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Sample records for gaas bipolar transistor

  1. 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.

  2. A GaAs heterojunction bipolar transistor with 106 V breakdown

    SciTech Connect

    Baca, A.G.; Klem, J.F.; Ashby, C.I.; Martin, D.C.

    2000-01-11

    A high voltage GaAs HBT with an open-base collector breakdown voltage of 106 V and an open-emitter breakdown voltage of 134 V has been demonstrated. A high quality 9.0 {micro}m thick collector doped to 2.0{times}10{sup 15} cm{sup {minus}3} grown by MBE on a doped GaAs substrate is the key to achieving this breakdown. These results were achieved for HBTs with 4{times}40 {micro}m{sup 2} emitters. DC current gain of 38 at 6,000 A/cm{sup 2} was measured.

  3. 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.

  4. 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.

  5. Vertical bipolar charge plasma transistor with buried metal layer.

    PubMed

    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 · f(T) 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

  6. 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

  7. Self-oscillating inverter with bipolar transistors

    NASA Astrophysics Data System (ADS)

    Baciu, I.; Cunţan, C. D.; Floruţa, M.

    2016-02-01

    The paper presents a self-oscillating inverter manufactured with bipolar transistors that supplies a high-amplitude alternating voltage to a fluorescent tube with a burned filament. The inverter is supplied from a low voltage accumulator that can be charged from a photovoltaic panel through a voltage regulator.

  8. Losses in high power bipolar transistors

    NASA Astrophysics Data System (ADS)

    Rockot, J. H.

    The calculation of power losses in high power bipolar transistors is examined for several of the commonly encountered types of power circuits. The magnitude of switching and conduction losses are dependent on the type of circuit in which they are used, the type of load, switching frequency, and characteristics of the transistor itself. Curves, based on computer simulation and mathematical analysis, are presented to aid in the calculation of these losses. Parameters taken into account are dynamic saturation voltage, load power factor, effect of snubbers and recovery characteristics of circuit associated diodes.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Generation and recombination in two-dimensional bipolar transistors

    NASA Astrophysics Data System (ADS)

    Gharekhanlou, Behnaz; Khorasani, Sina

    2014-06-01

    We study the effects of recombination and generation process on the operation of bipolar junction transistor based on two-dimensional materials, and in particular, graphone. Here, we use Shockley-Read-Hall model to study these process. First, we investigate the current-voltage characteristics of a graphone p- n junction considering generation and recombination process. Then, we calculate the estimated changes in current gain, cutoff frequency, and output characteristics of a graphone bipolar junction transistor designed in a recent study.

  15. Indium arsenide-based bipolar transistors grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Wu, Xiaohua

    Large carrier mobilities and large electron saturation velocity make InAs a promising material for high speed devices. Additionally, the low band gap is useful for low power applications. By applying bipolar transistors, high frequency, high-speed devices and applications can be easily realized. Thus InAs-based bipolar transistors are studied extensively in this work. InAs-based bipolar junction transistors (BJTs) with current gains (beta) up to 400 have been achieved. The physics of beta in InAs BJTs is studied by estimating the emitter injection efficiency (gamma), the base transport factor (alphaT), and the minority carrier (electrons) diffusion length in the base (LB). AlInAs/InAs and InAsP/InAs HBTs are realized. InAs based HBTs have higher current gain than BJTs with similar structures and same doping profiles. Advantages of HBTs over BJTs are shown by a comparison of the electrical characteristics of AlInAs/InAs HBTs and InAs BJTs. The development of a high frequency transistor is dependent on the insulating quality of the substrate, in order to reduce large leakage into the collector. However, presently no semi-insulating substrates that are lattice matched to InAs exist. This necessitates metamorphic growth of InAs bipolar junction transistors (BJTs) on semi-insulating substrates, such as GaAs or InP. The metamorphic InAs BJTs grown on InP and GaAs substrates are realized, studied and compared with the InAs BJTs lattice-matched grown on InAs substrates. The experimental results show that the surfaces are smoother and the leakage currents for base-collector junctions (Ir's) are smaller for the metamorphic BJTs with thicker buffer layer, although the surfaces are still rougher and Ir's are higher compared to InAs-based BJTs due to the lattice mismatch. Surprisingly, the current gains of all the metamorphic BJTs are not sensitive to the buffer layer thickness and comparable to the lattice-matched grown BJTs on InAs. They all have the current gains between 50 and 70 at room temperature. By comparing the metamorphic InAs BJTs on GaAs substrates and InP substrates, it is surprisingly discovered that the surface of the materials grown on GaAs substrates are smoother, which was not expected since the misfit between InAs and GaAs is twice greater than that between InAs and InP. This may be due to the difficulty of growing phosphides on arsenides. However, the devices on InP substrates exhibit better electrical characteristics than those on GaAs substrates. The success of fabricating InAs bipolar transistors on semi-insulating GaAs and InP substrates makes InAs-based high frequency and high speed devices possible.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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…

  3. 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…

  4. 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.

  5. 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.

  6. 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.

  7. Thermal management to avoid the collapse of current gain in power heterojunction bipolar transistors

    SciTech Connect

    Liu, W.

    1995-12-31

    One undesirable thermal phenomenon occurring in power heterojunction bipolar transistor is the collapse of current gain. This paper presents the electrical, electrical-thermal, thermal, and material approaches to avoid the collapse, and thus to improve the transistor output power.

  8. Dead-space corrected GaInP/GaAs composite collector double heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Poh, Z. S.; Yow, H. K.; Ong, D. S.; Houston, P. A.; Krysa, A. B.

    2007-04-01

    GaInP/GaAs/GaInP double heterojunction bipolar transistors incorporating dead-space corrected composite collectors were investigated experimentally. The optimized DHBT with a 10-nm lowly doped GaAs spacer and a 5-nm highly doped GaInP spacer has extended the operating range of the collector-emitter voltage, VCE, by maximizing the collector-emitter voltage at the onset of the multiplication, VCE ,onset, to 20 V, while minimizing the saturation voltage, VCE ,sat (<1 V), and maintaining the nominal breakdown voltage, BVCEO, of the GaInP collector at 25 V. The design incorporating an Al0.11Ga0.89As spacer rather than a GaInP spacer within the lowly doped GaAs-GaInP composite collector demonstrated similar breakdown behavior.

  9. 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.

  10. 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.

  11. GaAs transistors formed by Be or Mg ion implantation

    NASA Technical Reports Server (NTRS)

    Hunsperger, R. G.; Marsh, O. J.

    1974-01-01

    N-p-n transistor structures have been formed in GaAs by implanting n-type substrates with Be ions to form base regions and then implanting them with 20-keV Si ions to form emitters. P-type layers have been produced in GaAs by implantation of either Mg or Be ions, with substrate at room temperature, followed by annealing at higher temperatures.

  12. Inversion-mode GaAs wave-shaped field-effect transistor on GaAs (100) substrate

    SciTech Connect

    Zhang, Jingyun; Si, Mengwei; Wu, Heng; Ye, Peide D.; Lou, Xiabing; Gordon, Roy G.; Shao, Jiayi; Manfra, Michael J.

    2015-02-16

    Inversion-mode GaAs wave-shaped metal-oxide-semiconductor field-effect transistors (WaveFETs) are demonstrated using atomic-layer epitaxy of La{sub 2}O{sub 3} as gate dielectric on (111)A nano-facets formed on a GaAs (100) substrate. The wave-shaped nano-facets, which are desirable for the device on-state and off-state performance, are realized by lithographic patterning and anisotropic wet etching with optimized geometry. A well-behaved 1 μm gate length GaAs WaveFET shows a maximum drain current of 64 mA/mm, a subthreshold swing of 135 mV/dec, and an I{sub ON}/I{sub OFF} ratio of greater than 10{sup 7}.

  13. Inversion-mode GaAs wave-shaped field-effect transistor on GaAs (100) substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Jingyun; Lou, Xiabing; Si, Mengwei; Wu, Heng; Shao, Jiayi; Manfra, Michael J.; Gordon, Roy G.; Ye, Peide D.

    2015-02-01

    Inversion-mode GaAs wave-shaped metal-oxide-semiconductor field-effect transistors (WaveFETs) are demonstrated using atomic-layer epitaxy of La2O3 as gate dielectric on (111)A nano-facets formed on a GaAs (100) substrate. The wave-shaped nano-facets, which are desirable for the device on-state and off-state performance, are realized by lithographic patterning and anisotropic wet etching with optimized geometry. A well-behaved 1 μm gate length GaAs WaveFET shows a maximum drain current of 64 mA/mm, a subthreshold swing of 135 mV/dec, and an ION/IOFF ratio of greater than 107.

  14. 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.

  15. 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.

  16. Distinctive Features of the Temperature Sensitivity of a Transistor Structure in a Bipolar Mode of Measurement

    NASA Astrophysics Data System (ADS)

    Karimov, A. V.; Dzhuraev, D. P.; Kuliev, Sh. M.; Turaev, A. A.

    2016-03-01

    Results are presented of an experimental investigation of the temperature sensitivity of an individual base-to-collector junction of a bipolar transistor structure and of this same structure in the case of series connection of blocking emitter and collector junctions. It is shown that the temperature-sensitivity coefficient of the transistor structure operating in a bipolar mode of measurement is an order of magnitude larger than an analogous coefficient of the base-to-collector junction.

  17. 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.

  18. Evaluation of temperature-enhanced gain degradation of verticle npn and lateral pnp bipolar transistors

    SciTech Connect

    Witczak, S.C.; Lacoe, R.C.; Galloway, K.F.

    1997-03-01

    The effect of dose rate on radiation-induced gain degradation is compared for verticle npn and lateral pnp bipolar transistors. High dose rate irradiations at elevated temperatures are more effective at simulating low dose rate degradation in the lateral pnp transistors.

  19. 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.

  20. Extended velocity overshoot in InGaAs collectors for high-speed heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Maziar, Christine M.; Somervell, Mark H.; Kyono, Carl S.

    1990-08-01

    As 111-V device fabrication technology continues to improve and performance limiting parasitics are eliminated, the intrinsic speed of any given device structure and options for increasing that speed are of greater interest to device researchers and technologists. One approach to improving heterojunction bipolar transistor (HBT) high-frequency performance is to reduce the transit time across the collector space charge region by carefully tailoring the electric field in the collector in such a fashion as to extend or enhance velocity overshoot in the space charge region. This technique was first described' and demonstrated23 for AlGa,_As/GaAs HBTs. Recently, structures composed of materials lattice matched to InP substrates45 have emerged as champions in the race for high-speed and optical applications honors. Because these devices have utilized conventional collector structures, further gains can be achieved by application of collectors designed for enhanced or extended velocity overshoot. This is easily seen by noting that the extended velocity overshoot condition is more easily achieved in 1n053Ga047As than in GaAs, in large part due to the larger F - L conduction band separation (IEFL 0.55 eV for 1n053Ga047As; EEUL = 0.33 eV for GaAs). In this paper, we present Monte Carlo simulation results demonstrating the efficacy of the extended velocity overshoot approach for reducing transit times across the collector for a number of 1n053Ga047As collector structures.

  1. 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.

  2. 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.

  3. Self-aligned InGaP/GaAs heterojunction bipolar transistors for microwave power application

    SciTech Connect

    Ren, F.; Abernathy, C.R.; Pearton, S.J.; Lothian, J.R.; Wisk, P.W.; Fullowan, T.R.; Youngkai Chen ); Yang, L.W.; Fu, S.T.; Brozovich, R.S. )

    1993-07-01

    As an alternative to AlGaAs/GaAs heterojunction bipolar transistors (HBT's) for microwave applications, InGaP/ GaAs HBT's with carbon-doped base layers grown by metal organic molecular beam epitaxy (MOMBE) are demonstrated with excellent dc, RF, and microwave performance. As previously reported, with a 700-[angstrom]-thick base layer (135-[Omega]/[open square] sheet resistance), a dc current gain of 25, and cutoff frequency and maximum frequency of oscillation above 70 GHz were measured for a 2 [times] 5-[mu]m[sup 2] emitter area device. A device with 12 cells, each consisting of a 2 [times] 15-[mu] m[sup 2] emitter area device for a total emitter area of 360 [mu] m[sup 2], was power tested at 4 GHz under continuous-wave (CW) bias condition. The device delivered 0.6-W output power with 13-dB linear gain and a power-added efficiency of 50%.

  4. Recent advances in understanding total-dose effects in bipolar transistors

    SciTech Connect

    Schrimpf, R.D.

    1996-06-01

    Gain degradation in irradiated bipolar transistors can be a significant problem, particularly in linear integrated circuits. In many bipolar technologies, the degradation is greater for irradiation at low dose rates than it is for typical laboratory dose rates. Ionizing radiation causes the base current in bipolar transistors to increase, due to the presence of net positive charge in the oxides covering sensitive device areas and increases in surface recombination velocity. Understanding the mechanisms responsible for radiation-induced gain degradation in bipolar transistors is important in developing appropriate hardness assurance methods. This paper reviews recent modeling and experimental work, with the emphasis on low-dose-rate effects. A promising hardness assurance method based on irradiation at elevated temperatures is described.

  5. Dry etch damage in GaAs metal-semiconductor field-effect transistors exposed to inductively coupled plasma and electron cyclotron resonance Ar plasmas

    SciTech Connect

    Ren, F.; Lee, J.W.; Abernathy, C.R.; Pearton, S.J.; Constantine, C.; Barratt, C.; Shul, R.J.

    1997-07-01

    The effects of Ar plasma exposure on transconductance, channel sheet resistance, output resistance, and gate contact ideality factor of GaAs metal-semiconductor field-effect transistors (MESFETs) were investigated using two different high-density plasma sources, namely inductively coupled plasma and electron resonance plasma. Ion-induced damage is found to be reduced at moderate source powers ({approximately}200W) because of the reduction in cathode dc self-bias and hence ion energy, but at higher source powers the increase in ion flux produces significant deterioration of the device performance. Careful attention must be paid to both ion flux and ion energy in order to minimize ion-induced damage. Due to their relatively low channel doping levels, MESFETs are found to be more sensitive to plasma damage than devices with very heavily doped component layers such as heterojunction bipolar transistors. {copyright} {ital 1997 American Vacuum Society.}

  6. Radiation induced deep level defects in bipolar junction transistors under various bias conditions

    NASA Astrophysics Data System (ADS)

    Liu, Chaoming; Yang, Jianqun; Li, Xingji; Ma, Guoliang; Xiao, Liyi; Bollmann, Joachim

    2015-12-01

    Bipolar junction transistor (BJT) is sensitive to ionization and displacement radiation effects in space. In this paper, 35 MeV Si ions were used as irradiation source to research the radiation damage on NPN and PNP bipolar transistors. The changing of electrical parameters of transistors was in situ measured with increasing irradiation fluence of 35 MeV Si ions. Using deep level transient spectroscopy (DLTS), defects in the bipolar junction transistors under various bias conditions are measured after irradiation. Based on the in situ electrical measurement and DLTS spectra, it is clearly that the bias conditions can affect the concentration of deep level defects, and the radiation damage induced by heavy ions.

  7. 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.

  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. High Current Gain In0.49Ga0.51P/GaAs Heterojunction Bipolar Transistors with Double Spacers Grown by Gas Source Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Chen, Xiao-Jie; Chen, Jian-Xin; Chen, Yi-Qiao; Peng, Peng; Yang, Quan-Kui; Li, Ai-Zhen

    2000-12-01

    This paper reports the improved performance of the lattice-matched N-p+-n In0.49Ga0.51P/GaAs heterojunction bipolar transistors(HBTs) with undoped spacers grown by the gas source molecular beam epitaxy. A 600 Å GaAs base doped with beryllium at 3×1019 cm-3 and a 1000 Å In0.49Ga0.51P emitter doped with silicon at 3×1017 cm-3 have been grown. On both sides of the base, the 50 Å undoped GaAs spacers were grown. Devices with emitter area of 100 × 100 μm2 were fabricated by using selective wet chemical etching technique. The measured results of HBTs reveal good junction characteristics, and the common-emitter current gain reaches 320 at the collector current density of 280 A/cm2.

  10. Silicon on insulator bipolar junction transistors for flexible microwave applications

    NASA Astrophysics Data System (ADS)

    Bavier, John McGoldrick

    Microwave frequency flexible electronic devices require a high quality semiconducting material and a set of fabrication techniques that are compatible with device integration onto flexible polymer substrates. Over the past ten years, monocrystalline silicon nanomembranes (SiNMs) have been studied as a flexible semiconducting material that is compatible with industrial Si processing. Fabricated from commercial silicon on insulator (SOI) wafers, SiNMs can be transferred to flexible substrates using a variety of techniques. Due to their high carrier mobilities, SiNMs are a promising candidate for flexible microwave frequency devices. This dissertation presents fabrication techniques for flexible SiNM devices in general, as well as the progress made towards the development of a microwave frequency SiNM bipolar junction transistor (BJT). In order to overcome previous limitations associated with adhesion, novel methods for transfer printing of metal films and SiNMs are presented. These techniques enable transfer printing of a range of metal films and improve the alignment of small transfer printed SiNM devices. Work towards the development of a microwave frequency BJT on SOI for SiNM devices is also described. Utilizing a self-aligned polysilicon sidewall spacer technique, a BJT with an ultra-narrow base region is fabricated and tested. Two regimes of operation are identified and characterized under DC conditions. At low base currents, devices exhibited forward current gain as high as betaF = 900. At higher base current values, a transconductance of 59 mS was observed. Microwave scattering parameters were obtained for the BJTs under both biasing conditions and compared to unbiased measurements. Microwave frequency gain was not observed. Instead, bias-dependent non-reciprocal behavior was observed and examined. Limitations associated with the microwave impedance-matched electrode configuration are presented. High current densities in the narrow electrodes cause localized heating, which leads to electrode material damage and ultimately dopant diffusion in the BJT. Finally, device design improvements are proposed to address the problem of localized heating and increase device lifetime under testing conditions. High values for DC current gain suggest that future modifications should improve microwave frequency performance and measurement reproducibility.

  11. 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…

  12. 300 Degree C GaN/AlGaN Heterojunction Bipolar Transistor

    SciTech Connect

    Abernathy, C.R.; Baca, A.G.; Cho, H.; Chow, P.P.; Han, J.; Hichman, R.A.; Jung, K.B.; Kopf, R.F.; La Roche, J.R.; Pearton, S.J.; Ren, F.; Shul, R.J.; Van Hove, J.M.; Wilson, R.G.

    1998-10-14

    A GaN/AIGaN heterojunction bipolar transistor has been fabricated using C12/Ar dry etching for mesa formation. As the hole concentration increases due to more efficient ionization of the Mg acceptors at elevated temperatures (> 250oC), the device shows improved gain. Future efforts which are briefly summarized. should focus on methods for reducing base resistance.

  13. A breakdown model for the bipolar transistor to be used with circuit simulators

    SciTech Connect

    Keshavarz, A.A.; Raney, C.W.; Campbell, D.C.

    1993-08-01

    A breakdown model for the output characteristics of the bipolar transistor (bjt) has been developed. The behavioral modeling capability of PSPICE, a popular SPICE program (with Emphasis on Integrated circuits) was used to implement the macromodel. The model predicts bjt output characteristics under breakdown conditions. Experimental data was obtained to verify the macromodel. Good agreement exits between the measured and the simulated results.

  14. Laser processing of Silicon On Sapphire (SOS) for fabrication of bipolar transistors

    NASA Astrophysics Data System (ADS)

    Offord, B. W.; Russell, S. D.; Weiner, K. H.

    1990-11-01

    Nanosecond thermal processing using an excimer laser was used in fabrication of NPN bipolar transistors in silicon-on-sapphire (SOS). Functional devices with current gain approaching 100 were obtained. The deleterious effects of diffusion pipes in SOS material were minimized using rapid laser activation of in implanted dopant. Details of the device design fabrication, and test results are included in this report.

  15. Silicon bipolar transistor: a viable candidate for high speed applications at liquid nitrogen temperature

    NASA Astrophysics Data System (ADS)

    Cressler, John D.

    1990-12-01

    Despite its inherent speed advantage over CMOS technologies under loaded conditions, the silicon bipolar transistor historically has been dismissed as a viable candidate for digital applications in the 77 K environment. The principal reason for this is the well documented degradation in the device current gain at low temperatures. It is demonstrated in this paper that this conclusion is no longer valid with respect to state-of-the-art devices. The transistors used in this investigation have sufficient current gain at 77 K for most digital applications without intentional profile modification. Emitter coupled logic (ECL) circuits switch at < 100 ps speeds at 77 K, and reduced logic-swing operation offers the benefits of an attractive power-delay product. This paper examines the physics, design and performance issues associated with the low temperature operation of silicon bipolar transistors, and discusses the potential advantages of such devices for high speed applications in future low temperature computer systems.

  16. Radiation defects studies on silicon bipolar junction transistor irradiated by Br ions and electrons

    NASA Astrophysics Data System (ADS)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Ma, Guoliang; Xiao, Liyi; Bollmann, Joachim

    2015-12-01

    Bipolar junction transistors are sensitive to both ionization and displacement damage due to charged particles from space radiation. Passivating oxides and the SiO2/Si interface are more sensitive to ionization damage whereas displacement damage may strongly influence the bulk properties of a device. Fast electrons with energies below a few MeV introduces exclusively target ionization while heavy ions at moderate energies (lower than 2 MeV/amu) results in displacement damage due to individual Frenkel-pairs generation. Although both kinds of radiation are basically independent an effective correlation was seen in the electronic characteristics of transistors. We report on the effects on current gain and current-voltage characteristics of bipolar junction transistors due to successive irradiation with 20 MeV Br ions and 110 keV electrons.

  17. Topics on GaAs integrated circuit: GaAs grown on Si substrates, field-effect transistors, and electro-optic probing technique

    SciTech Connect

    Lo, Y.

    1987-01-01

    The possibility of integrating GaAs devices with Si devices by means of heteroepitaxy growth on Si is considered. The GaAs films are grown on Si substrates by molecular beam epitaxy. The material defects and thermal-induced stress in GaAs films are two fundamental problems of particular interests. The defects are mainly due to the inclined interface dislocations and stacking faults. It was found that these defects can be reduced if GaAs is grown on a clean and double-stepped Si surface. Various kinds of field-effect transistors (FET's) are demonstrated and analyzed. The buried-gate junction FET made by a submicron self-aligned process achieves a transconductance of 180 mS/mm. Besides, no back-gating effect is observed in this kind of device. Another novel device named as top-back-gate FET is also reported. In order to characterize the GaAs material and device in a non-invasive way, the author developed the electro-optic probing technique. Because the refractive indices of GaAs are modified by electric fields, he could obtain the information about internal fields in GaAs devices or material from the phase retardation of a probing beam. The experimental results in potential profile probing of various device structures are reported.

  18. 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.

  19. On the characterization and optimization of high-speed silicon bipolar transistors

    NASA Astrophysics Data System (ADS)

    Vanwijnen, Paul Jacques

    An on wafer high frequency measurement technique and its application to accurate small signal characterization and optimization of high speed bipolar transistors is presented. The evolution of high speed bipolar transistors and the need for accurate tools for device characterization, device modeling and parameter extraction, and device optimization are discussed. An introduction of small signal analysis and two port parameters is given. The scattering or s parameters and their relationships to the more conventional z, y, h, g, a and b Kirchhoff based two port parameter sets are derived. The custom high frequency small signal measurement setup, assembled from commercially available components, is described. The basic measurement methodology developed in order to account for these errors in a consistent manner is discussed. In particular, how this general methodology can be specialized to apply to on wafer measurements, is also discussed. High frequency characterization of small geometry bipolar transistors up to 18 GHz at various bias conditions is discussed. The device optimization is studied in the context of improving the high frequency performance. The use of a localized collector implant to improve the performance of polysilicon transistors is considered.

  20. Emitter injection efficiency and base transport factor in InAs bipolar transistors

    NASA Astrophysics Data System (ADS)

    Wu, X.; Maimon, S.; Averett, K. L.; Koch, M. W.; Wicks, G. W.

    2003-10-01

    The factors affecting the common emitter current gain (β) in InAs bipolar junction transistors (BJTs) have been studied by estimating the base transport factor (αT) and the emitter injection efficiency (γ). This has been accomplished by employing a specially designed sequence of InAs npn BJTs. αT, γ, and the minority carrier (electrons) diffusion length in the base (LB) are extracted from measured electrical characteristics by using a simple method. When the emitter doping density is large, the current gain is limited by the base transport factor αT. The value of LB in these BJTs is found to be 0.44 μm, which indicates high quality epitaxial material. The analysis developed is a general technique, also applicable to BJTs and heterojunction bipolar transistors in other material systems.

  1. Dose-rate effects on radiation-induced bipolar junction transistor gain degradation

    SciTech Connect

    Wei, A.; Kosier, S.L.; Schrimpf, R.D. ); Fleetwood, D.M. ); Combs, W.E. )

    1994-10-10

    Analysis of radiation damage in modern [ital NPN] bipolar transistors at various dose rates is performed with a recently introduced charge separation method and PISCES simulations. The charge separation method is verified with measurements on metal-oxide-semiconductor capacitors. Gain degradation is more pronounced at lower dose rates. The charge separation technique reveals that depletion-region spreading and effective recombination velocity are both greater for devices irradiated at lower dose rates.

  2. Laterally etched undercut (LEU) technique to reduce base-collector capcitances in heterojunction bipolar transistors

    SciTech Connect

    Liu, W.; Hill, D.; Chau, H.F.

    1995-12-31

    The authors report a novel fabrication process aimed at reducing the parasitic junction capacitance of AlGaAs/GaAs heterojunction bipolar transistors. The process, named as the Laterally Etched Undercut (LEU) process, physically removes the extrinsic base-collector junction area and results in a cantilever structure. The d.c., small-signal, and large-signal performances of the LEU devices are compared to those obtained from the conventional devices.

  3. 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.

  4. Effect of High-Voltage Heterojunction Bipolar Transistor Collector Design on f(T) and f(MAX)

    SciTech Connect

    Ashby, C.I.H.; Baca, A.G.; Chang, P.C.; Hietala, V.M.

    1999-03-02

    High-speed InGaP/GaAs heterojunction bipolar transistors (HBTs) for high-voltage circuit applications have been investigated. In order to obtain ideal IV characteristics, a lightly doped (N{sub DC} = 7.5 x 10{sup 15} cm{sup {minus}3}) thick (W{sub C} = 3.5 {micro}m) layer of GaAs was used as the collector layer. The devices fabricated have shown breakdown voltage exceeding 65 V. Device operated at up to a 60V bias, which is the highest operating voltage reported up to date for single heterojunction HBTs. Peak {line_integral}{sub T} and {line_integral}{sub MAX} values of 18 GHz and 29 GHz, respectively, have been achieved on a device with emitter area of 4x 12.5 {micro}m{sup 2}. Both {line_integral}{sub T} and {line_integral}{sub Max} degrades with higher bias, which is related to the elongation of the collector depletion width.

  5. 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.

  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. Optical reduction of low frequency noise in cryogenic GaAs junction field effect transistor

    NASA Astrophysics Data System (ADS)

    Fujiwara, M.; Nagata, H.; Matsuo, H.; Sasaki, M.

    2008-07-01

    We demonstrated optical low frequency noise reduction in a n-type SONY GaAs junction field effect transistor (JFET) (gate width: 5μm; length: 1μm) operating at 4.2K. At 1Hz, a 6dB decrease and a 10dB increase in noise were observed when the JFET (band gap: 1.51eV) was illuminated by light with wavelengths of 1650 and 1550nm, respectively, for a drain voltage of 0.5V and drain current of 0.25μA. When the drain current was 0.5μA, 1650nm illumination increased the noise; moreover, hysteretic behavior in response to the illumination was also observed. These results show that deep level trapped charges apparently affect low frequency noise, which can be controlled by illumination using photons whose energies are below the band gap energy at cryogenic temperatures.

  8. 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.

  9. Residual phase noise modeling of amplifiers using silicon bipolar transistors.

    PubMed

    Theodoropoulos, Konstantinos; Everard, Jeremy

    2010-03-01

    In this paper, we describe the modeling of residual 1/f phase noise for Si bipolar amplifiers operating in the linear region. We propose that for Si bipolar amplifiers, the 1/f phase noise is largely caused by the base emitter recombination flicker noise. The up-conversion mechanism is described through linear approximation of the phase variation of the amplifier phase response by the variation of the device parameters (C(b)c, C(be), g(m), r(e)) caused by the recombination 1/f noise. The amplifier phase response describes the device over the whole frequency range of operation for which the influence of the poles and zeros is investigated. It is found that for a common emitter amplifier it is sufficient to only incorporate the effect of the device poles to describe the phase noise behavior over most of its operational frequency range. Simulations predict the measurements of others, including the flattening of the PM noise at frequencies beyond f(3dB), not predicted by previous models. PMID:20211771

  10. SiGe heterojunction bipolar transistorsThe noise perspective

    NASA Astrophysics Data System (ADS)

    Schumacher, Hermann; Erben, Uwe; Drr, Wolfgang

    1997-10-01

    Si/SiGe heterojunction transistors with high germanium concentration in the base layer are capable of microwave noise figures below 1 dB at X-band frequencies, because of their low base resistance. We review critical device parameters which influence the minimum noise figure, location of the noise-optimum source reflection coefficient, and associated gain at noise match, including both low-parasitic double-mesa and highly manufacturable box-shaped HBT devices in our considerations. A higher associated gain can be obtained when the base-collector feedback capacitance is reduced. Using larger transistors, both the magnitude of the noise-optimum source reflection coefficient and the equivalent noise resistance will be reduced, making input matching easier and less lossy. Low-frequency noise results show 1/ f corner frequencies below 1 kHz in microwave devices. Two circuit examples, a d.c.-18 GHz amplifier and a low-noise active antenna at 5.8 GHz, demonstrate that device capabilities can be translated into superior circuit performance.

  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. Performance enhancement of a heterojunction bipolar transistor (HBT) by two-step passivation

    NASA Astrophysics Data System (ADS)

    Fu, Ssu-I.; Lai, Po-Hsien; Tsai, Yan-Ying; Hung, Ching-Wen; Yen, Chih-Hung; Cheng, Shiou-Ying; Liu, Wen-Chau

    2006-09-01

    An interesting two-step passivation (with ledge structure and sulphide based chemical treatment) on base surface, for the first time, is demonstrated to study the temperature-dependent DC characteristics and noise performance of an InGaP/GaAs heterojunction bipolar transistor (HBT). Improved transistor behaviors on maximum current gain βmax, offset voltage Δ VCE, and emitter size effect are obtained by using the two-step passivation. Moreover, the device with the two-step passivation exhibits relatively temperature-independent and improved thermal stable performances as the temperature is increased. Therefore, the two-step passivationed device can be used for high-temperature and low-power electronics applications.

  13. 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.

  14. Modeling plasma-induced bandgap narrowing effects for accurate simulation of advanced silicon bipolar transistors

    NASA Astrophysics Data System (ADS)

    Reaz Shaheed, M.; Maziar, C. M.

    1994-09-01

    Existing models for plasma-induced bandgap narrowing are briefly reviewed. A simple and more general model for plasma-induced bandgap narrowing in Si devices is proposed. Different issues related to modeling of plasma-induced bandgap narrowing are discussed. Results of numerical simulation of an advanced Si bipolar transistor structure are presented. Results of the simulations are compared with experimental data. It is shown that inclusion of plasma-induced bandgap narrowing model provides a more accurate estimate of the current gain characteristics. It is also shown that this effect becomes more important for simulation at low temperatures. The reasons behind the stronger effect at low temperatures are explained.

  15. Monte Carlo evaluation of electron transport in heterojunction bipolar transistor base structures

    NASA Astrophysics Data System (ADS)

    Maziar, C. M.; Klausmeier-Brown, M. E.; Bandyopadhyay, S.; Lundstrom, M. S.; Datta, S.

    1986-07-01

    Electron transport through base structures of Al(x)Ga(1-x)As heterojunction bipolar transistors is evaluated by Monte Carlo simulation. Simulation results demonstrate the effectiveness of both ballistic launching ramps and graded bases for reducing base transit time. Both techniques are limited, however, in their ability to maintain short transit times across the wide bases that are desirable for reduction of base resistance. Simulation results demonstrate that neither technique is capable of maintaining a 1-ps transit time across a 0.25-micron base. The physical mechanisms responsible for limiting the performance of each structure are identified and a promising hybrid structure is described.

  16. 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.

  17. 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.

  18. 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.

  19. 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 10100 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 ?W 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.

  20. 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.

  1. 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

  2. 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.

  3. Complementary GaAs junction-gated heterostructure field effect transistor fabrication for integrated circuits

    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.

    1994-10-01

    A new GaAs junction-gated complementary logic technology that integrates a modulation doped p-channel heterostructure field effect transistor (pHFET) and a fully ion implanted n-channel JFET has recently been fabricated. High-speed, low-power operation has been demonstrated with loaded ring oscillators that show gate delays of 179 ps/stage for a power-delay product of 28 fJ at 1.2 V operation and 320 ps/stage and 8.9 fJ at 0.8 V operation. The principal advantages of this technology include the ability to independently set the threshold voltage of n- and p-channel devices and to independently design the pHFET for high performance. A self-aligned refractory gate process based on tungsten and tungsten silicide gate metal has been used to fabricate the FETs. Novel aspects of the fabrication include the simultaneous formation of non-alloyed, refractory ohmic contacts for the junction gates and the formation of shallow p-n junctions by ion implantation.

