overall, the pH-responsive polymer/PSi-based microcomposite can be used as a universal platform for the delivery of different drug molecules for combination therapy. PMID:24616278

  14. Ultrafast laser functionalized rare phased gold-silicon/silicon oxide nanostructured hybrid biomaterials.

    PubMed

    Premnath, P; Tan, B; Venkatakrishnan, K

    2015-12-01

    We introduce a hybrid nanostructured biomaterial that is a combination of rare phases of immiscible gold and silicon oxide, functionalized via ultrafast laser synthesis. For the first time, we show cancer controlling properties of rare phases of gold silicides, which include Au7Si, Au5Si, Au0.7Si2.3 and Au8Si2. Conventionally, pure forms of gold and silicon/silicon oxide are extensively employed in targeted therapy and drug delivery systems due to their unique properties. While silicon and silicon oxide nanoparticles have shown biocompatibility, gold nanoparticles show conflicting results based on their size and material properties. Several studies have shown that gold and silicon combinations produce cell controlling properties, however, these studies were not able to produce a homogenous combination of gold and silicon, owing to its immiscibility. A homogenous combination of gold and silicon may potentially enable properties that have not previously been reported. We describe rare phased gold-silicon oxide nanostructured hybrid biomaterials and its unique cancer controlling properties, owing to material properties, concentration, size and density. The gold-silicon oxide nanostructured hybrid is composed of individual gold-silicon oxide nanoparticles in various concentrations of gold and silicon, some nanoparticles possess a gold-core and silicon-shell like structure. The individual nanoparticles are bonded together forming a three dimensional nanostructured hybrid. The interaction of the nanostructured hybrids with cervical cancer cells showed a 96% reduction in 24h. This engineered nanostructured hybrid biomaterial presents significant potential due to the combination of immiscible gold and silicon oxide in varying phases and can potentially satiate the current vacuum in cancer therapy. PMID:26539809

  15. Making silicon stronger.

    SciTech Connect

    Boyce, Brad Lee

    2010-11-01

    Silicon microfabrication has seen many decades of development, yet the structural reliability of microelectromechanical systems (MEMS) is far from optimized. The fracture strength of Si MEMS is limited by a combination of poor toughness and nanoscale etch-induced defects. A MEMS-based microtensile technique has been used to characterize the fracture strength distributions of both standard and custom microfabrication processes. Recent improvements permit 1000's of test replicates, revealing subtle but important deviations from the commonly assumed 2-parameter Weibull statistical model. Subsequent failure analysis through a combination of microscopy and numerical simulation reveals salient aspects of nanoscale flaw control. Grain boundaries, for example, suffer from preferential attack during etch-release thereby forming failure-critical grain-boundary grooves. We will discuss ongoing efforts to quantify the various factors that affect the strength of polycrystalline silicon, and how weakest-link theory can be used to make worst-case estimates for design.

  16. Evaluation of acceleration and deceleration cardiac processes using phase-rectified signal averaging in healthy and idiopathic dilated cardiomyopathy subjects.

    PubMed

    Bas, Rosana; Vallverdú, Montserrat; Valencia, Jose F; Voss, Andreas; de Luna, Antonio Bayés; Caminal, Pere

    2015-02-01

    The aim of the present study was to investigate the suitability of the Phase-Rectified Signal Averaging (PRSA) method for improved risk prediction in cardiac patients. Moreover, this technique, which separately evaluates acceleration and deceleration processes of cardiac rhythm, allows the effect of sympathetic and vagal modulations of beat-to-beat intervals to be characterized. Holter recordings of idiopathic dilated cardiomyopathy (IDC) patients were analyzed: high-risk (HR), who suffered sudden cardiac death (SCD) during the follow-up; and low-risk (LR), without any kind of cardiac-related death. Moreover, a control group of healthy subjects was analyzed. PRSA indexes were analyzed, for different time scales T and wavelet scales s, from RR series of 24 h-ECG recordings, awake periods and sleep periods. Also, the behavior of these indexes from simulated data was analyzed and compared with real data results. Outcomes demonstrated the PRSA capacity to significantly discriminate healthy subjects from IDC patients and HR from LR patients on a higher level than traditional temporal and spectral measures. The behavior of PRSA indexes agrees with experimental evidences related to cardiac autonomic modulations. Also, these parameters reflect more regularity of the autonomic nervous system (ANS) in HR patients. PMID:25585858

  17. Eliciting renal failure in mosquitoes with a small-molecule inhibitor of inward-rectifying potassium channels.

    PubMed

    Raphemot, Rene; Rouhier, Matthew F; Hopkins, Corey R; Gogliotti, Rocco D; Lovell, Kimberly M; Hine, Rebecca M; Ghosalkar, Dhairyasheel; Longo, Anthony; Beyenbach, Klaus W; Denton, Jerod S; Piermarini, Peter M

    2013-01-01

    Mosquito-borne diseases such as malaria and dengue fever take a large toll on global health. The primary chemical agents used for controlling mosquitoes are insecticides that target the nervous system. However, the emergence of resistance in mosquito populations is reducing the efficacy of available insecticides. The development of new insecticides is therefore urgent. Here we show that VU573, a small-molecule inhibitor of mammalian inward-rectifying potassium (Kir) channels, inhibits a Kir channel cloned from the renal (Malpighian) tubules of Aedes aegypti (AeKir1). Injection of VU573 into the hemolymph of adult female mosquitoes (Ae. aegypti) disrupts the production and excretion of urine in a manner consistent with channel block of AeKir1 and renders the mosquitoes incapacitated (flightless or dead) within 24 hours. Moreover, the toxicity of VU573 in mosquitoes (Ae. aegypti) is exacerbated when hemolymph potassium levels are elevated, suggesting that Kir channels are essential for maintenance of whole-animal potassium homeostasis. Our study demonstrates that renal failure is a promising mechanism of action for killing mosquitoes, and motivates the discovery of selective small-molecule inhibitors of mosquito Kir channels for use as insecticides. PMID:23734226

  18. Sorting nexin 27 regulation of G protein-gated inwardly rectifying K⁺ channels attenuates in vivo cocaine response.

    PubMed

    Munoz, Michaelanne B; Slesinger, Paul A

    2014-05-01

    The subcellular pathways that regulate G protein-gated inwardly rectifying potassium (GIRK or Kir3) channels are important for controlling the excitability of neurons. Sorting nexin 27 (SNX27) is a PDZ-containing protein known to bind GIRK2c/GIRK3 channels, but its function in vivo is poorly understood. Here, we investigated the role of SNX27 in regulating GIRK currents in dopamine (DA) neurons of the ventral tegmental area (VTA). Mice lacking SNX27 in DA neurons exhibited reduced GABABR-activated GIRK currents but had normal Ih currents and DA D2R-activated GIRK currents. Expression of GIRK2a, an SNX27-insensitive splice variant, restored GABABR-activated GIRK currents in SNX27-deficient DA neurons. Remarkably, mice with significantly reduced GABABR-activated GIRK currents in only DA neurons were hypersensitive to cocaine and could be restored to a normal locomotor response with GIRK2a expression. These results identify a pathway for regulating excitability of VTA DA neurons, highlighting SNX27 as a promising target for treating addiction. PMID:24811384

  19. High-fat diet-dependent modulation of the delayed rectifier K(+) current in adult guinea pig atrial myocytes.

    PubMed

    Aromolaran, Ademuyiwa S; Colecraft, Henry M; Boutjdir, Mohamed

    2016-06-01

    Obesity is associated with hyperlipidemia, electrical remodeling of the heart, and increased risk of supraventricular arrhythmias in both male and female patients. The delayed rectifier K(+) current (IK), is an important regulator of atrial repolarization. There is a paucity of studies on the functional role of IK in response to obesity. Here, we assessed the obesity-mediated functional modulation of IK in low-fat diet (LFD), and high-fat diet (HFD) fed adult guinea pigs. Guinea pigs were randomly divided into control and obese groups fed, ad libitum, with a LFD (10 kcal% fat) or a HFD (45 kcal% fat) respectively. Action potential duration (APD), and IK were studied in atrial myocytes and IKr and IKs in HEK293 cells using whole-cell patch clamp electrophysiology. HFD guinea pigs displayed a significant increase in body weight, total cholesterol and total triglycerides within 50 days. Atrial APD at 30% (APD30) and 90% (APD90) repolarization were shorter, while atrial IK density was significantly increased in HFD guinea pigs. Exposure to palmitic acid (PA) increased heterologously expressed IKr and IKs densities, while oleic acid (OA), severely reduced IKr and had no effect on IKs. The data are first to show that in obese guinea pigs abbreviated APD is due to increased IK density likely through elevations of PA. Our findings may have crucial implications for targeted treatment options for obesity-related arrhythmias. PMID:27130822

  20. Molecular and functional characterization of Anopheles gambiae inward rectifier potassium (Kir1) channels: A novel role in egg production

    PubMed Central

    Raphemot, Rene; Estévez-Lao, Tania Y.; Rouhier, Matthew F.; Piermarini, Peter M.; Denton, Jerod S.; Hillyer, Julián F.

