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Sample records for bipolar junction transistor

  1. Ion bipolar junction transistors.

    PubMed

    Tybrandt, Klas; Larsson, Karin C; Richter-Dahlfors, Agneta; Berggren, Magnus

    2010-06-01

    Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated. PMID:20479274

  2. Ion bipolar junction transistors

    PubMed Central

    Tybrandt, Klas; Larsson, Karin C.; Richter-Dahlfors, Agneta; Berggren, Magnus

    2010-01-01

    Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated. PMID:20479274

  3. Magnetoamplification in a Bipolar Magnetic Junction Transistor

    NASA Astrophysics Data System (ADS)

    Rangaraju, N.; Peters, J. A.; Wessels, B. W.

    2010-09-01

    We have demonstrated the first bipolar magnetic junction transistor using a dilute magnetic semiconductor. For an InMnAs p-n-p transistor magnetoamplification is observed at room temperature. The observed magnetoamplification is attributed to the magnetoresistance of the magnetic semiconductor InMnAs heterojunction. The magnetic field dependence of the transistor characteristics confirm that the magnetoamplification results from the junction magnetoresistance. To describe the experimentally observed transistor characteristics, we propose a modified Ebers-Moll model that includes a series magnetoresistance attributed to spin-selective conduction. The capability of magnetic field control of the amplification in an all-semiconductor transistor at room temperature potentially enables the creation of new computer logic architecture where the spin of the carriers is utilized.

  4. Polyphosphonium-based ion bipolar junction transistors

    PubMed Central

    Gabrielsson, Erik O.; Berggren, Magnus

    2014-01-01

    Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e., ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2 μm, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example, addressable drug-delivery devices. PMID:25553192

  5. Free electron gas primary thermometer: The bipolar junction transistor

    SciTech Connect

    Mimila-Arroyo, J.

    2013-11-04

    The temperature of a bipolar transistor is extracted probing its carrier energy distribution through its collector current, obtained under appropriate polarization conditions, following a rigorous mathematical method. The obtained temperature is independent of the transistor physical properties as current gain, structure (Homo-junction or hetero-junction), and geometrical parameters, resulting to be a primary thermometer. This proposition has been tested using off the shelf silicon transistors at thermal equilibrium with water at its triple point, the transistor temperature values obtained involve an uncertainty of a few milli-Kelvin. This proposition has been successfully tested in the temperature range of 77–450 K.

  6. A gallium phosphide high-temperature bipolar junction transistor

    NASA Technical Reports Server (NTRS)

    Zipperian, T. E.; Dawson, L. R.; Chaffin, R. J.

    1981-01-01

    Preliminary results are reported on the development of a high temperature (350 C) gallium phosphide bipolar junction transistor (BJT) for geothermal and other energy applications. This four-layer p(+)n(-)pp(+) structure was formed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into the lightly doped base. By appropriate choice of electrodes, the device may also be driven as an n-channel junction field-effect transistor. The initial design suffers from a series resistance problem which limits the transistor's usefulness at high temperatures.

  7. Bipolar junction transistor models for circuit simulation of cosmic-ray-induced soft errors

    NASA Astrophysics Data System (ADS)

    Benumof, R.; Zoutendyk, J.

    1984-11-01

    This paper examines bipolar junction transistor models suitable for calculating the effects of large excursions of some of the variables determining the operation of a transistor. Both the Ebers-Moll and Gummel-Poon models are studied, and the junction and diffusion capacitances are evaluated on the basis of the latter model. The most interesting result of this analysis is that a bipolar junction transistor when struck by a cosmic particle may cause a single event upset in an electronic circuit if the transistor is operated at a low forward base-emitter bias.

  8. Bipolar junction transistor models for circuit simulation of cosmic-ray-induced soft errors

    NASA Technical Reports Server (NTRS)

    Benumof, R.; Zoutendyk, J.

    1984-01-01

    This paper examines bipolar junction transistor models suitable for calculating the effects of large excursions of some of the variables determining the operation of a transistor. Both the Ebers-Moll and Gummel-Poon models are studied, and the junction and diffusion capacitances are evaluated on the basis of the latter model. The most interesting result of this analysis is that a bipolar junction transistor when struck by a cosmic particle may cause a single event upset in an electronic circuit if the transistor is operated at a low forward base-emitter bias.

  9. On noise sources in hot electron-degraded bipolar junction transistors

    NASA Astrophysics Data System (ADS)

    Llinares, P.; Ghibaudo, G.; Chroboczek, J. A.

    1997-09-01

    The effects of electrical stress on static characteristics and power spectral density, SIb, of base current, Ib, fluctuations at low frequencies, f<1 kHz, have been studied in quasiself-aligned bipolar n-p-n junction. In as-fabricated devices SIb∝1/AE, where AE is the transistor emitter area, whereas in strongly degraded transistors Sib∝1/PE, where PE is the transistor perimeter. The latter demonstrates directly that hot carrier-induced noise sources are generated at the periphery of the transistors, in agreement with former work on hot electron-induced aging of bipolar junction transistors.

  10. Theoretical values of various parameters in the Gummel-Poon model of a bipolar junction transistor

    NASA Technical Reports Server (NTRS)

    Benumof, R.; Zoutendyk, J.

    1986-01-01

    Various parameters in the Gummel-Poon model of a bipolar junction transistor are expressed in terms of the basic structure of a transistor. A consistent theoretical approach is used which facilitates an understanding of the foundations and limitations of the derived formulas. The results enable one to predict how changes in the geometry and composition of a transistor would affect performance.

  11. Sensitivities of bipolar junction transistor electrical parameters to processing variables

    NASA Astrophysics Data System (ADS)

    Abdulkarim, H. S.

    1980-03-01

    Variations and sensitivities of bipolar junction transistor (BJT) electrical parameters to processing variables were examined. The functional dependence of these sensitivities on the processing schedule employed was estimated. Some design criteria or guidelines that should be followed to reduce the sensitivities of electrical parameters and to minimize yield loss were determined. The BJT parameters considered were electrical parameters of the Ebers-Moll and hybrid-pi models, as well as some device parameters that were useful for the characterization of processing results. The processing variables considered were time and temperature for each of the processing steps of the double diffusion method, physical constants that influence the impurity distribution in silicon, and device dimensions. In evaluating the impurity atom distribution, the diffusion coefficient was assumed to be independent of impurity concentration and the superposition model was assumed for the interaction of the two oppositely charged impurities. In evaluating the electrical parameters, use of a one dimensional model and the modified Moll-Ross relations were assumed to be adequate in relating variations in electrical characteristics to variations in processing variables and physical properties.

  12. Using Animation to Improve the Students' Academic Achievement on Bipolar Junction Transistor

    ERIC Educational Resources Information Center

    Zoabi, W.; Sabag, N.; Gero, A.

    2012-01-01

    Teaching abstract subjects to students studying towards a degree in electronics practical engineering (a degree between a technician and an engineer) requires didactic tools that enable understanding of issues without using advanced mathematics and physics. One basic issue is the BJT (Bipolar Junction Transistor) that requires preliminary…

  13. Junction-to-Case Thermal Resistance of a Silicon Carbide Bipolar Junction Transistor Measured

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    2006-01-01

    Junction temperature of a prototype SiC-based bipolar junction transistor (BJT) was estimated by using the base-emitter voltage (V(sub BE)) characteristic for thermometry. The V(sub BE) was measured as a function of the base current (I(sub B)) at selected temperatures (T), all at a fixed collector current (I(sub C)) and under very low duty cycle pulse conditions. Under such conditions, the average temperature of the chip was taken to be the same as that of the temperature-controlled case. At increased duty cycle such as to substantially heat the chip, but same I(sub C) pulse height, the chip temperature was identified by matching the V(sub BE) to the thermometry curves. From the measured average power, the chip-to-case thermal resistance could be estimated, giving a reasonable value. A tentative explanation for an observed bunching with increasing temperature of the calibration curves may relate to an increasing dopant atom ionization. A first-cut analysis, however, does not support this.

  14. Bipolar Junction Transistors in Two-Dimensional WSe2 with Large Current and Photocurrent Gains.

    PubMed

    Agnihotri, Pratik; Dhakras, Prathamesh; Lee, Ji Ung

    2016-07-13

    In the development of semiconductor devices, the bipolar junction transistor (BJT) features prominently as being the first solid state transistor that helped to usher in the digital revolution. For any new semiconductor, therefore, the fabrication and characterization of the BJT are important for both technological importance and historical significance. Here, we demonstrate a BJT device in exfoliated TMD semiconductor WSe2. We use buried gates to electrostatically create doped regions with back-to-back p-n junctions. We demonstrate two central characteristics of a bipolar device: current gain when operated as a BJT and a photocurrent gain when operated as a phototransistor. We demonstrate a current gain of 1000 and photocurrent gain of 40 and describe features that enhance these properties due to the doping technique that we employ. PMID:27336742

  15. An improved bipolar junction transistor model for electrical and radiation effects

    SciTech Connect

    Kleiner, C.T.; Messenger, G.C.

    1982-12-01

    The use of bipolar technology in hardened electronic design requires an in-depth understanding of how the Bipolar Junction Transistor (BJT) behaves under normal electrical and radiation environments. Significant improvements in BJT process technology have been reported, and the successful use of sophisticated Computer Aided Design (CAD) tools has aided implementation with respect to specific families of hardened devices. The most advanced BJT model used to date is the Improved Gummel-Poon (IGP) model which is used in CAA programs such as the SPICE II and SLICE programs. The earlier Ebers-Moll model (ref 1 and 2) has also been updated to compare with the older Gummel-Poon model. This paper describes an adaptation of an existing computer model which incorporates the best features of both models into a new, more accurate model called the Improved Bipolar Junction Transistor model. This paper also describes a unique approach to data reduction for the B(I /SUB c/) and V /SUB BE/(ACT) vs I /SUB c/characterizations which has been successfully programmed in Basic using a Commodore PET computer. This model is described in the following sections.

  16. Large-scale transient sensitivity analysis of a radiation damaged bipolar junction transistor.

    SciTech Connect

    Hoekstra, Robert John; Gay, David M.; Bartlett, Roscoe Ainsworth; Phipps, Eric Todd

    2007-11-01

    Automatic differentiation (AD) is useful in transient sensitivity analysis of a computational simulation of a bipolar junction transistor subject to radiation damage. We used forward-mode AD, implemented in a new Trilinos package called Sacado, to compute analytic derivatives for implicit time integration and forward sensitivity analysis. Sacado addresses element-based simulation codes written in C++ and works well with forward sensitivity analysis as implemented in the Trilinos time-integration package Rythmos. The forward sensitivity calculation is significantly more efficient and robust than finite differencing.

  17. Urea biosensor based on an extended-base bipolar junction transistor.

    PubMed

    Sun, Tai-Ping; Shieh, Hsiu-Li; Liu, Chun-Lin; Chen, Chung-Yuan

    2014-01-01

    In this study, a urea biosensor was prepared by the immobilization of urease onto the sensitive membrane of an extended-base bipolar junction transistor. The pH variation was used to detect the concentration of urea. The SnO2/ITO glass, fabricated by sputtering SnO2 on the conductive ITO glass, was used as a pH-sensitive membrane, which was connected with a commercial bipolar junction transistor device. The gels, fabricated by the poly vinyl alcohol with pendent styrylpyridinium groups, were used to immobilize the urease. This readout circuit, fabricated in a 0.35-um CMOS 2P4M process, operated at 3.3V supply voltage. This circuit occupied an area of 1.0 mm × 0.9 mm. The dynamic range of the urea biosensor was from 1.4 to 64 mg/dl at the 10 mM phosphate buffer solution and the sensitivity of this range was about 65.8 mV/pUrea. The effect of urea biosensors with different pH values was considered, and the characteristics of urea biosensors based on EBBJT were described. PMID:24211878

  18. Implementation of total dose effects in the bipolar junction transistor Gummel-Poon model

    SciTech Connect

    Montagner, X.; Fouillat, P.; Briand, R.; Touboul, A.; Schrimpf, R.D.; Galloway, K.F.; Calvet, M.C.; Calvel, P.

    1997-12-01

    The effects of total dose on the SPICE model of bipolar junction transistors are investigated. The limitations of the standard Gummel-Poon model for simulating the radiation-induced excess base current are analyzed, and a new model based on an empirical approach is proposed. Four new SPICE rad-parameters are presented, and investigated for different dose rates. The relevant parameters are extracted using a new algorithmic procedure, combining a genetic approach and the standard optimization technique which minimizes the RMS error between measured and simulated excess base current. It is shown that the excess base current is accurately described by the same formula whatever the device type is. An empirical fitting of the rad-parameters as a function of total dose is proposed to use in hardening electronic circuits for space-like environments.

  19. Simulation of neutron displacement damage in bipolar junction transistors using high-energy heavy ion beams.

    SciTech Connect

    Doyle, Barney Lee; Buller, Daniel L.; Hjalmarson, Harold Paul; Fleming, Robert M; Bielejec, Edward Salvador; Vizkelethy, Gyorgy

    2006-12-01

    Electronic components such as bipolar junction transistors (BJTs) are damaged when they are exposed to radiation and, as a result, their performance can significantly degrade. In certain environments the radiation consists of short, high flux pulses of neutrons. Electronics components have traditionally been tested against short neutron pulses in pulsed nuclear reactors. These reactors are becoming less and less available; many of them were shut down permanently in the past few years. Therefore, new methods using radiation sources other than pulsed nuclear reactors needed to be developed. Neutrons affect semiconductors such as Si by causing atomic displacements of Si atoms. The recoiled Si atom creates a collision cascade which leads to displacements in Si. Since heavy ions create similar cascades in Si we can use them to create similar damage to what neutrons create. This LDRD successfully developed a new technique using easily available particle accelerators to provide an alternative to pulsed nuclear reactors to study the displacement damage and subsequent transient annealing that occurs in various transistor devices and potentially qualify them against radiation effects caused by pulsed neutrons.

  20. Design and simulation of oxide and doping engineered lateral bipolar junction transistors for high power applications

    NASA Astrophysics Data System (ADS)

    Loan, Sajad A.; Bashir, Faisal; Akhoon, M. Saqib; Alamoud, Abdulrahman M.

    2016-01-01

    In this paper, we propose new structures of lateral bipolar junction transistor (LBJT) on silicon on insulator (SOI) with improved performance. The proposed devices are lateral bipolar transistors with multi doping zone collector drift region and a thick buried oxide under the collector region. Calibrated simulation studies have revealed that the proposed devices have higher breakdown voltage than the conventional device, that too at higher drift doping concentration. This has resulted in improved tradeoff between the on-resistance and the breakdown voltage of the proposed devices. It has been observed that the proposed device with two collector drift doping zones and a buried oxide thick step results in ∼190% increase in the breakdown voltage than the conventional device. The further increase in the number of collector drift doping zones from two to three has increased the breakdown voltage by 260% than the conventional one. On comparing the proposed devices with the buried oxide double step devices, it has been found that an increase of ∼15-19% in the breakdown voltage is observed in the proposed devices even at higher drift doping concentrations. The use of higher drift doping concentration reduces the on-resistance of the proposed device and thus improves the tradeoff between the breakdown voltage and the on-resistance of the proposed device in comparison to buried oxide double step devices. Further, the use of step doping in the collector drift region has resulted in the reduction of kink effect in the proposed device. Using the mixed mode simulations, the proposed devices have been tested at the circuit level, by designing and simulating inverting amplifiers employing the proposed devices. Both DC and AC analyses of the inverting amplifiers have shown that the proposed devices work well at the circuit level. It has been observed that there is a slight increase in ON delay in the proposed device; however, the OFF delay is more or less same as that of the

  1. An improved bipolar junction transistor model for electrical and radiation effects

    NASA Astrophysics Data System (ADS)

    Kleiner, C. T.; Messenger, G. C.

    1982-12-01

    A bipolar transistor model is introduced which combines most of the best features of the modified Ebers-Moll (1954) model with the Gummel-Poon (1970) model. The model is constructed of two modified Ebers-Moll models with the addition of junction and basewidth modulation to account for leakage current dependence on reverse voltage and beta dependence on collector-emitter voltage. The electrical characteristics that can be obtained with the model include: nonlinear beta and V(BE) vs normal I(C) and/or inverted I(E); increase in f(T) from low injection to peak beta and decrease in f(T) beyond peak beta; nonlinear R(CX) vs I(C) and V(CE); inclusion of base-width modulation as a function of reverse bias for V(CB) or V(EB); and inclusion of junction leakage as a function of reverse bias. Radiation characteristics that can be obtained include: photocurrent generation and saturation including photocurrent response time; dose-rate modulation of resistors; inclusion of neutron damage constant as a function of injection level and incorporation of fast annealing; inclusion of temperature dependence.

  2. Radiation-induced 1/f noise degradation of PNP bipolar junction transistors at different dose rates

    NASA Astrophysics Data System (ADS)

    Qi-Feng, Zhao; Yi-Qi, Zhuang; Jun-Lin, Bao; Wei, Hu

    2016-04-01

    It is found that ionizing-radiation can lead to the base current and the 1/f noise degradations in PNP bipolar junction transistors. In this paper, it is suggested that the surface of the space charge region of the emitter-base junction is the main source of the base surface 1/f noise. A model is developed which identifies the parameters and describes their interactive contributions to the recombination current at the surface of the space charge region. Based on the theory of carrier number fluctuation and the model of surface recombination current, a 1/f noise model is developed. This model suggests that 1/f noise degradations are the result of the accumulation of oxide-trapped charges and interface states. Combining models of ELDRS, this model can explain the reason why the 1/f noise degradation is more severe at a low dose rate than at a high dose rate. The radiations were performed in a Co60 source up to a total dose of 700 Gy(Si). The low dose rate was 0.001 Gy(Si)/s and the high dose rate was 0.1 Gy(Si)/s. The model accords well with the experimental results. Project supported by the National Natural Science Foundation of China (Grant Nos. 61076101 and 61204092).

  3. Analysis of generation and annihilation of deep level defects in a silicon-irradiated bipolar junction transistor

    NASA Astrophysics Data System (ADS)

    Madhu, K. V.; Kulkarni, S. R.; Ravindra, M.; Damle, R.

    2007-08-01

    A commercial bipolar junction transistor (2 N 2219 A, npn), irradiated with 120 MeV Si9+ ions with a fluence of the order of 1012 ions cm-2, is studied for radiation-induced gain degradation and deep level defects. I-V measurements are made to study the gain degradation as a function of ion fluence. Properties such as activation energy, trap concentration and capture cross section of deep levels are studied by deep level transient spectroscopy (DLTS). Minority carrier trap energy levels with energies ranging from EC - 0.160 eV to EC - 0.581 eV are observed in the base-collector junction of the transistor. Majority carrier trap levels are also observed with energies ranging from EV + 0.182 eV to EV + 0.401 eV. The identification of the defect type is made on the basis of its finger prints such as activation energy, annealing temperature and capture cross section by comparing with those reported in the literature. New energy levels for the defects A-center, di-vacancy and Si-interstitial are also observed. The irradiated transistor is subjected to isothermal and isochronal annealing. The defects are seen to anneal above 250 °C. The defects generated in the base region of the transistor by displacement damage appear to be responsible for transistor gain degradation.

  4. Effect of thin emitter set-back layer on GaAs delta-doped emitter bipolar junction transistor

    NASA Astrophysics Data System (ADS)

    Lew, K. L.; Yoon, S. F.

    2005-05-01

    GaAs delta-doped emitter bipolar junction transistors (δ-BJT) with different emitter set-back layer thicknesses of 10to50nm were fabricated to study the emitter set-back layer thickness effect on device dc performance. We found that the current gain decreases following decrease in the emitter set-back layer thickness. A detailed analysis was performed to explain this phenomenon, which is believed to be caused by reduction of the effective barrier height in the δ-BJT. This is due to change in the electric-field distribution in the delta-doped structure caused by the built-in potential of the base-emitter (B-E ) junction. Considering the recombination and barrier height reduction effects, the thickness of the emitter set-back layer should be designed according to the B-E junction depletion width with a tolerance of ±5nm. The dc performance of a δ-BJT designed based on this criteria is compared to that of a Al0.25Ga0.75As /GaAs heterojunction bipolar transistor (HBT). Both devices employed base doping of 2×1019cm-3 and base-to-emitter doping ratio of 40. Large emitter area (AE≈1.6×10-5cm-2) and small emitter area (AE≈1.35×10-6cm-2) device current gains of 40 and 20, respectively, were obtained in both types of transistors passivated by (NH4)2S treatment. The measured current gain of the GaAs δ-BJT is the highest reported for a homojunction device with such high base-to-emitter doping ratio normally used in HBT devices.

  5. Evaluation of Enhanced Low Dose Rate Sensitivity in Discrete Bipolar Junction Transistors

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; Ladbury Raymond; LaBel, Kenneth; Topper, Alyson; Ladbury, Raymond; Triggs, Brian; Kazmakites, Tony

    2012-01-01

    We evaluate the low dose rate sensitivity in several families of discrete bipolar transistors across device parameter, quality assurance level, and irradiation bias configuration. The 2N2222 showed the most significant low dose rate sensitivity, with low dose rate enhancement factor of 3.91 after 100 krad(Si). The 2N2907 also showed critical degradation levels. The devices irradiated at 10 mrad(Si)/s exceeded specifications after 40 and 50 krad(Si) for the 2N2222 and 2N2907 devices, respectively.

  6. Low Gate Voltage Operated Multi-emitter-dot H+ Ion-Sensitive Gated Lateral Bipolar Junction Transistor

    NASA Astrophysics Data System (ADS)

    Yuan, Heng; Zhang, Ji-Xing; Zhang, Chen; Zhang, Ning; Xu, Li-Xia; Ding, Ming; Patrick, J. Clarke

    2015-02-01

    A low gate voltage operated multi-emitter-dot gated lateral bipolar junction transistor (BJT) ion sensor is proposed. The proposed device is composed of an arrayed gated lateral BJT, which is driven in the metal-oxide-semiconductor field-effect transistor (MOSFET)-BJT hybrid operation mode. Further, it has multiple emitter dots linked to each other in parallel to improve ionic sensitivity. Using hydrogen ionic solutions as reference solutions, we conduct experiments in which we compare the sensitivity and threshold voltage of the multi-emitter-dot gated lateral BJT with that of the single-emitter-dot gated lateral BJT. The multi-emitter-dot gated lateral BJT not only shows increased sensitivity but, more importantly, the proposed device can be operated under very low gate voltage, whereas the conventional ion-sensitive field-effect transistors cannot. This special characteristic is significant for low power devices and for function devices in which the provision of a gate voltage is difficult.

  7. Limit of validity of the thermionic-field-emission treatment of electron injection across emitter-base junctions in abrupt heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Kumar, T.; Cahay, M.; Shi, S.; Roenker, K.; Stanchina, W. E.

    1995-06-01

    A hybrid model is developed to simulate electron transport through the emitter-base heterojunction and the base region of abrupt heterojunction bipolar transistors. The energy distribution of the injected electron flux through the emitter-base junction is calculated using a rigorous quantum-mechanical treatment of electron tunneling and thermionic emission across the spike at the emitter-base junction. The results are compared with those predicted by the conventional thermionic-field-emission model. For both models, the electron fluxes injected across the emitter-base junction are used as initial energy distributions in a regional Monte Carlo calculation to model electron transport through the base. The average base transit times are calculated using the impulse response technique as a function of the emitter-base voltage. The differences between the thermionic-field-emission model and the rigorous quantum-mechanical approaches to model electron transport through abrupt heterojunction bipolar transistors are pointed out.

  8. MOSFET-BJT hybrid mode of the gated lateral bipolar junction transistor for C-reactive protein detection.

    PubMed

    Yuan, Heng; Kwon, Hyurk-Choon; Yeom, Se-Hyuk; Kwon, Dae-Hyuk; Kang, Shin-Won

    2011-10-15

    In this study, we propose a novel biosensor based on a gated lateral bipolar junction transistor (BJT) for biomaterial detection. The gated lateral BJT can function as both a BJT and a metal-oxide-semiconductor field-effect transistor (MOSFET) with both the emitter and source, and the collector and drain, coupled. C-reactive protein (CRP), which is an important disease marker in clinical examinations, can be detected using the proposed device. In the MOSFET-BJT hybrid mode, the sensitivity, selectivity, and reproducibility of the gated lateral BJT for biosensors were evaluated in this study. According to the results, in the MOSFET-BJT hybrid mode, the gated lateral BJT shows good selectivity and reproducibility. Changes in the emitter (source) current of the device for CRP antigen detection were approximately 0.65, 0.72, and 0.80 μA/decade at base currents of -50, -30, and -10 μA, respectively. The proposed device has significant application in the detection of certain biomaterials that require a dilution process using a common biosensor, such as a MOSFET-based biosensor. PMID:21835604

  9. Non-ideal effect in 4H-SiC bipolar junction transistor with double Gaussian-doped base

    NASA Astrophysics Data System (ADS)

    Yuan, Lei; Zhang, Yu-Ming; Song, Qing-Wen; Tang, Xiao-Yan; Zhang, Yi-Men

    2015-06-01

    The non-ideal effect of 4H-SiC bipolar junction transistor (BJT) with a double Gaussian-doped base is characterized and simulated in this paper. By adding a specific interface model between SiC and SiO2, the simulation results are in good agreement with the experiment data. An obvious early effect is found from the output characteristic. As the temperature rises, the early voltage increases, while the current gain gradually decreases, which is totally different from the scenario of silicon BJT. With the same effective Gummel number in the base region, the double Gaussian-doped base structure can realize higher current gain than the single base BJT due to the built-in electric field, whereas the early effect will be more salient. Besides, the emitter current crowding effect is also analyzed. Due to the low sheet resistance in the first highly-doped base epilayer, the 4H-BJT with a double base has more uniform emitter current density across the base-emitter junction, leading to better thermal stability. Project supported by the National Natural Science Foundation of China (Grant Nos. 60876061 and 61234006), the Natural Science Foundation of Shaanxi Province, China (Grant No. 2013JQ8012), and the Doctoral Fund of the Ministry of Education of China (Grant Nos. 20130203120017 and 20110203110010).

  10. A novel 4H-SiC lateral bipolar junction transistor structure with high voltage and high current gain

    NASA Astrophysics Data System (ADS)

    Deng, Yong-Hui; Xie, Gang; Wang, Tao; Sheng, Kuang

    2013-09-01

    In this paper, a novel structure of a 4H-SiC lateral bipolar junction transistor (LBJT) with a base field plate and double RESURF in the drift region is presented. Collector-base junction depletion extension in the base region is restricted by the base field plate. Thin base as well as low base doping of the LBJT therefore can be achieved under the condition of avalanche breakdown. Simulation results show that thin base of 0.32 μm and base doping of 3 × 1017 cm-3 are obtained, and corresponding current gain is as high as 247 with avalanche breakdown voltage of 3309 V when the drift region length is 30 μm. Besides, an investigation of a 4H-SiC vertical BJT (VBJT) with comparable breakdown voltage (3357 V) shows that the minimum base width of 0.25 μm and base doping as high as 8 × 1017 cm-3 contribute to a maximum current gain of only 128.

  11. Switching Characteristics of a 4H-SiC Based Bipolar Junction Transistor to 200 C

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    2006-01-01

    Static curves and resistive load switching characteristics of a 600 V, 4 A rated, SiC-based NPN bipolar power transistor (BJT) were observed at selected temperatures from room to 200 C. All testing was done in a pulse mode at low duty cycle (approx.0.1 percent). Turn-on was driven by an adjustable base current pulse and turn-off was accelerated by a negative base voltage pulse of 7 V. These base drive signals were implemented by 850 V, gated power pulsers, having rise-times of roughly 10 ns, or less. Base charge sweep-out with a 7 V negative pulse did not produce the large reverse base current pulse seen in a comparably rated Si-based BJT. This may be due to a very low charge storage time. The decay of the collector current was more linear than its exponential-like rise. Switching observations were done at base drive currents (I(sub B)) up to 400 mA and collector currents (I(sub C)) up to 4 A, using a 100 Omega non-inductive load. At I(sub B) = 400 mA and I(sub C) = 4 A, turn-on times typically varied from 80 to 94 ns, over temperatures from 23 to 200 C. As expected, lowering the base drive greatly extended the turn-on time. Similarly, decreasing the load current to I(sub C) = 1 A with I(sub B) = 400 mA produced turn-on times as short as 34 ns. Over the 23 to 200 C range, with I(sub B) = 400 mA and I(sub C) = 4 A, turn-off times were in the range of 72 to 84 ns with the 7 V sweep-out.

  12. An Ebers-Moll model for the heterostructure bipolar transistor

    NASA Astrophysics Data System (ADS)

    Lundstrom, M. S.

    1986-11-01

    An Ebers-Moll model for the heterostructure bipolar transistor (HBT) is developed. The model describes both single and double heterojunction transistors with or without band spikes and applies to uniform or graded base HBTs. Model parameters are directly related to device parameters such as doping densities, dimensions and band spikes. Junction velocities are introduced to describe the transport of carriers across the junctions. Results demonstrate that even for compositionally graded junctions, transport across the junctions may limit HBT performance if the base is graded. Use of the model is illustrated by examining a recently proposed technique for extracting conduction band spikes by comparing forward and inverted I- V characteristics.

  13. Noise modeling of microwave heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Escotte, Laurent; Roux, Jean-Phillippe; Plana, Robert; Graffeuil, Jacques; Gruhle, Andreas

    1995-05-01

    Analytical expressions of microwave heterojunction bipolar transistors minimum noise figure and noise parameter are reported in this paper. These expressions are derived from a noise model including nonideal junctions, emitter and base resistances and have been compared with measured data obtained on a Si/SiGe HBT. An agreement between theoretical and experimental data was observed up to 20 GHz for several bias conditions. The limits of the model or the range of validity of the proposed equations have been also examined with the help of an appropriate CAD software. The analysis of the influence of parasitic elements on noise parameters has shown a strong influence of the extrinsic base collector capacitance at microwave frequencies.

  14. Complementary junction heterostructure field-effect transistor

    DOEpatents

    Baca, Albert G.; Drummond, Timothy J.; Robertson, Perry J.; Zipperian, Thomas E.

    1995-01-01

    A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits.

  15. Complementary junction heterostructure field-effect transistor

    DOEpatents

    Baca, A.G.; Drummond, T.J.; Robertson, P.J.; Zipperian, T.E.

    1995-12-26

    A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits. 10 figs.

  16. Total Dose Effects in Conventional Bipolar Transistors

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.; Swift, G. W.; Rax, B. G.

    1994-01-01

    This paper examines various factors in bipolar device construction and design, and discusses their impact on radiation hardness. The intent of the paper is to improve understanding of the underlying mechanisms for practical devices without special test structures, and to provide (1) guidance in ways to select transistor designs that are more resistant to radiation damage, and (2) methods to estimate the maximum amount of damage that might be expected from a basic transistor design. The latter factor is extremely important in assessing the risk that future lots of devices will be substantially below design limits, which are usually based on test data for older devices.

  17. Generalization of Moll Ross relations for heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Mohammad, S. Noor

    2002-04-01

    Moll-Ross relations for the current flow through the base region of a bipolar transistor, and for the base transit time, have been generalized for heterojunction bipolar transistors with a nonuniform energy bandgap in the base region. The effect of both heavy doping and carrier degeneracy has been taken into account.

  18. The Ebers-Moll model for magnetic bipolar transistors

    NASA Astrophysics Data System (ADS)

    Fabian, Jaroslav; Žutić, Igor

    2005-03-01

    The equivalent electrical circuit of the Ebers-Moll-type is introduced for magnetic bipolar transistors. In addition to conventional diodes and current sources, the new circuit comprises two novel elements due to spin-charge coupling. A classification scheme of the operating modes of magnetic bipolar transistors in the low bias regime is presented.

  19. Thermal design studies of high-power heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Gao, Guang-Bo; Wang, Ming-Zhu; Gui, Xiang; Morkoc, Hadis

    1989-05-01

    A theoretical thermoelectro-feedback model has been developed for the thermal design of high-power GaAlAs/GaAs heterojunction bipolar transistors (HBTs). The power-handling capability, thermal instability, junction temperature, and current distributions of HBTs with multiple emitter fingers have been numerically studied. The calculated results indicate that power HBTs on Si substrates (or with Si as the collector) have excellent potential power performance and reliability. The power-handling capability on Si is 3.5 and 2.7 times as large as that on GaAs and InP substrates, respectively. The peak junction temperature and temperature difference on the chip decrease in comparison to the commonly used Si homostructure power transistors with the same geometry and power dissipation. Thereby HBTs are promising for high-speed microwave and millimeter-wave applications. It has been also found that the nonuniform distribution of junction temperature and current can be greatly improved by a balasting technique that uses unequal-value emitter resistors.

  20. Dose Rate Effects in Linear Bipolar Transistors

    NASA Technical Reports Server (NTRS)

    Johnston, Allan; Swimm, Randall; Harris, R. D.; Thorbourn, Dennis

    2011-01-01

    Dose rate effects are examined in linear bipolar transistors at high and low dose rates. At high dose rates, approximately 50% of the damage anneals at room temperature, even though these devices exhibit enhanced damage at low dose rate. The unexpected recovery of a significant fraction of the damage after tests at high dose rate requires changes in existing test standards. Tests at low temperature with a one-second radiation pulse width show that damage continues to increase for more than 3000 seconds afterward, consistent with predictions of the CTRW model for oxides with a thickness of 700 nm.

  1. Perpendicular transport in superlattice bipolar transistors (SBT)

    NASA Astrophysics Data System (ADS)

    Sibille, A.; Palmier, J. F.; Minot, C.; Harmand, J. C.; Dubon-Chevallier, C.

    Diffusion-limited electron transport in superlattices is studied by gain measurements on heterojunction bipolar transistors with a {GaAs}/{GaAlAs} superlattice base. In the case of thin barriers, Bloch conduction is observed, while hopping between localized levels prevails for large barriers. A transition occurs between these two regimes, localization being achieved when the energy broadening induced by the electron-phonon coupling added to the disorder due to imperfect growth is of the order of the miniband width. This interpretation is supported by temperature dependence measurements of the perpendicular mobilities in relation with theoretical calculations of these mobilities.

  2. Hardening measures for bipolar transistors against microwave-induced damage

    NASA Astrophysics Data System (ADS)

    Chai, Chang-Chun; Ma, Zhen-Yang; Ren, Xing-Rong; Yang, Yin-Tang; Zhao, Ying-Bo; Yu, Xin-Hai

    2013-06-01

    In the present paper we study the influences of the bias voltage and the external components on the damage progress of a bipolar transistor induced by high-power microwaves. The mechanism is presented by analyzing the variation in the internal distribution of the temperature in the device. The findings show that the device becomes less vulnerable to damage with an increase in bias voltage. Both the series diode at the base and the relatively low series resistance at the emitter, Re, can obviously prolong the burnout time of the device. However, Re will aid damage to the device when the value is sufficiently high due to the fact that the highest hot spot shifts from the base-emitter junction to the base region. Moreover, the series resistance at the base Rb will weaken the capability of the device to withstand microwave damage.

  3. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, J.C.; Shul, R.J.

    1999-02-02

    An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

  4. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, John C.; Shul, Randy J.

    1999-01-01

    An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

  5. Review of Heterojunctin Bipolar Transistor Structure, Applications, and Reliability

    NASA Technical Reports Server (NTRS)

    Lee, C.; Kayali, S.

    1993-01-01

    Heterojunction Bipolar Transistors (HBTs) are increasingly employed in high frequency, high linerity, and high efficiency applications. As the utilization of these devices becomes more widespread, their operation will be viewed with more scrutiny.

  6. Experimental Analysis of Proton-Induced Displacement and Ionization Damage Using Gate-Controlled Lateral PNP Bipolar Transistors

    NASA Technical Reports Server (NTRS)

    Ball, D. R.; Schrimpf, R. D.; Barnaby, H. J.

    2006-01-01

    The electrical characteristics of proton-irradiated bipolar transistors are affected by ionization damage to the insulating oxide and displacement damage to the semiconductor bulk. While both types of damage degrade the transistor, it is important to understand the mechanisms individually and to be able to analyze them separately. In this paper, a method for analyzing the effects of ionization and displacement damage using gate-controlled lateral PNP bipolar junction transistors is described. This technique allows the effects of oxide charge, surface recombination velocity, and bulk traps to be measured independently.

  7. Advanced insulated gate bipolar transistor gate drive

    DOEpatents

    Short, James Evans; West, Shawn Michael; Fabean, Robert J.

    2009-08-04

    A gate drive for an insulated gate bipolar transistor (IGBT) includes a control and protection module coupled to a collector terminal of the IGBT, an optical communications module coupled to the control and protection module, a power supply module coupled to the control and protection module and an output power stage module with inputs coupled to the power supply module and the control and protection module, and outputs coupled to a gate terminal and an emitter terminal of the IGBT. The optical communications module is configured to send control signals to the control and protection module. The power supply module is configured to distribute inputted power to the control and protection module. The control and protection module outputs on/off, soft turn-off and/or soft turn-on signals to the output power stage module, which, in turn, supplies a current based on the signal(s) from the control and protection module for charging or discharging an input capacitance of the IGBT.

  8. Npn double heterostructure bipolar transistor with ingaasn base region

    DOEpatents

    Chang, Ping-Chih; Baca, Albert G.; Li, Nein-Yi; Hou, Hong Q.; Ashby, Carol I. H.

    2004-07-20

    An NPN double heterostructure bipolar transistor (DHBT) is disclosed with a base region comprising a layer of p-type-doped indium gallium arsenide nitride (InGaAsN) sandwiched between n-type-doped collector and emitter regions. The use of InGaAsN for the base region lowers the transistor turn-on voltage, V.sub.on, thereby reducing power dissipation within the device. The NPN transistor, which has applications for forming low-power electronic circuitry, is formed on a gallium arsenide (GaAs) substrate and can be fabricated at commercial GaAs foundries. Methods for fabricating the NPN transistor are also disclosed.

  9. Heterojunction bipolar transistor technology for data acquisition and communication

    NASA Technical Reports Server (NTRS)

    Wang, C.; Chang, M.; Beccue, S.; Nubling, R.; Zampardi, P.; Sheng, N.; Pierson, R.

    1992-01-01

    Heterojunction Bipolar Transistor (HBT) technology has emerged as one of the most promising technologies for ultrahigh-speed integrated circuits. HBT circuits for digital and analog applications, data conversion, and power amplification have been realized, with speed performance well above 20 GHz. At Rockwell, a baseline AlGaAs/GaAs HBT technology has been established in a manufacturing facility. This paper describes the HBT technology, transistor characteristics, and HBT circuits for data acquisition and communication.

  10. Simulation of GaN/AlGaN heterojunction bipolar transistors: part I npn structures

    NASA Astrophysics Data System (ADS)

    Cao, X. A.; Van Hove, J. M.; Klaassen, J. J.; Polley, C. J.; Wowchak, A. M.; Chow, P. P.; King, D. J.; Zhang, A. P.; Dang, G.; Monier, C.; Pearton, S. J.; Ren, F.

    2000-07-01

    A drift-diffusion model was employed to calculate the dc performance of GaN/AlGaN heterojunction bipolar transistors (HBTs). The dc current gain was found to vary from ˜7 to 60 for collector currents of 10 -12-10 -2 A in 100 μm contact diameter devices with 2000 Å thick p-GaN base layers (P=2×10 17 cm-3) . The effects of base grading, base thickness, minority carrier lifetime and mobility in the base, base contact resistance and device operating temperature (25-300°C) were examined. The HBTs were found to have a significantly better gain at low collector current densities than the GaN bipolar junction transistors, due to the valence band offset.

  11. Bipolar Transistors Can Detect Charge in Electrostatic Experiments

    ERIC Educational Resources Information Center

    Dvorak, L.

    2012-01-01

    A simple charge indicator with bipolar transistors is described that can be used in various electrostatic experiments. Its behaviour enables us to elucidate links between 'static electricity' and electric currents. In addition it allows us to relate the sign of static charges to the sign of the terminals of an ordinary battery. (Contains 7 figures…

  12. Experiments with Charge Indicator Based on Bipolar Transistors

    ERIC Educational Resources Information Center

    Dvorak, Leos; Planinsic, Gorazd

    2012-01-01

    A simple charge indicator with bipolar transistors described recently enables us to perform a number of experiments suitable for high-school physics. Several such experiments are presented and discussed in this paper as well as some features of the indicator important for its use in schools, namely its sensitivity and robustness, i.e. the…

  13. Total dose and dose rate models for bipolar transistors in circuit simulation.

    SciTech Connect

    Campbell, Phillip Montgomery; Wix, Steven D.

    2013-05-01

    The objective of this work is to develop a model for total dose effects in bipolar junction transistors for use in circuit simulation. The components of the model are an electrical model of device performance that includes the effects of trapped charge on device behavior, and a model that calculates the trapped charge densities in a specific device structure as a function of radiation dose and dose rate. Simulations based on this model are found to agree well with measurements on a number of devices for which data are available.

  14. Langevin approach to noise modelling of bipolar microwave transistors

    NASA Astrophysics Data System (ADS)

    Patti, F.; Miceli, V.; Spagnolo, B.

    2000-04-01

    We present a new approach to study the complete stochastic properties of fluctuations of the output current of microwave transistors. We obtain the π-hybrid model of bipolar microwave transistors with the noise internal sources starting from experimental on-wafer measurements of the scattering and noise parameters. We derive the stochastic differential equations of the Giacoletto model for different loads and source admittances. We give the analytical temporal behavior of the second moment of the output current, assuming particular given correlation functions between the internal noise sources.

  15. The high-volume production of heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Pan, N.; Hill, D.; Rose, C.; McCullough, D.; Rice, P.; Vu, D. P.; Hong, K.; Farley, C.

    1998-08-01

    The insertion of advanced microwave devices into high-volume applications is critically dependent upon a robust and reproducible epitaxial growth technology accompanied with a reproducible process technology. The precise control of the material and device parameters is essential to maintain a high-yield process, which leads to a low-cost product. Although AlGaAs/GaAs heterojunction bipolar transistors have been widely demonstrated in many company research laboratories and universities, the transition from a laboratory environment to high-volume production requires a thorough understanding of the metalorganic chemical vapor deposition growth process and its correlation with device performance. In this work, high-performance AlGaAs/GaAs heterojunction bipolar transistors grown by MOCVD with excellent control in the device parameter tolerances have been demonstrated in very high volumes.

  16. Vertical Bipolar Charge Plasma Transistor with Buried Metal Layer

    PubMed Central

    Nadda, Kanika; Kumar, M. Jagadesh

    2015-01-01

    A self-aligned vertical Bipolar Charge Plasma Transistor (V-BCPT) with a buried metal layer between undoped silicon and buried oxide of the silicon-on-insulator substrate, is reported in this paper. Using two-dimensional device simulation, the electrical performance of the proposed device is evaluated in detail. Our simulation results demonstrate that the V-BCPT not only has very high current gain but also exhibits high BVCEO · fT product making it highly suitable for mixed signal high speed circuits. The proposed device structure is also suitable for realizing doping-less bipolar charge plasma transistor using compound semiconductors such as GaAs, SiC with low thermal budgets. The device is also immune to non-ideal current crowding effects cropping up at high current densities. PMID:25597295

  17. InP Heterojunction Bipolar Transistor Amplifiers to 255 GHz

    NASA Technical Reports Server (NTRS)

    Radisic, Vesna; Sawdai, Donald; Scott, Dennis; Deal, William; Dang, Linh; Li, Danny; Cavus, Abdullah; To, Richard; Lai, Richard

    2009-01-01

    Two single-stage InP heterojunction bipolar transistor (HBT) amplifiers operate at 184 and 255 GHz, using Northrop Grumman Corporation s InP HBT MMIC (monolithic microwave integrated circuit) technology. At the time of this reporting, these are reported to be the highest HBT amplifiers ever created. The purpose of the amplifier design is to evaluate the technology capability for high-frequency designs and verify the model for future development work.

  18. Doping To Reduce Base Resistances Of Bipolar Transistors

    NASA Technical Reports Server (NTRS)

    Lin, True-Lon

    1991-01-01

    Modified doping profile proposed to reduce base resistance of bipolar transistors. A p/p+ base-doping profile reduces base resistance without reducing current gain. Proposed low/high base-doping profile realized by such low-temperature deposition techniques as molecular-beam epitaxy, ultra-high-vacuum chemical-vapor deposition, and limited-reaction epitaxy. Produces desired doping profiles without excessive diffusion of dopant.

  19. An improved junction capacitance model for junction field-effect transistors

    NASA Astrophysics Data System (ADS)

    Ding, Hao; Liou, Juin J.; Cirba, Claude R.; Green, Keith

    2006-07-01

    A new junction capacitance model for the four-terminal junction field-effect transistor (JFET) is presented. With a single expression, the model, which is valid for different temperatures and a wide range of bias conditions, describes correctly the JFET junction capacitance behavior and capacitance drop-off phenomenon. The model has been verified using experimental data measured at Texas Instruments.

  20. Correlated noise in bipolar transistors: Model implementation issues

    NASA Astrophysics Data System (ADS)

    Huszka, Zoltan; Chakravorty, Anjan

    2015-12-01

    A new orthogonalization scheme is suggested for implementing correlated noise of bipolar transistors. The scheme provides a necessary condition on the non-quasi-static (NQS) models that can be used to obtain an implementation-suitable correlated noise model. One of the solutions presented here corresponds to a single node realization not reported so far. The gm -factor is introduced in the noise analysis explaining the deviations of a former noise model from device simulations. The model is extended to include the collector space-charge-region induced noise by retaining the simplicity of the realization and preserving the model parameter count.

  1. The dc characteristics of GaAs/AlGaAs heterojunction bipolar transistors with application to device modeling

    NASA Astrophysics Data System (ADS)

    Hafizi, Madjid E.; Crowell, Clarence R.; Grupen, Matthew E.

    1990-10-01

    A complete dc model for the heterojunction bipolar transistor (HBT) is presented. The HBT dc characteristics are compared with the Ebers-Moll (EM) model for conventional bipolar junction transistors (BJTs). It is shown that, although the details of HBT operation can differ markedly from those of a BJT, a model and a parameter extraction technique can be developed which have physical meaning and are exactly compatible with the EM models widely used for BJTs. Device I-V measurements at 77 and 300 K are used to analyze HBT performance in the context of an EM model. A technique is developed to extract the device base, emitter, and collector series resistances directly from the measured I-V data without requiring an ideal base current as reference. Accuracies of the extracted series resistances are assessed. The ac parameters of HBTs are calculated numerically from the physical device structure and shown to be comparable to those of conventional BJTs.

  2. Auger recombination in heavily doped shallow-emitter silicon p-n-junction solar cells, diodes, and transistors

    NASA Technical Reports Server (NTRS)

    Shibib, M. A.; Lindholm, F. A.; Fossum, J. G.

    1979-01-01

    A rigorous analytic evaluation of an emitter model that includes Auger recombination but excludes bandgap narrowing is presented. It is shown that such a model cannot explain the experimentally observed values of the open-circuit voltage in p-n-junction silicon solar cells. Thus physical mechanisms in addition to Auger recombination are responsible for the experimentally observed values of the open-circuit voltage in silicon solar cells and the common-emitter current gain in bipolar transistors.

  3. Vapor grown silicon dioxide improves transistor base-collector junctions

    NASA Technical Reports Server (NTRS)

    Carley, D. R.; Duclos, R. A.

    1966-01-01

    Vapor grown silicon dioxide layer protects base-collector junction in silicon planar transistors during the emitter diffusion process. This oxide fills in any imperfections that exist in the thermally grown oxide layer and is of greater thickness than that layer. This process is used to deposit protective silicon dioxide coatings on optical surfaces.

  4. A hybrid model to calculate the forward delay time of heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Kumar, T.; Cahay, M.; Shi, S.; Roenker, K.; Stanchina, W. E.

    1995-07-01

    The forward delay time (τ F) of heterojunction bipolar transistors (HBTs) is calculated using a hybrid model of carrier transport. A rigorous quantum-mechanical treatment of electron tunneling and thermionic emission across the spike at the emitter-base junction is used to determine the energy of the electron flux injected into the base region. This flux is used as an initial distribution in a regional Monte Carlo simulator to model electron transport from base to sub-collector. In this paper, we estimate the base transit time using the impulse response technique and the collector delay time using the expression of Laux and Lai (IEEE Electron Device Letters, 11, 174, 1990). Improvements to the hybrid model proposed here to reduce some of the discrepancies between measured and calculated values of ƒ τ for some InAlAs/InGaAs and InP/InGaAs structures reported in the literature are discussed.

  5. Microwave damage susceptibility trend of a bipolar transistor as a function of frequency

    NASA Astrophysics Data System (ADS)

    Ma, Zhen-Yang; Chai, Chang-Chun; Ren, Xing-Rong; Yang, Yin-Tang; Chen, Bin; Song, Kun; Zhao, Ying-Bo

    2012-09-01

    We conduct a theoretical study of the damage susceptibility trend of a typical bipolar transistor induced by a high-power microwave (HPM) as a function of frequency. The dependences of the burnout time and the damage power on the signal frequency are obtained. Studies of the internal damage process and the mechanism of the device are carried out from the variation analysis of the distribution of the electric field, current density, and temperature. The investigation shows that the burnout time linearly depends on the signal frequency. The current density and the electric field at the damage position decrease with increasing frequency. Meanwhile, the temperature elevation occurs in the area between the p-n junction and the n-n+ interface due to the increase of the electric field. Adopting the data analysis software, the relationship between the damage power and frequency is obtained. Moreover, the thickness of the substrate has a significant effect on the burnout time.

  6. Microwave power heterojunction bipolar transistors fabricated with thermal shunt bathtub

    SciTech Connect

    Bozada, C.A.; Barlage, D.W.; Barrette, J.P.

    1995-12-31

    Heterojunction bipolar transistor devices and circuits were fabricated using thermal shunt and bathtub thermal management techniques. Broadband cascode MMICs exhibited 10 - 14 dB gain at an output power of 2.5 - 3.0 Watts across 7 - 11 GHz. A 200 {mu}m{sup 2} common-emitter unit cell achieved 7 - 8 dB linear power gain and 40% power-added efficiency at a noise power ratio (NPR) of 18 dBc at 12 GHz. Under single tone measurements at 12 GHz, the unit cell achieved 52% power-added efficiency, with 9.5 dB linear gain, 8 dB power gain and 240 mW output power at 5 V bias.

  7. Development of gallium nitride-based PNP heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Green, Daniel S.

    GaN-based electronics have progressed mightily in the last 15 years. The primary focus of this development has been the AlGaN/GaN heterostructure FET, with the commercialization of this device in progress. Bipolar transistors however offer a few key potential advantages over the FET device, including the primary advantage of normally off operation. Additionally, the pnp heterostructure bipolar transistor (HBT) in particular offers more attractive base performance relative to the npn HBT. The pnp HBT also serves as an excellent test vehicle for the several material parameters of p-Gan that remain poor defined. However, implementation of the pnp HBT has been limited by the difficulty contacting p-GaN collector material. This work was designed to demonstrate and understand the pnp HBT. The research served as both an engineering challenge as well as an investigation of physical parameters governing the transport in the device. In order to remedy the poor collector contact available with buried p-GaN, a transformation diode HBT structure was introduced that added an n-type subcollector the HBT structure. This allowed for good collector contact at the cost of introducing an offset voltage to the HBT performance due to the turn-on voltage of the transformation diode under normal operation. The first transformation diode HBT in GaN was successful demonstrated. In order to improve the transformation diode performance, successive design iterations were performed to isolate the performance limiting elements. Device designs were implemented to mitigate saturated hole velocity, as well as to decrease base transit time through aggressive base scaling and compositional grading. Physical simulations and modelling of device non-idealities were used to understand actual device performance. Hole lifetime and saturated hole velocity were identified as primary contributors to lower than expected performance device performance. Successive device iterations yielded HBT performance of

  8. Understanding the failure mechanisms of microwave bipolar transistors caused by electrostatic discharge

    NASA Astrophysics Data System (ADS)

    Jin, Liu; Yongguang, Chen; Zhiliang, Tan; Jie, Yang; Xijun, Zhang; Zhenxing, Wang

    2011-10-01

    Electrostatic discharge (ESD) phenomena involve both electrical and thermal effects, and a direct electrostatic discharge to an electronic device is one of the most severe threats to component reliability. Therefore, the electrical and thermal stability of multifinger microwave bipolar transistors (BJTs) under ESD conditions has been investigated theoretically and experimentally. 100 samples have been tested for multiple pulses until a failure occurred. Meanwhile, the distributions of electric field, current density and lattice temperature have also been analyzed by use of the two-dimensional device simulation tool Medici. There is a good agreement between the simulated results and failure analysis. In the case of a thermal couple, the avalanche current distribution in the fingers is in general spatially unstable and results in the formation of current crowding effects and crystal defects. The experimental results indicate that a collector-base junction is more sensitive to ESD than an emitter-base junction based on the special device structure. When the ESD level increased to 1.3 kV, the collector-base junction has been burnt out first. The analysis has also demonstrated that ESD failures occur generally by upsetting the breakdown voltage of the dielectric or overheating of the aluminum-silicon eutectic. In addition, fatigue phenomena are observed during ESD testing, with devices that still function after repeated low-intensity ESDs but whose performances have been severely degraded.

  9. Neutron effects on the electrical and switching characteristics of NPN bipolar power transistors

    NASA Technical Reports Server (NTRS)

    Frasca, Albert J.; Schwarze, Gene E.

    1988-01-01

    The use of nuclear reactors to generate electrical power for future space missions will require the electrical components used in the power conditioning, control, and transmission subsystem to operate in the associated radiation environments. An initial assessment of neutron irradiation on the electrical and switching characteristics of commercial high power NPN bipolar transistors was investigated. The results clearly show the detrimental effects caused by neutron irradiation on the electrical and switching characteristics of the NPN bipolar power transistor.

  10. Long-Term Reliability of High Speed SiGe/Si Heterojunction Bipolar Transistors

    NASA Technical Reports Server (NTRS)

    Ponchak, George E. (Technical Monitor); Bhattacharya, Pallab

    2003-01-01

    Accelerated lifetime tests were performed on double-mesa structure Si/Si0.7Ge0.3/Si npn heterojunction bipolar transistors, grown by molecular beam epitaxy, in the temperature range of 175C-275C. Both single- and multiple finger transistors were tested. The single-finger transistors (with 5x20 micron sq m emitter area) have DC current gains approximately 40-50 and f(sub T) and f(sub MAX) of up to 22 GHz and 25 GHz, respectively. The multiple finger transistors (1.4 micron finger width, 9 emitter fingers with total emitter area of 403 micron sq m) have similar DC current gain but f(sub T) of 50 GHz. It is found that a gradual degradation in these devices is caused by the recombination enhanced impurity diffusion (REID) of boron atoms from the p-type base region and the associated formation of parasitic energy barriers to electron transport from the emitter to collector layers. This REID has been quantitatively modeled and explained, to the first order of approximation, and the agreement with the measured data is good. The mean time to failure (MTTF) of the devices at room temperature is estimated from the extrapolation of the Arrhenius plots of device lifetime versus reciprocal temperature. The results of the reliability tests offer valuable feedback for SiGe heterostructure design in order to improve the long-term reliability of the devices and circuits made with them. Hot electron induced degradation of the base-emitter junction was also observed during the accelerated lifetime testing. In order to improve the HBT reliability endangered by the hot electrons, deuterium sintered techniques have been proposed. The preliminary results from this study show that a deuterium-sintered HBT is, indeed, more resistant to hot-electron induced base-emitter junction degradation. SiGe/Si based amplifier circuits were also subjected to lifetime testing and we extrapolate MTTF is approximately 1.1_10(exp 6) hours at 125iC junction temperature from the circuit lifetime data.