  4. The influence of a doping profile on the characteristics of an ion-implanted GaAs field-effect transistor with a Schottky barrier

    SciTech Connect

    Shestakov, A. K. Zhuravlev, K. S.

    2011-12-15

    A GaAs field-effect ion-implanted transistor with a Schottky barrier is simulated. The doping profile obtained when doping through an insulator mask is determined and the dependences of the static transistor characteristics on the parameters of the doping profile are calculated and analyzed. The physical processes controlling the transistor characteristics in the case of a variation in the parameters of its doping profile and the coefficient of compensation of the substrate are studied. Based on calculations, the optimal doping-profile parameters ensuring the best characteristics for transistors are predicted.

  5. 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.

  6. Selective area chemical beam epitaxial regrowth of Si-doped GaAs by using silicon tetraiodide for field effect transistor application

    NASA Astrophysics Data System (ADS)

    Izumi, Shigekazu; Yamamoto, Yoshitsugu; Kunii, Tetsuro; Miyakuni, Shinichi; Hayafuji, Norio; Sato, Kazuhiko; Otsubo, Mutsuyuki

    1997-05-01

    Selective area regrowth of silicon-doped GaAs has been successfully achieved by chemical beam epitaxy (CBE) on dry etched trench structures. Abrupt doping-interface and excellent doping controllability have also been achieved by using a novel silicon dopant source of silicon tetraiodide (SiI 4). Metal-semiconductor field effect transistor (MESFET) and heterostructure field effect transistor (HFET) fabricated in this way with Ni/AuGe/Au alloyed contact contact metals on the Si-doped GaAs regrown layer reveal contact resistances as low as 3 × 10 - 7 Ω cm2 and perfect selectivity there being no polycrystalline growth on the dielectric mask film.

  7. 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.

  8. 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.

  9. 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.

  10. High-performance InGaP/GaAs pnp {delta}-doped heterojunction bipolar transistor

    SciTech Connect

    Tsai, J.-H. Chiu, S.-Y.; Lour, W.-S.; Guo, D.-F.

    2009-07-15

    In this article, a novel InGaP/GaAs pnp {delta}-doped heterojunction bipolar transistor is first demonstrated. Though the valence band discontinuity at InGaP/GaAs heterojunction is relatively large, the addition of a {delta}-doped sheet between two spacer layers at the emitter-base (E-B) junction effectively eliminates the potential spike and increases the confined barrier for electrons, simultaneously. Experimentally, a high current gain of 25 and a relatively low E-B offset voltage of 60 mV are achieved. The offset voltage is much smaller than the conventional InGaP/GaAs pnp HBT. The proposed device could be used for linear amplifiers and low-power complementary integrated circuit applications.

  11. 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.

  12. 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.

  13. Modeling ionizing radiation induced gain degradation of the lateral PNP bipolar junction transistor

    SciTech Connect

    Schmidt, D.M.; Wu, A.; Schrimpf, R.D.; Fleetwood, D.M.; Pease, R.L.

    1996-12-01

    Ionizing-radiation-induced gain degradation in lateral PNP bipolar junction transistors is due to an increase in base current as a result of recombination at the surface of the device. A qualitative model is presented which identifies the physical mechanism responsible for excess base current. The increase in surface recombination velocity due to interface traps results in an increase in excess base current and the positive oxide charge moderates the increase in excess base current and changes the slope of the current-voltage characteristics. Analytical and empirical models have been developed to quantitatively describe the excess base current response to ionizing radiation. It is shown that the surface recombination velocity dominates the excess base current response to total dose.

  14. 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.

  15. 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).

  16. 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.

  17. GaN pnp bipolar junction transistors operated to 250 C

    SciTech Connect

    Zhang, A.P.; Dang, G.; Ren, F.; Han, J.; Monier, C.; Baca, A.G.; Cao, X.A.; Cho, H.; Abernathy, C.R.; Pearton, S.J.

    2000-01-03

    The authors report on the dc performance of the first GaN pnp bipolar junction transistor. The structure was grown by MOCVD on c-plane sapphire substrates and mesas formed by low damage Inductively Coupled Plasma etching with a Cl{sub 2}/Ar chemistry. The dc characteristics were measured up to V{sub BC} of 65 V in common base mode and at temperatures up to 250 C. Under all conditions, I{sub C} {approximately} I{sub E}, indicating higher emitter injection efficiency. The offset voltage was {le} 2 V and devices were operated up to power densities of 40kW{center{underscore}dot}cm{sup {minus}2}.

  18. 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.

  19. Microwave performance of a self-aligned GaInP/Ga heterojunction bipolar transistor

    SciTech Connect

    Liu, W.; Fan, Shoukong; Henderson, T. ); Davito, D. )

    1993-04-01

    Microwave performance of a self-aligned GaInP/GaAs heterojunction bipolar transistor (HBT) is presented. At an operating current density of 2.08 [times] 10[sup 4] A/cm[sup 2], the measured cutoff frequency is 50 GHz, and the maximum oscillation frequency extrapolated from measured unilateral gain and the maximum available gain are 116 and 81 GHz, respectively, all using 20-dB/decade slopes. To the author's knowledge, these represent the highest reported values of HBT's based on the GaInP/GaAs material system. These results are compared with other reported high-frequency performance of GaInP HBT's. In addition, these results are compared with AlGaAs/GaAs HBT's having a similar device structure.

  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 conventional device.

  1. 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.

  2. Transient electro-thermal characterization of Si-Ge heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Sahoo, Amit Kumar; Weiß, Mario; Fregonese, Sébastien; Malbert, Nathalie; Zimmer, Thomas

    2012-08-01

    In this paper, a comprehensive evaluation of the transient self-heating in microwave heterojunction bipolar transistors (HBTs) have been carried out through simulations and measurements. Three dimensional thermal TCAD simulations have been performed to investigate precisely the influence of backend metallization on transient thermal behavior of a submicron SiGe:C BiCMOS technology with fT and fmax of 230 GHz and 290 GHz, respectively. Transient variation of Collector current caused by self-heating is obtained through pulse measurements. For thermal characterization, different electro-thermal networks have been employed at the temperature node of HiCuM compact model. Thermal parameters have been extracted by means of compact model simulation using a scalable transistor library. It has been shown that, the conventional R-C thermal network is not sufficient to accurately model the transient thermal spreading behavior and therefore a recursive network needs to be used. Recursive network is verified with device simulations as well as measurements and found to be in excellent agreement.

  3. Radiative recombination in GaN/InGaN heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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 IB-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.

  4. 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.

  5. The influence of collector designs on fmax versus ft characteristics for different types of Si-based RF bipolar transistors

    NASA Astrophysics Data System (ADS)

    Schippel, Christian; Schwierz, Frank; Fu, Jun

    2007-01-01

    The cut-off frequency ft, the maximum frequency of oscillation fmax and the collector-emitter breakdown voltage BVCEO are computed for various types of Si-based bipolar transistors with different selectively implanted collector (SIC) profiles. In particular, the influence of SIC profiles on ft versus BVCEO and fmax versus BVCEO characteristics is investigated. Subsequently, the fmax versus ft behaviour is discussed. It is shown that for slow transistors (BJTs) there is a trade-off between ft and fmax. However, in the case of faster HBTs this trend can be reversed.

  6. 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.

  7. Halogen-containing compounds in solid source III-V molecular beam epitaxy, and their use for fabrication of high performance heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Micovic, Miroslav

    The theme of this dissertation is the improvement of III-V compound semiconductor heterojunction bipolar transistors (HBT's) through the use of iodine or bromine in molecular beam epitaxy (MBE). The motivation for this work is to increase the speed of AlGaAs/GaAs HBT's by reduction of base resistance and parasitic base-collector capacitance. The base resistance of an HBT can be minimized, without severely affecting the base transit time, by doping the base to the highest attainable level. It is demonstrated in this work that epitaxial layers suitable for fabrication of AlGaAs/GaAs HBT's with a carbon base doping level of up to 10sp{20} cmsp{-3} can be grown by solid source MBE using CBrsb4 as a doping precursor. The DC gain of HBT's with extremely heavily doped base layers was studied to determine the base thickness which will provide the lowest possible base resistance and a current gain still acceptable for fabrication of microwave HBT's. Use of iodine for in situ etching and surface cleaning of GaAs, AlGaAs and InGaAs and InGaAs in the MBE growth chamber is demonstrated for the first time. In-situ etching and growth capabilities integrated in the same chamber were used for fabrication of AlGaAs/GaAs HBT's with selectively buried sub-collectors for reduction of base-collector capacitance. Fabrication of these device structures was successfully demonstrated by MBE regrowth on pre-patterned sub-collector mesa structures. Growth of GaAs and AlGaAs layers under an intentional flux of Isb2 molecules was explored in molecular beam epitaxy. An improvement of material quality which coincides with the history of iodine use in the MBE chamber was observed.

  8. Very high current gain InGaAs/InP heterojunction bipolar transistors grown by metalorganic chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Kyono, C. S.; Pinzone, C. J.; Maziar, C. M.; Dupuis, R. D.; Gerrard, N. D.

    1991-01-01

    A maximum dc current gain of 24,000 and small-signal current gain of 49,000 were obtained for InGaAs/InP heterojunction bipolar transistors (HBTs) grown by MOCVD. The excellent HBT gain performance is attributed to the exceptional material quality, the good control over p-type dopant diffusion at the base-emitter heterojunction, and the existence of a doping-induced drift field in the base.

  9. 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.

  10. The physics of high-speed transistors

    NASA Astrophysics Data System (ADS)

    Pozhela, Iuras K.

    This book considers the physics of high-speed transistors operating at frequencies above 10 Ghz and whose switching time is shorter than 100 ps. The physical principles permitting the augmentation of transistor speed are elaborated with reference to traditional types of transistors (bipolar and FET), the advanced heterostructure and ballistic transistors, and new concepts such as quantum transistors. The high-speed transistors are made from III-V semiconductors with high electron mobility and high drift velocity such as GaAs, InGaAs, AlGaAs, and InP. Data on the highest speed values achieved so far are presented, and the potential for further speed enhancement is assessed.

  11. 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.

  12. Electron Transport Behavior on Gate Length Scaling in Sub-50 nm GaAs Metal Semiconductor Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Han, Jaeheon

    2011-12-01

    Short channel GaAs Metal Semiconductor Field Effect Transistors (MESFETs) have been fabricated with gate length to 20 nm, in order to examine the characteristics of sub-50 nm MESFET scaling. Here the rise in the measured transconductance is mainly attributed to electron velocity overshoot. For gate lengths below 40 nm, however, the transconductance drops suddenly. The behavior of velocity overshoot and its degradation is investigated and simulated by using a transport model based on the retarded Langevin equation (RLE). This indicates the existence of a minimum acceleration length needed for the carriers to reach the overshoot velocity. The argument shows that the source resistance must be included as an internal element, or appropriate boundary condition, of relative importance in any model where the gate length is comparable to the inelastic mean free path of the carriers.

  13. 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.

  14. 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

  15. 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.

  16. Multi-level interconnects for heterojunction bipolar transistor integrated circuit technologies

    SciTech Connect

    Patrizi, G.A.; Lovejoy, M.L.; Schneider, R.P. Jr.; Hou, H.Q.; Enquist, P.M.

    1995-12-31

    Heterojunction bipolar transistors (HBTs) are mesa structures which present difficult planarization problems in integrated circuit fabrication. The authors report a multilevel metal interconnect technology using Benzocyclobutene (BCB) to implement high-speed, low-power photoreceivers based on InGaAs/InP HBTs. Processes for patterning and dry etching BCB to achieve smooth via holes with sloped sidewalls are presented. Excellent planarization of 1.9 {micro}m mesa topographies on InGaAs/InP device structures is demonstrated using scanning electron microscopy (SEM). Additionally, SEM cross sections of both the multi-level metal interconnect via holes and the base emitter via holes required in the HBT IC process are presented. All via holes exhibit sloped sidewalls with slopes of 0.4 {micro}m/{micro}m to 2 {micro}m/{micro}m which are needed to realize a robust interconnect process. Specific contact resistances of the interconnects are found to be less than 6 {times} 10{sup {minus}8} {Omega}cm{sup 2}. Integrated circuits utilizing InGaAs/InP HBTs are fabricated to demonstrate the applicability and compatibility of the multi-level interconnect technology with integrated circuit processing.

  17. Bipolar-power-transistor-based limiter for high frequency ultrasound imaging systems

    PubMed Central

    Choi, Hojong; Yang, Hao-Chung; Shung, K. Kirk

    2013-01-01

    High performance limiters are described in this paper for applications in high frequency ultrasound imaging systems. Limiters protect the ultrasound receiver from the high voltage (HV) spikes produced by the transmitter. We present a new bipolar power transistor (BPT) configuration and compare its design and performance to a diode limiter used in traditional ultrasound research and one commercially available limiter. Limiter performance depends greatly on the insertion loss (IL), total harmonic distortion (THD) and response time (RT), each of which will be evaluated in all the limiters. The results indicated that, compared with commercial limiter, BPT-based limiter had less IL (–7.7 dB), THD (–74.6 dB) and lower RT (43 ns) at 100MHz. To evaluate the capability of these limiters, they were connected to a 100 MHz single element transducer and a two-way pulse-echo test was performed. It was found that the -6 dB bandwidth and sensitivity of the transducer using BPT-based limiter were better than those of the commercial limiter by 22 % and 140 %, respectively. Compared to the commercial limiter, BPT-based limiter is shown to be capable of minimizing signal attenuation, RT and THD at high frequencies and is thus suited for high frequency ultrasound applications. PMID:24199954

  18. 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

  19. 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).

  20. Bipolar-power-transistor-based limiter for high frequency ultrasound imaging systems.

    PubMed

    Choi, Hojong; Yang, Hao-Chung; Shung, K Kirk

    2014-03-01

    High performance limiters are described in this paper for applications in high frequency ultrasound imaging systems. Limiters protect the ultrasound receiver from the high voltage (HV) spikes produced by the transmitter. We present a new bipolar power transistor (BPT) configuration and compare its design and performance to a diode limiter used in traditional ultrasound research and one commercially available limiter. Limiter performance depends greatly on the insertion loss (IL), total harmonic distortion (THD) and response time (RT), each of which will be evaluated in all the limiters. The results indicated that, compared with commercial limiter, BPT-based limiter had less IL (-7.7 dB), THD (-74.6 dB) and lower RT (43 ns) at 100 MHz. To evaluate the capability of these limiters, they were connected to a 100 MHz single element transducer and a two-way pulse-echo test was performed. It was found that the -6 dB bandwidth and sensitivity of the transducer using BPT-based limiter were better than those of the commercial limiter by 22% and 140%, respectively. Compared to the commercial limiter, BPT-based limiter is shown to be capable of minimizing signal attenuation, RT and THD at high frequencies and is thus suited for high frequency ultrasound applications. PMID:24199954

  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. Model of radiation-induced gain degradation of NPN bipolar junction transistor at different dose rates

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Ionizing-radiation-induced current gain degradation in NPN bipolar junction transistors is due to an increase in base current as a result of recombination at the surface of the device. A model is presented which identifies the physical mechanism responsible for current gain degradation. The increase in surface recombination velocity due to interface states results in an increase in base current. Besides, changing the surface potential along the base surface induced by the oxide-trapped charges can also lead to an increased base current. By combining the production mechanisms of oxide-trapped charges and interface states, this model can explain the fact that the current gain 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 70 krad(Si). The low dose rate was 0.1 rad(Si)/s and the high dose rate was 10 rad(Si)/s. The model accords well with the experimental results. Project supported by the National Natural Science Foundation of China (Nos. 61076101, 61204092).

  3. 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.

  4. Damage effect and mechanism of the GaAs high electron mobility transistor induced by high power microwave

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Chang-Chun, Chai; Yin-Tang, Yang; Jing, Sun; Zhi-Peng, Li

    2016-04-01

    In this paper, we present the damage effect and mechanism of high power microwave (HPM) on AlGaAs/GaAs pseudomorphic high-electron-mobility transistor (pHEMT) of low-noise amplifier (LNA). A detailed investigation is carried out by simulation and experiment study. A two-dimensional electro-thermal model of the typical GaAs pHEMT induced by HPM is established in this paper. The simulation result reveals that avalanche breakdown, intrinsic excitation, and thermal breakdown all contribute to damage process. Heat accumulation occurs during the positive half cycle and the cylinder under the gate near the source side is most susceptible to burn-out. Experiment is carried out by injecting high power microwave into GaAs pHEMT LNA samples. It is found that the damage to LNA is because of the burn-out at first stage pHEMT. The interiors of the damaged samples are observed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Experimental results accord well with the simulation of our model. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900) and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (Grant No. 2015-0214.XY.K).

  5. 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}.

  6. 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.

  7. 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.

  8. Triple implant (In,Ga)As/InP n-p-n heterojunction bipolar transistors for integrated circuit applications

    NASA Astrophysics Data System (ADS)

    Masum Choudhury, A. N. M.; Tabatabaie-Alavi, K.; Fonstad, C. G.

    1984-07-01

    For the first time (In,Ga)As/InP n-p-n heterojunction bipolar transistors (HJBT's) applicable to integrated circuits have been fabricated by triple ion implantation. The base has been formed by beryllium ion implantation and the collector by silicon ion implantation. The implants were made into an LPE-grown n-n (In,Ga)As/InP heterostructure on an n(+)-InP substrate. This inverted mode emitter-down heterojunction transistor structure demonstrates to a maximum current gain of 7 with no hysteresis in the characteristics. The ideality factors of the I(B) versus V(BE) and I(C) versus V(BE) characteristics with V(CB) = 0, are 1.25 and 1.08, respectively, indicating that the defect level in the heterojunction is low and that minority-carrier injection and diffusion is the dominant current flow mechanism.

  9. Effect of parasitic series resistances and spurious currents on the extracted temperature of a bipolar junction transistor.

    PubMed

    Mimila-Arroyo, J

    2013-12-01

    Verster's proposition to directly extract the temperature of a bipolar junction transistor using its collector current is widely used. However, the resulting temperature is low accurate even when calibrated. Here, it is demonstrated that the misuse of the emitter current instead of the collector one, because of the presence of spurious currents other than the injection-diffusion one and transistor parasitic series resistances both contribute to the observed inaccuracy. Particularly parasitic series resistances increase the inaccuracy and introduce a strong dependence of the extracted temperature on the collector currents used to extract the temperature; the higher those resistances the higher the inaccuracy. A proposition is made to reduce the effect of those resistances on the inaccuracy of this thermometric element, which allows obtaining a more accurate value on a wider range of the collector probe currents. PMID:24387455

  10. Bipolar Characteristics of an Organic Light-Emitting Filed Effect Transistor Using a TPTPT and NTCDA Co-Deposited Layer

    NASA Astrophysics Data System (ADS)

    Uchiuzou, Hiroyuki; Oyamada, Takahito; Sasabe, Hiroyuki; Adachi, Chihaya

    We fabricated an organic light-emitting field effect transistors (OLEFET) using a co-deposited layer of TPTPT and NTCDA which has p-type and n-type semiconducting behaviors, respectively. The organic layer was formed on a comb type electrode (source-drain electrodes) with a channel length of 25μm on a p-Si/SiO2 substrate. Bipolar and EL characteristics were investigated by changing co-deposition ratio of TPTPT and NTCDA. In the optimum deposition ratio, we observed typical ambipolar characteristics, demonstrating saturation current characteristics at low Vd (source-drain voltage), followed by divergent current characteristics at high Vd.

  11. 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 to provide consistently accurate values for base sheet resistance for both Si- and SiGe-base transistors over a wide range of temperatures. A model for plasma-induced bandgap narrowing suitable for implementation in a numerical simulator has been developed. The appropriate method of incorporating this model in a drift -diffusion solver is described. The importance of including this model for low temperature simulation is demonstrated. With these models in place, the enhanced simulator has been used for evaluating and designing the Si- and SiGe-base bipolar transistors. Silicon-germanium heterojunction bipolar transistors offer significant performance and cost advantages over conventional technologies in the production of integrated circuits for communications, computer and transportation applications. Their high frequency performance at low cost, will find widespread use in the currently exploding wireless communication market. However, the high performance SiGe-base transistors are prone to have a low common-emitter breakdown voltage. In this dissertation, a modification in the collector design is proposed for improving the breakdown voltage without sacrificing the high frequency performance. A comprehensive simulation study of p-n-p SiGe-base transistors has been performed. Different figures of merit such as drive current, current gain, cut -off frequency and Early voltage were compared between a graded germanium profile and an abrupt germanium profile. The differences in the performance level between the two profiles diminishes as the base width is scaled down.

  12. Damage effect and mechanism of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    NASA Astrophysics Data System (ADS)

    Xiao-Wen, Xi; Chang-Chun, Chai; Gang, Zhao; Yin-Tang, Yang; Xin-Hai, Yu; Yang, Liu

    2016-04-01

    The damage effect and mechanism of the electromagnetic pulse (EMP) on the GaAs pseudomorphic high electron mobility transistor (PHEMT) are investigated in this paper. By using the device simulation software, the distributions and variations of the electric field, the current density and the temperature are analyzed. The simulation results show that there are three physical effects, i.e., the forward-biased effect of the gate Schottky junction, the avalanche breakdown, and the thermal breakdown of the barrier layer, which influence the device current in the damage process. It is found that the damage position of the device changes with the amplitude of the step voltage pulse. The damage appears under the gate near the drain when the amplitude of the pulse is low, and it also occurs under the gate near the source when the amplitude is sufficiently high, which is consistent with the experimental results. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900), and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (CAEP) (Grant No. 2015-0214.XY.K).

  13. 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.

  14. Comparison of phonon scattering in nanowire field effect transistors with Si, GaAs and InGaAs cores using the NEGF formalism

    NASA Astrophysics Data System (ADS)

    Price, A.; Martinez, A.

    2015-10-01

    Using the Non-equilibrium Green's Function (NEGF) formalism, the impact of electron- phonon scattering on the performance of different core nanowire field effect transistors (NWFETs) has been investigated. Three core materials have been considered: Si, GaAs and InGaAs. The effective mass approximation has been used, with masses extracted from tight- binding simulations. The ID-VG characteristics at low and high drain bias are shown. It was found that at low drain bias, scattering caused a 86%, 72% and 50% percentage reduction in the current at high gate bias in the Si, GaAs and InGaAs core, 2.2 × 2.2 nm2 cross-section NWFETs respectively. The phonon-limited mobility and percentage tunnelling have also been calculated.

  15. 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.

  16. 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.

  17. 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.

  18. Modulation of high current gain (β>49) light-emitting InGaN /GaN heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Chu-Kung, B. F.; Wu, C. H.; Walter, G.; Feng, M.; Holonyak, N.; Chung, T.; Ryou, J.-H.; Dupuis, R. D.

    2007-12-01

    The electrical and optical characteristics of high-gain, small-area InGaN /GaN heterojunction bipolar transistors (HBTs) grown by metal-organic chemical vapor deposition on sapphire substrate are reported. The common-emitter current-voltage characteristics of a 3×10μm2 emitter device demonstrates a current gain β =ΔIC/ΔIB=49 at 3mA and breakdown voltage, BVCEO>70V. The radiative recombination spectrum of a large area 100×100μm2 emitter HBT is measured, showing a peak at 387nm and a full width at half maximum of 47nm. A 1kHz modulation input is applied to the HBT and both the optical and electrical outputs of a large area device is demonstrated.

  19. 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.

  20. 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.

  1. Non-equilibrium electron dynamics phenomena in scaled sub-100 nanometer gate length GaAs metal semiconductor field effect transistors

    NASA Astrophysics Data System (ADS)

    Han, Jaeheon; Yoo, Seungjin

    2005-06-01

    Ultrashort channel GaAs metal semiconductor field effect transistors were fabricated with gate lengths ranging from 30 nm to 1 05 nm, by electron beam lithography, in order to examine the scaling characteristics of transconductance. For gate lengths in sub-100 nanometer range, where gradual channel approximation is no longer valid, it was observed that the transconductance varies with a variety of small-dimension-related, nonequilibrium electron dynamics phenomena such as gate fringing effect, electron velocity overshoot, and short channel tunneling. Short channel tunneling was suggested experimentally for the first time to explain the degradation of transistor performance, overriding an enhancement due to electron velocity overshoot for a gate length smaller than the average inelastic mean free path of an electron.

  2. 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.

  3. 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.

  4. High-speed GaAs metal gate semiconductor field effect transistor structure grown on a composite Ge/GexSi1-x/Si substrate

    NASA Astrophysics Data System (ADS)

    Luo, Guang-Li; Hsieh, Yen-Chang; Chang, Edward Yi; Pilkuhn, M. H.; Chien, Chao-Hsin; Yang, Tsung-Hsi; Cheng, Chao-Ching; Chang, Chun-Yen

    2007-04-01

    In this study we used a low-pressure metal organic vapor phase epitaxy method to investigate the growth of GaAs metal gate semiconductor field effect transistor (MESFET) structures on a Si substrate. The buffer layer between the Si substrate and the grown GaAs epitaxial layers was a composite Ge/Si0.05Ge0.95/Si0.1Ge0.9 metamorphic layer. We used transmission electron microscopy to observe the microstructures formed in the grown GaAs/Ge/SixGe1-x/Si material and atomic force microscopy to analyze the surface morphology and the formation of antiphase domains in the GaAs epitaxial layers. The measured Hall electron mobility in the channel layer of a MESFET structure grown on a 6° misoriented Si substrate was 2015 cm2 V-1 s-1 with a carrier concentration of 5.0×1017 cm-3. The MESFET device fabricated on this sample exhibited good current-voltage characteristics.

  5. Impact of Parasitic Bipolar Effect on Single-Event Upset in p-Type Metal-Oxide-Semiconductor Field Effect Transistor with Embedded SiGe

    NASA Astrophysics Data System (ADS)

    Kato, Takashi; Uemura, Taiki; Mori, Hiroko; Ikeda, Yoshihiro; Suzuki, Kaina; Satoh, Shigeo; Matsuyama, Hideya

    2013-04-01

    Accelerated neutron tests for soft error rate (SER) are carried out using unbalanced feedback-loop circuits fabricated by Si and embedded SiGe (eSiGe) processes. The contribution of the p-type metal-oxide-semiconductor field effect transistor (PMOS) to total SER is shown to substantially decrease in the eSiGe process. The characteristics of parasitic bipolar transistors in PMOSs with and without eSiGe are investigated using technology computer-aided design (TCAD) simulations. We find that the narrow band gap of SiGe causes an increase in the rate of electron flow from the well region (Si) to the source region (SiGe), leading to a decrease in the current gain of the parasitic bipolar transistor in PMOS with eSiGe. Our results indicate that eSiGe can be attributed to the suppression of the parasitic bipolar effect, resulting in a reduced contribution of PMOS to SER.

  6. 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.

  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. Fabrication of InAlAs/InGaAsSb/InGaAs double heterojunction bipolar transistors

    SciTech Connect

    Lo, C. F.; Ren, F.; Chang, C. Y.; Pearton, S. J.; Chen, Shu-han; Chyi, Jen-inn; Wang, Sheng-yu; Kravchenko, Ivan I

    2011-01-01

    A trilevel resist system was employed to fabricate self-aligned, submicron emitter finger In0.52Al0.48As/ In0.42Ga0.58As0.77Sb0.23 / In0.53Ga0.47As double heterojunction bipolar transistors DHBTs. Selective wet-etchants were used to define the emitter fingers and to form an InGaAs guard-ring around the emitter fingers. Due to the low energy bandgap of the InGaAsSb base layer and type II base-collector junction, a low turn-on voltage of 0.38 V at 1 A/cm2 and a high dc current gain of 123.8 for a DHBT with a 0.658.65 m2 emitter area were obtained. A unity gain cutoff frequency fT of 260 GHz and a maximum oscillation frequency fmax of 485 GHz at JC =302 kA/cm2 were achieved.

  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 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.

  11. 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

  12. 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).

  13. Passivation of InGaAs surfaces and InGaAs/InP heterojunction bipolar transistors by sulfur treatment

    NASA Astrophysics Data System (ADS)

    Driad, R.; Lu, Z. H.; Charbonneau, S.; McKinnon, W. R.; Laframboise, S.; Poole, P. J.; McAlister, S. P.

    1998-08-01

    The surface properties of InGaAs(100) after ex situ treatment with (NH4)2S solution were investigated by photoluminescence (PL) and high-energy resolution x-ray photoelectron spectroscopy. The As 3d, Ga2p3/2, and In3d5/2 core level studies show that the surface is free of native oxides and is terminated by S after treatment. A dramatic increase (˜40 times) in the PL efficiency was observed on undoped InGaAs(100) surfaces after sulfur passivation. This S treatment has also been applied to the passivation of the extrinsic base of InGaAs/InP heterojunction bipolar transistors (HBTs). The effectiveness of the sulfur passivation treatment was confirmed by the resulting devices which exhibited dc current gain values of up to 200 at very low collector currents (nA). Further, the sulfur passivated HBTs do not show any dependence on the perimeter-to-area (P/A) ratio of the emitter junction which is of interest for high frequency characteristics while maintaining high current gain.

  14. 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

  15. 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

  16. A Base-Emitter Self-Aligned Multi-Finger Si1-xGex/Si Power Heterojunction Bipolar Transistor

    NASA Astrophysics Data System (ADS)

    Xue, Chun-Lai; Yao, Fei; Shi, Wen-Hua; Cheng, Bu-Wen; Wang, Hong-Jie; Yu, Jin-Zhong; Wang, Qi-Ming

    2007-07-01

    With a crystal orientation dependent on the etch rate of Si in KOH-based solution, a base-emitter self-aligned large-area multi-finger configuration power SiGe heterojunction bipolar transistor (HBT) device (with an emitter area of about 880 μm2) is fabricated with 2 μm double-mesa technology. The maximum dc current gain is 226.1. The collector-emitter junction breakdown voltage BVCEO is 10 V and the collector-base junction breakdown voltage BVCBO is 16 V with collector doping concentration of 1×1017 cm-3 and thickness of 400 nm. The device exhibited a maximum oscillation frequency fmax of 35.5 GHz and a cut-off frequency fT of 24.9 GHz at a dc bias point of IC = 70 mA and the voltage between collector and emitter is VCE = 3 V. Load pull measurements in class-A operation of the SiGe HBT are performed at 1.9 GHz with input power ranging from 0 dBm to 21 dBm. A maximum output power of 29.9 dBm (about 977 mW) is obtained at an input power of 18.5 dBm with a gain of 11.47 dB. Compared to a non-self-aligned SiGe HBT with the same heterostructure and process, fmax and fT are improved by about 83.9% and 38.3%, respectively.

  17. 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.

  18. 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.

  19. Carbon doping in AlGaAs for AlGaAs/GaAs graded-base heterojunction bipolar transistor by flow-rate modulation epitaxy

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi; Makimoto, Toshiki

    1991-06-01

    This letter investigates carbon doping in AlGaAs using flow-rate modulation epitaxy (FME). The tendency of hole concentration increasing with Al composition is explained by the thermal decomposition of trimethylaluminum molecules on the substrate surface. The highest hole concentration obtained is 3×1020 cm-3 in Al0.4Ga0.6As layers. An AlGaAs/GaAs heterojunction bipolar transistor with an FME-grown compositionally graded carbon-doped base layer was fabricated for the first time. It exhibits a current gain of 25 with 2×1019 cm-3 base doping.

  20. 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.

  1. Evolution of the MOS transistor - From conception to VLSI

    NASA Astrophysics Data System (ADS)

    Sah, Chih-Tang

    1988-10-01

    Historical developments of the MOSFET during the last 60 years are reviewed, from the 1928 patent disclosures of the field-effect conductivity modulation concept and the semiconductor triode structures proposed by Lilienfeld to the 1947 Shockley-originated efforts which led to the laboratory demonstration of the modern silicon MOSFET in 1960. A survey is then made of the milestones of the past 30 years leading to the latest submicron silicon logic CMOS and BICMOS (bipolar-junction transistor CMOS combined) arrays and the three-dimensional and ferroelectric extensions of Dennard's one-transistor DRAM cell. The status of the submicron lithographic technologies is summarized. Future trends of memory cell density and logic gate speed are projected. Comparisons of the switching speed of the silicon MOSFET with that of silicon bipolar and GaAs FETs are reviewed.

  2. Vertical electron transistor (VET) in GaAs with a heterojunction (AlGaAs-GaAs) cathode

    NASA Astrophysics Data System (ADS)

    Mishra, U.; Maki, P. A.; Wendt, J. R.; Schaff, W.; Kohn, E.; Eastman, L. F.

    1984-02-01

    The successful fabrication of submicrometer channel length (0.75 micron) and gate length (0.15 micron) vertical electron transistors with AlGaAs cathodes is reported. Lack of electron velocity enhancement has been proposed to be due to high operating channel temperatures, and low temperature measurements were hindered by carrier freeze-out.

  3. Investigation on phonon scattering in a GaAs nanowire field effect transistor using the non-equilibrium Green's function formalism

    SciTech Connect

    Price, A. Martinez, A.

