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Sample records for 4h-sic schottky diodes

  1. Silicon Carbide Schottky Barrier Diode

    NASA Technical Reports Server (NTRS)

    Zhao, Jian H.; Sheng, Kuang; Lebron-Velilla, Ramon C.

    2004-01-01

    This chapter reviews the status of SiC Schottky barrier diode development. The fundamental of Schottky barrier diodes is first provided, followed by the review of high-voltage SiC Schottky barrier diodes, junction-barrier Schottky diodes, and merged-pin-Schottky diodes. The development history is reviewed ad the key performance parameters are discussed. Applications of SiC SBDs in power electronic circuits as well as other areas such as gas sensors, microwave and UV detections are also presented, followed by discussion of remaining challenges.

  2. Carbon-Nanotube Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Wong, Eric; Schlecht, Erich; Hunt, Brian; Siegel, Peter

    2006-01-01

    Schottky diodes based on semiconducting single-walled carbon nanotubes are being developed as essential components of the next generation of submillimeter-wave sensors and sources. Initial performance predictions have shown that the performance characteristics of these devices can exceed those of the state-of-the-art solid-state Schottky diodes that have been the components of choice for room-temperature submillimeter-wave sensors for more than 50 years. For state-of-the-art Schottky diodes used as detectors at frequencies above a few hundred gigahertz, the inherent parasitic capacitances associated with their semiconductor junction areas and the resistances associated with low electron mobilities limit achievable sensitivity. The performance of such a detector falls off approximately exponentially with frequency above 500 GHz. Moreover, when used as frequency multipliers for generating signals, state-of-the-art solid-state Schottky diodes exhibit extremely low efficiencies, generally putting out only micro-watts of power at frequencies up to 1.5 THz. The shortcomings of the state-of-the-art solid-state Schottky diodes can be overcome by exploiting the unique electronic properties of semiconducting carbon nanotubes. A single-walled carbon nanotube can be metallic or semiconducting, depending on its chirality, and exhibits high electron mobility (recently reported to be approx.= 2x10(exp 5)sq cm/V-s) and low parasitic capacitance. Because of the narrowness of nanotubes, Schottky diodes based on carbon nanotubes have ultra-small junction areas (of the order of a few square nanometers) and consequent junction capacitances of the order of 10(exp -18) F, which translates to cutoff frequency >5 THz. Because the turn-on power levels of these devices are very low (of the order of nano-watts), the input power levels needed for pumping local oscillators containing these devices should be lower than those needed for local oscillators containing state-of-the-art solid

  3. Organic Schottky diode: Characterization of traps

    NASA Astrophysics Data System (ADS)

    Rani, Varsha; Yadav, Sarita; Ghosh, Subhasis

    2015-06-01

    We have demonstrated the formation and characterization of Schottky junction in metal/organic/metal sandwiched devices based on organic molecular semiconductors, using current-voltage (J-V) and capacitance-voltage (C-V) characteristics, in particular how traps affect the device performance. Ideality factor of organic Schottky diode is always greater than unity and increases with decreasing the temperature. Diffusion coefficient has been determined from current density -voltage characteristic in Schottky diodes.

  4. Schottky barrier diode and method thereof

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid (Inventor); Franz, David (Inventor)

    2008-01-01

    Pt/n.sup.-GaN Schottky barrier diodes are disclosed that are particularly suited to serve as ultra-violet sensors operating at wavelengths below 200 nm. The Pt/n.sup.-GaN Schottky barrier diodes have very large active areas, up to 1 cm.sup.2, which exhibit extremely low leakage current at low reverse biases. Very large area Pt/n.sup.-GaN Schottky diodes of sizes 0.25 cm.sup.2 and 1 cm.sup.2 have been fabricated from n.sup.-/n.sup.+ GaN epitaxial layers grown by vapor phase epitaxy on single crystal c-plane sapphire, which showed leakage currents of 14 pA and 2.7 nA, respectively for the 0.25 cm.sup.2 and 1 cm.sup.2 diodes both configured at a 0.5V reverse bias.

  5. Graphite based Schottky diodes formed semiconducting substrates

    NASA Astrophysics Data System (ADS)

    Schumann, Todd; Tongay, Sefaattin; Hebard, Arthur

    2010-03-01

    We demonstrate the formation of semimetal graphite/semiconductor Schottky barriers where the semiconductor is either silicon (Si), gallium arsenide (GaAs) or 4H-silicon carbide (4H-SiC). The fabrication can be as easy as allowing a dab of graphite paint to air dry on any one of the investigated semiconductors. Near room temperature, the forward-bias diode characteristics are well described by thermionic emission, and the extracted barrier heights, which are confirmed by capacitance voltage measurements, roughly follow the Schottky-Mott relation. Since the outermost layer of the graphite electrode is a single graphene sheet, we expect that graphene/semiconductor barriers will manifest similar behavior.

  6. Destructive Single-Event Failures in Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Casey, Megan C.; Lauenstein, Jean-Marie; Gigliuto, Robert A.; Wilcox, Edward P.; Phan, Anthony M.; Kim, Hak; Chen, Dakai; LaBel, Kenneth A.

    2014-01-01

    This presentation contains test results for destructive failures in DC-DC converters. We have shown that Schottky diodes are susceptible to destructive single-event effects. Future work will be completed to identify parameter that determines diode susceptibility.

  7. SiC-Based Schottky Diode Gas Sensors

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Neudeck, Philip G.; Chen, Liang-Yu; Knight, Dak; Liu, Chung-Chiun; Wu, Quing-Hai

    1997-01-01

    Silicon carbide based Schottky diode gas sensors are being developed for high temperature applications such as emission measurements. Two different types of gas sensitive diodes will be discussed in this paper. By varying the structure of the diode, one can affect the diode stability as well as the diode sensitivity to various gases. It is concluded that the ability of SiC to operate as a high temperature semiconductor significantly enhances the versatility of the Schottky diode gas sensing structure and will potentially allow the fabrication of a SiC-based gas sensor arrays for versatile high temperature gas sensing applications.

  8. Gate Modulation of Graphene-ZnO Nanowire Schottky Diode

    NASA Astrophysics Data System (ADS)

    Liu, Ren; You, Xu-Chen; Fu, Xue-Wen; Lin, Fang; Meng, Jie; Yu, Da-Peng; Liao, Zhi-Min

    2015-05-01

    Graphene-semiconductor interface is important for the applications in electronic and optoelectronic devices. Here we report the modulation of the electric transport properties of graphene/ZnO nanowire Schottky diode by gate voltage (Vg). The ideality factor of the graphene/ZnO nanowire Schottky diode is ~1.7, and the Schottky barrier height is ~0.28 eV without external Vg. The Schottky barrier height is sensitive to Vg due to the variation of Fermi level of graphene. The barrier height increases quickly with sweeping Vg towards the negative value, while decreases slowly towards the positive Vg. Our results are helpful to understand the fundamental mechanism of the electric transport in graphene-semiconductor Schottky diode.

  9. Self-Aligned Guard Rings For Schottky-Barrier Diodes

    NASA Technical Reports Server (NTRS)

    Lin, True-Lon

    1990-01-01

    Proposed self-aligned guard ring increases active area of Schottky-barrier infrared detector. Concept developed for silicide Schottky-barrier diodes in which platinum silicide or iridium silicide Schottky-contacts provide cutoff wavelengths of about 6 or 10 micrometers. Grid of silicon dioxide doped with phosphorus etched on silicon wafer, and phosphorus from grid diffused into substrate, creating n-type guard rings. Silicide layers formed in open areas of grid. Overlap of guard rings and silicide layers small.

  10. Laterally stacked Schottky diodes for infrared sensor applications

    NASA Technical Reports Server (NTRS)

    Lin, True-Lon (Inventor)

    1991-01-01

    Laterally stacked Schottky diodes for infrared sensor applications are fabricated utilizing porous silicon having pores. A Schottky metal contract is formed in the pores, such as by electroplating. The sensors may be integrated with silicon circuits on the same chip with a high quantum efficiency, which is ideal for IR focal plane array applications due to uniformity and reproducibility.

  11. Development and fabrication of improved Schottky power diodes

    NASA Technical Reports Server (NTRS)

    Cordes, L. F.; Garfinkel, M.; Taft, E. A.

    1975-01-01

    Reproducible methods for the fabrication of silicon Schottky diodes have been developed for tungsten, aluminum, conventional platinum silicide, and low temperature platinum silicide. Barrier heights and barrier lowering under reverse bias have been measured, permitting the accurate prediction of forward and reverse diode characteristics. Processing procedures have been developed that permit the fabrication of large area (about 1 sq cm) mesageometry power Schottky diodes with forward and reverse characteristics that approach theoretical values. A theoretical analysis of the operation of bridge rectifier circuits has been performed, which indicates the ranges of frequency and voltage for which Schottky rectifiers are preferred to p-n junctions. Power Schottky rectifiers have been fabricated and tested for voltage ratings up to 140 volts.

  12. Terahertz pulse detection by the GaAs Schottky diodes

    NASA Astrophysics Data System (ADS)

    Laperashvili, Tina; Kvitsiani, Orest; Imerlishvili, Ilia; Laperashvili, David

    2010-06-01

    We present the results of experimental studies of physical properties of the detection process of GaAs Schottky diodes for terahertz frequency radiation. The development of technology in the THz frequency band has a rapid progress recently. Considered as an extension of the microwave and millimeter wave bands, the THz frequency offers greater communication bandwidth than is available at microwave frequencies. The Schottky barrier contact has an important role in the operation of many GaAs devices. GaAs Schottky diodes have been the primary nonlinear device used in millimeter and sub millimeter wave detectors and receivers. GaAs Schottky diodes are especially interesting due to their high mobility transport characteristics, which allows for a large reduction of the resistance-capacitance (RC) time constant and thermal noise. In This work are investigated the electrical and photoelectric properties of GaAs Schottky diodes. Samples were obtained by deposition of different metals (Au, Ni, Pt, Pd, Fe, In, Ga, Al) on semiconductor. For fabrication metal-semiconductor (MS) structures is used original method of metal electrodepositing. In this method electrochemical etching of semiconductor surface occurs just before deposition of metal from the solution, which contains etching material and metal ions together. For that, semiconductor surface cleaning processes and metal deposition carries out in the same technological process. In the experiments as the electrolyte was used aqueous solution of chlorides. Metal deposition was carried out at room temperature.

  13. A novel physical parameter extraction approach for Schottky diodes

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Chen, Xing; Xu, Guang-Hui; Huang, Ka-Ma

    2015-07-01

    Parameter extraction is an important step for circuit simulation methods that are based on physical models of semiconductor devices. A novel physical parameter extraction approach for Schottky diodes is proposed in this paper. By employing a set of analytical formulas, this approach extracts all of the necessary physical parameters of the diode chip in a unique way. It then extracts the package parasitic parameters with a curve-fitting method. To validate the proposed approach, a model HSMS-282c commercial Schottky diode is taken as an example. Its physical parameters are extracted and used to simulate the diode’s electrical characteristics. The simulated results based on the extracted parameters are compared with the measurements and a good agreement is obtained, which verifies the feasibility and accuracy of the proposed approach. Project supported by the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1230112).

  14. Radiation hardness of n-GaN schottky diodes

    SciTech Connect

    Lebedev, A. A. Belov, S. V.; Mynbaeva, M. G.; Strel’chuk, A. M.; Bogdanova, E. V.; Makarov, Yu. N.; Usikov, A. S.; Kurin, S. Yu.; Barash, I. S.; Roenkov, A. D.; Kozlovski, V. V.

    2015-10-15

    Schottky-barrier diodes with a diameter of ∼10 µm are fabricated on n-GaN epitaxial films grown by hydride vapor-phase epitaxy (HVPE) on sapphire substrates. The changes in the parameters of the diodes under irradiation with 15 MeV protons are studied. The carrier removal rate was found to be 130–145 cm{sup –1}. The linear nature of the dependence N = f(D) (N is the carrier concentration, and D, the irradiation dose) shows that compensation of the material is associated with transitions of electrons from shallow donors to deep acceptor levels which are related to primary radiation defects.

  15. Process for preparing schottky diode contacts with predetermined barrier heights

    DOEpatents

    Chang, Y. Austin; Jan, Chia-Hong; Chen, Chia-Ping

    1996-01-01

    A process is provided for producing a Schottky diode having a preselected barrier height .phi..sub.Bn. The substrate is preferably n-GaAs, the metallic contact is derived from a starting alloy of the Formula [.SIGMA.M.sub..delta. ](Al.sub.x Ga.sub.1-x) wherein: .SIGMA.M is a moiety which consists of at least one M, and when more than one M is present, each M is different, M is a Group VIII metal selected from the group consisting of nickel, cobalt, ruthenium, rhodium, indium and platinum, .delta. is a stoichiometric coefficient whose total value in any given .SIGMA.M moiety is 1, and x is a positive number between 0 and 1 (that is, x ranges from greater than 0 to less than 1). Also, the starting alloy is capable of forming with the substrate a two phase equilibrium reciprocal system of the binary alloy mixture [.SIGMA.M.sub..delta. ]Ga-[.SIGMA.M.sub..delta. ]Al-AlAs-GaAs. When members of an alloy subclass within this Formula are each preliminarily correlated with the barrier height .phi..sub.Bn of a contact producable therewith, then Schottky diodes of predetermined barrier heights are producable by sputtering and annealing. Further provided are the product Schottky diodes that are produced according to this process.

  16. Additional electric field in real trench MOS barrier Schottky diode

    NASA Astrophysics Data System (ADS)

    Mamedov, R. K.; Aslanova, A. R.

    2016-04-01

    In real trench MOS barrier Schottky diode (TMBS diode) additional electric field (AEF) the whole is formed in the near contact region of the semiconductor and its propagation space is limited with the barrier metal and the metallic electrodes of MOS structures. Effective potential barrier height TMBS diode is formed via resulting electric field of superposition AEF and electric field of space charge region (SCR) semiconductor. The dependence of the resulting electric field intensity of the distance towards the inside the semiconductor is nonlinear and characterized by a peak at a certain distance from the interface. The thickness of the SCR in TMBS diode becomes equal to the trench depth. Force and energy parameters of the AEF, and thus resulting electric field in the SCR region, become dependent on the geometric design parameters TMBS diode. The forward I-V characteristic TMBS diode is described by the thermionic emission theory as in conventional flat Scottky diode, and in the reverse bias, current is virtually absent at initial voltage, appears abruptly at a certain critical voltage.

  17. Carbon nanotube Schottky diodes using Ti-Schottky and Pt-ohmic contacts for high frequency applications

    NASA Technical Reports Server (NTRS)

    Manohara, Harish M.; Wong, Eric W.; Schlecht, Erich; Hunt, Brian D.; Siegel, Peter H.

    2005-01-01

    We have demonstrated Schottky diodes using semiconducting single-walled nanotubes (s-SWNTs) with titanium Schottky and platinum Ohmic contacts for high-frequency applications. The diodes are fabricated using angled evaporation of dissimilar metal contacts over an s-SWNT. The devices demonstrate rectifying behavior with large reverse bias breakdown voltages of greater than 15 V. To decrease the series resistance, multiple SWNTs are grown in parallel in a single device, and the metallic tubes are burnt-out selectively. At low biases these diodes showed ideality factors in the range of 1.5 to 1.9. Modeling of these diodes as direct detectors at room temperature at 2.5 terahertz (THz) frequency indicates noise equivalent powers (NEP) potentially comparable to that of the state-of-the-art gallium arsenide solid-state Schottky diodes, in the range of 10-13 W(square root)xHz.

  18. Diamond Schottky diodes with ideality factors close to 1

    SciTech Connect

    Fiori, A. Teraji, T. Koide, Y.

    2014-09-29

    The stabilization by vacuum annealing of tungsten carbide/p-diamond Schottky barrier diodes (SBDs) has been investigated. The Schottky barrier height (ϕ{sub B}) and ideality factor (n), at high temperature, were consistently estimated by employing a vertical SBD structure. An exponential drop of ϕ{sub B} in time at 600 K and its stabilization at 1.46 eV after 90 min were reported. The lowest n among SBDs examined was close to 1.0 at 600 K. A linear relation between ϕ{sub B} and n in a statistical electrical characterization suggests a ϕ{sub B} inhomogeneity.

  19. Schottky barrier parameters and low frequency noise characteristics of graphene-germanium Schottky barrier diode

    NASA Astrophysics Data System (ADS)

    Khurelbaatar, Zagarzusem; Kil, Yeon-Ho; Shim, Kyu-Hwan; Cho, Hyunjin; Kim, Myung-Jong; Lee, Sung-Nam; Jeong, Jae-chan; Hong, Hyobong; Choi, Chel-Jong

    2016-03-01

    We investigated the electrical properties of chemical vapor deposition-grown monolayer graphene/n-type germanium (Ge) Schottky barrier diodes (SBD) using current-voltage (I-V) characteristics and low frequency noise measurements. The Schottky barrier parameters of graphene/n-type Ge SBDs, such as Schottky barrier height (VB), ideality factor (n), and series resistance (Rs), were extracted using the forward I-V and Cheung's methods. The VB and n extracted from the forward ln(I)-V plot were found to be 0.63 eV and 1.78, respectively. In contrast, from Cheung method, the VB and n were calculated to be 0.53 eV and 1.76, respectively. Such a discrepancy between the values of VB calculated from the forward I-V and Cheung's methods indicated a deviation from the ideal thermionic emission of graphene/n-type Ge SBD associated with the voltage drop across graphene. The low frequency noise measurements performed at the frequencies in the range of 10 Hz-1 kHz showed that the graphene/n-type Ge SBD had 1/f γ frequency dependence, with γ ranging from 1.09 to 1.12, regardless of applied forward biases. Similar to forward-biased SBDs operating in the thermionic emission mode, the current noise power spectral density of graphene/n-type Ge SBD was linearly proportional to the forward current.

  20. Neutron irradiation effects on gallium nitride-based Schottky diodes

    SciTech Connect

    Lin, Chung-Han; Katz, Evan J.; Zhang, Zhichun; Qiu, Jie; Cao, Lei; Mishra, Umesh K.; Brillson, Leonard J.

    2013-10-14

    Depth-resolved cathodoluminescence spectroscopy (DRCLS), time-resolved surface photovoltage spectroscopy, X-ray photoemission spectroscopy (XPS), and current-voltage measurements together show that fast versus thermal neutrons differ strongly in their electronic and morphological effects on metal-GaN Schottky diodes. Fast and thermal neutrons introduce GaN displacement damage and native point defects, while thermal neutrons also drive metallurgical reactions at metal/GaN interfaces. Defect densities exhibit a threshold neutron fluence below which thermal neutrons preferentially heal versus create new native point defects. Scanning XPS and DRCLS reveal strong fluence- and metal-dependent electronic and chemical changes near the free surface and metal interfaces that impact diode properties.

  1. Alpha particle detection with GaN Schottky diodes

    SciTech Connect

    Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Markov, A. V.; Kozhukhova, E. A.; Gazizov, I. M.; Kolin, N. G.; Merkurisov, D. I.; Boiko, V. M.; Korulin, A. V.; Zalyetin, V. M.; Pearton, S. J.; Lee, I.-H.; Dabiran, A. M.; Chow, P. P.

    2009-11-15

    Ni/GaN Schottky diode radiation detectors were fabricated on 3-mum-thick unintentionally doped n-GaN films grown by molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) and on 12-mum-thick undoped n-GaN layers prepared by epitaxial lateral overgrowth (ELOG). The reverse current of all detector structures was <10{sup -9} A for bias voltages necessary for detector operation, with the level of background donor doping of <10{sup 15} cm{sup -3}. With this doping level the space charge region of the Schottky diode could be extended to the entire thickness of the films. The charge collection efficiency of the detectors was close to 100% for MOCVD and ELOG detectors for alpha-particles with range comparable to the thickness of the layer. Electrical properties and deep trap spectra were also studied. The collection efficiency decreased when the concentra-tion of deep electron traps, particularly E{sub c}-0.6 eV traps, increased in MBE grown films.

  2. Low frequency noise in two-dimensional lateral GaN/AlGaN Schottky diodes

    NASA Astrophysics Data System (ADS)

    Cywiński, G.; Szkudlarek, K.; Kruszewski, P.; Yahniuk, I.; Yatsunenko, S.; Muzioł, G.; Skierbiszewski, C.; Knap, W.; Rumyantsev, S. L.

    2016-07-01

    Schottky diodes with Ni/Au contact to the side of the two dimensional channel in GaN/AlGaN system were fabricated and studied. This kind of lateral heterodimensional diodes demonstrated the ideality factor n = 1.2-1.25 and apparent barrier height φb = (0.59-0.63) eV. The noise measurements within the frequencies range from 1 Hz to 50 kHz showed that the diodes demonstrated the superposition of 1/f and generation recombination noise. In spite of extremely small area of lateral Schottky diodes, the amplitude of noise was similar or even smaller than that for AlGaN and GaN Schottky diodes with the regular contact. This makes GaN-based lateral Schottky diodes to be very promising devices for RF and terahertz applications.

  3. Theory of Giant Rectification in Molecular Schottky Diodes

    NASA Astrophysics Data System (ADS)

    Darancet, Pierre

    Following early theoretical models, efforts towards the synthesis and characterization of more efficient molecular diodes have consisted into attempts to increase the electron rich/poor characters of the donor/acceptor moieties, decrease their conjugation, and imbalance their coupling to the electrodes. The experimental poor performance of single-molecule diodes - with the notable exception of environment-induced diodes - suggests that these physical parameters tend to be mutually exclusive in most molecular systems. In this talk, inspired by recent observations of large rectification ratios at organic bilayers, we will show how molecules with a moiety strongly coupled to a metal electrode can, in principle, be used to optimize these different aspects simultaneously. Using first-principles calculations, we will show that this class of molecular systems -analog to macroscopic Schottky diodes, can display large rectification ratios at low operating voltages The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (Argonne). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.

  4. Development and fabrication of improved Schottky power diodes, phases I and II

    NASA Technical Reports Server (NTRS)

    Cordes, L. F.; Garfinkle, M.; Taft, E. A.

    1974-01-01

    Reproducible methods for the fabrication of silicon Schottky diodes were developed for the metals tungsten, aluminum, conventional platinum silicide and low temperature platinum silicide. Barrier heights and barrier lowering were measured permitting the accurate prediction of ideal forward and reverse diode performance. Processing procedures were developed which permit the fabrication of large area (approximately 1 sqcm) mesa-geometry power Schottky diodes with forward and reverse characteristics that approach theoretical values.

  5. A Schottky/2-DEG varactor diode for millimeter and submillimeter wave multiplier applications

    NASA Technical Reports Server (NTRS)

    Peatman, W. C. B.; Crowe, Thomas W.; Shur, M.; Gelmont, B.

    1992-01-01

    A new Schottky diode is investigated for use as a multiplier element in the millimeter and submillimeter wavelength regions. The new diode is based on the Schottky contact at the edge of a 2-dimensional electron gas (2-DEG). As a negative voltage is applied to the Schottky contact, the depletion layer between the Schottky contact and the 2-DEG expands and the junction capacitance decreases, resulting in a nonlinear capacitance-voltage characteristic. In this paper, we outline the theory, design, fabrication, and evaluation of the new device. Recent results include devices having cutoff frequencies of 1 THz and above. Preliminary multiplier results are also presented.