  11. Degradation of InGaAs/InP double heterojunction bipolar transistors under electron irradiation

    SciTech Connect

    Bandyopadhyay, A.; Subramanian, S.; Chandrasekhar, S.; Dentai, A.G.; Goodnick, S.M.

    1999-05-01

    The dc characteristics of InGaAs/InP double heterojunction bipolar transistors (DHBT`s) are studied under high-energy ({approximately}1 MeV) electron irradiation up to a fluence of 14.8 {times} 10{sup 15} electrons/cm{sup 2}. The devices show an increase in common-emitter current gain (h{sub fe}) at low levels of dose (<10{sup 15} electrons/cm{sup 2}) and a gradual decrease in h{sub fe} and an increase in output conductance for higher doses. The decrease in h{sub fe} is as much as {approximately}80% at low base currents ({approximately}10 {micro}A) after a cumulative dose of 14.8 {times} 10{sup 15} electrons/cm{sup 2}. The observed degradation effects in collector current-voltage (I-V) characteristics are studied quantitatively using a simple SPICE-like device model. The overall decrease in h{sub fe} is attributed to increased recombination in the emitter-base junction region caused by radiation-induced defects. The defects introduced in the collector-base junction region are believed to be responsible for the observed increase in the output conductance.

  12. Radiation effects in III-V semiconductors and heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Shatalov, Alexei

    The electron, gamma and neutron radiation degradation of III-V semiconductors and heterojunction bipolar transistors (HBTs) is investigated in this thesis. Particular attention is paid to InP and InGaAs materials and InP/InGaAs abrupt single HBTs (SHBTs). Complete process sequences for fabrication of InP/ InGaAs HBTs are developed and subsequently employed to produce the devices, which are then electrically characterized and irradiated with the different types of radiation. A comprehensive analytical HBT model is developed and radiation damage calculations are performed to model the observed radiation-induced degradation of SHBTs. The most pronounced radiation effects found in SHBTs include reduction of the common-emitter DC current gain, shift of the collector-emitter (CE) offset voltage and increase of the emitter, base and collector parasitic resistances. Quantitative analysis performed using the developed model demonstrates that increase of the neutral bulk and base-emitter (BE) space charge region (SCR) components of the base current are responsible for the observed current gain degradation. The rise of the neutral bulk recombination is attributed to decrease in a Shockley-Read-Hall (SRH) carrier lifetime, while the SCR current increase is caused by rising SCR SRH recombination and activation of a tunneling-recombination mechanism. On the material level these effects are explained by displacement defects produced in a semiconductor by the incident radiation. The second primary change of the SHBT characteristics, CE offset voltage shift, is induced by degradation of the base- collector (BC) junction. The observed rise of the BC current is brought on by diffusion and recombination currents which increase as more defects are introduced in a semiconductor. Finally, the resistance degradation is attributed to deterioration of low-doped layers of a transistor, and to degradation of the device metal contacts.

  13. InGaP/InGaAsN/GaAs NpN double-heterojunction bipolar transistor

    SciTech Connect

    Chang, P. C.; Baca, A. G.; Li, N. Y.; Xie, X. M.; Hou, H. Q.; Armour, E.

    2000-04-17

    We have demonstrated a functional NpN double-heterojunction bipolar transistor (DHBT) using InGaAsN for the base layer. The InGaP/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}/GaAs DHBT has a low V{sub ON} of 0.81 V, which is 0.13 V lower than in a InGaP/GaAs heterojunction bipolar transistor (HBT). The lower turn-on voltage is attributed to the smaller band gap (1.20 eV) of metalorganic chemical vapor deposition-grown In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} base layer. GaAs is used for the collector; thus the breakdown voltage (BV{sub CEO}) is 10 V, consistent with the BV{sub CEO} of InGaP/GaAs HBTs of comparable collector thickness and doping level. To alleviate the current blocking phenomenon caused by the larger conduction band discontinuity between InGaAsN and GaAs, a graded InGaAs layer with {delta} doping is inserted at the base-collector junction. The improved device has a peak current gain of seven with ideal current-voltage characteristics. (c) 2000 American Institute of Physics.

  14. Lateral carrier diffusion and current gain in terahertz InGaAs/InP double-heterojunction bipolar transistors

    SciTech Connect

    Chiang, Han-Wei; Rode, Johann C.; Choudhary, Prateek; Rodwell, Mark J. W.

    2014-01-21

    The DC current gain in In{sub 0.53}Ga{sub 0.47}As/InP double-heterojunction bipolar transistors is computed based on a drift-diffusion model, and is compared with experimental data. Even in the absence of other scaling effects, lateral diffusion of electrons to the base Ohmic contacts causes a rapid reduction in DC current gain as the emitter junction width and emitter-base contact spacing are reduced. The simulation and experimental data are compared in order to examine the effect of carrier lateral diffusion on current gain. The impact on current gain due to device scaling and approaches to increase current gain are discussed.

  15. Epitaxially-Grown GaN Junction Field Effect Transistors

    SciTech Connect

    Baca, A.G.; Chang, P.C.; Denbaars, S.P.; Lester, L.F.; Mishra, U.K.; Shul, R.J.; Willison, C.G.; Zhang, L.; Zolper, J.C.

    1999-05-19

    Junction field effect transistors (JFET) are fabricated on a GaN epitaxial structure grown by metal organic chemical vapor deposition (MOCVD). The DC and microwave characteristics of the device are presented. A junction breakdown voltage of 56 V is obtained corresponding to the theoretical limit of the breakdown field in GaN for the doping levels used. A maximum extrinsic transconductance (gm) of 48 mS/mm and a maximum source-drain current of 270 mA/mm are achieved on a 0.8 µ m gate JFET device at VGS= 1 V and VDS=15 V. The intrinsic transconductance, calculated from the measured gm and the source series resistance, is 81 mS/mm. The fT and fmax for these devices are 6 GHz and 12 GHz, respectively. These JFETs exhibit a significant current reduction after a high drain bias is applied, which is attributed to a partially depleted channel caused by trapped hot-electrons in the semi-insulating GaN buffer layer. A theoretical model describing the current collapse is described, and an estimate for the length of the trapped electron region is given.

  16. Transferred substrate heterojunction bipolar transistors for submillimeter wave applications

    NASA Technical Reports Server (NTRS)

    Fung, A.; Samoska, L.; Siegel, P.; Rodwell, M.; Urteaga, M.; Paidi, V.

    2003-01-01

    We present ongoing work towards the development of submillimeter wave transistors with goals of realizing advanced high frequency amplifiers, voltage controlled oscillators, active multipliers, and traditional high-speed digital circuits.

  17. Lateral PNP bipolar transistor with aiding field diffusions

    NASA Technical Reports Server (NTRS)

    Gallagher, R. C.; Mc Cann, D. H.

    1969-01-01

    Fabrication technique produces field aided lateral PNP transistors compatible with micropower switching circuits. The sub-collector diffusion is performed with phosphorus as the dopant and the epitaxy is grown using the higher temperature silicon tetrachloride process.

  18. Analysis of collector-emitter offset voltage of InGaP/GaAs composite collector double heterojunction bipolar transistor

    NASA Astrophysics Data System (ADS)

    Lew, K. L.; Yoon, S. F.

    2002-04-01

    The Ebers-Moll-like terminal current expressions of a composite collector double heterojunction bipolar transistor (DHBT), which takes the recombination effect into account, have been formulated and an expression for collector-emitter offset voltage [VCE(offset)] has been derived. Factors affecting the VCE(offset) of a composite collector DHBT are investigated and good agreement between the calculated and reported experimental results is shown. Analytical results showed that the transmission coefficient of the base-collector (B-C) junction does not have a considerable effect on the VCE(offset), provided that the B-C junction is of good quality. Thus, despite its asymmetric structure, the VCE(offset) of an optimally designed composite collector DHBT could be as low as that of a conventional DHBT. Hence a composite collector DHBT with low saturation voltage and negligible VCE(offset) is possible if the two conditions: (i) good quality B-C junction, (ii) base transport factor, α≈1, are fulfilled.

  19. A single epitaxial structure for the integration of lasers with heterostructure bipolar transistors

    NASA Astrophysics Data System (ADS)

    Goyal, Anish Kumar

    This dissertation introduces a new method of monolithically integrating lasers and heterostructure bipolar transistors (HBTs). This method relies on placing the gain medium for lasers in the collector layer of an (Al,Ga)As HBT epitaxial structure. The trade-offs between laser and HBT performance which are associated with such an integration method are discussed in detail. Two designs based on this method were evaluated experimentally. In the first design, an Npn, emitter-up HBT epitaxial structure was modified to incorporated three Insb{0.2}Gasb{0.8}As QWs in the collector layer which serve as the optical gain media for lasers. 13 x 13 μmsp2 HBTs fabricated from this epi-material exhibited common emitter current gains >50 while 6×20\\ μmsp2 HBTs exhibited an fsb{t}=21 GHz and fsb{max}=6.8 GHz. The DC and high frequency characteristics of HBTs are consistent with their size, layer thicknesses, layer dopings, etc. Metal-clad lasers were also fabricated from this epi-material. For these lasers, a silver film deposited directly on the base served as both the upper optical cladding layer and p-electrode. Lasers exhibit pulsed threshold current densities as low as 440 A/cmsp2. The measured waveguide propagation loss of these metal-clad lasers is in excellent agreement with theory. The second design was based on a Pnp, collector-up HBT epitaxial structure. For HBTs, the extrinsic portion of the EB junction was not deactivated and resulted in HBTs with less than unity current gain. 6.5 mum stripe width, ridge waveguide lasers fabricated from this same material exhibited threshold current densities of ˜1300 A/cmsp2. This is approximately what is expected from the epitaxial layer design and device structure. Furthermore, the measured waveguide propagation loss of 14 cmsp{-1} is close to the anticipated value of 11.2 cmsp{-1}.

  20. Ion-implanted GaN junction field effect transistor

    SciTech Connect

    Zolper, J.C.; Shul, R.J.; Baca, A.G.; Wilson, R.G.; Pearton, S.J.; Stall, R.A.

    1996-04-01

    Selective area ion implantation doping has been used to fabricate GaN junction field effect transistors (JFETs). {ital p}-type and {ital n}-type doping was achieved with Ca and Si implantation, respectively, followed by a 1150{degree}C rapid thermal anneal. A refractory W gate contact was employed that allows the {ital p}-gate region to be self-aligned to the gate contact. A gate turn-on voltage of 1.84 V at 1 mA/mm of gate current was achieved. For a {approximately}1.7 {mu}m{times}50 {mu}m JFET with a {minus}6 V threshold voltage, a maximum transconductance of 7 mS/mm at {ital V}{sub GS}={minus} 2V and saturation current of 33 mA/mm at {ital V}{sub GS}=0 V were measured. These results were limited by excess access resistance and can be expected to be improved with optimized {ital n}{sup +} implants in the source and drain regions. {copyright} {ital 1996 American Institute of Physics.}

  1. Unified planar process for fabricating heterojunction bipolar transistors and buried-heterostructure lasers utilizing impurity-induced disordering

    SciTech Connect

    Thornton, R.L.; Mosby, W.J.; Chung, H.F.

    1988-12-26

    We describe results on a novel geometry of heterojunction bipolar transistor that has been realized by impurity-induced disordering. This structure is fabricated by a method that is compatible with techniques for the fabrication of low threshold current buried-heterostructure lasers. We have demonstrated this compatibility by fabricating a hybrid laser/transistor structure that operates as a laser with a threshold current of 6 mA at room temperature, and as a transistor with a current gain of 5.

  2. Unified planar process for fabricating heterojunction bipolar transistors and buried-heterostructure lasers utilizing impurity-induced disordering

    NASA Astrophysics Data System (ADS)

    Thornton, R. L.; Mosby, W. J.; Chung, H. F.

    1988-12-01

    We describe results on a novel geometry of heterojunction bipolar transistor that has been realized by impurity-induced disordering. This structure is fabricated by a method that is compatible with techniques for the fabrication of low threshold current buried-heterostructure lasers. We have demonstrated this compatibility by fabricating a hybrid laser/transistor structure that operates as a laser with a threshold current of 6 mA at room temperature, and as a transistor with a current gain of 5.

  3. Simulation of synergistic effects on lateral PNP bipolar transistors induced by neutron and gamma irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Chenhui; Bai, Xiaoyan; Chen, Wei; Yang, Shanchao; Liu, Yan; Jin, Xiaoming; Ding, Lili

    2015-10-01

    With semiconductor device simulation software TCAD, numerical simulations of ionizing/displacement synergistic effects on 6 kinds of lateral PNP bipolar transistors induced by the mixed irradiation of neutron and gamma are carried out by means of changing the minority carrier lifetimes, adding charged traps to the oxide layer and increasing the surface recombination velocity in Si/SiO2 interface. The results indicate that ionizing/displacement synergistic effects on the lateral PNP bipolar transistors are not a simple sum of total ionizing dose effects and displacement effects, and total ionizing dose effects can enhance neutron displacement damages, leading to greater gain degradation. The physical mechanisms of ionizing/displacement synergistic effects are analyzed based on the results. The positive charge in the oxide layer and Si/SiO2 interface traps induced by gamma irradiation can enhance the recombination processes of carriers in the bulk defects induced by neutron irradiation, and this is the main cause of ionizing/displacement synergistic effects on the lateral PNP bipolar transistors.

  4. Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion

    PubMed Central

    Martí, A.; Luque, A.

    2015-01-01

    Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base–emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers that are required to match the limiting efficiency of dual-junction solar cells without using tunnel junctions. The device naturally emerges as a three-terminal solar cell and can also be used as building block of multijunction solar cells with an increased number of junctions. PMID:25902374

  5. Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion.

    PubMed

    Martí, A; Luque, A

    2015-01-01

    Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base-emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers that are required to match the limiting efficiency of dual-junction solar cells without using tunnel junctions. The device naturally emerges as a three-terminal solar cell and can also be used as building block of multijunction solar cells with an increased number of junctions. PMID:25902374

  6. An approximate HSPICE model for orbit low noise analog bipolar NPN transistors

    SciTech Connect

    Zimmerman, T.

    1991-07-01

    Vertical bipolar NPN transistors can be fabricated cheaply through MOSIS by using the Orbit 2 um Low Noise Analog CMOS process. The collector is formed from an N-well, the base from a p-base diffusion, and the emitter from an N-diffusion. However, since this is a CMOS process there is no buried layer in the collector. Therefore the collector resistance is quite large. Also, the minimum emitter size is 8 um {times} 8 um, which is substantially larger than many fast bipolar processes. For certain applications, though, such as common base or emitter follower amplifiers, the performance of this transistor may be quite acceptable. However, no AC SPICE model is published for this device. This paper describes a simple approximate measurement method that was used at Fermilab to formulate an HSPICE model for these transistor. This method requires only a fast pulse generator and a good digitizing oscilloscope with an active FET probe for the AC measurements. Model parameters for two transistors of different size are then given. 1 ref., 1 fig.

  7. Ballistic bipolar junctions in chemically gated graphene ribbons

    PubMed Central

    Baringhaus, Jens; Stöhr, Alexander; Forti, Stiven; Starke, Ulrich; Tegenkamp, Christoph

    2015-01-01

    The realization of ballistic graphene pn-junctions is an essential task in order to study Klein tunneling phenomena. Here we show that intercalation of Ge under the buffer layer of pre-structured SiC-samples succeeds to make truly nano-scaled pn-junctions. By means of local tunneling spectroscopy the junction width is found to be as narrow as 5 nm which is a hundred times smaller compared to electrically gated structures. The ballistic transmission across the junction is directly proven by systematic transport measurements with a 4-tip STM. Various npn- and pnp-junctions are studied with respect to the barrier length. The pn-junctions are shown to act as polarizer and analyzer with the second junction becoming transparent in case of a fully ballistic barrier. This can be attributed to the almost full suppression of electron transmission through the junction away from normal incidence. PMID:25898259

  8. Investigation and application of neutron damage to bipolar transistors in light water reactor dosimetry

    SciTech Connect

    Roknizadeh, M.

    1987-01-01

    A method of fast neutron metrology and a basis for prediction of changes in performance parameters of semiconductor devices in power plant radiation environments has been established using Cf-252 sources. Three general purpose NPN bipolar transistors (PN2222A, ECG-196, and ECG-184) were chosen as the neutron damage monitors and the change in inverse d.c. current gain before and after irradiation was chosen as the damage parameter for the measurement. The main findings of the investigation were as follows: the change in inverse d.c. current gain for PN2222A transistors was approximately a linear function of the neutron fluence up to 2.0E15 n(1MeV)/cm/sup 2/. The concept of 1-MeV equivalent neutron fluence which characterizes an incident energy-fluence spectrum in terms of the fluence of monoenergetic neutrons at 1 MeV, is in error for application to common transistors in a typical power plant environment. Finally, the normalized damage coefficient which is the ratio of damage to 1-MeV equivalent neutron fluence divided by the measured base transit time of individual transistors, for all three types of transistors is nearly the same with an average value of 1.27E - 7 +/- 15.0% cm/sup 2//m(1 MeV).Sec.

  9. Demonstration and properties of a planar heterojunction bipolar transistor with lateral current flow

    NASA Astrophysics Data System (ADS)

    Thornton, Robert L.; Mosby, William J.; Chung, Harlan F.

    1989-10-01

    The authors present fabrication techniques and device performance for a novel transistor structure, the lateral heterojunction bipolar transistor. The lateral heterojunctions are formed by impurity-induced disordering of a GaAs base layer sandwiched between two AlGaAs layers. These transistor structures exhibit current gains of 14 for base widths of 0.74 micron. Transistor action in this device occurs parallel to the surface of the device structure. The active base region of the structure is completely submerged, resulting in a reduction of surface recombination as a mechanism for gain reduction in the device. Impurity-induced disordering is used to widen the bandgap of the alloy in the emitter and collector, resulting in an improvement of the emitter injection efficiency. Since the device is based entirely on a surface diffusion process, the device is completely planar and has no steps involving etching of the III-V alloy material. These advantages lead this device to be considered as a candidate for optoelectronic integration applications. The transistor device functions as a buried heterostructure laser, with a threshold current as low as 6 mA for a 1.4-micron stripe.

  10. Two integral relations pertaining to the electron transport through a bipolar transistor with a nonuniform energy gap in the base region

    NASA Astrophysics Data System (ADS)

    Kroemer, H.

    1985-11-01

    The two integral relations by Moll and Ross for the current flow through the base region of a bipolar transistor, and for the base transit time, are generalized to the case of a heterostructure bipolar transistor with a nonuniform energy gap in the base region.

  11. Numerical analysis of distortion characteristics of heterojunction bipolar transistor laser

    NASA Astrophysics Data System (ADS)

    Piramasubramanian, S.; Ganesh Madhan, M.; Nagella, Jyothsna; Dhanapriya, G.

    2015-12-01

    Numerical analysis of harmonic and third order intermodulation distortion of transistor laser is presented in this paper. The three level rate equations are numerically solved to determine the modulation and distortion characteristics. DC and AC analysis on the device are carried out to determine its power-current and frequency response characteristics. Further, the effects of quantum well recombination time and electron capture time in the quantum well, on the modulation depth and distortion characteristics are examined. It is observed that the threshold current density of the device decreases with increasing electron lifetime, which coincides with earlier findings. Also, the magnitude of harmonic distortion and intermodulation products are found to reduce with increasing current density and with a reduction of spontaneous emission recombination lifetime. However, an increase of electron capture time improves the distortion performance. A maximum modulation depth of 18.42 dB is obtained for 50 ps spontaneous emission life time and 1 ps electron capture time, for 2.4 GHz frequency at a current density of 2Jth. A minimum second harmonic distortion magnitude of -66.8 dBc is predicted for 50 ps spontaneous emission life time and 1 ps electron capture time for 2.4 GHz frequency, at a current density of 7Jth. Similarly, a minimum third order intermodulation distortion of -83.93 dBc is obtained for 150 ps spontaneous emission life time and 5 ps electron capture time under similar biasing conditions.

  12. Efficient far-infrared thermal bremsstrahlung radiation from a heterojunction bipolar transistor

    SciTech Connect

    Chung, Pei-Kang; Yen, Shun-Tung

    2015-08-28

    We investigate the far-infrared thermal radiation properties of a heterojunction bipolar transistor. The device conveniently provides a high electric field for electrons to heat the lattice and the electron gas in a background with ions embedded. Because of very high effective temperature of the electron gas in the collector, the electron-ion bremsstrahlung makes efficient the thermal radiation in the far-infrared region. The transistor can yield a radiation power of 0.1 mW with the spectral region between 2 and 75 THz and a power conversion efficiency of 6 × 10{sup −4}. Such output contains a power of 20 μW in the low-frequency part (2–20 THz) of the spectrum.

  13. T-shaped emitter metal heterojunction bipolar transistors for submillimeter wave applications

    NASA Technical Reports Server (NTRS)

    Fung, Andy; Samoska, Lorene; Velebir, Jim; Siege, Peter; Rodwell, Mark; Paidi, Vamsi; Griffth, Zach; Urteaga, Miguel; Malik, Roger

    2004-01-01

    We report on the development of submillimeter wave transistors at JPL. The goal of the effort is to produce advance-reliable high frequency and high power amplifiers, voltage controlled oscillators, active multipliers, and high-speed mixed-signal circuits for space borne applications. The technology in development to achieve this is based on the Indium Phosphide (InP) Heterojunction Bipolar Transistor (HBT). The HBT is well suited for high speed, high power and uniform (across wafer) performance, due to the ability to tailor the material structure that electrons traverse through by well-controlled epitaxial growth methods. InP with its compatible lattice matched alloys such as indium gallium arsenide (InGaAs) and indium aluminium arsenide (InAlAs) provides for high electron velocities and high voltage breakdown capabilities. The epitaxial methods for this material system are fairly mature, however the implementation of high performance and reliable transistors are still under development by many laboratories. Our most recently fabricated, second generation mesa HBTs at JPL have extrapolated current gain cutoff frequency (FJ of 142GHz and power gain cutoff frequency (Fm,) of approximately 160GHz. This represents a 13% and 33% improvement of Ft and F, respectively, compared to the first generation mesa HBTs [l]. Analysis based on the University of California, Santa Barbara (UCSB) device model, RF device characteristics can be significantly improved by reducing base contact resistance and base metal contact width. We will describe our effort towards increasing transistor performance and yield.

  14. Cryogenic preamplification of a single-electron-transistor using a silicon-germanium heterojunction-bipolar-transistor

    NASA Astrophysics Data System (ADS)

    Curry, M. J.; England, T. D.; Bishop, N. C.; Ten-Eyck, G.; Wendt, J. R.; Pluym, T.; Lilly, M. P.; Carr, S. M.; Carroll, M. S.

    2015-05-01

    We examine a silicon-germanium heterojunction bipolar transistor (HBT) for cryogenic pre-amplification of a single electron transistor (SET). The SET current modulates the base current of the HBT directly. The HBT-SET circuit is immersed in liquid helium, and its frequency response from low frequency to several MHz is measured. The current gain and the noise spectrum with the HBT result in a signal-to-noise-ratio (SNR) that is a factor of 10-100 larger than without the HBT at lower frequencies. The transition frequency defined by SNR = 1 has been extended by as much as a factor of 10 compared to without the HBT amplification. The power dissipated by the HBT cryogenic pre-amplifier is approximately 5 nW to 5 μW for the investigated range of operation. The circuit is also operated in a single electron charge read-out configuration in the time-domain as a proof-of-principle demonstration of the amplification approach for single spin read-out.

  15. Cryogenic Preamplification of a Single-Electron-Transistor using a Silicon-Germanium Heterojunction-Bipolar-Transistor

    DOE PAGESBeta

    Curry, Matthew J.; England, Troy Daniel; Bishop, Nathaniel; Ten Eyck, Gregory A.; Wendt, Joel R.; Pluym, Tammy; Lilly, Michael; Carr, Stephen M; Carroll, Malcolm S.

    2015-05-21

    We examine a silicon-germanium heterojunction bipolar transistor (HBT) for cryogenic pre-amplification of a single electron transistor (SET). The SET current modulates the base current of the HBT directly. The HBT-SET circuit is immersed in liquid helium, and its frequency response from low frequency to several MHz is measured. The current gain and the noise spectrum with the HBT result in a signal-to-noise-ratio (SNR) that is a factor of 10–100 larger than without the HBT at lower frequencies. Furthermore, the transition frequency defined by SNR = 1 has been extended by as much as a factor of 10 compared to withoutmore » the HBT amplification. The power dissipated by the HBT cryogenic pre-amplifier is approximately 5 nW to 5 μW for the investigated range of operation. We found that the circuit is also operated in a single electron charge read-out configuration in the time-domain as a proof-of-principle demonstration of the amplification approach for single spin read-out.« less

  16. Cryogenic preamplification of a single-electron-transistor using a silicon-germanium heterojunction-bipolar-transistor

    SciTech Connect

    Curry, M. J.; England, T. D.; Bishop, N. C.; Ten-Eyck, G.; Wendt, J. R.; Pluym, T.; Lilly, M. P.; Carroll, M. S.; Carr, S. M.

    2015-05-18

    We examine a silicon-germanium heterojunction bipolar transistor (HBT) for cryogenic pre-amplification of a single electron transistor (SET). The SET current modulates the base current of the HBT directly. The HBT-SET circuit is immersed in liquid helium, and its frequency response from low frequency to several MHz is measured. The current gain and the noise spectrum with the HBT result in a signal-to-noise-ratio (SNR) that is a factor of 10–100 larger than without the HBT at lower frequencies. The transition frequency defined by SNR = 1 has been extended by as much as a factor of 10 compared to without the HBT amplification. The power dissipated by the HBT cryogenic pre-amplifier is approximately 5 nW to 5 μW for the investigated range of operation. The circuit is also operated in a single electron charge read-out configuration in the time-domain as a proof-of-principle demonstration of the amplification approach for single spin read-out.

  17. Cryogenic Preamplification of a Single-Electron-Transistor using a Silicon-Germanium Heterojunction-Bipolar-Transistor

    SciTech Connect

    Curry, Matthew J.; England, Troy Daniel; Bishop, Nathaniel; Ten Eyck, Gregory A.; Wendt, Joel R.; Pluym, Tammy; Lilly, Michael; Carr, Stephen M; Carroll, Malcolm S.

    2015-05-21

    We examine a silicon-germanium heterojunction bipolar transistor (HBT) for cryogenic pre-amplification of a single electron transistor (SET). The SET current modulates the base current of the HBT directly. The HBT-SET circuit is immersed in liquid helium, and its frequency response from low frequency to several MHz is measured. The current gain and the noise spectrum with the HBT result in a signal-to-noise-ratio (SNR) that is a factor of 10–100 larger than without the HBT at lower frequencies. Furthermore, the transition frequency defined by SNR = 1 has been extended by as much as a factor of 10 compared to without the HBT amplification. The power dissipated by the HBT cryogenic pre-amplifier is approximately 5 nW to 5 μW for the investigated range of operation. We found that the circuit is also operated in a single electron charge read-out configuration in the time-domain as a proof-of-principle demonstration of the amplification approach for single spin read-out.

  18. The total switch time of silicon bipolar transistors with base doping gradients or with germanium gradients in the base

    NASA Astrophysics Data System (ADS)

    Karlsteen, M.; Willander, M.

    1993-11-01

    In this paper the total switch time for a transistor in a Direct Coupled Transistor Logic (DCTL) circuit is simulated by using Laplace transformations of the Ebers-Moll equations. The influence of doping gradients and germanium gradients in the base is investigated and their relative importance and their limitations are established. In a well designed bipolar transistor only a minor enhancement of the total switch time is obtained with the use of a doping gradient in the base. However, for bipolar transistors with base thickness over 500 Å, an improperly selected doping profile could be devastating for the total switch time. For a bipolar transistor the improvement of the total switch time due to a linear germanium gradient in the base could be up to about 30% compared with an ordinary silicon bipolar transistor. Still, a too high germanium gradient forces the normal transistor current gain (α N) to grow and the total switch time is thereby increased. Further enhancement could be achieved by the use of a second degree polynomial germanium profile in the base. Also in this case, care must be taken not to enlarge the germanium gradient too much as the total switch time then starts to increase. In all cases the betterment of the base transit time that is introduced by the electric field will not be directly used to reduce the base transit time. Instead the improvement is mostly used to lower the emitter transition charging time. However, the most important parameter to control is the normal transistor current gain (α N) that has to be kept within a narrow range to keep the total switch time low.

  19. InGaP/InGaAsN/GaAs NpN double heterojunction bipolar transistor

    SciTech Connect

    Chang, P.C.; Baca, A.G.; Li, N.Y.; Xie, X.M.; Sharps, P.R.; Hou, H.Q.

    2000-01-10

    The authors have demonstrated a functional NpN double heterojunction bipolar transistor (DHBT) using InGaAsN for base layer. The InGaP/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}/GaAs DHBT has a low V{sub ON} of 0.81 V, which is 0.13 V lower than in a InGaP/GaAs HBT. The lower V{sub ON} is attributed to the smaller bandgap (E{sub g}=1.20eV) of MOCVD grown In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} base layer. GaAs is used for the collector; thus the BV{sub CEO} is 10 V, consistent with the BV{sub CEO} of InGaP/GaAs Hbts of comparable collector thickness and doping level. To alleviate the current blocking phenomenon caused by the larger {triangle}E{sub C} between InGaAsN and GaAs, a graded InGaAs layer with {delta}-doping is inserted at the base-collector junction. The improved device has a peak current gain of 7 with ideal IV characteristics.

  20. Trends in the emitter-base bias dependence of the average base transit time through abrupt heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Kumar, T.; Cahay, M.; Roenker, K.

    1996-11-01

    The average base transit time is computed using a current impulse response technique for three typical abrupt Npn heterojunction bipolar transistors as a function of the emitter-base bias, VBE. This technique is based on a hybrid model of carrier transport incorporating a quantum-mechanical analysis of carrier injection at the emitter-base junction and a Monte Carlo analysis of base transport. For typical AlGaAs/GaAs and InP/InGaAs structures, the base transit time first increases with VBE, reaches a maximum, and then decreases towards a value close to the one predicted using a semi-Maxwellian injection of carriers into the base at an energy equal to the emitter-base conduction band spike. For a typical InAlAs/InGaAs structure, the average base transit time is found to decrease with an increase in VBE. For all structures, we show that there is a correlation between the bias dependence of the average base transit time and the bias dependence of the average number of collisions per carrier (calculated for carriers transmitted across the base).

  1. High-speed electro-thermal modelling of a three-phase insulated gate bipolar transistor inverter power module

    NASA Astrophysics Data System (ADS)

    Zhou, Zhongfu; Igic, Petar

    2010-02-01

    In this article, a high-speed electro-thermal (ET) modelling strategy to predict the junction temperature of insulated gate bipolar transistor (IGBT) devices of a three-phase inverter power module is presented. The temperature-dependent power loss characteristics of IGBT and diode devices are measured and stored in lookup tables, which replace the conventional complicated physics-based compact models. An inverter is modelled as a voltage controlled voltage source, which allows the inverter-based power train simulation to be carried out in the continuous time domain with a large simulation time-step (1 ms). Using the simulated sinusoidal voltage and current components of the inverter output, the given pulse width modulation mode, the conduction time (duty ratio) and the current of the devices are extracted. Based on the lookup tables, on-times and conduction currents of devices, the average power loss over each simulation time-step is calculated, which is then fed into the inverter thermal model to predict the devices' temperatures. The advantage of the proposed model is that an accurate ET simulation of inverter for long real-time (many minutes) operation can be carried out within an acceptable computational time using a standard modern personal computer. Both simulation and experimental validation have been carried out, and an excellent agreement has been achieved between the simulation and experimental data.

  2. Effect of doping and stoichiometric profile on transport in SiGe heterojunction bipolar transistor

    NASA Astrophysics Data System (ADS)

    Halilov, S.

    2016-09-01

    Based on analytical consideration and numerical simulations, it is shown how the mutually adjusted doping and stoichiometric profile results in improved frequency response and current gain in Si1‑x Ge x -based heterojunction bipolar transistor. The closed-form expressions are derived for the dopant distribution within a certain mobility model which is parametrized in terms of the impurity concentration and stoichiometric grading on the same footing. With proper parametrization of the mobility, the method is suitable in both limits of high alloy scattering/low crystal ordering and low alloy scattering/highly ordered stoichiometrically graded structure. The work is corroborated by device simulations of a single-side HBT 30% stoichiometrically graded base, with detailed IV-curve, Gummel and AC analysis. It is shown that the distinct impurity distribution results in a reduced space-charge region, contributes to an effective electric field assisting the diffusion of the minority carriers and results in the saturation current density increased by 50%, the AC gain increased by 90%, the four-fold increase of the DC current gain, and improves the transition frequency from 274 to 358 GHz as compared to the case of the uniformly distributed acceptors. The obtained results may serve as a practical guide in design of highly-graded heterojunction bipolar transistors with efficient frequency response, high gain and enhanced power.

  3. Fabrication and high temperature characteristics of ion-implanted GaAs bipolar transistors and ring-oscillators

    NASA Technical Reports Server (NTRS)

    Doerbeck, F. H.; Yuan, H. T.; Mclevige, W. V.

    1981-01-01

    Ion implantation techniques that permit the reproducible fabrication of bipolar GaAs integrated circuits are studied. A 15 stage ring oscillator and discrete transistor were characterized between 25 and 400 C. The current gain of the transistor was found to increase slightly with temperature. The diode leakage currents increase with an activation energy of approximately 1 eV and dominate the transistor leakage current 1 sub CEO above 200 C. Present devices fail catastrophically at about 400 C because of Au-metallization.

  4. Negative differential transconductance in silicon quantum well metal-oxide-semiconductor field effect/bipolar hybrid transistors

    SciTech Connect

    Naquin, Clint; Lee, Mark; Edwards, Hal; Mathur, Guru; Chatterjee, Tathagata; Maggio, Ken

    2014-11-24

    Introducing explicit quantum transport into Si transistors in a manner amenable to industrial fabrication has proven challenging. Hybrid field-effect/bipolar Si transistors fabricated on an industrial 45 nm process line are shown to demonstrate explicit quantum transport signatures. These transistors incorporate a lateral ion implantation-defined quantum well (QW) whose potential depth is controlled by a gate voltage (V{sub G}). Quantum transport in the form of negative differential transconductance (NDTC) is observed to temperatures >200 K. The NDTC is tied to a non-monotonic dependence of bipolar current gain on V{sub G} that reduces drain-source current through the QW. These devices establish the feasibility of exploiting quantum transport to transform the performance horizons of Si devices fabricated in an industrially scalable manner.

  5. Design considerations of a MOS-bipolar Darlington structure: The vertical insulated base transistor (IBT)

    NASA Astrophysics Data System (ADS)

    Godignon, P.; Fernández, J.; Flores, D.; Hidalgo, S.; Rebollo, J.; Millán, J.; Chante, J. P.

    1996-12-01

    The analysis of a vertical insulated base transistor (MOS-bipolar Darlington power device with cellular layout) is discussed. The device operation is investigated in the framework of a schematic representation of the output characteristics and by means of 2D numerical simulation. A new design using a P --diffusion interconnecting the P-type regions is proposed to improve the device breakdown voltage. Several cellular and stripe geometries were implemented with a double metal layer technology. Experiments corroborate the simulation results pointing out that the IBT shows a low on-resistance and fast switching times. For the sake of comparison of their electrical characteristics VDMOS and IGBTs were also fabricated with the same process.

  6. Growth and Fabrication of GaN/AlGaN Heterojunction Bipolar Transistor

    SciTech Connect

    Abernathy, C.R.; Baca, A.G.; Cao, X.A.; Cho, H.; Dang, G.T.; Donovan, S.M.; Han, J.; Jung, K.B.; Pearton, S.J.; Ren, F.; Shul, R.J.; Willison, C.G.; Wilson, R.G.; Zhang, A.P.; Zhang, L

    1999-03-16

    A GaN/AlGaN heterojunction bipolar transistor structure with Mg doping in the base and Si Doping in the emitter and collector regions was grown by Metal Organic Chemical Vapor Deposition in c-axis Al(2)O(3). Secondary Ion Mass Spectrometry measurements showed no increase in the O concentration (2-3x10(18) cm(-3)) in the AlGaN emitter and fairly low levels of C (~4-5x10(17) cm (-3)) throughout the structure. Due to the non-ohmic behavior of the base contact at room temperature, the current gain of large area (~90 um diameter) devices was <3. Increasing the device operating temperature led to higher ionization fractions of the mg acceptors in the base, and current gains of ~10 were obtained at 300 degree C.

  7. InP Double Heterojunction Bipolar Transistor for broadband terahertz detection and imaging systems

    NASA Astrophysics Data System (ADS)

    Coquillat, D.; Nodjiadjim, V.; Konczykowska, A.; Dyakonova, N.; Consejo, C.; Ruffenach, S.; Teppe, F.; Riet, M.; Muraviev, A.; Gutin, A.; Shur, M.; Godin, J.; Knap, W.

    2015-10-01

    This paper presents terahertz detectors based on high performance 0.7-μm InP double heterojunction bipolar transistor (DHBT) technology and reports on the analysis of their voltage responsivity over a wide frequency range of the incoming terahertz radiation. The detectors operated without any spatial antennas to couple terahertz radiation to the device and have been characterized in the 0.25 - 3.1 THz range with the responsivities (normalized to 1 W radiant power) of 5 V/W and 200 μV/W measured at 0.35 THz and 3.11 THz, respectively. The InP DHBTs also performed as the imaging single-pixels at room temperature in the raster scanned transmission mode. A set of the sub-terahertz images of plant leaves suggest potential utility of InP DHBT detectors for terahertz imaging dedicated to non-invasive testing of plants.

  8. InGaAs/InP heterojunction bipolar transistors for ultra-low power circuit applications

    SciTech Connect

    Chang, P.C.; Baca, A.G.; Hafich, M.J.; Ashby, C.I.

    1998-08-01

    For many modern day portable electronic applications, low power high speed devices have become very desirable. Very high values of f{sub T} and f{sub MAX} have been reported with InGaAs/InP heterojunction bipolar transistors (HBTs), but only under high bias and high current level operating conditions. An InGaAs/InP ultra-lowpower HBT with f{sub MAX} greater than 10 GHz operating at less than 20 {micro}A has been reported for the first time in this work. The results are obtained on a 2.5 x 5 {micro}m{sup 2} device, corresponding to less than 150 A/cm{sup 2} of current density. These are the lowest current levels at which f{sub MAX} {ge} 10 GHz has been reported.

  9. Microwave characterization and modeling of GaAs/AlGaAs heterojunction bipolar transistors

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Romanofsky, Robert R.

    1987-01-01

    The characterization and modeling of a microwave GaAs/AlGaAs heterojunction Bipolar Transistor (HBT) are discussed. The de-embedded scattering parameters are used to derive a small signal lumped element equivalent circuit model using EEsof's Touchstone software package. Each element in the equivalent circuit model is shown to have its origin within the device. The model shows good agreement between the measured and modeled scattering parameters over a wide range of bias currents. Further, the MAG (maximum available power gain) and the h sub 21 (current gain) calculated from the measured data and those predicted by the model are also in good agreement. Consequently, the model should also be capable of predicting the f sub max and the f sub T of other HBTs.

  10. Investigation of proton irradiation effects on InP/InGaAs double heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Liu, Min; Zhang, Yuming; Lu, Hongliang; Zhang, Yimen; Zhang, Jincan; Ren, Xiaotang

    2015-07-01

    In this article, 3 MeV proton irradiation-induced degradation in InP/InGaAs double heterojunction bipolar transistors (DHBTs) is studied, the fluence up to 5 × 1012 protons/cm2, meanwhile 10 MeV proton irradiation is investigated in order to compare the differences induced by different proton energy irradiation. The devices exhibit good tolerance up to 5 × 1011 protons/cm2. The concentration of vacancies at different proton fluences can be calculated from SRIM. Being donor-like defects, the In and Ga vacancies act as compensation center while As vacancy acts as an acceptor-like defect. Adding the vacancies model into Sentaurus device simulator, simulation results match well with the trends of measured data.

  11. A high-conductivity insulated gate bipolar transistor with Schottky hole barrier contact

    NASA Astrophysics Data System (ADS)

    Mengxuan, Jiang; John, Shen Z.; Jun, Wang; Xin, Yin; Zhikang, Shuai; Jiang, Lu

    2016-02-01

    This letter proposes a high-conductivity insulated gate bipolar transistor (HC-IGBT) with Schottky contact formed on the p-base, which forms a hole barrier at the p-base side to enhance the conductivity modulation effect. TCAD simulation shows that the HC-IGBT provides a current density increase by 53% and turn-off losses decrease by 27% when compared to a conventional field-stop IGBT (FS-IGBT). Hence, the proposed IGBT exhibits superior electrical performance for high-efficiency power electronic systems. Project supported by the National High Technology Research and Development Program of China (No. 2014AA052601) and the National Natural Science Foundation of China (No. 51277060).

  12. SiGe:C Heterojunction Bipolar Transistors: From Materials Research to Chip Fabrication

    NASA Astrophysics Data System (ADS)

    Ruecker, H.; Heinemann, B.; Knoll, D.; Ehwald, K.-E.

    Incorporation of substitutional carbon ( ~10^20 cm^-3) into the SiGe region of a heterojunction bipolar transistor (HBT) strongly reduces boron diffusion during device processing. We describe the physical mechanism behind the suppression of B diffusion in C-rich Si and SiGe, and explain how the increased thermal stability of doping profiles in SiGe:C HBTs can be used to improve device performance. Manufacturability of SiGe:C HBTs with transit frequencies of 100 GHz and maximum oscillation frequencies of 130 GHz is demonstrated in a BiCMOS technology capable of fabricating integrated circuits for radio frequencies with high yield.

  13. Arsenide-antimonide hetero-junction tunnel transistors for low power logic applications

    NASA Astrophysics Data System (ADS)

    Mohata, Dheeraj Kumar

    Aggressive supply voltage (VCC) scaling of future transistors without increasing the off-state leakage while maintaining performance remains an important challenge. Hetero-junction Tunnel FETs (HTFETs) with steep switching slope and high drive current at low supply voltage (below 0.35V) have emerged as promising low VCC device option. GaAs1-ySby source and InxGa1-xAs channel form lattice matched arsenide-antimonide staggered hetero-junctions with compositionally tunable effective tunnel barrier height. Unlike homo-junction Tunnel FETs, the effective barrier height of staggered hetero-junctions can be made negligibly small while maintaining large band-gaps in the respective source, channel and drain regions, thus, enabling TFETs to achieve MOSFET like drive currents while maintaining higher on-off ratio. This dissertation focuses on experimental demonstration of mixed arsenide-antimonide hetero-junction TFETs with nano-pillar tunnel transistor architecture exhibiting MOSFET-like on-current and high on-off ratio for ultra-low power logic applications. Within this dissertation, using experimental demonstration and detailed modeling, following aspects of the n-channel hetero-junction Tunnel FETs will be discussed: a) Material selection and device design; b) Nano-pillar TFET process flow development; c) Hetero-junction TFET growth and materials characterization; and d) Hetero-junction TFET transport study. The dissertation concludes with benchmarking of the performance of arsenide-antimonide n-channel Tunnel FETs with those reported till date, and an address to the feasibility of arsenide-antimonide based complementary Tunnel FET logic for future ultra low power logic applications.

  14. Complementary GaAs junction-gated heterostructure field effect transistor technology

    SciTech Connect

    Baca, A.G.; Zolper, J.C.; Sherwin, M.E.; Robertson, P.J.; Shul, R.J.; Howard, A.J.; Rieger, D.J.; Klem, J.F.

    1994-09-01

    The first circuit results for a new GaAs complementary logic technology are presented. The technology allows for Independently optimizable p- and n- channel transistors with junction gates. Excellent loaded gate delays of 179 ps at 1.2 V and 319 ps at 0.8 V have been demonstrated at low power supply voltages. A power-delay product of 8.9 fJ was obtained at 0.8 V.

  15. Radiative recombination in GaN/InGaN heterojunction bipolar transistors

    SciTech Connect

    Kao, Tsung-Ting; Lee, Yi-Che; Kim, Hee-Jin; Ryou, Jae-Hyun; Kim, Jeomoh; Detchprohm, Theeradetch; Dupuis, Russell D.; Shen, Shyh-Chiang

    2015-12-14

    We report an electroluminescence (EL) study on npn GaN/InGaN heterojunction bipolar transistors (HBTs). Three radiative recombination paths are resolved in the HBTs, corresponding to the band-to-band transition (3.3 eV), conduction-band-to-acceptor-level transition (3.15 eV), and yellow luminescence (YL) with the emission peak at 2.2 eV. We further study possible light emission paths by operating the HBTs under different biasing conditions. The band-to-band and the conduction-band-to-acceptor-level transitions mostly arise from the intrinsic base region, while a defect-related YL band could likely originate from the quasi-neutral base region of a GaN/InGaN HBT. The I{sub B}-dependent EL intensities for these three recombination paths are discussed. The results also show the radiative emission under the forward-active transistor mode operation is more effective than that using a diode-based emitter due to the enhanced excess electron concentration in the base region as increasing the collector current increases.

  16. InAs/Si Hetero-Junction Nanotube Tunnel Transistors

    PubMed Central

    Hanna, Amir N.; Fahad, Hossain M.; Hussain, Muhammad M.

    2015-01-01

    Hetero-structure tunnel junctions in non-planar gate-all-around nanowire (GAA NW) tunnel FETs (TFETs) have shown significant enhancement in ‘ON’ state tunnel current over their all-silicon counterpart. Here we show the unique concept of nanotube TFET in a hetero-structure configuration that is capable of much higher drive current as opposed to that of GAA NW TFETs.Through the use of inner/outer core-shell gates, a single III-V hetero-structured nanotube TFET leverages physically larger tunneling area while achieving higher driver current (ION) and saving real estates by eliminating arraying requirement. Numerical simulations has shown that a 10 nm thin nanotube TFET with a 100 nm core gate has a 5×normalized output current compared to a 10 nm diameter GAA NW TFET. PMID:25923104

  17. Design considerations for integration of Horizontal Current Bipolar Transistor (HCBT) with 0.18 μm bulk CMOS technology

    NASA Astrophysics Data System (ADS)

    Koričić, Marko; Suligoj, Tomislav; Mochizuki, Hidenori; Morita, So-ichi; Shinomura, Katsumi; Imai, Hisaya

    2010-10-01

    Design issues associated with integration of Horizontal Current Bipolar Transistor (HCBT) with 0.18 μm bulk CMOS process are examined and the effects of fabrication parameters on transistor performance analyzed. HCBT is fabricated on a sidewall of a silicon hill defined by shallow trench isolation (STI). Height of the transistor is limited by the STI depth of 350 nm. Impact of vertical and horizontal dimensions on electrical performance of the transistor are analyzed by simulations with emphasis on extrinsic base design. Base current is reduced by high extrinsic base concentration and increased link-base length. Current gain is increased from 16 to 67 for transistor processed with the optimized extrinsic base profile. High-frequency performance is degraded by the collector charge sharing effect and can be improved by the larger separation between the extrinsic base and emitter, which is achieved with a small thickness of emitter polysilicon region. Misalignment tolerances of the extrinsic base implantation mask show no great impact on transistor's AC performance.

  18. Fabrication of Tunnel Junctions For Direct Detector Arrays With Single-Electron Transistor Readout Using Electron-Beam Lithography

    NASA Technical Reports Server (NTRS)

    Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Rhee, K. W.; Teufel, J.; Schoelkopf, R. J.

    2002-01-01

    This paper will describe the fabrication of small aluminum tunnel junctions for applications in astronomy. Antenna-coupled superconducting tunnel junctions with integrated single-electron transistor readout have the potential for photon-counting sensitivity at sub-millimeter wavelengths. The junctions for the detector and single-electron transistor can be made with electron-beam lithography and a standard self-aligned double-angle deposition process. However, high yield and uniformity of the junctions is required for large-format detector arrays. This paper will describe how measurement and modification of the sensitivity ratio in the resist bilayer was used to greatly improve the reliability of forming devices with uniform, sub-micron size, low-leakage junctions.

  19. InGaAsN/AlGaAs Pnp Heterojunction Bipolar Transistor

    SciTech Connect

    BACA,ALBERT G.; CHANG,PING-CHIH; HOU,H.Q.; LAROCHE,J.R.; LI,N.Y.; REN,F.; SHARPS,P.R.

    1999-11-03

    The authors have demonstrated a functional Pnp heterojunction bipolar transistor (HBT) using InGaAsN. The metalorganic vapor phase epitaxy (MOCVD) grown Al{sub 0.3}Ga{sub 0.7}As/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} HBT takes advantage of the narrower bandgap energy (E{sub g} = 1.25eV) of In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}, which is lattice matched to GaAs. Compared with the Al{sub 0.3}Ga{sub 0.7}As/GaAs material system, the Al{sub 0.3}Ga{sub 0.7}As/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} material system has a larger conduction band offset, while the valence band offset remains comparable. This characteristic band alignment is very suitable for Pnp HBT applications. The device's peak current gain is 23 and it has a turn on voltage of 0.77V, which is 0.25V lower than in a comparable Pnp Al{sub 0.3}Ga{sub 0.7}As/GaAs HBT.

  20. Heat Removal from Bipolar Transistor by Loop Heat Pipe with Nickel and Copper Porous Structures

    PubMed Central

    Smitka, Martin; Malcho, Milan

    2014-01-01

    Loop heat pipes (LHPs) are used in many branches of industry, mainly for cooling of electrical elements and systems. The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal performance of LHP, capillary wicks with high permeability and porosity and fine pore radius are expected. The aim of this work was to develop porous structures from copper and nickel powder with different grain sizes. For experiment copper powder with grain size of 50 and 100 μm and nickel powder with grain size of 10 and 25 μm were used. Analysis of these porous structures and LHP design are described in the paper. And the measurements' influences of porous structures in LHP on heat removal from the insulated gate bipolar transistor (IGBT) have been made. PMID:24959622

  1. Solution-processible organic-inorganic hybrid bipolar field-effect transistors

    NASA Astrophysics Data System (ADS)

    Chae, Gil Jo; Kim, Kang Dae; Cho, Shinuk; Walker, Bright; Seo, Jung Hwa

    2016-04-01

    Organic-inorganic hybrid bipolar field-effect transistors (HBFETs) comprising a layer of p-type organic poly(3-hexylthiophene) (P3HT) separated from a parallel layer of n-type inorganic zinc oxide (ZnO) were demonstrated by solution processing. In order to achieve balanced hole and electron mobilities, we initially optimized the hole-transporting P3HT channel by the addition of the polar non-solvent acetonitrile (AN) to P3HT solutions in chloroform, which induced a selfassembled nano-fibril morphology and an enhancement of hole mobilities. For the electron channel, a wet-chemically-prepared ZnO layer was optimized by thermal annealing. Unipolar P3HT FET with 5% AN exhibited the highest hole mobility of 7.20 × 10-2 cm2V-1s-1 while the highest electron mobility (3.64 × 10-2 cm2V-1s-1) was observed in unipolar ZnO FETs annealed at 200°C. The organic-inorganic HBFETs consisting of the P3HT layer with 5% AN and ZnO annealed at 200°C exhibited well-balanced hole and electron mobilities of 1.94 × 10-2 cm2V-1s-1 and 1.98 × 10-2 cm2V-1s-1, respectively.

  2. Heat removal from bipolar transistor by loop heat pipe with nickel and copper porous structures.

    PubMed

    Nemec, Patrik; Smitka, Martin; Malcho, Milan

    2014-01-01

    Loop heat pipes (LHPs) are used in many branches of industry, mainly for cooling of electrical elements and systems. The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal performance of LHP, capillary wicks with high permeability and porosity and fine pore radius are expected. The aim of this work was to develop porous structures from copper and nickel powder with different grain sizes. For experiment copper powder with grain size of 50 and 100 μm and nickel powder with grain size of 10 and 25 μm were used. Analysis of these porous structures and LHP design are described in the paper. And the measurements' influences of porous structures in LHP on heat removal from the insulated gate bipolar transistor (IGBT) have been made. PMID:24959622

  3. A new model for four-terminal junction field-effect transistors

    NASA Astrophysics Data System (ADS)

    Ding, Hao; Liou, Juin J.; Green, Keith; Cirba, Claude R.

    2006-03-01

    This paper presents a compact and semi-empirical model for a four-terminal (independent top and bottom gates) junction field-effect transistor (JFET). The model describes the steady-state characteristics for all bias conditions with a unified equation. Moreover, the model provides a high degree of accuracy and continuity for the different operation regions, a critical factor for robust analog circuit simulations. Capacitance modeling is also included to describe the JFET small-signal behavior. The model has been implemented in Cadence framework via Verilog-A and compared with data measured from JFETs used at Texas Instruments.

  4. Giant amplification of tunnel magnetoresistance in a molecular junction: Molecular spin-valve transistor

    SciTech Connect

    Dhungana, Kamal B.; Pati, Ranjit

    2014-04-21

    Amplification of tunnel magnetoresistance by gate field in a molecular junction is the most important requirement for the development of a molecular spin valve transistor. Herein, we predict a giant amplification of tunnel magnetoresistance in a single molecular spin valve junction, which consists of Ru-bis-terpyridine molecule as a spacer between two ferromagnetic nickel contacts. Based on the first-principles quantum transport approach, we show that a modest change in the gate field that is experimentally accessible can lead to a substantial amplification (320%) of tunnel magnetoresistance. The origin of such large amplification is attributed to the spin dependent modification of orbitals at the molecule-lead interface and the resultant Stark effect induced shift in channel position with respect to the Fermi energy.

  5. Focused Laser Induced Spatially Controllable p-n junction in Graphene Field-Effect Transistor

    NASA Astrophysics Data System (ADS)

    Kim, Young; Bae, Myung-Ho; Shu, Jung-Tak; Kim, Young; Ahn, Joung; Chun, Seung-Hyun; Park, Yun

    2013-03-01

    Tunable local doping on graphene is an important issue for future graphene-based electronics. Here we investigate a local doping effect by a focused laser irradiation and demonstrate a spatially controllable p-n junction in graphene field-effect transistor. Scanning photocurrent microscopy with varying back-gate voltages reveals the local charge trap in gate oxide near the laser-irradiated region. This is manifested by itself as double peaks in resistance as a function of gate voltage in graphene device, where the region between the double peaks corresponds to the p-n junction. Irradiation of a focused laser on graphene device suggests a new pave to spatially control the doping level, position and size of doped segment on graphene channel in a nondestructive way without high electrical bias, local gate electrode and chemical process. Korea Research Institute of Standards and Science

  6. Refined Transistor Model For Simulation Of SEU

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Benumof, Reuben

    1988-01-01

    Equivalent base resistance added. Theoretical study develops equations for parameters of Gummel-Poon model of bipolar junction transistor: includes saturation current, amplification factors, charging times, knee currents, capacitances, and resistances. Portion of study concerned with base region goes beyond Gummel-Poon analysis to provide more complete understanding of transistor behavior. Extended theory useful in simulation of single-event upset (SEU) caused in logic circuits by cosmic rays or other ionizing radiation.