    2015-04-28

    Using quantum transport simulations, the impact of electron-phonon scattering on the transfer characteristic of a gate-all-around nanowire (GaAs) field effect transistor (NWFET) has been thoroughly investigated. The Non-Equilibrium Green's Function formalism in the effective mass approximation using a decoupled mode decomposition has been deployed. NWFETs of different dimensions have been considered, and scattering mechanisms including acoustic, optical and polar optical phonons have been included. The effective masses were extracted from tight binding simulations. High and low drain bias have been considered. We found substantial source to drain tunnelling current and significant impact of phonon scattering on the performance of the NWFET. At low drain bias, for a 2.2 × 2.2 nm{sup 2} cross-section transistor, scattering caused a 72%, 77%, and 81% decrease in the on-current for a 6 nm, 10 nm, and 20 nm channel length, respectively. This reduction in the current due to scattering is influenced by the increase in the tunnelling current. We include the percentage tunnelling for each valley at low and high drain bias. It was also found that the strong quantisation caused the relative position of the valleys to vary with the cross-section. This had a large effect on the overall tunnelling current. The phonon-limited mobility was also calculated, finding a mobility of 950 cm{sup 2}/V s at an inversion charge density of 10{sup 12 }cm{sup −2} for a 4.2 × 4.2 nm{sup 2} cross-section device.

  4. 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.

  5. 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.

  6. Fabrication of InAs/AlSb/GaSb heterojunction bipolar transistors on Al2O3 substrates by wafer bonding

    NASA Astrophysics Data System (ADS)

    Moran, P. D.; Chow, D.; Hunter, A.; Kuech, T. F.

    2001-04-01

    High-frequency integrated circuit applications of GaSb-based materials are hampered by the lack of a suitable lattice-matched insulating substrate. Wafer bonding was used to fabricate InAs/AlSb/GaSb-based heterojunction bipolar transistors (HBTs) on an insulating sapphire substrate through a low temperature bonding process that results in a high bond strength and permitted the mechanical and chemomechanical removal of the initial GaSb substrate. The use of selective etches allows for the retention of the epitaxial device layers over virtually the entire wafer area. Minimal degradation of the transferred layers occurred in the bonding and substrate removal process. The resulting transferred structures were fabricated into functional HBTs exhibiting a dc current gain of ˜5.

  7. 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.

    2000-01-11

    The authors have demonstrated a functional MOCVD-grown AlGaAs/InGaAsN/GaAsPnP DHBT that is lattice matched to GaAs and has a peak current gain ({beta}) 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, 0.25 V lower than in a comparable Pnp AlGaAs/GaAs HBT. The BV{sub CEO} is 12 V, consistent with its GaAs collector thickness and doping level.

  8. Boron, bismuth co-doping of gallium arsenide and other compounds for photonic and heterojunction bipolar transistor devices

    DOEpatents

    Mascarenhas, Angelo

    2015-07-07

    Isoelectronic co-doping of semiconductor compounds and alloys with acceptors and deep donors is sued to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. For example, Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, B and Bi, to customize solar cells, and other semiconductor devices. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  9. Bipolar trends

    SciTech Connect

    Ning, T.H.; Tang, D.D.

    1986-12-01

    The development of bipolar technology in recent years is reviewed, and trends for future development are projected. The developments clearly point to three salient features of today's advanced bipolar transistors, namely i) self-aligned structure, ii) deep-trench isolation, and iii) polysilicon emitter contact. Both i) and ii) allow advanced bipolar devices to have much higher circuit density and lower power-delay product than without these features. The polysilicon emitter contact allows bipolar devices to be scaled down vertically without suffering from problems of insufficient current gain or low emitter-collector punchthrough voltage. It is clear that while progress will continue in scaling the familiar high-speed ECL logic and memory, the integration level of these very high-speed chips is severely limited by the accompanied power dissipation. One seemingly promising and yet relatively unexplored direction is to increase the integration level by taking advantage of circuits with much lower power-delay product than ECL, such as NTL, TTL, CML, and MTL to improve the functional throughput. The technology challenges as well as the potential of submicrometer bipolar technology are also discussed.

  10. Flow-rate modulation epitaxy of GaAs and AlGaAs

    NASA Astrophysics Data System (ADS)

    Kobayashi, Naoki; Makimoto, Toshiki; Yamauchi, Yoshiharu; Horikoshi, Yoshiji

    1989-07-01

    Flow-rate modulation epitaxy (FME) is a new epitaxial growth method which can produce a very flat heterointerface and a sharp doping profile. This paper describes FME growth conditions and electrical and optical properties of FME-grown GaAs, AlGaAs layers, and GaAs/AlGaAs single-quantum-well heterostructures. FME can reduce growth temperatures without deteriorating the crystalline quality and can produce flatter heterointerfaces than the metalorganic chemical vapor deposition method. The catalytic decomposition of silane on the Ga atomic surface efficiently dopes silicon into GaAs and AlGaAs with sharp profiles. For p-type doping, trimethyl metalorganic sources produce carbon atomic layer doping with no memory effect and a low diffusion coefficient of carbon. Experiments using FME to grow modulation doped heterostructures and heterostructure bipolar transistors prove FME to be a promising method of producing III-V semiconductor devices with thin-layered structures.

  11. Fabrication and Characterization of Self-aligned InAlAs/InGaAsSb/InGaAs Double Heterojunction Bipolar Transistors

    SciTech Connect

    Lo, C. F.; Chang, C. Y.; Chen, Shu-han; Wang, Sheng-yu; Chyi, Jen-inn; Kravchenko, Ivan I; Pearton, S. J.; Ren, F.

    2011-01-01

    A trilevel resist system was employed to fabricate self-aligned, submicron emitter finger In0.52Al0.48As/In0.42Ga0.58As0.77Sb0.23/ In0.53Ga0.47As double heterojunction bipolar transistors (DHBTs). Selective wet-etchants were used to define the emitter fingers and to form an InGaAs guard-ring around the emitter fingers. Due to the low energy bandgap of the InGaAsSb base layer and type II base-collector junction, a low turn-on voltage of 0.38 V at 1 A/cm2 and a high dc current gain of 123.8 for a DHBT with a 0.65 8.65 m2 emitter area were obtained. A unity gain cut-off frequency (fT) of 260 GHz and a maximum oscillation frequency (fmax) of 485 GHz at JC = 302 kA/cm2 were achieved.

  12. Fabrication of InP-based Optoelectronic Integrated Circuit (OEIC) Photoreceivers Using Shared Layer Integration of Heterojunction Bipolar Transistors and Refracting-Facet Photodiodes

    NASA Astrophysics Data System (ADS)

    Lee, Bangkeun; Yang, Kyounghoon

    2004-04-01

    InP-based monolithic photoreceivers have been fabricated using a shared layer integration scheme of refracting-facet photodiodes (RFPDs) and heterojunction bipolar transistors (HBTs). An HBT was fabricated using a self-aligned emitter-base process and nonalloyed metallization of the emitter, base and collector ohmic contacts. The fabricated 2× 10 μm2 emitter HBT exhibited a maximum current gain of 40. The maximum cutoff frequencies of this HBT were measured to be fT=79 GHz and fmax=143 GHz at IC=19 mA and VCE=1.5 V, respectively. An RFPD was fabricated using the base-collector junction layers of the HBT based on the selective wet chemical etching characteristics of InP and InGaAs layers. The fabricated RFPD showed a 37% increased optical responsivity of 0.48 A/W compared to the fabricated surface-illuminated photodiode using the same photoreceiver epitaxial layer. The full width at half maximum (FWHM) of the fabricated RFPD was determined to be 24 ps using the standard 50 Ω system load. The fabricated three-stage transimpedance amplifier (TIA) showed a transimpedance gain of 46 dBΩ and a -3 dB bandwidth of 12 GHz. The fabricated monolithic RFPD/HBT photoreceiver has demonstrated a -3 dB optical bandwidth of 6.9 GHz.

  13. In situ arsenic-doped polycrystalline silicon as a low thermal budget emitter contact for Si/Si1 - xGex heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    King, C. A.; Johnson, R. W.; Pinto, M. R.; Luftman, H. S.; Munanka, J.

    1996-01-01

    A low thermal budget emitter contact with low specific contact resistivity (ρc) with the absence of transient enhanced diffusion (TED) effects is essential to fabricate integratable high performance Si/SiGe heterojunction bipolar transistors (HBTs). We report the use of in situ As-doped polycrystalline silicon (polysilicon) from a low base pressure rapid thermal episystem for this purpose and find that it meets all the requirements. We used secondary ion mass spectrometry to find that 18 nm, heavily B-doped layers remain intact after implantation into the surface polysilicon and annealing at 800 °C for 40 s. Similar samples without the surface polylayer displayed extreme broadening of B profile. Kelvin crossbridge resistors together with 2D device simulations revealed that ρc is an extremely low value of 1.2×10-8 Ω cm2 in as-deposited material. Fabrication of simple 30×30 μm2 mesa isolated HBT devices showed IC to be more than two decades higher in devices with only an in situ As-doped polyemitter compared with devices that incorporated a surface implant into the single crystal portion of the emitter before polysilicon deposition. These results demonstrate that this doped polycrystalline silicon material is an excellent choice for emitter contacts to HBT devices.

  14. 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.

  15. Bipolar Disorder

    MedlinePlus

    ... Prevention (2 items) Treatments (4 items) Publications About Bipolar Disorder Bipolar Disorder A brochure on bipolar disorder that ... En Espaol Continue Reading Share More Information About Bipolar Disorder Bipolar Disorder Page Information about Bipolar Disorder from ...

  16. Bipolar Disorder

    MedlinePlus

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

  17. Magnetoresistance method to determine GaAs and Al(x)Ga(1-x)As mobilities in Al(x)Ga(1-x)As/GaAs modulation-doped field-effect transistor structures

    NASA Astrophysics Data System (ADS)

    Look, D. C.; Norris, G. B.; Kopp, W.; Henderson, T.; Morkoc, H.

    1985-08-01

    Charge carrier mobilities are conveniently measured in simple, homostructure field-effect transistors (FET's) by means of the geometric magnetoresistance (GMR) technique. Heterostructure FET's, however, are more complicated because of multiple conducting regions, as well as multiple conducting bands within a given region. A multilayer GMR mobility model is applied to a frequently used heterostructure FET design, namely, the Al0.3Ga0.7As/GaAs modulation-doped FET (MODFET). By analyzing the results at different magnetic fields, the contributions of the various GaAs subbands and the Al0.3Ga0.7As conduction band can be separated. In the particular MODFET structure studied here, the lowest GaAs subband mobility ranges from 5700 sq cm/Vs at threshold to 6900 sq cm/Vs at saturation, while the Al0.3Ga0.7As mobility is about 500 sq cm/Vs. This is the first time that the various mobilities in MODFET structures have been separately measured.

  18. Probing plasma-surface interactions with the transmission electron microscope or the Si-collector interface of the plasma bipolar junction transistor

    NASA Astrophysics Data System (ADS)

    Houlahan, T. J., Jr.; Li, B.; Xu, Z.; Jiang, J.; Liu, G. L.; Ruzic, D. N.; Eden, J. G.

    2013-11-01

    Two platforms developed to probe the plasma-solid interface are briefly reviewed here. A sensitive diagnostic of the interaction between a low-temperature plasma and a silicon surface is provided by the plasma bipolar junction transistor (PBJT) in which e--h+ (semiconductor) and e--ion (gas phase) plasmas are separated by a nanoscale potential barrier but coupled by a strong (>1 V µm-1) electric field. Electrical properties of the Si base-collector plasma interface are controlled by the bias applied to the PBJT emitter-base junction, as well as the morphology and electronic structure of the base surface facing the collector plasma. Recent experiments are described in which the Si(100) surface of the PBJT base is transformed into black Si, a nanostructured array comprising ˜3 × 109 nanocones. Each cone is ˜100 nm in height and has a radius of curvature at its tip of <1 nm. Altering the base surface so as to intentionally enhance field emission results in burst-mode operation of the PBJT in which the collector current oscillates as a result of the periodic contraction (or collapse) and revival of the plasma sheath. The observed oscillation frequencies (3.6-13 kHz) are consistent with the transit time of ions across the sheath. Integration of a microplasma device with a transmission electron microscope has also been realized recently (Tai et al 2013 Sci. Rep. 3 1325). This diagnostic tool allows plasma-surface interactions to be observed in real-time with a spatial resolution <100 nm. Although initial experiments concerned the growth of Au islands in a dc plasma, the extension of this probe to nanostructured and spatially modulated surfaces is proposed.

  19. 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 ˜ 3.5, at VCE = 20V and IB = 10mA) were obtained with an HBT formed via fusion at 600°C for 1 hour, with an optimized base-collector design. This was quite an improvement, as compared to an HBT with a simpler base-collector structure, also fused at 600°C for 1 hour (IC ˜ 0.83 kA/cm2 and beta ˜ 0.89, at VCE = 20V and IB = 10mA). Fused AlGaAs-GaAs-GaAs HBTs were compared to fused AlGaAs-GaAs-GaN HBTs, demonstrating that the use of a wider bandgap collector (Eg,GaN > Eg,GaAs) did indeed improve HBT performance at high applied voltages, as desired for high-power applications.

  20. 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 structures and map out the spatial sensitivities using the Sandia Focused Heavy Ion Microprobe Facility s Ion Beam Induced Charge Collection (IBICC) technique. Combining the two data sets offers insights into the charge collection mechanisms responsible for circuit level response and provides the first insights into the SEE characteristics of this latest version of IBM s commercial SiGe process.

  1. Bipolar Disorder

    MedlinePlus

    ... Treatments and Therapies Join a Study Learn More Bipolar Disorder Definition Bipolar disorder, also known as manic- ... known as major depressive disorder with mixed features. Bipolar Disorder and Other Illnesses Some bipolar disorder symptoms ...

  2. Application of double camel-like gate structures for a GaAs field-effect transistor with extremely high potential barrier height and gate turn-on voltage

    NASA Astrophysics Data System (ADS)

    Tsai, Jung-Hui; Chiu, Shao-Yen; Lour, Wen-Shiung; Guo, Der-Feng; Liu, Wen-Chau

    2006-08-01

    In this paper, extremely high potential barrier height and gate turn-on voltage in an n+/p+/n+/p+/n GaAs field-effect transistor employing double camel-like gate structures are demonstrated. The gate potential barrier height of the double camel-like gate is substantially enhanced by the addition of another n+/p+ layer in the gate region, as compared with the conventional n+/p+/n single camel-like gate structure. The influence of gate structure layers on the depletion depth, potential barrier height, transconductance and gate voltage swing are addressed. Experimental results show that a relatively high gate turn-on voltage up to +4.9 V is realized because two reverse-biased junctions of the double camel-like gate structures absorb part of the positive gate voltage. In addition, an extremely broad gate voltage swing greater than 4.6 V with the transconductance above 100 mS mm-1 is observed. These results indicate that the studied device is suitable for linear and signal amplifiers and inverter circuit applications.

  3. Charge separation for bipolar transistors

    SciTech Connect

    Kosier, S.L.; Schrimpf, R.D.; Wei, A.; Chai, F. ); Nowlin, R.N. ); Fleetwood, D.M. ); DeLaus, M. ); Pease, R.L. ); Combs, W.E. )

    1993-12-01

    The role of net positive oxide trapped charge and surface recombination velocity on excess base current in BJTs is identified. Although the interaction of these two radiation-induced defects is physically complex, simple approaches for estimating these quantities from measured BJT characteristics are presented. The oxide charge is estimated using a transition voltage in the plot of excess base current vs. emitter bias. Two approaches for quantifying die effects of surface recombination velocity are described; the first measures surface recombination directly using a gated diode. The second estimates its effects using an intercept current that is easily obtained from the BJT itself. The results are compared to two-dimensional simulations and measurements made on test structures. The techniques are simple to implement and provide insight into the mechanisms and magnitudes of the radiation-induced damage in BJTs.

  4. Low phase noise GaAs HBT VCO in Ka-band

    NASA Astrophysics Data System (ADS)

    Ting, Yan; Yuming, Zhang; Hongliang, L; Yimen, Zhang; Yue, Wu; Yifeng, Liu

    2015-02-01

    Design and fabrication of a Ka-band voltage-controlled oscillator (VCO) using commercially available 1-?m GaAs heterojunction bipolar transistor technology is presented. A fully differential common-emitter configuration with a symmetric capacitance with a symmetric inductance tank structure is employed to reduce the phase noise of the VCO, and a novel ?-feedback network is applied to compensate for the 180 phase shift. The on-wafer test shows that the VCO exhibits a phase noise of -96.47 dBc/Hz at a 1 MHz offset and presents a tuning range from 28.312 to 28.695 GHz. The overall dc current consumption of the VCO is 18 mA with a supply voltage of -6 V The chip area of the VCO is 0.7 0.7 mm2.

  5. Characterization of InP/InGaAs Heterojunction Bipolar Transistors with Carbon-Doped Base Layers Grown by Metal-Organic Chemical Vapor Deposition and Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Kuroda, Naotaka; Fujihara, Akira; Ikenaga, Yoshifumi; Ishizaki, Haruya; Tanaka, Shinichi

    2005-09-01

    We characterized InP/InGaAs heterojunction bipolar transistors (HBTs) with carbon-doped InGaAs base layers grown by metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). Since HBTs grown using these techniques require different processing steps, resulting in different types of process-related damage, we analyzed the bulk and periphery components of DC characteristics to clarify the effects of the crystal growth and process techniques on device characteristics separately. The MBE-grown HBTs were found to have an advantage over the MOCVD-grown HBTs, because they do not require harmful high-temperature annealing during processing steps. On the other hand, it was also shown that the MOCVD-grown HBTs have a significantly lower base recombination rate than the MBE-grown HBTs, making MOCVD a suitable method of growing InP HBTs that do not require annealing, such as that with a GaAsSb base.

  6. 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.

  7. GaAs optoelectronic neuron arrays.

    PubMed

    Lin, S; Grot, A; Luo, J; Psaltis, D

    1993-03-10

    A simple optoelectronic circuit integrated monolithically in GaAs to implement sigmoidal neuron responses is presented. The circuit integrates a light-emitting diode with one or two transistors and one or two photodetectors. The design considerations for building arrays with densities of up to 10(4) cm(-2) are discussed. PMID:20820261

  8. GaAs optoelectronic neuron arrays

    NASA Technical Reports Server (NTRS)

    Lin, Steven; Grot, Annette; Luo, Jiafu; Psaltis, Demetri

    1993-01-01

    A simple optoelectronic circuit integrated monolithically in GaAs to implement sigmoidal neuron responses is presented. The circuit integrates a light-emitting diode with one or two transistors and one or two photodetectors. The design considerations for building arrays with densities of up to 10,000/sq cm are discussed.

  9. 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.

  10. Impact ionization in GaAs metal-semiconductor field-effect transistors with a lightly doped drain structure and an Al0.2Ga0.8As/GaAs heterobuffer layer

    NASA Astrophysics Data System (ADS)

    Haruyama, Junzi; Katano, Humiaki

    1995-04-01

    Kink effects (abrupt increases in drain current) were observed with an abrupt increase of gate current (IG), substrate current (Isub), substrate potential (Vsub), and photoemission intensity (Iphoto) in GaAs metal-semiconductor field-effect transistors (MESFETs) with a lightly doped drain (LDD) structure and an Al0.2Ga0.8As/GaAs heterobuffer layer. The kink drain voltage (VKD) increases as substrate temperature increases. Since impact ionization has a negative coefficient for increase of temperature, the increase of VKD indicates that impact ionization occurs at VKD. VKD also increases as VG becomes more negative and as the ratio of the dose of the silicon ions is reduced in the LDD region. Thus it is confirmed that impact ionization occurs at the drain side along the channel current path because those changes of VG and dose ratio reduce the electric field at the drain-side channel. In addition, impact ionization coefficients were calculated from IG and Isub based on the method proposed by Hui et al. Both the coefficients were exponentially proportional to the negative inverse of the electric field, although the magnitude of Isub was approximately 250× greater than that of IG. On the other hand, it was found that Iphoto was linearly proportional to Vsub. It suggests that Iphoto depends on the number of holes which overflow the n-GaAs channel/i-GaAs buffer interface potential barrier into the channel layer. These behaviors of IG, Isub, Iphoto, and Vsub are attributed to this FET structure which has a thin channel layer with a high donor density and a heterobuffer layer.

  11. Characteristics enhancement of a GaAs based heterostructure field-effect transistor with an electrophoretic deposition (EPD) surface treated gate structure

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Chia; Chen, Huey-Ing; Liu, I.-Ping; Chou, Po-Cheng; Liou, Jian-Kai; Tsai, Yu-Ting; Liu, Wen-Chau

    2015-06-01

    A Pt/AlGaAs/InGaAs/GaAs heterostructure field-effect transistor (HFET), prepared by an electrophoretic deposition (EPD) approach on gate Schottky contact region, is fabricated and studied. The EPD-based Pt-gates with three different molar ratios (ω0) are examined by scanning electron microscopy (SEM) image. Good Pt-gate coverage with effective reduction of thermal-induced defects at Pt/AlGaAs interface is achieved through a low temperature EPD approach. Experimentally, for a gate dimension of 1 μm × 100 μm, a lower gate current of 1.9 × 10-2 mA/mm, a higher turn-on voltage of 0.85 V, a higher maximum drain saturation current of 319.3 mA/mm, and a higher maximum extrinsic transconductance of 146.8 mS/mm are obtained for an EPD-based HFET at 300 K. Moreover, comparable microwave characteristics of an EPD-based HFET are demonstrated at different temperature ambiences. Therefore, based on the improved DC performance and inherent benefits of low cost, simple apparatus, flexible deposition on varied substrates, and adjustable alloy grain size, the proposed EPD approach shows the promise to fabricate high-performance electronic devices.

  12. Rapid thermal anneal in InP, GaAs and GaAs/GaAlAs

    NASA Astrophysics Data System (ADS)

    Descouts, B.; Duhamel, N.; Godefroy, S.; Krauz, P.

    Ion implantation in semiconductors provides a doping technique with several advantages over more conventional doping methods and is now extensively used for device applications, e.g. field effect transistors (MESFET GaAs, MIS (InP), GaAs/GaAlAs heterojunction bipolar transistors (HBT). Because of the lattice disorder produced by the implantation, the dopant must be made electrically active by a postimplant anneal. As the device performances are very dependent on its electrical characteristics, the anneal is a very important stage of the process. Rapid anneal is known to provide less exodiffusion and less induffusion of impurities compared to conventional furnace anneal, so this technique has been used in this work to activate an n-type dopant (Si) in InP and a p-type dopant (Mg) in GaAs and GaAs/GaAIAs. These two ions have been chosen to realize implanted MIS InP and the base contacts for GaAs/GaAlAs HBTs. The experimental conditions to obtain the maximum electrical activity in these two cases will be detailed. For example, although we have not been able to obtain a flat profile in Mg + implanted GaAs/GaAlAs heterostructure by conventional thermal anneal, rapid thermal anneal gives a flat hole profile over a depth of 0.5 μm with a concentration of 1 x 10 19 cm -3.

  13. Gallium Arsenide Transistors: Realization Through a Molecularly Designed Insulator

    NASA Astrophysics Data System (ADS)

    Jenkins, Phillip P.; Macinnes, Andrew N.; Tabib-Azar, Massood; Barron, Andrew R.

    1994-03-01

    A GaAs-based transistor, analogous to commercial silicon devices, has been fabricated with vapor-deposited cubic GaS as the insulator material. The n-channel, depletion mode, GaAs field-effect transistor shows, in addition to classical transistor characteristics, a channel mobility of 4665.6 square centimeters per volt per second, an interfacial trap density of 1011 per electron volt per square centimeter, and a transconductance of 7 millisiemens for a 5-micrometer gate length at a gate voltage of 8 volts. Furthermore, the GaAs transistor shows an on-to-off resistance ratio comparable to that of commercial devices.

  14. A 32-bit RISC implemented in enhancement-mode JFET GaAs

    SciTech Connect

    Rasset, T.L.; Niederland, R.A.; Lane, J.H.; Geideman, W.A.

    1986-10-01

    Recently, considerable attention has been focused on gallium arsenide (GaAs) semiconductor process technologies for very high speed digital integrated circuits. This attention is motivated primarily by the ability of GaAs transistors to switch much faster with lower power consumption than transistors in silicon technologies. Soon to be available with higher switching speed and more transistors than the fastest silicon technology (emitter-coupled logic), GaAs digital ICs will be a boon to developers of super-computers and specialized high-speed microprocessors, such as digital signal processors. GaAs transistors are also much more resistant to temperature extremes and to ionizing radiation than silicon, important features for applications requiring operation in harsh environments. This does not mean that GaAs will replace silicon; rather, where the higher cost of GaAs is warranted by application requirements that only GaAs can satisfy, it will augment silicon. The high cost of GaAs chips is due mainly to the scarcity of gallium and the inferior quality and difficulty in manufacturing the gallium arsenide compound. Unlike silicon, which is very uniform and pure, GaAs has many defects and its characteristics may vary considerably from ingot to ingot, affecting yield. Also, the wafers have a tendency to break during processing.

  15. Bipolar Disorder

    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 ...

  16. Bipolar disorder

    MedlinePlus

    ... www.ncbi.nlm.nih.gov/pubmed/23663953 . Perlis RH, Ostacher MJ. Bipolar disorder. In: Stern TA, Fava ... Philadelphia, PA: Elsevier Mosby; 2016:chap 30. Perlis RH. Bipolar disorder. In: Stern TA, Rosenbaum JF, Fava ...

  17. Bipolar Disorder

    MedlinePlus

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

  18. Bipolar Disorder

    MedlinePlus

    ... Sledding, Skiing, Snowboarding, Skating Crushes What's a Booger? Bipolar Disorder KidsHealth > For Kids > Bipolar Disorder Print A A A Text Size What's ... it can be like for people who have bipolar disorder, a serious but treatable condition that both ...

  19. Cryogenic measurements of aerojet GaAs n-JFETs

    NASA Technical Reports Server (NTRS)

    Goebel, John H.; Weber, Theodore T.

    1993-01-01

    The spectral noise characteristics of Aerojet gallium arsenide (GaAs) junction field effect transistors (JFET's) have been investigated down to liquid-helium temperatures. Noise characterization was performed with the field effect transistor (FET) in the floating-gate mode, in the grounded-gate mode to determine the lowest noise readings possible, and with an extrinsic silicon photodetector at various detector bias voltages to determine optimum operating conditions. The measurements indicate that the Aerojet GaAs JFET is a quiet and stable device at liquid helium temperatures. Hence, it can be considered a readout line driver or infrared detector preamplifier as well as a host of other cryogenic applications. Its noise performance is superior to silicon (Si) metal oxide semiconductor field effect transistor (MOSFET's) operating at liquid helium temperatures, and is equal to the best Si n channel junction field effect transistor (n-JFET's) operating at 300 K.

  20. Calculation of the base current components and determination of their relative importance in AlGaAs/GaAs and InAlAs/InGaAs heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Liou, J. J.

    1991-03-01

    The base current density JB is an important parameter in determining the common-emitter current gain β of heterojunction bipolar transistors (HBTs). To develop an analytical β model with which a circuit designer can quickly estimate the current gain in a HBT, it is also important to identify the dominant component of JB so that minimum computations are required. Based on heterojunction device physics, the three components of JB have been calculated, namely, the recombination current density in the base JRB, the recombination current density in the space-charge region JSCR, and the injection current density from the base to the emitter JRE, and have determined their relative importance to JB for abrupt AlGaAs/GaAs and InAlAs/InGaAs HBTs under normal bias conditions. It is found that relative importance of the three current densities depends strongly on the bias condition, strongly on the density of states NtI at the emitter-base heterointerface, but weakly on the density of trapping states NtB in the bulk of the emitter-base space-charge region. Also, JB is relatively insensitive to device makeup such as doping concentration and layer thickness. Depending on NtI and on the bias condition, either JSCR or JRE is the dominant component for AlGaAs/GaAs HBTs and either JSCR or JRB is the dominant component for InAlAs/InGaAs HBTs. Effects of base and heterojunction grading on the present findings are also addressed.

  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. The 20 GHz power GaAs FET development

    NASA Technical Reports Server (NTRS)

    Crandell, M.

    1986-01-01

    The development of power Field Effect Transistors (FET) operating in the 20 GHz frequency band is described. The major efforts include GaAs FET device development (both 1 W and 2 W devices), and the development of an amplifier module using these devices.

  3. Developing Low-Noise GaAs JFETs For Cryogenic Operation

    NASA Technical Reports Server (NTRS)

    Cunningham, Thomas J.

    1995-01-01

    Report discusses aspects of effort to develop low-noise, low-gate-leakage gallium arsenide-based junction field-effect transistors (JFETs) for operation at temperature of about 4 K as readout amplifiers and multiplexing devices for infrared-imaging devices. Transistors needed to replace silicon transistors, relatively noisy at 4 K. Report briefly discusses basic physical principles of JFETs and describes continuing process of optimization of designs of GaAs JFETs for cryogenic operation.

  4. 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…

  5. 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

  6. 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.

  7. Examination of temperature effects on gate-to-drain avalanche breakdown in GaAs MESFETS (metal-semiconductor field effect transistors) by measuring light emission under rf drive. Master's thesis

    SciTech Connect

    Robb, R.E.

    1987-12-01

    This investigation examines temperature effects on avalanche breakdown in GaAs MESFETs to determine if this failure mechanism is accelerated by high-temperature life tests. The specific objective is to assess whether the accelerated life-test evaluations performed on a GaAs MESFET planned for use in future Defense Satellite Communications System (DSCS) spacecraft have adequately addressed the reliability issues concerning the gate-to-drain avalanche breakdown failure mechanism. This objective was accomplished by adapting an existing analytical model for temperature effects, and using it to predict the variation in avalanche multiplication activity with temperature. To verify this model, it was used to calculate the associated changes in light emissions over temperature which were experimentally validated on one device of the type planned for use by the DSCS program. Once validated, these models were used to evaluate the adequacy of the accelerated-temperature life tests. The results of this evaluation indicate that the the avalanche-breakdown failure mechanism is decelerated with temperature, and therefore, the effects of avalanche breakdown on the reliability of GaAs MESFETs cannot be determined by accelerated temperature life testing.

  8. An introduction GaAs microprocessor architecture for VLSI

    SciTech Connect

    Milutinovic, V.; Fura, D.; Helbig, W.

    1986-03-01

    Gallium arsenide, or GaAs, technology has recently shown rapid increases in maturity. In particular, the advances made in digital chip complexity have been enormous. This progress is especially evident in two types of chips: static rams and gate arrays. In 1983, static rams containing 1K bits were announced. One year later both a 4K-bit and a 16K-bit version were presented. Gate arrays have advanced from a 1000-gate design presented in 1984 to a 2000-gate design announced in 1985. With this enormous progress underway, it is now appropriate to consider the use of this new technology in the implementation of high-performance processors. GaAs technology generates high levels of enthusiasm primarily because of two advantages it enjoys over silicon: higher speed and greater resistance to adverse environmental conditions. GaAs gates switch faster than silicon transistor-transistor logic, or TTL, gates by nearly an order of magnitude. These switching speeds are even faster than those attained by the fastest silicon emitter-coupled logic, or ECL, but at power levels an order of magnitude lower. For this reason, GaAs is seen to have applications in computer design within several computationally intensive areas. In fact, it has been reported that the Cray-3 will contain GaAs parts. GaAs also enjoys greater resistance to radiation and temperature variations than does silicon. GaAs successfully operates in radiation levels of 10 to 100 million rads. Its operating temperature range extends from -200 to 200/sup 0/C. Consequently, GaAs has created great excitement in the military and aerospace markets.

  9. 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.

  10. 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.

  11. Types of Bipolar Disorder

    MedlinePlus

    ... Research Studies Peer Support Research WeSearchTogether Types of Bipolar Disorder There are several kinds of bipolar disorder. ... and pattern of episodes of mania and depression. Bipolar I Disorder Bipolar I is characterized by one ...

  12. Ion implanted GaAs microwave FET's

    NASA Astrophysics Data System (ADS)

    Gill, S. S.; Blockley, E. G.; Dawsey, J. R.; Foreman, B. J.; Woodward, J.; Ball, G.; Beard, S. J.; Gaskell, J. M.; Allenson, M. B.

    1988-06-01

    The combination of ion implantation and photolithographic patterning techniques was applied to the fabrication of GaAs microwave FETs to provide a large number of devices having consistently predictable dc and high frequency characteristics. To validate the accuracy and repeatability of the high frequency device parameters, an X-band microwave circuit was designed and realized. The performance of this circuit, a buffered amplifier, is very close to the design specification. The availability of a large number of reproducible, well-characterized transistors enabled work to commence on the development of a large signal model for FETs. Work in this area is also described.

