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Sample records for insulated gate field

  1. Ambipolar organic field-effect transistor using gate insulator hysteresis

    NASA Astrophysics Data System (ADS)

    Mizuno, Eriko; Taniguchi, Masateru; Kawai, Tomoji

    2005-04-01

    An organic field-effect transistor based on a copper-phthalocyanine and cyanoethylpullulan gate insulator showed ambipolar operation using gate insulator hysteresis, which appeared at less than 1mHz. The gate insulator possesses spontaneous polarization of 1.6μC/cm2 and a coercive electric field of 50kV/cm. After poling in an effort to obtain a large amount of accumulated charge, the field-effect mobilities of the hole and electron were 4.1×10-3 and 3.5×10-6cm2/Vs, respectively. The on/off ratio at VSG=±10V was 6×104 for the p type and 70 for the n type.

  2. Low voltage vertical organic field-effect transistor with polyvinyl alcohol as gate insulator

    NASA Astrophysics Data System (ADS)

    Rossi, Lucieli; Seidel, Keli F.; Machado, Wagner S.; Hümmelgen, Ivo A.

    2011-11-01

    We report the preparation of low gate leakage current organic field effect transistors in vertical architecture using polyvinyl alcohol as gate insulator and C60 fullerene as n-type semiconductor in devices with gate, source, and drain electrodes of Al. Intermediate electrode and top electrode operate, respectively, as source and drain, or vice-versa, depending on polarity. In these devices the intermediate electrode (source or drain) is permeable to the electric field produced by the gate so that increased drain current is obtained at either increasingly negative gate voltage when the source is the intermediate electrode or increasingly positive gate voltage when the drain is the intermediate electrode.

  3. Radiation tolerant silicon nitride insulated gate field effect transistors

    NASA Technical Reports Server (NTRS)

    Newman, P. A.

    1969-01-01

    Metal-Insulated-Semiconductor Field Effect Transistor /MISFET/ device uses a silicon nitride passivation layer over a thin silicon oxide layer to enhance the radiation tolerance. It is useful in electronic systems exposed to space radiation environment or the effects of nuclear weapons.

  4. Negative transconductance in double-gate germanium-on-insulator field effect transistors

    NASA Astrophysics Data System (ADS)

    Zaslavsky, A.; Soliveres, S.; Le Royer, C.; Cristoloveanu, S.; Clavelier, L.; Deleonibus, S.

    2007-10-01

    Transport in double-gate (DG) transistors offers unusual properties due to the coupling between the two channels. We report on room-temperature negative transconductance in germanium-on-insulator DG transistors in the subthreshold regime. The effect is due to the coupling between conducting channels, analogous to the velocity modulation transistor (VMT). Unlike the VMT, our effect can be induced by either of the gates and arises not from a difference in the channel mobilities but from partial electric field screening at low channel densities combined with the density dependence of mobility. The negative transconductance becomes weaker as gate length LG is reduced.

  5. SINGLE CRYSTAL CADMIUM SULFIDE AND CADMIUM SELENIDE INSULATED-GATE FIELD-EFFECT TRIODES.

    DTIC Science & Technology

    Insulated-gate field-effect triodes were fabricated on single crystal cadmium sulfide and cadmium selenide . Both bulk crystals and platelets were...used for single crystal samples. Chromium and aluminum were found to make low impedance contacts to cadmium sulfide and cadmium selenide . The...polycrystalline cadmium sulfide and cadmium selenide IGFET’s. The characteristics of the fabricated devices were unstable with respect to time and temperature

  6. Gate Tunable Relativistic Mass and Berry's phase in Topological Insulator Nanoribbon Field Effect Devices

    PubMed Central

    Jauregui, Luis A.; Pettes, Michael T.; Rokhinson, Leonid P.; Shi, Li; Chen, Yong P.

    2015-01-01

    Transport due to spin-helical massless Dirac fermion surface state is of paramount importance to realize various new physical phenomena in topological insulators, ranging from quantum anomalous Hall effect to Majorana fermions. However, one of the most important hallmarks of topological surface states, the Dirac linear band dispersion, has been difficult to reveal directly in transport measurements. Here we report experiments on Bi2Te3 nanoribbon ambipolar field effect devices on high-κ SrTiO3 substrates, where we achieve a gate-tuned bulk metal-insulator transition and the topological transport regime with substantial surface state conduction. In this regime, we report two unambiguous transport evidences for gate-tunable Dirac fermions through π Berry's phase in Shubnikov-de Haas oscillations and effective mass proportional to the Fermi momentum, indicating linear energy-momentum dispersion. We also measure a gate-tunable weak anti-localization (WAL) with 2 coherent conduction channels (indicating 2 decoupled surfaces) near the charge neutrality point, and a transition to weak localization (indicating a collapse of the Berry's phase) when the Fermi energy approaches the bulk conduction band. The gate-tunable Dirac fermion topological surface states pave the way towards a variety of topological electronic devices. PMID:25677703

  7. Germanium Metal - Insulator - Semiconductor Field Effect Transistors Utilizing a Germanium Nitride Gate Insulator.

    NASA Astrophysics Data System (ADS)

    Rosenberg, James Jordan

    The work presented in this thesis provides new information on three distinct but related topics. Firstly, it describes a technique for growing thin films of germanium nitride on germanium--a previously unexplored semiconductor -insulator system. Secondly, it describes electrical measurements made on metal-Ge(,3)N(,4)-Ge capacitors which demonstrate that this metal-insulator-semiconductor (MIS) system is of high quality. Thirdly, it describes a process by which n-channel germanium metal-insulator-semiconductor field effect transistors (MISFETs) have been fabricated. The motivations for exploring this new MIS system (e.g. basic physics of germanium inversion layers, higher performance MISFETs, etc.) are also described. The growth technique described here and the films produced by it possess several distinct advantages over previous methods of obtaining insulating films on germanium. The growth technique itself is simple. It involves no elaborate or expensive equipment, and is essentially identical in its execution (although not in its chemical process) to conventional techniques for obtaining an insulator on silicon (i.e. thermal oxidation of silicon). The film growth technique yields very reproducible results (in terms of film thickness and refractive index) from wafer to wafer. The physical properties of the film itself are also attractive. It is far more chemically stable than germanium oxide, and is quite process compatible. It is resistant to many chemicals encountered in typical processing cycles, but also can be readily patterned in hot phosphoric acid, which does not appreciably attack germanium. Electrical measurements on MIS capacitors indicate that the density of fast states at the germanium-germanium nitride interface is quite low. The interface state density is less than or equal to 1 x 10('11)/cm('2)-eV from midgap to within 0.15 eV of the conduction band edge, as determined by variable frequency capacitance measurements. The MISFETs fabricated for this

  8. Field effect transistor with HfO2/Parylene-C bilayer hybrid gate insulator

    NASA Astrophysics Data System (ADS)

    Kumar, Neeraj; Kito, Ai; Inoue, Isao

    2015-03-01

    We have investigated the electric field control of the carrier density and the mobility at the surface of SrTiO3, a well known transition-metal oxide, in a field effect transistor (FET) geometry. We have used a Parylene-C (8 nm)/HfO2 (20 nm) double-layer gate insulator (GI), which can be a potential candidate for a solid state GI for the future Mott FETs. So far, only examples of the Mott FET used liquid electrolyte or ferroelectric oxides for the GI. However, possible electrochemical reaction at the interface causes damage to the surface of the Mott insulator. Thus, an alternative GI has been highly desired. We observed that even an ultra thin Parylene-C layer is effective for keeping the channel surface clean and free from oxygen vacancies. The 8 nm Parylene-C film has a relatively low resistance and consequentially its capacitance does not dominate the total capacitance of the Parylene-C/HfO2 GI. The breakdown gate voltage at 300 K is usually more than 10 V (~ 3.4 MV/cm). At gate voltage of 3 V the carrier density measured by the Hall effect is about 3 ×1013 cm-2, competent to cause the Mott transition. Moreover, the field effect mobility reaches in the range of 10 cm2/Vs indicating the Parylene-C passivated surface is actually very clean.

  9. Characterization of a vertically movable gate field effect transistor using a silicon-on-insulator wafer

    NASA Astrophysics Data System (ADS)

    Song, In-Hyouk; Forfang, William B. D.; Cole, Bryan; You, Byoung Hee

    2014-10-01

    The vertically movable gate field effect transistor (VMGFET) is a FET-based sensing element, whose gate moves in a vertical direction over the channel. A VMGFET gate covers the region between source and drain. A 1 μm thick air layer separates the gate and the substrate of the VMGFET. A novel fabrication process to form a VMGFET using a silicon-on-insulator (SOI) wafer provides minimal internal stress of the gate structure. The enhancement-type n-channel VMGFET is fabricated with the threshold voltage of 2.32 V in steady state. A non-inverting amplifier is designed and integrated on a printable circuit board (PCB) to characterize device sensitivity and mechanical properties. The VMGFET is mechanically coupled to a speaker membrane to apply mechanical vibration. The oscillated drain current of FET are monitored and sampled with NI LabVIEW. The frequency of the output signal correlates with that of the input stimulus. The resonance frequency of the fabricated VMGFET is measured to be 1.11 kHz. The device sensitivity linearly increases by 0.106 mV/g Hz in the range of 150 Hz and 1 kHz.

  10. Plasma-deposited germanium nitride gate insulators for indium phosphide metal-insulator-semiconductor field-effect transistors

    NASA Technical Reports Server (NTRS)

    Johnson, Gregory A.; Kapoor, Vik J.

    1991-01-01

    Plasma-deposited germanium nitride was investigated for the first time as a possible gate insulator for InP compound semiconductor metal-insulator-semiconductor FET (MISFET) technology. The germanium nitride films were successfully deposited in a capacitively coupled parallel plate reactor at 13.56 MHz operation using GeH4/N2/NH3 and GeH4/N2 mixtures as reactant gases. The former process produced better quality films with enhanced uniformity, increased deposition rates, and increased resistivity. The breakdown field strength of the films was greater than 10 to the 6th V/cm. Auger electron spectroscopy did not indicate significant chemical composition differences between the two processes. For MISFETs with 2-micron channel lengths fabricated on InP, the device transconductance and threshold voltage for the GeH4/N2/NH3 process were 17 mS/mm and -3.6 V, respectively. The drain-source breakdown voltages were greater than 10 V.

  11. Fabrication and Characterization of Ferroelectric Gate Field-Effect Transistor Memory Based on Ferroelectric-Insulator Interface Conduction

    NASA Astrophysics Data System (ADS)

    Lee, Bong Yeon; Minami, Takaki; Kanashima, Takeshi; Okuyama, Masanori

    2006-11-01

    A new type of ferroelectric gate field-effect transistor (FET) using ferroelectric-insulator interface conduction has been proposed. Drain current flows along the interface between the ferroelectric and insulator layers and requires no semiconductor. The channel region of the FET is composed of a Pt/insulator HfO2/ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT)/Pt/TiO2/SiO2/Si multilayer, and the source and drain areas are formed at the interface of the PZT and HfO2 films. Drain current versus gate voltage characteristics show a clockwise hysteresis loop similar to that for a conventional p-channel transistor. The FET shows that the on/off ratio of the conduction current is within 105 to 106 and that the off-state current is about 10-10 A.

  12. Silicon dioxide with a silicon interfacial layer as an insulating gate for highly stable indium phosphide metal-insulator-semiconductor field effect transistors

    NASA Technical Reports Server (NTRS)

    Kapoor, V. J.; Shokrani, M.

    1991-01-01

    A novel gate insulator consisting of silicon dioxide (SiO2) with a thin silicon (Si) interfacial layer has been investigated for high-power microwave indium phosphide (InP) metal-insulator-semiconductor field effect transistors (MISFETs). The role of the silicon interfacial layer on the chemical nature of the SiO2/Si/InP interface was studied by high-resolution X-ray photoelectron spectroscopy. The results indicated that the silicon interfacial layer reacted with the native oxide at the InP surface, thus producing silicon dioxide, while reducing the native oxide which has been shown to be responsible for the instabilities in InP MISFETs. While a 1.2-V hysteresis was present in the capacitance-voltage (C-V) curve of the MIS capacitors with silicon dioxide, less than 0.1 V hysteresis was observed in the C-V curve of the capacitors with the silicon interfacial layer incorporated in the insulator. InP MISFETs fabricated with the silicon dioxide in combination with the silicon interfacial layer exhibited excellent stability with drain current drift of less than 3 percent in 10,000 sec, as compared to 15-18 percent drift in 10,000 sec for devices without the silicon interfacial layer. High-power microwave InP MISFETs with Si/SiO2 gate insulators resulted in an output power density of 1.75 W/mm gate width at 9.7 GHz, with an associated power gain of 2.5 dB and 24 percent power added efficiency.

  13. 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.

  14. Topological insulator state in gated bilayer silicene

    NASA Astrophysics Data System (ADS)

    Zhang, Ming-Ming; Xu, Lei; Zhang, Jun

    2015-11-01

    We investigate the topological insulator state of gated bilayer silicene in the presence of extrinsic Rashba spin-orbit (SO) coupling. The system exhibits a band insulator (BI) phase for small Rashba SO coupling, and then translate to a strong topological insulator (TI) phase with both spin and valley filtered at large Rashba SO coupling. The strong TI phase is robust in the presence of intrinsic SO and intrinsic Rashba SO couplings. When a titled electric field is introduced, the in-plane component of the electric field gives rise to an interlayer Rashba SO coupling, and the system turns to a BI phase no matter how large the Rashab SO coupling and bias voltage are. This will provide potential application in nanoelectronics based on silicene.

  15. High drain current density and reduced gate leakage current in channel-doped AlGaN /GaN heterostructure field-effect transistors with Al2O3/Si3N4 gate insulator

    NASA Astrophysics Data System (ADS)

    Maeda, Narihiko; Wang, Chengxin; Enoki, Takatomo; Makimoto, Toshiki; Tawara, Takehiko

    2005-08-01

    Channel-doped AlGaN /GaN heterostructure field-effect transistors (HFETs) with metal-insulator-semiconductor (MIS) structures have been fabricated to obtain the high drain current density and reduced gate leakage current. A thin bilayer dielectric of Al2O3(4nm)/Si3N4(1nm) was used as the gate insulator, to simultaneously take advantage of the high-quality interface between Si3N4 and AlGaN, and high resistivity and a high dielectric constant of Al2O3. A MIS HFET with a gate length of 1.5μm has exhibited a record high drain current density of 1.87A/mm at a gate voltage (Vg) of +3V, which is ascribed to a high applicable Vg and a very high two-dimensional electron gas (2DEG) density of 2.6×1013cm-2 in the doped channel. The gate leakage current was reduced by two or three orders of magnitude, compared with that in normal HFETs without a gate insulator. The transconductance (gm) was 168mS/mm, which is high in the category of the MIS structure. Channel-doped MIS HFETs fabricated have thus been proved to exhibit the high current density, reduced gate leakage current, and relatively high transconductance, hence, promising for high-power applications.

  16. Persistent optical gating of a topological insulator

    PubMed Central

    Yeats, Andrew L.; Pan, Yu; Richardella, Anthony; Mintun, Peter J.; Samarth, Nitin; Awschalom, David D.

    2015-01-01

    The spin-polarized surface states of topological insulators (TIs) are attractive for applications in spintronics and quantum computing. A central challenge with these materials is to reliably tune the chemical potential of their electrons with respect to the Dirac point and the bulk bands. We demonstrate persistent, bidirectional optical control of the chemical potential of (Bi,Sb)2Te3 thin films grown on SrTiO3. By optically modulating a space-charge layer in the SrTiO3 substrates, we induce a persistent field effect in the TI films comparable to electrostatic gating techniques but without additional materials or processing. This enables us to optically pattern arbitrarily shaped p- and n-type regions in a TI, which we subsequently image with scanning photocurrent microscopy. The ability to optically write and erase mesoscopic electronic structures in a TI may aid in the investigation of the unique properties of the topological insulating phase. The gating effect also generalizes to other thin-film materials, suggesting that these phenomena could provide optical control of chemical potential in a wide range of ultrathin electronic systems. PMID:26601300

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

    SciTech Connect

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

    2010-01-01

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

  18. High Electron Mobility Ge n-Channel Metal-Insulator-Semiconductor Field-Effect Transistors Fabricated by the Gate-Last Process with the Solid Source Diffusion Technique

    NASA Astrophysics Data System (ADS)

    Maeda, Tatsuro; Morita, Yukinori; Takagi, Shinichi

    2010-06-01

    We fabricate high-k/Ge n-channel metal-insulator-semiconductor field-effect transistors (MISFETs) by the gate-last process with the thermal solid source diffusion to achieve both of high quality source/drain (S/D) and gate stack. The n+/p junction formed by solid source diffusion technique of Sb dopant shows the excellent diode characteristics of ˜1.5×105 on/off ratio between +1 and -1 V and the quite low reverse current density of ˜4.1×10-4 A/cm2 at +1 V after the fabrication of high-k/Ge n-channel MISFETs that enable us to observe well-behaved transistor performances. The extracted electron mobility with the peak of 891 cm2/(V.s) is high enough to be superior to the Si universal electron mobility especially in low Eeff.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  20. Heavy ion induced permanent damage in MNOS gate insulators

    NASA Astrophysics Data System (ADS)

    Pickel, J. C.; Blandford, J. T., Jr.; Waskiewicz, A. E.; Strahan, V. H., Jr.

    1985-12-01

    Heavy-ion-induced permanent damage in MNOS gate insulators has been investigated using a Cf252 fission source. The electric field and ion LET thresholds for onset of the damage has been characterized. The results are consistent with a thermal runaway mechanism in the silicon nitride layer initiated by a single heavy ion and leading to a permanent high conductivity path through the dielectric layers.

  1. Electrical performance of silicon-on-insulator field-effect transistors with multiple top-gate organic layers in electrolyte solution.

    PubMed

    Khamaisi, Bassam; Vaknin, Oshri; Shaya, Oren; Ashkenasy, Nurit

    2010-08-24

    The utilization of field-effect transistor (FET) devices in biosensing applications have been extensively studied in recent years. Qualitative and quantitative understanding of the contribution of the organic layers constructed on the device gate, and the electrolyte media, on the behavior of the device is thus crucial. In this work we analyze the contribution of different organic layers on the pH sensitivity, threshold voltage, and gain of a silicon-on-insulator based FET device. We further monitor how these properties change as function of the electrolyte screening length. Our results show that in addition to electrostatic effects, changes in the amphoteric nature of the surface also affect the device threshold voltage. These effects were found to be additive for the first (3-aminopropyl)trimethoxysilane linker layer and second biotin receptor layer. For the top streptavidin protein layer, these two effects cancel each other. The number and nature of amphoteric groups on the surface, which changes upon the formation of the layers, was shown also to affect the pH sensitivity of the device. The pH sensitivity reduces with the construction of the first two layers. However, after the formation of the streptavidin protein layer, the protein's multiple charged side chains induce an increase in the sensitivity at low ionic strengths. Furthermore, the organic layers were found to influence the device gain due to their dielectric properties, reducing the gain with the successive construction of each layer. These results demonstrate the multilevel influence of organic layers on the behavior of the FET devices.

  2. Chemically gated electronic structure of a superconducting doped topological insulator system

    NASA Astrophysics Data System (ADS)

    Wray, L. A.; Xu, S.; Neupane, M.; Fedorov, A. V.; Hor, Y. S.; Cava, R. J.; Hasan, M. Z.

    2013-07-01

    Angle resolved photoemission spectroscopy is used to observe changes in the electronic structure of bulk-doped topological insulator CuxBi2Se3 as additional copper atoms are deposited onto the cleaved crystal surface. Carrier density and surface-normal electrical field strength near the crystal surface are estimated to consider the effect of chemical surface gating on atypical superconducting properties associated with topological insulator order, such as the dynamics of theoretically predicted Majorana Fermion vortices.

  3. A scheme for a topological insulator field effect transistor

    NASA Astrophysics Data System (ADS)

    Vali, Mehran; Dideban, Daryoosh; Moezi, Negin

    2015-05-01

    We propose a scheme for a topological insulator field effect transistor. The idea is based on the gate voltage control of the Dirac fermions in a ferromagnetic topological insulator channel with perpendicular magnetization connecting to two metallic topological insulator leads. Our theoretical analysis shows that the proposed device displays a switching effect with high on/off current ratio and a negative differential conductance with a good peak to valley ratio.

  4. Atomistic characterization of SAM coatings as gate insulators in Si-based FET devices

    SciTech Connect

    Gala, F.; Zollo, G.

    2014-06-19

    Many nano-material systems are currently under consideration as possible candidates for gate dielectric insulators in both metal-oxide-semiconductor (MOSFET) and organic (OFET) field-effect transistors. In this contribution, the possibility of employing self-assembled monolayers (SAMs) of hydroxylated octadecyltrichlorosilane (OTS) chains on a (111) Si substrate as gate dielectrics is discussed; in particular ab initio theoretical simulations have been employed to study the structural properties, work function modifications, and the insulating properties of OTS thin film coatings on Si substrates.

  5. Gas insulated transmission line with insulators having field controlling recesses

    DOEpatents

    Cookson, Alan H.; Pederson, Bjorn O.

    1984-01-01

    A gas insulated transmission line having a novel insulator for supporting an inner conductor concentrically within an outer sheath. The insulator has a recess contiguous with the periphery of one of the outer and inner conductors. The recess is disposed to a depth equal to an optimum gap for the dielectric insulating fluid used for the high voltage insulation or alternately disposed to a large depth so as to reduce the field at the critical conductor/insulator interface.

  6. Positive-bias gate-controlled metal–insulator transition in ultrathin VO2 channels with TiO2 gate dielectrics

    PubMed Central

    Yajima, Takeaki; Nishimura, Tomonori; Toriumi, Akira

    2015-01-01

    The next generation of electronics is likely to incorporate various functional materials, including those exhibiting ferroelectricity, ferromagnetism and metal–insulator transitions. Metal–insulator transitions can be controlled by electron doping, and so incorporating such a material in transistor channels will enable us to significantly modulate transistor current. However, such gate-controlled metal–insulator transitions have been challenging because of the limited number of electrons accumulated by gate dielectrics, or possible electrochemical reaction in ionic liquid gate. Here we achieve a positive-bias gate-controlled metal–insulator transition near the transition temperature. A significant number of electrons were accumulated via a high-permittivity TiO2 gate dielectric with subnanometre equivalent oxide thickness in the inverse-Schottky-gate geometry. An abrupt transition in the VO2 channel is further exploited, leading to a significant current modulation far beyond the capacitive coupling. This solid-state operation enables us to discuss the electrostatic mechanism as well as the collective nature of gate-controlled metal–insulator transitions, paving the pathway for developing functional field effect transistors. PMID:26657761

  7. Magnetic gating of a 2D topological insulator

    NASA Astrophysics Data System (ADS)

    Dang, Xiaoqian; Burton, J. D.; Tsymbal, Evgeny Y.

    2016-09-01

    Deterministic control of transport properties through manipulation of spin states is one of the paradigms of spintronics. Topological insulators offer a new playground for exploring interesting spin-dependent phenomena. Here, we consider a ferromagnetic ‘gate’ representing a magnetic adatom coupled to the topologically protected edge state of a two-dimensional (2D) topological insulator to modulate the electron transmission of the edge state. Due to the locked spin and wave vector of the transport electrons the transmission across the magnetic gate depends on the mutual orientation of the adatom magnetic moment and the current. If the Fermi energy matches an exchange-split bound state of the adatom, the electron transmission can be blocked due to the full back scattering of the incident wave. This antiresonance behavior is controlled by the adatom magnetic moment orientation so that the transmission of the edge state can be changed from 1 to 0. Expanding this consideration to a ferromagnetic gate representing a 1D chain of atoms shows a possibility to control the spin-dependent current of a strip of a 2D topological insulator by magnetization orientation of the ferromagnetic gate.

  8. Bio Organic-Semiconductor Field-Effect Transistor (BioFET) Based on Deoxyribonucleic Acid (DNA) Gate Dielectric

    DTIC Science & Technology

    2010-03-31

    floating gate devices and metal-insulator-oxide-semiconductor (MIOS) devices. First attempts to use polarizable gate insulators in combination with...organic semiconductors. The field effect transistors showed floating gate effects, but the potential for organic memories was not realized. Recently...

  9. Modelling and extraction procedure for gate insulator and fringing gate capacitance components of an MIS structure

    NASA Astrophysics Data System (ADS)

    Tinoco, J. C.; Martinez-Lopez, A. G.; Lezama, G.; Mendoza-Barrera, C.; Cerdeira, A.; Estrada, M.

    2016-07-01

    CMOS technology has been guided by the continuous reduction of MOS transistors used to fabricate integrated circuits. Additionally, the use of high-k dielectrics as well as a metal gate electrode have promoted the development of nanometric MOS transistors. Under this scenario, the proper modelling of the gate capacitance, with the aim of adequately evaluating the dielectric film thickness, becomes challenging for nanometric metal-insulator-semiconductor (MIS) structures due to the presence of extrinsic fringing capacitance components which affect the total gate capacitance. In this contribution, a complete intrinsic-extrinsic model for gate capacitance under accumulation of an MIS structure, together with an extraction procedure in order to independently determine the different capacitance components, is presented. ATLAS finite element simulation has been used to validate the proposed methodology.

  10. A high voltage silicon-on-insulator lateral insulated gate bipolar transistor with a reduced cell-pitch

    NASA Astrophysics Data System (ADS)

    Luo, Xiao-Rong; Wang, Qi; Yao, Guo-Liang; Wang, Yuan-Gang; Lei, Tian-Fei; Wang, Pei; Jiang, Yong-Heng; Zhou, Kun; Zhang, Bo

    2013-02-01

    A high voltage (> 600 V) integrable silicon-on-insulator (SOI) trench-type lateral insulated gate bipolar transistor (LIGBT) with a reduced cell-pitch is proposed. The LIGBT features multiple trenches (MTs): two oxide trenches in the drift region and a trench gate extended to the buried oxide (BOX). Firstly, the oxide trenches enhance electric field strength because of the lower permittivity of oxide than that of Si. Secondly, oxide trenches bring in multi-directional depletion, leading to a reshaped electric field distribution and an enhanced reduced-surface electric-field (RESURF) effect. Both increase the breakdown voltage (BV). Thirdly, oxide trenches fold the drift region around the oxide trenches, leading to a reduced cell-pitch. Finally, the oxide trenches enhance the conductivity modulation, resulting in a high electron/hole concentration in the drift region as well as a low forward voltage drop (Von). The oxide trenches cause a low anode—cathode capacitance, which increases the switching speed and reduces the turn-off energy loss (Eoff). The MT SOI LIGBT exhibits a BV of 603 V at a small cell-pitch of 24 μm, a Von of 1.03 V at 100 A/cm-2, a turn-off time of 250 ns and Eoff of 4.1×10-3 mJ. The trench gate extended to BOX synchronously acts as dielectric isolation between high voltage LIGBT and low voltage circuits, simplifying the fabrication processes.

  11. High on/off current ratio in ballistic CNTFETs based on tuning the gate insulator parameters for different ambient temperatures

    NASA Astrophysics Data System (ADS)

    Shirazi, Shaahin G.; Mirzakuchaki, Sattar

    2013-11-01

    A theoretical study is presented on the on/off current ratio limits for a ballistic coaxially-gated carbon nanotube field effect transistor (CNTFET) with highly doped source/drain regions. Based on changes in gate insulator dielectric constant and thickness, the current ratio has been estimated at different ambient temperatures. Decreasing the gate insulator thickness after a certain value around 3 nm causes the current ratio to degrade drastically. Although the higher dielectric constant values have a fair effect on current ratio, this effect could be suppressed when the device with a low gate insulator thickness works at a low ambient temperature. The simulation results also show that the temperature drastically degrades the current ratio value; whereas in a certain range of ambient temperature, tuning the values of gate insulator thickness and dielectric constant could be very helpful. In this way, the optimum values of gate insulator thickness and dielectric constant are identified to offer the highest on/off current ratio of the device.

  12. Gas-controlled dynamic vacuum insulation with gas gate

    DOEpatents

    Benson, David K.; Potter, Thomas F.

    1994-06-07

    Disclosed is a dynamic vacuum insulation comprising sidewalls enclosing an evacuated chamber and gas control means for releasing hydrogen gas into a chamber to increase gas molecule conduction of heat across the chamber and retrieving hydrogen gas from the chamber. The gas control means includes a metal hydride that absorbs and retains hydrogen gas at cooler temperatures and releases hydrogen gas at hotter temperatures; a hydride heating means for selectively heating the metal hydride to temperatures high enough to release hydrogen gas from the metal hydride; and gate means positioned between the metal hydride and the chamber for selectively allowing hydrogen to flow or not to flow between said metal hydride and said chamber.

  13. Gas-controlled dynamic vacuum insulation with gas gate

    DOEpatents

    Benson, D.K.; Potter, T.F.

    1994-06-07

    Disclosed is a dynamic vacuum insulation comprising sidewalls enclosing an evacuated chamber and gas control means for releasing hydrogen gas into a chamber to increase gas molecule conduction of heat across the chamber and retrieving hydrogen gas from the chamber. The gas control means includes a metal hydride that absorbs and retains hydrogen gas at cooler temperatures and releases hydrogen gas at hotter temperatures; a hydride heating means for selectively heating the metal hydride to temperatures high enough to release hydrogen gas from the metal hydride; and gate means positioned between the metal hydride and the chamber for selectively allowing hydrogen to flow or not to flow between said metal hydride and said chamber. 25 figs.

  14. Gate-to-body tunneling current model for silicon-on-insulator MOSFETs

    NASA Astrophysics Data System (ADS)

    Wu, Qing-Qing; Chen, Jing; Luo, Jie-Xin; Lü, Kai; Yu, Tao; Chai, Zhan; Wang, Xi

    2013-10-01

    A gate-to-body tunneling current model for silicon-on-insulator (SOI) devices is simulated. As verified by the measured data, the model, considering both gate voltage and drain voltage dependence as well as image force-induced barrier low effect, provides a better prediction of the tunneling current and gate-induced floating body effect than the BSIMSOI4 model. A delayed gate-induced floating body effect is also predicted by the model.

  15. Monte Carlo simulation of double gate silicon on insulator devices operated as velocity modulation transistors

    NASA Astrophysics Data System (ADS)

    Sampedro, C.; Gamiz, F.; Godoy, A.; Prunnila, M.; Ahopelto, J.

    2005-05-01

    We used an ensemble Monte Carlo simulator to study both the dc and transient behavior of a double gate silicon-on-insulator transistor (DGSOI) operated as a velocity modulation transistor (VMT) and as a conventional field effect transistor (FET). Operated as a VMT, the DGSOI transistor provides switching times shorter than 1ps regardless of the channel length, with a significant current modulation factor at room temperature. The same device operated as a FET provides much longer switching times which, in addition, increase with the channel length.

  16. Electrical Probing of Inherent Spin Polarization in a Topological Insulator with Electrical Gating

    NASA Astrophysics Data System (ADS)

    Lee, Joon Sue; Richardella, Anthony; Samarth, Nitin

    2015-03-01

    The hallmark of a time-reversal symmetry protected three-dimensional topological insulator is the helically spin-textured surface state. Although electrical detection of spin polarization in topological insulators has been demonstrated very recently, there have not been any electrical measurements to demonstrate the entire mapping of the spin polarization throughout the surface state. We report the electrical probing of the spin-polarized surface state using a magnetic tunnel junction as a spin detector while the chemical potential of a topological insulator (Bi,Sb)2Te3 is tuned by back gating. Hysteretic spin signals were observed as the magnetization of the detector ferromagnet (permalloy) switches with in-plane magnetic field. Changing the direction of bias current through the topological insulator channel flips the direction of the spin polarization, resulting in the reverse of sign of the detected spin signals. We demonstrate the control of the Fermi energy, which has importance not only in further understanding of the spin-momentum locking in the surface state but also in possible electrical tuning of the spin polarization for potential spin-based devices. Supported by C-SPIN & DARPA/SRC.

  17. Quantum Dot Channel (QDC) FETs with Wraparound II-VI Gate Insulators: Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Jain, F.; Lingalugari, M.; Kondo, J.; Mirdha, P.; Suarez, E.; Chandy, J.; Heller, E.

    2016-11-01

    This paper presents simulations predicting the feasibility of 9-nm wraparound quantum dot channel (QDC) field-effect transistors (FETs). In particular, II-VI lattice-matched layers which reduce the density of interface states, serving as top (tunnel gate), side, and bottom gate insulators, have been simulated. Quantum simulations show FET operation with voltage swing of ~0.2 V. Incorporation of cladded quantum dots, such as SiO x -Si and GeO x -Ge, under the gate tunnel oxide results in electrical transport in one or more quantum dot layers which form a quantum dot superlattice (QDSL). Long-channel QDC FETs have experimental multistate drain current ( I D)-gate voltage ( V G) and drain current ( I D)-drain voltage ( V D) characteristics, which can be attributed to the manifestation of extremely narrow energy minibands formed in the QDSL. An approach for modeling the multistate I D- V G characteristics is reported. The multistate characteristics of QDC FETs permit design of compact two-bit multivalued logic circuits.

  18. Accessing Rashba states in electrostatically gated topological insulator devices

    NASA Astrophysics Data System (ADS)

    Banerjee, Abhishek; Sundaresh, Ananthesh; Majhi, Kunjalata; Ganesan, R.; Anil Kumar, P. S.

    2016-12-01

    We study the low temperature electrical transport in gated BiSbTe1.25Se1.75/hexagonal-Boron Nitride van der Waals heterostructure devices. Our experiments indicate the presence of Rashba spin-split states confined to the sample surface. While such states have been observed previously in photo-emission spectroscopy and STM experiments, it has not been possible to unambiguously detect them by electrical means and their transport properties remain mostly unknown. We show that these states support high mobility conduction with Hall effect mobilities ˜2000 to 3000 cm2/V-s that are paradoxically much larger than the mobilities of the topological surface states ˜300 cm2/V-s at T = 2 K. The spin-split nature of these states is confirmed by magneto-resistance measurements that reveal multi-channel weak anti-localization. Our work shows that Rashba spin split states can be electrically accessed in Topological insulators paving the way for future spintronic applications.

  19. Characterization and modeling of the power Insulated Gate Bipolar Transistor

    SciTech Connect

    Hefner, A.R.

    1987-01-01

    The power Insulated Gate Bipolar Transistor (IGBT) is a new switching device designed to overcome the high on-state loss of the power MOSFET. The IGBT behaves as a bipolar transistor which is supplied base current by a MOSFET. The bipolar transistor of the IBGT has a wide base with the base contact at the collector edge of the base and is operated with its base in high-level injection. Because of this, the traditional bipolar transistor models are not adequate for the IBGT and the new model developed in this dissertation must be used. The new model is developed using ambipolar transport and does not assume the quasi-static condition for the transient analysis. The new IBGT model is used to describe measurements for extracting the essential physical device parameters of the model. With these extracted parameters, the new IGBT model consistently describes the measured electrical characteristics of IGBTs with different base lifetimes. The important electrical characteristics of the IGBT are the on-state I-V characteristics, the steady-state saturation current, and the switching transient current and voltage waveforms. The transient waveforms are examined in detail for constant anode voltage switching, clamped inductive load switching, and series resistor, inductor load switching.

  20. Characterization of insulated-gate bipolar transistor temperature on insulating, heat-spreading polycrystalline diamond substrate

    NASA Astrophysics Data System (ADS)

    Umezawa, Hitoshi; Shikata, Shin-ichi; Kato, Yukako; Mokuno, Yoshiaki; Seki, Akinori; Suzuki, Hiroshi; Bessho, Takeshi

    2017-01-01

    Polycrystalline diamond films have been utilized as direct bonding aluminum (DBA) substrates to improve cooling efficiency. A diamond film with a high quality factor was characterized by Raman spectroscopy and showed a high thermal conductivity of more than 1800 W m-1 K-1 and a low leakage current, even at an applied bias of 3 kV, because of the suppression of electrical conduction through the grain boundaries. The operating temperatures of Insulated-gate bipolar transistors (IGBTs) on diamond DBAs were 20-28% lower than those on AlN DBAs. The thermal resistivity of the diamond DBA module was 0.32 °C/W. The uniformity of the temperature distribution on a diamond DBA was excellent.

  1. Oleyl group-functionalized insulating gate transistors for measuring extracellular pH of floating cells

    PubMed Central

    Imaizumi, Yuki; Goda, Tatsuro; Toya, Yutaro; Matsumoto, Akira; Miyahara, Yuji

    2016-01-01

    Abstract The extracellular ionic microenvironment has a close relationship to biological activities such as by cellular respiration, cancer development, and immune response. A system composed of ion-sensitive field-effect transistors (ISFET), cells, and program-controlled fluidics has enabled the acquisition of real-time information about the integrity of the cell membrane via pH measurement. Here we aimed to extend this system toward floating cells such as T lymphocytes for investigating complement activation and pharmacokinetics through alternations in the plasma membrane integrity. We functionalized the surface of tantalum oxide gate insulator of ISFET with oleyl-tethered phosphonic acid for interacting with the plasma membranes of floating cells without affecting the cell signaling. The surface modification was characterized by X-ray photoelectron spectroscopy and water contact angle measurements. The Nernst response of −37.8 mV/pH was obtained for the surface-modified ISFET at 37 °C. The oleyl group-functionalized gate insulator successfully captured Jurkat T cells in a fluidic condition without acute cytotoxicity. The system was able to record the time course of pH changes at the cells/ISFET interface during the process of instant addition and withdrawal of ammonium chloride. Further, the plasma membrane injury of floating cells after exposure by detergent Triton™ X-100 was successfully determined using the modified ISFET with enhanced sensitivity as compared with conventional hemolysis assays. PMID:27877886

  2. Modeling and estimation of process-induced stress in the nanowire field-effect-transistors (NW-FETs) on Insulator-on-Silicon substrates with high-k gate-dielectrics

    NASA Astrophysics Data System (ADS)

    Chatterjee, Sulagna; Chattopadhyay, Sanatan

    2016-10-01

    An analytical model including the simultaneous impact of lattice and thermo-elastic constant mismatch-induced stress in nanowires on Insulator-on-Silicon substrate is developed. It is used to calibrate the finite-element based software, ANSYS, which is subsequently employed to estimate process-induced stress in the sequential steps of NW-FET fabrication. The model considers crystal structures and orientations for both the nanowires and substrates. In-plane stress components along nanowire-axis are estimated for different radii and fractions of insertion. Nature of longitudinal stress is observed to change when inserted fraction of nanowires is changed. Effect of various high-k gate-dielectrics is also investigated. A longitudinal tensile stress of 2.4 GPa and compressive stress of 1.89 GPa have been obtained for NW-FETs with 1/4th and 3/4th insertions with La2O3 and TiO2 as the gate-dielectrics, respectively. Therefore, it is possible to achieve comparable values of electron and hole mobility in NW-FETs by judiciously choosing gate-dielectrics and fractional insertion of the nanowires.

  3. Engineered Ceramic Insulators for High Field Magnets

    NASA Astrophysics Data System (ADS)

    Rice, J. A.

    2006-03-01

    High field magnet coils made from brittle A15 superconductors need to be rigidly contained by their support structure but yet be electrically insulated from it. Current insulators (end shoes, pole pieces, spacers, mandrels, etc.) are often made from coated metallic shapes that satisfy the mechanical and thermal requirements but are electrically unreliable. The insulating coating on the metal core too often chips or flakes, causing electrical shorts. Any replacement insulator materials must manage the thermal expansion mismatch to control the stress within the coil enabling the achievement of ultimate magnet performance. A novel ceramic insulator has been developed that eliminates the potential for shorting while maintaining high structural integrity and thermal performance. The insulator composition can be engineered to provide a thermal expansion that matches the coil expansion, minimizing detrimental stress on the superconductor. These ceramic insulators are capable of surviving high temperature heat treatments and are radiation resistant. The material can withstand high mechanical loads generated during magnet operation. These more robust insulators will lower the magnet production costs, which will help enable future devices to be constructed within budgetary restrictions.

  4. Positive Bias Instability of Bottom-Gate Zinc Oxide Thin-Film Transistors with a SiOx/SiNx-Stacked Gate Insulator

    NASA Astrophysics Data System (ADS)

    Furuta, Mamoru; Kamada, Yudai; Hiramatsu, Takahiro; Li, Chaoyang; Kimura, Mutsumi; Fujita, Shizuo; Hirao, Takashi

    2011-03-01

    The positive bias instabilities of the zinc oxide thin-film transistors (ZnO TFTs) with a SiOx/SiNx-stacked gate insulator have been investigated. The film quality of a gate insulator of SiOx, which forms an interface with the ZnO channel, was varied by changing the gas mixture ratio of SiH4/N2O/N2 during plasma-enhanced chemical vapor deposition. The positive bias stress endurance of ZnO TFT strongly depended on the deposition condition of the SiOx gate insulator. From the relaxations of the transfer curve shift after imposition of positive bias stress, transfer curves could not be recovered completely without any thermal annealing. A charge trapping in a gate insulator rather than that in bulk ZnO and its interface with a gate insulator is a dominant instability mechanism of ZnO TFTs under positive bias stress.

  5. Protected gates for topological quantum field theories

    NASA Astrophysics Data System (ADS)

    Beverland, Michael E.; Buerschaper, Oliver; Koenig, Robert; Pastawski, Fernando; Preskill, John; Sijher, Sumit

    2016-02-01

    We study restrictions on locality-preserving unitary logical gates for topological quantum codes in two spatial dimensions. A locality-preserving operation is one which maps local operators to local operators — for example, a constant-depth quantum circuit of geometrically local gates, or evolution for a constant time governed by a geometrically local bounded-strength Hamiltonian. Locality-preserving logical gates of topological codes are intrinsically fault tolerant because spatially localized errors remain localized, and hence sufficiently dilute errors remain correctable. By invoking general properties of two-dimensional topological field theories, we find that the locality-preserving logical gates are severely limited for codes which admit non-abelian anyons, in particular, there are no locality-preserving logical gates on the torus or the sphere with M punctures if the braiding of anyons is computationally universal. Furthermore, for Ising anyons on the M-punctured sphere, locality-preserving gates must be elements of the logical Pauli group. We derive these results by relating logical gates of a topological code to automorphisms of the Verlinde algebra of the corresponding anyon model, and by requiring the logical gates to be compatible with basis changes in the logical Hilbert space arising from local F-moves and the mapping class group.

  6. Protected gates for topological quantum field theories

    SciTech Connect

    Beverland, Michael E.; Pastawski, Fernando; Preskill, John; Buerschaper, Oliver; Koenig, Robert; Sijher, Sumit

    2016-02-15

    We study restrictions on locality-preserving unitary logical gates for topological quantum codes in two spatial dimensions. A locality-preserving operation is one which maps local operators to local operators — for example, a constant-depth quantum circuit of geometrically local gates, or evolution for a constant time governed by a geometrically local bounded-strength Hamiltonian. Locality-preserving logical gates of topological codes are intrinsically fault tolerant because spatially localized errors remain localized, and hence sufficiently dilute errors remain correctable. By invoking general properties of two-dimensional topological field theories, we find that the locality-preserving logical gates are severely limited for codes which admit non-abelian anyons, in particular, there are no locality-preserving logical gates on the torus or the sphere with M punctures if the braiding of anyons is computationally universal. Furthermore, for Ising anyons on the M-punctured sphere, locality-preserving gates must be elements of the logical Pauli group. We derive these results by relating logical gates of a topological code to automorphisms of the Verlinde algebra of the corresponding anyon model, and by requiring the logical gates to be compatible with basis changes in the logical Hilbert space arising from local F-moves and the mapping class group.

  7. Gate-tuned superconductor-insulator transition in (Li,Fe)OHFeSe

    NASA Astrophysics Data System (ADS)

    Lei, B.; Xiang, Z. J.; Lu, X. F.; Wang, N. Z.; Chang, J. R.; Shang, C.; Zhang, A. M.; Zhang, Q. M.; Luo, X. G.; Wu, T.; Sun, Z.; Chen, X. H.

    2016-02-01

    The antiferromagnetic (AFM) insulator-superconductor transition has always been a center of interest in the underlying physics of unconventional superconductors. However, in the family of iron-based high-Tc superconductors, no intrinsic superconductor-insulator transition has been confirmed so far. Here, we report a first-order transition from superconductor to AFM insulator with a strong charge doping induced by ionic gating in the thin flakes of single crystal (Li,Fe)OHFeSe. The superconducting transition temperature (Tc) is continuously enhanced with electron doping by ionic gating up to a maximum Tc of 43 K, and a striking superconductor-insulator transition occurs just at the verge of optimal doping with highest Tc. A phase diagram of temperature-gating voltage with the superconductor-insulator transition is mapped out, indicating that the superconductor-insulator transition is a common feature for unconventional superconductivity. These results help to uncover the underlying physics of iron-based superconductivity as well as the universal mechanism of high-Tc superconductivity. Our finding also suggests that the gate-controlled strong charge doping makes it possible to explore novel states of matter in a way beyond traditional methods.

  8. 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).

  9. Tuning the metal-insulator crossover and magnetism in SrRuO3 by ionic gating

    SciTech Connect

    Yi, Hee Taek; Gao, Bin; Xie, Wei; Cheong, Sang -Wook; Podzorov, Vitaly

    2014-10-13

    Reversible control of charge transport and magnetic properties without degradation is a key for device applications of transition metal oxides. Chemical doping during the growth of transition metal oxides can result in large changes in physical properties, but in most of the cases irreversibility is an inevitable constraint. We report a reversible control of charge transport, metal-insulator crossover and magnetism in field-effect devices based on ionically gated archetypal oxide system - SrRuO3. In these thin-film devices, the metal-insulator crossover temperature and the onset of magnetoresistance can be continuously and reversibly tuned in the range 90–250 K and 70–100 K, respectively, by application of a small gate voltage. We infer that a reversible diffusion of oxygen ions in the oxide lattice dominates the response of these materials to the gate electric field. These findings provide critical insights into both the understanding of ionically gated oxides and the development of novel applications.

  10. Tuning the metal-insulator crossover and magnetism in SrRuO3 by ionic gating

    DOE PAGES

    Yi, Hee Taek; Gao, Bin; Xie, Wei; ...

    2014-10-13

    Reversible control of charge transport and magnetic properties without degradation is a key for device applications of transition metal oxides. Chemical doping during the growth of transition metal oxides can result in large changes in physical properties, but in most of the cases irreversibility is an inevitable constraint. We report a reversible control of charge transport, metal-insulator crossover and magnetism in field-effect devices based on ionically gated archetypal oxide system - SrRuO3. In these thin-film devices, the metal-insulator crossover temperature and the onset of magnetoresistance can be continuously and reversibly tuned in the range 90–250 K and 70–100 K, respectively,more » by application of a small gate voltage. We infer that a reversible diffusion of oxygen ions in the oxide lattice dominates the response of these materials to the gate electric field. These findings provide critical insights into both the understanding of ionically gated oxides and the development of novel applications.« less

  11. Floating-Gate Type Organic Memory with Organic Insulator Thin Film of Plasma Polymerized Methyl Methacrylate

    NASA Astrophysics Data System (ADS)

    Kim, Hee-sung; Lee, Boong-Joo; Kim, Gun-Su; Shin, Paik-Kyun

    2013-02-01

    To fabricate organic memory device by entirely dry process, plasma polymerized methyl methacrylate (ppMMA) thin films were prepared and they were used as both tunneling layer and gate insulator layer in a floating-gate type organic memory device. The ppMMA thin films were prepared with inductively coupled plasma (ICP) source combined with stabilized monomer vapor control. The ppMMA gate insulator thin film revealed dielectric constant of 3.75 and low leakage current of smaller than 10-9 A/cm. The floating-gate type organic memory device showed promising memory characteristics such as memory window value of 12 V and retention time of over 2 h, where 60 V of writing voltage and -30 V of erasing voltage were applied, respectively.

  12. Combined gate-tunable Josephson junctions and normal state transport in Bi2Te3 topological insulator thin films

    NASA Astrophysics Data System (ADS)

    Ngabonziza, Prosper; Stehno, Martin, P.; Myoren, Hiroaki; Brinkman, Alexander

    In recent years, extensive efforts have been made to improve the coupling between topological insulators and s-wave superconductors in topological insulator Josephson devices (TIJDs). Despite significant progress, essential questions remain open such as the bulk contribution to the Josephson critical current or the existence (and number) of 4 π -periodic bound states (Majoranas) in TIJDs. To address these issues, we fabricated Nb/Bi2Te3/Nb Josephson junctions alongside Hall bar devices on MBE-grown Bi2Te3 topological insulator thin films. Using the SrTiO3 [111] substrate as a gate dielectric, we tuned the carrier density electrostatically and measured the Josephson supercurrent and the normal state transport properties of our thin film devices. We identify three gate voltage ranges with distinct behavior: A region of intermediate gate bias where the measured quantities change rapidly with the applied electric field, and two saturation regions for large bias of either polarity. We discuss carrier distribution and band alignment in the material as well as implications for the effective Josephson coupling in TIJDs. This work is financially supported by the Dutch Foundation for Fundamental Research on Matter (FOM), the Netherlands Organization for Scientific Research (NWO), and by the European Research Council (ERC).

  13. Soft-switching performance analysis of the clustered insulated gate bipolar transistor (CIGBT)

    NASA Astrophysics Data System (ADS)

    Nicholls, Jonathan Christopher

    The use of Insulated Gate Bipolar Transistors (IGBT) have enabled better switching performance than the Metal Oxide Semiconductor Field effect Transistor (MOSFET) in medium to high power applications due to their lower on-state power loss and higher current densities. This current research focuses on the Clustered Insulated Gate Bipolar Transistor (CIGBT) whilst being operated under soft-switching regimes. The CIGBT is a MOS gated thyristor device that exhibits a unique self-clamping feature that protects cathode cells from high anode voltages under all operating conditions. The self-clamping feature also enables current saturation at high gate biases and provides low switching losses. Its low on-state voltage and high voltage blocking capabilities make the CIGBT suitable as a contender to the IGBT in medium to high power switching applications. For the first time, the CIGBT has been operated under soft-switching regimes and transient over-voltages at turn-on have been witnessed which have been found to be associated with a number of factors.. The internal dynamics of the CIGBT have been analysed using 2D numerical simulations and it has been shown that a major influence on the peak voltage is the P well spacing within the CIGBT structure. For example, Small adjacent P well spacings within the device results in an inability for the CIGBT to switch iv on correctly. Further to this, implant concentrations of the n well region during device fabrication can also affect the turn-on transients. Despite this, the CIGBT has been experimental analysed under soft-switching conditions and found to outperform the IGBT by 12% and 27% for on-state voltage drop and total energy losses respectively. Turn off current bumps have been seen whilst switching the device in zero voltage and zero current switching mode of operation and the internal dynamics have been analysed to show the influence upon the current at turn off. Preliminary results on the Trench CIGBT (TCIGBT) under soft

  14. Surface modification of a polyimide gate insulator with an yttrium oxide interlayer for aqueous-solution-processed ZnO thin-film transistors.

    PubMed

    Jang, Kwang-Suk; Wee, Duyoung; Kim, Yun Ho; Kim, Jinsoo; Ahn, Taek; Ka, Jae-Won; Yi, Mi Hye

    2013-06-11

    We report a simple approach to modify the surface of a polyimide gate insulator with an yttrium oxide interlayer for aqueous-solution-processed ZnO thin-film transistors. It is expected that the yttrium oxide interlayer will provide a surface that is more chemically compatible with the ZnO semiconductor than is bare polyimde. The field-effect mobility and the on/off current ratio of the ZnO TFT with the YOx/polyimide gate insulator were 0.456 cm(2)/V·s and 2.12 × 10(6), respectively, whereas the ZnO TFT with the polyimide gate insulator was inactive.

  15. Combined scheme of UV/ozone and HMDS treatment on a gate insulator for performance improvement of a low-temperature-processed bottom-contact OTFT

    NASA Astrophysics Data System (ADS)

    Fan, Ching-Lin; Lin, Yu-Zuo; Huang, Cheng-Han

    2011-04-01

    This study investigates the performance improvement of a pentacene-based OTFT (organic thin-film transistor) by the combined scheme of UV/ozone cleaning and hexamethyldisilazane coating on a gate insulator. Because the surface energy and the trap state density of the gate insulator were effectively improved, the combined scheme can significantly advance the performances of the OTFT, compared to those of the samples without any surface treatments, such that the field-effect mobility was dramatically increased by about three orders of magnitude and the on-current was increased by 185%.

  16. Radiation hardening of MOS devices by boron. [for stabilizing gate threshold potential of field effect device

    NASA Technical Reports Server (NTRS)

    Danchenko, V. (Inventor)

    1974-01-01

    A technique is described for radiation hardening of MOS devices and specifically for stabilizing the gate threshold potential at room temperature of a radiation subjected MOS field-effect device with a semiconductor substrate, an insulating layer of oxide on the substrate, and a gate electrode disposed on the insulating layer. The boron is introduced within a layer of the oxide of about 100 A-300 A thickness immediately adjacent the semiconductor-insulator interface. The concentration of boron in the oxide layer is preferably maintained on the order of 10 to the 18th power atoms/cu cm. The technique serves to reduce and substantially annihilate radiation induced positive gate charge accumulations.

  17. Dual-gated topological insulator thin-film device for efficient Fermi-level tuning.

    PubMed

    Yang, Fan; Taskin, A A; Sasaki, Satoshi; Segawa, Kouji; Ohno, Yasuhide; Matsumoto, Kazuhiko; Ando, Yoichi

    2015-04-28

    Observations of novel quantum phenomena expected for three-dimensional topological insulators (TIs) often require fabrications of thin-film devices and tuning of the Fermi level across the Dirac point. Since thin films have both top and bottom surfaces, an effective control of the surface chemical potential requires dual gating. However, a reliable dual-gating technique for TI thin films has not yet been developed. Here we report a comprehensive method to fabricate a dual-gated TI device and demonstrate tuning of the chemical potential of both surfaces across the Dirac points. The most important part of our method is the recipe for safely detaching high-quality, bulk-insulating (Bi(1-x)Sb(x))2Te3 thin films from sapphire substrates and transferring them to Si/SiO2 wafers that allow back gating. Fabrication of an efficient top gate by low-temperature deposition of a SiN(x) dielectric complements the procedure. Our dual-gated devices are shown to be effective in tuning the chemical potential in a wide range encompassing the Dirac points on both surfaces.

  18. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators.

    PubMed

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P

    2016-05-04

    Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at the double Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. Such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation.

  19. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P.

    2016-05-01

    Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at the double Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. Such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation.

  20. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators

    SciTech Connect

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P.

    2016-05-04

    Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at the double Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. As a result, such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation.

  1. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators

    DOE PAGES

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P.

    2016-05-04

    Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at the doublemore » Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. As a result, such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation.« less

  2. Gate insulator effects on the electrical performance of ZnO thin film transistor on a polyethersulphone substrate.

    PubMed

    Lee, Jae-Kyu; Choi, Duck-Kyun

    2012-07-01

    Low temperature processing for fabrication of transistor backplane is a cost effective solution while fabrication on a flexible substrate offers a new opportunity in display business. Combination of both merits is evaluated in this investigation. In this study, the ZnO thin film transistor on a flexible Polyethersulphone (PES) substrate is fabricated using RF magnetron sputtering. Since the selection and design of compatible gate insulator is another important issue to improve the electrical properties of ZnO TFT, we have evaluated three gate insulator candidates; SiO2, SiNx and SiO2/SiNx. The SiO2 passivation on both sides of PES substrate prior to the deposition of ZnO layer was effective to enhance the mechanical and thermal stability. Among the fabricated devices, ZnO TFT employing SiNx/SiO2 stacked gate exhibited the best performance. The device parameters of interest are extracted and the on/off current ratio, field effect mobility, threshold voltage and subthreshold swing are 10(7), 22 cm2/Vs, 1.7 V and 0.4 V/decade, respectively.

  3. ZnO thin-film transistors with a polymeric gate insulator built on a polyethersulfone substrate

    NASA Astrophysics Data System (ADS)

    Hyung, Gun Woo; Park, Jaehoon; Koo, Ja Ryong; Choi, Kyung Min; Kwon, Sang Jik; Cho, Eou Sik; Kim, Yong Seog; Kim, Young Kwan

    2012-03-01

    Zinc oxide (ZnO) thin-film transistors (TFTs) with a cross-linked poly(vinyl alcohol) (c-PVA) insulator are fabricated on a polyethersulfone substrate. The ZnO film, formed by atomic layer deposition, shows a polycrystalline hexagonal structure with a band gap energy of about 3.37 eV. The fabricated ZnO TFT exhibits a field-effect mobility of 0.38 cm2/Vs and a threshold voltage of 0.2 V. The hysteresis of the device is mainly caused by trapped electrons at the c-PVA/ZnO interface, whereas the positive threshold voltage shift occurs as a consequence of constant positive gate bias stress after 5000 s due to an electron injection from the ZnO film into the c-PVA insulator.

  4. Electric-field-induced superconductivity in an insulator.

    PubMed

    Ueno, K; Nakamura, S; Shimotani, H; Ohtomo, A; Kimura, N; Nojima, T; Aoki, H; Iwasa, Y; Kawasaki, M

    2008-11-01

    Electric field control of charge carrier density has long been a key technology to tune the physical properties of condensed matter, exploring the modern semiconductor industry. One of the big challenges is to increase the maximum attainable carrier density so that we can induce superconductivity in field-effect-transistor geometry. However, such experiments have so far been limited to modulation of the critical temperature in originally conducting samples because of dielectric breakdown. Here we report electric-field-induced superconductivity in an insulator by using an electric-double-layer gating in an organic electrolyte. Sheet carrier density was enhanced from zero to 10(14) cm(-2) by applying a gate voltage of up to 3.5 V to a pristine SrTiO(3) single-crystal channel. A two-dimensional superconducting state emerged below a critical temperature of 0.4 K, comparable to the maximum value for chemically doped bulk crystals, indicating this method as promising for searching for unprecedented superconducting states.

  5. Novel trench gate field stop IGBT with trench shorted anode

    NASA Astrophysics Data System (ADS)

    Xudong, Chen; Jianbing, Cheng; Guobing, Teng; Houdong, Guo

    2016-05-01

    A novel trench field stop (FS) insulated gate bipolar transistor (IGBT) with a trench shorted anode (TSA) is proposed. By introducing a trench shorted anode, the TSA-FS-IGBT can obviously improve the breakdown voltage. As the simulation results show, the breakdown voltage is improved by a factor of 19.5% with a lower leakage current compared with the conventional FS-IGBT. The turn off time of the proposed structure is 50% lower than the conventional one with less than 9% voltage drop increased at a current density of 150 A/cm2. Additionally, there is no snapback observed. As a result, the TSA-FS-IGBT has a better trade-off relationship between the turn off loss and forward drop. Project supported by the National Natural Science Foundation of China (No. 61274080) and the Postdoctoral Science Foundation of China (No. 2013M541585).

  6. Extremely large, gate tunable spin Hall angle in 3D Topological Insulator pn junction

    NASA Astrophysics Data System (ADS)

    Habib, K. M. Masum; Sajjad, Redwan; Ghosh, Avik

    2015-03-01

    The band structure of the surface states of a three dimensional Topological Insulator (3D TI) is similar to that of graphene featuring massless Dirac Fermions. We show that due to this similarity, the chiral tunneling of electron in a graphene pn junction also appears in 3D TI. Electrons with very small incident angle (modes) are allowed to transmit through a TI pn junction (TIPNJ) due to the chiral tunneling. The rest of the electrons are reflected. As a result, the charge current in a TIPNJ is suppressed. Due to the spin momentum locking, all the small angle modes are spin-down states. Therefore, the transmitted end of the TIPNJ becomes highly spin polarized. On the other hand, the spin of the reflected electron is flipped due to spin momentum locking. This enhances the spin current at the injection end. Thus, the interplay between the chiral tunneling and spin momentum locking reduces the charge current but enhances the spin current at the same time, leading to an extremely large (~20) spin Hall angle. Since the chiral tunneling can be controlled by an external electric field, the spin Hall angle is gate tunable. The spin current generated by a TIPNJ can be used for energy-efficient switching of nanoscaled ferromagnets, which is an essential part of spintronic devices. This work is supported by the NRI INDEX center.

  7. Characterization of Chemical Trends in Magnetically Doped, Electrically Gated Topological Insulator Thin Films

    NASA Astrophysics Data System (ADS)

    Richardella, Anthony; Kandala, Abhinav; Lee, Joon Sue; Fraleigh, Robbie; Samarth, Nitin; Liu, Minhao; Ong, Nai Phuan; Tao, Jing

    2014-03-01

    Interfacing topological insulators (TIs) with magnetism breaks time reversal symmetry and opens a gap in the surface states at the Dirac point. This results in novel phenomena, such as the recently reported quantized conductance at zero applied external magnetic field due to the quantum anomalous Hall effect (QAHE) in Cr doped (BixSb1-x)2 Te3 [C-Z. Chang, et al., Science 340, 167 (2013)]. We have studied magnetically doped (BixSb1-x)2 Te3 thin films grown by MBE on SrTiO3(111) (STO) substrates using Cr, Fe and Mn as magnetic dopants and as a function of the Bi and Sb composition. These films are carefully characterized by XRD, AFM, SQUID magnetometry and TEM. The chemical composition is determined using SIMS, RBS and XRF. Low temperature transport shows a large gate-tunable Hall effect in Cr doped samples and systematically varying longitudinal magneto-conductance as the Fermi energy is tuned through the Dirac point. The origin of ferromagnetism and its dependence on the chemical potential, chemical composition and sample thickness is discussed. Funded by DARPA and ARO-MURI.

  8. A dual-gate and dielectric-inserted lateral trench insulated gate bipolar transistor on a silicon-on-insulator substrate

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Zhang, Bo; Luo, Xiao-Rong; Li, Zhao-Ji

    2013-07-01

    In this paper, a novel dual-gate and dielectric-inserted lateral trench insulated gate bipolar transistor (DGDI LTIGBT) structure, which features a double extended trench gate and a dielectric inserted in the drift region, is proposed and discussed. The device can not only decrease the specific on-resistance Ron,sp, but also simultaneously improve the temperature performance. Simulation results show that the proposed LTIGBT achieves an ultra-low on-state voltage drop of 1.31 V at 700 A·cm-2 with a small half-cell pitch of 10.5 μm, a specific on-resistance Ron,sp of 187 mΩ·mm2, and a high breakdown voltage of 250 V. The on-state voltage drop of the DGDI LTIGBT is 18% less than that of the DI LTIGBT and 30.3% less than that of the conventional LTIGBT. The proposed LTIGBT exhibits a good positive temperature coefficient for safety paralleling to handling larger currents and enhances the short-circuit capability while maintaining a low self-heating effect. Furthermore, it also shows a better tradeoff between the specific on-resistance and the turnoff loss, although it has a longer turnoff delay time.

  9. Electric field-induced superconducting transition of insulating FeSe thin film at 35 K.

    PubMed

    Hanzawa, Kota; Sato, Hikaru; Hiramatsu, Hidenori; Kamiya, Toshio; Hosono, Hideo

    2016-04-12

    It is thought that strong electron correlation in an insulating parent phase would enhance a critical temperature (Tc) of superconductivity in a doped phase via enhancement of the binding energy of a Cooper pair as known in high-Tc cuprates. To induce a superconductor transition in an insulating phase, injection of a high density of carriers is needed (e.g., by impurity doping). An electric double-layer transistor (EDLT) with an ionic liquid gate insulator enables such a field-induced transition to be investigated and is expected to result in a high Tc because it is free from deterioration in structure and carrier transport that are in general caused by conventional carrier doping (e.g., chemical substitution). Here, for insulating epitaxial thin films (∼10 nm thick) of FeSe, we report a high Tc of 35 K, which is 4× higher than that of bulk FeSe, using an EDLT under application of a gate bias of +5.5 V. Hall effect measurements under the gate bias suggest that highly accumulated electron carrier in the channel, whose area density is estimated to be 1.4 × 10(15) cm(-2) (the average volume density of 1.7 × 10(21) cm(-3)), is the origin of the high-Tc superconductivity. This result demonstrates that EDLTs are useful tools to explore the ultimate Tc for insulating parent materials.