  7. Ultra-High Voltage 4H-SiC Bi-Directional Insulated Gate Bipolar Transistors

    NASA Astrophysics Data System (ADS)

    Chowdhury, Sauvik

    4H- Silicon Carbide (4H-SiC) is an attractive material for power semiconductor devices due to its large bandgap, high critical electric field and high thermal conductivity compared to Silicon (Si). For ultra-high voltage applications (BV > 10 kV), 4H-SiC Insulated Gate Bipolar Transistors (IGBTs) are favored over unipolar transistors due to lower conduction losses. With improvements in SiC materials and processing technology, promising results have been demonstrated in the area of conventional unidirectional 4H-SiC IGBTs, with breakdown voltage ratings up to 27 kV. This research presents the experimental demonstration of the world's first high voltage bi-directional power transistors in 4H-SiC. Traditionally, four (two IGBTs and two diodes) or two (two reverse blocking IGBTs) semiconductor devices are necessary to yield a bidirectional switch. With a monolithically integrated bidirectional switch as presented here, the number of semiconductor devices is reduced to only one, which results in increased reliability and reduced cost of the overall system. Additionally, by using the unique dual gate operation of BD-IGBTs, switching losses can be reduced to a small fraction of that in conventional IGBTs, resulting in increased efficiency. First, the performance limits of SiC IGBTs are calculated by using analytical methods. The performance benefits of SiC IGBTs over SiC unipolar devices and Si IGBTs are quantified. Numerical simulations are used to optimize the unit cell and edge termination structures for a 15 kV SiC BD-IGBT. The effect of different device parameters on BD-IGBT static and switching performance are quantified. Second, the process technology necessary for the fabrication of high voltage SiC BD-IGBTs is optimized. The effect of different process steps on parameters such as breakdown voltage, carrier lifetime, gate oxide reliability, SiO2-SiC interface charge density is quantified. A carrier lifetime enhancement process has been optimized for lightly doped

  8. Gallium nitride junction field effect transistors for high-temperature operation

    SciTech Connect

    Zolper, J.C.; Shul, R.J.; Baca, A.G.; Hietala, V.M.; Pearton, S.J.; Stall, R.A.; Wilson, R.G.

    1996-06-01

    GaN is an attractive material for use in high-temperature or high-power electronic devices due to its high bandgap (3.39 eV), high breakdown field ({approximately}5 {times} 10{sup 6} V/cm), high saturation drift velocity (2.7 {times} 10{sup 7} cm/s), and chemical inertness. To this end, Metal Semiconductor FETs (MESFETs), High Electron Mobility Transistors (HEMTs), Heterostructure FETs (HFETs), and Metal Insulator Semiconductor FETs (MISFETs) have all been reported based on epitaxial AlN/GaN structures (Khan 1993a,b; Binari 1994 and 1995). GaN Junction Field Effect Transistors (JFETs), however, had not been reported until recently (Zolper 1996b). JFETs are attractive for high-temperature operation due to the inherently higher thermal stability of the p/n junction gate of a JFET as compared to the Schottky barrier gate of a MESFET or HFET. In this paper the authors present the first results for elevated temperature performance of a GaN JFET. Although the forward gate properties are well behaved at higher temperatures, the reverse characteristics show increased leakage at elevated temperature. However, the increased date leakage alone does not explain the observed increase in drain current with temperature. Therefore, they believe this first device is limited by temperature activated substrate conduction.

  9. Characteristics of Novel InGaAsN Double Heterojunction Bipolar Transistors

    SciTech Connect

    LI,N.Y.; CHANG,PING-CHIH; BACA,ALBERT G.; LAROCHE,J.R.; REN,F.; ARMOUR,E.; SHARPS,P.R.; HOU,H.Q.

    2000-08-01

    The authors demonstrate, for the first time, both functional Pnp AlGaAs/InGaAsN/GaAs (Pnp InGaAsN) and Npn InGaP/InGaAsN/GaAs (Npn InGaAsN) double heterojunction bipolar transistors (DHBTs) using a 1.2 eV In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} as the base layer for low-power electronic applications. The Pnp InGaAsN DHBT has a peak current gain ({beta}) of 25 and a low turn-on voltage (V{sub ON}) of 0.79 V. This low V{sub ON} is {approximately} 0.25 V lower than in a comparable Pnp AlGAAs/GaAs HBT. For the Npn InGaAsN DHBT, it has a low V{sub ON} of 0.81 V, which is 0.13 V lower than in an InGaP/GaAs HBT. A peak {beta} of 7 with nearly ideal I-V characteristics has been demonstrated. Since GaAs is used as the collector of both Npn and Pnp InGaAsN DHBTs, the emitter-collector breakdown voltage (BV{sub CEO}) are 10 and 12 V, respectively, consistent with the BV{sub CEO} of Npn InGaP/GaAs and Pnp AlGaAs/GaAs HBTs of comparable collector thickness and doping level. All these results demonstrate the potential of InGaAsN DHBTs as an alternative for application in low-power electronics.

  10. InGaAsN/AlGaAs P-n-p heterojunction bipolar transistor

    SciTech Connect

    Chang, P. C.; Baca, A. G.; Li, N. Y.; Sharps, P. R.; Hou, H. Q.; Laroche, J. R.; Ren, F.

    2000-05-08

    We have demonstrated a functional P-n-p heterojunction bipolar transistor (HBT) using InGaAsN. The metalorganic-vapor-phase-epitaxy-grown Al{sub 0.3}Ga{sub 0.7}As/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} HBT takes advantage of the narrower band gap energy (E{sub g}=1.2 eV) of In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}, which is lattice matched to GaAs. Compared with the Al{sub 0.3}Ga{sub 0.7}As/GaAs material system, the Al{sub 0.3}Ga{sub 0.7}As/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} material system has a larger conduction-band offset, while the valence-band offset remains comparable. This characteristic band alignment is very suitable for P-n-p HBT applications. The device's peak current gain is 23, and it has a turn-on voltage of 0.77 V, which is 0.25 V lower than in a comparable P-n-p Al{sub 0.3}Ga{sub 0.7}As/GaAs HBT. (c) 2000 American Institute of Physics.

  11. Copper-Based OHMIC Contracts for the Si/SiGe Heterojunction Bipolar Transistor Structure

    NASA Technical Reports Server (NTRS)

    Das, Kalyan; Hall, Harvey

    1999-01-01

    Silicon based heterojunction bipolar transistors (HBT) with SiGe base are potentially important devices for high-speed and high-frequency microelectronics. These devices are particularly attractive as they can be fabricated using standard Si processing technology. However, in order to realize the full potential of devices fabricated in this material system, it is essential to be able to form low resistance ohmic contacts using low thermal budget process steps and have full compatibility with VLSI/ULSI processing. Therefore, a study was conducted in order to better understand the contact formation and to develop optimized low resistance contacts to layers with doping densities corresponding to the p-type SiGe base and n-type Si emitter regions of the HBTS. These as-grown doped layers were implanted with BF(sub 2) up to 1 X 10(exp 16)/CM(exp 2) and As up to 5 x 10(exp 15)/CM2, both at 30 keV for the p-type SiGe base and n-type Si emitter layers, respectively, in order to produce a low sheet resistance surface layer. Standard transfer length method (TLM) contact pads on both p and n type layers were deposited using an e-beam evaporated trilayer structure of Ti/CufTi/Al (25)A/1500A/250A/1000A). The TLM pads were delineated by a photoresist lift-off procedure. These contacts in the as-deposited state were ohmic, with specific contact resistances for the highest implant doses of the order of 10(exp -7) ohm-CM2 and lower.

  12. Electronic Transport and Quantum Hall Effect in Bipolar Graphene p-n-p Junctions

    NASA Astrophysics Data System (ADS)

    Özyilmaz, Barbaros; Jarillo-Herrero, Pablo; Efetov, Dmitri; Abanin, Dmitry A.; Levitov, Leonid S.; Kim, Philip

    2007-10-01

    We have developed a device fabrication process to pattern graphene into nanostructures of arbitrary shape and control their electronic properties using local electrostatic gates. Electronic transport measurements have been used to characterize locally gated bipolar graphene p-n-p junctions. We observe a series of fractional quantum Hall conductance plateaus at high magnetic fields as the local charge density is varied in the p and n regions. These fractional plateaus, originating from chiral edge states equilibration at the p-n interfaces, exhibit sensitivity to interedge backscattering which is found to be strong for some of the plateaus and much weaker for other plateaus. We use this effect to explore the role of backscattering and estimate disorder strength in our graphene devices.

  13. Single-Shot Charge Readout Using a Cryogenic Heterojunction Bipolar Transistor Preamplifier Inline with a Silicon Single Electron Transistor at Millikelvin Temperatures

    NASA Astrophysics Data System (ADS)

    Curry, Matthew; England, Troy; Wendt, Joel; Pluym, Tammy; Lilly, Michael; Carr, Stephen; Carroll, Malcolm

    Single-shot readout is a requirement for many implementations of quantum information processing. The single-shot readout fidelity is dependent on the signal-to-noise-ratio (SNR) and bandwidth of the readout detection technique. Several different approaches are being pursued to enhance read-out including RF-reflectometry, RF-transmission, parametric amplification, and transistor-based cryogenic preamplification. The transistor-based cryogenic preamplifier is attractive in part because of the reduced experimental complexity compared with the RF techniques. Here we present single-shot charge readout using a cryogenic Heterojunction-Bipolar-Transistor (HBT) inline with a silicon SET charge-sensor at millikelvin temperatures. For the relevant range of HBT DC-biasing, the current gain is 100 to 2000 and the power dissipation is 50 nW to 5 μW, with the microfabricated SET and discrete HBT in an integrated package mounted to the mixing chamber stage of a dilution refrigerator. We experimentally demonstrate a SNR of up to 10 with a bandwidth of 1 MHz, corresponding to a single-shot time-domain charge-sensitivity of approximately 10-4 e / √Hz. This measured charge-sensitivity is comparable to the values reported using the RF techniques. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  14. Impact ionization in the base of a hot-electron AlSb/InAs bipolar transistor

    NASA Technical Reports Server (NTRS)

    Vengurlekar, Arvind S.; Capasso, Federico; Chiu, T. Heng

    1990-01-01

    The operation of a new AlSb/InAs heterojunction bipolar transistor is studied. The electrons are injected into a p-InAs base across the AlSb/InAs heterojunction. The conduction-band discontinuity at this heterojunction is sufficiently large so that energy of the electrons injected into InAs exceeds the threshold for generating electron-hole pairs by impact ionization. The observed incremental common base current at zero collector-base bias decreases and becomes negative as the emitter current is increased, thus providing direct evidence for impact ionization entirely by band-edge discontinuities.

  15. Modeling and Simulation of - and Silicon Germanium-Base Bipolar Transistors Operating at a Wide Range of Temperatures.

    NASA Astrophysics Data System (ADS)

    Shaheed, M. Reaz

    1995-01-01

    Higher speed at lower cost and at low power consumption is a driving force for today's semiconductor technology. Despite a substantial effort toward achieving this goal via alternative technologies such as III-V compounds, silicon technology still dominates mainstream electronics. Progress in silicon technology will continue for some time with continual scaling of device geometry. However, there are foreseeable limits on achievable device performance, reliability and scaling for room temperature technologies. Thus, reduced temperature operation is commonly viewed as a means for continuing the progress towards higher performance. Although silicon CMOS will be the first candidate for low temperature applications, bipolar devices will be used in a hybrid fashion, as line drivers or in limited critical path elements. Silicon -germanium-base bipolar transistors look especially attractive for low-temperature bipolar applications. At low temperatures, various new physical phenomena become important in determining device behavior. Carrier freeze-out effects which are negligible at room temperature, become of crucial importance for analyzing the low temperature device characteristics. The conventional Pearson-Bardeen model of activation energy, used for calculation of carrier freeze-out, is based on an incomplete picture of the physics that takes place and hence, leads to inaccurate results at low temperatures. Plasma -induced bandgap narrowing becomes more pronounced in device characteristics at low temperatures. Even with modern numerical simulators, this effect is not well modeled or simulated. In this dissertation, improved models for such physical phenomena are presented. For accurate simulation of carrier freeze-out, the Pearson-Bardeen model has been extended to include the temperature dependence of the activation energy. The extraction of the model is based on the rigorous, first-principle theoretical calculations available in the literature. The new model is shown

  16. Theoretical results on the tandem junction solar cell based on its Ebers-Moll transistor model

    NASA Technical Reports Server (NTRS)

    Goradia, C.; Vaughn, J.; Baraona, C. R.

    1980-01-01

    A one-dimensional theoretical model of the tandem junction solar cell (TJC) with base resistivity greater than about 1 ohm-cm and under low level injection has been derived. This model extends a previously published conceptual model which treats the TJC as an npn transistor. The model gives theoretical expressions for each of the Ebers-Moll type currents of the illuminated TJC and allows for the calculation of the spectral response, I(sc), V(oc), FF and eta under variation of one or more of the geometrical and material parameters and 1MeV electron fluence. Results of computer calculations based on this model are presented and discussed. These results indicate that for space applications, both a high beginning of life efficiency, greater than 15% AM0, and a high radiation tolerance can be achieved only with thin (less than 50 microns) TJC's with high base resistivity (greater than 10 ohm-cm).

  17. Impact of gate workfunction in junctionless versus junction SOI n-MOSFET transistor

    NASA Astrophysics Data System (ADS)

    Huda, A. R. N.; Arshad, M. K. Md.; Othman, Noraini; Voon, C. H.; Liu, Wei-Wen; Hashim, U.; Lee, H. Cheun; Adelyn, P. Y. P.; Kahar, S. M.

    2016-07-01

    In this paper, the effect of gate workfunction variation on DC characteristics in 100 nm gate length silicon-on-insulator (SOI) junctionless (JL) and junction transistors has been investigated by using numerical simulations. The digital figure-of-merits characteristics such as threshold voltage (VTH), on/off-current ratio, subthreshold voltage, and drain-induced-barrier-lowering are the main parameters that have been investigated. The rate of change in VTH with the respect to gate workfunction for both JLT and JT devices was almost same. Besides that, it shows the designated JLT device is achieving full-depletion at higher gate workfunction of more than 5.0 eV whereas the designated JT device is more wider range, ranging from low, mid-gap or high workfunction.

  18. Fully transparent organic transistors with junction-free metallic network electrodes

    SciTech Connect

    Pei, Ke; Wang, Zongrong; Ren, Xiaochen; Zhang, Zhichao; Peng, Boyu; Chan, Paddy K. L.

    2015-07-20

    We utilize highly transparent, junction-free metal network electrodes to fabricate fully transparent organic field effect transistors (OFETs). The patterned transparent Ag networks are developed by polymer crack template with adjustable line width and density. Sheet resistance of the network is 6.8 Ω/sq and optical transparency in the whole visible range is higher than 80%. The bottom contact OFETs with DNTT active layer and parylene-C dielectric insulator show a maximum field-effect mobility of 0.13 cm{sup 2}/V s (average mobility is 0.12 cm{sup 2}/V s) and on/off ratio is higher than 10{sup 7}. The current OFETs show great potential for applications in the next generation of transparent and flexible electronics.

  19. Large-Signal Characterization and Modeling of the Heterojunction Bipolar Transistor

    NASA Astrophysics Data System (ADS)

    Teeter, Douglas Andrew

    1992-01-01

    Rapid improvements in Heterojunction Bipolar Transistor (HBT) device performance have made power applications in the millimeter wave regime possible. Improved large-signal modeling and characterization techniques are required for designing circuits at these frequencies. Several large-signal modeling approaches are investigated in this thesis. The most detailed model involves numerically solving moments of the Boltzmann Transport Equation. Velocity overshoot and energy relaxation effects are included in this model. After a detailed description of the numerical techniques is given, the model is used to investigate HBT operation under large-signal steady state RF conditions. Internal device carrier concentrations, electric fields, electron temperature, and electron velocity are determined at various stages during the RF cycle. While the model is a valuable tool for studying the internal device physics, its use in circuit design applications is limited due to the computer time required. The fully numerical model is then used to investigate several simpler large-signal HBT models. It is found that the commonly used Gummel-Poon model exhibits poor agreement with numerical and experimental data at millimeter wave frequencies due to neglect of transit time delays. A modified Ebers-Moll model is described which overcomes this problem by implementing the transit time delay in the frequency domain. Two large-signal measurement systems covering 8 to 35 GHz were built to compare simulated results with experimental data. A commercial tuner system was used to make measurements from 8 to 16 GHz. However, to measure beyond 26 GHz, an active loadpull system was designed and constructed to circumvent problems created by component losses. Details of this measurement system, its accuracy, and error correction techniques are given. Good agreement between measured and modeled output power, gain compression, and efficiency is obtained using the modified Ebers-Moll model over a wide range

  20. Optical orientation in bipolar spintronic devices

    NASA Astrophysics Data System (ADS)

    Fabian, Jaroslav; Žutić, Igor

    2008-11-01

    Optical orientation is a highly efficient tool for the generation of nonequilibrium spin polarization in semiconductors. Combined with spin-polarized transport it offers new functionalities for conventional electronic devices, such as pn junction bipolar diodes or transistors. In nominally nonmagnetic junctions optical orientation can provide a source for spin capacitance—the bias-dependent nonequilibrium spin accumulation—or for spin-polarized current in bipolar spin-polarized solar cells. In magnetic junctions, the nonequilibrium spin polarization generated by spin orientation in the proximity of an equilibrium magnetization gives rise to the spin-voltaic effect (a realization of the Silsbee-Johnson coupling), enabling efficient control of electrical properties such as the I-V characteristics of the junctions by magnetic and optical fields. This paper reviews the main results of investigations of spin-polarized and magnetic pn junctions, from spin capacitance to the spin-voltaic effect.

  1. Comparison of total dose effects on SiGe heterojunction bipolar transistors induced by different swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Sun, Ya-Bin; Fu, Jun; Xu, Jun; Wang, Yu-Dong; Zhou, Wei; Zhang, Wei; Cui, Jie; Li, Gao-Qing; Liu, Zhi-Hong

    2014-11-01

    The degradations in NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were fully studied in this work, by means of 25-MeV Si, 10-MeV Cl, 20-MeV Br, and 10-MeV Br ion irradiation, respectively. Electrical parameters such as the base current (IB), current gain (β), neutral base recombination (NBR), and Early voltage (VA) were investigated and used to evaluate the tolerance to heavy ion irradiation. Experimental results demonstrate that device degradations are indeed radiation-source-dependent, and the larger the ion nuclear energy loss is, the more the displacement damages are, and thereby the more serious the performance degradation is. The maximum degradation was observed in the transistors irradiated by 10-MeV Br. For 20-MeV and 10-MeV Br ion irradiation, an unexpected degradation in IC was observed and Early voltage decreased with increasing ion fluence, and NBR appeared to slow down at high ion fluence. The degradations in SiGe HBTs were mainly attributed to the displacement damages created by heavy ion irradiation in the transistors. The underlying physical mechanisms are analyzed and investigated in detail.

  2. Compact Modeling of Floating-Base Effect in Injection-Enhanced Insulated-Gate Bipolar Transistor Based on Potential Modification by Accumulated Charge

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takao; Miyake, Masataka; Miura-Mattausch, Mitiko

    2013-04-01

    We have developed a compact model of the injection-enhanced insulated-gate bipolar transistor (IGBT) applicable for circuit optimization. The main development is modeling the hole accumulation in the floating-base region. It is demonstrated that the observed negative gate capacitance is well reproduced with the developed model.

  3. Design, fabrication, and analysis of p-channel arsenide/antimonide hetero-junction tunnel transistors

    SciTech Connect

    Rajamohanan, Bijesh Mohata, Dheeraj; Hollander, Matthew; Datta, Suman; Zhu, Yan; Hudait, Mantu; Jiang, Zhengping; Klimeck, Gerhard

    2014-01-28

    In this paper, we demonstrate InAs/GaSb hetero-junction (hetJ) and GaSb homo-junction (homJ) p-channel tunneling field effect transistors (pTFET) employing a low temperature atomic layer deposited high-κ gate dielectric. HetJ pTFET exhibited drive current of 35 μA/μm in comparison to homJ pTFET, which exhibited drive current of 0.3 μA/μm at V{sub DS} = −0.5 V under DC biasing conditions. Additionally, with pulsing of 1 μs gate voltage, hetJ pTFET exhibited enhanced drive current of 85 μA/μm at V{sub DS} = −0.5 V, which is the highest reported in the category of III-V pTFET. Detailed device characterization was performed through analysis of the capacitance-voltage characteristics, pulsed current-voltage characteristics, and x-ray diffraction studies.

  4. Programmable Schottky Junctions Based on Ferroelectric Gated MoS2 Transistors

    NASA Astrophysics Data System (ADS)

    Xiao, Zhiyong; Song, Jingfeng; Drcharme, Stephen; Hong, Xia

    We report a programmable Schottky junction based on MoS2 field effect transistors with a SiO2 back gate and a ferroelectric copolymer poly(vinylidene-fluoride-trifluorethylene) (PVDF) top gate. We fabricated mechanically exfoliated single layer MoS2 flakes into two point devices via e-beam lithography, and deposited on the top of the devices ~20 nm PVDF thin films. The polarization of the PVDF layer is controlled locally by conducting atomic force microscopy. The devices exhibit linear ID-VD characteristics when the ferroelectric gate is uniformly polarized in one direction. We then polarized the gate into two domains with opposite polarization directions, and observed that the ID-VD characteristics of the MoS2 channel can be modulated between linear and rectified behaviors depending on the back gate voltage. The nonlinear ID-VD relation emerges when half of the channel is in the semiconductor phase while the other half is in the metallic phase, and it can be well described by the thermionic emission model with a Schottky barrier of ~0.5 eV. The Schottky junction can be erased by re-write the entire channel in the uniform polarization state. Our study facilitates the development of programmable, multifunctional nanoelectronics based on layered 2D TMDs..

  5. Forward-bias tunneling - A limitation to bipolar device scaling

    NASA Technical Reports Server (NTRS)

    Del Alamo, Jesus A.; Swanson, Richard M.

    1986-01-01

    Forward-bias tunneling is observed in heavily doped p-n junctions of bipolar transistors. A simple phenomenological model suitable to incorporation in device codes is developed. The model identifies as key parameters the space-charge-region (SCR) thickness at zero bias and the reduced doping level at its edges which can both be obtained from CV characteristics. This tunneling mechanism may limit the maximum gain achievable from scaled bipolar devices.

  6. Analysis of high-voltage metal–oxide–semiconductor transistors with gradual junction in the drift region

    NASA Astrophysics Data System (ADS)

    Chen, Jone F.; Ai, Teng-Jen; Tsai, Yan-Lin; Hsu, Hao-Tang; Chen, Chih-Yuan; Hwang, Hann-Ping

    2016-08-01

    The device characteristics and hot-carrier-induced degradation of high-voltage n-type metal–oxide–semiconductor transistors with traditional and gradual junctions in the drift region are studied in this work. The gradual junction used in this study is realized by self-aligned N‑ implantation through dual thicknesses of screen oxide during N‑ drift implantation. Compared with traditional devices, devices with gradual junctions have improved off-state breakdown voltage (V BD) without sacrificing on-state driving current and hot-carrier-induced degradation. More improvement in V BD is observed if the dimensions of the device are larger. The mechanism responsible for V BD improvement in devices with gradual junctions is also investigated by using technology computer-aided-design simulations.

  7. Antenna-Coupled Superconducting Tunnel Junctions with Single-Electron Transistor Readout for Detection of Sub-mm Radiation

    NASA Technical Reports Server (NTRS)

    Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Wollack, E. J.; Schoelkopf, R. J.; Teufel, J.; Krebs, Carolyn (Technical Monitor)

    2002-01-01

    Antenna-coupled superconducting tunnel junction detectors have the potential for photon-counting sensitivity at sub-mm wavelengths. The device consists of an antenna structure to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure currents through tunnel junction contacts to the absorber volume. We will describe optimization of device parameters, and recent results on fabrication techniques for producing devices with high yield for detector arrays. We will also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

  8. All-optical transistors and logic gates using a parity-time-symmetric Y-junction: Design and simulation

    SciTech Connect

    Ding, Shulin; Wang, Guo Ping

    2015-09-28

    Classical nonlinear or quantum all-optical transistors are dependent on the value of input signal intensity or need extra co-propagating beams. In this paper, we present a kind of all-optical transistors constructed with parity-time (PT)-symmetric Y-junctions, which perform independently on the value of signal intensity in an unsaturated gain case and can also work after introducing saturated gain. Further, we show that control signal can switch the device from amplification of peaks in time to transformation of peaks to amplified troughs. By using these PT-symmetric Y-junctions with currently available materials and technologies, we can implement interesting logic functions such as NOT and XOR (exclusive OR) gates, implying potential applications of such structures in designing optical logic gates, optical switches, and signal transformations or amplifications.

  9. The Aluminum-Free P-n-P InGaAsN Double Heterojunction Bipolar Transistors

    SciTech Connect

    CHANG,PING-CHIH; LI,N.Y.; BACA,ALBERT G.; MONIER,C.; LAROCHE,J.R.; HOU,H.Q.; REN,F.; PEARTON,S.J.

    2000-08-01

    The authors have demonstrated an aluminum-free P-n-P GaAs/InGaAsN/GaAs double heterojunction bipolar transistor (DHBT). The device has a low turn-on voltage (V{sub ON}) that is 0.27 V lower than in a comparable P-n-p AlGaAs/GaAs HBT. The device shows near-ideal D. C. characteristics with a current gain ({beta}) greater than 45. The high-speed performance of the device are comparable to a similar P-n-p AlGaAs/GaAs HBT, with f{sub T} and f{sub MAX} values of 12 GHz and 10 GHz, respectively. This device is very suitable for low-power complementary HBT circuit applications, while the aluminum-free emitter structure eliminates issues typically associated with AlGaAs.

  10. Electrical stress-induced instability of amorphous indium-gallium-zinc oxide thin-film transistors under bipolar ac stress

    SciTech Connect

    Lee, Sangwon; Jeon, Kichan; Park, Jun-Hyun; Kim, Sungchul; Kong, Dongsik; Kim, Dong Myong; Kim, Dae Hwan; Kim, Sangwook; Kim, Sunil; Hur, Jihyun; Park, Jae Chul; Song, Ihun; Kim, Chang Jung; Park, Youngsoo; Jung, U-In

    2009-09-28

    Bipolar ac stress-induced instability of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors is comparatively investigated with that under a positive dc gate bias stress. While the positive dc gate bias stress-induced threshold voltage shift ({delta}V{sub T}) is caused by the charge trapping into the interface/gate dielectric as reported in previous works, the dominant mechanism of the ac stress-induced {delta}V{sub T} is observed to be due to the increase in the acceptorlike deep states of the density of states (DOS) in the a-IGZO active layer. Furthermore, it is found that the variation of deep states in the DOS makes a parallel shift in the I{sub DS}-V{sub GS} curve with an insignificant change in the subthreshold slope, as well as the deformation of the C{sub G}-V{sub G} curves.

  11. Physical modeling based on hydrodynamic simulation for the design of InGaAs/InP double heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Ge, Ji; Liu, Hong-Gang; Su, Yong-Bo; Cao, Yu-Xiong; Jin, Zhi

    2012-05-01

    A physical model for scaling and optimizing InGaAs/InP double heterojunction bipolar transistors (DHBTs) based on hydrodynamic simulation is developed. The model is based on the hydrodynamic equation, which can accurately describe non-equilibrium conditions such as quasi-ballistic transport in the thin base and the velocity overshoot effect in the depleted collector. In addition, the model accounts for several physical effects such as bandgap narrowing, variable effective mass, and doping-dependent mobility at high fields. Good agreement between the measured and simulated values of cutoff frequency, ft, and maximum oscillation frequency, fmax, are achieved for lateral and vertical device scalings. It is shown that the model in this paper is appropriate for downscaling and designing InGaAs/InP DHBTs.

  12. Effect of composite collector design on the breakdown behavior of InGaP/GaAs double heterojunction bipolar transistor

    NASA Astrophysics Data System (ADS)

    Lew, K. L.; Yoon, S. F.

    2003-01-01

    A series of experiments and calculations has been carried out to study the effect of different composite collector designs on InGaP/GaAs/InGaP double heterojunction bipolar transistor breakdown characteristics. A comparison between uncorrected and dead-space corrected models was carried out, and it was found that the dead-space effect is dominant for collector thickness below 300 nm. However, this effect can be neglected for collector thickness larger than 500 nm. The role of lightly doped GaAs (n--GaAs) and heavily doped InGaP (N+-InGaP) spacer layers is discussed systematically to establish a criterion for designing the composite collector structure. The experimental and theoretical results show that it is necessary to keep the sum of n--GaAs and N+-InGaP spacer layer thickness below 50 nm to avoid significant degradation of the device breakdown characteristics.

  13. Low-temperature characteristics of the current gain of GaN/InGaN double-heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Nishikawa, Atsushi; Kumakura, Kazuhide; Kasu, Makoto; Makimoto, Toshiki

    2009-05-01

    We investigated the temperature dependence of the current gain of npn-type GaN/InGaN double-heterojunction bipolar transistors (DHBTs) in the low-temperature region. The current gain increased with decrease in device temperature due to the reduction of the recombination current in the p-type base layer. The current gain reached as high as 5000 at 40 K, which is the highest among nitride-based HBTs. For conventional HBTs made of InP or GaAs, the current gain decreased with decreasing device temperature. However, no reduction of the current gain was observed in this study, suggesting that the minority carrier mobility in the p-type InGaN base layer has negative temperature dependence, presumably because the ionized impurity scattering is relatively unaffected owing to the carrier freezeout and the high activation energy of Mg in the p-InGaN base layer.

  14. Influence of the external component on the damage of the bipolar transistor induced by the electromagnetic pulse

    NASA Astrophysics Data System (ADS)

    Xiaowen, Xi; Changchun, Chai; Xingrong, Ren; Yintang, Yang; Zhenyang, Ma; Jing, Wang

    2010-07-01

    A study on the influence of the external resistor and the external voltage source during the injection of the electromagnetic pulse (EMP) into the bipolar transistor (BJT) is carried out. Research shows that the increase of the external resistor Rb at base makes the burnout time of the device decrease slightly, the increase of the external voltage source Vbe at base can aid the damage of the device when the magnitude of the injecting voltage is relatively low and has little influence when the magnitude is sufficiently high causing the device appearing the PIN structure damage, and the increase of the external resistor Re can remarkably reduce the voltage drops added to the device and improve the durability of the device. In the final analysis, the effect of the external circuit component on the BJT damage is the influence on the condition which makes the device appear current-mode second breakdown.

  15. SEMICONDUCTOR DEVICES: EMP injection damage effects of a bipolar transistor and its relationship between the injecting voltage and energy

    NASA Astrophysics Data System (ADS)

    Xiaowen, Xi; Changchun, Chai; Xingrong, Ren; Yintang, Yang; Bing, Zhang; Xiao, Hong

    2010-04-01

    The response of a bipolar transistor (BJT) under a square-wave electromagnetic pulse (EMP) with different injecting voltages is investigated. Adopting the curve fitting method, the relationship between the burnout time, the damage energy and the injecting voltage is obtained. Research shows that the damage energy is not a constant value, but changes with the injecting voltage level. By use of the device simulator Medici, the internal behavior of the burned device is analyzed. Simulation results indicate that the variation of the damage energy with injecting voltage is caused by the distribution change of hot spot position under different injection levels. Therefore, the traditional way to evaluate the trade-off between the burnout time and the injecting voltage is not comprehensive due to the variation of the damage energy.

  16. Degradation of dc characteristics of InGaAs/InP single heterojunction bipolar transistors under electron irradiation

    SciTech Connect

    Bandyopadhyay, A.; Subramanian, S.; Chandrasekhar, S.; Dentai, A.G.; Goodnick, S.M.

    1999-05-01

    The effects of high-energy ({approximately}1 MeV) electron irradiation on the dc characteristics of InGaAs/InP single heterojunction bipolar transistors (SHBT`s) are investigated. The device characteristics do not show any significant change for electron doses <10{sup 15}/cm{sup 2}. For higher doses, devices show a decrease in collector current, a degradation of common-emitter current gain, an increase in collector saturation voltage and an increase in the collector output conductance. A simple SPICE-like device model is developed to describe the dc characteristics of SHBT`s. The model parameters extracted from the measured dc characteristics of the devices before and after irradiation are used to get an insight into the physical mechanisms responsible for the degradation of the devices.

  17. Computer-aided prediction of high-frequency performance limits in silicon bipolar integrated circuits

    NASA Technical Reports Server (NTRS)

    Burns, J. L.; Choma, J., Jr.

    1982-01-01

    A circuit model for an existing silicon integrated bipolar junction transistor (IBJT) is used to evaluate presently achievable high frequency circuit performance. The relationship between circuit model and processing parameters are semi-quantitatively explored to make predictions on the frequency response, which can be achieved through realistic device fabrication modifications. A new figure of merit is introduced, which is defined as the signal frequency at which an integrated bipolar junction transistor can deliver a power gain of G. The most sensitive parameter influencing attainable high frequency IBJT performance is base resistance.

  18. Simulation of Npn and Pnp AlGaN/GaN heterojunction bipolar transistors performances: Limiting factors and optimum design

    SciTech Connect

    MONIER,C.; REN,F.; HAN,JUNG; CHANG,PING-CHIH; SHUL,RANDY J.; LEE,K.P.; ZHANG,A.P.; BACA,ALBERT G.; PEARTON,S.J.

    2000-04-25

    The performance capabilities of Npn and Pnp AlGaN/GaN heterojunction bipolar transistors have been investigated by using a drift-diffusion transport model. Numerical results have been employed to study the effect of the p-type Mg doping and its incomplete ionization on device performance. The high base resistance induced by the deep acceptor level is found to be the cause of limited current gain values for Npn devices. Several computation approaches have been considered to improve their performance. Reasonable improvement of the DC current gain {beta} is observed by realistically reducing the base thickness in accordance with processing limitations. Base transport enhancement is also predicted by the introduction of a quasi-electric field in the base. The impact of the base resistivity on high-frequency characteristics is investigated for Npn AlGaN/GaN devices. Optimized predictions with maximum oscillation frequency value as high as f{sub MAX} = 20 GHz and a unilateral power gain--U = 25 dB make this bipolar GaN-based technology compatible with communication applications. Simulation results reveal that the restricted amount of free carriers from the p-doped emitter limits Pnp's DC performances operating in common emitter configuration. A preliminary analysis of r.f. characteristics for the Pnp counterpart indicates limited performance mainly caused by the degraded hole mobility.

  19. A doping concentration-dependent upper limit of the breakdown voltage cutoff frequency product in Si bipolar transistors

    NASA Astrophysics Data System (ADS)

    Rieh, Jae-Sung; Jagannathan, Basanth; Greenberg, David; Freeman, Greg; Subbanna, Seshadri

    2004-02-01

    Recent high-speed Si-based bipolar transistors apparently exceed the Johnson Limit in terms of breakdown voltage-cutoff frequency product, and this paper addresses the relevant issues. First, BV CES rather than BV CEO is shown to be the representative breakdown voltage in describing the breakdown-speed trade-off in collector design, since BV CEO is modulated by the current gain which is irrelevant of the collector design and also practical bipolar circuits are rarely operated with open-base condition for which BV CEO is defined. In the same context, it is suggested BV CES be employed in representing the upper limit of breakdown voltage-cutoff frequency product. Second, a collector doping concentration-dependent upper limit of BV CES· fT product is proposed incorporating the doping concentration-dependent critical electric field and accurate values for related device parameters. With this new approach, it is shown that the limit is far larger than the Johnson Limit and the limit is still yet to be reached.

  20. Incorporation of the silicon germanium carbon compound in the realization of a bipolar inversion channel field-effect transistor (BICFET)

    NASA Astrophysics Data System (ADS)

    Sharer, Deborah Louise

    The feasibility of fabrication of an inversion base transistor in the BICFET (Bipolar Inversion Channel Field Effect Transistor) configuration is investigated in this project. The requisite heterostructure will be realized through the extensive use of the silicon germanium carbon compound Si1-x-yGexCy. It is anticipated that band offsets comparable to Si1-xGex(x ˜ 0.5) will be achieved without the inherent difficulties associated with induced strains and epilayer thickness limitations present in this system. Initial explorations will be carried out through utilization of software acquired from Technology Modeling Associates, Sunnyvale, California. Simulations will be accomplished through the use of the Medici software, which is capable of modeling semiconductor devices comprised of conventional and/or user defined materials, impurities, structures and operating conditions. The Medici package, in conjunction with the Heterojunction Device Advanced Application Module (AAM), the Lattice Temperature AAK the Trapped Charge AAK and the Anisotropic Material AAK will also allow prediction of the electrical properties and characteristics of semiconductor devices composed of anisotropic media that possess a discontinuous band structure and inevitable defect constraints under variable thermal conditions. Through the capability of user defined compounds, the effect of incorporating carbon into Si1--xGex will be explored and internal device operation, as well as any breakdown or failure mechanisms allowed for in the software, will be determined.

  1. Fabrication and characterization of GaN junction field effect transistors

    SciTech Connect

    Zhang, L.; Lester, L.F.; Baca, A.G.; Shul, R.J.; Chang, P.C.; Willison, C.L.; Mishra, U.K.; Denbaars, S.P.; Zolper, J.C.

    2000-01-11

    Junction field effect transistors (JFET) were fabricated on a GaN epitaxial structure grown by metal organic chemical vapor deposition. The DC and microwave characteristics, as well as the high temperature performance of the devices were studied. These devices exhibited excellent pinch-off and a breakdown voltage that agreed with theoretical predictions. An extrinsic transconductance (g{sub m}) of 48 mS/mm was obtained with a maximum drain current (I{sub D}) of 270 mA/mm. The microwave measurement showed an f{sub T} of 6 GHz and an f{sub max} of 12 GHz. Both the I{sub D} and the g{sub m} were found to decrease with increasing temperature, possibly due to lower electron mobility at elevated temperatures. These JFETs exhibited a significant current reduction after a high drain bias was applied, which was attributed to a partially depleted channel caused by trapped electrons in the semi-insulating GaN buffer layer.

  2. Molecular beam epitaxy of gallium arsenide antimonide-based ultra-high-speed double heterojunction bipolar transistors and light emitting transistors

    NASA Astrophysics Data System (ADS)

    Wu, Bing-Ruey

    In this work, GaAsSb-based double heterojunction bipolar transistors (DHBTs) and light emitting transistors (LETs) are grown using gas source molecular beam epitaxy (GSMBE). High-speed GaAs0.5Sb0.5/InP DHBTs are developed through the exercise of GSMBE growth optimization, device fabrication, and characterization. By adjusting the growth temperature and V/III flux ratio, the optimal conditions for growing GaAs0.5Sb0.5 base are found to be at high growth temperature and low V/III ratio. The switching sequence is also optimized so that the Sb segregation effect is minimized. By using GaAs0.5Sb0.5-In0.2Ga0.8As 0.7Sb0.3 compositional grading in the base of the GaAsSb/InP DHBT, a significant improvement of fT from 380 GHz to 500 GHz was achieved compared to a uniform GaAs0.5Sb 0.5 DHBT, while maintaining a high breakdown voltage BVCEO ˜ 4V. The cutoff frequency---breakdown voltage product, fT·BVCEO, of over 2000 GHz-V, is the record value for DHBTs of any material system. Incorporating graded InAs-InGaAs emitter contact layer is also shown to effectively reduce the total emitter resistance, further improving the DHBT high speed performance. LET characteristics with quantum wells (QWs) inserted into the base region of GaAsSb/InP DHBTs are also investigated and the preliminary results are presented. An LET with a tensile strained InGaAsSb/GaAs0.65Sb 0.35 DQW in the base was designed and achieved the emission wavelength of ˜1.6 mum, despite of its low light output intensity. The potential and limitation of realizing a transistor laser with an emission wavelength of 1.55 mum using GaAsSb/InP material system will be discussed.

  3. Comments on determination of bandgap narrowing from activation plots. [for bipolar transistors

    NASA Technical Reports Server (NTRS)

    Park, J.-S.; Neugroschel, A.; Lindholm, F. A.

    1986-01-01

    A determination is made of the temperature-dependence of emitter saturation current in bipolar devices which allows the derivation of a value for bandgap narrowing that is in better agreement with other determinations than previous results based on ohmic contact measurements of temperature dependence. The new values were obtained by varying the surface recombination velocity at the emitter surface. This improves accuracy by varying the minority carrier surface recombination velocity at the emitter contacts of otherwise indistinguishable emitters.

  4. High current gain 4H-SiC bipolar junction transistor

    NASA Astrophysics Data System (ADS)

    Yourun, Zhang; Jinfei, Shi; Ying, Liu; Chengchun, Sun; Fei, Guo; Bo, Zhang

    2016-04-01

    A novel 4H-SiC BJT of high current gain with a suppressing surface traps effect has been proposed. It is effective to improve the current gain due to the lower electrons density in the surface region by extending the emitter metal to overlap the passivation layer on the extrinsic base surface. The electrons trapped in the extrinsic base surface induce the degeneration of SiC BJTs device performance. By modulating the electron recombination rate, the novel structure can increase the current gain to 63.2% compared with conventional ones with the compatible process technology. Optimized sizes are an overlapped metal length of 4 μm, as well as an oxide layer thickness of 50 nm. Project supported by the National Natural Science Foundation of China (Nos. 61306093, 61401075).

  5. AlGaAs/InGaAsN/GaAs PnP double heterojunction bipolar transistor

    SciTech Connect

    Chang, P.C.; Baca, A.G.; Li, N.Y.; Sharps, P.R.; Hou, H.Q.; Laroche, J.R.; Ren, F.

    2000-01-04

    The authors demonstrated a functional PnP double heterojunction bipolar transistor (DHBT) using AlGaAs, InGaAsN, and GaAs. The band alignment between InGaAsN and GaAs has a large {triangle}E{sub c} and negligible {triangle}E{sub v}, this unique characteristic is very suitable for PnP DHBT applications. The metalorganic vapor phase epitaxy (MOCVD) grown Al{sub 0.3}Ga{sub 0.7}As/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}/GaAs PnP DHBT is lattice matched to GaAs and has a peak current gain of 25. Because of the smaller bandgap (E{sub g}=1.20eV) of In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} used for the base layer, this device has a low V{sub ON} of 0.79 V, which is 0.25 V lower than in a comparable Pnp AlGaAs/GaAs HBT. And because GaAs is used for the collector, its BV{sub CEO} is 12 V, consistent with BV{sub CEO} of AlGaAs/GaAs HBTs.

  6. Effect of Mg ionization efficiency on performance of Npn AlGaN/GaN heterojunction bipolar transistors

    SciTech Connect

    MONIER,C.; PEARTON,S.J.; CHANG,PING-CHIH; BACA,ALBERT G.

    2000-03-10

    A drift-diffusion transport model has been used to examine the performance capabilities of AlGaN/GaN Npn heterojunction bipolar transistors (HBTs). The Gummel plot from the first GaN-based HBT structure recently demonstrated is adjusted with simulation by using experimental mobility and lifetime reported in the literature. Numerical results have been explored to study the effect of the p-type Mg doping and its incomplete ionization in the base. The high base resistance induced by the deep acceptor level is found to be the cause of limiting current gain values. Increasing the operating temperature of the device activates more carriers in the base. An improvement of the simulated current gain by a factor of 2 to 4 between 25 and 300 C agrees well with the reported experimental results. A preliminary analysis of high frequency characteristics indicates substantial progress of predicted rf performances by operating the device at higher temperature due to a reduced extrinsic base resistivity.

  7. DC modeling and characterization of AlGaAs/GaAs heterojunction bipolar transistors for high-temperature applications

    SciTech Connect

    Dikmen, C.T.; Dogan, N.S.; Osman, M.A. . School of Electrical Engineering and Computer Science)

    1994-02-01

    There is currently a demand for active electronic devices operating reliably over wide range of temperatures. Potential applications for the high-temperature devices and integrated circuits are in the areas of jet engine and control instrumentation for nuclear power plants. Here, the large signal dc characteristics of AlGaAs/GaAs heterojunction bipolar transistors (HBT) at high temperatures (27--300 C) are reported. A high-temperature SPICE model is developed which includes the recombination-generation current components and avalanche multiplication which become extremely important at high temperatures. The effect of avalanche breakdown is also included to model the current due to thermal generation of electron/hole pairs causing breakdown at high temperatures. A parameter extraction program is developed used to extract the model parameters of HBT's at different temperatures. Fitting functions for the model parameters as a function of temperature are developed. These parameters are then used in the SPICE Ebers-Moll model for the dc characterization of the HBT at any temperature between (27--300 C).

  8. A 65-kV insulated gate bipolar transistor switch applied in damped AC voltages partial discharge detection system.

    PubMed

    Jiang, J; Ma, G M; Luo, D P; Li, C R; Li, Q M; Wang, W

    2014-02-01

    Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system. PMID:24593382

  9. A 65-kV insulated gate bipolar transistor switch applied in damped AC voltages partial discharge detection system

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Ma, G. M.; Luo, D. P.; Li, C. R.; Li, Q. M.; Wang, W.

    2014-02-01

    Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system.

  10. Magnetic Vortex Based Transistor Operations

    PubMed Central

    Kumar, D.; Barman, S.; Barman, A.

    2014-01-01

    Transistors constitute the backbone of modern day electronics. Since their advent, researchers have been seeking ways to make smaller and more efficient transistors. Here, we demonstrate a sustained amplification of magnetic vortex core gyration in coupled two and three vortices by controlling their relative core polarities. This amplification is mediated by a cascade of antivortex solitons travelling through the dynamic stray field. We further demonstrated that the amplification can be controlled by switching the polarity of the middle vortex in a three vortex sequence and the gain can be controlled by the input signal amplitude. An attempt to show fan–out operation yielded gain for one of the symmetrically placed branches which can be reversed by switching the core polarity of all the vortices in the network. The above observations promote the magnetic vortices as suitable candidates to work as stable bipolar junction transistors (BJT). PMID:24531235

  11. Graded junction termination extensions for electronic devices

    NASA Technical Reports Server (NTRS)

    Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

    2007-01-01

    A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

  12. Graded junction termination extensions for electronic devices

    NASA Technical Reports Server (NTRS)

    Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

    2006-01-01

    A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

  13. Resonant plasmonic terahertz detection in graphene split-gate field-effect transistors with lateral p–n junctions

    NASA Astrophysics Data System (ADS)

    Ryzhii, V.; Ryzhii, M.; Shur, M. S.; Mitin, V.; Satou, A.; Otsuji, T.

    2016-08-01

    We evaluate the proposed resonant terahertz (THz) detectors on the basis of field-effect transistors (FETs) with split gates, electrically induced lateral p–n junctions, uniform graphene layer (GL) or perforated (in the p–n junction depletion region) graphene layer (PGL) channel. The perforated depletion region forms an array of the nanoconstions or nanoribbons creating the barriers for the holes and electrons. The operation of the GL-FET- and PGL-FET-detectors is associated with the rectification of the ac current across the lateral p–n junction enhanced by the excitation of bound plasmonic oscillations in the p- and n-sections of the channel. Using the developed device model, we find the GL-FET- and PGL-FET-detector characteristics. These detectors can exhibit very high voltage responsivity at the THz radiation frequencies close to the frequencies of the plasmonic resonances. These frequencies can be effectively voltage tuned. We show that in PL-FET-detectors the dominant mechanism of the current rectification is due to the tunneling nonlinearity, whereas in the PGL-FET-detector the current rectification is primarily associated with the thermionic processes. Due to much lower p–n junction conductance in the PGL-FET-detectors, their resonant response can be substantially more pronounced than in the GL-FET-detectors corresponding to fairly high detector responsivity.

  14. A dc model for power switching transistors suitable for computer-aided design and analysis

    NASA Technical Reports Server (NTRS)

    Wilson, P. M.; George, R. T., Jr.; Owen, H. A.; Wilson, T. G.

    1979-01-01

    A model for bipolar junction power switching transistors whose parameters can be readily obtained by the circuit design engineer, and which can be conveniently incorporated into standard computer-based circuit analysis programs is presented. This formulation results from measurements which may be made with standard laboratory equipment. Measurement procedures, as well as a comparison between actual and computed results, are presented.

  15. A dc model for power switching transistors suitable for computer-aided design and analysis

    NASA Technical Reports Server (NTRS)

    Wilson, P. M.; George, R. T., Jr.; Owen, H. A., Jr.; Wilson, T. G.

    1979-01-01

    The proposed dc model for bipolar junction power switching transistors is based on measurements which may be made with standard laboratory equipment. Those nonlinearities which are of importance to power electronics design are emphasized. Measurements procedures are discussed in detail. A model formulation adapted for use with a computer program is presented, and a comparison between actual and computer-generated results is made.

  16. Superconducting transistor

    DOEpatents

    Gray, Kenneth E.

    1979-01-01

    A superconducting transistor is formed by disposing three thin films of superconducting material in a planar parallel arrangement and insulating the films from each other by layers of insulating oxides to form two tunnel junctions. One junction is biased above twice the superconducting energy gap and the other is biased at less than twice the superconducting energy gap. Injection of quasiparticles into the center film by one junction provides a current gain in the second junction.

  17. On the Emitter Resistance of High-Performance GaAs- and InP-Based Heterojunction Bipolar Transistors

    NASA Astrophysics Data System (ADS)

    Matsuoka, Yutaka; Ohkubo, Yukio; Matsumoto, Taisuke; Koji, Takashi; Amano, Yoshiaki; Takagi, Akio

    2008-06-01

    Emitter resistance REE and collector current ideality factor nC of InGaP/GaAs heterostructure bipolar transistors (HBTs) and InP/InGaAs double-HBTs (DHBTs) were investigated from the viewpoints of DC and RF characteristics. It was found that the apparent ideality factor of collector current nCapp increases with the collector current IC for all HBTs. The increase in nCapp is more conspicuous in the InP/InGaAs DHBTs than in the InGaP/GaAs HBTs. The most likely explanation is that the REE consists of two components: one is the well-known contact resistivity REE0 and the other is band-profile-dependent resistivity REi, which decreases as IC increases. In the InP/InGaAs DHBTs, the increase in nCapp with IC is made remarkable by the insertion of an InGaAs etching stop layer (ESL) that makes it easy to form a ledge structure indispensable for high-reliability and high-performance HBTs. However, with the increase of IC, the difference in REE between the InP/InGaAs DHBTs with and without the ESL becomes small. The insertion of an ESL is considered acceptable for high-speed IC applications. Using an emitter structure with an ESL, we developed self-aligned InP/InGaAs DHBTs with a ledge passivation structure that attained an fT of 302 GHz, fmax of 388 GHz, and BVCEO of 6.2 V.

  18. Collector-up aluminum gallium arsenide/gallium arsenide heterojunction bipolar transistors using oxidized aluminum arsenide for current confinement

    NASA Astrophysics Data System (ADS)

    Massengale, Alan Ross

    1998-12-01

    The discovery in 1990 that the wet thermal oxidation of AlAs can create a stable native oxide has added a new constituent, AlAs-oxide, to the AlGaAs/GaAs materials system. Native oxides of high Al mole-fraction AlGaAs are being used to confine electrical and/or optical fields in many types of electronic and optoelectronic structures with very promising results. Among these devices are collector-up heterojunction bipolar transistors (HBTs). Collector-up HBTs offer a means to reduce base-collector capacitance relative to their emitter-up counterparts, and thus to improve device performance. A novel method for fabricating collector-up AlGaAs/GaAs HBTs where an AlAs layer is inserted into the emitter layer and is oxidized in water vapor at 450sp°C has been developed. The resulting AlAs-oxide serves as a current confining layer that constricts collector current flow to the intrinsic portion of the device. Compared to previous methods of fabricating these devices, the process of converting AlAs into an insulator requires only one growth, and does not suffer from implant damage in the base. Because the lateral oxidation of AlAs is a process that proceeds at rates of microns per minute, one of the major challenges facing its implementation is the ability to accurately control the oxidation rate over the wafer, and from one wafer to the next. In the course of work on the oxidation of AlAs, a method to lithographically form lateral oxidation stop layers has been achieved. This technique utilizes impurity induced layer disordering (IILD) in heavily Si-doped buried planes, combined with selective surface patterning and thermal annealing, to create a lateral variation in the Al mole-fraction of the layer to be oxidized.

  19. Compact model for non-local avalanche effect in advanced bipolar transistors: An assessment of the relaxation length and its temperature dependence

    NASA Astrophysics Data System (ADS)

    Setekera, Robert; van der Toorn, Ramses

    2016-05-01

    We present a physics based compact model formulation for non-local avalanche effects. It is explicit and in terms of elementary functions, hence suitable for implementation in existing compact transistor models. The formulation has only two material coefficients as parameters: the energy relaxation length and its temperature coefficient. We present a detailed verification of our model against measured avalanche characteristics, as a function of both bias and temperature, for Si and SiGe industrial bipolar transistors. We demonstrate that the model is complete and accurate enough for the parameter extraction to be taken as an in situ measurement for both the electron energy relaxation length and its temperature coefficient: values obtained correspond to the values published earlier in the semiconductor literature.

  20. Heavy-ion broad-beam and microprobe studies of single-event upsets in 0.20 um SiGe heterojunction bipolar transistors and circuits.

    SciTech Connect

    Fritz, Karl; Irwin, Timothy J.; Niu, Guofu; Fodness, Bryan; Carts, Martin A.; Marshall, Paul W.; Reed, Robert A.; Gilbert, Barry; Randall, Barbara; Prairie, Jason; Riggs, Pam; Pickel, James C.; LaBel, Kenneth; Cressler, John D.; Krithivasan, Ramkumar; Dodd, Paul Emerson; Vizkelethy, Gyorgy

    2003-09-01

    Combining broad-beam circuit level single-event upset (SEU) response with heavy ion microprobe charge collection measurements on single silicon-germanium heterojunction bipolar transistors improves understanding of the charge collection mechanisms responsible for SEU response of digital SiGe HBT technology. This new understanding of the SEU mechanisms shows that the right rectangular parallele-piped model for the sensitive volume is not applicable to this technology. A new first-order physical model is proposed and calibrated with moderate success.

  1. Effect of Si interface surface roughness to the tunneling current of the Si/Si1-xGex/Si heterojunction bipolar transistor

    NASA Astrophysics Data System (ADS)

    Hasanah, Lilik; Suhendi, Endi; Tayubi, Yuyu Rahmat; Yuwono, Heru; Nandiyanto, Asep Bayu Dani; Murakami, Hideki; Khairrurijal

    2016-02-01

    In this work we discuss the surface roughness of Si interface impact to the tunneling current of the Si/Si1-xGex/Si heterojunction bipolar transistor. The Si interface surface roughness can be analyzed from electrical characteristics through the transversal electron velocity obtained as fitting parameter factor. The results showed that surface roughness increase as Ge content of virtual substrate increase This model can be used to investigate the effect of Ge content of the virtual substrate to the interface surface condition through current-voltage characteristic.

  2. Evaluation and Control of Break-Even Time of Nonvolatile Static Random Access Memory Based on Spin-Transistor Architecture with Spin-Transfer-Torque Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Shuto, Yusuke; Yamamoto, Shuu'ichirou; Sugahara, Satoshi

    2012-04-01

    The energy performance of a nonvolatile static random access memory (NV-SRAM) cell for power gating applications was quantitatively analyzed for the first time using the performance index of break-even time (BET). The NV-SRAM cell is based on spin-transistor architecture using ordinary metal-oxide-semiconductor field-effect transistors (MOSFETs) and spin-transfer-torque magnetic tunnel junctions (STT-MTJs), whose circuit representation of spin-transistor is referred to as a pseudo-spin-MOSFET (PS-MOSFET). The cell is configured with a standard six-transistor SRAM cell and two PS-MOSFETs. The NV-SRAM cell basically has a short BET of submicroseconds. Although the write (store) operation to the STT-MTJs causes an increase in the BET, it can be successfully reduced by the proposed power-aware bias-control for the PS-MOSFETs.

  3. Radiation effect on silicon transistors in mixed neutrons-gamma environment

    NASA Astrophysics Data System (ADS)

    Assaf, J.; Shweikani, R.; Ghazi, N.