  13. Carbon doping of GaAs NWs

    NASA Astrophysics Data System (ADS)

    Salehzadeh Einabad, Omid

    Nanowires (NWs) have been proposed and demonstrated as the building blocks for nanoscale electronic and photonic devices such as NW field effect transistors and NW solar cells which rely on doping and trap-free carrier transport. Controlled doping of NWs and a high degree of structure and morphology control are required for device applications. However, doping of III-V nanowires such as GaAs nanowires has not been reported extensively in the literature. Carbon is a well known p-type dopant in planar GaAs due to its low diffusivity and high solubility in bulk GaAs; however its use as an intentional dopant in NW growth has not yet been investigated. In this work we studied the carbon doping of GaAs nanowires using CBr4 as the dopant source. Gold nanoparticles (NP) at the tip ofthe NWs have been used to drive the NW growth. We show that carbon doping suppresses the migration ofthe gold NPs from the tip of the NWs. In addition, we show that the carbon doping of GaAs NWs is accompanied by an increase of the axial growth rate and decrease of the lateral growth rate ofthe NWs. Carbon-doped GaAs NWs, unlike the undoped ones which are highly tapered, are rod-like. The origin of the observed morphological changes is attributed to the carbon adsorbates on the sidewalls ofthe nanowires which suppress the lateral growth of the nanowires and increase the diffusion length of the gallium adatoms on the sidewalls. Stacking fault formation consisting of alternating regIOns of zincblende and wurtzite structures has been commonly observed in NWs grown along the (111) direction. In this work, based on transmission electron microscopy (TEM) analysis, we show that carbon doping ofGaAs NWs eliminates the stacking fault formation. Raman spectroscopy was used to investigate the effects of carbon doping on the vibrational properties of the carbon-doped GaAs nanowires. Carbon doping shows a strong impact on the intrinsic longitudinal and transverse optical (La and TO) modes of the GaAs nanowires resulting in red-shifts and broadening of these modes. In addition we observed the appearance of a forbidden mode at the low energy side of the TO mode which has been activated by the breakdown of the Raman selection rule due to disorder introduced into the crystal by carbon impurities. In addition, Raman studies, consistent with TEM results, confirm that the doped NWs are free of stacking faults with pure zincblende crystal structure. This has been confirmed by the suppression ofthe wurtzite TO mode in the doped samples.

  14. Performance analysis of undoped cylindrical gate all around (GAA) MOSFET at subthreshold regime

    NASA Astrophysics Data System (ADS)

    Jena, B.; Pradhan, K. P.; Dash, S.; Mishra, G. P.; Sahu, P. K.; Mohapatra, S. K.

    2015-09-01

    In this work the sensitivity of process parameters like channel length (L), channel thickness (tSi), and gate work function (φM) on various performance metrics of an undoped cylindrical gate all around (GAA) metal-oxide-semiconductor field effect transistor (MOSFET) are systematically analyzed. Undoped GAA MOSFET is a radical invention as it introduces a new direction for transistor scaling. In conventional MOSFET, generally the channel doping concentration is very high to provide high on-state current, but in contrary it causes random dopant fluctuation and threshold voltage variation. So, the undoped nature of GAA MOSFET solves the above complications. Hence, we have analyzed the electrical characteristics as well as the analog/RF performances of undoped GAA MOSFET through Sentaurus device simulator.

  15. New dynamic FET logic and serial memory circuits for VLSI GaAs technology

    NASA Technical Reports Server (NTRS)

    Eldin, A. G.

    1991-01-01

    The complexity of GaAs field effect transistor (FET) very large scale integration (VLSI) circuits is limited by the maximum power dissipation while the uniformity of the device parameters determines the functional yield. In this work, digital GaAs FET circuits are presented that eliminate the DC power dissipation and reduce the area to 50% of that of the conventional static circuits. Its larger tolerance to device parameter variations results in higher functional yield.

  16. Multistreamer regime of GaAs thyristor switching

    SciTech Connect

    Vainshtein, S.N.; Kilpelae, A.J.; Kostamovaara, J.T.; Myllylae, R.A.; Starobinets, S.U.; Zhilyaev, J.V. . Dept. of Electrical Engineering)

    1994-08-01

    GaAs bipolar thyristors have been used to obtain current pulses of over 100 A with rise times less than 600 ps and load resistance of approximately 0.4 [Omega]. The maximum voltage has been shown to exceeded 500 V in some cases. To interpret the experimental results a multichannel switch regime is proposed. Analysis of the experimental data suggests the possibility of a further increase in the maximum amplitude of the current pulse.

  17. 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.

  18. Performance Evaluation of Source Heterojunction Strained Channel Gate all around Nanowire Transistor

    NASA Astrophysics Data System (ADS)

    Hosseini, Reza; Fathipour, Morteza; Faez, Rahim

    A Gate All Around Nanowire Transistor (GAA NWT) which employs source heterojunction and strained channel is proposed which improves device characteristics. A quantum mechanical transport approach based on nonequilibrium Green's function (NEGF) method in the frame work of effective mass theory is employed in this analysis. We evaluate the variation of the threshold voltage, the subthreshold slope, ON and OFF state currents when channel length decreases. It is shown that the source heterojunction strained channel GAA NWT gives high performance transistors values of the scaled transconductance and ON current that are greater than conventional silicon GAA NWT. Furthermore, comparison of switching delay τd and unity current gain frequency fT of the devices shows that the performance of source heterojunction strained channel GAA NWT is better than the conventional silicon GAA NWT.

  19. GaAs Optoelectronic Integrated-Circuit Neurons

    NASA Technical Reports Server (NTRS)

    Lin, Steven H.; Kim, Jae H.; Psaltis, Demetri

    1992-01-01

    Monolithic GaAs optoelectronic integrated circuits developed for use as artificial neurons. Neural-network computer contains planar arrays of optoelectronic neurons, and variable synaptic connections between neurons effected by diffraction of light from volume hologram in photorefractive material. Basic principles of neural-network computers explained more fully in "Optoelectronic Integrated Circuits For Neural Networks" (NPO-17652). In present circuits, devices replaced by metal/semiconductor field effect transistors (MESFET's), which consume less power.

  20. Cryogenic Low Noise Amplifier with GaAs JFETs

    NASA Astrophysics Data System (ADS)

    Fujiwara, Mikio; Nagata, Hirohisa; Hibi, Yasunori; Matsuo, Hiroshi; Sasaki, Masahide

    2009-12-01

    A SONY n-type GaAs junction field effect transistor (JFET) can operate at deep cryogenic temperatures without exhibiting kink phenomena or hysteresis in its I-V characteristics. Further the GaAs JFET has small gate leakage currents(<4.6×10-19A) and a minute input capacitance (0.037 pF). Moreover, even though the gate terminal of a JFET is surrounded by high-impedance materials, the noise level does not increase and a low noise level of ˜500 nV/Hz1/2 at 1 Hz with low power dissipation (<1 μW) was achieved. We are currently developing operational amplifiers (Op-Amps) and digital modules for cryogenically cooled high-sensitivity photodetection systems. The GaAs Op-Amp with an open loop gain of 2000 at a power dissipation of 6.5 μW has been developed.

  1. 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)

  2. Selective epitaxy base transistor (SEBT)

    NASA Astrophysics Data System (ADS)

    Burghartz, J. N.; Ginsberg, B. J.; Mader, S. R.; Chen, Tze-Chiang; Harame, David L.

    1988-05-01

    A bipolar transistor using selective epitaxy for base formation in a double-play self-aligned structure is presented. The intrinsic base was formed by a selective-epitaxial deposition in place of ion implantation. Such epitaxial base processes are capable of achieving a narrow intrinsic base sheet resistance Rbi and base-emitter diffusion capacitance cbe compared to advanced ion-implanted processes. A selective epitaxial base can be simply introduced in advanced double-poly self-aligned processes compared to a nonselective epitaxial layer.

  3. 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.

  4. Design consideration of δ-doping channels for high-performance n + - GaAs / p + -InGaP/n-GaAs camel-gate field effect transistors

    NASA Astrophysics Data System (ADS)

    Tsai, Jung-Hui; Chen, Jeng-Shyan; Chu, Yu-Jui

    2005-01-01

    The influence of δ-doping channels on the performance of n +-GaAs/p +-InGaP/n-GaAs camel-gate field effect transistors is investigated by theoretical analysis and experimental results. The depleted pn junction of the camel gate and the existence of considerable conduction band discontinuity at the InGaP/GaAs heterojunction enhance the potential barrier height and the forward gate voltage. As the concentration-thickness products of the n-GaAs layer and δ-doping layer are fixed, the higher δ-doping device exhibits a higher potential barrier height, a larger drain current, and a broader gate voltage swing, whereas the transconductance is somewhat lower. For a n +=5.5×10 12 cm -2δ-doping device, the experimental result exhibits a maximum transconductance of 240 mS/mm and a gate voltage swing of 3.5 V. Consequently, the studied devices provide a good potential for large signal and linear circuit applications.

  5. Novel WSi/Au T-shaped gate GaAs metal-semiconductor field-effect-transistor fabrication process for super low-noise microwave monolithic integrated circuit amplifiers

    SciTech Connect

    Takano, H.; Hosogi, K.; Kato, T.

    1995-05-01

    A fully ion-implanted self-aligned T-shaped gate Ga As metal-semiconductor field-effect transistor (MESFET) with high frequency and extremely low-noise performance has been successfully fabricated for super low-noise microwave monolithic integrated circuit (MMIC) amplifiers. A subhalf-micrometer gate structure composed of WSi/Ti/Mo/Au is employed to reduce gate resistance effectively. This multilayer gate structure is formed by newly developed dummy SiON self-alignment technology and a photoresist planarization process. At an operating frequency of 12 GHz, a minimum noise figure of 0.87 dB with an associated gain of 10.62 dB has been obtained. Based on the novel FET process, a low-noise single-stage MMIC amplifier with an excellent low-noise figure of 1.2 dB with an associated gain of 8 dB in the 14 GHz band has been realized. This is the lowest noise figure ever reported at this frequency for low-noise MMICs based on ion-implanted self-aligned gate MESFET technology. 14 refs., 9 figs.

  6. 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.

  7. 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.

  8. Progress on GaAs cryogenic readout circuits for SISCAM

    NASA Astrophysics Data System (ADS)

    Nagata, H.; Kobayashi, J.; Matsuo, H.; Fujiwara, M.

    2006-06-01

    We are developing cryogenic readout circuits for the array of superconducting tunneling junctions (STJs) at submillimeter wavelength SISCAM (Superconductive Imaging Submillimeter-wave CAMera). A current conceptual design of SISCAM will employ a direct hybrid array system just like CMOS image sensors widely used at optical and infrared wavelength. Because of relatively large impedance of the STJ fabricated by RIKEN (~10 MΩ in a dark condition), it requires readout preamplifier with low current noise. Therefore, it is not suitable for the STJ to use a readout system by Superconductive Quantum Interferences Devices as for Transition Edge Sensor. Instead, we selected capacitive transimpedance amplifier (CTIA) using a SONY n-type GaAs Junction Field Effect Transistor (JFET). However, the CTIA has not been used as the readout of the STJ. Therefore, we measured the photocurrent of the STJ by the CTIA with Silicon JFETs and by transimpedance amplifier (TIA), which is a conventional readout for the STJ, in the same bias condition, and confirmed both results are in good agreement. Additionally, we report development of readout integrated circuits with GaAs JFETs. In order to design the CTIA circuit with the GaAs JFETs, we fabricated the independent GaAs JFETs and matched pairs of them. We measured electrical characteristics of these GaAs JFETs at the cryogenic temperatures less than 4.2 K. We demonstrated performance of an operational amplifier fabricated with the GaAs JFETs measuring a differential amplifier with the dual GaAs JFET, and additionally estimate amplifier gain, offset voltage, and power consumption of the CTIA by the circuit simulation using the PSPICE. In consequence, the expected performance fulfills the requirements for the readout amplifier of the STJs except for the noise performance.

  9. 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.

  10. Vertical Ge/Si Core/Shell Nanowire Junctionless Transistor.

    PubMed

    Chen, Lin; Cai, Fuxi; Otuonye, Ugo; Lu, Wei D

    2016-01-13

    Vertical junctionless transistors with a gate-all-around (GAA) structure based on Ge/Si core/shell nanowires epitaxially grown and integrated on a ⟨111⟩ Si substrate were fabricated and analyzed. Because of efficient gate coupling in the nanowire-GAA transistor structure and the high density one-dimensional hole gas formed in the Ge nanowire core, excellent P-type transistor behaviors with Ion of 750 μA/μm were obtained at a moderate gate length of 544 nm with minimal short-channel effects. The experimental data can be quantitatively modeled by a GAA junctionless transistor model with few fitting parameters, suggesting the nanowire transistors can be fabricated reliably without introducing additional factors that can degrade device performance. Devices with different gate lengths were readily obtained by tuning the thickness of an etching mask film. Analysis of the histogram of different devices yielded a single dominate peak in device parameter distribution, indicating excellent uniformity and high confidence of single nanowire operation. Using two vertical nanowire junctionless transistors, a PMOS-logic inverter with near rail-to-rail output voltage was demonstrated, and device matching in the logic can be conveniently obtained by controlling the number of nanowires employed in different devices rather than modifying device geometry. These studies show that junctionless transistors based on vertical Ge/Si core/shell nanowires can be fabricated in a controlled fashion with excellent performance and may be used in future hybrid, high-performance circuits where bottom-up grown nanowire devices with different functionalities can be directly integrated with an existing Si platform. PMID:26674542

  11. 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.

  12. 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.

  13. High current transistor pulse generator

    SciTech Connect

    Nesterov, V.; Cassel, R.

    1991-05-01

    A solid state pulse generator capable of delivering high current trapezoidally shaped pulses into an inductive load has been developed at SLAC. Energy stored in the capacitor bank of the pulse generator is switched to the load through a pair of Darlington transistors. A combination of diodes and Darlington transistors is used to obtain trapezoidal or triangular shaped current pulses into an inductive load and to recover the remaining energy in the same capacitor bank without reversing capacitor voltage. The transistors work in the switch mode, and the power losses are low. The rack mounted pulse generators presently used at SLAC contain a 660 microfarad storage capacitor bank and can deliver 400 amps at 800 volts into inductive loads up to 3 mH. The pulse generators are used in several different power systems, including pulse to pulse bipolar power supplies and in application with current pulses distributed into different inductive loads. The current amplitude and discharge time are controlled by the central computer system through a specially developed multichannel controller. Several years of operation with the pulse generators have proven their consistent performance and reliability. 8 figs.

  14. 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.

  15. 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 ...

  16. 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.

  17. 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

  18. A 600-MHz median-type digital filter on GaAs

    NASA Technical Reports Server (NTRS)

    Vainjo, Olli; Sundaram, Mani; Long, Stephen I.; Neuvo, Yrjo

    1992-01-01

    A single-chip GaAs implementation of an FIR-median hybrid filter is presented. The very high-speed digital filter combines linear averaging structures to a median selector. The filter operates on 5-b samples with ECL-compatible I/O interfaces. The 1500-transistor LSI device with 3.6-sq mm chip size was processed with a 1.0-micron GaAs depletion-mode (D-mode) MESFET process. The filter demonstrates 600-MHz sample rate when operated in test mode utilizing special built-in feedback.

  19. An all-implanted, self-aligned, GaAs JFET with a nonalloyed W/p[sup +]-GaAs ohmic gate contact

    SciTech Connect

    Zolper, J.C.; Baca, A.G.; Shul, R.J.; Howard, A.J.; Rieger, D.J.; Sherwin, M.E.; Lovejoy, M.L.; Hjalmarson, H.P.; Draper, B.L.; Klem, J.F.; Hietala, V.M. )

    1994-07-01

    The authors describe a self-aligned, refractory metal gate contact, enhancement mode, GaAs junction field effect transistor (JFET) where all impurity doping was done by ion implantation. Processing conditions are presented for realizing a high gate turn on voltage ([approximately]1.0 V at 1 mA/mm of gate current) relative to GaAs MESFET's. The high gate turn-on voltage is the result of optimizing the p+-gate implant and anneal to achieve a nonalloyed ohmic contact between the implanted p[sup +]-GaAs and the sputter deposited tungsten gate contact. Initial nominally 1.0 [mu]m [times] 50 [mu]m n-JFET's have a transconductance of 85 mS/mm and f[sub t] of 11.4 GHz.

  20. GaAs IC technology for wireless communications applications

    SciTech Connect

    Nair, V.

    1995-12-31

    Present day wireless communication products require low power consumption receivers and high efficiency transmitters. Long battery life, light weight, small size and low cost are few of the key parameters that determine the success of a portable communication product. The size and weight of wireless products can be drastically reduced by decreasing the number of battery cells. RF power amplifiers are the highest energy consumption component of portable communication equipment. The introduction of GaAs MESFET, HFET, and HBT into wireless communications equipment increased the performance level of RF power functions. A significant improvement in DC to RF conversion efficiency over the previous bipolar RF power amplifiers was achieved. In order to meet the customer demand for longer talk time, low power receiver ICs and high efficiency power amplifiers are being designed into wireless communications products. Semiconductor devices with better noise figure-gain performance and higher efficiency are needed to maintain the same RF performance at lower voltages. Linearity of the device is also very important for the transmitter and receiver applications. GaAs device and IC technology has many salient features that make it an ideal candidate for wireless communication applications. GaAs IC receivers lead to a reduction in the number of parts and interconnects and, hence, the size and weight. In this paper we will discuss the principles of GaAs device and IC design, with emphasis on the active and passive devices, circuit design and applications. GaAs Microwave Monolithic Integrated Circuits (MMICs) design principles and examples will also be discussed.

  1. Characterization and modeling of ion-implanted GaAs FET's

    SciTech Connect

    Chen, C.H.

    1986-01-01

    Gallium arsenide has several advantages compared to silicon such as high low-field mobility, large (approx. 1.4 eV), and direct energy-band gap. Fabrication of devices and IC's (integrated circuits) relies heavily on semi-insulating (SI) GaAs substrate. However, there are some undesirable properties associated with binary compound semiconductors. Because the physical properties (such as melting point) of Ga are quite different from those of As, GaAs has intrinsic defects and surface defects. This leads to GaAs material characteristics with large surface-state densities and deep-level traps in the bulk. This thesis investigates the non-ideal behavior of GaAs FET's (field effect transistors) fabricated by ion-implantion into the GaAs substrate. In order to understand the behavior of ion-implanted GaAs FET's, a thorough understanding of the crystal properties is required. A model based on the process parameters such as doses, projected range, etc., is developed. This model is used for the simulation of the FET's device parameters such as threshold voltage and transconductance as functions of the gate length, temperature, and orientation on the water. This model can also simulate the effect of annealing time on the FET characteristics. It can be used as a tool to optimize the process parameters before the actual fabrication.

  2. Integration of front-end electronics with GaAs pixel detectors: Experimental and feasibility analysis

    SciTech Connect

    Bertuccio, G.; Longoni, A.; De Geronimo, G.; Canali, C.; Lanzieri, C.; Nava, F.

    1999-08-01

    This work aims to study the feasibility of the integration, on the same chip, of GaAs pixel detectors and frontend electronics employing GaAs metal semiconductor FET`s (MESFET`s) or high electron mobility transistors (HEMT`s). The interest of fully integrated GaAs systems lies in X and {gamma}-ray spectroscopy and Imaging for scientific, industrial, and medical applications. The system design criteria and the prediction of the performance have been derived on the basis of recent experimental results on semi-insulating GaAs pixel detectors. Measurements of the relevant parameters of GaAs FET`s suitable for the stringent requirements of a specroscopy-grade frontend amplifier are analyzed. It is shown that an optimized GaAs integrated system can reach an electronic noise level below 100 electrons rms (<1 keV FWHM) even at room temperature. Some open problems regarding the detector-electronics integration are highlighted and discussed.

  3. 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.

  4. 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.

  5. 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)

  6. The bootstrapped gate FET (BGFET) - A new control transistor

    SciTech Connect

    Bayruns, R.; Li, K.; Stoffman, O.D.

    1995-12-31

    Si PIN diodes are used almost exclusively when low cost, low distortion variable attenuators are needed. PIN diodes can obtain an input third order intercept IIP3 of +20 to +40 dBm, but at the expense of complicated biasing and high current consumption. GaAs MESFETs used as attenuators require only a control voltage and are easily integrated into monolithic circuits. A major disadvantage of the GaAs MESFET is its high level of distortion. In a series attenuator configuration, a typical GaAs MESFET IIP3 is 0 dBm at 10 dB attenuation. Therefore, GaAs MESFETs are used only under very low level input signals. This precludes their use from most high volume applications such as cable television, DBS receivers and cellular telephones. The authors will present a new transistor, a bootstrapped gate FET (BGFET) which provides about an approximate 20 dB improvement in distortion over a standard GaAs MESFET.

  7. 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.

  8. Characterizing charge trapping in microwave transistors

    NASA Astrophysics Data System (ADS)

    Rathmell, James G.; Parker, Anthony E.

    2005-12-01

    This paper looks at the problems associated with pulsed testing of GaN and GaAs HEMTs and its use in examining the charging and discharging times of the various traps that affect conduction. A particular problem is that the RF behaviour of these transistors varies with the state of charge of the traps. This is a concern for a large class of applications where the usage pattern is comparable to the time constants of the traps. Such classes include the intermittently-switched front ends of 802.11 and mobile telephone circuits. The conventional approach with pulsed testing is to sit at a bias point for a sufficiently long time and then to pulse to characteristic voltages very quickly before returning to the bias. If the pulsing to the applied characteristic voltages is much faster than the time constants of the traps of the transistor, then the characteristic measured will reflect the state of charge of the traps for the bias point. Our approach here is to perform a series of characteristic measurements as the bias and trap charge-state change. Each characteristic is measured too quickly to affect the trapped charge significantly. The set of characteristics then reflects the changing nature of the transistor's bias and state of charge of its traps.

  9. 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

  10. A Ku-band oscillator subsystem using a broadband GaAs MMIC push-pull amplifier/doubler

    NASA Astrophysics Data System (ADS)

    Martin, Robert; Ali, Fazal

    1991-11-01

    The design and performance results of a Ku-band voltage controlled oscillator subsystem using a broadband GaAs MMIC (monolithic microwave integrated circuit) push-pull amplifier as a frequency doubler are described. The subsystem utilizes both GaAs MMIC and Si bipolar technologies to achieve the desired performance objectives. The oscillator subsystem is tunable over the 14-18-GHz frequency range with a minimum output power of 18 dBm and a phase noise of -88 dBc/Hz at 100-kHz offset from the carrier over a 0 to +65 C temperature range.

  11. Bipolar Disorder, Bipolar Depression and Comorbid Illness.

    PubMed

    Manning, J Sloan

    2015-06-01

    There is a substantial need for the early recognition and treatment of the psychiatric and medical comorbidities of bipolar disorder in primary care. If comorbid conditions are recognized and treated, serious adverse health outcomes may be averted, including substantial morbidity and mortality. PMID:26172635

  12. Pressure transducer of the on the basis of reactive properties of transistor structure with negative resistance

    NASA Astrophysics Data System (ADS)

    Osadchuk, Alexander V.; Osadchuk, Iaroslav A.; Smolarz, Andrzej; Kussambayeva, Nazym

    2015-12-01

    The opportunity of direct transformation of pressure in frequency is shown on the basis of the hybrid integrated circuit consisting of the two-collector pressure sensitive transistor and the field two-gate transistor with an active inductive element on the basis of the bipolar transistor with a phase-shifting RC chain. Analytical dependencies of transformation function and the equation of sensitivity are received. Theoretical and experimental research have shown, that sensitivity of the transducer makes 1,55-1,10kHz/kPa.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Fracture mechanics evaluation of GaAs

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    1984-01-01

    A data base of mechanical and fracture properties for GaAs was generated. The data for single crystal GaAs will be used to design reusable GaAs solar modules. Database information includes; (1) physical property characterizations; (2) fracture behavior evaluations; and (3) strength of cells determined as a function of cell processing and material parameters.

  20. Ku-band MIC bipolar VCO

    NASA Astrophysics Data System (ADS)

    Winch, R. G.; Matson, J. L.

    1981-04-01

    Voltage-controlled oscillators (VCO) for electronic counter measures (ECM) applications require a highly linear V/f response. From a systems standpoint, interfacing the VCO is an equally important consideration. In order to satisfy the requirements at high Ku-band, an effective design philosophy is to use a self-oscillating multiplier (osciplier) which initially generates the oscillation frequency at half the output frequency and uses the tuning diodes and output matching to enhance the first harmonic for the output. The feasibility of a bipolar VCO at 18 GHz using transistors and diodes is illustrated. When interfaced with an amplifier/buffer/limiter, the oscillator output power is increased and flattened to approximately 8.0 + or - 0.5 dBm across the band.

  1. 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.

  2. Recent advances in GaAs JFETs for deep cryogenic focal plane readouts

    NASA Astrophysics Data System (ADS)

    Cunningham, Thomas J.; Fitzsimmons, Michael

    1998-09-01

    The progress of the JPL in developing gallium arsenide junction field-effect transistors (GaAs JFETs) for application in RI readout electronics operating below 10 Kelvin is discussed. Results on GaAs JFETs fabricated using a highly isotropic HF-based etchant have been presented previously by our group. The isotropic etch reduced the typical input leakage current at 4K to less than 1 fA. These JFETs had a low frequency noise of just under 1 (mu) V/Hz(superscript 1/2) at 1 Hz at 4K, while dissipating less than 1 (mu) W of power. Building on this work, we have fabricated small-scale integrated circuits based on this GaAs JFET technology. In this paper we report on the fabrication of small-scale integrated circuit multiplexers and amplifiers. An 8 by 1 source-follower-per-detector multiplexer and a three-transistor differential pair have been fabricated and are fully functional at 4K. The input-referred noise and leakage current is consistent with that for the discrete devices. A systematic study of the device size dependence of the noise has been started, but as yet is inconclusive.

  3. 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.

  4. 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 ...

  5. GaAs MOEMS Technology

    SciTech Connect

    SPAHN, OLGA B.; GROSSETETE, GRANT D.; CICH, MICHAEL J.; TIGGES, CHRIS P.; RENO, JOHN L.; PEAKE, GREGORY M.; KLEM, JOHN F.; LEAN, JEN; FULLER, CHARLES T.; BURKHART, JEFF; BAUER, THOMAS; SULLIVAN, CHARLES T.

    2003-03-01

    Many MEMS-based components require optical monitoring techniques using optoelectronic devices for converting mechanical position information into useful electronic signals. While the constituent piece-parts of such hybrid opto-MEMS components can be separately optimized, the resulting component performance, size, ruggedness and cost are substantially compromised due to assembly and packaging limitations. GaAs MOEMS offers the possibility of monolithically integrating high-performance optoelectronics with simple mechanical structures built in very low-stress epitaxial layers with a resulting component performance determined only by GaAs microfabrication technology limitations. GaAs MOEMS implicitly integrates the capability for radiation-hardened optical communications into the MEMS sensor or actuator component, a vital step towards rugged integrated autonomous microsystems that sense, act, and communicate. This project establishes a new foundational technology that monolithically combines GaAs optoelectronics with simple mechanics. Critical process issues addressed include selectivity, electrochemical characteristics, and anisotropy of the release chemistry, and post-release drying and coating processes. Several types of devices incorporating this novel technology are demonstrated.

  6. 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.

  7. Long-Wavelength-Infrared Hot-Electron Transistor

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D.; Liu, John K.; Park, Jin S.; Lin, True-Lon

    1995-01-01

    Dark current reduced by energy-discriminating quantum filter. Very long-wavelength-infrared hot-electron transistor developed. Device detects photons at wavelengths around 16 micrometers. Comprises photodector integrated with energy-discriminating quantum filter in multiple-quantum-well structure. Made of variously doped and undoped layers of GaAs (quantum wells) and Al(x)Ga(1-x)As (barriers between wells). In transistor, bound-to-continuum GaAs/Al(x)Ga(1-x)As multiple-quantum-well infrared photodectors (QWIP) serves as photosensitive emitter. Wide quantum well serves as base, and there is thick barrier between base and collector. Combination of barrier and base quantum well acts as energy-discriminating filter: electrons with higher energies pass through filter to collector, those with lower energies blocked and diverted from output-current path through base contact.

  8. 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

  9. A highly selective, chlorofluorocarbon-free GaAs on AlGaAs etch

    SciTech Connect

    Smith, L.E. . Solid State Technology Center)

    1993-07-01

    A highly selective reactive ion etching process using SiCl[sub 4], CF[sub 4], O[sub 2], and He is reported. The selectivity of the etch, which is adjustable, ranges from 308:1 to 428:1 for GaAs to Al[sub 0.11]Ga[sub 0.89]As. This variability in selectivity is achieved by adjusting the helium flow rate. One very attractive feature of this etch is that it uses no chlorofluorocarbons and therefore complies with future bans on these substances imposed at both federal and corporate levels. The etch is demonstrated on a GaAs field effect transistor structure with an underlying Al[sub 0.11]Ga[sub 0.89]As stop-etch layer. The etch can be used for both anisotropic and isotropic applications.

  10. Monolithic cryogenic preamplifiers based on large gate-area GaAs MESFETs

    SciTech Connect

    Camin, D.V.; Fedyakin, N.; Pessina, G.; Previtali, E.

    1995-08-01

    Monolithic preamplifiers using large gate-area Gallium-Arsenide Metal-Semiconductor Field-Effect Transistors (GaAs MESFETs) at the input have been designed and fabricated using an ion-implanted GaAs process. Large gate-area is necessary to obtain low series noise. A differential voltage-sensitive preamplifier has at the input two MESFETs with a gate width W = 6,000 {micro}m, it is fully DC coupled, has a large common-mode rejection ratio (CMRR) and dissipates low power at 4 K. Dual current-sensitive preamplifiers using at the input MESFETs with W = 24,000 {micro}m, designed for the readout of noble liquid calorimeters, have been integrated in a single chip. Recent tests with a LAr calorimeter prototype demonstrated strong noise reduction compared to previous state-of-the-art hybrid readout circuits. Radiation damage tests have been performed at cold on the current-sensitive preamplifier chips.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Development of a HgCdTe photomixer and impedance matched GaAs FET amplifier

    NASA Technical Reports Server (NTRS)

    Shanley, J. F.; Paulauskas, W. A.; Taylor, D. R.

    1982-01-01

    A research program for the development of a 10.6 micron HgCdTe photodiode/GaAs field effect transistor amplifier package for use at cryogenic temperatures (77k). The photodiode/amplifier module achieved a noise equivalent power per unit bandwidth of 5.7 times 10 to the 20th power W/Hz at 2.0 GHz. The heterodyne sensitivity of the HgCdTe photodiode was improved by designing and building a low noise GaAs field effect transistor amplifier operating at 77K. The Johnson noise of the amplifier was reduced at 77K, and thus resulted in an increased photodiode heterodyne sensitivity.

  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. 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.

  20. Epilepsy and bipolar disorder.

    PubMed

    Knott, Sarah; Forty, Liz; Craddock, Nick; Thomas, Rhys H

    2015-11-01

    It is well recognized that mood disorders and epilepsy commonly co-occur. Despite this, our knowledge regarding the relationship between epilepsy and bipolar disorder is limited. Several shared features between the two disorders, such as their episodic nature and potential to run a chronic course, and the efficacy of some antiepileptic medications in the prophylaxis of both disorders, are often cited as evidence of possible shared underlying pathophysiology. The present paper aims to review the bidirectional associations between epilepsy and bipolar disorder, with a focus on epidemiological links, evidence for shared etiology, and the impact of these disorders on both the individual and wider society. Better recognition and understanding of these two complex disorders, along with an integrated clinical approach, are crucial for improved evaluation and management of comorbid epilepsy and mood disorders. PMID:26316422

  1. Bipolar pulse shaping revisited

    SciTech Connect

    Fairstein, E.

    1996-12-31

    Compared with unipolar pulse shaping, bipolar shaping is insensitive to misadjusted or missing pole-zero cancellation, doesn`t require a baseline line restorer, and furnishes an amplitude-invariant time marker for coincidence measurements. These characteristics should be useful in amplifier arrays for integrated circuits (ASICs), despite the greater noise and resolving time. With ASIC technology in mind, unipolar and bipolar shaping methods are compared here. An item that emerged from the study is that two CR differentiators and two RC integrators are optimum from a cost-benefit viewpoint. The network can be adjusted to produce the transfer function (sin t - t) exp(-t), which has half the transmission loss and 8% shorter resolving time than the same configuration with all time constants alike.

  2. 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.

  3. Living with bipolar disorder.

    PubMed

    Kasper, Siegfried F

    2004-11-01

    Bipolar disorder is a chronic, episodic disease characterized by intermittent episodes of depressive and manic symptoms. It causes significant and long-lasting distress, functional impairment and morbidity, and is associated with a high risk of mortality. Quality of life and disease burden, particularly in terms of lifestyle and general functioning, are gaining increasing recognition as valid therapeutic targets for intervention. Quality of life among patients with bipolar disorders is significantly impaired both during and between acute episodes. Somatic and mood symptoms, stigmatization, comorbid conditions, associated cognitive deficits and the burden of treatment all can combine to severely undermine patient quality of life and functioning at all levels. The tolerability of treatment is an important consideration when choosing a therapeutic option as patient satisfaction with, and adherence to, treatment can influence health outcomes and quality of life. Early intervention with the appropriate treatment can alter the course of bipolar disorder and improve the long-term experience of patients in their management of the disease. PMID:16279866

  4. Bipolar Disorder in Children and Teens

    MedlinePlus

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

  5. 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.

  6. 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.

  7. GaAs solar cell development

    NASA Technical Reports Server (NTRS)

    Knechtli, R. C.; Kamath, S.; Loo, R.