  6. Tension assisted metal transfer of graphene for Schottky diodes onto wafer scale substrates.

    PubMed

    Lee, Jooho; Lee, Su Chan; Kim, Yongsung; Heo, Jinseong; Lee, Kiyoung; Lee, Dongwook; Kim, Jaekwan; Lee, Sunghee; Lee, Chang Seung; Nam, Min Sik; Jun, Seong Chan

    2016-02-19

    We developed an effective graphene transfer method for graphene/silicon Schottky diodes on a wafer as large as 6 inches. Graphene grown on a large scale substrate was passivated and sealed with a gold layer, protecting graphene from any possible contaminant and keeping good electrical contact. The Au/graphene was transferred by the tension-assisted transfer process without polymer residues. The gold film itself was used directly as the electrodes of a Schottky diode. We demonstrated wafer-scale integration of graphene/silicon Schottky diode using the proposed transfer process. The transmission electron microscopy analysis and relatively low ideality factor of the diodes indicated fewer defects on the interface than those obtained using the conventional poly(methyl methacrylate)-assisted transfer method. We further demonstrated gas sensors as an application of graphene Schottky diodes.

  7. Tension assisted metal transfer of graphene for Schottky diodes onto wafer scale substrates

    NASA Astrophysics Data System (ADS)

    Lee, Jooho; Lee, Su Chan; Kim, Yongsung; Heo, Jinseong; Lee, Kiyoung; Lee, Dongwook; Kim, Jaekwan; Lee, Sunghee; Lee, Chang Seung; Nam, Min Sik; Jun, Seong Chan

    2016-02-01

    We developed an effective graphene transfer method for graphene/silicon Schottky diodes on a wafer as large as 6 inches. Graphene grown on a large scale substrate was passivated and sealed with a gold layer, protecting graphene from any possible contaminant and keeping good electrical contact. The Au/graphene was transferred by the tension-assisted transfer process without polymer residues. The gold film itself was used directly as the electrodes of a Schottky diode. We demonstrated wafer-scale integration of graphene/silicon Schottky diode using the proposed transfer process. The transmission electron microscopy analysis and relatively low ideality factor of the diodes indicated fewer defects on the interface than those obtained using the conventional poly(methyl methacrylate)-assisted transfer method. We further demonstrated gas sensors as an application of graphene Schottky diodes.

  8. Temperature dependent simulation of diamond depleted Schottky PIN diodes

    NASA Astrophysics Data System (ADS)

    Hathwar, Raghuraj; Dutta, Maitreya; Koeck, Franz A. M.; Nemanich, Robert J.; Chowdhury, Srabanti; Goodnick, Stephen M.

    2016-06-01

    Diamond is considered as an ideal material for high field and high power devices due to its high breakdown field, high lightly doped carrier mobility, and high thermal conductivity. The modeling and simulation of diamond devices are therefore important to predict the performances of diamond based devices. In this context, we use Silvaco® Atlas, a drift-diffusion based commercial software, to model diamond based power devices. The models used in Atlas were modified to account for both variable range and nearest neighbor hopping transport in the impurity bands associated with high activation energies for boron doped and phosphorus doped diamond. The models were fit to experimentally reported resistivity data over a wide range of doping concentrations and temperatures. We compare to recent data on depleted diamond Schottky PIN diodes demonstrating low turn-on voltages and high reverse breakdown voltages, which could be useful for high power rectifying applications due to the low turn-on voltage enabling high forward current densities. Three dimensional simulations of the depleted Schottky PIN diamond devices were performed and the results are verified with experimental data at different operating temperatures

  9. Electrical characterization of MEH-PPV based Schottky diodes

    NASA Astrophysics Data System (ADS)

    Nimith, K. M.; Satyanarayan, M. N.; Umesh, G.

    2016-05-01

    MEH-PPV Schottky diodes with and without Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been fabricated and characterized. The highlight of this work is that all the fabrication and characterization steps had been carried out in the ambient conditions and the device fabrication was done without any UV-Ozone surface treatment of ITO anodes. Current Density-Voltage characteristics shows that the addition of hole injection layer (HIL) enhances the charge injection into the polymer layer by reducing the energy barrier across the Indium Tin Oxide (ITO)-Organic interface. The rectification ratio increases to 2.21 from 0.76 at 5V for multilayer devices compared to single layer devices. Further we investigated the effect of an alkali metal fluoride (LiF) by inserting a thin layer in between the organic layer and Aluminum (Al) cathode. The results of these investigations will be discussed in detail.

  10. Graphene-Based Reversible Nano-Switch/Sensor Schottky Diode

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Meador, Michael A.; Theofylaktos, Onoufrios; Pinto, Nicholas J.; Mueller, Carl H.; Santos-Perez, Javier

    2010-01-01

    This proof-of-concept device consists of a thin film of graphene deposited on an electrodized doped silicon wafer. The graphene film acts as a conductive path between a gold electrode deposited on top of a silicon dioxide layer and the reversible side of the silicon wafer, so as to form a Schottky diode. By virtue of the two-dimensional nature of graphene, this device has extreme sensitivity to different gaseous species, thereby serving as a building block for a volatile species sensor, with the attribute of having reversibility properties. That is, the sensor cycles between active and passive sensing states in response to the presence or absence of the gaseous species.

  11. Cumulant Analysis of Detection of Random Process Using a Schottky Diode with δ-DOPING

    NASA Astrophysics Data System (ADS)

    Klyuev, A. V.

    2013-05-01

    We present the results of cumulant analysis for detection of random process using a Schottky diode with δ-doping. The statistical characteristics of the output process of the detector, based on a Schottky diode with δ-doping, are investigated. We discuss noninertial and inertial detection mode. It was shown that at a relatively large dispersion of the input noise a noninertial detection mode occurs.

  12. Simulation of a perfect CVD diamond Schottky diode steep forward current-voltage characteristic

    NASA Astrophysics Data System (ADS)

    Kukushkin, V. A.

    2016-10-01

    The kinetic equation approach to the simulation of the perfect CVD diamond Schottky diode current-voltage characteristic is considered. In result it is shown that the latter has a significantly steeper forward branch than that of perfect devices of such a type on usual semiconductors. It means that CVD diamond-based Schottky diodes have an important potential advantage over analogous devices on conventional materials.

  13. High-Voltage AlGaN/GaN-Based Lateral Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Kang, He; Wang, Quan; Xiao, Hong-Ling; Wang, Cui-Mei; Jiang, Li-Juan; Feng, Chun; Chen, Hong; Yin, Hai-Bo; Wang, Xiao-Liang; Wang, Zhan-Guo; Hou, Xun

    2014-06-01

    Lateral Schottky barrier diodes (SBDs) on AlGaN/GaN heterojunctions are fabricated and studied. The characteristics of the fabricated SBDs with different Schottky contact diameters and different Schottky-Ohmic contact spacings are investigated. The breakdown voltage can be increased by either increasing the Schottky-Ohmic contact spacing or increasing the Schottky contact diameter. However, the specific on-resistance is increased at the same time. A high breakdown voltage of 1400 V and low reverse leakage current below 20nA are achieved by the device with a Schottky contact diameter of 100 μm and a contact spacing of 40 μm, yielding a high V2BR/RON,sp value of 194 MW.cm-2.

  14. Questions of the analysis of millimeter-wave frequency converters on diodes with a Schottky barrier

    NASA Technical Reports Server (NTRS)

    Bordonskiy, G. S.

    1977-01-01

    Millimeter-wave frequency converters on a diode with a Schottky barrier were analyzed. The analysis includes investigation of the effect of the variable capacitance of the diode's elements on the frequency converters. Specifically, the transmission, impedance, and noise characteristics of the frequency converters were examined.

  15. Mechanism for nearly ohmic behavior in annealed Au/n-GaAs Schottky diodes

    NASA Technical Reports Server (NTRS)

    Leon, R. P.; Newman, N.; Liliental-Weber, Z.; Weber, E. R.; Washburn, J.

    1989-01-01

    The mechanism of the ohmic behavior commonly observed after annealing Au/n-GaAs 110-oriented Schottky diodes was investigated using electron-beam-induced current (EBIC) measurements, secondary electron imaging (SEI), and SEM and TEM observations. The results showed that the ohmic behavior of annealed Schottky diodes originates from a shunt current pathway at the diode periphery. The SEI, EBIC, and electrical measurements indicated that the ohmic leakage current is due to the surface recombinations at the exposed surface of GaAs between elongated Au crystallites.

  16. Minority carrier injection and current-voltage characteristics of Schottky diodes at high injection level

    NASA Astrophysics Data System (ADS)

    Mnatsakanov, Tigran T.; Levinshtein, Michael E.; Tandoev, Alexey G.; Yurkov, Sergey N.; Palmour, John W.

    2016-07-01

    Transport phenomena in Schottky diodes are analyzed at high injection levels of minority carriers. It is shown that the correct description of these phenomena requires that the mode of diffusion stimulated by the quasi-neutral drift (DSQD) should be considered. An analytical expression for current-voltage characteristics of a Schottky diode at high injection levels is derived. The expression predicts a seemingly paradoxical result: the higher the base doping level, the higher the voltage drop across a diode at the same current density. The analytical results are confirmed by computer simulations. The results may be important for analyses of SiC Junction Barrier Schottky (JBS) diodes at very high current densities (surge current mode).

  17. Schottky Diodes Based on Polyaniline/Multi-Walled Carbon Nanotube Composites

    NASA Astrophysics Data System (ADS)

    Hajibadali, A.; Nejad, M. Baghaei; Farzi, G.

    2015-08-01

    Polyaniline/multi-walled carbon nanotube composites (PANI/MWCNT), with various concentration of multi-walled carbon nanotube, were synthesized. Several Schottky diodes were fabricated, where PANI or PANI/MWCNT composites, aluminum, and gold were used as semiconductor, Schottky contact, and ohmic contact, respectively. Then current-voltage characteristics of the fabricated diodes were measured at room temperature and within the bias range of -5 to +5 V. The measurements were repeated three times for each sample to verify repeatability of experiment. The obtained results show that by increasing the MWCNT concentration, the current intensity increases. Furthermore, I-V characteristics of pure polyaniline Schottky diode follows the thermionic emission mechanism while the I-V characteristics of Schottky diodes based on PANI/MWCNT composites show two distinct power law regions. At lower voltages, the mechanism follows Ohm's Law, whereas at higher voltages, the mechanism is compatible with space charge limited conduction emission mechanism. The parameters of Schottky diodes were determined, and it was observed that critical voltage decreased when the concentration of MWCNT in the composite increased.

  18. Barrier inhomogeneities limited current and 1/f noise transport in GaN based nanoscale Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Kumar, Ashutosh; Heilmann, M.; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M.; Christiansen, Silke H.; Kumar, Vikram; Singh, Rajendra

    2016-06-01

    The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained.

  19. Barrier inhomogeneities limited current and 1/f noise transport in GaN based nanoscale Schottky barrier diodes.

    PubMed

    Kumar, Ashutosh; Heilmann, M; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M; Christiansen, Silke H; Kumar, Vikram; Singh, Rajendra

    2016-01-01

    The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained.

  20. Barrier inhomogeneities limited current and 1/f noise transport in GaN based nanoscale Schottky barrier diodes

    PubMed Central

    Kumar, Ashutosh; Heilmann, M.; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M.; Christiansen, Silke H.; Kumar, Vikram; Singh, Rajendra

    2016-01-01

    The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained. PMID:27282258

  1. Bias stress instability involving subgap state transitions in a-IGZO Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Qian, Huimin; Wu, Chenfei; Lu, Hai; Xu, Weizong; Zhou, Dong; Ren, Fangfang; Chen, Dunjun; Zhang, Rong; Zheng, Youdou

    2016-10-01

    Vertical Schottky barrier diodes (SBDs) based on amorphous indium-gallium-zinc-oxide (a-IGZO) with either a top or bottom Schottky contact are fabricated by controlling the oxygen partial pressure during a-IGZO deposition. Although Au electrodes are employed for both Schottky and Ohmic contacts, it is found that Schottky contacts are preferentially formed on a-IGZO film in lower oxygen vacancy concentrations. The effect of negative bias stress on device performance is studied. The Schottky barrier height and series resistance of the a-IGZO SBD are found to increase upon negative bias stress, which is correlated with a reduction of the trap state and background carrier concentration within the a-IGZO film. A physical model based on subgap state transitions from ionized V\\text{O}2+ states to neutralized V O states is proposed to explain the observed electrical instability behavior.

  2. InGaAs/InP heteroepitaxial Schottky barrier diodes for terahertz applications

    NASA Technical Reports Server (NTRS)

    Bhapkar, Udayan V.; Li, Yongjun; Mattauch, Robert J.

    1992-01-01

    This paper explores the feasibility of planar, sub-harmonically pumped, anti-parallel InGaAs/InP heteroepitaxial Schottky diodes for terahertz applications. We present calculations of the (I-V) characteristics of such diodes using a numerical model that considers tunneling. We also present noise and conversion loss predictions of diode mixers operated at 500 GHz, and obtained from a multi-port mixer analysis, using the I-V characteristics predicted by our model. Our calculations indicate that InGaAs/InP heteroepitaxial Schottky barrier diodes are expected to have an I-V characteristic with an ideality factor comparable to that of GaAs Schottky diodes. However, the reverse saturation current of InGaAs/InP diodes is expected to be much greater than that of GaAs diodes. These predictions are confirmed by experiment. The mixer analyses predict that sub-harmonically pumped anti-parallel InGaAs/InP diode mixers are expected to offer a 2 dB greater conversion loss and a somewhat higher single sideband noise temperature than their GaAs counterparts. More importantly, the InGaAs/InP devices are predicted to require only one-tenth of the local oscillator power required by similar GaAs diodes.

  3. Barrier height enhancement of Ni/GaN Schottky diode using Ru based passivation scheme

    SciTech Connect

    Kumar, Ashish Kumar, Mukesh; Singh, R.; Kaur, Riajeet; Joshi, Amish G.; Vinayak, Seema

    2014-03-31

    Wet chemical passivation of n-GaN surface using Ru based solution has been reported. X-ray photoelectron spectroscopy characterization of the GaN surface revealed removal of surface oxides by the introduction of Ru complex species. Ni/n-GaN Schottky barrier diodes were fabricated on passivated GaN and a remarkable improvement in Schottky barrier height from 0.76 eV to 0.92 eV was observed.

  4. Metal silicide/Si thin-film Schottky-diode bolometers

    NASA Astrophysics Data System (ADS)

    Yuryev, Vladimir A.; Chizh, Kirill V.; Chapnin, Valery V.; Kalinushkin, Victor P.

    2015-06-01

    Recently, we have demonstrated Ni silicide/poly-Si diodes as a budget alternative to SOI-diode temperature sensors in uncooled microbolometer FPAs. This paper introduces a solution still more suitable for industry: We have developed PtSi/poly-Si Schottky diodes for microbolometers. Ease of integration of the PtSi/poly-Si diode formation process into the CMOS technology, in analogy with the internal photoemission PtSi/Si IR FPAs, is the merit of the PtSi/poly-Si sensors. Now we demonstrate PtSi/poly-Si diode microbolometers and propose them as a promising solution for focal plane arrays.

  5. On-Chip Power-Combining for High-Power Schottky Diode Based Frequency Multipliers

    NASA Technical Reports Server (NTRS)

    Siles Perez, Jose Vicente (Inventor); Chattopadhyay, Goutam (Inventor); Lee, Choonsup (Inventor); Schlecht, Erich T. (Inventor); Jung-Kubiak, Cecile D. (Inventor); Mehdi, Imran (Inventor)

    2015-01-01

    A novel MMIC on-chip power-combined frequency multiplier device and a method of fabricating the same, comprising two or more multiplying structures integrated on a single chip, wherein each of the integrated multiplying structures are electrically identical and each of the multiplying structures include one input antenna (E-probe) for receiving an input signal in the millimeter-wave, submillimeter-wave or terahertz frequency range inputted on the chip, a stripline based input matching network electrically connecting the input antennas to two or more Schottky diodes in a balanced configuration, two or more Schottky diodes that are used as nonlinear semiconductor devices to generate harmonics out of the input signal and produce the multiplied output signal, stripline based output matching networks for transmitting the output signal from the Schottky diodes to an output antenna, and an output antenna (E-probe) for transmitting the output signal off the chip into the output waveguide transmission line.

  6. New approach to the design of Schottky barrier diodes for THz mixers

    NASA Technical Reports Server (NTRS)

    Jelenski, A.; Grueb, A.; Krozer, V.; Hartnagel, H. L.

    1992-01-01

    Near-ideal GaAs Schottky barrier diodes especially designed for mixing applications in the THz frequency range are presented. A diode fabrication process for submicron diodes with near-ideal electrical and noise characteristics is described. This process is based on the electrolytic pulse etching of GaAs in combination with an in-situ platinum plating for the formation of the Schottky contacts. Schottky barrier diodes with a diameter of 1 micron fabricated by the process have already shown excellent results in a 650 GHz waveguide mixer at room temperature. A conversion loss of 7.5 dB and a mixer noise temperature of less than 2000 K have been obtained at an intermediate frequency of 4 GHz. The optimization of the diode structure and the technology was possible due to the development of a generalized Schottky barrier diode model which is valid also at high current densities. The common diode design and optimization is discussed on the basis of the classical theory. However, the conventional fomulas are valid only in a limited forward bias range corresponding to currents much smaller than the operating currents under submillimeter mixing conditions. The generalized new model takes into account not only the phenomena occurring at the junction such as current dependent recombination and drift/diffusion velocities, but also mobility and electron temperature variations in the undepleted epi-layer. Calculated diode I/V and noise characteristics are in excellent agreement with the measured values. Thus, the model offers the possibility of optimizing the diode structure and predicting the diode performance under mixing conditions at THz frequencies.

  7. Simplified gas sensor model based on AlGaN/GaN heterostructure Schottky diode

    SciTech Connect

    Das, Subhashis Majumdar, S.; Kumar, R.; Bag, A.; Chakraborty, A.; Biswas, D.

    2015-08-28

    Physics based modeling of AlGaN/GaN heterostructure Schottky diode gas sensor has been investigated for high sensitivity and linearity of the device. Here the surface and heterointerface properties are greatly exploited. The dependence of two dimensional electron gas (2DEG) upon the surface charges is mainly utilized. The simulation of Schottky diode has been done in Technology Computer Aided Design (TCAD) tool and I-V curves are generated, from the I-V curves 76% response has been recorded in presence of 500 ppm gas at a biasing voltage of 0.95 Volt.

  8. Electronic transport and Schottky barrier heights of p-type CuAlO2 Schottky diodes

    NASA Astrophysics Data System (ADS)

    Lin, Yow-Jon; Luo, Jie; Hung, Hao-Che

    2013-05-01

    A CuAlO2 Schottky diode was fabricated and investigated using current density-voltage (J-V) and capacitance-voltage (C-V) methods. It is shown that the barrier height (qϕB) determined from J-V measurements is lower than that determined from C-V measurements and qϕB determined from C-V measurements is close to the Schottky limit. This is due to a combined effect of the image-force lowering and tunneling. Time domain measurements provide evidence of the domination of electron trapping with long-second lifetime in CuAlO2. Carrier capture and emission from charge traps may lead to the increased probability of tunneling, increasing the ideality factor.

  9. Study of breakdown voltage of indium-gallium-zinc-oxide-based Schottky diode

    SciTech Connect

    Xin, Qian; Yan, Linlong; Luo, Yi; Song, Aimin

    2015-03-16

    In contrast to the intensive studies on thin-film transistors based on indium gallium zinc oxide (IGZO), the research on IGZO-based diodes is still very limited, particularly on their behavior and stability under high bias voltages. Our experiments reveal a sensitive dependence of the breakdown voltage of IGZO Schottky diodes on the anode metal and the IGZO film thickness. Devices with an Au anode are found to breakdown easily at a reverse bias as low as −2.5 V, while the devices with a Pd anode and a 200-nm, fully depleted IGZO layer have survived up to −15 V. All diodes are fabricated by radio-frequency magnetron sputtering at room temperature without any thermal treatment, yet showing an ideality factor as low as 1.14, showing the possibility of achieving high-performance Schottky diodes on flexible plastic substrate.

  10. Mixing of 10-microm radiation in room-temperature Schottky diodes.

    PubMed

    Tannenwald, P E; Fetterman, H R; Freed, C; Parker, C D; Clifton, B J; O'Donnell, R G

    1981-10-01

    Schottky diodes have been used as room-temperature mixers of CO(2)-laser radiation. When a microwave local oscillator signal was introduced directly into the diode, beat notes between lasers separated by up to 69 GHz were observed. At CO(2) frequencies (30 THz) the photon energy exceeds the measured dc nonlinearities, and the device is expected to approach operation as a photon counter rather than a classical resistive mixer.

  11. Temperature dependent electrical transport behavior of InN/GaN heterostructure based Schottky diodes

    SciTech Connect

    Roul, Basanta; Kumar, Mahesh; Rajpalke, Mohana K.; Bhat, Thirumaleshwara N.; Krupanidhi, S. B.; Sinha, Neeraj; Kalghatgi, A. T.

    2011-02-15

    InN/GaN heterostructure based Schottky diodes were fabricated by plasma-assisted molecular beam epitaxy. The temperature dependent electrical transport properties were carried out for InN/GaN heterostructure. The barrier height and the ideality factor of the Schottky diodes were found to be temperature dependent. The temperature dependence of the barrier height indicates that the Schottky barrier height is inhomogeneous in nature at the heterostructure interface. The higher value of the ideality factor and its temperature dependence suggest that the current transport is primarily dominated by thermionic field emission (TFE) other than thermionic emission (TE). The room temperature barrier height obtained by using TE and TFE models were 1.08 and 1.43 eV, respectively.

  12. Silicon Schottky photovoltaic diodes for solar energy conversion

    NASA Technical Reports Server (NTRS)

    Anderson, W. A.

    1975-01-01

    Various factors in Schottky barrier solar cell fabrication are evaluated in order to improve understanding of the current flow mechanism and to isolate processing variables that improve efficiency. Results of finger design, substrate resistivity, surface finishing and activation energy studies are detailed. An increased fill factor was obtained by baking of the vacuum system to remove moisture.

  13. Junction properties of aluminum/polypyrrole (polypyrrole derivatives) Schottky diodes

    NASA Astrophysics Data System (ADS)

    Singh, Ramadhar; Narula, Amarjeet K.

    1997-11-01

    The current-voltage characteristics of Schottky junctions formed by using aluminum on polypyrrole, poly(N-methyl pyrrole) and the copolymer poly(N-methyl pyrrole-pyrrole) have been investigated. The formation of the junctions has been confirmed by capacitance-voltage characteristics and Chot plots. The results have been explained on the basis of thermionic emission theory.

  14. On-Chip Power-Combining for High-Power Schottky Diode-Based Frequency Multipliers

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam; Mehdi, Imran; Schlecht, Erich T.; Lee, Choonsup; Siles, Jose V.; Maestrini, Alain E.; Thomas, Bertrand; Jung, Cecile D.

    2013-01-01

    A 1.6-THz power-combined Schottky frequency tripler was designed to handle approximately 30 mW input power. The design of Schottky-based triplers at this frequency range is mainly constrained by the shrinkage of the waveguide dimensions with frequency and the minimum diode mesa sizes, which limits the maximum number of diodes that can be placed on the chip to no more than two. Hence, multiple-chip power-combined schemes become necessary to increase the power-handling capabilities of high-frequency multipliers. The design presented here overcomes difficulties by performing the power-combining directly on-chip. Four E-probes are located at a single input waveguide in order to equally pump four multiplying structures (featuring two diodes each). The produced output power is then recombined at the output using the same concept.