    2014-01-01

    Inward rectifier potassium (Kir) channels play essential roles in regulating diverse physiological processes. Although Kir channels are encoded in mosquito genomes, their functions remain largely unknown. In this study, we identified the members of the Anopheles gambiae Kir gene family and began to investigate their function. Notably, we sequenced the A. gambiae Kir1 (AgKir1) gene and showed that it encodes all the canonical RIP features of a Kir channel: an ion pore that is composed of a pore helix and a selectivity filter, two transmembrane domains that flank the ion pore, and the so-called G-loop. Heterologous expression of AgKir1 in Xenopus oocytes revealed that this gene encodes a functional, barium-sensitive Kir channel. Quantitative RT-PCR experiments then showed that relative AgKir1 mRNA levels are highest in the pupal stage, and that AgKir1 mRNA is enriched in the adult ovaries. Gene silencing of AgKir1 by RNA interference did not affect the survival of female mosquitoes following a blood in mosquito fecundity, and further validates them as promising molecular targets for the meal, but decreased their egg output. These data provide evidence for a new role of Kir channels development of a new class of mosquitocides to be used in vector control. PMID:24855023

  1. Performance of a Thin-Wndow Silicon Drift Detector X-Ray Fluorescence Spectrometer

    SciTech Connect

    Carini, G.; Chen, W.; De Geronimo, G.; Gaskin, J.; Keister, J.; Li, Z.; Ramey, B.; Rehak, P. and Siddons, P.

    2009-10-01

    Several sets of hexagonal Silicon Drift Detector (SDD) arrays were produced by Brookhaven National Laboratory (BNL) and by the commercial vendor, KETEK. These detector arrays were tested at BNL. Each array consists of 14 independent SDD detectors (pixels) and two additional test pixels located at two corners of the array. The side of the detector upon which the X-ray radiation is incident (window side) has a thin junction covering the entire active area. The opposite side (device side) contains a drift-field electrode structure in the form of a hexagonal spiral and an electron collecting anode. There are four guard rings surrounding the 14-pixel array area on each side of the detector. Within each array, seven pixels have aluminum field plates - interrupted spirals that stabilize the electric potential under the Si-SiO{sub 2} interface, while the other seven do not. Three bias voltages are applied to control the drift field in the silicon volume; one is applied to a rectifying contact surrounding the central anode (one for each pixel), one is applied to the detector entrance window (common to the full array), and a third bias is applied to a contact on the outer portion of the spiral, common to all pixels in the array. Some arrays were recently tested in NSLS beam line U3C at BNL. For this work, we installed the complete assemblies in the vacuum and cooled them to -27degC. During this beam run, we collected spectra for energies ranging between 350 and 900 eV in several pixels, some with field plates and others without. The detailed testing results of several arrays are reported here.

  2. High-voltage 4H-SiC trench MOS barrier Schottky rectifier with low forward voltage drop using enhanced sidewall layer

    NASA Astrophysics Data System (ADS)

    Cho, Doohyung; Sim, Seulgi; Park, Kunsik; Won, Jongil; Kim, Sanggi; Kim, Kwangsoo

    2015-12-01

    In this paper, a 4H-SiC trench MOS barrier Schottky (TMBS) rectifier with an enhanced sidewall layer (ESL) is proposed. The proposed structure has a high doping concentration at the trench sidewall. This high doping concentration improves both the reverse blocking and forward characteristics of the structure. The ESL-TMBS rectifier has a 7.4% lower forward voltage drop and a 24% higher breakdown voltage. However, this structure has a reverse leakage current that is approximately three times higher than that of a conventional TMBS rectifier owing to the reduction in energy barrier height. This problem is solved when ESL is used partially, since its use provides a reverse leakage current that is comparable to that of a conventional TMBS rectifier. Thus, the forward voltage drop and breakdown voltage improve without any loss in static and dynamic characteristics in the ESL-TMBS rectifier compared with the performance of a conventional TMBS rectifier.

  3. Crystalline Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Green, Martin A.

    2015-10-01

    The following sections are included: * Overview * Silicon cell development * Substrate production * Cell processing * Cell costs * Opportunities for improvement * Silicon-supported thin films * Summary * Acknowledgement * References

  4. Functional Role of CLC-2 Chloride Inward Rectifier Channels in Cardiac Sinoatrial Nodal Pacemaker Cells

    PubMed Central

    Huang, Z. Maggie; Prasad, Chaithra; Britton, Fiona C.; Ye, Linda L.; Hatton, William J.; Duan, Dayue

    2009-01-01

    A novel Cl− inward rectifier channel (Cl,ir) encoded by ClC-2, a member of the ClC voltage-gated Cl− channel gene superfamily, has been recently discovered in cardiac myocytes of several species. However, the physiological role of Cl,ir channels in the heart remains unknown. In this study we tested the hypothesis that Cl,ir channels may play an important role in cardiac pacemaker activity. In isolated guinea-pig sinoatrial node (SAN) cells, Cl,ir current was activated by hyperpolarization and hypotonic cell swelling. RT-PCR and immunohistological analyses confirmed the molecular expression of ClC-2 in guinea-pig SAN cells. Hypotonic stress increased the diastolic depolarization slope and decreased the maximum diastolic potential, action potential amplitude, APD50, APD90, and the cycle-length of the SAN cells. These effects were largely reversed by intracellular dialysis of anti-ClC-2 antibody, which significantly inhibited Cl,ir current but not other pacemaker currents, including the hyperpolarization-activated non-selective cationic “funny” current (If), the L-type Ca2+ currents (ICa,L), the slowly-activating delayed rectifier IKs and the volume-regulated outwardly-rectifying Cl− current (ICl,vol). Telemetry electrocardiograph studies in conscious ClC-2 knockout (Clcn2−/−) mice revealed a decreased chronotropic response to acute exercise stress when compared to their age-matched Clcn2+/+ and Clcn2+/− littermates. Targeted inactivation of ClC-2 does not alter intrinsic heart rate but prevented the positive chronotropic effect of acute exercise stress through a sympathetic regulation of ClC-2 channels. These results provide compelling evidence that ClC-2-encoded endogenous Cl,ir channels may play an important role in the regulation of cardiac pacemaker activity, which may become more prominent under stressed or pathological conditions. PMID:19376127

  5. Liquid-phase reaction-bonding of silicon carbide using alloyed silicon-molybdenum melts

    SciTech Connect

    Messner, R.P.; Chiang, Y.M. . Dept. of Materials Science and Engineering)

    1990-05-01

    The authors have investigated reaction-forming of silicon carbide by the infiltration of carbonaceous preforms using alloyed silicon melts, in order to synthesize composite materials free of the residual silicon phase that has previously limited mechanical properties and upper use temperatures. In this approach, rejection of the alloying component(s) from the primary silicon carbide phase into the remaining melt results in the formation of a secondary refractory phase, such as a silicide, in place of residual free silicon. Experiments conducted in the Si-Mo melt system show that relatively dense ({gt}90%) silicon carbide-molybdenum silicide materials free of residual silicon and residual carbon can be obtained. A model for reactive infiltration based on time-dependent permeabilities is proposed. Processing variables important for control of the reaction rate relative to the infiltration rate, and associated processing flaws, are discussed.

  6. In situ ZnO nanowire growth to promote the PVDF piezo phase and the ZnO-PVDF hybrid self-rectified nanogenerator as a touch sensor.

    PubMed

    Li, Zetang; Zhang, Xu; Li, Guanghe

    2014-03-28

    A PVDF-ZnO nanowires (NWs) hybrid generator (PZHG) was designed. A simple, cost effective method to produce the PVDF β phase by nano force is introduced. With the ZnO NWs growing, the in situ nano extension force promotes the phase change. A theoretical analysis of the ZnO NWs acting as a self-rectifier of the nano generator is established. The ZnO NWs acted as a self-adjustment diode to control the current output of the PZHG by piezo-electric and semi-conductive effects. Based on the self-controllability of the piezoelectric output, three kinds of finger touching are distinguished by the output performances of the PZHG, which is applicable to an LCD touch pad. PMID:24515250

  7. Semiconductor systems utilizing materials that form rectifying junctions in both N and P-type doping regions, whether metallurgically or field induced, and methods of use

    DOEpatents

    Welch, James D.

    2000-01-01

    Disclosed are semiconductor systems, such as integrated circuits utilizing Schotky barrier and/or diffused junction technology, which semiconductor systems incorporate material(s) that form rectifying junctions in both metallurgically and/or field induced N and P-type doping regions, and methods of their use. Disclosed are Schottky barrier based inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to multiple device CMOS systems and which can be operated as modulators, N and P-channel MOSFETS and CMOS formed therefrom, and (MOS) gate voltage controlled rectification direction and gate voltage controlled switching devices, and use of such material(s) to block parasitic current flow pathways. Simple demonstrative five mask fabrication procedures for inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to multiple device CMOS systems are also presented.