    1977-01-01

    The motivation for developing GaAs solar cells is based on their superior efficiency when compared to silicon cells, their lower degradation with increasing temperature, and the expectation for better resistance to space radiation damage. The AMO efficiency of GaAs solar cells was calculated. A key consideration in the HRL technology is the production of GaAs cells of large area (greater than 4 sg cm) at a reasonable cost without sacrificing efficiency. An essential requirement for the successful fabrication of such cells is the ability to grow epitaxially a uniform layer of high quality GaAs (buffer layer) on state-of-the-art GaAs substrates, and to grow on this buffer layer the required than layer of (AlGa)As. A modified infinite melt liquid phase epitaxy (LPE) growth technique is detailed.

  8. Improvement of terahertz field effect transistor detectors by substrate thinning and radiation losses reduction.

    PubMed

    Coquillat, Dominique; Marczewski, Jacek; Kopyt, Pawel; Dyakonova, Nina; Giffard, Benoit; Knap, Wojciech

    2016-01-11

    Phenomena of the radiation coupling to the field effect transistors based terahertz (THz) detectors are studied. We show that in the case of planar metal antennas a significant portion of incoming radiation, instead of being coupled to the transistors, is coupled to an antenna substrate leading to responsivity losses and/or cross-talk effects in the field effect based THz detector arrays. Experimental and theoretical investigations of the responsivity versus substrate thickness are performed. They clearly show how to minimize the losses by the detector/ array substrate thinning. In conclusion simple quantitative rules of losses minimization by choosing a proper substrate thickness of field effect transistor THz detectors are presented for common materials (Si, GaAs, InP, GaN) used in semiconductor technologies. PMID:26832258

  9. 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).

  10. 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.

  11. Childhood trauma in bipolar disorder

    PubMed Central

    Gallagher, Peter; Dougall, Dominic; Porter, Richard; Moncrieff, Joanna; Ferrier, I Nicol; Young, Allan H

    2014-01-01

    Objective: There has been little investigation of early trauma in bipolar disorder despite evidence that stress impacts on the course of this illness. We aimed to compare the rates of childhood trauma in adults with bipolar disorder to a healthy control group, and to investigate the impact of childhood trauma on the clinical course of bipolar disorder. Methods: Retrospective assessment of childhood trauma was conducted using the Childhood Trauma Questionnaire (CTQ) in 60 outpatients with bipolar disorder being treated for a depressive episode and 55 control participants across two centres in north-east England and New Zealand. Results: Significantly higher rates of childhood trauma were observed in patients with bipolar I and bipolar II disorder compared to controls. Logistic regression, controlling for age and sex, identified emotional neglect to be the only significant CTQ subscale associated with a diagnosis of bipolar disorder. Childhood history of sexual abuse was not a significant predictor. Associations with clinical severity or course were less clear. Conclusions: Childhood emotional neglect appears to be significantly associated with bipolar disorder. Limitations include the relatively small sample size, which potentially increases the risk of type II errors. Replication of this study is required, with further investigation into the neurobiological consequences of childhood trauma, particularly emotional neglect. PMID:24343193

  12. 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.

  13. Bipolar Disorder and Inflammation.

    PubMed

    Rosenblat, Joshua D; McIntyre, Roger S

    2016-03-01

    The pathophysiology of bipolar disorder (BD) remains poorly understood. Current psychopharmacologic treatments are often poorly tolerated and carry high rates of treatment resistance. Mounting evidence has suggested that innate immune system dysfunction may play a role in the pathophysiology of BD. Elevated proinflammatory cytokine levels have been identified. The innate immune system is a novel therapeutic target in BD. Lithium has been shown to have antiinflammatory properties. Further research is needed to establish the role of antiinflammatory agents in the treatment of BD; however, evidence from several clinical trials indicates that antiinflammatory agents may be incorporated into clinical practice soon. PMID:26876323

  14. 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

  15. GaAs MMICs satisfy EW requirements

    NASA Astrophysics Data System (ADS)

    Tenedorio, Jaime G.; Komiak, James J.

    1988-11-01

    The characteristics of GaAs MMICs are discussed with emphasis placed on the features required for their application to electronic warfare. Several examples of GaAs MMICs developed for phased-array application are described. Attention is also given to an X-band MMIC-based module designed for the multifunction active-array radar for fighter aircraft and to a C-band T/R module designed for a ground-based tactical radar. Two examples of GaAs MMIC applications to electronic countermeasure technology are presented.

  16. Photosensitive graphene transistors.

    PubMed

    Li, Jinhua; Niu, Liyong; Zheng, Zijian; Yan, Feng

    2014-08-20

    High performance photodetectors play important roles in the development of innovative technologies in many fields, including medicine, display and imaging, military, optical communication, environment monitoring, security check, scientific research and industrial processing control. Graphene, the most fascinating two-dimensional material, has demonstrated promising applications in various types of photodetectors from terahertz to ultraviolet, due to its ultrahigh carrier mobility and light absorption in broad wavelength range. Graphene field effect transistors are recognized as a type of excellent transducers for photodetection thanks to the inherent amplification function of the transistors, the feasibility of miniaturization and the unique properties of graphene. In this review, we will introduce the applications of graphene transistors as photodetectors in different wavelength ranges including terahertz, infrared, visible, and ultraviolet, focusing on the device design, physics and photosensitive performance. Since the device properties are closely related to the quality of graphene, the devices based on graphene prepared with different methods will be addressed separately with a view to demonstrating more clearly their advantages and shortcomings in practical applications. It is expected that highly sensitive photodetectors based on graphene transistors will find important applications in many emerging areas especially flexible, wearable, printable or transparent electronics and high frequency communications. PMID:24715703

  17. Standard Transistor Arrays

    NASA Technical Reports Server (NTRS)

    Cox, G. W.; Carroll, B. D.; Pitts, E. R.; Wright, R. A.

    1983-01-01

    Standard Transistor Array (STAR) design system is semicustom approach to generating random-logic integrated MOS digital circuits. Primary program in STAR system is CAPSTAR, STAR Cell Arrangement Program. CAPSTAR is augmented by automatic routining program, Display program and library of logic cells.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. Comorbid anxiety in bipolar disorder

    PubMed Central

    Nakagawa, Atsuo; Grunebaum, Michael F; Sullivan, Gregory M; Currier, Dianne; Ellis, Steven P; Burke, Ainsley K; Brent, David A; Mann, J John; Oquendo, Maria A

    2009-01-01

    Objective Comorbid anxiety disorder is reported to increase suicidality in bipolar disorder. However, studies of the impact of anxiety disorders on suicidal behavior in mood disorders have shown mixed results. The presence of personality disorders, often comorbid with anxiety and bipolar disorders, may explain these inconsistencies. This study examined the impact of comorbid Cluster B personality disorder and anxiety disorder on suicidality in bipolar disorder. Methods A total of 116 depressed bipolar patients with and without lifetime anxiety disorder were compared. Multiple regression analysis tested the association of comorbid anxiety disorder with past suicide attempts and severity of suicidal ideation, adjusting for the effect of Cluster B personality disorder. The specific effect of panic disorder was also explored. Results Bipolar patients with and without anxiety disorders did not differ in the rate of past suicide attempt. Suicidal ideation was less severe in those with anxiety disorders. In multiple regression analysis, anxiety disorder was not associated with past suicide attempts or with the severity of suicidal ideation, whereas Cluster B personality disorder was associated with both. The results were comparable when comorbid panic disorder was examined. Conclusions Comorbid Cluster B personality disorder appears to exert a stronger influence on suicidality than comorbid anxiety disorder in persons with bipolar disorder. Assessment of suicide risk in patients with bipolar disorder should include evaluation and treatment of Cluster B psychopathology. PMID:18452449

  3. Pulse transformer for GaAs laser

    NASA Technical Reports Server (NTRS)

    Rutz, E. M.

    1976-01-01

    High-radiance gallium arsenide (GaAs) laser operating at room temperature is utilized in optical navigation system. For efficient transformer-to-laser impedance match, laser should be connected directly to pulse transformer secondary winding.

  4. 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

  5. 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.

  6. GaAs based floating point module

    NASA Astrophysics Data System (ADS)

    Lange, Thomas; Tetzlaff, David E.; Snodgrass, Thomas D.; Woods, Jordon W.

    1990-10-01

    GaAs integrated circuit technology is being applied to improve the performance and functionality of the Digital Video Mapping System. A 400 MFLOP 32 bit floating point processor will be used to accelerate data and graphics processing algorithms. The GaAs processor will contain 4 circuit types interconnected using a thin film multilayer packaging technology. The processor clock rate is 200 MHz and the I/Os are at CMOS levels operating at less than 50MHz.

  7. Ohmic contact to GaAs semiconductor

    NASA Technical Reports Server (NTRS)

    Hovel, H. J.; Woodall, J. M.

    1980-01-01

    Multimetallic layers produce stable, low-resistance contacts for p-type GaAs and p-type GaAlAs devices. Contacts present no leakage problems, and their series resistance is too small to measure at 1 Sun intensity. Ohmic contacts are stable and should meet 20-year-life requirement at 150 C for GaAs combined photothermal/photovoltaic concentrators.

  8. A Vertically Integrated Junctionless Nanowire Transistor.

    PubMed

    Lee, Byung-Hyun; Hur, Jae; Kang, Min-Ho; Bang, Tewook; Ahn, Dae-Chul; Lee, Dongil; Kim, Kwang-Hee; Choi, Yang-Kyu

    2016-03-01

    A vertically integrated junctionless field-effect transistor (VJ-FET), which is composed of vertically stacked multiple silicon nanowires (SiNWs) with a gate-all-around (GAA) structure, is demonstrated on a bulk silicon wafer for the first time. The proposed VJ-FET mitigates the issues of variability and fabrication complexity that are encountered in the vertically integrated multi-NW FET (VM-FET) based on an identical structure in which the VM-FET, as recently reported, harnesses a source and drain (S/D) junction for its operation and is thus based on the inversion mode. Variability is alleviated by bulk conduction in a junctionless FET (JL-FET), where current flows through the core of the SiNW, whereas it is not mitigated by surface conduction in an inversion mode FET (IM-FET), where current flows via the surface of the SiNW. The fabrication complexity is reduced by the inherent JL structure of the JL-FET because S/D formation is not required. In contrast, it is very difficult to dope the S/D when it is positioned at each floor of a tall SiNW with greater uniformity and with less damage to the crystalline structure of the SiNW in a VM-FET. Moreover, when the proposed VJ-FET is used as nonvolatile flash memory, the endurance and retention characteristics are improved due to the above-mentioned bulk conduction. PMID:26885948

  9. 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

  10. Genetics of bipolar disorder

    PubMed Central

    Kerner, Berit

    2014-01-01

    Bipolar disorder is a common, complex genetic disorder, but the mode of transmission remains to be discovered. Many researchers assume that common genomic variants carry some risk for manifesting the disease. The research community has celebrated the first genome-wide significant associations between common single nucleotide polymorphisms (SNPs) and bipolar disorder. Currently, attempts are under way to translate these findings into clinical practice, genetic counseling, and predictive testing. However, some experts remain cautious. After all, common variants explain only a very small percentage of the genetic risk, and functional consequences of the discovered SNPs are inconclusive. Furthermore, the associated SNPs are not disease specific, and the majority of individuals with a “risk” allele are healthy. On the other hand, population-based genome-wide studies in psychiatric disorders have rediscovered rare structural variants and mutations in genes, which were previously known to cause genetic syndromes and monogenic Mendelian disorders. In many Mendelian syndromes, psychiatric symptoms are prevalent. Although these conditions do not fit the classic description of any specific psychiatric disorder, they often show nonspecific psychiatric symptoms that cross diagnostic boundaries, including intellectual disability, behavioral abnormalities, mood disorders, anxiety disorders, attention deficit, impulse control deficit, and psychosis. Although testing for chromosomal disorders and monogenic Mendelian disorders is well established, testing for common variants is still controversial. The standard concept of genetic testing includes at least three broad criteria that need to be fulfilled before new genetic tests should be introduced: analytical validity, clinical validity, and clinical utility. These criteria are currently not fulfilled for common genomic variants in psychiatric disorders. Further work is clearly needed before genetic testing for common variants in psychiatric disorders should be established. PMID:24683306

  11. 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.

  12. Gyrator employing field effect transistors

    NASA Technical Reports Server (NTRS)

    Hochmair, E. S. (Inventor)

    1973-01-01

    A gyrator circuit of the conventional configuration of two amplifiers in a circular loop, one producing zero phase shift and the other producing 180 deg phase reversal is examined. All active elements are MOS field effect transistors. Each amplifier comprises a differential amplifier configuration with current limiting transistor, followed by an output transistor in cascode configuration, and two load transistors of opposite conductivity type from the other transistors. A voltage divider control circuit comprises a series string of transistors with a central voltage input to provide control, with locations on the amplifiers receiving reference voltages by connection to appropriate points on the divider. The circuit produces excellent response and is well suited for fabrication by integrated circuits.

  13. [Bipolar depression and suicidal behavior].

    PubMed

    Guillaume, S; Courtet, P; Samalin, L

    2011-12-01

    Suicide is a frequent and tragic consequence of bipolar depression. The prevention of suicidal behavior (SB) need an assessment of vulnerability traits related related to SB (personal suicide history, impulsive traits...), characteristics of depression (mixed depression, subtype of bipolar disorder...), psychiatric comorbidities and stressors psycho-social. Meanwhile, the characteristics of suicidal behavior (ie: severe or multiple attempts) suggest a diagnosis of bipolar disorder rather than major depressive disorder. In addition to a correct screening of bipolar disorders and assessment of suicidal behavior, the removal of lethal means, networking and treatment of depression reduces the risk of suicidal behavior. Finally, lithium may have a particular interest in subjects at high risk of suicide. PMID:22212869

  14. Architecture/compiler synergism in GaAs computer systems

    SciTech Connect

    Milutinovic, V.; Fura, D.; Helbig, W.; Linn, J.

    1987-05-01

    In this article the authors describe an approach to computer system design that we feel is very attractive for GaAs technology. The strategy involves the use of a single-chip GaAs processor, an increased role for the compiler, and an aggressive migration of functions from hardware to the compiler. In fact, the authors believe that the advantages of GaAs technology cannot be fully exploited without further developments in compiler technology. This article follows previous papers on GaAs processor design and GaAs system design, and completes our overview of GaAs technology-based computer system design.

  15. Metatronic transistor amplifier

    NASA Astrophysics Data System (ADS)

    Chettiar, Uday K.; Engheta, Nader

    2015-10-01

    Utilizing the notion of metamaterials, in recent years the concept of a circuit and lumped circuit elements have been extended to the optical domains, providing the paradigm of optical metatronics, i.e., metamaterial-inspired optical nanocircuitry, as a powerful tool for design and study of more complex systems at the nanoscale. In this paper we present a design for a new metatronic element, namely, a metatronic transistor that functions as an amplifier. As shown by our analytical and numerical paper here, this metatronic transistor provides gain as well as isolation between the input and output ports of such two-port device. The cascadability and fan-out aspects of this element are also explored.

  16. 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.

  17. High voltage power transistor development

    NASA Technical Reports Server (NTRS)

    Hower, P. L.

    1981-01-01

    Design considerations, fabrication procedures, and methods of evaluation for high-voltage power-transistor development are discussed. Technique improvements such as controlling the electric field at the surface and perserving lifetimes in the collector region which have advanced the state of the art in high-voltage transistors are discussed. These improvements can be applied directly to the development of 1200 volt, 200 ampere transistors.

  18. 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

  19. 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

  20. The investigation of the diameter dimension effect on the Si nano-tube transistors

    NASA Astrophysics Data System (ADS)

    Liao, M.-H.; Yeh, C.-H.; Lee, C.-C.; Wang, C.-P.

    2016-03-01

    The vertical gate-all-around (V-GAA) Si nano-tube (NT) devices with different diameter dimensions are studied in this work with the promising device performance. The V-GAA structure makes the transistor easy to be scaled down continuously to meet the complementary metal-oxide-semiconductor (CMOS) scaling requirements of the 7/10 nm technology node and beyond. The Si NT device with the hollow structure is demonstrated to have the capability to "deplete" and "screen-out" the out-of gate control carriers in the center of the NT and further result in the better device short channel control. Based on the study in this work, the V-GAA Si NT device with the optimized diameter dimension (=20 nm) can benefit the Ion-state current and reduce the Ioff-state stand-by power simultaneously, due to the less surface roughness scattering and the better short channel control characteristics. The proposed V-GAA Si NT device is regarded as one of the most promising candidates for the future application of the sub-7/10 nm logic era.

  1. The Genetics of Bipolar Disorder

    PubMed Central

    Barnett, Jennifer H; Smoller, Jordan W

    2009-01-01

    Bipolar disorder is a mood disorder characterized by impairing episodes of mania and depression. Twin studies have established that bipolar disorder is among the most heritable of medical disorders and efforts to identify specific susceptibility genes have intensified over the past two decades. The search for genes influencing bipolar disorder has been complicated by a paucity of animal models, limited understanding of pathogenesis, and the genetic and phenotypic complexity of the syndrome. Linkage studies have implicated several chromosomal regions as harboring relevant genes, but results have been inconsistent. It is now widely accepted that the genetic liability to bipolar disorder reflects the action of many genes of individually small effect, a scenario for which linkage studies are poorly suited. Thus, association studies, which are more powerful for the detection of modest effect loci, have become the focus of gene-finding research. A large number of candidate genes, including biological candidates derived from hypotheses about the pathogenesis of the disorder and positional candidates derived from linkage and cytogenetic studies, have been evaluated. Several of these genes have been associated with the disorder in independent studies (including BDNF, DAOA, DISC1, GRIK4, SLC6A4, and TPH2), but none has been established. The clinical heterogeneity of bipolar disorder and its phenotypic and genetic overlap with other disorders (especially schizophrenia, schizoaffective disorder, and major depressive disorder) has raised questions about the optimal phenotype definition for genetic studies. Nevertheless, genomewide association analysis, which has successfully identified susceptibility genes for a variety of complex disorders, has begun to implicate specific genes for bipolar disorder (DGKH, CACNA1C, ANK3). The polygenicity of the disorder means that very large samples will be needed to detect the modest effect loci that likely contribute to bipolar disorder. Detailed genetic dissection of the disorder may provide novel targets (both pharmacologic and psychosocial) for intervention. PMID:19358880

  2. 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 great questions facing the field and one that is likely to have profound treatment implications, given that fact that such a discovery would greatly increase our ability to individualize - and by extension, enhance - treatment. PMID:25202283

  3. All GaAs signal processing architecture

    SciTech Connect

    Geideman, W.A.; Rasset, T.L.; Misko, T.A.; Wine, J.W.

    1987-09-01

    The architecture, design, simulation, and evaluation of an all-GaAs vector signal processor for on-board space-system applications are described. The vector processor, whose architecture is based on a modular, building-block approach, consists of three main units: the control/scalar processor, the vector memory, and the execution unit. Each unit functions independently from the other, enabling the data addressing, data processing, and control to operate in parallel rather than serial manner. The GaAs processor's performance was compared with the performance of several commercial processors including the CMOS MIPS processor. When the latter was substituted for the GaAs processor in the same vector processor architecture, the performance/power ratio was nearly equal to that of the GaAs processor, but GaAs has demonstrated a higher performance upper bound. It was found that, in addition to high performance, the GaAs vector processor has fault-tolerant features and is flexible and radiation hard.

  4. Ultra-Thin-Film GaAs Solar Cells

    NASA Technical Reports Server (NTRS)

    Wang, K. L.; Shin, B. K.; Yeh, Y. C. M.; Stirn, R. J.

    1982-01-01

    Process based on organo-metallic chemical vapor deposition (OM/CVD) of trimethyl gallium with arsine forms economical ultrathin GaAs epitaxial films. Process has higher potential for low manufacturing cost and large-scale production compared with more-conventional halide CVD and liquid-phase epitaxy processes. By reducing thickness of GaAs and substituting low-cost substrate for single-crystal GaAs wafer, process would make GaAs solar cells commercially more attractive.

  5. 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.

  6. Transparent metal oxide nanowire transistors.

    PubMed

    Chen, Di; Liu, Zhe; Liang, Bo; Wang, Xianfu; Shen, Guozhen

    2012-05-21

    With the features of high mobility, a high electric on/off ratio and excellent transparency, metal oxide nanowires are excellent candidates for transparent thin-film transistors, which is one of the key technologies to realize transparent electronics. This article provides a comprehensive review of the state-of-the-art research activities that focus on transparent metal oxide nanowire transistors. It begins with the brief introduction to the synthetic methods for high quality metal oxide nanowires, and the typical nanowire transfer and printing techniques with emphasis on the simple contact printing methodology. High performance transparent transistors built on both single nanowires and nanowire thin films are then highlighted. The final section deals with the applications of transparent metal oxide nanowire transistors in the field of transparent displays and concludes with an outlook on the current perspectives and future directions of transparent metal oxide nanowire transistors. PMID:22495655

  7. Crystal growth of device quality GaAs in space

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Lagowski, J.

    1979-01-01

    The optimization of space processing of GaAs is described. The detailed compositional, structural, and electronic characterization of GaAs on a macro- and microscale and the relationships between growth parameters and the properties of GaAs are among the factors discussed. The key parameters limiting device performance are assessed.

  8. [Bipolar disorder in the elderly].

    PubMed

    Monczor, Myriam

    2010-01-01

    Bipolar disorder is a frequent disorder in the elderly, with a prevalence of 0.1 a 0.4%; a 10% of bipolar patients have mania onset after 50 years old. It has in ageing a more heterogeneous clinical presentation. The manic episodes are less severe, mixed depression is common, as well as confusion and cognitive impairment. A first manic episode in ageing can be secondary to medical illness. Treatment for bipolar disorder in ageing is similar to treatment for young patients. The differences are due to pharmacocinetic changes because of the age, with the comorbidity and with the etiology, if it is a secondary mania. Lithium can be the first choice for treating mania in patients with antecedent of good response and have tolerance to adverse effects, but because of its toxicity and secondary effects other possibilities may be considered: divalproate, cabamazepine, antipsychotics. There are some little studies that show lamotrigine efficacy in bipolar depression in elderly. We need more specific studies about bipolar disorder treatment in aging. PMID:21188315

  9. Brainstorm: occupational choice, bipolar illness and creativity.

    PubMed

    Tremblay, Carol Horton; Grosskopf, Shawna; Yang, Ke

    2010-07-01

    Although economists have analyzed earnings, unemployment, and labor force participation for those with bipolar illness, occupational choice has yet to be explored. Psychological and medical studies often suggest an association between bipolar illness and creative achievement, but they tend to focus on eminent figures, case studies, or small samples. We seek to examine occupational creativity of non-eminent individuals with bipolar disorder. We use Epidemiologic Catchment Area data to estimate a multinomial logit model matched to an index of occupational creativity. Those with bipolar illness appear to be disproportionately concentrated in the most creative occupational category. Nonparametric kernel density estimates reveal that the densities of the occupational creativity variable for the bipolar and non-bipolar individuals significantly differ in the ECA data, and suggest that the probability of engaging in creative activities on the job is higher for bipolar than non-bipolar workers. PMID:20138016

  10. 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.

  11. 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.

  12. Photoluminescence of Mn+ doped GaAs

    NASA Astrophysics Data System (ADS)

    Zhou, Huiying; Qu, Shengchun; Liao, Shuzhi; Zhang, Fasheng; Liu, Junpeng; Wang, Zhanguo

    2010-10-01

    Photoluminescence is one of the most useful techniques to obtain information about optoelectronic properties and defect structures of materials. In this work, the room-temperature and low temperature photoluminescence of Mn-doped GaAs were investigated, respectively. Mn-doped GaAs structure materials were prepared by Mn+ ion implantation at room temperature into GaAs. The implanted samples were subsequently annealed at various temperatures under N2 atmosphere to recrystallize the samples and remove implant damage. A strong peak was found for the sample annealed at 950 °C for 5 s. Transitions near 0.989 eV (1254 nm), 1.155 eV (1074 nm) and 1.329 eV (933 nm) were identified and formation of these emissions was analyzed for all prepared samples. This structure material could have myriad applications, including information storage, magnet-optical properties and energy level engineering.

  13. GaAs Solar Cell Radiation Handbook

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.

    1996-01-01

    The handbook discusses the history of GaAs solar cell development, presents equations useful for working with GaAs solar cells, describes commonly used instrumentation techniques for assessing radiation effects in solar cells and fundamental processes occurring in solar cells exposed to ionizing radiation, and explains why radiation decreases the electrical performance of solar cells. Three basic elements required to perform solar array degradation calculations: degradation data for GaAs solar cells after irradiation with 1 MeV electrons at normal incidence; relative damage coefficients for omnidirectional electron and proton exposure; and the definition of the space radiation environment for the orbit of interest, are developed and used to perform a solar array degradation calculation.

  14. Characterizing the Switching Thresholds of Magnetophoretic Transistors.

    PubMed

    Abedini-Nassab, Roozbeh; Joh, Daniel Y; Van Heest, Melissa A; Yi, John S; Baker, Cody; Taherifard, Zohreh; Margolis, David M; Garcia, J Victor; Chilkoti, Ashutosh; Murdoch, David M; Yellen, Benjamin B

    2015-10-28

    The switching thresholds of magnetophoretic transistors for sorting cells in microfluidic environments are characterized. The transistor operating conditions require short 20-30 mA pulses of electrical current. By demonstrating both attractive and repulsive transistor modes, a single transistor architecture is used to implement the full write cycle for importing and exporting single cells in specified array sites. PMID:26349853

  15. Impacts of crystal orientation of GaAs on the interfacial structures and electrical properties of Hf{sub 0.6}La{sub 0.4}O{sub x} films

    SciTech Connect

    Jia, Tingting; Kimura, Hideo; Zhao, Hongyang; Yao, Qiwen; Cheng, Zhenxiang; Cheng, Xinghong; Yu, Yuehui

    2014-04-07

    One of the major challenges in realizing the GaAs channel in the metal oxide semiconductor field effect transistor is the degrading in electron transport properties at the interface between GaAs and the gate oxide. In this study, Hf{sub 0.6}La{sub 0.4}O{sub x} gate oxide films were deposited at a low temperature (200 °C) on GaAs(111)A and GaAs(100) substrates by plasma enhanced atomic layer deposition. Microstructure analysis indicates that residuals of gallium oxide, arsenic oxide, and As element remained at the interface of Hf{sub 0.6}La{sub 0.4}O{sub x}/GaAs(100). On contrast, a smoother interface is observed between Hf{sub 0.6}La{sub 0.4}O{sub x} thin film and GaAs(111)A substrate. Furthermore, a reduction of interfacial layer is observed in Hf{sub 0.6}La{sub 0.4}O{sub x}/GaAs(111)A. Electrical characterization of the metal-insulator-semiconductor Pt/Hf{sub 0.6}La{sub 0.4}O{sub x}/n-GaAs(111)A capacitor indicated a reduction of D{sub it} and leakage current compared with the capacitor fabricated on GaAs(100)

  16. GaAs photoconductive semiconductor switch

    DOEpatents

    Loubriel, G.M.; Baca, A.G.; Zutavern, F.J.

    1998-09-08

    A high gain, optically triggered, photoconductive semiconductor switch (PCSS) implemented in GaAs as a reverse-biased pin structure with a passivation layer above the intrinsic GaAs substrate in the gap between the two electrodes of the device is disclosed. The reverse-biased configuration in combination with the addition of the passivation layer greatly reduces surface current leakage that has been a problem for prior PCSS devices and enables employment of the much less expensive and more reliable DC charging systems instead of the pulsed charging systems that needed to be used with prior PCSS devices. 5 figs.

  17. GaAs photoconductive semiconductor switch

    DOEpatents

    Loubriel, Guillermo M. (Sandia Park, NM); Baca, Albert G. (Albuquerque, NM); Zutavern, Fred J. (Albuquerque, NM)

    1998-01-01

    A high gain, optically triggered, photoconductive semiconductor switch (PCSS) implemented in GaAs as a reverse-biased pin structure with a passivation layer above the intrinsic GaAs substrate in the gap between the two electrodes of the device. The reverse-biased configuration in combination with the addition of the passivation layer greatly reduces surface current leakage that has been a problem for prior PCSS devices and enables employment of the much less expensive and more reliable DC charging systems instead of the pulsed charging systems that needed to be used with prior PCSS devices.

  18. 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.

  19. A new bipolar hook for endoscopic surgery.

    PubMed

    Perko, Z; Mimica, Z; Cala, Z; Druzijanic, N

    2000-01-01

    This article presents a new bipolar hook for endoscopic surgery. With this instrument monopolar and bipolar current can be used. The advantage of this new instrument is the possibility of using a bipolar current, which is safer than using the monopolar current. The technical details and usage instructions are discussed. PMID:10918995

  20. 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

  1. Is bipolar always bipolar? Understanding the controversy on bipolar disorder in children

    PubMed Central

    Grimmer, Yvonne; Hohmann, Sarah

    2014-01-01

    Dramatically increasing prevalence rates of bipolar disorder in children and adolescents in the United States have provoked controversy regarding the boundaries of manic symptoms in child and adolescent psychiatry. The serious impact of this ongoing debate on the treatment of affected children is reflected in the concomitant increase in prescription rates for antipsychotic medication. A key question in the debate is whether this increase in bipolar disorder in children and adolescents is based on a better detection of early-onset bipolar disorder—which can present differently in children and adolescents—or whether it is caused by an incorrect assignment of symptoms which overlap with other widely known disorders. So far, most findings suggest that the suspected symptoms, in particular chronic, non-episodic irritability (a mood symptom presenting with easy annoyance, temper tantrums and anger) do not constitute a developmental presentation of childhood bipolar disorder. Additional research based on prospective, longitudinal studies is needed to further clarify the developmental trajectories of bipolar disorder and the diagnostic status of chronic, non-episodic irritability. PMID:25580265

  2. Bipolar dislocation of the clavicle

    PubMed Central

    Jiang, Wei; Gao, Shu-guang; Li, Yu-sheng; Lei, Guang-hua

    2012-01-01

    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

  3. 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.

  4. 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

  5. VCSEL`s bonded directly to foundry fabricated GaAs smart pixel arrays

    SciTech Connect

    Pu, R.; Hayes, E.M.; Jurrat, R.; Wilmsen, C.W.; Choquette, K.D.; Hou, H.Q.; Geib, K.M.

    1997-12-01

    This letter reports the flip-chip bonding of an 8 x 8 array of free standing VCSEL`s to a foundry fabricated GaAs metal-semiconductor field-effect transistor (MESFET) smart pixel array. The VCSEL`s have oxide defined apertures and are co-planar bonded directly to smart pixels which perform the selection function of a data filter. The V{sub th} and series resistance of the VCSEL`s were on average approximately 2.1 V and 250 {Omega}, respectively, which indicates that good electrical contact was obtainable with this process. The I{sub th} ranged between 2--4 mA, with a corresponding output power of between 400 {micro}W and >1.0 mW depending on aperture size.

  6. A Cryogenic GaAs PHEMT/ Ferroelectric Ku-Band Tunable Oscillator

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.; Miranda, Felix A.; VanKeuls, Fred W.

    1998-01-01

    A Ku-band tunable oscillator operated at and below 77 K is described. The oscillator is based on two separate technologies: a 0.25 mm GaAs pseudomorphic high electron mobility transistor (PHEMT) circuit optimized for cryogenic operation, and a gold microstrip ring resonator patterned on a thin ferroelectric (SrTiO3) film which was laser ablated onto a LaAlO3 substrate. A tuning range of up to 3% of the center frequency was achieved by applying dc bias between the ring resonator and ground plane. To the best of our knowledge, this is the first tunable oscillator based on a thin film ferroelectric structure demonstrated in the microwave frequency range. The design methodology of the oscillator and the performance characteristics of the tunable resonator are described.

  7. Spectroscopy of a GaAs Double Dot Qubit with Dispersive Readout

    NASA Astrophysics Data System (ADS)

    Colless, James; Mahoney, Alice; Croot, Xanthe; Hornibrook, John; Doherty, Andrew; Stace, Tom; Lu, Hong; Gossard, Art; Reilly, David

    2013-03-01

    We report microwave spectroscopy of a GaAs double dot qubit device using the dispersive gate sensor (DGS) readout technique. In contrast to charge sensing methods based on quantum point contacts (QPCs) or single electron transistors (SETs), the DGS detection method senses the tunneling of charge between states that are near degenerate in energy. Microwave excitation applied to the surface gates enables this readout approach to resolve low energy spectroscopic features not apparent in transport or standard charge sensing measurements. We discuss the origin of these features and the use of this technique for characterizing semiconductor qubit systems. We acknowledge funding from the U.S. Intelligence Advanced Research Projects Activity (IARPA), through the U.S. Army Research Office and the Australian Research Council Centre of Excellence Scheme (Grant No. EQuS CE110001013).