  10. Electric field-induced superconducting transition of insulating FeSe thin film at 35 K

    PubMed Central

    Hanzawa, Kota; Sato, Hikaru; Hiramatsu, Hidenori; Kamiya, Toshio; Hosono, Hideo

    2016-01-01

    It is thought that strong electron correlation in an insulating parent phase would enhance a critical temperature (Tc) of superconductivity in a doped phase via enhancement of the binding energy of a Cooper pair as known in high-Tc cuprates. To induce a superconductor transition in an insulating phase, injection of a high density of carriers is needed (e.g., by impurity doping). An electric double-layer transistor (EDLT) with an ionic liquid gate insulator enables such a field-induced transition to be investigated and is expected to result in a high Tc because it is free from deterioration in structure and carrier transport that are in general caused by conventional carrier doping (e.g., chemical substitution). Here, for insulating epitaxial thin films (∼10 nm thick) of FeSe, we report a high Tc of 35 K, which is 4× higher than that of bulk FeSe, using an EDLT under application of a gate bias of +5.5 V. Hall effect measurements under the gate bias suggest that highly accumulated electron carrier in the channel, whose area density is estimated to be 1.4 × 1015 cm–2 (the average volume density of 1.7 × 1021 cm–3), is the origin of the high-Tc superconductivity. This result demonstrates that EDLTs are useful tools to explore the ultimate Tc for insulating parent materials. PMID:27035956

  11. Topological insulator in a helicoidal magnetization field

    NASA Astrophysics Data System (ADS)

    Stagraczyński, S.; Chotorlishvili, L.; Dugaev, V. K.; Jia, C.-L.; Ernst, A.; Komnik, A.; Berakdar, J.

    2016-11-01

    A key feature of topological insulators is the robustness of the electron energy spectrum. At a surface of a topological insulator, the Dirac point is protected by the characteristic symmetry of the system. The breaking of the symmetry opens a gap in the energy spectrum. Therefore, topological insulators are very sensitive to magnetic fields, which can open a gap in the electronic spectrum. Concerning "internal" magnetic effects, for example, the situation with doped magnetic impurities, is not trivial. A single magnetic impurity is not enough to open the band gap, while in the case of a ferromagnetic chain of deposited magnetic impurities the Dirac point is lifted. However, a much more interesting case is when localized magnetic impurities form a chiral spin order. Our first principle density functional theory calculations have shown that this is the case for Fe deposited on the surface of a Bi2Se3 topological insulator. But not only magnetic impurities can form a chiral helicoidal spin texture. An alternative way is to use chiral multiferroics (prototype material is LiCu2O2 ) that induce a proximity effect. The theoretical approach we present here is valid for both cases. We observed that opposite to a ferromagnetically ordered case, a chiral spin order does not destroy the Dirac point. We also observed that the energy gap appears at the edges of the new Brillouin zone. Another interesting result concerns the spin dynamics. We derived an equation for the spin density dynamics with a spin current and relaxation terms. We have shown that the motion of the conductance electron generates a magnetic torque and exerts a certain force on the helicoidal texture.

  12. Micromachined mold-type double-gated metal field emitters

    NASA Astrophysics Data System (ADS)

    Lee, Yongjae; Kang, Seokho; Chun, Kukjin

    1997-12-01

    Electron field emitters with double gates were fabricated using micromachining technology and the effect of the electric potential of the focusing gate (or second gate) was experimentally evaluated. The molybdenum field emission tip was made by filling a cusplike mold formed when a conformal film was deposited on the hole-trench that had been patterned on stacked metals and dielectric layers. The hole-trench was patterned by electron beam lithography and reactive ion etching. Each field emitter has a 0960-1317/7/4/009/img1 diameter extraction gate (or first gate) and a 0960-1317/7/4/009/img2 diameter focusing gate (or second gate). To make a path for the emitted electrons, silicon bulk was etched anisotropically in KOH and EDP (ethylene-diamine pyrocatechol) solution successively. The I - V characteristics and anode current change due to the focusing gate potential were measured.

  13. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P.

    Topological insulators (TI) are a novel class of quantum matter with a gapped insulating bulk yet gapless spin helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film TI devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully-tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity of 4e2 / h at the double Dirac point, a series of ambipolar two-component ''half-integer'' Dirac quantum Hall states and an electron-hole total filling factor ν=0 state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction respectively. Such a system paves the way to explore rich physics ranging from topological magnetoelectric effects to exciton condensation. DARPA MESO program.

  14. Quantum and Classical Magnetoresistance in Ambipolar Topological Insulator Transistors with Gate-tunable Bulk and Surface Conduction

    PubMed Central

    Tian, Jifa; Chang, Cuizu; Cao, Helin; He, Ke; Ma, Xucun; Xue, Qikun; Chen, Yong P.

    2014-01-01

    Weak antilocalization (WAL) and linear magnetoresistance (LMR) are two most commonly observed magnetoresistance (MR) phenomena in topological insulators (TIs) and often attributed to the Dirac topological surface states (TSS). However, ambiguities exist because these phenomena could also come from bulk states (often carrying significant conduction in many TIs) and are observable even in non-TI materials. Here, we demonstrate back-gated ambipolar TI field-effect transistors in (Bi0.04Sb0.96)2Te3 thin films grown by molecular beam epitaxy on SrTiO3(111), exhibiting a large carrier density tunability (by nearly 2 orders of magnitude) and a metal-insulator transition in the bulk (allowing switching off the bulk conduction). Tuning the Fermi level from bulk band to TSS strongly enhances both the WAL (increasing the number of quantum coherent channels from one to peak around two) and LMR (increasing its slope by up to 10 times). The SS-enhanced LMR is accompanied by a strongly nonlinear Hall effect, suggesting important roles of charge inhomogeneity (and a related classical LMR), although existing models of LMR cannot capture all aspects of our data. Our systematic gate and temperature dependent magnetotransport studies provide deeper insights into the nature of both MR phenomena and reveal differences between bulk and TSS transport in TI related materials. PMID:24810663

  15. Study of carbon nanotube field effect transistors performance based on changes in gate parameters.

    PubMed

    Shirazi, Shaahin G; Mirzakuchaki, Sattar

    2011-12-01

    Carbon nanotubes are known as an interesting material to be used in the next generations of electronic technology, especially at nano regime. Nowadays, carbon nanotube field effect transistor or CNTFET is one of the promising devices for future electronic applications. A CNTFET which uses carbon nanotube as channel or source/drain region is the most promising candidate for replacing the current silicon transistor technology. The study of modern manufacturing approach and impact of device parameters on its performance is one of the important research fields in nanoelectronics. In this paper we study some aspects of changes in gate parameters at different channel diameters. This paper shows that for small values of diameter, increasing the dielectric constant of gate insulator doesn't help to improve the performance as value of dielectric constant of gate insulator reaches a certain amount. Also, increasing the oxide thickness of gate insulator doesn't always decrease transistor performance. For high diameter values, increasing the thickness up to a certain value improves the transistor performance.

  16. The 6.5 kV clustered insulated gate bipolar transistor in homogeneous base technology

    NASA Astrophysics Data System (ADS)

    Luther-King, N.; Sweet, M.; Spulber, O.; Vershinin, K.; Ngw, C. K.; Bose, S. C.; De Souza, M. M.; Sankara Narayanan, E. M.

    2001-01-01

    The aim of this paper is to evaluate the performance of a new power semiconductor device called the clustered insulated gate bipolar transistor (CIGBT) in the homogeneous base (HB) technology for high power applications. The CIGBT belongs to a new family of MOS controlled power devices with thyristor mode of operation in the on-state and current saturation characteristics even at high gate biases. The saturation characteristics are achieved through a unique 'self-clamping' phenomenon at a predetermined anode voltage. This inherent feature enables a wide FBSOA and low loss during switching. Our detailed analysis of the CIGBT using a 2-D mixed device-circuit simulation tool indicates that 525 μm of lightly doped silicon is adequate to block 6.5 kV in the HB technology. The thin substrate improves the trade-off between conduction and switching losses even further. With an on-state voltage drop as low as 2 V at 30 A cm -2 and 3.1 V at 100 A cm -2 the device is able to turn off under inductive switching conditions at a 3 kV line voltage, with significantly low energy losses in comparison to an optimised homogeneous base insulated gate bipolar transistor (HB-IGBT). Further, the device shows good short circuit withstand capability and its positive temperature coefficient of the forward voltage drop eases parallel integration.

  17. Local Ambipolar Graphene Field Effect Transistors via Metal Side Gates

    NASA Astrophysics Data System (ADS)

    Tian, Jifa; Jauregui, Luis; Lopez, Gabriel; Cao, Helin; Chen, Yong

    2010-03-01

    We fabricated local graphene field effect transistors (FET) based on metal side gates. The characteristic ambipolar field effect of graphene device was observed by sweeping only the voltage of a local metal side gate. The local charge neutrality point of the side-gate graphene FET can be tuned in a large voltage range from positive to negative by a second side gate. Furthermore, we observed that the field effect due to the side gate can be appreciably weakened by electrically grounding the back gate compared to floating the back gate. The experimental results can be well explained by electrostatic simulation using COMSOL. Our technique offers a simple method for local tuning of charge density of graphene nanodevices while avoiding coating graphene surface with dielectrics, which may cause contamination and degradation of graphene.

  18. Quantum Dot Channel (QDC) Field Effect Transistors (FETs) and Floating Gate Nonvolatile Memory Cells

    NASA Astrophysics Data System (ADS)

    Kondo, J.; Lingalugari, M.; Chan, P.-Y.; Heller, E.; Jain, F.

    2015-09-01

    This paper presents silicon quantum dot channel (QDC) field effect transistors (FETs) and floating gate nonvolatile memory structures. The QDC-FET operation is explained by carrier transport in narrow mini-energy bands which are manifested in an array of SiO x -cladded silicon quantum dot layers. For nonvolatile memory structures, simulations of electron charge densities in the floating quantum dot layers are presented. Experimental threshold voltage shift in I D- V G characteristics is presented after the `Write' cycle. The QDC-FETs and nonvolatile memory due to improved threshold voltage variations by incorporating the lattice-matched II-VI layer as the gate insulator.

  19. Versatile sputtering technology for Al2O3 gate insulators on graphene.

    PubMed

    Friedemann, Miriam; Woszczyna, Mirosław; Müller, André; Wundrack, Stefan; Dziomba, Thorsten; Weimann, Thomas; Ahlers, Franz J

    2012-04-01

    We report a novel, sputtering-based fabrication method of Al2O3 gate insulators on graphene. Electrical performance of dual-gated mono- and bilayer exfoliated graphene devices is presented. Sputtered Al2O3 layers possess comparable quality to oxides obtained by atomic layer deposition with respect to a high relative dielectric constant of about 8, as well as low-hysteresis performance and high breakdown voltage. We observe a moderate carrier mobility of about 1000 cm(2) V(-1) s(-1) in monolayer graphene and 350 cm(2) V(-1) s(-1) in bilayer graphene, respectively. The mobility decrease can be attributed to the resonant scattering on atomic-scale defects, likely originating from the Al precursor layer evaporated prior to sputtering.

  20. Field Programmable Gate Array Hysteresis Control of Parallel Connected Inverters

    DTIC Science & Technology

    2006-06-01

    voltage with respect to time FPGA Field Programmable Gate Array GIC Generalized Impedance Converter GTO Gate-Turn-Off Transistors HDL...C. Figure 12 SEMIKRON PEBB [After Ref 13] G. FIELD PROGRAMMABLE GATE ARRAYS An FPGA is a generic semiconductor device containing a large... generate reference voltage and current waves for each of the three phases. The time to complete one logical operation inside the FPGA is a function of how

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

    NASA Astrophysics Data System (ADS)

    Chowdhury, Sauvik

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

  2. Topological Field Theory of Time-Reversal Invariant Insulators

    SciTech Connect

    Qi, Xiao-Liang; Hughes, Taylor; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-19

    We show that the fundamental time reversal invariant (TRI) insulator exists in 4 + 1 dimensions, where the effective field theory is described by the 4 + 1 dimensional Chern-Simons theory and the topological properties of the electronic structure is classified by the second Chern number. These topological properties are the natural generalizations of the time reversal breaking (TRB) quantum Hall insulator in 2 + 1 dimensions. The TRI quantum spin Hall insulator in 2 + 1 dimensions and the topological insulator in 3 + 1 dimension can be obtained as descendants from the fundamental TRI insulator in 4 + 1 dimensions through a dimensional reduction procedure. The effective topological field theory, and the Z{sub 2} topological classification for the TRI insulators in 2+1 and 3+1 dimensions are naturally obtained from this procedure. All physically measurable topological response functions of the TRI insulators are completely described by the effective topological field theory. Our effective topological field theory predicts a number of novel and measurable phenomena, the most striking of which is the topological magneto-electric effect, where an electric field generates a magnetic field in the same direction, with an universal constant of proportionality quantized in odd multiples of the fine structure constant {alpha} = e{sup 2}/hc. Finally, we present a general classification of all topological insulators in various dimensions, and describe them in terms of a unified topological Chern-Simons field theory in phase space.

  3. Characterization of a self-built field-plate gate on InGaP/InGaAs heterojunction doped-channel field-effect transistors

    NASA Astrophysics Data System (ADS)

    Chen, H. R.; Hsu, M. K.; Chiu, S. Y.; Chen, W. T.; Guo, D. F.; Lour, W. S.

    2007-03-01

    Heterojunction doped-channel field-effect transistors (HDCFETs) with a self-built field-plate gate formation were fabricated and proposed in this work. Arrangement of Schottky metal across a step undercut between the Schottky barrier and the insulator-like layer is the key process to produce a self-built field-plate gate. A controllably reduced gate length and a self-built field plate were simultaneously formed. Effects of gate-metal length, field-plate length and insulator thickness on HDCFET performance were also investigated. Simulated results reveal that higher currents, lower electric fields, better device linearity and larger output power are expected by offsetting the Schottky metal towards the drain side. A HDCFET with gate-metal length of 0.4 µm, field-plate length of 0.6 µm and insulator thickness of 120 nm was successfully fabricated for comparison to that with a 1 µm traditional planar gate. Current density (451 mA mm-1), transconductance (225 mS mm-1), breakdown voltages (VBD(DS)/VBD(GD) = 22/-25.5 V), gate-voltage swing (2.24 V), unity current-gain and power-gain frequencies (ft/fmax = 17.2/32 GHz) are improved as compared to those of a 1 µm gate device without field plates. At 1.8 GHz and VDS of 4.0 V, maximum power-added efficiency of 36% with output power of 13.9 dBm and power gain of 8.7 dB was obtained. Saturated output power and linear power gain are 316 mW mm-1 and 13 dB, respectively.

  4. Reliability analysis of charge plasma based double material gate oxide (DMGO) SiGe-on-insulator (SGOI) MOSFET

    NASA Astrophysics Data System (ADS)

    Pradhan, K. P.; Sahu, P. K.; Singh, D.; Artola, L.; Mohapatra, S. K.

    2015-09-01

    A novel device named charge plasma based doping less double material gate oxide (DMGO) silicon-germanium on insulator (SGOI) double gate (DG) MOSFET is proposed for the first time. The fundamental objective in this work is to modify the channel potential, electric field and electron velocity for improving leakage current, transconductance (gm) and transconductance generation factor (TGF). Using 2-D simulation, we exhibit that the DMGO-SGOI MOSFET shows higher electron velocity at source side and lower electric field at drain side as compare to ultra-thin body (UTB) DG MOSFET. On the other hand DMGO-SGOI MOSFET demonstrates a significant improvement in gm and TGF in comparison to UTB-DG MOSFET. This work also evaluates the existence of a biasing point i.e. zero temperature coefficient (ZTC) bias point, where the device parameters become independent of temperature. The impact of operating temperature (T) on above said various performance metrics are also subjected to extensive analysis. This further validates the reliability of charge plasma DMGO SGOI MOSFET and its application opportunities involved in designing analog/RF circuits for a wide range of temperature applications.

  5. Electric-field control of spin-orbit torque in a magnetically doped topological insulator

    NASA Astrophysics Data System (ADS)

    Fan, Yabin; Kou, Xufeng; Upadhyaya, Pramey; Shao, Qiming; Pan, Lei; Lang, Murong; Che, Xiaoyu; Tang, Jianshi; Montazeri, Mohammad; Murata, Koichi; Chang, Li-Te; Akyol, Mustafa; Yu, Guoqiang; Nie, Tianxiao; Wong, Kin L.; Liu, Jun; Wang, Yong; Tserkovnyak, Yaroslav; Wang, Kang L.

    2016-04-01

    Electric-field manipulation of magnetic order has proved of both fundamental and technological importance in spintronic devices. So far, electric-field control of ferromagnetism, magnetization and magnetic anisotropy has been explored in various magnetic materials, but the efficient electric-field control of spin-orbit torque (SOT) still remains elusive. Here, we report the effective electric-field control of a giant SOT in a Cr-doped topological insulator (TI) thin film using a top-gate field-effect transistor structure. The SOT strength can be modulated by a factor of four within the accessible gate voltage range, and it shows strong correlation with the spin-polarized surface current in the film. Furthermore, we demonstrate the magnetization switching by scanning gate voltage with constant current and in-plane magnetic field applied in the film. The effective electric-field control of SOT and the giant spin-torque efficiency in Cr-doped TI may lead to the development of energy-efficient gate-controlled spin-torque devices compatible with modern field-effect semiconductor technologies.

  6. Gate bias symmetry dependency of electron mobility and prospect of velocity modulation in double-gate silicon-on-insulator transistors

    NASA Astrophysics Data System (ADS)

    Prunnila, M.; Ahopelto, J.; Henttinen, K.; Gamiz, F.

    2004-11-01

    We report on detailed room-temperature transport properties of a 17nm thick double-gate silicon-on-insulator (DGSOI) transistor. We find that when the electron gas is transferred between the top and the bottom of the silicon-on-insulator (SOI) layer by changing the gate bias symmetry (i.e., applying the gate biases in a push-pull fashion), while keeping the carrier density constant the maximum mobility occurs when the electron gas symmetrically occupies the whole SOI slab. The observed mobility behavior is the fingerprint of volume inversion/accumulation. This gate bias symmetry dependency of the mobility suggests that DGSOI devices intrinsically can be operated in a velocity modulation transistor (VMT) mode. In the experimental gate bias window, the maximum velocity/mobility modulation is ˜40%. The VMT transconductance exceeds conventional single-gate transconductance when electron density is above ˜5.3×1016m-2. Improvements of the observed VMT operation in thin DGSOI devices are discussed.

  7. Excavationless Exterior Foundation Insulation Field Study

    SciTech Connect

    Schirber, T.; Mosiman, G.; Ojczyk, C.

    2014-09-01

    Building science research supports installing exterior (soil side) foundation insulation as the optimal method to enhance the hygrothermal performance of new homes. With exterior foundation insulation, water management strategies are maximized while insulating the basement space and ensuring a more even temperature at the foundation wall. However, such an approach can be very costly and disruptive when applied to an existing home, requiring deep excavation around the entire house. The NorthernSTAR Building America Partnership team implemented an innovative, minimally invasive foundation insulation upgrade technique on an existing home. The approach consisted of using hydrovac excavation technology combined with liquid insulating foam. The team was able to excavate a continuous 4 inches wide by 4 feet to 5 feet deep trench around the entire house, 128 linear feet, except for one small part under the stoop that was obstructed with concrete debris. The combination pressure washer and vacuum extraction technology also enabled the elimination of large trenches and soil stockpiles normally produced by backhoe excavation. The resulting trench was filled with liquid insulating foam, which also served as a water-control layer of the assembly. The insulation was brought above grade using a liquid foam/rigid foam hybrid system and terminated at the top of the rim joist. Cost savings over the traditional excavation process ranged from 23% to 50%. The excavationless process could result in even greater savings since replacement of building structures, exterior features, utility meters, and landscaping would be minimal or non-existent in an excavationless process.

  8. Excavationless Exterior Foundation Insulation Field Study

    SciTech Connect

    Schirber, T.; Mosiman, G.; Ojczyk, C.

    2014-10-01

    Building science research supports installing exterior (soil side) foundation insulation as the optimal method to enhance the hygrothermal performance of new homes. With exterior foundation insulation, water management strategies are maximized while insulating the basement space and ensuring a more even temperature at the foundation wall. However, such an approach can be very costly and disruptive when applied to an existing home, requiring deep excavation around the entire house. The NorthernSTAR Building America Partnership team implemented an innovative, minimally invasive foundation insulation upgrade technique on an existing home. The approach consisted of using hydrovac excavation technology combined with a liquid insulating foam. The team was able to excavate a continuous 4" wide by 4' to 5' deep trench around the entire house, 128 linear feet, except for one small part under the stoop that was obstructed with concrete debris. The combination pressure washer and vacuum extraction technology also enabled the elimination of large trenches and soil stockpiles normally produced by backhoe excavation. The resulting trench was filled with liquid insulating foam, which also served as a water-control layer of the assembly. The insulation was brought above grade using a liquid foam/rigid foam hybrid system and terminated at the top of the rim joist. Cost savings over the traditional excavation process ranged from 23% to 50%. The excavationless process could result in even greater savings since replacement of building structures, exterior features, utility meters, and landscaping would be minimal or non-existent in an excavationless process.

  9. Design and analysis of polarization independent all-optical logic gates in silicon-on-insulator photonic crystal

    NASA Astrophysics Data System (ADS)

    Rani, Preeti; Kalra, Yogita; Sinha, R. K.

    2016-09-01

    In this paper, we have reported design and analysis of polarization independent all optical logic gates in silicon-on-insulator photonic crystal consisting of two dimensional honeycomb lattices with two different air holes exhibiting photonic band gap for both TE and TM mode in the optical communication window. The proposed structures perform as an AND optical logic gate and all the optical logic gates based on the phenomenon of interference. The response period and bit rate for TE and TM polarizations at a wavelength of 1.55 μm show improved results as reported earlier.

  10. Positive charge trapping phenomenon in n-channel thin-film transistors with amorphous alumina gate insulators

    NASA Astrophysics Data System (ADS)

    Daus, Alwin; Vogt, Christian; Münzenrieder, Niko; Petti, Luisa; Knobelspies, Stefan; Cantarella, Giuseppe; Luisier, Mathieu; Salvatore, Giovanni A.; Tröster, Gerhard

    2016-12-01

    In this work, we investigate the charge trapping behavior in InGaZnO4 (IGZO) thin-film transistors with amorphous Al2O3 (alumina) gate insulators. For thicknesses ≤10 nm, we observe a positive charge generation at intrinsic defects inside the Al2O3, which is initiated by quantum-mechanical tunneling of electrons from the semiconductor through the Al2O3 layer. Consequently, the drain current shows a counter-clockwise hysteresis. Furthermore, the de-trapping through resonant tunneling causes a drastic subthreshold swing reduction. We report a minimum value of 19 mV/dec at room temperature, which is far below the fundamental limit of standard field-effect transistors. Additionally, we study the thickness dependence for Al2O3 layers with thicknesses of 5, 10, and 20 nm. The comparison of two different gate metals shows an enhanced tunneling current and an enhanced positive charge generation for Cu compared to Cr.

  11. Microscopic signature of insulator-to-metal transition in highly doped semicrystalline conducting polymers in ionic-liquid-gated transistors

    SciTech Connect

    Tanaka, Hisaaki Nishio, Satoshi; Ito, Hiroshi; Kuroda, Shin-ichi

    2015-12-14

    Electronic state of charge carriers, in particular, in highly doped regions, in thin-film transistors of a semicrystalline conducting polymer poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene), has been studied by using field-induced electron spin resonance (ESR) spectroscopy. By adopting an ionic-liquid gate insulator, a gate-controlled reversible electrochemical hole-doping of the polymer backbone is achieved, as confirmed from the change of the optical absorption spectra. The edge-on molecular orientation in the pristine film is maintained even after the electrochemical doping, which is clarified from the angular dependence of the g value. As the doping level increases, spin 1/2 polarons transform into spinless bipolarons, which is demonstrated from the spin-charge relation showing a spin concentration peak around 1%, contrasting to the monotonic increase in the charge concentration. At high doping levels, a drastic change in the linewidth anisotropy due to the generation of conduction electrons is observed, indicating the onset of metallic state, which is also supported by the temperature dependence of the spin susceptibility and the ESR linewidth. Our results suggest that semicrystalline conducting polymers become metallic with retaining their molecular orientational order, when appropriate doping methods are chosen.

  12. Organic ferroelectric gate field-effect transistor memory using high-mobility rubrene thin film

    NASA Astrophysics Data System (ADS)

    Kanashima, Takeshi; Katsura, Yuu; Okuyama, Masanori

    2014-01-01

    An organic ferroelectric gate field-effect transistor (FET) memory has been fabricated using an organic semiconductor of rubrene thin film with a high mobility and a gate insulating layer of poly(vinylidene fluoride-tetrafluoroethylene) [P(VDF-TeFE)] thin film. A rubrene thin-film sheet was grown by physical vapor transport (PVT), and placed onto a spin-coated P(VDF-TeFE) thin-film layer, and Au source and drain electrodes were formed on this rubrene thin film. A hysteresis loop of the drain current-gate voltage (ID-VG) characteristic has been clearly observed in the ferroelectric gate FET, and is caused by the ferroelectricity. The maximum drain current is 1.5 × 10-6 A, which is about two orders of magnitude larger than that of the P(VDF-TeFE) gate FET using a pentacene thin film. Moreover, the mobility of this organic ferroelectric gate FET using rubrene thin film is 0.71 cm2 V-1 s-1, which is 35 times larger than that of the FET with pentacene thin film.

  13. Insulated gate and surface passivation structures for GaN-based power transistors

    NASA Astrophysics Data System (ADS)

    Yatabe, Zenji; Asubar, Joel T.; Hashizume, Tamotsu

    2016-10-01

    Recent years have witnessed GaN-based devices delivering their promise of unprecedented power and frequency levels and demonstrating their capability as an able replacement for Si-based devices. High-electron-mobility transistors (HEMTs), a key representative architecture of GaN-based devices, are well-suited for high-power and high frequency device applications, owing to highly desirable III-nitride physical properties. However, these devices are still hounded by issues not previously encountered in their more established Si- and GaAs-based devices counterparts. Metal-insulator-semiconductor (MIS) structures are usually employed with varying degrees of success in sidestepping the major problematic issues such as excessive leakage current and current instability. While different insulator materials have been applied to GaN-based transistors, the properties of insulator/III-N interfaces are still not fully understood. This is mainly due to the difficulty of characterizing insulator/AlGaN interfaces in a MIS HEMT because of the two resulting interfaces: insulator/AlGaN and AlGaN/GaN, making the potential modulation rather complicated. Although there have been many reports of low interface-trap densities in HEMT MIS capacitors, several papers have incorrectly evaluated their capacitance-voltage (C-V) characteristics. A HEMT MIS structure typically shows a 2-step C-V behavior. However, several groups reported C-V curves without the characteristic step at the forward bias regime, which is likely to the high-density states at the insulator/AlGaN interface impeding the potential control of the AlGaN surface by the gate bias. In this review paper, first we describe critical issues and problems including leakage current, current collapse and threshold voltage instability in AlGaN/GaN HEMTs. Then we present interface properties, focusing on interface states, of GaN MIS systems using oxides, nitrides and high-κ dielectrics. Next, the properties of a variety of AlGaN/GaN MIS

  14. Colossal magnetoresistance in a Mott insulator via magnetic field-driven insulator-metal transition

    SciTech Connect

    Zhu, M.; Peng, J.; Zou, T.; Prokes, K.; Mahanti, S. D.; Hong, Tao; Mao, Z. Q.; Liu, G. Q.; Ke, X.

    2016-05-25

    Here, we present a new type of colossal magnetoresistance (CMR) arising from an anomalous collapse of the Mott insulating state via a modest magnetic field in a bilayer ruthenate, Ti-doped Ca3Ru2O7. Such an insulator-metal transition is accompanied by changes in both lattice and magnetic structures. Our findings have important implications because a magnetic field usually stabilizes the insulating ground state in a Mott-Hubbard system, thus calling for a deeper theoretical study to reexamine the magnetic field tuning of Mott systems with magnetic and electronic instabilities and spin-lattice-charge coupling. This study further provides a model approach to search for CMR systems other than manganites, such as Mott insulators in the vicinity of the boundary between competing phases.

  15. Colossal magnetoresistance in a Mott insulator via magnetic field-driven insulator-metal transition

    DOE PAGES

    Zhu, M.; Peng, J.; Zou, T.; ...

    2016-05-25

    Here, we present a new type of colossal magnetoresistance (CMR) arising from an anomalous collapse of the Mott insulating state via a modest magnetic field in a bilayer ruthenate, Ti-doped Ca3Ru2O7. Such an insulator-metal transition is accompanied by changes in both lattice and magnetic structures. Our findings have important implications because a magnetic field usually stabilizes the insulating ground state in a Mott-Hubbard system, thus calling for a deeper theoretical study to reexamine the magnetic field tuning of Mott systems with magnetic and electronic instabilities and spin-lattice-charge coupling. This study further provides a model approach to search for CMR systemsmore » other than manganites, such as Mott insulators in the vicinity of the boundary between competing phases.« less

  16. Metallization of Epitaxial VO2 Films by Ionic Liquid Gating through Initially Insulating TiO2 Layers.

    PubMed

    Passarello, Donata; Altendorf, Simone G; Jeong, Jaewoo; Samant, Mahesh G; Parkin, Stuart S P

    2016-09-14

    Ionic liquid gating has been shown to metallize initially insulating layers formed from several different oxide materials. Of these vanadium dioxide (VO2) is of especial interest because it itself is metallic at temperatures above its metal-insulator transition. Recent studies have shown that the mechanism of ionic liquid gated induced metallization is entirely distinct from that of the thermally driven metal-insulator transition and is derived from oxygen migration through volume channels along the (001) direction of the rutile structure of VO2. Here we show that it is possible to metallize the entire volume of 10 nm thick layers of VO2 buried under layers of rutile titanium dioxide (TiO2) up to 10 nm thick. Key to this process is the alignment of volume channels in the respective oxide layers, which have the same rutile structure with clamped in-plane lattice constants. The metallization of the VO2 layers is accompanied by large structural expansions of up to ∼6.5% in the out-of-plane direction, but the structure of the TiO2 layer is hardly affected by gating. The TiO2 layers become weakly conducting during the gating process, but in contrast to the VO2 layers, the conductivity disappears on exposure to air. Indeed, even after air exposure, X-ray photoelectron spectroscopy studies show that the VO2 films have a reduced oxygen content after metallization. Ionic liquid gating of the VO2 films through initially insulating TiO2 layers is not consistent with conventional models that have assumed the gate induced carriers are of electrostatic origin.

  17. Gate Tunable Infrared Optical Response of (Bi1-xSbx)2 Te3 Topological Insulators

    NASA Astrophysics Data System (ADS)

    Whitney, William; Brar, Victor; Ou, Yunbo; He, Ke; Xue, Qi-Kun; Atwater, Harry

    The electronic properties of topological insulators - narrow band-gap semiconductors that exhibit insulating bulk and semimetallic Dirac surface states - have been the subject of intense study over the past several years. The optical and optoelectronic behavior of these materials, however, remain widely uncharacterized. It has previously been shown that electrostatic gating can be used to tune the Fermi level in the Dirac semimetal graphene, modifying interband transitions and free carrier absorption. We report here experiments that demonstrate electronic control of the optical properties of 5-20 nm thick (Bi1-xSbx)2 Te3 films grown by Van der Waals epitaxy and transferred to silicon dioxide on silicon via an epitaxial lift off process. We find that infrared transmission and reflection from 3 to 10 microns are consistent with modulation of free-carrier absorption and bulk interband transitions in (Bi1-xSbx)2 Te3. We discuss transport results as well as the contributions that bulk and topological surface electronic transitions make to the optical response of these materials.

  18. Protected gates for topological quantum field theories

    NASA Astrophysics Data System (ADS)

    Koenig, Robert

    2015-03-01

    We give restrictions on the locality-preserving unitary automorphisms U, which are protected gates, for topologically ordered systems. For arbitrary anyon models, we show that such unitaries only generate a finite group, and hence do not provide universality. For abelian anyon models, we find that the logical action of U is contained in a proper subgroup of the generalized Clifford group. In the case D(?2), which describes Kitaev's toric code, this represents a tightening of statement previously obtained within the stabilizer framework (PRL 110:170503). For non-abelian models, we find that such automorphisms are very limited: for example, there is no non-trivial gate for Fibonacci anyons. For Ising anyons, protected gates are elements of the Pauli group. These results are derived by relating such automorphisms to symmetries of the underlying anyon model: protected gates realize automorphisms of the Verlinde algebra. We additionally use the compatibility with basis changes to characterize the logical action. This is joint work with M. Beverland, F. Pastawski, J. Preskill and S. Sijher.

  19. Plasmonic response of partially gated field effect transistors

    NASA Astrophysics Data System (ADS)

    Rudin, S.; Rupper, G.; Reed, M. L.; Shur, M.

    2016-09-01

    Electron density oscillations in the transistor channels - plasma waves in the two-dimensional electron gas - determine the high frequency device response. Plasmonic field effect transistors have emerged as very sensitive, tunable, and extremely fast detectors of THz radiation. They have been implemented using silicon (CMOS), AlGaAs/InGaAs HEMTs, and AlGaAs/InGaAs HEMTs, with the HEMTs shown to operate more efficiently at higher THz frequencies. These HEMTs have both gated and ungated sections of the device channel between the source and drain, and the photovoltaic regime of operation requires an asymmetric gate placement in the device channel. The interactions of the plasma waves in the gated and ungated channel regions strongly affect the overall response and have been investigated in numerous publications. This work addresses a new aspect of such interaction - the effect of the relative position of the gated and ungated section. We show this previously unexplored effect plays a dominant role in determining the response. The results of the numerical simulation based on the solution of the complete system of the hydrodynamic equations describing the electron fluid in the device channel show that the inverse response frequency could be approximated by the sum of the gated plasmon transit time in the gated section of the device, the ungated plasmon transit time in the ungated section of the device between the gate and the drain, and the RC gate-to-source constant. Here R and C are the resistance and capacitance of the gate to source section. Hence, the highest speed is achieved when the gate is as close to the source as possible. This suggests a novel plasmonic detector design, where the gate and source electrode overlap, which is shown to have a superior frequency response for the same distance between the source and the drain.

  20. Electron beam assisted field evaporation of insulating nanowires/tubes

    SciTech Connect

    Blanchard, N. P. Niguès, A.; Choueib, M.; Perisanu, S.; Ayari, A.; Poncharal, P.; Purcell, S. T.; Siria, A.; Vincent, P.

    2015-05-11

    We demonstrate field evaporation of insulating materials, specifically BN nanotubes and undoped Si nanowires, assisted by a convergent electron beam. Electron irradiation leads to positive charging at the nano-object's apex and to an important increase of the local electric field thus inducing field evaporation. Experiments performed both in a transmission electron microscope and in a scanning electron microscope are presented. This technique permits the selective evaporation of individual nanowires in complex materials. Electron assisted field evaporation could be an interesting alternative or complementary to laser induced field desorption used in atom probe tomography of insulating materials.

  1. High temperature study of flexible silicon-on-insulator fin field-effect transistors

    SciTech Connect

    Diab, Amer; Torres Sevilla, Galo A.; Ghoneim, Mohamed T.; Hussain, Muhammad M.

    2014-09-29

    We report high temperature electrical transport characteristics of a flexible version of the semiconductor industry's most advanced architecture: fin field-effect transistor on silicon-on-insulator with sub-20 nm fins and high-κ/metal gate stacks. Characterization from room to high temperature (150 °C) was completed to determine temperature dependence of drain current (I{sub ds}), gate leakage current (I{sub gs}), transconductance (g{sub m}), and extracted low-field mobility (μ{sub 0}). Mobility degradation with temperature is mainly caused by phonon scattering. The other device characteristics show insignificant difference at high temperature which proves the suitability of inorganic flexible electronics with advanced device architecture.

  2. Analytical drain current formulation for gate dielectric engineered dual material gate-gate all around-tunneling field effect transistor

    NASA Astrophysics Data System (ADS)

    Madan, Jaya; Gupta, R. S.; Chaujar, Rishu

    2015-09-01

    In this work, an analytical drain current model for gate dielectric engineered (hetero dielectric)-dual material gate-gate all around tunnel field effect transistor (HD-DMG-GAA-TFET) has been developed. Parabolic approximation has been used to solve the two-dimensional (2D) Poisson equation with appropriate boundary conditions and continuity equations to evaluate analytical expressions for surface potential, electric field, tunneling barrier width and drain current. Further, the analog performance of the device is studied for three high-k dielectrics (Si3N4, HfO2, and ZrO2), and it has been investigated that the problem of lower ION, can be overcome by using the hetero-gate architecture. Moreover, the impact of scaling the gate oxide thickness and bias variations has also been studied. The HD-DMG-GAA-TFET shows an enhanced ION of the order of 10-4 A. The effectiveness of the proposed model is validated by comparing it with ATLAS device simulations.

  3. Remote phonon scattering in field-effect transistors with a high κ insulating layer

    NASA Astrophysics Data System (ADS)

    Laikhtman, B.; Solomon, P. M.

    2008-01-01

    In this paper a remote phonon scattering of channel electrons in a field-effect transistor (FET) with a high dielectric constant (κ) insulator in between the gate and the channel is studied theoretically. The spectrum of phonons confined in the high κ layer and its modification by the gate screening is investigated. Only two phonon modes of five participate in the remote electron-phonon scattering. The gate suppresses one of the modes but increases scattering by the other. Numerical results for the channel mobility limited only by remote phonon scattering were obtained for a Si FET with a HfO2 layer and a SiO2 layer in between the channel and metallic gate. A surprising result is the reduction of the mobility compared to the case when the gate screening is absent. The dependence of the mobility on the widths of HfO2 and interfacial SiO2 layers on channel concentration and temperature was studied. The accuracy of the calculations based on the Boltzmann equation is discussed. Finally, a comparison of our results with available experimental data leads to the conclusion that the remote phonon scattering is not the dominating scattering mechanism.

  4. Back-gated InGaAs-on-insulator lateral N+NN+ MOSFET: Fabrication and typical conduction mechanisms

    NASA Astrophysics Data System (ADS)

    Park, H. J.; Pirro, L.; Czornomaz, L.; Ionica, I.; Bawedin, M.; Djara, V.; Deshpande, V.; Cristoloveanu, S.

    2017-02-01

    Back-gated InGaAs-on-insulator lateral N+NN+ MOSFETs are successfully fabricated by direct wafer bonding and selective epitaxial regrowth. These devices were characterized using a revisited pseudo-MOSFET configuration. Two different transport mechanisms are evidenced: volume conduction in the undepleted region of the film and surface conduction at the interface between InGaAs and buried insulator. We propose extraction techniques for the volume mobility and interface mobility. The impact of film thickness, channel width, and length is evaluated. Additional measurements reveal the variation of the transistor parameters at low temperature and under externally applied uniaxial tensile strain.

  5. Interdigitated Extended Gate Field Effect Transistor Without Reference Electrode

    NASA Astrophysics Data System (ADS)

    Ali, Ghusoon M.

    2017-02-01

    An interdigitated extended gate field effect transistor (IEGFET) has been proposed as a modified pH sensor structure of an extended gate field effect transistor (EGFET). The reference electrode and the extended gate in the conventional device have been replaced by a single interdigitated extended gate. A metal-semiconductor-metal interdigitated extended gate containing two multi-finger Ni electrodes based on zinc oxide (ZnO) thin film as a pH-sensitive membrane. ZnO thin film was grown on a p-type Si (100) substrate by the sol-gel technique. The fabricated extended gate is connected to a commercial metal-oxide-semiconductor field-effect transistor device in CD4007UB. The experimental data show that this structure has real time and linear pH voltage and current sensitivities in a concentration range between pH 4 and 11. The voltage and current sensitivities are found to be about 22.4 mV/pH and 45 μA/pH, respectively. Reference electrode elimination makes the IEGFET device simple to fabricate, easy to carry out the measurements, needing a small volume of solution to test and suitable for disposable biosensor applications. Furthermore, this uncomplicated structure could be extended to fabricate multiple ions microsensors and lab-on-chip devices.

  6. Gate control of ferromagnetic insulating phase in lightly-doped La0.875Sr0.125MnO3-δ film

    NASA Astrophysics Data System (ADS)

    Kuang, H.; Wang, J.; Hu, F. X.; Zhao, Y. Y.; Liu, Y.; Wu, R. R.; Sun, J. R.; Shen, B. G.

    2016-02-01

    The electric field effect on the lightly doped La0.875Sr0.125MnO3-δ (LSMO) thin film in electric double-layer transistors was investigated by measuring transport properties of the film under various gate voltages. It was found that the positive gate bias leads to an increase of the charge-orbital ordering (COO) transition temperature and a decrease of the Curie temperature TC, indicating the suppression of ferromagnetic metal (FMM) phases and preference of COO/ferromagnetic insulator (FMI) with the hole depletion by gate bias. Such different electric field effects can be ascribed to the weakening of the ferromagnetic interaction and enhancement of Jahn-Teller (JT) distortion caused by the transformation of JT inactive Mn4+-ions to JT active Mn3+-ions. Moreover, a step-like increase in the high temperature region of the ρ-T curve, which is related to the transition of cooperative JT distortion, was found to develop with increasing the positive bias, indicating that the cooperative JT distorted phase is stabilized by the depletion of holes in LSMO film. These results demonstrate that the modulation of holes via electric field strongly affects the balance between energy gains of different interactions and thus produce different effects on the competing FMI, FMM, and cooperative JT distorted phases in LSMO film.

  7. Electrolyte-gated charge transport in molecularly linked gold nanoparticle films: The transition from a Mott insulator to an exotic metal with strong electron-electron interactions

    NASA Astrophysics Data System (ADS)

    Tie, M.; Dhirani, A.-A.

    2016-09-01

    Strong electron-electron interactions experienced by electrons as they delocalize are widely believed to play a key role in a range of remarkable phenomena such as high Tc superconductivity, colossal magnetoresistance, and others. Strongly correlated electrons are often described by the Hubbard model, which is the simplest description of a correlated system and captures important gross features of phase diagrams of strongly correlated materials. However, open challenges in this field include experimentally mapping correlated electron phenomena beyond those captured by the Hubbard model, and extending the model accordingly. Here we use electrolyte gating to study a metal-insulator transition (MIT) in a new class of strongly correlated material, namely, nanostructured materials, using 1,4-butanedithiol-linked Au nanoparticle films (NPFs) as an example. Electrolyte gating provides a means for tuning the chemical potential of the materials over a wide range, without significantly modifying film morphology. On the insulating side of the transition, we observe Efros-Shklovskii variable range hopping and a soft Coulomb gap, evidencing the importance of Coulomb barriers. On the metallic side of the transition, we observe signatures of strong disorder mediated electron-electron correlations. Gating films near MIT also reveal a zero-bias conductance peak, which we attribute to a resonance at the Fermi level predicted by the Hubbard and Anderson impurity models when electrons delocalize and experience strong Coulomb electron-electron interactions. This study shows that by enabling large changes in carrier density, electrolyte gating of Au NPFs is a powerful means for tuning through the Hubbard MIT in NPFs. By revealing the range of behaviours that strongly correlated electrons can exhibit, this platform can guide the development of an improved understanding of correlated materials.

  8. Gallium Arsenide Field Effect Transistors with Semi-Insulated Gates.

    DTIC Science & Technology

    1977-09-01

    amplifier . As a preliminary test of the theoretical anal ysis , a numbe r of conventiona l GaAs MESFETs were tested as X—band amplifiers to determine ... circuit design was actuall y based on S—parameters measured from a one—cell MESFET fabricated from the same epi taxial wafer (l6375-3011A) . This... equivalent to those of the ion implant produced SIGFETs. 2. Pulsed Operation SIGFETs and MESFETS from the same slice were operated under pulsed

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  10. Golden Gate Park, Chalet Recreation Field, Bounded by John F. ...

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

    Golden Gate Park, Chalet Recreation Field, Bounded by John F. Kennedy Drive to the north and east, former Richmond-Sunset Sewage Treatment Plant to the south, and the Old Railroad Trail to the west, San Francisco, San Francisco County, CA

  11. High-transconductance graphene solution-gated field effect transistors

    NASA Astrophysics Data System (ADS)

    Hess, L. H.; Hauf, M. V.; Seifert, M.; Speck, F.; Seyller, T.; Stutzmann, M.; Sharp, I. D.; Garrido, J. A.

    2011-07-01

    In this work, we report on the electronic properties of solution-gated field effect transistors (SGFETs) fabricated using large-area graphene. Devices prepared both with epitaxially grown graphene on SiC as well as with chemical vapor deposition grown graphene on Cu exhibit high transconductances, which are a consequence of the high mobility of charge carriers in graphene and the large capacitance at the graphene/water interface. The performance of graphene SGFETs, in terms of gate sensitivity, is compared to other SGFET technologies and found to be clearly superior, confirming the potential of graphene SGFETs for sensing applications in electrolytic environments.

  12. Diamond logic inverter with enhancement-mode metal-insulator-semiconductor field effect transistor

    SciTech Connect

    Liu, J. W.; Liao, M. Y.; Imura, M.; Watanabe, E.; Oosato, H.; Koide, Y.

    2014-08-25

    A diamond logic inverter is demonstrated using an enhancement-mode hydrogenated-diamond metal-insulator-semiconductor field effect transistor (MISFET) coupled with a load resistor. The gate insulator has a bilayer structure of a sputtering-deposited LaAlO{sub 3} layer and a thin atomic-layer-deposited Al{sub 2}O{sub 3} buffer layer. The source-drain current maximum, extrinsic transconductance, and threshold voltage of the MISFET are measured to be −40.7 mA·mm{sup −1}, 13.2 ± 0.1 mS·mm{sup −1}, and −3.1 ± 0.1 V, respectively. The logic inverters show distinct inversion (NOT-gate) characteristics for input voltages ranging from 4.0 to −10.0 V. With increasing the load resistance, the gain of the logic inverter increases from 5.6 to as large as 19.4. The pulse response against the high and low input voltages shows the inversion response with the low and high output voltages.

  13. Effects of Sulfide Passivation on the Performance of GaAs MISFETs with Photo-CVD Grown P3N5 Gate Insulators

    NASA Astrophysics Data System (ADS)

    Jeong, Yoon-Ha; Choi, Ki-Hwan; Jo, Seong-Kue; Kang, Bongkoo

    1995-02-01

    Accumulation-mode and depletion-mode GaAs metal-insulator-semiconductor field-effect transistors (MISEETs), with sulfur-treatment and a photochemical vapor-deposited- P3N5 gate insulator, have been successfully fabricated. The devices have good linearity, low hysteresis in current-voltage characteristics, and the instability of the current less than 22 percent for the period of 1.0-1.0×104 s. The effective electron mobility and extrinsic transconductance of the FETs at room temperature are about 1300 cm2/V·s and 1.41 mS/mm for the accumulation-mode, and about 4500 cm2/V·s and 4 mS/mm for the depletion-mode, respectively. Capacitance-voltage (C-V) characteristics and Auger electron spectroscopy (AES) analysis for different sulfur-treatment conditions are discussed. The atomic concentration ratios of sulfur and oxygen to arsenide on GaAs surfaces and GaAs metal-insulator-semiconductor (MIS) interface properties are critically dependent on sulfur pretreatment conditions, and the optimum sulfur-treatment temperature is determined to be about 40° C. The minimum density of interface trap states for an Al/P3N5/GaAs MIS diode with the optimized surface treatment is about 4.3×1010 cm-2 eV-1.

  14. High-performance GaN metal-insulator-semiconductor ultraviolet photodetectors using gallium oxide as gate layer.

    PubMed

    Lee, Ming-Lun; Mue, T S; Huang, F W; Yang, J H; Sheu, J K

    2011-06-20

    In this study, gallium nitride (GaN)-based metal-insulator-semiconductor (MIS) ultraviolet (UV) photodetectors (PDs) with a gallium oxide (GaO(x)) gate layer formed by alternating current bias-assisted photoelectrochemical oxidation of n-GaN are presented. By introducing the GaO(x) gate layer to the GaN MIS UV PDs, the leakage current is reduced and a much larger UV-to-visible rejection ratio (R(UV/vis)) of spectral responsivity is achieved. In addition, a bias-dependent spectral response results in marked increase of the R(UV/vis) with bias voltage up to ~10(5). The bias-dependent responsivity suggests the possible existence of internal gain in of the GaN MIS PDs.

  15. Metrology solutions for high performance germanium multi-gate field-effect transistors using optical scatterometry

    NASA Astrophysics Data System (ADS)

    Chin, Hock-Chun; Ling, Moh-Lung; Liu, Bin; Zhang, Xingui; Li, Jie; Liu, Yongdong; Hu, Jiangtao; Yeo, Yee-Chia

    2013-04-01

    In this work, we report the first demonstration of scatterometry Optical Critical Dimension (OCD) characterization on advanced Ge Multi-Gate Field-Effect Transistor (MuGFET) or FinFET formed on a Germanium-on-Insulator (GeOI) substrate. Two critical process steps in the Ge MuGFET process flow were investigated, i.e. after Ge Fin formation, and after TaN gate stack etching process. All key process variations in the test structures were successfully monitored by the floating or fitting parameters in the OCD models. In addition, excellent static repeatability, with 3σ lower than 0.12 nm, was also achieved. The measurement results from OCD were also compared with both Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) measurements. Excellent correlation with both SEM and TEM was achieved by employing OCD characterization, confirming scatterometry OCD as a promising metrology technique for next generation multi-gate transistor with an advanced channel material.

  16. AlN/GaN Metal Insulator Semiconductor Field Effect Transistor on Sapphire Substrate

    NASA Astrophysics Data System (ADS)

    Seo, Sanghyun; Ghose, Kaustav; Zhao, Guang Yuan; Pavlidis, Dimitris

    AlN/GaN Metal Insulator Semiconductor Field Effect Transistors (MISFETs) were designed, simulated and fabricated. DC, S-parameter and power measurements were also performed. Drift-diffusion simulations using DESSIS compared AlN/GaN MISFETs and Al32Ga68N/GaN Heterostructure FETs (HFETs) with the same geometries. The simulation results show the advantages of AlN/GaN MISFETs in terms of higher saturation current, lower gate leakage and higher transconductance than AlGaN/GaN HFETs. First results from fabricated AlN/GaN devices with 1μm gate length and 200μm gate width showed a maximum drain current density of ˜380mA/mm and a peak extrinsic transconductance of 85mS/mm. S-parameter measurements showed that currentgain cutoff frequency (fT) and maximum oscillation frequency (fmax) were 5.85GHz and 10.57GHz, respectively. Power characteristics were measured at 2GHz and showed output power density of 850mW/mm with 23.8% PAE at VDS=15V. To the authors knowledge this is the first report of a systematic study of AlN/GaN MISFETs addressing their physical modeling and experimental high-frequency characteristics including the power performance.

  17. Design and theoretical investigation of a silicon-on-insulator based electro-optical logic gate device

    NASA Astrophysics Data System (ADS)

    Li, Lei; Qi, Zhipeng; Hu, Guohua; Yun, Binfeng; Zhong, Yuan; Cui, Yiping

    2016-10-01

    A compact electro-optical "NOR" logic gate device based on silicon-on-insulator (SOI) platform is proposed and investigated theoretically. By introducing a hook-type waveguide, the signal could be coupled between the bus and hook-type waveguide to form an optical circuit and realize NOR logic gate. We can easily realize the NOR logical function by the voltage applied on the coupling components. The numerical simulation shows that a high coupling efficiency of more than 99% is obtained at the wavelength of 1550 nm, and the footprint of our device is smaller than 90 μm2. In addition, the response time of the proposed NOR logic gate is 3 ns with a switching voltage of 1.8 V. Moreover, it is demonstrated that such NOR logic gate device could obtain an extinction ratio of 21.8 dB. Thus, it has great potential to achieve high speed response, low power consumption, and small footprint, which fulfill the demands of next-generation on-chip computer multiplex processors.

  18. Topological BF field theory description of topological insulators

    SciTech Connect

    Cho, Gil Young; Moore, Joel E.

    2011-06-15

    Research Highlights: > We show that a BF theory is the effective theory of 2D and 3D topological insulators. > The non-gauge-invariance of the bulk theory yields surface terms for a bosonized Dirac fermion. > The 'axion' term in electromagnetism is correctly obtained from gapped surfaces. > Generalizations to possible fractional phases are discussed in closing. - Abstract: Topological phases of matter are described universally by topological field theories in the same way that symmetry-breaking phases of matter are described by Landau-Ginzburg field theories. We propose that topological insulators in two and three dimensions are described by a version of abelian BF theory. For the two-dimensional topological insulator or quantum spin Hall state, this description is essentially equivalent to a pair of Chern-Simons theories, consistent with the realization of this phase as paired integer quantum Hall effect states. The BF description can be motivated from the local excitations produced when a {pi} flux is threaded through this state. For the three-dimensional topological insulator, the BF description is less obvious but quite versatile: it contains a gapless surface Dirac fermion when time-reversal-symmetry is preserved and yields 'axion electrodynamics', i.e., an electromagnetic E . B term, when time-reversal symmetry is broken and the surfaces are gapped. Just as changing the coefficients and charges of 2D Chern-Simons theory allows one to obtain fractional quantum Hall states starting from integer states, BF theory could also describe (at a macroscopic level) fractional 3D topological insulators with fractional statistics of point-like and line-like objects.

  19. Field Programmable Gate Array-Based Attitude Stabilization

    DTIC Science & Technology

    2008-07-01

    Conversion ω θ RPM ω Inertial Interface Attitude Update Floating Point Figure 5. FPGA Block Diagram Inertial Interface A generic signal interface for the...With the FPGA operating at 50 MHz, the PWM interface is able to provide a command signal resolution of 1/50,000. The ability of the speed controller to...Center, Ohio University, Athens, OH 45701 A system for determining vehicle attitude using a field programmable gate array ( FPGA ) and low cost gyroscopes

  20. Insulation.

    ERIC Educational Resources Information Center

    Rhea, Dennis

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with insulation. Its objective is for the student to be able to determine insulation needs of new or existing structures, select type to use, use installation techniques, calculate costs, and apply safety factors. Some topics covered…

  1. Facile fabrication of electrolyte-gated single-crystalline cuprous oxide nanowire field-effect transistors

    NASA Astrophysics Data System (ADS)

    Stoesser, Anna; von Seggern, Falk; Purohit, Suneeti; Nasr, Babak; Kruk, Robert; Dehm, Simone; Wang, Di; Hahn, Horst; Dasgupta, Subho

    2016-10-01

    Oxide semiconductors are considered to be one of the forefront candidates for the new generation, high-performance electronics. However, one of the major limitations for oxide electronics is the scarcity of an equally good hole-conducting semiconductor, which can provide identical performance for the p-type metal oxide semiconductor field-effect transistors as compared to their electron conducting counterparts. In this quest, here we present a bulk synthesis method for single crystalline cuprous oxide (Cu2O) nanowires, their chemical and morphological characterization and suitability as active channel material in electrolyte-gated, low-power, field-effect transistors (FETs) for portable and flexible logic circuits. The bulk synthesis method used in the present study includes two steps: namely hydrothermal synthesis of the nanowires and the removal of the surface organic contaminants. The surface treated nanowires are then dispersed on a receiver substrate where the passive electrodes are structured, followed by printing of a composite solid polymer electrolyte (CSPE), chosen as the gate insulator. The characteristic electrical properties of individual nanowire FETs are found to be quite interesting including accumulation-mode operation and field-effect mobility of 0.15 cm2 V-1 s-1.

  2. Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating.

    PubMed

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; He, Xi; Bollinger, Anthony T; Pavuna, Davor; Pindak, Ron; Božović, Ivan

    2016-08-31

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms.

  3. Oxygen Displacement in Cuprates under IonicLiquid Field-Effect Gating

    SciTech Connect

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; He, Xi; Bollinger, Anthony T.; Pavuna, Davor; Pindak, Ron; Bozovic, Ivan

    2016-08-15

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and planar oxygen atoms were displaced towards the sample surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of planar oxygen atoms.

  4. Oxygen Displacement in Cuprates under IonicLiquid Field-Effect Gating

    DOE PAGES

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; ...

    2016-08-15

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were nomore » structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and planar oxygen atoms were displaced towards the sample surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of planar oxygen atoms.« less

  5. Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating

    NASA Astrophysics Data System (ADS)

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; He, Xi; Bollinger, Anthony T.; Pavuna, Davor; Pindak, Ron; Božović, Ivan

    2016-08-01

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms.

  6. Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating

    PubMed Central

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; He, Xi; Bollinger, Anthony T.; Pavuna, Davor; Pindak, Ron; Božović, Ivan

    2016-01-01

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms. PMID:27578237

  7. Structural advantages of silicon-on-insulator FETs over FinFETs in steep subthreshold-swing operation in ferroelectric-gate FETs

    NASA Astrophysics Data System (ADS)

    Ota, Hiroyuki; Migita, Shinji; Hattori, Junichi; Fukuda, Koichi; Toriumi, Akira

    2017-04-01

    In this paper, we discuss the subthreshold operation of fully depleted silicon-on-insulator FETs (SOI-FETs) and FinFETs, with embedded ferroelectric negative-capacitance gate insulators, using technology computer-aided design simulations. SOI-FETs with ultrathin buried-oxide layers and appropriate workfunctions for bottom electrodes are found to be more preferable to attain steep subthreshold swings lesser than 60 mV/decade, because SOI-FETs can effectively enable a voltage drop in the ferroelectric layer, even though the degree of matching of the depletion capacitance and the ferroelectric gate insulator capacitance is almost the same in SOI-FETs and FinFETs. These results give a novel insight into how the subthreshold swing can be improved in ferroelectric-gate MOSFETs.

  8. Imperfect two-dimensional topological insulator field-effect transistors

    NASA Astrophysics Data System (ADS)

    Vandenberghe, William G.; Fischetti, Massimo V.

    2017-01-01

    To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose two-dimensional topological insulator field-effect transistors that switch based on the modulation of scattering. We model transistors made of two-dimensional topological insulator ribbons accounting for scattering with phonons and imperfections. In the on-state, the Fermi level lies in the bulk bandgap and the electrons travel ballistically through the topologically protected edge states even in the presence of imperfections. In the off-state the Fermi level moves into the bandgap and electrons suffer from severe back-scattering. An off-current more than two-orders below the on-current is demonstrated and a high on-current is maintained even in the presence of imperfections. At low drain-source bias, the output characteristics are like those of conventional field-effect transistors, at large drain-source bias negative differential resistance is revealed. Complementary n- and p-type devices can be made enabling high-performance and low-power electronic circuits using imperfect two-dimensional topological insulators.

  9. Imperfect two-dimensional topological insulator field-effect transistors.

    PubMed

    Vandenberghe, William G; Fischetti, Massimo V

    2017-01-20

    To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose two-dimensional topological insulator field-effect transistors that switch based on the modulation of scattering. We model transistors made of two-dimensional topological insulator ribbons accounting for scattering with phonons and imperfections. In the on-state, the Fermi level lies in the bulk bandgap and the electrons travel ballistically through the topologically protected edge states even in the presence of imperfections. In the off-state the Fermi level moves into the bandgap and electrons suffer from severe back-scattering. An off-current more than two-orders below the on-current is demonstrated and a high on-current is maintained even in the presence of imperfections. At low drain-source bias, the output characteristics are like those of conventional field-effect transistors, at large drain-source bias negative differential resistance is revealed. Complementary n- and p-type devices can be made enabling high-performance and low-power electronic circuits using imperfect two-dimensional topological insulators.

  10. Imperfect two-dimensional topological insulator field-effect transistors

    PubMed Central

    Vandenberghe, William G.; Fischetti, Massimo V.

    2017-01-01

    To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose two-dimensional topological insulator field-effect transistors that switch based on the modulation of scattering. We model transistors made of two-dimensional topological insulator ribbons accounting for scattering with phonons and imperfections. In the on-state, the Fermi level lies in the bulk bandgap and the electrons travel ballistically through the topologically protected edge states even in the presence of imperfections. In the off-state the Fermi level moves into the bandgap and electrons suffer from severe back-scattering. An off-current more than two-orders below the on-current is demonstrated and a high on-current is maintained even in the presence of imperfections. At low drain-source bias, the output characteristics are like those of conventional field-effect transistors, at large drain-source bias negative differential resistance is revealed. Complementary n- and p-type devices can be made enabling high-performance and low-power electronic circuits using imperfect two-dimensional topological insulators. PMID:28106059

  11. Poly(4-vinylphenol) gate insulator with cross-linking using a rapid low-power microwave induction heating scheme for organic thin-film-transistors

    NASA Astrophysics Data System (ADS)

    Fan, Ching-Lin; Shang, Ming-Chi; Hsia, Mao-Yuan; Wang, Shea-Jue; Huang, Bohr-Ran; Lee, Win-Der

    2016-03-01

    A Microwave-Induction Heating (MIH) scheme is proposed for the poly(4-vinylphenol) (PVP) gate insulator cross-linking process to replace the traditional oven heating cross-linking process. The cross-linking time is significantly decreased from 1 h to 5 min by heating the metal below the PVP layer using microwave irradiation. The necessary microwave power was substantially reduced to about 50 W by decreasing the chamber pressure. The MIH scheme is a good candidate to replace traditional thermal heating for cross-linking of PVP as the gate insulator for organic thin-film-transistors.

  12. Investigation of negative bias temperature instability dependence on fin width of silicon-on-insulator-fin-based field effect transistors

    SciTech Connect

    Young, Chadwin D. Wang, Zhe; Neugroschel, Arnost; Majumdar, Kausik; Matthews, Ken; Hobbs, Chris

    2015-01-21

    The fin width dependence of negative bias temperature instability (NBTI) of double-gate, fin-based p-type Field Effect Transistors (FinFETs) fabricated on silicon-on-insulator (SOI) wafers was investigated. The NBTI degradation increased as the fin width narrowed. To investigate this phenomenon, simulations of pre-stress conditions were employed to determine any differences in gate oxide field, fin band bending, and electric field profile as a function of the fin width. The simulation results were similar at a given gate stress bias, regardless of the fin width, although the threshold voltage was found to increase with decreasing fin width. Thus, the NBTI fin width dependence could not be explained from the pre-stress conditions. Different physics-based degradation models were evaluated using specific fin-based device structures with different biasing schemes to ascertain an appropriate model that best explains the measured NBTI dependence. A plausible cause is an accumulation of electrons that tunnel from the gate during stress into the floating SOI fin body. As the fin narrows, the sidewall device channel moves in closer proximity to the stored electrons, thereby inducing more band bending at the fin/dielectric interface, resulting in a higher electric field and hole concentration in this region during stress, which leads to more degradation. The data obtained in this work provide direct experimental proof of the effect of electron accumulation on the threshold voltage stability in FinFETs.

  13. Improvement in performance of solution-processed indium-zinc-tin oxide thin-film transistors by UV/O3 treatment on zirconium oxide gate insulator

    NASA Astrophysics Data System (ADS)

    Naik, Bukke Ravindra; Avis, Christophe; Delwar Hossain Chowdhury, Md; Kim, Taehun; Lin, Tengda; Jang, Jin

    2016-03-01

    We studied solution-processed amorphous indium-zinc-tin oxide (a-IZTO) thin-film transistors (TFTs) with spin-coated zirconium oxide (ZrOx) as the gate insulator. The ZrOx gate insulator was used without and with UV/O3 treatment. The TFTs with an untreated ZrOx gate dielectric showed a saturation mobility (μsat) of 0.91 ± 0.29 cm2 V-1 s-1, a threshold voltage (Vth) of 0.28 ± 0.36 V, a subthreshold swing (SS) of 199 ± 37.17 mV/dec, and a current ratio (ION/IOFF) of ˜107. The TFTs with a UV/O3-treated ZrOx gate insulator exhibited μsat of 2.65 ± 0.43 cm2 V-1 s-1, Vth of 0.44 ± 0.35 V, SS of 133 ± 24.81 mV/dec, and ION/IOFF of ˜108. Hysteresis was 0.32 V in the untreated TFTs and was eliminated by UV/O3 treatment. Also, the leakage current decreased significantly when the IZTO TFT was coated onto a UV/O3-treated ZrOx gate insulator.