  8. Silicon Micromachined Microlens Array for THz Antennas

    NASA Technical Reports Server (NTRS)

    Lee, Choonsup; Chattopadhyay, Goutam; Mehdi, IImran; Gill, John J.; Jung-Kubiak, Cecile D.; Llombart, Nuria

    2013-01-01

    5 5 silicon microlens array was developed using a silicon micromachining technique for a silicon-based THz antenna array. The feature of the silicon micromachining technique enables one to microfabricate an unlimited number of microlens arrays at one time with good uniformity on a silicon wafer. This technique will resolve one of the key issues in building a THz camera, which is to integrate antennas in a detector array. The conventional approach of building single-pixel receivers and stacking them to form a multi-pixel receiver is not suited at THz because a single-pixel receiver already has difficulty fitting into mass, volume, and power budgets, especially in space applications. In this proposed technique, one has controllability on both diameter and curvature of a silicon microlens. First of all, the diameter of microlens depends on how thick photoresist one could coat and pattern. So far, the diameter of a 6- mm photoresist microlens with 400 m in height has been successfully microfabricated. Based on current researchers experiences, a diameter larger than 1-cm photoresist microlens array would be feasible. In order to control the curvature of the microlens, the following process variables could be used: 1. Amount of photoresist: It determines the curvature of the photoresist microlens. Since the photoresist lens is transferred onto the silicon substrate, it will directly control the curvature of the silicon microlens. 2. Etching selectivity between photoresist and silicon: The photoresist microlens is formed by thermal reflow. In order to transfer the exact photoresist curvature onto silicon, there needs to be etching selectivity of 1:1 between silicon and photoresist. However, by varying the etching selectivity, one could control the curvature of the silicon microlens. The figure shows the microfabricated silicon microlens 5 x5 array. The diameter of the microlens located in the center is about 2.5 mm. The measured 3-D profile of the microlens surface has a

  9. Development of thermal rectifier using unusual electron thermal conductivity of icosahedral quasicrystals

    NASA Astrophysics Data System (ADS)

    Takeuchi, Tsunehiro

    2015-03-01

    The bulk thermal rectifiers usable at high temperature were developed using the unusual increase of electron thermal conductivity of icosahedral quasicrystals (ICQ's) at high temperature. Our previously performed analyses in terms of linear response theory suggested that the unusual increase of electron thermal conductivity of ICQ was brought about by the synergy effect of quasiperiodicity and narrow pseudogap at the Fermi level. Since the linear response theory suggests that the unusual increase of electron thermal conductivity is coupled with the small magnitude of Seebeck coefficient, the composition of Al-Cu-Fe ICQ, where the thermal conductivity shows the most significant increase with increasing temperature, was determined with a great help of Seebeck coefficient measurements. Consequently obtained Al61.5Cu26.5Fe12.0 ICQ, which was characterized by the small magnitude of Seebeck coefficient, possessed 9 times larger value of thermal conductivity at 1000 K than that observed at 300 K. The increasing tendency of electron thermal conductivity with increasing temperature was further enhanced by means of small amount of Re substitution for Fe. This substitution definitely reduced the lattice thermal conductivity while the electron thermal conductivity was kept unchanged. The lattice thermal conductivity was reduced by 35 % under the presence of 0.5 at.% Re, and the thermal conductivity at 1000 K consequently became about 11 times larger than that at 300 K. The thermal rectifiers were constructed using our newly developed ICQ (Al61.5Cu26.5Fe12.0 or Al61.0Si0.5Cu26.5Fe11.5Re0.5) together with one of the selected materials (Si, Al2O3, CuGeTe2 or Ag2Te) that possess thermal conductivity decreasing with increasing temperature. The heat current flowing in the rectifiers was confirmed to show significant direction dependence. The consequently obtained TRR =|Jlarge|/ |Jsmall | for the composite consisting of

  10. (99m)Tc-HMDP scintigraphy rectifies wrong diagnosis of AL amyloidosis.

    PubMed

    Galat, Arnault; Van Der Gucht, Axel; Colombat, Magali; Attias, David; Itti, Emmanuel; Meignan, Michel; Lebras, Fabien; Molinier-Frenkel, Valérie; Benhaiem, Nicole; Guellich, Aziz; Rosso, Jean; Damy, Thibaud

    2015-08-01

    A 71-year-old African man without history of cardiac disease was referred to our center for dyspnea. Transthoracic echocardiogram and cardiac MRI were suggestive of cardiac amyloidosis (CA). The diagnosis of the light-chain cardiac amyloidosis (AL-CA) was made after a first endomyocardial biopsy. Accordingly chemotherapy was started. Systematic 99mTc-HMDP scintigraphy showed moderate cardiac uptake (visual score of 2), unusual for AL-CA, and permitted to rectify the diagnosis. Hereditary transthyretin cardiac amyloidosis was confirmed by a second endomyocardial biopsy with a positive Congo-red and anti-transthyretin antibody stainings, mass spectrometry and genetic analysis (Val122Ile mutation). PMID:26002815

  11. Rotation Driven by Rectified RF-sheath Potentials and Spatial Dispersion

    SciTech Connect

    Hellsten, T.

    2009-11-26

    Plasma rotation is of interest for improving confinement and stabilising plasma. Effects from fast particles with broad orbits can only partly explain the changes in the rotation profiles during ICRH. The effect on wave-particle interaction of a finite poloidal mode number is discussed and two new RF-mechanisms are proposed: Co-current torque caused by sputtering by rectified RF-sheath potentials and transport of momentum due to spatial dispersion. The latter effect affects the RF-current drive, in particular, in conjunction with mode conversion.

  12. Rectifying the Optical-Field-Induced Current in Dielectrics: Petahertz Diode

    NASA Astrophysics Data System (ADS)

    Lee, J. D.; Yun, Won Seok; Park, Noejung

    2016-02-01

    Investigating a theoretical model of the optical-field-induced current in dielectrics driven by strong few-cycle laser pulses, we propose an asymmetric conducting of the current by forming a heterojunction made of two distinct dielectrics with a low hole mass (mh*≪me*) and low electron mass (me*≪mh* ), respectively. This proposition introduces the novel concept of a petahertz (1015 Hz ) diode to rectify the current in the petahertz domain, which should be a key ingredient for the electric signal manipulation of future light-wave electronics. Further, we suggest the candidate dielectrics for the heterojunction.

  13. Rectifying performance and negative differential behavior in graphite—chain—carbon nanotube junctions

    SciTech Connect

    Qiu, Ming; Li, Jiangfan; Liew, K. M.; Yuan, Chris

    2014-01-13

    In this paper, the (5, 5) capped carbon nanotubes (CNTs) in contact with different lengths of sp monoatomic chains grown on the surface of graphite substrate are fabricated and its electronic transport properties sandwiched between CNT and graphite electrodes are investigated. The first-principles calculations based on nonequilibrium Green's function in combination with density-functional theory show that their rectifying performance and negative differential resistance behavior are observed under very low biases and obviously are enhanced when the length increases. From our analysis, the charge transfer, transmission spectra, projected density of states and evolutions of molecular orbitals are responsible for these phenomena.

  14. Rectifying performance and negative differential behavior in graphite—chain—carbon nanotube junctions

    NASA Astrophysics Data System (ADS)

    Qiu, Ming; Li, Jiangfan; Liew, K. M.; Yuan, Chris

    2014-01-01

    In this paper, the (5, 5) capped carbon nanotubes (CNTs) in contact with different lengths of sp monoatomic chains grown on the surface of graphite substrate are fabricated and its electronic transport properties sandwiched between CNT and graphite electrodes are investigated. The first-principles calculations based on nonequilibrium Green's function in combination with density-functional theory show that their rectifying performance and negative differential resistance behavior are observed under very low biases and obviously are enhanced when the length increases. From our analysis, the charge transfer, transmission spectra, projected density of states and evolutions of molecular orbitals are responsible for these phenomena.

  15. Current-driven antivortex core resonance measured by the rectifying effect

    NASA Astrophysics Data System (ADS)

    Goto, Minori; Nozaki, Yukio

    2016-02-01

    We demonstrate the current-driven resonance of a single antivortex core confined in a cross-shaped Ni81Fe19 wire. The antivortex core dynamics can be excited purely by spin transfer torque; therefore, it is significant to understand the current-induced magnetization dynamics. The antivortex core resonance can be measured from the frequency dependence of a rectified voltage generated by an alternating current application. We found that the resonance frequency and peak amplitude greatly depend on the external magnetic field. This result is in good agreement with micromagnetic simulation.