  8. Influence of the local environment on Mn acceptors in GaAs.

    PubMed

    Lee, Donghun; Gohlke, David; Benjamin, Anne; Gupta, Jay A

    2015-04-22

    As transistors continue to shrink toward nanoscale dimensions, their characteristics are increasingly dependent on the statistical variations of impurities in the semiconductor material. The scanning tunneling microscope (STM) can be used to not only study prototype devices with atomically precise placement of impurity atoms, but can also probe how the properties of these impurities depend on the local environment. Tunneling spectroscopy of Mn acceptors in GaAs indicates that surface-layer Mn act as a deep acceptor, with a hole binding energy that can be tuned by positioning charged defects nearby. Band bending induced by the tip or by these defects can also tune the ionization state of the acceptor complex, evident as a ring-like contrast in STM images. The interplay of these effects is explored over a wide range of defect distances, and understood using iterative simulations of tip-induced band bending. PMID:25782688

  9. Lithography-Free Fabrication of Core-Shell GaAs Nanowire Tunnel Diodes.

    PubMed

    Darbandi, A; Kavanagh, K L; Watkins, S P

    2015-08-12

    GaAs core-shell p-n junction tunnel diodes were demonstrated by combining vapor-liquid-solid growth with gallium oxide deposition by atomic layer deposition for electrical isolation. The characterization of an ensemble of core-shell structures was enabled by the use of a tungsten probe in a scanning electron microscope without the need for lithographic processing. Radial tunneling transport was observed, exhibiting negative differential resistance behavior with peak-to-valley current ratios of up to 3.1. Peak current densities of up to 2.1 kA/cm(2) point the way to applications in core-shell photovoltaics and tunnel field effect transistors. PMID:26189994

  10. Cryogenic ultra-low power dissipation operational amplifiers with GaAs JFETs

    NASA Astrophysics Data System (ADS)

    Hibi, Yasunori; Matsuo, Hiroshi; Ikeda, Hirokazu; Fujiwara, Mikio; Kang, Lin; Chen, Jian; Wu, Peiheng

    2016-01-01

    To realize a multipixel camera for astronomical observation, we developed cryogenic multi-channel readout systems using gallium arsenide junction field-effect transistor (GaAs JFET) integrated circuits (ICs). Based on our experience with these cryogenic ICs, we designed, manufactured, and demonstrated operational amplifiers requiring four power supplies and two voltage sources. The amplifiers operate at 4.2 K with an open-loop gain of 2000. The gain-bandwidth product can expect 400 kHz at a power dissipation of 6 μW. In performance evaluations, the input-referred voltage noise was 4 μVrms/Hz0.5 at 1 Hz and 30 nVrms/Hz0.5 at 10 kHz, respectively. The noise power spectrum density was of type 1/f and extended to 10 kHz.

  11. 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).

  12. High Electron Mobility Transistors For Millimeter Wave And High Speed Digital IC Applications

    NASA Astrophysics Data System (ADS)

    Gupta, Aditya K.; Higgins, J. A.; Lee, Chien-Ping

    1988-02-01

    High Electron Mobility Transistors (HEMTs) are currently regarded as the most promising three-terminal devices for ultra-high-speed digital and monolithic millimeter-wave integrated circuits. In their most basic form, these devices consist of a GaAs-MESFET-like FET fabricated on a (A1,Ga)As/GaAs epitaxial layer. The (A1,Ga)As layer is highly doped n-type and the GaAs layer is undoped. Due to the lower electron affinity of (A1,Ga)As, free electrons diffuse out of the doped layer into undoped GaAs where they form a two-dimensional electron gas near the heterointerface. Since the electrons and ionized donors are spatially separated, ionized impurity scattering is reduced and electron transport properties at the heterointerface are comparable to pure GaAs. FETs fabricated on these hetero-junctions offer many advantages such as (i) a small gate-to-channel separation which leads to extremely high transconductances; (ii) high f due to improved electron transport properties; (iii) a small source resistance; and (ivy a small saturation voltage. The benefits improve substantially upon cooling the device. In a mere seven years, HEMT technology has evolved from simple ring oscillators to circuits of LSI complexity such as 16K SRAMs. The speed performance demonstrated by this relatively immature technology has already surpassed all other semiconductor technologies. Ring oscillator gate delays of 5.8 ps at 77K and 10.2 ps at 300K have been achieved using'0.35 μm gate length devices. In the analog domain, HEMTs are the leaders in low noise and high gain amplification. At room temperatures, devices with a noise figure of 2.4 dB at 62 GHz and fmax > 250 GHz have been demonstrated.

  13. Characterization of LT GaAs carrier lifetime in multilayer GaAs epitaxial wafers by the transient reflectivity technique

    SciTech Connect

    McMorrow, D.; Melinger, J.S.; Campbell, A.B.; Knudson, A.R.; Buchner, S.; Ikossi-Anastasiou, K.; Moss, S.C.; Engelhardt, D.; Childs, T.

    1997-12-01

    A methodology for determining the carrier lifetime of LT GaAs buffer layers in GaAs multilayer wafers utilizing the femtosecond transient reflectivity technique is introduced. Experimental results and computer simulations performed as a function of the LT GaAs growth temperature are presented for the multilayer GaAs structures that are used for device fabrication. The markedly non-exponential nature of the measured transients is a consequence of the multilayer structure of the wafers. The carrier lifetime measurements are correlated with available SEU data measured for structures fabricated with LT GaAs buffers with different growth temperatures.

  14. Optically-Activated GaAs Switches for Ground Penetrating Radar and Firing Set Applications

    SciTech Connect

    Aurand, J.; Brown, D.J.; Carin, L.; Denison, G.J.; Helgeson, W.D.; Loubriel, G.M.; Mar, A.; O'Malley, M.W.; Rinehart, L.F.; Zutavern, F.J.

    1999-07-14

    Optically activated, high gain GaAs switches are being tested for many different applications. TWO such applications are ground penetrating radar (GPR) and firing set switches. The ability of high gain GaAs Photoconductive Semiconductor Switches (PCSs) to deliver fast risetime pulses makes them suitable for their use in radars that rely on fast impulses. This type of direct time domain radar is uniquely suited for the detection of buried items because it can operate at low frequency, high average power, and close to the ground, greatly increasing power on target. We have demonstrated that a PCSs based system can be used to produce a bipolar waveform with a total duration of about 6 ns and with minimal ringing. Such a pulse is radiated and returns from a 55 gallon drum will be presented. For firing sets, the switch requirements include small size, high current, dc charging, radiation hardness and modest longevity. We have switched 1 kA at 1 kV and 2.8 kA at 3 kV dc charge.

  15. GaAs Solar Cell Radiation Handbook

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.

    1996-01-01

    History of GaAs solar cell development is provided. Photovoltaic equations are described along with instrumentation techniques for measuring solar cells. Radiation effects in solar cells, electrical performance, and spacecraft flight data for solar cells are discussed. The space radiation environment and solar array degradation calculations are addressed.

  16. 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

  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. 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…

  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. Ballistic superconductivity in high mobility two dimensional electron gas in GaAs heterostructures

    NASA Astrophysics Data System (ADS)

    Wan, Zhong; Kazakov, Aleksandr; Manfra, Michael; Pfeiffer, Loren; West, Ken; Rokhinson, Leonid

    2015-03-01

    Introduction of a Josephson field effect transistor (JoFET) concept sparked active research on proximity effects in semiconductors. Induced superconductivity and electrostatic control of critical current has been demonstrated in two-dimensional gases in InAs, graphene and topological insulators, and in one-dimensional systems including quantum spin Hall edges. Recently, interest in superconductor-semiconductor interfaces was renewed by the search for non-Abelian states when fractional quantum Hall edge states interface with superconductivity. However, the highest mobility 2D gases in GaAs, where variety of strongly correlated states including fractional quantum Hall effect can be observed, are notoriously absent from the list of materials where superconductivity have been induced. We report formation of transparent superconducting contacts to the high mobility 2DEG in GaAs and demonstrate induced superconductivity across several microns. Ballistic supercurrent has been observed across 0.6 μm of 2DEG, a regime essential to the formation of well separated non-Abelian states. High critical fields (> 16 Tesla) in NbN contacts enables investigation of a regime of an interplay between superconductivity and strongly correlated states in a 2DEG at high magnetic fields.

  1. Ionizing radiation response of GaAs JFETs and DCFL circuits

    SciTech Connect

    Zuleeg, R.; Notthoff, J.K.; Troeger, G.L.

    1982-12-01

    Transient responses and logic upset threshold dose rates of planar, all-ion implanted GaAs E-JFETs and DCFL (= direct-coupled field-effect transistor logic) integrated circuits to ionizing radiation pulses of 20 ns duration from a LINAC are reported. It is experimentally verified that the logic upset dose rate of enhancement mode GaAs JFET integrated circuits is inversely proportional to the square of their channel length. For L = 1 ..mu..m a theoretical value of UPSILON /SUB UPSET/ = 1.175 x 10/sup 11/ rad (GaAs)/s is predicted and medium scale integrated circuits have confirmed this value with experimental results in the range of 5 x 10/sup 10/ to 1 x 10/sup 11/ rad (GaAs)/s. A theoretical relation for logic upset dose rate and a correlation of experimental results with theory is presented. Long term conductance transients are not inherent to E-JFET inverters with resistive and depletion mode JFET load, but are present in source-follower circuits. A model for this circuit behavior will be presented.

  2. Modulating the morphology and electrical properties of GaAs nanowires via catalyst stabilization by oxygen.

    PubMed

    Han, Ning; Yang, Zaixing; Wang, Fengyun; Yip, SenPo; Dong, Guofa; Liang, Xiaoguang; Hung, TakFu; Chen, Yunfa; Ho, Johnny C

    2015-03-11

    Nowadays, III-V compound semiconductor nanowires (NWs) have attracted extensive research interest because of their high carrier mobility favorable for next-generation electronics. However, it is still a great challenge for the large-scale synthesis of III-V NWs with well-controlled and uniform morphology as well as reliable electrical properties, especially on the low-cost noncrystalline substrates for practical utilization. In this study, high-density GaAs NWs with lengths >10 μm and uniform diameter distribution (relative standard deviation σ ∼ 20%) have been successfully prepared by annealing the Au catalyst films (4-12 nm) in air right before GaAs NW growth, which is in distinct contrast to the ones of 2-3 μm length and widely distributed of σ ∼ 20-60% of the conventional NWs grown by the H2-annealed film. This air-annealing process is found to stabilize the Au nanoparticle seeds and to minimize Ostwald ripening during NW growth. Importantly, the obtained GaAs NWs exhibit uniform p-type conductivity when fabricated into NW-arrayed thin-film field-effect transistors (FETs). Moreover, they can be integrated with an n-type InP NW FET into effective complementary metal oxide semiconductor inverters, capable of working at low voltages of 0.5-1.5 V. All of these results explicitly demonstrate the promise of these NW morphology and electrical property controls through the catalyst engineering for next-generation electronics. PMID:25700210

  3. Subnanosecond photoconductive switching in GaAs

    NASA Astrophysics Data System (ADS)

    Druce, R. L.; Pocha, M. D.; Griffin, K. L.

    1991-04-01

    We are conducting research in photoconductive switching for the purpose of generating microwave pulses with amplitudes up to 50 kV. This technology has direct application to impulse radar and HPM sources. We are exploiting the very fast recombination rates of Gallium Arsenide (GaAs) to explore the potential of GaAs as an on-off switch when operating in the linear mode (the linear mode is defined such that one carrier pair is generated for each photon absorbed). In addition, we are exploring the potential GaAs to act as a closing switch in 'avalanche' mode at high fields. We have observed switch closing times of less than 200 psec with a 100 psec duration laser pulse and opening times of less than 400 psec with neutron irradiated GaAs at fields of tens of kV/cm. If the field is increased and the laser energy decreased, the laser can be used to trigger photoconductive switches into 'avalanche' mode of operation in which carrier multiplication occurs. This mode of operation is quite promising since the switches close in less than 1 nsec while realizing significant energy gain (ratio of electrical energy in the pulse to optical trigger energy). We are currently investigating both large area (1 sq cm) and small area (less than 1 sq mm) switches illuminated by GaAlAs laser diodes at 900 nm and Nd:YAG lasers at 1.06 micrometers. Preliminary results indicate that the closing time of the avalanche switches depends primarily on the material properties of the devices with closing times of 300-1300 psec at voltages of 6-35 kV. We will present experimental results for linear, lock on, and avalanche mode operation of GaAs photoconductive switches and how these pulses may be applied to microwave generation.

  4. Subnanosecond photoconductive switching in GaAs

    NASA Astrophysics Data System (ADS)

    Druce, R. L.; Pocha, M. D.; Griffin, K. L.

    We are conducting research in photoconductive switching for the purpose of generating microwave pulses with amplitudes up to 50 kV. This technology has direct application to impulse radar and HPM sources. We are exploiting the very fast recombination rates of Gallium Arsenide (GaAs) to explore the potential of GaAs as an on-off switch when operating in the linear mode (the linear mode is defined such that one carrier pair is generated for each photon absorbed). In addition, we are exploring the potential of GaAs to act as a closing switch in avalanche mode at high fields. We have observed switch closing times of less than 200 psec with 100 psec duration laser pulse and opening times of less than 400 psec with neutron irradiated GaAs at fields of tens of kV/cm. If the field is increased and the laser energy decreased, the laser can be used to trigger photoconductive switches into an avalanche mode of operation in which carrier multiplication occurs. This mode of operation is quite promising since the switches close in less than 1 nsec while realizing significant energy gain (ratio of electrical energy in the pulse to optical trigger energy). We are currently investigating both large area (1 sq cm) and small area (less than 1 sq mm) switches illuminated by GaAlAs laser diodes at 900 nm and Nd:YAG lasers at 1.06 micrometers. Preliminary results indicate that the closing time of the avalanche switches depends primarily on the material properties of the devices with closing times of 300 to 1300 psec at voltages of 6 to 35 kV. We will present experimental results for linear, lock on and avalanche mode operation of GaAs photoconductive switches and how these pulses may be applied to microwave generation.

  5. 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 bipolarity is one of the great questions facing the field and one that is likely to have profound treatment implications, given that fact that such a discovery would greatly increase our ability to individualize – and by extension, enhance – treatment. PMID:25202283

  6. 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

  7. High transconductance organic electrochemical transistors

    NASA Astrophysics Data System (ADS)

    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.

    2013-07-01

    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.

  8. High transconductance organic electrochemical transistors.

    PubMed

    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

  9. 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.

  10. Acoustic Wave Chemical Microsensors in GaAs

    SciTech Connect

    Albert G. Baca; Edwin J. Heller; Gregory C. Frye-Mason; John L. Reno; Richard Kottenstette; Stephen A. Casalnuovo; Susan L. Hietala; Vincent M. Hietala

    1998-09-20

    High sensitivity acoustic wave chemical microsensors are being developed on GaAs substrates. These devices take advantage of the piezoelectric properties of GaAs as well as its mature microelectronics fabrication technology and nascent micromachining technology. The design, fabrication, and response of GaAs SAW chemical microsensors are reported. Functional integrated GaAs SAW oscillators, suitable for chemical sensing, have been produced. The integrated oscillator requires 20 mA at 3 VK, operates at frequencies up to 500 MHz, and occupies approximately 2 mmz. Discrete GaAs sensor components, including IC amplifiers, SAW delay lines, and IC phase comparators have been fabricated and tested. A temperature compensation scheme has been developed that overcomes the large temperature dependence of GaAs acoustic wave devices. Packaging issues related to bonding miniature flow channels directly to the GaAs substrates have been resolved. Micromachining techniques for fabricating FPW and TSM microsensors on thin GaAs membranes are presented and GaAs FPW delay line performance is described. These devices have potentially higher sensitivity than existing GaAs and quartz SAW sensors.

  11. 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.

  12. 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

  13. Vertical Silicon Nanowire Field Effect Transistors with Nanoscale Gate-All-Around

    NASA Astrophysics Data System (ADS)

    Guerfi, Youssouf; Larrieu, Guilhem

    2016-04-01

    Nanowires are considered building blocks for the ultimate scaling of MOS transistors, capable of pushing devices until the most extreme boundaries of miniaturization thanks to their physical and geometrical properties. In particular, nanowires' suitability for forming a gate-all-around (GAA) configuration confers to the device an optimum electrostatic control of the gate over the conduction channel and then a better immunity against the short channel effects (SCE). In this letter, a large-scale process of GAA vertical silicon nanowire (VNW) MOSFETs is presented. A top-down approach is adopted for the realization of VNWs with an optimum reproducibility followed by thin layer engineering at nanoscale. Good overall electrical performances were obtained, with excellent electrostatic behavior (a subthreshold slope (SS) of 95 mV/dec and a drain induced barrier lowering (DIBL) of 25 mV/V) for a 15-nm gate length. Finally, a first demonstration of dual integration of n-type and p-type VNW transistors for the realization of CMOS inverter is proposed.

  14. Vertical Silicon Nanowire Field Effect Transistors with Nanoscale Gate-All-Around.

    PubMed

    Guerfi, Youssouf; Larrieu, Guilhem

    2016-12-01

    Nanowires are considered building blocks for the ultimate scaling of MOS transistors, capable of pushing devices until the most extreme boundaries of miniaturization thanks to their physical and geometrical properties. In particular, nanowires' suitability for forming a gate-all-around (GAA) configuration confers to the device an optimum electrostatic control of the gate over the conduction channel and then a better immunity against the short channel effects (SCE). In this letter, a large-scale process of GAA vertical silicon nanowire (VNW) MOSFETs is presented. A top-down approach is adopted for the realization of VNWs with an optimum reproducibility followed by thin layer engineering at nanoscale. Good overall electrical performances were obtained, with excellent electrostatic behavior (a subthreshold slope (SS) of 95 mV/dec and a drain induced barrier lowering (DIBL) of 25 mV/V) for a 15-nm gate length. Finally, a first demonstration of dual integration of n-type and p-type VNW transistors for the realization of CMOS inverter is proposed. PMID:27094824

  15. 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.

  16. LEC GaAs for integrated circuit applications

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, C. G.; Chen, R. T.; Homes, D. E.; Asbeck, P. M.; Elliott, K. R.; Fairman, R. D.; Oliver, J. D.

    1984-01-01

    Recent developments in liquid encapsulated Czochralski techniques for the growth of semiinsulating GaAs for integrated circuit applications have resulted in significant improvements in the quality and quantity of GaAs material suitable for device processing. The emergence of high performance GaAs integrated circuit technologies has accelerated the demand for high quality, large diameter semiinsulating GaAs substrates. The new device technologies, including digital integrated circuits, monolithic microwave integrated circuits and charge coupled devices have largely adopted direct ion implantation for the formation of doped layers. Ion implantation lends itself to good uniformity and reproducibility, high yield and low cost; however, this technique also places stringent demands on the quality of the semiinsulating GaAs substrates. Although significant progress was made in developing a viable planar ion implantation technology, the variability and poor quality of GaAs substrates have hindered progress in process development.

  17. GaAs shallow-homojunction solar cells

    NASA Technical Reports Server (NTRS)

    Fan, J. C. C.

    1981-01-01

    The feasibility of fabricating space resistant, high efficiency, light weight, low cost GaAs shallow homojunction solar cells for space application is investigated. The material preparation of ultrathin GaAs single crystal layers, and the fabrication of efficient GaAs solar cells on bulk GaAs substrates are discussed. Considerable progress was made in both areas, and conversion efficiency about 16% AMO was obtained using anodic oxide as a single layer antireflection coating. A computer design shows that even better cells can be obtained with double layer antireflection coating. Ultrathin, high efficiency solar cells were obtained from GaAs films prepared by the CLEFT process, with conversion efficiency as high as 17% at AMI from a 10 micrometers thick GaAs film. A organometallic CVD was designed and constructed.

  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. A new generation of space power - GaAs solar cell

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongwei; Shi, Wencao

    1991-11-01

    This paper describes the status and trend of GaAs solar cell development. The significance of GaAs solar cell properties for space applications are pointed out. The prospects for GaAs solar cell usage are addressed.

  20. Bipolar disorder in old age.

    PubMed Central

    Shulman, K. I.; Herrmann, N.

    1999-01-01

    OBJECTIVE: To review the classification, clinical characteristics, and epidemiology of bipolar disorders in old age with a special focus on neurologic comorbidity, high mortality, and management. QUALITY OF EVIDENCE: Most available data is gleaned from retrospective chart reviews and cohort studies. Treatment recommendations are based on evidence from younger populations and a few anecdotal case reports and series involving elderly people. MAIN MESSAGE: While relatively rare in the community setting, mania in old age frequently leads to hospitalization. It is associated with late-onset neurologic disorders (especially cerebrovascular disease) involving the right hemisphere and orbitofrontal cortex. Prognosis is relatively poor; morbidity and mortality rates are high. Management of bipolarity includes cautious use of mood stabilizers, especially lithium and divalproex. CONCLUSIONS: Mania in old age should trigger a careful assessment of underlying neurologic disease, especially cerebrovascular disease. Close clinical follow up is essential. PMID:10349067

  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. New generation of space batteries: GaAs solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongwei; Shi, Wenzao

    1995-05-01

    This paper describes a new generation of space power sources -- GaAs solar cells -- and the status of their development inside China and abroad. In conjunction with this, on the basis of unique properties associated with GaAs solar cells, it points out the direction of development, clarifies the value of key space applications, and forecasts the application prospects for GaAs solar cells.

  3. Progress in digital GaAs IC's

    NASA Astrophysics Data System (ADS)

    Perea, Ernesto

    1986-06-01

    The paper describes the status of the activity of one of the most advanced European companies in the field of technology for GaAs monolithic IC's. The main emphasis is concentrated on digital high speed devices where three approaches are followed: custom design, standard cells and gate arrays. The basic process is fully implanted with optical litography for digital IC's while a mixture of Electron beam direct writing and optical lithography is used for most microwave applications.

  4. Piezoelectric field in strained GaAs.

    SciTech Connect

    Chow, Weng Wah; Wieczorek, Sebastian Maciej

    2005-11-01

    This report describes an investigation of the piezoelectric field in strained bulk GaAs. The bound charge distribution is calculated and suitable electrode configurations are proposed for (1) uniaxial and (2) biaxial strain. The screening of the piezoelectric field is studied for different impurity concentrations and sample lengths. Electric current due to the piezoelectric field is calculated for the cases of (1) fixed strain and (2) strain varying in time at a constant rate.

  5. A model for the breakdown characteristics of p-channel MOS transistor protection devices

    NASA Astrophysics Data System (ADS)

    Maes, H.; Six, P.; Sansen, W.

    1981-06-01

    Gate controlled diodes, MOS transistors with grounded gate, source and substrate and gate controlled pnn + structures are compared when used as a protective input device on p-channel MOS integrated circuits. For this purpose two pulse techniques are developed which allow an accurate determination of the dynamic resistance by minimizing the walk-out of the breakdown voltage during the measurement. While the breakdown voltage does not differ much for the different types of devices, the dynamic resistance however is found to be considerably lower for the MOS transistor than for both other devices. For these low values the series resistance of the drain and source diffusion is shown to constitute already an important contribution. The lower dynamic resistance of MOST's can be ascribed to parasitic bipolar transistor operation during breakdown. The identification of this mechanism leads to a simple model for the MOS transistor in breakdown which has been experimentally verified and confirmed. Guidelines for the definition of the source diffusion for an optimal protective functioning can be obtained from this model.

  6. Silicon-compatible compound semiconductor tunneling field-effect transistor for high performance and low standby power operation

    NASA Astrophysics Data System (ADS)

    Cho, Seongjae; Man Kang, In; Kamins, Theodore I.; Park, Byung-Gook; Harris, James S.

    2011-12-01

    In this study, we propose and characterize by simulation a silicon-compatible compound semiconductor tunneling field-effect transistor (TFET) based on germanium (Ge)/gallium arsenide (GaAs) heterojunction aiming the various integrated systems on silicon substrate. By introducing Ge as p+ source and GaAs as the high-mobility channel and n+ drain materials, we maximize on-state current (Ion) and minimize off-state current (Ioff) to obtain a TFET for high performance and low standby power capabilities. The effects of physical parameters such as aluminum content, source-gate overlap length, and gate workfunction on device performance were examined thoroughly. Further, we evaluate its radio frequency performance and confirm that it shows superb current and power gain characteristics.

  7. 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 ... Strike Out Stroke Wise Choices Links Dealing with Bipolar Disorder If you have bipolar disorder, get treatment ...

  8. GaAs photoconductors to characterize picosecond response in GaAs integrated devices and circuits

    SciTech Connect

    Hammond, R.B.; Paulter, N.G.; Gibbs, A.J.

    1986-01-01

    Optoelectronic techniques that use femtosecond lasers and promise the precise measurement of transient response in high speed electronic devices and circuits have been under study for several years. We have investigated on-wafer electrical-impulse generation and sampling using femto-second-laser-excited GaAs photoconductors. This approach is applicable to any transmission line structure, it is directly integrable, non-invasive, jitter-free, and it is applicable to both microwave and digital circuits. We have developed the capability to: (a) generate electrical impulses in on-wafer GaAs transmission lines with 3-dB bandwidths in excess of 60 GHz, and (b) sample the electrical impulse response of an on-wafer test structure without jitter and with a 3-dB measurement bandwidth of 103 GHz at a noise level of -67 dBm. We have studied dispersion in GaAs on-wafer coplanar-waveguide transmission lines.

  9. 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

  10. 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…

  11. Crystal growth of device quality GaAs in space

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Lagowski, J.

    1984-01-01

    The crystal growth, device processing and device related properties and phenomena of GaAs are investigated. Our GaAs research evolves about these key thrust areas. The overall program combines: (1) studies of crystal growth on novel approaches to engineering of semiconductor materials (i.e., GaAs and related compounds); (2) investigation and correlation of materials properties and electronic characteristics on a macro- and microscale; (3) investigation of electronic properties and phenomena controlling device applications and device performance. The ground based program is developed which would insure successful experimentation with and eventually processing of GaAs in a near zero gravity environment.

  12. High efficiency, low cost thin GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Fan, J. C. C.

    1982-01-01

    The feasibility of fabricating space-resistant, high efficiency, light-weight, low-cost GaAs shallow-homojunction solar cells for space application is demonstrated. This program addressed the optimal preparation of ultrathin GaAs single-crystal layers by AsCl3-GaAs-H2 and OMCVD process. Considerable progress has been made in both areas. Detailed studies on the AsCl3 process showed high-quality GaAs thin layers can be routinely grown. Later overgrowth of GaAs by OMCVD has been also observed and thin FaAs films were obtained from this process.

  13. Treatment of Bipolar Depression: Evolving Recommendations.

    PubMed

    Post, Robert M

    2016-03-01

    Bipolar depression is the most common and difficult-to-treat phase of bipolar disorder. Antidepressants for unipolar depression are among the most widely used drugs, but recent data and meta-analyses indicate a lack of efficacy. Many of the drugs discussed here are graded provisionally for the strength of the findings in the literature, safety and tolerability, and likely utility of use in patients with bipolar disorder. Successful long-term treatment of bipolar depression is critical to preventing illness-related morbidity, disability, cognitive decline, suicide, and premature loss of years of life expectancy largely from the excess medical mortality associated with cardiovascular disorders. PMID:26876316

  14. Simulation of novel complementary bipolar inverters for low-voltage high-speed ULSI

    NASA Astrophysics Data System (ADS)

    Bubennikov, Alexander N.; Zykov, Andrey V.

    2000-01-01

    Complementary bipolar (CBi) inverters on scaled down self-aligned transistors with highly-doped bases for advanced high-speed low-voltage low-power deep-submicron ULSI are considered and studied using a simulator PSPICE. A novel symmetrical transistor structure (STS) with undoped (lightly-doped) active base and nanometer regime, that can function as complementary n-p-n and p-n-p devices for CBi inverters at ultra-reduced supply voltages VEE, VEE=0.1-0.5 V, is investigated and simulated. It is shown that numerical mixed 2D-device-circuit simulator (DCSIM) for personal computer gives accurate knowledge of the static and dynamic properties of upward and downward self-aligned STS and CBi inverters eliminating the intermediate nonaccurate procedure of model electrical parameter extraction. This paper presents 2D numerical device-circuit simulations of the bipolar nanostructures and push-pull inverters on complementary STS with undoped active bases in ultra-low-voltage regime providing a high degree of integration, extremely high intrinsic speed and sufficiently high driving capacity. The switching problems for high-speed low-power low-action operations and optimization of sub-0.5 V Cbi inverters are studied.

  15. An ion-gated bipolar amplifier for ion sensing with enhanced signal and improved noise performance

    NASA Astrophysics Data System (ADS)

    Zhang, Da; Gao, Xindong; Chen, Si; Norström, Hans; Smith, Ulf; Solomon, Paul; Zhang, Shi-Li; Zhang, Zhen

    2014-08-01

    This work presents a proof-of-concept ion-sensitive device operating in electrolytes. The device, i.e., an ion-gated bipolar amplifier (IGBA), consists of a modified ion-sensitive field-effect transistor (ISFET) intimately integrated with a vertical bipolar junction transistor for immediate current amplification without introducing additional noise. With the current non-optimized design, the IGBA is already characterized by a 70-fold internal amplification of the ISFET output signal. This signal amplification is retained when the IGBA is used for monitoring pH variations. The tight integration significantly suppresses the interference of the IGBA signal by external noise, which leads to an improvement in signal-to-noise performance compared to its ISFET reference. The IGBA concept is especially suitable for biochips with millions of electric sensors that are connected to peripheral readout circuitry via extensive metallization which may in turn invite external interferences leading to contamination of the signal before it reaches the first external amplification stage.

  16. Are there different genotypes in Bipolar II and Bipolar I disorder and if so, why then do we tend to observe Unipolar Depression converting to Bipolar II and then converting to Bipolar I?

    PubMed

    Fawcett, Martha; Agius, Mark

    2015-09-01

    We review the recent literature in order to establish the importance of a spectrum for bipolar affective disorder, and that unipolar depression, bipolar II and bipolar I are discrete entities that may however evolve in sequence. We discuss clinical, genetic and neurobiological data which illustrate the differences between bipolar I and bipolar II. To fit the data we suggest a series of multiple mood disorder genotypes, some of which evolve into other conditions on the bipolar spectrum. Thence we discuss the nature of the bipolar spectrum and demonstrate how this concept can be used as the basis of a staging model for bipolar disorder. PMID:26417754

  17. 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.

  18. 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.

  19. Social Desirability And Bipolar Affective Disorder

    ERIC Educational Resources Information Center

    Donnelly, Howard F.; Murphy, Dennis L.

    1973-01-01

    Exploring the bipolar (manic-depressive) and the unipolar (depression without mania) subtypes of primary affective disorders, this study determines whether the conforming attitudes of bipolar subjects are related to depression as possible coping mechanisms. The findings explain the less self-reported depression and psychopathology in the bipolar…

  20. Screening for bipolar disorder during pregnancy.

    PubMed

    Merrill, Lindsay; Mittal, Leena; Nicoloro, Jennifer; Caiozzo, Christina; Maciejewski, Paul K; Miller, Laura J

    2015-08-01

    Bipolar disorder is a high-risk condition during pregnancy. In women receiving prenatal care, this study addresses the proportion screening positive for bipolar disorder with or without also screening positive for depression. This is a pilot study using chart abstraction of Edinburgh Postnatal Depression Scale (EPDS) and Mood Disorder Questionnaire (MDQ) scores from patients' initial prenatal visits. Among 342 participants, 289 (87.1 %) completed the EPDS, 277 (81.0 %) completed the MDQ, and 274 (80.1 %) completed both. Among EPDS screens, 49 (16.4 %) were positive. Among MDQ screens, 14 (5.1 %) were positive. Nine (21.4 %) of the 42 participants with a positive EPDS also had a positive MDQ. Of the 14 patients with a positive MDQ, five (35.7 %) had a negative EPDS. The prevalence of positive screens for bipolar disorder in an obstetric population is similar to gestational diabetes and hypertension, which are screened for routinely. Without screening for bipolar disorder, there is a high risk of misclassifying bipolar depression as unipolar depression. If only women with current depressive symptoms are screened for bipolar disorder, approximately one third of bipolar disorder cases would be missed. If replicated, these findings support simultaneous screening for both depression and bipolar disorder during pregnancy. PMID:25968603

  1. Subthreshold bipolarity: diagnostic issues and challenges

    PubMed Central

    Nusslock, Robin; Frank, Ellen

    2012-01-01

    Background Research suggests that current diagnostic criteria for bipolar disorders may fail to include milder, but clinically significant, bipolar syndromes and that a substantial percentage of these conditions are diagnosed, by default, as unipolar major depression. Accordingly, a number of researchers have argued for the upcoming 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) to better account for subsyndromal hypomanic presentations. Methods The present paper is a critical review of research on subthreshold bipolarity, and an assessment of some of the challenges that researchers and clinicians might face if the DSM-5 were designed to systematically document subsyndromal hypomanic presentations. Results Individuals with major depressive disorder (MDD) who display subsyndromal hypomanic features, not concurrent with a major depressive episode, have a more severe course compared to individuals with MDD and no hypomanic features, and more closely resemble individuals with bipolar disorder on a number of clinical validators. Conclusion There are clinical and scientific reasons for systematically documenting subsyndromal hypomanic presentations in the assessment and diagnosis of mood disorders. However, these benefits are balanced with important challenges, including (i) the difficulty in reliably identifying subsyndromal hypomanic presentations, (ii) operationalizing subthreshold bipolarity, (iii) differentiating subthreshold bipolarity from borderline personality disorder, (iv) the risk of over-diagnosing bipolar spectrum disorders, and (v) uncertainties about optimal interventions for subthreshold bipolarity. PMID:22085472

  2. 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.