    2014-10-01

    The effects of gamma and neutron irradiations on two different types of transistors, Junction Field Effect Transistor (JFET) and Bipolar Junction Transistor (BJT), were investigated. Irradiation was performed using a Syrian research reactor (RR) (Miniature Neutron Source Reactor (MNSR)) and a gamma source (Co-60 cell). For RR irradiation, MCNP code was used to calculate the absorbed dose received by the transistors. The experimental results showed an overall decrease in the gain factors of the transistors after irradiation, and the JFETs were more resistant to the effects of radiation than BJTs. The effect of RR irradiation was also greater than that of gamma source for the same dose, which could be because neutrons could cause more damage than gamma irradiation.

  4. Comparative passivation effects of self-assembled mono- and multilayers on GaAs junction field effect transistors

    NASA Astrophysics Data System (ADS)

    Lee, Kangho; Lu, Gang; Facchetti, Antonio; Janes, David B.; Marks, Tobin J.

    2008-03-01

    Control of semiconductor interface state density with molecular passivation is essential for developing conduction-based biosensors. In this study, GaAs junction field effect transistors (JFETs) are fabricated and characterized before and after passivation of the GaAs surface with self-assembled mono- and multilayers. The JFETs functionalized with 1-octadecanethiol monolayers and two types of self-assembled organic nanodielectric (SAND) multilayers exhibit significantly different threshold voltage (Vth) and subthreshold slope (Ssub) characteristics versus the unpassivated devices and provide useful information on the quality of the passivation. Two-dimensional device simulations quantify the effective density of fixed surface charges and interfacial traps and argue for the importance of the type-III SAND ionic charges in enhancing GaAs JFET response characteristics.

  5. Efficient light output power for InGaP/GaAs heterojunction bipolar transistors incorporated with InGaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Huang, Tzu-Hsuan; Wu, Meng-Chyi

    2016-07-01

    In this work, the current gain and optical frequency response of the heterojunction bipolar transistor (HBT) and heterojunction bipolar light-emitting transistor (HBLET) are investigated. Compared to the conventional HBT, two-pair quantum wells are embedded in the base region of the HBLET. The current gain of HBLET increases with temperature, which shows dissimilar electrical properties to the HBT. Although the current gain of HBLET is much smaller than that of HBT, the decrement of current gain is converted to enhance the light output power. The light output power of HBLET can reach 0.96 mW at 90 mA. The HBLET exhibits the 3-dB bandwidths (f3dB) of 554 and 559 MHz at 30 and 50 mA, respectively. It is found that the 3-dB frequency is proportional to the square root of base current density, while the minority carrier lifetime is inversely proportional to the square root of base current density. Therefore, our results suggest that HBLET with the high light output power shows a great potential in the short range optical data communications.

  6. Black Phosphorus-Zinc Oxide Nanomaterial Heterojunction for p-n Diode and Junction Field-Effect Transistor.

    PubMed

    Jeon, Pyo Jin; Lee, Young Tack; Lim, June Yeong; Kim, Jin Sung; Hwang, Do Kyung; Im, Seongil

    2016-02-10

    Black phosphorus (BP) nanosheet is two-dimensional (2D) semiconductor with distinct band gap and attracting recent attention from researches because it has some similarity to gapless 2D semiconductor graphene in the following two aspects: single element (P) for its composition and quite high mobilities depending on its fabrication conditions. Apart from several electronic applications reported with BP nanosheet, here we report for the first time BP nanosheet-ZnO nanowire 2D-1D heterojunction applications for p-n diodes and BP-gated junction field effect transistors (JFETs) with n-ZnO channel on glass. For these nanodevices, we take advantages of the mechanical flexibility of p-type conducting of BP and van der Waals junction interface between BP and ZnO. As a result, our BP-ZnO nanodimension p-n diode displays a high ON/OFF ratio of ∼10(4) in static rectification and shows kilohertz dynamic rectification as well while ZnO nanowire channel JFET operations are nicely demonstrated by BP gate switching in both electrostatics and kilohertz dynamics. PMID:26771206

  7. Method and apparatus for increasing resistance of bipolar buried layer integrated circuit devices to single-event upsets

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A. (Inventor)

    1991-01-01

    Bipolar transistors fabricated in separate buried layers of an integrated circuit chip are electrically isolated with a built-in potential barrier established by doping the buried layer with a polarity opposite doping in the chip substrate. To increase the resistance of the bipolar transistors to single-event upsets due to ionized particle radiation, the substrate is biased relative to the buried layer with an external bias voltage selected to offset the built-in potential just enough (typically between about +0.1 to +0.2 volt) to prevent an accumulation of charge in the buried-layer-substrate junction.

  8. Progress Towards High-Sensitivity Arrays of Detectors of Sub-mm Radiation Using Superconducting Tunnel Junctions with Integrated Radio Frequency Single-Electron Transistors

    NASA Technical Reports Server (NTRS)

    Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Prober, D. E.; Rhee, K. W.; Schoelkopf, R. J.; Stahle, C. M.; Teufel, J.; Wollack, E. J.

    2004-01-01

    For high resolution imaging and spectroscopy in the FIR and submillimeter, space observatories will demand sensitive, fast, compact, low-power detector arrays with 104 pixels and sensitivity less than 10(exp -20) W/Hz(sup 0.5). Antenna-coupled superconducting tunnel junctions with integrated rf single-electron transistor readout amplifiers have the potential for achieving this high level of sensitivity, and can take advantage of an rf multiplexing technique. The device consists of an antenna to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure current through junctions contacting the absorber. We describe optimization of device parameters, and results on fabrication techniques for producing devices with high yield for detector arrays. We also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

  9. Normal metal tunnel junction-based superconducting quantum interference proximity transistor

    SciTech Connect

    D'Ambrosio, Sophie Meissner, Martin; Blanc, Christophe; Ronzani, Alberto; Giazotto, Francesco

    2015-09-14

    We report the fabrication and characterization of an alternative design for a superconducting quantum interference proximity transistor (SQUIPT) based on a normal metal (N) probe. The absence of direct Josephson coupling between the proximized metal nanowire and the N probe allows us to observe the full modulation of the wire density of states around zero voltage and current via the application of an external magnetic field. This results into a drastic suppression of power dissipation which can be as low as a few ∼10{sup −17} W. In this context, the interferometer allows an improvement of up to four orders of magnitude with respect to earlier SQUIPT designs and makes it ideal for extra-low power cryogenic applications. In addition, the N-SQUIPT has been recently predicted to be the enabling candidate for the implementation of coherent caloritronic devices based on proximity effect.

  10. NpN-GaN/InxGa1-xN/GaN heterojunction bipolar transistor on free-standing GaN substrate

    NASA Astrophysics Data System (ADS)

    Lochner, Zachary; Jin Kim, Hee; Lee, Yi-Che; Zhang, Yun; Choi, Suk; Shen, Shyh-Chiang; Doug Yoder, P.; Ryou, Jae-Hyun; Dupuis, Russell D.

    2011-11-01

    Data and analysis are presented for NpN-GaN/InGaN/GaN double-heterojunction bipolar transistors (HBTs) grown and fabricated on a free-standing GaN (FS-GaN) substrate in comparison to that on a sapphire substrate to investigate the effect of dislocations in III-nitride HBT epitaxial structures. The performance characteristics of HBTs on FS-GaN exhibit a maximum collector current density of ˜12.3 kA/cm2, dc current gain of ˜90, and maximum differential gain of ˜120 without surface passivation, representing a substantial improvement over similar devices grown on sapphire. This is attributed to the reduction in threading dislocation density afforded by using a homoepitaxial growth on a high-crystalline-quality substrate. The minority carrier diffusion length increases significantly owing to not only a mitigated carrier trap effect via fewer dislocations, but also possibly reduced microscopic localized states.

  11. On the AlGaInP-bulk and AlGaInP/GaAs-superlattice confinement effects for heterostructure-emitter bipolar transistors

    SciTech Connect

    Tsai, Jung-Hui

    2015-02-09

    The confinement effect and electrical characteristics of heterostructure-emitter bipolar transistors with an AlGaInP bulk-confinement layer and an AlGaInP/GaAs superlattice-confinement layer are first demonstrated and compared by experimentally results. In the two devices, the relatively large valence band discontinuity at AlGaInP/GaAs heterojunction provides excellent confinement effect for holes to enhance current gain. As to the AlGaInP/GaAs superlattice-confinement device, part of thermionic-emission electrons will be trapped in the GaAs quantum wells of the superlattice. This will result in lower collector current and current gain as compared with the bulk-confinement device. Nevertheless, the superlattice-confinement device exhibits a larger current-gain cutoff frequency, which can be attributed that the tunneling behavior is included in the carrier transportation and transporting time across the emitter region could be substantially reduced.

  12. Numerical investigation of temperature field Induced by dual wavelength lasers in sub-microsecond laser annealing technology for insulated gate bipolar transistor

    NASA Astrophysics Data System (ADS)

    Cui, GuoDong; Ma, Mingying; Wang, Fan; Sun, Gang; Lan, Yanping; Xu, Wen

    2015-07-01

    To enhance the performance of the Insulated Gate Bipolar Transistor (IGBT), sub-microsecond laser annealing (LA) is propitious to achieve maximal dopant activation with minimal diffusion. In this work, two different lasers are used as annealing resource: a continuous 808 nm laser with larger spot is applied to preheat the wafer and another sub-microsecond pulsed 527 nm laser is responsible to activate the dopant. To optimize the system's performance, a physical model is presented to predict the thermal effect of two laser fields interacting on wafer. Using the Finite-Element method (FEM), we numerically investigate the temperature field induced by lasers in detail. The process window corresponding to the lasers is also acquired which can satisfy the requirements of the IGBT's annealing.

  13. Switching characteristics of a 4H-SiC insulated-gate bipolar transistor with interface defects up to the nonquasi-static regime

    NASA Astrophysics Data System (ADS)

    Pesic, Iliya; Navarro, Dondee; Fujinaga, Masato; Furui, Yoshiharu; Miura-Mattausch, Mitiko

    2015-04-01

    The switching characteristics of a trench-type 4H-SiC insulated-gate bipolar transistor (IGBT) device with interface defects are analyzed up to the nonquasi-static (NQS) switching regime using reported interface density measurements and device simulation. Collector current degradation characterized by threshold voltage shift to higher gate voltages and reduction of current magnitude due to carrier trapping are observed under quasi-static (QS) simulation condition. At slow switching of the gate voltage, carrier trapping causes a hump in the transient current at the start of conduction. At very fast switching, the current hump is limited by the NQS effect which results to a reduced switching efficiency and increased on-resistance.

  14. Investigation of 4H-SiC insulated-gate bipolar transistor turn-off performance for achieving low power loss

    NASA Astrophysics Data System (ADS)

    Navarro, Dondee; Pesic, Iliya; Morikawa, Yoji; Furui, Yoshiharu; Miura-Mattausch, Mitiko

    2016-04-01

    The dynamic characteristics of a 4H-SiC insulated-gate bipolar transistor (IGBT) at pulse switching is investigated by incorporating reported measurements of the interface defect density to device simulation. Different trap features such as energy states and trap time constants are investigated to determine the influence of traps on circuit performance. The capture cross-section parameter used in the simulation depicts the probability of traps to trap/detrap carriers which relates to the carrier trap time constant. It is demonstrated that trapped carriers from the on-state condition cause enhanced generation current during the off-state condition, which give rise to undesired leakage current in addition to the threshold voltage shift previously reported. The device power dissipation is increased by a factor of 100 due to the defects.

  15. Plasma Separation Process: Betacell (BCELL) code: User's manual. [Bipolar barrier junction

    SciTech Connect

    Taherzadeh, M.

    1987-11-13

    The emergence of clearly defined applications for (small or large) amounts of long-life and reliable power sources has given the design and production of betavoltaic systems a new life. Moreover, because of the availability of the plasma separation program, (PSP) at TRW, it is now possible to separate the most desirable radioisotopes for betacell power generating devices. A computer code, named BCELL, has been developed to model the betavoltaic concept by utilizing the available up-to-date source/cell parameters. In this program, attempts have been made to determine the betacell energy device maximum efficiency, degradation due to the emitting source radiation and source/cell lifetime power reduction processes. Additionally, comparison is made between the Schottky and PN junction devices for betacell battery design purposes. Certain computer code runs have been made to determine the JV distribution function and the upper limit of the betacell generated power for specified energy sources. A Ni beta emitting radioisotope was used for the energy source and certain semiconductors were used for the converter subsystem of the betacell system. Some results for a Promethium source are also given here for comparison. 16 refs.

  16. Optically Induced PN Junction Diode and Photovoltaic Response on Ambipolar MoSe2 Field-effect Transistor

    NASA Astrophysics Data System (ADS)

    Pradhan, Nihar; Lu, Zhengguang; Rhodes, Daniel; Terrones, Mauricio; Smirnov, Dmitry; Balicas, Luis

    2015-03-01

    Transition metal dichalcogenides (TMDs) have emerged as an attractive material for electronic and optoelectronic devices due to their sizable band gap, flexibility and reduced dimensionality, which makes them promising candidates for applications in translucent optoelectronics components, such as solar cells and light emitting diodes. Here, we present an optically induced diode like response and concomitant photovoltaic effect in few-atomic layers molybdenum diselenide (MoSe2) field-effect transistors. Compared to recently reported PN junctions based on TMDs, ambipolar MoSe2 shows nearly ideal diode rectification under illumination, with a sizable photovoltaic efficiency. The observed light induced diode response under fixed gate voltage, yields a maximum open circuit voltage 0.28V and short circuit current 230nA at 30uW incident laser power. The sense of current rectification can be altered by changing the polarity of the applied gate voltage (Vbg) . At Vbg = 0V the highest electrical power obtained is 175pW corresponding to a maximum photovoltaic efficiency of 0.01%. These values increased to 11nW and 0.05% under a Vbg = -7.5V. At an excitation voltage 1V we observed maximum photocurrent responsivity surpassing 100mA/W with corresponding external quantum efficiency ~ 30%.

  17. Electrical detection of the biological interaction of a charged peptide via gallium arsenide junction-field-effect transistors

    NASA Astrophysics Data System (ADS)

    Lee, Kangho; Nair, Pradeep R.; Alam, Muhammad A.; Janes, David B.; Wampler, Heeyeon P.; Zemlyanov, Dmitry Y.; Ivanisevic, Albena

    2008-06-01

    GaAs junction-field-effect transistors (JFETs) are utilized to achieve label-free detection of biological interaction between a probe transactivating transcriptional activator (TAT) peptide and the target trans-activation-responsive (TAR) RNA. The TAT peptide is a short sequence derived from the human immunodeficiency virus-type 1 TAT protein. The GaAs JFETs are modified with a mixed adlayer of 1-octadecanethiol (ODT) and TAT peptide, with the ODT passivating the GaAs surface from polar ions in physiological solutions and the TAT peptide providing selective binding sites for TAR RNA. The devices modified with the mixed adlayer exhibit a negative pinch-off voltage (VP) shift, which is attributed to the fixed positive charges from the arginine-rich regions in the TAT peptide. Immersing the modified devices into a TAR RNA solution results in a large positive VP shift (>1 V) and a steeper subthreshold slope (˜80 mV/decade), whereas "dummy" RNA induced a small positive VP shift (˜0.3 V) without a significant change in subthreshold slopes (˜330 mV/decade). The observed modulation of device characteristics is analyzed with analytical modeling and two-dimensional numerical device simulations to investigate the electronic interactions between the GaAs JFETs and biological molecules.

  18. Electrical detection of the biological interaction of a charged peptide via gallium arsenide junction-field-effect transistors

    PubMed Central

    Lee, Kangho; Nair, Pradeep R.; Alam, Muhammad A.; Janes, David B.; Wampler, Heeyeon P.; Zemlyanov, Dmitry Y.; Ivanisevic, Albena

    2008-01-01

    GaAs junction-field-effect transistors (JFETs) are utilized to achieve label-free detection of biological interaction between a probe transactivating transcriptional activator (TAT) peptide and the target trans-activation-responsive (TAR) RNA. The TAT peptide is a short sequence derived from the human immunodeficiency virus-type 1 TAT protein. The GaAs JFETs are modified with a mixed adlayer of 1-octadecanethiol (ODT) and TAT peptide, with the ODT passivating the GaAs surface from polar ions in physiological solutions and the TAT peptide providing selective binding sites for TAR RNA. The devices modified with the mixed adlayer exhibit a negative pinch-off voltage (VP) shift, which is attributed to the fixed positive charges from the arginine-rich regions in the TAT peptide. Immersing the modified devices into a TAR RNA solution results in a large positive VP shift (>1 V) and a steeper subthreshold slope (∼80 mV∕decade), whereas “dummy” RNA induced a small positive VP shift (∼0.3 V) without a significant change in subthreshold slopes (∼330 mV∕decade). The observed modulation of device characteristics is analyzed with analytical modeling and two-dimensional numerical device simulations to investigate the electronic interactions between the GaAs JFETs and biological molecules. PMID:19484151

  19. Stability Diagrams of Single-Common-Gate Double-Dot Single-Electron Transistors with Arbitrary Junction and Gate Capacitances

    NASA Astrophysics Data System (ADS)

    Imai, Shigeru; Kato, Hiroki; Hiraoka, Yasuhiro

    2012-12-01

    Stability diagrams of single-common-gate double-dot single-electron transistors are drawn in the Vg-V plane using the exact formulas that represent Coulomb blockade conditions, where the gate, source, and drain voltages are Vg, -V/2, and V/2, respectively. The stability regions are arranged along the Vg axis with no overlap. If gate capacitances Cg1 and Cg2 satisfy Cg1/m1 = Cg2/m2 = C0, the stability diagram is periodic with the period of e/C0 along the Vg axis, where m1 and m2 are natural numbers prime to each other. The stability diagram is point-symmetrical with respect to the point (me/2C0, 0) for all integers m. If Vg increases at V = 0, electrons are transferred into the islands under a rule, which can be explained in terms of periodicity and symmetry. The detailed features are described for the cases of uniform gate capacitances and uniform junction capacitances.

  20. Determination of lifetimes and recombination currents in p-n junction solar cells, diodes, and transistors

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.

    1981-01-01

    New methods are presented and illustrated that enable the accurate determination of the diffusion length of minority carriers in the narrow regions of a solar cell or a diode. Other methods now available are inaccurate for the desired case in which the width of the region is less than the diffusion length. Once the diffusion length is determined by the new methods, this result can be combined with measured dark I-V characteristics and with small-signal admittance characteristics to enable determination of the recombination currents in each quasi-neutral region of the cell - for example, in the emitter, low-doped base, and high-doped base regions of the BSF (back-surface-field) cell. This approach leads to values for the effective surface recombination velocity of the high-low junction forming the back-surface field of BSF cells or the high-low emitter junction of HLE cells. These methods are also applicable for measuring the minority-carrier lifetime in thin epitaxial layers grown on substrates with opposite conductivity type.

  1. Analysis of different tunneling mechanisms of In{sub x}Ga{sub 1−x}As/AlGaAs tunnel junction light-emitting transistors

    SciTech Connect

    Wu, Cheng-Han; Wu, Chao-Hsin

    2014-10-27

    The electrical and optical characteristics of tunnel junction light-emitting transistors (TJLETs) with different indium mole fractions (x = 5% and 2.5%) of the In{sub x}Ga{sub 1−x}As base-collector tunnel junctions have been investigated. Two electron tunneling mechanisms (photon-assisted or direct tunneling) provide additional currents to electrical output and resupply holes back to the base region, resulting in the upward slope of I-V curves and enhanced optical output under forward-active operation. The larger direct tunneling probability and stronger Franz-Keldysh absorption for 5% TJLET lead to higher collector current slope and less optical intensity enhancement when base-collector junction is under reverse-biased.

  2. Oxide bipolar electronics: materials, devices and circuits

    NASA Astrophysics Data System (ADS)

    Grundmann, Marius; Klüpfel, Fabian; Karsthof, Robert; Schlupp, Peter; Schein, Friedrich-Leonhard; Splith, Daniel; Yang, Chang; Bitter, Sofie; von Wenckstern, Holger

    2016-06-01

    We present the history of, and the latest progress in, the field of bipolar oxide thin film devices. As such we consider primarily pn-junctions in which at least one of the materials is a metal oxide semiconductor. A wide range of n-type and p-type oxides has been explored for the formation of such bipolar diodes. Since most oxide semiconductors are unipolar, challenges and opportunities exist with regard to the formation of heterojunction diodes and band lineups. Recently, various approaches have led to devices with high rectification, namely p-type ZnCo2O4 and NiO on n-type ZnO and amorphous zinc-tin-oxide. Subsequent bipolar devices and applications such as photodetectors, solar cells, junction field-effect transistors and integrated circuits like inverters and ring oscillators are discussed. The tremendous progress shows that bipolar oxide electronics has evolved from the exploration of various materials and heterostructures to the demonstration of functioning integrated circuits. Therefore a viable, facile and high performance technology is ready for further exploitation and performance optimization.

  3. Static and switching characteristics of 3.3 kV double channel-doped SiC vertical junction field effect transistor in cascode configuration

    NASA Astrophysics Data System (ADS)

    Shimizu, Haruka; Akiyama, Satoru; Yokoyama, Natsuki; Shima, Akio; Shimamoto, Yasuhiro

    2015-04-01

    A silicon-carbide (SiC) junction field-effect transistor (JFET)/Si metal-oxide-semiconductor field-effect transistor (MOSFET) cascode is a good solution owing to its high reliability, low on-resistance, high switching speed, and good gate controllability. A 3.3 kV SiC vertical JFET using a double channel doping technique is proposed in this paper. The characteristics of a cascode including the developed JFET are also presented. A blocking voltage higher than 4.0 kV and a low on-resistance of 14.7 mΩ cm2 were realized. The saturation current of the cascode was suppressed by controlling the threshold voltage of the JFET. Moreover, small switching losses were obtained.

  4. Modeling Low-Dose-Rate Effects in Irradiated Bipolar-Base Oxides

    SciTech Connect

    Cirba, C.R.; Fleetwood, D.M.; Graves, R.J.; Michez, A.; Milanowski, R.J.; Saigne, F.; Schrimpf, R.D.; Witczak, S.C.

    1998-10-26

    A physical model is developed to quantify the contribution of oxide-trapped charge to enhanced low-dose-rate gain degradation in bipolar junction transistors. Multiple-trapping simulations show that space charge limited transport is partially responsible for low-dose-rate enhancement. At low dose rates, more holes are trapped near the silicon-oxide interface than at high dose rates, resulting in larger midgap voltage shifts at lower dose rates. The additional trapped charge near the interface may cause an exponential increase in excess base current, and a resultant decrease in current gain for some NPN bipolar technologies.

  5. High Accuracy Transistor Compact Model Calibrations

    SciTech Connect

    Hembree, Charles E.; Mar, Alan; Robertson, Perry J.

    2015-09-01

    Typically, transistors are modeled by the application of calibrated nominal and range models. These models consists of differing parameter values that describe the location and the upper and lower limits of a distribution of some transistor characteristic such as current capacity. Correspond- ingly, when using this approach, high degrees of accuracy of the transistor models are not expected since the set of models is a surrogate for a statistical description of the devices. The use of these types of models describes expected performances considering the extremes of process or transistor deviations. In contrast, circuits that have very stringent accuracy requirements require modeling techniques with higher accuracy. Since these accurate models have low error in transistor descriptions, these models can be used to describe part to part variations as well as an accurate description of a single circuit instance. Thus, models that meet these stipulations also enable the calculation of quantifi- cation of margins with respect to a functional threshold and uncertainties in these margins. Given this need, new model high accuracy calibration techniques for bipolar junction transis- tors have been developed and are described in this report.

  6. A silicon nanocrystal tunnel field effect transistor

    SciTech Connect

    Harvey-Collard, Patrick; Drouin, Dominique; Pioro-Ladrière, Michel

    2014-05-12

    In this work, we demonstrate a silicon nanocrystal Field Effect Transistor (ncFET). Its operation is similar to that of a Tunnelling Field Effect Transistor (TFET) with two barriers in series. The tunnelling barriers are fabricated in very thin silicon dioxide and the channel in intrinsic polycrystalline silicon. The absence of doping eliminates the problem of achieving sharp doping profiles at the junctions, which has proven a challenge for large-scale integration and, in principle, allows scaling down the atomic level. The demonstrated ncFET features a 10{sup 4} on/off current ratio at room temperature, a low 30 pA/μm leakage current at a 0.5 V bias, an on-state current on a par with typical all-Si TFETs and bipolar operation with high symmetry. Quantum dot transport spectroscopy is used to assess the band structure and energy levels of the silicon island.

  7. Characterization of vertical GaN p-n diodes and junction field-effect transistors on bulk GaN down to cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Kizilyalli, I. C.; Aktas, O.

    2015-12-01

    There is great interest in wide-bandgap semiconductor devices and most recently in vertical GaN structures for power electronic applications such as power supplies, solar inverters and motor drives. In this paper the temperature-dependent electrical behavior of vertical GaN p-n diodes and vertical junction field-effect transistors fabricated on bulk GaN substrates of low defect density (104 to 106 cm-2) is described. Homoepitaxial MOCVD growth of GaN on its native substrate and the ability to control the doping in the drift layers in GaN have allowed the realization of vertical device architectures with drift layer thicknesses of 6 to 40 μm and net carrier electron concentrations as low as 1 × 1015 cm-3. This parameter range is suitable for applications requiring breakdown voltages of 1.2 kV to 5 kV. Mg, which is used as a p-type dopant in GaN, is a relatively deep acceptor (E A ≈ 0.18 eV) and susceptible to freeze-out at temperatures below 200 K. The loss of holes in p-GaN has a deleterious effect on p-n junction behavior, p-GaN contacts and channel control in junction field-effect transistors at temperatures below 200 K. Impact ionization-based avalanche breakdown (BV > 1200 V) in GaN p-n junctions is characterized between 77 K and 423 K for the first time. At higher temperatures the p-n junction breakdown voltage improves due to increased phonon scattering. A positive temperature coefficient in the breakdown voltage is demonstrated down to 77 K; however, the device breakdown characteristics are not as abrupt at temperatures below 200 K. On the other hand, contact resistance to p-GaN is reduced dramatically above room temperature, improving the overall device performance in GaN p-n diodes in all cases except where the n-type drift region resistance dominates the total forward resistance. In this case, the electron mobility can be deconvolved and is found to decrease with T -3/2, consistent with a phonon scattering model. Also, normally-on vertical junction

  8. Device characteristics of the PnP AlGaAs/InGaAsN/GaAs double heterojunction bipolar transistor

    SciTech Connect

    CHANG,PING-CHIH; LI,N.Y.; LAROCHE,J.R.; BACA,ALBERT G.; HOU,H.Q.; REN,F.

    2000-02-09

    The authors have demonstrated a functional PnP double heterojunction bipolar transistor (DHBT) using AlGaAs, InGaAsN, and GaAs. The band alignment between InGaAsN and GaAs has a large {triangle}E{sub C} and a negligible {triangle}E{sub V}, and this unique characteristic is very suitable for PnP DHBT applications. The metalorganic vapor phase epitaxy (MOCVD) grown Al{sub 0.3}Ga{sub 0.7}As/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}/GaAs PnP DHBT is lattice matched to GaAs and has a peak current gain of 25. Because of the smaller bandgap (Eg = 1.20 eV) of In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} used for the base layer, this device has a low V{sub ON} of 0.79 V, which is 0.25 V lower than in a comparable Pnp AlGaAs/GaAs HBT. And because GaAs is used for the collector, its BV{sub CEO} is 12 V, consistent with BV{sub CEO} of AlGaAs/GaAs HBTs of comparable collector thickness and doping level.

  9. An investigation of the effect of graded layers and tunneling on the performance of AlGaAs/GaAs heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Grinberg, A. A.; Shur, M. S.; Fischer, R. J.; Morkoc, H.

    1984-12-01

    Results of theoretical and experimental studies of the heterojunction bipolar transistor are presented. The calculations are based on a new thermionic field-diffusion model which takes into account the dependence of the emitter efficiency on the height of the interface conduction band spike and tunneling across the spike. Based on this theory, analytical expressions are derived for the current-voltage characteristics, and the short-circuit common emitter current gain is related to the material parameters, doping levels, grading length, and device temperature. It is demonstrated that the thermoemission transport across the interface spike limits the rate of increase in the collector current with the emitter-base voltage and, as a consequence, the maximum common emitter current gain. Tunneling also plays an important role, especially for abrupt heterojunctions. The calculations reveal an important role played by grading of the composition of the emitter region in the vicinity of the heterointerface. Such grading decreases the barrier height at the interface and greatly enhances the emitter injection efficiency.

  10. A G-band terahertz monolithic integrated amplifier in 0.5-μm InP double heterojunction bipolar transistor technology

    NASA Astrophysics Data System (ADS)

    Ou-Peng, Li; Yong, Zhang; Rui-Min, Xu; Wei, Cheng; Yuan, Wang; Bing, Niu; Hai-Yan, Lu

    2016-05-01

    Design and characterization of a G-band (140–220 GHz) terahertz monolithic integrated circuit (TMIC) amplifier in eight-stage common-emitter topology are performed based on the 0.5-μm InGaAs/InP double heterojunction bipolar transistor (DHBT). An inverted microstrip line is implemented to avoid a parasitic mode between the ground plane and the InP substrate. The on-wafer measurement results show that peak gains are 20 dB at 140 GHz and more than 15-dB gain at 140–190 GHz respectively. The saturation output powers are ‑2.688 dBm at 210 GHz and ‑2.88 dBm at 220 GHz, respectively. It is the first report on an amplifier operating at the G-band based on 0.5-μm InP DHBT technology. Compared with the hybrid integrated circuit of vacuum electronic devices, the monolithic integrated circuit has the advantage of reliability and consistency. This TMIC demonstrates the feasibility of the 0.5-μm InGaAs/InP DHBT amplifier in G-band frequencies applications. Project supported by the National Natural Science Foundation of China (Grant No. 61501091) and the Fundamental Research Funds for the Central Universities of Ministry of Education of China (Grant Nos. ZYGX2014J003 and ZYGX2013J020).

  11. Comparative investigation of InGaP/GaAs/GaAsBi and InGaP/GaAs heterojunction bipolar transistors

    SciTech Connect

    Wu, Yi-Chen; Tsai, Jung-Hui; Chiang, Te-Kuang; Wang, Fu-Min

    2015-10-15

    In this article the characteristics of In{sub 0.49}Ga{sub 0.51}P/GaAs/GaAs{sub 0.975}Bi{sub 0.025} and In{sub 0.49}Ga{sub 0.51}P/GaAs heterojunction bipolar transistor (HBTs) are demonstrated and compared by two-dimensional simulated analysis. As compared to the traditional InGaP/GaAs HBT, the studied InGaP/GaAs/GaAsBi HBT exhibits a higher collector current, a lower base-emitter (B–E) turn-on voltage, and a relatively lower collector-emitter offset voltage of only 7 mV. Because the more electrons stored in the base is further increased in the InGaP/GaAs/GaAsBi HBT, it introduces the collector current to increase and the B–E turn-on voltage to decrease for low input power applications. However, the current gain is slightly smaller than the traditional InGaP/GaAs HBT attributed to the increase of base current for the minority carriers stored in the GaAsBi base.

  12. Epitaxial growth and characterization of thick multi-layer 4H-SiC for very high-voltage insulated gate bipolar transistors

    NASA Astrophysics Data System (ADS)

    Miyazawa, Tetsuya; Nakayama, Koji; Tanaka, Atsushi; Asano, Katsunori; Ji, Shi-yang; Kojima, Kazutoshi; Ishida, Yuuki; Tsuchida, Hidekazu

    2015-08-01

    Techniques to fabricate thick multi-layer 4H-SiC epitaxial wafers were studied for very high-voltage p- and n-channel insulated gate bipolar transistors (IGBTs). Multi-layer epitaxial growth, including a thick p- drift layer (˜180 μm), was performed on a 4H-SiC n+ substrate to form a p-IGBT structure. For an n-IGBT structure, an inverted growth process was employed, in which a thick n- drift layer (˜180 μm) and a thick p++ injector layer (>55 μm) were epitaxially grown. The epitaxial growth conditions were modified to attain a low defect density, a low doping concentration, and a long carrier lifetime in the drift layers. Reduction of the forward voltage drop was attempted by using carrier lifetime enhancement processes, specifically, carbon ion implantation/annealing and thermal oxidation/annealing or hydrogen annealing. Simple PiN diodes were fabricated to demonstrate the effective conductivity modulation in the thick drift layers. The forward voltage drops of the PiN diodes with the p- and n-IGBT structures promise to obtain the extremely low-loss and very high-voltage IGBTs. The change in wafer shape during the processing of the very thick multi-layer 4H-SiC is also discussed.

  13. Progress Towards High-Sensitivity Arrays of Detectors of Sub-mm Radiation using Superconducting Tunnel Junctions with Radio-Frequency Single-Electron Transistors

    NASA Technical Reports Server (NTRS)

    Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Wollack, E. J.; Schoelkopf, R. J.; Krebs, Carolyn (Technical Monitor)

    2002-01-01

    The science drivers for the SPIRIT/SPECS missions demand sensitive, fast, compact, low-power, large-format detector arrays for high resolution imaging and spectroscopy in the far infrared and submillimeter. Detector arrays with 10,000 pixels and sensitivity less than 10(exp 20)-20 W/Hz(exp 20)0.5 are needed. Antenna-coupled superconducting tunnel junction detectors with integrated rf single-electron transistor readout amplifiers have the potential for achieving this high level of sensitivity, and can take advantage of an rf multiplexing technique when forming arrays. The device consists of an antenna structure to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure currents through tunnel junction contacts to the absorber volume. We will describe optimization of device parameters, and recent results on fabrication techniques for producing devices with high yield for detector arrays. We will also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

  14. Effect of 100MeV oxygen ion irradiation on silicon NPN power transistor

    SciTech Connect

    Kumar, M. Vinay; Krishnakumar, K. S.; Dinesh, C. M.; Krishnaveni, S.; Ramani

    2012-06-05

    The radiation response of npn Bipolar junction transistor (BJT) has been examined for 100 MeV O{sup 7+} ion. Key electrical properties like Gummel characteristics, dc current gain and capacitance-voltage of 100MeV O{sup 7+} ion irradiated transistor were studied before and after irradiation. The device was decapped and the electrical characterizations were performed at room temperature. Base current is observed to be more sensitive than collector current and gain appears to be degraded with ion fluence, also considerable degradation in C-V characteristics is observed and doping concentration is found to be increased along with the increase in ion fluence.

  15. STABILIZED TRANSISTOR AMPLIFIER

    DOEpatents

    Noe, J.B.

    1963-05-01

    A temperature stabilized transistor amplifier having a pair of transistors coupled in cascade relation that are capable of providing amplification through a temperature range of - 100 un. Concent 85% F to 400 un. Concent 85% F described. The stabilization of the amplifier is attained by coupling a feedback signal taken from the emitter of second transistor at a junction between two serially arranged biasing resistances in the circuit of the emitter of the second transistor to the base of the first transistor. Thus, a change in the emitter current of the second transistor is automatically corrected by the feedback adjustment of the base-emitter potential of the first transistor and by a corresponding change in the base-emitter potential of the second transistor. (AEC)

  16. Gallium arsenide-gallium nitride wafer fusion and the n-aluminum gallium arsenide/p-gallium arsenide/n-gallium nitride double heterojunction bipolar transistor

    NASA Astrophysics Data System (ADS)

    Estrada, Sarah M.

    This dissertation describes the n-AlGaAs/p-GaAs/n-GaN heterojunction bipolar transistor (HBT), the first transistor formed via wafer fusion. The fusion process was developed as a way to combine lattice-mismatched materials for high-performance electronic devices, not obtainable via conventional all-epitaxial formation methods. Despite the many challenges of wafer fusion, successful transistors were demonstrated and improved, via the optimization of material structure and fusion process conditions. Thus, this project demonstrated the integration of disparate device materials, chosen for their optimal electronic properties, unrestricted by the conventional (and very limiting) requirement of lattice-matching. By combining an AlGaAs-GaAs emitter-base with a GaN collector, the HBT benefited from the high breakdown voltage of GaN, and from the high emitter injection efficiency and low base transit time of AlGaAs-GaAs. Because the GaAs-GaN lattice mismatch precluded an all-epitaxial formation of the HBT, the GaAs-GaN heterostructure was formed via fusion. This project began with the development of a fusion process that formed mechanically robust and electrically active GaAs-GaN heterojunctions. During the correlation of device electrical performance with a systematic variation of fusion conditions over a wide range (500--750°C, 0.5--2hours), a mid-range fusion temperature was found to induce optimal HBT electrical performance. Transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) were used to assess possible reasons for the variations observed in device electrical performance. Fusion process conditions were correlated with electrical (I-V), structural (TEM), and chemical (SIMS) analyses of the resulting heterojunctions, in order to investigate the trade-off between increased interfacial disorder (TEM) with low fusion temperature and increased diffusion (SIMS) with high fusion temperature. The best do device results (IC ˜ 2.9 kA/cm2 and beta

  17. Design, fabrication, and performance analysis of GaN vertical electron transistors with a buried p/n junction

    SciTech Connect

    Yeluri, Ramya Lu, Jing; Keller, Stacia; Mishra, Umesh K.; Hurni, Christophe A.; Browne, David A.; Speck, James S.; Chowdhury, Srabanti

    2015-05-04

    The Current Aperture Vertical Electron Transistor (CAVET) combines the high conductivity of the two dimensional electron gas channel at the AlGaN/GaN heterojunction with better field distribution offered by a vertical design. In this work, CAVETs with buried, conductive p-GaN layers as the current blocking layer are reported. The p-GaN layer was regrown by metalorganic chemical vapor deposition and the subsequent channel regrowth was done by ammonia molecular beam epitaxy to maintain the p-GaN conductivity. Transistors with high ON current (10.9 kA/cm{sup 2}) and low ON-resistance (0.4 mΩ cm{sup 2}) are demonstrated. Non-planar selective area regrowth is identified as the limiting factor to transistor breakdown, using planar and non-planar n/p/n structures. Planar n/p/n structures recorded an estimated electric field of 3.1 MV/cm, while non-planar structures showed a much lower breakdown voltage. Lowering the p-GaN regrowth temperature improved breakdown in the non-planar n/p/n structure. Combining high breakdown voltage with high current will enable GaN vertical transistors with high power densities.

  18. A study of junction effect transistors and their roles in carbon nanotube field emission cathodes in compact pulsed power applications

    NASA Astrophysics Data System (ADS)

    Shui, Qiong

    This thesis is focusing on a study of junction effect transistors (JFETs) in compact pulsed power applications. Pulsed power usually requires switches with high hold-off voltage, high current, low forward voltage drop, and fast switching speed. 4H-SiC, with a bandgap of 3.26 eV (The bandgap of Si is 1.12eV) and other physical and electrical superior properties, has gained much attention in high power, high temperature and high frequency applications. One topic of this thesis is to evaluate if 4H-SiC JFETs have a potential to replace gas phase switches to make pulsed power system compact and portable. Some other pulsed power applications require cathodes of providing stable, uniform, high electron-beam current. So the other topic of this research is to evaluate if Si JFET-controlled carbon nanotube field emitter cold cathode will provide the necessary e-beam source. In the topic of "4H-SiC JFETs", it focuses on the design and simulation of a novel 4H-SiC normally-off VJFET with high breakdown voltage using the 2-D simulator ATLAS. To ensure realistic simulations, we utilized reasonable physical models and the established parameters as the input into these models. The influence of key design parameters were investigated which would extend pulsed power limitations. After optimizing the key design parameters, with a 50-mum drift region, the predicted breakdown voltage for the VJFET is above 8kV at a leakage current of 1x10-5A/cm2 . The specific on-state resistance is 35 mO·cm 2 at VGS = 2.7 V, and the switching speed is several ns. The simulation results suggest that the 4H-SiC VJFET is a potential candidate for improving switching performance in repetitive pulsed power applications. To evaluate the 4H-SiC VJFETs in pulsed power circuits, we extracted some circuit model parameters from the simulated I-V curves. Those parameters are necessary for circuit simulation program such as SPICE. This method could be used as a test bench without fabricating the devices to

  19. Interpreting Transistor Noise

    NASA Astrophysics Data System (ADS)

    Pospieszalski, M. W.

    2010-10-01

    The simple noise models of field effect and bipolar transistors reviewed in this article are quite useful in engineering practice, as illustrated by measured and modeled results. The exact and approximate expressions for the noise parameters of FETs and bipolar transistors reveal certain common noise properties and some general noise properties of both devices. The usefulness of these expressions in interpreting the dependence of measured noise parameters on frequency, bias, and temperature and, consequently, in checking of consistency of measured data has been demonstrated.

  20. Novel vertical hetero- and homo-junction tunnel field-effect transistors based on multi-layer 2D crystals

    NASA Astrophysics Data System (ADS)

    Lu, Shang-Chun; Mohamed, Mohamed; Zhu, Wenjuan

    2016-03-01

    Vertical hetero- and homo-junction tunnel FET (TFET) based on multi-layer black phosphorus (BP) and transition metal dichalcogenides are proposed and studied by numerical simulations employing the semi-classical density gradient quantum correction model. It is found that the vertical TFET based on BP can achieve high on-current (>200 μA μm-1) and steep subthreshold swing (average value = 24.6 mV/dec) simultaneously, due to its high mobility, direct narrow bandgap, and low dielectric constant. We also found that the on-current in vertical TFETs based on MoS2/MoSe2 hetero-junction is two orders of magnitudes higher than the one in MoS2 homo-junction TFET, due to the reduced effective bandgap in heterostructure with staggered band alignment. In addition, we present various design considerations and recommendations as well as provide a qualitative comparison with published data.

  1. Broad Beam and Ion Microprobe Studies of Single-Event Upsets in High Speed 0.18micron Silicon Germanium Heterojunction Bipolar Transistors and Circuits

    NASA Technical Reports Server (NTRS)

    Reed, Robert A.; Marshall, Paul W.; Pickel, Jim; Carts, Martin A.; Irwin, TIm; Niu, Guofu; Cressler, John; Krithivasan, Ramkumar; Fritz, Karl; Riggs, Pam

    2003-01-01

    SiGe based technology is widely recognized for its tremendous potential to impact the high speed microelectronic industry, and therefore the space industry, by monolithic incorporation of low power complementary logic with extremely high speed SiGe Heterojunction Bipolar Transistor (HBT) logic. A variety of studies have examined the ionizing dose, displacement damage and single event characteristics, and are reported. Accessibility to SiGe through an increasing number of manufacturers adds to the importance of understanding its intrinsic radiation characteristics, and in particular the single event effect (SEE) characteristics of the high bandwidth HBT based circuits. IBM is now manufacturing in its 3rd generation of their commercial SiGe processes, and access is currently available to the first two generations (known as and 6HP) through the MOSIS shared mask services with anticipated future release of the latest (7HP) process. The 5 HP process is described and is characterized by a emitter spacing of 0.5 micron and a cutoff frequency ff of 50 GHz, whereas the fully scaled 7HP HBT employs a 0.18 micron emitter and has an fT of 120 GHz. Previous investigations have the examined SEE response of 5 HP HBT circuits through both circuit testing and modeling. Charge collection modeling studies in the 5 H P process have also been conducted, but to date no measurements have been reported of charge collection in any SiGe HBT structures. Nor have circuit models for charge collection been developed in any version other than the 5 HP HBT structure. Our investigation reports the first indications of both charge collection and circuit response in IBM s 7HP-based SiGe process. We compare broad beam heavy ion SEU test results in a fully function Pseudo-Random Number (PRN) sequence generator up to frequencies of 12 Gbps versus effective LET, and also report proton test results in the same circuit. In addition, we examine the charge collection characteristics of individual 7HP HBT

  2. Bipolar Disorder

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Bipolar Disorder KidsHealth > For Teens > Bipolar Disorder Print A A ... Bipolar Disorder en español Trastorno bipolar What Is Bipolar Disorder? Bipolar disorders are one of several medical conditions ...

  3. Design consideration and fabrication of 1.2-kV 4H-SiC trenched-and-implanted vertical junction field-effect transistors

    NASA Astrophysics Data System (ADS)

    Chen, Si-Zhe; Sheng, Kuang

    2014-07-01

    We present the design consideration and fabrication of 4H-SiC trenched-and-implanted vertical junction field-effect transistors (TI-VJFETs). Different design factors, including channel width, channel doping, and mesa height, are considered and evaluated by numerical simulations. Based on the simulation result, normally-on and normally-off devices are fabricated. The fabricated device has a 12 μm thick drift layer with 8×1015 cm-3 N-type doping and 2.6 μm channel length. The normally-on device shows a 1.2 kV blocking capability with a minimum on-state resistance of 2.33 mΩ·cm2, while the normally-off device shows an on-state resistance of 3.85 mΩ·cm2. Both the on-state and the blocking performances of the device are close to the state-of-the-art values in this voltage range.

  4. Simple phenomenological modeling of transition-region capacitance of forward-biased p-n junction diodes and transistor diodes

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.

    1982-01-01

    The derivation of a simple expression for the capacitance C(V) associated with the transition region of a p-n junction under a forward bias is derived by phenomenological reasoning. The treatment of C(V) is based on the conventional Shockley equations, and simpler expressions for C(V) result that are in general accord with the previous analytical and numerical results. C(V) consists of two components resulting from changes in majority carrier concentration and from free hole and electron accumulation in the space-charge region. The space-charge region is conceived as the intrinsic region of an n-i-p structure for a space-charge region markedly wider than the extrinsic Debye lengths at its edges. This region is excited in the sense that the forward bias creates hole and electron densities orders of magnitude larger than those in equilibrium. The recent Shirts-Gordon (1979) modeling of the space-charge region using a dielectric response function is contrasted with the more conventional Schottky-Shockley modeling.

  5. Characterization, Modeling and Design Parameters Identification of Silicon Carbide Junction Field Effect Transistor for Temperature Sensor Applications

    PubMed Central

    Salah, Tarek Ben; Khachroumi, Sofiane; Morel, Hervé

    2010-01-01

    Sensor technology is moving towards wide-band-gap semiconductors providing high temperature capable devices. Indeed, the higher thermal conductivity of silicon carbide, (three times more than silicon), permits better heat dissipation and allows better cooling and temperature management. Though many temperature sensors have already been published, little endeavours have been invested in the study of silicon carbide junction field effect devices (SiC-JFET) as a temperature sensor. SiC-JFETs devices are now mature enough and it is close to be commercialized. The use of its specific properties versus temperatures is the major focus of this paper. The SiC-JFETs output current-voltage characteristics are characterized at different temperatures. The saturation current and its on-resistance versus temperature are successfully extracted. It is demonstrated that these parameters are proportional to the absolute temperature. A physics-based model is also presented. Relationships between on-resistance and saturation current versus temperature are introduced. A comparative study between experimental data and simulation results is conducted. Important to note, the proposed model and the experimental results reflect a successful agreement as far as a temperature sensor is concerned. PMID:22315547

  6. Ultra-stable oscillator with complementary transistors

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L. (Inventor)

    1974-01-01

    A high frequency oscillator, having both good short and long term stability, is formed by including a piezoelectric crystal in the base circuit of a first bi-polar transistor circuit, the bi-polar transistor itself operated below its transitional frequency and having its emitter load chosen so that the input impedance, looking into the base thereof, exhibits a negative resistance in parallel with a capacitive reactance. Combined with this basic circuit is an auxiliary, complementary, second bi-polar transistor circuit of the same form with the piezoelectric crystal being common to both circuits. By this configuration small changes in quiescent current are substantially cancelled by opposite variations in the second bi-polar transistor circuit, thereby achieving from the oscillator a signal having its frequency of oscillation stable over long time periods as well as short time periods.

  7. Optimization of Vertical Double-Diffused Metal-Oxide Semiconductor (VDMOS) Power Transistor Structure for Use in High Frequencies and Medical Devices.

    PubMed

    Farhadi, Rozita; Farhadi, Bita

    2014-01-01

    Power transistors, such as the vertical, double-diffused, metal-oxide semiconductor (VDMOS), are used extensively in the amplifier circuits of medical devices. The aim of this research was to construct a VDMOS power transistor with an optimized structure to enhance the operation of medical devices. First, boron was implanted in silicon by implanting unclamped inductive switching (UIS) and a Faraday shield. The Faraday shield was implanted in order to replace the gate-field parasitic capacitor on the entry part of the device. Also, implanting the UIS was used in order to decrease the effect of parasitic bipolar junction transistor (BJT) of the VDMOS power transistor. The research tool used in this study was Silvaco software. By decreasing the transistor entry resistance in the optimized VDMOS structure, power losses and noise at the entry of the transistor were decreased, and, by increasing the breakdown voltage, the lifetime of the VDMOS transistor lifetime was increased, which resulted in increasing drain flow and decreasing Ron. This consequently resulted in enhancing the operation of high-frequency medical devices that use transistors, such as Radio Frequency (RF) and electrocardiograph machines. PMID:25763152

  8. Bipolar disorder

    MedlinePlus

    Manic depression; Bipolar affective disorder; Mood disorder - bipolar; Manic depressive disorder ... Bipolar disorder affects men and women equally. It most often starts between ages 15 and 25. The exact ...

  9. Bipolar disorder

    MedlinePlus

    Manic depression; Bipolar affective disorder; Mood disorder - bipolar; Manic depressive disorder ... happiness and high activity or energy (mania) or depression and low activity or energy (depression). The following ...

  10. Radiation-induced 1/f noise degradation of bipolar linear voltage regulator

    NASA Astrophysics Data System (ADS)

    Qifeng, Zhao; Yiqi, Zhuang; Junlin, Bao; Wei, Hu

    2016-03-01

    Radiation-induced 1/f noise degradation in the LM117 bipolar linear voltage regulator is studied. Based on the radiation-induced degradation mechanism of the output voltage, it is suggested that the band-gap reference subcircuit is the critical component which leads to the 1/f noise degradation of the LM117. The radiation makes the base surface current of the bipolar junction transistors of the band-gap reference subcircuit increase, which leads to an increase in the output 1/f noise of the LM117. Compared to the output voltage, the 1/f noise parameter is more sensitive, it may be used to evaluate the radiation resistance capability of LM117. Project supported by the National Natural Science Foundation of China (Nos. 61076101, 61204092).

  11. Metamorphosis of the transistor into a laser

    NASA Astrophysics Data System (ADS)

    Feng, M.; Holonyak, N., Jr.

    2015-01-01

    Based on the invention and operation of the transistor, the alloy diode laser, the quantum-well diode laser and the high-speed heterojunction bipolar transistor (HBT), we have invented and realized now a transistor laser (TL). The transistor laser is a three-terminal technology providing coupling and the coherent light emission in the transistor. The quantum-well (QW) heterojunction bipolar transistor laser, inherently a fast switching device, operates by transporting a small minority base charge density ˜1016 \\text{cm}-3 over a nanoscale base thickness (<900 \\text{A}) in picoseconds. The TL, owing to its fast recombination speed, its unique three-terminal configuration, and complementary nature of its optical and electrical collector output signals, enables resonance-free base current and collector voltage modulation. It is a compact source of electro-optical applications such as nonlinear signal mixing, frequency multiplication, negative feedback, and optoelectronics logic gates.

  12. AlGaAs/GaAs/InGaAs pnp-type vertical-cavity surface-emitting transistor-lasers.

    PubMed

    Xiang, Y; Reuterskiöld-Hedlund, C; Yu, X; Yang, C; Zabel, T; Hammar, M; Akram, M N

    2015-06-15

    We report on the design, fabrication and analysis of vertical-cavity surface-emitting transistor-lasers (T-VCSELs) based on the homogeneous integration of an InGaAs/GaAs VCSEL and an AlGaAs/GaAs pnp-heterojunction bipolar transistor (HBT). Epitaxial regrowth confinement, modulation doping, intracavity contacting and non-conducting mirrors are used to ensure a low-loss structure, and a variety of design variations are investigated for a proper internal biasing and current injection to ensure a wide operating range. Optimized devices show mW-range output power, mA-range base threshold current and high-temperature operation to at least 60°C with the transistor in its active mode of operation for base currents well beyond threshold. Current confinement schemes based on pnp-blocking layers or a buried tunnel junction are investigated as well as asymmetric current injection for reduced extrinsic resistances. PMID:26193547

  13. Quantum Thermal Transistor

    NASA Astrophysics Data System (ADS)

    Joulain, Karl; Drevillon, Jérémie; Ezzahri, Younès; Ordonez-Miranda, Jose

    2016-05-01

    We demonstrate that a thermal transistor can be made up with a quantum system of three interacting subsystems, coupled to a thermal reservoir each. This thermal transistor is analogous to an electronic bipolar one with the ability to control the thermal currents at the collector and at the emitter with the imposed thermal current at the base. This is achieved by determining the heat fluxes by means of the strong-coupling formalism. For the case of three interacting spins, in which one of them is coupled to the other two, that are not directly coupled, it is shown that high amplification can be obtained in a wide range of energy parameters and temperatures. The proposed quantum transistor could, in principle, be used to develop devices such as a thermal modulator and a thermal amplifier in nanosystems.

  14. Quantum Thermal Transistor.

    PubMed

    Joulain, Karl; Drevillon, Jérémie; Ezzahri, Younès; Ordonez-Miranda, Jose

    2016-05-20

    We demonstrate that a thermal transistor can be made up with a quantum system of three interacting subsystems, coupled to a thermal reservoir each. This thermal transistor is analogous to an electronic bipolar one with the ability to control the thermal currents at the collector and at the emitter with the imposed thermal current at the base. This is achieved by determining the heat fluxes by means of the strong-coupling formalism. For the case of three interacting spins, in which one of them is coupled to the other two, that are not directly coupled, it is shown that high amplification can be obtained in a wide range of energy parameters and temperatures. The proposed quantum transistor could, in principle, be used to develop devices such as a thermal modulator and a thermal amplifier in nanosystems. PMID:27258859

  15. Study of In 0.49Ga 0.51P/GaAs/In 0.49Ga 0.51P double δ-doped heterojunction bipolar transistor

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chou; Chen, Jing-Yuh; Pan, Hsi-Jen; Feng, Shun-Ching; Yu, Kuo-Hui; Liu, Wen-Chau

    1999-07-01

    A lattice-matched In 0.49Ga 0.51P/GaAs/In 0.49Ga 0.51P double δ -doped heterojunction bipolar transistor, prepared by low-pressure metal organic chemical vapor deposition (LP-MOCVD), is fabricated successfully and reported. Due to the insertion of δ -doped sheets and setback layers both at base-emitter (B-E) and base-collector (B-C) heterojunctions, the potential spikes are suppressed significantly. In addition, the electron blocking effect is removed and a dramatic improvement of current gain is obtained. A modified Ebers-Moll model is employed to study and analyse the device performances. The experimental results show that the common-emitter current gain over 210 at the collector current of 35 mA and an offset voltage ΔVCE smaller than 50 mV are obtained. Also, a lower knee-shaped voltage of 1.4 V at the collector current of 40 mA is observed. These results indicate that the device studied is a good candidate for high-speed and high-power circuit applications.