  14. A High Temperature Silicon Carbide mosfet Power Module With Integrated Silicon-On-Insulator-Based Gate Drive

    SciTech Connect

    Wang, Zhiqiang; Shi, Xiaojie; Tolbert, Leon M.; Wang, Fei Fred; Liang, Zhenxian; Costinett, Daniel; Blalock, Benjamin J.

    2014-04-30

    Here we present a board-level integrated silicon carbide (SiC) MOSFET power module for high temperature and high power density application. Specifically, a silicon-on-insulator (SOI)-based gate driver capable of operating at 200°C ambient temperature is designed and fabricated. The sourcing and sinking current capability of the gate driver are tested under various ambient temperatures. Also, a 1200 V/100 A SiC MOSFET phase-leg power module is developed utilizing high temperature packaging technologies. The static characteristics, switching performance, and short-circuit behavior of the fabricated power module are fully evaluated at different temperatures. Moreover, a buck converter prototype composed of the SOI gate driver and SiC power module is built for high temperature continuous operation. The converter is operated at different switching frequencies up to 100 kHz, with its junction temperature monitored by a thermosensitive electrical parameter and compared with thermal simulation results. The experimental results from the continuous operation demonstrate the high temperature capability of the power module at a junction temperature greater than 225°C.

  15. A High Temperature Silicon Carbide mosfet Power Module With Integrated Silicon-On-Insulator-Based Gate Drive

    DOE PAGES

    Wang, Zhiqiang; Shi, Xiaojie; Tolbert, Leon M.; ...

    2014-04-30

    Here we present a board-level integrated silicon carbide (SiC) MOSFET power module for high temperature and high power density application. Specifically, a silicon-on-insulator (SOI)-based gate driver capable of operating at 200°C ambient temperature is designed and fabricated. The sourcing and sinking current capability of the gate driver are tested under various ambient temperatures. Also, a 1200 V/100 A SiC MOSFET phase-leg power module is developed utilizing high temperature packaging technologies. The static characteristics, switching performance, and short-circuit behavior of the fabricated power module are fully evaluated at different temperatures. Moreover, a buck converter prototype composed of the SOI gate drivermore » and SiC power module is built for high temperature continuous operation. The converter is operated at different switching frequencies up to 100 kHz, with its junction temperature monitored by a thermosensitive electrical parameter and compared with thermal simulation results. The experimental results from the continuous operation demonstrate the high temperature capability of the power module at a junction temperature greater than 225°C.« less

  16. Inversion gate capacitance of undoped single-gate and double-gate field-effect transistor geometries in the extreme quantum limit

    SciTech Connect

    Majumdar, Amlan

    2015-05-28

    We present first-principle analytical derivations and numerically modeled data to show that the gate capacitance per unit gate area C{sub G} of extremely thin undoped-channel single-gate and double-gate field-effect transistor geometries in the extreme quantum limit with single-subband occupancy can be written as 1/C{sub G} = 1/C{sub OX} + N{sub G}/C{sub DOS} + N{sub G}/ηC{sub WF}, where N{sub G} is the number of gates, C{sub OX} is the oxide capacitance per unit area, C{sub DOS} is the density-of-states capacitance per unit area, C{sub WF} is the wave function spreading capacitance per unit area, and η is a constant on the order of 1.

  17. Low-voltage operation of Si-based ferroelectric field effect transistors using organic ferroelectrics, poly(vinylidene fluoride-trifluoroethylene), as a gate dielectric

    NASA Astrophysics Data System (ADS)

    Miyata, Yusuke; Yoshimura, Takeshi; Ashida, Atsushi; Fujimura, Norifumi

    2016-04-01

    Si-based metal-ferroelectric-semiconductor (MFS) capacitors have been fabricated using poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] as a ferroelectric gate. The pinhole-free P(VDF-TrFE) thin films with high resistivity were able to be prepared by spin-coating directly onto hydrogen-terminated Si. The capacitance-voltage (C-V) characteristics of the ferroelectric gate field effect transistor (FeFET) using this MFS structure clearly show butterfly-shaped hysteresis originating from the ferroelectricity, indicating carrier modulation on the Si surface at gate voltages below 2 V. The drain current-gate voltage (I D-V G) characteristics also show counterclockwise hysteresis at gate voltages below 5 V. This is the first report on the low-voltage operation of a Si-based FeFET using P(VDF-TrFE) as a gate dielectric. This organic gate FeFET without any insulator layer at the ferroelectric/Si interface should be one of the promising devices for overcoming the critical issues of the FeFET, such as depolarization field and a decrease in the gate voltage.

  18. Amorphous Indium Gallium Zinc Oxide Semiconductor Thin Film Transistors Using O2 Plasma Treatment on the SiNx Gate Insulator

    NASA Astrophysics Data System (ADS)

    Kim, Woong-Sun; Moon, Yeon-Keon; Lee, Sih; Kang, Byung-Woo; Kim, Kyung-Taek; Lee, Je-Hun; Kim, Joo-Han; Ahn, Byung-Du; Park, Jong-Wan

    2010-08-01

    In this study, we investigated the role of processing parameters on the electrical characteristics of amorphous In-Ga-Zn-O (a-IGZO) thin film transistors (TFTs) fabricated using DC magnetron sputtering at room temperature. Processing parameters including the oxygen partial pressure, annealing temperature, and channel thickness have a great influence on TFT performance and better devices are obtained at a low oxygen partial pressure, annealing at 200 °C, and a low channel thickness. We attempted to improve the a-IGZO TFT performance and stability under a gate bias stress using O2 plasma treatment. With an O2 plasma treated gate insulator, remarkable properties including excellent bias stability as well as a field effect mobility (µFE) of 11.5 cm2 V-1 s-1, a subthreshold swing (S) of 0.59 V/decade, a turn-on voltage (VON) of -1.3 V, and an on/off current ratio (ION/IOFF) of 105 were achieved.

  19. Self-aligned-gate AlGaN/GaN heterostructure field-effect transistor with titanium nitride gate

    NASA Astrophysics Data System (ADS)

    Zhang, Jia-Qi; Wang, Lei; Li, Liu-An; Wang, Qing-Peng; Jiang, Ying; Zhu, Hui-Chao; Ao, Jin-Ping

    2016-08-01

    Self-aligned-gate heterostructure field-effect transistor (HFET) is fabricated using a wet-etching method. Titanium nitride (TiN) is one kind of thermal stable material which can be used as the gate electrode. A Ti/Au cap layer is fixed on the gate and acts as an etching mask. Then the T-shaped gate is automatically formed through over-etching the TiN layer in 30% H2O2 solution at 95 °C. After treating the ohmic region with an inductively coupled plasma (ICP) method, an Al layer is sputtered as an ohmic electrode. The ohmic contact resistance is approximately 0.3 Ω·mm after annealing at a low-temperature of 575 °C in N2 ambient for 1 min. The TiN gate leakage current is only 10-8 A after the low-temperature ohmic process. The access region length of the self-aligned-gate (SAG) HFET was reduced from 2 μm to 0.3 μm compared with that of the gate-first HFET. The output current density and transconductance of the device which has the same gate length and width are also increased.

  20. Electrophoretic-like gating used to control metal-insulator transitions in electronically phase separated manganite wires.

    PubMed

    Guo, Hangwen; Noh, Joo H; Dong, Shuai; Rack, Philip D; Gai, Zheng; Xu, Xiaoshan; Dagotto, Elbio; Shen, Jian; Ward, T Zac

    2013-08-14

    Electronically phase separated manganite wires are found to exhibit controllable metal-insulator transitions under local electric fields. The switching characteristics are shown to be fully reversible, polarity independent, and highly resistant to thermal breakdown caused by repeated cycling. It is further demonstrated that multiple discrete resistive states can be accessed in a single wire. The results conform to a phenomenological model in which the inherent nanoscale insulating and metallic domains are rearranged through electrophoretic-like processes to open and close percolation channels.

  1. Enhanced Miller plateau characteristics of a 4H-SiC insulated-gate bipolar transistor in the presence of interface traps

    NASA Astrophysics Data System (ADS)

    Navarro, Dondee; Tone, Akihiro; Kikuchihara, Hideyuki; Morikawa, Yoji; Miura-Mattausch, Mitiko

    2017-04-01

    Miller plateau characteristics of a 4H-SiC insulated-gate bipolar transistor (IGBT) is investigated during a gate voltage turn-on under the presence of interface carrier traps at the MOSFET gate oxide. The plateau, which is observed in the device gate-emitter voltage, increased with respect to both height and length. The plateau height is mainly determined by the density increase of trap states, which also causes slow charging of the gate capacitance in the overlap region that results in a longer plateau length. The shallow trap states contribute mainly to the plateau increase. It is observed that the switching loss at turn-on can increase by more than 60% due mainly to the carrier traps at the shallow trap states.

  2. Driving a Superconductor to Insulator Transition with Random Gauge Fields

    PubMed Central

    Nguyen, H. Q.; Hollen, S. M.; Shainline, J.; Xu, J. M.; Valles, J. M.

    2016-01-01

    Typically the disorder that alters the interference of particle waves to produce Anderson localization is potential scattering from randomly placed impurities. Here we show that disorder in the form of random gauge fields that act directly on particle phases can also drive localization. We present evidence of a superfluid bose glass to insulator transition at a critical level of this gauge field disorder in a nano-patterned array of amorphous Bi islands. This transition shows signs of metallic transport near the critical point characterized by a resistance , indicative of a quantum phase transition. The critical disorder depends on interisland coupling in agreement with recent Quantum Monte Carlo simulations. We discuss how this disorder tuned SIT differs from the common frustration tuned SIT that also occurs in magnetic fields. Its discovery enables new high fidelity comparisons between theoretical and experimental studies of disorder effects on quantum critical systems. PMID:27901081

  3. Driving a Superconductor to Insulator Transition with Random Gauge Fields

    NASA Astrophysics Data System (ADS)

    Nguyen, H. Q.; Hollen, S. M.; Shainline, J.; Xu, J. M.; Valles, J. M.

    2016-11-01

    Typically the disorder that alters the interference of particle waves to produce Anderson localization is potential scattering from randomly placed impurities. Here we show that disorder in the form of random gauge fields that act directly on particle phases can also drive localization. We present evidence of a superfluid bose glass to insulator transition at a critical level of this gauge field disorder in a nano-patterned array of amorphous Bi islands. This transition shows signs of metallic transport near the critical point characterized by a resistance , indicative of a quantum phase transition. The critical disorder depends on interisland coupling in agreement with recent Quantum Monte Carlo simulations. We discuss how this disorder tuned SIT differs from the common frustration tuned SIT that also occurs in magnetic fields. Its discovery enables new high fidelity comparisons between theoretical and experimental studies of disorder effects on quantum critical systems.

  4. Driving a Superconductor to Insulator Transition with Random Gauge Fields.

    PubMed

    Nguyen, H Q; Hollen, S M; Shainline, J; Xu, J M; Valles, J M

    2016-11-30

    Typically the disorder that alters the interference of particle waves to produce Anderson localization is potential scattering from randomly placed impurities. Here we show that disorder in the form of random gauge fields that act directly on particle phases can also drive localization. We present evidence of a superfluid bose glass to insulator transition at a critical level of this gauge field disorder in a nano-patterned array of amorphous Bi islands. This transition shows signs of metallic transport near the critical point characterized by a resistance , indicative of a quantum phase transition. The critical disorder depends on interisland coupling in agreement with recent Quantum Monte Carlo simulations. We discuss how this disorder tuned SIT differs from the common frustration tuned SIT that also occurs in magnetic fields. Its discovery enables new high fidelity comparisons between theoretical and experimental studies of disorder effects on quantum critical systems.

  5. Inhomogeneous field induced magnetoelectric effect in Mott insulators

    SciTech Connect

    Boulaevskii, Lev N; Batista, Cristian D

    2008-01-01

    We consider a Mott insulator like HoMnO{sub 3} whose magnetic lattice is geometrically frustrated and comprises a 3D array of triangular layers with magnetic moments ordered in a 120{sup o} structure. We show that the effect of a uniform magnetic field gradient, {gradient}H, is to redistribute the electronic charge of the magnetically ordered phase leading to a unfirom electric field gradient. The resulting voltage difference between the crystal edges is proportional to the square of the crystal thickness, or inter-edge distance, L. It can reach values of several volts for |{gradient}H| {approx} 0.01 T/cm and L {approx_equal} 1mm, as long as the crystal is free of antiferromagnetic domain walls.

  6. Experimental Observation of a Metal-insulator Transition in 2D at Zero Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kravchenko, S. V.

    1996-03-01

    The scaling theory of Abrahams et al. ^1 has had considerable success in describing many features of metal-insulator transitions. Within this theory, which was developed for non-interacting electrons, no such transition is possible in two-dimensional electron systems (2DES) in the absence of a magnetic field. However, we show experimentally that an ultra-high-mobility 2DES on the surface of silicon does exhibit the signature of a true metal-insulator phase transition at zero magnetic field at a critical electron density n_c ~10^11 cm-2. The energy of electron-electron interactions, ignored in the scaling theory,^1 is the dominant parameter in this 2DES. The resistivity, ρ, is empirically found to scale near the critical point both with temperature T and electric field E so that it can be represented by the form ρ(T,n_s)=ρ(T/T_0(n_s)) as Earrow0 or ρ(E,n_s)=ρ(E/E_0(n_s)) as Tarrow0. At the transition, the resistivity is close to 3h/e^2. Both scaling parameters, T0 and E_0, show power law behavior at the critical point. This is characteristic of a true phase transition and strongly resembles, in particular, the superconductor-insulator transition in disordered thin films,^2 as well as the transition between quantum Hall liquid and insulator.^3 Many high-mobility samples from two different sources (Institute for Metrological Service, Russia, and Siemens AG, Germany) with different oxide thicknesses and gate materials have been studied and similar results were found. Work done in collaboration with J. E. Furneaux, Whitney Mason, V. M. Pudalov, and M. D'Iorio, supported by NSF. ^1 E. Abrahams, P. W. Anderson, D. C. Licciardello, and T. V. Ramakrishnan, Phys. Rev. Lett. 42, 673 (1979). ^2 Y. Liu, K. A. McGreer, B. Nease, D. B. Haviland, G. Martinez, J. W. Halley, and A. M. Goldman, Phys. Rev. Lett. 67, 2068 (1991). ^3 T. Wang, K. P. Clark, G. F. Spencer, A. M. Mack, and W. P. Kirk, Phys. Rev. Lett. 72, 709 (1994).

  7. 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.

  8. 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.

  9. Electric field-induced transport modulation in VO{sub 2} FETs with high-k oxide/organic parylene-C hybrid gate dielectric

    SciTech Connect

    Wei, Tingting; Kanki, Teruo E-mail: h-tanaka@sanken.osaka-u.ac.jp; Chikanari, Masashi; Tanaka, Hidekazu E-mail: h-tanaka@sanken.osaka-u.ac.jp; Fujiwara, Kohei

    2016-02-01

    We report on the observation of reversible and immediate resistance switching by high-k oxide Ta{sub 2}O{sub 5}/organic parylene-C hybrid dielectric-gated VO{sub 2} thin films. Resistance change ratios at various temperatures in the insulating regime were demonstrated to occur in the vicinity of phase transition temperature. We also found an asymmetric hole-electron carrier modulation related to the suppression of phase transition temperature. The results in this research provide a possibility for clarifying the origin of metal-insulator transition in VO{sub 2} through the electrostatic field-induced transport modulation.

  10. Electric field-induced transport modulation in VO2 FETs with high-k oxide/organic parylene-C hybrid gate dielectric

    NASA Astrophysics Data System (ADS)

    Wei, Tingting; Kanki, Teruo; Fujiwara, Kohei; Chikanari, Masashi; Tanaka, Hidekazu

    2016-02-01

    We report on the observation of reversible and immediate resistance switching by high-k oxide Ta2O5/organic parylene-C hybrid dielectric-gated VO2 thin films. Resistance change ratios at various temperatures in the insulating regime were demonstrated to occur in the vicinity of phase transition temperature. We also found an asymmetric hole-electron carrier modulation related to the suppression of phase transition temperature. The results in this research provide a possibility for clarifying the origin of metal-insulator transition in VO2 through the electrostatic field-induced transport modulation.

  11. Gate direct-tunnelling and hot-carrier-induced hysteresis effect in partially depleted silicon-on-insulator floating-body MOSFETs

    NASA Astrophysics Data System (ADS)

    Zhou, Jianhua; Pang, Albert; Zou, Shichang

    2011-02-01

    The hysteresis effect in the output characteristics of partially depleted (PD) silicon-on-insulator (SOI) floating-body MOSFETs with an ultra-thin gate oxide is studied taking account of both gate direct-tunnelling and impact ionization-induced hot-carrier mechanisms. It is proposed that hole tunnelling from valence band (HVB) for floating-body PD SOI n-MOSFETs, electron tunnelling from conduction band (ECB) for floating-body PD SOI p-MOSFETs and impact-ionization-induced hot carriers are the main causes of the hysteresis effect. Meanwhile, body-contact structures of T-gate and H-gate PD SOI MOSFETs are also studied under floating-body configurations. It is found that the influence of the converse poly-gate on the body-contact side on gate direct-tunnelling cannot be neglected in view of floating-body potential variation. Based on the measurement results, the hysteresis can be suppressed using T-gate and H-gate PD SOI MOSFETs with floating-body configurations.

  12. Leakage and field emission in side-gate graphene field effect transistors

    NASA Astrophysics Data System (ADS)

    Di Bartolomeo, A.; Giubileo, F.; Iemmo, L.; Romeo, F.; Russo, S.; Unal, S.; Passacantando, M.; Grossi, V.; Cucolo, A. M.

    2016-07-01

    We fabricate planar graphene field-effect transistors with self-aligned side-gate at 100 nm from the 500 nm wide graphene conductive channel, using a single lithographic step. We demonstrate side-gating below 1 V with conductance modulation of 35% and transconductance up to 0.5 mS/mm at 10 mV drain bias. We measure the planar leakage along the SiO2/vacuum gate dielectric over a wide voltage range, reporting rapidly growing current above 15 V. We unveil the microscopic mechanisms driving the leakage, as Frenkel-Poole transport through SiO2 up to the activation of Fowler-Nordheim tunneling in vacuum, which becomes dominant at higher voltages. We report a field-emission current density as high as 1 μA/μm between graphene flakes. These findings are important for the miniaturization of atomically thin devices.

  13. Resistance modulation in VO2 nanowires induced by an electric field via air-gap gates

    NASA Astrophysics Data System (ADS)

    Kanki, Teruo; Chikanari, Masashi; Wei, Tingting; Tanaka, Hidekazu; The Institute of Scientific; Industrial Research Team

    Vanadium dioxide (VO2) shows huge resistance change with metal-insulator transition (MIT) at around room temperature. Controlling of the MIT by applying an electric field is a topical ongoing research toward the realization of Mott transistor. In this study, we have successfully switched channel resistance of VO2 nano-wire channels by a pure electrostatic field effect using a side-gate-type field-effect transistor (SG-FET) viaair gap and found that single crystalline VO2 nanowires and the channels with narrower width enhance transport modulation rate. The rate of change in resistance ((R0-R)/R, where R0 and R is the resistance of VO2 channel with off state and on state gate voltage (VG) , respectively) was 0.42 % at VG = 30 V in in-plane poly-crystalline VO2 channels on Al2O3(0001) substrates, while the rate in single crystalline channels on TiO2 (001) substrates was 3.84 %, which was 9 times higher than that using the poly-crystalline channels. With reducing wire width from 3000 nm to 400 nm of VO2 on TiO2 (001) substrate, furthermore, resistance modulation ratio enhanced from 0.67 % to 3.84 %. This change can not be explained by a simple free-electron model. In this presentation, we will compare the electronic properties between in-plane polycrystalline VO2 on Al2O3 (0001) and single crystalline VO2 on TiO2 (001) substrates, and show experimental data in detail..

  14. Field evaluation of 69-kV outdoor Polysil reg sign insulators

    SciTech Connect

    Richenbacher, A.G. )

    1990-03-01

    This report, together with previous interim reports, documents and summarizes the field performance of 69 kV Polysil{reg sign} insulators during the field trial period from January, 1983 to December, 1988. These insulators were manufactured for the Electric Power Research Institute by Lindsey Industries in 1979. A description of the insulator development and manufacturing process is contained in the EPRI Final Report EL1281-1. Following their manufacture, the insulators were delivered, in the form of test racks of 17 Polysil{reg sign} insulators and one porcelain insulator, to twelve United States utilities and the Instituto de Investigaciones Electricas (IIE) in Mexico. These racks were subsequently installed and energized at twenty-five test sites during the latter half of 1979 and early 1980 by the project participants for the purpose of analyzing the outdoor field performance of these insulators and comparing the relative effect on performance of variations in composition, coating, electrical grading method, and shape represented by individual insulators within the test racks. This report documents the effects of the various Polysil{reg sign} insulator parameters on electrical performance in the field over a specific period of 6 years. However, the insulators had been energized for approximately 3 years prior to the initiation of this project and, although specific performance data is not available for that time period, the overall effects of field exposure for that additional time period (total of 9 years) are seen in the results of this report. 3 refs., 23 figs., 9 tabs.

  15. Evolutionary Based Techniques for Fault Tolerant Field Programmable Gate Arrays

    NASA Technical Reports Server (NTRS)

    Larchev, Gregory V.; Lohn, Jason D.

    2006-01-01

    The use of SRAM-based Field Programmable Gate Arrays (FPGAs) is becoming more and more prevalent in space applications. Commercial-grade FPGAs are potentially susceptible to permanently debilitating Single-Event Latchups (SELs). Repair methods based on Evolutionary Algorithms may be applied to FPGA circuits to enable successful fault recovery. This paper presents the experimental results of applying such methods to repair four commonly used circuits (quadrature decoder, 3-by-3-bit multiplier, 3-by-3-bit adder, 440-7 decoder) into which a number of simulated faults have been introduced. The results suggest that evolutionary repair techniques can improve the process of fault recovery when used instead of or as a supplement to Triple Modular Redundancy (TMR), which is currently the predominant method for mitigating FPGA faults.

  16. Three-terminal field effect switches probing the electrically triggered Metal-Insulator Transition in Vanadium dioxide

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Gokul; Ko, Changhyun; Ruzmetov, Dmitry; Narayanamurti, Venkatesh; Ramanathan, Shriram

    2010-03-01

    Electrostatic control of the Metal-Insulator Transition (MIT) in correlated oxides is valuable, both as a probe of the nature of the phase transition, as well as being a critical aspect of novel switching devices based on Mott insulators. Of much recent interest among this class of materials, is vanadium dioxide (VO2), a correlated semiconductor which exhibits a thermally induced MIT close to room temperature, and has also been shown to undergo an ultra-fast switching of conductivity by optical and electrical means. Among many of the experiments demonstrating an electrically triggered transition, however, the attendant phenomenon of Joule heating in the current channel raises questions about the triggering mechanism. To carefully address this issue, we explore the fabrication of three terminal field-effect devices, in which the resistance of a VO2 based channel may be modulated by a gate electric field in the absence of any significant current induced heating. In this talk we present details of the fabrication, the technical challenges involved in implementing them, and results of gated I-V measurements performed on these devices along with our interpretation of the observed effects.

  17. Encapsulated gate-all-around InAs nanowire field-effect transistors

    SciTech Connect

    Sasaki, Satoshi Tateno, Kouta; Zhang, Guoqiang; Suominen, Henri; Harada, Yuichi; Saito, Shiro; Fujiwara, Akira; Sogawa, Tetsuomi; Muraki, Koji

    2013-11-18

    We report the fabrication of lateral gate-all-around InAs nanowire field-effect transistors whose gate overlaps the source and drain electrodes and thus fully encapsulates the nanowire channel. They feature large drive current and transconductance that surpass those of conventional non-gate-overlap devices. The improved device characteristics can be attributed to the elimination of access resistance associated with ungated segments between the gate and source/drain electrodes. Our data also reveal a correlation between the normalized transconductance and the threshold voltage, which points to a beneficial effect of our wet-etching procedure performed prior to the atomic-layer-deposition of the gate dielectric.

  18. High K Oxide Insulated Gate Group III Nitride-Based FETs

    DTIC Science & Technology

    2014-03-21

    AND ADDRESS(ES) Kansas State University 2 Fairchild Hall Manhattan , KS 66506-1103 3. DATES COVERED (From - To) 04/05/2009-03/20/2014 5a. CONTRACT...NUMBER 5b. GRANT NUMBER N00014-09-1-1160 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 09PRE09471-00 5e. TASK NUMBER 5f. WORK UNIT NUMBER 9...results indicate the promising potential of incorporation gate dielectric in future GaN devices. This project supported two students who completed

  19. Top-gated field-effect LaAlO{sub 3}/SrTiO{sub 3} devices made by ion-irradiation

    SciTech Connect

    Hurand, S.; Jouan, A.; Feuillet-Palma, C.; Singh, G.; Malnou, M.; Lesueur, J.; Bergeal, N.; Lesne, E.; Reyren, N.; Barthélémy, A.; Bibes, M.; Villegas, J. E.; Ulysse, C.; Pannetier-Lecoeur, M.

    2016-02-01

    We present a method to fabricate top-gated field-effect devices in a LaAlO{sub 3}/SrTiO{sub 3} two-dimensional electron gas (2-DEG). Prior to the gate deposition, the realisation of micron size conducting channels in the 2-DEG is achieved by an ion-irradiation with high-energy oxygen ions. After identifying the ion fluence as the key parameter that determines the electrical transport properties of the channels, we demonstrate the field-effect operation. At low temperature, the normal state resistance and the superconducting T{sub c} can be tuned over a wide range by a top-gate voltage without any leakage. A superconductor-to-insulator quantum phase transition is observed for a strong depletion of the 2-DEG.

  20. Spatially Uniform Thin-Film Formation of Polymeric Organic Semiconductors on Lyophobic Gate Insulator Surfaces by Self-Assisted Flow-Coating.

    PubMed

    Bulgarevich, Kirill; Sakamoto, Kenji; Minari, Takeo; Yasuda, Takeshi; Miki, Kazushi

    2017-02-22

    Surface hydrophobization by self-assembled monolayer formation is a powerful technique for improving the performance of organic field-effect transistors (OFETs). However, organic thin-film formation on such a surface by solution processing often fails due to the repellent property of the surface against common organic solvents. Here, a scalable unidirectional coating technique that can solve this problem, named self-assisted flow-coating, is reported. Producing a specially designed lyophobic-lyophilic pattern on the lyophobic surface enables organic thin-film formation in the lyophobic surface areas by flow-coating. To demonstrate the usefulness of this technique, OFET arrays with an active layer of poly(2,5-bis(3-hexadecylthiophene-2-yl)thieno[3,2-b]thiophene) are fabricated. The ideal transfer curves without hysteresis behavior are obtained for all OFETs. The average field-effect hole mobility in the saturation regime is 0.273 and 0.221 cm(2)·V(-1)·s(-1) for the OFETs with the channels parallel and perpendicular to the flow-coating direction, respectively, and the device-to-device variation is less than 3% for each OFET set. Very small device-to-device variation is also obtained for the on-state current, threshold voltage, and subthreshold swing. These results indicate that the self-assisted flow-coating is a promising coating technique to form spatially uniform thin films of polymeric organic semiconductors on lyophobic gate insulator surfaces.

  1. Control of Subthreshold Characteristics of Narrow-Channel Silicon-on-Insulator n-Type Metal-Oxide-Semiconductor Transistor with Additional Side Gate Electrodes

    NASA Astrophysics Data System (ADS)

    Okuyama, Kiyoshi; Yoshikawa, Koji; Sunami, Hideo

    2007-04-01

    A silicon-on-insulator (SOI) n-type metal-oxide-semiconductor (MOS) transistor with additional side gate electrodes is fabricated and its subthreshold characteristics are discussed. Since its device structure provides independent biasing to gates, flexible device-characteristic control for the respective device is expected. The key fabrication process is the formation of transistor gates. Additional side gate electrodes are formed by reactive ion etching (RIE) with a SiO2-covered top gate as an etching mask. Subthreshold characteristics are improved by negative side-gate biasing. In addition, the side-gate voltage VSG required to decrease off-leakage current by one decade is around 100 mV. Since the sidewall oxide thickness is chosen to be 5 nm, which is the same as the top-oxide thickness, rather sensitive subthreshold-characteristic control compared with that of biasing through a thick buried-oxide layer is achieved in response to performance requirement. In the viewpoint of stand-by-power suppression, these provide a certain controllability to a circuit operation.

  2. Investigation of field induced trapping on floating gates

    NASA Technical Reports Server (NTRS)

    Gosney, W. M.

    1975-01-01

    The development of a technology for building electrically alterable read only memories (EAROMs) or reprogrammable read only memories (RPROMs) using a single level metal gate p channel MOS process with all conventional processing steps is outlined. Nonvolatile storage of data is achieved by the use of charged floating gate electrodes. The floating gates are charged by avalanche injection of hot electrodes through gate oxide, and discharged by avalanche injection of hot holes through gate oxide. Three extra diffusion and patterning steps are all that is required to convert a standard p channel MOS process into a nonvolatile memory process. For identification, this nonvolatile memory technology was given the descriptive acronym DIFMOS which stands for Dual Injector, Floating gate MOS.

  3. Gate control of percolative conduction in strongly correlated manganite films.

    PubMed

    Hatano, Takafumi; Sheng, Zhigao; Nakamura, Masao; Nakano, Masaki; Kawasaki, Masashi; Iwasa, Yoshihiro; Tokura, Yoshinori

    2014-05-01

    Gate control of percolative conduction in a phase-separated manganite system is demonstrated in a field-effect transistor geometry, resulting in ambipolar switching from a metallic state to an insulating state.

  4. III-V-semiconductor-on-insulator n-channel metal-insulator-semiconductor field-effect transistors with buried Al2O3 layers and sulfur passivation: Reduction in carrier scattering at the bottom interface

    NASA Astrophysics Data System (ADS)

    Yokoyama, Masafumi; Yasuda, Tetsuji; Takagi, Hideki; Miyata, Noriyuki; Urabe, Yuji; Ishii, Hiroyuki; Yamada, Hisashi; Fukuhara, Noboru; Hata, Masahiko; Sugiyama, Masakazu; Nakano, Yoshiaki; Takenaka, Mitsuru; Takagi, Shinichi

    2010-04-01

    We have developed III-V-semiconductor-on-insulator (III-V-OI) structures on Si wafers with excellent bottom interfaces between In0.53Ga0.47As-OI channel layers and atomic-layer-deposited Al2O3 (ALD-Al2O3) buried oxides (BOXs). A surface activated bonding process and the sulfur passivation pretreatment have realized the excellent In0.53Ga0.47As-OI/ALD-Al2O3 BOX bottom interface properties. As a result, the III-V-OI n-channel metal-insulator-semiconductor field-effect transistors under the back-gate configuration showed the peak mobility of 1800 cm2/V s and the higher electron mobility than the Si universal one even in the high effective electric field range because of the reduction in the surface roughness and fixed charges.

  5. Response delay caused by dielectric relaxation of polymer insulators for organic transistors and resolution method

    NASA Astrophysics Data System (ADS)

    Suemori, Kouji; Kamata, Toshihide

    2012-08-01

    We investigated the effect of dielectric relaxation in polymer gate insulators on the device characteristics of organic field effect transistors. Dielectric relaxation of polymer gate insulators caused an increase in drain current (ID) in a period starting immediately after the application of the gate voltage (VG) and lasting several milliseconds. This induced an apparent delay in the response of ID. Based on the observed results, we suggested an ideal gate insulator to achieve organic field effect transistors that have a fast response and high performance.

  6. Assessment of performance potential of MoS{sub 2}-based topological insulator field-effect transistors

    SciTech Connect

    Liu, Leitao; Guo, Jing

    2015-09-28

    It was suggested that single-layer MoS{sub 2} at the 1T′ phase is a topological insulator whose electronic structure can be modulated by a vertical electric field for field-effect transistor (FET) applications [X. Qian, J. Liu, L. Fu, and J. Li, Science 346, 1344 (2014)]. In this work, performance potential of FETs based on vertical field modulation of the topological edge states is assessed by using quantum transport device simulations. To perform efficient device simulations, a phenomenological Hamiltonian is first proposed and validated to capture the effects of electric fields. Because the ON-state conductance is determined by transport through gapless edge states with a long scattering mean free path and the OFF-state conductance by transport through the gapped bulk states, the ON/OFF ratio is sensitive to the channel length, which is different from conventional FETs. Although a high vertical electric field is required to modulate the topological edge state, a reasonably small subthreshold swing of 131 mV/dec can still be achieved for a practical value of the gate insulator thickness.

  7. Critical regime for the insulator-metal transition in highly ordered conjugated polymers gated with ionic liquid

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi; Harada, Tomonori; Tanaka, Hisaaki; Kuroda, Shin-ichi

    2016-03-01

    We report the room-temperature and low-temperature transport properties of a poly(2,5-bis(3-hexadecylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT) film gated with an ionic liquid based on 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide at different annealing temperatures of the PBTTT film. By annealing the film up to 235 °C and subsequently cooling it, we observed a ribbonlike structure, as reported. For the 235-°C-annealed (ribbon phase) film, we could apply a higher voltage without any decrease in the channel conductivity than for the 180-°C-annealed (terrace phase) film. As a result, a charge mobility as high as 10 cm2 V-1 s-1 was achieved for the ribbon-phase film. The power-law behavior of the temperature dependence of the electrical conductivity at low temperatures, indicating the critical regime for the insulator-metal transition, was observed. The ribbon-phase film exhibits an even weaker temperature dependence with a smaller exponent of β = 0.10 than the terrace-phase film.

  8. A New 600 V Punch Through-Insulated Gate Bipolar Transistor with the Monolithic Fault Protection Circuit Using the Floating p-Well Voltage Detection

    NASA Astrophysics Data System (ADS)

    Ji, In-Hwan; Jeon, Byung-Chul; Choi, Young-Hwan; Ha, Min-Woo; Han, Min-Koo

    2006-10-01

    A new fault sensing scheme of the insulated gate bipolar transistor (IGBT) employing the floating p-well, which detects the over-voltage of the floating p-well under the short circuit fault condition, is proposed and implemented by fabricating the main IGBT and gate voltage pull-down circuit using the widely used planar IGBT process. The floating p-well structure also improves the avalanche energy of IGBT in addition to detecting the fault signal. The detection of fault and gate voltage pull-down operation is achieved by the proposed fault protection scheme employing the floating p-well voltage detection. The proposed fault protection circuit was measured under the hard switching fault (HSF) and fault under load (FUL) conditions. The normal switching behavior of the main IGBT with the proposed protection circuit was also investigated under inductive load switching conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  10. Infrared light gated MoS₂ field effect transistor.

    PubMed

    Fang, Huajing; Lin, Ziyuan; Wang, Xinsheng; Tang, Chun-Yin; Chen, Yan; Zhang, Fan; Chai, Yang; Li, Qiang; Yan, Qingfeng; Chan, H L W; Dai, Ji-Yan

    2015-12-14

    Molybdenum disulfide (MoS₂) as a promising 2D material has attracted extensive attentions due to its unique physical, optical and electrical properties. In this work, we demonstrate an infrared (IR) light gated MoS₂ transistor through a device composed of MoS₂ monolayer and a ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O₃-PbTiO₃ (PMN-PT). With a monolayer MoS₂ onto the top surface of (111) PMN-PT crystal, the drain current of MoS₂ channel can be modulated with infrared illumination and this modulation process is reversible. Thus, the transistor can work as a new kind of IR photodetector with a high IR responsivity of 114%/Wcm⁻². The IR response of MoS₂ transistor is attributed to the polarization change of PMN-PT single crystal induced by the pyroelectric effect which results in a field effect. Our result promises the application of MoS₂ 2D material in infrared optoelectronic devices. Combining with the intrinsic photocurrent feature of MoS₂ in the visible range, the MoS₂ on ferroelectric single crystal may be sensitive to a broadband wavelength of light.

  11. Start Up Application Concerns with Field Programmable Gate Arrays (FPGAs)

    NASA Technical Reports Server (NTRS)

    Katz, Richard B.

    1999-01-01

    This note is being published to improve the visibility of this subject, as we continue to see problems surface in designs, as well as to add additional information to the previously published note for design engineers. The original application note focused on designing systems with no single point failures using Actel Field Programmable Gate Arrays (FPGAs) for critical applications. Included in that note were the basic principles of operation of the Actel FPGA and a discussion of potential single-point failures. The note also discussed the issue of startup transients for that class of device. It is unfortunate that we continue to see some design problems using these devices. This note will focus on the startup properties of certain electronic components, in general, and current Actel FPGAs, in particular. Devices that are "power-on friendly" are currently being developed by Actel, as a variant of the new SX series of FPGAs. In the ideal world, electronic components would behave much differently than they do in the real world, The chain, of course, starts with the power supply. Ideally, the voltage will immediately rise to a stable V(sub cc) level, of course, it does not. Aside from practical design considerations, inrush current limits of certain capacitors must be observed and the power supply's output may be intentionally slew rate limited to prevent a large current spike on the system power bus. In any event, power supply rise time may range from less than I msec to 100 msec or more.

  12. Low field magnetoresistance in a 2D topological insulator based on wide HgTe quantum well

    NASA Astrophysics Data System (ADS)

    Olshanetsky, E. B.; Kvon, Z. D.; Gusev, G. M.; Mikhailov, N. N.; Dvoretsky, S. A.

    2016-09-01

    Low field magnetoresistance is experimentally studied in a two-dimensional topological insulator (TI) in both diffusive and quasiballistic samples fabricated on top of a wide (14 nm) HgTe quantum well. In all cases a pronounced quasi-linear positive magnetoresistance is observed similar to that found previously in diffusive samples based on a narrow (8 nm) HgTe well. The experimental results are compared with the main existing theoretical models based on different types of disorder: sample edge roughness, nonmagnetic disorder in an otherwise coherent TI and metallic puddles due to locally trapped charges that act like local gate on the sample. The quasiballistic samples with resistance close to the expected quantized values also show a positive low-field magnetoresistance but with a pronounced admixture of mesoscopic effects.

  13. Electric-field control of spin-orbit torque in magnetically doped topological insulators

    NASA Astrophysics Data System (ADS)

    Fan, Yabin; Shao, Qiming; Kou, Xufeng; Upadhyaya, Pramey; Wang, Kang

    Recent advances of spin-orbit torques (SOTs) generated by topological insulators (TIs) have drawn increasing interest to the spin-momentum locking feature of TIs' surface states, which can potentially provide a very efficient means to generate SOTs for spintronic applications. In this presentation, we will show the magnetization switching through current-induced giant SOT in both TI/Cr-doped TI bilayer and uniformly Cr-doped TI films In particular, we show that the current-induced SOT has significant contribution from the spin-momentum locked surface states of TIs. We find that the spin torque efficiency is in general three orders of magnitude larger than those reported in heavy metal/ferromagnetic heterostructures. In the second part, we will present the electric-field control of the giant SOT in magnetically doped TIs, which suggests promising gate-controlled spin-torque device applications. The giant SOT and efficient current-induced magnetization switching exhibited by the magnetic TIs may lead to innovative spintronic applications such as ultralow power dissipation memory and logic devices. We acknowledge the supports from DARPA, FAME, SHINES and ARO programs.

  14. Threshold voltage model of junctionless cylindrical surrounding gate MOSFETs including fringing field effects

    NASA Astrophysics Data System (ADS)

    Gupta, Santosh Kumar

    2015-12-01

    2D Analytical model of the body center potential (BCP) in short channel junctionless Cylindrical Surrounding Gate (JLCSG) MOSFETs is developed using evanescent mode analysis (EMA). This model also incorporates the gate bias dependent inner and outer fringing capacitances due to the gate-source/drain fringing fields. The developed model provides results in good agreement with simulated results for variations of different physical parameters of JLCSG MOSFET viz. gate length, channel radius, doping concentration, and oxide thickness. Using the BCP, an analytical model for the threshold voltage has been derived and validated against results obtained from 3D device simulator.

  15. Sensing with Advanced Computing Technology: Fin Field-Effect Transistors with High-k Gate Stack on Bulk Silicon.

    PubMed

    Rigante, Sara; Scarbolo, Paolo; Wipf, Mathias; Stoop, Ralph L; Bedner, Kristine; Buitrago, Elizabeth; Bazigos, Antonios; Bouvet, Didier; Calame, Michel; Schönenberger, Christian; Ionescu, Adrian M

    2015-05-26

    Field-effect transistors (FETs) form an established technology for sensing applications. However, recent advancements and use of high-performance multigate metal-oxide semiconductor FETs (double-gate, FinFET, trigate, gate-all-around) in computing technology, instead of bulk MOSFETs, raise new opportunities and questions about the most suitable device architectures for sensing integrated circuits. In this work, we propose pH and ion sensors exploiting FinFETs fabricated on bulk silicon by a fully CMOS compatible approach, as an alternative to the widely investigated silicon nanowires on silicon-on-insulator substrates. We also provide an analytical insight of the concept of sensitivity for the electronic integration of sensors. N-channel fully depleted FinFETs with critical dimensions on the order of 20 nm and HfO2 as a high-k gate insulator have been developed and characterized, showing excellent electrical properties, subthreshold swing, SS ∼ 70 mV/dec, and on-to-off current ratio, Ion/Ioff ∼ 10(6), at room temperature. The same FinFET architecture is validated as a highly sensitive, stable, and reproducible pH sensor. An intrinsic sensitivity close to the Nernst limit, S = 57 mV/pH, is achieved. The pH response in terms of output current reaches Sout = 60%. Long-term measurements have been performed over 4.5 days with a resulting drift in time δVth/δt = 0.10 mV/h. Finally, we show the capability to reproduce experimental data with an extended three-dimensional commercial finite element analysis simulator, in both dry and wet environments, which is useful for future advanced sensor design and optimization.

  16. Use of a hard mask for formation of gate and dielectric via nanofilament field emission devices

    DOEpatents

    Morse, Jeffrey D.; Contolini, Robert J.

    2001-01-01

    A process for fabricating a nanofilament field emission device in which a via in a dielectric layer is self-aligned to gate metal via structure located on top of the dielectric layer. By the use of a hard mask layer located on top of the gate metal layer, inert to the etch chemistry for the gate metal layer, and in which a via is formed by the pattern from etched nuclear tracks in a trackable material, a via is formed by the hard mask will eliminate any erosion of the gate metal layer during the dielectric via etch. Also, the hard mask layer will protect the gate metal layer while the gate structure is etched back from the edge of the dielectric via, if such is desired. This method provides more tolerance for the electroplating of a nanofilament in the dielectric via and sharpening of the nanofilament.

  17. Technologies for suppressing charge-traps in novel p-channel Field-MOSFET with thick gate oxide

    NASA Astrophysics Data System (ADS)

    Miyoshi, Tomoyuki; Oshima, Takayuki; Noguchi, Junji

    2015-05-01

    High voltage laterally diffused MOS (LDMOS) FETs are widely used in analog applications. A Field-MOSFET with a thick gate oxide is one of the best ways of achieving a simpler design and smaller circuit footprint for high-voltage analog circuits. This paper focuses on an approach to improving the reliability of p-channel Field-MOSFETs. By introducing a fluorine implantation process and terminating fluorine at the LOCOS bird’s beak, the gate oxide breakdown voltage could be raised to 350 V at a high-slew rate and the negative bias temperature instability (NBTI) shift could be kept to within 15% over a product’s lifetime. By controlling the amount of charge in the insulating layer through improving the interlayer dielectric (ILD) deposition processes, a higher BVDSS of 370 V and 10-year tolerability of 300 V were obtained with an assisted reduced surface electric field (RESURF) effect. These techniques can supply an efficient solution for ensuring reliable high-performance applications.

  18. Flat Panel Light Source with Lateral Gate Structure Based on SiC Nanowire Field Emitters

    PubMed Central

    Youh, Meng-Jey; Tseng, Chun-Lung; Jhuang, Meng-Han; Chiu, Sheng-Cheng; Huang, Li-Hu; Gong, Jyun-An; Li, Yuan-Yao

    2015-01-01

    A field-emission light source with high luminance, excellent luminance uniformity, and tunable luminance characteristics with a novel lateral-gate structure is demonstrated. The lateral-gate triode structure comprises SiC nanowire emitters on a Ag cathode electrode and a pair of Ag gate electrodes placed laterally on both sides of the cathode. The simple and cost-effective screen printing technique is employed to pattern the lateral-gates and cathode structure on soda lime glass. The area coverage of the screen-printed cathode and gates on the glass substrate (area: 6 × 8 cm2) is in the range of 2.04% – 4.74% depending on the set of cathode-gate electrodes on the substrate. The lateral-gate structure with its small area coverage exhibits a two-dimensional luminance pattern with high brightness and good luminance uniformity. A maximum luminance of 10952 cd/cm2 and a luminance uniformity of >90% can be achieved with a gate voltage of 500 V and an anode voltage of 4000 V, with an anode current of 1.44 mA and current leakage to the gate from the cathode of about 10%. PMID:26042359

  19. On the high-field transport and its temperature dependence in deca-nanometer fully depleted silicon-on-insulator field-effect-transistor

    NASA Astrophysics Data System (ADS)

    Kobayashi, Masaharu; Cai, Jin; Haensch, Wilfried

    2011-08-01

    Low-temperature characterization has been performed on fully depleted silicon-on-insulator (FDSOI) field-effect-transistor (FET) with gate length (Lg) down to 25 nm to clarify transport mechanisms that determine device performance in deca-nanometer scale. Linear drain current of FDSOI FET follows Lg-1 scaling down to 25 nm Lg, where mobility dominates, while saturation drain current largely deviates from Lg-1 scaling. Temperature dependence of effective source velocity at high drain voltage (Vds) is weaker than that at low Vds in short Lg and is consistent with that of saturation velocity. Drift velocity measurement revealed velocity overshooting behavior at high lateral field, indicating further Lg scaling benefit.

  20. Field-effect transistor replaces bulky transformer in analog-gate circuit

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Metal-oxide semiconductor field-effect transistor /MOSFET/ analog-gate circuit adapts well to integrated circuits. It provides better system isolation than a transformer, while size and weight are appreciably reduced.

  1. Organic field-effect transistor nonvolatile memories utilizing sputtered C nanoparticles as nano-floating-gate

    SciTech Connect

    Liu, Jie; Liu, Chang-Hai; She, Xiao-Jian; Sun, Qi-Jun; Gao, Xu; Wang, Sui-Dong

    2014-10-20

    High-performance organic field-effect transistor nonvolatile memories have been achieved using sputtered C nanoparticles as the nano-floating-gate. The sputtered C nano-floating-gate is prepared with low-cost material and simple process, forming uniform and discrete charge trapping sites covered by a smooth and complete polystyrene layer. The devices show large memory window, excellent retention capability, and programming/reading/erasing/reading endurance. The sputtered C nano-floating-gate can effectively trap both holes and electrons, and it is demonstrated to be suitable for not only p-type but also n-type organic field-effect transistor nonvolatile memories.

  2. Optimization of a Solution-Processed SiO2 Gate Insulator by Plasma Treatment for Zinc Oxide Thin Film Transistors.

    PubMed

    Jeong, Yesul; Pearson, Christopher; Kim, Hyun-Gwan; Park, Man-Young; Kim, Hongdoo; Do, Lee-Mi; Petty, Michael C

    2016-01-27

    We report on the optimization of the plasma treatment conditions for a solution-processed silicon dioxide gate insulator for application in zinc oxide thin film transistors (TFTs). The SiO2 layer was formed by spin coating a perhydropolysilazane (PHPS) precursor. This thin film was subsequently thermally annealed, followed by exposure to an oxygen plasma, to form an insulating (leakage current density of ∼10(-7) A/cm(2)) SiO2 layer. Optimized ZnO TFTs (40 W plasma treatment of the gate insulator for 10 s) possessed a carrier mobility of 3.2 cm(2)/(V s), an on/off ratio of ∼10(7), a threshold voltage of -1.3 V, and a subthreshold swing of 0.2 V/decade. In addition, long-term exposure (150 min) of the pre-annealed PHPS to the oxygen plasma enabled the maximum processing temperature to be reduced from 180 to 150 °C. The resulting ZnO TFT exhibited a carrier mobility of 1.3 cm(2)/(V s) and on/off ratio of ∼10(7).

  3. Nonvolatile memory thin-film transistors using biodegradable chicken albumen gate insulator and oxide semiconductor channel on eco-friendly paper substrate.

    PubMed

    Kim, So-Jung; Jeon, Da-Bin; Park, Jung-Ho; Ryu, Min-Ki; Yang, Jong-Heon; Hwang, Chi-Sun; Kim, Gi-Heon; Yoon, Sung-Min

    2015-03-04

    Nonvolatile memory thin-film transistors (TFTs) fabricated on paper substrates were proposed as one of the eco-friendly electronic devices. The gate stack was composed of chicken albumen gate insulator and In-Ga-Zn-O semiconducting channel layers. All the fabrication processes were performed below 120 °C. To improve the process compatibility of the synthethic paper substrate, an Al2O3 thin film was introduced as adhesion and barrier layers by atomic layer deposition. The dielectric properties of biomaterial albumen gate insulator were also enhanced by the preparation of Al2O3 capping layer. The nonvolatile bistabilities were realized by the switching phenomena of residual polarization within the albumen thin film. The fabricated device exhibited a counterclockwise hysteresis with a memory window of 11.8 V, high on/off ratio of approximately 1.1 × 10(6), and high saturation mobility (μsat) of 11.5 cm(2)/(V s). Furthermore, these device characteristics were not markedly degraded even after the delamination and under the bending situration. When the curvature radius was set as 5.3 cm, the ION/IOFF ratio and μsat were obtained to be 5.9 × 10(6) and 7.9 cm(2)/(V s), respectively.

  4. High performance thin film transistor (flex-TFT) with textured nanostructure ZnO film channel fabricated by exploiting electric double layer gate insulator

    NASA Astrophysics Data System (ADS)

    Ghimire, Rishi Ram; Raychaudhuri, A. K.

    2017-01-01

    We report a flexible thin film transistor (flex-TFT) fabricated on a commonly available polyimide (Kapton®) tape with a channel of highly textured nanocrystalline ZnO film grown by pulsed laser deposition. The flex-TFT with an electric double layer (EDL) gate insulator shows a low threshold for operation (Vth ≤ 1 V), an ON/OFF ratio reaching ≈107 and a subthreshold swing ≈75 mV/dec. The superior performance is enabled by a high saturation mobility (μs ≈ 70 cm2/V s) of the highly textured nanocrystalline channel. The low Vth arises from large charge density (≈1014/cm2) induced into the channel by EDL gate insulator. The large charge density induced by the EDL gate dielectric also enhances the Hall mobility in the film and brings down the sheet resistance by nearly 2 orders, which leads to large ON/OFF ratio. The flex-TFT operation can be sustained with reproducibility when the TFT is bent down to a radius of curvature ≈2 cm.

  5. Development of Gate and Base Drive Using SiC Junction Field Effect Transistors

    DTIC Science & Technology

    2008-05-01

    Development of Gate and Base Drive Using SiC Junction Field Effect Transistors by Timothy E. Griffin ARL-TR-4475 May 2008...Development of Gate and Base Drive Using SiC Junction Field Effect Transistors Timothy E. Griffin Sensors and Electron Devices...Effect Transistors 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 6. AUTHOR(S) Timothy E. Griffin 5f. WORK UNIT NUMBER

  6. 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).

  7. Liquid crystal-gated-organic field-effect transistors with in-plane drain-source-gate electrode structure.

    PubMed

    Seo, Jooyeok; Nam, Sungho; Jeong, Jaehoon; Lee, Chulyeon; Kim, Hwajeong; Kim, Youngkyoo

    2015-01-14

    We report planar liquid crystal-gated-organic field-effect transistors (LC-g-OFETs) with a simple in-plane drain-source-gate electrode structure, which can be cost-effectively prepared by typical photolithography/etching processes. The LC-g-OFET devices were fabricated by forming the LC layer (4-cyano-4'-pentylbiphenyl, 5CB) on top of the channel layer (poly(3-hexylthiophene), P3HT) that was spin-coated on the patterned indium-tin oxide (ITO)-coated glass substrates. The LC-g-OFET devices showed p-type transistor characteristics, while a current saturation behavior in the output curves was achieved for the 50-150 nm-thick P3HT (channel) layers. A prospective on/off ratio (>1 × 10(3)) was obtained regardless of the P3HT thickness, whereas the resulting hole mobility (0.5-1.1 cm(2)/(V s)) at a linear regime was dependent on the P3HT thickness. The tilted ordering of 5CB at the LC-P3HT interfaces, which is induced by the gate electric field, has been proposed as a core point of working mechanism for the present LC-g-OFETs.

  8. Semi-flexible gas-insulated transmission line using electric field stress shields

    DOEpatents

    Cookson, A.H.; Dale, S.J.; Bolin, P.C.

    1982-12-28

    A gas-insulated transmission line includes an outer sheath, an inner conductor, an insulating gas electrically insulating the inner conductor from the outer sheath, and insulating supports insulatably supporting the inner conductor within the outer sheath. The inner conductor is provided with flexibility by use of main conductor sections which are joined together through a conductor hub section and flexible flexing elements. Stress shields are provided to control the electric field at the locations of the conductor hub sections where the insulating supports are contacting the inner conductor. The flexing elements and the stress shields may also be utilized in connection with a plug and socket arrangement for providing electrical connection between main conductor sections. 10 figs.

  9. Semi-flexible gas-insulated transmission line using electric field stress shields

    DOEpatents

    Cookson, Alan H.; Dale, Steinar J.; Bolin, Philip C.

    1982-12-28

    A gas-insulated transmission line includes an outer sheath, an inner conductor, an insulating gas electrically insulating the inner conductor from the outer sheath, and insulating supports insulatably supporting the inner conductor within the outer sheath. The inner conductor is provided with flexibility by use of main conductor sections which are joined together through a conductor hub section and flexible flexing elements. Stress shields are provided to control the electric field at the locations of the conductor hub sections where the insulating supports are contacting the inner conductor. The flexing elements and the stress shields may also be utilized in connection with a plug and socket arrangement for providing electrical connection between main conductor sections.

  10. High mobility field effect transistor based on BaSnO{sub 3} with Al{sub 2}O{sub 3} gate oxide

    SciTech Connect

    Park, Chulkwon; Kim, Useong; Ju, Chan Jong; Park, Ji Sung; Kim, Young Mo; Char, Kookrin

    2014-11-17

    We fabricated an n-type accumulation-mode field effect transistor based on BaSnO{sub 3} transparent perovskite semiconductor, taking advantage of its high mobility and oxygen stability. We used the conventional metal-insulator-semiconductor structures: (In,Sn){sub 2}O{sub 3} as the source, drain, and gate electrodes, Al{sub 2}O{sub 3} as the gate insulator, and La-doped BaSnO{sub 3} as the semiconducting channel. The Al{sub 2}O{sub 3} gate oxide was deposited by atomic layer deposition technique. At room temperature, we achieved the field effect mobility value of 17.8 cm{sup 2}/Vs and the I{sub on}/I{sub off} ratio value higher than 10{sup 5} for V{sub DS} = 1 V. These values are higher than those previously reported on other perovskite oxides, in spite of the large density of threading dislocations in the BaSnO{sub 3} on SrTiO{sub 3} substrates. However, a relatively large subthreshold swing value was found, which we attribute to the large density of charge traps in the Al{sub 2}O{sub 3} as well as the threading dislocations.

  11. The Substrate is a pH-Controlled Second Gate of Electrolyte-Gated Organic Field-Effect Transistor.

    PubMed

    Di Lauro, Michele; Casalini, Stefano; Berto, Marcello; Campana, Alessandra; Cramer, Tobias; Murgia, Mauro; Geoghegan, Mark; Bortolotti, Carlo A; Biscarini, Fabio

    2016-11-23

    Electrolyte-gated organic field-effect transistors (EGOFETs), based on ultrathin pentacene films on quartz, were operated with electrolyte solutions whose pH was systematically changed. Transistor parameters exhibit nonmonotonic variation versus pH, which cannot be accounted for by capacitive coupling through the Debye-Helmholtz layer. The data were fitted with an analytical model of the accumulated charge in the EGOFET, where Langmuir adsorption was introduced to describe the pH-dependent charge buildup at the quartz surface. The model provides an excellent fit to the threshold voltage and transfer characteristics as a function of the pH, which demonstrates that quartz acts as a second gate controlled by pH and is mostly effective from neutral to alkaline pH. The effective capacitance of the device is always greater than the capacitance of the electrolyte, thus highlighting the role of the substrate as an important active element for amplification of the transistor response.

  12. Stark shift and field ionization of arsenic donors in {sup 28}Si-silicon-on-insulator structures

    SciTech Connect

    Lo, C. C. Morton, J. J. L.; Simmons, S.; Lo Nardo, R.; Weis, C. D.; Schenkel, T.; Tyryshkin, A. M.; Lyon, S. A.; Meijer, J.; Rogalla, D.; Bokor, J.

    2014-05-12

    We develop an efficient back gate for silicon-on-insulator (SOI) devices operating at cryogenic temperatures and measure the quadratic hyperfine Stark shift parameter of arsenic donors in isotopically purified {sup 28}Si-SOI layers using such structures. The back gate is implemented using MeV ion implantation through the SOI layer forming a metallic electrode in the handle wafer, enabling large and uniform electric fields up to 2 V/μm to be applied across the SOI layer. Utilizing this structure, we measure the Stark shift parameters of arsenic donors embedded in the {sup 28}Si-SOI layer and find a contact hyperfine Stark parameter of η{sub a} = −1.9 ± 0.7 × 10{sup −3} μm{sup 2}/V{sup 2}. We also demonstrate electric-field driven dopant ionization in the SOI device layer, measured by electron spin resonance.

  13. O3-sourced atomic layer deposition of high quality Al2O3 gate dielectric for normally-off GaN metal-insulator-semiconductor high-electron-mobility transistors

    NASA Astrophysics Data System (ADS)

    Huang, Sen; Liu, Xinyu; Wei, Ke; Liu, Guoguo; Wang, Xinhua; Sun, Bing; Yang, Xuelin; Shen, Bo; Liu, Cheng; Liu, Shenghou; Hua, Mengyuan; Yang, Shu; Chen, Kevin J.

    2015-01-01

    High quality Al2O3 film grown by atomic layer deposition (ALD), with ozone (O3) as oxygen source, is demonstrated for fabrication of normally-off AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs). Significant suppression of Al-O-H and Al-Al bonds in ALD-Al2O3 has been realized by substituting conventional H2O source with O3. A high dielectric breakdown E-field of 8.5 MV/cm and good TDDB behavior are achieved in a gate dielectric stack consisting of 13-nm O3-Al2O3 and 2-nm H2O-Al2O3 interfacial layer on recessed GaN. By using this 15-nm gate dielectric and a high-temperature gate-recess technique, the density of positive bulk/interface charges in normally-off AlGaN/GaN MIS-HEMTs is remarkably suppressed to as low as 0.9 × 1012 cm-2, contributing to the realization of normally-off operation with a high threshold voltage of +1.6 V and a low specific ON-resistance RON,sp of 0.49 mΩ cm2.

  14. Influence of line-edge roughness on multiple-gate tunnel field-effect transistors

    NASA Astrophysics Data System (ADS)

    Choi, Woo Young

    2017-04-01

    The influence of fin-line-edge roughness (fin-LER) and gate-LER on multiple-gate (MG) tunnel field-effect transistors (TFETs) has been investigated compared with MG MOSFETs by using full three-dimensional technology computer-aided design (TCAD) simulation. From simulation results, two interesting results have been observed. First, MG TFETs show much less severe gate-LER than MG MOSFETs, which means that only fin-LER can be considered when evaluating the total LER of MG TFETs. Second, TFETs show ∼3× more LER improvement than MOSFETs when their structures are changed from double-gate (DG) to triple-gate (TG) ones. Our findings provide the useful design guidelines of variation-tolerant TFETs.

  15. Gate controlled electronic transport in monolayer MoS{sub 2} field effect transistor

    SciTech Connect

    Zhou, Y. F.; Wang, B.; Yu, Y. J.; Wei, Y. D. E-mail: jianwang@hku.hk; Xian, H. M.; Wang, J. E-mail: jianwang@hku.hk

    2015-03-14

    The electronic spin and valley transport properties of a monolayer MoS{sub 2} are investigated using the non-equilibrium Green's function formalism combined with density functional theory. Due to the presence of strong Rashba spin orbit interaction (RSOI), the electronic valence bands of monolayer MoS{sub 2} are split into spin up and spin down Zeeman-like texture near the two inequivalent vertices K and K′ of the first Brillouin zone. When the gate voltage is applied in the scattering region, an additional strong RSOI is induced which generates an effective magnetic field. As a result, electron spin precession occurs along the effective magnetic field, which is controlled by the gate voltage. This, in turn, causes the oscillation of conductance as a function of the magnitude of the gate voltage and the length of the gate region. This current modulation due to the spin precession shows the essential feature of the long sought Datta-Das field effect transistor (FET). From our results, the oscillation periods for the gate voltage and gate length are found to be approximately 2.2 V and 20.03a{sub B} (a{sub B} is Bohr radius), respectively. These observations can be understood by a simple spin precessing model and indicate that the electron behaviors in monolayer MoS{sub 2} FET are both spin and valley related and can easily be controlled by the gate.

  16. Flexible gas insulated transmission line having regions of reduced electric field

    DOEpatents

    Cookson, Alan H.; Fischer, William H.; Yoon, Kue H.; Meyer, Jeffry R.

    1983-01-01

    A gas insulated transmission line having radially flexible field control means for reducing the electric field along the periphery of the inner conductor at predetermined locations wherein the support insulators are located. The radially flexible field control means of the invention includes several structural variations of the inner conductor, wherein careful controlling of the length to depth of surface depressions produces regions of reduced electric field. Several embodiments of the invention dispose a flexible connector at the predetermined location along the inner conductor where the surface depressions that control the reduced electric field are located.

  17. Fabrication of Ta2O5/GeNx gate insulator stack for Ge metal-insulator-semiconductor structures by electron-cyclotron-resonance plasma nitridation and sputtering deposition techniques

    NASA Astrophysics Data System (ADS)

    Otani, Yohei; Itayama, Yasuhiro; Tanaka, Takuo; Fukuda, Yukio; Toyota, Hiroshi; Ono, Toshiro; Mitsui, Minoru; Nakagawa, Kiyokazu

    2007-04-01

    The authors have fabricated germanium (Ge) metal-insulator-semiconductor (MIS) structures with a 7-nm-thick tantalum pentaoxide (Ta2O5)/2-nm-thick germanium nitride (GeNx) gate insulator stack by electron-cyclotron-resonance plasma nitridation and sputtering deposition. They found that pure GeNx ultrathin layers can be formed by the direct plasma nitridation of the Ge surface without substrate heating. X-ray photoelectron spectroscopy revealed no oxidation of the GeNx layer after the Ta2O5 sputtering deposition. The fabricated MIS capacitor with a capacitance equivalent thickness of 4.3nm showed excellent leakage current characteristics. The interface trap density obtained by the modified conductance method was 4×1011cm-2eV-1 at the midgap.

  18. Environmentally stable flexible metal-insulator-metal capacitors using zirconium-silicate and hafnium-silicate thin film composite materials as gate dielectrics.