  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 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…

  7. 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…

  8. 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…

  9. Analysing organic transistors based on interface approximation

    SciTech Connect

    Akiyama, Yuto; Mori, Takehiko; ACT-C, JST, Honcho, Kawaguchi, Saitama 332-0012

    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. Linearity of photoconductive GaAs detectors to pulsed electrons

    SciTech Connect

    Ziegler, L.H.

    1995-12-31

    The response of neutron damaged GaAs photoconductor detectors to intense, fast (50 psec fwhm) pulses of 16 MeV electrons has been measured. Detectors made from neutron damaged GaAs are known to have reduced gain, but significantly improved bandwidth. An empirical relationship between the observed signal and the incident electron fluence has been determined.

  11. Panel fabrication utilizing GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Mardesich, N.

    1984-01-01

    The development of the GaAs solar cells for space applications is described. The activities in the fabrication of GaAs solar panels are outlined. Panels were fabricated while introducing improved quality control, soldering laydown and testing procedures. These panels include LIPS II, San Marco Satellite, and a low concentration panel for Rockwells' evaluation. The panels and their present status are discussed.

  12. Radiation effects in GaAs FET devices

    SciTech Connect

    Zuleeg, R.

    1989-03-01

    This paper reviews the effects space and nuclear radiation have on GaAs devices utilized for integrated circuit design. The hardness capability of contemporary GaAs devices and logic circuits is presented in terms of four major nuclear and space radiation threat categories: total dose effects, dose rate effects, single particle phenomena, and neutron effects.

  13. 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 system power = 100 kilowatts; discharge time = 30 seconds; discharge current density = 1.75 amps/sq in.; system weight = 86 lbs (9.7 WH/lb); and system volume = 1071 cu. in. (.78 WH/cu. in.). EPI is currently working on a development program to produce a bipolar silver-zinc battery design for NASA. The potential application would be to power electromechanical actuators for space launch vehicles.

  14. Assessment Tools for Adult Bipolar Disorder

    PubMed Central

    Miller, Christopher J.; Johnson, Sheri L.; Eisner, Lori

    2010-01-01

    This article reviews the current state of the literature on the assessment of bipolar disorder in adults. Research on reliable and valid measures for bipolar disorder has unfortunately lagged behind assessment research for other disorders, such as major depression. We review diagnostic tools, self-report measures to facilitate screening for bipolar diagnoses, and symptom severity measures. We briefly review other assessment domains, including measures designed to facilitate self-monitoring of symptoms. We highlight particular gaps in the field, including an absence of research on the reliable diagnosis of bipolar II and milder forms of disorder, a lack of empirical data on the best ways to integrate data from multiple domains, and a shortage of measures targeting a broader set of illness-related constructs relevant to bipolar disorder. PMID:20360999

  15. Adolescent Bipolar Disorder: A Clinical Vignette

    PubMed Central

    Rodgers, Melissa J.; McKay, Julia B.; Solomon, A. Lee; Choby, Beth A.

    2010-01-01

    Adolescence is a vulnerable developmental phase marked by physical, psychological, and social changes that rapidly expose young people to a wide range of new stressors. When differentiating between bipolar disorder and teenage “acting out,” a careful history is important. Adolescent bipolar disorder is a psychiatric illness characterized by fluctuating episodes of mood elevation and depression that is frequently neither recognized nor formally diagnosed. Adolescents with bipolar disorder often manifest a more nonepisodic, chronic course with continuous rapid-cycling patterns than do adults. Pharmacologic treatment of adolescent bipolar disorder is difficult and often requires combination therapy to address comorbidities like attention-deficit/hyperactivity disorder and anxiety disorder. Adjuncts to pharmacologic treatment of bipolar disorder can be beneficial. Psychosocial treatments include family education, enhanced parenting techniques, stress management, and the development of effective coping strategies. PMID:21085549

  16. Integrating bipolar disorder management in primary care.

    PubMed

    Kilbourne, Amy M; Goodrich, David E; O'Donnell, Allison N; Miller, Christopher J

    2012-12-01

    There is growing realization that persons with bipolar disorder may exclusively be seen in primary (general medical) care settings, notably because of limited access to mental health care and stigma in seeking mental health treatment. At least two clinical practice guidelines for bipolar disorder recommend collaborative chronic care models (CCMs) to help integrate mental health care to better manage this illness. CCMs, which include provider guideline support, self-management support, care management, and measurement-based care, are well-established in primary care settings, and may help primary care practitioners manage bipolar disorder. However, further research is required to adapt CCMs to support complexities in diagnosing persons with bipolar disorder, and integrate decision-making processes regarding medication safety and tolerability in primary care. Additional implementation studies are also needed to adapt CCMs for persons with bipolar disorder in primary care, especially those seen in smaller practices with limited infrastructure and access to mental health care. PMID:23001382

  17. 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.

  18. 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

  19. Coaxial Inverted Geometry Epitaxial Transistor

    NASA Technical Reports Server (NTRS)

    Hruby, R. J.; Dunn, W. R.; Cress, S. B.

    1972-01-01

    Silicon transistor, developed for use in biotelemetry circuits, provides high current gain at low levels of power and voltage. Device operates from biopotential or miniature batteries and is suitable for incorporation into monolithic integrated circuits. Coaxial configuration and small size offer promise for high frequency application.

  20. Peeled film GaAs solar cell development

    NASA Technical Reports Server (NTRS)

    Wilt, D. M.; Thomas, R. D.; Bailey, S. G.; Brinker, D. J.; Deangelo, F. L.

    1990-01-01

    Thin-film, single-crystal gallium arsenide (GaAs) solar cells could exhibit a specific power approaching 700 W/kg including coverglass. A simple process has been described whereby epitaxial GaAs layers are peeled from a reusable substrate. This process takes advantage of the extreme selectivity of the etching rate of aluminum arsenide (AlAs) over GaAs in dilute hydrofluoric acid. The feasibility of using the peeled film technique to fabricate high-efficiency, low-mass GaAs solar cells is presently demonstrated. A peeled film GaAs solar cell was successfully produced. The device, although fractured and missing the aluminum gallium arsenide window and antireflective coating, had a Voc of 874 mV and a fill factor of 68 percent under AM0 illumination.

  1. Peeled film GaAs solar cell development

    NASA Astrophysics Data System (ADS)

    Wilt, D. M.; Thomas, R. D.; Bailey, S. G.; Brinker, D. J.; Deangelo, F. L.

    Thin-film, single-crystal gallium arsenide (GaAs) solar cells could exhibit a specific power approaching 700 W/kg including coverglass. A simple process has been described whereby epitaxial GaAs layers are peeled from a reusable substrate. This process takes advantage of the extreme selectivity of the etching rate of aluminum arsenide (AlAs) over GaAs in dilute hydrofluoric acid. The feasibility of using the peeled film technique to fabricate high-efficiency, low-mass GaAs solar cells is presently demonstrated. A peeled film GaAs solar cell was successfully produced. The device, although fractured and missing the aluminum gallium arsenide window and antireflective coating, had a Voc of 874 mV and a fill factor of 68 percent under AM0 illumination.

  2. 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

  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 preliminary support. PMID:25554538

  4. Diffractively structured GaAs EOIR windows

    NASA Astrophysics Data System (ADS)

    Wilson, Michael; Coulter, Phillip; Hammer, Jay A.; Borek, Gregg T.

    2005-05-01

    A process to diffractively structure GaAs for enhanced optical performance is described. The benefits of diffractively structuring an EOIR window material include improved FOR/FOV, consistent broadband performance, the ability to design and implement hyper-spectral characteristics directly into the substrate without incorporating a complex anti-reflective coating. Progress to date will be discussed including design evolution, process implementation, and optical characterization using the Automated Rasterable Integrated Spectrometer and TIS Measurement System (ARISTMS). Results will be presented on 100mm diameter samples.

  5. Optical absorptions of polyfluorene transistors

    NASA Astrophysics Data System (ADS)

    Deng, Yvonne Y.; Sirringhaus, Henning

    2005-07-01

    Conjugated polymers are a promising class of materials for organic electronics. While the progress in device performance is impressive, the basics of charge transport still pose many open questions. Specifically, conduction at the comparatively rough polymer-polymer interface in an all-polymer field-effect transistor is expected to be different from a sharp interface with an inorganic dielectric, such as silicon dioxide. In this work, charge modulation spectroscopy (CMS) is used to study the optical absorptions in the presence of charges in situ in the transistor structure. This allows direct observation of the charge carriers in the operational device via their spectroscopic signature; the technique is by design very sensitive to the properties of the semiconductor-dielectric interface. The semiconducting copolymer poly( 9,9' -dioctyl-fluorene-co-bithiophene) (F8T2) is incorporated into a top-gate thin-film transistor structure with a polymer dielectric layer deposited by spin coating and inkjet-printed polymer electrodes. A prominent charge-induced absorption at 1.65eV is observed as well as a shoulder at 1.3eV and a tail extending toward the absorption edge. The bias dependence of the CMS signature confirms that intermixing of the polymer layers is minimal, as expected from the excellent transistor characteristics. Polarization-dependent CMS measurements on aligned transistors show that the main feature at 1.65eV is strongly polarized whereas the shoulder is unpolarized. This observation, as well as further experimental evidence, lead to the conclusion that while the main absorption is attributable to the intrinsic, polaronic absorption in F8T2, the shoulder is likely to originate from a defect state.

  6. Forecasting depression in bipolar disorder.

    PubMed

    Moore, Paul J; Little, Max A; McSharry, Patrick E; Geddes, John R; Goodwin, Guy M

    2012-10-01

    Bipolar disorder is characterized by recurrent episodes of mania and depression and affects about 1% of the adult population. The condition can have a major impact on an individual's ability to function and is associated with a long-term risk of suicide. In this paper, we report on the use of self-rated mood data to forecast the next week's depression ratings. The data used in the study have been collected using SMS text messaging and comprises one time series of approximately weekly mood ratings for each patient. We find a wide variation between series: some exhibit a large change in mean over the monitored period and there is a variation in correlation structure. Almost half of the time series are forecast better by unconditional mean than by persistence. Two methods are employed for forecasting: exponential smoothing and Gaussian process regression. Neither approach gives an improvement over a persistence baseline. We conclude that the depression time series from patients with bipolar disorder are very heterogeneous and that this constrains the accuracy of automated mood forecasting across the set of patients. However, the dataset is a valuable resource and work remains to be done that might result in clinically useful information and tools. PMID:22855220

  7. Bipolar disorder: Mania and depression.

    PubMed

    Belmaker, R H; Bersudsky, Yuly

    2004-10-01

    Extract: Bipolar disorder is one of the most distinct syndromes in psychiatry and has been described in numerous cultures over the course of history, in a manner that suggests considerable similarity of the syndrome in time and place. The unique phase of the illness is mania. However, depression can be the most prominent phase and the ratio of depressions to manias over the life course of the illness is highly variable. Depression in a bipolar disorder is a syndrome that can be understood by any human being, as all of us have experienced sadness and there are at least some commonalities between normal sadness and the state of depression. Mania is often difficult to explain to someone who has not seen a manic patient. In many ways, mania is the opposite of depression and is characterized by the following: an elevated mood or euphoria, an overactivity with a lack of the need for sleep, and an increased optimism that usually becomes so severe that the patient's judgment is impaired and they may make decisions based on their optimism such as the purchase of 500 television sets if they believe that the merchandise will go up in price. PMID:20704954

  8. 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

  9. [Neuroimmunology of bipolar affective disorder].

    PubMed

    Remlinger-Molenda, Agnieszka; Rybakowski, Janusz

    2010-01-01

    Previous neuroimmunological studies focused mostly on depression, regardless of its diagnostic category. In this paper, the studies on the immunological system in patients with bipolar affective illness, including manic episode, have been presented. Research possibilities of neuroimmunology of affective disorders using molecular-genetic methods have also been shown. The studies on the neuroimmunology of depression have always been connected with studies on changes in the immunological system related to stress situations. Disturbances of the immunological system regulation have features of either decrease or pathological increase of the immunological system, with increased activity of pro-inflammatory cytokines (interleukin 1 and 6, interferon). Some pathogenic role for the disturbances of immunological system in depression is also played by viral infections (herpes, Borna viruses). The changes of the immunological system in mania are mostly similar to those observed during depression. An increase of activity of pro-inflammatory cytokines, connected with the lymphocyte Th1 system is especially evident. Like in depression, the role of viral infections has been pointed out (herpes, Borna, parvovirus B19). The oldest mood-stabilizing drug, lithium, has been shown to have strong action against herpes viruses. Molecular-genetic studies point to an association of some genes of the immunological system with both bipolar disorder and schizophrenia. An association of some genes with a predisposition to depression and efficacy of antidepressant drugs has also been shown. PMID:20449978

  10. Au impact on GaAs epitaxial growth on GaAs (111){sub B} substrates in molecular beam epitaxy

    SciTech Connect

    Liao, Zhi-Ming; Chen, Zhi-Gang; Xu, Hong-Yi; Guo, Ya-Nan; Sun, Wen; Zhang, Zhi; Yang, Lei; Lu, Zhen-Yu; Chen, Ping-Ping; Lu, Wei; Zou, Jin; Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, Queensland 4072

    2013-02-11

    GaAs growth behaviour under the presence of Au nanoparticles on GaAs {l_brace}111{r_brace}{sub B} substrate is investigated using electron microscopy. It has been found that, during annealing, enhanced Ga surface diffusion towards Au nanoparticles leads to the GaAs epitaxial growth into {l_brace}113{r_brace}{sub B} faceted triangular pyramids under Au nanoparticles, governed by the thermodynamic growth, while during conventional GaAs growth, growth kinetics dominates, resulting in the flatted triangular pyramids at high temperature and the epitaxial nanowires growth at relatively low temperature. This study provides an insight of Au nanoparticle impact on GaAs growth, which is critical for understanding the formation mechanisms of semiconductor nanowires.

  11. Implantation of carbon in GaAs

    SciTech Connect

    Moll, A.J.

    1992-03-01

    Carbon implanted into GaAs and thermally annealed typically exhibits very low (<3%) electrical activity. It has been demonstrated that the electrical activity of C can be significantly enhanced by co-implantation with Ga. Improved activation may result from either additional damage of the crystal lattice or from stoichiometric changes, forcing the C atoms onto As sites. To determine the relative importance of each of these effects, I have undertaken a systematic study of carbon activation in GaAs. A range of co-implants have been used: group III (B, Ga), group V (N, P, As) and noble gases (Ar, Kr). The damage introduced to the substrate will depend on the mass of the ion implanted. The group III and group V co-implants will affect the crystal stoichiometry. The results indicate that both lattice damage and crystal stoichiometry are important for high electrical activity of C. Increasing the damage will increase the activation due to the increased number of As vacancies but maximum activation can be obtained only by a co-implant which not only damages the lattice but also forces the C to occupy an As site.

  12. Attentional bias in euthymic bipolar I disorder.

    PubMed

    Peckham, Andrew D; Johnson, Sheri L; Gotlib, Ian H

    2016-04-01

    Little is known about the nature of the relation between information-processing biases and affective traits in bipolar disorder. The present study was designed to investigate whether attentional biases are evident in persons diagnosed with bipolar disorder when they are in a positive mood state, and whether biases are related to indices of emotion regulation and to prior history of mood episodes. Ninety adults diagnosed with bipolar I disorder and 81 controls with no lifetime mood disorder underwent a positive mood induction and then completed an emotion face dot-probe task; participants in the bipolar disorder group also completed a self-report measure of responses to positive affect. Attentional bias was not related to a diagnosis of bipolar disorder or to symptom severity. Consistent with hypotheses, analyses within the bipolar group indicated that greater dampening of positive affect related to significantly less attention paid to the positively valenced faces. Discussion focuses on the potential role of affective traits in shaping attentional bias in bipolar disorder. PMID:25757517

  13. High-Speed Planar GaAs Nanowire Arrays with fmax > 75 GHz by Wafer-Scale Bottom-up Growth.

    PubMed

    Miao, Xin; Chabak, Kelson; Zhang, Chen; Mohseni, Parsian K; Walker, Dennis; Li, Xiuling

    2015-05-13

    Wafer-scale defect-free planar III-V nanowire (NW) arrays with ∼100% yield and precisely defined positions are realized via a patterned vapor-liquid-solid (VLS) growth method. Long and uniform planar GaAs NWs were assembled in perfectly parallel arrays to form double-channel T-gated NW array-based high electron mobility transistors (HEMTs) with DC and RF performance surpassing those for all field-effect transistors (FETs) with VLS NWs, carbon nanotubes (CNTs), or graphene channels in-plane with the substrate. For a planar GaAs NW array-based HEMT with 150 nm gate length and 2 V drain bias, the on/off ratio (ION/IOFF), cutoff frequency (fT), and maximum oscillation frequency (fmax) are 10(4), 33, and 75 GHz, respectively. By characterizing more than 100 devices on a 1.5 × 1.5 cm(2) chip, we prove chip-level electrical uniformity of the planar NW array-based HEMTs and verify the feasibility of using this bottom-up planar NW technology for post-Si large-scale nanoelectronics. PMID:25494481

  14. 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

  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. 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

  17. 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

  18. The development of integrated chemical microsensors in GaAs

    SciTech Connect

    CASALNUOVO,STEPHEN A.; ASON,GREGORY CHARLES; HELLER,EDWIN J.; HIETALA,VINCENT M.; BACA,ALBERT G.; HIETALA,S.L.

    1999-11-01

    Monolithic, integrated acoustic wave chemical microsensors are being developed on gallium arsenide (GaAs) substrates. With this approach, arrays of microsensors and the high frequency electronic components needed to operate them reside on a single substrate, increasing the range of detectable analytes, reducing overall system size, minimizing systematic errors, and simplifying assembly and packaging. GaAs is employed because it is both piezoelectric, a property required to produce the acoustic wave devices, and a semiconductor with a mature microelectronics fabrication technology. Many aspects of integrated GaAs chemical sensors have been investigated, including: surface acoustic wave (SAW) sensors; monolithic SAW delay line oscillators; GaAs application specific integrated circuits (ASIC) for sensor operation; a hybrid sensor array utilizing these ASICS; and the fully monolithic, integrated SAW array. Details of the design, fabrication, and performance of these devices are discussed. In addition, the ability to produce heteroepitaxial layers of GaAs and aluminum gallium arsenide (AlGaAs) makes possible micromachined membrane sensors with improved sensitivity compared to conventional SAW sensors. Micromachining techniques for fabricating flexural plate wave (FPW) and thickness shear mode (TSM) microsensors on thin GaAs membranes are presented and GaAs FPW delay line and TSM resonator performance is described.

  19. SEU In An Advanced Bipolar Integrated Circuit

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Secrest, Elaine C.; Berndt, Dale F.

    1989-01-01

    Report summarizes investigation of single-event upsets (SEU) in bipolar integrated-circuit set of flip-flops (memory cells). Device tested made by advanced digital bipolar silicon process of Honeywell, Inc. Circuit chip contained 4 cells. Construction enabled study of effect of size on SEU behavior. Each cell externally biased so effect of bias current on SEU behavior. Results of study provides important information for optimal design of devices fabricated using buried-layer bipolar process operating in heavy-ion SEU environments. Designers use information to provide required levels of suppression of SEU in specific applications via combinations of size and/or cell-current scaling.

  20. A Rare Case of Bipolar Clavicle Fracture

    PubMed Central

    Hoy, Gregory A.

    2016-01-01

    Segmental or bipolar fractures of the clavicle generally refer to a concomitant ipsilateral distal clavicle and midshaft clavicle fracture. These injuries are exceedingly rare and are generally secondary to higher energy injuries. We report a case of a 38-year-old male who sustained a left bipolar clavicle fracture after falling from a push bike while riding recreationally which unusually involved the medial and lateral ends of the clavicle and not the midshaft as previously reported in other patients. The patient's exact fracture configuration was not immediately apparent highlighting the need for careful examination of the whole clavicle in order to not miss a bipolar fracture. PMID:27051546

  1. Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Joyce, Hannah J.; Docherty, Callum J.; Gao, Qiang; Tan, H. Hoe; Jagadish, Chennupati; Lloyd-Hughes, James; Herz, Laura M.; Johnston, Michael B.

    2013-05-01

    We have performed a comparative study of ultrafast charge carrier dynamics in a range of III-V nanowires using optical pump-terahertz probe spectroscopy. This versatile technique allows measurement of important parameters for device applications, including carrier lifetimes, surface recombination velocities, carrier mobilities and donor doping levels. GaAs, InAs and InP nanowires of varying diameters were measured. For all samples, the electronic response was dominated by a pronounced surface plasmon mode. Of the three nanowire materials, InAs nanowires exhibited the highest electron mobilities of 6000 cm2 V-1 s-1, which highlights their potential for high mobility applications, such as field effect transistors. InP nanowires exhibited the longest carrier lifetimes and the lowest surface recombination velocity of 170 cm s-1. This very low surface recombination velocity makes InP nanowires suitable for applications where carrier lifetime is crucial, such as in photovoltaics. In contrast, the carrier lifetimes in GaAs nanowires were extremely short, of the order of picoseconds, due to the high surface recombination velocity, which was measured as 5.4 × 105  cm s-1. These findings will assist in the choice of nanowires for different applications, and identify the challenges in producing nanowires suitable for future electronic and optoelectronic devices.

  2. Small signal model parameters analysis of GaN and GaAs based HEMTs over temperature for microwave applications

    NASA Astrophysics Data System (ADS)

    Alim, Mohammad A.; Rezazadeh, Ali A.; Gaquiere, Christophe

    2016-05-01

    Thermal and small-signal model parameters analysis have been carried out on 0.5 μm × (2 × 100 μm) AlGaAs/GaAs HEMT grown on semi-insulating GaAs substrate and 0.25 μm × (2 × 100 μm) AlGaN/GaN HEMT grown on SiC substrate. Two different technologies are investigated in order to establish a detailed understanding of their capabilities in terms of frequency and temperature using on-wafer S-parameter measurement over the temperature range from -40 to 150 °C up to 50 GHz. The equivalent circuit parameters as well as their temperature-dependent behavior of the two technologies were analyzed and discussed for the first time. The principle elevation or degradation of transistor parameters with temperature demonstrates the great potential of GaN device for high frequency and high temperature applications. The result provides some valuable insights for future design optimizations of advanced GaN and a comparison of this with the GaAs technology.

  3. 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

  4. 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.

  5. 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.

  6. Superconductor based neuron single electron transistor

    NASA Astrophysics Data System (ADS)

    Jiang, J. F.; Cai, Q. Y.; Cheng, Z. C.; Shen, B.; Gao, J.

    2000-11-01

    We have proposed a new functional superconductor single electron transistor called neuron superconducting single electron transistor (Neuron - SuSET), which simulates the function of biological neurons. The new transistor is capable of executing a weighted sum calculation of multiple input signals and threshold operation based on the results of the weighted summation, The basic structure and the variable threshold characteristics of the Neuron - SuSET are described based on the semiclassical model.

  7. 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.

  8. P+ contacts on GaAs for semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Parker, Michael A.; Honey, David A.; Olewicz, Alexander; Libby, Stuart I.; Swanson, Paul D.

    1992-10-01

    The physics and engineering of semiconductor electrical contacts and the importance of low resistance ohmic contacts for the best performance from electronic devices is discussed. A simple method is used to deduce the resistance of the electrical contacts and the bulk semiconductor. The fabrication process for P+ GaAs contacts is discussed. Test results are presented for the resistance of the metal electrodes, P+ GaAs bulk, the intrinsic contact resistance, and the temperature dependence of the metal and P+ GaAs. The distributed impedance of the contact structure for semiconductor lasers is discussed.

  9. Field dependent emission rates in radiation damaged GaAs

    SciTech Connect

    Fleming, R. M.; Myers, S. M.; Wampler, W. R.; Lang, D. V.; Seager, C. H.; Campbell, J. M.

    2014-07-07

    We have measured the temperature and field dependence of emission rates from five traps in electron damaged GaAs. Four of the traps have previously been identified as radiation defects. One of the traps, seen in higher doped diodes, has not been previously identified. We have fit the data to a multiphonon emission theory that allows recombination in GaAs to be characterized over a broad range of temperature and electric field. These results demonstrate an efficient method to calculate field-dependent emission rates in GaAs.

  10. Photocurrent Spectroscopy of Single Wurtzite GaAs Nanowires

    SciTech Connect

    Kim, D. C.; Ahtapodov, L.; Boe, A. B.; Moses, A. F.; Dheeraj, D. L.; Fimland, B. O.; Weman, H.; Choi, J. W.; Ji, H.; Kim, G. T.

    2011-12-23

    Photocurrent of single wurtzite GaAs nanowires grown by Au-assisted molecular beam epitaxy is measured at room and low temperature (10 K). At room temperature a high photo-response with more than two orders of magnitude increase of current is observed. The wavelength dependence of the photocurrent shows a sharp change near the zinc blende GaAs band gap. The absence of the free exciton peak in the low temperature photocurrent spectrum, and problems related to determining the exact position of the energy bandgap of wurtzite GaAs from the observed data are discussed.

  11. Ionizing radiation hardness of GaAs technologies

    SciTech Connect

    Listvan, M.A.; Vold, P.J.; Arch, D.K.

    1987-12-01

    The radiation response of several GaAs technologies to ionizing radiation has been investigated. Self-aligned gate (SAG) E/D GaAs Metal Semiconductor FET (MESFET), SAG AlGaAs/GaAs Modulation Doped FET (MODFET), and complementary-AlGaAs/GaAs Heterostructure Insulated Gate FET (C-HIGET) devices and circuits all demonstrated minimal sensitivity to total dose effects to 250 Mrad (GaAs). The heterostructure based technologies showed superior tolerance to high dose rate exposures, with upset levels exceeding 1 x 10/sup 10/ rads(GaAs)/s.

  12. Comorbidity in pediatric bipolar disorder.

    PubMed

    Joshi, Gagan; Wilens, Timothy

    2009-04-01

    The growing literature shows the pervasiveness and importance of comorbidity in youth with bipolar disorder (BPD). For instance, up to 90% of youth with BPD have been described to manifest comorbidity with attention-deficit hyperactivity disorder. Multiple anxiety, substance use, and disruptive behavior disorders are the other most commonly reported comorbidities with BPD. Moreover, important recent data highlight the importance of obsessive-compulsive and pervasive developmental illness in the context of BPD. Data suggest that not only special developmental relationships are operant in the context of comorbidity but also that the presence of comorbid disorders with BPD results in a more severe clinical condition. Moreover, the presence of comorbidity has therapeutic implications for the treatment response for both BPD and the associated comorbid disorder. Future longitudinal studies to address the relationship and the impact of comorbid disorders on course and therapeutic response over time are required in youth with BPD. PMID:19264265

  13. Antidepressant chronotherapeutics for bipolar depression

    PubMed Central

    Benedetti, Francesco

    2012-01-01

    Chronotherapeutics refers to treatments based on the principles of circadian rhythm organization and sleep physiology, which control the exposure to environmental stimuli that act on biological rhythms, in order to achieve therapeutic effects in the treatment of psychiatric conditions. It includes manipulations of the sleep-wake cycle such as sleep deprivation and sleep phase advance, and controlled exposure to light and dark. The antidepressant effects of chronotherapeutics are evident in difficult-to-treat conditions such as bipolar depression, which has been associated with extremely low success rates of antidepressant drugs in naturalistic settings and with stable antidepressant response to chronotherapeutics in more than half of the patients. Recent advances in the study of the effects of chronotherapeutics on neurotransmitter systems, and on the biological clock machinery, allow us to pinpoint its mechanism of action and to transform it from a neglected or “orphan” treatment to a powerful clinical instrument in everyday psychiatric practice. PMID:23393416

  14. Comorbidity in Pediatric Bipolar Disorder

    PubMed Central

    Joshi, Gagan; Wilens, Timothy

    2013-01-01

    Synopsis A growing literature shows the pervasiveness and importance of comorbidity in youth with bipolar disorder (BPD). For instance, up to 90% of youth with BPD have been described to manifest comorbidity with attention deficit hyperactivity disorder. Multiple anxiety, substance use, and disruptive behavior disorders are the other most commonly reported comorbidities with BPD. Moreover, important recent data highlights the importance of obsessive compulsive and pervasive developmental illness in the context of BPD. Data suggests that not only special developmental relationships are operant in context to comorbidity, but also that the presence of comorbid disorders with BPD results in a more severe clinical condition. Moreover, the presence of comorbidity has therapeutic implications for the treatment response for both BPD and the associated comorbid disorder. Future longitudinal studies to address the relationship and the impact of comorbid disorders on course and therapeutic response over time are required in youth with BPD. PMID:19264265

  15. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, B.; Bolstad, J.J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the present invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process. 4 figs.

  16. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, Bora; Bolstad, James J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the pesent invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process.

  17. Miniature Bipolar Electrostatic Ion Thruster

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2006-01-01

    The figure presents a concept of a bipolar miniature electrostatic ion thruster for maneuvering a small spacecraft. The ionization device in the proposed thruster would be a 0.1-micron-thick dielectric membrane with metal electrodes on both sides. Small conical holes would be micromachined through the membrane and electrodes. An electric potential of the order of a volt applied between the membrane electrodes would give rise to an electric field of the order of several mega-volts per meter in the submicron gap between the electrodes. An electric field of this magnitude would be sufficient to ionize all the molecules that enter the holes. In a thruster-based on this concept, one or more propellant gases would be introduced into such a membrane ionizer. Unlike in larger prior ion thrusters, all of the propellant molecules would be ionized. This thruster would be capable of bipolar operation. There would be two accelerator grids - one located forward and one located aft of the membrane ionizer. In one mode of operation, which one could denote the forward mode, positive ions leaving the ionizer on the backside would be accelerated to high momentum by an electric field between the ionizer and an accelerator grid. Electrons leaving the ionizer on the front side would be ejected into free space by a smaller accelerating field. The equality of the ion and electron currents would eliminate the need for an additional electron- or ion-emitting device to keep the spacecraft charge-neutral. In another mode of operation, which could denote the reverse mode, the polarities of the voltages applied to the accelerator grids and to the electrodes of the membrane ionizer would be the reverse of those of the forward mode. The reversal of electric fields would cause the ion and electrons to be ejected in the reverse of their forward mode directions, thereby giving rise to thrust in the direction opposite that of the forward mode.

  18. 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.

  19. GaAs VLSI technology and circuit elements for DSP

    NASA Astrophysics Data System (ADS)

    Mikkelson, James M.

    1990-10-01

    Recent progress in digital GaAs circuit performance and complexity is presented to demonstrate the current capabilities of GaAs components. High density GaAs process technology and circuit design techniques are described and critical issues for achieving favorable complexity speed power and cost tradeoffs are reviewed. Some DSP building blocks are described to provide examples of what types of DSP systems could be implemented with present GaAs technology. DIGITAL GaAs CIRCUIT CAPABILITIES In the past few years the capabilities of digital GaAs circuits have dramatically increased to the VLSI level. Major gains in circuit complexity and power-delay products have been achieved by the use of silicon-like process technologies and simple circuit topologies. The very high speed and low power consumption of digital GaAs VLSI circuits have made GaAs a desirable alternative to high performance silicon in hardware intensive high speed system applications. An example of the performance and integration complexity available with GaAs VLSI circuits is the 64x64 crosspoint switch shown in figure 1. This switch which is the most complex GaAs circuit currently available is designed on a 30 gate GaAs gate array. It operates at 200 MHz and dissipates only 8 watts of power. The reasons for increasing the level of integration of GaAs circuits are similar to the reasons for the continued increase of silicon circuit complexity. The market factors driving GaAs VLSI are system design methodology system cost power and reliability. System designers are hesitant or unwilling to go backwards to previous design techniques and lower levels of integration. A more highly integrated system in a lower performance technology can often approach the performance of a system in a higher performance technology at a lower level of integration. Higher levels of integration also lower the system component count which reduces the system cost size and power consumption while improving the system reliability. For large gate count circuits the power per gate must be minimized to prevent reliability and cooling problems. The technical factors which favor increasing GaAs circuit complexity are primarily related to reducing the speed and power penalties incurred when crossing chip boundaries. Because the internal GaAs chip logic levels are not compatible with standard silicon I/O levels input receivers and output drivers are needed to convert levels. These I/O circuits add significant delay to logic paths consume large amounts of power and use an appreciable portion of the die area. The effects of these I/O penalties can be reduced by increasing the ratio of core logic to I/O on a chip. DSP operations which have a large number of logic stages between the input and the output are ideal candidates to take advantage of the performance of GaAs digital circuits. Figure 2 is a schematic representation of the I/O penalties encountered when converting from ECL levels to GaAs

  20. 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.

  1. 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.

  2. Localized corrosion of GaAs surfaces and formation of porous GaAs

    SciTech Connect

    Schmuki, P.; Vitus, C.M.; Isaacs, H.S.; Fraser, J.; Graham, M.J.

    1995-12-01

    The present work deals with pitting corrosion of p- and n-type GaAs (100). Pit growth can be electrochemically initiated on both conduction types in chloride-containing solutions and leads after extended periods of time to the formation of a porous GaAs structure. In the case of p-type material, localized corrosion is only observed if a passivating film is present on the surface, otherwise -- e.g. in acidic solutions -- the material suffers from a uniform attack (electropolishing) which is independent of the anion present. In contrast, pitting corrosion of n-type material can be triggered independent of the presence of an oxide film. This is explained in terms of the different current limiting factor for the differently doped materials (oxide film in the case of the p- and a space charge layer in the case of the n-GaAs). The porous structure was characterized by SEM, EDX and AES, and consists mainly of GaAs. From scratch experiments it is clear that the pit initiation process is strongly influenced by surface defects. For n-type material, AFM investigations show that light induced roughening of the order of several hundred nm occurs under non-passivating conditions. This nm- scale roughening however does not affect the pitting process.