  16. 50-200 GHz Silicon-Germanium Heterojunction Bipolar Transistor BICMOS Technology and a Computer-Aided Design Environment for 2--50+ GHz Very Large-Scale Integration Mixed-Signal ICs

    NASA Astrophysics Data System (ADS)

    Subbanna, Seshadri; Freeman, Gregory; Rieh, Jae-Sung; Ahlgren, David; Stein, Kenneth; Dickey, Carl; Mecke, James; Bacon, Peter; Groves, Robert; Meghelli, Mounir; Soyuer, Mehmet; Jagannathan, Basanth; Schonenberg, Kathryn; Jeng, Shwu-Jen; Joseph, Alvin; Coolbaugh, Douglas; Volant, Richard; Greenberg, David; Chen, Huajie; Brelsford, Kevin; Harame, David; Dunn, James; Larson, Lawrence; Herman, Dean; Meyerson, Bernard

    2002-02-01

    Silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) BICMOS technology is a stable, ultra-high performance, semiconductor technology capable of supporting mixed-signal, very large-scale integration (VLSI) circuit designs for a variety of emerging communication applications. This technology is supported by a computer-aided design (CAD) system that supports a variety of high-performance circuit designs, mixed-signal circuit block reuse, and the ability to accurately predict circuit performance at the highest frequencies. This paper summarizes the progress this technology has made in recent years in moving from the research laboratory to a production environment. We also specifically address performance, operating voltage, reliability and integration considerations for using 100--200 GHz SiGe HBTs in high-speed (10--40 Gb/s) network ICs, an application space previously only addressed by InP technology. All indications are that SiGe will be very successful at addressing this new application space, and all facets of the networking IC market.

  17. John Bardeen and transistor physics

    NASA Astrophysics Data System (ADS)

    Huff, Howard R.

    2001-01-01

    John Bardeen and Walter Brattain invented the point-contact semiconductor amplifier (transistor action) in polycrystalline germanium (also observed in polycrystalline silicon) on Dec. 15, 1947, for which they received a patent on Oct. 3, 1950. Bill Shockley was not a co-patent holder on Bardeen and Brattain's point-contact semiconductor amplifier patent since Julius Lilienfeld had already received a patent in 1930 for what would have been Shockley's contribution; namely, the field-effect methodology. Shockley received patents for both his minority-carrier injection concept and junction transistor theory, however, and deservedly shared the Nobel prize with Bardeen and Brattain for his seminal contributions of injection, p-n junction theory and junction transistor theory. We will review the events leading up to the invention of Bardeen and Brattain's point-contact semiconductor amplifier during the magic month of November 17-December 16, 1947 and the invention of Shockley's junction semiconductor amplifier during his magic month of December 24, 1947-January 23, 1948. It was during the course of Bardeen and Brattain's research in November, 1947 that Bardeen also patented the essence of the MOS transistor, wherein the induced minority carriers were confined to the inversion layer enroute to the collector. C. T. Sah has described this device as a sourceless MOS transistor. Indeed, John Bardeen, co-inventor of the point-contact semiconductor amplifier and inventor of the MOS transistor, may rightly be called the father of modern electronics.

  18. Bipolar Disorder

    MedlinePlus

    Bipolar disorder is a serious mental illness. People who have it go through unusual mood changes. They go ... The down feeling is depression. The causes of bipolar disorder aren't always clear. It runs in families. ...

  19. Simulating Single-Event Upsets in Bipolar RAM's

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.

    1986-01-01

    Simulation technique saves testing. Uses interactive version of SPICE (Simulation Program with Integrated Circuit Emphasis). Device and subcircuit models available in software used to construct macromodel for an integrated bipolar transistor. Time-dependent current generators placed inside transistor macromodel to simulate charge collection from ion track. Significant finding of experiments is standard design practice of reducing power in unaddressed bipolar RAM cell increases sensitivity of cell to single-event upsets.

  20. A review of InP/InAlAs/InGaAs based transistors for high frequency applications

    NASA Astrophysics Data System (ADS)

    Ajayan, J.; Nirmal, D.

    2015-10-01

    This paper presents an overview of the rapid progress being made in the development of InP based devices for high speed applications. Over the past few decades, major aero space industries have been developing InP based hetero structure devices like hetero junction bipolar transistors (HBTs) and high electron mobility transistors (HEMT) because of their low DC power due to excellent low voltage operation and milli-meter wave frequency performance even though its widespread use has been limited by high cost. InP based HBTs, MOSFETs and HEMTs have also been developed by commercial companies for applications in high speed fiber optic communications because InP based device technologies takes advantage of the intrinsic material properties such as high thermal conductivity, high electron mobility and low energy band gap for low voltage operation compared to silicon, silicon-germenium, and GaAs based semiconductor devices.

  1. Design considerations for FET-gated power transistors

    NASA Technical Reports Server (NTRS)

    Chen, D. Y.; Chin, S. A.

    1983-01-01

    An FET-bipolar combinational power transistor configuration (tested up to 300 V, 20 A at 100 kHz) is described. The critical parameters for integrating the chips in hybrid form are examined, and an effort to optimize the overall characteristics of the configuration is discussed. Chip considerations are examined with respect to the voltage and current rating of individual chips, the FET surge capability, the choice of triple diffused transistor or epitaxial transistor for the bipolar element, the current tailing effect, and the implementation of the bipolar transistor and an FET as single chip or separate chips. Package considerations are discussed with respect to package material and geometry, surge current capability of bipolar base terminal bonding, and power losses distribution.

  2. Evaluating the interfacial reaction kinetics of the bipolar membrane interface in the bipolar membrane fuel cell.

    PubMed

    Peng, Sikan; Lu, Shanfu; Zhang, Jin; Sui, Pang-Chieh; Xiang, Yan

    2013-07-21

    A reaction kinetic model of the bipolar membrane interface in the bipolar membrane fuel cell (BPMFC) was proposed based on the p-n junction theory and chemical reaction kinetics. It verified the self-humidification feasibility of the BPMFC successfully. PMID:23744271

  3. Control of normal and abnormal bipolar resistive switching by interface junction on In/Nb:SrTiO{sub 3} interface

    SciTech Connect

    Sun, J.; Jia, C. H.; Li, G. Q.; Zhang, W. F.

    2012-09-24

    The resistive switching behaviors of indium (In)/Nb:SrTiO{sub 3} (NSTO) with different metal/semiconductor contacts are investigated. The In electrodes with the Schottky contacts are fabricated on NSTO surface using direct current reactive magnetron sputtering, and the fresh In is directly pressed to form the Ohmic contact. The device with one Schottky barrier displays a normal bipolar resistive switching (BRS) behavior, while the device with two Schottky barriers shows an abnormal BRS behavior. The results demonstrate that the injection and trapping or detrapping of carriers near the interface between the metal electrode and semiconductor are closely related to the resistive switching performance.

  4. Metamorphic Ga0.76In0.24As/GaAs0.75Sb0.25 tunnel junctions grown on GaAs substrates

    NASA Astrophysics Data System (ADS)

    García, I.; Geisz, J. F.; France, R. M.; Kang, J.; Wei, S.-H.; Ochoa, M.; Friedman, D. J.

    2014-08-01

    Lattice-matched and pseudomorphic tunnel junctions have been developed in the past for application in a variety of semiconductor devices, including heterojunction bipolar transistors, vertical cavity surface-emitting lasers, and multijunction solar cells. However, metamorphic tunnel junctions have received little attention. In 4-junction Ga0.51In0.49P/GaAs/Ga0.76In0.24As/Ga0.47In0.53As inverted-metamorphic solar cells (4J-IMM), a metamorphic tunnel junction is required to series connect the 3rd and 4th junctions. We present a tunnel junction based on a metamorphic Ga0.76In0.24As/GaAs0.75Sb0.25 structure for this purpose. This tunnel junction is grown on a metamorphic Ga0.76In0.24As template on a GaAs substrate. The band offsets in the resulting type-II heterojunction are calculated using the first-principles density functional method to estimate the tunneling barrier height and assess the performance of this tunnel junction against other material systems and compositions. The effect of the metamorphic growth on the performance of the tunnel junctions is analyzed using a set of metamorphic templates with varied surface roughness and threading dislocation density. Although the metamorphic template does influence the tunnel junction performance, all tunnel junctions measured have a peak current density over 200 A/cm2. The tunnel junction on the best template has a peak current density over 1500 A/cm2 and a voltage drop at 15 A/cm2 (corresponding to operation at 1000 suns) lower than 10 mV, which results in a nearly lossless series connection of the 4th junction in the 4J-IMM structure.

  5. Method for double-sided processing of thin film transistors

    DOEpatents

    Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.; Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang

    2008-04-08

    This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

  6. Neurons from rat brain coupled to transistors

    NASA Astrophysics Data System (ADS)

    Vassanelli, S.; Fromherz, P.

    Field-effect transistors form spontaneously capacitive junctions with cultured nerve cells from rat brains. The transfer of ac signals from neurons to silicon is studied and used to parametrize an equivalent circuit. The coupling is distinctly weaker than in junctions assembled with leech nerve cells. The implications with respect to the recording and stimulation of neuronal activity by silicon devices are considered.

  7. Bipolar Disorder.

    ERIC Educational Resources Information Center

    Spearing, Melissa

    Bipolar disorder, a brain disorder that causes unusual shifts in a person's mood, affects approximately one percent of the population. It commonly occurs in late adolescence and is often unrecognized. The diagnosis of bipolar disorder is made on the basis of symptoms, course of illness, and when possible, family history. Thoughts of suicide are…

  8. Bipolar Disorder

    MedlinePlus

    ... or digestive problems Problems sleeping, or wanting to sleep all of the time Feeling tired all of the time Thoughts about death and suicide Causes & Risk Factors What causes bipolar disorder? Bipolar disorder may be caused by a chemical imbalance in the brain. It sometimes runs in ...

  9. Bipolar disorder.

    PubMed

    Grande, Iria; Berk, Michael; Birmaher, Boris; Vieta, Eduard

    2016-04-01

    Bipolar disorder is a recurrent chronic disorder characterised by fluctuations in mood state and energy. It affects more than 1% of the world's population irrespective of nationality, ethnic origin, or socioeconomic status. Bipolar disorder is one of the main causes of disability among young people, leading to cognitive and functional impairment and raised mortality, particularly death by suicide. A high prevalence of psychiatric and medical comorbidities is typical in affected individuals. Accurate diagnosis of bipolar disorder is difficult in clinical practice because onset is most commonly a depressive episode and looks similar to unipolar depression. Moreover, there are currently no valid biomarkers for the disorder. Therefore, the role of clinical assessment remains key. Detection of hypomanic periods and longitudinal assessment are crucial to differentiate bipolar disorder from other conditions. Current knowledge of the evolving pharmacological and psychological strategies in bipolar disorder is of utmost importance. PMID:26388529

  10. Electronic Model of a Ferroelectric Field Effect Transistor

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd C.; Ho, Fat Duen; Russell, Larry (Technical Monitor)

    2001-01-01

    A pair of electronic models has been developed of a Ferroelectric Field Effect transistor. These models can be used in standard electrical circuit simulation programs to simulate the main characteristics of the FFET. The models use the Schmitt trigger circuit as a basis for their design. One model uses bipolar junction transistors and one uses MOSFET's. Each model has the main characteristics of the FFET, which are the current hysterisis with different gate voltages and decay of the drain current when the gate voltage is off. The drain current from each model has similar values to an actual FFET that was measured experimentally. T'he input and o Output resistance in the models are also similar to that of the FFET. The models are valid for all frequencies below RF levels. No attempt was made to model the high frequency characteristics of the FFET. Each model can be used to design circuits using FFET's with standard electrical simulation packages. These circuits can be used in designing non-volatile memory circuits and logic circuits and is compatible with all SPICE based circuit analysis programs. The models consist of only standard electrical components, such as BJT's, MOSFET's, diodes, resistors, and capacitors. Each model is compared to the experimental data measured from an actual FFET.

  11. Chirality effect in disordered graphene ribbon junctions

    NASA Astrophysics Data System (ADS)

    Long, Wen

    2012-05-01

    We investigate the influence of edge chirality on the electronic transport in clean or disordered graphene ribbon junctions. By using the tight-binding model and the Landauer-Büttiker formalism, the junction conductance is obtained. In the clean sample, the zero-magnetic-field junction conductance is strongly chirality-dependent in both unipolar and bipolar ribbons, whereas the high-magnetic-field conductance is either chirality-independent in the unipolar or chirality-dependent in the bipolar ribbon. Furthermore, we study the disordered sample in the presence of magnetic field and find that the junction conductance is always chirality-insensitive for both unipolar and bipolar ribbons with adequate disorders. In addition, the disorder-induced conductance plateaus can exist in all chiral bipolar ribbons provided the disorder strength is moderate. These results suggest that we can neglect the effect of edge chirality in fabricating electronic devices based on the magnetotransport in a disordered graphene ribbon.

  12. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

    PubMed Central

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-01-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits. PMID:27491391

  13. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

    NASA Astrophysics Data System (ADS)

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-08-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits.

  14. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal.

    PubMed

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-01-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature 'prototype' PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits. PMID:27491391

  15. Multimode silicon nanowire transistors.

    PubMed

    Glassner, Sebastian; Zeiner, Clemens; Periwal, Priyanka; Baron, Thierry; Bertagnolli, Emmerich; Lugstein, Alois

    2014-11-12

    The combined capabilities of both a nonplanar design and nonconventional carrier injection mechanisms are subject to recent scientific investigations to overcome the limitations of silicon metal oxide semiconductor field effect transistors. In this Letter, we present a multimode field effect transistors device using silicon nanowires that feature an axial n-type/intrinsic doping junction. A heterostructural device design is achieved by employing a self-aligned nickel-silicide source contact. The polymorph operation of the dual-gate device enabling the configuration of one p- and two n-type transistor modes is demonstrated. Not only the type but also the carrier injection mode can be altered by appropriate biasing of the two gate terminals or by inverting the drain bias. With a combined band-to-band and Schottky tunneling mechanism, in p-type mode a subthreshold swing as low as 143 mV/dec and an ON/OFF ratio of up to 10(4) is found. As the device operates in forward bias, a nonconventional tunneling transistor is realized, enabling an effective suppression of ambipolarity. Depending on the drain bias, two different n-type modes are distinguishable. The carrier injection is dominated by thermionic emission in forward bias with a maximum ON/OFF ratio of up to 10(7) whereas in reverse bias a Schottky tunneling mechanism dominates the carrier transport. PMID:25303290

  16. Bipolar Disorder

    MedlinePlus

    ... health professional before making a commitment. Learn More Free Booklets and Brochures Bipolar Disorder: A brochure on ... in the public domain and available for use free of charge. Citation of the NIMH is appreciated. ...

  17. Bipolar battery

    DOEpatents

    Kaun, Thomas D.

    1992-01-01

    A bipolar battery having a plurality of cells. The bipolar battery includes: a negative electrode; a positive electrode and a separator element disposed between the negative electrode and the positive electrode, the separator element electrically insulating the electrodes from one another; an electrolyte disposed within at least one of the negative electrode, the positive electrode and the separator element; and an electrode containment structure including a cup-like electrode holder.

  18. Modeling of single-event upset in bipolar integrated circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.

    1983-01-01

    The results of work done on the quantitative characterization of single-event upset (SEU) in bipolar random-access memories (RAMs) have been obtained through computer simulation of SEU in RAM cells that contain circuit models for bipolar transistors. The models include current generators that emulate the charge collected from ion tracks. The computer simulation results are compared with test data obtained from a RAM in a bipolar microprocessor chip. This methodology is applicable to other bipolar integrated circuit constructions in addition to RAM cells.

  19. Theoretical calculation of performance enhancement in lattice-matched SiGeSn/GeSn p-channel tunneling field-effect transistor with type-II staggered tunneling junction

    NASA Astrophysics Data System (ADS)

    Wang, Hongjuan; Han, Genquan; Wang, Yibo; Peng, Yue; Liu, Yan; Zhang, Chunfu; Zhang, Jincheng; Hu, Shengdong; Hao, Yue

    2016-04-01

    In this work, a lattice-matched SiGeSn/GeSn heterostructure p-channel tunneling field-effect transistor (hetero-PTFET) with a type-II staggered tunneling junction (TJ) is investigated theoretically. Lattice matching and type-II band alignment at the Γ-point is obtained at the SiGeSn/GeSn interface by tuning Sn and Si compositions. A steeper subthreshold swing (SS) and a higher on state current (I ON) are demonstrated in SiGeSn/GeSn hetero-PTFET than in GeSn homo-PTFET. Si0.31Ge0.49Sn0.20/Ge0.88Sn0.12 hetero-PTFET achieves a 2.3-fold higher I ON than Ge0.88Sn0.12 homo-PTFET at V DD of 0.3 V. Hetero-PTFET achieves a more abrupt hole profile and a higher carrier density near TJ than the homo-PTFET, which contributes to the significantly enhanced band-to-band tunneling (BTBT) rate and tunneling current in hetero-PTFET.

  20. Carbon nanotube intramolecular junctions

    NASA Astrophysics Data System (ADS)

    Yao, Zhen; Postma, Henk W. Ch.; Balents, Leon; Dekker, Cees

    1999-11-01

    The ultimate device miniaturization would be to use individual molecules as functional devices. Single-wall carbon nanotubes (SWNTs) are promising candidates for achieving this: depending on their diameter and chirality, they are either one-dimensional metals or semiconductors. Single-electron transistors employing metallic nanotubes and field-effect transistors employing semiconducting nanotubes have been demonstrated. Intramolecular devices have also been proposed which should display a range of other device functions. For example, by introducing a pentagon and a heptagon into the hexagonal carbon lattice, two tube segments with different atomic and electronic structures can be seamlessly fused together to create intramolecular metal-metal, metal-semiconductor, or semiconductor-semiconductor junctions. Here we report electrical transport measurements on SWNTs with intramolecular junctions. We find that a metal-semiconductor junction behaves like a rectifying diode with nonlinear transport characteristics that are strongly asymmetric with respect to bias polarity. In the case of a metal-metal junction, the conductance appears to be strongly suppressed and it displays a power-law dependence on temperatures and applied voltage, consistent with tunnelling between the ends of two Luttinger liquids. Our results emphasize the need to consider screening and electron interactions when designing and modelling molecular devices. Realization of carbon-based molecular electronics will require future efforts in the controlled production of these intramolecular nanotube junctions.

  1. Bipolar disorder

    PubMed Central

    Goodwin, Frederick K.; Ghaemi, S. Nassir

    1999-01-01

    Bipolar disorder's unique combination of three characteristics - clear genetic diathesis, distinctive clinical features, early availability of an effective treatment (lithium) - explains its special place in the history of psychiatry and its contribution to the current explosive growth of neuroscience. This article looks at the state of the art in bipolar disorder from the vantage point of: (i) genetics (possible linkages on chromosomes 18 and 21q, polygenic hypothesis, research into genetic markers); (ii) diagnosis (new focus on the subjective aspects of bipolar disorder to offset the current trend of underdiagnosis due to overreliance on standardized interviews and rating scales); (iii) outcome (increase in treatment-resistant forms signaling a change in the natural history of bipolar disorder); (iv) pathophysiology (research into circadian biological rhythms and the kindling hypothesis to explain recurrence); (v) treatment (emergence of the anticonvulsants, suggested role of chronic antidepressant treatment in the development of treatment resistance); (vi) neurobiology (evaluation of regulatory function in relation to affective disturbances, role of postsynaptic second-messenger mechanisms, advances in functional neuroimaging); and (vii) psychosocial research (shedding overly dualistic theories of the past to understand the mind and brain as an entity, thus emphasizing the importance of balancing the psychopharmacological and psychotherapeutic approaches). Future progress in the understanding and treatment of bipolar disorder will rely on successful integration of the biological and psychosocial lines of investigation. PMID:22033232

  2. Gate protective device for insulated gate field-effect transistors

    NASA Technical Reports Server (NTRS)

    Sunshine, R. A.

    1972-01-01

    Device, which protects insulated gate field-effect transistors, improves reliability through utilization of layers of conductive material on top of each alternating semiconductor material region. Separation of layers is necessary to prevent shorting out junctions between alternating regions.

  3. Bipolar Disorder

    MedlinePlus

    ... might cause your mood changes. If not treated, bipolar disorder can lead to damaged relationships, poor job or school performance, and even suicide. However, there are effective treatments to control symptoms: medicine and talk therapy. A combination usually works best. NIH: National Institute ...

  4. Analysis of long-channel nanotube field-effect-transistors (NT FETs)

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Kwak, Dochan (Technical Monitor)

    2001-01-01

    This viewgraph presentation provides an analysis of long-channel nanotube (NT) field effect transistors (FET) from NASA's Ames Research Center. The structure of such a transistor including the electrode contact, 1D junction, and the planar junction is outlined. Also mentioned are various characteristics of a nanotube tip-equipped scanning tunnel microscope (STM).

  5. Transistor Effect in Improperly Connected Transistors.

    ERIC Educational Resources Information Center

    Luzader, Stephen; Sanchez-Velasco, Eduardo

    1996-01-01

    Discusses the differences between the standard representation and a realistic representation of a transistor. Presents an experiment that helps clarify the explanation of the transistor effect and shows why transistors should be connected properly. (JRH)

  6. An improved trench gate super-junction IGBT with double emitter

    NASA Astrophysics Data System (ADS)

    Weinan, Dai; Jing, Zhu; Weifeng, Sun; Yicheng, Du; Keqin, Huang

    2015-01-01

    An improved trench gate super-junction insulated-gate bipolar transistor is presented. The improved structure contains two emitter regions. The first emitter region of the device works as the conventional structure, which can absorb both the electron current and hole current. The second emitter on the top of the p-pillar acts as the hole current diverter, leading to an improved latch-up capability without sacrificing the off-state breakdown voltage (BV) and turn-off loss. The simulation shows that the latch-up limit of the SJ-IGBT increases from 15000 to 28300 A/cm2 at VGE = 10 V, the BV is 810 V, and the turn off loss is 6.5 mJ/cm2 at Von = 1.2 V.

  7. Bipolar electrochemistry.

    PubMed

    Fosdick, Stephen E; Knust, Kyle N; Scida, Karen; Crooks, Richard M

    2013-09-27

    A bipolar electrode (BPE) is an electrically conductive material that promotes electrochemical reactions at its extremities (poles) even in the absence of a direct ohmic contact. More specifically, when sufficient voltage is applied to an electrolyte solution in which a BPE is immersed, the potential difference between the BPE and the solution drives oxidation and reduction reactions. Because no direct electrical connection is required to activate redox reactions, large arrays of electrodes can be controlled with just a single DC power supply or even a battery. The wireless aspect of BPEs also makes it possible to electrosynthesize and screen novel materials for a wide variety of applications. Finally, bipolar electrochemistry enables mobile electrodes, dubbed microswimmers, that are able to move freely in solution. PMID:23843205

  8. Types of Bipolar Disorder

    MedlinePlus

    ... Research Studies Peer Support Research WeSearchTogether Types of Bipolar Disorder There are several kinds of bipolar disorder. Each ... like an illness. What is the difference between bipolar disorder and ordinary mood swings? The three main things ...

  9. Bipolar-Battery Construction

    NASA Technical Reports Server (NTRS)

    Rippel, Wally E.; Edwards, Dean B.

    1988-01-01

    Bipolar batteries fabricated in continuous quasi-automated process. Components of battery configured so processing steps run sequentially. Key components of battery, bipolar plate and bipolar separator, fabricated separately and later joined together.

  10. A model-base comparison - GaAs/GaAlAs HBT versus silicon bipolar

    NASA Astrophysics Data System (ADS)

    Kurata, M.; Katoh, R.; Yoshida, J.; Akagi, J.

    1986-10-01

    A pure model-base comparison is made between the GaAs/GaAlAs heterojunction bipolar transistor and the silicon bipolar transistor for the high-speed switching performance under ring oscillator operation. Full utilization is made of the earlier developed (Kurata et al., 1984 and 1985) modeling tools, which include a 'physical' one-dimensional transistor model, a hybrid model to represent a realistic device structure, and a circuit simulator to allow direct access to the physical model. Delay time versus power characteristics, as well as dynamic carrier profiles are demonstrated, with discussion about limiting factors for the switching speed.

  11. Total Dose Effects on Bipolar Integrated Circuits at Low Temperature

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.; Swimm, R. T.; Thorbourn, D. O.

    2012-01-01

    Total dose damage in bipolar integrated circuits is investigated at low temperature, along with the temperature dependence of the electrical parameters of internal transistors. Bandgap narrowing causes the gain of npn transistors to decrease far more at low temperature compared to pnp transistors, due to the large difference in emitter doping concentration. When irradiations are done at temperatures of -140 deg C, no damage occurs until devices are warmed to temperatures above -50 deg C. After warm-up, subsequent cooling shows that damage is then present at low temperature. This can be explained by the very strong temperature dependence of dispersive transport in the continuous-time-random-walk model for hole transport. For linear integrated circuits, low temperature operation is affected by the strong temperature dependence of npn transistors along with the higher sensitivity of lateral and substrate pnp transistors to radiation damage.

  12. Switching Transistor

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Westinghouse Electric Corporation's D60T transistors are used primarily as switching devices for controlling high power in electrical circuits. It enables reduction in the number and size of circuit components and promotes more efficient use of energy. Wide range of application from a popcorn popper to a radio frequency generator for solar cell production.

  13. Comparison of the degradation effects of heavy ion, electron, and cobalt-60 irradiation in an advanced bipolar process

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Goben, Charles A.; Berndt, Dale F.

    1988-01-01

    Experimental measurements are reported of the degradation effects of high-energy particles (heavy Br ions and electrons) and Co-60 gamma-rays on the current gain of minimum-geometry bipolar transistors made from an advanced process. The data clearly illustrate the total-ionizing-dose vs particle-fluence behavior of this bipolar transistor produced by an advanced process. In particular, bulk damage from Co-60 gamma rays in bipolar transistors (base transport factor degradation) and surface damage in bipolar transistors from ionizing radiation (emitter-efficiency degradation) have been observed. The true equivalence between various types of radiation for this process technology has been determined on the basis of damage from the log K1 intercepts.

  14. A simplified boron diffusion for preparing the silicon single crystal p-n junction as an educational device

    NASA Astrophysics Data System (ADS)

    Shiota, Koki; Kai, Kazuho; Nagaoka, Shiro; Tsuji, Takuto; Wakahara, Akihiro; Rusop, Mohamad

    2016-07-01

    The educational method which is including designing, making, and evaluating actual semiconductor devices with learning the theory is one of the best way to obtain the fundamental understanding of the device physics and to cultivate the ability to make unique ideas using the knowledge in the semiconductor device. In this paper, the simplified Boron thermal diffusion process using Sol-Gel material under normal air environment was proposed based on simple hypothesis and the feasibility of the reproducibility and reliability were investigated to simplify the diffusion process for making the educational devices, such as p-n junction, bipolar and pMOS devices. As the result, this method was successfully achieved making p+ region on the surface of the n-type silicon substrates with good reproducibility. And good rectification property of the p-n junctions was obtained successfully. This result indicates that there is a possibility to apply on the process making pMOS or bipolar transistors. It suggests that there is a variety of the possibility of the applications in the educational field to foster an imagination of new devices.

  15. Distributed-Channel Bipolar Device: Experimentation, Analytical Modeling and Applications.

    NASA Astrophysics Data System (ADS)

    Jiang, Fenglai

    Experimental results and theoretical modeling for four terminal distributed channel bipolar devices (DCBD) are presented. The DCBD device is comprised of an interwoven BJT and MOSFET. The device may be characterized as a MOSFET with a bipolar transistor source distributed under the MOSFET channel. Alternatively, the device may be represented as a BJT where a MOSFET channel provides the current collection function. The physical layout of the device is that of a n-channel MOSFET placed above a p-Si epitaxial base region which was grown on an n^+-Si substrate emitter. Distributed electronic behavior exhibits itself through self-biasing influences of the channel-collected current on the channel-base junction bias. For appropriate biasing, the MOSFET channel divides itself into two regions exhibiting forward active and saturation BJT behavior. Both experimental results and theoretical modeling are provided. Experimental results for "large area" rectangular gate, circular gate and trapezoidal gate DCBD are reported. The experimental results exhibit the transconductance threshold voltage, beta fall off and transconductance fall-off features reported previously by others. A "large area" trapezoidal gate structure is incorporated to illustrate the gate area influences on the electrical characteristics and to provide a model sensitive structure for evaluating the validity of the theory developed in the dissertation. An analytical model based on conventional MOSFET and bipolar theories is developed. The analytical model is applied to the large gate area devices (example: 0.127 mm rectangular gate length) and smaller dimensional gate devices down to 0.9 micron rectangular gate length. The theoretical results show good agreement with the large gate area experimental results. Application examples are provided. The use of the base current invariant transconductance threshold voltage as a reference voltage is discussed. Comparison of the transconductance threshold voltage

  16. A Heteroepitaxial Perovskite Metal-Base Transistor

    SciTech Connect

    Yajima, T.; Hikita, Y.; Hwang, H.Y.; /Tokyo U. /JST, PRESTO /SLAC

    2011-08-11

    'More than Moore' captures a concept for overcoming limitations in silicon electronics by incorporating new functionalities in the constituent materials. Perovskite oxides are candidates because of their vast array of physical properties in a common structure. They also enable new electronic devices based on strongly-correlated electrons. The field effect transistor and its derivatives have been the principal oxide devices investigated thus far, but another option is available in a different geometry: if the current is perpendicular to the interface, the strong internal electric fields generated at back-to-back heterojunctions can be used for oxide electronics, analogous to bipolar transistors. Here we demonstrate a perovskite heteroepitaxial metal-base transistor operating at room temperature, enabled by interface dipole engineering. Analysis of many devices quantifies the evolution from hot-electron to permeable-base behaviour. This device provides a platform for incorporating the exotic ground states of perovskite oxides, as well as novel electronic phases at their interfaces.

  17. The bipolar silicon microstrip detector: A proposal for a novel precision tracking device

    NASA Astrophysics Data System (ADS)

    Horisberger, R.

    1990-03-01

    It is proposed to combine the technology of fully depleted silicon microstrip detectors fabricated on n doped high resistivity silicon with the concept of the bipolar transistor. This is done by adding a n ++ doped region inside the normal p + implanted region of the reverse biased p + n diode. Teh resulting structure has amplifying properties and is referred to as bipolar pixel transistor. The simplest readout scheme of a bipolar pixel array by an aluminium strip bus leads to the bipolar microstrip detector. The bipolar pixel structure is expected to give a better signal-to-noise performance for the detection of minimum ionizing charged particle tracks than the normal silicon diode strip detector and therefore should allow in future the fabrication of thinner silicon detectors for precision tracking.

  18. Principles of an atomtronic transistor

    NASA Astrophysics Data System (ADS)

    Caliga, Seth C.; Straatsma, Cameron J. E.; Zozulya, Alex A.; Anderson, Dana Z.

    2016-01-01

    A semiclassical formalism is used to investigate the transistor-like behavior of ultracold atoms in a triple-well potential. Atom current flows from the source well, held at fixed chemical potential and temperature, into an empty drain well. In steady-state, the gate well located between the source and drain is shown to acquire a well-defined chemical potential and temperature, which are controlled by the relative height of the barriers separating the three wells. It is shown that the gate chemical potential can exceed that of the source and have a lower temperature. In electronics terminology, the source-gate junction can be reverse-biased. As a result, the device exhibits regimes of negative resistance and transresistance, indicating the presence of gain. Given an external current input to the gate, transistor-like behavior is characterized both in terms of the current gain, which can be greater than unity, and the power output of the device.

  19. Characteristics of superconducting flux-flow transistors

    SciTech Connect

    Hohenwarter, G.K.G. ); Martens, J.S.; Thompson, J.H.; Beyer, J.B.; Nordman, J.E. . Dept. of Electrical and Computer Engineering); Ginley, D.S. )

    1991-03-01

    This paper compares the operational characteristics and physics of three superconducting thin-film based transistor structures. The devices are based on the motion of quantized vortices, either Josephson fluxons in a long tunnel junction or Abrikosov fluxons in a superconducting film. The transistor amplification mechanism, in all three cases, is accomplished by controlling magnetic field at the boundaries of the structure. This paper provides an overview of present understanding of device mechanisms and of measured characteristics, including voltampere relations and small and large signal circuit parameters. Demonstrated applications and anticipated limitations are discussed.

  20. Parasitic bipolar effect in ultra-thin FD SOI MOSFETs

    NASA Astrophysics Data System (ADS)

    Liu, F. Y.; Ionica, I.; Bawedin, M.; Cristoloveanu, S.

    2015-10-01

    The parasitic bipolar effect is investigated in fully-depleted silicon-on-insulator (FD SOI) n-type MOSFETs with ultra-thin films (5-10 nm). Our measurements show that at low drain bias the drain leakage current is governed by the gate current. Beyond VD > 1.0 V, leakage current amplification is observed in short-channel 10-nm thick devices. With film thickness shrinking, the current amplification is suppressed. We explain this amplification by the turn-on of the lateral parasitic bipolar transistor. TCAD simulations confirm that the parasitic bipolar is activated due to holes generated by band-to-band tunneling at the drain side and accumulated in the floating body. An effective method for the extraction of bipolar gain is proposed based on the comparison of leakage current in short- and long-channel devices. The experimental method is validated through simulations.

  1. Bipolar offspring: a window into bipolar disorder evolution.

    PubMed

    Chang, Kiki; Steiner, Hans; Dienes, Kimberly; Adleman, Nancy; Ketter, Terence

    2003-06-01

    Children of parents with bipolar disorder (bipolar offspring) represent a rich cohort for study with potential for illumination of prodromal forms of bipolar disorder. Due to their high-risk nature, bipolar offspring may present phenomenological, temperamental, and biological clues to early presentations of bipolar disorder. This article reviews the evidence for establishing bipolar offspring as a high-risk cohort, the studies which point to possible prodromal states in bipolar offspring, biological findings in bipolar offspring which may be indicators of even higher risk for bipolar disorder, initial attempts at early intervention in prodromal pediatric bipolar disorder, and implications for future research. PMID:12788239

  2. Help With Bipolar Disorders

    MedlinePlus

    ... a Psychiatrist Patients & Families All Topics Help With Bipolar Disorders Curated and updated for the community by APA Topic Information Bipolar disorders are brain disorders that cause changes in a ...

  3. Experimental synchronization of chaos in a large ring of mutually coupled single-transistor oscillators: Phase, amplitude, and clustering effects

    SciTech Connect

    Minati, Ludovico E-mail: ludovico.minati@unitn.it

    2014-12-01

    In this paper, experimental evidence of multiple synchronization phenomena in a large (n = 30) ring of chaotic oscillators is presented. Each node consists of an elementary circuit, generating spikes of irregular amplitude and comprising one bipolar junction transistor, one capacitor, two inductors, and one biasing resistor. The nodes are mutually coupled to their neighbours via additional variable resistors. As coupling resistance is decreased, phase synchronization followed by complete synchronization is observed, and onset of synchronization is associated with partial synchronization, i.e., emergence of communities (clusters). While component tolerances affect community structure, the general synchronization properties are maintained across three prototypes and in numerical simulations. The clusters are destroyed by adding long distance connections with distant notes, but are otherwise relatively stable with respect to structural connectivity changes. The study provides evidence that several fundamental synchronization phenomena can be reliably observed in a network of elementary single-transistor oscillators, demonstrating their generative potential and opening way to potential applications of this undemanding setup in experimental modelling of the relationship between network structure, synchronization, and dynamical properties.

  4. Nanotube junctions

    DOEpatents

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon; Zettl, Alexander Karlwalte

    2004-12-28

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  5. Nanotube junctions

    DOEpatents

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon Sheng; Zettl, Alexander Karlwalter

    2003-01-01

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  6. Nutrition and Bipolar Depression.

    PubMed

    Beyer, John L; Payne, Martha E

    2016-03-01

    As with physical conditions, bipolar disorder is likely to be impacted by diet and nutrition. Patients with bipolar disorder have been noted to have relatively unhealthy diets, which may in part be the reason they also have an elevated risk of metabolic syndrome and obesity. An improvement in the quality of the diet should improve a bipolar patient's overall health risk profile, but it may also improve their psychiatric outcomes. New insights into biological dysfunctions that may be present in bipolar disorder have presented new theoretic frameworks for understanding the relationship between diet and bipolar disorder. PMID:26876319

  7. NANOELECTRONICS. Epitaxial growth of a monolayer WSe2-MoS2 lateral p-n junction with an atomically sharp interface.

    PubMed

    Li, Ming-Yang; Shi, Yumeng; Cheng, Chia-Chin; Lu, Li-Syuan; Lin, Yung-Chang; Tang, Hao-Lin; Tsai, Meng-Lin; Chu, Chih-Wei; Wei, Kung-Hwa; He, Jr-Hau; Chang, Wen-Hao; Suenaga, Kazu; Li, Lain-Jong

    2015-07-31

    Two-dimensional transition metal dichalcogenides (TMDCs) such as molybdenum sulfide MoS2 and tungsten sulfide WSe2 have potential applications in electronics because they exhibit high on-off current ratios and distinctive electro-optical properties. Spatially connected TMDC lateral heterojunctions are key components for constructing monolayer p-n rectifying diodes, light-emitting diodes, photovoltaic devices, and bipolar junction transistors. However, such structures are not readily prepared via the layer-stacking techniques, and direct growth favors the thermodynamically preferred TMDC alloys. We report the two-step epitaxial growth of lateral WSe2-MoS2 heterojunction, where the edge of WSe2 induces the epitaxial MoS2 growth despite a large lattice mismatch. The epitaxial growth process offers a controllable method to obtain lateral heterojunction with an atomically sharp interface. PMID:26228146

  8. Transport in Carbon Nanotube Junctions

    NASA Astrophysics Data System (ADS)

    Khoo, K. H.; Chelikowsky, James R.

    2008-03-01

    There is growing interest in the use of carbon nanotube thin films as transparent electrical conductors and thin-film transistors owing to their high optical transmittance, low sheet resistivity, and ease of fabrication. [1,2] A major contribution to the sheet resistivity originates at nanotube junctions, as electrical contact is typically poor between adjacent nanotubes. It is thus important to characterize carbon nanotube junctions in order to understand the conduction properties of nanotube thin films. To this end, we have performed ab initio density functional theory calculations to investigate the structural, electronic and transport properties of carbon nanotube junctions as a function of nanotube chirality and contact geometry [1] Z. Wu et al., Science 305, 1273 (2004) [2] E. S. Snow, J. P. Novak, P. M. Campbell, and D. Park, Appl. Phys. Lett. 82, 2145 (2003).

  9. Graphene-porphyrin single-molecule transistors

    NASA Astrophysics Data System (ADS)

    Mol, Jan A.; Lau, Chit Siong; Lewis, Wilfred J. M.; Sadeghi, Hatef; Roche, Cecile; Cnossen, Arjen; Warner, Jamie H.; Lambert, Colin J.; Anderson, Harry L.; Briggs, G. Andrew D.

    2015-07-01

    We demonstrate a robust graphene-molecule-graphene transistor architecture. We observe remarkably reproducible single electron charging, which we attribute to insensitivity of the molecular junction to the atomic configuration of the graphene electrodes. The stability of the graphene electrodes allow for high-bias transport spectroscopy and the observation of multiple redox states at room-temperature.We demonstrate a robust graphene-molecule-graphene transistor architecture. We observe remarkably reproducible single electron charging, which we attribute to insensitivity of the molecular junction to the atomic configuration of the graphene electrodes. The stability of the graphene electrodes allow for high-bias transport spectroscopy and the observation of multiple redox states at room-temperature. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR03294F

  10. Experimental determination of single-event upset (SEU) as a function of collected charge in bipolar integrated circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Malone, C. J.; Smith, L. S.

    1984-01-01

    Single-Event Upset (SEU) in bipolar integrated circuits (ICs) is caused by charge collection from ion tracks in various regions of a bipolar transistor. This paper presents experimental data which have been obtained wherein the range-energy characteristics of heavy ions (Br) have been utilized to determine the cross section for soft-error generation as a function of charge collected from single-particle tracks which penetrate a bipolar static RAM. The results of this work provide a basis for the experimental verification of circuit-simulation SEU modeling in bipolar ICs.

  11. Josephson junction

    DOEpatents

    Wendt, Joel R.; Plut, Thomas A.; Martens, Jon S.

    1995-01-01

    A novel method for fabricating nanometer geometry electronic devices is described. Such Josephson junctions can be accurately and reproducibly manufactured employing photolithographic and direct write electron beam lithography techniques in combination with aqueous etchants. In particular, a method is described for manufacturing planar Josephson junctions from high temperature superconducting material.

  12. Josephson junction

    DOEpatents

    Wendt, J.R.; Plut, T.A.; Martens, J.S.

    1995-05-02

    A novel method for fabricating nanometer geometry electronic devices is described. Such Josephson junctions can be accurately and reproducibly manufactured employing photolithographic and direct write electron beam lithography techniques in combination with aqueous etchants. In particular, a method is described for manufacturing planar Josephson junctions from high temperature superconducting material. 10 figs.

  13. Bimetallic junctions

    NASA Technical Reports Server (NTRS)

    Arcella, F. G.; Lessmann, G. G.; Lindberg, R. A. (Inventor)

    1977-01-01

    The formation of voids through interdiffusion in bimetallic welded structures exposed to high operating temperatures is inhibited by utilizing an alloy of the parent materials in the junction of the parent materials or by preannealing the junction at an ultrahigh temperature. These methods are also used to reduce the concentration gradient of a hardening agent.

  14. High-performance silicon nanowire bipolar phototransistors

    NASA Astrophysics Data System (ADS)

    Tan, Siew Li; Zhao, Xingyan; Chen, Kaixiang; Crozier, Kenneth B.; Dan, Yaping

    2016-07-01

    Silicon nanowires (SiNWs) have emerged as sensitive absorbing materials for photodetection at wavelengths ranging from ultraviolet (UV) to the near infrared. Most of the reports on SiNW photodetectors are based on photoconductor, photodiode, or field-effect transistor device structures. These SiNW devices each have their own advantages and trade-offs in optical gain, response time, operating voltage, and dark current noise. Here, we report on the experimental realization of single SiNW bipolar phototransistors on silicon-on-insulator substrates. Our SiNW devices are based on bipolar transistor structures with an optically injected base region and are fabricated using CMOS-compatible processes. The experimentally measured optoelectronic characteristics of the SiNW phototransistors are in good agreement with simulation results. The SiNW phototransistors exhibit significantly enhanced response to UV and visible light, compared with typical Si p-i-n photodiodes. The near infrared responsivities of the SiNW phototransistors are comparable to those of Si avalanche photodiodes but are achieved at much lower operating voltages. Compared with other reported SiNW photodetectors as well as conventional bulk Si photodiodes and phototransistors, the SiNW phototransistors in this work demonstrate the combined advantages of high gain, high photoresponse, low dark current, and low operating voltage.

  15. High-Gain AlxGa1-xAs/GaAs Transistors For Neural Networks

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Hoon; Lin, Steven H.

    1991-01-01

    High-gain AlxGa1-xAs/GaAs npn double heterojunction bipolar transistors developed for use as phototransistors in optoelectronic integrated circuits, especially in artificial neural networks. Transistors perform both photodetection and saturating-amplification functions of neurons. Good candidates for such application because structurally compatible with laser diodes and light-emitting diodes, detect light, and provide high current gain needed to compensate for losses in holographic optical elements.

  16. Gap Junctions

    PubMed Central

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  17. Comparison of bipolar and unipolar ionic diodes

    SciTech Connect

    Vlassiouk, Ivan V

    2010-01-01

    Nanoporous ionic diodes, as well as devices for manipulating ions and molecules in a solution, have attracted a great deal of interest from researchers in various fields from the fundamental point of view. Ionic diodes allow the ions to be transported in one direction and block the transport in the other. There are two types of diodes that have been realized experimentally. A bipolar diode contains a junction between two zones of the pore walls with positive and negative surface charges. A unipolar diode contains a zone that is neutral and a zone that is charged. In this paper we discuss differences in operation of the diodes with a special emphasis on the sensitivity of their performance to the lengths of the charged and neutral zones. We also show that a bipolar diode offers more asymmetric current-voltage curves than a unipolar diode.

  18. Treatment of bipolar depression.

    PubMed

    Musetti, Laura; Del Grande, Claudia; Marazziti, Donatella; Dell'Osso, Liliana

    2013-08-01

    Depressive symptoms and episodes dominate the long-term course of bipolar disorder and are associated with high levels of disability and an increased risk of suicide. However, the treatment of bipolar depression has been poorly investigated in comparison with that of manic episodes and unipolar major depressive disorder. The goal of treatment in bipolar depression is not only to achieve full remission of acute symptoms, but also to avoid long-term mood destabilization and to prevent relapses. A depressive presentation of bipolar disorder may often delay the appropriate management and, thus, worsen the long-term outcome. In these cases, an accurate screening for diagnostic indicators of a possible bipolar course of the illness should guide the therapeutic choices, and lead to prognostic improvement. Antidepressant use is still the most controversial issue in the treatment of bipolar depression. Despite inconclusive evidence of efficacy and tolerability, this class of agents is commonly prescribed in acute and long-term treatment, often in combination with mood stabilizers. In this article, we review available treatment options for bipolar depression, and we shall provide some suggestions for the management of the different presentations of depression in the course of bipolar disorder. PMID:23391164

  19. Insight in bipolar disorder.

    PubMed

    Látalová, Klára

    2012-09-01

    Although there has been interest in insight in bipolar disorder, research has not been as developed as in schizophrenia. The Medline, Embase, and PsychInfo data bases were searched. The key words used in the search were "bipolar", "mania", "manic", "awareness", and "insight". Books, editorials, letters, and reports on pediatric subjects were excluded. Abstracts or full texts were screened for relevance. Better insight is associated with better adherence to treatment and better outcomes. Impairments of executive functions and memory, as well as higher severity of psychotic symptoms, are associated with impairments of insight. Insight is more impaired during an illness episode than during remission, in mixed than in pure manic episodes, in bipolar II than in bipolar I patients, in pure mania than in bipolar or unipolar depression. Psychosocial treatments improve insight and outcomes. There is a need for integration of quantitative assessment methods and their introduction into research and clinical practice. PMID:22101737

  20. Dc characterization of lateral bipolar devices in standard CMOS technology: a new model for base current partitioning

    NASA Astrophysics Data System (ADS)

    Corsi, F.; Di Ciano, M.; Marzocca, C.

    1999-05-01

    As is generally known, compared with MOSFETs bipolar transistors provide better performance in terms of small signal transconductance, intrinsic cut-off frequency and noise characteristics, at the cost of a more expensive technology. A good compromise between the low costs proper of standard CMOS technology and the excellent performance typical of bipolar devices can be achieved by using bipolar transistors derived from MOS structures. Naturally suitable models combined with efficient parameter extraction techniques are mandatory to provide designers with reliable simulation tools. A dc parameter extraction procedure for a PNP lateral transistor realized in a standard CMOS technology based on an existing composite circuit model is presented here. The extraction results provide accurate fitting between measured and simulated data for different operating regions without resort to numerical optimization, thus preserving the physical meaning of the extracted parameters and retaining a good correlation with process variations.

  1. Development and fabrication of an augmented power transistor

    NASA Technical Reports Server (NTRS)

    Geisler, M. J.; Hill, F. E.; Ostop, J. A.

    1983-01-01

    The development of device design and processing techniques for the fabrication of an augmented power transistor capable of fast switching and high voltage power conversion is discussed. The major device goals sustaining voltages in the range of 800 to 1000 V at 80 A and 50 A, respectively, at a gain of 14. The transistor switching rise and fall times were both to have been less than 0.5 microseconds. The development of a passivating glass technique to shield the device high voltage junction from moisture and ionic contaminants is discussed as well as the development of an isolated package that separates the thermal and electrical interfaces. A new method was found to alloy the transistors to the molybdenum disc at a relatively low temperature. The measured electrical performance compares well with the predicted optimum design specified in the original proposed design. A 40 mm diameter transistor was fabricated with seven times the emitter area of the earlier 23 mm diameter device.

  2. Characterization of power transistors as high dose dosimeters

    NASA Astrophysics Data System (ADS)

    Fuochi, P. G.; Lavalle, M.; Corda, U.; Kovacs, A.; Peimel-Stuglik, Z.; Gombia, E.

    2009-02-01

    A bipolar transistor, previously investigated as a possible radiation dosimeter and tested under industrial irradiation conditions in high-activity gamma and high-energy, high-power electron beam facilities has been subjected to stability test in order to understand its behaviour and help to improve its performances. Charge carrier lifetime was measured for several sets of transistors which were then irradiated with various doses (3-60 kGy): seven sets with 60Co gamma rays and eight with a 10 MeV electron beam. After irradiation all the transistors were measured and each set was divided into three groups: one group was left untreated, the second group was heated at 100 °C for 30 minutes and the third group was heated at 150 °C for 30 minutes, for testing the stability of the lifetime. Our data showed that heat treatment quite successfully eliminates post-irradiation changes in the response. Response measurements of the irradiated transistors, heat-treated and untreated, were carried out at room temperature over several weeks after irradiation to establish post-irradiation stability and assess if these transistors could be used for recording dose history. Calibration curves in the range 3-60 kGy for the thermally treated and untreated devices are presented. Dependence of the response of the transistors on the temperature of the measurements in the range 20-50 °C is reported.

  3. Semiconductor Lasers Containing Quantum Wells in Junctions

    NASA Technical Reports Server (NTRS)

    Yang, Rui Q.; Qiu, Yueming

    2004-01-01

    In a recent improvement upon In(x)Ga(1-x)As/InP semiconductor lasers of the bipolar cascade type, quantum wells are added to Esaki tunnel junctions, which are standard parts of such lasers. The energy depths and the geometric locations and thicknesses of the wells are tailored to exploit quantum tunneling such that, as described below, electrical resistances of junctions and concentrations of dopants can be reduced while laser performances can be improved. In(x)Ga(1-x)As/InP bipolar cascade lasers have been investigated as sources of near-infrared radiation (specifically, at wavelengths of about 980 and 1,550 nm) for photonic communication systems. The Esaki tunnel junctions in these lasers have been used to connect adjacent cascade stages and to enable transport of charge carriers between them. Typically, large concentrations of both n (electron-donor) and p (electron-acceptor) dopants have been necessary to impart low electrical resistances to Esaki tunnel junctions. Unfortunately, high doping contributes free-carrier absorption, thereby contributing to optical loss and thereby, further, degrading laser performance. In accordance with the present innovation, quantum wells are incorporated into the Esaki tunnel junctions so that the effective heights of barriers to quantum tunneling are reduced (see figure).

  4. Bipolar Disorder in Children

    PubMed Central

    2014-01-01

    Although bipolar disorder historically was thought to only occur rarely in children and adolescents, there has been a significant increase in children and adolescents who are receiving this diagnosis more recently (Carlson, 2005). Nonetheless, the applicability of the current bipolar disorder diagnostic criteria for children, particularly preschool children, remains unclear, even though much work has been focused on this area. As a result, more work needs to be done to further the understanding of bipolar symptoms in children. It is hoped that this paper can assist psychologists and other health service providers in gleaning a snapshot of the literature in this area so that they can gain an understanding of the diagnostic criteria and other behaviors that may be relevant and be informed about potential approaches for assessment and treatment with children who meet bipolar disorder criteria. First, the history of bipolar symptoms and current diagnostic criteria will be discussed. Next, assessment strategies that may prove helpful for identifying bipolar disorder will be discussed. Then, treatments that may have relevance to children and their families will be discussed. Finally, conclusions regarding work with children who may have a bipolar disorder diagnosis will be offered. PMID:24800202

  5. Calculating drain delay in high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Coffie, R.

    2015-12-01

    An expression for the signal delay (drain delay) associated with electrons traveling through the gate-drain depletion region has been obtained for nonuniform electron velocity. Due to the presence of the gate metal, the signal delay through the gate-drain depletion region was shown to be larger than the signal delay in the base-collector depletion region of a bipolar transistor when equal depletion lengths and velocity profiles were assumed. Drain delay is also shown to be larger in transistors with field plates (independent of field plate connection) compared to transistors without field plates when equal depletion lengths and velocity profiles were assumed. For the case of constant velocity, two expressions for the proportionality constant relating drain delay and electron transit time across the depletion were obtained.

  6. Bipolar fuel cell

    DOEpatents

    McElroy, James F.

    1989-01-01

    The present invention discloses an improved fuel cell utilizing an ion transporting membrane having a catalytic anode and a catalytic cathode bonded to opposite sides of the membrane, a wet-proofed carbon sheet in contact with the cathode surface opposite that bonded to the membrane and a bipolar separator positioned in electrical contact with the carbon sheet and the anode of the adjacent fuel cell. Said bipolar separator and carbon sheet forming an oxidant flowpath, wherein the improvement comprises an electrically conductive screen between and in contact with the wet-proofed carbon sheet and the bipolar separator improving the product water removal system of the fuel cell.

  7. Josephson Junctions Help Measure Resonance And Dispersion

    NASA Technical Reports Server (NTRS)

    Javadi, Hamid H. S.; Mcgrath, William R.; Bumble, Bruce; Leduc, Henry G.

    1994-01-01

    Electrical characteristics of superconducting microstrip transmission lines measured at millimeter and submillimeter wavelengths. Submicron Josephson (super-conductor/insulator/superconductor) junctions used as both voltage-controlled oscillators and detectors to measure frequencies (in range of hundreds of gigahertz) of high-order resonant electromagnetic modes of superconducting microstrip transmission-line resonators. This oscillator/detector approach similar to vacuum-tube grid dip meters and transistor dip meters used to probe resonances at much lower frequencies.

  8. Silicon-on-insulator-based high-voltage, high-temperature integrated circuit gate driver for silicon carbide-based power field effect transistors

    SciTech Connect

    Tolbert, Leon M; Huque, Mohammad A; Blalock, Benjamin J; Islam, Syed K

    2010-01-01

    Silicon carbide (SiC)-based field effect transistors (FETs) are gaining popularity as switching elements in power electronic circuits designed for high-temperature environments like hybrid electric vehicle, aircraft, well logging, geothermal power generation etc. Like any other power switches, SiC-based power devices also need gate driver circuits to interface them with the logic units. The placement of the gate driver circuit next to the power switch is optimal for minimising system complexity. Successful operation of the gate driver circuit in a harsh environment, especially with minimal or no heat sink and without liquid cooling, can increase the power-to-volume ratio as well as the power-to-weight ratio for power conversion modules such as a DC-DC converter, inverter etc. A silicon-on-insulator (SOI)-based high-voltage, high-temperature integrated circuit (IC) gate driver for SiC power FETs has been designed and fabricated using a commercially available 0.8--m, 2-poly and 3-metal bipolar-complementary metal oxide semiconductor (CMOS)-double diffused metal oxide semiconductor (DMOS) process. The prototype circuit-s maximum gate drive supply can be 40-V with peak 2.3-A sourcing/sinking current driving capability. Owing to the wide driving range, this gate driver IC can be used to drive a wide variety of SiC FET switches (both normally OFF metal oxide semiconductor field effect transistor (MOSFET) and normally ON junction field effect transistor (JFET)). The switching frequency is 20-kHz and the duty cycle can be varied from 0 to 100-. The circuit has been successfully tested with SiC power MOSFETs and JFETs without any heat sink and cooling mechanism. During these tests, SiC switches were kept at room temperature and ambient temperature of the driver circuit was increased to 200-C. The circuit underwent numerous temperature cycles with negligible performance degradation.