  15. Electronic and Interfacial Properties of PD/6H-SiC Schottky Diode Gas Sensors

    NASA Technical Reports Server (NTRS)

    Chen, Liang-Yu; Hunter, Gary W.; Neudeck, Philip G.; Bansal, Gaurav; Petit, Jeremy B.; Knight, Dak; Liu, Chung-Chiun; Wu, Qinghai

    1996-01-01

    Pd/SiC Schottky diodes detect hydrogen and hydrocarbons with high sensitivity. Variation of the diode temperature from 100 C to 200 C shows that the diode sensitivity to propylene is temperature dependent. Long-term heat treating at 425 C up to 140 hours is carried out to determine the effect of extended heat treating on the diode properties and gas sensitivity. The heat treating significantly affects the diode's capacitive characteristics, but the diode's current carrying characteristics are much more stable with a large response to hydrogen. Scanning Electron Microscopy and X-ray Spectrometry studies of the Pd surface after the heating show cluster formation and background regions with grain structure observed in both regions. The Pd and Si concentrations vary between grains. Auger Electron Spectroscopy depth profiles revealed that the heat treating promoted interdiffusion and reaction between the Pd and SiC dw broadened the interface region. This work shows that Pd/SiC Schottky diodes have significant potential as high temperature gas sensors, but stabilization of the structure is necessary to insure their repeatability in long-term, high temperature applications.

  16. Enhanced Thermionic Emission and Low 1/f Noise in Exfoliated Graphene/GaN Schottky Barrier Diode.

    PubMed

    Kumar, Ashutosh; Kashid, Ranjit; Ghosh, Arindam; Kumar, Vikram; Singh, Rajendra

    2016-03-01

    Temperature-dependent electrical transport characteristics of exfoliated graphene/GaN Schottky diodes are investigated and compared with conventional Ni/GaN Schottky diodes. The ideality factor of graphene/GaN and Ni/GaN diodes are measured to be 1.33 and 1.51, respectively, which is suggestive of comparatively higher thermionic emission current in graphene/GaN diode. The barrier height values for graphene/GaN diode obtained using thermionic emission model and Richardson plots are found to be 0.60 and 0.72 eV, respectively, which are higher than predicted barrier height ∼0.40 eV as per the Schottky-Mott model. The higher barrier height is attributed to hole doping of graphene due to graphene-Au interaction which shifts the Fermi level in graphene by ∼0.3 eV. The magnitude of flicker noise of graphene/GaN Schottky diode increases up to 175 K followed by its decrease at higher temperatures. This indicates that diffusion currents and barrier inhomogeneities dominate the electronic transport at lower and higher temperatures, respectively. The exfoliated graphene/GaN diode is found to have lower level of barrier inhomogeneities than conventional Ni/GaN diode, as well as earlier reported graphene/GaN diode fabricated using chemical vapor deposited graphene. The lesser barrier inhomogeneities in graphene/GaN diode results in lower flicker noise by 2 orders of magnitude as compared to Ni/GaN diode. Enhanced thermionic emission current, lower level of inhomogeneities, and reduced flicker noise suggests that graphene-GaN Schottky diodes may have the underlying trend for replacing metal-GaN Schottky diodes.

  17. Highly Conducting Gallium-Doped ZnO Thin Film as Transparent Schottky Contact for Organic- Semiconductor-Based Schottky Diodes

    NASA Astrophysics Data System (ADS)

    Singh, Budhi; Ghosh, Subhasis

    2015-08-01

    Highly conducting and transparent Ga-doped ZnO (GZO) thin films have been grown on transparent substrates at different growth temperatures with Ga content varying from 0.01% to 10%. All films showed pronounced c-axis orientation corresponding to hexagonal wurtzite structure. The minimum resistivity of 4.3 × 10-4 Ω cm was reproducibly obtained in GZO thin film doped with 2% Ga and grown at 600°C. We have further shown that highly conducting transparent GZO thin film can be used as a Schottky contact in copper phthalocyanine (CuPc)-based Schottky diodes. The capacitance-voltage characteristics of the Al/CuPc/Au and GZO/CuPc/Au Schottky diodes show similar built-in potential ( V bi) of 0.98 V, which is close to the difference in work function between Au (5.2 eV) and Al or GZO (4.2 eV), establishing that GZO behaves as a metal electrode with work function similar to Al. Similar values of acceptor concentration (˜1015 cm-3) in CuPc were obtained from the capacitance-voltage characteristics of the Al/CuPc/Au and GZO/CuPc/Au Schottky diodes. These observations indicate the absence of interface states at the metal/organic interface in CuPc-based Schottky diodes.

  18. In Situ Chemical Modification of Schottky Barrier in Solution-Processed Zinc Tin Oxide Diode.

    PubMed

    Son, Youngbae; Li, Jiabo; Peterson, Rebecca L

    2016-09-14

    Here we present a novel in situ chemical modification process to form vertical Schottky diodes using palladium (Pd) rectifying bottom contacts, amorphous zinc tin oxide (Zn-Sn-O) semiconductor made via acetate-based solution process, and molybdenum top ohmic contacts. Using X-ray photoelectron spectroscopy depth profiling, we show that oxygen plasma treatment of Pd creates a PdOx interface layer, which is then reduced back to metallic Pd by in situ reactions during Zn-Sn-O film annealing. The plasma treatment ensures an oxygen-rich environment in the semiconductor near the Schottky barrier, reducing the level of oxygen-deficiency-related defects and improving the rectifying contact. Using this process, we achieve diodes with high forward current density exceeding 10(3)A cm(-2) at 1 V, rectification ratios of >10(2), and ideality factors of around 1.9. The measured diode current-voltage characteristics are compared to numerical simulations of thermionic field emission with sub-bandgap states in the semiconductor, which we attribute to spatial variations in metal stoichiometry of amorphous Zn-Sn-O. To the best of our knowledge, this is the first demonstration of vertical Schottky diodes using solution-processed amorphous metal oxide semiconductor. Furthermore, the in situ chemical modification method developed here can be adapted to tune interface properties in many other oxide devices. PMID:27559750

  19. Electron Density and Capacitance at the interface of Au-ZnO Based Schottky Diode

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Sheng

    ZnO with wide direct band gap (3.37 eV) is a well-known and an interesting compound semiconducting material, which have been used for the fabrication of optical, electrical, and piezoelectric devices such as light emitting diodes, solar cells. Schottky diodes are associated with quicker switching and lower turn on voltages compared to p-n junction diodes. J-V characteristics exhibit nonlinear rectifying behavior with threshold voltage of 2.1 V. The barrier heights were found to be 0.61 eV. The measured capacitance for the Schottky junction depends on the reverse bias potential and frequency. At the lower frequencies the capacitance has the higher values due to the trapping occurred at the interface through the surface roughness and lattice mismatch. We perform model potential calculation with quantum well around the interface. Model potentials allow some degree of freedom in the design of the emitted wavelength through adjustment of the energy levels. We apply the various well width w and barrier height V in order to match the device information made by Willander. Solving the Schrödinger equation with exchange- correlation energy and effective mass of electrons will produce values of the energy levels and states. The variational barrier heights result in the change of the electron density This accounts for the excessive capacitance at the interface of Schottky diode.

  20. Schottky diode based on WS2 crossed with PEDOT/PSSA

    NASA Astrophysics Data System (ADS)

    Ortiz, Deliris; Pinto, Nicholas; Naylor, Carl; Johnson, A. T. Charlie

    An easy technique to fabricate a Schottky diode with WS2 and PEDOT-PSSA under ambient conditions is presented. WS2 is an air stable transition metal dichalcogenide semiconductor. When connected as a field effect transistor, WS2 exhibited n-type behavior with a charge mobility of ~7cm2/V-s on SiO2. PEDOT/PSSA is a conducting polymer that can be electro-spun to form fibers with a conductivity of ~1 S/cm. In this work we fabricated a Schottky diode by crossing a CVD grown monolayer WS2 crystal with a single electro-spun PEDOT/PSSA fiber. The resulting diode characteristics were analyzed assuming the standard thermionic emission model of a Schottky junction. Analysis of the results includes the ideality parameter of 4.75, diode rectification ratio ~10, and a turn on voltage of 1.4V. Efforts to investigate if these parameters are tunable with a back gate will also be presented. This work was supported by NSF-DMR-1523463 and NSF DMR RUI-1360772. ATJ acknowledges support from EFRI 2DARE EFMA-1542879.

  1. Investigation of Thickness Dependence of Metal Layer in Al/Mo/4H-SiC Schottky Barrier Diodes.

    PubMed

    Lee, Seula; Lee, Jinseon; Kang, Tai-Young; Kyoung, Sinsu; Jung, Eun Sik; Kim, Kyung Hwan

    2015-11-01

    In this paper, we present the preparation and characterization of Schottky barrier diodes based on silicon carbide with various Schottky metal layer thickness values. In this structure, molybdenum and aluminum were employed as the Schottky barrier metal and top electrode, respectively. Schottky metal layers were deposited with thicknesses ranging from 1000 to 3000 Å, and top electrodes were deposited with thickness as much as 3000 Å. The deposition of both metal layers was performed using the facing target sputtering (FTS) method, and the fabricated samples were annealed with the tubular furnace at 300 degrees C under argon ambient for 10 min. The Schottky barrier height, series resistance, and ideality factor was calculated from the forward I-V characteristic curve using the methods proposed by Cheung and Cheung, and by Norde. For as-deposited Schottky diodes, we observed an increase of the threshold voltage (V(T)) as the thickness of the Schottky metal layer increased. After the annealing, the Schottky barrier heights (SBHs) of the diodes, including Schottky metal layers of over 2000 Å, increased. In the case of the Schottky metal layer deposited to 1000 Å, the barrier heights decreased due to the annealing process. This may have been caused by the interfacial penetration phenomenon through the Schottky metal layer. For variations of V(T), the SBH changed with a similar tendency. The ideality factor and series resistance showed no significant changes before or after annealing. This indicates that this annealing condition is appropriate for Mo SiC structures. Our results confirm that it is possible to control V(T) by adjusting the thickness of the Schottky metal layer.

  2. Investigation of Thickness Dependence of Metal Layer in Al/Mo/4H-SiC Schottky Barrier Diodes.

    PubMed

    Lee, Seula; Lee, Jinseon; Kang, Tai-Young; Kyoung, Sinsu; Jung, Eun Sik; Kim, Kyung Hwan

    2015-11-01

    In this paper, we present the preparation and characterization of Schottky barrier diodes based on silicon carbide with various Schottky metal layer thickness values. In this structure, molybdenum and aluminum were employed as the Schottky barrier metal and top electrode, respectively. Schottky metal layers were deposited with thicknesses ranging from 1000 to 3000 Å, and top electrodes were deposited with thickness as much as 3000 Å. The deposition of both metal layers was performed using the facing target sputtering (FTS) method, and the fabricated samples were annealed with the tubular furnace at 300 degrees C under argon ambient for 10 min. The Schottky barrier height, series resistance, and ideality factor was calculated from the forward I-V characteristic curve using the methods proposed by Cheung and Cheung, and by Norde. For as-deposited Schottky diodes, we observed an increase of the threshold voltage (V(T)) as the thickness of the Schottky metal layer increased. After the annealing, the Schottky barrier heights (SBHs) of the diodes, including Schottky metal layers of over 2000 Å, increased. In the case of the Schottky metal layer deposited to 1000 Å, the barrier heights decreased due to the annealing process. This may have been caused by the interfacial penetration phenomenon through the Schottky metal layer. For variations of V(T), the SBH changed with a similar tendency. The ideality factor and series resistance showed no significant changes before or after annealing. This indicates that this annealing condition is appropriate for Mo SiC structures. Our results confirm that it is possible to control V(T) by adjusting the thickness of the Schottky metal layer. PMID:26726688

  3. Research on the electrical characteristics of the Pt/CdS Schottky diode

    NASA Astrophysics Data System (ADS)

    Ding, Jia-xin; Zhang, Xiang-feng; Yao, Guansheng

    2013-08-01

    With the development of technology, the demand for semiconductor ultraviolet detector is increasing day by day. Compared with the traditional infrared detector in missile guidance, ultraviolet/infrared dual-color detection can significantly improve the anti-interference ability of the missile. According to the need of missile guidance and other areas of the application of ultraviolet detector, the paper introduces a manufacture of the CdS Schottky barrier ultraviolet detector. By using the radio frequency magnetron sputtering technology, a Pt thin film layer is sputtered on CdS basement to form a Schottky contact firstly. Then the indium ohmic contact electrode is fabricated by thermal evaporation method, and eventually a Pt/CdS/In Schottky diode is formed. The I-V characteristic of the device was tested at room temperature, its zero bias current and open circuit voltage is -0.578nA and 130mV, respectively. Test results show that the the Schottky contact has been formed between Pt and CdS. The device has good rectifying characteristics. According to the thermionic emission theory, the I-V curve fitting analysis of the device was studied under the condition of small voltage. The ideality factor and Schottky barrier height is 1.89 and 0.61eV, respectively. The normalized spectral responsivity at zero bias has been tested. The device has peak responsivity at 500nm, and it cutoff at 510nm.

  4. Charge transport mechanisms in Schottky diodes based on low-resistance CdTe:Mn

    SciTech Connect

    Kosyachenko, L. A. Yurtsenyuk, N. S.; Rarenko, I. M.; Sklyarchuk, V. M.; Sklyarchuk, O. F.; Zakharuk, Z. I.; Grushko, E. V.

    2013-07-15

    CdTe:Mn crystals with a resistivity of {approx}1 {Omega} cm at 300 K and Schottky diodes based on them are investigated. The electrical conductivity of the material and its temperature variations are explained in terms of the statistics of electrons and holes in semiconductors with allowance for the compensation processes. The ionization energy and the degree of compensation of the donors responsible for the conductivity are determined. It is shown that, in the case of forward connection and low reverse biases, the currents in Au/CdTe:Mn Schottky diode are determined by generation-recombination processes in the space-charge region. At higher reverse biases (above 1.5-2 V) the excess current is caused by electron tunneling from the metal to the semiconductor, and at even higher voltages (>6-7 V) an additional increase in the reverse current due to avalanche processes is observed.

  5. Characterization of electrical explosion of Schottky diode for one-shot switch applications

    NASA Astrophysics Data System (ADS)

    Hu, Bo; Jiao, Jianshe; Zhu, Peng; Wu, Lizhi; Ye, Yinghua; Shen, Ruiqi

    2014-12-01

    The electrical explosion characteristics of Schottky diode for one-shot switch applications were acquired by analysis of photographs of high speed camera and current-voltage histories. Four types of connections among Schottky diode, top electrode and discharge capacitor were studied. Results show that type B has the longest time (1.4 ms) of optical radiation and highest energy consumption, which makes it easier to turn on the switch. The charge flux of plasma was determined to be 24.5 Q/(s m2) by parallel electrode plates method. Atomic emission spectroscopic measurements were devoted to determine plasma temperature and density during electrical explosion. Results show that temperature is between 4000 K and 5000 K, and density is about 1024 m-3. The one-shot switch based on ceramics has been fabricated and characterized and the results show that the peak current and the rise time are about 963.77 A and 381.6 ns, respectively.

  6. An integrated membrane sub-harmonic Schottky diode mixers at 340GHz

    NASA Astrophysics Data System (ADS)

    Wang, Junlong; Yang, Dabao; Xing, Dong; Liang, Shixiong; Zhang, Lisen; Zhao, Xiangyang; Feng, Zhihong

    2015-11-01

    This paper presents a sub-harmonic mixer operating over the spectral band 332-348 GHz. The mixers employ integrated GaAs membrane Schottky diode technology. The simulated results show that the conversion loss of the mixer is below dB in the band from 333 GHz to 347 GHz with a local oscillator power requirement of 5mW.The minimum is 8.2dB at 344GHz.

  7. Observation of negative differential capacitance (NDC) in Ti Schottky diodes on SiGe islands

    SciTech Connect

    Rangel-Kuoppa, Victor-Tapio; Jantsch, Wolfgang; Tonkikh, Alexander; Zakharov, Nikolay; Werner, Peter

    2013-12-04

    The Negative Differential Capacitance (NDC) effect on Ti Schottky diodes formed on n-type Silicon samples with embedded Germanium Quantum Dots (QDs) is observed and reported. The NDC-effect is detected using capacitance-voltage (CV) method at temperatures below 200 K. It is explained by the capture of electrons in Germanium QDs. Our measurements reveal that each Ge QD captures in average eight electrons.

  8. Fabrication and optimization of a whiskerless Schottky barrier diode for submillimeter wave applications

    NASA Technical Reports Server (NTRS)

    Bishop, W.; Mattauch, R. J.

    1990-01-01

    The following accomplishments were made towards the goal of an optimized whiskerless diode chip for submillimeter wavelength applications. (1) Surface channel whiskerless diode structure was developed which offers excellent DC and RF characteristics, reduced shunt capacitance and simplified fabrication compared to mesa and proton isolated structures. (2) Reliable fabrication technology was developed for the surface channel structure. The new anode plating technology is a major improvement. (3) DC and RF characterization of the surface channel diode was compared with whisker contacted diodes. This data indicates electrical performance as good as the best reported for similar whisker contacted devices. (4) Additional batches of surface channel diodes were fabricated with excellent I-V and reduced shunt capacitance. (5) Large scale capacitance modelinng was done for the planar diode structure. This work revealed the importance of removing the substrate gallium arsenide for absolute minimum pad capacitance. (6) A surface channel diode was developed on quartz substrate and this substrate was completely removed after diode mounting for minimum parasitic capacitance. This work continues with the goal of producing excellent quality submillimeter wavelength planar diodes which satisfy the requirements of easy handling and robustness. These devices will allow the routine implementation of Schottky receivers into space-based applications at frequencies as high as 1 THz, and, in the future, beyond.

  9. 670 GHz Schottky Diode Based Subharmonic Mixer with CPW Circuits and 70 GHz IF

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam (Inventor); Schlecht, Erich T. (Inventor); Lee, Choonsup (Inventor); Lin, Robert H. (Inventor); Gill, John J. (Inventor); Sin, Seth (Inventor); Mehdi, Imran (Inventor)

    2014-01-01

    A coplanar waveguide (CPW) based subharmonic mixer working at 670 GHz using GaAs Schottky diodes. One example of the mixer has a LO input, an RF input and an IF output. Another possible mixer has a LO input, and IF input and an RF output. Each input or output is connected to a coplanar waveguide with a matching network. A pair of antiparallel diodes provides a signal at twice the LO frequency, which is then mixed with a second signal to provide signals having sum and difference frequencies. The output signal of interest is received after passing through a bandpass filter tuned to the frequency range of interest.

  10. Optical properties of ITO/ZnO Schottky diode with enhanced UV Photoresponse

    NASA Astrophysics Data System (ADS)

    Lee, Hsin-Yen; Chern, Ming-Yau

    2015-11-01

    Photoluminescence (PL) spectra of zinc oxide (ZnO) samples with different hydrogen peroxide (H2O2) treatment durations were measured to examine several point defects on the surfaces of the films. The results suggest successful oxidation through the reaction between oxygen radicals dissociated from H2O2 and the ZnO surface. To further confirm the defect-induced gain mechanism, we fabricated highly transparent indium-tin-oxide (ITO)/ZnO Schottky diodes and measured the key diode characteristics. Photocurrents were measured at different wavelengths, and possible explanations for the high optical gain within the ultraviolet (UV) region are provided.

  11. X-ray detectors based on GaN Schottky diodes

    SciTech Connect

    Duboz, Jean-Yves; Frayssinet, Eric; Chenot, Sebastien; Reverchon, Jean-Luc; Idir, Mourad

    2010-10-18

    GaN Schottky diodes have been fabricated and tested as x-ray detectors in the range from 6 to 21 keV. The spectral response has been measured and is compared to its theoretical value. The study of the response and its temporal dynamics as a function of the bias allows to identify a photovoltaic behavior at low bias and a photoconductive one at larger reverse biases. The GaN diode turned out to be linear as a function of the incident power. The noise and detectivity are given and discussed.

  12. Design Considerations for Heavily-Doped Cryogenic Schottky Diode Varactor Multipliers

    NASA Technical Reports Server (NTRS)

    Schlecht, E.; Maiwald, F.; Chattopadhyay, G.; Martin, S.; Mehdi, I.

    2001-01-01

    Diode modeling for Schottky varactor frequency multipliers above 500 GHz is presented with special emphasis placed on simple models and fitted equations for rapid circuit design. Temperature- and doping-dependent mobility, resistivity, and avalanche current multiplication and breakdown are presented. Next is a discussion of static junction current, including the effects of tunneling as well as thermionic emission. These results have been compared to detailed measurements made down to 80 K on diodes fabricated at JPL, followed by a discussion of the effect on multiplier efficiency. Finally, a simple model of current saturation in the undepleted active layer suitable for inclusion in harmonic balance simulators is derived.

  13. Comparison between MIM and Schottky diodes as harmonic mixers for visible lasers and microwave sources

    NASA Astrophysics Data System (ADS)

    Acef, O.; Hilico, L.; Bahoura, M.; Nez, F.; De Natale, P.

    1994-07-01

    We report our results on high order harmonic mixing between two visible lasers and microwave radiations in point-contact diodes. We have observed up to the 17th harmonic mixing order between two lasers ( Δv = 150 GHz) and a X-band klystron in a Schottky diode. We have been able to monitor very large laser frequency differences, up to 540 GHz (≈ 1.3 nm) with a good signal to noise ratio while using a very low power microwave source (20 mW/90 GHz). These results can be improved by using stabilized lasers and phase-locked microwave sources.

  14. 670-GHz Schottky Diode-Based Subharmonic Mixer with CPW Circuits and 70-GHz IF

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam; Schlecht, Erich T.; Lee, Choonsup; Lin, Robert H.; Gill, John J.; Mehdi, Imran; Sin, Seth; Deal, William; Loi, Kwok K.; Nam, Peta; Rodriguez, Bryan

    2012-01-01

    GaAs-based, sub-harmonically pumped Schottky diode mixers offer a number of advantages for array implementation in a heterodyne receiver system. Since the radio frequency (RF) and local oscillator (LO) signals are far apart, system design becomes much simpler. A proprietary planar GaAs Schottky diode process was developed that results in very low parasitic anodes that have cutoff frequencies in the tens of terahertz. This technology enables robust implementation of monolithic mixer and frequency multiplier circuits well into the terahertz frequency range. Using optical and e-beam lithography, and conventional epitaxial layer design with innovative usage of GaAs membranes and metal beam leads, high-performance terahertz circuits can be designed with high fidelity. All of these mixers use metal waveguide structures for housing. Metal machined structures for RF and LO coupling hamper these mixers to be integrated in multi-pixel heterodyne array receivers for spectroscopic and imaging applications. Moreover, the recent developments of terahertz transistors on InP substrate provide an opportunity, for the first time, to have integrated amplifiers followed by Schottky diode mixers in a heterodyne receiver at these frequencies. Since the amplifiers are developed on a planar architecture to facilitate multi-pixel array implementation, it is quite important to find alternative architecture to waveguide-based mixers.