  16. Properties of the inwardly rectifying K+ conductance in the toad retinal pigment epithelium.

    PubMed Central

    Segawa, Y; Hughes, B A

    1994-01-01

    An inwardly rectifying K+ current was analysed in isolated toad retinal pigment epithelial (RPE) cells using the perforated-patch clamp technique. The zero-current potential (Vo) of RPE cells averaged -71 mV when the extracellular K+ concentration ([K+]o) was 2 mM. Increasing [K+]o from 0.5 to 5 mM shifted V0 by +43 mV, indicating a relative K+ conductance (TK) of 0.74. At [K+]o greater than 5 mM, TK decreased to 0.53. Currents were larger in response to hyperpolarizing voltage pulses than depolarizing pulses, indicating an inwardly rectifying conductance. Currents were time independent except in response to voltage pulses to potentials positive to 0 mV, where the outward current decayed with an exponential time course. Both the inwardly rectifying current and the transient outward current were eliminated by the addition of 0.5 mM Ba2+, 5 mM Cs+ or 2 mM Rb+ to the extracellular solution. The current blocked by these ions reversed near the K+ equilibrium potential (EK) over a wide range of [K+]o, indicating a highly selective K+ channel. The current-voltage relationship of the isolated K+ current exhibited mild inward rectification at voltages negative to -20 mV and a negative slope conductance at voltages positive to -20 mV. The Cs(+)- and Ba(2+)-induced blocks of the K+ current were concentration dependent but voltage independent. The apparent dissociation constants were 0.8 mM for Cs+ and 40 microM for Ba2+. The K+ conductance decreased when extracellular Na+ was removed. Increasing [K+]o decreased the K+ chord conductance (gK) at negative membrane potentials. In the physiological voltage range, increasing [K+]o from 2 to 5 mM caused gK to decrease by approximately 25%. We conclude that the inwardly rectifying K+ conductance represents the resting K+ conductance of the toad RPE apical membrane. The unusual properties of this conductance may enhance the ability of the RPE to buffer [K+]o changes that take place in the subretinal space at the transition between

  17. Filament Guides for Silicon-Ribbon Growth

    NASA Technical Reports Server (NTRS)

    Morrison, A. D.

    1985-01-01

    Contamination reduced in modified growth system. In Silicon-ribbongrowth apparatus, capillary filament guides are integral parts of crucible, extending from bottom to top of melt. Addition of guides expected to result in better thermal control of growth process and higher silicon purity.

  18. Asymmetric Die Grows Purer Silicon Ribbon

    NASA Technical Reports Server (NTRS)

    Kalejs, J. P.; Chalmers, B.; Surek, T.

    1983-01-01

    Concentration of carbide impurities in silicon ribbon is reduced by growing crystalline ribbon with die one wall higher than other. Height difference controls shape of meniscus at liquid/crystal interface and concentrates silicon carbide impurity near one of broad faces. Opposite face is left with above-average purity. Significantly improves efficiency of solar cells made from ribbon.

  19. Sodium Spray Would Speed Silicon Production

    NASA Technical Reports Server (NTRS)

    Sancier, K. M.

    1983-01-01

    Production rate of solar-grade silicon in sodium/silicon tetrafluoride reactor increase by spray feed. Liquid-sodium droplet size is controlled by pressure of argon gas and by nozzle design. Baffle helps to prevent reactor opening from becoming clogged by reaction products.

  20. Use of silicon-versus-layout verification (SiVL) in process control of wafer lithography and mask-making metrology

    NASA Astrophysics Data System (ADS)

    van Adrichem, Paul J. M.; Driessen, Frank A. J. M.; van Hasselt, Kees

    2003-05-01

    The latest generations of CMOS are being patterned at decreasing k1 values, which is one of the reasons that their process windows are decreasing. Hence, control of the process gets more and more important and in-die critical dimension (CD) measurements are gradually being introduced for the monitoring of the in-line lithographic process performance. Because an increasingly large portion of the CD-error-budget is already being consumed by the mask-making, there is also a strong tendency toward improving process control of the mask, which in turn leads to a rapid increase in the number of mask-CD measurements even within the die. The main two reasons for the larger contribution of the mask to the error budget at wafer level are: 1) the mask process itself, and 2) the mask-error enhancement factor (MEEF), the magnification factor of reticle-to-wafer error. The latter factor and its lithographic process dependence are very much depending on the shape of a feature and its local vicinity. For example a narrow dense binary line has a larger MEEF than an isolated line and its partial derivative to defocus is much larger. Hence it would make sense to relate such MEEF process-behaviour to the 2D layout shapes in the design and use that as a metric during mask qualification. In this work the Silicon-versus-layout verification (SiVL) tool- inherently an OPC evaluation tool- is used to find such features in the layout that will be most critical for the wafer lithographic process by automatic extraction and selection of their MEEF values. This information can then be used to generate realistic mask specifications and forms a cost-method to control both mask quality and price.

  1. Comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier.

    PubMed

    Tsai, Cheng-Tao; Su, Jye-Chau; Tseng, Sheng-Yu

    2013-01-01

    This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications. PMID:24381521

  2. Control and expression of -NH2, -SH, -COOH and SiO2 on the surface of silicon carbide quantum dots

    NASA Astrophysics Data System (ADS)

    Mwania, Munuve; Aguirre-Medel, Susana; Kroll, Peter

    2015-03-01

    We present simple protocols for reliably tailoring the surfaces of zinc blende silicon carbide quantum dots (β-SiC QDs). The SiC QDs are synthesized via photo-assisted electrochemical corrosion of bulk powders at different temperatures and time scales. After washing the residual acid and resuspending in H2O, the surfaces of SiC QDs were controllably coated with four different functional groups, specifically -NH2, -SH, and -COOH and -SiO2. We began by covalently attaching primary amines (-NH2) to the QD surface. The amine terminations were then converted to amine/thiolate (-NH2/SH) and amine/carboxylate (-NH2/COOH) functional groups. SiO2 shells around SiC QDs (to create SiC@SiO2nano-structures) were grown using a TEOS-mediated Stöber method. The presence of amine and thiol groups was confirmed by fluoresceamine assay test, X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR). While a negative fluoresceamine assay test confirmed the replacement of amine groups by thiol groups, the thiolation of the surface was also confirmed through Ellman's assay, XPS and FTIR. The presence of the SiO2 shells was examined using transmission electron microscopy and XPS. Our results open up possibilities to manipulate SiC QDs for various applications.

  3. Precise control of photoluminescence of silicon-vacancy color centers in homoepitaxial single-crystal diamond: evaluation of efficiency of Si doping from gas phase

    NASA Astrophysics Data System (ADS)

    Ralchenko, Victor; Sedov, Vadim; Saraykin, Vladimir; Bolshakov, Andrey; Zavedeev, Evgeny; Ashkinazi, Evgeny; Khomich, Andrew

    2016-09-01

    Ability to precisely control the Si-related color center abundance in diamond is important for the use of silicon-vacancy (SiV) defects with bright photoluminescence (PL) in quantum information technologies and optical biomarkers. Here, we evaluated the efficiency of Si incorporation in (100) plane of homoepitaxial diamond layers upon in situ doping by adding silane SiH4 in the course of diamond chemical vapor deposition in microwave plasma using CH4-H2 mixtures. Both the Si concentration in the doped samples, as determined by secondary ion mass spectrometry, and PL intensity of SiV centers at 738 nm wavelength, measured at excitation wavelength of 473 nm, demonstrate a linear increase with silane content in feed gas in the range. The incorporation efficiency f, defined as the ratio of Si concentration in diamond to that in gas, f = [Si/C]dia/[Si/C]gas is found to be (1.1 ± 0.5) × 10-3 for the silane concentrations explored, [SiH4/CH4] < 0.7 %; thus, the Si atoms are accommodated in (100) diamond face easier than nitrogen and phosphorus, but more difficult than boron. This finding allows a tailoring of the Si content and photoluminescence intensity of SiV centers in in situ doped CVD diamond.

  4. Silicon limitation on primary production and its destiny in Jiaozhou Bay, China. V: Silicon deficit process

    NASA Astrophysics Data System (ADS)

    Yang, Dongfang; Gao, Zhenhui; Wang, Peigang; Sun, Peiyan; Liu, Shuang

    2005-06-01

    Silicon is a necessary nutrient for diatoms, silicon uptake in diatom reproduction decreased seawater silicon content. This paper clarified the characteristics of silicon transferring in the sea, which plays an important role in phytoplankton growth, zooplankton graze and marine ecosystem. Analysis revealed that silicate is supplied by terrestrial sources, through plankton uptake, death, and eventually deposits to the sea bottom, and cannot diffuse upward. This is a general silicon deficit process. Many global marine waters showed the same silicon transfer route: land→silicon biogeochemical process→sea bottom. River flow brings abundant silicate into marine waters, silicate concentration in the waters decreased in the distance away from the river estuaries. In discussion of silicon characteristics and its transfer route, it was considred that the main factor controlling the mechanism of diatom and non-diatom red tides occurrence is silicon, and the changes in silicon source. Human activities, such as sea-route cutting by building embankment and dam, and silicon supplement by the sea, such as sandstorm, rainstorm and storm tide, have largely impaired the earth ecosystem and hugely threatened the human existence. It is suggested in this paper that man should resume the original face of the Si input into the sea to keep natural ecosystem in sustainable pattern.