  9. Current-Induced Transistor Sensorics with Electrogenic Cells.

    PubMed

    Fromherz, Peter

    2016-01-01

    The concepts of transistor recording of electroactive cells are considered, when the response is determined by a current-induced voltage in the electrolyte due to cellular activity. The relationship to traditional transistor recording, with an interface-induced response due to interactions with the open gate oxide, is addressed. For the geometry of a cell-substrate junction, the theory of a planar core-coat conductor is described with a one-compartment approximation. The fast electrical relaxation of the junction and the slow change of ion concentrations are pointed out. On that basis, various recording situations are considered and documented by experiments. For voltage-gated ion channels under voltage clamp, the effects of a changing extracellular ion concentration and the enhancement/depletion of ion conductances in the adherent membrane are addressed. Inhomogeneous ion conductances are crucial for transistor recording of neuronal action potentials. For a propagating action potential, the effects of an axon-substrate junction and the surrounding volume conductor are distinguished. Finally, a receptor-transistor-sensor is described, where the inhomogeneity of a ligand-activated ion conductance is achieved by diffusion of the agonist and inactivation of the conductance. Problems with regard to a development of reliable biosensors are mentioned. PMID:27120627

  10. Current-Induced Transistor Sensorics with Electrogenic Cells

    PubMed Central

    Fromherz, Peter

    2016-01-01

    The concepts of transistor recording of electroactive cells are considered, when the response is determined by a current-induced voltage in the electrolyte due to cellular activity. The relationship to traditional transistor recording, with an interface-induced response due to interactions with the open gate oxide, is addressed. For the geometry of a cell-substrate junction, the theory of a planar core-coat conductor is described with a one-compartment approximation. The fast electrical relaxation of the junction and the slow change of ion concentrations are pointed out. On that basis, various recording situations are considered and documented by experiments. For voltage-gated ion channels under voltage clamp, the effects of a changing extracellular ion concentration and the enhancement/depletion of ion conductances in the adherent membrane are addressed. Inhomogeneous ion conductances are crucial for transistor recording of neuronal action potentials. For a propagating action potential, the effects of an axon-substrate junction and the surrounding volume conductor are distinguished. Finally, a receptor-transistor-sensor is described, where the inhomogeneity of a ligand–activated ion conductance is achieved by diffusion of the agonist and inactivation of the conductance. Problems with regard to a development of reliable biosensors are mentioned. PMID:27120627

  11. Voltage dependence of the differential capacitance of a p{sup +}-n junction

    SciTech Connect

    Shekhovtsov, N. A.

    2013-04-15

    The dependences of the differential capacitance and current of a p{sup +}-n junction with a uniformly doped n region on the voltage in the junction region are calculated. The p{sup +}-n junction capacitance controls the charge change in the junction region taking into account a change in the electric field of the quasi-neutral n region and a change in its bipolar drift mobility with increasing excess charge-carrier concentration. It is shown that the change in the sign of the p{sup +}-n junction capacitance with increasing injection level is caused by a decrease in the bipolar drift mobility as the electron-hole pair concentration in the n region increases. It is shown that the p{sup +}-n junction capacitance decreases with increasing reverse voltage and tends to a constant positive value.

  12. Copper oxide transistor on copper wire for e-textile

    NASA Astrophysics Data System (ADS)

    Han, Jin-Woo; Meyyappan, M.

    2011-05-01

    A Cu2O-based field effect transistor was fabricated on Cu wire. Thermal oxidation of Cu forms Cu-Cu2O core-shell structure, where the metal-semiconductor Schottky junction was used as a gate barrier with Pt Ohmic contacts for source and drain. The device was coated with polydimethylsiloxane (PDMS) to protect from contamination and demonstrated as a humidity sensor. The cylindrical structure of the Cu wire and the transistor function enable embedding of simple circuits into textile which can potentially offer smart textile for wearable computing, environmental sensing, and monitoring of human vital signs.

  13. Soft switch-avalanche IGBT convertor. [Insulated Gate Bipolar Transistor

    NASA Technical Reports Server (NTRS)

    Chen, K.; Stuart, T. A.

    1990-01-01

    A full bridge dc-dc converter using a zero voltage and zero current switching technique is described. This circuit utilizes the characteristics of the IGBT to achieve power and frequency combinations that are much higher than those previously reported for this device. Experimental results are included for a 1.5 kW, 100 kHz converter with 94 percent efficiency.

  14. Design considerations for the Tandem Junction Solar Cell

    NASA Technical Reports Server (NTRS)

    Matzen, W. T.; Carbajal, B. G.; Hardy, R. W.

    1979-01-01

    Structure and operation of the tandem junction cell (TJC) are described. The impact of using only back contacts is discussed. A model is presented which explains operation of the TJC in terms of transistor action. The model is applied to predict TJC performance as a function of physical parameters.

  15. Gating a single-molecule transistor with individual atoms

    NASA Astrophysics Data System (ADS)

    Martínez-Blanco, Jesús; Nacci, Christophe; Erwin, Steven C.; Kanisawa, Kiyoshi; Locane, Elina; Thomas, Mark; von Oppen, Felix; Brouwer, Piet W.; Fölsch, Stefan

    2015-08-01

    Transistors, regardless of their size, rely on electrical gates to control the conductance between source and drain contacts. In atomic-scale transistors, this conductance is sensitive to single electrons hopping via individual orbitals. Single-electron transport in molecular transistors has been previously studied using top-down approaches to gating, such as lithography and break junctions. But atomically precise control of the gate--which is crucial to transistor action at the smallest size scales--is not possible with these approaches. Here, we used individual charged atoms, manipulated by a scanning tunnelling microscope, to create the electrical gates for a single-molecule transistor. This degree of control allowed us to tune the molecule into the regime of sequential single-electron tunnelling, albeit with a conductance gap more than one order of magnitude larger than observed previously. This unexpected behaviour arises from the existence of two different orientational conformations of the molecule, depending on its charge state. Our results show that strong coupling between these charge and conformational degrees of freedom leads to new behaviour beyond the established picture of single-electron transport in atomic-scale transistors.

  16. Depression and Bipolar Support Alliance

    MedlinePlus

    ... events Visit the podcast archive Mood Disorders Depression Bipolar Disorder Anxiety Screening Center Co-occurring Illnesses/Disorders Related ... for Your Patients Information about Depression Information about Bipolar Disorder Wellness Tools DBSA Support Groups Active Research Studies ...

  17. Bipolar Affective Disorder and Migraine

    PubMed Central

    Engmann, Birk

    2012-01-01

    This paper consists of a case history and an overview of the relationship, aetiology, and treatment of comorbid bipolar disorder migraine patients. A MEDLINE literature search was used. Terms for the search were bipolar disorder bipolar depression, mania, migraine, mood stabilizer. Bipolar disorder and migraine cooccur at a relatively high rate. Bipolar II patients seem to have a higher risk of comorbid migraine than bipolar I patients have. The literature on the common roots of migraine and bipolar disorder, including both genetic and neuropathological approaches, is broadly discussed. Moreover, bipolar disorder and migraine are often combined with a variety of other affective disorders, and, furthermore, behavioural factors also play a role in the origin and course of the diseases. Approach to treatment options is also difficult. Several papers point out possible remedies, for example, valproate, topiramate, which acts on both diseases, but no first-choice treatments have been agreed upon yet. PMID:22649454

  18. Lightweight bipolar storage battery

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor)

    1992-01-01

    An apparatus [10] is disclosed for a lightweight bipolar battery of the end-plate cell stack design. Current flow through a bipolar cell stack [12] is collected by a pair of copper end-plates [16a,16b] and transferred edgewise out of the battery by a pair of lightweight, low resistance copper terminals [28a,28b]. The copper terminals parallel the surface of a corresponding copper end-plate [16a,16b] to maximize battery throughput. The bipolar cell stack [12], copper end-plates [16a,16b] and copper terminals [28a,28b] are rigidly sandwiched between a pair of nonconductive rigid end-plates [20] having a lightweight fiber honeycomb core which eliminates distortion of individual plates within the bipolar cell stack due to internal pressures. Insulating foam [30] is injected into the fiber honeycomb core to reduce heat transfer into and out of the bipolar cell stack and to maintain uniform cell performance. A sealed battery enclosure [ 22] exposes a pair of terminal ends [26a,26b] for connection with an external circuit.

  19. Room temperature operational single electron transistor fabricated by focused ion beam deposition

    NASA Astrophysics Data System (ADS)

    Karre, P. Santosh Kumar; Bergstrom, Paul L.; Mallick, Govind; Karna, Shashi P.

    2007-07-01

    We present the fabrication and room temperature operation of single electron transistors using 8nm tungsten islands deposited by focused ion beam deposition technique. The tunnel junctions are fabricated using oxidation of tungsten in peracetic acid. Clear Coulomb oscillations, showing charging and discharging of the nanoislands, are seen at room temperature. The device consists of an array of tunnel junctions; the tunnel resistance of individual tunnel junction of the device is calculated to be as high as 25.13GΩ. The effective capacitance of the array of tunnel junctions was found to be 0.499aF, giving a charging energy of 160.6meV.

  20. Bipolar battery construction

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A lightweight, bipolar battery construction for lead acid batteries in which a plurality of thin, rigid, biplates each comprise a graphite fiber thermoplastic composition in conductive relation to lead stripes plated on opposite flat surfaces of the plates, and wherein a plurality of nonconductive thermoplastic separator plates support resilient yieldable porous glass mats in which active material is carried, the biplates and separator plates with active material being contained and maintained in stacked assembly by axial compression of the stacked assembly. A method of assembling such a bipolar battery construction.

  1. From The Lab to The Fab: Transistors to Integrated Circuits

    NASA Astrophysics Data System (ADS)

    Huff, Howard R.

    2003-09-01

    Transistor action was experimentally observed by John Bardeen and Walter Brattain in n-type polycrystalline germanium on December 16, 1947 (and subsequently polycrystalline silicon) as a result of the judicious placement of gold-plated probe tips in nearby single crystal grains of the polycrystalline material (i.e., the point-contact semiconductor amplifier, often referred to as the point-contact transistor).The device configuration exploited the inversion layer as the channel through which most of the emitted (minority) carriers were transported from the emitter to the collector. The point-contact transistor was manufactured for ten years starting in 1951 by the Western Electric Division of AT&T. The a priori tuning of the point-contact transistor parameters, however, was not simple inasmuch as the device was dependent on the detailed surface structure and, therefore, very sensitive to humidity and temperature as well as exhibiting high noise levels. Accordingly, the devices differed significantly in their characteristics and electrical instabilities leading to "burnout" were not uncommon. With the implementation of crystalline semiconductor materials in the early 1950s, however, p-n junction (bulk) transistors began replacing the point-contact transistor, silicon began replacing germanium and the transfer of transistor technology from the lab to the lab accelerated. We shall review the historical route by which single crystalline materials were developed and the accompanying methodologies of transistor fabrication, leading to the onset of the Integrated Circuit (IC) era. Finally, highlights of the early years of the IC era will be reviewed from the 256 bit through the 4M DRAM. Elements of IC scaling and the role of Moore's Law in setting the parameters by which the IC industry's growth was monitored will be discussed.

  2. Vertical organic transistors

    NASA Astrophysics Data System (ADS)

    Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

    2015-11-01

    Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100 nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-μm structuring technologies. In this review, these different approaches are compared and recent progress is highlighted.

  3. Noise characteristics of single-walled carbon nanotube network transistors

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

    2008-07-01

    The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors.

  4. Noise characteristics of single-walled carbon nanotube network transistors.

    PubMed

    Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

    2008-07-16

    The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors. PMID:21828739

  5. Physics-based stability analysis of MOS transistors

    NASA Astrophysics Data System (ADS)

    Ferrara, A.; Steeneken, P. G.; Boksteen, B. K.; Heringa, A.; Scholten, A. J.; Schmitz, J.; Hueting, R. J. E.

    2015-11-01

    In this work, a physics-based model is derived based on a linearization procedure for investigating the electrical, thermal and electro-thermal instability of power metal-oxide-semiconductor (MOS) transistors. The proposed model can be easily interfaced with a circuit or device simulator to perform a failure analysis, making it particularly useful for power transistors. Furthermore, it allows mapping the failure points on a three-dimensional (3D) space defined by the gate-width normalized drain current, drain voltage and junction temperature. This leads to the definition of the Safe Operating Volume (SOV), a powerful frame work for making failure predictions and determining the main root of instability (electrical, thermal or electro-thermal) in different bias and operating conditions. A comparison between the modeled and the measured SOV of silicon-on-insulator (SOI) LDMOS transistors is reported to support the validity of the proposed stability analysis.

  6. Polyphosphonium‐based bipolar membranes for rectification of ionic currents

    PubMed Central

    Gabrielsson, Erik O.; Berggren, Magnus

    2013-01-01

    Bipolar membranes (BMs) have interesting applications within the field of bioelectronics, as they may be used to create non-linear ionic components (e.g., ion diodes and transistors), thereby extending the functionality of, otherwise linear, electrophoretic drug delivery devices. However, BM based diodes suffer from a number of limitations, such as narrow voltage operation range and/or high hysteresis. In this work, we circumvent these problems by using a novel polyphosphonium-based BM, which is shown to exhibit improved diode characteristics. We believe that this new type of BM diode will be useful for creating complex addressable ionic circuits for delivery of charged biomolecules. PMID:24400035

  7. Experimental results of a vortex flow transistor amplifier

    SciTech Connect

    McGinnis, D.P.; Hohenwarter, G.K.G.; Ketkar, M.; Beyer, J.B.; Nordman, J.E.

    1989-03-01

    A Niobium based superconducting amplifier consisting of a series array of 60 vortex flow transistors (VFT) was fabricated and tested. Each VFT consisted of a long Josephson junction biased in the flux flow state, magnetically coupled to a current carrying control line. The topology of the circuit is based on a distributed amplifier configuration. The transresistance of the amplifier in a 50 Ohm environment for frequencies up to 1 MHz was measured.

  8. Endophenotypes in bipolar disorder.

    PubMed

    Lenox, Robert H; Gould, Todd D; Manji, Husseini K

    2002-05-01

    The search for genes in bipolar disorder has provided numerous genetic loci that have been linked to susceptibility to developing the disorder. However, because of the genetic heterogeneity inherent in bipolar disorder, additional strategies may need to be employed to fully dissect the genetic underpinnings. One such strategy involves reducing complex behaviors into their component parts (endophenotypes). Abnormal neurophysiological, biochemical, endocrinological, neuroanatomical, cognitive, and neuropsychological findings are characteristics that often accompany psychiatric illness. It is possible that some of these may eventually be useful in subdefining complex genetic disorders, allowing for improvements in diagnostic assessment, genetic linkage studies, and development of animal models. Findings in patients with bipolar disorder that may eventually be useful as endophenotypes include abnormal regulation of circadian rhythms (the sleep/wake cycle, hormonal rhythms, etc.), response to sleep deprivation, P300 event-related potentials, behavioral responses to psychostimulants and other medications, response to cholinergics, increase in white matter hyperintensities (WHIs), and biochemical observations in peripheral mononuclear cells. Targeting circadian rhythm abnormalities may be a particularly useful strategy because circadian cycles appear to be an inherent evolutionarily conserved function in all organisms and have been implicated in the pathophysiology of bipolar disorder. Furthermore, lithium has been shown to regulate circadian cycles in diverse species, including humans, possibly through inhibition of glycogen synthase kinase 3-beta (GSK-3beta), a known target of lithium. PMID:11992561

  9. Transistor-based interface circuitry

    DOEpatents

    Taubman, Matthew S.

    2004-02-24

    Among the embodiments of the present invention is an apparatus that includes a transistor, a servo device, and a current source. The servo device is operable to provide a common base mode of operation of the transistor by maintaining an approximately constant voltage level at the transistor base. The current source is operable to provide a bias current to the transistor. A first device provides an input signal to an electrical node positioned between the emitter of the transistor and the current source. A second device receives an output signal from the collector of the transistor.

  10. Transistor-based interface circuitry

    DOEpatents

    Taubman, Matthew S.

    2007-02-13

    Among the embodiments of the present invention is an apparatus that includes a transistor, a servo device, and a current source. The servo device is operable to provide a common base mode of operation of the transistor by maintaining an approximately constant voltage level at the transistor base. The current source is operable to provide a bias current to the transistor. A first device provides an input signal to an electrical node positioned between the emitter of the transistor and the current source. A second device receives an output signal from the collector of the transistor.

  11. Nitrided Metallic Bipolar Plates

    SciTech Connect

    Brady, Michael P; Tortorelli, Peter F; Pihl, Josh A; Toops, Todd J; More, Karren Leslie; Meyer III, Harry M; Vitek, John Michael; Wang, Heli; Turner, John; Wilson, Mahlon; Garzon, Fernando; Rockward, Tommy; Connors, Dan; Rakowski, Jim; Gervasio, Don

    2008-01-01

    The objectives are: (1) Develop and optimize stainless steel alloys amenable to formation of a protective Cr-nitride surface by gas nitridation, at a sufficiently low cost to meet DOE targets and with sufficient ductility to permit manufacture by stamping. (2) Demonstrate capability of nitridation to yield high-quality stainless steel bipolar plates from thin stamped alloy foils (no significant stamped foil warping or embrittlement). (3) Demonstrate single-cell fuel cell performance of stamped and nitrided alloy foils equivalent to that of machined graphite plates of the same flow-field design ({approx}750-1,000 h, cyclic conditions, to include quantification of metal ion contamination of the membrane electrode assembly [MEA] and contact resistance increase attributable to the bipolar plates). (4) Demonstrate potential for adoption in automotive fuel cell stacks. Thin stamped metallic bipolar plates offer the potential for (1) significantly lower cost than currently-used machined graphite bipolar plates, (2) reduced weight/volume, and (3) better performance and amenability to high volume manufacture than developmental polymer/carbon fiber and graphite composite bipolar plates. However, most metals exhibit inadequate corrosion resistance in proton exchange membrane fuel cell (PEMFC) environments. This behavior leads to high electrical resistance due to the formation of surface oxides and/or contamination of the MEA by metallic ions, both of which can significantly degrade fuel cell performance. Metal nitrides offer electrical conductivities up to an order of magnitude greater than that of graphite and are highly corrosion resistant. Unfortunately, most conventional coating methods (for metal nitrides) are too expensive for PEMFC stack commercialization or tend to leave pinhole defects, which result in accelerated local corrosion and unacceptable performance.

  12. Preventing Simultaneous Conduction In Switching Transistors

    NASA Technical Reports Server (NTRS)

    Mclyman, William T.

    1990-01-01

    High voltage spikes and electromagnetic interference suppressed. Power-supply circuit including two switching transistors easily modified to prevent simultaneous conduction by both transistors during switching intervals. Diode connected between collector of each transistor and driving circuit for opposite transistor suppresses driving signal to transistor being turned on until transistor being turned off ceases to carry current.

  13. A comparison of radiation damage in transistors from cobalt-60 gamma rays and 2.2 MeV electrons

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Price, W. E.; Gauthier, M. K.

    1982-01-01

    The total ionizing dose response of ten bipolar transistor types has been measured using Co-60 gamma rays and 2.2 MeV electrons from exposure levels of 750, 1500, and 3000 Gy(Si). Gain measurements were made for a range of collector-emitter voltages and collector currents.

  14. Electronic transport in benzodifuran single-molecule transistors

    NASA Astrophysics Data System (ADS)

    Xiang, An; Li, Hui; Chen, Songjie; Liu, Shi-Xia; Decurtins, Silvio; Bai, Meilin; Hou, Shimin; Liao, Jianhui

    2015-04-01

    Benzodifuran (BDF) single-molecule transistors have been fabricated in electromigration break junctions for electronic measurements. The inelastic electron tunneling spectrum validates that the BDF molecule is the pathway of charge transport. The gating effect is analyzed in the framework of a single-level tunneling model combined with transition voltage spectroscopy (TVS). The analysis reveals that the highest occupied molecular orbital (HOMO) of the thiol-terminated BDF molecule dominates the charge transport through Au-BDF-Au junctions. Moreover, the energy shift of the HOMO caused by the gate voltage is the main reason for conductance modulation. In contrast, the electronic coupling between the BDF molecule and the gold electrodes, which significantly affects the low-bias junction conductance, is only influenced slightly by the applied gate voltage. These findings will help in the design of future molecular electronic devices.Benzodifuran (BDF) single-molecule transistors have been fabricated in electromigration break junctions for electronic measurements. The inelastic electron tunneling spectrum validates that the BDF molecule is the pathway of charge transport. The gating effect is analyzed in the framework of a single-level tunneling model combined with transition voltage spectroscopy (TVS). The analysis reveals that the highest occupied molecular orbital (HOMO) of the thiol-terminated BDF molecule dominates the charge transport through Au-BDF-Au junctions. Moreover, the energy shift of the HOMO caused by the gate voltage is the main reason for conductance modulation. In contrast, the electronic coupling between the BDF molecule and the gold electrodes, which significantly affects the low-bias junction conductance, is only influenced slightly by the applied gate voltage. These findings will help in the design of future molecular electronic devices. Electronic supplementary information (ESI) available: The fabrication procedure for BDF single

  15. Fabrication and characterization of heterojunction transistors

    NASA Astrophysics Data System (ADS)

    Lo, Chien-Fong

    2011-12-01

    Submircon emitter finger high-speed double heterojunction InAlAs/InGaAsSb/InGaAs bipolar transistors (DHBTs) and a variety of nitride high electron mobility transistors (HEMTs) including AlGaN/GaN, InAlN/GaN, and AlN/GaN were fabricated and characterized. DHBT structures were grown by solid source molecular beam epitaxy (SSMBE) on Fe-doped semiinsulating InP substrates and nitride HEMTs were grown with a metal organic chemical vapor deposition (MOCVD) system on sapphire or SiC substrates. AlN/GaN HEMTs were grown with a RF-VMBE on sapphire substrates. Ultra low base contact resistance of 3.7 x 10-7 ohm-cm2 after 1 min 250¢XC thermal treatment on noval InGaAsSb base of DHBTs was achieved and a long-term thermal stability of base metallization was studied. Regarding small scale DHBT fabrication, tri-layer system was introduced to improve the resolution for submicron emitter patterning and help to pile up a thicker emitter metal stack; guard-ring technique was applied around the emitter periphery in order to preserve the current gain at small emitter dimensions. Ultra low turn-on voltage and high current gain can be realized with InGaAsSb-base DHBTs as compared to the conventional InGaAs-base DHBTs. A peak current gain cutoff frequency (fT) of 268 GHz and power gain cutoff frequency (fmax) of 485 GHz were achieved. GaN-based HEMTs herein were fabricated with gate lengths from 400 nm to 1im, and were deposited Ti/Al/Ni/Au as their Ohmic contact metallization. Effects of the Ohmic contact annealing for lattice-matched InAlN/GaN HEMTs with and without a thin GaN cap layer were exhibited and their optimal annealing temperature were obtained. A maximum drain current of 1.3 A/mm and an extrinsic transconductance of 366 mS/mm were demonstrated for InAlN/GaN HEMTs with the shortest gate length. A unity-gain cutoff frequency (fT) of 69 GHz and a maximum frequency of oscillation (fmax) of 80 GHz for InAlN/GaN HEMTs were extracted from measured scattering parameters

  16. Graphene oxide as a water dissociation catalyst in the bipolar membrane interfacial layer.

    PubMed

    McDonald, Michael B; Freund, Michael S

    2014-08-27

    Bipolar membranes are formed by the lamination of an anion- and cation-exchange layer. Upon a sufficient applied reverse bias, water molecules at the layer junction dissociate, generating OH(-) and H(+), which can be useful in electrodialysis and electrosynthesis applications. Graphene oxide has been introduced into bipolar membrane junctions (illustrated in the adjacent graphic) and is shown to be an efficient new water dissociation catalyst, lowering the overpotential by 75% compared to a control membrane. It was found that adjusting deposition conditions changes the nature of the graphene oxide films, leading to tunable membrane performance. Additionally, it is shown that their low overpotentials are stable, making for industrially viable, high-performance bipolar membranes. PMID:25046580

  17. Boron nitride housing cools transistors

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Boron nitride ceramic heat sink cools transistors in r-f transmitter and receiver circuits. Heat dissipated by the transistor is conducted by the boron nitride housing to the metal chassis on which it is mounted.

  18. Total Dose Effects on Single Event Transients in Digital CMOS and Linear Bipolar Circuits

    NASA Technical Reports Server (NTRS)

    Buchner, S.; McMorrow, D.; Sibley, M.; Eaton, P.; Mavis, D.; Dusseau, L.; Roche, N. J-H.; Bernard, M.

    2009-01-01

    This presentation discusses the effects of ionizing radiation on single event transients (SETs) in circuits. The exposure of integrated circuits to ionizing radiation changes electrical parameters. The total ionizing dose effect is observed in both complementary metal-oxide-semiconductor (CMOS) and bipolar circuits. In bipolar circuits, transistors exhibit grain degradation, while in CMOS circuits, transistors exhibit threshold voltage shifts. Changes in electrical parameters can cause changes in single event upset(SEU)/SET rates. Depending on the effect, the rates may increase or decrease. Therefore, measures taken for SEU/SET mitigation might work at the beginning of a mission but not at the end following TID exposure. The effect of TID on SET rates should be considered if SETs cannot be tolerated.

  19. Pleated metal bipolar assembly

    DOEpatents

    Wilson, Mahlon S.; Zawodzinski, Christine

    2001-01-01

    A thin low-cost bipolar plate for an electrochemical cell is formed from a polymer support plate with first flow channels on a first side of the support plate and second flow channels on a second side of the support plate, where the first flow channels and second flow channels have intersecting locations and have a depth effective to form openings through the support plate at the intersecting locations. A first foil of electrically conductive material is pressed into the first flow channels. A second foil of electrically conductive material pressed into the second flow channels so that electrical contact is made between the first and second foils at the openings through the support plate. A particular application of the bipolar plate is in polymer electrolyte fuel cells.

  20. Self Contact Organic Transistors

    NASA Astrophysics Data System (ADS)

    Inoue, Jun-ichi; Wada, Hiroshi; Mori, Takehiko

    2010-07-01

    Thin films of various organic semiconductors, such as pentacene, sexithiophene, copper phthalocyanine, and C60, as well as an organic charge-transfer salt (TTF)(TCNQ) [TTF: tetrathiafulvalene; TCNQ: tetracyanoquinodimethane] are laser-irradiated to form conductive films, which are identified by Raman spectroscopy and atomic force microscopy to be carbon. The resulting practically transparent films are as conductive as laser-sintered carbon films and show temperature-independent conductivity. Source and drain electrodes of organic field-effect transistors are patterned by this method; in these “self-contact” transistors, both the active layers and the electrodes are derived from the same organic film. The laser-sintered carbon films are also utilized for organic single-crystal transistors based on rubrene and TCNQ.

  1. Bipolar Disorder in Children and Teens

    MedlinePlus

    ... is in crisis. What do I do? Share Bipolar Disorder in Children and Teens Download PDF Download ePub ... brochure will give you more information. What is bipolar disorder? Bipolar disorder is a serious brain illness. It ...

  2. [Antipsychotics in bipolar disorders].

    PubMed

    Vacheron-Trystram, M-N; Braitman, A; Cheref, S; Auffray, L

    2004-01-01

    This article is a review of the various treatments that are currently available, in particular in France, for the treatment of bipolar disorders. This article specifically addresses the use of novel antipsychotic agents as alternative therapy to a lithium therapy and/or the use of conventional antipsychotics. The prevalence of bipolar disorder over a lifetime is around 1% of the general population. Bipolar disorder consists of alternating depressive and manic episodes. It mainly affects younger subjects, and is often associated with alcohol and drug addictions. There are two main subtypes of bipolar disorder. According to the DSM IV-R, type 1 of bipolar disorder is characterised when at least one manic episode (or a mixed episode) has been diagnosed. Type 2 of bipolar disorder is related to patients enduring recurrent depressive episodes but no manic episode. Type 2 affects women more frequently as opposed to type 1 affecting individuals of both sexes. Manic-depressive disorder (or cyclo-thymic disorder) appears in relation to patients who has never suffered manic episode, mixed episode or severe depressive episode but have undergone numerous periods with some symptoms of depression and hypomanic symptoms over a two-year period during which any asymptomatic periods last no longer than two months. The average age of the person going through a first episode (often a depressive one) is 20 years-old. Untreated bipolar patients may endure more than ten manic or depressive episodes. Finally, in relation to 10 to 20% of patients, the bipolar disorder will turn into a fast cycle form, either spontaneously or as a result of certain medical treatments. Psychiatrists are now able to initiate various treating strategies which are most likely to be effective as a result of the identification of clinical subtypes of the bipolar disorder. Lithium therapy has been effectively and acutely used for patients with pure or elated mania and its prophylaxis. However, lithium medication

  3. VOLTAGE-CONTROLLED TRANSISTOR OSCILLATOR

    DOEpatents

    Scheele, P.F.

    1958-09-16

    This patent relates to transistor oscillators and in particular to those transistor oscillators whose frequencies vary according to controlling voltages. A principal feature of the disclosed transistor oscillator circuit resides in the temperature compensation of the frequency modulating stage by the use of a resistorthermistor network. The resistor-thermistor network components are selected to have the network resistance, which is in series with the modulator transistor emitter circuit, vary with temperature to compensate for variation in the parameters of the transistor due to temperature change.

  4. Imaging dissipation and hot spots in carbon nanotube network transistors

    NASA Astrophysics Data System (ADS)

    Estrada, David; Pop, Eric

    2011-02-01

    We use infrared thermometry of carbon nanotube network (CNN) transistors and find the formation of distinct hot spots during operation. However, the average CNN temperature at breakdown is significantly lower than expected from the breakdown of individual nanotubes, suggesting extremely high regions of power dissipation at the CNN junctions. Statistical analysis and comparison with a thermal model allow the estimate of an upper limit for the average tube-tube junction thermal resistance, ˜4.4×1011 K/W (thermal conductance of ˜2.27 pW/K). These results indicate that nanotube junctions have a much greater impact on CNN transport, dissipation, and reliability than extrinsic factors such as low substrate thermal conductivity.

  5. Ambipolar nonvolatile memory based on a quantum-dot transistor with a nanoscale floating gate

    NASA Astrophysics Data System (ADS)

    Che, Yongli; Zhang, Yating; Cao, Xiaolong; Song, Xiaoxian; Cao, Mingxuan; Dai, Haitao; Yang, Junbo; Zhang, Guizhong; Yao, Jianquan

    2016-07-01

    Using only solution processing methods, we developed ambipolar quantum-dot (QD) transistor floating-gate memory (FGM) that uses Au nanoparticles as a floating gate. Because of the bipolarity of the active channel of PbSe QDs, the memory could easily trap holes or electrons in the floating gate by programming/erasing (P/E) operations, which could shift the threshold voltage both up and down. As a result, the memory exhibited good programmable memory characteristics: a large memory window (ΔVth ˜ 15 V) and a long retention time (>105 s). The magnitude of ΔVth depended on both P/E voltages and the bias voltage (VDS): ΔVth was a cubic function to VP/E and linearly depended on VDS. Therefore, this FGM based on a QD transistor is a promising alternative to its inorganic counterparts owing to its advantages of bipolarity, high mobility, low cost, and large-area production.

  6. Fin width and height dependence of bipolar amplification in bulk FinFETs submitted to heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Yu, Jun-Ting; Chen, Shu-Ming; Chen, Jian-Jun; Huang, Peng-Cheng

    2015-11-01

    FinFET technologies are becoming the mainstream process as technology scales down. Based on a 28-nm bulk p-FinFET device, we have investigated the fin width and height dependence of bipolar amplification for heavy-ion-irradiated FinFETs by 3D TCAD numerical simulation. Simulation results show that due to a well bipolar conduction mechanism rather than a channel (fin) conduction path, the transistors with narrower fins exhibit a diminished bipolar amplification effect, while the fin height presents a trivial effect on the bipolar amplification and charge collection. The results also indicate that the single event transient (SET) pulse width can be mitigated about 35% at least by optimizing the ratio of fin width and height, which can provide guidance for radiation-hardened applications in bulk FinFET technology. Project supported by the National Natural Science of China (Grant No. 61376109).

  7. Analyses of Transistor Punchthrough Failures

    NASA Technical Reports Server (NTRS)

    Nicolas, David P.

    1999-01-01

    The failure of two transistors in the Altitude Switch Assembly for the Solid Rocket Booster followed by two additional failures a year later presented a challenge to failure analysts. These devices had successfully worked for many years on numerous missions. There was no history of failures with this type of device. Extensive checks of the test procedures gave no indication for a source of the cause. The devices were manufactured more than twenty years ago and failure information on this lot date code was not readily available. External visual exam, radiography, PEID, and leak testing were performed with nominal results Electrical testing indicated nearly identical base-emitter and base-collector characteristics (both forward and reverse) with a low resistance short emitter to collector. These characteristics are indicative of a classic failure mechanism called punchthrough. In failure analysis punchthrough refers to an condition where a relatively low voltage pulse causes the device to conduct very hard producing localized areas of thermal runaway or "hot spots". At one or more of these hot spots, the excessive currents melt the silicon. Heavily doped emitter material diffuses through the base region to the collector forming a diffusion pipe shorting the emitter to base to collector. Upon cooling, an alloy junction forms between the pipe and the base region. Generally, the hot spot (punch-through site) is under the bond and no surface artifact is visible. The devices were delidded and the internal structures were examined microscopically. The gold emitter lead was melted on one device, but others had anomalies in the metallization around the in-tact emitter bonds. The SEM examination confirmed some anomalies to be cosmetic defects while other anomalies were artifacts of the punchthrough site. Subsequent to these analyses, the contractor determined that some irregular testing procedures occurred at the time of the failures heretofore unreported. These testing

  8. Studies of silicon p-n junction solar cells

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Lindholm, F. A.

    1979-01-01

    To provide theoretical support for investigating different ways to obtain high open-circuit voltages in p-n junction silicon solar cells, an analytical treatment of heavily doped transparent-emitter devices is presented that includes the effects of bandgap narrowing, Fermi-Dirac statistics, a doping concentration gradient, and a finite surface recombination velocity at the emitter surface. Topics covered include: (1) experimental determination of bandgap narrowing in the emitter of silicon p-n junction devices; (2) heavily doped transparent regions in junction solar cells, diodes, and transistors; (3) high-low-emitter solar cell; (4) determination of lifetimes and recombination currents in p-n junction solar cells; (5) MOS and oxide-charged-induced BSF solar cells; and (6) design of high efficiency solar cells for space and terrestrial applications.

  9. Vertical organic transistors.

    PubMed

    Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

    2015-11-11

    Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100 nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-μm structuring technologies. In this review, these different approaches are compared and recent progress is highlighted. PMID:26466388

  10. Carrier injection dynamics in heterojunction solar cells with bipolar molecule

    SciTech Connect

    Takahashi, Yosuke; Yonezawa, Kouhei; Yasuda, Takeshi E-mail: moritomo.yutaka.gf@u.tsukuba.ac.jp; Moritomo, Yutaka E-mail: moritomo.yutaka.gf@u.tsukuba.ac.jp

    2015-03-23

    A boron subphthalocyanine chloride (SubPc) is a bipolar molecule and is used in hetero-junction organic solar cells. Here, we investigated the carrier injection dynamics from the donor α-sexithiophene (6T) or acceptor C{sub 60} layers to the bipolar SubPc layer by means of the femtosecond time-resolved spectroscopy. We observed gradual increase of the SubPc{sup –} (SubPc{sup +}) species within ≈300 ps. The increases are interpreted in terms of the exciton diffusion within the 6T (C{sub 60}) layer and subsequent electron (hole) injection at the interface. In 6T/SubPc heterojunction, the electron injection is observed even at 80 K. The robust electron injection is ascribed to the efficient charge separation within the 6T layer under photo exciation at 400 nm.

  11. Radiation-hardened transistor and integrated circuit

    DOEpatents

    Ma, Kwok K.

    2007-11-20

    A composite transistor is disclosed for use in radiation hardening a CMOS IC formed on an SOI or bulk semiconductor substrate. The composite transistor has a circuit transistor and a blocking transistor connected in series with a common gate connection. A body terminal of the blocking transistor is connected only to a source terminal thereof, and to no other connection point. The blocking transistor acts to prevent a single-event transient (SET) occurring in the circuit transistor from being coupled outside the composite transistor. Similarly, when a SET occurs in the blocking transistor, the circuit transistor prevents the SET from being coupled outside the composite transistor. N-type and P-type composite transistors can be used for each and every transistor in the CMOS IC to radiation harden the IC, and can be used to form inverters and transmission gates which are the building blocks of CMOS ICs.

  12. Edge mixing dynamics in graphene p-n junctions in the quantum Hall regime

    NASA Astrophysics Data System (ADS)

    Matsuo, Sadashige; Takeshita, Shunpei; Tanaka, Takahiro; Nakaharai, Shu; Tsukagoshi, Kazuhito; Moriyama, Takahiro; Ono, Teruo; Kobayashi, Kensuke

    2015-09-01

    Massless Dirac electron systems such as graphene exhibit a distinct half-integer quantum Hall effect, and in the bipolar transport regime co-propagating edge states along the p-n junction are realized. Additionally, these edge states are uniformly mixed at the junction, which makes it a unique structure to partition electrons in these edge states. Although many experimental works have addressed this issue, the microscopic dynamics of electron partition in this peculiar structure remains unclear. Here we performed shot-noise measurements on the junction in the quantum Hall regime as well as at zero magnetic field. We found that, in sharp contrast with the zero-field case, the shot noise in the quantum Hall regime is finite in the bipolar regime, but is strongly suppressed in the unipolar regime. Our observation is consistent with the theoretical prediction and gives microscopic evidence that the edge states are uniquely mixed along the p-n junction.

  13. Edge mixing dynamics in graphene p–n junctions in the quantum Hall regime

    PubMed Central

    Matsuo, Sadashige; Takeshita, Shunpei; Tanaka, Takahiro; Nakaharai, Shu; Tsukagoshi, Kazuhito; Moriyama, Takahiro; Ono, Teruo; Kobayashi, Kensuke

    2015-01-01

    Massless Dirac electron systems such as graphene exhibit a distinct half-integer quantum Hall effect, and in the bipolar transport regime co-propagating edge states along the p–n junction are realized. Additionally, these edge states are uniformly mixed at the junction, which makes it a unique structure to partition electrons in these edge states. Although many experimental works have addressed this issue, the microscopic dynamics of electron partition in this peculiar structure remains unclear. Here we performed shot-noise measurements on the junction in the quantum Hall regime as well as at zero magnetic field. We found that, in sharp contrast with the zero-field case, the shot noise in the quantum Hall regime is finite in the bipolar regime, but is strongly suppressed in the unipolar regime. Our observation is consistent with the theoretical prediction and gives microscopic evidence that the edge states are uniquely mixed along the p–n junction. PMID:26337445

  14. Complete gate control of supercurrent in graphene p-n junctions

    NASA Astrophysics Data System (ADS)

    Choi, Jae-Hyun; Lee, Gil-Ho; Park, Sunghun; Jeong, Dongchan; Lee, Jeong-O.; Sim, H.-S.; Doh, Yong-Joo; Lee, Hu-Jong

    2013-09-01

    In a conventional Josephson junction of graphene, the supercurrent is not turned off even at the charge neutrality point, impeding further development of superconducting quantum information devices based on graphene. Here we fabricate bipolar Josephson junctions of graphene, in which a p-n potential barrier is formed in graphene with two closely spaced superconducting contacts, and realize supercurrent ON/OFF states using electrostatic gating only. The bipolar Josephson junctions of graphene also show fully gate-driven macroscopic quantum tunnelling behaviour of Josephson phase particles in a potential well, where the confinement energy is gate tuneable. We suggest that the supercurrent OFF state is mainly caused by a supercurrent dephasing mechanism due to a random pseudomagnetic field generated by ripples in graphene, in sharp contrast to other nanohybrid Josephson junctions. Our study may pave the way for the development of new gate-tuneable superconducting quantum information devices.

  15. Complete gate control of supercurrent in graphene p-n junctions.

    PubMed

    Choi, Jae-Hyun; Lee, Gil-Ho; Park, Sunghun; Jeong, Dongchan; Lee, Jeong-O; Sim, H-S; Doh, Yong-Joo; Lee, Hu-Jong

    2013-01-01

    In a conventional Josephson junction of graphene, the supercurrent is not turned off even at the charge neutrality point, impeding further development of superconducting quantum information devices based on graphene. Here we fabricate bipolar Josephson junctions of graphene, in which a p-n potential barrier is formed in graphene with two closely spaced superconducting contacts, and realize supercurrent ON/OFF states using electrostatic gating only. The bipolar Josephson junctions of graphene also show fully gate-driven macroscopic quantum tunnelling behaviour of Josephson phase particles in a potential well, where the confinement energy is gate tuneable. We suggest that the supercurrent OFF state is mainly caused by a supercurrent dephasing mechanism due to a random pseudomagnetic field generated by ripples in graphene, in sharp contrast to other nanohybrid Josephson junctions. Our study may pave the way for the development of new gate-tuneable superconducting quantum information devices. PMID:24056682

  16. Tobacco Use in Bipolar Disorder

    PubMed Central

    Thomson, Daniel; Berk, Michael; Dodd, Seetal; Rapado-Castro, Marta; Quirk, Shae E.; Ellegaard, Pernille K.; Berk, Lesley; Dean, Olivia M.

    2015-01-01

    Tobacco use in mental health in general and bipolar disorder in particular remains disproportionally common, despite declining smoking rates in the community. Furthermore, interactions between tobacco use and mental health have been shown, indicating the outcomes for those with mental health disorders are impacted by tobacco use. Factors need to be explored and addressed to improve outcomes for those with these disorders and target specific interventions for people with psychiatric illness to cease tobacco smoking. In the context of bipolar disorder, this review explores; the effects of tobacco smoking on symptoms, quality of life, suicidal behaviour, the biological interactions between tobacco use and bipolar disorder, the interactions between tobacco smoking and psychiatric medications, rates and factors surrounding tobacco smoking cessation in bipolar disorder and suggests potential directions for research and clinical translation. The importance of this review is to bring together the current understanding of tobacco use in bipolar disorder to highlight the need for specific intervention. PMID:25912533

  17. Tobacco use in bipolar disorder.

    PubMed

    Thomson, Daniel; Berk, Michael; Dodd, Seetal; Rapado-Castro, Marta; Quirk, Shae E; Ellegaard, Pernille K; Berk, Lesley; Dean, Olivia M

    2015-04-30

    Tobacco use in mental health in general and bipolar disorder in particular remains disproportionally common, despite declining smoking rates in the community. Furthermore, interactions between tobacco use and mental health have been shown, indicating the outcomes for those with mental health disorders are impacted by tobacco use. Factors need to be explored and addressed to improve outcomes for those with these disorders and target specific interventions for people with psychiatric illness to cease tobacco smoking. In the context of bipolar disorder, this review explores; the effects of tobacco smoking on symptoms, quality of life, suicidal behavior, the biological interactions between tobacco use and bipolar disorder, the interactions between tobacco smoking and psychiatric medications, rates and factors surrounding tobacco smoking cessation in bipolar disorder and suggests potential directions for research and clinical translation. The importance of this review is to bring together the current understanding of tobacco use in bipolar disorder to highlight the need for specific intervention. PMID:25912533

  18. Optical pulse generation in a transistor laser via intra-cavity photon-assisted tunneling and excess base carrier redistribution

    SciTech Connect

    Feng, M.; Iverson, E. W.; Wang, C. Y.; Holonyak, N.

    2015-11-02

    For a direct-gap semiconductor (e.g., a p-n junction), photon-assisted tunneling is known to exhibit a high nonlinear absorption. In a transistor laser, as discussed here, the coherent photons generated at the quantum well interact with the collector junction field and “assist” electron tunneling from base to collector, thus resulting in the nonlinear modulation of the laser and the realization of optical pulse generation. 1 and 2 GHz optical pulses are demonstrated in the transistor laser using collector voltage control.

  19. Investigation of effective base transit time and current gain modulation of light-emitting transistors under different ambient temperatures

    SciTech Connect

    Yang, Hao-Hsiang; Tu, Wen-Chung; Wang, Hsiao-Lun; Wu, Chao-Hsin

    2014-11-03

    In this report, the modulation of current gain of InGaP/GaAs light-emitting transistors under different ambient temperatures are measured and analyzed using thermionic emission model of quantum well embedded in the transistor base region. Minority carriers captured by quantum wells gain more energy at high temperatures and escape from quantum wells resulting in an increase of current gain and lower optical output, resulting in different I-V characteristics from conventional heterojunction bipolar transistors. The effect of the smaller thermionic lifetime thus reduces the effective base transit time of transistors at high temperatures. The unique current gain enhancement of 27.61% is achieved when operation temperature increase from 28 to 85 °C.

  20. Bipolar disorder in women

    PubMed Central

    Parial, Sonia

    2015-01-01

    Bipolar affective disorder in women is a challenging disorder to treat. It is unique in its presentation in women and characterized by later age of onset, seasonality, atypical presentation, and a higher degree of mixed episodes. Medical and psychiatric co-morbidity adversely affects recovery from the bipolar disorder (BD) more often in women. Co-morbidity, particularly thyroid disease, migraine, obesity, and anxiety disorders occur more frequently in women while substance use disorders are more common in men. Treatment of women during pregnancy and lactation is challenging. Pregnancy neither protects nor exacerbates BD, and many women require continuation of medication during the pregnancy. The postpartum period is a time of high risk for onset and recurrence of BD in women. Prophylaxis with mood stabilizers might be needed. Individualized risk/benefits assessments of pregnant and postpartum women with BD are required to promote the health of the women and to avoid or limit exposure of the fetus or infant to potential adverse effects of medication. PMID:26330643

  1. Bipolar pulse forming line

    DOEpatents

    Rhodes, Mark A.

    2008-10-21

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  2. Improved chopper circuit uses parallel transistors

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Parallel transistor chopper circuit operates with one transistor in the forward mode and the other in the inverse mode. By using this method, it acts as a single, symmetrical, bidirectional transistor, and reduces and stabilizes the offset voltage.

  3. Avalanche transistor selection for long term stability in streak camera sweep and pulser applications

    SciTech Connect

    Thomas, S.W.; Griffith, R.L.; Teruya, A.T.

    1990-09-05

    We have identified the Motorola 2N4014 and 2N5551 and the Raytheon RS3944 as three transistor types that exhibit avalanche characteristics and have long term collector breakdown voltage stability superior to other transistors tested. Stability on all types has been improved by power burnin. An automatic avalanche transistor burnin tester has been constructed to allow power burnin of up to 1008 transistors at a time. The tester is controlled by an IBM Personal Computer (PC) and can be programmed to acquire data, unattended, at any desired rate or period. Data are collected from each run and stored on a floppy disk in ASCII format. The data analysis software, RS/1, was used for analysis and display. Data runs were typically 3 to 4 months long, with readings taken weekly. The transistors were biased into the avalanche or Zener region by individual current sources set to about 20% of the self-avalanche current for each type of transistor. Motorola, Zetex and National transistors were operated at 100 microamperes ({mu}A), and the Raytheon units were operated at 20 {mu}A. The electric field causes migration of material in the high field region at the surface near the collector-base junction, creating the voltage instability. 7 refs., 9 figs., 1 tab.

  4. Influence of a perpendicular magnetic field on the thermal depinning of a single Abrikosov vortex in a superconducting Josephson junction

    SciTech Connect

    Kouzoudis, D.

    1999-02-12

    The prime interest of the present research is to measure the thermal energy needed for depinning a trapped vortex when an external magnetic field is perpendicular to the plane of the junction, and thus there are Meissner currents flowing along the edge of the film. These currents introduce an additional force and the author wishes to study thermal depinning under the influence of this force. These studies are of interest because Nb junctions are used in a wide range of electronic applications. Such junctions are useful, for instance, in superconducting quantum interference devices (SQUIDs) or in vortex-flow transistors because their performance can be enhanced by tuning the parameters of the individual junctions to optimum operation values. Furthermore gated Josephson junctions can be used as Josephson field-effect transistors (JOFETs).

  5. Chemoresponsive Monolayer Transistors

    SciTech Connect

    Guo,X.; Myers, M.; Xiao, S.; Lefenfeld, M.; Steiner, R.; Tulevski, G.; Tang, J.; Baumert, J.; Leibfarth, F.; et al.

    2006-01-01

    This work details a method to make efficacious field-effect transistors from monolayers of polycyclic aromatic hydrocarbons that are able to sense and respond to their chemical environment. The molecules used in this study are functionalized so that they assemble laterally into columns and attach themselves to the silicon oxide surface of a silicon wafer. To measure the electrical properties of these monolayers, we use ultrasmall point contacts that are separated by only a few nanometers as the source and drain electrodes. These contacts are formed through an oxidative cutting of an individual metallic single-walled carbon nanotube that is held between macroscopic metal leads. The molecules assemble in the gap and form transistors with large current modulation and high gate efficiency. Because these devices are formed from an individual stack of molecules, their electrical properties change significantly when exposed to electron-deficient molecules such as tetracyanoquinodimethane (TCNQ), forming the basis for new types of environmental and molecular sensors.

  6. TRANSISTOR HIGH VOLTAGE POWER SUPPLY

    DOEpatents

    Driver, G.E.

    1958-07-15

    High voltage, direct current power supplies are described for use with battery powered nuclear detection equipment. The particular advantages of the power supply described, are increased efficiency and reduced size and welght brought about by the use of transistors in the circuit. An important feature resides tn the employment of a pair of transistors in an alternatefiring oscillator circuit having a coupling transformer and other circuit components which are used for interconnecting the various electrodes of the transistors.

  7. Polarization induced doped transistor

    DOEpatents

    Xing, Huili; Jena, Debdeep; Nomoto, Kazuki; Song, Bo; Zhu, Mingda; Hu, Zongyang

    2016-06-07

    A nitride-based field effect transistor (FET) comprises a compositionally graded and polarization induced doped p-layer underlying at least one gate contact and a compositionally graded and doped n-channel underlying a source contact. The n-channel is converted from the p-layer to the n-channel by ion implantation, a buffer underlies the doped p-layer and the n-channel, and a drain underlies the buffer.

  8. Solitons in Josephson junctions

    NASA Astrophysics Data System (ADS)

    Ustinov, A. V.

    1998-11-01

    Magnetic flux quanta in Josephson junctions, often called fluxons, in many cases behave as solitons. A review of recent experiments and modelling of fluxon dynamics in Josephson circuits is presented. Classic quasi-one-dimensional junctions, stacked junctions (Josephson superlattices), and discrete Josephson transmission lines (JTLs) are discussed. Applications of fluxon devices as high-frequency oscillators and digital circuits are also addressed.

  9. Methods for calculating SEU rates for bipolar and NMOS circuits

    NASA Astrophysics Data System (ADS)

    McNulty, P. J.; Abdel-Kader, W. G.; Bisgrove, J. M.

    1985-12-01

    Computer codes developed at Clarkson for simulating charge generation by proton-induced nuclear reactions in well-defined silicon microstructures can be used to calculate SEU rates for specific devices when the critical charge and the dimensions of all SEU sensitive junctions on the device are known, provided one can estimate the contribution from externally-generated charge which enters the sensitive junction by drift and diffusion. Calculations for two important bipolar devices, the AMD 2901B bit slice and the Fairchild 93L422 RAM, for which the dimensions of the sensitive volumes were estimated from available heavy-ion test data, have been found to be in agreement with experimental data. Circuit data for the Intel 2164A, an alpha sensitive dRAM, was provided by the manufacturer. Calculations based on crude assumptions regarding which nuclear recoils and which alphas trigger upsets in the 2164A were found to agree with experimental data.

  10. Basic Electronics II.

    ERIC Educational Resources Information Center

    Willison, Neal A.; Shelton, James K.

    Designed for use in basic electronics programs, this curriculum guide is comprised of 15 units of instruction. Unit titles are Review of the Nature of Matter and the P-N Junction, Rectifiers, Filters, Special Semiconductor Diodes, Bipolar-Junction Diodes, Bipolar Transistor Circuits, Transistor Amplifiers, Operational Amplifiers, Logic Devices,…

  11. Psychotherapeutic Treatment of Bipolar Depression.

    PubMed

    McMahon, Kibby; Herr, Nathaniel R; Zerubavel, Noga; Hoertel, Nicolas; Neacsiu, Andrada D

    2016-03-01

    The gold standard for treating bipolar depression is based on the combination of mood stabilizers and psychotherapy. Therefore, the authors present evidence-based models and promising approaches for psychotherapy for bipolar depression. Cognitive-behavioral therapy, family focused therapy, interpersonal and social rhythm therapy, mindfulness-based cognitive therapy, and dialectical behavior therapy are discussed. Behavioral activation, the cognitive behavioral analysis system of psychotherapy, and the unified protocol as promising future directions are presented. This review informs medical providers of the most appropriate referral guidelines for psychotherapy for bipolar depression. The authors conclude with a decision tree delineating optimal referrals to each psychotherapy approach. PMID:26876317

  12. Asenapine for bipolar disorder

    PubMed Central

    Scheidemantel, Thomas; Korobkova, Irina; Rej, Soham; Sajatovic, Martha

    2015-01-01

    Asenapine (Saphris®) is an atypical antipsychotic drug which has been approved by the US Food and Drug Administration for the treatment of schizophrenia in adults, as well as the treatment of acute manic or mixed episodes of bipolar I in both adult and pediatric populations. Asenapine is a tetracyclic drug with antidopaminergic and antiserotonergic activity with a unique sublingual route of administration. In this review, we examine and summarize the available literature on the safety, efficacy, and tolerability of asenapine in the treatment of bipolar disorder (BD). Data from randomized, double-blind trials comparing asenapine to placebo or olanzapine in the treatment of acute manic or mixed episodes showed asenapine to be an effective monotherapy treatment in clinical settings; asenapine outperformed placebo and showed noninferior performance to olanzapine based on improvement in the Young Mania Rating Scale scores. There are limited data available on the use of asenapine in the treatment of depressive symptoms of BD, or in the maintenance phase of BD. The available data are inconclusive, suggesting the need for more robust data from prospective trials in these clinical domains. The most commonly reported adverse effect associated with use of asenapine is somnolence. However, the somnolence associated with asenapine use did not cause significant rates of discontinuation. While asenapine was associated with weight gain when compared to placebo, it appeared to be modest when compared to other atypical antipsychotics, and its propensity to cause increases in hemoglobin A1c or serum lipid levels appeared to be similarly modest. Asenapine does not appear to cause any clinically significant QTc prolongation. The most commonly reported extra-pyramidal symptom associated with asenapine was akathisia. Overall, asenapine appears to be a relatively well-tolerated atypical antipsychotic, effective in the treatment of acute manic and mixed episodes of BD. PMID:26674884

  13. Bipolar disorder and multiple sclerosis.

    PubMed

    Ybarra, Mariana Inés; Moreira, Marcos Aurélio; Araújo, Carolina Reis; Lana-Peixoto, Marco Aurélio; Teixeira, Antonio Lucio

    2007-12-01

    Bipolar disorder may be overrepresented in multiple sclerosis (MS) patients. Although research in this area is limited, studies assessing the nature of this association have focused on genetic aspects, adverse reaction to drugs and brain demyelinating lesions. Herein we report three patients with MS that also presented bipolar disorder. The coexistence of neurological and psychiatric symptoms in most MS relapses highlights the relevance of biological factors in the emergence of mood disorders in these patients. PMID:18345425

  14. Superconducting Field-Effect Transistors

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul; Romanofsky, Robert R.; Tabib-Azar, Massood

    1995-01-01

    Devices offer switching speeds greater than semiconducting counterparts. High-Tc superconducting field-effect transistors (SUPEFETs) investigated for use as electronic switches in delay-line-type microwave phase shifters. Resemble semiconductor field-effect transistors in some respects, but their operation based on different principle; namely, electric-field control of transition between superconductivity and normal conductivity.