    PubMed

    Meena, Jagan Singh; Chu, Min-Ching; Wu, Chung-Shu; Ravipati, Srikanth; Ko, Fu-Hsiang

    2011-08-01

    Fully flexible metal-insulator-metal (MIM) capacitors fabricated on 25 microm thin polyimide (PI) substrates via the surface sol-gel process using 10-nm-thick zirconium-silicate (ZrSixOy) and hafnium-silicate (HfSimOn) films as gate dielectrics. The surface morphology of the ZrSixOy and HfSimOn films were investigated using atomic force microscopy and scanning electron microscopy, which confirmed that continuous and crack-free surface growth had occurred on the PI. Both the films treated with oxygen (O2) plasma and annealing (ca. 250 degrees C) consisted of amorphous phase; confirmed by X-ray diffraction. We employed X-ray photoelectron spectroscopy (XPS) at high resolution to examine the chemical composition of the films subjected to various treatment conditions. The shift of the XPS peaks towards higher binding energy revealed the O2 plasma-pretreatment followed by annealing was the most effective process to the surface oxidation at relatively low-temperature, for further passivate the grease traps and making dielectric films thermally stable. The ZrSixOy and HfSimOn films in sandwich-like MIM configuration on the PI substrates exhibited the low leakage current densities of 7.1 x 10(-9) and 8.4 x 10(-9) A/cm2 at applied electric field of 10 MV/cm and maximum capacitance densities of 7.5 and 5.3 fF/microm2 at 1 MHz, respectively. In addition, the ZrSixOy and HfSimOn films in MIM capacitors showed the estimated dielectric constants of 8.2 and 6.0, respectively. Prior to use of flexible MIM capacitors in advanced flexible electronic devices; the reliability test was studied by applying day-dependent leakage current density measurements up to 30 days. These films of silicate-surfactant mesostructured materials have special interest to be used as gate dielectrics in future for flexible metal-oxide-semiconductor devices.

  19. Moffett Field Funnel and Gate TCE Treatment System: Interpretation of Field Performance using Reactive Transport Modeling

    SciTech Connect

    Yabusaki, Steven B.; Cantrell, Kirk J.; Sass, B. M.

    2001-06-30

    A multicomponent reactive transport simulator was used to understand the behavior of chemical components, including TCE and cis-1,2-DCE, in groundwater transported through the pilot-scale funnel and gate chemical treatment system at Moffett Field, California. Field observations indicated that zero-valent iron emplaced in the gate to effect the destruction of chlorinated hydrocarbons also resulted in increases in pH and hydrocarbons, as well as decreases in EH, alkalinity, dissolved O2 and CO2, and major ions (i.e., Ca, Mg, Cl, sulfate, nitrate). Of concern are chemical transformations that may reduce the effectiveness or longevity of the iron cell and/or create secondary contaminants. A coupled model of transport and reaction processes was developed to account for mobile and immobile components undergoing equilibrium and kinetic reactions including TCE degradation, parallel iron dissolution reactions, precipitation of secondary minerals, and complexation reactions. The model reproduced solution chemistry observed in the iron cell using reaction parameters from the literature and laboratory studies. Mineral precipitation in the iron zone, which is critical to correctly predicting the aqueous concentrations, was predicted to account for up to 3 percent additional mineral volume annually. Interplay between rates of transport and rates of reaction in the field was key to understanding system behavior.

  20. Effect of Polymer Gate Dielectrics on Charge Transport in Carbon Nanotube Network Transistors: Low-k Insulator for Favorable Active Interface.

    PubMed

    Lee, Seung-Hoon; Xu, Yong; Khim, Dongyoon; Park, Won-Tae; Kim, Dong-Yu; Noh, Yong-Young

    2016-11-30

    Charge transport in carbon nanotube network transistors strongly depends on the properties of the gate dielectric that is in direct contact with the semiconducting carbon nanotubes. In this work, we investigate the dielectric effects on charge transport in polymer-sorted semiconducting single-walled carbon nanotube field-effect transistors (s-SWNT-FETs) by using three different polymer insulators: A low-permittivity (εr) fluoropolymer (CYTOP, εr = 1.8), poly(methyl methacrylate) (PMMA, εr = 3.3), and a high-εr ferroelectric relaxor [P(VDF-TrFE-CTFE), εr = 14.2]. The s-SWNT-FETs with polymer dielectrics show typical ambipolar charge transport with high ON/OFF ratios (up to ∼10(5)) and mobilities (hole mobility up to 6.77 cm(2) V(-1) s(-1) for CYTOP). The s-SWNT-FET with the lowest-k dielectric, CYTOP, exhibits the highest mobility owing to formation of a favorable interface for charge transport, which is confirmed by the lowest activation energies, evaluated by the fluctuation-induced tunneling model (FIT) and the traditional Arrhenius model (EaFIT = 60.2 meV and EaArr = 10 meV). The operational stability of the devices showed a good agreement with the activation energies trend (drain current decay ∼14%, threshold voltage shift ∼0.26 V in p-type regime of CYTOP devices). The poor performance in high-εr devices is accounted for by a large energetic disorder caused by the randomly oriented dipoles in high-k dielectrics. In conclusion, the low-k dielectric forms a favorable interface with s-SWNTs for efficient charge transport in s-SWNT-FETs.

  1. Fabrication of a metal-oxide-semiconductor-type capacitive microtip array using SiO2 or HfO2 gate insulators

    NASA Astrophysics Data System (ADS)

    Kim, Kyung-Min; Choi, Byung Joon; Kim, Seong Keun; Hwang, Cheol Seong

    2004-11-01

    Capacitive tip arrays having a metal-insulator-semiconductor capacitor structure were fabricated using thermally oxidized SiO2 or atomic-layer-deposited HfO2 gate dielectric films for their application to scanning-probe-array-type memory devices. The SiO2 film showed a nonuniform thickness distribution over the flat and tip areas of the arrays owing to the different oxidation speeds of the flat and tip Si surfaces. This resulted in a smaller sensing margin of the device. However, the high-dielectric HfO2 film showed not only a higher capacitance value but also a more uniform growth behavior over the whole area, which would result in a better device performance. The capacitance-voltage characteristics of both devices coincide well with the simulation results based on conventional metal-insulator-semiconductor theories.

  2. Effect of nitrogen incorporation into Al-based gate insulators in AlON/AlGaN/GaN metal-oxide-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Asahara, Ryohei; Nozaki, Mikito; Yamada, Takahiro; Ito, Joyo; Nakazawa, Satoshi; Ishida, Masahiro; Ueda, Tetsuzo; Yoshigoe, Akitaka; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2016-10-01

    The superior physical and electrical properties of aluminum oxynitride (AlON) gate dielectrics on AlGaN/GaN substrates in terms of thermal stability, reliability, and interface quality were demonstrated by direct AlON deposition and subsequent annealing. Nitrogen incorporation into alumina was proven to be beneficial both for suppressing intermixing at the insulator/AlGaN interface and reducing the number of electrical defects in Al2O3 films. Consequently, we achieved high-quality AlON/AlGaN/GaN metal-oxide-semiconductor capacitors with improved stability against charge injection and a reduced interface state density as low as 1.2 × 1011 cm-2 eV-1. The impact of nitrogen incorporation into the insulator will be discussed on the basis of experimental findings.

  3. A Novel Gate Electrode Structure for Reduction of Gate Resistance of Sub-0.1 µm RF/Mixed-Signal Metal Oxide Semiconductor Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Nagase, Hirokazu; Tanabe, Akira; Umeda, Kyoko; Watanabe, Takashi; Hayashi, Yoshihiro

    2009-04-01

    To reduce noise and enhance gain for scaled-down metal oxide semiconductor field-effect transistors (MOSFETs), a novel gate electrode structure “direct finger contact (DFC)” is proposed. The DFC structure reduces the gate electrode resistance by 40%. NF50 (noise figure when the input impedance is 50 Ω) is reduced by 4% with the gate length L = 48 nm, the gate width Wfinger =1 µm, and the number of finger N =20. This structure is suitable for low-noise sub-0.1 µm RF/mixed-signal system on chips (SoCs).

  4. Induced fields, charges and currents on a lineman engaged in transmission-line insulator washing

    SciTech Connect

    Abdel-Salam, M.; El-Mohandes, M.T.; Alghamdi, A.S.

    1995-12-31

    This paper is aimed to calculate the distribution of the field, induced charges and currents on a lineman engaged in transmission-line insulator washing. The method of analysis is based on the charge simulation technique. The lineman is modeled by small sphere for the head and a large sphere for the body. For simplicity, the tower is chosen of the duct type and the insulator of the suspension type. The transmission-line conductor is simulated by finite and semi-infinite line charges to account for the nonuniform distribution of conductor charge resulting from the suspension insulator and the supporting tower. As the purity of the washing water is high, the water spray is simulated by a thin conducting stick extending between the column insulator and the lineman sitting on the crossarm of the tower. This represents a three-dimensional field problem and care has been devoted in the choice of the number and coordinates of charges simulating the tower, the insulator, the conductor, the water spray and the lineman. The induced currents increase as the lineman approaches the insulator with the suspended line conductor. These currents are higher than those for insulated lineman and may exceed the safe limits.

  5. Gate-control efficiency and interface state density evaluated from capacitance-frequency-temperature mapping for GaN-based metal-insulator-semiconductor devices

    SciTech Connect

    Shih, Hong-An; Kudo, Masahiro; Suzuki, Toshi-kazu

    2014-11-14

    We present an analysis method for GaN-based metal-insulator-semiconductor (MIS) devices by using capacitance-frequency-temperature (C-f-T) mapping to evaluate the gate-control efficiency and the interface state density, both exhibiting correlations with the linear-region intrinsic transconductance. The effectiveness of the method was exemplified by application to AlN/AlGaN/GaN MIS devices to elucidate the properties of AlN-AlGaN interfaces depending on their formation processes. Using the C-f-T mapping, we extract the gate-bias-dependent activation energy with its derivative giving the gate-control efficiency, from which we evaluate the AlN-AlGaN interface state density through the Lehovec equivalent circuit in the DC limit. It is shown that the gate-control efficiency and the interface state density have correlations with the linear-region intrinsic transconductance, all depending on the interface formation processes. In addition, we give characterization of the AlN-AlGaN interfaces by using X-ray photoelectron spectroscopy, in relation with the results of the analysis.

  6. Physical Modeling of Gate-Controlled Schottky Barrier Lowering of Metal-Graphene Contacts in Top-Gated Graphene Field-Effect Transistors

    PubMed Central

    Mao, Ling-Feng; Ning, Huansheng; Huo, Zong-Liang; Wang, Jin-Yan

    2015-01-01

    A new physical model of the gate controlled Schottky barrier height (SBH) lowering in top-gated graphene field-effect transistors (GFETs) under saturation bias condition is proposed based on the energy conservation equation with the balance assumption. The theoretical prediction of the SBH lowering agrees well with the experimental data reported in literatures. The reduction of the SBH increases with the increasing of gate voltage and relative dielectric constant of the gate oxide, while it decreases with the increasing of oxide thickness, channel length and acceptor density. The magnitude of the reduction is slightly enhanced under high drain voltage. Moreover, it is found that the gate oxide materials with large relative dielectric constant (>20) have a significant effect on the gate controlled SBH lowering, implying that the energy relaxation of channel electrons should be taken into account for modeling SBH in GFETs. PMID:26674338

  7. Meta-gated channel for the discrete control of electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Yang, Rui; Wang, Hui; Shi, Ayuan; Zhang, Aofang; Wang, Jing; Gao, Dongxing; Lei, Zhenya; Hu, Bowei

    2016-08-01

    We demonstrate the meta-gate controlled wave propagation through multiple metallic plates with properly devised sub-wavelength defect apertures. Different from using gradient refractive-index meta-materials or phase-discontinuity meta-surfaces to produce the discrepancy between the incident angle and the refractive angle, our technique redirects electromagnetic fields by setting-up discrete transmission gateways between adjacent meta-gates and creates the perfect channels for the wave propagation. Electromagnetic fields can be assigned in the response of the driving frequency of meta-gates with extraordinary transmissions and propagate simply relying on their pre-set locations as illustrated by the meta-gate guided electromagnetic fields travelling in the paths of the Silk-Road and the contour line of Xi'an city where the Silk-Road starts. The meta-gate concept, offering the feasibility of the discrete control of electromagnetic fields with gating routes, may pave an alternative way for precisely transmitting of signals and efficiently sharing of resource in the communication.

  8. A carbon nanotube field effect transistor with a suspended nanotube gate.

    PubMed

    Tarakanov, Yury A; Kinaret, Jari M

    2007-08-01

    We investigate theoretically field effect transistors based on single-walled carbon nanotubes (CNTFET) and explore two device geometries with suspended multiwalled carbon nanotubes (MWNT) functioning as gate electrodes. In the two geometries, a doubly or singly clamped MWNT is electrostatically deflected toward the transistor channel, allowing for a variable gate coupling and leading to, for instance, a superior subthreshold slope. We suggest that the proposed designs can be used as nanoelectromechanical switches and as detectors of mechanical motion on the nanoscale.

  9. Gate-induced carrier delocalization in quantum dot field effect transistors.

    PubMed

    Turk, Michael E; Choi, Ji-Hyuk; Oh, Soong Ju; Fafarman, Aaron T; Diroll, Benjamin T; Murray, Christopher B; Kagan, Cherie R; Kikkawa, James M

    2014-10-08

    We study gate-controlled, low-temperature resistance and magnetotransport in indium-doped CdSe quantum dot field effect transistors. We show that using the gate to accumulate electrons in the quantum dot channel increases the "localization product" (localization length times dielectric constant) describing transport at the Fermi level, as expected for Fermi level changes near a mobility edge. Our measurements suggest that the localization length increases to significantly greater than the quantum dot diameter.

  10. Field Programmable Gate Array Control of Power Systems in Graduate Student Laboratories

    DTIC Science & Technology

    2008-03-01

    Transistor kHz Kilohertz LUT Lookup Table LPF Lowpass Filter NPS Naval Postgraduate School OPAMP Operational Amplifier PCB Printed Circuit...VSC employing three parallel-connected half- bridges with an Insulated Gate Bipolar Transistor (IGBT) diode brake for protection; a MEMECTM Virtex-4...T 2 0 T 2 2 T 2 1 T 2 1 T 2 2 T Sector II Sector I pnn pnn ppn ppn ppp nnn nnn npn npn ppn ppn ppp nnn nnn 4 0 T 4 0 T 2 0 T 2 1 T 2 2 T 2 2 T 2 1 T 4

  11. Self-Aligned ALD AlOx T-gate Insulator for Gate Leakage Current Suppression in SiNx-Passivated AlGaN/GaN HEMTs

    DTIC Science & Technology

    2010-01-01

    blanket-deposited between the source and drain, as has been demonstrated by Ye et al. [21]. Similiarly, Saadat and co-workers have used ALD-deposited HfOx...been reported previously by Saadat et al. [22] and noted to be indicative of slow trapping centers in the oxide and at the oxide/semiconductor...gate dielectric. Appl Phys Lett 2005;86:063501–3. [22] Saadat OI, Chung JW, Piner EL, Palacios T. Gate-first AlGaN/GaN HEMT technology for high-frequency

  12. Thirty-Day-Long Data Retention in Ferroelectric-Gate Field-Effect Transistors with HfO2 Buffer Layers

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazuhiro; Aizawa, Koji; Park, Byung-Eun; Ishiwara, Hiroshi

    2005-08-01

    Metal-ferroelectric-insulator-semiconductor (MFIS) diodes and p-channel MFIS field-effect transistors (FETs) were fabricated and their electrical properties were characterized. These MFIS structures were formed using HfO2 as an insulating buffer layer, and SrBi2Ta2O9 (SBT) and (Bi,La)4Ti3O12 (BLT) as ferroelectric films. HfO2 buffer layers of about 8 nm physical thickness were deposited by ultrahigh-vacuum (UHV) electron-beam evaporation, then ferroelectric films of about 400 nm thickness were deposited by sol-gel spin coating. The fabricated p-channel MFIS-FETs with the SBT/HfO2 gate structure exhibited a drain current on/off ratio larger than 103 even after 30 days had elapsed. It was also found that the degradation of ferroelectricity was not pronounced even after applying 2.2× 1011 bipolar pulses.

  13. Tuning phase transitions in FeSe thin flakes by field-effect transistor with solid ion conductor as the gate dielectric

    NASA Astrophysics Data System (ADS)

    Lei, B.; Wang, N. Z.; Shang, C.; Meng, F. B.; Ma, L. K.; Luo, X. G.; Wu, T.; Sun, Z.; Wang, Y.; Jiang, Z.; Mao, B. H.; Liu, Z.; Yu, Y. J.; Zhang, Y. B.; Chen, X. H.

    2017-01-01

    We have developed a field-effect transistor (FET) device using a solid ion conductor (SIC) as the gate dielectric, which can tune the carrier density of FeSe by driving lithium ions in and out of the FeSe thin flakes and consequently control the physical properties and phase transitions. A dome-shaped superconducting phase diagram was mapped out with increasing Li content, with Tc˜46.6 K for optimal doping, and an insulating phase was reached at the extremely overdoped regime. Our study suggests that, by using a solid ion conductor as the gate dielectric, the SIC-FET device is able to induce much higher carrier doping in the bulk, suit many surface-sensitive experimental probes, and stabilize structural phases that are inaccessible in ordinary conditions.

  14. Field programmable gate arrays: Evaluation report for space-flight application

    NASA Technical Reports Server (NTRS)

    Sandoe, Mike; Davarpanah, Mike; Soliman, Kamal; Suszko, Steven; Mackey, Susan

    1992-01-01

    Field Programmable Gate Arrays commonly called FPGA's are the newer generation of field programmable devices and offer more flexibility in the logic modules they incorporate and in how they are interconnected. The flexibility, the number of logic building blocks available, and the high gate densities achievable are why users find FPGA's attractive. These attributes are important in reducing product development costs and shortening the development cycle. The aerospace community is interested in incorporating this new generation of field programmable technology in space applications. To this end, a consortium was formed to evaluate the quality, reliability, and radiation performance of FPGA's. This report presents the test results on FPGA parts provided by ACTEL Corporation.

  15. 100-nm-size ferroelectric-gate field-effect transistor with 108-cycle endurance

    NASA Astrophysics Data System (ADS)

    Van Hai, Le; Takahashi, Mitsue; Zhang, Wei; Sakai, Shigeki

    2015-08-01

    The fabrication process of 100-nm-size ferroelectric-gate field-effect transistors (FeFETs) with high endurance was reported. The FeFETs had Pt/Sr0.8Ca0.2Bi2Ta2O9 (SCBT)/HfO2/Si stacks where the Pt gate length was 100 nm. The FeFETs were successfully fabricated by integrating many technologies such as fine patterning of etching masks by electron-beam lithography, precise anisotropic etching of the gate stacks, well-controlled ion implantation for gate-self-aligned sources and drains, and the sidewall-cover process that we had developed. Good performances of the FeFETs were characterized by the endurance of 108 program-and-erase cycles with negligible threshold-voltage shift and good drain-current retention for 3.98 × 105 s.

  16. Field-Driven Mott Gap Collapse and Resistive Switch in Correlated Insulators

    NASA Astrophysics Data System (ADS)

    Mazza, G.; Amaricci, A.; Capone, M.; Fabrizio, M.

    2016-10-01

    Mott insulators are "unsuccessful metals" in which Coulomb repulsion prevents charge conduction despite a metal-like concentration of conduction electrons. The possibility to unlock the frozen carriers with an electric field offers tantalizing prospects of realizing new Mott-based microelectronic devices. Here we unveil how such unlocking happens in a simple model that shows the coexistence of a stable Mott insulator and a metastable metal. Considering a slab subject to a linear potential drop, we find, by means of the dynamical mean-field theory, that the electric breakdown of the Mott insulator occurs via a first-order insulator-to-metal transition characterized by an abrupt gap collapse in sharp contrast to the standard Zener breakdown. The switch on of conduction is due to the field-driven stabilization of the metastable metallic phase. Outside the region of insulator-metal coexistence, the electric breakdown occurs through a more conventional quantum tunneling across the Hubbard bands tilted by the field. Our findings rationalize recent experimental observations and may offer a guideline for future technological research.

  17. Additional-Body Effects in a Self-Aligned Deca-Nanometer Ultrathin-Body and Buried Oxide Silicon-on-Insulator Metal-Oxide-Semiconductor Field-Effect Transistor: A Three-Dimensional Simulation Study

    NASA Astrophysics Data System (ADS)

    Lin, Jyi-Tsong; Eng, Yi-Chuen; Chen, Cheng-Hsin; Fan, Yi-Hsuan

    2011-11-01

    In this paper, we numerically investigate the additional-body effects (ABEs) created by the isolation-last fabrication process of a self-aligned deca-nanometer ultrathin-body and buried oxide (UTBB) silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistor (MOSFET). The reasons for the device's new electrical characteristics are also explained in detail. The additional silicon body volumes of the UTBB SOI MOSFET are found to improve the subthreshold swing and the on/off current ratio. The additional body has a negative effect, however, upon both the gate leakage current and the total gate capacitance, when compared with a standard UTBB SOI MOSFET.

  18. Field-Induced Reversible Phase Manipulation in Metal-Insulator Transition using Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Park, Se Jun

    2005-03-01

    Reversible electronic switching between insulating and metallic phases is a novel idea that may allow new types of field effect devices feasible.^1 Here we demonstrate the reversible manipulation between metallic and insulating phases in two-dimensional In nanowire arrays on Si(111) surface near the metal-insulator transition temperature (Tc). The electronic switching of phases was induced by local electric field applied by the probe tip of a scanning tunneling microscope. The field-dependent hysteresis behavior was also observed in tip height measurements as a function of the sample bias, under the constraint of constant tunneling current. A model including the intrinsic bi-stability of the nanometer-scale domains of In nanowire arrays will be discussed. ^1C. Ahn, J. Triscone, J. Mannhart, Nature 6952, 1015 (2003)

  19. Field evaporation of insulators and semiconductors: Theoretical insights for ZnO.

    PubMed

    Karahka, Markus; Kreuzer, H J

    2015-12-01

    We look at the new challenges associated with Atom Probe Tomography of insulators and semiconductors with regard to local fields inside and on the surface of such materials. The theoretical discovery that in high fields the band gap in these materials is drastically reduced to the point where at the evaporation field strength it vanishes will be crucial in our discussion. To understand Atom Probe results on the field evaporation of insulators and semiconductors we use density functional theory on ZnO clusters to follow the structural and electronic changes during field evaporation and to obtain potential energy curves, HOMO-LUMO gaps, field distributions, desorption pathways and fragments, dielectric constants, and polarizabilities. We also examine the effects of electric field reversal on the evaporation of ZnO and compare the results with Si.

  20. Enhancement of Dimension Uniformity of Wet-Etched Thick Insulator Holes in Triode Carbon Nanotube Field-Emission Display Devices

    NASA Astrophysics Data System (ADS)

    Wei, Hsiao-Fen; Hsiue, Ging-Ho; Liu, Chin-Yh; Chen, Kuo-Feng

    2008-12-01

    A triode structure carbon nanotube field-emission display was fabricated using the thick-film process. The critical dimensional uniformity of wet-etched thick insulator holes was enhanced by changing the wet etching mechanism from vertical dip-etching to horizontal spray-etching. The profile of the insulator holes fabricated using the new etcher was similar to anisotropic. After optimizing the operation conditions of the new etcher, the dimensional uniformity of the insulator holes increased to 97.7%. The optimal concentration of etchant was 2.2 wt % for achieving the least side etching of the insulator holes. The carbon nanotube paste was pattern-printed into the insulator holes. The uniform size of the insulator holes implied that the carbon nanotube distribution was similarly among the insulator holes. This result showed an improved uniform field emission image over the panel from 59 to 83.85%.

  1. Large field-of-view range-gated laser imaging based on image fusion

    NASA Astrophysics Data System (ADS)

    Ren, Pengdao; Wang, Xinwei; Sun, Liang; You, Ruirong; Lei, Pingshun; Zhou, Yan

    2016-11-01

    Laser range-gated imaging has great potentials in remote night surveillance with far detection distance and high resolution, even if under bad weather conditions such as fog, snow and rain. However, the field of view (FOV) is smaller than large objects like buildings, towers and mountains, thus only parts of targets are observed in one single frame, so that it is difficult for targets identification. Apparently, large FOV is beneficial to solve the problem, but the detection range is not available due to low illumination density in a large field of illumination matching with the FOV. Therefore, a large field-of-view range-gated laser imaging is proposed based on image fusion in this paper. Especially an image fusion algorithm has been developed for low contrast images. First of all, an infrared laser range-gated system is established to acquire gate images with small FOV for three different scenarios at night. Then the proposed image fusion algorithm is used for generating panoramas for the three groups of images respectively. Compared with raw images directly obtained by the imaging system, the fused images have a larger FOV with more detail target information. The experimental results demonstrate that the proposed image fusion algorithm is effective to expand the FOV of range-gated imaging.

  2. Strain Gated Bilayer Molybdenum Disulfide Field Effect Transistor with Edge Contacts.

    PubMed

    Chai, Yu; Su, Shanshan; Yan, Dong; Ozkan, Mihrimah; Lake, Roger; Ozkan, Cengiz S

    2017-02-10

    Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS2 (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS2 field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area. Helium plasma etched MoS2 layers for edge contacts. Current on/off ratio and other performance metrics are measured and compared as the FETs evolve from back-gated, to top-gated and finally, to strain-gated configurations. While the indirect band gap of bilayer MoS2 at 0% strain is 1.25 eV, the band gap decreases as the tensile strain increases on an average of ~100 meV per 1% tensile strain, and the decrease in band gap is mainly due to lowering the conduction band at K point. Comparing top- and strain-gated structures, we find a 58% increase in electron mobility and 46% increase in on-current magnitude, signalling a benign effect of tensile strain on the carrier transport properties of MoS2.

  3. Metal-Ferroelectric-Semiconductor Field-Effect Transistor NAND Gate Switching Time Analysis

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; Macleod, Todd C.; Ho, Fat D.

    2006-01-01

    Previous research investigated the modeling of a N Wga te constructed of Metal-Ferroelectric- Semiconductor Field-Effect Transistors (MFSFETs) to obtain voltage transfer curves. The NAND gate was modeled using n-channel MFSFETs with positive polarization for the standard CMOS n-channel transistors and n-channel MFSFETs with negative polarization for the standard CMOS p-channel transistors. This paper investigates the MFSFET NAND gate switching time propagation delay, which is one of the other important parameters required to characterize the performance of a logic gate. Initially, the switching time of an inverter circuit was analyzed. The low-to-high and high-to-low propagation time delays were calculated. During the low-to-high transition, the negatively polarized transistor pulls up the output voltage, and during the high-to-low transition, the positively polarized transistor pulls down the output voltage. The MFSFETs were simulated by using a previously developed model which utilized a partitioned ferroelectric layer. Then the switching time of a 2-input NAND gate was analyzed similarly to the inverter gate. Extension of this technique to more complicated logic gates using MFSFETs will be studied.

  4. Modeling of a Metal-Ferroelectric-Semiconductor Field-Effect Transistor NAND Gate

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; MacLeod, Todd C.; Ho, Fat Duen

    2005-01-01

    Considerable research has been performed by several organizations in the use of the Metal- Ferroelectric-Semiconductor Field-Effect Transistors (MFSFET) in memory circuits. However, research has been limited in expanding the use of the MFSFET to other electronic circuits. This research project investigates the modeling of a NAND gate constructed from MFSFETs. The NAND gate is one of the fundamental building blocks of digital electronic circuits. The first step in forming a NAND gate is to develop an inverter circuit. The inverter circuit was modeled similar to a standard CMOS inverter. A n-channel MFSFET with positive polarization was used for the n-channel transistor, and a n-channel MFSFET with negative polarization was used for the p-channel transistor. The MFSFETs were simulated by using a previously developed current model which utilized a partitioned ferroelectric layer. The inverter voltage transfer curve was obtained over a standard input of zero to five volts. Then a 2-input NAND gate was modeled similar to the inverter circuit. Voltage transfer curves were obtained for the NAND gate for various configurations of input voltages. The resultant data shows that it is feasible to construct a NAND gate with MFSFET transistors.

  5. Strain Gated Bilayer Molybdenum Disulfide Field Effect Transistor with Edge Contacts

    NASA Astrophysics Data System (ADS)

    Chai, Yu; Su, Shanshan; Yan, Dong; Ozkan, Mihrimah; Lake, Roger; Ozkan, Cengiz S.

    2017-02-01

    Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS2 (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS2 field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area. Helium plasma etched MoS2 layers for edge contacts. Current on/off ratio and other performance metrics are measured and compared as the FETs evolve from back-gated, to top-gated and finally, to strain-gated configurations. While the indirect band gap of bilayer MoS2 at 0% strain is 1.25 eV, the band gap decreases as the tensile strain increases on an average of ~100 meV per 1% tensile strain, and the decrease in band gap is mainly due to lowering the conduction band at K point. Comparing top- and strain-gated structures, we find a 58% increase in electron mobility and 46% increase in on-current magnitude, signalling a benign effect of tensile strain on the carrier transport properties of MoS2.

  6. Strain Gated Bilayer Molybdenum Disulfide Field Effect Transistor with Edge Contacts

    PubMed Central

    Chai, Yu; Su, Shanshan; Yan, Dong; Ozkan, Mihrimah; Lake, Roger; Ozkan, Cengiz S.

    2017-01-01

    Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS2 (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS2 field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area. Helium plasma etched MoS2 layers for edge contacts. Current on/off ratio and other performance metrics are measured and compared as the FETs evolve from back-gated, to top-gated and finally, to strain-gated configurations. While the indirect band gap of bilayer MoS2 at 0% strain is 1.25 eV, the band gap decreases as the tensile strain increases on an average of ~100 meV per 1% tensile strain, and the decrease in band gap is mainly due to lowering the conduction band at K point. Comparing top- and strain-gated structures, we find a 58% increase in electron mobility and 46% increase in on-current magnitude, signalling a benign effect of tensile strain on the carrier transport properties of MoS2. PMID:28186113

  7. Interplay between Rashba interaction and electromagnetic field in the edge states of a two-dimensional topological insulator

    NASA Astrophysics Data System (ADS)

    Dolcini, Fabrizio

    2017-02-01

    The effects of Rashba interaction and electromagnetic field on the edge states of a two-dimensional topological insulator are investigated in a nonperturbative way. We show that the electron dynamics is equivalent to a problem of massless Dirac fermions propagating with an inhomogeneous velocity, enhanced by the Rashba profile with respect to the bare Fermi value vF. Despite the inelastic and time-reversal breaking processes induced by the electromagnetic field, no backscattering occurs without interaction. The photoexcited electron densities are explicitly obtained in terms of the electric field and the Rashba interaction, and are shown to fulfill generalized chiral anomaly equations. The case of a Gaussian electromagnetic pulse is analyzed in detail. When the photoexcitation occurs far from the Rashba region, the latter effectively acts as a "superluminal gate" boosting the photoexcited wave packet outside the light-cone determined by vF. In contrast, for an electric pulse overlapping the Rashba region, the emerging wave packets are squeezed in a manner that depends on the overlap area. The electron-electron interaction effects are also discussed, for both intraspin and interspin density-density coupling. The results suggest that Rashba interaction, often considered as an unwanted disorder effect, may be exploited to tailor the shape and the propagation time of photoexcited spin-polarized wave packets.

  8. A hydrogel capsule as gate dielectric in flexible organic field-effect transistors

    SciTech Connect

    Dumitru, L. M.; Manoli, K.; Magliulo, M.; Torsi, L.; Ligonzo, T.; Palazzo, G.

    2015-01-01

    A jellified alginate based capsule serves as biocompatible and biodegradable electrolyte system to gate an organic field-effect transistor fabricated on a flexible substrate. Such a system allows operating thiophene based polymer transistors below 0.5 V through an electrical double layer formed across an ion-permeable polymeric electrolyte. Moreover, biological macro-molecules such as glucose-oxidase and streptavidin can enter into the gating capsules that serve also as delivery system. An enzymatic bio-reaction is shown to take place in the capsule and preliminary results on the measurement of the electronic responses promise for low-cost, low-power, flexible electronic bio-sensing applications using capsule-gated organic field-effect transistors.

  9. Influence of the charge trap density distribution in a gate insulator on the positive-bias stress instability of amorphous indium-gallium-zinc oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Eungtaek; Kim, Choong-Ki; Lee, Myung Keun; Bang, Tewook; Choi, Yang-Kyu; Park, Sang-Hee Ko; Choi, Kyung Cheol

    2016-05-01

    We investigated the positive-bias stress (PBS) instability of thin film transistors (TFTs) composed of different types of first-gate insulators, which serve as a protection layer of the active surface. Two different deposition methods, i.e., the thermal atomic layer deposition (THALD) and plasma-enhanced ALD (PEALD) of Al2O3, were applied for the deposition of the first GI. When THALD was used to deposit the GI, amorphous indium-gallium-zinc oxide (a-IGZO) TFTs showed superior stability characteristics under PBS. For example, the threshold voltage shift (ΔVth) was 0 V even after a PBS time (tstress) of 3000 s under a gate voltage (VG) condition of 5 V (with an electrical field of 1.25 MV/cm). On the other hand, when the first GI was deposited by PEALD, the ΔVth value of a-IGZO TFTs was 0.82 V after undergoing an identical amount of PBS. In order to interpret the disparate ΔVth values resulting from PBS quantitatively, the average oxide charge trap density (NT) in the GI and its spatial distribution were investigated through low-frequency noise characterizations. A higher NT resulted during in the PEALD type GI than in the THALD case. Specifically, the PEALD process on a-IGZO layer surface led to an increasing trend of NT near the GI/a-IGZO interface compared to bulk GI owing to oxygen plasma damage on the a-IGZO surface.

  10. DNA manipulation by means of insulator-based dielectrophoresis employing direct current electric fields.

    PubMed

    Gallo-Villanueva, Roberto C; Rodríguez-López, Carlos E; Díaz-de-la-Garza, Rocío I; Reyes-Betanzo, Claudia; Lapizco-Encinas, Blanca H

    2009-12-01

    Electrokinetic techniques offer a great potential for biological particle manipulation. Among these, dielectrophoresis (DEP) has been successfully utilized for the concentration of bioparticles. Traditionally, DEP is performed employing microelectrodes, an approach with attractive characteristics but expensive due to microelectrode fabrication costs. An alternative is insulator-based DEP, a method where non-uniform electric fields are created with arrays of insulating structures. This study presents the concentration of linear DNA particles (pET28b) employing a microchannel, with an array of cylindrical insulating structures and direct current electric fields. Results showed manipulation of DNA particles with a combination of electroosmotic, electrophoretic, and dielectrophoretic forces. Employing suspending media with conductivity of 104 muS/cm and pH of 11.15, under applied fields between 500 and 1500 V/cm, DNA particles were observed to be immobilized due to negative dielectrophoretic trapping. The observation of DNA aggregates that occurred at higher applied fields, and dispersed once the field was removed is also included. Finally, concentration factors varying from 8 to 24 times the feed concentration were measured at 2000 V/cm after concentration time-periods of 20-40 s. The results presented here demonstrate the potential of insulator-based DEP for DNA concentration, and open the possibility for fast DNA manipulation for laboratory and large-scale applications.

  11. Utilizing self-assembled-monolayer-based gate dielectrics to fabricate molybdenum disulfide field-effect transistors

    SciTech Connect

    Kawanago, Takamasa Oda, Shunri

    2016-01-25

    In this study, we apply self-assembled-monolayer (SAM)-based gate dielectrics to the fabrication of molybdenum disulfide (MoS{sub 2}) field-effect transistors. A simple fabrication process involving the selective formation of a SAM on metal oxides in conjunction with the dry transfer of MoS{sub 2} flakes was established. A subthreshold slope (SS) of 69 mV/dec and no hysteresis were demonstrated with the ultrathin SAM-based gate dielectrics accompanied by a low gate leakage current. The small SS and no hysteresis indicate the superior interfacial properties of the MoS{sub 2}/SAM structure. Cross-sectional transmission electron microscopy revealed a sharp and abrupt interface of the MoS{sub 2}/SAM structure. The SAM-based gate dielectrics are found to be applicable to the fabrication of low-voltage MoS{sub 2} field-effect transistors and can also be extended to various layered semiconductor materials. This study opens up intriguing possibilities of SAM-based gate dielectrics in functional electronic devices.

  12. Electric Field-Induced Skyrmion Crystals via Charged Monopoles in Insulating Helimagets

    NASA Astrophysics Data System (ADS)

    Watanabe, Haruki; Vishwanath, Ashvin

    2016-06-01

    Electrons propagating in a magnetically ordered medium experience an additional gauge field associated with the Berry phase of their spin following the local magnetic texture. In contrast to the usual electromagnetic field, this gauge field admits monopole excitations, corresponding to hedgehog defects of the magnetic order. In an insulator, these hedgehogs carry a well-defined electric charge allowing for them to be controlled by electric fields. One particularly robust mechanism that contributes to the charge is the orbital magnetoelectric effect, captured by a θ angle, which leads to a charge of eθ/2π on hedgehogs. This is a direct consequence of the Witten effect for magnetic monopoles in a θ medium. A physical consequence is that external electric fields can induce skyrmion crystal phases in insulating helimagnets.

  13. Terahertz-field-induced insulator-to-metal transition in vanadium dioxide metamaterial.

    PubMed

    Liu, Mengkun; Hwang, Harold Y; Tao, Hu; Strikwerda, Andrew C; Fan, Kebin; Keiser, George R; Sternbach, Aaron J; West, Kevin G; Kittiwatanakul, Salinporn; Lu, Jiwei; Wolf, Stuart A; Omenetto, Fiorenzo G; Zhang, Xin; Nelson, Keith A; Averitt, Richard D

    2012-07-19

    Electron-electron interactions can render an otherwise conducting material insulating, with the insulator-metal phase transition in correlated-electron materials being the canonical macroscopic manifestation of the competition between charge-carrier itinerancy and localization. The transition can arise from underlying microscopic interactions among the charge, lattice, orbital and spin degrees of freedom, the complexity of which leads to multiple phase-transition pathways. For example, in many transition metal oxides, the insulator-metal transition has been achieved with external stimuli, including temperature, light, electric field, mechanical strain or magnetic field. Vanadium dioxide is particularly intriguing because both the lattice and on-site Coulomb repulsion contribute to the insulator-to-metal transition at 340 K (ref. 8). Thus, although the precise microscopic origin of the phase transition remains elusive, vanadium dioxide serves as a testbed for correlated-electron phase-transition dynamics. Here we report the observation of an insulator-metal transition in vanadium dioxide induced by a terahertz electric field. This is achieved using metamaterial-enhanced picosecond, high-field terahertz pulses to reduce the Coulomb-induced potential barrier for carrier transport. A nonlinear metamaterial response is observed through the phase transition, demonstrating that high-field terahertz pulses provide alternative pathways to induce collective electronic and structural rearrangements. The metamaterial resonators play a dual role, providing sub-wavelength field enhancement that locally drives the nonlinear response, and global sensitivity to the local changes, thereby enabling macroscopic observation of the dynamics. This methodology provides a powerful platform to investigate low-energy dynamics in condensed matter and, further, demonstrates that integration of metamaterials with complex matter is a viable pathway to realize functional nonlinear

  14. Modeling SiO2 Ion Impurities Aging in Insulated Gate Power Devices Under Temperature and Voltage Stress

    DTIC Science & Technology

    2010-10-01

    parasitic capacitance over time. Figure 7 shows the model of the power MOSFET with the relevant parasitic elements during switch on process. The (a...implies that for the same S:  0 )(1 x o ox So G d K V   (8) Finally, computing the capacitance for a nonideal MOSFET /IGBT os to... MOSFETs and IGBTs have similar gate structure as describe earlier, the gate parasitic capacitance , that has been modeled and tested, would have similar

  15. Ferroelectric/Dielectric Double Gate Insulator Spin-Coated Using Barium Titanate Nanocrystals for an Indium Oxide Nanocrystal-Based Thin-Film Transistor.

    PubMed

    Pham, Hien Thu; Yang, Jin Ho; Lee, Don-Sung; Lee, Byoung Hun; Jeong, Hyun-Dam

    2016-03-23

    Barium titanate nanocrystals (BT NCs) were prepared under solvothermal conditions at 200 °C for 24 h. The shape of the BT NCs was tuned from nanodot to nanocube upon changing the polarity of the alcohol solvent, varying the nanosize in the range of 14-22 nm. Oleic acid-passivated NCs showed good solubility in a nonpolar solvent. The effect of size and shape of the BT NCs on the ferroelectric properties was also studied. The maximum polarization value of 7.2 μC/cm(2) was obtained for the BT-5 NC thin film. Dielectric measurements of the films showed comparable dielectric constant values of BT NCs over 1-100 kHz without significant loss. Furthermore, the bottom gate In2O3 NC thin film transistors exhibited outstanding device performance with a field-effect mobility of 11.1 cm(2) V(-1) s(-1) at a low applied gate voltage with BT-5 NC/SiO2 as the gate dielectric. The low-density trapped state was observed at the interface between the In2O3 NC semiconductor and the BT-5 NCs/SiO2 dielectric film. Furthermore, compensation of the applied gate field by an electric dipole-induced dipole field within the BT-5 NC film was also observed.

  16. Systems and methods for detecting a failure event in a field programmable gate array

    NASA Technical Reports Server (NTRS)

    Ng, Tak-Kwong (Inventor); Herath, Jeffrey A. (Inventor)

    2009-01-01

    An embodiment generally relates to a method of self-detecting an error in a field programmable gate array (FPGA). The method includes writing a signature value into a signature memory in the FPGA and determining a conclusion of a configuration refresh operation in the FPGA. The method also includes reading an outcome value from the signature memory.

  17. Electrolyte-gated organic field-effect transistor for selective reversible ion detection.

    PubMed

    Schmoltner, Kerstin; Kofler, Johannes; Klug, Andreas; List-Kratochvil, Emil J W

    2013-12-17

    An ion-sensitive electrolyte-gated organic field-effect transistor for selective and reversible detection of sodium (Na(+) ) down to 10(-6) M is presented. The inherent low voltage - high current operation of these transistors in combination with a state-of-the-art ion-selective membrane proves to be a novel, versatile modular sensor platform.

  18. Measurement of transverse emittance and coherence of double-gate field emitter array cathodes.

    PubMed

    Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R J Dwayne

    2016-12-23

    Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence.

  19. Photon-number discrimination using a semiconductor quantum dot, optically gated, field-effect transistor

    NASA Astrophysics Data System (ADS)

    Gansen, Eric J.; Rowe, Mary A.; Greene, Marion B.; Rosenberg, Danna; Harvey, Todd E.; Su, Mark Y.; Nam, Sae Woo; Mirin, Richard P.

    2007-09-01

    We demonstrate photon-number discrimination using a novel semiconductor detector that utilizes a layer of self-assembled InGaAs quantum dots (QDs) as an optically addressable floating gate in a GaAs/AlGaAs δ-doped field-effect transistor. When the QDOGFET (quantum dot, optically gated, field-effect transistor) is illuminated, the internal gate field directs the holes generated in the dedicated absorption layer of the structure to the QDs, where they are trapped. The positively charged holes are confined to the dots and screen the internal gate field, causing a persistent change in the channel current that is proportional to the total number of holes trapped in the QD ensemble. We use highly attenuated laser pulses to characterize the response of the QDOGFET cooled to 4 K. We demonstrate that different photon-number states produce well resolved changes in the channel current, where the responses of the detector reflect the Poisson statistics of the laser light. For a mean photon number of 1.1, we show that decision regions can be defined such that the QDOGFET determines the number (0, 1, 2, or >=3) of detected photons with a probability of accuracy >=83 % in a single-shot measurement.

  20. RHrFPGA Radiation-Hardened Re-programmable Field-Programmable Gate Array

    NASA Technical Reports Server (NTRS)

    Sanders, A. B.; LaBel, K. A.; McCabe, J. F.; Gardner, G. A.; Lintz, J.; Ross, C.; Golke, K.; Burns, B.; Carts, M. A.; Kim, H. S.

    2004-01-01

    Viewgraphs on the development of the Radiation-Hardened Re-programmable Field-Programmable Gate Array (RHrFPGA) are presented. The topics include: 1) Radiation Test Suite; 2) Testing Interface; 3) Test Configuration; 4) Facilities; 5) Test Programs; 6) Test Procedure; and 7) Test Results. A summary of heavy ion and proton testing is also included.

  1. An Undergraduate Course and Laboratory in Digital Signal Processing with Field Programmable Gate Arrays

    ERIC Educational Resources Information Center

    Meyer-Base, U.; Vera, A.; Meyer-Base, A.; Pattichis, M. S.; Perry, R. J.

    2010-01-01

    In this paper, an innovative educational approach to introducing undergraduates to both digital signal processing (DSP) and field programmable gate array (FPGA)-based design in a one-semester course and laboratory is described. While both DSP and FPGA-based courses are currently present in different curricula, this integrated approach reduces the…

  2. Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

    PubMed Central

    Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R.J. Dwayne

    2016-01-01

    Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence. PMID:28008918

  3. Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

    NASA Astrophysics Data System (ADS)

    Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R. J. Dwayne

    2016-12-01

    Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence.

  4. O{sub 3}-sourced atomic layer deposition of high quality Al{sub 2}O{sub 3} gate dielectric for normally-off GaN metal-insulator-semiconductor high-electron-mobility transistors

    SciTech Connect

    Huang, Sen; Liu, Xinyu Wei, Ke; Liu, Guoguo; Wang, Xinhua; Sun, Bing; Yang, Xuelin; Shen, Bo; Liu, Cheng; Liu, Shenghou; Hua, Mengyuan; Yang, Shu; Chen, Kevin J.

    2015-01-19

    High quality Al{sub 2}O{sub 3} film grown by atomic layer deposition (ALD), with ozone (O{sub 3}) as oxygen source, is demonstrated for fabrication of normally-off AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs). Significant suppression of Al–O–H and Al–Al bonds in ALD-Al{sub 2}O{sub 3} has been realized by substituting conventional H{sub 2}O source with O{sub 3}. A high dielectric breakdown E-field of 8.5 MV/cm and good TDDB behavior are achieved in a gate dielectric stack consisting of 13-nm O{sub 3}-Al{sub 2}O{sub 3} and 2-nm H{sub 2}O-Al{sub 2}O{sub 3} interfacial layer on recessed GaN. By using this 15-nm gate dielectric and a high-temperature gate-recess technique, the density of positive bulk/interface charges in normally-off AlGaN/GaN MIS-HEMTs is remarkably suppressed to as low as 0.9 × 10{sup 12 }cm{sup −2}, contributing to the realization of normally-off operation with a high threshold voltage of +1.6 V and a low specific ON-resistance R{sub ON,sp} of 0.49 mΩ cm{sup 2}.

  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. Extended-gate organic field-effect transistor for the detection of histamine in water

    NASA Astrophysics Data System (ADS)

    Minamiki, Tsukuru; Minami, Tsuyoshi; Yokoyama, Daisuke; Fukuda, Kenjiro; Kumaki, Daisuke; Tokito, Shizuo

    2015-04-01

    As part of our ongoing research program to develop health care sensors based on organic field-effect transistor (OFET) devices, we have attempted to detect histamine using an extended-gate OFET. Histamine is found in spoiled or decayed fish, and causes foodborne illness known as scombroid food poisoning. The new OFET device possesses an extended gate functionalized by carboxyalkanethiol that can interact with histamine. As a result, we have succeeded in detecting histamine in water through a shift in OFET threshold voltage. This result indicates the potential utility of the designed OFET devices in food freshness sensing.

  7. Characterizing featureless Mott insulating state by quasiparticle interference: A dynamical mean field theory view

    NASA Astrophysics Data System (ADS)

    Mukherjee, Shantanu; Lee, Wei-Cheng

    2015-12-01

    The quasiparticle interferences (QPIs) of the featureless Mott insulators are investigated by a T -matrix formalism implemented with the dynamical mean field theory (T -DMFT). In the Mott insulating state, due to the singularity at zero frequency in the real part of the electron self-energy [Re Σ (ω )˜η /ω ] predicted by DMFT, where η can be considered as the "order parameter" for the Mott insulating state, QPIs are completely washed out at small bias voltages. However, a further analysis shows that Re Σ (ω ) serves as an energy-dependent chemical potential shift. As a result, the effective bias voltage seen by the system is e V'=e V -Re Σ (e V ) , which leads to a critical bias voltage e Vc˜√{η } satisfying e V'=0 if and only if η is nonzero. Consequently, the same QPI patterns produced by the noninteracting Fermi surfaces appear at this critical bias voltage e Vc in the Mott insulating state. We propose that this reentry of noninteracting QPI patterns at e Vc could serve as an experimental signature of the Mott insulating state, and the order parameter can be experimentally measured as η ˜(eVc) 2 .

  8. Design Architecture of field-effect transistor with back gate electrode for biosensor application

    NASA Astrophysics Data System (ADS)

    Fathil, M. F. M.; Arshad, M. K. Md.; Hashim, U.; Ruslinda, A. R.; Gopinath, Subash C. B.; M. Nuzaihan M., N.; Ayub, R. M.; Adzhri, R.; Zaki, M.; Azman, A. H.

    2016-07-01

    This paper presents the preparation method of photolithography chrome mask design used in fabrication process of field-effect transistor with back gate biasing based biosensor. Initially, the chrome masks are designed by studying the process flow of the biosensor fabrication, followed by drawing of the actual chrome mask using the AutoCAD software. The overall width and length of the device is optimized at 16 mm and 16 mm, respectively. Fabrication processes of the biosensor required five chrome masks, which included source and drain formation mask, the back gate area formation mask, electrode formation mask, front gate area formation mask, and passivation area formation mask. The complete chrome masks design will be sent for chrome mask fabrication and for future use in biosensor fabrication.

  9. Design and fabrication of high-performance diamond triple-gate field-effect transistors

    PubMed Central

    Liu, Jiangwei; Ohsato, Hirotaka; Wang, Xi; Liao, Meiyong; Koide, Yasuo

    2016-01-01

    The lack of large-area single-crystal diamond wafers has led us to downscale diamond electronic devices. Here, we design and fabricate a hydrogenated diamond (H-diamond) triple-gate metal-oxide-semiconductor field-effect transistor (MOSFET) to extend device downscaling and increase device output current. The device’s electrical properties are compared with those of planar-type MOSFETs, which are fabricated simultaneously on the same substrate. The triple-gate MOSFET’s output current (174.2 mA mm−1) is much higher than that of the planar-type device (45.2 mA mm−1), and the on/off ratio and subthreshold swing are more than 108 and as low as 110 mV dec−1, respectively. The fabrication of these H-diamond triple-gate MOSFETs will drive diamond electronic device development forward towards practical applications. PMID:27708372

  10. Lateral energy band profile modulation in tunnel field effect transistors based on gate structure engineering

    NASA Astrophysics Data System (ADS)

    Cui, Ning; Liang, Renrong; Wang, Jing; Xu, Jun

    2012-06-01

    Choosing novel materials and structures is important for enhancing the on-state current in tunnel field-effect transistors (TFETs). In this paper, we reveal that the on-state performance of TFETs is mainly determined by the energy band profile of the channel. According to this interpretation, we present a new concept of energy band profile modulation (BPM) achieved with gate structure engineering. It is believed that this approach can be used to suppress the ambipolar effect. Based on this method, a Si TFET device with a symmetrical tri-material-gate (TMG) structure is proposed. Two-dimensional numerical simulations demonstrated that the special band profile in this device can boost on-state performance, and it also suppresses the off-state current induced by the ambipolar effect. These unique advantages are maintained over a wide range of gate lengths and supply voltages. The BPM concept can serve as a guideline for improving the performance of nanoscale TFET devices.

  11. Coupling between electrolyte and organic semiconductor in electrolyte-gated organic field effect transistors (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Biscarini, Fabio; Di Lauro, Michele; Berto, Marcello; Bortolotti, Carlo A.; Geerts, Yves H.; Vuillaume, Dominique

    2016-11-01

    Organic field effect transistors (OFET) operated in aqueous environments are emerging as ultra-sensitive biosensors and transducers of electrical and electrochemical signals from a biological environment. Their applications range from detection of biomarkers in bodily fluids to implants for bidirectional communication with the central nervous system. They can be used in diagnostics, advanced treatments and theranostics. Several OFET layouts have been demonstrated to be effective in aqueous operations, which are distinguished either by their architecture or by the respective mechanism of doping by the ions in the electrolyte solution. In this work we discuss the unification of the seemingly different architectures, such as electrolyte-gated OFET (EGOFET), organic electrochemical transistor (OECT) and dual-gate ion-sensing FET. We first demonstrate that these architectures give rise to the frequency-dependent response of a synapstor (synapse-like transistor), with enhanced or depressed modulation of the output current depending on the frequency of the time-dependent gate voltage. This behavior that was reported for OFETs with embedded metal nanoparticles shows the existence of a capacitive coupling through an equivalent network of RC elements. Upon the systematic change of ions in the electrolyte and the morphology of the charge transport layer, we show how the time scale of the synapstor is changed. We finally show how the substrate plays effectively the role of a second bottom gate, whose potential is actually fixed by the pH/composition of the electrolyte and the gate voltage applied.

  12. Measurement and Analysis of a Ferroelectric Field-Effect Transistor NAND Gate

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; MacLeond, Todd C.; Sayyah, Rana; Ho, Fat Duen

    2009-01-01

    Previous research investigated expanding the use of Ferroelectric Field-Effect Transistors (FFET) to other electronic devices beyond memory circuits. Ferroelectric based transistors possess unique characteris tics that give them interesting and useful properties in digital logic circuits. The NAND gate was chosen for investigation as it is one of the fundamental building blocks of digital electronic circuits. In t his paper, NAND gate circuits were constructed utilizing individual F FETs. N-channel FFETs with positive polarization were used for the standard CMOS NAND gate n-channel transistors and n-channel FFETs with n egative polarization were used for the standard CMOS NAND gate p-chan nel transistors. The voltage transfer curves were obtained for the NA ND gate. Comparisons were made between the actual device data and the previous modeled data. These results are compared to standard MOS logic circuits. The circuits analyzed are not intended to be fully opera tional circuits that would interface with existing logic circuits, bu t as a research tool to look into the possibility of using ferroelectric transistors in future logic circuits. Possible applications for th ese devices are presented, and their potential benefits and drawbacks are discussed.

  13. Normally-off HfO2-gated diamond field effect transistors

    NASA Astrophysics Data System (ADS)

    Liu, J. W.; Liao, M. Y.; Imura, M.; Koide, Y.

    2013-08-01

    A normally-off hydrogenated-diamond (H-diamond) field effect transistor (FET) using a HfO2 gate oxide is demonstrated. The HfO2 gate oxide has a bilayer structure which is fabricated by a sputter-deposition (SD) technique on a thin buffer layer prepared by an atomic layer deposition (ALD) technique. The role of the ALD-HfO2 is found to prevent deterioration of the H-diamond surface by the SD process. The leakage current density of the SD-HfO2/ALD-HfO2/H-diamond structure is smaller than 1.1 × 10-4 A cm-2 at gate voltages from -9.0 to 2.0 V. The capacitance-voltage characteristic shows that fixed and trapped charge densities are low enough to operate the FET. The HfO2-gated FET has p-type channel and complete normally-off characteristics. The drain-source current maximum, threshold voltage, extrinsic transconductance maximum, and effective mobility of the FET with gate length of 4 μm are -37.6 mA mm-1, -1.3 ± 0.1 V, 11.2 ± 0.1 mS mm-1, and 38.7 ± 0.5 cm2 V-1 s-1, respectively.

  14. Graphene field-effect transistor array with integrated electrolytic gates scaled to 200 mm

    NASA Astrophysics Data System (ADS)

    Vieira, N. C. S.; Borme, J.; Machado, G., Jr.; Cerqueira, F.; Freitas, P. P.; Zucolotto, V.; Peres, N. M. R.; Alpuim, P.

    2016-03-01

    Ten years have passed since the beginning of graphene research. In this period we have witnessed breakthroughs both in fundamental and applied research. However, the development of graphene devices for mass production has not yet reached the same level of progress. The architecture of graphene field-effect transistors (FET) has not significantly changed, and the integration of devices at the wafer scale has generally not been sought. Currently, whenever an electrolyte-gated FET (EGFET) is used, an external, cumbersome, out-of-plane gate electrode is required. Here, an alternative architecture for graphene EGFET is presented. In this architecture, source, drain, and gate are in the same plane, eliminating the need for an external gate electrode and the use of an additional reservoir to confine the electrolyte inside the transistor active zone. This planar structure with an integrated gate allows for wafer-scale fabrication of high-performance graphene EGFETs, with carrier mobility up to 1800 cm2 V-1 s-1. As a proof-of principle, a chemical sensor was achieved. It is shown that the sensor can discriminate between saline solutions of different concentrations. The proposed architecture will facilitate the mass production of graphene sensors, materializing the potential of previous achievements in fundamental and applied graphene research.

  15. A compact, short-pulse laser for near-field, range-gated imaging

    SciTech Connect

    Zutavern, F.J.; Helgeson, W.D.; Loubriel, G.M.; Yates, G.J.; Gallegos, R.A.; McDonald, T.E.

    1996-12-31

    This paper describes a compact laser, which produces high power, wide-angle emission for a near-field, range-gated, imaging system. The optical pulses are produced by a 100 element laser diode array (LDA) which is pulsed with a GaAs, photoconductive semiconductor switch (PCSS). The LDA generates 100 ps long, gain-switched, optical pulses at 904 nm when it is driven with 3 ns, 400 A, electrical pulses from a high gain PCSS. Gain switching is facilitated with this many lasers by using a low impedance circuit to drive an array of lasers, which are connected electrically in series. The total optical energy produced per pulse is 10 microjoules corresponding to a total peak power of 100 kW. The entire laser system, including prime power (a nine volt battery), pulse charging, PCSS, and LDA, is the size of a small, hand-held flashlight. System lifetime, which is presently limited by the high gain PCSS, is an active area of research and development. Present limitations and potential improvements will be discussed. The complete range-gated imaging system is based on complementary technologies: high speed optical gating with intensified charge coupled devices (ICCD) developed at Los Alamos National Laboratory (LANL) and high gain, PCSS-driven LDAs developed at Sandia National Laboratories (SNL). The system is designed for use in highly scattering media such as turbid water or extremely dense fog or smoke. The short optical pulses from the laser and high speed gating of the ICCD are synchronized to eliminate the back-scattered light from outside the depth of the field of view (FOV) which may be as short as a few centimeters. A high speed photodiode can be used to trigger the intensifier gate and set the range-gated FOV precisely on the target. The ICCD and other aspects of the imaging system are discussed in a separate paper.

  16. Carbon Nanotube Field Emission Devices With Integrated Gate for High Current Applications

    DTIC Science & Technology

    2008-08-01

    exhibits an edge effect and in fact, shows a slight enhancement. A baseline structure, consisting of two parallel plates with the same applied field and...electrostatics the addition of the gate electrode will not reduce the edge effect for the CNT pillars. As a result of this it is expected that the voltage...field emission from an individual aligned carbon nanotube bundle enhanced by edge effect ", Appl. Phys. Lett., 90, 153108, 2007. [6] Killian, J. L

  17. High fluence swift heavy ion structure modification of the SiO2/Si interface and gate insulator in 65 nm MOSFETs

    NASA Astrophysics Data System (ADS)

    Ma, Yao; Gao, Bo; Gong, Min; Willis, Maureen; Yang, Zhimei; Guan, Mingyue; Li, Yun

    2017-04-01

    In this work, a study of the structure modification, induced by high fluence swift heavy ion radiation, of the SiO2/Si structures and gate oxide interface in commercial 65 nm MOSFETs is performed. A key and novel point in this study is the specific use of the transmission electron microscopy (TEM) technique instead of the conventional atomic force microscope (AFM) or scanning electron microscope (SEM) techniques which are typically performed following the chemical etching of the sample to observe the changes in the structure. Using this method we show that after radiation, the appearance of a clearly visible thin layer between the SiO2 and Si is observed presenting as a variation in the TEM intensity at the interface of the two materials. Through measuring the EDX line scans we reveal that the Si:O ratio changed and that this change can be attributed to the migration of the Si towards interface after the Si-O bond is destroyed by the swift heavy ions. For the 65 nm MOSFET sample, the silicon substrate, the SiON insulator and the poly-silicon gate interfaces become blurred under the same irradiation conditions.

  18. Supplement analysis for Greenville Gate access to Kirschbaum Field at Lawrence Livermore National Laboratory

    SciTech Connect

    1997-12-05

    The National Ignition Facility (NIF) Program proposes to provide additional access to the Kirschbaum Field construction laydown area. This additional access would alleviate traffic congestion at the East Gate entrance to Lawrence Livermore National Laboratory (LLNL) from Greenville Road during periods of heavy construction for the NIF. The new access would be located along the northeastern boundary of LLNL, about 305 m (1,000 ft) north of the East Gate entrance. The access road would extend from Greenville Road to the Kirschbaum Field construction laydown area and would traverse an existing storm water drainage channel. Two culverts, side by side, and a compacted road base would be installed across the channel. The security fence that runs parallel to Greenville Road would be modified to accommodate this new entrance and a vehicle gate would be installed at the entrance of Kirschbaum Field. The exiting shoulder along Greenville Road would be converted into a new turn lane for trucks entering the new gate. This analysis evaluates the impacts of constructing the Kirschbaum Field bridge and access gate at a different location than was analyzed in the NIF Project specific Analysis in the Final Programmatic environmental Impact Statement for Stockpile Stewardship and Management (SS and M PEIS) published in September 1996 (DOE/EIS-0236) and the Record of Decision published on December 19, 1996. Issues of concern addressed in this supplement analysis include potential impacts to wetlands downstream of the access bridge, potential impacts to the California red-legged frog (Rana aurora draytonii) listed as threatened on the federal listing pursuant to the Endangered Species Act of 1974, and potential impacts on the 100-yr floodplain along the Arroyo Las Positas.

  19. Acquisition of He3 Cryostat Insert for Experiments on Topological Insulators

    DTIC Science & Technology

    2016-02-03

    P.O. Box 12211 Research Triangle Park, NC 27709-2211 Cryogenic equipment with 9 Tesla magnet, low temperature experiments REPORT DOCUMENTATION PAGE...facilitated by the cryogenic system are i) In-situ low - temperature tuning of the chemical potential in the topological insulator using ionic liquid gating...situ low - temperature tuning of the chemical potential in the topological insulator using ionic liquid gating. The intense electric field applied

  20. Friability of spray-applied fireproofing and thermal insulations: field evaluation of prototype test devices

    SciTech Connect

    Rossiter, W.J.; Roberts, W.E.; Mathey, R.G.

    1989-03-01

    The report describes results of the third and final phase of a study conducted for the General Services Administration (GSA) to develop a field-test method to measure the friability of spray-applied fireproofing and thermal-insulation materials. Field tests were conducted on 17 fibrous and 2 cementitious spray-applied materials to assess surface and bulk compression/shear, indentation, abrasion, and impact properties. The tests were performed using prototype devices developed in an earlier phase of the study. As expected, the field specimens displayed varying response to dislodgment or indentation in the tests. The field tests confirmed that the goal of the study had been achieved.

  1. Attosecond x-ray source generation from two-color polarized gating plasmonic field enhancement

    SciTech Connect

    Feng, Liqiang; Yuan, Minghu; Chu, Tianshu

    2013-12-15

    The plasmonic field enhancement from the vicinity of metallic nanostructures as well as the polarization gating technique has been utilized to the generation of the high order harmonic and the single attosecond x-ray source. Through numerical solution of the time-dependent Schrödinger equation, for moderate the inhomogeneity and the polarized angle of the two fields, we find that not only the harmonic plateau has been extended and enhanced but also the single short quantum path has been selected to contribute to the harmonic. As a result, a series of 50 as pulses around the extreme ultraviolet and the x-ray regions have been obtained. Furthermore, by investigating the other parameters effects on the harmonic emission, we find that this two-color polarized gating plasmonic field enhancement scheme can also be achieved by the multi-cycle pulses, which is much better for experimental realization.