  5. Power spectrum of the rectified EMG: when and why is rectification beneficial for identifying neural connectivity?

    NASA Astrophysics Data System (ADS)

    Negro, Francesco; Keenan, Kevin; Farina, Dario

    2015-06-01

    Objective. The identification of common oscillatory inputs to motor neurons in the electromyographic (EMG) signal power spectrum is often preceded by EMG rectification for enhancing the low-frequency oscillatory components. However, rectification is a nonlinear operator and its influence on the EMG signal spectrum is not fully understood. In this study, we aim at determining when EMG rectification is beneficial in the study of oscillatory inputs to motor neurons. Approach. We provide a full mathematical description of the power spectrum of the rectified EMG signal and the influence of the average shape of the motor unit action potentials on it. We also provide a validation of these theoretical results with both simulated and experimental EMG signals. Main results. Simulations using an advanced computational model and experimental results demonstrated the accuracy of the theoretical derivations on the effect of rectification on the EMG spectrum. These derivations proved that rectification is beneficial when assessing the strength of low-frequency (delta and alpha bands) common synaptic inputs to the motor neurons, when the duration of the action potentials is short, and when the level of cancellation is relatively low. On the other hand, rectification may distort the estimation of common synaptic inputs when studying higher frequencies (beta and gamma), in a way dependent on the duration of the action potentials, and may introduce peaks in the coherence function that do not correspond to physiological shared inputs. Significance. This study clarifies the conditions when rectifying the surface EMG is appropriate for studying neural connectivity.

  6. A new pH-sensitive rectifying potassium channel in mitochondria from the embryonic rat hippocampus.

    PubMed

    Kajma, Anna; Szewczyk, Adam

    2012-10-01

    Patch-clamp single-channel studies on mitochondria isolated from embryonic rat hippocampus revealed the presence of two different potassium ion channels: a large-conductance (288±4pS) calcium-activated potassium channel and second potassium channel with outwardly rectifying activity under symmetric conditions (150/150mM KCl). At positive voltages, this channel displayed a conductance of 67.84pS and a strong voltage dependence at holding potentials from -80mV to +80mV. The open probability was higher at positive than at negative voltages. Patch-clamp studies at the mitoplast-attached mode showed that the channel was not sensitive to activators and inhibitors of mitochondrial potassium channels but was regulated by pH. Moreover, we demonstrated that the channel activity was not affected by the application of lidocaine, an inhibitor of two-pore domain potassium channels, or by tertiapin, an inhibitor of inwardly rectifying potassium channels. In summary, based on the single-channel recordings, we characterised for the first time mitochondrial pH-sensitive ion channel that is selective for cations, permeable to potassium ions, displays voltage sensitivity and does not correspond to any previously described potassium ion channels in the inner mitochondrial membrane. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012). PMID:22406520

  7. Exploring the roles of standard rectifying circuits on the performance of a nonlinear piezoelectric energy harvester

    NASA Astrophysics Data System (ADS)

    Tang, Lihua; Han, Yue; Hand, James; Harne, Ryan L.

    2016-04-01

    To enhance the energy conversion performance of piezoelectric vibration energy harvesters, such structures have been recently designed to leverage bandwidth-enhancing nonlinear dynamics. While key findings have been made, the majority of researchers have evaluated the opportunities when the harvesters are connected to pure resistive loads (AC interface). The alternating voltage generated by such energy harvesting systems cannot be directly utilized to power conventional electronics. Rectifying circuits are required to interface the device and electronic load but few efforts have considered how a standard rectifying DC interface circuit (DC interface) connected to a nonlinear piezoelectric energy harvester influences the system performance. The aim of this research is to begin exploring this critical feature of the nonlinear energy harvesting system. A nonlinear, monostable piezoelectric energy harvester (MPEH) is fabricated and evaluated to determine the generated power and useful operating bandwidth when connected to a DC interface. The nonlinearity is introduced into the harvester design by tuneable magnetic force. An equivalent circuit model of the MPEH is implemented with a user-defined nonlinear behavioral voltage source representative of the magnetic interaction. The model is validated comparing the open circuit voltage from circuit simulation and experiment. The practical energy harvesting capability of the MPEH connected to the AC and DC interface circuits are then investigated and compared, focusing on the influence of the varying load on the nonlinear dynamics and subsequent bandwidth and harvested power.

  8. Simulation and Analysis of Three-Phase Rectifiers for Aerospace Power Applications

    NASA Technical Reports Server (NTRS)

    Truong, Long V.; Birchenough, Arthur G.

    2004-01-01

    Due to the nature of planned planetary missions, fairly large advanced power systems are required for the spacecraft. These future high power spacecrafts are expected to use dynamic power conversion systems incorporating high speed alternators as three-phase AC electrical power source. One of the early design considerations in such systems is the type of rectification to be used with the AC source for DC user loads. This paper address the issues involved with two different rectification methods, namely the conventional six and twelve pulses. Two circuit configurations which involved parallel combinations of the six and twelve-pulse rectifiers were selected for the simulation. The rectifier s input and output power waveforms will be thoroughly examined through simulations. The effects of the parasitic load for power balancing and filter components for reducing the ripple voltage at the DC loads are also included in the analysis. Details of the simulation circuits, simulation results, and design examples for reducing risk from damaging of spacecraft engines will be presented and discussed.

  9. One-Stage High-Frequency-Isolated Three-Phase PWM Rectifier

    NASA Astrophysics Data System (ADS)

    Sato, Shinji

    The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sinewave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC48 V. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. In addition, the power components of the power converter make the compact design of the power supply difficult. To resolve these problems, this paper presents a new PWM rectifier as a one-stage power conversion scheme. It experiment, it is proved from a practical point of view that 92.1% of conversion efficiency and input current which can meet harmonics regulation of the Class A in IEC61000-3-2 are achieved.

  10. Self-contained sub-millimeter wave rectifying antenna integrated circuit

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H. (Inventor)

    2004-01-01

    The invention is embodied in a monolithic semiconductor integrated circuit in which is formed an antenna, such as a slot dipole antenna, connected across a rectifying diode. In the preferred embodiment, the antenna is tuned to received an electromagnetic wave of about 2500 GHz so that the device is on the order of a wavelength in size, or about 200 microns across and 30 microns thick. This size is ideal for mounting on a microdevice such as a microrobot for example. The antenna is endowed with high gain in the direction of the incident radiation by providing a quarter-wavelength (30 microns) thick resonant cavity below the antenna, the cavity being formed as part of the monolithic integrated circuit. Preferably, the integrated circuit consists of a thin gallium arsenide membrane overlying the resonant cavity and supporting an epitaxial Gallium Arsenide semiconductor layer. The rectifying diode is a Schottky diode formed in the GaAs semiconductor layer and having an area that is a very small fraction of the wavelength of the 2500 GHz incident radiation. The cavity provides high forward gain in the antenna and isolation from surrounding structure.

  11. Processing of reaction-bonded silicon carbide without residual silicon phase

    SciTech Connect

    Messner, R.P.; Chiang, Y.M.

    1988-08-01

    Reaction-bonded silicon carbide free of the residual silicon phase that has previously limited upper use temperatures and mechanical properties has been synthesized by the infiltration of carbonaceous preforms using alloyed silicon melts. In this approach, rejection of the alloying components from the primary reacted silicon carbide phase into the remaining liquid forms a secondary refractory silicide, in a potentially broad and controllable range of volume fractions. Dense SiC-MoSi/sub 2/ materials free of residual silicon and residual carbon have been synthesized. In addition to a fully-infiltrated monolith, surface coatings on a carbon body have been synthesized by control of processing parameters. In each, the absence of free silicon and incorporation of the secondary phase is expected to improve mechanical properties. 14 references.

  12. Plasmas in saline solutions sustained using rectified ac voltages: polarity and frequency effects on the discharge behaviour

    NASA Astrophysics Data System (ADS)

    Chang, Hung-wen; Hsu, Cheng-che

    2012-06-01

    In this work, three major problems, namely severe electrode damage, poor plasma stability and excess power consumption, arising in ac-driven plasmas in saline solutions are solved using a rectified power source. Diagnostic studies on the effects of power source polarity and frequency on the plasma behaviour are performed. Examination of I-V characteristics and temporally resolved light emission shows that the polarity significantly influences the current amplitude when the plasma exists, while the frequency alters the bubble dynamics, which in turn affects the plasma ignition voltage. When the plasma is driven by a rectified ac power source, the electrode erosion is reduced substantially. With a low frequency, moderate applied voltage and positively rectified ac power source (e.g. 100 Hz and 350 V), a stable plasma is ignited in nearly every power cycle.

  13. Point defects in silicon carbide as a promising basis for spectroscopy of single defects with controllable quantum states at room temperature

    NASA Astrophysics Data System (ADS)

    Soltamov, V. A.; Tolmachev, D. O.; Il'in, I. V.; Astakhov, G. V.; Dyakonov, V. V.; Soltamova, A. A.; Baranov, P. G.

    2015-05-01

    The spin and optical properties of silicon vacancy defects in silicon carbide of the hexagonal 6 H polytype have been investigated using photoluminescence, electron paramagnetic resonance, and X-band optically detected magnetic resonance. It has been shown that different configurations of these defects can be used to create an optical alignment of their spin sublevels as in the case of low temperatures and at temperatures close to room temperature ( T = 293 K). The main specific feature of silicon vacancy centers in silicon carbide is that the zero-magnetic-field-splitting parameter of some centers remains constant with variations in the temperature, which indicates prospects for the use of these centers for quantum magnetometry. It has also been shown that a number of centers, on the contrary, are characterized by a strong dependence of the zero-magnetic-field-splitting parameter on the temperature, which indicates prospects for the use of these centers as temperature sensors.