  15. Fabrication and electrical characterization of nickel/p-Si Schottky diode at low temperature

    NASA Astrophysics Data System (ADS)

    Kumar, Rajender; Chand, Subhash

    2016-08-01

    In this study the current-voltage and capacitance-voltage characteristics of metal semiconductor Ni/p-Si(100) based Schottky diode on p- type silicon measured over a wide temperature range (60-300 K) have been studied on the basis of thermionic emission diffusion mechanism and the assumption of a Gaussian distribution of barrier heights. The parameters ideality factor, barrier height and series resistance are determined from the forward bias current-voltage characteristics. The barrier height for Ni/p-Si(100) Schottky diode found to vary between 0.513 eV and 0.205 eV, and the ideality factor between 2.34 and 8.88 on decreasing temperature 300-60 K. A plot involving the use of ϕb versus 1/T data is used to gather evidence for the occurrence of a Gaussian distribution of barrier height and obtain the value of standard deviation. The observed temperature dependences of barrier height and ideality factor and non-linear activation energy plot are attributed to the Gaussian distribution of barrier heights at the metal-semiconductor contact. The barrier height of Ni/p-Si(100) Schottky diode was also measured over wide temperature from the capacitance-voltage study.

  16. X-ray detection with zinc-blende (cubic) GaN Schottky diodes

    PubMed Central

    Gohil, T.; Whale, J.; Lioliou, G.; Novikov, S. V.; Foxon, C. T.; Kent, A. J.; Barnett, A. M.

    2016-01-01

    The room temperature X-ray responses as functions of time of two n type cubic GaN Schottky diodes (200 μm and 400 μm diameters) are reported. The current densities as functions of time for both diodes showed fast turn-on transients and increases in current density when illuminated with X-ray photons of energy up to 35 keV. The diodes were also electrically characterized: capacitance, implied depletion width and dark current measurements as functions of applied bias at room temperature are presented. At −5 V reverse bias, the capacitances of the diodes were measured to be (84.05 ± 0.01) pF and (121.67 ± 0.02) pF, respectively. At −5 V reverse bias, the dark current densities of the diodes were measured to be (347.2 ± 0.4) mA cm−2 and (189.0 ± 0.2) mA cm−2, respectively. The Schottky barrier heights of the devices (0.52 ± 0.07) eV and (0.63 ± 0.09) eV, respectively, were extracted from the forward dark current characteristics. PMID:27403806

  17. X-ray detection with zinc-blende (cubic) GaN Schottky diodes.

    PubMed

    Gohil, T; Whale, J; Lioliou, G; Novikov, S V; Foxon, C T; Kent, A J; Barnett, A M

    2016-01-01

    The room temperature X-ray responses as functions of time of two n type cubic GaN Schottky diodes (200 μm and 400 μm diameters) are reported. The current densities as functions of time for both diodes showed fast turn-on transients and increases in current density when illuminated with X-ray photons of energy up to 35 keV. The diodes were also electrically characterized: capacitance, implied depletion width and dark current measurements as functions of applied bias at room temperature are presented. At -5 V reverse bias, the capacitances of the diodes were measured to be (84.05 ± 0.01) pF and (121.67 ± 0.02) pF, respectively. At -5 V reverse bias, the dark current densities of the diodes were measured to be (347.2 ± 0.4) mA cm(-2) and (189.0 ± 0.2) mA cm(-2), respectively. The Schottky barrier heights of the devices (0.52 ± 0.07) eV and (0.63 ± 0.09) eV, respectively, were extracted from the forward dark current characteristics.

  18. X-ray detection with zinc-blende (cubic) GaN Schottky diodes.

    PubMed

    Gohil, T; Whale, J; Lioliou, G; Novikov, S V; Foxon, C T; Kent, A J; Barnett, A M

    2016-01-01

    The room temperature X-ray responses as functions of time of two n type cubic GaN Schottky diodes (200 μm and 400 μm diameters) are reported. The current densities as functions of time for both diodes showed fast turn-on transients and increases in current density when illuminated with X-ray photons of energy up to 35 keV. The diodes were also electrically characterized: capacitance, implied depletion width and dark current measurements as functions of applied bias at room temperature are presented. At -5 V reverse bias, the capacitances of the diodes were measured to be (84.05 ± 0.01) pF and (121.67 ± 0.02) pF, respectively. At -5 V reverse bias, the dark current densities of the diodes were measured to be (347.2 ± 0.4) mA cm(-2) and (189.0 ± 0.2) mA cm(-2), respectively. The Schottky barrier heights of the devices (0.52 ± 0.07) eV and (0.63 ± 0.09) eV, respectively, were extracted from the forward dark current characteristics. PMID:27403806

  19. Electronic Properties of DNA-Based Schottky Barrier Diodes in Response to Alpha Particles.

    PubMed

    Al-Ta'ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2015-01-01

    Detection of nuclear radiation such as alpha particles has become an important field of research in recent history due to nuclear threats and accidents. In this context; deoxyribonucleic acid (DNA) acting as an organic semiconducting material could be utilized in a metal/semiconductor Schottky junction for detecting alpha particles. In this work we demonstrate for the first time the effect of alpha irradiation on an Al/DNA/p-Si/Al Schottky diode by investigating its current-voltage characteristics. The diodes were exposed for different periods (0-20 min) of irradiation. Various diode parameters such as ideality factor, barrier height, series resistance, Richardson constant and saturation current were then determined using conventional, Cheung and Cheung's and Norde methods. Generally, ideality factor or n values were observed to be greater than unity, which indicates the influence of some other current transport mechanism besides thermionic processes. Results indicated ideality factor variation between 9.97 and 9.57 for irradiation times between the ranges 0 to 20 min. Increase in the series resistance with increase in irradiation time was also observed when calculated using conventional and Cheung and Cheung's methods. These responses demonstrate that changes in the electrical characteristics of the metal-semiconductor-metal diode could be further utilized as sensing elements to detect alpha particles. PMID:26007733

  20. Electronic Properties of DNA-Based Schottky Barrier Diodes in Response to Alpha Particles

    PubMed Central

    Al-Ta’ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2015-01-01

    Detection of nuclear radiation such as alpha particles has become an important field of research in recent history due to nuclear threats and accidents. In this context; deoxyribonucleic acid (DNA) acting as an organic semiconducting material could be utilized in a metal/semiconductor Schottky junction for detecting alpha particles. In this work we demonstrate for the first time the effect of alpha irradiation on an Al/DNA/p-Si/Al Schottky diode by investigating its current-voltage characteristics. The diodes were exposed for different periods (0–20 min) of irradiation. Various diode parameters such as ideality factor, barrier height, series resistance, Richardson constant and saturation current were then determined using conventional, Cheung and Cheung’s and Norde methods. Generally, ideality factor or n values were observed to be greater than unity, which indicates the influence of some other current transport mechanism besides thermionic processes. Results indicated ideality factor variation between 9.97 and 9.57 for irradiation times between the ranges 0 to 20 min. Increase in the series resistance with increase in irradiation time was also observed when calculated using conventional and Cheung and Cheung’s methods. These responses demonstrate that changes in the electrical characteristics of the metal-semiconductor-metal diode could be further utilized as sensing elements to detect alpha particles. PMID:26007733

  1. Studies on the Thermal Stability of Ni/n–GaN and Pt/n–GaN Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Kumar, Ashish; Mahajan, Somna; Vinayak, Seema; Singh, R.

    2016-08-01

    High temperature annealing of Ni and Pt Schottky diodes on n-GaN has been investigated. Ni/n–GaN and Pt/n–GaN Schottky diodes were fabricated using ultra high vacuum and annealed at various temperatures (200 °C‑700 °C) using rapid thermal anneal system. It was observed that in case of Ni/GaN diodes, the Schottky barrier height increases for 200 °C and then decreases with increase in annealing temperature. For Pt/GaN diodes, the barrier height found to decrease with increase in annealing temperature. The observed variation of barrier height and ideality factor is discussed on the basis of interfacial chemical reactions between metal and semiconductor.

  2. Planar Schottky varactor diode and corresponding large signal model for millimeter-wave applications

    NASA Astrophysics Data System (ADS)

    Jie, Huang; Qian, Zhao; Hao, Yang; Junrong, Dong; Haiying, Zhang

    2014-05-01

    A GaAs-based planar Schottky varactor diode (PSVD) is successfully developed to meet the demand of millimeter-wave harmonic generation. Based on the measured S-parameter, I-V and C-V characteristics, an accurate and reliable extraction method of the millimeter-wave large signal equivalent circuit model of the PSVD is proposed and used to extract the model parameters of two PSVDs with Schottky contact areas of 160 μm2 and 49 μm2, respectively. The simulated S-parameter, I-V and C-V performances of the proposed physics-based model are in good agreement with the measured one over the frequency range from 0.1 to 40 GHz for wide operation bias range from -10 to 0.6 V for these two PSVDs. The proposed equivalent large signal circuit model of this PSVD has been proven to be reliable and can potentially be used to design microwave circuits., planar Schottky varactor diode

  3. Low-frequency noise properties in Pt-indium gallium zinc oxide Schottky diodes

    SciTech Connect

    Zhang, Jiawei; Zhang, Linqing; Ma, Xiaochen; Wilson, Joshua; Jin, Jidong; Du, Lulu; Xin, Qian; Song, Aimin

    2015-08-31

    The low-frequency noise properties of Pt-indium gallium zinc oxide (IGZO) Schottky diodes at different forward biases are investigated. The IGZO layer and Pt contact were deposited by RF sputtering at room temperature. The diode showed an ideality factor of 1.2 and a barrier height of 0.94 eV. The current noise spectral density exhibited 1/f behavior at low frequencies. The analysis of the current dependency of the noise spectral density revealed that for the as-deposited diode, the noise followed Luo's mobility and diffusivity fluctuation model in the thermionic-emission-limited region and Hooge's empirical theory in the series-resistance-limited region. A low Hooge's constant of 1.4 × 10{sup −9} was found in the space-charge region. In the series-resistance-limited region, the Hooge's constant was 2.2 × 10{sup −5}. After annealing, the diode showed degradation in the electrical performance. The interface-trap-induced noise dominated the noise spectrum. By using the random walk model, the interface-trap density was obtained to be 3.6 × 10{sup 15 }eV{sup −1 }cm{sup −2}. This work provides a quantitative approach to analyze the properties of Pt-IGZO interfacial layers. These low noise properties are a prerequisite to the use of IGZO Schottky diodes in switch elements in memory devices, photosensors, and mixer diodes.

  4. Effect of neutron irradiation on charge collection efficiency in 4H-SiC Schottky diode

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Jiang, Yong; Lei, Jiarong; Fan, Xiaoqiang; Chen, Yu; Li, Meng; Zou, Dehui; Liu, Bo

    2014-01-01

    The charge collection efficiency (CCE) in 4H-SiC Schottky diode is studied as a function of neutron fluence. The 4H-SiC diode was irradiated with fast neutrons of a critical assembly in Nuclear Physics and Chemistry Institute and CCE for 3.5 MeV alpha particles was then measured as a function of the applied reverse bias. It was found from our experiment that an increase of neutron fluence led to a decrease of CCE. In particular, CCE of the diode was less than 1.3% at zero bias after an irradiation at 8.26×1014 n/cm2. A generalized Hecht's equation was employed to analyze CCE in neutron irradiated 4H-SiC diode. The calculations nicely fit the CCE of 4H-SiC diode irradiated at different neutron fluences. According to the calculated results, the extracted electron μτ product (μτ)e and hole μτ product (μτ)h of the irradiated 4H-SiC diode are found to decrease by increasing the neutron fluence.

  5. Interface states of Ag/(110)GaAs Schottky diodes without and with interfacial layers

    SciTech Connect

    Platen, W.; Schmutzler, H.; Kohl, D.; Brauchle, K.; Wolter, K.

    1988-07-01

    GaAs(110) faces with different preparations: ultrahigh vacuum (UHV) cleaved, polished and etched, polished and sputtered: are prepared as Schottky diodes by the deposition of Ag. Diodes based on UHV-cleaved faces do show homogeneously distributed EL2 and EL5 states in deep level transient spectroscopy (DLTS). On polished and etched samples an additional interface state (IS) distribution with a density of 9 x 10/sup 11/ eV/sup -1/ cm/sup -2/ at the DLTS maximum appears. These states can be caused by defects at the oxidic interfacial layer. Polishing and sputtering also evokes the IS distribution. The absence of a DLTS signal from metal-induced gap states (MIGS) which pin the Fermi level at 0.49 eV above the valence-band maximum is related to the absence of an interfacial layer in the UHV prepared Schottky diodes. The sputter process increases the electron density in a thin layer below the interface by an As excess. The corresponding smaller extent of the barrier causes an additional electron emission via tunneling processes from the IS distribution. Furthermore, a near-interface state, EL6 (V/sub Ga/-V/sub As/), shows up. Its concentration at the interface attains N/sub EL6/ = 2.5 x 10/sup 16/ cm/sup -3/ comparable to the shallow donor concentration.

  6. Interface states of Ag/(110)GaAs Schottky diodes without and with interfacial layers

    NASA Astrophysics Data System (ADS)

    Platen, W.; Schmutzler, H.-J.; Kohl, D.; Brauchle, K.-A.; Wolter, K.

    1988-07-01

    GaAs(110) faces with different preparations—ultrahigh vacuum (UHV) cleaved, polished and etched, polished and sputtered—are prepared as Schottky diodes by the deposition of Ag. Diodes based on UHV-cleaved faces do show homogeneously distributed EL2 and EL5 states in deep level transient spectroscopy (DLTS). On polished and etched samples an additional interface state (IS) distribution with a density of 9×1011 eV-1 cm-2 at the DLTS maximum appears. These states can be caused by defects at the oxidic interfacial layer. Polishing and sputtering also evokes the IS distribution. The absence of a DLTS signal from metal-induced gap states (MIGS) which pin the Fermi level at 0.49 eV above the valence-band maximum is related to the absence of an interfacial layer in the UHV prepared Schottky diodes. The sputter process increases the electron density in a thin layer below the interface by an As excess. The corresponding smaller extent of the barrier causes an additional electron emission via tunneling processes from the IS distribution. Furthermore, a near-interface state, EL6 (VGa-VAs), shows up. Its concentration at the interface attains NEL6 =2.5×1016 cm-3 comparable to the shallow donor concentration.

  7. Experimental determination of the laterally homogeneous barrier height of Au/ n-Si Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Sağlam, M.; Cimilli, F. E.; Türüt, A.

    2004-05-01

    We have computed the homogeneous barrier height (BH) of Au/ n-Si Schottky diodes (SDs). Thereby, Au/ n-Si/Au-Sb SDs (24 dots) have identically been prepared, and the effective BHs and ideality factors of these diodes have been calculated from their experimental forward bias current-voltage ( I- V) and reverse bias capacitance-voltage ( C- V) characteristics. The BH for the Au/ n-Si/Au-Sb diodes from the I- V characteristics varied from 0.789 to 0.819 eV, the ideality factor n varied from 1.051 to 1.179, and the BH from C-2- V characteristics varied from 0.801 to 0.851 eV. The Gaussian fits of he experimental Schottky BH distributions obtained from the C-2- V and I- V characteristics have yielded a mean BH values of 0.808 and 0.809 eV, respectively, that are in close agreement with value of about 0.805 eV predicted by metal-induced gap states (MIGS) and chemical electronegativity concepts for Au/ n-Si SDs. Furthermore, the lateral homogeneous BH value of approximately 0.834 eV were also computed from the extrapolation of the linear plot of experimental BHs versus ideality factors.

  8. New type of Schottky diode-based Cu-Al-Mn-Cr shape memory material films

    NASA Astrophysics Data System (ADS)

    Aksu Canbay, C.; Dere, A.; Mensah-Darkwa, Kwadwo; Al-Ghamdi, Ahmed; Karagoz Genç, Z.; Gupta, R. K.; Yakuphanoglu, F.

    2016-07-01

    Cr-doped CuAlMn shape memory alloys were produced by arc melting method. The effects of Cr content on microstructure and transformation parameters of were investigated. The alloys were characterized by X-ray analysis, optical microscope observations and differential scanning calorimetry measurements. The grain size of the alloys was decreased by the addition of Cr into CuAlMn alloy system. The martensite transformation temperature was shifted both the lower temperature and higher temperature with the addition of chromium. This change was explained on the basis of the change in the thermodynamics such as enthalpy, entropy and activation energy values. The obtained results indicate that the phase transformation temperatures of the CuAlMn alloy system can be controlled by addition of Cr. We fabricated a Schottky barrier diode and observed that ideality factor and barrier height increase with increasing temperature. The diodes exhibited a thermal sensor behavior. This indicates that Schottky diode-based Cu-Al-Mn-Cr shape memory material films can be used as a sensor in high-temperature measurement applications.

  9. Simulations about self-absorption of tritium in titanium tritide and the energy deposition in a silicon Schottky barrier diode.

    PubMed

    Li, Hao; Liu, Yebing; Hu, Rui; Yang, Yuqing; Wang, Guanquan; Zhong, Zhengkun; Luo, Shunzhong

    2012-11-01

    Simulations on the self-absorption of tritium electrons in titanium tritide films and the energy deposition in a silicon Schottky barrier diode are carried out using the Geant4 radiation transport toolkit. Energy consumed in each part of the Schottky radiovoltaic battery is simulated to give a clue about how to make the battery work better. The power and energy-conversion efficiency of the tritium silicon Schottky radiovoltaic battery in an optimized design are simulated. Good consistency with experiments is obtained. PMID:22935439

  10. THz frequency multiplier chains base on planar Schottky diodes

    NASA Technical Reports Server (NTRS)

    Maiwald, F.; Schlecht, E.; Maestrini, A.; Chattopadhyay, G.; Pearson, J.; Pukala, D.; Mehdi, I.

    2002-01-01

    The Herschel Space Observatory (HSO), an ESA cornerstone mission with NASA contribution, will enable a comprehensive study of the galactic as well as the extra galactic universe. At the heart of this exploration are ultra sensitive coherent detectors that can allow for high-resolution spectroscopy. Successful operation of these receivers is predicated on providing a sufficiently powerful local oscillator (LO) source. Historically, a versatile space qualified LO source for frequencies beyond 500 GHz has been difficult if not impossible. This paper will focus on the effort under way to develop, build, characterize and qualify a LO chain to 1200 GHz (Band 5 on HSO) that is based on planar GaAs diodes mounted in waveguide circuits. State-of-the-art performance has been obtained from a three-stage ( x2 x 2 x 3 ) multiplier chain that can provide a peak output power of 120 uW (1178 GHz) at room temperature and a peak output power of 190 uW at 1183 GHz when cooled to 113 K. Implementation of this LO source for the Heterodyne Instrument for Far Infrared (HIFI) on HSO will be discussed in detail.

  11. Temperature-dependent electrical transport properties of (Au/Ni)/n-GaN Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Dogan, Hulya; Elagoz, Sezai

    2014-09-01

    The temperature-dependent electrical properties of (Au/Ni)/n-GaN Schottky barrier diodes (SBDs)have been investigated in the wide temperature range of 40-400 K. The analysis of the main electrical characteristics such as zero-bias barrier height (ΦB0), ideality factor (n) and series resistance (Rs) were found strongly temperature dependent. Such behavior is attributed to barrier inhomogeneities by assuming a Gaussian distribution (GD) of barrier heights (BHs) at the interface. It is evident that the diode parameters such as zero-bias barrier height increases and the ideality factor decreases with increasing temperature. The values of series resistance that are obtained from Cheung's method are decreasing with increasing temperature. The temperature dependence of Schottky barrier height (SBD) and ideality factor (n) are explained by invoking three sets of Gaussian distribution of (SBH) in the temperature ranges of 280-400 K, 120-260 K and 40-100 K, respectively. (Au/Ni)/n-GaN Schottky barrier diode have been shown a Gaussian distribution giving mean BHs (ΦbarB0) of 1.167, 0.652 and 0.356 eV and standard deviation σs of 0.178, 0.087 and 0.133 V for the three temperature regions. A modified ln(I0/T2)-q2σ2/2k2T2 vs. 1/kT plot have given ΦbarB0 and A* as 1.173 eV and 34.750 A/cm2 K2, 0.671 eV and 26.293 A/cm2 K2, 0.354 eV and 10.199 A/cm2 K2, respectively.

  12. Impedance characterization of AlGaN/GaN Schottky diodes with metal contacts

    NASA Astrophysics Data System (ADS)

    Donahue, M.; Lübbers, B.; Kittler, M.; Mai, P.; Schober, A.

    2013-04-01

    To obtain detailed information on structural and electrical properties of AlGaN/GaN Schottky diodes and to determine an appropriate equivalent circuit, impedance spectroscopy and impedance voltage profiling are employed over a frequency range of 1 MHz-1 Hz. In contrast to the commonly assumed parallel connection of capacitive and resistive elements, an equivalent circuit is derived from impedance spectra which utilizes the constant phase element and accounts for frequency dispersion and trap states. The trap density is estimated and is in good agreement with the literature values. The resulting reduced equivalent circuit consists of a capacitor and resistor connected in series.

  13. Finite element analysis of skin effect resistance in submillimeter wave Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Campbell, J. S.; Wrixon, G. T.

    1982-05-01

    The skin effect resistance of GaAs Schottky barrier diodes, operating at high frequency, has been obtained using a specially developed finite element computer program. The devices were analyzed as multiplane finite element models entailing curved high-order numerically integrated isoparametric elements. These models coped easily with complexity of shape and with the near singularity associated with the geometry of the anode. A parametric study entailing twenty-six analyses was carried out, from which it was concluded that the skin effect resistance can be minimized by the correct choice of topographical features such as the extent of the ohmic contact and the anode shape.

  14. Catalytic-Metal/PdO(sub x)/SiC Schottky-Diode Gas Sensors

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Xu, Jennifer C.; Lukco, Dorothy

    2006-01-01

    Miniaturized hydrogen- and hydrocarbon-gas sensors, heretofore often consisting of Schottky diodes based on catalytic metal in contact with SiC, can be improved by incorporating palladium oxide (PdOx, where 0 less than or equal to x less than or equal to 1) between the catalytic metal and the SiC. In prior such sensors in which the catalytic metal was the alloy PdCr, diffusion and the consequent formation of oxides and silicides of Pd and Cr during operation at high temperature were observed to cause loss of sensitivity. However, it was also observed that any PdOx layers that formed and remained at PdCr/SiC interfaces acted as barriers to diffusion, preventing further deterioration by preventing the subsequent formation of metal silicides. In the present improvement, the lesson learned from these observations is applied by placing PdOx at the catalytic metal/SiC interfaces in a controlled and uniform manner to form stable diffusion barriers that prevent formation of metal silicides. A major advantage of PdOx over other candidate diffusion-barrier materials is that PdOx is a highly stable oxide that can be incorporated into gas sensor structures by use of deposition techniques that are standard in the semiconductor industry. The PdOx layer can be used in a gas sensor structure for improved sensor stability, while maintaining sensitivity. For example, in proof-of-concept experiments, Pt/PdOx/SiC Schottky-diode gas sensors were fabricated and tested. The fabrication process included controlled sputter deposition of PdOx to a thickness of 50 Angstroms on a 400-m-thick SiC substrate, followed by deposition of Pt to a thickness of 450 Angstroms on the PdOx. The SiC substrate (400 microns in thickness) was patterned with photoresist and a Schottky-diode photomask. A lift-off process completed the definition of the Schottky-diode pattern. The sensors were tested by measuring changes in forward currents at a bias potential of 1 V during exposure to H2 in N2 at temperatures

  15. Optical response at 10.6 microns in tungsten silicide Schottky barrier diodes

    NASA Technical Reports Server (NTRS)

    Kumar, Sandeep; Boyd, Joseph T.; Jackson, Howard E.