  2. High-performance ZnO nanowire field-effect transistor with forming gas treated SiO{sub 2} gate dielectrics

    SciTech Connect

    Qian, Haolei; Wang, Yewu E-mail: phyjsha@zju.edu.cn; Fang, Yanjun; Gu, Lin; Lu, Ren; Sha, Jian E-mail: phyjsha@zju.edu.cn

    2015-04-28

    The SiO{sub 2} films thermally grown on Si wafer have been annealed in forming atmosphere (N{sub 2}:H{sub 2} = 9:1) prior to use as gate insulators in ZnO nanowire field effect transistors (ZnO NW-FETs). Without the annealing process, ZnO NW-FETs exhibit very poor performance, and most of them even cannot be depleted under a high gate voltage of −100 V; however, with the annealing process in forming atmosphere, the device characteristics can be significantly improved, exhibiting a large turn on-off ratio of ∼10{sup 4} and a low sub-threshold swing ∼1 V/decade. The pre-annealing treatment of SiO{sub 2} (300 nm)/p-Si in N{sub 2}/H{sub 2} ambient may significantly reduce the number of non-bridging oxygen atoms, which blocks the interaction between ZnO nanowires and SiO{sub 2} surface, and finally enhances the electrical characteristics of the back-gated ZnO NW-FETs. In addition, the FET electrode fabrication process introduced in this paper is much simpler than the traditional photo-lithography and lift-off method, which has potential applications in future device fabrication.

  3. Electric Field-induced Resistance Switching in VO2 Channels using Hybrid Gate Dielectric of High- k Ta2O5/Organic material Parylene-C

    NASA Astrophysics Data System (ADS)

    Wei, Tingting; Kanki, Teruo; Fujiwara, Kohei; Chikanari, Masashi; Tanaka, Hidekazu

    Electrostatic approach utilizing field-effect transistor (FET) with correlated electron materials provides an avenue to realize the novel devices (Mott-transistor) and to clarify condensed matter physics. In this study, we have prepared Mott-transistors using vanadium dioxide (VO2) channels and employed hybrid gate dielectric consisted of high- k material Ta2O5 and organic polymer parylene-C to trigger carrier transport modulation in VO2. Obvious resistance modulations were observed in insulating regime through time-dependent resistance measurement at varied square-shaped gate bias (VG) . Contrasting to the hysteretic response in electric double layer transistor (EDLT), an abrupt resistance switching in less than of 2-second-interval enables us to attribute such immediate modulation to pure electrostatic effect. Moreover, the maximum of resistance change was identified to appear around phase transition temperature (TMI) , which confirmed the disordered heterogeneous regime at TMI. Taking advantage of systematic modulation using VO2-based devices, we demonstrated the pronounced shifts of TMI by gate bias. Another fascinating behavior on asymmetric drop in TMI by hole-electron carrier doping was observed.

  4. Field-effect control of superconductivity and Rashba spin-orbit coupling in top-gated LaAlO3/SrTiO3 devices

    PubMed Central

    Hurand, S.; Jouan, A.; Feuillet-Palma, C.; Singh, G.; Biscaras, J.; Lesne, E.; Reyren, N.; Barthélémy, A.; Bibes, M.; Villegas, J. E.; Ulysse, C.; Lafosse, X.; Pannetier-Lecoeur, M.; Caprara, S.; Grilli, M.; Lesueur, J.; Bergeal, N.

    2015-01-01

    The recent development in the fabrication of artificial oxide heterostructures opens new avenues in the field of quantum materials by enabling the manipulation of the charge, spin and orbital degrees of freedom. In this context, the discovery of two-dimensional electron gases (2-DEGs) at LaAlO3/SrTiO3 interfaces, which exhibit both superconductivity and strong Rashba spin-orbit coupling (SOC), represents a major breakthrough. Here, we report on the realisation of a field-effect LaAlO3/SrTiO3 device, whose physical properties, including superconductivity and SOC, can be tuned over a wide range by a top-gate voltage. We derive a phase diagram, which emphasises a field-effect-induced superconductor-to-insulator quantum phase transition. Magneto-transport measurements show that the Rashba coupling constant increases linearly with the interfacial electric field. Our results pave the way for the realisation of mesoscopic devices, where these two properties can be manipulated on a local scale by means of top-gates. PMID:26244916

  5. Sub-10 nm transparent all-around-gated ambipolar ionic field effect transistor

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Hyun; Lee, Hyomin; Jin, Tianguang; Park, Sungmin; Yoon, Byung Jun; Sung, Gun Yong; Kim, Ki-Bum; Kim, Sung Jae

    2014-12-01

    In this paper, we developed a versatile ionic field effect transistor (IFET) which has an ambipolar function for manipulating molecules regardless of their polarity and can be operated at a wide range of electrolytic concentrations (10-5 M-1 M). The IFET has circular nanochannels radially covered by gate electrodes, called ``all-around-gate'', with an aluminum oxide (Al2O3) oxide layer of a near-zero surface charge. Experimental and numerical validations were conducted for characterizing the IFET. We found that the versatility originated from the zero-charge density of the oxide layer and all-around-gate structure which increased the efficiency of the gate effect 5 times higher than a previously developed planar-gate by capacitance calculations. Our numerical model adapted Poisson-Nernst-Planck-Stokes (PNPS) formulations with additional nonlinear constraints of a fringing field effect and a counter-ion condensation and the experimental and numerical results were well matched. The device can control the transportation of ions at concentrations up to 1 M electrolyte which resembles a backflow of a shale gas extraction process. Furthermore, while traditional IFETs can manipulate either positively or negatively charged species depending on the inherently large surface charge of oxide layer, the presenting device and mechanism provide effective means to control the motion of both negatively and positively charged molecules which is important in biomolecule transport through nanochannels, medical diagnosis system and point-of-care system, etc.In this paper, we developed a versatile ionic field effect transistor (IFET) which has an ambipolar function for manipulating molecules regardless of their polarity and can be operated at a wide range of electrolytic concentrations (10-5 M-1 M). The IFET has circular nanochannels radially covered by gate electrodes, called ``all-around-gate'', with an aluminum oxide (Al2O3) oxide layer of a near-zero surface charge. Experimental and

  6. Photon-number-discriminating detection using a quantum-dot, optically gated, field-effect transistor

    NASA Astrophysics Data System (ADS)

    Gansen, E. J.; Rowe, M. A.; Greene, M. B.; Rosenberg, D.; Harvey, T. E.; Su, M. Y.; Hadfield, R. H.; Nam, S. W.; Mirin, R. P.

    2007-10-01

    Detectors with the capability to directly measure the photon number of a pulse of light enable linear optics quantum computing, affect the security of quantum communications, and can be used to characterize and herald non-classical states of light. Here, we demonstrate the photon-number-resolving capabilities of a quantum-dot, optically gated, field-effect transistor that uses quantum dots as optically addressable floating gates in a GaAs/Al0.2Ga0.8As δ-doped field-effect transistor. When the active area of the detector is illuminated, photo-generated carriers trapped by quantum dots screen the gate field, causing a persistent change in the channel current that is proportional to the number of confined carriers. Using weak laser pulses, we show that discrete numbers of trapped carriers produce well resolved changes in the channel current. We demonstrate that for a mean photon number of 1.1, decision regions can be defined such that the field-effect transistor determines the number of detected photons with a probability of accuracy greater than 83%.

  7. Performance of AlGaN/GaN MISHFET using dual-purpose thin Al2O3 layer for surface protection and gate insulator

    NASA Astrophysics Data System (ADS)

    Kim, Do-Kywn; Sindhuri, V.; Jo, Young-Woo; Kim, Dong-Seok; Kang, Hee-Sung; Lee, Jun-Hyeok; Lee, Yong Soo; Bae, Youngho; Hahm, Sung-Ho; Lee, Jung-Hee

    2014-10-01

    In this work, we have investigated a role of a thin Al2O3 layer in AlGaN/GaN MISHFET by characterizing the variation of the sheet resistance of the 2DEG channel layer. The Al2O3 layer, varying the thickness from 0 to 10 nm, was utilized as the gate insulator of the device as well as the surface protection layer during RTP for ohmic contact formation. After RTP, the 2DEG channel layer without the Al2O3 layer was rapidly degraded by increasing the sheet resistance of the layer to 1360 Ω/□ from the sheet resistance of 400 Ω/□ of the as-grown sample. The degradation was still observed even when 1.5 nm-thick Al2O3 layer was used. However, the sheet resistances of the devices remained constant with slightly decreased value from that of the as-grown sample when the thickness is larger than 3 nm, which indicates that the 3 nm-thick Al2O3 layer well protects the AlGaN surface above the 2DEG channel during RTP. The slight decrease in sheet resistance is probably because some acceptor-like states existing at AlGaN surface become neutralized and hence the 2DEG density increases. The Al2O3 layer was not removed for proceeding the fabrication of AlGaN/GaN MISHFET, but rather used as a gate dielectric, which simplifies the device fabrication eliminating the additional deposition steps for the gate dielectric. The threshold voltage of the device, investigated in this work, was increased to the negative direction with increasing the thickness of Al2O3 layers while the transconductance was decreased. The best performances were obtained from the device with 8 nm-thick Al2O3 layer, exhibiting very low gate leakage current of 10-9 A/mm with subthreshold swing (SS) of 80 mV/dec and very high Ion/Ioff ratio (>9 orders).

  8. Controlled microparticle manipulation employing low frequency alternating electric fields in an array of insulators.

    PubMed

    Baylon-Cardiel, Javier L; Jesús-Pérez, Nadia M; Chávez-Santoscoy, Ana V; Lapizco-Encinas, Blanca H

    2010-12-07

    Low frequency alternating current insulator-based dielectrophoresis is a novel technique that allows for highly controlled manipulation of particles. By varying the shape of an AC voltage applied across a microchannel containing an array of insulating cylindrical structures it was possible to concentrate and immobilize microparticles in bands; and then, move the bands of particles to a different location. Mathematical modeling was performed to analyze the distribution of the electric field and electric field gradient as function of the shape of the AC applied potential, employing frequencies in the 0.2-1.25 Hz range. Three different signals were tested: sinusoidal, half sinusoidal and sawtooth. Experimental results demonstrated that this novel dielectrophoretic mode allows highly controlled particle manipulation.

  9. Chiral magnetism and spin liquid Mott insulators induced by synthetic gauge fields

    NASA Astrophysics Data System (ADS)

    Paramekanti, Arun; Hickey, Ciaran; Cincio, Lukasz; Papic, Zlatko; Vellat-Sadashivan, Arun; Sohal, Ramanjit

    2016-05-01

    Recent experiments using Raman-assisted tunneling or lattice-shaking have realized synthetic gauge fields and optical lattice bands with nontrivial band topology. Here we examine the effect of particle interactions in such bands, focussing on two-component fermions with local Hubbard repulsion. We show that interactions can drive the integer quantum Hall insulator into Mott insulating states which possess noncoplanar chiral magnetic textures and even chiral spin liquids with many-body topological order. We establish our results using a combination of mean field theory, strong coupling expansions, numerical exact diagonalization and DMRG methods. We also discuss possible signatures of such non-coplanar orders in Bragg scattering and noise measurements.

  10. Space charge effects on the current-voltage characteristics of gated field emitter arrays

    NASA Astrophysics Data System (ADS)

    Jensen, K. L.; Kodis, M. A.; Murphy, R. A.; Zaidman, E. G.

    1997-07-01

    Microfabricated field emitter arrays (FEAs) can provide the very high electron current densities required for rf amplifier applications, typically on the order of 100 A/cm2. Determining the dependence of emission current on gate voltage is important for the prediction of emitter performance for device applications. Field emitters use high applied fields to extract current, and therefore, unlike thermionic emitters, the current densities can exceed 103A/cm2 when averaged over an array. At such high current densities, space charge effects (i.e., the influence of charge between cathode and collector on emission) affect the emission process or initiate conditions which can lead to failure mechanisms for field emitters. A simple model of a field emitter will be used to calculate the one-dimensional space charge effects on the emission characteristics by examining two components: charge between the gate and anode, which leads to Child's law, and charge within the FEA unit cell, which gives rise to a field suppression effect which can exist for a single field emitter. The predictions of the analytical model are compared with recent experimental measurements designed to assess space charge effects and predict the onset of gate current. It is shown that negative convexity on a Fowler-Nordheim plot of Ianode(Vgate) data can be explained in terms of field depression at the emitter tip in addition to reflection of electrons by a virtual cathode created when the anode field is insufficient to extract all of the current; in particular, the effects present within the unit cell constitute a newly described effect.

  11. The Effects of ’Normal’ Annealing Cycles During IGFET Fabrication on Initial and Radiation Induced Gate Insulator Defects

    DTIC Science & Technology

    1989-07-13

    indicated that the " extrinsic " defects arc localized near, but not at, the Si/SiO 2 interface. It is shown that if the insulator thi-kness is separated into...three regions; (1) a region above the extrinsic defect volume in whichAVT is linear in t 9 (2) a region containing all of the extrinsic defects in...which CV is quadratic in t , and (3) a region below the extrinsic defect volume close to the S SiO 2 interface in which .V T=0, then theV T vs. t data

  12. Extended Gate Field-Effect Transistor Biosensors for Point-Of-Care Testing of Uric Acid.

    PubMed

    Guan, Weihua; Reed, Mark A

    2017-01-01

    An enzyme-free redox potential sensor using off-chip extended-gate field effect transistor (EGFET) with a ferrocenyl-alkanethiol modified gold electrode has been used to quantify uric acid concentration in human serum and urine. Hexacyanoferrate (II) and (III) ions are used as redox reagent. The potentiometric sensor measures the interface potential on the ferrocene immobilized gold electrode, which is modulated by the redox reaction between uric acid and hexacyanoferrate ions. The device shows a near Nernstian response to uric acid and is highly specific to uric acid in human serum and urine. The interference that comes from glucose, bilirubin, ascorbic acid, and hemoglobin is negligible in the normal concentration range of these interferents. The sensor also exhibits excellent long term reliability and is regenerative. This extended gate field effect transistor based sensor is promising for point-of-care detection of uric acid due to the small size, low cost, and low sample volume consumption.

  13. Ionic-Liquid Gated Bilayer MoS2 Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Madusanka Perera, Meeghage; Chuang, Hsun-Jen; Lin, Ming-Wei; Chamlagain, Bhim; Tan, Xuebin; Ming-Cheng Cheng, Mark; Zhou, Zhixian

    2012-10-01

    We report the electrical characterization of ionic-liquid-gated bilayer MoS2 field-effect transistors. An On-Off current ratio greater than 10^6 is achieved for hole transport, while that for electron transport exceeds 10^8. The subthreshold swing of our bilayer MoS2 devices reaches as low as 47 mV/dec at 230 K, approaching the theoretical limit. We also demonstrate that 1) the extrinsic mobility of back-gated MoS2 field-effect transistors is largely limited by the contact resistance; and 2) the extremely large electrical-double-layer capacitance of ionic liquid significantly reduces the Schottky contact barrier leading up to three orders of magnitude mobility increase for electron transport.

  14. Giant tunable magnetoresistance of electrically gated graphene ribbon with lateral interface under magnetic field

    NASA Astrophysics Data System (ADS)

    Kadigrobov, A. M.

    2017-01-01

    Quantum dynamics and kinetics of electrically gated graphene ribbons with lateral n-p and n-p-n junctions under magnetic field are investigated. It is shown that the snake-like states [C. W. J. Beenakker, Rev. Mod. Phys. 80, 1337 (2008)] of quasiparticles skipping along the n-p interface do not manifest themselves in the main semi-classical part of the ribbon conductance. Giant oscillations of the conductance of a ribbon with an n-p-n junction are predicted and analytically calculated. Depending on the number of junctions inside the ribbon its magneto-resistance may be controllably changed by 50%-90% by an extremely small change of the magnetic field or the gate voltage.

  15. Numerical correction of coherence gate in full-field swept-source interference microscopy.

    PubMed

    Grebenyuk, Anton A; Ryabukho, Vladimir P

    2012-07-01

    A big problem in low-coherence interference microscopy is the degradation of the coherence signal caused by shift of the angular and temporal spectrum gates. It limits the depth of field in confocal optical coherence microscopy and degrades images of sample inner structure in most interference microscopy techniques. To overcome this problem we propose numerical correction of the coherence gate in application to full-field swept-source interference microscopy. The proposed technique allows three-dimensional sample imaging without mechanical movement of the microscope components and is also capable of determining separately the geometrical thickness and the refractive index of the sample layers, when the sample contains a transversal pattern. The applicability of the proposed technique is verified with numerical simulation.

  16. Electron emission properties of gated silicon field emitter arrays driven by laser pulses

    NASA Astrophysics Data System (ADS)

    Shimawaki, Hidetaka; Nagao, Masayoshi; Neo, Yoichiro; Mimura, Hidenori; Wakaya, Fujio; Takai, Mikio

    2016-10-01

    We report optically modulated electron emission from gated p-type silicon field emitter arrays (Si-FEAs). The device's "volcano" structure is designed to control the photoexcitation of electrons by transmitting light through the small gate aperture, thereby minimizing the photogeneration of slow diffusion carriers outside the depletion region in the tip. Compared to that in the dark, the emission current was enhanced by more than three orders of magnitude in the high field region when irradiated with blue laser pulses. Results from the time-resolved measurements of photoassisted electron emission showed that these possess the same response as the laser pulse with no discernible delay. These results indicate that the volcano device structure is effective at eliminating the generation of diffusion carriers and that a fully optimized FEA is promising as a photocathode for producing high-speed modulated electron beams.

  17. Extended-Gate Metal Oxide Semiconductor Field Effect Transistor-Based Biosensor for Detection of Deoxynivalenol

    NASA Astrophysics Data System (ADS)

    Kwon, Insu; Lee, Hee-Ho; Choi, Jinhyeon; Shin, Jang-Kyoo; Seo, Sang-Ho; Choi, Sung-Wook; Chun, Hyang Sook

    2011-06-01

    In this work, we present an extended-gate metal oxide semiconductor field effect transistor (MOSFET)-based biosensor for the detection of deoxynivalenol using a null-balancing circuit. An extended-gate MOSFET-based biosensor was fabricated by a standard complementary metal oxide semiconductor (CMOS) process and its characteristics were measured. A null-balancing circuit was used to measure the output voltage of the sensor directly, instead of measuring the drain current of the sensor. Au was used as the gate metal, which has a chemical affinity with thiol, which leads to the immobilization of a self-assembled monolayer (SAM) of mercaptohexadecanoic acid (MHDA). The SAM was used to immobilize the anti-deoxynivalenol antibody. The carboxyl group of the SAM was bound to the anti-deoxynivalenol antibody. The anti-deoxynivalenol antibody and deoxynivalenol were bound by their antigen-antibody reaction. The measurements were performed in phosphate buffered saline (PBS; pH 7.4) solution. A standard Ag/AgCl electrode was employed as a reference electrode. The bindings of a SAM, anti-deoxynivalenol antibody, and deoxynivalenol caused a variation in the output voltage of the extended-gate MOSFET-based biosensor. Surface plasmon resonance (SPR) measurement was performed to verify the interaction among the SAM, deoxynivalenol-antibody, and deoxynivalenol.

  18. Porphyrin-silicon hybrid field-effect transistor with individually addressable top-gate structure.

    PubMed

    Seol, Myeong-Lok; Choi, Sung-Jin; Kim, Chang-Hoon; Moon, Dong-Il; Choi, Yang-Kyu

    2012-01-24

    A conductance-controllable hybrid device that utilizes the photoinduced charge transfer behavior of a porphyrin in a field-effect transistor (FET) with a nanogap is proposed and analyzed. A conventional metal-oxide-semiconductor (MOS) structure is modified to form a nanogap in which the porphyrin can be embedded. The conductance of an inversion channel is controlled by the negatively charged, optically activated porphyrin molecules. The proposed nanogap-formed MOSFET structure solves the conventional dilemma that a top-gate cannot be used for an organic-inorganic hybrid device because the top-gate blocks an entire area of a channel where organic material should be immobilized. The top-gate structure has much practicality compared with the back-gate structure because each device can be controlled individually. Furthermore, the device is highly compatible with the chip-based integrated system because the fabrication process follows the standard complementary metal-oxide-semiconductor (CMOS) technology. The charge transfer mechanisms between silicon and porphyrin are analyzed using devices with different doping polarities and geometrical parameters. The results show that the influence of the negative charge of the porphyrin in the device is reversed when opposite doping polarities are used. The device characteristics can be comprehensively evaluated using the energy band diagram analysis and simulation. The possible application of the proposed device for nonvolatile memory is demonstrated using the optical charging and electrical discharging behavior of the porphyrins.

  19. Ion-selective electrolyte-gated field-effect transistors: prerequisites for proper functioning

    NASA Astrophysics Data System (ADS)

    Kofler, Johannes; Schmoltner, Kerstin; List-Kratochvil, Emil J. W.

    2014-10-01

    Electrolyte-gated organic field-effect transistors (EGOFETs) used as transducers and amplifiers in potentiometric sensors have recently attracted a significant amount of scientific interest. For that reason, the fundamental prerequisites to achieve a proper potentiometric signal amplification and transduction are examined. First, polarizable as well as non-polarizable semiconductor- and gate-electrolyte- interface combinations are investigated by normal pulse voltammetry. The results of these measurements are correlated with the corresponding transistor characteristics, clarifying the functional principle of EGOFETs and the requirements for high signal amplification. In addition to a good electrical performance, the EGOFET-transducers should also be compatible with the targeted sensing application. Accordingly, the influence of different gate materials and electrolytes on the sensing abilities, are discussed. Even though all physical requirements are met, EGOFETs typically exhibit irreversible degradation, if the gate potential exceeds a certain level. For that reason, EGOFETs have to be operated using a constant source-drain operation mode which is presented by means of an H+ (pH) sensitive ion-sensor.

  20. Tunnel field-effect transistor with asymmetric gate dielectric and body thickness

    NASA Astrophysics Data System (ADS)

    Kwon, Dae Woong; Park, Byung-Gook

    2017-04-01

    Tunnel field-effect transistor (TFET) with asymmetric gate dielectric and body thickness (TFETAsy) is proposed. The TFETAsy not only reduces the tunneling resistance by using the thinner source-side gate dielectric and body, but also suppresses the ambipolar current (I ambipolar) and the degradation of alternating current (AC) switching performances with the thicker drain-side gate dielectric and body. Technology computer aided design process and device/circuit simulations are performed to verify the validity of the TFETAsy in terms of fabrication process and electrical characteristics. From the simulation results, it is revealed that the thinner source-side gate dielectric and body can be simply formed by oxide wet-etching after the selective oxidation of the source-side body. Moreover, the thinner source-side SiGe body can be also formed by using Ge condensation process instead of the oxidation. Additionally, it is confirmed that the TFETAsy has higher on-current, steeper subthreshold swing, lower I ambipolar and improved AC switching characteristics as compared to those of conventional TFET with symmetric structure.

  1. Implementing a Microcontroller Watchdog with a Field-Programmable Gate Array (FPGA)

    NASA Technical Reports Server (NTRS)

    Straka, Bartholomew

    2013-01-01

    Reliability is crucial to safety. Redundancy of important system components greatly enhances reliability and hence safety. Field-Programmable Gate Arrays (FPGAs) are useful for monitoring systems and handling the logic necessary to keep them running with minimal interruption when individual components fail. A complete microcontroller watchdog with logic for failure handling can be implemented in a hardware description language (HDL.). HDL-based designs are vendor-independent and can be used on many FPGAs with low overhead.

  2. Characterization of Hardening by Design Techniques on Commercial, Small Feature Sized Field-Programmable Gate Arrays

    DTIC Science & Technology

    2009-03-01

    AFIT/GE/ENG/09-43 CHARACTERIZATION OF HARDENING BY DESIGN TECHNIQUES ON COMMERCIAL, SMALL FEATURE SIZED FIELD-PROGRAMMABLE GATE ARRAYS THESIS...The purpose of which is to determine the radiation effects and characterize the improvements of various hardening by design techniques. The...Distributed RAM memory elements that are loaded both with ECC and non-error corrected data. The circuit is designed to check for errors in memory data, stuck

  3. A simple laser locking system based on a field-programmable gate array

    NASA Astrophysics Data System (ADS)

    Jørgensen, N. B.; Birkmose, D.; Trelborg, K.; Wacker, L.; Winter, N.; Hilliard, A. J.; Bason, M. G.; Arlt, J. J.

    2016-07-01

    Frequency stabilization of laser light is crucial in both scientific and industrial applications. Technological developments now allow analog laser stabilization systems to be replaced with digital electronics such as field-programmable gate arrays, which have recently been utilized to develop such locking systems. We have developed a frequency stabilization system based on a field-programmable gate array, with emphasis on hardware simplicity, which offers a user-friendly alternative to commercial and previous home-built solutions. Frequency modulation, lock-in detection, and a proportional-integral-derivative controller are programmed on the field-programmable gate array and only minimal additional components are required to frequency stabilize a laser. The locking system is administered from a host-computer which provides comprehensive, long-distance control through a versatile interface. Various measurements were performed to characterize the system. The linewidth of the locked laser was measured to be 0.7 ± 0.1 MHz with a settling time of 10 ms. The system can thus fully match laser systems currently in use for atom trapping and cooling applications.

  4. Dual field effects in electrolyte-gated spinel ferrite: electrostatic carrier doping and redox reactions

    PubMed Central

    Ichimura, Takashi; Fujiwara, Kohei; Tanaka, Hidekazu

    2014-01-01

    Controlling the electronic properties of functional oxide materials via external electric fields has attracted increasing attention as a key technology for next-generation electronics. For transition-metal oxides with metallic carrier densities, the electric-field effect with ionic liquid electrolytes has been widely used because of the enormous carrier doping capabilities. The gate-induced redox reactions revealed by recent investigations have, however, highlighted the complex nature of the electric-field effect. Here, we use the gate-induced conductance modulation of spinel ZnxFe3−xO4 to demonstrate the dual contributions of volatile and non-volatile field effects arising from electronic carrier doping and redox reactions. These two contributions are found to change in opposite senses depending on the Zn content x; virtual electronic and chemical field effects are observed at appropriate Zn compositions. The tuning of field-effect characteristics via composition engineering should be extremely useful for fabricating high-performance oxide field-effect devices. PMID:25056718

  5. Side-by-Side Field Evaluation of Highly Insulating Windows in the PNNL Lab Homes

    SciTech Connect

    Widder, Sarah H.; Parker, Graham B.; Baechler, Michael C.; Bauman, Nathan N.

    2012-08-01

    To examine the energy, air leakage, and thermal performance of highly insulating windows, a field evaluation was undertaken in a matched pair of all-electric, factory-built “Lab Homes” located on the Pacific Northwest National Laboratory (PNNL) campus in Richland, Washington. The “baseline” Lab Home B was retrofitted with “standard” double-pane clear aluminum-frame slider windows and patio doors, while the “experimental” Lab Home A was retrofitted with Jeld-Wen® triple-pane vinyl-frame slider windows and patio doors with a U-factor of 0.2 and solar heat gain coefficient of 0.19. To assess the window, the building shell air leakage, energy use, and interior temperatures of each home were compared during the 2012 winter heating and summer cooling seasons. The measured energy savings in Lab Home B averaged 5,821 watt-hours per day (Wh/day) during the heating season and 6,518 Wh/day during the cooling season. The overall whole-house energy savings of Lab Home B compared to Lab Home A are 11.6% ± 1.53% for the heating season and 18.4 ± 2.06% for the cooling season for identical occupancy conditions with no window coverings deployed. Extrapolating these energy savings numbers based on typical average heating degree days and cooling degree days per year yields an estimated annual energy savings of 12.2%, or 1,784 kWh/yr. The data suggest that highly insulating windows are an effective energy-saving measure that should be considered for high-performance new homes and in existing retrofits. However, the cost effectiveness of the measure, as determined by the simple payback period, suggests that highly insulating window costs continue to make windows difficult to justify on a cost basis alone. Additional reductions in costs via improvements in manufacturing and/or market penetration that continue to drive down costs will make highly insulating windows much more viable as a cost-effective energy efficiency measure. This study also illustrates that highly

  6. Highly stable organic field-effect transistors with engineered gate dielectrics (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kippelen, Bernard; Wang, Cheng-Yin; Fuentes-Hernandez, Canek; Yun, Minseong; Singh, Ankit K.; Dindar, Amir; Choi, Sangmoo; Graham, Samuel

    2016-11-01

    Organic field-effect transistors (OFETs) have the potential to lead to low-cost flexible displays, wearable electronics, and sensors. While recent efforts have focused greatly on improving the maximum charge mobility that can be achieved in such devices, studies about the stability and reliability of such high performance devices are relatively scarce. In this talk, we will discuss the results of recent studies aimed at improving the stability of OFETs under operation and their shelf lifetime. In particular, we will focus on device architectures where the gate dielectric is engineered to act simultaneously as an environmental barrier layer. In the past, our group had demonstrated solution-processed top-gate OFETs using TIPS-pentacene and PTAA blends as a semiconductor layer with a bilayer gate dielectric layer of CYTOP/Al2O3, where the oxide layer was fabricated by atomic layer deposition, ALD. Such devices displayed high operational stability with little degradation after 20,000 on/off scan cycles or continuous operation (24 h), and high environmental stability when kept in air for more than 2 years, with unchanged carrier mobility. Using this stable device geometry, simple circuits and sensors operating in aqueous conditions were demonstrated. However, the Al2O3 layer was found to degrade due to corrosion under prolonged exposure in aqueous solutions. In this talk, we will report on the use of a nanolaminate (NL) composed of Al2O3 and HfO2 by ALD to replace the Al2O3 single layer in the bilayer gate dielectric use in top-gate OFETs. Such OFETs were found to operate under harsh condition such as immersion in water at 95 °C. This work was funded by the Department of Energy (DOE) through the Bay Area Photovoltaics Consortium (BAPVC) under Award Number DE-EE0004946.

  7. Fabrication and characterization of a charge-biased CMOS-MEMS resonant gate field effect transistor

    NASA Astrophysics Data System (ADS)

    Chin, C. H.; Li, C. S.; Li, M. H.; Wang, Y. L.; Li, S. S.

    2014-09-01

    A high-frequency charge-biased CMOS-MEMS resonant gate field effect transistor (RGFET) composed of a metal-oxide composite resonant-gate structure and an FET transducer has been demonstrated utilizing the TSMC 0.35 μm CMOS technology with Q > 1700 and a signal-to-feedthrough ratio greater than 35 dB under a direct two-port measurement configuration. As compared to the conventional capacitive-type MEMS resonators, the proposed CMOS-MEMS RGFET features an inherent transconductance gain (gm) offered by the FET transduction capable of enhancing the motional signal of the resonator and relaxing the impedance mismatch issue to its succeeding electronics or 50 Ω-based test facilities. In this work, we design a clamped-clamped beam resonant-gate structure right above a floating gate FET transducer as a high-Q building block through a maskless post-CMOS process to combine merits from the large capacitive transduction areas of the large-width beam resonator and the high gain of the underneath FET. An analytical model is also provided to simulate the behavior of the charge-biased RGFET; the theoretical prediction is in good agreement with the experimental results. Thanks to the deep-submicrometer gap spacing enabled by the post-CMOS polysilicon release process, the proposed resonator under a purely capacitive transduction already attains motional impedance less than 10 kΩ, a record-low value among CMOS-MEMS capacitive resonators. To go one step further, the motional signal of the proposed RGFET is greatly enhanced through the FET transduction. Such a strong transmission and a sharp phase transition across 0° pave a way for future RGFET-type oscillators in RF and sensor applications. A time-elapsed characterization of the charge leakage rate for the floating gate is also carried out.

  8. Magnetic-Field-Induced Insulator-Conductor Transition in SU(2) Quenched Lattice Gauge Theory

    SciTech Connect

    Buividovich, P.V.; Kharzeev, D.; Chernodub, M.N., Kalaydzhyan, T., Luschevskaya, E.V., and M.I. Polikarpov

    2010-09-24

    We study the correlator of two vector currents in quenched SU(2) lattice gauge theory with a chirally invariant lattice Dirac operator with a constant external magnetic field. It is found that in the confinement phase the correlator of the components of the current parallel to the magnetic field decays much slower than in the absence of a magnetic field, while for other components the correlation length slightly decreases. We apply the maximal entropy method to extract the corresponding spectral function. In the limit of zero frequency this spectral function yields the electric conductivity of quenched theory. We find that in the confinement phase the external magnetic field induces nonzero electric conductivity along the direction of the field, transforming the system from an insulator into an anisotropic conductor. In the deconfinement phase the conductivity does not exhibit any sizable dependence on the magnetic field.

  9. Effect of annealing temperature of Bi1.5Zn1.0Nb1.5O7 gate insulator on performance of ZnO based thin film transistors

    NASA Astrophysics Data System (ADS)

    Wei, Ye; Wei, Ren; Peng, Shi; Zhuangde, Jiang

    2016-07-01

    The bottom-gate structure ZnO based thin film transistors (ZnO-TFTs) using Bi1.5Zn1.0Nb1.5O7 (BZN) thin films as gate insulator were fabricated on Pt/SiO2/Si substrate by radio frequency magnetic sputtering. We investigated the effect of annealing temperature at 300, 400, and 500 °C on the performance of BZN thin films and ZnO-TFTs. XRD measurement confirmed that BZN thin films were amorphous in nature. BZN thin films annealed at 400 °C obtain the high capacitance density of 249 nF/cm2, high dielectric constant of 71, and low leakage current density of 10-7 A/cm2 on/off current ratio and field effect mobility of ZnO-TFTs annealed at 400 °C are approximately one order of magnitude and two times, respectively higher than that of ZnO-TFTs annealed at 300 °C. When the annealing temperature is 400 °C, the electrical performance of ZnO-TFTs is enhanced remarkably. Devices obtain a low sub-threshold swing of 470 mV/dec and surface states density of 3.21 × 1012cm-2. Project supported by the National Natural Science Foundation of China (Nos. 51332003, 51202184), the International Science & Technology Cooperation Program of China (Nos. 2010DFB13640, 2011DFA51880), and the “111 Project” of China (No. B14040).

  10. Novel process for widening memory window of sub-200 nm ferroelectric-gate field-effect transistor by ferroelectric coating the gate-stack sidewall

    NASA Astrophysics Data System (ADS)

    Van Hai, Le; Takahashi, Mitsue; Zhang, Wei; Sakai, Shigeki

    2015-01-01

    Ferroelectric-gate field-effect transistors (FeFETs) with metallurgical-gate lengths of 140 nm, 160 nm and 190 nm were successfully fabricated using a novel fabrication process. The gate stacks of the FeFETs were Pt/Sr0.8Ca0.2Bi2Ta2O9(SCBT)/HfO2/Si. Key to the process was covering the as-etched gate-stack sidewalls with SCBT precursor films and annealing altogether. The FeFETs which underwent the novel process showed larger memory windows than those without the process by about 0.5 V at scanned gate-voltages of 1 ± 5 V. Endurances of the FeFETs made by the novel process were measured up to 109 cycles with good separations of the on- and off-states. The endurance pulses were 1 ± 5 V with 2 μs period. Good data-retentions of them were also demonstrated which were measured for at least 6.5 days.

  11. Characterization of SiO{sub 2}/SiN{sub x} gate insulators for graphene based nanoelectromechanical systems

    SciTech Connect

    Tóvári, E.; Csontos, M. Kriváchy, T.; Csonka, S.; Fürjes, P.

    2014-09-22

    The structural and magnetotransport characterization of graphene nanodevices exfoliated onto Si/SiO{sub 2}/SiN{sub x} heterostructures are presented. Improved visibility of the deposited flakes is achieved by optimal tuning of the dielectric film thicknesses. The conductance of single layer graphene Hall-bar nanostructures utilizing SiO{sub 2}/SiN{sub x} gate dielectrics were characterized in the quantum Hall regime. Our results highlight that, while exhibiting better mechanical and chemical stability, the effect of non-stoichiometric SiN{sub x} on the charge carrier mobility of graphene is comparable to that of SiO{sub 2}, demonstrating the merits of SiN{sub x} as an ideal material platform for graphene based nanoelectromechanical applications.

  12. Field Testing of an Unvented Roof with Fibrous Insulation, Tiles, and Vapor Diffusion Venting

    SciTech Connect

    Ueno, K.; Lstiburek, J. W.

    2016-02-01

    This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane. As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design.

  13. Composite fermions and the field-tuned superconductor-insulator transition

    NASA Astrophysics Data System (ADS)

    Raghu, Srinivas; Mulligan, Michael

    In several two-dimensional films that exhibit a magnetic field-tuned superconductor to insulator transition (SIT), stable metallic phases have been observed. Building on the `dirty boson' description of the SIT, we suggest that the metallic region is analogous to the composite Fermi liquid observed about half-filled Landau levels of the two-dimensional electron gas. The composite fermions here are mobile vortices attached to one flux quantum of an emergent gauge field. The composite vortex liquid is a 2D non-Fermi liquid metal, which we argue is stable to weak quenched disorder. We describe several experimental consequences of the emergent composite vortex liquid.

  14. Composite fermions and the field-tuned superconductor-insulator transition

    NASA Astrophysics Data System (ADS)

    Mulligan, Michael; Raghu, S.

    2016-05-01

    In several two-dimensional films that exhibit a magnetic field-tuned superconductor to insulator transition (SIT), stable metallic phases have been observed. Building on the `dirty boson' description of the SIT, we suggest that the metallic region is analogous to the composite Fermi liquid observed about half-filled Landau levels of the two-dimensional electron gas. The composite fermions here are mobile vortices attached to one flux quantum of an emergent gauge field. The composite vortex liquid is a 2D non-Fermi liquid metal, which we argue is stable to weak quenched disorder. We describe several experimental consequences of the emergent composite vortex liquid.

  15. A novel Tunneling Graphene Nano Ribbon Field Effect Transistor with dual material gate: Numerical studies

    NASA Astrophysics Data System (ADS)

    Ghoreishi, Seyed Saleh; Saghafi, Kamyar; Yousefi, Reza; Moravvej-farshi, Mohammad Kazem

    2016-09-01

    In this work, we present Dual Material Gate Tunneling Graphene Nano-Ribbon Field Effect Transistors (DMG-T-GNRFET) mainly to suppress the am-bipolar current with assumption that sub-threshold swing which is one of the important characteristics of tunneling transistors must not be degraded. In the proposed structure, dual material gates with different work functions are used. Our investigations are based on numerical simulations which self-consistently solves the 2D Poisson based on an atomistic mode-space approach and Schrodinger equations, within the Non-Equilibrium Green's (NEGF). The proposed device shows lower off-current and on-off ratio becomes 5order of magnitude greater than the conventional device. Also two different short channel effects: Drain Induced Barrier Shortening (DIBS) and hot-electron effect are improved in the proposed device compare to the main structure.

  16. Role of deposition and annealing of the top gate dielectric in a-IGZO TFT-based dual-gate ion-sensitive field-effect transistors

    NASA Astrophysics Data System (ADS)

    Kumar, Narendra; Sutradhar, Moitri; Kumar, Jitendra; Panda, Siddhartha

    2017-03-01

    The deposition of the top gate dielectric in thin film transistor (TFT)-based dual-gate ion-sensitive field-effect transistors (DG ISFETs) is critical, and expected not to affect the bottom gate TFT characteristics, while providing a higher pH sensitive surface and efficient capacitive coupling between the gates. Amorphous Ta2O5, in addition to having good sensing properties, possesses a high dielectric constant of ∼25 making it well suited as the top gate dielectric in a DG ISFET by providing higher capacitive coupling (ratio of C top/C bottom) leading to higher amplification. To avoid damage of the a-IGZO channel reported to be caused by plasma exposure, deposition of Ta2O5 by e-beam evaporation followed by annealing was investigated in this work to obtain sensitivity over the Nernst limit. The deteriorated bottom gate TFT characteristics, indicated by an increase in the channel conductance, confirmed that plasma exposure is not the sole contributor to the changes. Oxygen vacancies at the Ta2O5/a-IGZO interface, which emerged during processing, increased the channel conductivity, became filled by optimum annealing in oxygen at 400 °C for 1 h, which was confirmed by an x-ray photoelectron spectroscopy depth profiling analysis. The obtained pH sensitivity of the TFT-based DG ISFET was 402 mV pH‑1, which is about 6.8 times the Nernst limit (59 mV pH‑1). The concept of capacitive coupling was also demonstrated by simulating an a-IGZO-based DG TFT structure. Here, the exposure of the top gate dielectric to the electrolyte without applying any top gate bias led to changes in the measured threshold voltage of the bottom gate TFT, and this obviated the requirement of a reference electrode needed in conventional ISFETs and other reported DG ISFETs. These devices, with high sensitivities and requiring low volumes (∼2 μl) of analyte solution, could be potential candidates for utilization as chemical sensors and biosensors.

  17. Electrostatic Gating of Ultrathin Films

    NASA Astrophysics Data System (ADS)

    Goldman, A. M.

    2014-07-01

    Electrostatic gating of ultrathin films can be used to modify electronic and magnetic properties of materials by effecting controlled alterations of carrier concentration while, in principle, not changing the level of disorder. As such, electrostatic gating can facilitate the development of novel devices and can serve as a means of exploring the fundamental properties of materials in a manner far simpler than is possible with the conventional approach of chemical doping. The entire phase diagram of a compound can be traversed by changing the gate voltage. In this review, we survey results involving conventional field effect devices as well as more recent progress, which has involved structures that rely on electrochemical configurations such as electric double-layer transistors. We emphasize progress involving thin films of oxide materials such as high-temperature superconductors, magnetic oxides, and oxides that undergo metal-insulator transitions.

  18. Physiologically gated microbeam radiation using a field emission x-ray source array

    SciTech Connect

    Chtcheprov, Pavel E-mail: zhou@email.unc.edu; Burk, Laurel; Inscoe, Christina; Ger, Rachel; Hadsell, Michael; Lu, Jianping; Yuan, Hong; Zhang, Lei; Chang, Sha; Zhou, Otto E-mail: zhou@email.unc.edu

    2014-08-15

    Purpose: Microbeam radiation therapy (MRT) uses narrow planes of high dose radiation beams to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000 Gy of peak entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during treatment can lead to significant movement of microbeam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), which reduces the effectiveness of MRT. Recently, the authors have demonstrated the feasibility of generating microbeam radiation for small animal treatment using a carbon nanotube (CNT) x-ray source array. The purpose of this study is to incorporate physiological gating to the CNT microbeam irradiator to minimize motion-induced microbeam blurring. Methods: The CNT field emission x-ray source array with a narrow line focal track was operated at 160 kVp. The x-ray radiation was collimated to a single 280 μm wide microbeam at entrance. The microbeam beam pattern was recorded using EBT2 Gafchromic{sup ©} films. For the feasibility study, a strip of EBT2 film was attached to an oscillating mechanical phantom mimicking mouse chest respiratory motion. The servo arm was put against a pressure sensor to monitor the motion. The film was irradiated with three microbeams under gated and nongated conditions and the full width at half maximums and PVDRs were compared. An in vivo study was also performed with adult male athymic mice. The liver was chosen as the target organ for proof of concept due to its large motion during respiration compared to other organs. The mouse was immobilized in a specialized mouse bed and anesthetized using isoflurane. A pressure sensor was attached to a mouse's chest to monitor its respiration. The output signal triggered the electron extraction voltage of the field emission source such that x-ray was generated only during a

  19. Effects of gate insulator using high pressure annealing on the characteristics of solid phase crystallized polycrystalline silicon thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Moojin; Jin, GuangHai

    2009-04-01

    The oxidizing ambient was built using high pressure H2O vapor at 550 °C. For the solid phase crystallization (SPC) polycrystalline silicon (poly-Si) that is annealed for 1 h at 2 MPa, the oxide thickness is about 150 Å. The oxide layer is approximately 90 Å above the original surface of the poly-Si and 60 Å below the original surface. The oxide layer is used as the first gate insulator layer of thin-film transistors (TFTs). The heating at 550 °C with 2 MPa H2O vapor increased the carrier mobility from 17.6 cm2/V s of the conventional SPC process to 30.4 cm2/V s, and it reduced the absolute value of the threshold voltage (Vth) from 4.13 to 3.62 V. The subthreshold swing also decreased from 0.72 to 0.60 V/decade. This improvement is attributed mainly to the reduction in defect density at the oxide/poly-Si interface and in the poly-Si film by the high pressure annealing (HPA) process. Since the realization of excellent performance at the oxide/poly-Si interface and in poly-Si depends on the defect density, the poly-Si having the thermal oxide formed by a combined process of SPC and HPA may be well suited for fabrication of poly-Si TFTs for flat panel displays such as active matrix organic light emitting diodes.

  20. A Low Temperature, Solution-Processed Poly(4-vinylphenol), YO(x) Nanoparticle Composite/Polysilazane Bi-Layer Gate Insulator for ZnO Thin Film Transistor.

    PubMed

    Shin, Hyeonwoo; Kang, Chan-Mo; Chae, Hyunsik; Kim, Hyun-Gwan; Baek, Kyu-Ha; Choi, Hyoung Jin; Park, Man-Young; Do, Lee-Mi; Lee, Changhee

    2016-03-01

    Low temperature, solution-processed metal oxide thin film transistors (MEOTFTs) have been widely investigated for application in low-cost, transparent, and flexible electronics. To enlarge the application area, solution-processed gate insulators (GI) have been investigated in recent years. We investigated the effects of the organic/inorganic bi-layer GI to ZnO thin film transistors (TFTs). PVP, YO(x) nanoparticle composite, and polysilazane bi-layer showed low leakage current (-10(-8) A/cm2 in 2 MV), which are applicable in low temperature processed MEOTFTs. Polysilazane was used as an interlayer between ZnO and PVP, YO(x) nanoparticle composite as a good charge transport interface with ZnO. By applying the PVP, YO(x), nanoparticle composite/polysilazane bi-layer structure to ZnO TFTs, we successfully suppressed the off current (I(off)) to -10(-11) and fabricated good MEOTFTs in 180 degrees C.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  2. Numerical Computation of Electric Field and Potential Along Silicone Rubber Insulators Under Contaminated and Dry Band Conditions

    NASA Astrophysics Data System (ADS)

    Arshad; Nekahi, A.; McMeekin, S. G.; Farzaneh, M.

    2016-09-01

    Electrical field distribution along the insulator surface is considered one of the important parameters for the performance evaluation of outdoor insulators. In this paper numerical simulations were carried out to investigate the electric field and potential distribution along silicone rubber insulators under various polluted and dry band conditions. Simulations were performed using commercially available simulation package Comsol Multiphysics based on the finite element method. Various pollution severity levels were simulated by changing the conductivity of pollution layer. Dry bands of 2 cm width were inserted at the high voltage end, ground end, middle part, shed, sheath, and at the junction of shed and sheath to investigate the effect of dry band location and width on electric field and potential distribution. Partial pollution conditions were simulated by applying pollution layer on the top and bottom surface respectively. It was observed from the simulation results that electric field intensity was higher at the metal electrode ends and at the junction of dry bands. Simulation results showed that potential distribution is nonlinear in the case of clean and partially polluted insulator and linear for uniform pollution layer. Dry band formation effect both potential and electric field distribution. Power dissipated along the insulator surface and the resultant heat generation was also studied. The results of this study could be useful in the selection of polymeric insulators for contaminated environments.

  3. Cluster mean-field signature of entanglement entropy in bosonic superfluid-insulator transitions

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Qin, Xizhou; Ke, Yongguan; Lee, Chaohong

    2016-08-01

    Entanglement entropy (EE), a fundamental concept in quantum information for characterizing entanglement, has been extensively employed to explore quantum phase transitions (QPTs). Although the conventional single-site mean-field (MF) approach successfully predicts the emergence of QPTs, it fails to include any entanglement. Here, in the framework of a cluster MF treatment, we extract the signature of EE in bosonic superfluid-insulator (SI) transitions. We consider a trimerized Kagomé lattice of interacting bosons, in which each trimer is treated as a cluster, and implement the cluster MF treatment by decoupling all intertrimer hopping. In addition to superfluid and integer insulator phases, we find that fractional insulator phases appear when the tunneling is dominated by the intratrimer part. To quantify the residual bipartite entanglement in a cluster, we calculate the second-order Rényi entropy, which can be experimentally measured by quantum interference of many-body twins. The second-order Rényi entropy itself is continuous everywhere, however, the continuousness of its first-order derivative breaks down at the phase boundary. This means that the bosonic SI transitions can still be efficiently captured by the residual entanglement in our cluster MF treatment. Besides to the bosonic SI transitions, our cluster MF treatment may also be used to capture the signature of EE for other QPTs in quantum superlattice models.

  4. Hybridization and Field Driven Phase Transitions in Hexagonally Warped Topological Insulators

    NASA Astrophysics Data System (ADS)

    Menon, Anirudha; Chowdhury, Debashree; Basu, Banasri

    2016-09-01

    In this paper, we discuss the role of material parameters and external field effects on a thin film topological insulator(TI) in the context of quantum phase transition (QPT). First, we consider an in-plane tilted magnetic field and determine the band structure of the surface states as a function of the tilt angle. We show that the presence of either a hybridization term or hexagonal warping or a combination of both leads to a semi-metal to insulator phase transition which is facilitated by their 𝒫𝒯 symmetry breaking character. We then note that while the introduction of an electric field does not allow for this QPT since it does not break 𝒫𝒯 symmetry, it can be used in conjunction with a tunneling element to reach a phase transition efficiently. The corresponding critical point is then nontrivially dependent on the electric field, which is pointed out here. Then, we demonstrate that including a hexagonal warping term leads to an immediate 𝒫𝒯 symmetry violating QPT.

  5. Linear kink effect Lorentzians in the noise spectra of n- and p-channel fin field-effect transistors processed in standard and strained silicon-on-insulator substrates

    NASA Astrophysics Data System (ADS)

    Lukyanchikova, N.; Garbar, N.; Kudina, V.; Smolanka, A.; Claeys, C.; Simoen, E.

    2009-06-01

    The Lorentzian-like noise induced by Electron Valence Band (EVB) tunneling has been investigated in n- and p-channel multiple-gate field-effect transistors (MuGFETs), processed on silicon-on-insulator (SOI) and strained SOI (sSOI) substrates. The effect has been studied for different back-gate and front-gate biases and as a function of the device geometry. Similar as for wide fully depleted SOI transistors, this type of excess low-frequency noise is found when the back gate is biased in accumulation. However, it is shown that the characteristic time constant of the Lorentzian cannot be modeled assuming a uniform EVB tunneling current across the gate area of the MuGFETs. This indicates an impact of the three-dimensional nature of the device architecture on the so-called linear kink effects. In addition, it is demonstrated that the tensile strain in sSOI MuGFETs also yields a change in the Lorentzian parameters, associated with changes in the EVB tunneling current.

  6. Ionic-Liquid Gated Few-layer MoS2 Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Perera, Meeghage; Lin, Ming-Wei; Chuang, Hsun-Jen; Chamlagain, Bhim; Wang, Chongyu; Tan, Xuebin; Cheng, Mark Ming-Cheng; Zhou, Zhixian

    2013-03-01

    We report the electrical characterization of ionic-liquid-gated bilayer and few-layer MoS2 field-effect transistors. The extrinsic mobility of our ionic-liquid-gated devices exceeds 70 cm2V-1S-1 at 250 K, which is 1-2 orders of magnitude higher than that measured in the Si back-gate configuration (without ionic liquid). These devices also show ambipolar behavior with a high ON-OFF current ratio of > 107 for electrons and > 106 for holes, and a near ideal subthreshold swing (SS) of ~ 50 mV/decade at 250 K for the electron channel. More significantly, we show that the mobility increases from ~ 100 cm2V-1S-1 at 180 K to ~ 220 cm2V-1S-1 at 77K as the temperature decreases following a μ ~ T-γ dependence with γ ~ 1, indicating that the intrinsic phonon-limited mobility can be achieved in few-layer MoS2 FETs. We attribute the enhanced device performance to the drastic reduction of the Schottky barrier width (thus higher tunneling efficiency) via highly efficient band bending at the MoS2/metal interface afforded by the extremely large electrical double layer capacitance of the ionic liquid. This work was supported by NSF (No. ECCS-1128297).

  7. Touch sensors based on planar liquid crystal-gated-organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Seo, Jooyeok; Lee, Chulyeon; Han, Hyemi; Lee, Sooyong; Nam, Sungho; Kim, Hwajeong; Lee, Joon-Hyung; Park, Soo-Young; Kang, Inn-Kyu; Kim, Youngkyoo

    2014-09-01

    We report a tactile touch sensor based on a planar liquid crystal-gated-organic field-effect transistor (LC-g-OFET) structure. The LC-g-OFET touch sensors were fabricated by forming the 10 μm thick LC layer (4-cyano-4'-pentylbiphenyl - 5CB) on top of the 50 nm thick channel layer (poly(3-hexylthiophene) - P3HT) that is coated on the in-plane aligned drain/source/gate electrodes (indium-tin oxide - ITO). As an external physical stimulation to examine the tactile touch performance, a weak nitrogen flow (83.3 μl/s) was employed to stimulate the LC layer of the touch device. The LC-g-OFET device exhibited p-type transistor characteristics with a hole mobility of 1.5 cm2/Vs, but no sensing current by the nitrogen flow touch was measured at sufficiently high drain (VD) and gate (VG) voltages. However, a clear sensing current signal was detected at lower voltages, which was quite sensitive to the combination of VD and VG. The best voltage combination was VD = -0.2 V and VG = -1 V for the highest ratio of signal currents to base currents (i.e., signal-to-noise ratio). The change in the LC alignment upon the nitrogen flow touch was assigned as the mechanism for the present LC-g-OFET touch sensors.

  8. Effect of muscle contraction strength on gating of somatosensory magnetic fields.

    PubMed

    Sugawara, Kazuhiro; Onishi, Hideaki; Yamashiro, Koya; Kotan, Shinichi; Kojima, Sho; Miyaguchi, Shota; Tsubaki, Atsuhiro; Kirimoto, Hikari; Tamaki, Hiroyuki; Shirozu, Hiroshi; Kameyama, Shigeki

    2016-11-01

    Afferent somatosensory information is modulated before the afferent input arrives at the primary somatosensory cortex during voluntary movement. The aim of the present study was to clarify the effect of muscular contraction strength on somatosensory evoked fields (SEFs) during voluntary movement. In addition, we examined the differences in gating between innervated and non-innervated muscle during contraction. We investigated the changes in gating effect by muscular contraction strength and innervated and non-innervated muscles in human using 306-channel magnetoencephalography. SEFs were recorded following the right median nerve stimulation in a resting condition and during isometric muscular contractions from 10 % electromyographic activity (EMG), 20 and 30 % EMG of the right extensor indicis muscle and abductor pollicis brevis muscle. Our results showed that the equivalent current dipole (ECD) strength for P35m decreased with increasing strength of muscular contraction of the right abductor pollicis brevis muscle. However, changes were observed only at 30 % EMG contraction level of the right extensor indicis muscle, which was not innervated by the median nerve. There were no significant changes in the peak latencies and ECD locations of each component in all conditions. The ECD strength did not differ significantly for N20m and P60m regardless of the strength of muscular contraction and innervation. Therefore, we suggest that the gating of SEF waveforms following peripheral nerve stimulation was affected by the strength of muscular contraction and innervation of the contracting muscle.

  9. Field Evaluation of Highly Insulating Windows in the Lab Homes: Winter Experiment

    SciTech Connect

    Parker, Graham B.; Widder, Sarah H.; Bauman, Nathan N.

    2012-06-01

    This field evaluation of highly insulating windows was undertaken in a matched pair of 'Lab Homes' located on the Pacific Northwest National Laboratory (PNNL) campus during the 2012 winter heating season. Improving the insulation and solar heat gain characteristics of a home's windows has the potential to significantly improve the home's building envelope and overall thermal performance by reducing heat loss (in the winter), and cooling loss and solar heat gain (in the summer) through the windows. A high quality installation and/or window retrofit will also minimize or reduce air leakage through the window cavity and thus also contribute to reduced heat loss in the winter and cooling loss in the summer. These improvements all contribute to decreasing overall annual home energy use. Occupant comfort (non-quantifiable) can also be increased by minimizing or eliminating the cold 'draft' (temperature) many residents experience at or near window surfaces that are at a noticeably lower temperature than the room air temperature. Lastly, although not measured in this experiment, highly insulating windows (triple-pane in this experiment) also have the potential to significantly reduce the noise transmittance through windows compared to standard double-pane windows. The metered data taken in the Lab Homes and data analysis presented here represent 70 days of data taken during the 2012 heating season. As such, the savings from highly insulating windows in the experimental home (Lab Home B) compared to the standard double-pane clear glass windows in the baseline home (Lab Home A) are only a portion of the energy savings expected from a year-long experiment that would include a cooling season. The cooling season experiment will take place in the homes in the summer of 2012, and results of that experiment will be reported in a subsequent report available to all stakeholders.

  10. Fabrication of aligned nanofibers by electric-field-controlled electrospinning: insulating-block method.

    PubMed

    Hwang, Wontae; Pang, Changhyun; Chae, Heeyeop

    2016-10-28

    Aligned nanofiber arrays and mats were fabricated with an electrospinning process by manipulating the electric field. The electric field was modified by insulating blocks (IBs) that were installed between the nozzle and the substrate as guiding elements to control the trajectory of the electrospinning jet flow. Simulation results showed that the electric field was deformed near the IBs, resulting in confinement of the electrospinning jet between the blocks. The balance of the electric field in the vertical direction and the repulsive force by space charges in the confined electrified jet stream was attributed to the aligned motion of the jet. Aligned arrays of 200 nm thick polyethylene oxide nanofibers were obtained, exhibiting wave-shaped and cross patterns as well as rectilinear patterns. In addition, 40 μm thick quasi-aligned carbon-nanofiber mats with anisotropic electrical property were also attained by this method.

  11. Fabrication of aligned nanofibers by electric-field-controlled electrospinning: insulating-block method

    NASA Astrophysics Data System (ADS)

    Hwang, Wontae; Pang, Changhyun; Chae, Heeyeop

    2016-10-01

    Aligned nanofiber arrays and mats were fabricated with an electrospinning process by manipulating the electric field. The electric field was modified by insulating blocks (IBs) that were installed between the nozzle and the substrate as guiding elements to control the trajectory of the electrospinning jet flow. Simulation results showed that the electric field was deformed near the IBs, resulting in confinement of the electrospinning jet between the blocks. The balance of the electric field in the vertical direction and the repulsive force by space charges in the confined electrified jet stream was attributed to the aligned motion of the jet. Aligned arrays of 200 nm thick polyethylene oxide nanofibers were obtained, exhibiting wave-shaped and cross patterns as well as rectilinear patterns. In addition, 40 μm thick quasi-aligned carbon-nanofiber mats with anisotropic electrical property were also attained by this method.

  12. Ultralow turnoff loss dual-gate SOI LIGBT with trench gate barrier and carrier stored layer

    NASA Astrophysics Data System (ADS)

    He, Yi-Tao; Qiao, Ming; Zhang, Bo

    2016-12-01

    A novel ultralow turnoff loss dual-gate silicon-on-insulator (SOI) lateral insulated gate bipolar transistor (LIGBT) is proposed. The proposed SOI LIGBT features an extra trench gate inserted between the p-well and n-drift, and an n-type carrier stored (CS) layer beneath the p-well. In the on-state, the extra trench gate acts as a barrier, which increases the carrier density at the cathode side of n-drift region, resulting in a decrease of the on-state voltage drop (Von). In the off-state, due to the uniform carrier distribution and the assisted depletion effect induced by the extra trench gate, large number of carriers can be removed at the initial turnoff process, contributing to a low turnoff loss (Eoff). Moreover, owing to the dual-gate field plates and CS layer, the carrier density beneath the p-well can greatly increase, which further improves the tradeoff between Eoff and Von. Simulation results show that Eoff of the proposed SOI LIGBT can decrease by 77% compared with the conventional trench gate SOI LIGBT at the same Von of 1.1 V. Project supported by the National Natural Science Foundation of China (Grant Nos. 61376080 and 61674027) and the Natural Science Foundation of Guangdong Province, China (Grant Nos. 2014A030313736 and 2016A030311022).

  13. Gap-gate field effect gas sensing device for chemical image generation

    NASA Astrophysics Data System (ADS)

    Filippini, D.; Lundström, I.; Uchida, H.

    2004-04-01

    A field effect chemically sensitive device, specially suited for the generation of scanning light pulse technique chemical images, is demonstrated. The present approach provides a complete separation between the required electrical biasing and chemical sensing functions inherently coupled in all previous systems. The concept is demonstrated by sensing hydrogen with insensitive biasing electrodes, composing a so-called gap gate, combined with discontinuous palladium clusters usually unsuitable for sensing in conventional arrangements. A simple one-dimensional model is used to explain the observed behavior.

  14. Hardware Implementation of a Lossless Image Compression Algorithm Using a Field Programmable Gate Array

    NASA Astrophysics Data System (ADS)

    Klimesh, M.; Stanton, V.; Watola, D.

    2000-10-01

    We describe a hardware implementation of a state-of-the-art lossless image compression algorithm. The algorithm is based on the LOCO-I (low complexity lossless compression for images) algorithm developed by Weinberger, Seroussi, and Sapiro, with modifications to lower the implementation complexity. In this setup, the compression itself is performed entirely in hardware using a field programmable gate array and a small amount of random access memory. The compression speed achieved is 1.33 Mpixels/second. Our algorithm yields about 15 percent better compression than the Rice algorithm.

  15. Self-Aligned Integrally Gated Nanofilament Field Emitter Cell and Array

    DTIC Science & Technology

    2001-03-09

    composed of carbon nanotubes , alternate nanofilaments may be nanowires composed of Si, Ge, SiC, GaAs, GaP, InAs, InP, ZnS, ZnSe, CdS, CdSe, MoS2 , WS2...integrally gated, self-aligned field emitter cell and array whose cathode is formed of a recently discovered class of materials of nanotubes and...nanotechnology have resulted in the creation of nanofilaments including nanotubes . One such example is carbon nanotubes . These nanotubes behave like

  16. Plasmon-controlled optimum gate bias for GaN heterostructure field-effect transistors

    NASA Astrophysics Data System (ADS)

    Šimukovič, A.; Matulionis, A.; Liberis, J.; Šermukšnis, E.; Sakalas, P.; Zhang, F.; Leach, J. H.; Avrutin, V.; Morkoç, H.

    2013-05-01

    Electron density-dependent dc, rf and power characteristics are investigated for nearly lattice-matched InAlN/AlN/GaN heterostructure field-effect transistors (HFETs). The best performance in respect to transconductance and cutoff frequency is demonstrated at the optimal gate bias of -8 V for the devices with electron sheet density of 3 × 1013 cm-2 (measured on Hall bars of as-grown heterostructures). The results are in fair agreement with the universal bias-density relation controlled by the plasmon-assisted ultrafast decay of nonequilibrium optical phonons launched by hot electrons.

  17. High-resolution full-field spatial coherence gated optical tomography using monochromatic light source

    NASA Astrophysics Data System (ADS)

    Srivastava, Vishal; Nandy, Sreyankar; Singh Mehta, Dalip

    2013-09-01

    We demonstrate dispersion free, high-resolution full-field spatial coherence gated optical tomography using spatially incoherent monochromatic light source. Spatial coherence properties of light source were synthesized by means of combining a static diffuser and vibrating multi mode fiber bundle. Due to low spatial coherence of light source, the axial resolution of the system was achieved similar to that of conventional optical coherence tomography which utilizes low temporal coherence. Experimental results of fringe visibility versus optical path difference are presented for varying numerical apertures objective lenses. High resolution optically sectioned images of multilayer onion skin, and red blood cells are presented.