  14. Thermal Conductivity of Size-Controlled Bulk Silicon Nanocrystals Using Self-Limiting Oxidation and HF Etching

    NASA Astrophysics Data System (ADS)

    Suzuki, Takayuki; Ohishi, Yuji; Kurosaki, Ken; Muta, Hiroaki; Yamanaka, Shinsuke

    2012-08-01

    We propose a new method of obtaining low thermal conductivity in bulk Si. In this method, which we call “HF-etching nanosize-controlling process for powder” (HNPP), self-limiting oxidation coupled with HF etching is applied to nanopowder Si. The application of HNPP to nanopowder Si reduces the average diameter from 58 to 35 nm. The thermal conductivity is reduced from 25.7 to 13.5 W m-1 K-1 at 300 K. Theoretical calculation including grain boundary transmission and frequency-dependent grain boundary scattering shows that these thermal conductivity reductions can be attributed to phonon scattering at grain boundaries.

  15. Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method

    NASA Astrophysics Data System (ADS)

    Seike, Yoshiyuki; Miyachi, Keiji; Shibata, Tatsuo; Kobayashi, Yoshinori; Kurokawa, Syuhei; Doi, Toshiro

    2010-06-01

    A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 µm or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.

  16. Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method

    NASA Astrophysics Data System (ADS)

    Yoshiyuki Seike,; Keiji Miyachi,; Tatsuo Shibata,; Yoshinori Kobayashi,; Syuhei Kurokawa,; Toshiro Doi,

    2010-06-01

    A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 μm or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.

  17. Upgrading Metallurgical-Grade Silicon

    NASA Technical Reports Server (NTRS)

    Woerner, L. M.; Moore, E. B.

    1985-01-01

    Closed-loop process produces semiconductor-grade silicon. Metallurgical-grade silicon converted to ultrapure silicon by reacting with hydrogen and silicon tetrahalide to form trihalosilane, purifying this intermediate and again decomposing to high purity silicon in third stage. Heterogeneously and homogeneously nucleated polycrystalline silicon used in semiconductor device applications and in silicon photovoltaic solar cell fabrication.

  18. Silicon Micromachining

    NASA Astrophysics Data System (ADS)

    Elwenspoek, Miko; Jansen, Henri V.

    2004-08-01

    This comprehensive book provides an overview of the key techniques used in the fabrication of micron-scale structures in silicon. Recent advances in these techniques have made it possible to create a new generation of microsystem devices, such as microsensors, accelerometers, micropumps, and miniature robots. The authors underpin the discussion of each technique with a brief review of the fundamental physical and chemical principles involved. They pay particular attention to methods such as isotropic and anisotropic wet chemical etching, wafer bonding, reactive ion etching, and surface micromachining. There is a special section on bulk micromachining, and the authors also discuss release mechanisms for movable microstructures. The book is a blend of detailed experimental and theoretical material, and will be of great interest to graduate students and researchers in electrical engineering and materials science whose work involves the study of micro-electromechanical systems (MEMS).

  19. Suprachiasmatic nucleus function and circadian entrainment are modulated by G protein-coupled inwardly rectifying (GIRK) channels

    PubMed Central

    Hablitz, L M; Molzof, H E; Paul, J R; Johnson, R L; Gamble, K L

    2014-01-01

    Abstract G protein signalling within the central circadian oscillator, the suprachiasmatic nucleus (SCN), is essential for conveying time-of-day information. We sought to determine whether G protein-coupled inwardly rectifying potassium channels (GIRKs) modulate SCN physiology and circadian behaviour. We show that GIRK current and GIRK2 protein expression are greater during the day. Pharmacological inhibition of GIRKs and genetic loss of GIRK2 depolarized the day-time resting membrane potential of SCN neurons compared to controls. Behaviourally, GIRK2 knockout (KO) mice failed to shorten free running period in response to wheel access in constant darkness and entrained more rapidly to a 6 h advance of a 12 h:12 h light–dark (LD) cycle than wild-type (WT) littermate controls. We next examined whether these effects were due to disrupted signalling of neuropeptide Y (NPY), which is known to mediate non-photic phase shifts, attenuate photic phase shifts and activate GIRKs. Indeed, GIRK2 KO SCN slices had significantly fewer silent cells in response to NPY, likely contributing to the absence of NPY-induced phase advances of PER2::LUC rhythms in organotypic SCN cultures from GIRK2 KO mice. Finally, GIRK channel activation is sufficient to cause a non-photic-like phase advance of PER2::LUC rhythms on a Per2Luc+/− background. These results suggest that rhythmic regulation of GIRK2 protein and channel function in the SCN contributes to day-time resting membrane potential, providing a mechanism for the fine tuning responses to non-photic and photic stimuli. Further investigation could provide insight into disorders with circadian disruption comorbidities such as epilepsy and addiction, in which GIRK channels have been implicated. PMID:25217379

  20. Thin silicon solar cells

    SciTech Connect

    Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M.

    1992-12-01

    The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

  1. Silicon Web Process Development

    NASA Technical Reports Server (NTRS)

    Duncan, C. S.; Seidensticker, R. G.; Hopkins, R. H.; Mchugh, J. P.; Hill, F. E.; Heimlich, M. E.; Driggers, J. M.

    1978-01-01

    Progress in the development of techniques to grow silicon web at 25 wq cm/min output rate is reported. Feasibility of web growth with simultaneous melt replenishment is discussed. Other factors covered include: (1) tests of aftertrimmers to improve web width; (2) evaluation of growth lid designs to raise speed and output rate; (3) tests of melt replenishment hardware; and (4) investigation of directed gas flow systems to control unwanted oxide deposition in the system and to improve convective cooling of the web. Compatibility with sufficient solar cell performance is emphasized.

  2. Controlled Nitrogen Atom Incorporation at Silicon - Dioxide Interfaces by a New, Low-Temperature Remote Plasma Process

    NASA Astrophysics Data System (ADS)

    Lee, David Roger

    1995-01-01

    A new, low-temperature (300^circ C), remote plasma process has been developed for incorporating controlled amounts of N-atoms at Si-SiO _2 interfaces and has been shown to improve the quality and reliability of Metal-Oxide-Semiconductor (MOS) devices. The process involves exposing an ex-situ cleaned wafer to species from a remote N_2 O plasma as a prelude to Remote Plasma Enhanced Chemical Vapor Deposition (Remote PECVD) of gate-quality SiO_2 films. Auger Electron Spectroscopy (AES) studies and Secondary Ion Mass Spectrometry (SIMS) depth profiles have been used to investigate the chemical nature of the Si-SiO_2 interface formed by this new technique. The results indicate that this pre-deposition process (1) removed residual carbon to ~10^{12 } C-atoms/cm^2, (2) resulted in the remote plasma-assisted growth of ~0.5 nm of SiO_2, and (3) incorporated controllably between 10^ {14}-10^{15} N-atoms/cm^2 at the Si-SiO _2 interface. Optical Second Harmonic Generation (SHG) spectroscopy has shown that the N-atoms are bonded to Si-atoms at the Si-SiO_2 interface and relieve chemical strain in adjacent Si-Si bonds relative to the case where only O-atoms are bonded at the interface. This N_2O remote plasma, predeposition oxidation process was used in a cluster tool manufacturing test bed for the fabrication of MOS capacitors and Field-Effect Transistors (FETs). Remote PECVD oxides with and without nitrided interfaces were compared, and N-atom incorporation by this technique was found to improve the drive current and high-field electron mobility of n -MOSFETs while not adversely affecting the threshold voltage, V_{rm t}, or peak channel transconductance, g_{rm m}, of the devices. N-atom incorporation also suppressed hot-carrier damage in the gate dielectric of sub-micron (effective channel length ~ 0.64 μm) n-MOSFETs. In particular, peak g_{rm m}, V _{rm t}, and the slope of the subthreshold current are all degraded less with increasing N-atom concentrations at the Si-SiO _2

  3. Buried oxide layer in silicon

    DOEpatents

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  4. Controlled dissolution of silicon dioxide layers for depth resolved multielement analysis by inductively coupled plasma-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Lorge, Susan E.; Houk, R. S.

    2009-11-01

    Dissolution procedures were developed to control the number of surface layers removed, in an attempt to achieve depth resolved analysis by inductively coupled plasma-mass spectrometry (ICP-MS). NIST 612 glass was chosen because it is a homogeneous material with many elements at interesting concentrations, ~ 50 ppm. Varying dissolution time and HF concentration resulted in the reproducible removal of SiO 2 layers as thin as 70 Å deep. Dissolved trace metals were determined after dilution by inductively coupled plasma-mass spectrometry (ICP-MS) with a magnetic sector instrument. The amount removed was determined from the concentration of a major element, Ca. With the exception of Zn, trace metal concentrations agreed reasonably well with their certified values for removal depths of 500, 300 and 150 Å. Zinc concentration was significantly high in all dissolutions indicating either a contamination problem or that Zn is removed at a faster rate than Ca. For the dissolutions that removed 70 Å of SiO 2, Cr, Mn, Co, Sr, Cd, Ce, Dy, Er, Yb and U recovery results agreed with their certified values (~ 50 ppm); Ti, As, Mo, Ba, and Th could not be determined because net intensities were below 3 σ of the blank; and measured concentrations for Cu, Pb and Zn were well above the certified values.