    1987-01-01

    Optical response to radiation at a wavelength of 10.6 microns in tungsten silicide-silicon Schottky barrier diodes has been observed. Incident photons excite electrons by means of junction plasmon assisted inelastic electron tunneling. At 78 K, a peak in the second derivative of current versus junction bias voltage was observed at a voltage corresponding to the energy of photons having a wavelength of 10.6 microns. This peak increased with increasing incident laser power, saturating at the highest laser powers investigated.

  16. Rectifying properties of magnetite-based Schottky diode and the effects of magnetic field

    NASA Astrophysics Data System (ADS)

    Chen, Y. Z.; Sun, J. R.; Xie, Y. W.; Wang, D. J.; Lu, W. M.; Liang, S.; Shen, B. G.

    2007-04-01

    Rectifying properties, with and without magnetic field, of a high quality Fe3O4/SrTiO3:Nb Schottky diode have been experimentally studied. The junction exhibits an excellent rectifying behavior both below and above the Verwey temperature (TV) of Fe3O4. Magnetic field has a weak but visible effect on the transport process of the junction, producing a negative magnetoresistance for T TV. Based on an analysis of the current-voltage characteristics, the spin polarization of Fe3O4 has been deduced. It is a strong function of temperature, varying between -78% and 18%.

  17. Time Dependence of Current-Voltage Characteristics of Pb/p-Si Schottky Diode under Hydrostatic Pressure

    NASA Astrophysics Data System (ADS)

    Ucar, Nazim; Özdemira, Ahmet Faruk; Aldemira, Durmus Ali; Çankayab, Güven

    2011-09-01

    The effect of time on the characteristic parameters of Pb/p-Si Schottky diodes has been presented as a function of hydrostatic pressure. Current-voltage curves of the Pb=p-Si Schottky diodes have been measured at immediate, 15, 30, 60, and 120 min intervals under 1, 2, and 4 kbar hydrostatic pressure. It has been found that the values of the ideality factor have been approximately unchanged with increasing time. On the other hand, the barrier height of the Pb=p-Si structure slowly increase with increasing time, while these parameters also change with hydrostatic pressure. The diode shows nonideal current-voltage behaviour with an ideality factor greater than unity that can be ascribed to the interfacial layer and the interface states. In addition, the Schottky barrier height increases with a linear pressure coefficient of 92 meV=kbar, which is higher than the pressure coefficient of the silicon fundamental band gap.

  18. Temperature dependence of the inhomogeneous parameters of the Mo/4H–SiC Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Latreche, A.; Ouennoughi, Z.; Weiss, R.

    2016-08-01

    The inhomogeneous parameters of Mo/4H–SiC Schottky barrier diodes were determined from current–voltage (I–V) characteristics in the temperature range of 303–498 K by using a general approach for the real Schottky diode. In this approach the total series resistances is divided into two resistances; the first one (R P) is the sum of the series resistances (r) of the particular diodes connected in parallel and the second is the common resistance (R C) to all particular diodes. The mean barrier height (\\bar{φ }) and the standard deviation (σ) decrease linearly with decreasing temperature and they are between the values for the diodes with the two limiting cases; no current spreading and full current spreading. The series resistance R C increases, while the series resistance R P slightly decreases with decreasing temperature.

  19. Fabrication of IrSi(3)/p-Si Schottky diodes by a molecular beam epitaxy technique

    NASA Technical Reports Server (NTRS)

    Lin, T. L.; Iannelli, J. M.

    1990-01-01

    IrSi(3)/p-Si Schottky diodes have been fabricated by a molecular beam epitaxy technique at 630 C. Good surface morphology was observed for IrSi(3) layers grown at temperatures below 680 C, and an increasing tendency to form islands is observed in samples grown at higher temperatures. Good diode current-voltage characteristics were observed and Schottky barrier heights of 0.14-0.18 eV were determined by activation energy analysis and spectral response measurement.

  20. Metal-oxide-semiconductor capacitors and Schottky diodes studied with scanning microwave microscopy at 18 GHz

    SciTech Connect

    Kasper, M.; Gramse, G.; Hoffmann, J.; Gaquiere, C.; Feger, R.; Stelzer, A.; Smoliner, J.; Kienberger, F.

    2014-11-14

    We measured the DC and RF impedance characteristics of micrometric metal-oxide-semiconductor (MOS) capacitors and Schottky diodes using scanning microwave microscopy (SMM). The SMM consisting of an atomic force microscopy (AFM) interfaced with a vector network analyser (VNA) was used to measure the reflection S11 coefficient of the metallic MOS and Schottky contact pads at 18 GHz as a function of the tip bias voltage. By controlling the SMM biasing conditions, the AFM tip was used to bias the Schottky contacts between reverse and forward mode. In reverse bias direction, the Schottky contacts showed mostly a change in the imaginary part of the admittance while in forward bias direction the change was mostly in the real part of the admittance. Reference MOS capacitors which are next to the Schottky diodes on the same sample were used to calibrate the SMM S11 data and convert it into capacitance values. Calibrated capacitance between 1–10 fF and 1/C{sup 2} spectroscopy curves were acquired on the different Schottky diodes as a function of the DC bias voltage following a linear behavior. Additionally, measurements were done directly with the AFM-tip in contact with the silicon substrate forming a nanoscale Schottky contact. Similar capacitance-voltage curves were obtained but with smaller values (30–300 aF) due to the corresponding smaller AFM-tip diameter. Calibrated capacitance images of both the MOS and Schottky contacts were acquired with nanoscale resolution at different tip-bias voltages.

  1. Modeling of Kink-Shaped Carbon-Nanotube Schottky Diode with Gate Bias Modulation

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryan (Technical Monitor)

    2001-01-01

    A model is proposed for the recent gate-voltage (V(sub G)) modulation experiment of a kink-shaped carbon nanotube (NT) Schottky diode. Since larger V(sub G) increases both the forward and the reverse turn-on voltages of the diode in the experiment, we show that: (1) the rectification must occur at the kink where the metallic and the semiconducting NTs meet, and not at the electrode contact, and (2) the semiconducting NT must be n-type. The turn-on voltages are derived analytically as a function of V(sub G) with the electrode contact contribution and a good agreement is obtained with the experimental data.

  2. Measuring size dependent electrical properties from nanoneedle structures: Pt/ZnO Schottky diodes

    SciTech Connect

    Mao, Shimin; Anderson, Daniel D.; Shang, Tao; Park, Byoungnam; Dillon, Shen J.

    2014-04-14

    This work reports the fabrication and testing of nanoneedle devices with well-defined interfaces that are amenable to a variety of structural and electrical characterization, including transmission electron microscopy. Single Pt/ZnO nanoneedle Schottky diodes were fabricated by a top down method using a combination of electro-polishing, sputtering, and focused ion beam milling. The resulting structures contained nanoscale planar heterojunctions with low ideality factors, the dimensions of which were tuned to study size-dependent electrical properties. The diameter dependence of the Pt/ZnO diode barrier height is explained by a joule heating effect and/or electronic inhomogeneity in the Pt/ZnO contact area.

  3. TCAD simulation for alpha-particle spectroscopy using SIC Schottky diode.

    PubMed

    Das, Achintya; Duttagupta, Siddhartha P

    2015-12-01

    There is a growing requirement of alpha spectroscopy in the fields context of environmental radioactive contamination, nuclear waste management, site decommissioning and decontamination. Although silicon-based alpha-particle detection technology is mature, high leakage current, low displacement threshold and radiation hardness limits the operation of the detector in harsh environments. Silicon carbide (SiC) is considered to be excellent material for radiation detection application due to its high band gap, high displacement threshold and high thermal conductivity. In this report, an alpha-particle-induced electron-hole pair generation model for a reverse-biased n-type SiC Schottky diode has been proposed and verified using technology computer aided design (TCAD) simulations. First, the forward-biased I-V characteristics were studied to determine the diode ideality factor and compared with published experimental data. The ideality factor was found to be in the range of 1.4-1.7 for a corresponding temperature range of 300-500 K. Next, the energy-dependent, alpha-particle-induced EHP generation model parameters were optimised using transport of ions in matter (TRIM) simulation. Finally, the transient pulses generated due to alpha-particle bombardment were analysed for (1) different diode temperatures (300-500 K), (2) different incident alpha-particle energies (1-5 MeV), (3) different reverse bias voltages of the 4H-SiC-based Schottky diode (-50 to -250 V) and (4) different angles of incidence of the alpha particle (0°-70°).The above model can be extended to other (wide band-gap semiconductor) device technologies useful for radiation-sensing application.

  4. TCAD simulation for alpha-particle spectroscopy using SIC Schottky diode.

    PubMed

    Das, Achintya; Duttagupta, Siddhartha P

    2015-12-01

    There is a growing requirement of alpha spectroscopy in the fields context of environmental radioactive contamination, nuclear waste management, site decommissioning and decontamination. Although silicon-based alpha-particle detection technology is mature, high leakage current, low displacement threshold and radiation hardness limits the operation of the detector in harsh environments. Silicon carbide (SiC) is considered to be excellent material for radiation detection application due to its high band gap, high displacement threshold and high thermal conductivity. In this report, an alpha-particle-induced electron-hole pair generation model for a reverse-biased n-type SiC Schottky diode has been proposed and verified using technology computer aided design (TCAD) simulations. First, the forward-biased I-V characteristics were studied to determine the diode ideality factor and compared with published experimental data. The ideality factor was found to be in the range of 1.4-1.7 for a corresponding temperature range of 300-500 K. Next, the energy-dependent, alpha-particle-induced EHP generation model parameters were optimised using transport of ions in matter (TRIM) simulation. Finally, the transient pulses generated due to alpha-particle bombardment were analysed for (1) different diode temperatures (300-500 K), (2) different incident alpha-particle energies (1-5 MeV), (3) different reverse bias voltages of the 4H-SiC-based Schottky diode (-50 to -250 V) and (4) different angles of incidence of the alpha particle (0°-70°).The above model can be extended to other (wide band-gap semiconductor) device technologies useful for radiation-sensing application. PMID:25634901

  5. Frequency dependent dielectric properties in Schottky diodes based on rubrene organic semiconductor

    NASA Astrophysics Data System (ADS)

    Barış, Behzad

    2013-12-01

    Al/rubrene/p-Si Schottky diode has been fabricated by forming a rubrene layer on p type Si by using the spin coating method. The frequency and voltage dependent dielectric constant (ε‧), dielectric loss (ε″), tangent loss (tanδ), electrical modulus (M‧ and M″), and ac electrical conductivity (σ) properties of Al/rubrene/p-Si Schottky diodes have been investigated in the frequency range of 1 kHz-1 MHz at room temperature. It is found that the values of the ε‧, ε″ and tanδ decrease with increasing frequency while an increase is observed in σ and the real component (M‧) of the electrical modulus. The values of ε‧, ε″, and tanδ were found as 5.01, 2.55, and 0.51 for 1 kHz and 2.46, 0.069, and 0.028 for 1 MHz at zero bias, respectively. Furthermore, the imaginary component (M″) of the electric modulus showed a peak that shifts to a higher voltage with decreasing frequency.

  6. Influence of contact shape on AlGaN/GaN Schottky diode prepared on Si with thick buffer layer

    NASA Astrophysics Data System (ADS)

    Kumar, Manoj; Sekiguchi, Hiroto; Okada, Hiroshi; Wakahara, Akihiro

    2013-09-01

    A report on the fabrication and characterization of high performance conventional and ring-shaped AlGaN/GaN Schottky barrier diode on Si is presented. The resulting device exhibited low leakage current, which led to a detectivity performance of 3.48×1013 and 1.76×1013 cm Hz1/2 W-1, respectively, for both conventional and ring-shaped Schottky diode. The differential resistances of both devices were obtained at approximately 1.37×1012 and 1.41×1013 Ω, respectively. The zero bias peak responsivities of conventional and ring-shaped Schottky diodes were estimated to be 3.18 and 2.08 A cm-2/W, respectively. The typical UV to visible rejection ratio was observed over three orders of magnitude at zero bias. The C- V measurements was used to calculate and analyze the polarization sheet charge density of the AlGaN barrier layer by using self-consistently solving Schrodinger's and Poisson's equations. It is demonstrated that the ring shape of the Schottky barrier has higher polarization sheet charge density, which has the consequence that the Schottky shape has influence on the strain of the AlGaN barrier layer.

  7. Temperature dependent electrical properties of Al/Cd0.8Zn0.2S/ITO Schottky diode

    NASA Astrophysics Data System (ADS)

    M, Parameshwari P.; V, Shrisha B.; Naik, K. Gopalakrishna

    2015-06-01

    In this work effect of temperature on the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Al/Cd0.8Zn0.2S/ITO diode were studied. The series resistance, Schottky barrier height and ideality factor of the diode were obtained from the forward I-V characteristics at temperatures ranging193 K - 303 K. Activation energy of the diode was calculated from the reverse bias I-V characteristics. Room temperature C - V measurement was used to find the carrier concentration (NA) and built in voltage (Vb) of the diode. Schottky barrier height (ΦB) was also measured from C-V characteristics at room temperature.

  8. Flexible indium-gallium-zinc-oxide Schottky diode operating beyond 2.45 GHz.

    PubMed

    Zhang, Jiawei; Li, Yunpeng; Zhang, Binglei; Wang, Hanbin; Xin, Qian; Song, Aimin

    2015-01-01

    Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning. PMID:26138510

  9. Laterally Inhomogeneous Barrier Analysis Using Capacitance-Voltage Characteristics of Identically Fabricated Schottky Diodes

    NASA Astrophysics Data System (ADS)

    Çavdar, Şükrü; Tuğluoğlu, Nihat; Akgül, Kübra Bengin; Koralay, Haluk

    2016-08-01

    Au Schottky contacts (50 dots) on n-Si (100) were fabricated by thermal evaporation under the same conditions. The mean of the electrical parameters of the diodes were investigated by means of capacitance-voltage ( C- V) measurements at 1 MHz. Even if the diodes were all equally fabricated, there was a diode-to-diode change. The values of barrier height (ΦB) were determined from the C -2- V characteristics, which ranged from 0.812 eV to 0.837 eV. The Gaussian fit of the barrier height distributions gave a mean of barrier height value of 0.822 eV and a standard value of 0.005 eV. Furthermore, the mean values of other parameters such as the carrier donor concentration ( N D), the diffusion potential at zero bias ( V 0), the Fermi level ( E F), the image force lowering (ΔΦb) and the space charge layer width ( W D) were investigated and determined to be 1.311 × 1015 cm-3, 0.575 V, 0.257 eV, 1.363 × 10-2 eV, and 7.573 × 10-5 cm, respectively.

  10. Flexible indium-gallium-zinc-oxide Schottky diode operating beyond 2.45 GHz

    NASA Astrophysics Data System (ADS)

    Zhang, Jiawei; Li, Yunpeng; Zhang, Binglei; Wang, Hanbin; Xin, Qian; Song, Aimin

    2015-07-01

    Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning.

  11. Flexible indium-gallium-zinc-oxide Schottky diode operating beyond 2.45 GHz.

    PubMed

    Zhang, Jiawei; Li, Yunpeng; Zhang, Binglei; Wang, Hanbin; Xin, Qian; Song, Aimin

    2015-01-01

    Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning.

  12. Application of well characterized e - beam evaporated WSe2 thin films in Schottky Barrier diodes

    NASA Astrophysics Data System (ADS)

    Patel, Mayurkumar M.

    The studies of semiconductor thin films and their junctions such as metal semiconductor junctions (Schottky Barriers) have received much attention due to their applications in various electronic and optoelectronic devices including high frequency switching device, Schottky barrier devices, solar cells etc. But, realization of any electronic device using a combination of bulk and thin film or all bulk or all thin film components essentially requires metallization of metal contacts for electrical signals to flow into and out of the device. Thus junction between two metals and metal-semiconductor is an integral part of the device without which communication to the external circuit components would not be possible. In this reference stable metalsemiconductor contacts of ohmic as well as rectifying nature are very much important from technological point of view. In both cases preparation of reliable and efficient metal contacts with high yield and stability is challenging task for devices operating at high frequencies when packing density is increased by many fold. Thus, the behavior of metal-semiconductor contacts at microscopic scale may be explored for the development of future technology. The subject matter of such contacts is well documented in many books with review of developments in the recent past. Earlier devices were prepared on the bulk elemental semiconductors as an active region which was then followed by crystalline/amorphous compound semiconductors in bulk as well as thin film forms like Solar cells, p-n junction diodes, Schottky barrier devices etc. in recent past. Normally bulk crystalline'or amorphous substrate is used to support device structure made from crystalline/amorphous bulk and thin film. However, to the best of author's knowledge no attempts have been made to study the devices prepared by depositing semiconductor thin film with thin metal film supported by a by a non-conducting glass substrate. For this purpose, studies were carried out on

  13. Neutron and Proton Radiation Damage and Isothermal Annealing of Irradiated SiC Schottky Power Diodes

    SciTech Connect

    Kulisek, Jonathan A.; Blue, Thomas E.

    2009-03-16

    NASA is exploring the potential use of nuclear reactors as power sources for future missions. These missions will require semiconductor switches to be placed in close vicinity to the reactor, in the midst of a high neutron and gamma radiation field. Cree SiC Schottky diodes, part number CSD10120A, rated at 10 A and 1200 V, were chosen as the test articles for this radiation-hardness study, since SiC is a wide bandgap semiconductor that has exhibited tolerance for such high radiation environments. As an extension of previous work regarding the degradation of SiC Schottky diodes in the presence of a neutron and gamma radiation field, isothermal annealing experiments were performed on these diodes after they were irradiated in The Ohio State University Research Reactor (OSURR). The experimental results demonstrate that even at an anneal temperature of only 175 C, a noticeable improvement in the electrical performance of the diodes, in the form of decreased series resistance, may be readily observed from I-V curve measurements. Also, since electrical components used for space applications will also be exposed to charged particle radiation from space, such as high energy protons in the Van Allen Radiation Belts surrounding earth, it is important that, in studying the effects of radiation-induced displacement damage, the effects of both neutron and charged particle radiation are considered. Therefore, the data obtained from this study were compared with the data obtained from previous 203 MeV proton irradiations, for which the same diode model was tested. To develop neutron-proton equivalencies which are relevant to the radiation electronics hardening community and the materials science community, comparisons of the degradation of the diodes for proton and neutron irradiation are made in two ways 1) on the basis of displacement damage dose, D{sub d} for protons and neutrons; and 2) on the basis of initially induced vacancies per atom (at a temperature of 0 K)(IIVPA0) for

  14. Role of self-trapped holes in the photoconductive gain of β-gallium oxide Schottky diodes

    NASA Astrophysics Data System (ADS)

    Armstrong, Andrew M.; Crawford, Mary H.; Jayawardena, Asanka; Ahyi, Ayayi; Dhar, Sarit

    2016-03-01

    Solar-blind photodetection and photoconductive gain >50 corresponding to a responsivity >8 A/W were observed for β-Ga2O3 Schottky photodiodes. The origin of photoconductive gain was investigated. Current-voltage characteristics of the diodes did not indicate avalanche breakdown, which excludes carrier multiplication by impact ionization as the source for gain. However, photocapacitance measurements indicated a mechanism for hole localization for above-band gap illumination, suggesting self-trapped hole formation. Comparison of photoconductivity and photocapacitance spectra indicated that self-trapped hole formation coincides with the strong photoconductive gain. It is concluded that self-trapped hole formation near the Schottky diode lowers the effective Schottky barrier in reverse bias, producing photoconductive gain. Ascribing photoconductive gain to an inherent property like self-trapping of holes can explain the operation of a variety of β-Ga2O3 photodetectors.

  15. Role of self-trapped holes in the photoconductive gain of β-gallium oxide Schottky diodes

    DOE PAGESBeta

    Armstrong, Andrew M.; Crawford, Mary H.; Jayawardena, Asanka; Ahyi, Ayayi; Dhar, Sarit

    2016-03-10

    Solar-blind photodetection and photoconductive gain > 50 corresponding to a responsivity > 8 A/W was observed for β-Ga2O3 Schottky photodiodes. We investigated the origin of photoconductive gain. Current-voltage characteristics of the diodes did not indicate avalanche breakdown, which excludes carrier multiplication by impact ionization as the source for gain. However, photocapacitance measurements indicated a mechanism for hole localization for above-band gap illumination, suggesting self-trapped hole formation. Comparison of photoconductivity and photocapacitance spectra indicated that self-trapped hole formation coincides with the strong photoconductive gain. We conclude that self-trapped hole formation near the Schottky diode lowers the effective Schottky barrier in reversemore » bias, producing photoconductive gain. Ascribing photoconductive gain to an inherent property like self-trapping of holes can explain the operation of a variety of β-Ga2O3 photodetectors.« less

  16. Fabrication and characterization of magnetically tunable metal-semiconductor schottky diode using barium hexaferrite thin film on gold

    NASA Astrophysics Data System (ADS)

    Kaur, Jotinder; Sharma, Vinay; Sharma, Vipul; Veerakumar, V.; Kuanr, Bijoy K.

    2016-05-01

    Barium Hexaferrite (BaM) is an extensively studied magnetic material due to its potential device application. In this paper, we study Schottky junction diodes fabricated using gold and BaM and demonstrate the function of a spintronic device. Gold (50 nm)/silicon substrate was used to grow the BaM thin films (100-150 nm) using pulsed laser deposition. I-V characteristics were measured on the Au/BaM structure sweeping the voltage from ±5 volts. The forward and reverse bias current-voltage curves show diode like rectifying characteristics. The threshold voltage decreases while the output current increases with increase in the applied external magnetic field showing that the I-V characteristics of the BaM based Schottky junction diodes can be tuned by external magnetic field. It is also demonstrated that, the fabricated Schottky diode can be used as a half-wave rectifier, which could operate at high frequencies in the range of 1 MHz compared to the regular p-n junction diodes, which rectify below 10 kHz. In addition, it is found that above 1 MHz, Au/BaM diode can work as a rectifier as well as a capacitor filter, making the average (dc) voltage much larger.

  17. Phase locking of 2.324 and 2.959 terahertz quantum cascade lasers using a Schottky diode harmonic mixer.

    PubMed

    Danylov, Andriy; Erickson, Neal; Light, Alexander; Waldman, Jerry

    2015-11-01

    The 23rd and 31st harmonics of a microwave signal generated in a novel THz balanced Schottky diode mixer were used as a frequency stable reference source to phase lock solid-nitrogen-cooled 2.324 and 2.959 THz quantum cascade lasers. Hertz-level frequency stability was achieved, which was maintained for several hours. PMID:26512526

  18. Phase locking of 2.324 and 2.959 terahertz quantum cascade lasers using a Schottky diode harmonic mixer.

    PubMed

    Danylov, Andriy; Erickson, Neal; Light, Alexander; Waldman, Jerry

    2015-11-01

    The 23rd and 31st harmonics of a microwave signal generated in a novel THz balanced Schottky diode mixer were used as a frequency stable reference source to phase lock solid-nitrogen-cooled 2.324 and 2.959 THz quantum cascade lasers. Hertz-level frequency stability was achieved, which was maintained for several hours.