  15. Threat sensitivity in bipolar disorder.

    PubMed

    Muhtadie, Luma; Johnson, Sheri L

    2015-02-01

    Life stress is a major predictor of the course of bipolar disorder. Few studies have used laboratory paradigms to examine stress reactivity in bipolar disorder, and none have assessed autonomic reactivity to laboratory stressors. In the present investigation we sought to address this gap in the literature. Participants, 27 diagnosed with bipolar I disorder and 24 controls with no history of mood disorder, were asked to complete a complex working memory task presented as "a test of general intelligence." Self-reported emotions were assessed at baseline and after participants were given task instructions; autonomic physiology was assessed at baseline and continuously during the stressor task. Compared to controls, individuals with bipolar disorder reported greater increases in pretask anxiety from baseline and showed greater cardiovascular threat reactivity during the task. Group differences in cardiovascular threat reactivity were significantly correlated with comorbid anxiety in the bipolar group. Our results suggest that a multimethod approach to assessing stress reactivity-including the use of physiological parameters that differentiate between maladaptive and adaptive profiles of stress responding-can yield valuable information regarding stress sensitivity and its associations with negative affectivity in bipolar disorder. (PsycINFO Database Record (c) 2015 APA, all rights reserved). PMID:25688436

  16. Vertical Ge and GeSn heterojunction gate-all-around tunneling field effect transistors

    NASA Astrophysics Data System (ADS)

    Schulze, Jörg; Blech, Andreas; Datta, Arnab; Fischer, Inga A.; Hähnel, Daniel; Naasz, Sandra; Rolseth, Erlend; Tropper, Eva-Maria

    2015-08-01

    We present experimental results on the fabrication and characterization of vertical Ge and GeSn heterojunction Tunneling Field Effect Transistors (TFETs). A gate-all-around process with mesa diameters down to 70 nm is used to reduce leakage currents and improve electrostatic control of the gate over the transistor channel. An ION = 88.4 μA/μm at VDS = VG = -2 V is obtained for a TFET with a 10 nm Ge0.92Sn0.08 layer at the source/channel junction. We discuss further possibilities for device improvements.

  17. High resolution thermoreflectance imaging on transistor arrays with defect-induced leakage

    NASA Astrophysics Data System (ADS)

    Tessier, G.; Filloy, C.; Polignano, M. L.; Mica, I.; Jerosolimski, G.; Holé, S.; Fournier, D.

    2005-06-01

    Crystal defects are very harmful in present silicon devices when responsible for a source-to-drain junction piping and hence for a transistor leakage current. These effects are difficult to characterise with existing methods. Two transistor arrays including patterns critical for defect formation have been constructed and then characterised using a multiplexed CCD-based thermoreflectance microscope. Since this technique measures heating associated to defects, it does not discriminate dielectric breakdown and actual source-to-drain leakage. Both types of defects, buried under 6 μm of intermetal and encapsulation dielectric, are clearly detected with a spatial resolution of 350 nm.

  18. From transistor to nanotube

    NASA Astrophysics Data System (ADS)

    Boudenot, Jean-Claude

    2008-01-01

    We present here the main steps in the evolution of the transistor, since the tremendous invention of such a device and the introduction of the integrated circuit. We will then recall the main steps of Moore's law development. Nanotechnology began at the very beginning of the 21st century. Two aspects are presented in this article: the first, called 'More Moore', consists in continuing the laws of scale up to the physical limits; the second aspect, called 'beyond CMOS' explores new concepts such as spintronics, moletronics, nanotronics and other types of molecular electronics. To cite this article: J.-C. Boudenot, C. R. Physique 9 (2008).

  19. Power transistor switching characterization

    NASA Technical Reports Server (NTRS)

    Blackburn, D. L.

    1981-01-01

    The switching properties of power transistors are investigated. The devices studied were housed in IO-3 cases and were of an n(+)-p-n(-)-n(+) vertical dopant structure. The effects of the magnitude of the reverse-base current and temperature on the reverse-bias second breakdown characteristics are discussed. Brief discussions of device degradation due to second breakdown and of a constant voltage turn-off circuit are included. A description of a vacuum tube voltage clamp circuit which reduces clamped collector voltage overshoot is given.

  20. REGENERATIVE TRANSISTOR AMPLIFIER

    DOEpatents

    Kabell, L.J.

    1958-11-25

    Electrical circults for use in computers and the like are described. particularly a regenerative bistable transistor amplifler which is iurned on by a clock signal when an information signal permits and is turned off by the clock signal. The amplifier porforms the above function with reduced power requirements for the clock signal and circuit operation. The power requirements are reduced in one way by employing transformer coupling which increases the collector circuit efficiency by eliminating the loss of power in the collector load resistor.

  1. Bulk-barrier transistor

    NASA Astrophysics Data System (ADS)

    Mader, H.; Mueller, R.; Beinvogl, W.

    1983-10-01

    Experimental and theoretical results are presented on a bulk-barrier transistor (BBT). In this device the charge-carrier transportation is determined by an energy barrier, which is located inside a semiconductor. The barrier is the result of a space-charge region in a three-layered n-p-n or p-n-p structure with a very thin middle layer. The height of the energy barrier, which is adjustable by technological parameters, can be controlled by an external voltage.

  2. The coupled atom transistor.

    PubMed

    Jehl, X; Voisin, B; Roche, B; Dupont-Ferrier, E; De Franceschi, S; Sanquer, M; Cobian, M; Niquet, Y-M; Sklénard, B; Cueto, O; Wacquez, R; Vinet, M

    2015-04-22

    We describe the first implementation of a coupled atom transistor where two shallow donors (P or As) are implanted in a nanoscale silicon nanowire and their electronic levels are controlled with three gate voltages. Transport spectroscopy through these donors placed in series is performed both at zero and microwave frequencies. The coherence of the charge transfer between the two donors is probed by Landau-Zener-Stückelberg interferometry. Single-charge transfer at zero bias (electron pumping) has been performed and the crossover between the adiabatic and non-adiabatic regimes is studied. PMID:25783566

  3. The coupled atom transistor

    NASA Astrophysics Data System (ADS)

    Jehl, X.; Voisin, B.; Roche, B.; Dupont-Ferrier, E.; De Franceschi, S.; Sanquer, M.; Cobian, M.; Niquet, Y.-M.; Sklénard, B.; Cueto, O.; Wacquez, R.; Vinet, M.

    2015-04-01

    We describe the first implementation of a coupled atom transistor where two shallow donors (P or As) are implanted in a nanoscale silicon nanowire and their electronic levels are controlled with three gate voltages. Transport spectroscopy through these donors placed in series is performed both at zero and microwave frequencies. The coherence of the charge transfer between the two donors is probed by Landau-Zener-Stückelberg interferometry. Single-charge transfer at zero bias (electron pumping) has been performed and the crossover between the adiabatic and non-adiabatic regimes is studied.

  4. Alloyed 2D Metal-Semiconductor Atomic Layer Junctions.

    PubMed

    Kim, Ah Ra; Kim, Yonghun; Nam, Jaewook; Chung, Hee-Suk; Kim, Dong Jae; Kwon, Jung-Dae; Park, Sang Won; Park, Jucheol; Choi, Sun Young; Lee, Byoung Hun; Park, Ji Hyeon; Lee, Kyu Hwan; Kim, Dong-Ho; Choi, Sung Mook; Ajayan, Pulickel M; Hahm, Myung Gwan; Cho, Byungjin

    2016-03-01

    Heterostructures of compositionally and electronically variant two-dimensional (2D) atomic layers are viable building blocks for ultrathin optoelectronic devices. We show that the composition of interfacial transition region between semiconducting WSe2 atomic layer channels and metallic NbSe2 contact layers can be engineered through interfacial doping with Nb atoms. WxNb1-xSe2 interfacial regions considerably lower the potential barrier height of the junction, significantly improving the performance of the corresponding WSe2-based field-effect transistor devices. The creation of such alloyed 2D junctions between dissimilar atomic layer domains could be the most important factor in controlling the electronic properties of 2D junctions and the design and fabrication of 2D atomic layer devices. PMID:26839956

  5. Schottky versus bipolar 3.3 kV SiC diodes

    NASA Astrophysics Data System (ADS)

    Pérez-Tomás, A.; Brosselard, P.; Hassan, J.; Jordà, X.; Godignon, P.; Placidi, M.; Constant, A.; Millán, J.; Bergman, J. P.

    2008-12-01

    A comparative study of the electrical characteristics of 3.3 kV SiC Schottky barrier (SBD), junction bipolar Schottky (JBS) and PiN diodes is presented. 3.3 kV class 4H-SiC SBD, JBS and PiN diodes have been fabricated with an analogous technology process on similar epi wafers. Diodes have been characterized in forward, reverse and switching mode in the 25 °C-300 °C temperature range. The optimum performance of the diodes depends on the adequate use of the unipolar or bipolar advantages and is established by the final application specifications. In this respect, a reverse recovery charge versus on-resistance diagram for different current densities is also presented. DC stress tests have been performed to investigate the forward voltage drift, related to the formation of stacking faults, during the bipolar mode of operation.

  6. Axial SiGe Heteronanowire Tunneling Field-Effect Transistors

    SciTech Connect

    Le, Son T.; Jannaty, P.; Luo, Xu; Zaslavsky, A.; Perea, Daniel E.; Dayeh, Shadi A.; Picraux, Samuel T.

    2012-10-31

    We present silicon-compatible tri-gated p-Ge/i-Si/n-Si axial heteronanowire tunneling field-effect transistors (TFETs), where on-state tunneling occurs in the Ge drain section, while off-state leakage is dominated by the Si junction in the source. Our TFETs have high ION ~ 2 µA/µm, fully suppressed ambipolarity, and a sub-threshold slope SS ~ 140 mV/decade over 4 decades of current with lowest SS ~ 50 mV/decade. Device operation in the tunneling mode is confirmed by three-dimensional TCAD simulation. Interestingly, in addition to the TFET mode, our devices work as standard nanowire FETs with good ION/IOFF ratio when the source-drain junction is forward-biased. The improved transport in both biasing modes confirms the benefits of utilizing bandgap engineered axial nanowires for enhancing device performance.

  7. Integrated neurobiology of bipolar disorder.

    PubMed

    Maletic, Vladimir; Raison, Charles

    2014-01-01

    From a neurobiological perspective there is no such thing as bipolar disorder. Rather, it is almost certainly the case that many somewhat similar, but subtly different, pathological conditions produce a disease state that we currently diagnose as bipolarity. This heterogeneity - reflected in the lack of synergy between our current diagnostic schema and our rapidly advancing scientific understanding of the condition - limits attempts to articulate an integrated perspective on bipolar disorder. However, despite these challenges, scientific findings in recent years are beginning to offer a provisional "unified field theory" of the disease. This theory sees bipolar disorder as a suite of related neurodevelopmental conditions with interconnected functional abnormalities that often appear early in life and worsen over time. In addition to accelerated loss of volume in brain areas known to be essential for mood regulation and cognitive function, consistent findings have emerged at a cellular level, providing evidence that bipolar disorder is reliably associated with dysregulation of glial-neuronal interactions. Among these glial elements are microglia - the brain's primary immune elements, which appear to be overactive in the context of bipolarity. Multiple studies now indicate that inflammation is also increased in the periphery of the body in both the depressive and manic phases of the illness, with at least some return to normality in the euthymic state. These findings are consistent with changes in the hypothalamic-pituitary-adrenal axis, which are known to drive inflammatory activation. In summary, the very fact that no single gene, pathway, or brain abnormality is likely to ever account for the condition is itself an extremely important first step in better articulating an integrated perspective on both its ontological status and pathogenesis. Whether this perspective will translate into the discovery of innumerable more homogeneous forms of bipolarity is one of the

  8. Microwave field effect transistor

    NASA Technical Reports Server (NTRS)

    Huang, Ho-Chung (Inventor)

    1989-01-01

    Electrodes of a high power, microwave field effect transistor are substantially matched to external input and output networks. The field effect transistor includes a metal ground plane layer, a dielectric layer on the ground plane layer, a gallium arsenide active region on the dielectric layer, and substantially coplanar spaced source, gate, and drain electrodes having active segments covering the active region. The active segment of the gate electrode is located between edges of the active segments of the source and drain electrodes. The gate and drain electrodes include inactive pads remote from the active segments. The pads are connected directly to the input and output networks. The source electrode is connected to the ground plane layer. The space between the electrodes and the geometry of the electrodes extablish parasitic shunt capacitances and series inductances that provide substantial matches between the input network and the gate electrode and between the output network and the drain electrode. Many of the devices are connected in parallel and share a common active region, so that each pair of adjacent devices shares the same source electrodes and each pair of adjacent devices shares the same drain electrodes. The gate electrodes for the parallel devices are formed by a continuous stripe that extends between adjacent devices and is connected at different points to the common gate pad.

  9. Monolithic metal oxide transistors.

    PubMed

    Choi, Yongsuk; Park, Won-Yeong; Kang, Moon Sung; Yi, Gi-Ra; Lee, Jun-Young; Kim, Yong-Hoon; Cho, Jeong Ho

    2015-04-28

    We devised a simple transparent metal oxide thin film transistor architecture composed of only two component materials, an amorphous metal oxide and ion gel gate dielectric, which could be entirely assembled using room-temperature processes on a plastic substrate. The geometry cleverly takes advantage of the unique characteristics of the two components. An oxide layer is metallized upon exposure to plasma, leading to the formation of a monolithic source-channel-drain oxide layer, and the ion gel gate dielectric is used to gate the transistor channel effectively at low voltages through a coplanar gate. We confirmed that the method is generally applicable to a variety of sol-gel-processed amorphous metal oxides, including indium oxide, indium zinc oxide, and indium gallium zinc oxide. An inverter NOT logic device was assembled using the resulting devices as a proof of concept demonstration of the applicability of the devices to logic circuits. The favorable characteristics of these devices, including (i) the simplicity of the device structure with only two components, (ii) the benign fabrication processes at room temperature, (iii) the low-voltage operation under 2 V, and (iv) the excellent and stable electrical performances, together support the application of these devices to low-cost portable gadgets, i.e., cheap electronics. PMID:25777338

  10. Chemoresponsive monolayer transistors

    PubMed Central

    Guo, Xuefeng; Myers, Matthew; Xiao, Shengxiong; Lefenfeld, Michael; Steiner, Rachel; Tulevski, George S.; Tang, Jinyao; Baumert, Julian; Leibfarth, Frank; Yardley, James T.; Steigerwald, Michael L.; Kim, Philip; Nuckolls, Colin

    2006-01-01

    This work details a method to make efficacious field-effect transistors from monolayers of polycyclic aromatic hydrocarbons that are able to sense and respond to their chemical environment. The molecules used in this study are functionalized so that they assemble laterally into columns and attach themselves to the silicon oxide surface of a silicon wafer. To measure the electrical properties of these monolayers, we use ultrasmall point contacts that are separated by only a few nanometers as the source and drain electrodes. These contacts are formed through an oxidative cutting of an individual metallic single-walled carbon nanotube that is held between macroscopic metal leads. The molecules assemble in the gap and form transistors with large current modulation and high gate efficiency. Because these devices are formed from an individual stack of molecules, their electrical properties change significantly when exposed to electron-deficient molecules such as tetracyanoquinodimethane (TCNQ), forming the basis for new types of environmental and molecular sensors. PMID:16855049

  11. Treatment of bipolar disorder.

    PubMed

    Geddes, John R; Miklowitz, David J

    2013-05-11

    We review recent developments in the acute and long-term treatment of bipolar disorder and identify promising future routes to therapeutic innovation. Overall, advances in drug treatment remain quite modest. Antipsychotic drugs are effective in the acute treatment of mania; their efficacy in the treatment of depression is variable with the clearest evidence for quetiapine. Despite their widespread use, considerable uncertainty and controversy remains about the use of antidepressant drugs in the management of depressive episodes. Lithium has the strongest evidence for long-term relapse prevention; the evidence for anticonvulsants such as divalproex and lamotrigine is less robust and there is much uncertainty about the longer term benefits of antipsychotics. Substantial progress has been made in the development and assessment of adjunctive psychosocial interventions. Long-term maintenance and possibly acute stabilisation of depression can be enhanced by the combination of psychosocial treatments with drugs. The development of future treatments should consider both the neurobiological and psychosocial mechanisms underlying the disorder. We should continue to repurpose treatments and to recognise the role of serendipity. We should also investigate optimum combinations of pharmacological and psychotherapeutic treatments at different stages of the illness. Clarification of the mechanisms by which different treatments affect sleep and circadian rhythms and their relation with daily mood fluctuations is likely to help with the treatment selection for individual patients. To be economically viable, existing psychotherapy protocols need to be made briefer and more efficient for improved scalability and sustainability in widespread implementation. PMID:23663953

  12. Physical limits of silicon transistors and circuits

    NASA Astrophysics Data System (ADS)

    Keyes, Robert W.

    2005-12-01

    A discussion on transistors and electronic computing including some history introduces semiconductor devices and the motivation for miniaturization of transistors. The changing physics of field-effect transistors and ways to mitigate the deterioration in performance caused by the changes follows. The limits of transistors are tied to the requirements of the chips that carry them and the difficulties of fabricating very small structures. Some concluding remarks about transistors and limits are presented.

  13. Experimental and Simulated Results of Room Temperature Single Electron Transistor Formed by Atomic Force Microscopy Nano-Oxidation Process

    NASA Astrophysics Data System (ADS)

    Gotoh, Yoshitaka; Matsumoto, Kazuhiko; Bubanja, Vladimir; Vazquez, Francisco; Maeda, Tatsuro; Harris, James S.

    2000-04-01

    A planar-type single electron transistor (SET) was fabricated by the atomic force microscopy (AFM) nano-oxidation process. The fabricated SET showed the Coulomb oscillation characteristic with the period of about 2 V at room temperature. From the three-dimensional simulation, it is found out that the smaller the SET island size, the smaller the tunnel junction capacitance, and the tunnel junction capacitance shows a weak dependence on the tunnel junction width. Using the analytical model, the reason for this weak dependence was clarified.

  14. Targeting astrocytes in bipolar disorder.

    PubMed

    Peng, Liang; Li, Baoman; Verkhratsky, Alexei

    2016-06-01

    Astrocytes are homeostatic cells of the central nervous system, which are critical for development and maintenance of synaptic transmission and hence of synaptically connected neuronal ensembles. Astrocytic densities are reduced in bipolar disorder, and therefore deficient astroglial function may contribute to overall disbalance in neurotransmission and to pathological evolution. Classical anti-bipolar drugs (lithium salts, valproic acid and carbamazepine) affect expression of astroglial genes and modify astroglial signalling and homeostatic cascades. Many effects of both antidepressant and anti-bipolar drugs are exerted through regulation of glutamate homeostasis and glutamatergic transmission, through K(+) buffering, through regulation of calcium-dependent phospholipase A2 (that controls metabolism of arachidonic acid) or through Ca(2+) homeostatic and signalling pathways. Sometimes anti-depressant and anti-bipolar drugs exert opposite effects, and some effects on gene expression in drug treated animals are opposite in neurones vs. astrocytes. Changes in the intracellular pH induced by anti-bipolar drugs affect uptake of myo-inositol and thereby signalling via inositoltrisphosphate (InsP3), this being in accord with one of the main theories of mechanism of action for these drugs. PMID:27015045

  15. Chemical control over the energy-level alignment in a two-terminal junction

    NASA Astrophysics Data System (ADS)

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C. S. Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A.

    2016-07-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions.

  16. Chemical control over the energy-level alignment in a two-terminal junction

    PubMed Central

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C. S. Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A.

    2016-01-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions. PMID:27456200

  17. Chemical control over the energy-level alignment in a two-terminal junction.

    PubMed

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C S Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A

    2016-01-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions. PMID:27456200

  18. Spin transistor based on cadmium fluoride nanostructures

    SciTech Connect

    Bagraev, N. T. Gimbitskaya, O. N.; Klyachkin, L. E.; Malyarenko, A. M.; Shelykh, I. A.; Ryskin, A. I.; Shcheulin, A. S.

    2009-01-15

    A study of CdB{sub x}F{sub 2-x}/p-CdF{sub 2}/CdB{sub x}F{sub 2-x} planar sandwich structures fabricated on n-CdF{sub 2} crystal surface was carried out in order to obtain the spin-transistor effect at room temperature. Features related to the band gap of CdF{sub 2} (7.8 eV) along with those related to the spectrum for two-dimensional (2D) hole subbands in p-CdF{sub 2} quantum well (QW) were observed in the current-voltage characteristics for ultrashallow p{sup +}-n junctions. The results obtained demonstrate the important role for 2D hole subbands in the mechanism of the 'proximity effect' that appears due to Andreev's reflection in sandwich structures consisting of a narrow QW confined between superconducting barriers. Resonance behavior for the longitudinal voltage in a weak magnetic field normal to the plane of the p-CdF{sub 2} QW gives evidence for high degree of spin polarization for 2D holes. Analysis of the dependences for the 2D-hole-gas conductance on the magnitude and direction of the magnetic field normal to the plane of the p-CdF{sub 2} QW reveals anti-crossings for Zeeman sublevels in the singlet ground state and triplet excited state of boron dipole centers, responsible for the spin polarization of 2D holes in edge channels in the p-CdF{sub 2} QW. The high degree of spin polarization for 2D holes in edge channels in the p-CdF{sub 2} QW identifies the mechanism underlying spin-transistor I-V characteristics observed upon the variation of the gate voltage, which controls the magnitude of Bychkov-Rashba's spin-orbit coupling.

  19. Contact electrification field-effect transistor.

    PubMed

    Zhang, Chi; Tang, Wei; Zhang, Limin; Han, Changbao; Wang, Zhong Lin

    2014-08-26

    Utilizing the coupled metal oxide semiconductor field-effect transistor and triboelectric nanogenerator, we demonstrate an external force triggered/controlled contact electrification field-effect transistor (CE-FET), in which an electrostatic potential across the gate and source is created by a vertical contact electrification between the gate material and a “foreign” object, and the carrier transport between drain and source can be tuned/controlled by the contact-induced electrostatic potential instead of the traditional gate voltage. With the two contacted frictional layers vertically separated by 80 μm, the drain current is decreased from 13.4 to 1.9 μA in depletion mode and increased from 2.4 to 12.1 μA in enhancement mode at a drain voltage of 5 V. Compared with the piezotronic devices that are controlled by the strain-induced piezoelectric polarization charged at an interface/junction, the CE-FET has greatly expanded the sensing range and choices of materials in conjunction with semiconductors. The CE-FET is likely to have important applications in sensors, human–silicon technology interfacing, MEMS, nanorobotics, and active flexible electronics. Based on the basic principle of the CE-FET, a field of tribotronics is proposed for devices fabricated using the electrostatic potential created by triboelectrification as a “gate” voltage to tune/control charge carrier transport in conventional semiconductor devices. By the three-way coupling among triboelectricity, semiconductor, and photoexcitation, plenty of potentially important research fields are expected to be explored in the near future. PMID:25119657

  20. Mathematical models of bipolar disorder

    NASA Astrophysics Data System (ADS)

    Daugherty, Darryl; Roque-Urrea, Tairi; Urrea-Roque, John; Troyer, Jessica; Wirkus, Stephen; Porter, Mason A.

    2009-07-01

    We use limit cycle oscillators to model bipolar II disorder, which is characterized by alternating hypomanic and depressive episodes and afflicts about 1% of the United States adult population. We consider two non-linear oscillator models of a single bipolar patient. In both frameworks, we begin with an untreated individual and examine the mathematical effects and resulting biological consequences of treatment. We also briefly consider the dynamics of interacting bipolar II individuals using weakly-coupled, weakly-damped harmonic oscillators. We discuss how the proposed models can be used as a framework for refined models that incorporate additional biological data. We conclude with a discussion of possible generalizations of our work, as there are several biologically-motivated extensions that can be readily incorporated into the series of models presented here.

  1. Non-hysteretic superconducting quantum interference proximity transistor with enhanced responsivity

    SciTech Connect

    Jabdaraghi, R. N.; Meschke, M.; Pekola, J. P.

    2014-02-24

    This Letter presents fabrication and characterization of an optimized superconducting quantum interference proximity transistor. The present device, characterized by reduced tunnel junction area and shortened normal-metal section, demonstrates no hysteresis at low temperatures as we increased the Josephson inductance of the weak link by decreasing its cross section. It has consequently almost an order of magnitude improved magnetic field responsivity as compared to the earlier design. The modulation of both the current and the voltage across the junction have been measured as a function of magnetic flux piercing the superconducting loop.

  2. Transistorized converter provides nondissipative regulation

    NASA Technical Reports Server (NTRS)

    1964-01-01

    A transistorized regulator converter efficiently converts fluctuating input voltages to a constant output voltage, avoiding the use of saturable reactors. It is nondissipative in operation and functions in an open loop through variable duty cycles.

  3. High transconductance organic electrochemical transistors

    PubMed Central

    Khodagholy, Dion; Rivnay, Jonathan; Sessolo, Michele; Gurfinkel, Moshe; Leleux, Pierre; Jimison, Leslie H.; Stavrinidou, Eleni; Herve, Thierry; Sanaur, Sébastien; Owens, Róisín M.; Malliaras, George G.

    2013-01-01

    The development of transistors with high gain is essential for applications ranging from switching elements and drivers to transducers for chemical and biological sensing. Organic transistors have become well-established based on their distinct advantages, including ease of fabrication, synthetic freedom for chemical functionalization, and the ability to take on unique form factors. These devices, however, are largely viewed as belonging to the low-end of the performance spectrum. Here we present organic electrochemical transistors with a transconductance in the mS range, outperforming transistors from both traditional and emerging semiconductors. The transconductance of these devices remains fairly constant from DC up to a frequency of the order of 1 kHz, a value determined by the process of ion transport between the electrolyte and the channel. These devices, which continue to work even after being crumpled, are predicted to be highly relevant as transducers in biosensing applications. PMID:23851620

  4. Cryogenic ultra-low-noise SiGe transistor amplifier.

    PubMed

    Ivanov, B I; Trgala, M; Grajcar, M; Il'ichev, E; Meyer, H-G

    2011-10-01

    An ultra-low-noise one-stage SiGe heterojunction bipolar transistor amplifier was designed for cryogenic temperatures and a frequency range of 10 kHz-100 MHz. A noise temperature T(N) ≈ 1.4 K was measured at an ambient temperature of 4.2 K at frequencies between 100 kHz and 100 MHz for a source resistance of ~50 Ω. The voltage gain of the amplifier was 25 dB at a power consumption of 720 μW. The input voltage noise spectral density of the amplifier is about 35 pV/√Hz. The low noise resistance and power consumption makes the amplifier suitable for readout of resistively shunted DC SQUID magnetometers and amplifiers. PMID:22047315

  5. Bipolar lead acid battery development

    NASA Technical Reports Server (NTRS)

    Eskra, Michael; Vidas, Robin; Miles, Ronald; Halpert, Gerald; Attia, Alan; Perrone, David

    1991-01-01

    A modular bipolar battery configuration is under development at Johnson Control, Inc. (JCI) and the Jet Propulsion Laboratory (JPL). The battery design, incorporating proven lead acid electrochemistry, yields a rechargeable, high-power source that is light weight and compact. This configuration offers advantages in power capability, weight, and volume over conventional monopolar batteries and other battery chemistries. The lead acid bipolar battery operates in a sealed, maintenance-free mode allowing for maximum application flexibility. It is ideal for high-voltage and high-power applications.

  6. Bipolar lead acid battery development

    NASA Astrophysics Data System (ADS)

    Eskra, Michael; Vidas, Robin; Miles, Ronald; Halpert, Gerald; Attia, Alan; Perrone, David

    A modular bipolar battery configuration is under development at Johnson Control, Inc. (JCI) and the Jet Propulsion Laboratory (JPL). The battery design, incorporating proven lead acid electrochemistry, yields a rechargeable, high-power source that is light weight and compact. This configuration offers advantages in power capability, weight, and volume over conventional monopolar batteries and other battery chemistries. The lead acid bipolar battery operates in a sealed, maintenance-free mode allowing for maximum application flexibility. It is ideal for high-voltage and high-power applications.

  7. Refractory bipolar disorder and neuroprogression.

    PubMed

    da Costa, Sabrina C; Passos, Ives C; Lowri, Caroline; Soares, Jair C; Kapczinski, Flavio

    2016-10-01

    Immune activation and failure of physiologic compensatory mechanisms over time have been implicated in the pathophysiology of illness progression in bipolar disorder. Recent evidence suggests that such changes are important contributors to neuroprogression and may mediate the cross-sensitization of episode recurrence, trauma exposure and substance use. The present review aims to discuss the potential factors related to bipolar disorder refractoriness and neuroprogression. In addition, we will discuss the possible impacts of early therapeutic interventions as well as the alternative approaches in late stages of the disorder. PMID:26368941

  8. Bipolar dislocation of the clavicle.

    PubMed

    Jiang, Wei; Gao, Shu-Guang; Li, Yu-Sheng; Lei, Guang-Hua

    2012-11-01

    Bipolar dislocation of the clavicle at acromioclavicular and sternoclavicular joint is an uncommon traumatic injury. The conservative treatments adopted in the past is associated with redislocation dysfunction and deformity. A 41 years old lady with bipolar dislocation of right shoulder is treated surgically by open reduction and internal fixation by oblique T-plate at sternoclavicular joint and Kirschner wire stabilization at acromioclavicular joint. The patient showed satisfactory recovery with full range of motion of the right shoulder and normal muscular strength. The case reported in view of rarity and at 2 years followup. PMID:23325981

  9. Solder Bonding for Power Transistors

    NASA Technical Reports Server (NTRS)

    Snytsheuvel, H. A.; Mandel, H.

    1985-01-01

    Indium solder boosts power rating and facilitates circuit changes. Efficient heat conduction from power transistor to heat sink provided by layer of indium solder. Low melting point of indium solder (141 degrees C) allows power transistor to be removed, if circuit must be reworked, without disturbing other components mounted with ordinary solder that melts at 181 degrees C. Solder allows devices operated at higher power levels than does conventional attachment by screws.

  10. Three-junction solar cell

    DOEpatents

    Ludowise, Michael J.

    1986-01-01

    A photovoltaic solar cell is formed in a monolithic semiconductor. The cell contains three junctions. In sequence from the light-entering face, the junctions have a high, a medium, and a low energy gap. The lower junctions are connected in series by one or more metallic members connecting the top of the lower junction through apertures to the bottom of the middle junction. The upper junction is connected in voltage opposition to the lower and middle junctions by second metallic electrodes deposited in holes 60 through the upper junction. The second electrodes are connected to an external terminal.

  11. Bipolar supercurrent in graphene

    NASA Astrophysics Data System (ADS)

    Heersche, Hubert B.; Jarillo-Herrero, Pablo; Oostinga, Jeroen B.; Vandersypen, Lieven M. K.; Morpurgo, Alberto F.

    2007-03-01

    Graphene-a recently discovered form of graphite only one atomic layer thick-constitutes a new model system in condensed matter physics, because it is the first material in which charge carriers behave as massless chiral relativistic particles. The anomalous quantization of the Hall conductance, which is now understood theoretically, is one of the experimental signatures of the peculiar transport properties of relativistic electrons in graphene. Other unusual phenomena, like the finite conductivity of order 4e2/h (where e is the electron charge and h is Planck's constant) at the charge neutrality (or Dirac) point, have come as a surprise and remain to be explained. Here we experimentally study the Josephson effect in mesoscopic junctions consisting of a graphene layer contacted by two closely spaced superconducting electrodes. The charge density in the graphene layer can be controlled by means of a gate electrode. We observe a supercurrent that, depending on the gate voltage, is carried by either electrons in the conduction band or by holes in the valence band. More importantly, we find that not only the normal state conductance of graphene is finite, but also a finite supercurrent can flow at zero charge density. Our observations shed light on the special role of time reversal symmetry in graphene, and demonstrate phase coherent electronic transport at the Dirac point.

  12. Bipolar supercurrent in graphene.

    PubMed

    Heersche, Hubert B; Jarillo-Herrero, Pablo; Oostinga, Jeroen B; Vandersypen, Lieven M K; Morpurgo, Alberto F

    2007-03-01

    Graphene--a recently discovered form of graphite only one atomic layer thick--constitutes a new model system in condensed matter physics, because it is the first material in which charge carriers behave as massless chiral relativistic particles. The anomalous quantization of the Hall conductance, which is now understood theoretically, is one of the experimental signatures of the peculiar transport properties of relativistic electrons in graphene. Other unusual phenomena, like the finite conductivity of order 4e(2)/h (where e is the electron charge and h is Planck's constant) at the charge neutrality (or Dirac) point, have come as a surprise and remain to be explained. Here we experimentally study the Josephson effect in mesoscopic junctions consisting of a graphene layer contacted by two closely spaced superconducting electrodes. The charge density in the graphene layer can be controlled by means of a gate electrode. We observe a supercurrent that, depending on the gate voltage, is carried by either electrons in the conduction band or by holes in the valence band. More importantly, we find that not only the normal state conductance of graphene is finite, but also a finite supercurrent can flow at zero charge density. Our observations shed light on the special role of time reversal symmetry in graphene, and demonstrate phase coherent electronic transport at the Dirac point. PMID:17330038

  13. Evolvable circuit with transistor-level reconfigurability

    NASA Technical Reports Server (NTRS)

    Stoica, Adrian (Inventor); Salazar-Lazaro, Carlos Harold (Inventor)

    2004-01-01

    An evolvable circuit includes a plurality of reconfigurable switches, a plurality of transistors within a region of the circuit, the plurality of transistors having terminals, the plurality of transistors being coupled between a power source terminal and a power sink terminal so as to be capable of admitting power between the power source terminal and the power sink terminal, the plurality of transistors being coupled so that every transistor terminal to transistor terminal coupling within the region of the circuit comprises a reconfigurable switch.

  14. Polygenic dissection of the bipolar phenotype

    PubMed Central

    Hamshere, M. L.; O’Donovan, M. C.; Jones, I. R.; Jones, L.; Kirov, G.; Green, E. K.; Moskvina, V.; Grozeva, D.; Bass, N.; McQuillin, A.; Gurling, H.; St Clair, D.; Young, A. H.; Ferrier, I. N.; Farmer, A.; McGuffin, P.; Sklar, P.; Purcell, S.; Holmans, P. A.; Owen, M. J.; Craddock, N.

    2011-01-01

    Background Recent data provide strong support for a substantial common polygenic contribution (i.e. many alleles each of small effect) to genetic susceptibility for schizophrenia and overlapping susceptibility for bipolar disorder. Aims To test hypotheses about the relationship between schizophrenia and psychotic types of bipolar disorder. Method Using a polygenic score analysis to test whether schizophrenia polygenic risk alleles, en masse, significantly discriminate between individuals with bipolar disorder with and without psychotic features. The primary sample included 1829 participants with bipolar disorder and the replication sample comprised 506 people with bipolar disorder. Results The subset of participants with Research Diagnostic Criteria schizoaffective bipolar disorder (n = 277) were significantly discriminated from the remaining participants with bipolar disorder (n = 1552) in both the primary (P = 0.00059) and the replication data-sets (P = 0.0070). In contrast, those with psychotic bipolar disorder as a whole were not significantly different from those with non-psychotic bipolar disorder in either data-set. Conclusions Genetic susceptibility influences at least two major domains of psychopathological variation in the schizophrenia–bipolar disorder clinical spectrum: one that relates to expression of a ‘bipolar disorder-like’ phenotype and one that is associated with expression of ‘schizophrenia-like’ psychotic symptoms. PMID:21972277

  15. The management of bipolar disorder.

    PubMed

    Saunders, Kate E A; Geddes, John R

    2016-03-01

    Bipolar disorder is a common mental disorder which is relapsing and remitting in nature. Subsyndromal symptoms are common and associated with poorer outcomes. Management of the disorder can be challenging and depends on the polarity and severity of the mood episode. PMID:26961448

  16. Double heterojunction bipolar phototransistor model

    NASA Astrophysics Data System (ADS)

    Horak, Michal

    2003-07-01

    An analytical mathematical model of the double heterojunction NpN bipolar phototransistor with abrupt heterojunctions in three terminal configuration is presented. The thermionic-filed emission and diffusion of injected carriers is considered and the Ebers-Moll type relations for the collector and emitter current are obtained. Several steady state characteristics of the phototransistor structure are calculated (optical gain, quantum efficiency, responsivity).

  17. Suicidality in Bipolar I Disorder

    ERIC Educational Resources Information Center

    Johnson, Sheri L.; McMurrich, Stephanie L.; Yates, Marisa

    2005-01-01

    People with bipolar disorder are at high suicide risk. The literature suggests that suicidality is predicted by higher symptom severity and less use of pharmacological agents, but few studies have examined the joint contributions of these variables. The present study examines the conjoint contribution of symptom severity and pharmacological…

  18. [Cognitive deficits in bipolar disorder].

    PubMed

    Sachs, Gabriele; Schaffer, Markus; Winklbaur, Bernadette

    2007-01-01

    Bipolar disorders are often associated with cognitive deficits which have an influence on social functioning and the course of the illness. These deficits have an impact on occupational ability and social integration. To date, specific cognitive domains have been found which characterize bipolar affective disorders. However, there is evidence of stable and lasting cognitive impairment in all phases of the disorder, including the remission phase, in the following domains: sustained attention, memory and executive functions (e.g. cognitive flexibility and problem solving). Although their cognitive deficits are comparable the deficits in patients with schizophrenia are more severe than those with bipolar disorder. Recent brain imaging findings indicate structural and functional abnormalities in the cortical and limbic networks of the brain in patients with bipolar disorder compared to healthy controls. Mood stabilizer and atypical antipsychotics may reduce cognitive deficits in certain domains (e.g. executive functions and word fluency) and may have a positive effect on quality of life and social functioning. PMID:17640495

  19. Corrosion resistant metallic bipolar plate

    DOEpatents

    Brady, Michael P.; Schneibel, Joachim H.; Pint, Bruce A.; Maziasz, Philip J.

    2007-05-01

    A corrosion resistant, electrically conductive component such as a bipolar plate for a PEM fuel cell includes 20 55% Cr, balance base metal such as Ni, Fe, or Co, the component having thereon a substantially external, continuous layer of chromium nitride.

  20. Integrated Neurobiology of Bipolar Disorder

    PubMed Central

    Maletic, Vladimir; Raison, Charles

    2014-01-01

    From a neurobiological perspective there is no such thing as bipolar disorder. Rather, it is almost certainly the case that many somewhat similar, but subtly different, pathological conditions produce a disease state that we currently diagnose as bipolarity. This heterogeneity – reflected in the lack of synergy between our current diagnostic schema and our rapidly advancing scientific understanding of the condition – limits attempts to articulate an integrated perspective on bipolar disorder. However, despite these challenges, scientific findings in recent years are beginning to offer a provisional “unified field theory” of the disease. This theory sees bipolar disorder as a suite of related neurodevelopmental conditions with interconnected functional abnormalities that often appear early in life and worsen over time. In addition to accelerated loss of volume in brain areas known to be essential for mood regulation and cognitive function, consistent findings have emerged at a cellular level, providing evidence that bipolar disorder is reliably associated with dysregulation of glial–neuronal interactions. Among these glial elements are microglia – the brain’s primary immune elements, which appear to be overactive in the context of bipolarity. Multiple studies now indicate that inflammation is also increased in the periphery of the body in both the depressive and manic phases of the illness, with at least some return to normality in the euthymic state. These findings are consistent with changes in the hypothalamic–pituitary–adrenal axis, which are known to drive inflammatory activation. In summary, the very fact that no single gene, pathway, or brain abnormality is likely to ever account for the condition is itself an extremely important first step in better articulating an integrated perspective on both its ontological status and pathogenesis. Whether this perspective will translate into the discovery of innumerable more homogeneous forms of

  1. Nanofluidic Transistor Circuits

    NASA Astrophysics Data System (ADS)

    Chang, Hsueh-Chia; Cheng, Li-Jing; Yan, Yu; Slouka, Zdenek; Senapati, Satyajyoti

    2012-02-01

    Non-equilibrium ion/fluid transport physics across on-chip membranes/nanopores is used to construct rectifying, hysteretic, oscillatory, excitatory and inhibitory nanofluidic elements. Analogs to linear resistors, capacitors, inductors and constant-phase elements were reported earlier (Chang and Yossifon, BMF 2009). Nonlinear rectifier is designed by introducing intra-membrane conductivity gradient and by asymmetric external depletion with a reverse rectification (Yossifon and Chang, PRL, PRE, Europhys Lett 2009-2011). Gating phenomenon is introduced by functionalizing polyelectrolytes whose conformation is field/pH sensitive (Wang, Chang and Zhu, Macromolecules 2010). Surface ion depletion can drive Rubinstein's microvortex instability (Chang, Yossifon and Demekhin, Annual Rev of Fluid Mech, 2012) or Onsager-Wien's water dissociation phenomenon, leading to two distinct overlimiting I-V features. Bipolar membranes exhibit an S-hysteresis due to water dissociation (Cheng and Chang, BMF 2011). Coupling the hysteretic diode with some linear elements result in autonomous ion current oscillations, which undergo classical transitions to chaos. Our integrated nanofluidic circuits are used for molecular sensing, protein separation/concentration, electrospray etc.

  2. Single-Electron Transistors

    NASA Astrophysics Data System (ADS)

    Fulton, T. A.

    2000-03-01

    Subsequent to the early work, the basic all-metal single-electron transistor (SET) and its semiconductor counterparts have become widely studied, both for their own behavior and for applications. For many people, the SET is an everyday research tool whose inner workings, even though they depend on charge quantization and the energy-time uncertainty principle, can readily be understood (given electron tunneling) by simple arguments based on elementary circuit models. Our own further studies, in various collaborations, were first concerned with finding and studying interactions between charging effects and Josephson tunneling in SET circuits, which had been the original motivation. Later, looking into applications for SETs, we demonstrated a crude but recognizable form of single-electron memory. Significant digital-circuit applications of SETs still seem remote, alas, but some analog applications are promising. Recently, in an ongoing collaboration, we have fabricated an SET on the tip of a tapered glass fiber for use as a scanning probe. With it, we have mapped the electric fields over a two-dimensional electron gas having a density, n, that varies with position. In the quantum Hall regime, step-like changes in surface potential are seen along lines where n corresponds to an integer filling factor ("edge-state regions"). Currently, we are investigating certain sub-micrometer structures, which sometimes form small networks, that appear in these regions. This structure seems to involve localization of individual electrons. note

  3. A novel Tunneling Graphene Nano Ribbon Field Effect Transistor with dual material gate: Numerical studies

    NASA Astrophysics Data System (ADS)

    Ghoreishi, Seyed Saleh; Saghafi, Kamyar; Yousefi, Reza; Moravvej-farshi, Mohammad Kazem

    2016-09-01

    In this work, we present Dual Material Gate Tunneling Graphene Nano-Ribbon Field Effect Transistors (DMG-T-GNRFET) mainly to suppress the am-bipolar current with assumption that sub-threshold swing which is one of the important characteristics of tunneling transistors must not be degraded. In the proposed structure, dual material gates with different work functions are used. Our investigations are based on numerical simulations which self-consistently solves the 2D Poisson based on an atomistic mode-space approach and Schrodinger equations, within the Non-Equilibrium Green's (NEGF). The proposed device shows lower off-current and on-off ratio becomes 5order of magnitude greater than the conventional device. Also two different short channel effects: Drain Induced Barrier Shortening (DIBS) and hot-electron effect are improved in the proposed device compare to the main structure.

  4. Spontaneous dissociation of bipolar hip hemiarthroplasty in a patient with nerve palsy: A case report and review of the literature

    PubMed Central

    Yuenyongviwat, Varah; Iamthanaporn, Khanin; Hongnaparak, Theerawit

    2015-01-01

    Introduction Dislocation after bipolar hemiarthroplasty is a common complication but dissociation of the prosthesis is rare. There are some reports of bipolar hemiarthroplasty dissociation at the inner head and outer shell. However, there are limited reports on acute spontaneous dissociation of the head and neck at the taper interface in bipolar hemiarthroplasty. Presentation of case A 65-year-old female had cemented bipolar hemi hip replacement after fixation failure of a dynamic hip screw. She had left lower limb weakness for ten years after previous spinal surgery. At the sixth week of postoperation, the patient had dissociation of the components of the bipolar hemiarthroplasty at the femoral head and neck junction. The patient had open reduction and femoral head revision. There was no re-dislocation at one-year follow-up. Discussion Dissociation of bipolar hemiarthroplasty is a complex complication that can happen from the modularity of the implant. This condition requires operative treatment. The mechanism and cause of failure should be identified before the operation. Conclusion To prevent this condition, preoperative planning and proper techniques should be done as an index procedure. In the case of marked shortening of the limb after an operation in patients with lower limb muscle weakness, we hypothesize that early full weight bearing with immediate use of a shoe lift might help prevent this condition. PMID:26339788

  5. Doped semiconductor nanocrystal junctions

    NASA Astrophysics Data System (ADS)

    Borowik, Ł.; Nguyen-Tran, T.; Roca i Cabarrocas, P.; Mélin, T.

    2013-11-01

    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (ND≈1020-1021cm-3) silicon nanocrystals (NCs) in the 2-50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as ND-1/3, and depleted charge linearly increasing with the NC diameter and varying as ND1/3. We thus establish a "nanocrystal counterpart" of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  6. Passivated ambipolar black phosphorus transistors

    NASA Astrophysics Data System (ADS)

    Yue, Dewu; Lee, Daeyeong; Jang, Young Dae; Choi, Min Sup; Nam, Hye Jin; Jung, Duk-Young; Yoo, Won Jong

    2016-06-01

    We report the first air-passivated ambipolar BP transistor formed by applying benzyl viologen, which serves as a surface charge transfer donor for BP flakes. The passivated BP devices exhibit excellent stability under both an ambient atmosphere and vacuum; their transistor performance is maintained semi-permanently. Unlike their intrinsic p-type properties, passivated BP devices present advantageous ambipolar properties with much higher electron mobility up to ~83 cm2 V-1 s-1 from 2-terminal measurement at 300 K, compared to other reported studies on n-type BP transistors. On the basis of the n-type doping effect that originated from benzyl viologen, we also systematically investigated the BP thickness dependence of our devices on electrical properties, in which we found the best electron transport performance to be attained when an ~10 nm thick BP flake was used.We report the first air-passivated ambipolar BP transistor formed by applying benzyl viologen, which serves as a surface charge transfer donor for BP flakes. The passivated BP devices exhibit excellent stability under both an ambient atmosphere and vacuum; their transistor performance is maintained semi-permanently. Unlike their intrinsic p-type properties, passivated BP devices present advantageous ambipolar properties with much higher electron mobility up to ~83 cm2 V-1 s-1 from 2-terminal measurement at 300 K, compared to other reported studies on n-type BP transistors. On the basis of the n-type doping effect that originated from benzyl viologen, we also systematically investigated the BP thickness dependence of our devices on electrical properties, in which we found the best electron transport performance to be attained when an ~10 nm thick BP flake was used. Electronic supplementary information (ESI) available: Transfer characteristics of BP field effect transistors (BV1-BV4) (Fig. S1 and S2 and Table S1); output characteristics of BP field effect transistors in different directions (Fig. S3

  7. Diagnosis and treatment of postpartum bipolar depression.

    PubMed

    Kelly, Erin; Sharma, Verinder

    2010-07-01

    The postpartum period is a time of increased risk of new-onset psychiatric illness, hospital admissions and out-patient psychiatric care for new mothers. Research into postpartum mood disorders has focused primarily on major depressive disorder, and has overlooked the study of bipolar disorder, particularly bipolar II disorder and bipolar disorder not otherwise specified. Failure to properly diagnose postpartum bipolar disorder may delay the initiation of appropriate treatment, lead to inappropriate treatment - thereby precipitating (hypo)mania, rapid cycling or a mixed episode - or result in polypharmacy and treatment refractoriness. The most serious consequence, however, is the high risk of infanticide and suicide among women with postpartum bipolar disorder. While no specific screening tools have been validated for postpartum mania or bipolar depression, symptoms of hypomania, atypical depression, a family history of bipolar disorder and a rapid onset of depressive symptoms following delivery may suggest a bipolar diathesis. In the absence of any pharmacological or psychotherapeutic treatments to guide clinical decision-making, it is recommended that the treatment of postpartum bipolar depression follow the same guidelines as the treatment of non-postpartum bipolar depression, using medications that are compatible with lactation. PMID:20586688

  8. Autocapture enhancements: unipolar and bipolar lead compatibility and bipolar pacing capability on bipolar leads.

    PubMed

    Binner, Ludwig; Messenger, John; Sperzel, Johannes; Bondke, Hansjürgen; Vandekerckhove, Yves; Poore, John; Scheiner, Jöerg; Berkhof, Marc; Park, Euljoon; Holmström, Nils; Bornzin, Gene A

    2003-01-01

    Beat-by-beat Autocapture maximizes device longevity by minimizing stimulus amplitude while assuring patient safety. Currently, Autocapture permits use of only bipolar leads. The authors have devised a detection method that operates with unipolar and bipolar leads and covers all pacing and sensing combinations (but bipolar pace and sense simultaneously). This new detection method for unipolar sensing uses the integral of the negative portion of the unipolar evoked response as a robust capture detection feature. When using bipolar leads, the method provides the flexibility of bipolar or unipolar pacing. In this study, unipolar ventricular intracardiac electrograms (EGMs) were recorded in 71 patients, 73.7 +/- 9.9 years of age; 9 with high polarization, 62 with low polarization. High polarization had polished platinum or activated carbon electrodes. Low polarization had TiN, platinized platinum, or IrOx electrodes. The intracardiac EGMs were recorded 544 +/- 796 days after implant. The pacemakers performed an automatic capture threshold test while the intracardiac EGM signals were recorded in a programmer. These digitized signals were saved for off-line analysis. The unipolar evoked response was calculated at up to six (depending on capture threshold) pacing voltages and the polarization integral at 4.5 V and at loss of capture. An automatic calibration algorithm determined if the signal-to-noise ratio was adequate for Autocapture operation. Autocapture was possible with 60 of 62 of the low polarizations, and with 6 of 9 of the high polarizations. The average values form the data collected were: average unipolar evoked response--4.1 +/- 2.1 mV, average peak negative voltage--10.0 +/- 3.7 mV, average polarization 0.3 +/- 0.34 mV, and average signal-to-noise ratio (unipolar evoked response/ polarization) 38 +/- 71. In all cases the algorithm correctly determined the appropriateness of using Autocapture with the electrodes tested and the unipolar evoked response

  9. Nicotine dependence and psychosis in Bipolar disorder and Schizoaffective disorder, Bipolar type.

    PubMed

    Estrada, Elena; Hartz, Sarah M; Tran, Jeffrey; Hilty, Donald M; Sklar, Pamela; Smoller, Jordan W; Pato, Michele T; Pato, Carlos N

    2016-06-01

    Patients with Bipolar disorder smoke more than the general population. Smoking negatively impacts mortality and clinical course in Bipolar disorder patients. Prior studies have shown contradictory results regarding the impact of psychosis on smoking behavior in Bipolar disorder. We analyzed a large sample of Bipolar disorder and Schizoaffective disorder, Bipolar Type patients and predicted those with a history of psychosis would be more likely to be nicotine dependent. Data from subjects and controls were collected from the Genomic Psychiatry Cohort (GPC). Subjects were diagnosed with Bipolar disorder without psychosis (N = 610), Bipolar disorder with psychosis (N = 1544). Participants were classified with or without nicotine dependence. Diagnostic groups were compared to controls (N = 10065) using logistic regression. Among smokers (N = 6157), those with Bipolar disorder had an increased risk of nicotine dependence (OR = 2.5; P < 0.0001). Patients with Bipolar disorder with psychosis were more likely to be dependent than Bipolar disorder patients without psychosis (OR = 1.3; P = 0.03). Schizoaffective disorder, Bipolar Type patients had more risk of nicotine dependence when compared to Bipolar disorder patients with or without psychosis (OR = 1.2; P = 0.02). Bipolar disorder patients experiencing more severity of psychosis have more risk of nicotine dependence. © 2015 Wiley Periodicals, Inc. PMID:26467098

  10. Metallic Electrode: Semiconducting Nanotube Junction Model

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryon (Technical Monitor)

    2001-01-01

    A model is proposed for two observed current-voltage (I-V) patterns in an experiment with a scanning tunneling microscope tip and a carbon nanotube [Collins et al., Science 278, 100 ('97)]. We claim that there are two contact modes for a tip (metal) -nanotube semi conductor) junction depending whether the alignment of the metal and semiconductor band structure is (1) variable (vacuum-gap) or (2) fixed (touching) with V. With the tip grounded, the tunneling case in (1) would produce large dI/dV with V > 0, small dI/dV with V < 0, and I = 0 near V = 0 for an either n- or p-nanotube. However, the Schottky mechanism in (2) would result in forward current with V < 0 for an n-nanotube, while with V > 0 for an p-nanotube. The two observed I-V patterns are thus entirely explained by a tip-nanotube contact of the two types, where the nanotube must be n-type. We apply this picture to the source-drain I-V characteristics in a long nanotube-channel field-effect-transistor (Zhou et al., Appl. Phys. Lett. 76, 1597 ('00)], and show that two independent metal-semiconductor junctions connected in series are responsible for the observed behavior.

  11. Quantum junction solar cells.

    PubMed

    Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO(2)); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. PMID:22881834

  12. Passivated ambipolar black phosphorus transistors.

    PubMed

    Yue, Dewu; Lee, Daeyeong; Jang, Young Dae; Choi, Min Sup; Nam, Hye Jin; Jung, Duk-Young; Yoo, Won Jong

    2016-07-01

    We report the first air-passivated ambipolar BP transistor formed by applying benzyl viologen, which serves as a surface charge transfer donor for BP flakes. The passivated BP devices exhibit excellent stability under both an ambient atmosphere and vacuum; their transistor performance is maintained semi-permanently. Unlike their intrinsic p-type properties, passivated BP devices present advantageous ambipolar properties with much higher electron mobility up to ∼83 cm(2) V(-1) s(-1) from 2-terminal measurement at 300 K, compared to other reported studies on n-type BP transistors. On the basis of the n-type doping effect that originated from benzyl viologen, we also systematically investigated the BP thickness dependence of our devices on electrical properties, in which we found the best electron transport performance to be attained when an ∼10 nm thick BP flake was used. PMID:27283027

  13. High current gain transistor laser.

    PubMed

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-01-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge. PMID:27282466

  14. High current gain transistor laser

    NASA Astrophysics Data System (ADS)

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-06-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge.

  15. High current gain transistor laser

    PubMed Central

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-01-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge. PMID:27282466

  16. Single gate p-n junctions in graphene-ferroelectric devices

    NASA Astrophysics Data System (ADS)

    Hinnefeld, J. Henry; Xu, Ruijuan; Rogers, Steven; Pandya, Shishir; Shim, Moonsub; Martin, Lane W.; Mason, Nadya

    2016-05-01

    Graphene's linear dispersion relation and the attendant implications for bipolar electronics applications have motivated a range of experimental efforts aimed at producing p-n junctions in graphene. Here we report electrical transport measurements of graphene p-n junctions formed via simple modifications to a PbZr0.2Ti0.8O3 substrate, combined with a self-assembled layer of ambient environmental dopants. We show that the substrate configuration controls the local doping region, and that the p-n junction behavior can be controlled with a single gate. Finally, we show that the ferroelectric substrate induces a hysteresis in the environmental doping which can be utilized to activate and deactivate the doping, yielding an "on-demand" p-n junction in graphene controlled by a single, universal backgate.

  17. Gap-junctional coupling of mammalian rod photoreceptors and its effect on visual detection

    PubMed Central

    Li, Peter H.; Verweij, Jan; Long, James H.; Schnapf, Julie L.