  5. Colloidal characterization of silicon nitride and silicon carbide

    NASA Technical Reports Server (NTRS)

    Feke, Donald L.

    1986-01-01

    The colloidal behavior of aqueous ceramic slips strongly affects the forming and sintering behavior and the ultimate mechanical strength of the final ceramic product. The colloidal behavior of these materials, which is dominated by electrical interactions between the particles, is complex due to the strong interaction of the solids with the processing fluids. A surface titration methodology, modified to account for this interaction, was developed and used to provide fundamental insights into the interfacial chemistry of these systems. Various powder pretreatment strategies were explored to differentiate between true surface chemistry and artifacts due to exposure history. The colloidal behavior of both silicon nitride and carbide is dominated by silanol groups on the powder surfaces. However, the colloid chemistry of silicon nitride is apparently influenced by an additional amine group. With the proper powder treatments, silicon nitride and carbide powder can be made to appear colloidally equivalent. The impact of these results on processing control will be discussed.

  6. Passivation of InGaAs(001)-(2 × 4) by Self-Limiting Chemical Vapor Deposition of a Silicon Hydride Control Layer.

    PubMed

    Edmonds, Mary; Kent, Tyler; Chagarov, Evgueni; Sardashti, Kasra; Droopad, Ravi; Chang, Mei; Kachian, Jessica; Park, Jun Hong; Kummel, Andrew

    2015-07-01

    A saturated Si-Hx seed layer for gate oxide or contact conductor ALD has been deposited via two separate self-limiting and saturating CVD processes on InGaAs(001)-(2 × 4) at substrate temperatures of 250 and 350 °C. For the first self-limiting process, a single silicon precursor, Si3H8, was dosed at a substrate temperature of 250 °C, and XPS results show the deposited silicon hydride layer saturated at about 4 monolayers of silicon coverage with hydrogen termination. STS results show the surface Fermi level remains unpinned following the deposition of the saturated silicon hydride layer, indicating the InGaAs surface dangling bonds are electrically passivated by Si-Hx. For the second self-limiting process, Si2Cl6 was dosed at a substrate temperature of 350 °C, and XPS results show the deposited silicon chloride layer saturated at about 2.5 monolayers of silicon coverage with chlorine termination. Atomic hydrogen produced by a thermal gas cracker was subsequently dosed at 350 °C to remove the Si-Cl termination by replacing with Si-H termination as confirmed by XPS, and STS results confirm the saturated Si-Hx bilayer leaves the InGaAs(001)-(2 × 4) surface Fermi level unpinned. Density function theory modeling of silicon hydride surface passivation shows an Si-Hx monolayer can remove all the dangling bonds and leave a charge balanced surface on InGaAs. PMID:26070022

  7. Characterization and control of crystal nucleation in amorphous electron beam evaporated silicon for thin film solar cells

    SciTech Connect

    Sontheimer, Tobias; Scherf, Simone; Klimm, Carola; Becker, Christiane; Rech, Bernd

    2011-09-15

    The kinetics of crystal nucleation in high-rate electron beam evaporated amorphous Si for polycrystalline thin film solar cells was systematically studied on SiN and selected ZnO:Al-coated glass substrates with dissimilar surface topographies by employing Raman spectroscopy, transmission electron microscopy, and optical microscopy. The influence of the surface topography of the substrate and the disorder of the deposited amorphous Si could be correlated to the respective characteristics of the transient and steady state regime of the nucleation rate. The steady state nucleation rate I{sub ss}, its corresponding activation energy E{sub Iss}, and consequently the size of the grains in the crystallized Si were found to be governed by the interplay between the surface roughness and the deposition temperature. The steady state nucleation rate I{sub ss} increased gradually upon increasing the substrate roughness, while lowering the deposition temperature of the amorphous Si on rough textures resulted in a decline of I{sub ss}. The time-lag {tau}, which represents a distinctive parameter for the transient regime, was only slightly affected by the substrate topography. The deposition temperature, however, had a significant influence on {tau}, with {tau} increasing by a factor of 8 upon lowering the deposition temperature from 300 to 200 deg. C for all substrate topographies. These characteristics could be correlated with the increasing structural disorder of the deposited a-Si upon decreasing the deposition temperature. Based on this analysis, we could determine design rules for the controlled preparation of large-grained poly-Si in minimized processing time on any of the used substrate types by individually adjusting the deposition temperature and implementing nucleation layers.

  8. Advancements in silicon web technology

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Easoz, J.; Mchugh, J. P.; Piotrowski, P.; Hundal, R.

    1987-01-01

    Low defect density silicon web crystals up to 7 cm wide are produced from systems whose thermal environments are designed for low stress conditions using computer techniques. During growth, the average silicon melt temperature, the lateral melt temperature distribution, and the melt level are each controlled by digital closed loop systems to maintain thermal steady state and to minimize the labor content of the process. Web solar cell efficiencies of 17.2 pct AM1 have been obtained in the laboratory while 15 pct efficiencies are common in pilot production.

  9. A Voltage Controlled Oscillator for a Phase-Locked Loop Frequency Synthesizer in a Silicon-on-Sapphire Process

    SciTech Connect

    Garrison, Sean

    2009-05-21

    Engineers from a government-owned engineering and manufacturing facility were contracted by government-owned research laboratory to design and build an S-band telemetry transmitter using Radio Frequency Integrated Circuit (RFIC) technology packaged in a Low-Temperature Co-fired Ceramic (LTCC) Multi-Chip Module. The integrated circuit technology chosen for the Phase-Locked Loop Frequency Synthesizer portion of the telemetry transmitter was a 0.25 um CMOS process that utilizes a sapphire substrate and is fabricated by Peregrine Semiconductor corporation. This thesis work details the design of the Voltage Controlled Oscillator (VCO) portion of the PLL frequency synthesizer and constitutes an fully integrated VCO core circuit and a high-isolation buffer amplifier. The high-isolation buffer amplifier was designed to provide 16 dB of gain for 2200-3495 MHz as well as 60 dB of isolation for the oscillator core to provide immunity to frequency pulling due to RF load mismatch. Actual measurements of the amplifier gain and isolation showed the gain was approximately 5 dB lower than the simulated gain when all bond-wire and test substrate parasitics were taken into account. The isolation measurements were shown to be 28 dB at the high end of the frequency band but the measurement was more than likely compromised due to the aforementioned bond-wire and test substrate parasitics. The S-band oscillator discussed in this work was designed to operate over a frequency range of 2200 to 2300 MHz with a minimum output power of 0 dBm with a phase-noise of -92 dBc/Hz at a 100 kHz offset from the carrier. The tuning range was measured to be from 2215 MHz to 2330 MHz with a minimum output power of -7 dBm over the measured frequency range. A phase-noise of -90 dBc was measured at a 100 kHz offset from the carrier.

  10. Purified silicon production system

    DOEpatents

    Wang, Tihu; Ciszek, Theodore F.

    2004-03-30

    Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.

  11. OsKAT2 is the prevailing functional inward rectifier potassium channels in rice guard cell

    PubMed Central

    Hwang, Hyunsik; Yoon, Jin-Young; Cho, Hana; Kim, Beom-Gi

    2013-01-01

    AtKAT1 plays roles as a major channel to uptake K+ in guard cell when stomata open in dicot model plant Arabidopsis. In a recent publication, we isolated 3 KAT-like potassium channels in rice. We expressed them in CHO cell to identify electrophysiological characteristics of the channels. OsKAT2 showed much bigger inwardly rectifying potassium channel activities among them. The histochemical X-glu staining of transgenic rice leaf blades expressing β-glucuronidase fused with OsKAT2 promoter showed that the OsKAT2 is dominantly expressed in rice guard cell. These findings indicate that OsKAT2 may be a functional ortholog of AtKAT1 in rice. Thus this gene will be the prime target for engineering the guard cell movement to improve drought tolerance in monocot plants, including most major crops. PMID:24103920

  12. Delayed rectifier K channels contribute to contrast adaptation in mammalian retinal ganglion cells

    PubMed Central

    Weick, Michael; Demb, Jonathan B.