  19. Pt silicide/poly-Si Schottky diodes as temperature sensors for bolometers

    SciTech Connect

    Yuryev, V. A. Chizh, K. V.; Chapnin, V. A.; Mironov, S. A.; Dubkov, V. P.; Uvarov, O. V.; Kalinushkin, V. P.; Senkov, V. M.; Nalivaiko, O. Y.; Novikau, A. G.; Gaiduk, P. I.

    2015-05-28

    Platinum silicide Schottky diodes formed on films of polycrystalline Si doped by phosphorus are demonstrated to be efficient and manufacturable CMOS-compatible temperature sensors for microbolometer detectors of radiation. Thin-film platinum silicide/poly-Si diodes have been produced by a CMOS-compatible process on artificial Si{sub 3}N{sub 4}/SiO{sub 2}/Si(001) substrates simulating the bolometer cells. Layer structure and phase composition of the original Pt/poly-Si films and the Pt silicide/poly-Si films synthesized by a low-temperature process have been studied by means of the scanning transmission electron microscopy; they have also been explored by means of the two-wavelength X-ray structural phase analysis and the X-ray photoelectron spectroscopy. Temperature coefficient of voltage for the forward current of a single diode is shown to reach the value of about −2%/ °C in the temperature interval from 25 to 50 °C.

  20. Pt silicide/poly-Si Schottky diodes as temperature sensors for bolometers

    NASA Astrophysics Data System (ADS)

    Yuryev, V. A.; Chizh, K. V.; Chapnin, V. A.; Mironov, S. A.; Dubkov, V. P.; Uvarov, O. V.; Kalinushkin, V. P.; Senkov, V. M.; Nalivaiko, O. Y.; Novikau, A. G.; Gaiduk, P. I.

    2015-05-01

    Platinum silicide Schottky diodes formed on films of polycrystalline Si doped by phosphorus are demonstrated to be efficient and manufacturable CMOS-compatible temperature sensors for microbolometer detectors of radiation. Thin-film platinum silicide/poly-Si diodes have been produced by a CMOS-compatible process on artificial Si3N4/SiO2/Si(001) substrates simulating the bolometer cells. Layer structure and phase composition of the original Pt/poly-Si films and the Pt silicide/poly-Si films synthesized by a low-temperature process have been studied by means of the scanning transmission electron microscopy; they have also been explored by means of the two-wavelength X-ray structural phase analysis and the X-ray photoelectron spectroscopy. Temperature coefficient of voltage for the forward current of a single diode is shown to reach the value of about -2%/ °C in the temperature interval from 25 to 50 °C.

  1. Electrical Characterization of High Energy Electron Irradiated Ni/4 H-SiC Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Paradzah, A. T.; Omotoso, E.; Legodi, M. J.; Auret, F. D.; Meyer, W. E.; Diale, M.

    2016-08-01

    The effect of high energy electron irradiation on Ni/4 H-SiC Schottky barrier diodes was evaluated by current-voltage ( I- V) and capacitance-voltage ( C- V) measurements at room temperature. Electron irradiation was achieved by using a radioactive strontium source with peak emission energy of 2.3 MeV. Irradiation was performed in fluence steps of 4.9 × 1013 cm-2 until a total fluence of 5.4 × 1014 cm-2 was reached. The Schottky barrier height determined from I- V measurements was not significantly changed by irradiation while that obtained from C- V measurements increased with irradiation. The ideality factor was obtained before irradiation as 1.05 and this value did not significantly change as a result of irradiation. The series resistance increased from 47 Ω before irradiation to 74 Ω after a total electron fluence of 5.4 × 1014 cm-2. The net donor concentration decreased with increasing irradiation fluence from 4.6 × 1014 cm-3 to 3.0 × 1014 cm-3 from which the carrier removal rate was calculated to be 0.37 cm-1.

  2. Frequency dependent capacitance and conductance properties of Schottky diode based on rubrene organic semiconductor

    NASA Astrophysics Data System (ADS)

    Barış, Behzad

    2013-10-01

    Al/rubrene/p-Si Schottky diode has been fabricated by forming a rubrene layer on p type Si by using the spin coating method. The frequency dependent capacitance-voltage (C-V-f) and conductance-voltage (G-V-f) characteristics of Al/rubrene/p-Si Schottky diyotes has been investigated in the frequency range of 5 kHz-500 kHz at room temperature. The C-V plots show a peak for each frequency. The capacitance of the device decreased with increasing frequency. The decrease in capacitance results from the presence of interface states. The plots of series resistance-voltage (Rs-V) gave a peak in the depletion region at all frequencies. The density of interface states (Nss) and relaxation time (τ) distribution profiles as a function of applied voltage bias have been determined from the C-V and G-V measurements. The values of the Nss and τ have been calculated in the ranges of 8.37×1011-4.85×1011 eV-1 cm-2 and 5.17×10-6-1.02×10-5 s, respectively.

  3. Schottky diode characteristics and 1/f noise of high sensitivity reduced graphene oxide/Si heterojunction photodetector

    NASA Astrophysics Data System (ADS)

    Zhu, Miao; Li, Xinming; Li, Xiao; Zang, Xiaobei; Zhen, Zhen; Xie, Dan; Fang, Ying; Zhu, Hongwei

    2016-03-01

    Reduced graphene oxide (RGO)/Si Schottky diode has been reported nowadays to show excellent performances in photodetection and other photoelectrical devices. Different from pure graphene, there are large amounts of function groups and structural defects left on the base plane of RGO, which may influence the interfacial properties of RGO/Si Schottky diode. Herein, the barrier inhomogeneity and junction characteristics were systematically investigated to help to describe the interface of RGO/Si diode. From the perspective of its applications, the influences of gas molecule and noise properties are considered to be important. Thus, the photovoltaic performance of RGO/Si devices in air and vacuum is investigated to analyze their effects. Meanwhile, 1/f noise of RGO/Si diodes is investigated under air/vacuum conditions and varied temperatures. It is found that the devices in vacuum and under higher power incident light show much lower 1/f noise. These results are meaningful to the noise control and performance improvement in the development of Schottky diode based devices.

  4. Excess leakage currents in high-voltage 4H-SiC Schottky diodes

    SciTech Connect

    Ivanov, P. A. Grekhov, I. V.; Potapov, A. S.; Samsonova, T. P.; Il'inskaya, N. D.; Kon'kov, O. I.; Serebrennikova, O. Yu.

    2010-05-15

    The high-voltage 4H-SiC Schottky diodes are fabricated with a nickel barrier and a guard system in the form of 'floating' planar p-n junctions. The analysis of I-V characteristics measured in a wide temperature range shows that the forward current is caused by thermionic emission; however, the current is 'excessive' in the reverse direction. It is assumed that the reverse current flows locally through the points of the penetrating-dislocation outcrop to the Ni-SiC interface. The shape of reverse I-V characteristics makes it possible to conclude that the electron transport is governed by the monopolar-injection mechanism (the space-charge limited current) with participation of capture traps.

  5. The studies of Schottky-diode based co-plane detector for surface plasmon resonance sensing

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Sheng; Wen, Tsun-Yu; Wang, Da-Shin; Lin, Chii-Wann

    2010-08-01

    The Surface Plasmon Resonance (SPR) is a label-free, highly sensitive and real time sensing technique and has been extensively applied to biosensing and assay for decades. In a conventional SPR biosensor, a prism is used to create the total reflection in which the evanescent wave can excite the surface plasmon mode at the metal-dielectric interface at certain angle, at which condition the reflectivity of incident TM-polarized vanished as measured by a far-field photodetector. This is the optical detection of surface plasmon resonance. In this research, zinc oxide (ZnO) was used as the dielectric thin-film material above the gold surface on the glass substrate to form a co-plane Schottky diode; this structure is designed to be an alternative way to detect SPR. The strength of plasmonic field is possible to be monitored by measuring the photocurrent under the reverse bias. According to our experimental results, the measured photocurrents with TM-polarized illumination (representing the SPR case), TE-polarized illumination (non-SPR case) and no illumination conditions under DC -1.5V bias are -76.158mA (2.5μA), -76.085mA (3.6μA) and -76.089mA (3.4μA), respectively. Based on the results, we have demonstrated this Schottky diode based co-plane device has the potential to be used as the SPR detector and provides a possible solution for the need of a low-cost, miniaturized, electronically integrated, and portable SPR biosensor in the near future.

  6. High sensitivity Schottky junction diode based on monolithically grown aligned polypyrrole nanofibers: Broad range detection of m-dihydroxybenzene.

    PubMed

    Ameen, Sadia; Akhtar, M Shaheer; Seo, Hyung-Kee; Shin, Hyung Shik

    2015-07-30

    Aligned p-type polypyrrole (PPy) nanofibers (NFs) thin film was grown on n-type silicon (100) substrate by an electrochemical technique to fabricate Schottky junction diode for the efficient detection of m-dihydroxybenzene chemical. The highly dense and well aligned PPy NFs with the average diameter (∼150-200 nm) were grown on n-type Si substrate. The formation of aligned PPy NFs was confirmed by elucidating the structural, compositional and the optical properties. The electrochemical behavior of the fabricated Pt/p-aligned PPy NFs/n-silicon Schottky junction diode was evaluated by cyclovoltametry (CV) and current (I)-voltage (V) measurements with the variation of m-dihydroxybenzene concentration in the phosphate buffer solution (PBS). The fabricated Pt/p-aligned PPy NFs/n-silicon Schottky junction diode exhibited the rectifying behavior of I-V curve with the addition of m-dihydroxybenzene chemical, while a weak rectifying I-V behavior was observed without m-dihydroxybenzene chemical. This non-linear I-V behavior suggested the formation of Schottky barrier at the interface of Pt layer and p-aligned PPy NFs/n-silicon thin film layer. By analyzing the I-V characteristics, the fabricated Pt/p-aligned PPy NFs/n-silicon Schottky junction diode displayed reasonably high sensitivity ∼23.67 μAmM(-1)cm(-2), good detection limit of ∼1.51 mM with correlation coefficient (R) of ∼0.9966 and short response time (10 s).

  7. A 1100+ V AlGaN/GaN-Based Planar Schottky Barrier Diode without Edge Termination

    NASA Astrophysics Data System (ADS)

    Cao, Dong-Sheng; Lu, Hai; Chen, Dun-Jun; Han, Ping; Zhang, Rong; Zheng, You-Dou

    2011-01-01

    AlGaN/GaN-based planar Schottky barrier diodes with various spacings between ohmic and Schottky contacts are fabricated without any edge termination. The reverse leakage current of the devices quickly saturates at low reverse bias when the two-dimensional electron gas (2DEG) at the AlGaN/GaN interface is fully depleted. The corresponding breakdown voltage is found to follow a linear dependence on contact spacing and exceeds 1100 V at a contact spacing of 20 μm, yielding a high V2BR/RON value of > 280 MW·cm-2. The observations are tentatively explained by a “natural super-junction" theory, in which ionized surface states at front surface of the AlGaN barrier have to be neutralized by reverse surface leakage current from the Schottky electrode.

  8. Planar InP-based Schottky barrier diodes for terahertz applications

    NASA Astrophysics Data System (ADS)

    Jingtao, Zhou; Chengyue, Yang; Ji, Ge; Zhi, Jin

    2013-06-01

    Based on characteristics such as low barrier and high electron mobility of lattice matched In0.53Ga0.47As layer, InP-based Schottky barrier diodes (SBDs) exhibit the superiorities in achieving a lower turn-on voltage and series resistance in comparison with GaAs ones. Planar InP-based SBDs have been developed in this paper. Measurements show that a low forward turn-on voltage of less than 0.2 V and a cutoff frequency of up to 3.4 THz have been achieved. The key factors of the diode such as series resistance and the zero-biased junction capacitance are measured to be 3.32 Ω and 9.1 fF, respectively. They are highly consistent with the calculated values. The performances of the InP-based SBDs in this work, such as low noise and low loss, are promising for applications in the terahertz mixer, multiplier and detector circuits.

  9. Influence of monomer concentration on polycarbazole-polyindole (PCz-PIn) copolymer properties: Application in Schottky diode

    NASA Astrophysics Data System (ADS)

    Gupta, Bhavana; Singh, Arun Kumar; Melvin, Ambrose A.; Prakash, Rajiv

    2014-09-01

    Copolymerization of carbazole (Cz) and indole (In) is successfully performed through potentiostatic polymerization; and the influence of the monomer concentrations ratio on copolymer formation, is investigated. It is found that 1:2 ratio of Cz to In monomer is optimum for the synthesis of a copolymer with high electroactivity. The structural, optical, thermal and morphological analysis of the copolymers are carried out with UV-vis, FT-IR spectroscopy, differential scanning coulometry (DSC) and scanning electron microscopic (SEM) technique. Electrochemical and thermal studies, further support better redox activity and thermal stability of the copolymer, respectively. We also report fabrication and characterizations of the electrochemically synthesized copolymer in organic Schottky diode with configuration metal Al/copolymer/indium tin oxide coated glass (ITO). The current density-voltage (J-V) characteristic of the Schottky diode is consequential in extracting the electronic parameters and the charge transport mechanism of the devices.

  10. Studies on metal/n-GaAs Schottky barrier diodes: The effects of temperature and carrier concentrations

    SciTech Connect

    Mangal, Sutanu; Banerji, P.

    2009-04-15

    Metal/Semiconductor Schottky diodes were fabricated to study the effect of temperature and carrier concentrations on diode parameters, such as ideality factor and barrier heights. The diodes were formed on the epitaxial layers of metal organic chemical vapor deposition (MOCVD) grown n-GaAs with metals such as Al, Pd, and Zn-Pd deposited onto n-GaAs by thermal evaporation technique. Trimethyl gallium and AsH{sub 3} were used as Ga and As precursors, respectively, to grow GaAs on semi-insulating GaAs substrates at 600 deg. C and H{sub 2}S was used for n-type doping in a horizontal reactor atmospheric pressure MOCVD system. The Schottky diodes were characterized by forward bias current-voltage measurements in the temperature range 130-300 K and capacitance-voltage measurement at room temperature and diode parameters such as ideality factor and barrier height have been evaluated. It is found that the Schottky barrier height decreases with decrease in temperature while the ideality factor increases. It is also observed that the barrier height increases linearly with the applied forward bias voltage and the rate of change of barrier height with voltage increases for higher carrier concentration of the semiconductor. The carrier concentration of n-GaAs was chosen in the regime 1x10{sup 16}-8.2x10{sup 16} cm{sup -3} so that the depletion region extends inside the semiconductor and the diode can be used as a III-V photovoltaic device.

  11. Franz–Keldysh effect in n-type GaN Schottky barrier diode under high reverse bias voltage

    NASA Astrophysics Data System (ADS)

    Maeda, Takuya; Okada, Masaya; Ueno, Masaki; Yamamoto, Yoshiyuki; Horita, Masahiro; Suda, Jun

    2016-09-01

    The photocurrent of GaN vertical Schottky barrier diodes was investigated under sub-bandgap wavelength light irradiation. Under a low reverse bias voltage, the photocurrent is induced by internal photoemission, while under a high reverse bias voltage, the photocurrent increases significantly with the bias voltage. This is due to sub-bandgap optical absorption in a depletion region due to the Franz–Keldysh effect. The voltage and wavelength dependences of the photocurrent are successfully explained quantitatively.

  12. CdSe Nanowire-Based Flexible Devices: Schottky Diodes, Metal-Semiconductor Field-Effect Transistors, and Inverters.

    PubMed

    Jin, Weifeng; Zhang, Kun; Gao, Zhiwei; Li, Yanping; Yao, Li; Wang, Yilun; Dai, Lun

    2015-06-24

    Novel CdSe nanowire (NW)-based flexible devices, including Schottky diodes, metal-semiconductor field-effect transistors (MESFETs), and inverters, have been fabricated and investigated. The turn-on voltage of a typical Schottky diode is about 0.7 V, and the rectification ratio is larger than 1 × 10(7). The threshold voltage, on/off current ratio, subthreshold swing, and peak transconductance of a typical MESFET are about -0.3 V, 4 × 10(5), 78 mV/dec, and 2.7 μS, respectively. The inverter, constructed with two MESFETs, exhibits clear inverting behavior with the gain to be about 28, 34, and 38, at the supply voltages (V(DD)) of 3, 5, and 7 V, respectively. The inverter also shows good dynamic behavior. The rising and falling times of the output signals are about 0.18 and 0.09 ms, respectively, under 1000 Hz square wave signals input. The performances of the flexible devices are stable and reliable under different bending conditions. Our work demonstrates these flexible NW-based Schottky diodes, MESFETs, and inverters are promising candidate components for future portable transparent nanoelectronic devices.

  13. The Study of 0.34 THz Monolithically Integrated Fourth Subharmonic Mixer Using Planar Schottky Barrier Diode

    NASA Astrophysics Data System (ADS)

    Tong, Xiaodong; Li, Qian; An, Ning; Wang, Wenjie; Deng, Xiaodong; Zhang, Liang; Liu, Haitao; Zeng, Jianping; Li, Zhiqiang; Tang, Hailing; Xiong, Yong-Zhong

    2015-11-01

    A planar Schottky barrier diode with the designed Schottky contact area of approximately 3 μm2 is developed on gallium arsenide (GaAs) material. The measurements of the developed planar Schottky barrier diode indicate that the zero-biased junction capacitance Cj0 is 11.0 fF, the parasitic series resistance RS is 3.0 Ω, and the cut off frequency fT is 4.8 THz. A monolithically integrated fourth subharmonic mixer with this diode operating at the radio frequency (RF) signal frequency of 0.34 THz with the chip area of 0.6 mm2 is implemented. The intermediate frequency (IF) bandwidth is from DC to 40 GHz. The local oscillator (LO) bandwidth is 37 GHz from 60 to 97 GHz. The RF bandwidth is determined by the bandwidth of the on chip antenna, which is 28 GHz from 322 to 350 GHz. The measurements of the mixer demonstrated a conversion loss of approximately 51 dB.

  14. Current transient spectroscopy for trapping analysis on Au-free AlGaN/GaN Schottky barrier diode

    SciTech Connect

    Hu, J. Groeseneken, G.; Stoffels, S.; Lenci, S.; Venegas, R.; Decoutere, S.; Bakeroot, B.

    2015-02-23

    This paper presents a combined technique of high voltage off-state stress and current transient measurements to investigate the trapping/de-trapping characteristics of Au-free AlGaN/GaN Schottky barrier diodes. The device features a symmetric three-terminal structure with a central anode contact surrounded by two separate cathodes. Under the diode off-state stress conditions, the two separate cathodes were electrically shorted. The de-trapping dynamics was studied by monitoring the recovery of the two-dimensional electron gas (2DEG) current at different temperatures by applying 0.5 V at cathode 2 while grounding cathode 1. During the recovery, the anode contact acts as a sensor of changes in diode leakage current. This leakage variation was found to be mainly due to the barrier height variation. With this method, the energy level and capture cross section of different traps in the AlGaN/GaN Schottky barrier diode can be extracted. Furthermore, the physical location of different trapping phenomena is indicated by studying the variation of the diode leakage current during the recovery. We have identified two distinct trapping mechanisms: (i) electron trapping at the AlGaN surface in the vicinity of the Schottky contact which results in the leakage reduction (barrier height ϕ{sub B} increase) together with R{sub ON} degradation; (ii) the electron trapping in the GaN channel layer which partially depletes the 2DEG. The physical origin of the two different traps is discussed in the text.

  15. Current transient spectroscopy for trapping analysis on Au-free AlGaN/GaN Schottky barrier diode

    NASA Astrophysics Data System (ADS)

    Hu, J.; Stoffels, S.; Lenci, S.; Bakeroot, B.; Venegas, R.; Groeseneken, G.; Decoutere, S.

    2015-02-01

    This paper presents a combined technique of high voltage off-state stress and current transient measurements to investigate the trapping/de-trapping characteristics of Au-free AlGaN/GaN Schottky barrier diodes. The device features a symmetric three-terminal structure with a central anode contact surrounded by two separate cathodes. Under the diode off-state stress conditions, the two separate cathodes were electrically shorted. The de-trapping dynamics was studied by monitoring the recovery of the two-dimensional electron gas (2DEG) current at different temperatures by applying 0.5 V at cathode 2 while grounding cathode 1. During the recovery, the anode contact acts as a sensor of changes in diode leakage current. This leakage variation was found to be mainly due to the barrier height variation. With this method, the energy level and capture cross section of different traps in the AlGaN/GaN Schottky barrier diode can be extracted. Furthermore, the physical location of different trapping phenomena is indicated by studying the variation of the diode leakage current during the recovery. We have identified two distinct trapping mechanisms: (i) electron trapping at the AlGaN surface in the vicinity of the Schottky contact which results in the leakage reduction (barrier height ϕB increase) together with RON degradation; (ii) the electron trapping in the GaN channel layer which partially depletes the 2DEG. The physical origin of the two different traps is discussed in the text.

  16. Investigation of the Electrical Characteristics of Al/p-Si/Al Schottky Diode

    NASA Astrophysics Data System (ADS)

    Şenarslan, Elvan; Güzeldir, Betül; Sağlam, Mustafa

    2016-04-01

    In this study, p-type Si semiconductor wafer with (100) orientation, 400 μm thickness and 1-10 Ω cm resistivity was used. The Si wafer before making contacts were chemically cleaned with the Si cleaning procedure which for remove organic contaminations were ultrasonically cleaned at acetone and methanol for 10 min respectively and then rinsed in deionized water of 18 MΩ and dried with high purity N2. Then respectively RCA1(i.e., boiling in NH3+H2O2+6H2O for 10 min at 60°C ), RCA2 (i.e., boiling in HCl+H2O2+6H2O for 10 min at 60°C ) cleaning procedures were applied and rinsed in deionized water followed by drying with a stream of N2. After the cleaning process, the wafer is immediately inserted in to the coating unit. Ohmic contact was made by evaporating of Al on the non-polished side of the p-Si wafer pieces under ~ 4,2 10-6 Torr pressure. After process evaporation, p-Si with omic contac thermally annealed 580°C for 3 min in a quartz tube furnace in N2. Then, the rectifier contact is made by evaporation Al metal diameter of about 1.0 mm on the polished surface of p-Si in turbo molecular pump at about ~ 1 10-6 Torr. Consequently, Al/p-Si/Al Schottky diode was obtained. The I–V measurements of this diode performed by the use of a KEITLEY 487 Picoammeter/Voltage Source and the C–V measurements were performed with HP 4192A (50–13 MHz) LF Impedance Analyzer at room temperature and in dark.

  17. A Study of the Parasitic Properties of the Schottky Barrier Diode

    NASA Astrophysics Data System (ADS)

    Ren, Tianhao; Zhang, Yong; Liu, Shuang; Guo, Fangzhou; Jin, Zhi; Zhou, Jingtao; Yang, Chengyue

    2016-09-01

    In this paper, we present a newly designed parameter extraction method of the Schottky barrier diode (SBD) with the purpose of measuring and studying its parasitic properties. This method includes three kinds of auxiliary configurations and is named as three-configuration parameter extraction method (TPEM). TPEM has such features as simplicity of operation, self-consistence, and accuracy. With TPEM, the accurate parasitic parameters of the diode can be easily obtained. Taking a GaAs SBD as an example, the pad-to-pad capacitance is 7 fF, the air-bridge finger self-inductance 11 pH, the air-bridge finger self-resistance 0.6 Ω, and the finger-to-pad capacitance 2.1 fF. A more accurate approach to finding the value of the series resistant of the SBD is also proposed, and then a complete SBD model is built. The evaluation of the modeling technology, as well as TPEM, is implemented by comparing the simulated and measured I-V curves and the S-parameters. And good agreements are observed. By using TPEM, the influence of the variation of the geometric parameters is studied, and several ways to reduce the parasitic effect are presented. The results show that the width of the air-bridge finger and the length of the channel are the two largest influencing parameters, with the normalized impact factors 0.56 and 0.29, respectively. By using TPEM and the modeling technology presented in this paper, a design process of the SBD is proposed. As an example, a type of SBD suitable for 500-600 GHz zero-biased detection is designed, and the agreement between the simulated and measured results has been improved. SBDs for other applications could be designed in a similar way.