  18. A control system based on field programmable gate array for papermaking sewage treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Zi Sheng; Xie, Chang; Qing Xiong, Yan; Liu, Zhi Qiang; Li, Qing

    2013-03-01

    A sewage treatment control system is designed to improve the efficiency of papermaking wastewater treatment system. The automation control system is based on Field Programmable Gate Array (FPGA), coded with Very-High-Speed Integrate Circuit Hardware Description Language (VHDL), compiled and simulated with Quartus. In order to ensure the stability of the data used in FPGA, the data is collected through temperature sensors, water level sensor and online PH measurement system. The automatic control system is more sensitive, and both the treatment efficiency and processing power are increased. This work provides a new method for sewage treatment control.

  19. Note: The design of thin gap chamber simulation signal source based on field programmable gate array

    SciTech Connect

    Hu, Kun; Wang, Xu; Li, Feng; Jin, Ge; Lu, Houbing; Liang, Futian

    2015-01-15

    The Thin Gap Chamber (TGC) is an important part of ATLAS detector and LHC accelerator. Targeting the feature of the output signal of TGC detector, we have designed a simulation signal source. The core of the design is based on field programmable gate array, randomly outputting 256-channel simulation signals. The signal is generated by true random number generator. The source of randomness originates from the timing jitter in ring oscillators. The experimental results show that the random number is uniform in histogram, and the whole system has high reliability.

  20. Design and test of field programmable gate arrays in space applications

    NASA Technical Reports Server (NTRS)

    Mckerracher, Priscilla L.; Cain, Russel P.; Barnett, Jon C.; Green, William S.; Kinnison, James D.

    1992-01-01

    Field Programmable Gate Arrays (FPGAU's) offer substantial benefits in terms of flexibility and design integration. In addition to qualifying this device for space applications by establishing its reliability and evaluating its sensitivity to radiation, screening the programmed devices with Automatic Test Equipment (ATE) and functional burn-in presents an interesting challenge. This paper presents a review of the design, qualification, and screening cycle employed for FPGA designs in a space program, and demonstrates the need for close interaction between design and test engineers.

  1. Architecture optimization of nanobridge-based field-programmable gate array and its evaluation

    NASA Astrophysics Data System (ADS)

    Bai, Xu; Sakamoto, Toshitsugu; Tsuji, Yukihide; Miyamura, Makoto; Morioka, Ayuka; Nebashi, Ryusuke; Tada, Munehiro; Banno, Naoki; Okamoto, Koichiro; Iguchi, Noriyuki; Hada, Hiromitsu; Sugibayashi, Tadahiko

    2017-04-01

    Logic cell architecture on nanobridge-based field-programmable gate array (NB-FPGA) is investigated in terms of cell area and signal delay. Area-delay product is minimized when the cluster size is 4 and the segment length is 4, because of small area and small capacitance of nanobridge (NB). 1.34× logic density improvement and 15% energy saving, compared to the previous NB-FPGA with cluster size = 2, are demonstrated by implementing an application of a lightweight block cipher.

  2. Electrolyte-gated graphene field-effect transistors for detecting pH and protein adsorption.

    PubMed

    Ohno, Yasuhide; Maehashi, Kenzo; Yamashiro, Yusuke; Matsumoto, Kazuhiko

    2009-09-01

    We investigated electrolyte-gated graphene field-effect transistors (GFETs) for electrical detecting pH and protein adsorptions. Nonfunctionalized single-layer graphene was used as a channel. GFETs immersed in an electrolyte showed transconductances 30 times higher than those in a vacuum and their conductances exhibited a direct linear increase with electrolyte pH, indicating their potential for use in pH sensor applications. We also attempted to direct surface-protein adsorption and showed that the conductance of GFETs increased with exposure to a protein at several hundred picomolar. The GFETs thus acted as highly sensitive electrical sensors for detecting pH and biomolecule concentrations.

  3. Reprogrammable field programmable gate array with integrated system for mitigating effects of single event upsets

    NASA Technical Reports Server (NTRS)

    Ng, Tak-kwong (Inventor); Herath, Jeffrey A. (Inventor)

    2010-01-01

    An integrated system mitigates the effects of a single event upset (SEU) on a reprogrammable field programmable gate array (RFPGA). The system includes (i) a RFPGA having an internal configuration memory, and (ii) a memory for storing a configuration associated with the RFPGA. Logic circuitry programmed into the RFPGA and coupled to the memory reloads a portion of the configuration from the memory into the RFPGA's internal configuration memory at predetermined times. Additional SEU mitigation can be provided by logic circuitry on the RFPGA that monitors and maintains synchronized operation of the RFPGA's digital clock managers.

  4. Field programmable gate array-assigned complex-valued computation and its limits

    SciTech Connect

    Bernard-Schwarz, Maria; Zwick, Wolfgang; Klier, Jochen; Wenzel, Lothar; Gröschl, Martin

    2014-09-15

    We discuss how leveraging Field Programmable Gate Array (FPGA) technology as part of a high performance computing platform reduces latency to meet the demanding real time constraints of a quantum optics simulation. Implementations of complex-valued operations using fixed point numeric on a Virtex-5 FPGA compare favorably to more conventional solutions on a central processing unit. Our investigation explores the performance of multiple fixed point options along with a traditional 64 bits floating point version. With this information, the lowest execution times can be estimated. Relative error is examined to ensure simulation accuracy is maintained.

  5. Very Low-Voltage Operation of Ionic Liquid-Gated n-Type Organic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Uemura, Takafumi; Yamagishi, Masakazu; Ono, Shimpei; Takeya, Jun

    2010-01-01

    n-Type organic field-effect transistors are operated with high transconductance at very low gate voltage using ionic-liquid electrolyte for the gating layers. Tetracyanoquinodimethane single crystals and C60 thin films are respectively interfaced with ionic liquid of 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide known for its low viscosity and high ionic conductivity, so that high-density electrons are rapidly accumulated in the semiconductor surfaces. The transistors are gated by high electric field confined to a molecular scale Helmholtz layer with the application of minimum gate voltages. The high-transconductance single-crystal device exhibits excellent air stability and the C60 thin-film transistor has realized the highest normalized transconductance among reported n-type organic transistors, together with remarkable improvement in threshold voltage as compared with that in conventional SiO2 devices.

  6. The origin of excellent gate-bias stress stability in organic field-effect transistors employing fluorinated-polymer gate dielectrics.

    PubMed

    Kim, Jiye; Jang, Jaeyoung; Kim, Kyunghun; Kim, Haekyoung; Kim, Se Hyun; Park, Chan Eon

    2014-11-12

    Tuning of the energetic barriers to charge transfer at the semiconductor/dielectric interface in organic field-effect transistors (OFETs) is achieved by varying the dielectric functionality. Based on this, the correlation between the magnitude of the energy barrier and the gate-bias stress stability of the OFETs is demonstrated, and the origin of the excellent device stability of OFETs employing fluorinated dielectrics is revealed.

  7. Non-abelian gauge fields and topological insulators in shaken optical lattices.

    PubMed

    Hauke, Philipp; Tieleman, Olivier; Celi, Alessio; Olschläger, Christoph; Simonet, Juliette; Struck, Julian; Weinberg, Malte; Windpassinger, Patrick; Sengstock, Klaus; Lewenstein, Maciej; Eckardt, André

    2012-10-05

    Time-periodic driving like lattice shaking offers a low-demanding method to generate artificial gauge fields in optical lattices. We identify the relevant symmetries that have to be broken by the driving function for that purpose and demonstrate the power of this method by making concrete proposals for its application to two-dimensional lattice systems: We show how to tune frustration and how to create and control band touching points like Dirac cones in the shaken kagome lattice. We propose the realization of a topological and a quantum spin Hall insulator in a shaken spin-dependent hexagonal lattice. We describe how strong artificial magnetic fields can be achieved for example in a square lattice by employing superlattice modulation. Finally, exemplified on a shaken spin-dependent square lattice, we develop a method to create strong non-abelian gauge fields.

  8. G4-FETs as Universal and Programmable Logic Gates

    NASA Technical Reports Server (NTRS)

    Johnson, Travis; Fijany, Amir; Mojarradi, Mohammad; Vatan, Farrokh; Toomarian, Nikzad; Kolawa, Elizabeth; Cristoloveanu, Sorin; Blalock, Benjamin

    2007-01-01

    An analysis of a patented generic silicon- on-insulator (SOI) electronic device called a G4-FET has revealed that the device could be designed to function as a universal and programmable logic gate. The universality and programmability could be exploited to design logic circuits containing fewer discrete components than are required for conventional transistor-based circuits performing the same logic functions. A G4-FET is a combination of a junction field-effect transistor (JFET) and a metal oxide/semiconductor field-effect transistor (MOSFET) superimposed in a single silicon island and can therefore be regarded as two transistors sharing the same body. A G4-FET can also be regarded as a single transistor having four gates: two side junction-based gates, a top MOS gate, and a back gate activated by biasing of the SOI substrate. Each of these gates can be used to control the conduction characteristics of the transistor; this possibility creates new options for designing analog, radio-frequency, mixed-signal, and digital circuitry. With proper choice of the specific dimensions for the gates, channels, and ancillary features of the generic G4-FET, the device could be made to function as a three-input, one-output logic gate. As illustrated by the truth table in the top part of the figure, the behavior of this logic gate would be the inverse (the NOT) of that of a majority gate. In other words, the device would function as a NOT-majority gate. By simply adding an inverter, one could obtain a majority gate. In contrast, to construct a majority gate in conventional complementary metal oxide/semiconductor (CMOS) circuitry, one would need four three-input AND gates and a four-input OR gate, altogether containing 32 transistors.

  9. Poly(methyl methacrylate) as a self-assembled gate dielectric for graphene field-effect transistors

    SciTech Connect

    Sanne, A.; Movva, H. C. P.; Kang, S.; McClellan, C.; Corbet, C. M.; Banerjee, S. K.

    2014-02-24

    We investigate poly(methyl methacrylate) (PMMA) as a low thermal budget organic gate dielectric for graphene field effect-transistors (GFETs) based on a simple process flow. We show that high temperature baking steps above the glass transition temperature (∼130 °C) can leave a self-assembled, thin PMMA film on graphene, where we get a gate dielectric almost for “free” without additional atomic layer deposition type steps. Electrical characterization of GFETs with PMMA as a gate dielectric yields a dielectric constant of k = 3.0. GFETs with thinner PMMA dielectrics have a lower dielectric constant due to decreased polarization arising from neutralization of dipoles and charged carriers as baking temperatures increase. The leakage through PMMA gate dielectric increases with decreasing dielectric thickness and increasing electric field. Unlike conventional high-k gate dielectrics, such low-k organic gate dielectrics are potentially attractive for devices such as the proposed Bilayer pseudoSpin Field-Effect Transistor or flexible high speed graphene electronics.

  10. Metal-insulator-transition in SrTiO3 induced by argon bombardment combined with field effect

    SciTech Connect

    Xu, Jie; Zhu, Zhengyong; Zhao, Hengliang; Luo, Zhijiong

    2014-12-15

    By fabricating the Field-Effect-Transistors on argon bombardment SrTiO3 substrates, not only we have achieved one of the best mobility for Field-Effect-Transistors fabricated on SrTiO3, but also realized strong field induced Metal-Insulator-Transition. The critical sheet resistance for the Metal-Insulator-Transition is only 1/7 of the value obtained in the former experiments, indicating a different mechanism. Further study shows that the Metal-Insulator-Transition can be attributed to the oxygen vacancies formed after the bombardment becoming the electron donor under the electric field modulation, increasing SrTiO3 surface electron density and transforming the substrate into metallic state.

  11. Self-modulated field electron emitter: Gated device of integrated Si tip-on-nano-channel

    NASA Astrophysics Data System (ADS)

    Huang, Zhijun; Huang, Yifeng; Pan, Zhangxu; She, Juncong; Deng, Shaozhi; Chen, Jun; Xu, Ningsheng

    2016-12-01

    We report the featured gated field electron emission devices of Si nano-tips with individually integrated Si nano-channels and the interpretation of the related physics. A rational procedure was developed to fabricate the uniform integrated devices. The electrical and thermal conduction tests demonstrated that the Si nano-channel can limit both the current and heat flows. The integrated devices showed the specialties of self-enhancement and self-regulation. The heat resistance results in the heat accumulation at the tip-apex, inducing the thermally enhanced field electron emission. The self-regulated effect of the electrical resistance is benefit for impeding the current overloading and prevents the emitters from a catastrophic breakdown. The nano-channel-integrated Si nano-tip array exhibited emission current density up to 24.9 mA/cm2 at a gate voltage of 94 V, much higher than that of the Si nano-tip array without an integrated nano-channel.

  12. Mobility overestimation due to gated contacts in organic field-effect transistors

    PubMed Central

    Bittle, Emily G.; Basham, James I.; Jackson, Thomas N.; Jurchescu, Oana D.; Gundlach, David J.

    2016-01-01

    Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current–voltage characteristics and interpreted by using the classical metal oxide–semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm2 V−1 s−1), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current–voltage characterization are overestimated by one order of magnitude or more. PMID:26961271

  13. Gate field plate IGBT with trench accumulation layer for extreme injection enhancement

    NASA Astrophysics Data System (ADS)

    Xu, Xiaorui; Chen, Wanjun; Liu, Chao; Chen, Nan; Tao, Hong; Shi, Yijun; Ma, Yinchang; Zhou, Qi; Zhang, Bo

    2017-04-01

    A gate field plate IGBT (GFP-IGBT) with extreme injection enhancement is proposed and verified using TCAD simulations. The GFP-IGBT features a gate field plate (GFP) inserted into n-drift region directly and a tiny P-base region separated from the GFP. In the ON-state, the accumulation layer is formed near to not only the bottom but also the side of the trench, which enhances electron injection efficiency. And the tiny P-base region reduces the holes extracted by reverse-biased P-base/N-drift junction. Both the GFP and tiny P-base contribute to achieving extreme injection enhancement, leading to a low forward voltage drop. In the OFF-state, due to the low stored charges in N-buffer layer, GFP-IGBT shows a short current fall time, leading to a decrease of turn-off loss. The simulation results show that, compared with the conventional IGBT, the GFP-IGBT offers a forward voltage drop reduction of 25% or current fall time reduction of 89% (i.e. turn-off loss reduction of 53%), resulting in low power loss. The excellent device performance, coupled with a commercial IGBT-compatible fabrication process, makes the proposed GFP-IGBT a promising candidate for power switching applications.

  14. Molecular gating of silicon nanowire field-effect transistors with nonpolar analytes.

    PubMed

    Paska, Yair; Stelzner, Thomas; Assad, Ossama; Tisch, Ulrike; Christiansen, Silke; Haick, Hossam

    2012-01-24

    Silicon nanowire field-effect transistors (Si NW FETs) have been used as powerful sensors for chemical and biological species. The detection of polar species has been attributed to variations in the electric field at the conduction channel due to molecular gating with polar molecules. However, the detection of nonpolar analytes with Si NW FETs has not been well understood to date. In this paper, we experimentally study the detection of nonpolar species and model the detection process based on changes in the carrier mobility, voltage threshold, off-current, off-voltage, and subthreshold swing of the Si NW FET. We attribute the detection of the nonpolar species to molecular gating, due to two indirect effects: (i) a change in the dielectric medium close to the Si NW surface and (ii) a change in the charged surface states at the functionality of the Si NW surface. The contribution of these two effects to the overall measured sensing signal is determined and discussed. The results provide a launching pad for real-world sensing applications, such as environmental monitoring, homeland security, food quality control, and medicine.

  15. Probing top-gated field effect transistor of reduced graphene oxide monolayer made by dielectrophoresis

    NASA Astrophysics Data System (ADS)

    Vasu, K. S.; Chakraborty, Biswanath; Sampath, S.; Sood, A. K.

    2010-08-01

    We demonstrate a top-gated field effect transistor made of a reduced graphene oxide (RGO) monolayer (graphene) by dielectrophoresis. The Raman spectrum of RGO flakes of typical size of 5 μm×5 μm shows a single 2D band at 2687 cm -1, characteristic of single-layer graphene. The two-probe current-voltage measurements of RGO flakes, deposited in between the patterned electrodes with a gap of 2.5 μm using ac dielectrophoresis, show ohmic behavior with a resistance of ˜37 kΩ. The temperature dependence of the resistance (R) of RGO measured between 305 K and 393 K yields a temperature coefficient of resistance [dR/dT]/R˜-9.5×10-4/K, the same as that of mechanically exfoliated single-layer graphene. The field-effect transistor action was obtained by electrochemical top-gating using a solid polymer electrolyte (PEO+LiClO 4) and Pt wire. The ambipolar nature of graphene flakes is observed up to a doping level of ˜6×1012/cm and carrier mobility of ˜50 cm 2/V s. The source-drain current characteristics show a tendency of current saturation at high source-drain voltage which is analyzed quantitatively by a diffusive transport model.

  16. Investigation of an anomalous hump in gate current after negative-bias temperature-instability in HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors

    NASA Astrophysics Data System (ADS)

    Ho, Szu-Han; Chang, Ting-Chang; Wu, Chi-Wei; Lo, Wen-Hung; Chen, Ching-En; Tsai, Jyun-Yu; Liu, Guan-Ru; Chen, Hua-Mao; Lu, Ying-Shin; Wang, Bin-Wei; Tseng, Tseung-Yuen; Cheng, Osbert; Huang, Cheng-Tung; Sze, Simon M.

    2013-01-01

    This Letter investigates a hump in gate current after negative-bias temperature-instability (NBTI) in HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. Measuring gate current at initial through body floating and source/drain floating shows that hole current flows from source/drain. The fitting of gate current (Ig)-gate voltage (Vg) characteristic curves demonstrates that the Frenkel-Poole mechanism dominates the conduction. Next, by fitting the gate current after NBTI, in the order of Frenkel-Poole then tunneling, the Frenkel-Poole mechanism can be confirmed. These phenomena can be attributed to hole trapping in high-k bulk and the electric field formula Ehigh-k ɛhigh-k = Q + Esio2ɛsio2.

  17. Analysis of an anomalous hump in gate current after dynamic negative bias stress in HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors

    NASA Astrophysics Data System (ADS)

    Ho, Szu-Han; Chang, Ting-Chang; Wu, Chi-Wei; Lo, Wen-Hung; Chen, Ching-En; Tsai, Jyun-Yu; Luo, Hung-Ping; Tseng, Tseung-Yuen; Cheng, Osbert; Huang, Cheng-Tung; Sze, Simon M.

    2012-07-01

    This letter investigates a hump in gate current after dynamic negative bias stress (NBS) in HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. By measuring gate current under initial through body floating and source/drain floating, it shows that hole current flows from source/drain. The fitting of gate current-gate voltage characteristic curve demonstrates that Frenkel-Poole mechanism dominates the conduction. Next, by fitting the gate current after dynamic NBS, in the order of Frenkel-Poole then tunneling, the Frenkel-Poole mechanism can be confirmed. These phenomena can be attributed to hole trapping in high-k bulk and the electric field formula Ehigh-k ɛhigh-k = Q + Esio2ɛsio2.

  18. A Full electric-field tuning of thermoelectric power in a dual-gated Bi-layer graphene device

    NASA Astrophysics Data System (ADS)

    Lee, Wei-Li; Wang, Chang-Ran; Lu, Wen-Sen; Hao, Lei; Lee, Ting-Kuo; Lin, Feng; Cheng, I.-Chun; Chen, Jiang-Zhang

    2012-02-01

    By using high quality microcrystals of hexagonal boron nitride as top gate dielectric, we fabricated dual-gated bilayer graphene devices. We demonstrate a full electric field tuning of thermoelectric power resulting from the opening of a band-gap by applying a perpendicular electric field on bilayer graphene. We uncover a large enhancement in thermoelectric power at low temperature. At 15 K, the thermoelectric power can be amplified by more than four-fold attaining a value of ˜ 50μV/K at a displacement field of 0.8 V/nm. Our result may open up a new possibility in thermoelectric application using graphene-based device.

  19. Controlling chaos with magnetic field in semi-insulating GaAs

    SciTech Connect

    Oliveira, A. G. de; Ribeiro, G. M.; Moreira, M. V. B.; Gonzalez, J. C.; Silva, R. L. da; Rubinger, R. M.

    2007-10-15

    Chaos control has stimulated a large amount of work. We have studied the effect of an external parallel magnetic field on the low-frequency current oscillations observed on a molecular beam epitaxy GaAs sample grown at 265 deg. C, and we have shown that it can be efficiently used for chaos control. The study of the magnetoresistance indicates that the effect of the magnetic field on the charges of the hopping conduction mechanism induces changes in the low-frequency oscillations. Due to this, we have used the magnetic field to control chaos assessed through direct observation low-frequency oscillations, their attractors, and bifurcation diagrams. We also found that the magnetic field interferes indirectly with the Coulombian interaction between the free charges in the conduction band and the hopping carriers, as well as with the recombination mechanism of field enhanced trapping. Controlling the low-frequency oscillations in semi-insulating GaAs by means of an external magnetic field permits probing the interaction of the slow hopping carriers and the fast free carriers in the electric-field domains.

  20. Chiral Spin Liquids in Triangular-Lattice SU (N ) Fermionic Mott Insulators with Artificial Gauge Fields

    NASA Astrophysics Data System (ADS)

    Nataf, Pierre; Lajkó, Miklós; Wietek, Alexander; Penc, Karlo; Mila, Frédéric; Läuchli, Andreas M.

    2016-10-01

    We show that, in the presence of a π /2 artificial gauge field per plaquette, Mott insulating phases of ultracold fermions with SU (N ) symmetry and one particle per site generically possess an extended chiral phase with intrinsic topological order characterized by an approximate ground space of N low-lying singlets for periodic boundary conditions, and by chiral edge states described by the SU(N ) 1 Wess-Zumino-Novikov-Witten conformal field theory for open boundary conditions. This has been achieved by extensive exact diagonalizations for N between 3 and 9, and by a parton construction based on a set of N Gutzwiller projected fermionic wave functions with flux π /N per triangular plaquette. Experimental implications are briefly discussed.

  1. Simulation of Electric Field in Semi Insulating Au/CdTe/Au Detector under Flux

    SciTech Connect

    Franc, J.; James, R.; Grill, R.; Kubat, J.; Belas, E.; Hoschl, P.; Moravec, P.; Praus, P.

    2009-08-02

    We report our simulations on the profile of the electric field in semi insulating CdTe and CdZnTe with Au contacts under radiation flux. The type of the space charge and electric field distribution in the Au/CdTe/Au structure is at high fluxes result of a combined influence of charge formed due to band bending at the electrodes and from photo generated carriers, which are trapped at deep levels. Simultaneous solution of drift-diffusion and Poisson equations is used for the calculation. We show, that the space charge originating from trapped photo-carriers starts to dominate at fluxes 10{sup 15}-10{sup 16}cm{sup -2}s{sup -1}, when the influence of contacts starts to be negligible.

  2. Effective exchange fields in spin-torque resonance of magnetic insulators

    NASA Astrophysics Data System (ADS)

    Chiba, Takahiro; Bauer, Gerrit E. W.; Takahashi, Saburo

    2016-02-01

    We report additional results on the spin-torque ferromagnetic resonance (ST-FMR) of a bilayer system made from a magnetic insulator such as Y3 Fe5 O12 (YIG) and a heavy normal metal such as Pt in terms of the interface spin-mixing conductance and including spin pumping. We analyze experimental ST-FMR spectra for out-of-plane and in-plane magnetization configurations in terms of an anisotropic imaginary part Gi of the mixing conductance (or interface effective field). The estimated ratio between imaginary and real parts Gi /Gr ≲ 0.3 is sensitive to an (unknown) phase shift between microwave current bias and associated Oersted field.

  3. Steep switching characteristics of single-gated feedback field-effect transistors

    NASA Astrophysics Data System (ADS)

    Kim, Minsuk; Kim, Yoonjoong; Lim, Doohyeok; Woo, Sola; Cho, Kyoungah; Kim, Sangsig

    2017-02-01

    In this study, we propose newly designed feedback field-effect transistors that utilize the positive feedback of charge carriers in single-gated silicon channels to achieve steep switching behaviors. The band diagram, I-V characteristics, subthreshold swing, and on/off current ratio are analyzed using a commercial device simulator. Our proposed feedback field-effect transistors exhibit subthreshold swings of less than 0.1 mV dec-1, an on/off current ratio of approximately 1011, and an on-current of approximately 10-4 A at room temperature, demonstrating that the switching characteristics are superior to those of other silicon-based devices. In addition, the device parameters that affect the device performance, hysteresis characteristics, and temperature-dependent device characteristics are discussed in detail.

  4. Quantum logic gates from time-dependent global magnetic field in a system with constant exchange

    SciTech Connect

    Nenashev, A. V. Dvurechenskii, A. V.; Zinovieva, A. F.; Gornov, A. Yu.; Zarodnyuk, T. S.

    2015-03-21

    We propose a method that implements a universal set of one- and two-quantum-bit gates for quantum computation in a system of coupled electron pairs with constant non-diagonal exchange interaction. In our proposal, suppression of the exchange interaction is performed by the continual repetition of single-spin rotations. A small g-factor difference between the electrons allows for addressing qubits and avoiding strong magnetic field pulses. Numerical experiments were performed to show that, to implement the one- and two-qubit operations, it is sufficient to change the strength of the magnetic field by a few Gauss. This introduces one and then the other electron in a resonance. To determine the evolution of the two-qubit system, we use the algorithms of optimal control theory.

  5. Theoretical study of electrolyte gate AlGaN /GaN field effect transistors

    NASA Astrophysics Data System (ADS)

    Bayer, M.; Uhl, C.; Vogl, P.

    2005-02-01

    We predict the sensitivity of solution gate AlGaN /GaN field effect transistors to pH values of the electrolyte and to charged adsorbates at the semiconductor-electrolyte interface. Invoking the site-binding model for the chemical reactions at the oxidic semiconductor-electrolyte interface and taking into account the large polarization fields within the nitride heterostructure, the spatial charge and potential distribution have been calculated self-consistently both in the semiconductor and the electrolyte. In addition, the source-drain current is calculated and its sensitivity to the electrolyte's pH value is studied systematically. Comparison with experiment shows good agreement. A significantly enhanced resolution is predicted for AlGaN /GaN structures of N-face polarity.

  6. Realization of a quantum gate using gravitational search algorithm by perturbing three-dimensional harmonic oscillator with an electromagnetic field

    NASA Astrophysics Data System (ADS)

    Sharma, Navneet; Rawat, Tarun Kumar; Parthasarathy, Harish; Gautam, Kumar

    2016-06-01

    The aim of this paper is to design a current source obtained as a representation of p information symbols \\{I_k\\} so that the electromagnetic (EM) field generated interacts with a quantum atomic system producing after a fixed duration T a unitary gate U( T) that is as close as possible to a given unitary gate U_g. The design procedure involves calculating the EM field produced by \\{I_k\\} and hence the perturbing Hamiltonian produced by \\{I_k\\} finally resulting in the evolution operator produced by \\{I_k\\} up to cubic order based on the Dyson series expansion. The gate error energy is thus obtained as a cubic polynomial in \\{I_k\\} which is minimized using gravitational search algorithm. The signal to noise ratio (SNR) in the designed gate is higher as compared to that using quadratic Dyson series expansion. The SNR is calculated as the ratio of the Frobenius norm square of the desired gate to that of the desired gate error.

  7. Nanocrystalline cellulose applied simultaneously as the gate dielectric and the substrate in flexible field effect transistors

    NASA Astrophysics Data System (ADS)

    Gaspar, D.; Fernandes, S. N.; de Oliveira, A. G.; Fernandes, J. G.; Grey, P.; Pontes, R. V.; Pereira, L.; Martins, R.; Godinho, M. H.; Fortunato, E.

    2014-03-01

    Cotton-based nanocrystalline cellulose (NCC), also known as nanopaper, one of the major sources of renewable materials, is a promising substrate and component for producing low cost fully recyclable flexible paper electronic devices and systems due to its properties (lightweight, stiffness, non-toxicity, transparency, low thermal expansion, gas impermeability and improved mechanical properties). Here, we have demonstrated for the first time a thin transparent nanopaper-based field effect transistor (FET) where NCC is simultaneously used as the substrate and as the gate dielectric layer in an ‘interstrate’ structure, since the device is built on both sides of the NCC films; while the active channel layer is based on oxide amorphous semiconductors, the gate electrode is based on a transparent conductive oxide. Such hybrid FETs present excellent operating characteristics such as high channel saturation mobility (>7 cm2 V -1 s-1), drain-source current on/off modulation ratio higher than 105, enhancement n-type operation and subthreshold gate voltage swing of 2.11 V/decade. The NCC film FET characteristics have been measured in air ambient conditions and present good stability, after two weeks of being processed, without any type of encapsulation or passivation layer. The results obtained are comparable to ones produced for conventional cellulose paper, marking this out as a promising approach for attaining high-performance disposable electronics such as paper displays, smart labels, smart packaging, RFID (radio-frequency identification) and point-of-care systems for self-analysis in bioscience applications, among others.

  8. Touch sensors based on planar liquid crystal-gated-organic field-effect transistors

    SciTech Connect

    Seo, Jooyeok; Lee, Chulyeon; Han, Hyemi; Lee, Sooyong; Nam, Sungho; Kim, Youngkyoo; Kim, Hwajeong; Lee, Joon-Hyung; Park, Soo-Young; Kang, Inn-Kyu

    2014-09-15

    We report a tactile touch sensor based on a planar liquid crystal-gated-organic field-effect transistor (LC-g-OFET) structure. The LC-g-OFET touch sensors were fabricated by forming the 10 μm thick LC layer (4-cyano-4{sup ′}-pentylbiphenyl - 5CB) on top of the 50 nm thick channel layer (poly(3-hexylthiophene) - P3HT) that is coated on the in-plane aligned drain/source/gate electrodes (indium-tin oxide - ITO). As an external physical stimulation to examine the tactile touch performance, a weak nitrogen flow (83.3 μl/s) was employed to stimulate the LC layer of the touch device. The LC-g-OFET device exhibited p-type transistor characteristics with a hole mobility of 1.5 cm{sup 2}/Vs, but no sensing current by the nitrogen flow touch was measured at sufficiently high drain (V{sub D}) and gate (V{sub G}) voltages. However, a clear sensing current signal was detected at lower voltages, which was quite sensitive to the combination of V{sub D} and V{sub G}. The best voltage combination was V{sub D} = −0.2 V and V{sub G} = −1 V for the highest ratio of signal currents to base currents (i.e., signal-to-noise ratio). The change in the LC alignment upon the nitrogen flow touch was assigned as the mechanism for the present LC-g-OFET touch sensors.

  9. High-Performance Wrap-Gated InGaAs Nanowire Field-Effect Transistors with Sputtered Dielectrics

    PubMed Central

    Shen, Li-Fan; Yip, SenPo; Yang, Zai-xing; Fang, Ming; Hung, TakFu; Pun, Edwin Y.B.; Ho, Johnny C.

    2015-01-01

    Although wrap-gated nanowire field-effect-transistors (NWFETs) have been explored as an ideal electronic device geometry for low-power and high-frequency applications, further performance enhancement and practical implementation are still suffering from electron scattering on nanowire surface/interface traps between the nanowire channel and gate dielectric as well as the complicated device fabrication scheme. Here, we report the development of high-performance wrap-gated InGaAs NWFETs using conventional sputtered Al2O3 layers as gate dielectrics, instead of the typically employed atomic layer deposited counterparts. Importantly, the surface chemical passivation of NW channels performed right before the dielectric deposition is found to significantly alleviate plasma induced defect traps on the NW channel. Utilizing this passivation, the wrap-gated device exhibits superior electrical performances: a high ION/IOFF ratio of ~2 × 106, an extremely low sub-threshold slope of 80 mV/decade and a peak field-effect electron mobility of ~1600 cm2/(Vs) at VDS = 0.1 V at room temperature, in which these values are even better than the ones of state-of-the-art NWFETs reported so far. By combining sputtering and pre-deposition chemical passivation to achieve high-quality gate dielectrics for wrap-gated NWFETs, the superior gate coupling and electrical performances have been achieved, confirming the effectiveness of our hybrid approach for future advanced electronic devices. PMID:26607169

  10. Human aquaporin 4 gating dynamics in dc and ac electric fields: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Garate, J.-A.; English, Niall J.; MacElroy, J. M. D.

    2011-02-01

    Water self-diffusion within human aquaporin 4 has been studied using molecular dynamics (MD) simulations in the absence and presence of external ac and dc electric fields. The computed diffusive (pd) and osmotic (pf) permeabilities under zero-field conditions are (0.718 ± 0.24) × 10-14 cm3 s-1 and (2.94 ± 0.47) × 10-14 cm3 s-1, respectively; our pf agrees with the experimental value of (1.50 ± 0.6) × 10-14 cm3 s-1. A gating mechanism has been proposed in which side-chain dynamics of residue H201, located in the selectivity filter, play an essential role. In addition, for nonequilibrium MD in external fields, it was found that water dipole orientation within the constriction region of the channel is affected by electric fields (e-fields) and that this governs the permeability. It was also found that the rate of side-chain flipping motion of residue H201 is increased in the presence of e-fields, which influences water conductivity further.

  11. Prediction and Measurement of Temperature Fields in Silicon-on-Insulator Electronic Circuits

    DTIC Science & Technology

    1995-08-01

    1442-1447. Touloukian , Y. S., Powell, R. W., Ho, C. Y., and Klemens, P. G.. 1971), "Thermal Conductivity: Metallic Elements and Alloys ," in: Thermol... property or dimension = average temperature rise in of source and drain gate, K f = property or dimension = maximum interconnect temper- of fin...ature, K g = property or dimension = substrate temperature, K of gate = voltage drop along gate, V m = property or dimension = gate-source voltage

  12. Field evaluation of 69-kV outdoor Polysil insulators. Final report

    SciTech Connect

    Richenbacher, A.G.

    1985-03-01

    After three years of exposure to widely varying climates and environments, Polysil (polymer concrete) 69-kV post-type insulators are still performing satisfactorily. In all test situations, Polysil insulators performed as well as - sometimes even surpassed - their porcelain counterparts. They also demonstrated potential for substantially reducing insulator costs.

  13. Single trap dynamics in electrolyte-gated Si-nanowire field effect transistors

    SciTech Connect

    Pud, S.; Li, J.; Offenhäusser, A.; Vitusevich, S. A.; Gasparyan, F.; Petrychuk, M.

    2014-06-21

    Liquid-gated silicon nanowire (NW) field effect transistors (FETs) are fabricated and their transport and dynamic properties are investigated experimentally and theoretically. Random telegraph signal (RTS) fluctuations were registered in the nanolength channel FETs and used for the experimental and theoretical analysis of transport properties. The drain current and the carrier interaction processes with a single trap are analyzed using a quantum-mechanical evaluation of carrier distribution in the channel and also a classical evaluation. Both approaches are applied to treat the experimental data and to define an appropriate solution for describing the drain current behavior influenced by single trap resulting in RTS fluctuations in the Si NW FETs. It is shown that quantization and tunneling effects explain the behavior of the electron capture time on the single trap. Based on the experimental data, parameters of the single trap were determined. The trap is located at a distance of about 2 nm from the interface Si/SiO{sub 2} and has a repulsive character. The theory of dynamic processes in liquid-gated Si NW FET put forward here is in good agreement with experimental observations of transport in the structures and highlights the importance of quantization in carrier distribution for analyzing dynamic processes in the nanostructures.

  14. Magnetic Field-Tuned Superconductor-Insulator Transition in One-Dimensional Arrays of Small Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Kuo, Watson; Chen, C. D.

    2003-03-01

    We have studied experimentally the magnetic field induced superconductor-insulator quantum phase transition in one-dimensional arrays of small Josephson junctions. It is found that the critical magnetic field that separates the two phases corresponds to the onset of Coulomb blockade of Cooper pairs tunneling in the current-voltage characteristics. The resistance data are analyzed in the context of the superfluid-insulator transition in one dimension. Combining results from Haviland et. al.,2 we construct an experimental phase diagram using Josepshon coupling-to-charging energy ratio(EJ/ECP) and dissipation strength.

  15. SUPERGLASS. Engineering field tests - Phase 3. Production, market planning, and product evaluation for a high-thermal-performance insulating glass design utilizing HEAT MIRROR transparent insulation. Final report

    SciTech Connect

    Tilford, C L

    1982-11-01

    HEAT MIRROR transparent window insulation consists of a clear polyester film two mils (.002'') thick with a thin, clear low-emissivity (.15) coating deposited on one side by state-of-the-art vacuum deposition processes. This neutral-colored invisible coating reflects long-wave infrared energy (heat). When mounted by being stretched with a 1/2'' air-gap on each side of the film, the resulting unit reduces heat loss by 60% compared to dual insulating glass. Southwall Corporation produces HEAT MIRROR transparent insulation and markets it to manufacturers of sealed insulating glass (I.G.) units and window and building manufacturers who make their own I.G. These companies build and sell the SUPERGLASS sealed glazing units. Units made and installed in buildings by six customers were visited. These units were located in many geographic regions, including the Pacific Northwest, Rocky Mountains, New England, Southeast, and West Coast. As much as could be obtained of their history was recorded, as was their current condition and performance. These units had been in place from two weeks to over a year. All of the units were performing thermally very well, as measured by taking temperature profiles through them and through adjacent conventional I.G. units. Some units had minor visual defects (attributed to I.G. assembly techniques) which are discussed in detail. Overall occupant acceptance was enthusiastically positive. In addition to saving energy, without compromise of optical quality or appearance, the product makes rooms with large glazing areas comfortable to be in in cold weather. All defects observed were present when built; there appears to be no in-field degradation of quality at this time.

  16. Field Effect Modulation of Ion Transport in Silicon-On-Insulator Nanopores and Their Application as Nanoscale Coulter Counters

    NASA Astrophysics Data System (ADS)

    Joshi, Punarvasu

    In the last few years, significant advances in nanofabrication have allowed tailoring of structures and materials at a molecular level enabling nanofabrication with precise control of dimensions and organization at molecular length scales, a development leading to significant advances in nanoscale systems. Although, the direction of progress seems to follow the path of microelectronics, the fundamental physics in a nanoscale system changes more rapidly compared to microelectronics, as the size scale is decreased. The changes in length, area, and volume ratios due to reduction in size alter the relative influence of various physical effects determining the overall operation of a system in unexpected ways. One such category of nanofluidic structures demonstrating unique ionic and molecular transport characteristics are nanopores. Nanopores derive their unique transport characteristics from the electrostatic interaction of nanopore surface charge with aqueous ionic solutions. In this doctoral research cylindrical nanopores, in single and array configuration, were fabricated in silicon-on-insulator (SOI) using a combination of electron beam lithography (EBL) and reactive ion etching (RIE). The fabrication method presented is compatible with standard semiconductor foundries and allows fabrication of nanopores with desired geometries and precise dimensional control, providing near ideal and isolated physical modeling systems to study ion transport at the nanometer level. Ion transport through nanopores was characterized by measuring ionic conductances of arrays of nanopores of various diameters for a wide range of concentration of aqueous hydrochloric acid (HCl) ionic solutions. Measured ionic conductances demonstrated two distinct regimes based on surface charge interactions at low ionic concentrations and nanopore geometry at high ionic concentrations. Field effect modulation of ion transport through nanopore arrays, in a fashion similar to semiconductor transistors

  17. Silicon-on-insulator field effect transistor with improved body ties for rad-hard applications

    DOEpatents

    Schwank, James R.; Shaneyfelt, Marty R.; Draper, Bruce L.; Dodd, Paul E.

    2001-01-01

    A silicon-on-insulator (SOI) field-effect transistor (FET) and a method for making the same are disclosed. The SOI FET is characterized by a source which extends only partially (e.g. about half-way) through the active layer wherein the transistor is formed. Additionally, a minimal-area body tie contact is provided with a short-circuit electrical connection to the source for reducing floating body effects. The body tie contact improves the electrical characteristics of the transistor and also provides an improved single-event-upset (SEU) radiation hardness of the device for terrestrial and space applications. The SOI FET also provides an improvement in total-dose radiation hardness as compared to conventional SOI transistors fabricated without a specially prepared hardened buried oxide layer. Complementary n-channel and p-channel SOI FETs can be fabricated according to the present invention to form integrated circuits (ICs) for commercial and military applications.

  18. Giant Electroresistance in Edge Metal-Insulator-Metal Tunnel Junctions Induced by Ferroelectric Fringe Fields

    PubMed Central

    Jung, Sungchul; Jeon, Youngeun; Jin, Hanbyul; Lee, Jung-Yong; Ko, Jae-Hyeon; Kim, Nam; Eom, Daejin; Park, Kibog

    2016-01-01

    An enormous amount of research activities has been devoted to developing new types of non-volatile memory devices as the potential replacements of current flash memory devices. Theoretical device modeling was performed to demonstrate that a huge change of tunnel resistance in an Edge Metal-Insulator-Metal (EMIM) junction of metal crossbar structure can be induced by the modulation of electric fringe field, associated with the polarization reversal of an underlying ferroelectric layer. It is demonstrated that single three-terminal EMIM/Ferroelectric structure could form an active memory cell without any additional selection devices. This new structure can open up a way of fabricating all-thin-film-based, high-density, high-speed, and low-power non-volatile memory devices that are stackable to realize 3D memory architecture. PMID:27476475

  19. High-Mobility Transparent SnO2 and ZnO-SnO2 Thin-Film Transistors with SiO2/Al2O3 Gate Insulators

    NASA Astrophysics Data System (ADS)

    Cheong, Woo-Seok; Yoon, Sung-Min; Hwang, Chi-Sun; Chu, Hye Yong

    2009-04-01

    Using a double-layered gate insulator [SiO2 (100 nm)/Al2O3 (10 nm)] and a dry-etching process for the channel layer, we could obtain high mobility top-gate SnO2 and ZnO-SnO2 (ZTO) transparent thin-film transistor (TTFT). After annealing at 300 °C, for 1 h in O2 ambient, the saturated mobility of SnO2 TTFT was 17.4 cm2 s-1 V-1, and that of ZTO TTFT was 50.4 cm2 s-1 V-1. Generally, both devices operated in the enhancement mode with a drain current on-off ratio of ˜106.

  20. A digital optical phase-locked loop for diode lasers based on field programmable gate array.

    PubMed

    Xu, Zhouxiang; Zhang, Xian; Huang, Kaikai; Lu, Xuanhui

    2012-09-01

    We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382∕MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad(2) and transition time of 100 μs under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

  1. A digital optical phase-locked loop for diode lasers based on field programmable gate array

    NASA Astrophysics Data System (ADS)

    Xu, Zhouxiang; Zhang, Xian; Huang, Kaikai; Lu, Xuanhui

    2012-09-01

    We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382/MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad2 and transition time of 100 μs under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

  2. Flux-gate magnetic field sensor based on yttrium iron garnet films for magnetocardiography investigations

    NASA Astrophysics Data System (ADS)

    Vetoshko, P. M.; Gusev, N. A.; Chepurnova, D. A.; Samoilova, E. V.; Syvorotka, I. I.; Syvorotka, I. M.; Zvezdin, A. K.; Korotaeva, A. A.; Belotelov, V. I.

    2016-08-01

    A new type of f lux-gate vector magnetometer based on epitaxial yttrium iron garnet films has been developed and constructed for magnetocardiography (MCG) investigations. The magnetic field sensor can operate at room temperature and measure MCG signals at a distance of about 1 mm from the thoracic cage. The high sensitivity of the sensor, better than 100 fT/Hz1/2, is demonstrated by the results of MCG measurements on rats. The main MCG pattern details and R-peak on a level of 10 pT are observed without temporal averaging, which allows heart rate anomalies to be studied. The proposed magnetic sensors can be effectively used in MCG investigations.

  3. Real-time face detection and lip feature extraction using field-programmable gate arrays.

    PubMed

    Nguyen, Duy; Halupka, David; Aarabi, Parham; Sheikholeslami, Ali

    2006-08-01

    This paper proposes a new technique for face detection and lip feature extraction. A real-time field-programmable gate array (FPGA) implementation of the two proposed techniques is also presented. Face detection is based on a naive Bayes classifier that classifies an edge-extracted representation of an image. Using edge representation significantly reduces the model's size to only 5184 B, which is 2417 times smaller than a comparable statistical modeling technique, while achieving an 86.6% correct detection rate under various lighting conditions. Lip feature extraction uses the contrast around the lip contour to extract the height and width of the mouth, metrics that are useful for speech filtering. The proposed FPGA system occupies only 15050 logic cells, or about six times less than a current comparable FPGA face detection system.

  4. A hardware implementation of artificial neural networks using field programmable gate arrays

    NASA Astrophysics Data System (ADS)

    Won, E.

    2007-11-01

    An artificial neural network algorithm is implemented using a low-cost field programmable gate array hardware. One hidden layer is used in the feed-forward neural network structure in order to discriminate one class of patterns from the other class in real time. In this work, the training of the network is performed in the off-line computing environment and the results of the training are configured to the hardware in order to minimize the latency of the neural computation. With five 8-bit input patterns, six hidden nodes, and one 8-bit output, the implemented hardware neural network makes decisions on a set of input patterns in 11 clock cycles, or less than 200 ns with a 60 MHz clock. The result from the hardware neural computation is well predictable based on the off-line computation. This implementation may be used in level 1 hardware triggers in high energy physics experiments.

  5. Self-Adaptive System based on Field Programmable Gate Array for Extreme Temperature Electronics

    NASA Technical Reports Server (NTRS)

    Keymeulen, Didier; Zebulum, Ricardo; Rajeshuni, Ramesham; Stoica, Adrian; Katkoori, Srinivas; Graves, Sharon; Novak, Frank; Antill, Charles

    2006-01-01

    In this work, we report the implementation of a self-adaptive system using a field programmable gate array (FPGA) and data converters. The self-adaptive system can autonomously recover the lost functionality of a reconfigurable analog array (RAA) integrated circuit (IC) [3]. Both the RAA IC and the self-adaptive system are operating in extreme temperatures (from 120 C down to -180 C). The RAA IC consists of reconfigurable analog blocks interconnected by several switches and programmable by bias voltages. It implements filters/amplifiers with bandwidth up to 20 MHz. The self-adaptive system controls the RAA IC and is realized on Commercial-Off-The-Shelf (COTS) parts. It implements a basic compensation algorithm that corrects a RAA IC in less than a few milliseconds. Experimental results for the cold temperature environment (down to -180 C) demonstrate the feasibility of this approach.

  6. A digital optical phase-locked loop for diode lasers based on field programmable gate array

    SciTech Connect

    Xu Zhouxiang; Zhang Xian; Huang Kaikai; Lu Xuanhui

    2012-09-15

    We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382/MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad{sup 2} and transition time of 100 {mu}s under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

  7. Field Programmable Gate Array for Implementation of Redundant Advanced Digital Feedback Control

    NASA Technical Reports Server (NTRS)

    King, K. D.

    2003-01-01

    The goal of this effort was to develop a digital motor controller using field programmable gate arrays (FPGAs). This is a more rugged approach than a conventional microprocessor digital controller. FPGAs typically have higher radiation (rad) tolerance than both the microprocessor and memory required for a conventional digital controller. Furthermore, FPGAs can typically operate at higher speeds. (While speed is usually not an issue for motor controllers, it can be for other system controllers.) Other than motor power, only a 3.3-V digital power supply was used in the controller; no analog bias supplies were used. Since most of the circuit was implemented in the FPGA, no additional parts were needed other than the power transistors to drive the motor. The benefits that FPGAs provide over conventional designs-lower power and fewer parts-allow for smaller packaging and reduced weight and cost.

  8. Modeling of Gate Bias Modulation in Carbon Nanotube Field-Effect-Transistor

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    The threshold voltages of a carbon-nanotube (CNT) field-effect transistor (FET) are studied. The CNT channel is so thin that there is no voltage drop perpendicular to the gate electrode plane, and this makes the device characteristics quite unique. The relation between the voltage and the electrochemical potentials, and the mass action law for electrons and holes are examined in the context of CNTs, and inversion and accumulation threshold voltages (V(sub Ti), and V(sub Ta)) are derived. V(sub Ti) of the CNTFETs has a much stronger doping dependence than that of the metal-oxide- semiconductor FETs, while V(sub Ta) of both devices depends weakly on doping with the same functional form.

  9. Electric-field-induced metal maintained by current of the Mott insulator Ca2RuO4

    PubMed Central

    Nakamura, Fumihiko; Sakaki, Mariko; Yamanaka, Yuya; Tamaru, Sho; Suzuki, Takashi; Maeno, Yoshiteru

    2013-01-01

    Recently, “application of electric field (E-field)” has received considerable attention as a new method to induce novel quantum phenomena since application of E-field can tune the electronic states directly with obvious scientific and industrial advantages over other turning methods. However, E-field-induced Mott transitions are rare and typically require high E-field and low temperature. Here we report that the multiband Mott insulator Ca2RuO4 shows unique insulator-metal switching induced by applying a dry-battery level voltage at room temperature. The threshold field Eth ~40 V/cm is much weaker than the Mott gap energy. Moreover, the switching is accompanied by a bulk structural transition. Perhaps the most peculiar of the present findings is that the induced metal can be maintained to low temperature by a weak current. PMID:23985626

  10. Ferroelectric Single-Crystal Gated Graphene/Hexagonal-BN/Ferroelectric Field-Effect Transistor.

    PubMed

    Park, Nahee; Kang, Haeyong; Park, Jeongmin; Lee, Yourack; Yun, Yoojoo; Lee, Jeong-Ho; Lee, Sang-Goo; Lee, Young Hee; Suh, Dongseok

    2015-11-24

    The effect of a ferroelectric polarization field on the charge transport in a two-dimensional (2D) material was examined using a graphene monolayer on a hexagonal boron nitride (hBN) field-effect transistor (FET) fabricated using a ferroelectric single-crystal substrate, (1-x)[Pb(Mg1/3Nb2/3)O3]-x[PbTiO3] (PMN-PT). In this configuration, the intrinsic properties of graphene were preserved with the use of an hBN flake, and the influence of the polarization field from PMN-PT could be distinguished. During a wide-range gate-voltage (VG) sweep, a sharp inversion of the spontaneous polarization affected the graphene channel conductance asymmetrically as well as an antihysteretic behavior. Additionally, a transition from antihysteresis to normal ferroelectric hysteresis occurred, depending on the V(G) sweep range relative to the ferroelectric coercive field. We developed a model to interpret the complex coupling among antihysteresis, current saturation, and sudden conductance variation in relation with the ferroelectric switching and the polarization-assisted charge trapping, which can be generalized to explain the combination of 2D structured materials with ferroelectrics.

  11. Fabrication of Gate-Electrode Integrated Carbon-Nanotube Bundle Field Emitters

    NASA Technical Reports Server (NTRS)

    Toda, Risaku; Bronikowski, Michael; Luong, Edward; Manohara, Harish

    2008-01-01

    A continuing effort to develop carbon-nanotube-based field emitters (cold cathodes) as high-current-density electron sources has yielded an optimized device design and a fabrication scheme to implement the design. One major element of the device design is to use a planar array of bundles of carbon nanotubes as the field-emission tips and to optimize the critical dimensions of the array (principally, heights of bundles and distances between them) to obtain high area-averaged current density and high reliability over a long operational lifetime a concept that was discussed in more detail in Arrays of Bundles of Carbon Nanotubes as Field Emitters (NPO-40817), NASA Tech Briefs, Vol. 31, No. 2 (February 2007), page 58. Another major element of the design is to configure the gate electrodes (anodes used to extract, accelerate, and/or focus electrons) as a ring that overhangs a recess wherein the bundles of nanotubes are located, such that by virtue of the proximity between the ring and the bundles, a relatively low applied potential suffices to generate the large electric field needed for emission of electrons.

  12. Field effect vs. Hall mobility in back-gated multilayered InSe FETs

    NASA Astrophysics Data System (ADS)

    Sucharitakul, Sukrit; Goble, Nicholas; Rajesh Kumar, U.; Sankar, Raman; Chou, Fang Cheng; Chen, Yit-Tsong; Gao, Xuan

    2015-03-01

    2D graphene-like materials, not only are interesting for their exotic transport behavior but also, hold promises for their mechanical robustness and many possibilities in miniaturization. As one material belonging to this category, InSe is not only a promising candidate for optoelectronic devices but also has potential for ultrathin field effect transistor (FET) with high mobility transport. Recent investigation showed that exfoliated InSe FET device on PMMA substrate can yield field effect mobility as high as 1000 cm2/Vs at room temperature. In this work, various substrates such as PMMA, bare SiO2, passivated SiO2, and Si3N4 were used to fabricate InSe FET devices. Through back gating and Hall measurement, the devices' field effect mobility and intrinsic Hall mobility were extracted at various temperatures to study the dielectric effect on the material's intrinsic transport behavior. Overall trend of the devices' mobility was found to increase as the temperature is reduced due to reduced phonon scattering. The sample's field effect and Hall mobilities over the range of 77-300K fall in the range of 0.5-2.0 × 103 cm2/Vs, better than the transition metal-dichalcogenides. X.P.A.G. acknowledges NSF CAREER Award (Grant Number DMR-1151534).

  13. Terahertz signal detection in a short gate length field-effect transistor with a two-dimensional electron gas

    SciTech Connect

    Vostokov, N. V. Shashkin, V. I.

    2015-11-28

    We consider the problem of non-resonant detection of terahertz signals in a short gate length field-effect transistor having a two-dimensional electron channel with zero external bias between the source and the drain. The channel resistance, gate-channel capacitance, and quadratic nonlinearity parameter of the transistor during detection as a function of the gate bias voltage are studied. Characteristics of detection of the transistor connected in an antenna with real impedance are analyzed. The consideration is based on both a simple one-dimensional model of the transistor and allowance for the two-dimensional distribution of the electric field in the transistor structure. The results given by the different models are discussed.

  14. Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

    SciTech Connect

    Cui, Ze-Qun; Wang, Shun; Chen, Jian-Mei; Gao, Xu; Dong, Bin E-mail: chilf@suda.edu.cn Chi, Li-Feng E-mail: chilf@suda.edu.cn Wang, Sui-Dong E-mail: chilf@suda.edu.cn

    2015-03-23

    Electron and hole trapping into the nano-floating-gate of a pentacene-based organic field-effect transistor nonvolatile memory is directly probed by Kelvin probe force microscopy. The probing is straightforward and non-destructive. The measured surface potential change can quantitatively profile the charge trapping, and the surface characterization results are in good accord with the corresponding device behavior. Both electrons and holes can be trapped into the nano-floating-gate, with a preference of electron trapping than hole trapping. The trapped charge quantity has an approximately linear relation with the programming/erasing gate bias, indicating that the charge trapping in the device is a field-controlled process.

  15. Silicon on ferroelectic insulator field effect transistor (SOF-FET) a new device for the next generation ultra low power circuits

    NASA Astrophysics Data System (ADS)

    Es-Sakhi, Azzedin D.

    Field effect transistors (FETs) are the foundation for all electronic circuits and processors. These devices have progressed massively to touch its final steps in sub-nanometer level. Left and right proposals are coming to rescue this progress. Emerging nano-electronic devices (resonant tunneling devices, single-atom transistors, spin devices, Heterojunction Transistors rapid flux quantum devices, carbon nanotubes, and nanowire devices) took a vast share of current scientific research. Non-Si electronic materials like III-V heterostructure, ferroelectric, carbon nanotubes (CNTs), and other nanowire based designs are in developing stage to become the core technology of non-classical CMOS structures. FinFET present the current feasible commercial nanotechnology. The scalability and low power dissipation of this device allowed for an extension of silicon based devices. High short channel effect (SCE) immunity presents its major advantage. Multi-gate structure comes to light to improve the gate electrostatic over the channel. The new structure shows a higher performance that made it the first candidate to substitute the conventional MOSFET. The device also shows a future scalability to continue Moor's Law. Furthermore, the device is compatible with silicon fabrication process. Moreover, the ultra-low-power (ULP) design required a subthreshold slope lower than the thermionic-emission limit of 60mV/ decade (KT/q). This value was unbreakable by the new structure (SOI-FinFET). On the other hand most of the previews proposals show the ability to go beyond this limit. However, those pre-mentioned schemes have publicized a very complicated physics, design difficulties, and process non-compatibility. The objective of this research is to discuss various emerging nano-devices proposed for ultra-low-power designs and their possibilities to replace the silicon devices as the core technology in the future integrated circuit. This thesis proposes a novel design that exploits the

  16. Measurement of insulating and dielectric properties of acrylic elastomer membranes at high electric fields

    NASA Astrophysics Data System (ADS)

    Di Lillo, L.; Schmidt, A.; Carnelli, D. A.; Ermanni, P.; Kovacs, G.; Mazza, E.; Bergamini, A.

    2012-01-01

    This work reports on the investigation of VHB 4910 acrylic elastomer insulating and dielectric properties. This material is widely exploited for the realization of actuators with large deformations, dielectric elastomer actuators (DEA), and belongs to the group of so-called electroactive polymers (EAP). Extensive investigations concerning its mechanical properties are available in literature while its electric behavior at working conditions has not received the same level of attention. In this work, the relative permittivity and the volume resistivity have been measured on VHB 4910 membranes under different fixed stretch conditions (λ1, λ2 = 3, 3.6, 4, 5) using circular gold electrodes sputtered onto both sides of the specimens. The measured values of relative permittivity are in fairly good agreement with the results previously published by other groups. The volume resistivity, at field values close to the operational ones, has shown a field-dependent behavior revealing dissipative properties that should be considered in real applications. Further, measurements on circular actuators verify these findings. Consequences for modeling of VHB 4910 are drawn and new material model parameters proposed to account for the value of relative permittivity at high electric fields.

  17. A digital magnetic resonance imaging spectrometer using digital signal processor and field programmable gate array

    NASA Astrophysics Data System (ADS)

    Liang, Xiao; Binghe, Sun; Yueping, Ma; Ruyan, Zhao

    2013-05-01

    A digital spectrometer for low-field magnetic resonance imaging is described. A digital signal processor (DSP) is utilized as the pulse programmer on which a pulse sequence is executed as a subroutine. Field programmable gate array (FPGA) devices that are logically mapped into the external addressing space of the DSP work as auxiliary controllers of gradient control, radio frequency (rf) generation, and rf receiving separately. The pulse programmer triggers an event by setting the 32-bit control register of the corresponding FPGA, and then the FPGA automatically carries out the event function according to preset configurations in cooperation with other devices; accordingly, event control of the spectrometer is flexible and efficient. Digital techniques are in widespread use: gradient control is implemented in real-time by a FPGA; rf source is constructed using direct digital synthesis technique, and rf receiver is constructed using digital quadrature detection technique. Well-designed performance is achieved, including 1 μs time resolution of the gradient waveform, 1 μs time resolution of the soft pulse, and 2 MHz signal receiving bandwidth. Both rf synthesis and rf digitalization operate at the same 60 MHz clock, therefore, the frequency range of transmitting and receiving is from DC to ˜27 MHz. A majority of pulse sequences have been developed, and the imaging performance of the spectrometer has been validated through a large number of experiments. Furthermore, the spectrometer is also suitable for relaxation measurement in nuclear magnetic resonance field.

  18. Field programmable gate array based reconfigurable scanning probe/optical microscope.

    PubMed

    Nowak, Derek B; Lawrence, A J; Dzegede, Zechariah K; Hiester, Justin C; Kim, Cliff; Sánchez, Erik J

    2011-10-01

    The increasing popularity of nanometrology and nanospectroscopy has pushed researchers to develop complex new analytical systems. This paper describes the development of a platform on which to build a microscopy tool that will allow for flexibility of customization to suit research needs. The novelty of the described system lies in its versatility of capabilities. So far, one version of this microscope has allowed for successful near-field and far-field fluorescence imaging with single molecule detection sensitivity. This system is easily adapted for reflection, polarization (Kerr magneto-optical (MO)), Raman, super-resolution techniques, and other novel scanning probe imaging and spectroscopic designs. While collecting a variety of forms of optical images, the system can simultaneously monitor topographic information of a sample with an integrated tuning fork based shear force system. The instrument has the ability to image at room temperature and atmospheric pressure or under liquid. The core of the design is a field programmable gate array (FPGA) data acquisition card and a single, low cost computer to control the microscope with analog control circuitry using off-the-shelf available components. A detailed description of electronics, mechanical requirements, and software algorithms as well as examples of some different forms of the microscope developed so far are discussed.

  19. Realization of quantum gates based on three-dimensional harmonic oscillator in a time-varying electromagnetic field

    NASA Astrophysics Data System (ADS)

    Gautam, Kumar; Chauhan, Garv; Rawat, Tarun Kumar; Parthasarathy, Harish; Sharma, Navneet

    2015-09-01

    This paper presents the design of a given quantum unitary gate by perturbing a three-dimensional (3-D) quantum harmonic oscillator with a time-varying but spatially constant electromagnetic field. The idea is based on expressing the radiation- perturbed Hamiltonian as the sum of the unperturbed Hamiltonian and O( e) and perturbations and then solving the Schrödinger equation to obtain the evolution operator at time T up to , and this is a linear-quadratic function of the perturbing electromagnetic field values over the time interval [0, T]. Setting the variational derivative of the error energy with respect to the electromagnetic field values with an average electromagnetic field energy constraint leads to the optimal electromagnetic field solution, a linear integral equation. The reliability of such a gate design procedure in the presence of heat bath coupling is analysed, and finally, an example illustrating how atoms and molecules can be approximated using oscillators is presented.

  20. Misalignment-free signal propagation in nanomagnet arrays and logic gates with 45°-clocking field

    SciTech Connect

    Li, Zheng; Kwon, Byung Seok; Krishnan, Kannan M.

    2014-05-07

    A key obstacle for the application of Magnetic Quantum-dot Cellular Automata (MQCA) is the misalignment of clocking field, which results in low stability for both signal propagations within nanomagnet array and logic operation in majority gates. Here, we demonstrate that a reversal clocking field applied at 45° off the hard axis, with progressively reduced amplitude, applied to a shape-tuned nanomagnet array fabricated by e-beam lithography, helps intrinsically eliminate the misalignment sensitivity of the elements and results in correct signal propagation. Further, least reversal steps and reduced field amplitude was required owing to the 45°-clocking field. This clocking field was also tested for majority gates (OR function) and characterized by Magnetic Force Microscopy demonstrating correct output. This novel design provides high stability for signal propagation and logic operation of MQCA and potentially paves way for its application.

  1. Building America Case Study: Field Testing an Unvented Roof with Fibrous Insulation and Tiles, Orlando, Florida

    SciTech Connect

    2015-11-01

    This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane. As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design. The unvented roof had extended winter periods of 95-100% RH, and wafer (wood surrogate RH sensor) measurements indicating possible condensation; high moisture levels were concentrated at the roof ridge. In contrast, the diffusion vent roofs had drier conditions, with most peak MCs (sheathing) below 20%. In the spring, as outdoor temperatures warmed, all roofs dried well into the safe range (10% MC or less). Some roof-wall interfaces showed moderately high MCs; this might be due to moisture accumulation at the highest point in the lower attic, and/or shading of the roof by the adjacent second story. Monitoring will be continued at least through spring 2016 (another winter and spring).

  2. Field Testing of an Unvented Roof with Fibrous Insulation, Tiles and Vapor Diffusion Venting

    SciTech Connect

    Ueno, K.; Lstiburek, J. W.

    2016-02-05

    This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane. As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design. The unvented roof had extended winter periods of 95-100% RH, and wafer (wood surrogate RH sensor) measurements indicating possible condensation; high moisture levels were concentrated at the roof ridge. In contrast, the diffusion vent roofs had drier conditions, with most peak MCs (sheathing) below 20%. In the spring, as outdoor temperatures warmed, all roofs dried well into the safe range (10% MC or less). Some roof-wall interfaces showed moderately high MCs; this might be due to moisture accumulation at the highest point in the lower attic, and/or shading of the roof by the adjacent second story. Monitoring will be continued at least through spring 2016 (another winter and spring).