    2011-01-01

    SUMMARY Retinal ganglion cells adapt by reducing their sensitivity during periods of high contrast. Contrast adaptation in the firing response depends on both presynaptic and intrinsic mechanisms. Here, we investigated intrinsic mechanisms for contrast adaptation in OFF Alpha ganglion cells in the in vitro guinea pig retina. Using either visual stimulation or current injection, we show that brief depolarization evoked spiking and suppressed firing during subsequent depolarization. The suppression could be explained by Na channel inactivation, as shown in salamander cells. However, brief hyperpolarization in the physiological range (5–10 mV) also suppressed firing during subsequent depolarization. This suppression was sensitive selectively to blockers of delayed-rectifier K channels (KDR). Somatic membrane patches showed TEA-sensitive KDR currents with activation near −25 mV and removal of inactivation at voltages negative to Vrest. Brief periods of hyperpolarization apparently remove KDR inactivation and thereby increase the channel pool available to suppress excitability during subsequent depolarization. PMID:21745646

  13. Rectifying properties of ZnO thin films deposited on FTO by electrodeposition technique

    NASA Astrophysics Data System (ADS)

    Lv, Jianguo; Sun, Yue; Zhao, Min; Cao, Li; Xu, Jiayuan; He, Gang; Zhang, Miao; Sun, Zhaoqi

    2016-03-01

    ZnO thin films were successfully grown on fluorine-doped tin oxide glass by electrodeposition technique. The crystal structure, surface morphology and optical properties of the thin films were investigated. The average crystallite size and intensity of A1(LO) mode increase with improving the absolute value of deposition potential. The best preferential orientation along c-axis and the richest oxygen interstitial defects have been observed in the sample deposited at -0.8 V. A heterojunction device consisting of ZnO thin film and n-type fluorine-doped tin oxide was fabricated. The current-voltage (I-V) characteristic of the p-n heterojunction device deposited at -0.8 V shows the best rectifying diode behavior. The p-type conductivity of the ZnO thin film could be attributed to complex defect of unintentional impurity and interstitial oxygen.

  14. Immunological identification and characterization of a delayed rectifier K+ channel polypeptide in rat brain.

    PubMed Central

    Trimmer, J S

    1991-01-01

    Antibodies specific for the drk1 polypeptide were used to characterize the corresponding protein in rat brain. Recombinant and synthetic immunogens containing fragments of the drk1 polypeptide were produced. Antibodies raised to these immunogens display monospecific reactions with the same 130-kDa polypeptide on immunoblots of adult rat brain membranes. Immunoprecipitation of 125I-labeled brain membranes identifies a 38-kDa peptide in tight association with the drk1 polypeptide. Immunohistochemical staining of sections of adult rat cortex shows that drk1 protein is restricted to neurons, where staining is present on dendrites and cell bodies but not on axons. These studies point to the value of such immunological reagents to the further characterization of the components of this delayed rectifier K+ channel in the mammalian central nervous system. Images PMID:1961744

  15. Negative differential resistance and rectifying performance induced by doped graphene nanoribbons p-n device

    NASA Astrophysics Data System (ADS)

    Zhou, Yuhong; Qiu, Nianxiang; Li, Runwei; Guo, Zhansheng; Zhang, Jian; Fang, Junfeng; Huang, Aisheng; He, Jian; Zha, Xianhu; Luo, Kan; Yin, Jingshuo; Li, Qiuwu; Bai, Xiaojing; Huang, Qing; Du, Shiyu

    2016-03-01

    Employing nonequilibrium Green's Functions in combination with density functional theory, the electronic transport properties of armchair graphene nanoribbon (GNR) devices with various widths are investigated in this work. In the adopted model, two semi-infinite graphene electrodes are periodically doped with boron or nitrogen atoms. Our calculations reveal that these devices have a striking nonlinear feature and show notable negative differential resistance (NDR). The results also indicate the diode-like properties are reserved and the rectification ratios are high. It is found the electronic transport properties are strongly dependent on the width of doped nanoribbons and the positions of dopants and three distinct families are elucidated for the current armchair GNR devices. The NDR as well as rectifying properties can be well explained by the variation of transmission spectra and the relative shift of discrete energy states with applied bias voltage. These findings suggest that the doped armchair GNR is a promising candidate for the next generation nanoscale device.

  16. Computational design of intrinsic molecular rectifiers based on asymmetric functionalization of N-phenylbenzamide

    DOE PAGESBeta

    Ding, Wendu; Koepf, Matthieu; Koenigsmann, Christopher; Batra, Arunabh; Venkataraman, Latha; Negre, Christian F. A.; Brudvig, Gary W.; Crabtree, Robert H.; Schmuttenmaer, Charles A.; Batista, Victor S.

    2015-11-03

    Here, we report a systematic computational search of molecular frameworks for intrinsic rectification of electron transport. The screening of molecular rectifiers includes 52 molecules and conformers spanning over 9 series of structural motifs. N-Phenylbenzamide is found to be a promising framework with both suitable conductance and rectification properties. A targeted screening performed on 30 additional derivatives and conformers of N-phenylbenzamide yielded enhanced rectification based on asymmetric functionalization. We demonstrate that electron-donating substituent groups that maintain an asymmetric distribution of charge in the dominant transport channel (e.g., HOMO) enhance rectification by raising the channel closer to the Fermi level. These findingsmore » are particularly valuable for the design of molecular assemblies that could ensure directionality of electron transport in a wide range of applications, from molecular electronics to catalytic reactions.« less

  17. Computational design of intrinsic molecular rectifiers based on asymmetric functionalization of N-phenylbenzamide

    SciTech Connect

    Ding, Wendu; Koepf, Matthieu; Koenigsmann, Christopher; Batra, Arunabh; Venkataraman, Latha; Negre, Christian F. A.; Brudvig, Gary W.; Crabtree, Robert H.; Schmuttenmaer, Charles A.; Batista, Victor S.

    2015-11-03

    Here, we report a systematic computational search of molecular frameworks for intrinsic rectification of electron transport. The screening of molecular rectifiers includes 52 molecules and conformers spanning over 9 series of structural motifs. N-Phenylbenzamide is found to be a promising framework with both suitable conductance and rectification properties. A targeted screening performed on 30 additional derivatives and conformers of N-phenylbenzamide yielded enhanced rectification based on asymmetric functionalization. We demonstrate that electron-donating substituent groups that maintain an asymmetric distribution of charge in the dominant transport channel (e.g., HOMO) enhance rectification by raising the channel closer to the Fermi level. These findings are particularly valuable for the design of molecular assemblies that could ensure directionality of electron transport in a wide range of applications, from molecular electronics to catalytic reactions.

  18. CFTR regulates outwardly rectifying chloride channels through an autocrine mechanism involving ATP.

    PubMed

    Schwiebert, E M; Egan, M E; Hwang, T H; Fulmer, S B; Allen, S S; Cutting, G R; Guggino, W B

    1995-06-30

    The cystic fibrosis transmembrane conductance regulator (CFTR) functions to regulate both Cl- and Na+ conductive pathways; however, the cellular mechanisms whereby CFTR acts as a conductance regulator are unknown. CFTR and outwardly rectifying Cl- channels (ORCCs) are distinct channels but are linked functionally via an unknown regulatory mechanism. We present results from whole-cell and single-channel patch-clamp recordings, short-circuit current recordings, and [gamma-32P]ATP release assays of normal, CF, and wild-type or mutant CFTR-transfected CF airway cultured epithelial cells wherein CFTR regulates ORCCs by triggering the transport of the potent agonist, ATP, out of the cell. Once released, ATP stimulates ORCCs through a P2U purinergic receptor-dependent signaling mechanism. Our results suggest that CFTR functions to regulate other Cl- secretory pathways in addition to itself conducting Cl-. PMID:7541313

  19. Crowdsourcing Aquatic Resource Data Collection: Exploring Effective Methods to Collect and Rectify Citizen Contributed Data

    NASA Astrophysics Data System (ADS)

    Soderberg, J.

    2011-12-01

    Increasing use of mobile computing and geopositioning technology has provided the environmental sciences with vast new pools of data. Prominent among the gathering methods which produce this data is "crowdsourcing", in which citizen scientists volunteer data. Environmental data collected by crowdsourcing may need to be rectified prior to use by the scientific community. Using mobile applications to educate the crowd, support for the targeted environmental data desired, coupled with thoughtful design of mobile applications can potentially aid the process of rectification. This presentation will outline the use of crowdsourced data, cohort groups and design options for mobile applications that can be used to collect aquatic resource information. If rectification challenges can be overcome, the collective power of the crowd can be harnessed to gather standards-based geographic data, information about environmental conditions, and detailed biological data about aquatic resources. Key Words: Crowdsource, Citizen Scientist, Volunteer Data, Geopositioning Aquatic Resource Geographic Data Author Jon Eric Soderberg

  20. Pacemaker Created in Human Ventricle by Depressing Inward-Rectifier K+ Current: A Simulation Study

    PubMed Central

    Zhang, Yue; Li, Qince; Zhang, Henggui

    2016-01-01

    Cardiac conduction disorders are common diseases which cause slow heart rate and syncope. The best way to treat these diseases by now is to implant electronic pacemakers, which, yet, have many disadvantages, such as the limited battery life and infection. Biopacemaker has been expected to replace the electronic devices. Automatic ventricular myocytes (VMs) could show pacemaker activity, which was induced by depressing inward-rectifier K+ current (IK1). In this study, a 2D model of human biopacemaker was created from the ventricular endocardial myocytes. We examined the stability of the created biopacemaker and investigated its driving capability by finding the suitable size and spatial distribution of the pacemaker for robust pacing and driving the surrounding quiescent cardiomyocytes. Our results suggest that the rhythm of the pacemaker is similar to that of the single cell at final stable state. The driving force of the biopacemaker is closely related to the pattern of spatial distribution of the pacemaker. PMID:26998484