  18. Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry

    SciTech Connect

    Di Venanzio, C.; Marinelli, Marco; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Falco, M. D.; Bagala, P.; Santoni, R.; Pimpinella, M.

    2013-02-15

    Purpose: To investigate the dosimetric properties of synthetic single crystal diamond based Schottky diodes under irradiation with therapeutic electron beams from linear accelerators. Methods: A single crystal diamond detector was fabricated and tested under 6, 8, 10, 12, and 15 MeV electron beams. The detector performances were evaluated using three types of commercial detectors as reference dosimeters: an Advanced Markus plane parallel ionization chamber, a Semiflex cylindrical ionization chamber, and a p-type silicon detector. Preirradiation, linearity with dose, dose rate dependence, output factors, lateral field profiles, and percentage depth dose profiles were investigated and discussed. Results: During preirradiation the diamond detector signal shows a weak decrease within 0.7% with respect to the plateau value and a final signal stability of 0.1% (1{sigma}) is observed after about 5 Gy. A good linear behavior of the detector response as a function of the delivered dose is observed with deviations below {+-}0.3% in the dose range from 0.02 to 10 Gy. In addition, the detector response is dose rate independent, with deviations below 0.3% in the investigated dose rate range from 0.17 to 5.45 Gy/min. Percentage depth dose curves obtained from the diamond detector are in good agreement with the ones from the reference dosimeters. Lateral beam profile measurements show an overall good agreement among detectors, taking into account their respective geometrical features. The spatial resolution of solid state detectors is confirmed to be better than that of ionization chambers, being the one from the diamond detector comparable to that of the silicon diode. A good agreement within experimental uncertainties was also found in terms of output factor measurements between the diamond detector and reference dosimeters. Conclusions: The observed dosimetric properties indicate that the tested diamond detector is a suitable candidate for clinical electron beam dosimetry.

  19. Investigation of the Electrical Characteristics of Al/p-Si/Al Schottky Diode

    NASA Astrophysics Data System (ADS)

    Şenarslan, Elvan; Güzeldir, Betül; Sağlam, Mustafa

    2016-04-01

    In this study, p-type Si semiconductor wafer with (100) orientation, 400 μm thickness and 1-10 Ω cm resistivity was used. The Si wafer before making contacts were chemically cleaned with the Si cleaning procedure which for remove organic contaminations were ultrasonically cleaned at acetone and methanol for 10 min respectively and then rinsed in deionized water of 18 MΩ and dried with high purity N2. Then respectively RCA1(i.e., boiling in NH3+H2O2+6H2O for 10 min at 60°C ), RCA2 (i.e., boiling in HCl+H2O2+6H2O for 10 min at 60°C ) cleaning procedures were applied and rinsed in deionized water followed by drying with a stream of N2. After the cleaning process, the wafer is immediately inserted in to the coating unit. Ohmic contact was made by evaporating of Al on the non-polished side of the p-Si wafer pieces under ~ 4,2 10-6 Torr pressure. After process evaporation, p-Si with omic contac thermally annealed 580°C for 3 min in a quartz tube furnace in N2. Then, the rectifier contact is made by evaporation Al metal diameter of about 1.0 mm on the polished surface of p-Si in turbo molecular pump at about ~ 1 10-6 Torr. Consequently, Al/p-Si/Al Schottky diode was obtained. The I-V measurements of this diode performed by the use of a KEITLEY 487 Picoammeter/Voltage Source and the C-V measurements were performed with HP 4192A (50-13 MHz) LF Impedance Analyzer at room temperature and in dark.

  20. Modification of electrical properties of Au/n-type InP Schottky diode with a high-k Ba0.6Sr0.4TiO3 interlayer

    NASA Astrophysics Data System (ADS)

    Thapaswini, P. Prabhu; Padma, R.; Balaram, N.; Bindu, B.; Rajagopal Reddy, V.

    2016-05-01

    Au/Ba0.6Sr0.4TiO3 (BST)/n-InP metal/insulator/semiconductor (MIS) Schottky diodes have been analyzed by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The surface morphology of the BST films on InP is fairly smooth. The Au/BST/n-InP MIS Schottky diode shows better rectification ratio and low leakage current compared to the conventional Au/n-InP metal-semiconductor (MS) Schottky diode. Higher barrier height is achieved for the MIS Schottky diode compared to the MS Schottky diode. The Norde and Cheung's methods are employed to determine the barrier height, ideality factor and series resistance. The interface state density (NSS) is determined from the forward bias I-V data for both the MS and MIS Schottky diodes. Results reveal that the NSS of the MIS Schottky diode is lower than that of the MS Schottky diode. The Poole-Frenkel emission is found dominating the reverse current in both Au/n-InP MS and Au/BST/n-InP MIS Schottky diodes, indicating the presence of structural defects and trap levels in the dielectric film.

  1. Measuring the Electronic Properties of DNA-Specific Schottky Diodes Towards Detecting and Identifying Basidiomycetes DNA

    NASA Astrophysics Data System (ADS)

    Periasamy, Vengadesh; Rizan, Nastaran; Al-Ta’Ii, Hassan Maktuff Jaber; Tan, Yee Shin; Tajuddin, Hairul Annuar; Iwamoto, Mitsumasa

    2016-07-01

    The discovery of semiconducting behavior of deoxyribonucleic acid (DNA) has resulted in a large number of literatures in the study of DNA electronics. Sequence-specific electronic response provides a platform towards understanding charge transfer mechanism and therefore the electronic properties of DNA. It is possible to utilize these characteristic properties to identify/detect DNA. In this current work, we demonstrate a novel method of DNA-based identification of basidiomycetes using current-voltage (I-V) profiles obtained from DNA-specific Schottky barrier diodes. Electronic properties such as ideality factor, barrier height, shunt resistance, series resistance, turn-on voltage, knee-voltage, breakdown voltage and breakdown current were calculated and used to quantify the identification process as compared to morphological and molecular characterization techniques. The use of these techniques is necessary in order to study biodiversity, but sometimes it can be misleading and unreliable and is not sufficiently useful for the identification of fungi genera. Many of these methods have failed when it comes to identification of closely related species of certain genus like Pleurotus. Our electronics profiles, both in the negative and positive bias regions were however found to be highly characteristic according to the base-pair sequences. We believe that this simple, low-cost and practical method could be useful towards identifying and detecting DNA in biotechnology and pathology.

  2. Illumination effect on electrical characteristics of organic-based Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Uslu, Habibe; Altındal, Şemsettin; Dökme, Ilbilge

    2010-11-01

    The forward and reverse bias capacitance-voltage (C -V) and conductance-voltage (G /ω-V) characteristics of Au/polyvinyl alcohol (Co, Zn-doped)/n-Si Schottky barrier diodes have been investigated depending on illumination intensity at room temperature and 1 MHz. These experimental C -V and G /ω-V characteristics show fairly large illumination dispersion especially in the weak inversion and depletion regions and they increase with the increasing illumination intensity because of the illumination induced interface states and electron-hole pair. The C -V plots show that peaks are the results of the particular distribution density of the interface states (Nss), interfacial polymer layer, and series resistance (Rs) of device. The magnitude of the peaks increases with the increasing illumination intensity and their positions shift from the high forward bias voltage to low forward bias voltages. The C-2-V plots give a straight line in a wide bias voltage region for each illumination intensity. The variation in doping concentration (ND), depletion layer width (WD), and barrier height [ΦB(C -V)] were obtained from these C-2-V plots. In addition, voltage dependent density distribution profile of Nss was obtained from both low-high capacitance (CLF-CHF) and Hill-Coleman methods. It is observed that there is a good agreement between the results obtained by these methods. In addition, voltage dependent Rs profile was obtained from C -V and G /ω-V data by using Nicollian and Brews method.

  3. Detection Properties of Thin-Film Slot-Antenna-Coupled GaAs Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Hayashi, Kosuke; Tachiki, Takashi; Uchida, Takashi; Furuya, Takashi; Idehara, Toshitaka; Yasuoka, Yoshizumi

    2009-08-01

    GaAs Schottky barrier diodes (SBDs) coupled with a thin-film slot antenna were fabricated using a microfabrication technique, and video detection and mixing properties were investigated at 94 GHz. In the video detection, the bias voltage dependence of detected voltage showed almost the same variation with the calculated value derived from the theory of square-law detection. It was confirmed that detected voltage was obtained from the nonlinearity of the current-voltage (I-V) characteristic of the device. A Si extended hemispherical lens was coupled to the device to improve device responsivity. The increase in detected voltage was 22.2 dB upon using a lens with a radius of 10 mm, and a noise equivalent irradiance (NEI) of 1.2×10-10 W/(cm2·Hz1/2) was obtained. In the mixing, IF signals were observed up to a harmonic number of 7 using the thin-film GaAs SBD.

  4. Measuring the Electronic Properties of DNA-Specific Schottky Diodes Towards Detecting and Identifying Basidiomycetes DNA

    PubMed Central

    Periasamy, Vengadesh; Rizan, Nastaran; Al-Ta’ii, Hassan Maktuff Jaber; Tan, Yee Shin; Tajuddin, Hairul Annuar; Iwamoto, Mitsumasa

    2016-01-01

    The discovery of semiconducting behavior of deoxyribonucleic acid (DNA) has resulted in a large number of literatures in the study of DNA electronics. Sequence-specific electronic response provides a platform towards understanding charge transfer mechanism and therefore the electronic properties of DNA. It is possible to utilize these characteristic properties to identify/detect DNA. In this current work, we demonstrate a novel method of DNA-based identification of basidiomycetes using current-voltage (I-V) profiles obtained from DNA-specific Schottky barrier diodes. Electronic properties such as ideality factor, barrier height, shunt resistance, series resistance, turn-on voltage, knee-voltage, breakdown voltage and breakdown current were calculated and used to quantify the identification process as compared to morphological and molecular characterization techniques. The use of these techniques is necessary in order to study biodiversity, but sometimes it can be misleading and unreliable and is not sufficiently useful for the identification of fungi genera. Many of these methods have failed when it comes to identification of closely related species of certain genus like Pleurotus. Our electronics profiles, both in the negative and positive bias regions were however found to be highly characteristic according to the base-pair sequences. We believe that this simple, low-cost and practical method could be useful towards identifying and detecting DNA in biotechnology and pathology. PMID:27435636

  5. Optimization of chemical structure of Schottky-type selection diode for crossbar resistive memory.

    PubMed

    Kim, Gun Hwan; Lee, Jong Ho; Jeon, Woojin; Song, Seul Ji; Seok, Jun Yeong; Yoon, Jung Ho; Yoon, Kyung Jean; Park, Tae Joo; Hwang, Cheol Seong

    2012-10-24

    The electrical performances of Pt/TiO(2)/Ti/Pt stacked Schottky-type diode (SD) was systematically examined, and this performance is dependent on the chemical structures of the each layer and their interfaces. The Ti layers containing a tolerable amount of oxygen showed metallic electrical conduction characteristics, which was confirmed by sheet resistance measurement with elevating the temperature, transmission line measurement (TLM), and Auger electron spectroscopy (AES) analysis. However, the chemical structure of SD stack and resulting electrical properties were crucially affected by the dissolved oxygen concentration in the Ti layers. The lower oxidation potential of the Ti layer with initially higher oxygen concentration suppressed the oxygen deficiency of the overlying TiO(2) layer induced by consumption of the oxygen from TiO(2) layer. This structure results in the lower reverse current of SDs without significant degradation of forward-state current. Conductive atomic force microscopy (CAFM) analysis showed the current conduction through the local conduction paths in the presented SDs, which guarantees a sufficient forward-current density as a selection device for highly integrated crossbar array resistive memory.

  6. Design, fabrication, and performance of a whiskerless Schottky diode for millimeter and submillimeter wave applications

    NASA Astrophysics Data System (ADS)

    McKinney, K.; Mattaugh, R. J.; Bishop, W. L.

    1985-05-01

    Design considerations, fabrication techniques, and performance predictions are presented for a planar whiskerless Schottky diode to be used (in radio astronomy applications) at 100-300 GHz. The anode and ohmic contacts are on the same side of the device, and proton bombardment is used to establish the divided surface (by making some regions of the GaAs wafer semiinsulating) prior to definition of a B-doped SiO2 finger, ohmic contacting, anode formation, and anode contact metallization (all using photolithographic techniques). The contributions of parasitic elements are calculated for a device with a 3.5-micron-deep n(+) layer doped at 2 x 10 to the 18th/cu cm, a 250-nm-thick epitaxial layer doped at 5 x 10 to the 16th/cu cm, and a 1-micron-radius anode (providing zero-bias junction capacitance 7 fE). It is predicted that such a device would have total series resistance 12.58 ohm and total shunt capacitance 1.37 fF, compared with 14.27 ohm and 0.93 fF for the corresponding whiskered device.

  7. Millimeter wave broadband high sensitivity detectors with zero-bias Schottky diodes

    NASA Astrophysics Data System (ADS)

    Changfei, Yao; Ming, Zhou; Yunsheng, Luo; Conghai, Xu

    2015-06-01

    Two broadband detectors at W-band and D-band are analyzed and designed with low barrier Schottky diodes. The input circuit of the detectors is realized by low and high impedance microstrip lines, and their output circuit is composed of a radio frequency (RF) bandstop filter and a tuning line for optimum reflection phase of the RF signal. S-parameters of the complete circuit are exported to a circuit simulator for voltage sensitivity analysis. For the W band detectors, the highest measured voltage sensitivity is 11800 mV/mW at 100 GHz, and the sensitivity is higher than 2000 mV/mW in 80-104 GHz. Measured tangential sensitivity (TSS) is higher than —38 dBm, and its linearity is superior than 0.99992 at 95 GHz. For the D band detector, the highest measured voltage sensitivity is 1600 mV/mW, and the typical sensitivity is 600 mV/mW in 110-170 GHz. TSS is higher than -29 dBm, and its linearity is superior than 0.99961 at 150 GHz.

  8. Design, fabrication, and performance of a whiskerless Schottky diode for millimeter and submillimeter wave applications

    NASA Technical Reports Server (NTRS)

    Mckinney, K.; Mattaugh, R. J.; Bishop, W. L.

    1985-01-01

    Design considerations, fabrication techniques, and performance predictions are presented for a planar whiskerless Schottky diode to be used (in radio astronomy applications) at 100-300 GHz. The anode and ohmic contacts are on the same side of the device, and proton bombardment is used to establish the divided surface (by making some regions of the GaAs wafer semiinsulating) prior to definition of a B-doped SiO2 finger, ohmic contacting, anode formation, and anode contact metallization (all using photolithographic techniques). The contributions of parasitic elements are calculated for a device with a 3.5-micron-deep n(+) layer doped at 2 x 10 to the 18th/cu cm, a 250-nm-thick epitaxial layer doped at 5 x 10 to the 16th/cu cm, and a 1-micron-radius anode (providing zero-bias junction capacitance 7 fE). It is predicted that such a device would have total series resistance 12.58 ohm and total shunt capacitance 1.37 fF, compared with 14.27 ohm and 0.93 fF for the corresponding whiskered device.

  9. Forward current transport mechanisms in Ni/Au-AlGaN/GaN Schottky diodes

    NASA Astrophysics Data System (ADS)

    Yan, Dawei; Jiao, Jinping; Ren, Jian; Yang, Guofeng; Gu, Xiaofeng

    2013-10-01

    The forward current transport mechanisms in Ni/Au-AlGaN/GaN Schottky diodes are studied by temperature dependent current-voltage (T-I-V) measurements from 298 to 473 K. The zero-bias barrier height qϕBn and ideality factor values determined based on the conventional thermionic-emission (TE) model are strong functions of temperature, which cannot be explained by the standard TE theory. Various transport models are considered to analyze the experimental I-V data. The fitting results indicate that the increased current at low bias is due to the trap-assisted tunneling with an effective trap density of about 8.8 × 106 cm-2, while the high-bias current flow is dominated by the TE transport mechanism, accompanied by a significant series resistance effect. By fitting the high-forward-bias I-V characteristics, the effective qϕBn values with a small negative temperature coefficient are obtained. The temperature dependence of the saturation tunneling current and qϕBn is finally explained by considering the thermally induced band gap shrinkage effect.

  10. Fabrication and characterization of Cd0.9Zn0.1Te Schottky diodes for nuclear radiation detectors

    NASA Astrophysics Data System (ADS)

    Mandal, Krishna C.; Muzykov, Peter G.; Krishna, Ramesh M.; Hayes, Timothy C.

    2011-09-01

    We have fabricated and characterized cadmium zinc telluride (CZT) Schottky diodes with low reverse leakage current for high resolution radiation detector applications. The diodes were made using Cd0.9Zn0.1Te detector grade crystals grown by the low temperature tellurium solvent method. The diodes were characterized using electron beam induced current (EBIC) technique to investigate crystallographic defects. The EBIC images were correlated with transmission infrared (TIR) images of CZT crystals and the EBIC contrast was attributed to the nonuniformities in spatial distribution of Te. Further characterization by the thermally stimulated current (TSC) spectroscopy revealed shallow and deep level centers with activation energies 0.25- 0.4 eV and 0.65 - 0.8 eV respectively, which we attribute to intrinsic defects associated with excess of Te. Pulse height spectra (PHS) measurements were carried out using a 241Am (59.6 keV) radiation source on the Frisch collar radiation detectors made from the suitable portions of the CZT ingot used for Schottky diode fabrication, and an energy resolution of ~4.2% FWHM was obtained.

  11. Humidity influenced capacitance and resistance of an Al/DNA/Al Schottky diode irradiated by alpha particles

    PubMed Central

    Al-Ta’ii, Hassan Maktuff Jaber; Amin, Yusoff Mohd; Periasamy, Vengadesh

    2016-01-01

    Deoxyribonucleic acid or DNA based sensors, especially as humidity and alpha particle sensors have become quite popular in recent times due to flexible and highly optimizable nature of this fundamental biomaterial. Application of DNA electronics allow for more sensitive, accurate and effective sensors to be developed and fabricated. In this work, we examined the effect of different humidity conditions on the capacitive and resistive response of Aluminum (Al)/DNA/Al Schottky barrier structure when bombarded by time-dependent dosages of alpha particles. Based on current-voltage profiles, which demonstrated rectifying behaviours, Schottky diode parameters such as ideality factor, barrier height and series resistance was calculated. Results observed generally pointed towards a decrease in the resistance value from the pristine to the radiated structures. It was also demonstrated that under the effect of humidity, the capacitance of the DNA thin film increased from 0.05894 to 92.736 nF, with rising relative humidity level. We also observed the occurrence of the hypersensitivity phenomena after alpha irradiation between 2 to 4 min by observing a drop in the series resistance, crucial in the study of DNA damage and repair mechanisms. These observations may also suggest the exciting possibility of utilizing Al/DNA/Al Schottky diodes as potentially sensitive humidity sensors. PMID:27160654

  12. Humidity influenced capacitance and resistance of an Al/DNA/Al Schottky diode irradiated by alpha particles

    NASA Astrophysics Data System (ADS)

    Al-Ta’Ii, Hassan Maktuff Jaber; Amin, Yusoff Mohd; Periasamy, Vengadesh

    2016-05-01

    Deoxyribonucleic acid or DNA based sensors, especially as humidity and alpha particle sensors have become quite popular in recent times due to flexible and highly optimizable nature of this fundamental biomaterial. Application of DNA electronics allow for more sensitive, accurate and effective sensors to be developed and fabricated. In this work, we examined the effect of different humidity conditions on the capacitive and resistive response of Aluminum (Al)/DNA/Al Schottky barrier structure when bombarded by time-dependent dosages of alpha particles. Based on current-voltage profiles, which demonstrated rectifying behaviours, Schottky diode parameters such as ideality factor, barrier height and series resistance was calculated. Results observed generally pointed towards a decrease in the resistance value from the pristine to the radiated structures. It was also demonstrated that under the effect of humidity, the capacitance of the DNA thin film increased from 0.05894 to 92.736 nF, with rising relative humidity level. We also observed the occurrence of the hypersensitivity phenomena after alpha irradiation between 2 to 4 min by observing a drop in the series resistance, crucial in the study of DNA damage and repair mechanisms. These observations may also suggest the exciting possibility of utilizing Al/DNA/Al Schottky diodes as potentially sensitive humidity sensors.

  13. On the electrical and interface properties of nanostructured CdTe Schottky diodes electrodeposited from an ionic liquid medium

    NASA Astrophysics Data System (ADS)

    Chauhan, Khushbu R.; Mukhopadhyay, Indrajit

    2014-06-01

    A simple and cost effective method to fabricate nearly ideal Schottky diode out of p-CdTe semiconductor is discussed. The efficient re-use of ionic liquid for the deposition of nano-microstructures of CdTe is also disclosed. The I-V characteristic of the diode configured as Cu:FTO:p-CdTe:Cu showed the rectifying nature with a small forward voltage (0.8 V) and a rectification ratio of 6 × 103 at 4.8 V. Theoretical model suggests the diffusion controlled carrier transport process with an ideality factor of 1.1 up to a small forward voltage range whereas the thermionic transport with generation recombination dominates at higher voltages. The interface properties of p-CdTe and FTO were studied by impedance spectroscopy under varied bias conditions to electrically represent the diode.

  14. Using Atom-Probe Tomography to Understand Zn O ∶Al /SiO 2/Si Schottky Diodes

    NASA Astrophysics Data System (ADS)

    Jaramillo, R.; Youssef, Amanda; Akey, Austin; Schoofs, Frank; Ramanathan, Shriram; Buonassisi, Tonio

    2016-09-01

    We use electronic transport and atom-probe tomography to study Zn O ∶Al /SiO 2/Si Schottky diodes on lightly doped n - and p -type Si. We vary the carrier concentration in the ZnO ∶Al films by 2 orders of magnitude, but the Schottky barrier height remains nearly constant. Atom-probe tomography shows that Al segregates to the interface, so that the ZnO ∶Al at the junction is likely to be metallic even when the bulk of the ZnO ∶Al film is semiconducting. We hypothesize that the observed Fermi-level pinning is connected to the insulator-metal transition in doped ZnO. This implies that tuning the band alignment at oxide/Si interfaces may be achieved by controlling the transition between localized and extended states in the oxide, thereby changing the orbital hybridization across the interface.