    2012-01-01

    The presence of gap junctions between rods in mammalian retina suggests a role for rod-rod coupling in human vision. Rod coupling is known to reduce response variability, but because junctional conductances are not known, the downstream effects on visual performance are uncertain. Here we assessed rod coupling in guinea pig retina by measuring: 1) the variability in responses to dim flashes, 2) Neurobiotin tracer coupling, and 3) junctional conductances. Results were consolidated into an electrical network model and a model of human psychophysical detection. Guinea pig rods form tracer pools of 1 to ~20 rods, with junctional conductances averaging ~350 pS. We calculate that coupling will reduce human dark-adapted sensitivity ~10% by impairing the noise filtering of the synapse between rods and rod bipolar cells. However, coupling also mitigates synaptic saturation and is thus calculated to improve sensitivity when stimuli are spatially restricted or are superimposed over background illumination. PMID:22399777

  18. Band-to-band tunneling field effect transistor for low power logic and memory applications: Design, fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Mookerjea, Saurabh A.

    Over the past decade the microprocessor clock frequency has hit a plateau. The main reason for this has been the inability to follow constant electric field scaling, which requires the transistor supply voltage to be scaled down as the transistor dimensions are reduced. Scaling the supply voltage down reduces the dynamic power quadratically but increases the static leakage power exponentially due to non-scalability of threshold voltage of the transistor, which is required to maintain the same ON state performance. This limitation in supply voltage scaling is directly related to MOSFET's (Metal Oxide Semiconductor Field Effect Transistor) sub-threshold slope (SS) limitation of 60 mV/dec at room temperature. Thus novel device design/materials are required that would allow the transistor to switch with sub-threshold slopes steeper than 60 mV/dec at room temperature, thus facilitating supply voltage scaling. Recently, a new class of devices known as super-steep slope (SS<60 mV/dec) transistors are under intense research for its potential to replace the ubiquitous MOSFET. The focus of this dissertation is on the design, fabrication and characterization of band-to-band tunneling field effect transistor (TFET) which belongs to the family of steep slope transistors. TFET with a gate modulated zener tunnel junction at the source allows sub-kT/q (sub-60 mV/dec at room temperature) sub-threshold slope (SS) device operation over a certain gate bias range near the off-state. This allows TFET to achieve much higher I ON-IOFF ratio over a specified gate voltage swing compared to MOSFETs, thus enabling aggressive supply voltage scaling for low power logic operation without impacting its ON-OFF current ratio. This dissertation presents the operating principle of TFET, the material selection strategy and device design for TFET fabrication. This is followed by a novel 6T SRAM design which circumvents the issue of unidirectional conduction in TFET. The switching behavior of TFET is

  19. [Psychopharmacological treatment of bipolar disease].

    PubMed

    Licht, Rasmus W; Vestergaard, Per

    2002-05-01

    This paper gives an update on the psychopharmacological treatment of bipolar disorder. The antimanic efficacy of lithium is well documented. The same applies to valproate, which is also efficacious in mixed mania. Conventional antipsychotics act fast in mania and do not require blood tests, but they have considerable neurological side effects. The newer antipsychotics, olanzapine, risperidone, and ziprasidone, have also been shown to have antimanic efficacy. Clozapine is extremely effective, also when other treatment fails. For the treatment of bipolar depression, lithium, lamotrigine, and antidepressants all seem to work, but antidepressants may sometimes precipitate mania or worsen the course of illness. For prophylaxis, lithium is still to be considered the first drug of choice. However, for several reasons, for instance treatment failure or side effects, long-term treatment with antiepileptics may often be necessary. Among the antiepileptics, carbamazepine, valproate, and lamotrigine are the best studied. PMID:12025705

  20. [Poststroke-bipolar affective disorder].

    PubMed

    Bengesser, S A; Wurm, W E; Lackner, N; Birner, A; Reininghaus, B; Kapfhammer, H-P; Reininghaus, E

    2013-08-01

    A few weeks after suffering from a basal ganglia infarction (globus pallidus) with left-sided hemiplegia, a 23-year-old woman exhibited for the first time a pronounced mania with self-endangerment. The use of oral contraceptives was the only determinable risk factor. During the further course, the mother also developed a depressive disorder. Thus a certain genetic predisposition for affective disorders may be relevant, although this would not explain the outbreak by itself. An association between the right-sided basal ganglia infarction and the occurrence of a bipolar affective disorder has been described in the literature. Vascular or, respectively, inflammatory risk factors in synopsis with the aetiopathogenesis of bipolar affective disorders are also discussed in depth in this case report. PMID:23939559

  1. Unsplit bipolar pulse forming line

    DOEpatents

    Rhodes, Mark A.

    2011-05-24

    A bipolar pulse forming transmission line module and system for linear induction accelerators having first, second, third, and fourth planar conductors which form a sequentially arranged interleaved stack having opposing first and second ends, with dielectric layers between the conductors. The first and second planar conductors are connected to each other at the first end, and the first and fourth planar conductors are connected to each other at the second end via a shorting plate. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short at the first end a high voltage from the third planar conductor to the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  2. Gate-Controlled P-I-N Junction Switching Device with Graphene Nanoribbon

    NASA Astrophysics Data System (ADS)

    Nakaharai, Shu; Iijima, Tomohiko; Ogawa, Shinichi; Miyazaki, Hisao; Li, Songlin; Tsukagoshi, Kazuhito; Sato, Shintaro; Yokoyama, Naoki

    2012-01-01

    A graphene P-I-N junction switching device with a nanoribbon is proposed, which was aimed at finding an optimized operation scheme for graphene transistors. The device has two bulk graphene regions where the carrier type is electrostatically controlled by a top gate, and these two regions are separated by a nanoribbon that works as an insulator, resulting in a junction configuration of (P or N)-I-(P or N). It is demonstrated that the drain current modulation strongly depends on the junction configuration, while the nanoribbon is not directly top-gated, and that the device with a P-I-N or N-I-P junction can exhibit better switching properties.

  3. Programmable, automated transistor test system

    NASA Technical Reports Server (NTRS)

    Truong, L. V.; Sundburg, G. R.

    1986-01-01

    A programmable, automated transistor test system was built to supply experimental data on new and advanced power semiconductors. The data will be used for analytical models and by engineers in designing space and aircraft electric power systems. A pulsed power technique was used at low duty cycles in a nondestructive test to examine the dynamic switching characteristic curves of power transistors in the 500 to 1000 V, 10 to 100 A range. Data collection, manipulation, storage, and output are operator interactive but are guided and controlled by the system software.

  4. Major Ups and Downs: Bipolar Disorder Brings Extreme Mood Swings

    MedlinePlus

    ... our exit disclaimer . Subscribe Major Ups and Downs Bipolar Disorder Brings Extreme Mood Swings Most people feel happy ... Strike Out Stroke Wise Choices Links Dealing with Bipolar Disorder If you have bipolar disorder, get treatment and ...

  5. Silicon on insulator self-aligned transistors

    DOEpatents

    McCarthy, Anthony M.

    2003-11-18

    A method for fabricating thin-film single-crystal silicon-on-insulator (SOI) self-aligned transistors. Standard processing of silicon substrates is used to fabricate the transistors. Physical spaces, between the source and gate, and the drain and gate, introduced by etching the polysilicon gate material, are used to provide connecting implants (bridges) which allow the transistor to perform normally. After completion of the silicon substrate processing, the silicon wafer is bonded to an insulator (glass) substrate, and the silicon substrate is removed leaving the transistors on the insulator (glass) substrate. Transistors fabricated by this method may be utilized, for example, in flat panel displays, etc.

  6. Course of Subthreshold Bipolar Disorder in Youth: Diagnostic Progression from Bipolar Disorder Not Otherwise Specified

    ERIC Educational Resources Information Center

    Axelson, David A.; Birmaher, Boris; Strober, Michael A.; Goldstein, Benjamin I.; Ha, Wonho; Gill, Mary Kay; Goldstein, Tina R.; Yen, Shirley; Hower, Heather; Hunt, Jeffrey I.; Liao, Fangzi; Iyengar, Satish; Dickstein, Daniel; Kim, Eunice; Ryan, Neal D.; Frankel, Erica; Keller, Martin B.

    2011-01-01

    Objective: To determine the rate of diagnostic conversion from an operationalized diagnosis of bipolar disorder not otherwise specified (BP-NOS) to bipolar I disorder (BP-I) or bipolar II disorder (BP-II) in youth over prospective follow-up and to identify factors associated with conversion. Method: Subjects were 140 children and adolescents…

  7. Recent progress in understanding pediatric bipolar disorder.

    PubMed

    Goldstein, Benjamin I

    2012-04-01

    Bipolar disorder is one of the most severe psychiatric illnesses, particularly when onset occurs during childhood or adolescence. With recent empirical evidence, questions regarding the existence of bipolar disorder among children and adolescents have given way to questions regarding prevalence. There are substantial risks inherent in misapplying diagnoses and treatments of bipolar disorder when not warranted and in withholding these diagnoses and treatments when they are warranted. As with adults, the course of bipolar disorder among children and adolescents diagnosed using unmodified diagnostic criteria is characterized by recovery and recurrence, functional impairment, suicidality, and high rates of comorbid psychiatric and medical problems. Discrepancies between increasing billing diagnoses and a stable epidemiologic prevalence of bipolar disorder suggest the possibility that diagnostic criteria are not being systematically applied in some clinical settings. Introducing new diagnoses may exacerbate rather than mitigate concerns regarding misdiagnosis and excessive use of mood-stabilizing medications. Several medications, particularly second-generation antipsychotics, are efficacious for treating acute manic episodes of bipolar I disorder. However, less is known regarding the treatment of other mood states and subtypes of bipolar disorder. Psychosocial treatments provide a forum in which to educate children and families regarding bipolar disorder and its treatment, and may be especially beneficial for reducing depressive symptoms. Offspring of parents with bipolar disorder are at increased risk of developing the illness, as are youth with major depressive disorder and certain psychiatric comorbidities. Preliminary findings regarding biomarkers offer hope that, in the future, these biomarkers may inform diagnostic and treatment decisions. PMID:22213607

  8. Distinctions between bipolar and unipolar depression

    PubMed Central

    Cuellar, Amy K.; Johnson, Sheri L.; Winters, Ray

    2010-01-01

    This is a review of the studies comparing unipolar and bipolar depression, with focus on the course, symptomatology, neurobiology, and psychosocial literatures. These are reviewed with one question in mind: does the evidence support diagnosing bipolar and unipolar depressions as the same disorder or different? The current nomenclature of bipolar and unipolar disorders has resulted in research that compares these disorders as a whole, without considering depression separately from mania within bipolar disorder. Future research should investigate two broad categories of depression and mania as separate disease processes that are highly comorbid. PMID:15792852

  9. Analysing organic transistors based on interface approximation

    SciTech Connect

    Akiyama, Yuto; Mori, Takehiko

    2014-01-15

    Temperature-dependent characteristics of organic transistors are analysed thoroughly using interface approximation. In contrast to amorphous silicon transistors, it is characteristic of organic transistors that the accumulation layer is concentrated on the first monolayer, and it is appropriate to consider interface charge rather than band bending. On the basis of this model, observed characteristics of hexamethylenetetrathiafulvalene (HMTTF) and dibenzotetrathiafulvalene (DBTTF) transistors with various surface treatments are analysed, and the trap distribution is extracted. In turn, starting from a simple exponential distribution, we can reproduce the temperature-dependent transistor characteristics as well as the gate voltage dependence of the activation energy, so we can investigate various aspects of organic transistors self-consistently under the interface approximation. Small deviation from such an ideal transistor operation is discussed assuming the presence of an energetically discrete trap level, which leads to a hump in the transfer characteristics. The contact resistance is estimated by measuring the transfer characteristics up to the linear region.

  10. Four-junction superconducting circuit.

    PubMed

    Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J Q

    2016-01-01

    We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit. PMID:27356619

  11. Four-junction superconducting circuit

    NASA Astrophysics Data System (ADS)

    Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.

    2016-06-01

    We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit.

  12. Four-junction superconducting circuit

    PubMed Central

    Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.

    2016-01-01

    We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit. PMID:27356619

  13. Bipolar resistive switching in room temperature grown disordered vanadium oxide thin-film devices

    NASA Astrophysics Data System (ADS)

    Wong, Franklin J.; Sriram, Tirunelveli S.; Smith, Brian R.; Ramanathan, Shriram

    2013-09-01

    We demonstrate bipolar switching with high OFF/ON resistance ratios (>104) in Pt/vanadium oxide/Cu structures deposited entirely at room temperature. The SET (RESET) process occurs when negative (positive) bias is applied to the top Cu electrode. The vanadium oxide (VOx) films are amorphous and close to the vanadium pentoxide stoichiometry. We also investigated Cu/VOx/W structures, reversing the position of the Cu electrode, and found the same polarity dependence with respect to the top and bottom electrodes, which suggests that the bipolar nature is linked to the VOx layer itself. Bipolar switching can be observed at 100 °C, indicating that it not due to a temperature-induced metal-insulator transition of a vanadium dioxide second phase. We discuss how ionic drift can lead to the bipolar electrical behavior of our junctions, similar to those observed in devices based on several other defective oxides. Such low-temperature processed oxide switches could be of relevance to back-end or package integration processing schemes.

  14. Ionotropic glutamate receptors mediate OFF responses in light-adapted ON bipolar cells

    PubMed Central

    Pang, Ji-Jie; Gao, Fan; Wu, Samuel M.

    2013-01-01

    Previous studies have suggested that photoreceptor synaptic inputs to depolarizing bipolar cells (DBCs or ON bipolar cells) are mediated by mGluR6 receptors and those to hyperpolarizing bipolar cells (HBCs or OFF bipolar cells) are mediated by AMPA/kainate receptors. Here we show that in addition to mGluR6 receptors which mediate the sign-inverting, depolarizing light responses, subpopulations of cone-dominated and rod/cone mixed DBCs use GluR4 AMPA receptors to generate a transient sign-preserving OFF response under light adapted conditions. These AMPA receptors are located at the basal junctions postsynaptic to rods and they are silent under dark-adapted conditions, as tonic glutamate release in darkness desensitizes these receptors. Light adaptation enhances rod-cone coupling and thus allows cone photocurrents with an abrupt OFF depolarization to enter the rods. The abrupt rod depolarization triggers glutamate activation of unoccupied AMPA receptors, resulting in a transient OFF response in DBCs. It has been widely accepted that the DNQX-sensitive, OFF transient responses in retinal amacrine cells and ganglion cells are mediated exclusively by HBCs. Our results suggests that this view needs revision as AMPA receptors in subpopulations of DBCs are likely to significantly contribute to the DNQX-sensitive OFF transient responses in light-adapted third- and higher-order visual neurons. PMID:22842089

  15. Black phosphorus nonvolatile transistor memory.

    PubMed

    Lee, Dain; Choi, Yongsuk; Hwang, Euyheon; Kang, Moon Sung; Lee, Seungwoo; Cho, Jeong Ho

    2016-04-28

    We demonstrated nanofloating gate transistor memory devices (NFGTMs) using mechanically-exfoliated few-layered black phosphorus (BP) channels and gold nanoparticle (AuNPs) charge trapping layers. The resulting BP-NFGTMs exhibited excellent memory performances, including the five-level data storage, large memory window (58.2 V), stable retention (10(4) s), and cyclic endurance (1000 cycles). PMID:27074903

  16. The four-gate transistor

    NASA Technical Reports Server (NTRS)

    Mojarradi, M. M.; Cristoveanu, S.; Allibert, F.; France, G.; Blalock, B.; Durfrene, B.

    2002-01-01

    The four-gate transistor or G4-FET combines MOSFET and JFET principles in a single SOI device. Experimental results reveal that each gate can modulate the drain current. Numerical simulations are presented to clarify the mechanisms of operation. The new device shows enhanced functionality, due to the combinatorial action of the four gates, and opens rather revolutionary applications.

  17. T-Junction Benchmark

    SciTech Connect

    2010-01-01

    Part 1: Two different volume renderings of fluid temperatures in a turbulent T-junction mixing problem at Reynolds number Re=40,000. Part 2: Volume rendering of fluid temperatures in a turbulent T-junction mixing problem at Reynolds number Re=40,000, simulated using Nek5000 at three different resolutions. Part 3: Temperature distribution for a turbulent T-junction mixing problem at Reynolds number Re=40,000, simulated using Nek5000 with 89056 spectral elements of order N=9 (65 million grid points). Credits: Science: Aleks Obabko and Paul Fisher, Argonne National Laboratory
 Visualization: Hank Childs, Lawrence Berkeley National Laboratory

 This research used resources of the Argonne Leadership Computing Facility at Argonne National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under contract DE-AC02-06CH11357

  18. Monte Carlo calculations for metal-semiconductor hot-electron injection via tunnel-junction emission

    NASA Astrophysics Data System (ADS)

    Appelbaum, Ian; Narayanamurti, V.

    2005-01-01

    We present a detailed description of a scheme to calculate the injection current for metal-semiconductor systems using tunnel-junction electron emission. We employ a Monte Carlo framework for integrating over initial free-electron states in a metallic emitter and use interfacial scattering at the metal-semiconductor interface as an independent parameter. These results have implications for modeling metal-base transistors and ballistic electron emission microscopy and spectroscopy.

  19. A Single-Material Logical Junction Based on 2D Crystal PdS2.

    PubMed

    Ghorbani-Asl, Mahdi; Kuc, Agnieszka; Miró, Pere; Heine, Thomas

    2016-02-01

    A single-material logical junction with negligible contact resistance is designed by exploiting quantum-confinement effects in 1T PdS2 . The metallic bilayer serves as electrodes for the semiconducting channel monolayer, avoiding contact resistance. Heat dissipation is then governed by tunnel loss, which becomes negligible at channel lengths larger than 2.45 nm. This value marks the integration limit for a conventional 2D transistor. PMID:26632273

  20. Parity effect of bipolar quantum Hall edge transport around graphene antidots

    NASA Astrophysics Data System (ADS)

    Matsuo, Sadashige; Nakaharai, Shu; Komatsu, Katsuyoshi; Tsukagoshi, Kazuhito; Moriyama, Takahiro; Ono, Teruo; Kobayashi, Kensuke

    2015-06-01

    Parity effect, which means that even-odd property of an integer physical parameter results in an essential difference, ubiquitously appears and enables us to grasp its physical essence as the microscopic mechanism is less significant in coarse graining. Here we report a new parity effect of quantum Hall edge transport in graphene antidot devices with pn junctions (PNJs). We found and experimentally verified that the bipolar quantum Hall edge transport is drastically affected by the parity of the number of PNJs. This parity effect is universal in bipolar quantum Hall edge transport of not only graphene but also massless Dirac electron systems. These results offer a promising way to design electron interferometers in graphene.

  1. Parity effect of bipolar quantum Hall edge transport around graphene antidots.

    PubMed

    Matsuo, Sadashige; Nakaharai, Shu; Komatsu, Katsuyoshi; Tsukagoshi, Kazuhito; Moriyama, Takahiro; Ono, Teruo; Kobayashi, Kensuke

    2015-01-01

    Parity effect, which means that even-odd property of an integer physical parameter results in an essential difference, ubiquitously appears and enables us to grasp its physical essence as the microscopic mechanism is less significant in coarse graining. Here we report a new parity effect of quantum Hall edge transport in graphene antidot devices with pn junctions (PNJs). We found and experimentally verified that the bipolar quantum Hall edge transport is drastically affected by the parity of the number of PNJs. This parity effect is universal in bipolar quantum Hall edge transport of not only graphene but also massless Dirac electron systems. These results offer a promising way to design electron interferometers in graphene. PMID:26122468

  2. Charge transport in nanoscale junctions.

    PubMed

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-01

    many particle excitations, new surface states in semiconductor electrodes, various mechanisms for single molecule rectification of the current, inelastic electron spectra and SERS spectroscopy. Three terminal architectures allowing (electrochemical) gating and transistor effects. Electrochemical nanojunctions and gating: intermolecular electron transfer in multi-redox metalloproteins, contact force modulation, characteristic current-noise patterns due to conformational fluctuations, resonance effects and electrocatalysis. Novel architectures: linear coupled quantum-dot-bridged junctions, electrochemical redox mediated transfer in two center systems leading to double maxima current-voltage plots and negative differential resistance, molecular-nanoparticle hybrid junctions and unexpected mesoscopic effects in polymeric wires. Device integration: techniques for creating stable metal/molecule/metal junctions using 'nano-alligator clips' and integration with 'traditional' silicon-based technology. The Guest Editors would like to thank all of the authors and referees of this special issue for their meticulous work in making each paper a valuable contribution to this research area, the early-bird authors for their patience, and Journal of Physics: Condensed Matter editorial staff in Bristol for their continuous support. PMID:21694407

  3. Swimming in Deep Water: Childhood Bipolar Disorder

    ERIC Educational Resources Information Center

    Senokossoff, Gwyn W.; Stoddard, Kim

    2009-01-01

    The authors focused on one parent's struggles in finding a diagnosis and intervention for a child who had bipolar disorder. The authors explain the process of identification, diagnosis, and intervention of a child who had bipolar disorder. In addition to the personal story, the authors provide information on the disorder and outline strategies…

  4. Bipolar Disorder in School-Age Children

    ERIC Educational Resources Information Center

    Olson, Patricia M.; Pacheco, Mary Rae

    2005-01-01

    This article examines the individual components of bipolar disorder in children and the behaviors that can escalate as a result of misdiagnosis and treatment. The brain/behavior relationship in bipolar disorders can be affected by genetics, developmental failure, or environmental influences, which can cause an onset of dramatic mood swings and…

  5. Bipolar Disorder and Cognitive Therapy: A Commentary

    ERIC Educational Resources Information Center

    Riskind, John H.

    2005-01-01

    This article comments on the three articles (Leahy, 2005; Newman, 2005; and Reilly-Harrington & Knauz, 2005) that deal with the applications of cognitive therapy to treatment of bipolar disorder. They focus on the uses of cognitive therapy in treating three important facets of the special problems of bipolar patients: rapid cycling, severe…

  6. Bipolar disorder diagnosis: challenges and future directions.

    PubMed

    Phillips, Mary L; Kupfer, David J

    2013-05-11

    Bipolar disorder refers to a group of affective disorders, which together are characterised by depressive and manic or hypomanic episodes. These disorders include: bipolar disorder type I (depressive and manic episodes: this disorder can be diagnosed on the basis of one manic episode); bipolar disorder type II (depressive and hypomanic episodes); cyclothymic disorder (hypomanic and depressive symptoms that do not meet criteria for depressive episodes); and bipolar disorder not otherwise specified (depressive and hypomanic-like symptoms that do not meet the diagnostic criteria for any of the aforementioned disorders). Bipolar disorder type II is especially difficult to diagnose accurately because of the difficulty in differentiation of this disorder from recurrent unipolar depression (recurrent depressive episodes) in depressed patients. The identification of objective biomarkers that represent pathophysiologic processes that differ between bipolar disorder and unipolar depression can both inform bipolar disorder diagnosis and provide biological targets for the development of new and personalised treatments. Neuroimaging studies could help the identification of biomarkers that differentiate bipolar disorder from unipolar depression, but the problem in detection of a clear boundary between these disorders suggests that they might be better represented as a continuum of affective disorders. Innovative combinations of neuroimaging and pattern recognition approaches can identify individual patterns of neural structure and function that accurately ascertain where a patient might lie on a behavioural scale. Ultimately, an integrative approach, with several biological measurements using different scales, could yield patterns of biomarkers (biosignatures) to help identify biological targets for personalised and new treatments for all affective disorders. PMID:23663952

  7. Thomson semiconductors bipolar IC strategy to 1986

    NASA Astrophysics Data System (ADS)

    Dellamussia, J. P.

    1984-04-01

    The strategy to develop and market bipolar integrated circuits through 1986 by thomson semiconductors is discussed. Current technology and future research on prototype microprocessors using bipolar integrated circuits is evaluated. The physical properties of the circuits such as heat dissipation, energy consumption rates and response times are studied.

  8. Modeling "Soft" Errors in Bipolar Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J.; Benumof, R.; Vonroos, O.

    1985-01-01

    Mathematical models represent single-event upset in bipolar memory chips. Physics of single-event upset in integrated circuits discussed in theoretical paper. Pair of companion reports present mathematical models to predict critical charges for producing single-event upset in bipolar randomaccess memory (RAM) chips.

  9. Harnessing denatured protein for controllable bipolar doping of a monolayer graphene.

    PubMed

    Jang, Sung Kyu; Jang, Ji-Ryang; Choe, Woo-Seok; Lee, Sungjoo

    2015-01-21

    In this work, we demonstrated tunable p- and/or n-type doping of chemical vapor deposition-grown graphene with the use of protein bovine serum albumin (BSA) as a dopant. BSA undergoes protonation or deprotonation reaction subject to solution pH, thereby acting as either an electron donor or an electron acceptor on the graphene surface layered with denatured BSA through π-stacking interaction. This direct annealing of graphene with denatured BSA of amphoteric nature rendered facilitated fabrication of a p- and/or n-type graphene transistor by modulating pH-dependent net charges of the single dopant. Following AFM confirmation of the BSA/graphene interface assembly, the carrier transport properties of BSA-doped graphene transistors were assessed by I-V measurement and Raman spectra to show effective charge modulation of the graphene enabled by BSA doping at various pH conditions. The protein-mediated bipolar doping of graphene demonstrated in our work is simple, scalable, and straightforward; the proposed scheme is therefore expected to provide a useful alternative for fabricating graphene transistors of novel properties and promote their implementation in practice. PMID:25546483

  10. Adjunctive Psychotherapy for Bipolar Disorder

    PubMed Central

    Miklowitz, David J.

    2008-01-01

    Objective Psychotherapy has long been recommended as adjunctive to pharmacotherapy for bipolar disorder, but it is unclear which interventions are effective for which patients, over what intervals, and for what domains of outcome. This article reviews randomized trials of adjunctive psychotherapy for bipolar disorder. Method Eighteen trials of individual and group psychoeducation, systematic care, family therapy, interpersonal therapy, and cognitive-behavioral therapy are described. Relevant outcome variables include time to recovery, recurrence, duration of episodes, symptom severity, and psychosocial functioning. Results The effects of the treatment modalities varied according to the clinical condition of patients at the time of random assignment and the polarity of symptoms at follow-up. Family therapy, interpersonal therapy, and systematic care appeared to be most effective in preventing recurrences when initiated after an acute episode, whereas cognitive-behavioral therapy and group psychoeducation appeared to be most effective when initiated during a period of recovery. Individual psychoeducational and systematic care programs were more effective for manic than depressive symptoms, whereas family therapy and cognitive-behavioral therapy were more effective for depressive than manic symptoms. Conclusions Adjunctive psychotherapy enhances the symptomatic and functional outcomes of bipolar disorder over 2-year periods. The various modalities differ in content, structure, and associated mediating mechanisms. Treatments that emphasize medication adherence and early recognition of mood symptoms have stronger effects on mania, whereas treatments that emphasize cognitive and interpersonal coping strategies have stronger effects on depression. The placement of psychotherapy within chronic care algorithms and its role as a preventative agent in the early stages of the disorder deserve investigation. PMID:18794208

  11. Understanding electronic structure and transport properties in nanoscale junctions

    NASA Astrophysics Data System (ADS)

    Dhungana, Kamal B.

    Understanding the electronic structure and the transport properties of nanoscale materials are pivotal for designing future nano-scale electronic devices. Nanoscale materials could be individual or groups of molecules, nanotubes, semiconducting quantum dots, and biomolecules. Among these several alternatives, organic molecules are very promising and the field of molecular electronics has progressed significantly over the past few decades. Despite these progresses, it has not yet been possible to achieve atomic level control at the metal-molecule interface during a conductance measurement, which hinders the progress in this field. The lack of atomic level information of the interface also makes it much harder for theorist to interpret the experimental results. To identify the junction configuration that possibly exists during the experimental measurement of conductance in molecular junction, we created an ensemble of Ruthanium-bis(terpyridine) molecular devices, and studied the transport behavior in these molecular junctions. This helps us identifying the junction geometry that yields the experimentally measured current-voltage characteristics. Today's electronic devices mostly ignore the spin effect of an electron. The inclusion of spin effect of an electron on solid-state transistor allows us to build more efficient electronic devices; this also alleviates the problem of huge heat dissipation in the nanoscale electronic devices. Different materials have been utilized to build three terminals spin transistor since its inception in 1950. In search of suitable candidates for the molecular spin transistor, we have recently designed a spin-valve transistor based on an organometallic molecule; a large amplification (320 %) in tunnel magneto-resistance (TMR) is found to occur at an experimentally accessible gate field. This suggests that the organic molecules can be utilized for making the next generation three terminal spintronic devices. Similarly, we have designed a

  12. Victory Junction Gang Camp

    ERIC Educational Resources Information Center

    Shell, Ryan

    2007-01-01

    This article describes the Victory Junction Gang Camp, a not-for-profit, NASCAR-themed camp for children with chronic medical conditions that serves 24 different disease groups. The mission of the camp is to give children life-changing camping experiences that are exciting, fun, and empowering in a safe and medically sound environment. While doing…

  13. Josephson junction mixing.

    NASA Technical Reports Server (NTRS)

    Thompson, E. D.

    1973-01-01

    A theory is presented which, though too simple to explain quantitative details in the Josephson junction mixing response, is sufficient for explaining qualitatively the results observed. Crucial to the theory presented, and that which differentiates it from earlier ones, is the inclusion of harmonic voltages across the ideal Josephson element.

  14. Squeezable electron tunneling junctions

    NASA Astrophysics Data System (ADS)

    Moreland, J.; Alexander, S.; Cox, M.; Sonnenfeld, R.; Hansma, P. K.

    1983-09-01

    We report a versatile new technique for constructing electron tunneling junctions with mechanically-adjusted artificial barriers. I-V curves are presented for tunneling between Ag electrodes with vacuum, gas, liquid or solid in the barrier. An energy gap is apparent in the measured I-V curve when tunneling occurs between superconducting Pb electrodes.

  15. Doped semiconductor nanocrystal junctions

    SciTech Connect

    Borowik, Ł.; Mélin, T.; Nguyen-Tran, T.; Roca i Cabarrocas, P.

    2013-11-28

    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  16. Bipolar Ag-Zn battery

    NASA Astrophysics Data System (ADS)

    Giltner, L. John

    1994-02-01

    The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected

  17. [Child and adolescent bipolar disorder].

    PubMed

    Aichhorn, Wolfgang; Stuppäck, Christoph; Kralovec, Karl; Yazdi, Kurosch; Aichhorn, Monika; Hausmann, Armand

    2007-01-01

    The onset of bipolar disorders before the age of 10 is rare. First manifestation occurs most frequently between the age of 15 to 30. Children of a parent with bipolar disorder are at a fivefold risk for developing a bipolar disorder. Therefore, an elaborate family-history is essential for the assessment of potentially manic or depressive symptoms in children and adolescents. Basically, for all age groups the same diagnostic criteria according to ICD 10 are applied. Due to the differing symptoms for children and adolescents the finding of a diagnosis is considerably harder than for adults. Manic episodes before the age of 10 are characterized by increased activity, more risk taking behaviour and elevated emotional instability. In adolescents, however, behavioural disturbance with antisocial behaviour and drug-abuse are more common. Thus, typical misdiagnosis as ADHD or conduct disorders for children and adolescents are frequent. Aggravating the complexity, in up to 90 % both differential-diagnosis may occur as comorbid disorders. Furthermore, psychotic symptoms are more common than in adults and dysphoria is more likely than euphoric or depressive mood. Asymptomatic intervals rarely exist, whereas "ups" and "downs" in rapid succession are prevailing (rapid cycling). An early diagnosis, leading specific treatment, is essential for the prognosis of bipolar disorders. Additionally, structural (CCT or MRI) and laboratory examination are essential to expel endocrine or brain-organic diseases. Besides psychotherapeutic and psychoeducative methods, always including parents and attached persons, the psychopharmacological treatment is a major part of a multimodal treatment. The available substances partly have been in use for years and are appropriate for youngsters. These include mood stabilizers like lithium, divalproex and carbamazepine, which provide besides their acute antimanic effects also relapse-prophylactic properties. In addition atypical antipsychotics like

  18. Bipolar Ag-Zn battery

    NASA Technical Reports Server (NTRS)

    Giltner, L. John

    1994-01-01

    The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected

  19. Brain barriers: Crosstalk between complex tight junctions and adherens junctions

    PubMed Central

    Tietz, Silvia

    2015-01-01

    Unique intercellular junctional complexes between the central nervous system (CNS) microvascular endothelial cells and the choroid plexus epithelial cells form the endothelial blood–brain barrier (BBB) and the epithelial blood–cerebrospinal fluid barrier (BCSFB), respectively. These barriers inhibit paracellular diffusion, thereby protecting the CNS from fluctuations in the blood. Studies of brain barrier integrity during development, normal physiology, and disease have focused on BBB and BCSFB tight junctions but not the corresponding endothelial and epithelial adherens junctions. The crosstalk between adherens junctions and tight junctions in maintaining barrier integrity is an understudied area that may represent a promising target for influencing brain barrier function. PMID:26008742

  20. Highly flexible electronics from scalable vertical thin film transistors.

    PubMed

    Liu, Yuan; Zhou, Hailong; Cheng, Rui; Yu, Woojong; Huang, Yu; Duan, Xiangfeng

    2014-03-12

    Flexible thin-film transistors (TFTs) are of central importance for diverse electronic and particularly macroelectronic applications. The current TFTs using organic or inorganic thin film semiconductors are usually limited by either poor electrical performance or insufficient mechanical flexibility. Here, we report a new design of highly flexible vertical TFTs (VTFTs) with superior electrical performance and mechanical robustness. By using the graphene as a work-function tunable contact for amorphous indium gallium zinc oxide (IGZO) thin film, the vertical current flow across the graphene-IGZO junction can be effectively modulated by an external gate potential to enable VTFTs with a highest on-off ratio exceeding 10(5). The unique vertical transistor architecture can readily enable ultrashort channel devices with very high delivering current and exceptional mechanical flexibility. With large area graphene and IGZO thin film available, our strategy is intrinsically scalable for large scale integration of VTFT arrays and logic circuits, opening up a new pathway to highly flexible macroelectronics. PMID:24502192

  1. Effect of disorder on longitudinal resistance of a graphene p-n junction in the quantum Hall regime

    NASA Astrophysics Data System (ADS)

    Chen, Jiang-Chai; Yeung, T. C. Au; Sun, Qing-Feng

    2010-06-01

    The longitudinal resistances of a six-terminal graphene p-n junction under a perpendicular magnetic field are investigated. Because of the chirality of the Hall edge states, the longitudinal resistances on top and bottom edges of the graphene ribbon are not equal. In the presence of suitable disorder, the top-edge and bottom-edge resistances well show the plateau structures in the both unipolar and bipolar regimes, and the plateau values are determined by the Landau filling factors only. These plateau structures are in excellent agreement with the recent experiment. For the unipolar junction, the resistance plateaus emerge in the absence of impurity and they are destroyed by strong disorder. But for the bipolar junction, the resistances are very large without the plateau structures in the clean junction. The disorder can strongly reduce the resistances and leads the formation of the resistance plateaus due to the mixture of the Hall edge states in virtue of the disorder. In addition, the size effect of the junction on the resistances is studied and some extra resistance plateaus are found in the long graphene junction case. This is explained by the fact that only part of the edge states participate in the full mixing.

  2. Analysis of dynamic characteristics and ways of development of bipolar main memory with miniaturization of integrated circuit elements

    NASA Astrophysics Data System (ADS)

    Sergeyev, A. G.; Savenkov, V. N.; Parmenov, Y. A.; Neklyudov, V. A.; Mindeyeva, A. A.

    1984-08-01

    A forecast estimate of the characteristics of a super large scale integrated circuit (super-BIS) memory as applied to bipolar main memory (OZU) circuits is presented. The limiting speed of bipolar OSU with d 2 micrometer will be determined by the characteristics of the interconnections and not by the parameters of bipolar devices. With d 2 micrometer, slowing down of the rate of growth of the response speed of OZU must be expected as the result of miniaturization as a consequence of the increase of the specific capacities of the p-n junctions and the metallization and constraint on the current density in the interconnections. The limitation and the specific properties of the energetics of bipolar OZU--localization of the current in separate lines, leads to a variance between speed of response and the decree of integration. For realization of the potentially high speed of response of bipolar OSU an improvement is necessary of the technology of the interconnections with the object of an increase of the current density to master a three layered system of interconnections.

  3. The prestige model of spectrum bipolarity.

    PubMed

    Le Bas, James; Newton, Richard; Sore, Rachel; Castle, David

    2015-02-01

    Because affective pathogenesis is a hard problem for psychiatry, it behoves researchers to develop and test novel models of causality. We examine the notion that the adaptive drive to social investment - prestige - provides clues to the bipolar spectrum. A seven node bipolar spectrum is proposed, based on a putative gradient of "bipolarity". It is conceived that this gradient may correlate with the drive to social investment (prestige). In order to test this hypothesis with proof of concept data, a case control study categorised 228 subjects into a seven node bipolar spectrum. Whilst controlling for mood elevation and depression, differences in strategic prestige (leadership) motivation (MSPM) between spectrum groups were examined. The bipolar I (S1) node had a greater strategic prestige (leadership) motivation score than the controls (S7) by 21.17 points, 95% CI [8.16, 34.18], p<.001, d=1.05, while the bipolar II (S2) node was higher than the control group by 16.73 points, 95% CI [0.92, 32.54], p=.030, d=0.84. Whilst the pseudounipolar (S3) node (those with depression and bipolar family histories; n=17) had only a marginally statistical difference in MSPM compared to controls (p=.051), the mean difference (16.98) and d value (0.86) indicated an elevated MSPM level. Prestige (leadership) motivation score positively correlated with dimensional lifetime bipolarity (Mood Disorder Questionnaire) score (rp=0.47), supporting the spectrum prestige motivation gradient notion. Evidence is presented for a genetic disposition to elevated strategic prestige (leadership) motivation. Sensitivity to Social Inclusion (MSIS), Contingency of Self-Worth (CSW.av) and tension significantly predicted strategic prestige (leadership) motivation (MSPM) score in a multiple regression. - suggesting that a vulnerability of the social self may be a feature of bipolar disorders. The prestige model of spectrum bipolarity offers a new conceptualisation of affective disorders and has received

  4. Long-Term Characterization of 6H-SiC Transistor Integrated Circuit Technology Operating at 500 C

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Spry, David J.; Chen, Liang-Yu; Chang, Carl W.; Beheim, Glenn M.; Okojie, Robert S.; Evans, Laura J.; Meredith Roger D.; Ferrier, Terry L.; Krasowski, Michael J.; Prokop, Norman F.

    2008-01-01

    NASA has been developing very high temperature semiconductor integrated circuits for use in the hot sections of aircraft engines and for Venus exploration. This paper reports on long-term 500 C electrical operation of prototype 6H-SiC integrated circuits based on epitaxial 6H-SiC junction field effect transistors (JFETs). As of this writing, some devices have surpassed 4000 hours of continuous 500 C electrical operation in oxidizing air atmosphere with minimal change in relevant electrical parameters.

  5. Bipolar resistive switching in Cr-doped TiOx thin films

    NASA Astrophysics Data System (ADS)

    Xing, Zhong-Wen; X., Chen; J. Wu, N.; Ignatiev, A.

    2011-09-01

    The electric-pulse-induced resistive switching effect is studied for Ti0.85Cr0.15Ox (TCO) films grown on Ir—Si substrates by pulsed laser deposition. Such a TCO device exhibits bipolar switching behaviour with an electric-pulse-induced resistance ratio as large as about 1000% and threshold voltages smaller than 2 V. The resistive switching characteristics may be understood by resistance changes of a Schottky junction composed of a metal and an n-type semiconductor, and its nonvolatility is attributed to the movement of oxygen vacancies near the interface.

  6. Viruses, schizophrenia, and bipolar disorder.

    PubMed Central

    Yolken, R H; Torrey, E F

    1995-01-01

    The hypothesis that viruses or other infectious agents may cause schizophrenia or bipolar disorder dates to the 19th century but has recently been revived. It could explain many clinical, genetic, and epidemiologic aspects of these diseases, including the winter-spring birth seasonality, regional differences, urban birth, household crowding, having an older sibling, and prenatal exposure to influenza as risk factors. It could also explain observed immunological changes such as abnormalities of lymphocytes, proteins, autoantibodies, and cytokines. However, direct studies of viral infections in individuals with these psychiatric diseases have been predominantly negative. Most studies have examined antibodies in blood or cerebrospinal fluid, and relatively few studies have been done on viral antigens, genomes, cytopathic effect on cell culture, and animal transmission experiments. Viral research on schizophrenia and bipolar disorder is thus comparable to viral research on multiple sclerosis and Parkinson's disease: an attractive hypothesis with scattered interesting findings but no clear proof. The application of molecular biological techniques may allow the identification of novel infectious agents and the associations of these novel agents with serious mental diseases. PMID:7704891

  7. Black phosphorus nonvolatile transistor memory

    NASA Astrophysics Data System (ADS)

    Lee, Dain; Choi, Yongsuk; Hwang, Euyheon; Kang, Moon Sung; Lee, Seungwoo; Cho, Jeong Ho

    2016-04-01

    We demonstrated nanofloating gate transistor memory devices (NFGTMs) using mechanically-exfoliated few-layered black phosphorus (BP) channels and gold nanoparticle (AuNPs) charge trapping layers. The resulting BP-NFGTMs exhibited excellent memory performances, including the five-level data storage, large memory window (58.2 V), stable retention (104 s), and cyclic endurance (1000 cycles).We demonstrated nanofloating gate transistor memory devices (NFGTMs) using mechanically-exfoliated few-layered black phosphorus (BP) channels and gold nanoparticle (AuNPs) charge trapping layers. The resulting BP-NFGTMs exhibited excellent memory performances, including the five-level data storage, large memory window (58.2 V), stable retention (104 s), and cyclic endurance (1000 cycles). Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02078j

  8. Coaxial inverted geometry transistor having buried emitter

    NASA Technical Reports Server (NTRS)

    Hruby, R. J.; Cress, S. B.; Dunn, W. R. (Inventor)

    1973-01-01

    The invention relates to an inverted geometry transistor wherein the emitter is buried within the substrate. The transistor can be fabricated as a part of a monolithic integrated circuit and is particularly suited for use in applications where it is desired to employ low actuating voltages. The transistor may employ the same doping levels in the collector and emitter, so these connections can be reversed.

  9. Single-transistor-clocked flip-flop

    DOEpatents

    Zhao, Peiyi; Darwish, Tarek; Bayoumi, Magdy

    2005-08-30

    The invention provides a low power, high performance flip-flop. The flip-flop uses only one clocked transistor. The single clocked transistor is shared by the first and second branches of the device. A pulse generator produces a clock pulse to trigger the flip-flop. In one preferred embodiment the device can be made as a static explicit pulsed flip-flop which employs only two clocked transistors.

  10. A graphene-based hot electron transistor.

    PubMed

    Vaziri, Sam; Lupina, Grzegorz; Henkel, Christoph; Smith, Anderson D; Ostling, Mikael; Dabrowski, Jarek; Lippert, Gunther; Mehr, Wolfgang; Lemme, Max C

    2013-04-10

    We experimentally demonstrate DC functionality of graphene-based hot electron transistors, which we call graphene base transistors (GBT). The fabrication scheme is potentially compatible with silicon technology and can be carried out at the wafer scale with standard silicon technology. The state of the GBTs can be switched by a potential applied to the transistor base, which is made of graphene. Transfer characteristics of the GBTs show ON/OFF current ratios exceeding 10(4). PMID:23488893

  11. Nanoscale Magnetic Materials for Energy-Efficient Spin Based Transistors

    NASA Astrophysics Data System (ADS)

    Incorvia, Jean Anne Currivan

    In this dissertation, I study the physical behavior of nanoscale magnetic materials and build spin-based transistors that encode information in magnetic domain walls. It can be argued that energy dissipation is the most serious problem in modern electronics, and one that has been resistant to a breakthrough. Wasted heat during computing both wastes energy and hinders further technology scaling. This is an opportunity for physicists and engineers to come up with creative solutions for more energy-efficient computing. I present the device we have designed, called domain wall logic (DW-Logic). Information is stored in the position of a magnetic domain wall in a ferromagnetic wire and read out using a magnetic tunnel junction. This hybrid design uses electrical current as the input and output, keeping the device compatible with charge- based transistors. I build an iterative model to predict both the micromagnetic and circuit behavior of DW- Logic, showing a single device can operate as a universal gate. The model shows we can build complex circuits including an 18-gate Full Adder, and allows us to predict the device switching energy compared to complementary metal-oxide semiconductor (CMOS) transistors. Comparing ?15 nm feature nodes, I find DW-Logic made with perpendicular magnetic anisotropy materials, and utilizing both spin torque transfer and the Spin Hall effect, could operate with 1000x reduced switching energy compared to CMOS. I fabricate DW-Logic device prototypes and show in experiment they can act as AND and NAND gates. I demonstrate that one device can drive two subsequent devices, showing gain, which is a necessary requirement for fanout. I also build a clocked ring oscillator circuit to demonstrate successful bit propagation in a DW-Logic circuit and show that properly scaled devices can have improved operation. Through building the devices, I develop a novel fabrication method for patterning sub-25 nm magnetic wires with very low (˜ 2 nm) average edge

  12. Transport Properties of III-N Hot Electron Transistors

    NASA Astrophysics Data System (ADS)

    Suntrup, Donald J., III

    Unipolar hot electron transistors (HETs) represent a tantalizing alternative to established bipolar transistor technologies. During device operation electrons are injected over a large emitter barrier into the base where they travel along the device axis with very high velocity. Upon arrival at the collector barrier, high-energy electrons pass over the barrier and contribute to collector current while low-energy electrons are quantum mechanically reflected back into the base. Designing the base with thickness equal to or less than the hot electron mean free path serves to minimize scattering events and thus enable quasi-ballistic operation. Large current gain is achieved by increasing the ratio of transmitted to reflected electrons. Although III-N HETs have undergone substantial development in recent years, there remain ample opportunities to improve key device metrics. In order to engineer improved device performance, a deeper understanding of the operative transport physics is needed. Fortunately, the HET provides fertile ground for studying several prominent electron transport phenomena. In this thesis we present results from several studies that use the III-N HET as both emitter and analyzer of hot electron momentum states. The first provides a measurement of the hot electron mean free path and the momentum relaxation rate in GaN; the second relies on a new technique called electron injection spectroscopy to investigate the effects of barrier height inhomogeneity in the emitter. To supplement our analysis we develop a comprehensive theory of coherent electron transport that allows us to model the transfer characteristics of complex heterojunctions. Such a model provides a theoretical touchstone with which to compare our experimental results. While these studies are of potential interest in their own right, we interpret the results with an eye toward improving next-generation device performance.

  13. Tuning electron transport through a single molecular junction by bridge modification

    SciTech Connect

    Li, Xiao-Fei Qiu, Qi; Luo, Yi

    2014-07-07

    The possibility of controlling electron transport in a single molecular junction represents the ultimate goal of molecular electronics. Here, we report that the modification of bridging group makes it possible to improve the performance and obtain new functions in a single cross-conjugated molecular junction, designed from a recently synthesized bipolar molecule bithiophene naphthalene diimide. Our first principles results show that the bipolar characteristic remains after the molecule was modified and sandwiched between two metal electrodes. Rectifying is the intrinsic characteristic of the molecular junction and its performance can be enhanced by replacing the saturated bridging group with an unsaturated group. A further improvement of the rectifying and a robust negative differential resistance (NDR) behavior can be achieved by the modification of unsaturated bridge. It is revealed that the modification can induce a deviation angle about 4° between the donor and the acceptor π-conjugations, making it possible to enhance the communication between the two π systems. Meanwhile, the low energy frontier orbitals of the junction can move close to the Fermi level and encounter in energy at certain biases, thus a transport channel with a considerable transmission can be formed near the Fermi level only at a narrow bias regime, resulting in the improvement of rectifying and the robust NDR behavior. This finding could be useful for the design of single molecular devices.

  14. Bipolar plates for PEM fuel cells

    NASA Astrophysics Data System (ADS)

    Middelman, E.; Kout, W.; Vogelaar, B.; Lenssen, J.; de Waal, E.

    The bipolar plates are in weight and volume the major part of the PEM fuel cell stack, and are also a significant contributor to the stack costs. The bipolar plate is therefore a key component if power density has to increase and costs must come down. Three cell plate technologies are expected to reach targeted cost price levels, all having specific advantages and drawbacks. NedStack has developed a conductive composite materials and a production process for fuel cell plates (bipolar and mono-polar). The material has a high electric and thermal conductivity, and can be processed into bipolar plates by a proprietary molding process. Process cycle time has been reduced to less than 10 s, making the material and process suitable for economical mass production. Other development work to increase material efficiency resulted in thin bipolar plates with integrated cooling channels, and integrated seals, and in two-component bipolar plates. Total thickness of the bipolar plates is now less than 3 mm, and will be reduced to 2 mm in the near future. With these thin integrated plates it is possible to increase power density up to 2 kW/l and 2 kW/kg, while at the same time reducing cost by integrating other functions and less material use.

  15. Brief Report: A Family Risk Study Exploring Bipolar Spectrum Problems and Cognitive Biases in Adolescent Children of Bipolar Parents

    ERIC Educational Resources Information Center

    Espie, Jonathan; Jones, Steven H.; Vance, Yvonne H.; Tai, Sara J.

    2012-01-01

    Children of parents with bipolar disorder are at increased risk of bipolar spectrum diagnoses. This cross-sectional study explores cognitive factors in the prediction of vulnerability to bipolar disorder. Adolescents at high-risk (with a parent with bipolar disorder; n = 23) and age and gender matched adolescents (n = 24) were recruited. Parent…

  16. Minimizing electrode edge in organic transistors with ultrathin reduced graphene oxide for improving charge injection efficiency.

    PubMed

    Xu, Zeyang; Chen, Xiaosong; Zhang, Suna; Wu, Kunjie; Li, Hongwei; Meng, Yancheng; Li, Liqiang

    2016-05-11

    Electrode materials and geometry play a crucial role in the charge injection efficiency in organic transistors. Reduced graphene oxide (RGO) electrodes show good compatibility with an organic semiconductor from the standpoint of energy levels and ordered growth of the organic semiconductor, both of which are favourable for charge injection. However, the wide electrode edge (>10 nm) in commonly-used RGO electrodes is generally detrimental to charge injection. In this study, ultrathin (about 3 nm) RGO electrodes are fabricated via a covalency-based assembly strategy, which has advantages such as robustness against solvents, high conductivity, transparency, and easy scaling-up. More remarkably, the ultrathin electrode fabricated in this study has a narrow edge, which may facilitate the diffusion and assembly of organic semiconductors and thus form a uniform semiconductor film across the electrode/channel junction area. As a result, the minimized electrode edge may significantly improve the charge injection in organic transistors compared with thick electrodes. PMID:27062997

  17. A miniature microcontroller curve tracing circuit for space flight testing transistors

    NASA Astrophysics Data System (ADS)

    Prokop, N.; Greer, L.; Krasowski, M.; Flatico, J.; Spina, D.

    2015-02-01

    This paper describes a novel miniature microcontroller based curve tracing circuit, which was designed to monitor the environmental effects on Silicon Carbide Junction Field Effect Transistor (SiC JFET) device performance, while exposed to the low earth orbit environment onboard the International Space Station (ISS) as a resident experiment on the 7th Materials on the International Space Station Experiment (MISSE7). Specifically, the microcontroller circuit was designed to operate autonomously and was flown on the external structure of the ISS for over a year. This curve tracing circuit is capable of measuring current vs. voltage (I-V) characteristics of transistors and diodes. The circuit is current limited for low current devices and is specifically designed to test high temperature, high drain-to-source resistance SiC JFETs. The results of each I-V data set are transmitted serially to an external telemetered communication interface. This paper discusses the circuit architecture, its design, and presents example results.

  18. Recognising Bipolar Disorders in Primary Care.

    PubMed

    Dietch, Daniel

    2015-09-01

    Bipolar disorder, previously called 'Manic-depression', is a complex group of conditions characterised by recurrent changes in mood and energy. Crucially, the intensity and duration of these changes go beyond normal fluctuations and personality traits. Bipolar Disorder is a mental health disorder, but physical health manifestations (Smith 2013, Westman 2013, Fagiolini 2008, Young 2013) and complications are just as important. GPs have a key role in the recognition and management, in conjunction with secondary care colleagues. Diagnosis is often difficult and may take several years (Smith 2011, Angst 2005, Manning 2010), because patients usually seek help for anxiety, depression or fatigue, not hypomania/mania, which they may not recognise. Individuals with a first episode of mania are more likely to present directly to secondary care, sometimes via a third party alerting the emergency services. There is also debate around the classification, diagnosis and treatment of individuals with brief and milder mood changes ('bipolar spectrum disorder') (Faravelli 2009, Spence 2011). In the UK, the recent NICE Guidelines (2014) 1 only included Bipolar I and Bipolar II for these reasons. A particular challenge for GPs is that whilst most people who have Bipolar Disorder (and especially Bipolar II) are depressed, most people with depression within a Primary Care setting do not have Bipolar Disorder. Thus, a brief pragmatic screen is recommended in Primary care: ask about a family history of Bipolar Disorder and screen for a history of mania/hypomania in individuals with anxiety, depression or irritability, especially if there are recurrent episodes, suicidal thoughts or a previous suicide attempt. For suspected cases, formal diagnosis should not be made within Primary Care but individuals should be referred for Psychiatric assessment, ideally to a Mood Disorders specialist. PMID:26417759

  19. High-Power, High-Frequency Si-Based (SiGe) Transistors Developed

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.

    2002-01-01

    Future NASA, DOD, and commercial products will require electronic circuits that have greater functionality and versatility but occupy less space and cost less money to build and integrate than current products. System on a Chip (SOAC), a single semiconductor substrate containing circuits that perform many functions or containing an entire system, is widely recognized as the best technology for achieving low-cost, small-sized systems. Thus, a circuit technology is required that can gather, process, store, and transmit data or communications. Since silicon-integrated circuits are already used for data processing and storage and the infrastructure that supports silicon circuit fabrication is very large, it is sensible to develop communication circuits on silicon so that all the system functions can be integrated onto a single wafer. Until recently, silicon integrated circuits did not function well at the frequencies required for wireless or microwave communications, but with the introduction of small amounts of germanium into the silicon to make silicon-germanium (SiGe) transistors, silicon-based communication circuits are possible. Although microwavefrequency SiGe circuits have been demonstrated, there has been difficulty in obtaining the high power from their transistors that is required for the amplifiers of a transmitter, and many researchers have thought that this could not be done. The NASA Glenn Research Center and collaborators at the University of Michigan have developed SiGe transistors and amplifiers with state-of-the-art output power at microwave frequencies from 8 to 20 GHz. These transistors are fabricated using standard silicon processing and may be integrated with CMOS integrated circuits on a single chip. A scanning electron microscope image of a typical SiGe heterojunction bipolar transistor is shown in the preceding photomicrograph. This transistor achieved a record output power of 550 mW and an associated power-added efficiency of 33 percent at 8

  20. Wireless Josephson Junction Arrays

    NASA Astrophysics Data System (ADS)

    Adams, Laura

    2015-03-01

    We report low temperature, microwave transmission measurements on a wireless two- dimensional network of Josephson junction arrays composed of superconductor-insulator -superconductor tunnel junctions. Unlike their biased counterparts, by removing all electrical contacts to the arrays and superfluous microwave components and interconnects in the transmission line, we observe new collective behavior in the transmission spectra. In particular we will show emergent behavior that systematically responds to changes in microwave power at fixed temperature. Likewise we will show the dynamic and collective response of the arrays while tuning the temperature at fixed microwave power. We discuss these spectra in terms of the Berezinskii-Kosterlitz-Thouless phase transition and Shapiro steps. We gratefully acknowledge the support Prof. Steven Anlage at the University of Maryland and Prof. Allen Goldman at the University of Minnesota. Physics and School of Engineering and Applied Sciences.