  3. 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 8.4 GHz, as shown. Record performance was also demonstrated at 12.6 and 18 GHz. Developers have combined these state-of-the-art transistors with transmission lines and micromachined passive circuit components, such as inductors and capacitors, to build multistage amplifiers. Currently, a 1-W, 8.4-GHz power amplifier is being built for NASA deep space communication architectures.

  4. The clinical side of bipolar disorders.

    PubMed

    Grunze, H

    2011-05-01

    This article summarizes key facts on the epidemiology, diagnosis and clinical treatment of bipolar disorder. Bipolar disorder is a common mental disorder with a high disease burden, but still does not get the attention it deserves in research and clinical training. The nature of the disorder is complex, but it is apparent that biological factors are decisive. Thus, understanding the biological systems and cycles affected will become crucial for developing more targeted interventions. Currently, standard treatments seem to have a low specificity for Bipolar Disorder, and only few experimental interventions target directly potential underlying disturbances as HPA axis or circadian clock dysregulation. Systemic analysing and modelling of bipolar disorder is a novel approach which might open up new ways in developing more selective therapies. PMID:21544744

  5. Empirical typology of bipolar I mood episodes*

    PubMed Central

    Solomon, David A.; Leon, Andrew C.; Endicott, Jean; Coryell, William H.; Li, Chunshan; Fiedorowicz, Jess G.; Keller, Martin B.

    2009-01-01

    Background Much remains unknown about the phenomenology of bipolar I disorder. Aims To determine the type of bipolar I mood episodes that occur over time, and their relative frequency. Method A total of 219 individuals with Research Diagnostic Criteria bipolar I disorder were prospectively followed for up to 25 years (median 20 years). Psychopathology was assessed with the Longitudinal Interval Follow-up Evaluation. Results Overall, 1208 mood episodes were prospectively observed. The episodes were empirically classified as follows: major depression, 30.9% (n = 373); minor depression, 13.0% (n = 157); mania, 20.4% (n = 246); hypomania, 10.4% (n = 126); cycling, 17.3% (n = 210); cycling plus mixed state, 7.8% (n = 94); and mixed, 0.2% (n = 2). Conclusions Cycling episodes constituted 25% of all episodes. Work groups revising ICD–10 and DSM–IV should add a category for bipolar I cycling episode. PMID:19949203

  6. White matter microstructure alterations in bipolar disorder

    PubMed Central

    Bellani, Marcella; Perlini, Cinzia; Ferro, Adele; Cerruti, Stefania; Rambaldelli, Gianluca; Isola, Miriam; Cerini, Roberto; Dusi, Nicola; Andreone, Nicola; Balestrieri, Matteo; Mucelli, Roberto Pozzi; Tansella, Michele; Brambilla, Paolo

    2012-01-01

    Summary Genetic, neuropathological and magnetic resonance imaging findings support the presence of diffuse white matter cytoarchitectural disruption in bipolar disorder. In this study, diffusion-weighted imaging (DWI) was applied to study cortical white matter microstructure organisation in 24 patients with DSM-IV bipolar disorder and 35 matched normal controls. DWI images were obtained using a 1.5 Tesla scanner and apparent diffusion coefficient (ADC) values were determined over regions of interest placed, bilaterally, in the frontal, temporal, parietal, and occipital white matter. Significantly increased ADC values were found in bipolar patients with respect to normal controls in the right temporal lobe, left parietal lobe and bilateral occipital lobes. ADC values did not associate significantly with age or with clinical variables (p>0.05). Diffuse cortical white matter alterations on DWI in bipolar disorder denote widespread disruption of white matter integrity and may be due to altered myelination and/or axonal integrity. PMID:22687164

  7. Plasmonic superlensing in doped GaAs.

    PubMed

    Fehrenbacher, Markus; Winnerl, Stephan; Schneider, Harald; Döring, Jonathan; Kehr, Susanne C; Eng, Lukas M; Huo, Yongheng; Schmidt, Oliver G; Yao, Kan; Liu, Yongmin; Helm, Manfred

    2015-02-11

    We demonstrate a semiconductor based broadband near-field superlens in the mid-infrared regime. Here, the Drude response of a highly doped n-GaAs layer induces a resonant enhancement of evanescent waves accompanied by a significantly improved spatial resolution at radiation wavelengths around λ = 20 μm, adjustable by changing the doping concentration. In our experiments, gold stripes below the GaAs superlens are imaged with a λ/6 subwavelength resolution by an apertureless near-field optical microscope utilizing infrared radiation from a free-electron laser. The resonant behavior of the observed superlensing effect is in excellent agreement with simulations based on the Drude-Lorentz model. Our results demonstrate a rather simple superlens implementation for infrared nanospectroscopy. PMID:25584806

  8. Enhanced CAD model for gate leakage current in heterostructure field effect transistors

    SciTech Connect

    Lee, K.Y. |; Lund, B.; Ytterdal, T.; Robertson, J.; Shur, M.S.; Robertson, P.; Martinez, E.J.

    1996-06-01

    A simple and accurate circuit model for Heterostructure Field Effect Transistors (HFET`s) is proposed to simulate both the gate and the drain current characteristics accounting for hot-electron effects on gate current and the effect of the gate current on the channel current. An analytical equation that describes the effective electron temperature is developed in a simple form. This equation is suitable for implementation in circuit simulators. The model describes both the drain and gate currents at high gate bias voltages. It has been implemented in the circuit simulator AIM-Spice, and good agreement between simulated and measured results is achieved for enhancement-mode HFET`s fabricated in different laboratories. The proposed equivalent circuit and model equations are applicable to other compound semiconductor FET`s, i.e., GaAs MESFET`s.

  9. Reverse contrast imaging in GaAs

    NASA Astrophysics Data System (ADS)

    Mohades-Kassai, A.; Brozel, M. R.

    1990-06-01

    "Reverse contrast imaging" is a technique that has been developed for imaging dislocation distributions in undoped semi-insulating LEC GaAs. This technique, which relies on the mapping of near-bandgap infrared transmission, is both rapid and non-destructive. Until now, no satisfactory mechanism has been proposed for the images except that it has been concluded that they are a result of an absorption process. In the present work we have investigated the rôle of scattering in the production of this image. We have previously described an optical apparatus which is sensitive to changes in refractive index and have shown how it can be used to image both growth striations and doping non-uniformities in n-type GaAs. In this method, changes of refractive index which produce small changes in paths of light beams transmitted by the sample, are directly imaged by an infra-red sensitive TV camera. Using this apparatus we have now demonstrated that the images in reverse contrast, which occur only when the sample is cooled below 150 K and when imaged with light of energy within ∽ 50 meV of the bandedge, have two components, one due to absorption and one due to scattering. The wavelength dependencies of these components are different; the scattering image is observable at longer wavelengths than the absorption image. We conclude that the scattering and absorption arise from the same defects. These absorb near bandedge light, are gettered by dislocations and the resulting concentration gradients are the cause of the light scattering. We tentatively associate these defects with arsenic vacancies.

  10. Rumination in bipolar disorder: evidence for an unquiet mind

    PubMed Central

    2012-01-01

    Depression in bipolar disorder has long been thought to be a state characterized by mental inactivity. However, recent research demonstrates that patients with bipolar disorder engage in rumination, a form of self-focused repetitive cognitive activity, in depressed as well as in manic states. While rumination has long been associated with depressed states in major depressive disorder, the finding that patients with bipolar disorder ruminate in manic states is unique to bipolar disorder and challenges explanations put forward for why people ruminate. We review the research on rumination in bipolar disorder and propose that rumination in bipolar disorder, in both manic and depressed states, reflects executive dysfunction. We also review the neurobiology of bipolar disorder and recent neuroimaging studies of rumination, which is consistent with our hypothesis that the tendency to ruminate reflects executive dysfunction in bipolar disorder. Finally, we relate the neurobiology of rumination to the neurobiology of emotion regulation, which is disrupted in bipolar disorder. PMID:22738363

  11. The development of lurasidone for bipolar depression.

    PubMed

    Loebel, Antony; Xu, Jane; Hsu, Jay; Cucchiaro, Josephine; Pikalov, Andrei

    2015-11-01

    Bipolar disorder is a chronic, recurrent illness that ranks among the top 10 causes of disability in the developed world. As the illness progresses, major depressive episodes increasingly predominate. However, few treatment options are available that have demonstrated efficacy in the treatment of bipolar depression, either as monotherapy or adjunctive therapy in combination with mood stabilizers. Lurasidone is an atypical antipsychotic drug that was initially developed for the treatment of schizophrenia. Since no previous atypical antipsychotic development program had proceeded directly from work on schizophrenia to bipolar depression, the decision to focus on this indication represented an innovation in central nervous system drug development and was designed to address a clinically significant unmet need. The current review summarizes key results of a clinical development program undertaken to characterize the efficacy and safety of lurasidone in patients diagnosed with bipolar depression. Lurasidone is currently the only treatment for bipolar depression approved in the United States as both a monotherapy and an adjunctive therapy with lithium or valproate. The approval of lurasidone expands available treatment options for patients with bipolar depression and provides a therapy with an overall favorable risk-benefit profile. PMID:26771990

  12. The use of bipolar technology in hysteroscopy.

    PubMed

    Calabrese, Stefania; DE Alberti, Davide; Garuti, Giancarlo

    2016-04-01

    Bipolar technology was introduced in the hysteroscopic clinical use in 1999, by the design of both loop electrodes addressed to resectoscopic surgery and miniaturized electrodes adaptable to small-size hysteroscopes. The need of an electrolytic solution as distension medium and the spatial relationships between the active and return bipolar electrode avoid, by definition, the risks of severe electrolyte imbalance syndromes and unpredictable electrical burns, sometimes complicating monopolar surgery. The true revolution in the hysteroscopy care has achieved through the availability of mini-hysteroscopes not requiring cervical dilatation, thus limiting uterine wall damages and allowing surgeons to manage several endometrial pathologies by mini-invasive procedures using an effective electrosurgical bipolar instrumentation. Many surgical interventions, traditionally accomplished by the resectoscope in a surgical room theatre, can be now carried out in an outpatient setting without any support from anesthesia. The patients' avoidance of surgical room access and the quick return to daily activities lead to an obvious - but not fully demonstrated - improvement in the medical and social costs associated to outpatient operative hysteroscopy. In the field of resectoscopy, bipolar electrodes are clinically as effective as monopolar devices. Randomized trials showed that bipolar resectoscopic technology prevents the electrolyte imbalance observed after monopolar surgery. However, in daily clinical practice the assumedly safer profile of bipolar with respect to monopolar resectoscopy has not been demonstrated yet. PMID:26928415

  13. Attention and psychomotor functioning in bipolar depression.

    PubMed

    Burdick, Katherine E; Gunawardane, Nisali; Goldberg, Joseph F; Halperin, Jeffrey M; Garno, Jessica L; Malhotra, Anil K

    2009-04-30

    The objective of this study was to assess psychomotor functioning and attention in individuals with bipolar disorder during the depressed phase of illness. Measures of attention and psychomotor functioning were administered to a sample of 24 bipolar I and II patients and a matched sample of healthy controls. Relative to the healthy controls, the bipolar sample demonstrated evidence of psychomotor slowing and revealed deficits on measures of effortful attention, yet demonstrated comparable performance on measures of automatic attention. In the bipolar sample, we detected significant correlations among measures of psychomotor functioning and some aspects of attention and a strong relationship between the severity of depression and psychomotor functioning, but no direct relationship between attention deficits and depressive symptomatology. These results suggest an attentional impairment during the depressed phase of bipolar disorder that may be specific to effortful processing, while automatic processes remain relatively intact. Associations among indices of attention deficits and psychomotor slowing may be indicative of similarities in the underlying neurobiology of these frequently co-occurring symptom domains in depressed individuals with bipolar disorder. PMID:19272656

  14. Crystal growth of device quality GaAs in space

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Lagowski, J.

    1983-01-01

    GaAs device technology has recently reached a new phase of rapid advancement, made possible by the improvement of the quality of GaAs bulk crystals. At the same time, the transition to the next generation of GaAs integrated circuits and optoelectronic systems for commercial and government applications hinges on new quantum steps in three interrelated areas: crystal growth, device processing and device-related properties and phenomena. Special emphasis is placed on the establishment of quantitative relationships among crystal growth parameters-material properties-electronic properties and device applications. The overall program combines studies of crystal growth on novel approaches to engineering of semiconductor material (i.e., GaAs and related compounds); investigation and correlation of materials properties and electronic characteristics on a macro- and microscale; and investigation of electronic properties and phenomena controlling device applications and device performance.

  15. High Speed GaAs Ics: Performance And Reliability

    NASA Astrophysics Data System (ADS)

    Hickling, Ronald M.; Kemps, John H.

    1987-02-01

    With the data rates of LANs starting to exceed 200 Mbits/sec and long-haul communication systems entering the gigahertz realm, system designers are having to look for alternatives to standard ECL logic to achieve these ultra-high speeds. Until a few years ago, only a precious few OEMs large enough to own a GaAs fab line would have considered it practical to baseline GaAs logic as a solution. However, with the availability of off-the-shelf GaAs digital components, any manufacturer that is accustomed to dealing with ECL technology can now realize system data rates greater than 500 Mbps with ease. This paper will discuss the considerations related to the utilization of GaAs ICs in fiber optic systems including reliability, thermal management, and interconnection issues.

  16. Characteristics of GaAs with inverted thermal conversion

    NASA Technical Reports Server (NTRS)

    Kang, C. H.; Lagowski, J.; Gatos, H. C.

    1987-01-01

    GaAs crystals exhibiting inverted thermal conversion (ITC) of resistivity were investigated in conjunction with standard semiinsulating (SI) GaAs regarding characteristics important in device processing. It was established that dislocation density and Si implant activation are unaffected by transformation to the ITC state. However, in ITC GaAs the controlled increase of the EL2 (native midgap donor) concentration during annealing makes it possible to attain resistivities one order of magnitude greater (e.g., about 10 to the 9th ohm cm of 300 K) than those attained in standard SI GaAs (e.g., 10 to the 7th-10 to the 8th ohm cm).

  17. Crystal Growth of Device Quality Gaas in Space

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.

    1985-01-01

    The GaAs research evolves about these key thrust areas. The overall program combines: (1) studies of crystal growth on novel approaches to engineering of semiconductor material (i.e., GaAs and related compounds); (2) investigation and correlation of materials properties and electronic characteristics on a macro- and microscale; and (3) investigation of electronic properties and phenomena controlling device applications and device performance. This effort is aimed at the essential ground-based program which would insure successful experimentation with and eventually processing of GaAs in near zero gravity environment. It is believed that this program addresses in a unique way materials engineering aspects which bear directly on the future exploitation of the potential of GaAs and related materials in device and systems applications.

  18. GaAs monolithic RF modules for SARSAT distress beacons

    NASA Technical Reports Server (NTRS)

    Cauley, Michael A.

    1991-01-01

    Monolithic GaAs UHF components for use in SARSAT Emergency Distress beacons are under development by Microwave Monolithics, Inc., Simi Valley, CA. The components include a bi-phase modulator, driver amplifier, and a 5 watt power amplifier.

  19. Simulation of silicon diffusion in GaAs

    NASA Astrophysics Data System (ADS)

    Saad, A. M.; Velichko, O. I.

    2011-03-01

    The simulation of coupled diffusion of silicon atoms and point defects in GaAs has been carried out for diffusion at the temperatures of 1000 and 850 °C. The amphoteric behavior of silicon atoms in GaAs has been taken into account in the investigation of high concentration diffusion from silicon layer deposited on GaAs substrate. The calculated dopant profiles agree well with the experimental ones and they confirm the adequacy of the model of silicon diffusion used for simulation. A comparison with the experimental data has enabled this work to obtain the parameters of silicon effective diffusivity and other values describing high concentration silicon diffusion in GaAs.

  20. Size quantization effect in GaAs nanocrystals

    NASA Astrophysics Data System (ADS)

    Nayak, J.; Mythili, R.; Vijayalakshmi, M.; Sahu, S. N.

    2004-09-01

    GaAs nanocrystals have been synthesized by an electrochemical route from the acidic solutions of metallic gallium and arsenic oxide. Structural analysis by transmission electron microscopy (TEM), reveales the presence of orthorhombic phase, in contrast to the usual cubic phase of bulk GaAs. Well separated GaAs nanocrystals having sizes in the range of 7 to 15 nm are identified in the TEM micrograph. Optical absorption shows a strong excitonic absorption band on account of quantum size effect associated with GaAs nanocrystals. Photoluminescence, recorded at 300 K under ultraviolet excitation (369 nm), shows the HOMO-LUMO transition band as well as the red shifted bands. Micro-Raman analysis shows a phonon mode centered at 250 cm-1 associated with a point defect.

  1. GaAs Films Prepared by RF-Magnetron Sputtering

    SciTech Connect

    L.H. Ouyang; D.L. Rode; T. Zulkifli; B. Abraham-Shrauner; N. Lewis; M.R. Freeman

    2001-08-01

    The authors reported on the optical absorption, adhesion, and microstructure of RF-magnetron sputtered films of hydrogenated amorphous and microcrystalline GaAs films for the 1 to 25 {micro}m infrared wavelength rate. Sputtering parameters which were varied include sputtering power, temperature and pressure, and hydrogen sputtering-gas concentration. TEM results show a sharp transition from purely amorphous GaAs to a mixture of microcrystalline GaAs in an amorphous matrix at 34 {+-} 2 C. By optimizing the sputtering parameters, the optical absorption coefficient can be decreased below 100 cm{sup -1} for wavelengths greater than about 1.25 {micro}m. These results represent the lowest reported values of optical absorption for sputtered films of GaAs directly measured by spectrophotometry for the near-infrared wavelength region.

  2. Anisotropic spin transport in (110) GaAs quantum wells.

    PubMed

    Couto, O D D; Iikawa, F; Rudolph, J; Hey, R; Santos, P V

    2007-01-19

    Mobile piezoelectric potentials are used to coherently transport electron spins in GaAs (110) quantum wells (QW) over distances exceeding 60 microm. We demonstrate that the dynamics of mobile spins under external magnetic fields depends on the direction of motion in the QW plane. This transport anisotropy is an intrinsic property of moving spins associated with the bulk inversion asymmetry of the underlying GaAs lattice. PMID:17358707

  3. Characterisation of semi-insulating GaAs

    NASA Technical Reports Server (NTRS)

    Walukiewicz, W.; Pawlowicz, L.; Lagowski, J.; Gatos, H. C.

    1982-01-01

    Hole and electron mobilities as functions of temperature and ionised impurity concentration are calculated for GaAs. It is shown that these calculations, when used to analyse electrical properties of semi-insulating GaAs, enable an assessment of the Fermi energy position and ionised impurity concentration to be made. In contrast to previous work, the analysis does not require any phenomenological assumptions.

  4. Heavy ion total fluence effects in GaAs devices

    SciTech Connect

    Anderson, W.T.; Knudson, A.R.; Roussos, J.A. ); Meulenberg, A.; Hung, H.L. ); Kiriakidis, G. )

    1990-12-01

    Heavy ion radiation effects were studied in GaAs FETs, MMICs, and HEMTs. Significant degradation occurred at 1 {times} 10{sup 9} cm{sup {minus}2} to 6 {times} 10{sup 11} cm{sup {minus}2} for GaAs MMICs depending on whether the irradiation was Si or H, respectively. HEMTs were found to withstand higher levels of irradiation than FETs or MMICs for the same degree of drain current degradation.

  5. The effect of (NH4)2Sx passivation on the (311)A GaAs surface and its use in AlGaAs/GaAs heterostructure devices

    NASA Astrophysics Data System (ADS)

    Carrad, D. J.; Burke, A. M.; Reece, P. J.; Lyttleton, R. W.; Waddington, D. E. J.; Rai, A.; Reuter, D.; Wieck, A. D.; Micolich, , A. P.

    2013-08-01

    We have studied the efficacy of (NH4)2Sx surface passivation on the (311)A GaAs surface. We report XPS studies of simultaneously-grown (311)A and (100) heterostructures showing that the (NH4)2Sx solution removes surface oxide and sulfidizes both surfaces. Passivation is often characterized using photoluminescence measurements; we show that while (NH4)2Sx treatment gives a 40-60 × increase in photoluminescence intensity for the (100) surface, an increase of only 2-3 × is obtained for the (311)A surface. A corresponding lack of reproducible improvement in the gate hysteresis of (311)A heterostructure transistor devices made with the passivation treatment performed immediately prior to gate deposition is also found. We discuss possible reasons why sulfur passivation is ineffective for (311)A GaAs, and propose alternative strategies for passivation of this surface.

  6. Design and fabrication of GaAs OMIST photodetector

    NASA Astrophysics Data System (ADS)

    Kang, Xuejun; Lin, ShiMing; Liao, Qiwei; Gao, Junhua; Liu, Shi'an; Cheng, Peng; Wang, Hongjie; Zhang, Chunhui; Wang, Qiming

    1998-08-01

    We designed and fabricated GaAs OMIST (Optical-controlled Metal-Insulator-Semiconductor Thyristor) device. Using oxidation of AlAs layer that is grown by MBE forms the Ultra- Thin semi-Insulating layer (UTI) of the GAAS OMIST. The accurate control and formation of high quality semi-insulating layer (AlxOy) are the key processes for fabricating GaAs OMIST. The device exhibits a current-controlled negative resistance region in its I-V characteristics. When illuminated, the major effect of optical excitation is the reduction of the switching voltage. If the GaAs OMIST device is biased at a voltage below its dark switching voltage Vs, sufficient incident light can switch OMIST from high impedance low current 'off' state to low impedance high current 'on' state. The absorbing material of OMIST is GaAS, so if the wavelength of incident light within 600 to approximately 850 nm can be detected effectively. It is suitable to be used as photodetector for digital optical data process. The other attractive features of GaAs OMIST device include suitable conducted current, switching voltage and power levels for OEIC, high switch speed and high sensitivity to light or current injection.

  7. Clinical, Demographic, and Familial Correlates of Bipolar Spectrum Disorders among Offspring of Parents with Bipolar Disorder

    ERIC Educational Resources Information Center

    Goldstein, Benjamin I.; Shamseddeen, Wael; Axelson, David A.; Kalas, Cathy; Monk, Kelly; Brent, David A.; Kupfer, David J.; Birmaher, Boris

    2010-01-01

    Objective: Despite increased risk, most offspring of parents with bipolar disorder (BP) do not manifest BP. The identification of risk factors for BP among offspring could improve preventive and treatment strategies. We examined this topic in the Pittsburgh Bipolar Offspring Study (BIOS). Method: Subjects included 388 offspring, ages 7-17 years,

  8. Clinical, Demographic, and Familial Correlates of Bipolar Spectrum Disorders among Offspring of Parents with Bipolar Disorder

    ERIC Educational Resources Information Center

    Goldstein, Benjamin I.; Shamseddeen, Wael; Axelson, David A.; Kalas, Cathy; Monk, Kelly; Brent, David A.; Kupfer, David J.; Birmaher, Boris

    2010-01-01

    Objective: Despite increased risk, most offspring of parents with bipolar disorder (BP) do not manifest BP. The identification of risk factors for BP among offspring could improve preventive and treatment strategies. We examined this topic in the Pittsburgh Bipolar Offspring Study (BIOS). Method: Subjects included 388 offspring, ages 7-17 years,…

  9. Subcortical Gray Matter Volume Abnormalities in Healthy Bipolar Offspring: Potential Neuroanatomical Risk Marker for Bipolar Disorder?

    ERIC Educational Resources Information Center

    Ladouceur, Cecile D.; Almeida, Jorge R. C.; Birmaher, Boris; Axelson, David A.; Nau, Sharon; Kalas, Catherine; Monk, Kelly; Kupfer, David J.; Phillips, Mary L.

    2008-01-01

    A study is conducted to examine the extent to which bipolar disorder (BD) is associated with gray matter volume abnormalities in brain regions in healthy bipolar offspring relative to age-matched controls. Results show increased gray matter volume in the parahippocampus/hippocampus in healthy offspring at genetic risk for BD.

  10. Controlling Transistor Temperature During Burn-In

    NASA Technical Reports Server (NTRS)

    Scott, B. C.

    1986-01-01

    Boiling refrigerant provides simple temperature control for newly manufactured power transistors. Heat-transfer liquid is Fluorinert FC-77 (or equivalent). Liquid boils at 100 degrees C, which is specified temperature at which transistor cases should be maintained during burn-in with this technique.

  11. Pass transistor implementations of multivalued logic

    NASA Technical Reports Server (NTRS)

    Maki, G.; Whitaker, S.

    1990-01-01

    A simple straight-forward Karnaugh map logic design procedure for realization of multiple-valued logic circuits is presented in this paper. Pass transistor logic gates are used to realize multiple-valued networks. This work is an extension of pass transistor implementations for binary-valued logic.

  12. Thresholds for Cenozoic bipolar glaciation.

    PubMed

    Deconto, Robert M; Pollard, David; Wilson, Paul A; Plike, Heiko; Lear, Caroline H; Pagani, Mark

    2008-10-01

    The long-standing view of Earth's Cenozoic glacial history calls for the first continental-scale glaciation of Antarctica in the earliest Oligocene epoch ( approximately 33.6 million years ago), followed by the onset of northern-hemispheric glacial cycles in the late Pliocene epoch, about 31 million years later. The pivotal early Oligocene event is characterized by a rapid shift of 1.5 parts per thousand in deep-sea benthic oxygen-isotope values (Oi-1) within a few hundred thousand years, reflecting a combination of terrestrial ice growth and deep-sea cooling. The apparent absence of contemporaneous cooling in deep-sea Mg/Ca records, however, has been argued to reflect the growth of more ice than can be accommodated on Antarctica; this, combined with new evidence of continental cooling and ice-rafted debris in the Northern Hemisphere during this period, raises the possibility that Oi-1 represents a precursory bipolar glaciation. Here we test this hypothesis using an isotope-capable global climate/ice-sheet model that accommodates both the long-term decline of Cenozoic atmospheric CO(2) levels and the effects of orbital forcing. We show that the CO(2) threshold below which glaciation occurs in the Northern Hemisphere ( approximately 280 p.p.m.v.) is much lower than that for Antarctica ( approximately 750 p.p.m.v.). Therefore, the growth of ice sheets in the Northern Hemisphere immediately following Antarctic glaciation would have required rapid CO(2) drawdown within the Oi-1 timeframe, to levels lower than those estimated by geochemical proxies and carbon-cycle models. Instead of bipolar glaciation, we find that Oi-1 is best explained by Antarctic glaciation alone, combined with deep-sea cooling of up to 4 degrees C and Antarctic ice that is less isotopically depleted (-30 to -35 per thousand) than previously suggested. Proxy CO(2) estimates remain above our model's northern-hemispheric glaciation threshold of approximately 280 p.p.m.v. until approximately 25 Myr ago, but have been near or below that level ever since. This implies that episodic northern-hemispheric ice sheets have been possible some 20 million years earlier than currently assumed (although still much later than Oi-1) and could explain some of the variability in Miocene sea-level records. PMID:18833277

  13. Magnetotransport Properties of Epitaxial Ge/AlAs Heterostructures Integrated on GaAs and Silicon.

    PubMed

    Hudait, Mantu K; Clavel, Michael; Goley, Patrick S; Xie, Yuantao; Heremans, Jean J

    2015-10-14

    The magnetotransport properties of epitaxial Ge/AlAs heterostructures with different growth conditions and substrate architectures have been studied under ±9 T magnetic field and at 390 mK temperature. Systematic mobility measurements of germanium (Ge) epilayers grown on GaAs substrates at growth temperatures from 350 to 450 °C allow us to extract a precise growth window for device-quality Ge, corroborated by structural and morphological properties. Our results on Si substrate using a composite metamorphic AlAs/GaAs buffer at 400 °C Ge growth temperature, show that the Ge/AlAs system can be tailored to have a single carrier transport while keeping the charge solely in the Ge layer. Single carrier transport confined to the Ge layer is demonstrated by the weak-localization quantum correction to the conductivity observed at low magnetic fields and 390 mK temperature. The weak localization effect points to a near-absence of spin-orbit interaction for carriers in the electronically active layer and is used here for the first time to pinpoint Ge as this active layer. Thus, the epitaxial Ge grown on Si using AlAs/GaAs buffer architecture is a promising candidate for next-generation energy-efficient fin field-effect transistor applications. PMID:26413844

  14. Correlation of hot-carrier stress and ionization induced degradation in bipolar transistors

    SciTech Connect

    Pease, R.L.; Kosier, S.L.; Schrimpf, R.D.; Combs, W.E.; DeLaus, M.; Fleetwood, D.M.

    1994-03-01

    The correlation of hot carrier stress and ionization induced gain degradation in npn BJTs was studied to determine if hot-carrier stress could be used as a hardness assurance tool for total dose. The correlation was measured at the wafer level and for several hardening variations for a single process technology. Additional experiments are planned and will be presented in the full paper. Based on a detailed physical analysis of the mechanisms for hot-carrier stress and ionization no correlation was expected. The results demonstrated the lack of correlation and indicate that hot-carrier stress degradation is not a predictor of total dose response.

  15. 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).

  16. An insulated gate bipolar transistor with surface n-type barrier

    NASA Astrophysics Data System (ADS)

    Mengxuan, Jiang; John, Shen Z.; Jun, Wang; Zhikang, Shuai; Xin, Yin; Bingbing, Sun; Linyuan, Liao

    2015-12-01

    This letter proposes a novel IGBT structure with an n-type barrier (NB-IGBT) formed on the silicon surface to enhance the conductivity modulation effect with a relatively simple fabrication process. TCAD simulation indicates that the NB-IGBT offers a current density 49% higher and turn-off losses 25% lower than a conventional field-stop IGBT (FS-IGBT) with a similar breakdown voltage, turn-off time and avalanche energy. Furthermore, the NB-IGBT exhibits extremely large transconductance, which is favorable to turn-on and turn-off. Therefore, the proposed IGBT offers an attractive option for high-voltage and large-power electronics applications. 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).

  17. Heteroepitaxy of ternary SiGeC alloys on Si for bipolar transistors

    NASA Astrophysics Data System (ADS)

    Mayer, James W.

    1994-07-01

    The final report covers: (1) the development of synthetic methods and detailed phase and compositional characterization of our cubic SiC-GeC solid solutions and diamond structured SiGeC thin films; (2) our preliminary findings on bandgap measurements; and (3) the development of a novel technique for in situ observation of SiGeC CVD in an environmental electron microscope. We used this technique to deposit films that are lattice matched to Silicon. The work was carried out in the Chemical Vapor Deposition Laboratory (by graduate student Michael Todd, postdoctoral research associate Philippe Bonneau, and Professor John Kouvetakis) and the Ion Beam Facility (Barry Wilkens), with assistance from the staff of the High Resolution Electron Microscopy Group (Dr. Renu Sharma, and Professor David Smith) at Arizona State University. Vibrational characterization and bandgap studies were carried out by Nigel Cave at Motorola Phoenix.

  18. IGBT convertor with active snubber for soft switching. [Insulated Gate Bipolar Transistor

    NASA Technical Reports Server (NTRS)

    Masserant, B. J.; Shriver, J.; Stuart, T. A.

    1991-01-01

    This full bridge dc-dc convertor with IGBTs uses zero voltage switching (ZVS) for one leg of the bridge and zero current switching (ZCS) for the other. It is shown that an active snubber greatly improves the performance over previous methods. Experimental results are shown for a 6 kW circuit switching at 20 kHz.

  19. Universal power transistor base drive control unit

    DOEpatents

    Gale, A.R.; Gritter, D.J.

    1988-06-07

    A saturation condition regulator system for a power transistor is disclosed which achieves the regulation objectives of a Baker clamp but without dumping excess base drive current into the transistor output circuit. The base drive current of the transistor is sensed and used through an active feedback circuit to produce an error signal which modulates the base drive current through a linearly operating FET. The collector base voltage of the power transistor is independently monitored to develop a second error signal which is also used to regulate base drive current. The current-sensitive circuit operates as a limiter. In addition, a fail-safe timing circuit is disclosed which automatically resets to a turn OFF condition in the event the transistor does not turn ON within a predetermined time after the input signal transition. 2 figs.

  20. Universal power transistor base drive control unit

    DOEpatents

    Gale, Allan R.; Gritter, David J.

    1988-01-01

    A saturation condition regulator system for a power transistor which achieves the regulation objectives of a Baker clamp but without dumping excess base drive current into the transistor output circuit. The base drive current of the transistor is sensed and used through an active feedback circuit to produce an error signal which modulates the base drive current through a linearly operating FET. The collector base voltage of the power transistor is independently monitored to develop a second error signal which is also used to regulate base drive current. The current-sensitive circuit operates as a limiter. In addition, a fail-safe timing circuit is disclosed which automatically resets to a turn OFF condition in the event the transistor does not turn ON within a predetermined time after the input signal transition.