  3. Field-Programmable Gate Array Computer in Structural Analysis: An Initial Exploration

    NASA Technical Reports Server (NTRS)

    Singleterry, Robert C., Jr.; Sobieszczanski-Sobieski, Jaroslaw; Brown, Samuel

    2002-01-01

    This paper reports on an initial assessment of using a Field-Programmable Gate Array (FPGA) computational device as a new tool for solving structural mechanics problems. A FPGA is an assemblage of binary gates arranged in logical blocks that are interconnected via software in a manner dependent on the algorithm being implemented and can be reprogrammed thousands of times per second. In effect, this creates a computer specialized for the problem that automatically exploits all the potential for parallel computing intrinsic in an algorithm. This inherent parallelism is the most important feature of the FPGA computational environment. It is therefore important that if a problem offers a choice of different solution algorithms, an algorithm of a higher degree of inherent parallelism should be selected. It is found that in structural analysis, an 'analog computer' style of programming, which solves problems by direct simulation of the terms in the governing differential equations, yields a more favorable solution algorithm than current solution methods. This style of programming is facilitated by a 'drag-and-drop' graphic programming language that is supplied with the particular type of FPGA computer reported in this paper. Simple examples in structural dynamics and statics illustrate the solution approach used. The FPGA system also allows linear scalability in computing capability. As the problem grows, the number of FPGA chips can be increased with no loss of computing efficiency due to data flow or algorithmic latency that occurs when a single problem is distributed among many conventional processors that operate in parallel. This initial assessment finds the FPGA hardware and software to be in their infancy in regard to the user conveniences; however, they have enormous potential for shrinking the elapsed time of structural analysis solutions if programmed with algorithms that exhibit inherent parallelism and linear scalability. This potential warrants further

  4. Radiation-Insensitive Inverse Majority Gates

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Mojarradi, Mohammad

    2008-01-01

    To help satisfy a need for high-density logic circuits insensitive to radiation, it has been proposed to realize inverse majority gates as microscopic vacuum electronic devices. In comparison with solid-state electronic devices ordinarily used in logic circuits, vacuum electronic devices are inherently much less adversely affected by radiation and extreme temperatures. The proposed development would involve state-of-the-art micromachining and recent advances in the fabrication of carbon-nanotube-based field emitters. A representative three-input inverse majority gate would be a monolithic, integrated structure that would include three gate electrodes, six bundles of carbon nanotubes (serving as electron emitters) at suitable positions between the gate electrodes, and an overhanging anode. The bundles of carbon nanotubes would be grown on degenerately doped silicon substrates that would be parts of the monolithic structure. The gate electrodes would be fabricated as parts of the monolithic structure by means of a double-silicon-on-insulator process developed at NASA's Jet Propulsion Laboratory. The tops of the bundles of carbon nanotubes would lie below the plane of the tops of the gate electrodes. The particular choice of shapes, dimensions, and relative positions of the electrodes and bundles of carbon nanotubes would provide for both field emission of electrons from the bundles of carbon nanotubes and control of the electron current to obtain the inverse majority function, which is described in the paper.

  5. Influence of trap-assisted tunneling on trap-assisted tunneling current in double gate tunnel field-effect transistor

    NASA Astrophysics Data System (ADS)

    Zhi, Jiang; Yi-Qi, Zhuang; Cong, Li; Ping, Wang; Yu-Qi, Liu

    2016-02-01

    Trap-assisted tunneling (TAT) has attracted more and more attention, because it seriously affects the sub-threshold characteristic of tunnel field-effect transistor (TFET). In this paper, we assess subthreshold performance of double gate TFET (DG-TFET) through a band-to-band tunneling (BTBT) model, including phonon-assisted scattering and acoustic surface phonons scattering. Interface state density profile (Dit) and the trap level are included in the simulation to analyze their effects on TAT current and the mechanism of gate leakage current. Project supported by the National Natural Science Foundation of China (Grant Nos. 61574109 and 61204092).

  6. T-gate geometric (solution for submicrometer gate length) HEMT: Physical analysis, modeling and implementation as parasitic elements and its usage as dual gate for variable gain amplifiers

    NASA Astrophysics Data System (ADS)

    Gupta, Ritesh; Rathi, Servin; Kaur, Ravneet; Gupta, Mridula; Gupta, R. S.

    2009-03-01

    In order to achieve superior RF performance, short gate length is required for the compound semiconductor field effect transistors, but the limitation in lithography for submicrometer gate lengths leads to the formation of various metal-insulator geometries like T-gate [Sandeep R. Bahl, Jesus A. del Alamo, Physics of breakdown in InAlAs/ n +-InGaAs heterostructure field-effect transistors, IEEE Trans. Electron Devices 41 (12) (1994) 2268-2275]. These geometries are the combination of various Metal-Semiconductor (MS)/Metal-Air-Semiconductor (MAS) contacts. Moreover, field plates [S. Karmalkar, M.S. Shur, G. Simin, M. Asif Khan, Field-plate engineering for HFETs, IEEE Trans. Electron Devices 52 (2005) 2534-2540] are also being fabricated these days, mainly at the drain end ( Γ-gate) having Metal-Insulator-Semiconductor (MIS) instead of MAS contact with the intention of increasing the breakdown voltage of the device. To realize the effect of upper gate electrode in the T-gate structure and field plates, an analytical model has been proposed in the present article by dividing the whole structure into MS/MIS contact regions, applying current continuity among them and solving iteratively. The model proposed for Metal-Insulator Semiconductor High Electron Mobility Transistor (MISHEMT) [R. Gupta, S.K. Aggarwal, M. Gupta, R.S. Gupta, Analytical model for metal insulator semiconductor high electron mobility transistor (MISHEMT) for its high frequency and high power applications, J. Semicond. Technol. Sci. 6 (3) (2006) 189-198], is equally applicable to High Electron Mobility Transistors (HEMT) and has been used to formulate this model. In this paper, various structures and geometries have been compared to anticipate the need of T-gate modeling. The effect of MIS contacts has been implemented as parasitic resistance and capacitance and has also been studied to control the middle conventional gate as in dual gate technology by applying separate voltages across it. The results

  7. Dielectric strength, swelling and weight loss of the ITER Toroidal Field Model Coil insulation after low temperature reactor irradiation

    NASA Astrophysics Data System (ADS)

    Humer, K.; Weber, H. W.; Hastik, R.; Hauser, H.; Gerstenberg, H.

    2000-04-01

    The insulation system for the Toroidal Field Model Coil of ITER is a fiber reinforced plastic (FRP) laminate, which consists of a combined Kapton/R-glass-fiber reinforcement tape, vacuum-impregnated with an epoxy DGEBA system. Pure disk shaped laminates, FRP/stainless-steel sandwiches, and conductor insulation prototypes were irradiated at 5 K in a fission reactor up to a fast neutron fluence of 10 22 m -2 ( E>0.1 MeV) to investigate the radiation induced degradation of the dielectric strength of the insulation system. After warm-up to room temperature, swelling, weight loss, and the breakdown strength were measured at 77 K. The sandwich swells by 4% at a fluence of 5×10 21 m-2 and by 9% at 1×10 22 m-2. The weight loss of the FRP is 2% at 1×10 22 m-2. The dielectric strength remained unchanged over the whole dose range.

  8. Electronic Excitations and Metal-Insulator Transition inPoly(3-hexylthiophene) Organic Field-Effect Transistors

    SciTech Connect

    Sai, N.; Li, Z.Q.; Martin, M.C.; Basov, D.N.; Di Ventra, M.

    2006-11-07

    We carry out a comprehensive theoretical and experimentalstudy of charge injection in poly(3-hexylthiophene) (P3HT) to determinethe most likely scenario for metal-insulator transition in this system.Wecalculate the optical-absorption frequencies corresponding to a polaronand a bipolaron lattice in P3HT. We also analyze the electronicexcitations for three possible scenarios under which a first- or asecond-order metal-insulator transition can occur in doped P3HT. Thesetheoretical scenarios are compared with data from infrared absorptionspectroscopy on P3HT thin-film field-effect transistors (FETs). Ourmeasurements and theoretical predictions suggest that charge-inducedlocalized states in P3HT FETs are bipolarons and that the highest dopinglevel achieved in our experiments approaches that required for afirst-order metal-insulator transition.

  9. Hydrogen-terminated diamond vertical-type metal oxide semiconductor field-effect transistors with a trench gate

    NASA Astrophysics Data System (ADS)

    Inaba, Masafumi; Muta, Tsubasa; Kobayashi, Mikinori; Saito, Toshiki; Shibata, Masanobu; Matsumura, Daisuke; Kudo, Takuya; Hiraiwa, Atsushi; Kawarada, Hiroshi

    2016-07-01

    The hydrogen-terminated diamond surface (C-H diamond) has a two-dimensional hole gas (2DHG) layer independent of the crystal orientation. A 2DHG layer is ubiquitously formed on the C-H diamond surface covered by atomic-layer-deposited-Al2O3. Using Al2O3 as a gate oxide, C-H diamond metal oxide semiconductor field-effect transistors (MOSFETs) operate in a trench gate structure where the diamond side-wall acts as a channel. MOSFETs with a side-wall channel exhibit equivalent performance to the lateral C-H diamond MOSFET without a side-wall channel. Here, a vertical-type MOSFET with a drain on the bottom is demonstrated in diamond with channel current modulation by the gate and pinch off.

  10. Differential multiple-time-programmable memory cells by laterally coupled floating metal gate fin field-effect transistors

    NASA Astrophysics Data System (ADS)

    Hsu, Chia-Ling; Liao, Chu-Feng; Chien, Wei Yu; Chih, Yue-Der; Lin, Chrong Jung; King, Ya-Chin

    2017-04-01

    In this paper, we present a new differential multiple-time-programmable (MTP) memory cell with a novel slot contact coupling structure in the fin field-effect transistor (FinFET) CMOS process. This MTP cell contains a pair of floating metal gates to store differential data on a single cell. Through differential read operations, the cells are less susceptible to read error caused by cell-to-cell variations. In a nano-scaled FinFET process, the gate dielectric layer becomes too thin to retain charge in the floating gates for long periods of time. Differential cell design further extends the data lifetime, even with the serious charge-loss problem, and reduces the overall intellectual property (IP) area.

  11. Gate modulation of below-band-gap photoconductivity in ZnO nanowire field-effect-transistors

    NASA Astrophysics Data System (ADS)

    Cammi, Davide; Röder, Robert; Ronning, Carsten

    2014-10-01

    We investigated the modulation of the photoconductivity under below-band gap excitation in single ZnO nanowire field effect transistors. Light excitation at 550 nm does not induce any change in the drain-source current when the gate voltage is kept at Vgs = 0 V, but results in a current increase when it is set to Vgs = -50 V. At this negative value of the gate voltage we further investigated the photo-reaction in the below-band-gap range 400-800 nm, observing a qualitative similar profile for all the photo-current curves. These results were attributed to a local effect, suggesting that the change in conductivity is due to the release of electrons from interface states located between the ZnO nanowire active channel and the gate dielectric SiO2.

  12. Fabrication and independent control of patterned polymer gate for a few-layer WSe2 field-effect transistor

    NASA Astrophysics Data System (ADS)

    Hong, Sung Ju; Park, Min; Kang, Hojin; Lee, Minwoo; Jeong, Dae Hong; Park, Yung Woo

    2016-08-01

    We report the fabrication of a patterned polymer electrolyte for a two-dimensional (2D) semiconductor, few-layer tungsten diselenide (WSe2) field-effect transistor (FET). We expose an electron-beam in a desirable region to form the patterned structure. The WSe2 FET acts as a p-type semiconductor in both bare and polymer-covered devices. We observe a highly efficient gating effect in the polymer-patterned device with independent gate control. The patterned polymer gate operates successfully in a molybdenum disulfide (MoS2) FET, indicating the potential for general applications to 2D semiconductors. The results of this study can contribute to large-scale integration and better flexibility in transition metal dichalcogenide (TMD)-based electronics.

  13. Physics of gate leakage current in N-polar InAlN/GaN heterojunction field effect transistors

    SciTech Connect

    Goswami, Arunesh; Trew, Robert J.; Bilbro, Griff L.

    2014-10-28

    A physics based model of the gate leakage current in N-polar InAlN/GaN heterojunction field effect transistors is demonstrated. The model is based on the space charge limited current flow dominated by the effects of deep traps in the InAlN surface layer. The model predicts accurately the gate-leakage measurement data of the N-polar InAlN/GaN device with InAlN cap layer. In the pinch-off state, the gate leakage current conduction through the surface of the device in the drain access region dominates the current flow through the two dimensional electron gas channel. One deep trap level and two levels of shallow traps are extracted by fitting the model results with measurement data.

  14. Bio-fabrication of nanomesh channels of single-walled carbon nanotubes for locally gated field-effect transistors

    NASA Astrophysics Data System (ADS)

    Byeon, Hye-Hyeon; Lee, Woo Chul; Kim, Wonbin; Kim, Seong Keun; Kim, Woong; Yi, Hyunjung

    2017-01-01

    Single-walled carbon nanotubes (SWNTs) are one of the promising electronic components for nanoscale electronic devices such as field-effect transistors (FETs) owing to their excellent device characteristics such as high conductivity, high carrier mobility and mechanical flexibility. Localized gating gemometry of FETs enables individual addressing of active channels and allows for better electrostatics via thinner dielectric layer of high k-value. For localized gating of SWNTs, it becomes critical to define SWNTs of controlled nanostructures and functionality onto desired locations in high precision. Here, we demonstrate that a biologically templated approach in combination of microfabrication processes can successfully produce a nanostructured channels of SWNTs for localized active devices such as local bottom-gated FETs. A large-scale nanostructured network, nanomesh, of SWNTs were assembled in solution using an M13 phage with strong binding affinity toward SWNTs and micrometer-scale nanomesh channels were defined using negative photolithography and plasma-etching processes. The bio-fabrication approach produced local bottom-gated FETs with remarkably controllable nanostructures and successfully enabled semiconducting behavior out of unsorted SWNTs. In addition, the localized gating scheme enhanced the device performances such as operation voltage and I on/I off ratio. We believe that our approach provides a useful and integrative method for fabricating electronic devices out of nanoscale electronic materials for applications in which tunable electrical properties, mechanical flexibility, ambient stability, and chemical stability are of crucial importance.

  15. Physiologically gated micro-beam radiation therapy using electronically controlled field emission x-ray source array

    NASA Astrophysics Data System (ADS)

    Chtcheprov, Pavel; Hadsell, Michael; Burk, Laurel; Ger, Rachel; Zhang, Lei; Yuan, Hong; Lee, Yueh Z.; Chang, Sha; Lu, Jianping; Zhou, Otto

    2013-03-01

    Micro-beam radiation therapy (MRT) uses parallel planes of high dose narrow (10-100 um in width) radiation beams separated by a fraction of a millimeter to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000Gy of entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during the treatment can result in significant movement of micro beam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), and thus can reduce the effectiveness of the MRT. Recently we have developed the first bench-top image guided MRT system for small animal treatment using a high powered carbon nanotube (CNT) x-ray source array. The CNT field emission x-ray source can be electronically synchronized to an external triggering signal to enable physiologically gated firing of x-ray radiation to minimize motion blurring. Here we report the results of phantom study of respiratory gated MRT. A simulation of mouse breathing was performed using a servo motor. Preliminary results show that without gating the micro beam full width at tenth maximum (FWTM) can increase by 70% and PVDR can decrease up to 50%. But with proper gating, both the beam width and PVDR changes can be negligible. Future experiments will involve irradiation of mouse models and comparing histology stains between the controls and the gated irradiation.

  16. Quasi-two-dimensional threshold voltage model for junctionless cylindrical surrounding gate metal-oxide-semiconductor field-effect transistor with dual-material gate

    NASA Astrophysics Data System (ADS)

    Li, Cong; Zhuang, Yi-Qi; Zhang, Li; Jin, Gang

    2014-01-01

    Based on the quasi-two-dimensional (2D) solution of Poisson's equation in two continuous channel regions, an analytical threshold voltage model for short-channel junctionless dual-material cylindrical surrounding-gate (JLDMCSG) metal-oxide-semiconductor field-effect transistor (MOSFET) is developed. Using the derived model, channel potential distribution, horizontal electrical field distribution, and threshold voltage roll-off of JLDMCSG MOSFET are investigated. Compared with junctionless single-material CSG (JLSGCSG) MOSFET, JLDMCSG MOSFET can effectively suppress short-channel effects and simultaneously improve carrier transport efficiency. It is also revealed that threshold voltage roll-off of JLDMCSG can be significantly reduced by adopting both a small oxide thickness and a small silicon channel radius. The model is verified by comparing its calculated results with that obtained from three-dimensional (3D) numerical device simulator ISE.

  17. Design of acoustic logging signal source of imitation based on field programmable gate array

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Ju, X. D.; Lu, J. Q.; Men, B. Y.

    2014-08-01

    An acoustic logging signal source of imitation is designed and realized, based on the Field Programmable Gate Array (FPGA), to improve the efficiency of examining and repairing acoustic logging tools during research and field application, and to inspect and verify acoustic receiving circuits and corresponding algorithms. The design of this signal source contains hardware design and software design,and the hardware design uses an FPGA as the control core. Four signals are made first by reading the Random Access Memory (RAM) data which are inside the FPGA, then dealing with the data by digital to analog conversion, amplification, smoothing and so on. Software design uses VHDL, a kind of hardware description language, to program the FPGA. Experiments illustrate that the ratio of signal to noise for the signal source is high, the waveforms are stable, and also its functions of amplitude adjustment, frequency adjustment and delay adjustment are in accord with the characteristics of real acoustic logging waveforms. These adjustments can be used to imitate influences on sonic logging received waveforms caused by many kinds of factors such as spacing and span of acoustic tools, sonic speeds of different layers and fluids, and acoustic attenuations of different cementation planes.

  18. Technology Solutions Case Study: Field Testing an Unvented Roof with Fibrous Insulation and Tiles

    SciTech Connect

    2015-11-01

    This case study by the U.S. Department of Energy’s Building America research team Building Science Corporation is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, Florida; zone 2A), insulated with air-permeable insulation (netted and blown fiberglass).

  19. Finite field methods for the supercell modeling of charged insulator/electrolyte interfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Sprik, Michiel

    2016-12-01

    Surfaces of ionic solids interacting with an ionic solution can build up charge by exchange of ions. The surface charge is compensated by a strip of excess charge at the border of the electrolyte forming an electric double layer. These electric double layers are very hard to model using the supercell's methods of computational condensed phase science. The problem arises when the solid is an electric insulator (as most ionic solids are) permitting a finite interior electric field over the width of the slab representing the solid in the supercell. The slab acts as a capacitor. The stored charge is a deficit in the solution failing to compensate fully for the solid surface charge. Here, we show how these problems can be overcome using the finite field methods developed by Stengel, Spaldin, and Vanderbilt [Nat. Phys. 5, 304 (2009), 10.1038/nphys1185]. We also show how the capacitance of the double layer can be computed once overall electric neutrality of the double layer is restored by application of a finite macroscopic field E or alternatively by zero electric displacement D . The method is validated for a classical model of a solid-electrolyte interface using the finite-temperature molecular dynamics adaptation of the constant field method presented previously [C. Zhang and M. Sprik, Phys. Rev. B 93, 144201 (2016), 10.1103/PhysRevB.93.144201]. Because ions in electrolytes can diffuse across supercell boundaries, this application turns out to be a critical illustration of the multivaluedness of polarization in periodic systems.

  20. Metrology solutions using optical scatterometry for advanced CMOS: III-V and Germanium multi-gate field-effect transistors

    NASA Astrophysics Data System (ADS)

    Chin, Hock-Chun; Liu, Bin; Zhang, Xingui; Ling, Moh-Lung; Yip, Chan-Hoe; Liu, Yongdong; Hu, Jiangtao; Yeo, Yee-Chia

    2013-04-01

    In this work, we report metrology solutions using scatterometry Optical Critical Dimension (OCD) characterization on two advanced CMOS devices: novel n-channel gate-last In0.53Ga0.47As FinFET with self-aligned Molybdenum (Mo) contacts and p-channel Ge FinFET formed on Germanium-on-Insulator (GOI) substrate. Key critical process steps during the fabrication of these advanced transistors were identified for process monitor using scatterometry OCD measurement to improve final yield. Excellent correlation with reference metrology and high measurement precision were achieved by using OCD characterization, confirming scatterometry OCD as a promising metrology technique for next generation device applications. In addition, we also further explore OCD characterization using normal incidence spectroscopic reflectometry (SR), oblique incidence spectroscopic ellipsometry (SE), and combined SR+SE technologies. The combined SR+SE approach was found to provide better precision.

  1. AlGaN/GaN metal-insulator-semiconductor high-electron mobility transistors with high on/off current ratio of over 5 × 1010 achieved by ozone pretreatment and using ozone oxidant for Al2O3 gate insulator

    NASA Astrophysics Data System (ADS)

    Tokuda, Hirokuni; Asubar, Joel T.; Kuzuhara, Masaaki

    2016-12-01

    This letter describes DC characteristics of AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with Al2O3 deposited by atomic layer deposition (ALD) as gate dielectric. Comparison was made for the samples deposited using ozone (O3) or water as oxidant. The effect of pretreatment, where O3 was solely supplied prior to depositing Al2O3, was also investigated. The MIS-HEMT with O3 pretreatment and Al2O3 gate dielectric deposited using O3 as the oxidant exhibited the most desirable characteristics with an excellent high on/off current ratio of 7.1 × 1010, and a low sub-threshold swing (SS) of 73 mV/dec.

  2. Four allotropes of semiconducting layered arsenic that switch into a topological insulator via an electric field: Computational study

    NASA Astrophysics Data System (ADS)

    Mardanya, Sougata; Thakur, Vinay Kumar; Bhowmick, Somnath; Agarwal, Amit

    2016-07-01

    We propose four different thermodynamically stable structural phases of arsenic monolayers based on ab initio density functional theory calculations, all of which undergo a topological phase transition on application of a perpendicular electric field. All four arsenic monolayer allotropes have a wide band gap, varying from 1.21 to 3.0 eV (based on GW calculations), and in general they undergo a metal-insulator quantum phase transition on application of uniaxial in-layer strain. Additionally, an increasing transverse electric field induces band inversion at the Γ point in all four monolayer allotropes, leading to a nontrivial topological phase (insulating for three allotropes and metallic for one allotrope), characterized by the switching of the Z2 index from 0 (before band inversion) to 1 (after band inversion). The topological phase tuned by the transverse electric field should support spin-separated gapless edge states which should manifest in the quantum spin Hall effect.

  3. Orbital magnetic field driven metal-insulator transition in spinless extended Falicov-Kimball model on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Yadav, Umesh K.

    2017-01-01

    Ground state properties of spinless, extended Falicov-Kimball model (FKM) on a finite size triangular lattice with orbital magnetic field normal to the lattice are studied using numerical diagonalization and Monte-Carlo simulation methods. We show that the ground state configurations of localized electrons strongly depend on the magnetic field. Magnetic field induces a metal to insulator transition accompanied by segregated phase to an ordered regular phase except at density nf = 1 / 2 of localized electrons. It is proposed that magnetic field can be used as a new tool to produce segregated phase which was otherwise accessible only either with correlated hopping or with large on-site interactions.

  4. Field study of moisture damage in walls insulated without a vapor barrier. Final report for the Oregon Department of Energy

    SciTech Connect

    Tsongas, G.A.

    1980-05-01

    Considerable uncertainty has existed over whether or not wall insulation installed without a vapor barrier causes an increased risk of moisture damage (wood decay) within walls. This report describes the results of one of the first major studies in the country aimed at finding out if such a moisture problem really exists. The exterior walls of a total of 96 homes in Portland, Oregon were opened, of which 70 had retrofitted insulation and 26 were uninsulated and were a control group. The types of insulation included urea-formaldehyde foam (44), mineral wool (16), and cellulose (10). In each opened wall cavity the moisture content of wood was measured and insulation and wood samples were taken for laboratory analysis of moisture content and for the determination of the presence of absence of decay fungi. Foam shrinkage was also measured. To evaluate the possible influence of the relative air tightness of the homes, fan depressurization tests were run using a door blower unit. The field and laboratory test results indicating the lack of a moisture damage problem in existing homes with wood siding in climates similar to that of western Oregon are described along with results of a statistical analysis of the data. Related problems of interest to homeowners and insulation installers are noted. The standard operating procedures used throughout the study are discussed, including the home selection process, quantitative and qualitative techniques used to identify wall locations with the highest moisture content, wall opening and data/sample collection methodology, laboratory analysis of samples, data processing and analysis, and applicability of the results. Recommendations for furutre tests are made. Finally, the potential and desirability for future retrofitting of wall insulation is explored.

  5. On Field-Effect Photovoltaics: Gate Enhancement of the Power Conversion Efficiency in a Nanotube/Silicon-Nanowire Solar Cell

    SciTech Connect

    Petterson, Maureen K.; Lemaitre, Maxime G.; Shen, Yu; Wadhwa, Pooja; Hou, Jie; Vasilyeva, Svetlana V.; Kravchenko, Ivan I.; Rinzler, Andrew G.

    2015-09-09

    Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separated there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm2 AM1.5G illumination, results in a short-circuit current density of 35 mA/cm2 and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. Finally, a deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.

  6. On Field-Effect Photovoltaics: Gate Enhancement of the Power Conversion Efficiency in a Nanotube/Silicon-Nanowire Solar Cell

    DOE PAGES

    Petterson, Maureen K.; Lemaitre, Maxime G.; Shen, Yu; ...

    2015-09-09

    Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separatedmore » there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm2 AM1.5G illumination, results in a short-circuit current density of 35 mA/cm2 and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. Finally, a deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.« less

  7. On Field-Effect Photovoltaics: Gate Enhancement of the Power Conversion Efficiency in a Nanotube/Silicon-Nanowire Solar Cell.

    PubMed

    Petterson, Maureen K; Lemaitre, Maxime G; Shen, Yu; Wadhwa, Pooja; Hou, Jie; Vasilyeva, Svetlana V; Kravchenko, Ivan I; Rinzler, Andrew G

    2015-09-30

    Recent years have seen a resurgence of interest in crystalline silicon Schottky junction solar cells distinguished by the use of low density of electronic states (DOS) nanocarbons (nanotubes, graphene) as the metal contacting the Si. Recently, unprecedented modulation of the power conversion efficiency in a single material system has been demonstrated in such cells by the use of electronic gating. The gate field induced Fermi level shift in the low-DOS carbon serves to enhance the junction built-in potential, while a gate field induced inversion layer at the Si surface, in regions remote from the junction, keeps the photocarriers well separated there, avoiding recombination at surface traps and defects (a key loss mechanism). Here, we extend these results into the third dimension of a vertical Si nanowire array solar cell. A single wall carbon nanotube layer engineered to contact virtually each n-Si nanowire tip extracts the minority carriers, while an ionic liquid electrolytic gate drives the nanowire body into inversion. The enhanced light absorption of the vertical forest cell, at 100 mW/cm(2) AM1.5G illumination, results in a short-circuit current density of 35 mA/cm(2) and associated power conversion efficiency of 15%. These results highlight the use of local fields as opposed to surface passivation as a means of avoiding front surface recombination. A deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue, a nonencapsulation-based approach is also implemented.

  8. Solution-deposited sodium beta-alumina gate dielectrics for low-voltage and transparent field-effect transistors.

    PubMed

    Pal, Bhola N; Dhar, Bal Mukund; See, Kevin C; Katz, Howard E

    2009-11-01

    Sodium beta-alumina (SBA) has high two-dimensional conductivity, owing to mobile sodium ions in lattice planes, between which are insulating AlO(x) layers. SBA can provide high capacitance perpendicular to the planes, while causing negligible leakage current owing to the lack of electron carriers and limited mobility of sodium ions through the aluminium oxide layers. Here, we describe sol-gel-beta-alumina films as transistor gate dielectrics with solution-deposited zinc-oxide-based semiconductors and indium tin oxide (ITO) gate electrodes. The transistors operate in air with a few volts input. The highest electron mobility, 28.0 cm2 V(-1) s(-1), was from zinc tin oxide (ZTO), with an on/off ratio of 2 x 10(4). ZTO over a lower-temperature, amorphous dielectric, had a mobility of 10 cm2 V(-1) s(-1). We also used silicon wafer and flexible polyimide-aluminium foil substrates for solution-processed n-type oxide and organic transistors. Using poly(3,4-ethylenedioxythiophene) poly(styrenesulphonate) conducting polymer electrodes, we prepared an all-solution-processed, low-voltage transparent oxide transistor on an ITO glass substrate.

  9. Solution-deposited sodium beta-alumina gate dielectrics for low-voltage and transparent field-effect transistors

    NASA Astrophysics Data System (ADS)

    Pal, Bhola N.; Dhar, Bal Mukund; See, Kevin C.; Katz, Howard E.

    2009-11-01

    Sodium beta-alumina (SBA) has high two-dimensional conductivity, owing to mobile sodium ions in lattice planes, between which are insulating AlOx layers. SBA can provide high capacitance perpendicular to the planes, while causing negligible leakage current owing to the lack of electron carriers and limited mobility of sodium ions through the aluminium oxide layers. Here, we describe sol-gel-beta-alumina films as transistor gate dielectrics with solution-deposited zinc-oxide-based semiconductors and indium tin oxide (ITO) gate electrodes. The transistors operate in air with a few volts input. The highest electron mobility, 28.0cm2V-1s-1, was from zinc tin oxide (ZTO), with an on/off ratio of 2×104. ZTO over a lower-temperature, amorphous dielectric, had a mobility of 10cm2V-1s-1. We also used silicon wafer and flexible polyimide-aluminium foil substrates for solution-processed n-type oxide and organic transistors. Using poly(3,4-ethylenedioxythiophene) poly(styrenesulphonate) conducting polymer electrodes, we prepared an all-solution-processed, low-voltage transparent oxide transistor on an ITO glass substrate.

  10. 2006/07 Field Testing of Cellulose Fiber Insulation Enhanced with Phase Change Material

    SciTech Connect

    Kosny, Jan; Yarbrough, David W; Miller, William A; Petrie, Thomas; Childs, Phillip W; Syed, Azam M

    2008-12-01

    Most recent improvements in building envelope technologies suggest that in the near future, residences will be routinely constructed to operate with very low heating and cooling loads. In that light, the application of novel building materials containing active thermal components (e.g., phase change materials [PCMs,] sub-venting, radiant barriers, and integrated hydronic systems) is like a final step in achieving relatively significant heating and cooling energy savings from technological improvements in the building envelope. It is expected that optimized building envelope designs using PCMs for energy storage can effectively bring notable savings in energy consumption and reductions in peak hour power loads. During 2006/07, a research team at Oak Ridge National Laboratory (ORNL) performed a series of laboratory and field tests of several wall and roof assemblies using PCM-enhanced cellulose insulation. This report summarizes the test results from the perspective of energy performance. The ORNL team is working on both inorganic and organic PCMs; this report discusses only paraffinic PCMs. A limited economical analysis also is presented. PCMs have been tested as a thermal mass component in buildings for at least 40 years. Most of the research studies found that PCMs enhanced building energy performance. In the case of the application of organic PCMs, problems such as high initial cost and PCM leaking (surface sweating) have hampered widespread adoption. Paraffinic hydrocarbon PCMs generally performed well, with the exception that they increased the flammability of the building envelope.

  11. Double gate graphene nanoribbon field effect transistor with single halo pocket in channel region

    NASA Astrophysics Data System (ADS)

    Naderi, Ali

    2016-01-01

    A new structure for graphene nanoribbon field-effect transistors (GNRFETs) is proposed and investigated using quantum simulation with a nonequilibrium Green's function (NEGF) method. Tunneling leakage current and ambipolar conduction are known effects for MOSFET-like GNRFETs. To minimize these issues a novel structure with a simple change of the GNRFETs by using single halo pocket in the intrinsic channel region, "Single Halo GNRFET (SH-GNRFET)", is proposed. An appropriate halo pocket at source side of channel is used to modify potential distribution of the gate region and weaken band to band tunneling (BTBT). In devices with materials like Si in channel region, doping type of halo and source/drain regions are different. But, here, due to the smaller bandgap of graphene, the mentioned doping types should be the same to reduce BTBT. Simulations have shown that in comparison with conventional GNRFET (C-GNRFET), an SH-GNRFET with appropriately halo doping results in a larger ON current (Ion), smaller OFF current (Ioff), a larger ON-OFF current ratio (Ion/Ioff), superior ambipolar characteristics, a reduced power-delay product and lower delay time.

  12. Digital control of force microscope cantilevers using a field programmable gate array.

    PubMed

    Jacky, Jonathan P; Garbini, Joseph L; Ettus, Matthew; Sidles, John A

    2008-12-01

    This report describes a cantilever controller for magnetic resonance force microscopy based on a field programmable gate array, along with the hardware and software used to integrate the controller into an experiment. The controller is assembled from a low-cost commercially available software defined radio device and libraries of open-source software. The controller includes a digital filter comprising two cascaded second-order sections ("biquads"), which together can implement transfer functions for optimal cantilever controllers. An appendix in this report shows how to calculate filter coefficients for an optimal controller from measured cantilever characteristics. The controller also includes an input multiplexer and adder used in calibration protocols. Filter coefficients and multiplexer settings can be set and adjusted by control software while an experiment is running. The input is sampled at 64 MHz; the sampling frequency in the filters can be divided down under software control to achieve a good match with filter characteristics. Data reported here were sampled at 500 kHz, chosen for acoustic cantilevers with resonant frequencies near 8 kHz. Inputs are digitized with 12 bit resolution, and outputs are digitized with 14 bits. The experiment software is organized as a client and server to make it easy to adapt the controller to different experiments. The server encapsulates the details of controller hardware organization, connection technology, filter architecture, and number representation. The same server could be used in any experiment, while a different client encodes the particulars of each experiment.

  13. Real-time processing for Fourier domain optical coherence tomography using a field programmable gate array

    PubMed Central

    Ustun, Teoman E.; Iftimia, Nicusor V.; Ferguson, R. Daniel; Hammer, Daniel X.

    2008-01-01

    Real-time display of processed Fourier domain optical coherence tomography (FDOCT) images is important for applications that require instant feedback of image information, for example, systems developed for rapid screening or image-guided surgery. However, the computational requirements for high-speed FDOCT image processing usually exceeds the capabilities of most computers and therefore display rates rarely match acquisition rates for most devices. We have designed and developed an image processing system, including hardware based upon a field programmable gated array, firmware, and software that enables real-time display of processed images at rapid line rates. The system was designed to be extremely flexible and inserted in-line between any FDOCT detector and any Camera Link frame grabber. Two versions were developed for spectrometer-based and swept source-based FDOCT systems, the latter having an additional custom high-speed digitizer on the front end but using all the capabilities and features of the former. The system was tested in humans and monkeys using an adaptive optics retinal imager, in zebrafish using a dual-beam Doppler instrument, and in human tissue using a swept source microscope. A display frame rate of 27 fps for fully processed FDOCT images (1024 axial pixels×512 lateral A-scans) was achieved in the spectrometer-based systems. PMID:19045902

  14. Modular design and implementation of field-programmable-gate-array-based Gaussian noise generator

    NASA Astrophysics Data System (ADS)

    Li, Yuan-Ping; Lee, Ta-Sung; Hwang, Jeng-Kuang

    2016-05-01

    The modular design of a Gaussian noise generator (GNG) based on field-programmable gate array (FPGA) technology was studied. A new range reduction architecture was included in a series of elementary function evaluation modules and was integrated into the GNG system. The approximation and quantisation errors for the square root module with a first polynomial approximation were high; therefore, we used the central limit theorem (CLT) to improve the noise quality. This resulted in an output rate of one sample per clock cycle. We subsequently applied Newton's method for the square root module, thus eliminating the need for the use of the CLT because applying the CLT resulted in an output rate of two samples per clock cycle (>200 million samples per second). Two statistical tests confirmed that our GNG is of high quality. Furthermore, the range reduction, which is used to solve a limited interval of the function approximation algorithms of the System Generator platform using Xilinx FPGAs, appeared to have a higher numerical accuracy, was operated at >350 MHz, and can be suitably applied for any function evaluation.

  15. Boron δ-doped (111) diamond solution gate field effect transistors.

    PubMed

    Edgington, Robert; Ruslinda, A Rahim; Sato, Syunsuke; Ishiyama, Yuichiro; Tsuge, Kyosuke; Ono, Tasuku; Kawarada, Hiroshi; Jackman, Richard B

    2012-03-15

    A solution gate field effect transistor (SGFET) using an oxidised boron δ-doped channel on (111) diamond is presented for the first time. Employing an optimised plasma chemical vapour deposition (PECVD) recipe to deposit δ-layers, SGFETs show improved current-voltage (I-V) characteristics in comparison to previous similar devices fabricated on (100) and polycrystalline diamond, where the device is shown to operate in the enhancement mode of operation, achieving channel pinch-off and drain-source current saturation within the electrochemical window of diamond. A maximum gain and transconductance of 3 and 200μS/mm are extracted, showing comparable figures of merit to hydrogen-based SGFET. The oxidised device shows a site-binding model pH sensitivity of 36 mV/pH, displaying fast temporal responses. Considering the biocompatibility of diamond towards cells, the device's highly mutable transistor characteristics, pH sensitivity and stability against anodic oxidation common to hydrogen terminated diamond SGFET, oxidised boron δ-doped diamond SGFETs show promise for the recording of action potentials from electrogenic cells.

  16. Real-time processing for Fourier domain optical coherence tomography using a field programmable gate array

    NASA Astrophysics Data System (ADS)

    Ustun, Teoman E.; Iftimia, Nicusor V.; Ferguson, R. Daniel; Hammer, Daniel X.

    2008-11-01

    Real-time display of processed Fourier domain optical coherence tomography (FDOCT) images is important for applications that require instant feedback of image information, for example, systems developed for rapid screening or image-guided surgery. However, the computational requirements for high-speed FDOCT image processing usually exceeds the capabilities of most computers and therefore display rates rarely match acquisition rates for most devices. We have designed and developed an image processing system, including hardware based upon a field programmable gated array, firmware, and software that enables real-time display of processed images at rapid line rates. The system was designed to be extremely flexible and inserted in-line between any FDOCT detector and any Camera Link frame grabber. Two versions were developed for spectrometer-based and swept source-based FDOCT systems, the latter having an additional custom high-speed digitizer on the front end but using all the capabilities and features of the former. The system was tested in humans and monkeys using an adaptive optics retinal imager, in zebrafish using a dual-beam Doppler instrument, and in human tissue using a swept source microscope. A display frame rate of 27 fps for fully processed FDOCT images (1024 axial pixels×512 lateral A-scans) was achieved in the spectrometer-based systems.

  17. Temperature, Magnetic field, and Gate Bias Dependence of the Infrared Hall Effect in Graphene

    NASA Astrophysics Data System (ADS)

    Ellis, C. T.; Stier, A. V.; Stabile, A.; Kim, M.-H.; Sambandamurthy, G.; Cerne, J.; Banerjee, S.

    2010-03-01

    In our study we probe the infrared Hall conductivity (σxy) for single and bilayer graphene in the 120-1000 meV range as a function of gate bias at temperatures down to 7K and magnetic fields up to 7T using Faraday measurements. Unlike the longitudinal conductivity (σxx), which measures the sum of the optical responses for left and right circularly polarized light, σxy measures the difference and therefore is sensitive to small changes in symmetry. While σxx and the DC Hall effect have revealed extraordinary properties of graphene (Zhang, Nature 2005; Novoselov, Nature 2005; Jiang, PRL 2007; etc...) recent calculations (Morimoto, PRL 2009) predict remarkable step-like features in the infrared σxy. We also probe the chiral response of graphene due to spatial inversion symmetry breaking. Our graphene samples are prepared using several methods, including anodically bonding graphite to pyrex, which can produce a high yield of large single layer graphene flakes (>100 μm) (Shukla et al., Solid State Comm. 2009), normal mechanical exfoliation of kish graphite, and grown chemical vapor deposition techniques.

  18. Full image-processing pipeline in field-programmable gate array for a small endoscopic camera

    NASA Astrophysics Data System (ADS)

    Mostafa, Sheikh Shanawaz; Sousa, L. Natércia; Ferreira, Nuno Fábio; Sousa, Ricardo M.; Santos, Joao; Wäny, Martin; Morgado-Dias, F.

    2017-01-01

    Endoscopy is an imaging procedure used for diagnosis as well as for some surgical purposes. The camera used for the endoscopy should be small and able to produce a good quality image or video, to reduce discomfort of the patients, and to increase the efficiency of the medical team. To achieve these fundamental goals, a small endoscopy camera with a footprint of 1 mm×1 mm×1.65 mm is used. Due to the physical properties of the sensors and human vision system limitations, different image-processing algorithms, such as noise reduction, demosaicking, and gamma correction, among others, are needed to faithfully reproduce the image or video. A full image-processing pipeline is implemented using a field-programmable gate array (FPGA) to accomplish a high frame rate of 60 fps with minimum processing delay. Along with this, a viewer has also been developed to display and control the image-processing pipeline. The control and data transfer are done by a USB 3.0 end point in the computer. The full developed system achieves real-time processing of the image and fits in a Xilinx Spartan-6LX150 FPGA.

  19. Modeling of Gate Bias Modulation in Carbon Nanotube Field-Effect-Transistors

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryan (Technical Monitor)

    2002-01-01

    The threshold voltages of a carbon nanotube (CNT) field-effect transistor (FET) are derived and compared with those of the metal oxide-semiconductor (MOS) FETs. The CNT channel is so thin that there is no voltage drop perpendicular to the gate electrode plane, which is the CNT diameter direction, and this makes the CNTFET characteristics quite different from those in MOSFETs. The relation between the voltage and the electrochemical potentials, and the mass action law for electrons and holes are examined in the context of CNTs, and it is shown that the familiar relations are still valid because of the macroscopic number of states available in the CNTs. This is in sharp contrast to the cases of quantum dots. Using these relations, we derive an inversion threshold voltage V(sub Ti) and an accumulation threshold voltage V(sub Ta) as a function of the Fermi level E(sub F) in the channel, where E(sub F) is a measure of channel doping. V(sub Ti) of the CNTFETs has a much stronger dependence than that of MOSFETs, while V(sub Ta)s of both CNTFETs and MOSFETs depend quite weakly on E(sub F) with the same functional form. This means the transition from normally-off mode to normally-on mode is much sharper in CNTFETs as the doping increases, and this property has to be taken into account in circuit design.

  20. Single Event Effects Test Results for Advanced Field Programmable Gate Arrays

    NASA Technical Reports Server (NTRS)

    Allen, Gregory R.; Swift, Gary M.

    2006-01-01

    Reconfigurable Field Programmable Gate Arrays (FPGAs) from Altera and Actel and an FPGA-based quick-turnApplication Specific Integrated Circuit (ASIC) from Altera were subjected to single-event testing using heavy ions. Both Altera devices (Stratix II and HardCopy II) exhibited a low latchup threshold (below an LET of 3 MeV-cm2/mg) and thus are not recommended for applications in the space radiation environment. The flash-based Actel ProASIC Plus device did not exhibit latchup to an effective LET of 75 MeV-cm2/mg at room temperature. In addition, these tests did not show flash cell charge loss (upset) or retention damage. Upset characterization of the design-level flip-flops yielded an LET threshold below 10 MeV-cm2/mg and a high LET cross section of about lxlO-6 cm2/bit for storing ones and about lxl0-7 cm2/bit for storing zeros . Thus, the ProASIC device may be suitable for critical flight applications with appropriate triple modular redundancy mitigation techniques.

  1. Gate-Sensing Coherent Charge Oscillations in a Silicon Field-Effect Transistor.

    PubMed

    Gonzalez-Zalba, M Fernando; Shevchenko, Sergey N; Barraud, Sylvain; Johansson, J Robert; Ferguson, Andrew J; Nori, Franco; Betz, Andreas C

    2016-03-09

    Quantum mechanical effects induced by the miniaturization of complementary metal-oxide-semiconductor (CMOS) technology hamper the performance and scalability prospects of field-effect transistors. However, those quantum effects, such as tunneling and coherence, can be harnessed to use existing CMOS technology for quantum information processing. Here, we report the observation of coherent charge oscillations in a double quantum dot formed in a silicon nanowire transistor detected via its dispersive interaction with a radio frequency resonant circuit coupled via the gate. Differential capacitance changes at the interdot charge transitions allow us to monitor the state of the system in the strong-driving regime where we observe the emergence of Landau-Zener-Stückelberg-Majorana interference on the phase response of the resonator. A theoretical analysis of the dispersive signal demonstrates that quantum and tunneling capacitance changes must be included to describe the qubit-resonator interaction. Furthermore, a Fourier analysis of the interference pattern reveals a charge coherence time, T2 ≈ 100 ps. Our results demonstrate charge coherent control and readout in a simple silicon transistor and open up the possibility to implement charge and spin qubits in existing CMOS technology.

  2. Evaluation of soft-core processors on a Xilinx Virtex-5 field programmable gate array.

    SciTech Connect

    Learn, Mark Walter

    2011-04-01

    Node-based architecture (NBA) designs for future satellite projects hold the promise of decreasing system development time and costs, size, weight, and power and positioning the laboratory to address other emerging mission opportunities quickly. Reconfigurable field programmable gate array (FPGA)-based modules will comprise the core of several of the NBA nodes. Microprocessing capabilities will be necessary with varying degrees of mission-specific performance requirements on these nodes. To enable the flexibility of these reconfigurable nodes, it is advantageous to incorporate the microprocessor into the FPGA itself, either as a hard-core processor built into the FPGA or as a soft-core processor built out of FPGA elements. This document describes the evaluation of three reconfigurable FPGA-based soft-core processors for use in future NBA systems: the MicroBlaze (uB), the open-source Leon3, and the licensed Leon3. Two standard performance benchmark applications were developed for each processor. The first, Dhrystone, is a fixed-point operation metric. The second, Whetstone, is a floating-point operation metric. Several trials were run at varying code locations, loop counts, processor speeds, and cache configurations. FPGA resource utilization was recorded for each configuration.

  3. Photoinduced current in n-AlGaAs/GaAs heterojunction field-effect transistor driven by local illumination in edge regions of Schottky metal gate

    NASA Astrophysics Data System (ADS)

    Kawazu, Takuya; Noda, Takeshi; Sakuma, Yoshiki

    2017-04-01

    We investigated the photoresponses of the Schottky gate region of an n-AlGaAs/GaAs field-effect transistor (FET) by local illumination with a near-infrared (IR) laser beam. We examined (1) the Schottky photocurrent J SG from the source to the metal gate and (2) the lateral photocurrent J SD from the source to the drain under the open gate condition. We found that the magnitudes of J SG and J SD rapidly increase as the laser spot approaches the edges of the metal gate; IR photoresponses are enhanced in the regions near the gate edges. Experimental findings are well explained by a simple model considering the IR photoresponses with the gate edge effect.

  4. A facile route for the fabrication of large-scale gate-all-around nanofluidic field-effect transistors with low leakage current.

    PubMed

    Shin, Sangwoo; Kim, Beom Seok; Song, Jiwoon; Lee, Hwanseong; Cho, Hyung Hee

    2012-07-21

    Active modulation of ions and molecules via field-effect gating in nanofluidic channels is a crucial technology for various promising applications such as DNA sequencing, drug delivery, desalination, and energy conversion. Developing a rapid and facile fabrication method for ionic field-effect transistors (FET) over a large area may offer exciting opportunities for both fundamental research and innovative applications. Here, we report a rapid, cost-effective route for the fabrication of large-scale nanofluidic field-effect transistors using a simple, lithography-free two-step fabrication process that consists of sputtering and barrier-type anodization. A robust alumina gate dielectric layer, which is formed by anodizing sputtered aluminium, can be rapidly fabricated in the order of minutes. When anodizing aluminium, we employ a hemispherical counter electrode in order to give a uniform electric field that encompasses the whole sputtered aluminium layer which has high surface roughness. In consequence, a well-defined thin layer of alumina with perfect step coverage is formed on a highly rough aluminium surface. A gate-all-around nanofluidic FET with a leak-free gate dielectric exhibits outstanding gating performance despite a large channel size. The thin and robust anodized alumina gate dielectric plays a crucial role in achieving such excellent capacitive coupling. The combination of a gate-all-around structure with a leak-free gate dielectric over a large area could yield breakthroughs in areas ranging from biotechnology to energy and environmental applications.

  5. Highly scaled ( Lg ˜ 56 nm) gate-last Si tunnel field-effect transistors with ION > 100 μA/μm

    NASA Astrophysics Data System (ADS)

    Loh, Wei-Yip; Jeon, Kanghoon; Kang, Chang Yong; Oh, Jungwoo; King Liu, Tsu-Jae; Tseng, Hsing-Huang; Xiong, Wade; Majhi, Prashant; Jammy, Raj; Hu, Chenming

    2011-11-01

    Planar band-to-band tunneling FETs (TFETs) have been fabricated on silicon-on-insulator (SOI) substrates using conventional CMOS technologies with a highly scaled sub-60 nm gate length (effective gate length [Lg] ∼ 40 nm due to an overlap between the source and gate) and different anneal sequences. The optimal anneal sequence including spike and flash annealing resulted in a drive ON current (ION)) > 100 μA/μm with ION/IOFF > 105 at a drain bias of -1 V. The devices exhibited negative differential resistance and non-linear subthreshold temperature dependencies, consistent with the band-to-band tunneling mechanism. Simulations using a 2-D TCAD simulator, MEDICI, agreed with experimental data, demonstrating the possibility of Si tunnel transistors in logic applications.

  6. Simulating the Activation of Voltage Sensing Domain for a Voltage-Gated Sodium Channel Using Polarizable Force Field.

    PubMed

    Sun, Rui-Ning; Gong, Haipeng

    2017-03-02

    Voltage-gated sodium (NaV) channels play vital roles in the signal transduction of excitable cells. Upon activation of a NaV channel, the change of transmembrane voltage triggers conformational change of the voltage sensing domain, which then elicits opening of the pore domain and thus allows an influx of Na(+) ions. Description of this process with atomistic details is in urgent demand. In this work, we simulated the partial activation process of the voltage sensing domain of a prokaryotic NaV channel using a polarizable force field. We not only observed the conformational change of the voltage sensing domain from resting to preactive state, but also rigorously estimated the free energy profile along the identified reaction pathway. Comparison with the control simulation using an additive force field indicates that voltage-gating thermodynamics of NaV channels may be inaccurately described without considering the electrostatic polarization effect.

  7. Effects of Photowashing Treatment on Gate Leakage Current of GaAs Metal-Semiconductor Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Choi, Kyoung Jin; Moon, Jae Kyoung; Park, Min; Kim, Haechon; Lee, Jong-Lam

    2002-05-01

    Effects of photowashing treatment on gate leakage current (IGD) of a GaAs metal-semiconductor field-effect transistor were studied by observing changes in atomic composition and band bending at the surface of GaAs through X-ray photoemission spectroscopy. The photowashing treatment produces Ga2O3 on the surface of GaAs, leaving acceptor-type Ga antisites behind under the oxide. The Ga antisites played a role in reducing the maximum electric field at the drain edge of the gate, leading to the decrease of IGD. The longer photowashing time produced thicker oxide on the surface of GaAs, acting as a conducting pass for electrons, leading to the increase of IGD.

  8. High carrier mobility of CoPc wires based field-effect transistors using bi-layer gate dielectric

    SciTech Connect

    Gedda, Murali; Obaidulla, Sk. Md.; Subbarao, Nimmakayala V. V.; Goswami, Dipak K.

    2013-11-15

    Polyvinyl alcohol (PVA) and anodized Al{sub 2}O{sub 3} layers were used as bi-layer gate for the fabrication of cobalt phthalocyanine (CoPc) wire base field-effect transistors (OFETs). CoPc wires were grown on SiO{sub 2} surfaces by organic vapor phase deposition method. These devices exhibit a field-effect carrier mobility (μ{sub EF}) value of 1.11 cm{sup 2}/Vs. The high carrier mobility for CoPc molecules is attributed to the better capacitive coupling between the channel of CoPc wires and the gate through organic-inorganic dielectric layer. Our measurements also demonstrated the way to determine the thicknesses of the dielectric layers for a better process condition of OFETs.

  9. Scaling behavior of the magnetic-field-tuned superconductor-insulator transition in two-dimensional Josephson-junction arrays

    SciTech Connect

    Chen, C.D.; Delsing, P.; Haviland, D.B.; Harada, Y.; Claeson, T.

    1995-06-01

    We have studied the superconductor-insulator (SI) phase transition for two-dimensional (2D) arrays of small Josephson junctions in a weak magnetic field. The data were analyzed within the context of the theory of the magnetic-field-tuned SI transition in 2D superconductors. We show resistance scaling curves over several orders of magnitude for the 2D arrays. The critical exponent {ital z}{sub {ital B}} is determined to be 1.05, in good agreement with the theory. Moreover, the transverse (Hall) resistance at the critical field is found to be very small in comparison to the longitudinal resistance.

  10. Comparison of Focused and Near-Field Imaging of Spray on Foam Insulation (SOFI) at Millimeter Wave Frequencies

    NASA Technical Reports Server (NTRS)

    Kharkovshy, S.; Zoughi, R.; Hepburn, F. L.

    2007-01-01

    Millimeter wave imaging techniques can provide high spatial-resolution images of various composites. Lens antennas may be incorporated into the imaging system to provide a small incident beam footprint. Another approach may involve the use of horn antennas, which if operating in their near-fields, images with reasonably high spatial-resolutions may also be obtained. This paper gives a comparison between such near-field and focused far-field imaging of the Space Shuttle Spray on Foam Insulation (SOFI) used in its external fuel tank at millimeter wave frequencies. Small horn antennas and lens antennas with relatively long depth of focus were used in this investigation.

  11. Low operating voltage n-channel organic field effect transistors using lithium fluoride/PMMA bilayer gate dielectric

    SciTech Connect

    Kumar, S.; Dhar, A.

    2015-10-15

    Highlights: • Alternative to chemically crosslinking of PMMA to achieve low leakage in provided. • Effect of LiF in reducing gate leakage through the OFET device is studied. • Effect of gate leakage on transistor performance has been investigated. • Low voltage operable and low temperature processed n-channel OFETs were fabricated. - Abstract: We report low temperature processed, low voltage operable n-channel organic field effect transistors (OFETs) using N,N′-Dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C{sub 8}) organic semiconductor and poly(methylmethacrylate) (PMMA)/lithium fluoride (LiF) bilayer gate dielectric. We have studied the role of LiF buffer dielectric in effectively reducing the gate leakage through the device and thus obtaining superior performance in contrast to the single layer PMMA dielectric devices. The bilayer OFET devices had a low threshold voltage (V{sub t}) of the order of 5.3 V. The typical values of saturation electron mobility (μ{sub s}), on/off ratio and inverse sub-threshold slope (S) for the range of devices made were estimated to be 2.8 × 10{sup −3} cm{sup 2}/V s, 385, and 3.8 V/decade respectively. Our work thus provides a potential substitution for much complicated process of chemically crosslinking PMMA to achieve low leakage, high capacitance, and thus low operating voltage OFETs.

  12. Dirac point and transconductance of top-gated graphene field-effect transistors operating at elevated temperature

    SciTech Connect

    Hopf, T.; Vassilevski, K. V. Escobedo-Cousin, E.; King, P. J.; Wright, N. G.; O'Neill, A. G.; Horsfall, A. B.; Goss, J. P.; Wells, G. H.; Hunt, M. R. C.

    2014-10-21

    Top-gated graphene field-effect transistors (GFETs) have been fabricated using bilayer epitaxial graphene grown on the Si-face of 4H-SiC substrates by thermal decomposition of silicon carbide in high vacuum. Graphene films were characterized by Raman spectroscopy, Atomic Force Microscopy, Scanning Tunnelling Microscopy, and Hall measurements to estimate graphene thickness, morphology, and charge transport properties. A 27 nm thick Al₂O₃ gate dielectric was grown by atomic layer deposition with an e-beam evaporated Al seed layer. Electrical characterization of the GFETs has been performed at operating temperatures up to 100 °C limited by deterioration of the gate dielectric performance at higher temperatures. Devices displayed stable operation with the gate oxide dielectric strength exceeding 4.5 MV/cm at 100 °C. Significant shifting of the charge neutrality point and an increase of the peak transconductance were observed in the GFETs as the operating temperature was elevated from room temperature to 100 °C.

  13. Study of Strain Induction for Metal-Oxide-Semiconductor Field-Effect Transistors using Transparent Dummy Gates and Stress Liners

    NASA Astrophysics Data System (ADS)

    Kosemura, Daisuke; Takei, Munehisa; Nagata, Kohki; Akamatsu, Hiroaki; Kohno, Masayuki; Nishita, Tatsuo; Nakanishi, Toshio; Ogura, Atsushi

    2009-06-01

    Strain induction was studied on a sample that had a dummy gate tetraethyl orthosilicate-silicon dioxide (TEOS-SiO2) and SiN film by UV-Raman spectroscopy with high spatial and high wave-number resolution. The UV laser penetrated through the dummy gate that was transparent to UV light, which enabled us to evaluate strain in the channel of the metal-oxide-semiconductor field-effect transistor (MOSFET) model. Furthermore, we compared stress profiles obtained by finite element (FE) calculations with those obtained by UV-Raman measurements. There was a difference between the stress profiles in the line-and-space pattern sample and in the dummy-gate sample; large compressive (tensile) strains were concentrated at the channel edges in the dummy-gate sample with the compressive (tensile) stress liner, although both tensile and compressive strains existed at the channel edge in the line-and-space pattern sample. The results from UV-Raman spectroscopy were consistent with those obtained by the FE calculation.

  14. Friability of spray-applied fireproofing and thermal insulations: the basis for a field-test method

    SciTech Connect

    Rossiter, W.J.; Roberts, W.E.; Mathey, R.G.

    1987-12-01

    The investigation was Phase 1 of a two-part study to develop a test method that can be used in the field to measure the friability of spray-applied fireproofing and insulating materials containing asbestos fibers. Four test methods were selected; compression/shear, indentation, abrasion, and impact. For each of the four tests, mechanical devices were devised by modification of existing material test apparatus. A description of the test devices is given in the report.

  15. Real-time implementation of frequency-modulated continuous-wave synthetic aperture radar imaging using field programmable gate array.

    PubMed

    Quan, Yinghui; Li, Yachao; Hu, Guibin; Xing, Mengdao

    2015-06-01

    A new miniature linear frequency-modulated continuous-wave radar which mounted on an unmanned aerial vehicle is presented. It allows the accomplishment of high resolution synthetic aperture radar imaging in real-time. Only a Kintex-7 field programmable gate array from Xilinx is utilized for whole signal processing of sophisticated radar imaging algorithms. The proposed hardware architecture achieves remarkable improvement in integration, power consumption, volume, and computing performance over its predecessor designs. The realized design is verified by flight campaigns.

  16. Single Event Test Methodologies and System Error Rate Analysis for Triple Modular Redundant Field Programmable Gate Arrays

    NASA Technical Reports Server (NTRS)

    Allen, Gregory; Edmonds, Larry D.; Swift, Gary; Carmichael, Carl; Tseng, Chen Wei; Heldt, Kevin; Anderson, Scott Arlo; Coe, Michael

    2010-01-01

    We present a test methodology for estimating system error rates of Field Programmable Gate Arrays (FPGAs) mitigated with Triple Modular Redundancy (TMR). The test methodology is founded in a mathematical model, which is also presented. Accelerator data from 90 nm Xilins Military/Aerospace grade FPGA are shown to fit the model. Fault injection (FI) results are discussed and related to the test data. Design implementation and the corresponding impact of multiple bit upset (MBU) are also discussed.

  17. Nanofabrication of Arrays of Silicon Field Emitters with Vertical Silicon Nanowire Current Limiters and Self-Aligned Gates

    DTIC Science & Technology

    2016-08-19

    polysilicon is deposited at 625 °C using low-pressure chemical vapor deposition (LPCVD). At this temperature, the polysilicon has columnar growth and large...results, as the transconductance for a cathode scales exponentially with the gate voltage, and the currents for which they report transconductance were...radius and perhaps a tighter distribution principally due to the exponential relationship between the field factor (and hence the tip radius) on the

  18. Optimization of Cyclostationary Signal Processing Algorithms Using Multiple Field Programmable Gate Arrays on the SRC-6 Reconfigurable Computer

    DTIC Science & Technology

    2009-09-01

    of the architecture is seen in Figure 36. Two major components make up the FPGA . The input/output blocks (IOBs) provide the interface between...programming language to make a complete program. To take advantage of FPGAs precise circuit design should be utilized by employing Verilog or VHDL. 47...runtime to approach real-time processing. The focus of the implementation is to utilize dual field programmable gate arrays ( FPGAs ) within a single

  19. Real-time implementation of frequency-modulated continuous-wave synthetic aperture radar imaging using field programmable gate array

    NASA Astrophysics Data System (ADS)

    Quan, Yinghui; Li, Yachao; Hu, Guibin; Xing, Mengdao

    2015-06-01

    A new miniature linear frequency-modulated continuous-wave radar which mounted on an unmanned aerial vehicle is presented. It allows the accomplishment of high resolution synthetic aperture radar imaging in real-time. Only a Kintex-7 field programmable gate array from Xilinx is utilized for whole signal processing of sophisticated radar imaging algorithms. The proposed hardware architecture achieves remarkable improvement in integration, power consumption, volume, and computing performance over its predecessor designs. The realized design is verified by flight campaigns.

  20. Monte Carlo Simulation of a 6 MV X-Ray Beam for Open and Wedge Radiation Fields, Using GATE Code.

    PubMed

    Bahreyni-Toosi, Mohammad-Taghi; Nasseri, Shahrokh; Momennezhad, Mahdi; Hasanabadi, Fatemeh; Gholamhosseinian, Hamid

    2014-10-01

    The aim of this study is to provide a control software system, based on Monte Carlo simulation, and calculations of dosimetric parameters of standard and wedge radiation fields, using a Monte Carlo method. GATE version 6.1 (OpenGATE Collaboration), was used to simulate a compact 6 MV linear accelerator system. In order to accelerate the calculations, the phase-space technique and cluster computing (Condor version 7.2.4, Condor Team, University of Wisconsin-Madison) were used. Dosimetric parameters used in treatment planning systems for the standard and wedge radiation fields (10 cm × 10 cm to 30 cm × 30 cm and a 60° wedge), including the percentage depth dose and dose profiles, were measured by both computational and experimental methods. Gamma index was applied to compare calculated and measured results with 3%/3 mm criteria. Gamma index was applied to compare calculated and measured results. Almost all calculated data points have satisfied gamma index criteria of 3% to 3 mm. Based on the good agreement between calculated and measured results obtained for various radiation fields in this study, GATE may be used as a useful tool for quality control or pretreatment verification procedures in radiotherapy.

  1. Monte Carlo Simulation of a 6 MV X-Ray Beam for Open and Wedge Radiation Fields, Using GATE Code

    PubMed Central

    Bahreyni-Toosi, Mohammad-Taghi; Nasseri, Shahrokh; Momennezhad, Mahdi; Hasanabadi, Fatemeh; Gholamhosseinian, Hamid

    2014-01-01

    The aim of this study is to provide a control software system, based on Monte Carlo simulation, and calculations of dosimetric parameters of standard and wedge radiation fields, using a Monte Carlo method. GATE version 6.1 (OpenGATE Collaboration), was used to simulate a compact 6 MV linear accelerator system. In order to accelerate the calculations, the phase-space technique and cluster computing (Condor version 7.2.4, Condor Team, University of Wisconsin–Madison) were used. Dosimetric parameters used in treatment planning systems for the standard and wedge radiation fields (10 cm × 10 cm to 30 cm × 30 cm and a 60° wedge), including the percentage depth dose and dose profiles, were measured by both computational and experimental methods. Gamma index was applied to compare calculated and measured results with 3%/3 mm criteria. Gamma index was applied to compare calculated and measured results. Almost all calculated data points have satisfied gamma index criteria of 3% to 3 mm. Based on the good agreement between calculated and measured results obtained for various radiation fields in this study, GATE may be used as a useful tool for quality control or pretreatment verification procedures in radiotherapy. PMID:25426430

  2. A novel low specific on-resistance double-gate LDMOS with multiple buried p-layers in the drift region based on the Silicon-On-Insulator substrate

    NASA Astrophysics Data System (ADS)

    Chen, Yinhui; Hu, Shengdong; Cheng, Kun; Jiang, YuYu; Luo, Jun; Wang, Jian'an; Tang, Fang; Zhou, Xichuan; Zhou, Jianlin; Gan, Ping

    2016-01-01

    A novel double-gate SOI LDMOS with multiple buried p-layers in the drift region (MBP SOI LDMOS) is proposed in this paper. MBP SOI LDMOS has two gates, the planar gate and the trench gate. The big feature of MBP LDMOS is the multiple buried p-layers with intervals in the drift region which is an arithmetic progression and decreases successively. Firstly, double gates of the structure form dual current conduction channels, leading to a low specific on-resistance (Ron,sp). Secondly, the multiple buried p-layers form a more significant triple RESURF effect, which not only increases the drift doping concentration but also modulates the electric field of the drift region, resulting in a low Ron,sp and a high breakdown voltage (BV). MBP SOI LDMOS is thus owning a reduced Ron,sp and an improved BV. The effects of structure parameters on the device performances are investigated. Compared with the conventional SOI LDMOS, the Ron,sp of MBP SOI LDMOS is reduced by 52.5% with BV increasing by 36.4% at the same 16-μm-drift region.

  3. High quality PECVD SiO2 process for recessed MOS-gate of AlGaN/GaN-on-Si metal-oxide-semiconductor heterostructure field-effect transistors

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Gil; Kim, Hyun-Seop; Seo, Kwang-Seok; Cho, Chun-Hyung; Cha, Ho-Young

    2016-08-01

    A high quality SiO2 deposition process using a plasma enhanced chemical vapor deposition system has been developed for the gate insulator process of normally-off recessed-gate AlGaN/GaN metal-oxide-semiconductor-heterostructure field-effect transistors (MOS-HFETs). SiO2 films were deposited by using SiH4 and N2O mixtures as reactant gases. The breakdown field increased with increasing the N2O flow rate. The optimum SiH4/N2O ratio was 0.05, which resulted in a maximum breakdown field of 11 MV/cm for the SiO2 film deposited on recessed GaN surface. The deposition conditions were optimized as follows; a gas flow rate of SiH4/N2O (=27/540 sccm), a source RF power of 100 W, a pressure of 2 Torr, and a deposition temperature of 350 °C. A fabricated normally-off MOS-HFET exhibited a threshold voltage of 3.2 V, a specific on-resistance of 4.46 mΩ cm2, and a breakdown voltage of 810 V.

  4. Use of Field Programmable Gate Array Technology in Future Space Avionics

    NASA Technical Reports Server (NTRS)

    Ferguson, Roscoe C.; Tate, Robert

    2005-01-01

    Fulfilling NASA's new vision for space exploration requires the development of sustainable, flexible and fault tolerant spacecraft control systems. The traditional development paradigm consists of the purchase or fabrication of hardware boards with fixed processor and/or Digital Signal Processing (DSP) components interconnected via a standardized bus system. This is followed by the purchase and/or development of software. This paradigm has several disadvantages for the development of systems to support NASA's new vision. Building a system to be fault tolerant increases the complexity and decreases the performance of included software. Standard bus design and conventional implementation produces natural bottlenecks. Configuring hardware components in systems containing common processors and DSPs is difficult initially and expensive or impossible to change later. The existence of Hardware Description Languages (HDLs), the recent increase in performance, density and radiation tolerance of Field Programmable Gate Arrays (FPGAs), and Intellectual Property (IP) Cores provides the technology for reprogrammable Systems on a Chip (SOC). This technology supports a paradigm better suited for NASA's vision. Hardware and software production are melded for more effective development; they can both evolve together over time. Designers incorporating this technology into future avionics can benefit from its flexibility. Systems can be designed with improved fault isolation and tolerance using hardware instead of software. Also, these designs can be protected from obsolescence problems where maintenance is compromised via component and vendor availability.To investigate the flexibility of this technology, the core of the Central Processing Unit and Input/Output Processor of the Space Shuttle AP101S Computer were prototyped in Verilog HDL and synthesized into an Altera Stratix FPGA.

  5. The Use of Field Programmable Gate Arrays (FPGA) in Small Satellite Communication Systems

    NASA Technical Reports Server (NTRS)

    Varnavas, Kosta; Sims, William Herbert; Casas, Joseph

    2015-01-01

    This paper will describe the use of digital Field Programmable Gate Arrays (FPGA) to contribute to advancing the state-of-the-art in software defined radio (SDR) transponder design for the emerging SmallSat and CubeSat industry and to provide advances for NASA as described in the TAO5 Communication and Navigation Roadmap (Ref 4). The use of software defined radios (SDR) has been around for a long time. A typical implementation of the SDR is to use a processor and write software to implement all the functions of filtering, carrier recovery, error correction, framing etc. Even with modern high speed and low power digital signal processors, high speed memories, and efficient coding, the compute intensive nature of digital filters, error correcting and other algorithms is too much for modern processors to get efficient use of the available bandwidth to the ground. By using FPGAs, these compute intensive tasks can be done in parallel, pipelined fashion and more efficiently use every clock cycle to significantly increase throughput while maintaining low power. These methods will implement digital radios with significant data rates in the X and Ka bands. Using these state-of-the-art technologies, unprecedented uplink and downlink capabilities can be achieved in a 1/2 U sized telemetry system. Additionally, modern FPGAs have embedded processing systems, such as ARM cores, integrated inside the FPGA allowing mundane tasks such as parameter commanding to occur easily and flexibly. Potential partners include other NASA centers, industry and the DOD. These assets are associated with small satellite demonstration flights, LEO and deep space applications. MSFC currently has an SDR transponder test-bed using Hardware-in-the-Loop techniques to evaluate and improve SDR technologies.

  6. Optical multi-token-ring networking using smart pixels with field programmable gate arrays (FPGAs)

    NASA Astrophysics Data System (ADS)

    Zhang, Liping; Hong, Sunkwang; Min, Changki; Alpaslan, Zahir Y.; Sawchuk, Alexander A.

    2001-12-01

    This research explores architectures and design principles for monolithic optoelectronic integrated circuits (OEICs) through the implementation of an optical multi-token-ring network testbed system. Monolithic smart pixel CMOS OEICs are of paramount importance to high performance networks, communication switches, computer interfaces, and parallel signal processing for demanding future multimedia applications. The general testbed system is called Reconfigurable Translucent Smart Pixel Array (R-Transpar) and includes a field programmable gate array (FPGA), a transimpedance receiver array, and an optoelectronic very large-scale integrated (OE-VLSI) smart pixel array. The FPGA is an Altera FLEX10K100E chip that performs logic functions and receives inputs from the transimpedance receiver array. A monolithic (OE-VLSI) smart pixel device containing an array of 4 X 4 vertical-cavity surface-emitting lasers (VCSELs) spatially interlaced with an array of 4 X 4 metal- semiconductor-metal (MSM) detectors connects to these devices and performs optical input-output functions. These components are mounted on a printed circuit board for testing and evaluation of integrated monolithic OEIC designs and various optical interconnection techniques. The system moves information between nodes by transferring 3-D optical packets in free space or through fiber image guides. The R-Transpar system is reconfigurable to test different network protocols and signal processing functions. In its operation as a 3-D multi-token-ring network, we use a specific version of the system called Transpar-Token-Ring (Transpar-TR) that uses novel time-division multiplexed (TDM) network node addressing to enhance channel utilization and throughput. Host computers interface with the system via a high-speed digital I/O board that sends commands for networking and application algorithm operations. We describe the system operation and experimental results in detail.

  7. A time digitizer for space instrumentation using a field programmable gate array

    NASA Astrophysics Data System (ADS)

    Rogacki, S.; Zurbuchen, T. H.

    2013-08-01

    Space instruments such as time-of-flight (TOF) mass spectrometers and altimeters rely on time-to-digital converters (TDCs) to measure accurately times in the picosecond to microsecond range. Time-to-digital conversion is often implemented with analog circuitry or more recently with custom ASIC (Application Specific Integrated Circuit) devices. The analog approach may be costly in terms of circuit board area and parts count, while ASIC development is risky and costly when system requirements may change. Here, we present a highly flexible, accurate, and low-cost field-programmable gate array (FPGA) implementation of such TDC functionality. Compared with other technologies, this method reduces the parts count in TOF-supporting circuits and provides design flexibility in TOF instrumentation, especially for use in space or for applications with a number of sensors too small to warrant the development of a dedicated ASIC. Our technique can accommodate one or more STOP pulse measurements for each START pulse as signal reference, effectively providing measurements of multiple times-of-flight with the same start trigger. Alternatively, all pulse event edges can receive an absolute time stamp, enabling a broad set of new sensor applications. This novel design is based on the construction of a delay-line internal to the FPGA. Propagation variations due to temperature and supply voltage, which typically limit FPGA-based timing designs, are automatically compensated, allowing active signal processing 100% of the time. A methodology for the characterization of internal delay-line timing and nonlinearity has also been developed and is not specific to a particular FPGA architecture. We describe the design of this FPGA-based TDC and also describe detailed tests with a Xilinx XC2V1000. For single non-repetitive events, this design achieves 60 ps accuracy (standard deviation of error); a simplified implementation is suitable for non-reprogrammable FPGAs.

  8. Enzyme-modified electrolyte-gated organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Buth, Felix; Donner, Andreas; Stutzmann, Martin; Garrido, Jose A.

    2012-10-01

    Organic solution-gated field-effect transistors (SGFETs) can be operated at low voltages in aqueous environments, paving the way to the use of organic semiconductors in bio-sensing applications. However, it has been shown that these devices exhibit only a rather weak sensitivity to standard electrolyte parameters such as pH and ionic strength. In order to increase the sensitivity and to add specificity towards a given analyte, the covalent attachment of functional groups and enzymes to the device surface would be desirable. In this contribution we demonstrate that enzyme modified organic SGFETs can be used for the in-situ detection of penicillin in the low μM regime. In a first step, silane molecules with amine terminal groups are grafted to α-sexithiophene-based thin film transistors. Surface characterization techniques like X-ray photoemission confirm the modification of the surface with these functional groups, which are stable in standard aqueous electrolytes. We show that the presence of surface-bound amphoteric groups (e.g. amino or carboxylic moieties) increases the pH-sensitivity of the organic SGFETs. In addition, these groups serve as anchoring sites for the attachment of the enzyme penicillinase. The resulting enzyme-FETs are used for the detection of penicillin, enabling the study of the influence of the buffer strength and the pH of the electrolyte on the enzyme kinetics. The functionalization of the organic FETs shown here can be extended to a large variety of enzymes, allowing the specific detection of different chemical and biochemical analytes.

  9. Development and modeling of a stereo vision focusing system for a field programmable gate array robot

    NASA Astrophysics Data System (ADS)

    Tickle, Andrew J.; Buckle, James; Grindley, Josef E.; Smith, Jeremy S.

    2010-10-01

    Stereo vision is a situation where an imaging system has two or more cameras in order to make it more robust by mimicking the human vision system. By using two inputs, knowledge of their own relative geometry can be exploited to derive depth information from the two views they receive. 3D co-ordinates of an object in an observed scene can be computed from the intersection of the two sets of rays. Presented here is the development of a stereo vision system to focus on an object at the centre of a baseline between two cameras at varying distances. This has been developed primarily for use on a Field Programmable Gate Array (FPGA) but an adaptation of this developed methodology is also presented for use with a PUMA 560 Robotic Manipulator with a single camera attachment. The two main vision systems considered here are a fixed baseline with an object moving at varying distances from this baseline, and a system with a fixed distance and a varying baseline. These two differing situations provide enough data so that the co-efficient variables that determine the system operation can be calibrated automatically with only the baseline value needing to be entered, the system performs all the required calculations for the user for use with a baseline of any distance. The limits of system with regards to the focusing accuracy obtained are also presented along with how the PUMA 560 controls its joints for the stereo vision and how it moves from one position to another to attend stereo vision compared to the two camera system for the FPGA. The benefits of such a system for range finding in mobile robotics are discussed and how this approach is more advantageous when compared against laser range finders or echolocation using ultrasonics.

  10. Physical and electrical properties of induced high-k ZrHfO crystallization with ZrN cap by high power impulse magnetron sputtering for metal-gate metal-insulator-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Tsai, Jung-Ruey; Juan, Pi-Chun; Lin, Cheng-Li; Lin, Guo-Cheng

    2017-01-01

    Metal-gate TiN/ZrN/ZrHfO/p-Si metal-insulator-semiconductor (MIS) structures have been fabricated in this work. The physical and electrical properties were characterized. The crystallization of high-k ZrHfO thin-film is induced by high power impulse magnetron sputtering (HIPIMS) during the deposition of ZrN capping layer. The binding energies and depth profiles were investigated by X-ray photoelectron spectroscopy (XPS). It is found that Zr and Hf out-diffusion from high-k dielectric in samples with HIPIMS is lesser than those in samples with the conventional DC magnetron sputtering (DCMS). The dielectric constant which strongly relates to the tetragonal phase becomes higher and the flatband voltage shift shows smaller by using the HIPIMS method than by the conventional DCMS. The cation and anion vacancies have been investigated by the defect reaction model.

  11. Fabrication of normally-off AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors by photo-electrochemical gate recess etching in ionic liquid

    NASA Astrophysics Data System (ADS)

    Zhang, Zhili; Qin, Shuangjiao; Fu, Kai; Yu, Guohao; Li, Weiyi; Zhang, Xiaodong; Sun, Shichuang; Song, Liang; Li, Shuiming; Hao, Ronghui; Fan, Yaming; Sun, Qian; Pan, Gebo; Cai, Yong; Zhang, Baoshun

    2016-08-01

    We characterized an ionic liquid (1-butyl-3-methylimidazolium nitrate, C8H15N3O3) as a photo-electrochemical etchant for fabricating normally-off AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs). Using the ionic liquid, we achieved an etching rate of ˜2.9 nm/min, which is sufficiently low to facilitate good etching control. The normally-off AlGaN/GaN MIS-HEMT was fabricated with an etching time of 6 min, with the 20 nm low-pressure chemical vapor deposition (LPCVD) silicon nitride (Si3N4) gate dielectric exhibiting a threshold voltage shift from -10 to 1.2 V, a maximum drain current of more than 426 mA/mm, and a breakdown voltage of 582 V.

  12. Improved performance of nanoscale junctionless tunnel field-effect transistor based on gate engineering approach

    NASA Astrophysics Data System (ADS)

    Molaei Imen Abadi, Rouzbeh; Sedigh Ziabari, Seyed Ali

    2016-11-01

    In this paper, a first qualitative study on the performance characteristics of dual-work function gate junctionless TFET (DWG-JLTFET) on the basis of energy band profile modulation is investigated. A dual-work function gate technique is used in a JLTFET in order to create a downward band bending on the source side similar to PNPN structure. Compared with the single-work function gate junctionless TFET (SWG-JLTFET), the numerical simulation results demonstrated that the DWG-JLTFET simultaneously optimizes the ON-state current, the OFF-state leakage current, and the threshold voltage and also improves average subthreshold slope. It is illustrated that if appropriate work functions are selected for the gate materials on the source side and the drain side, the JLTFET exhibits a considerably improved performance. Furthermore, the optimization design of the tunnel gate length ( L Tun) for the proposed DWG-JLTFET is studied. All the simulations are done in Silvaco TCAD for a channel length of 20 nm using the nonlocal band-to-band tunneling (BTBT) model.

  13. Performance analysis of InGaAs/GaAsP heterojunction double gate tunnel field effect transistor

    NASA Astrophysics Data System (ADS)

    Ahish, S.; Sharma, Dheeraj; Vasantha, M. H.; Kumar, Y. B. N.

    2017-03-01

    In this paper, analog/RF performance of InGaAs/GaAsP heterojunction double gate tunnel field effect transistor (HJTFET) has been explored. A highly doped n+ layer is placed at the Source-Channel junction in order to improve the horizontal electric field component and thus, improve the realiability of the device. The analog performance of the device is analysed by extracting current-voltage characteristics, transcondutance (gm), gate-to-drain capacitance (Cgd) and gate-to-source capacitance (Cgs). Further, RF performance of the device is evaluated by obtaining cut-off frequency (fT) and Gain Bandwidth (GBW) product. ION /IOFF ratio equal to ≈ 109, subthreshold slope of 27 mV/dec, maximum fT of 2.1 THz and maximum GBW of 484 GHz were achieved. Also, the impact of temperature variation on the linearity performance of the device has been investigated. Furthermore, the circuit level performance of the device is performed by implementing a Common Source (CS) amplifier; maximum gain of 31.11 dB and 3-dB cut-off frequency equal to 91.2 GHz were achieved for load resistance (RL) = 17.5 KΩ.

  14. Fabrication and electrical properties of MoS2 nanodisc-based back-gated field effect transistors

    PubMed Central

    2014-01-01

    Two-dimensional (2D) molybdenum disulfide (MoS2) is an attractive alternative semiconductor material for next-generation low-power nanoelectronic applications, due to its special structure and large bandgap. Here, we report the fabrication of large-area MoS2 nanodiscs and their incorporation into back-gated field effect transistors (FETs) whose electrical properties we characterize. The MoS2 nanodiscs, fabricated via chemical vapor deposition (CVD), are homogeneous and continuous, and their thickness of around 5 nm is equal to a few layers of MoS2. In addition, we find that the MoS2 nanodisc-based back-gated field effect transistors with nickel electrodes achieve very high performance. The transistors exhibit an on/off current ratio of up to 1.9 × 105, and a maximum transconductance of up to 27 μS (5.4 μS/μm). Moreover, their mobility is as high as 368 cm2/Vs. Furthermore, the transistors have good output characteristics and can be easily modulated by the back gate. The electrical properties of the MoS2 nanodisc transistors are better than or comparable to those values extracted from single and multilayer MoS2 FETs. PMID:24576344

  15. Electric field assisted low-temperature growth of SiGe on insulating films for future TFT

    NASA Astrophysics Data System (ADS)

    Miyao, Masanobu; Kanno, Hiroshi; Sadoh, Taizoh

    2008-02-01

    Development of new semiconductors with high mobility is strongly needed to realize future system-in-displays. To achieve this, we have been investigating electric field assisted metal-induced lateral crystallization (MILC) of a-Si 1-XGe X (0insulating substrates. This realizes uniform crystal growth of SiGe with all Ge fractions. In addition, thin-film transistors (TFTs) with Schottky source and drain structures were fabricated, which showed good ambipolar operation characteristics. Present paper reviews such our recent progress of electric field assisted low temperature SiGe growth and discusses the possible application to TFTs with high speed operation.

  16. Semiconducting properties of bilayer graphene modulated by an electric field for next-generation atomic-film electronics

    NASA Astrophysics Data System (ADS)

    Tsukagoshi, K.; Li, S.-L.; Miyazaki, H.; Aparecido-Ferreira, A.; Nakaharai, S.

    2014-03-01

    A practical wide bandgap was induced in bilayer graphene using a perpendicular electric field. A self-assembled gate insulator was used to apply a large electric field. The wide bandgap allows the operation of fundamental logic gates composed of bilayer graphene transistors. The results reviewed here indicate the potential for graphene electronics to be realized as emerging transistors with an atomically thin semiconductor.

  17. Gate dielectric ion implantation to modulate the threshold voltage of In2O3 nanowire field effect transistors

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Li, Wenqing; Wu, Pengcheng; Jiang, Changzhong; Xiao, Xiangheng

    2016-11-01

    In semiconductor technology, In2O3 nanowire field effect transistor (FET) can serve as an important building block due to its admirable electrical switching properties. However, the relatively too large threshold voltages and threshold voltage fluctuations of the devices may hinder their extensive applications. In this report, N+ ion implantation of gate dielectric was conducted to modulate the threshold voltage of In2O3 nanowire FET. Electrical measurements reveal that the threshold voltage can be reduced to as low as -2.0 V from the initial -23.2 V after ion implantation. This can be attributed to the effects of implantation induced electron traps. Moreover, it is found that the stability of threshold voltage can be improved by ion implantation. This simple and convenient method indicates that gate dielectric ion implantation may be a potential way to realize the low voltage operation and uniform In2O3 nanowire FETs.

  18. Palladium nanoparticle decorated silicon nanowire field-effect transistor with side-gates for hydrogen gas detection

    SciTech Connect

    Ahn, Jae-Hyuk; Yun, Jeonghoon; Park, Inkyu; Choi, Yang-Kyu

    2014-01-06

    A silicon nanowire field-effect transistor (SiNW FET) with local side-gates and Pd surface decoration is demonstrated for hydrogen (H{sub 2}) detection. The SiNW FETs are fabricated by top-down method and functionalized with palladium nanoparticles (PdNPs) through electron beam evaporation for H{sub 2} detection. The drain current of the PdNP-decorated device reversibly responds to H{sub 2} at different concentrations. The local side-gates allow individual addressing of each sensor and enhance the sensitivity by adjusting the working region to the subthreshold regime. A control experiment using a non-functionalized device verifies that the hydrogen-sensitivity is originated from the PdNPs functionalized on the SiNW surface.

  19. A compact quantum correction model for symmetric double gate metal-oxide-semiconductor field-effect transistor

    SciTech Connect

    Cho, Edward Namkyu; Shin, Yong Hyeon; Yun, Ilgu

    2014-11-07

    A compact quantum correction model for a symmetric double gate (DG) metal-oxide-semiconductor field-effect transistor (MOSFET) is investigated. The compact quantum correction model is proposed from the concepts of the threshold voltage shift (ΔV{sub TH}{sup QM}) and the gate capacitance (C{sub g}) degradation. First of all, ΔV{sub TH}{sup QM} induced by quantum mechanical (QM) effects is modeled. The C{sub g} degradation is then modeled by introducing the inversion layer centroid. With ΔV{sub TH}{sup QM} and the C{sub g} degradation, the QM effects are implemented in previously reported classical model and a comparison between the proposed quantum correction model and numerical simulation results is presented. Based on the results, the proposed quantum correction model can be applicable to the compact model of DG MOSFET.

  20. Gas Sensors Characterization and Multilayer Perceptron (MLP) Hardware Implementation for Gas Identification Using a Field Programmable Gate Array (FPGA)

    PubMed Central

    Benrekia, Fayçal; Attari, Mokhtar; Bouhedda, Mounir

    2013-01-01

    This paper develops a primitive gas recognition system for discriminating between industrial gas species. The system under investigation consists of an array of eight micro-hotplate-based SnO2 thin film gas sensors with different selectivity patterns. The output signals are processed through a signal conditioning and analyzing system. These signals feed a decision-making classifier, which is obtained via a Field Programmable Gate Array (FPGA) with Very High-Speed Integrated Circuit Hardware Description Language. The classifier relies on a multilayer neural network based on a back propagation algorithm with one hidden layer of four neurons and eight neurons at the input and five neurons at the output. The neural network designed after implementation consists of twenty thousand gates. The achieved experimental results seem to show the effectiveness of the proposed classifier, which can discriminate between five industrial gases. PMID:23529119

  1. Numerical analysis of the transient temperature field of the multilayer insulative systems of Space Shuttle

    NASA Astrophysics Data System (ADS)

    Geng, Weiqun; Yang, Maozhao; Huang, Zhenzhong

    1992-09-01

    The finite difference method and the finite element method have been used to determine the temperature distribution through the multilayer insulative systems of the Space Shuttle. The computed results have been compared with STS-2 flight data and other experimental results; they show good agreement.

  2. Silicon Carbide Junction Field Effect Transistor Digital Logic Gates Demonstrated at 600 deg. C

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.

    1998-01-01

    The High Temperature Integrated Electronics and Sensors (HTIES) Program at the NASA Lewis Research Center is currently developing silicon carbide (SiC) for use in harsh conditions where silicon, the semiconductor used in nearly all of today's electronics, cannot function. The HTIES team recently fabricated and demonstrated the first semiconductor digital logic gates ever to function at 600 C.

  3. Short-Channel Tunneling Field-Effect Transistor with Drain-Overlap and Dual-Metal Gate Structure for Low-Power and High-Speed Operations.

    PubMed

    Yoon, Young Jun; Eun, Hye Rim; Seo, Jae Hwa; Kang, Hee-Sung; Lee, Seong Min; Lee, Jeongmin; Cho, Seongjae; Tae, Heung-Sik; Lee, Jung-Hee; Kang, In Man

    2015-10-01

    We have investigated and proposed a highly scaled tunneling field-effect transistor (TFET) based on Ge/GaAs heterojunction with a drain overlap to suppress drain-induced barrier thinning (DIBT) and improve low-power (LP) performance. The highly scaled TFET with a drain overlap achieves lower leakage tunneling current because of the decrease in tunneling events between the source and drain, whereas a typical short-channel TFET suffers from a great deal of tunneling leakage current due to the DIBT at the off-state. However, the drain overlap inevitably increases the gate-to-drain capacitance (Cgd) because of the increase in the overlap capacitance (Cov) and inversion capacitance (Cinv). Thus, in this work, a dual-metal gate structure is additionally applied along with the drain overlap. The current performance and the total gate capacitance (Cgg) of the device with a dual-metal gate can be possibly controlled by adjusting the metal gate workfunction (φgate) and φoverlap-gate in the overlapping regions. As a result, the intrinsic delay time (τ) is greatly reduced by obtaining lower Cgg divided by the on-state current (Ion), i.e., Cgg/Ion. We have successfully demonstrated excellent LP and high-speed performance of a highly scaled TFET by adopting both drain overlap and dual-metal gate with DIBT minimization.

  4. Effect of crystal-field splitting and interband hybridization on the metal-insulator transitions of strongly correlated systems

    NASA Astrophysics Data System (ADS)

    Poteryaev, Alexander I.; Ferrero, Michel; Georges, Antoine; Parcollet, Olivier

    2008-07-01

    We investigate a quarter-filled two-band Hubbard model involving a crystal-field splitting, which lifts the orbital degeneracy as well as an interorbital hopping (interband hybridization). Both terms are relevant to the realistic description of correlated materials such as transition-metal oxides. The nature of the Mott metal-insulator transition is clarified and is found to depend on the magnitude of the crystal-field splitting. At large values of the splitting, a transition from a two-band to a one-band metal is first found as the on-site repulsion is increased and is followed by a Mott transition for the remaining band, which follows the single-band (Brinkman-Rice) scenario well documented previously within dynamical mean-field theory. At small values of the crystal-field splitting, a direct transition from a two-band metal to a Mott insulator with partial orbital polarization is found, which takes place simultaneously for both orbitals. This transition is characterized by a vanishing of the quasiparticle weight for the majority orbital but has a first-order character for the minority orbital. It is pointed out that finite-temperature effects may easily turn the metallic regime into a bad metal close to the orbital polarization transition in the metallic phase.

  5. Effect of Surface-optical Phonons on the Charge Transport in Wrap-gated Semiconducting Nanowire Field-effect Transistors

    NASA Astrophysics Data System (ADS)

    Konar, Aniruddha; Fang, Tian; Jena, Debdeep

    2010-03-01

    Surface phonons (SO-phonons) arise at the boundary of two different dielectric mediums. Though the effect of electron-surface phonon scattering on low-filed charge transport has been studied extensively for thin Si-MOSFET [1] and graphene [2], its effect on the 1D nanowire devices has not studied so far. Vibrating diploes in polar gate-dielectric induces a time-varying potential inside the nanowires. The frequencies of these time-varying fields have been calculated by implementing electrostatic boundary conditions at different interfaces of nanowire-dielectric-metal system. Our calculation shows that the electron-SO phonon interaction strength decays exponentially from the gate-nanowire interface towards the nanowire axis. Electron-SO phonon scattering rate has been calculated using Boltzmann transport equation under relaxation time approximation. We find that for thin nanowires (radius 1-20 nm), electron-SO phonon scattering rate is comparable to other dominant scattering mechanisms (such as impurity and bulk optical phonon scatterings) and reduces carrier mobility significantly. Calculating surface-phonon limited mobility of Si nanowires on various available common dielectrics, we have predicted the optimum choice of gate-dielectrics for nanowire-based electronic devices. [4pt] [1] M. V. Fischetti et. al J. Appl. Phys. 90 4581 (2001). [0pt] [2] A. Konar et. al. arXiv: 0902.0819.

  6. Water-Gated n-Type Organic Field-Effect Transistors for Complementary Integrated Circuits Operating in an Aqueous Environment

    PubMed Central

    2017-01-01

    The first demonstration of an n-type water-gated organic field-effect transistor (WGOFET) is here reported, along with simple water-gated complementary integrated circuits, in the form of inverting logic gates. For the n-type WGOFET active layer, high-electron-affinity organic semiconductors, including naphthalene diimide co-polymers and a soluble fullerene derivative, have been compared, with the latter enabling a high electric double layer capacitance in the range of 1 μF cm–2 in full accumulation and a mobility–capacitance product of 7 × 10–3 μF/V s. Short-term stability measurements indicate promising cycling robustness, despite operating the device in an environment typically considered harsh, especially for electron-transporting organic molecules. This work paves the way toward advanced circuitry design for signal conditioning and actuation in an aqueous environment and opens new perspectives in the implementation of active bio-organic interfaces for biosensing and neuromodulation. PMID:28180187

  7. Selective nitrate detection by an enzymatic sensor based on an extended-gate type organic field-effect transistor.

    PubMed

    Minami, Tsuyoshi; Sasaki, Yui; Minamiki, Tsukuru; Wakida, Shin-Ichi; Kurita, Ryoji; Niwa, Osamu; Tokito, Shizuo

    2016-07-15

    First selective nitrate biosensor device based on an extended-gate type organic field-effect transistor (OFET) is reported. The fabricated sensor device consists of the extended-gate electrode functionalized by a nitrate reductase with a mediator (=a bipyridinium derivative) and an OFET-based transducer. The mechanism of the nitrate detection can be explained by an electron-relay on the extended-gate electrode, resulting in changes of the electric properties of the OFET. The detection limit of nitrate in water is estimated to be 45 ppb, which suggests that the sensitivity of our fabricated sensor is comparable to those of some conventional detection methods. As a practical application of the OFET sensor, the nitrate detection in diluted human saliva has been successfully demonstrated; the results agreed well with those by conventional colorimetric measurement. The advantages of OFETs are printability, mechanical flexibility, stretchability and disposability, meaning that the fabricated OFET could open up a new approach for low-cost electronic devices toward on-site detection of nitrate in aqueous media.

  8. Water-Gated n-Type Organic Field-Effect Transistors for Complementary Integrated Circuits Operating in an Aqueous Environment.

    PubMed

    Porrazzo, Rossella; Luzio, Alessandro; Bellani, Sebastiano; Bonacchini, Giorgio Ernesto; Noh, Yong-Young; Kim, Yun-Hi; Lanzani, Guglielmo; Antognazza, Maria Rosa; Caironi, Mario

    2017-01-31

    The first demonstration of an n-type water-gated organic field-effect transistor (WGOFET) is here reported, along with simple water-gated complementary integrated circuits, in the form of inverting logic gates. For the n-type WGOFET active layer, high-electron-affinity organic semiconductors, including naphthalene diimide co-polymers and a soluble fullerene derivative, have been compared, with the latter enabling a high electric double layer capacitance in the range of 1 μF cm(-2) in full accumulation and a mobility-capacitance product of 7 × 10(-3) μF/V s. Short-term stability measurements indicate promising cycling robustness, despite operating the device in an environment typically considered harsh, especially for electron-transporting organic molecules. This work paves the way toward advanced circuitry design for signal conditioning and actuation in an aqueous environment and opens new perspectives in the implementation of active bio-organic interfaces for biosensing and neuromodulation.

  9. New optical gating technique for detection of electric field waveforms with subpicosecond resolution

    NASA Astrophysics Data System (ADS)

    Muraviev, Andrey; Gutin, Alexey; Rupper, Greg; Rudin, Sergey; Shen, Xiaohan; Yamaguchi, Masashi; Aizin, Gregory; Shur, Michael

    2016-06-01

    We report on the new optical gating technique used for the direct photoconductive detection of short pulses of terahertz radiation with the resolution up to 250 femtoseconds. The femtosecond optical laser pulse time delayed with respect to the THz pulse generated a large concentration of the electron hole pairs in the AlGaAs/InGaAs High Electron Mobility Transistor (HEMT) drastically increasing the conductivity on the femtosecond scale and effectively shorting the source and drain. This optical gating quenched the response of the plasma waves launched by the THz pulse and allowed us to reproduce the waveform of the THz pulse by varying the time delay between the THz and quenching optical pulses. The results are in excellent agreement with the electro-optic effect measurements and with our hydrodynamic model that predicts the ultra-fast transistor plasmonic response at the time scale much shorter than the electron transit time, in full agreement with the measured data.

  10. Measurement of Ion Transverse Energy and the Electric Field in the Acceleration Gap of a Magnetically Insulated Diode

    DTIC Science & Technology

    1983-05-01

    practical diodes. The principles of the measurements in the present experiment are as follows. The accelerating ions, drawn from a surface - flashover ...magnetic field6 for magnetic insulation at the applied voltge of 400 kV is 5.7 kG. When the high voltage pulse was applied, a surface - flashover plasma ...the presence of multikilovolt Ba+ ions even ignor- ing the normal 10-15 ns turn-on time of the surface flashover anode plasma . 1 In Fig. 3, the total

  11. 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.

  12. Sub-15 nm gate-all-around field effect transistors on vertical silicon nanowires

    NASA Astrophysics Data System (ADS)

    Larrieu, G.; Guerfi, Y.; Han, X. L.; Clément, N.

    2017-04-01

    A vertical MOS architecture implemented on Si nanowire (NW) array with a scaled Gate-All-Around (14 nm) and symmetrical diffusive S/D contacts is presented with noteworthy demonstrations in both processing (layer engineering at nanoscale), and in electrical properties (high electrostatic control, low defect level, multi-Vt platform). Furthermore, the versatility and reliability of this technology is evidenced with a CMOS inverter, providing bright perspectives for ultimate scaling.

  13. Initial Single Event Effects Testing of the Xilinx Virtex-4 Field Programmable Gate Array

    NASA Technical Reports Server (NTRS)

    Allen, Gregory R.; Swift, Gary M.; Carmichael, C.; Tseng, C.

    2007-01-01

    We present initial results for the thin epitaxial Xilinx Virtex-4 Fie ld Programmable Gate Array (FPGA), and compare to previous results ob tained for the Virtex-II and Virtex-II Pro. The data presented was a cquired through a consortium based effort with the common goal of pr oviding the space community with data and mitigation methods for the use of Xilinx FPGAs in space.

  14. Methods for heat transfer and temperature field analysis of the insulated diesel, phase 3

    NASA Technical Reports Server (NTRS)

    Morel, Thomas; Wahiduzzaman, Syed; Fort, Edward F.; Keribar, Rifat; Blumberg, Paul N.

    1988-01-01

    Work during Phase 3 of a program aimed at developing a comprehensive heat transfer and thermal analysis methodology for design analysis of insulated diesel engines is described. The overall program addresses all the key heat transfer issues: (1) spatially and time-resolved convective and radiative in-cylinder heat transfer, (2) steady-state conduction in the overall structure, and (3) cyclical and load/speed temperature transients in the engine structure. These are all accounted for in a coupled way together with cycle thermodynamics. This methodology was developed during Phases 1 and 2. During Phase 3, an experimental program was carried out to obtain data on heat transfer under cooled and insulated engine conditions and also to generate a database to validate the developed methodology. A single cylinder Cummins diesel engine was instrumented for instantaneous total heat flux and heat radiation measurements. Data were acquired over a wide range of operating conditions in two engine configurations. One was a cooled baseline. The other included ceramic coated components (0.050 inches plasma sprayed zirconia)-piston, head and valves. The experiments showed that the insulated engine has a smaller heat flux than the cooled one. The model predictions were found to be in very good agreement with the data.

  15. Cycle of charge carrier states with formation and extinction of a floating gate in an ambipolar tetracyanoquaterthienoquinoid-based field-effect transistor

    NASA Astrophysics Data System (ADS)

    Itoh, Takuro; Toyota, Taro; Higuchi, Hiroyuki; Matsushita, Michio M.; Suzuki, Kentaro; Sugawara, Tadashi

    2017-03-01

    A tetracyanoquaterthienoquinoid (TCT4Q)-based field effect transistor is characterized by the ambipolar transfer characteristics and the facile shift of the threshold voltage induced by the bias stress. The trapping and detrapping kinetics of charge carriers was investigated in detail by the temperature dependence of the decay of source-drain current (ISD). We found a repeatable formation of a molecular floating gate is derived from a 'charge carrier-and-gate' cycle comprising four stages, trapping of mobile carriers, formation of a floating gate, induction of oppositely charged mobile carriers, and recombination between mobile and trapped carriers to restore the initial state.

  16. An Organic Field-effect Transistor with an Extended-gate Electrode Capable of Detecting Human Immunoglobulin A.

    PubMed

    Minamiki, Tsukuru; Minami, Tsuyoshi; Sasaki, Yui; Kurita, Ryoji; Niwa, Osamu; Wakida, Shin-ichi; Tokito, Shizuo

    2015-01-01

    We herein report on the development of an extended-gate type organic field-effect transistor (OFET)-based immunosensor for the detection of human immunoglobulin A (IgA). The titration results of IgA exhibited shifts in the transfer characteristics of the OFET sensor device with increasing IgA concentration. A linear detection range from 0 to 10 μg/mL was realized with a detection limit of 2.1 μg/mL, indicating that the OFET-based immunosensor can be potentially applied to the monitoring of infectious diseases and psychological stress in daily life.

  17. Compact field programmable gate array-based pulse-sequencer and radio-frequency generator for experiments with trapped atoms

    SciTech Connect

    Pruttivarasin, Thaned; Katori, Hidetoshi

    2015-11-15

    We present a compact field-programmable gate array (FPGA) based pulse sequencer and radio-frequency (RF) generator suitable for experiments with cold trapped ions and atoms. The unit is capable of outputting a pulse sequence with at least 32 transistor-transistor logic (TTL) channels with a timing resolution of 40 ns and contains a built-in 100 MHz frequency counter for counting electrical pulses from a photo-multiplier tube. There are 16 independent direct-digital-synthesizers RF sources with fast (rise-time of ∼60 ns) amplitude switching and sub-mHz frequency tuning from 0 to 800 MHz.

  18. 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.

  19. Scaling analysis of field-tuned superconductor–insulator transition in two-dimensional tantalum thin films

    NASA Astrophysics Data System (ADS)

    Park, Sungyu; Shin, Junghyun; Kim, Eunseong

    2017-02-01

    The superconductor–insulator (SI) transition in two-dimensional Ta thin films is investigated by controlling both film thickness and magnetic field. An intriguing metallic phase appears between a superconducting and an insulating phase within a range of film thickness and magnetic field. The temperature and electric field scaling analyses are performed to investigate the nature of the SI transition in the thickness-tuned metallic and superconducting samples. The critical exponents product of νz obtained from the temperature scaling analysis is found to be approximately 0.67 in the entire range of film thickness. On the other hand, an apparent discrepancy is measured in the product of ν(z + 1) by the electric filed analysis. The product values are found to be about 1.37 for the superconducting films and about 1.86 for the metallic films respectively. We find that the discrepancy is the direct consequence of electron heating that introduces additional dissipation channels in the metallic Ta films.

  20. Method for generating linear current-field characteristics and eliminating charging delay in no-insulation superconducting magnets

    NASA Astrophysics Data System (ADS)

    Kim, Seokho; Hahn, Seungyong; Kim, Kwangmin; Larbalestier, David

    2017-03-01

    No-insulation (NI) rare-earth barium copper oxide (REBCO) magnets are promising for high field or high temperature superconducting magnets because they simplify quench protection. However, the turn-to-turn leakage current path induced by the absence of insulation introduces nonlinearities into the magnetic fieldcurrent characteristic and significant delay in reaching the desired field. This paper shows that active feedback control can mitigate both the nonlinearity and the charging delay. To verify our approach, simulations and tests were performed with an NI REBCO magnet made of 13 double-pancake coils. A proportional and integral (PI) feedback control of the power supply was adopted which allowed determination of the appropriate PI gains using dynamic simulations of the equivalent circuit of the NI magnet. Feedback control tests were then performed in liquid nitrogen at 77 K. The time to reach 99.5% of the target magnetic field to become essentially steady-state was reduced by more than 2000 times from 850 s without control to 0.4 s with control. The results demonstrate a potential that one of the most significant perceived disadvantages of an NI magnet can essentially be removed by active feedback control of the power supply current.

  1. Scaling analysis of field-tuned superconductor–insulator transition in two-dimensional tantalum thin films

    PubMed Central

    Park, Sungyu; Shin, Junghyun; Kim, Eunseong

    2017-01-01

    The superconductor–insulator (SI) transition in two-dimensional Ta thin films is investigated by controlling both film thickness and magnetic field. An intriguing metallic phase appears between a superconducting and an insulating phase within a range of film thickness and magnetic field. The temperature and electric field scaling analyses are performed to investigate the nature of the SI transition in the thickness-tuned metallic and superconducting samples. The critical exponents product of νz obtained from the temperature scaling analysis is found to be approximately 0.67 in the entire range of film thickness. On the other hand, an apparent discrepancy is measured in the product of ν(z + 1) by the electric filed analysis. The product values are found to be about 1.37 for the superconducting films and about 1.86 for the metallic films respectively. We find that the discrepancy is the direct consequence of electron heating that introduces additional dissipation channels in the metallic Ta films. PMID:28218296

  2. Low-Frequency Noise in Gate Tunable Topological Insulator Nanowire Field Emission Transistor near the Dirac Point

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Song, Zhi-Jun; Feng, Jun-Ya; Ji, Zhong-Qing; Lu, Li

    2016-08-01

    Not Available Supported by the National Basic Research Program of China under Grant No 2012CB921703, the National Natural Science Foundation of China under Grant Nos 11174357 and 11574379, and the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDB07010300.

  3. Electric field effect near the metal-insulator transition of a two-dimensional electron system in SrTiO3

    NASA Astrophysics Data System (ADS)

    Ahadi, Kaveh; Shoron, Omor F.; Marshall, Patrick B.; Mikheev, Evgeny; Stemmer, Susanne

    2017-02-01

    SmTiO3/SrTiO3 interfaces exhibit a two-dimensional electron system with carrier densities in the order of 3 × 1014 cm-2 due to the polar discontinuity at the interface. Here, electric field effect is used to investigate an electron system at this interface whose carrier density has been depleted substantially by the gate metal and by reducing the thickness of the SmTiO3. At zero applied gate voltage, the sheet resistance exceeds the quantum resistance, h/e2, by more than an order of magnitude, and the SrTiO3 channel is in the hopping transport regime. The electric field modulates the carrier density in the channel, which approaches the transition to a metal at positive gate bias. The channel resistances are found to scale by a single parameter that depends on the gate voltage, similar to two-dimensional electron systems in high-quality semiconductors.

  4. Electroluminescence from individual air-suspended carbon nanotubes within split-gate structures

    NASA Astrophysics Data System (ADS)

    Higashide, N.; Uda, T.; Yoshida, M.; Ishii, A.; Kato, Y. K.

    Electrically induced light emission from chirality-identified single-walled carbon nanotubes are investigated by utilizing split-gate field-effect devices fabricated on silicon-on-insulator substrates. We begin by etching trenches through the top silicon layer into the buried oxide, and the silicon layer is thermally oxidized for use as local gates. We partially remove the oxide and form gate electrodes, then contacts for nanotubes are deposited on both sides of the trench. Catalyst particles are placed on the contacts, and nanotubes are grown over the trench by chemical vapor deposition. We use photoluminescence microscopy to locate the nanotubes and perform excitation spectroscopy to identify their chirality. Gate-induced photoluminescence quenching is used to confirm carrier doping, and electroluminescence intensity is investigated as a function of the split-gate and bias voltages. Work supported by JSPS (KAKENHI 24340066, 26610080), MEXT (Photon Frontier Network Program, Nanotechnology Platform), Canon Foundation, and Asahi Glass Foundation.

  5. Hysteresis modeling in graphene field effect transistors

    SciTech Connect

    Winters, M.; Rorsman, N.; Sveinbjörnsson, E. Ö.

    2015-02-21

    Graphene field effect transistors with an Al{sub 2}O{sub 3} gate dielectric are fabricated on H-intercalated bilayer graphene grown on semi-insulating 4H-SiC by chemical vapour deposition. DC measurements of the gate voltage v{sub g} versus the drain current i{sub d} reveal a severe hysteresis of clockwise orientation. A capacitive model is used to derive the relationship between the applied gate voltage and the Fermi energy. The electron transport equations are then used to calculate the drain current for a given applied gate voltage. The hysteresis in measured data is then modeled via a modified Preisach kernel.

  6. Near-Field Nanoscopy of Metal-Insulator Phase Transitions Towards Synthesis of Novel Correlated Transition Metal Oxides and Their Interaction with Plasmon Resonances

    DTIC Science & Technology

    2016-01-05

    most exciting discoveries in the past few years in condensed matter research is the theoretical foundations of topological insulating electronic...Figure 1b–d) show bright and dark optical contrast due to the coexisting insulating ( dark ) and metallic (bright) phases affecting the nanoscale...separated by a dark contrast from the inner bright surface of the structure. Such an edge fringe is missing in the near-field amplitude image taken

  7. Ferroelectric control of a Mott insulator

    PubMed Central

    Yamada, Hiroyuki; Marinova, Maya; Altuntas, Philippe; Crassous, Arnaud; Bégon-Lours, Laura; Fusil, Stéphane; Jacquet, Eric; Garcia, Vincent; Bouzehouane, Karim; Gloter, Alexandre; Villegas, Javier E.; Barthélémy, Agnès; Bibes, Manuel

    2013-01-01

    The electric field control of functional properties is an important goal in oxide-based electronics. To endow devices with memory, ferroelectric gating is interesting, but usually weak compared to volatile electrolyte gating. Here, we report a very large ferroelectric field-effect in perovskite heterostructures combining the Mott insulator CaMnO3 and the ferroelectric BiFeO3 in its “supertetragonal” phase. Upon polarization reversal of the BiFeO3 gate, the CaMnO3 channel resistance shows a fourfold variation around room temperature, and a tenfold change at ~200 K. This is accompanied by a carrier density modulation exceeding one order of magnitude. We have analyzed the results for various CaMnO3 thicknesses and explain them by the electrostatic doping of the CaMnO3 layer and the presence of a fixed dipole at the CaMnO3/BiFeO3 interface. Our results suggest the relevance of ferroelectric gates to control orbital- or spin-ordered phases, ubiquitous in Mott systems, and pave the way toward efficient Mott-tronics devices. PMID:24089020

  8. Nanofabrication of arrays of silicon field emitters with vertical silicon nanowire current limiters and self-aligned gates

    NASA Astrophysics Data System (ADS)

    Guerrera, S. A.; Akinwande, A. I.

    2016-07-01

    We developed a fabrication process for embedding a dense array (108 cm-2) of high-aspect-ratio silicon nanowires (200 nm diameter and 10 μm tall) in a dielectric matrix and then structured/exposed the tips of the nanowires to form self-aligned gate field emitter arrays using chemical mechanical polishing (CMP). Using this structure, we demonstrated a high current density (100 A cm-2), uniform, and long lifetime (>100 h) silicon field emitter array architecture in which the current emitted by each tip is regulated by the silicon nanowire current limiter connected in series with the tip. Using the current voltage characteristics and with the aid of numerical device models, we estimated the tip radius of our field emission arrays to be ≈4.8 nm, as consistent with the tip radius measured using a scanning electron microscope (SEM).

  9. New isolated gate bipolar transistor two-quadrant chopper power supply for a fast field cycling nuclear magnetic resonance spectrometer

    NASA Astrophysics Data System (ADS)

    Sousa, D. M.; Marques, G. D.; Sebastião, P. J.; Ribeiro, A. C.

    2003-10-01

    This work, presents, for the first time, an Isolated Gate Bipolar Transistor (IGBT) two-quadrant chopper power supply for a fast field cycling (FFC) nuclear magnetic resonance spectrometer. This power supply was designed to achieve a maximum current of 200 A with good efficiency, low semiconductor losses, low cost, and easy maintenance. Both energy storage circuits and dumping circuits are used to obtain switching times less than 2 ms between field levels in agreement with the FFC technique specifications. The current ripple at high currents is better than 1×10-4 and presents a specific shape which can be used for additional compensation using auxiliary circuits. The implemented power supply was tested and been continuously operating with a home-built FFC solenoidal magnet, associated cooling system, and rf units for fields between 0 and 0.2 T.

  10. A radio-frequency source using direct digital synthesis and field programmable gate array for nuclear magnetic resonance.

    PubMed

    Liang, Xiao; Weimin, Wang

    2009-12-01

    A radio-frequency (rf) source for nuclear magnetic resonance (NMR) is described. With the application of direct digital synthesis (DDS), the rf source has the ability to yield rf pulses with short switching time and high resolution in frequency and phase. To facilitate the generation of a soft pulse, a field programmable gate array (FPGA) cooperating with a pulse programmer is used as the auxiliary controller of the DDS chip. Triggered by the pulse programmer, the FPGA automatically controls the DDS to generate soft pulse according to predefined parameters, and the operation mode of the pulse programmer is optimized. The rf source is suitable for being used as transmitter in low-field (<1 T) NMR applications, for example, magnetic resonance imaging and relaxation measurement. As a compact and low-cost module, the rf source is of general use for constructing low-field NMR spectrometer.

  11. A radio-frequency source using direct digital synthesis and field programmable gate array for nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Liang, Xiao; Weimin, Wang

    2009-12-01

    A radio-frequency (rf) source for nuclear magnetic resonance (NMR) is described. With the application of direct digital synthesis (DDS), the rf source has the ability to yield rf pulses with short switching time and high resolution in frequency and phase. To facilitate the generation of a soft pulse, a field programmable gate array (FPGA) cooperating with a pulse programmer is used as the auxiliary controller of the DDS chip. Triggered by the pulse programmer, the FPGA automatically controls the DDS to generate soft pulse according to predefined parameters, and the operation mode of the pulse programmer is optimized. The rf source is suitable for being used as transmitter in low-field (<1 T) NMR applications, for example, magnetic resonance imaging and relaxation measurement. As a compact and low-cost module, the rf source is of general use for constructing low-field NMR spectrometer.

  12. Detangling extrinsic and intrinsic hysteresis for detecting dynamic switch of electric dipoles using graphene field-effect transistors on ferroelectric gates

    NASA Astrophysics Data System (ADS)

    Ma, Chunrui; Gong, Youpin; Lu, Rongtao; Brown, Emery; Ma, Beihai; Li, Jun; Wu, Judy

    2015-11-01

    A transition in source-drain current vs. back gate voltage (ID-VBG) characteristics from extrinsic polar molecule dominant hysteresis to anti-hysteresis induced by an oxygen deficient surface layer that is intrinsic to the ferroelectric thin films has been observed on graphene field-effect transistors on Pb0.92La0.08Zr0.52Ti0.48O3 gates (GFET/PLZT-Gate) during a vacuum annealing process developed to systematically remove the polar molecules adsorbed on the GFET channel surface. This allows the extrinsic and intrinsic hysteresis on GFET/PLZT-gate devices to detangle and the detection of the dynamic switch of electric dipoles using GFETs, taking advantage of their high gating efficiency on ferroelectric gate. A model of the charge trapping and pinning mechanism is proposed to successfully explain the transition. In response to pulsed VBG trains of positive, negative, as well as alternating polarities, respectively, the source-drain current ID variation is instantaneous with the response amplitude following the ID-VBG loops measured by DC VBG with consideration of the remnant polarization after a given VBG pulse when the gate electric field exceeds the coercive field of the PLZT. A detection sensitivity of around 212 dipole per μm2 has been demonstrated at room temperature, suggesting the GFET/ferroelectric-gate devices provide a promising high-sensitivity scheme for uncooled detection of electrical dipole dynamic switch.A transition in source-drain current vs. back gate voltage (ID-VBG) characteristics from extrinsic polar molecule dominant hysteresis to anti-hysteresis induced by an oxygen deficient surface layer that is intrinsic to the ferroelectric thin films has been observed on graphene field-effect transistors on Pb0.92La0.08Zr0.52Ti0.48O3 gates (GFET/PLZT-Gate) during a vacuum annealing process developed to systematically remove the polar molecules adsorbed on the GFET channel surface. This allows the extrinsic and intrinsic hysteresis on GFET/PLZT-gate

  13. Buckley Prize Talk: Electrostatic Control of the Superconductor-Insulator Transition

    NASA Astrophysics Data System (ADS)

    Goldman, Allen

    2015-03-01

    The superconductor-insulator transitions (SITs) of ultra-thin films are among the simplest quantum phase transitions. The ground states of systems that have been studied are usually changed by adjusting the level of disorder, by the application of perpendicular and parallel magnetic fields, by altering the chemical composition, and by the seeding of the surface with pair-breaking magnetic impurities. More recently, realizations of the electric field effect have been used to tune SITs. This has been done with devices employing high dielectric constant gate insulators, as well as with electric double layer transistor devices employing ionic liquids as gate insulators. In addition to disordered ultrathin films, cuprates, and metallic interfaces between insulators have also been studied. The SITs of selected systems will be reviewed with particular attention being paid to the results of finite size scaling analyses of the transitions, and the nature of the insulating states found. In the case of the cuprates, the extent to which their phase diagrams can be traversed will be explored. Finally the potential value of electrostatic gating as a tool in the search for new superconductors will be discussed. This work was supported by the National Science Foundation under awards, DMR-0854752 and DMR-1263316, and by the University of Minnesota MRSEC under Award DMR-1420013.

  14. Tinv Scaling and Gate Leakage Reduction for n-Type Metal Oxide Semiconductor Field Effect Transistor with HfSix/HfO2 Gate Stack by Interfacial Layer Formation Using Ozone-Water-Last Treatment

    NASA Astrophysics Data System (ADS)

    Oshiyama, Itaru; Tai, Kaori; Hirano, Tomoyuki; Yamaguchi, Shinpei; Tanaka, Kazuaki; Hagimoto, Yoshiya; Uemura, Takayuki; Ando, Takashi; Watanabe, Koji; Yamamoto, Ryo; Kanda, Saori; Wang, Junli; Tateshita, Yasushi; Wakabayashi, Hitoshi; Tagawa, Yukio; Tsukamoto, Masanori; Iwamoto, Hayato; Saito, Masaki; Oshima, Masaharu; Toyoda, Satoshi; Nagashima, Naoki; Kadomura, Shingo

    2008-04-01

    In this paper, we demonstrate a wet treatment for the HfSix/HfO2 gate stack of n-type metal oxide semiconductor field effect transistor (nMOSFET) fabricated by a gate-last process in order to scale down the electrical thickness at inversion state Tinv value and reduce the gate leakage Jg. As a result, we succeeded in scaling down Tinv to 1.41 nm without mobility or Jg degradation by ozone-water-last treatment. We found that a high-density interfacial layer (IFL) is formed owing to the ozone-water-last treatment, and Hf diffusion to the IFL is suppressed, which was analyzed by high-resolution angle-resolved spectroscopy.

  15. Effective Work Function Engineering for Aggressively Scaled Planar and Multi-Gate Fin Field-Effect Transistor-Based Devices with High-k Last Replacement Metal Gate Technology

    NASA Astrophysics Data System (ADS)

    Veloso, Anabela; Aik Chew, Soon; Higuchi, Yuichi; Ragnarsson, Lars-Åke; Simoen, Eddy; Schram, Tom; Witters, Thomas; Van Ammel, Annemie; Dekkers, Harold; Tielens, Hilde; Devriendt, Katia; Heylen, Nancy; Sebaai, Farid; Brus, Stephan; Favia, Paola; Geypen, Jef; Bender, Hugo; Phatak, Anup; Chen, Michael S.; Lu, Xinliang; Ganguli, Seshadri; Lei, Yu; Tang, Wei; Fu, Xinyu; Gandikota, Srinivas; Noori, Atif; Brand, Adam; Yoshida, Naomi; Thean, Aaron; Horiguchi, Naoto

    2013-04-01

    This work reports on aggressively scaled replacement metal gate, high-k last devices (RMG-HKL), exploring several options for effective work function (EWF) engineering, and targeting logic high-performance and low-power applications. Tight low-threshold voltage (VT) distributions for scaled NMOS devices are obtained by controlled TiN/TiAl-alloying, either by using RF-physical vapor deposition (RF-PVD) or atomic layer deposition (ALD) for TiN growth. The first technique allows optimization of the TiAl/TiN thicknesses at the bottom of gate trenches while maximizing the space to be filled with a low-resistance metal; using ALD minimizes the occurrence of preferential paths, at gate sidewalls, for Al diffusion into the high-k dielectric, reducing gate leakage (JG). For multi-gate fin field-effect transistors (FinFETs) which require smaller EWF shifts from mid-gap for low-VT: 1) conformal, lower-JG ALD-TiN/TaSiAl; and 2) Al-rich ALD-TiN by controlled Al diffusion from the fill-metal are demonstrated to be promising candidates. Comparable bias temperature instability (BTI), improved noise behavior, and slightly reduced equivalent oxide thickness (EOT) are measured on Al-rich EWF-metal stacks.

  16. Human dopamine receptor nanovesicles for gate-potential modulators in high-performance field-effect transistor biosensors

    PubMed Central

    Park, Seon Joo; Song, Hyun Seok; Kwon, Oh Seok; Chung, Ji Hyun; Lee, Seung Hwan; An, Ji Hyun; Ahn, Sae Ryun; Lee, Ji Eun; Yoon, Hyeonseok; Park, Tai Hyun; Jang, Jyongsik

    2014-01-01

    The development of molecular detection that allows rapid responses with high sensitivity and selectivity remains challenging. Herein, we demonstrate the strategy of novel bio-nanotechnology to successfully fabricate high-performance dopamine (DA) biosensor using DA Receptor-containing uniform-particle-shaped Nanovesicles-immobilized Carboxylated poly(3,4-ethylenedioxythiophene) (CPEDOT) NTs (DRNCNs). DA molecules are commonly associated with serious diseases, such as Parkinson's and Alzheimer's diseases. For the first time, nanovesicles containing a human DA receptor D1 (hDRD1) were successfully constructed from HEK-293 cells, stably expressing hDRD1. The nanovesicles containing hDRD1 as gate-potential modulator on the conducting polymer (CP) nanomaterial transistors provided high-performance responses to DA molecule owing to their uniform, monodispersive morphologies and outstanding discrimination ability. Specifically, the DRNCNs were integrated into a liquid-ion gated field-effect transistor (FET) system via immobilization and attachment processes, leading to high sensitivity and excellent selectivity toward DA in liquid state. Unprecedentedly, the minimum detectable level (MDL) from the field-induced DA responses was as low as 10 pM in real- time, which is 10 times more sensitive than that of previously reported CP based-DA biosensors. Moreover, the FET-type DRNCN biosensor had a rapid response time (<1 s) and showed excellent selectivity in human serum. PMID:24614248

  17. Human dopamine receptor nanovesicles for gate-potential modulators in high-performance field-effect transistor biosensors

    NASA Astrophysics Data System (ADS)

    Park, Seon Joo; Song, Hyun Seok; Kwon, Oh Seok; Chung, Ji Hyun; Lee, Seung Hwan; An, Ji Hyun; Ahn, Sae Ryun; Lee, Ji Eun; Yoon, Hyeonseok; Park, Tai Hyun; Jang, Jyongsik

    2014-03-01

    The development of molecular detection that allows rapid responses with high sensitivity and selectivity remains challenging. Herein, we demonstrate the strategy of novel bio-nanotechnology to successfully fabricate high-performance dopamine (DA) biosensor using DA Receptor-containing uniform-particle-shaped Nanovesicles-immobilized Carboxylated poly(3,4-ethylenedioxythiophene) (CPEDOT) NTs (DRNCNs). DA molecules are commonly associated with serious diseases, such as Parkinson's and Alzheimer's diseases. For the first time, nanovesicles containing a human DA receptor D1 (hDRD1) were successfully constructed from HEK-293 cells, stably expressing hDRD1. The nanovesicles containing hDRD1 as gate-potential modulator on the conducting polymer (CP) nanomaterial transistors provided high-performance responses to DA molecule owing to their uniform, monodispersive morphologies and outstanding discrimination ability. Specifically, the DRNCNs were integrated into a liquid-ion gated field-effect transistor (FET) system via immobilization and attachment processes, leading to high sensitivity and excellent selectivity toward DA in liquid state. Unprecedentedly, the minimum detectable level (MDL) from the field-induced DA responses was as low as 10 pM in real- time, which is 10 times more sensitive than that of previously reported CP based-DA biosensors. Moreover, the FET-type DRNCN biosensor had a rapid response time (<1 s) and showed excellent selectivity in human serum.

  18. Method and infrastructure for cycle-reproducible simulation on large scale digital circuits on a coordinated set of field-programmable gate arrays (FPGAs)

    SciTech Connect

    Asaad, Sameh W; Bellofatto, Ralph E; Brezzo, Bernard; Haymes, Charles L; Kapur, Mohit; Parker, Benjamin D; Roewer, Thomas; Tierno, Jose A

    2014-01-28

    A plurality of target field programmable gate arrays are interconnected in accordance with a connection topology and map portions of a target system. A control module is coupled to the plurality of target field programmable gate arrays. A balanced clock distribution network is configured to distribute a reference clock signal, and a balanced reset distribution network is coupled to the control module and configured to distribute a reset signal to the plurality of target field programmable gate arrays. The control module and the balanced reset distribution network are cooperatively configured to initiate and control a simulation of the target system with the plurality of target field programmable gate arrays. A plurality of local clock control state machines reside in the target field programmable gate arrays. The local clock state machines are configured to generate a set of synchronized free-running and stoppable clocks to maintain cycle-accurate and cycle-reproducible execution of the simulation of the target system. A method is also provided.

  19. Simulated optimum gate and encapsulant properties for a refractory gate GaAs metal-semiconductor field effect transistor during annealing

    SciTech Connect

    Kitajo, S.; Kanamori, M.

    1993-03-01

    The stress distribution in a refractory gate GaAs substrate during annealing was calculated by computer simulation, using the finite element method. Simulations were used to investigate the correlation between the thermal expansion coefficient of the gate and the encapsulant internal stress. The condition in which minimum or no dislocations were induced into the GaAs substrate were studied. It was demonstrate that the best thermal expansion coefficient value of the gate was close to the value that was reported for tungsten. It was concluded that, by controlling the encapsulant thermal stress of SiO{sub 2} or SiN encapsulant, during high temperature annealing, a dislocation-free GaAs substrate could be obtained. 6 refs., 6 figs., 1 tab.

  20. Development of dielectrophoresis separator with an insulating porous membrane using DC-Offset AC Electric Fields.

    PubMed

    Hakoda, Masaru

    2016-09-01

    Our previous studies revealed that the dielectrophoresis method is effective for separating cells having different dielectric properties. The purpose of this study was to evaluate the separation characteristics of two kinds of cells by direct current (DC) voltage offset/alternating current (AC) voltage using an insulating porous membrane dielectrophoretic separator. The separation device gives dielectrophoretic (DEP) force and electrophoretic (EP) force to dispersed particles by applying the DC-offset AC voltage. This device separates cells of different DEP properties by adopting a structure in which only the parallel plate electrodes and the insulating porous membrane are disposed in the flow path through which the cell-suspension flows. The difference in the retention ratios of electrically homogeneous 4.5 μm or 20.0 μm diameter standard particles was a maximum of 82 points. Furthermore, the influences of the AC voltage or offset voltage on the retention ratios of mouse hybridoma 3-2H3 cells and horse red blood cells (HRBC) were investigated. The difference in the retention ratio of the two kinds of cells was a maximum of 56 points. The separation efficiency of this device is expected to be improved by changing the device shape, number of pores, and pore placement. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1292-1300, 2016.