  15. Temperature dependence of electrical characteristics of Pt/GaN Schottky diode fabricated by UHV e-beam evaporation

    PubMed Central

    2013-01-01

    Temperature-dependent electrical characterization of Pt/n-GaN Schottky barrier diodes prepared by ultra high vacuum evaporation has been done. Analysis has been made to determine the origin of the anomalous temperature dependence of the Schottky barrier height, the ideality factor, and the Richardson constant calculated from the I-V-T characteristics. Variable-temperature Hall effect measurements have been carried out to understand charge transport at low temperature. The modified activation energy plot from the barrier inhomogeneity model has given the value of 32.2 A/(cm2 K2) for the Richardson constant A** in the temperature range 200 to 380 K which is close to the known value of 26.4A/(cm2 K2) for n-type GaN. PMID:24229424

  16. An investigation of the electrical properties of the interface between pyrolytic carbon and silicon for Schottky diode applications

    NASA Astrophysics Data System (ADS)

    Graham, A. P.; Jay, T.; Jakschik, S.; Knebel, S.; Weber, W.; Schröder, U.; Mikolajick, T.

    2012-06-01

    An investigation of the electrical properties of the interface between nano-crystalline, pyrolytic carbon, and silicon is presented. We have deposited conductive carbon films on silicon substrates by the pyrolysis of ethene and structured them into Schottky diodes in order to evaluate the electrical properties of the interface. The results show that the Schottky barrier to n-doped silicon is 0.46 eV, whereas for p-doped silicon, it is 0.66 eV. The carbon to n-type silicon barrier height is comparable to the values for metal silicide contacts in commercial devices. The results imply that no interfacial layer is formed and show the absence of Fermi-level pinning.

  17. High efficiency single Ag nanowire/p-GaN substrate Schottky junction-based ultraviolet light emitting diodes

    SciTech Connect

    Wu, Y.; Li, X.; Xu, P.; Wang, Y.; Shen, X.; Liu, X.; Yang, Q.; Hasan, T.

    2015-02-02

    We report a high efficiency single Ag nanowire (NW)/p-GaN substrate Schottky junction-based ultraviolet light emitting diode (UV-LED). The device demonstrates deep UV free exciton electroluminescence at 362.5 nm. The dominant emission, detectable at ultralow (<1 μA) forward current, does not exhibit any shifts when the forward current is increased. External quantum efficiency (EQE) as high as 0.9% is achieved at 25 μA current at room temperature. Experiments and simulation analysis show that devices fabricated with thinner Ag NWs have higher EQE. However, for very thin Ag NWs (diameter < 250 nm), this trend breaks down due to heat accumulation in the NWs. Our simple device architecture offers a potentially cost-effective scheme to fabricate high efficiency Schottky junction-based UV-LEDs.

  18. Enhanced performances of AlGaInP-based light-emitting diodes with Schottky current blocking layers

    NASA Astrophysics Data System (ADS)

    Ma, Li; Shen, Guang-Di; Gao, Zhi-Yuan; Xu, Chen

    2015-09-01

    A new epitaxial structure of AlGaInP-based light-emitting diode (LED) with a 0.5-μm GaP window layer was fabricated. In addition, indium tin oxide (ITO) and localized Cr deposition beneath the p-pad electrode were used as the current spreading layer and the Schottky current blocking layer (CBL), respectively. The results indicated that ITO and the Schottky CBL improve the total light extraction efficiency by relieving the current density crowding beneath the p-pad electrode. At the current of 20 mA, the light output power of the novel LED was 40% and 19% higher than those of the traditional LED and the new epitaxial LED without CBL. It was also found that the novel LED with ITO and CBL shows better thermal characteristics. Project supported by the National Natural Science Foundation of China (Grant No. 11204009) and the Natural Science Foundation of Beijing, China (Grant No. 4142005).

  19. Compact and Sensitive Millimetre Wave Detectors Based on Low Barrier Schottky Diodes on Impedance Matched Planar Antennas

    NASA Astrophysics Data System (ADS)

    Hoefle, Matthias; Haehnsen, Katharina; Oprea, Ion; Cojocari, Oleg; Penirschke, Andreas; Jakoby, Rolf

    2014-11-01

    Compact and highly responsive millimeter wave planar Schottky detectors are proposed for uni-planar and low-cost fabrication. For optimum power transfer, the zero-bias Schottky diodes are impedance matched by the antenna design itself, with an established meander dipole and a new folded dipole type. In particular, up to 200GHz, the folded dipole exhibits a single responsivity peak, notably beneficial for communications. The realized detectors exhibit an outstanding system RF voltage responsivity of up to 16005mV/mW at 87.8GHz without lenses or pre amplification. In addition, an excellent NEP level is demonstrated by the detectors with 0.39pW/.

  20. An ultra-thin Schottky diode as a transmission particle detector for biological microbeams.

    PubMed

    Grad, Michael; Harken, Andrew; Randers-Pehrson, Gerhard; Attinger, Daniel; Brenner, David J

    2012-12-01

    We fabricated ultrathin metal-semiconductor Schottky diodes for use as transmission particle detectors in the biological microbeam at Columbia University's Radiological Research Accelerator Facility (RARAF). The RARAF microbeam can deliver a precise dose of ionizing radiation in cell nuclei with sub-micron precision. To ensure an accurate delivery of charged particles, the facility currently uses a commercial charged-particle detector placed after the sample. We present here a transmission detector that will be placed between the particle accelerator and the biological specimen, allowing the irradiation of samples that would otherwise block radiation from reaching a detector behind the sample. Four detectors were fabricated with co-planar gold and aluminum electrodes thermally evaporated onto etched n-type crystalline silicon substrates, with device thicknesses ranging from 8.5 μm - 13.5 μm. We show coincident detections and pulse-height distributions of charged particles in both the transmission detector and the commercial detector above it. Detections are demonstrated at a range of operating conditions, including incoming particle type, count rate, and beam location on the detectors. The 13.5 μm detector is shown to work best to detect 2.7 MeV protons (H(+)), and the 8.5 μm detector is shown to work best to detect 5.4 MeV alpha particles ((4)He(++)). The development of a transmission detector enables a range of new experiments to take place at RARAF on radiation-stopping samples such as thick tissues, targets that need immersion microscopy, and integrated microfluidic devices for handling larger quantities of cells and small organisms.

  1. Correlation of EBIC and SWBXT Imaged Defects and Epilayer Growth Pits in 6H-SiC Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Schnable, C. M.; Tabib-Azar, M.; Neudeck, P. G.; Bailey, S. G.; Su, H. B.; Dudley, M.; Raffaelle, R. P.

    2000-01-01

    We show the first direct experimental correlation between the presence of closed core screw dislocations in 6H-SiC epilayers with recombination centers, as well as with some of the small growth pits on the epilayer surface in lightly-doped 6H-SiC Schottky diodes. At every Synchrotron White-Beam X-ray Topography (SWBXT)-identified closed core screw dislocation, an Electron Beam Induced Current (EBIC) image showed a dark spot indicating a recombination center, and Nomarski optical microscope and Atomic Force Microscope (AFM) images showed a corresponding small growth pit with a sharp apex on the surface of the epilayer.

  2. Measurement of Radiation Frequency of Gyrotron by GaAs Schottky Barrier Diodes Coupled with Thin-Film Slot Antenna

    NASA Astrophysics Data System (ADS)

    Hayashi, Kosuke; Furuya, Takashi; Tachiki, Takashi; Uchida, Takashi; Idehara, Toshitaka; Yasuoka, Yoshizumi

    2010-03-01

    Thin-film slot-antenna-coupled GaAs Schottky barrier diodes (SBDs) used at the 180 GHz band were fabricated by microfabrication techniques, and the radiation frequency of a gyrotron at the University of Fukui (Gyrotron FU CW IV) was measured. In second-harmonic mixing using a local oscillator (LO) wave of 88.0899 GHz, an intermediate frequency (IF) signal of 102.8 MHz was observed and the radiation frequency of the gyrotron was found to be 176.077 GHz.

  3. Barrier height enhancement of InP-based n-Ga(0.47)In(0.53)As Schottky-barrier diodes grown by molecular beam epitaxy

    NASA Technical Reports Server (NTRS)

    Kim, J. H.; Li, S. S.; Figueroa, L.

    1988-01-01

    Barrier height enhancement of an InP-based p(+)n-Ga(0.47)In(0.53)As Schottky diode grown by MBE has been demonstrated for infra-red photodetector applications. A barrier height of 0.35 eV for n-Ga(0.47)In(0.53)As Schottky barrier diodes, was increased to the effective barrier height of 0.55 eV, with a p(+)-Ga(0.47)In(0.53)As surface layer of 30 nm thick. The results show a reverse leakage current density of 0.0015 A/sq cm and a junction capacitance of 0.3 pF, which are comparable to those of p-Ga(0.47)In(0.53)As Schottky-barrier diodes at a reverse bias voltage of 5 V.

  4. Studying of barrier height and ideality factor relation in the nano sized Au-n type Si Schottky diodes

    NASA Astrophysics Data System (ADS)

    Yeganeh, M. A.; Mamedov, R. K.; Rahmatallahpur, Sh.

    2011-07-01

    The results of formation of the operating potential barrier height ( Φв) of inhomogeneous Schottky diodes (SD) in view of an additional electric field in the near contact region of the semiconductor and features of its dependence on the external applied voltage are presented. A correlation, between SD heterogeneity and dependence between potential barrier height ( Φв) and ideality factor ( n), is presented. Using conducting probe atomic force microscope (CP-AFM) techniques, it is shown that Au/n-Si diodes consist of sets of parallel-connected and cooperating nano diodes with the contact surfaces sizes in the order of 100-200 nm. The effective Φв and ideality factors of the SD have been obtained from the current-voltage ( I- V) characteristics, which were measured using a CP-AFM along a contact surface. It was experimentally shown that the forward and reverse part of I- V characteristics and their effective Φв and ideality factors of the identically fabricated nano-SD differ from diode to diode. The Φв for the nano-SD has ranged from 0.565 to 0.723 eV and ideality factor from 1.11 to 1.98. No correlation can be found between the Φв and ideality factor. The Φв distribution obtained from the I- V characteristics has been fitted by a Gaussian function but the ideality factor distribution could not be fitted by a Gaussian function.

  5. Magnetic field induced suppression of the forward bias current in Bi2Se3/Si Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Jin, Haoming; Hebard, Arthur

    Schottky diodes formed by van der Waals bonding between freshly cleaved flakes of the topological insulator Bi2Se3 and doped silicon substrates show electrical characteristics in good agreement with thermionic emission theory. The motivation is to use magnetic fields to modulate the conductance of the topologically protected conducting surface state. This surface state in close proximity to the semiconductor surface may play an important role in determining the nature of the Schottky barrier. Current-voltage (I-V) and capacitance-voltage (C-V) characteristics were obtained for temperatures in the range 50-300 K and magnetic fields, both perpendicular and parallel to the interface, as high as 7 T. The I-V curve shows more than 6 decades linearity on semi-logarithmic plots, allowing extraction of parameters such as ideality (η), zero-voltage Schottky barrier height (SBH), and series resistance (Rs). In forward bias we observe a field-induced decrease in current which becomes increasingly more pronounced at higher voltages and lower temperature, and is found to be correlated with changes in Rs rather than other barrier parameters. A comparison of changes in Rs in both field direction will be made with magnetoresistance in Bi2Se3 transport measurement. The work is supported by NSF through DMR 1305783.

  6. The effects of illumination on electrical parameters of Au/P3HT/n-Si Schottky barrier diode

    NASA Astrophysics Data System (ADS)

    Yükseltürk, Esra; Bülbül, M. Mahir; Zeyrek, Sedat

    2016-03-01

    The electrical characteristics of Au/P3HT/n-Si Schottky Barrier Diode (SBD) have been investigated by using current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements at room temperature and 1MHz. The illumination effects on main structure parameters such as zero-bias-barrier height (ΦBo), ideality factor (n), series resistance (Rs) and interface states (Nss) of Au/P3HT/n-Si diode were determined in dark and under various illumination intensities. Under illumination, both of the values of forward and reverse currents have increased with increasing illumination intensity. The density of interface states (Nss) distribution profiles as a function of (Ec-Ess) was extracted from the forward I-V measurements dark and under various illumination intensities. The interface state densities were observed to be strongly illumination dependent and are decreased with increasing illumination intensities.

  7. Influence of temperature on Al/p-CuInAlSe2 thin-film Schottky diodes

    NASA Astrophysics Data System (ADS)

    Parihar, Usha; Ray, Jaymin; Panchal, C. J.; Padha, Naresh

    2016-06-01

    Al/p-CuInAlSe2 Schottky diodes were fabricated using the optimized thin layers of CuInAlSe2 semiconductor. These diodes were used to study their temperature-dependent current-voltage (I-V) and capacitance-voltage (C-V) analysis over a wide range of 233-353 K. Based on these measurements, diode parameters such as ideality factor ( η), barrier height (ϕbo) and series resistance ( R s) were determined from the downward curvature of I-V characteristics using Cheung and Cheung method. The extracted parameters were found to be strongly temperature dependent; ϕbo increases, while η and R s decrease with increasing temperature. This behavior of ϕbo and η with change in temperature has been explained on the basis of barrier inhomogeneities over the MS interface by assuming a Gaussian distribution (GD) of the ϕbo at the interface. GD of barrier height (BH) was confirmed from apparent BH (ϕap) versus q/2 kT plot, and the values of the mean BH and standard deviation (σs) obtained from this plot at zero bias were found to be 1.02 and 0.14 eV, respectively. Also, a modified ln ( {J_{{s}} /T2 } ) - q2 σ_{{s}}2 /2k2 T2 versus q/ kT plot for Al/p-CuInAlSe2 Schottky diodes according to the GD gives ϕbo and Richardson constant ( A ** ) as 1.01 eV and 26 Acm-2 K-2, respectively. The Richardson constant value of 26 Acm-2 K-2 is very close to the theoretical value of 30 Acm-2 K-2. The discrepancy between BHs obtained from I-V and C-V measurements has also been interpreted.

  8. Current-voltage-temperature characteristics of PEDOT:PSS/ZnO thin film-based Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Hernandez-Como, N.; Rodriguez-Lopez, A.; Hernandez-Cuevas, F. J.; Munguia, J.; Garcia, R.; Baca-Arroyo, R.; Aleman, M.

    2016-11-01

    In this work, we report the temperature dependence of the electrical parameters of PEDOT:PSS/ZnO Schottky barrier diodes (SBDs) grown on glass substrates. To understand the current conduction mechanism, the current-voltage-temperature characteristics of PEDOT:PSS/ZnO thin film SBDs were studied. The electrical parameters were extracted with both thermionic emission and Cheung models. The obtained Richardson constant and effective barrier height were 5 A cm-2 °K-2 and 0.74 eV, respectively. The diode ideality factor was 1.5 and the series resistance was 36 Ω. All these electrical parameters turned out to be temperature independent which was associated with the dominant transport mechanisms of thermionic emission. The Richardson constant slightly deviates from theoretical values due to the presence of interfacial defects created by the preparation and deposition of PEDOT:PSS and the ZnO film crystallinity. The conductive polymer PEDOT:PSS, as a Schottky contact to ZnO, arises as an alternative to the expensive noble metals: Pt, Pd, Ag and metal oxides: IrOx, PdOx, PtOx.

  9. Optically and thermally detected deep levels in n-type Schottky and p+-n GaN diodes

    NASA Astrophysics Data System (ADS)

    Hierro, A.; Kwon, D.; Ringel, S. A.; Hansen, M.; Speck, J. S.; Mishra, U. K.; DenBaars, S. P.

    2000-05-01

    N-Schottky and p+-n GaN junctions are currently used for different technologies. A comparison of the deep levels found throughout the entire band gap of n-GaN grown by metal-organic chemical vapor deposition under both configurations is presented. Both deep level optical spectroscopy and deep level transient spectroscopy measurements are used allowing the observation of both majority and minority carrier traps. Deep levels at Ec-Et=0.58-0.62, 1.35, 2.57-2.64, and 3.22 eV are observed for both diode configurations, with concentrations in the ˜1014-1016cm-3 range. The 0.58-0.62 eV level appears correlated with residual Mg impurities in the n side of the p+-n diode measured by secondary-ion-mass spectroscopy, while the 1.35 eV level concentration increases by a factor of ˜4 for the Schottky junction possibly correlating with the carbon profile. The 2.57-2.64 eV level is a minority carrier hole trap in n-GaN, likely related to the yellow photoluminescence band, and is detected both optically from the conduction band (2.64 eV) and thermally from the valence band (0.87 eV).

  10. Schottky diodes between Bi{sub 2}S{sub 3} nanorods and metal nanoparticles in a polymer matrix as hybrid bulk-heterojunction solar cells

    SciTech Connect

    Saha, Sudip K.; Pal, Amlan J.

    2015-07-07

    We report the use of metal-semiconductor Schottky junctions in a conjugated polymer matrix as solar cells. The Schottky diodes, which were formed between Bi{sub 2}S{sub 3} nanorods and gold nanoparticles, efficiently dissociated photogenerated excitons. The bulk-heterojunction (BHJ) devices based on such metal-semiconductor Schottky diodes in a polymer matrix therefore acted as an efficient solar cell as compared to the devices based on only the semiconductor nanorods in the polymer matrix or when gold nanoparticles were added separately to the BHJs. In the latter device, gold nanoparticles offered plasmonic enhancement due to an increased cross-section of optical absorption. We report growth and characteristics of the Schottky junctions formed through an intimate contact between Bi{sub 2}S{sub 3} nanorods and gold nanoparticles. We also report fabrication and characterization of BHJ solar cells based on such heterojunctions. We highlight the benefit of using metal-semiconductor Schottky diodes over only inorganic semiconductor nanorods or quantum dots in a polymer matrix in forming hybrid BHJ solar cells.

  11. Schottky diodes between Bi2S3 nanorods and metal nanoparticles in a polymer matrix as hybrid bulk-heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Saha, Sudip K.; Pal, Amlan J.

    2015-07-01

    We report the use of metal-semiconductor Schottky junctions in a conjugated polymer matrix as solar cells. The Schottky diodes, which were formed between Bi2S3 nanorods and gold nanoparticles, efficiently dissociated photogenerated excitons. The bulk-heterojunction (BHJ) devices based on such metal-semiconductor Schottky diodes in a polymer matrix therefore acted as an efficient solar cell as compared to the devices based on only the semiconductor nanorods in the polymer matrix or when gold nanoparticles were added separately to the BHJs. In the latter device, gold nanoparticles offered plasmonic enhancement due to an increased cross-section of optical absorption. We report growth and characteristics of the Schottky junctions formed through an intimate contact between Bi2S3 nanorods and gold nanoparticles. We also report fabrication and characterization of BHJ solar cells based on such heterojunctions. We highlight the benefit of using metal-semiconductor Schottky diodes over only inorganic semiconductor nanorods or quantum dots in a polymer matrix in forming hybrid BHJ solar cells.

  12. The interface structure of high performance ZnO Schottky diodes

    NASA Astrophysics Data System (ADS)

    Mayes, Edwin L. H.; Partridge, James G.; Field, Matthew R.; McCulloch, Dougal G.; Durbin, Steven M.; Kim, Hyung-Suk; Allen, Martin W.

    2012-08-01

    Oxidized iridium (IrOx) anodes fabricated on n-type ZnO single crystal wafers using reactive pulsed laser deposition are known to produce high quality Schottky barriers with ideality factors approaching the image-force-controlled limit for laterally homogeneous interfaces. These high performance IrOx/ZnO Schottky contacts were cross-sectioned and analyzed using transmission electron microscopy, revealing an amorphous interfacial layer of 2-3 nm thickness. Electron energy loss spectroscopy, used to study the composition of the interface region, showed evidence of significant zinc diffusion across the interface into the IrOx film, which leads to the creation of Zn vacancies (acceptors), in the ZnO sub-interface region. There is also evidence for oxygen passivation near the interface resulting from the use of an active oxygen ambient during the IrOx deposition. Both these factors may explain the outstanding electrical performance of these Schottky devices.

  13. Deep-level transient spectroscopy on an amorphous InGaZnO{sub 4} Schottky diode

    SciTech Connect

    Chasin, Adrian Bhoolokam, Ajay; Nag, Manoj; Genoe, Jan; Heremans, Paul; Simoen, Eddy; Gielen, Georges

    2014-02-24

    The first direct measurement is reported of the bulk density of deep states in amorphous IGZO (indium-gallium-zinc oxide) semiconductor by means of deep-level transient spectroscopy (DLTS). The device under test is a Schottky diode of amorphous IGZO semiconductor on a palladium (Pd) Schottky-barrier electrode and with a molybdenum (Mo) Ohmic contact at the top. The DLTS technique allows to independently measure the energy and spatial distribution of subgap states in the IGZO thin film. The subgap trap concentration has a double exponential distribution as a function energy, with a value of ∼10{sup 19} cm{sup −3} eV{sup −1} at the conduction band edge and a value of ∼10{sup 17} cm{sup −3} eV{sup −1} at an energy of 0.55 eV below the conduction band. Such spectral distribution, however, is not uniform through the semiconductor film. The spatial distribution of subgap states correlates well with the background doping density distribution in the semiconductor, which increases towards the Ohmic Mo contact, suggesting that these two properties share the same physical origin.

  14. Surface and Interface Study of PdCr/SiC Schottky Diode Gas Sensor Annealed at 425 C

    NASA Technical Reports Server (NTRS)

    Chen, Liang-Yu; Hunter, Gary W.; Neudeck, Philip G.; Knight, Dak

    1998-01-01

    The surface and interface properties of Pd(sub 0.9)Cr(sub 0.1/SiC Schottky diode gas sensor both before and after annealing are investigated using Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). At room temperature the alloy reacted with SiC and formed Pd(sub x)Si only in a very narrow interfacial region. After annealing for 250 hours at 425 deg. C, the surface of the Schottky contact area has much less silicon and carbon contamination than that found on the surface of an annealed Pd/SiC structure. Pd(sub x)Si formed at a broadened interface after annealing, but a significant layer of alloy film is still free of silicon and carbon. The chromium concentration with respect to palladium is quite uniform down to the deep interface region. A stable catalytic surface and a clean layer of Pd(sub 0.9)Cr(sub 0.1) film are likely responsible for significantly improved device sensitivity.

  15. Surface and Interface Properties of PdCr/SiC Schottky Diode Gas Sensor Annealed at 425 C

    NASA Technical Reports Server (NTRS)

    Chen, Liang-Yu; Hunter, Gary W.; Neudeck, Philip G.; Knight, Dak

    1998-01-01

    The surface and interface properties of Pd(0.9,)Cr(0.1)/SiC Schottky diode gas sensors both before and after annealing are investigated using Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). At room temperature the alloy reacted with SiC and formed Pd,Si only in a very narrow interfacial region. After annealing for 250 h ,It 425 C, the surface of the Schottky contact area his much less silicon and carbon contamination than that found on the surface of an annealed Pd/SiC structure. Palladium silicides (Pd(x)Si) formed at a broadened interface after annealing, but a significant layer of alloy film is still free of silicon and carbon. The chromium concentration with respect to palladium is quite uniform down to the deep interface region. A stable catalytic surface and a clean layer of Pd(0.9)Cr(0.1) film are likely responsible for significantly improved device sensitivity.

  16. Surface and Interface Properties of PdCr/SiC Schottky Diode Gas Sensor Annealed at 425 C

    NASA Technical Reports Server (NTRS)

    Chen, Liang-Yu; Hunter, Gary W.; Neudeck, Philip G.; Knight, Dak

    1998-01-01

    The surface and interface properties of Pd(0.9)Cr(0.1)/SiC Schottky diode gas sensors both before and after annealing are investigated using Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). At room temperature the alloy reacted with SiC and formed Pd(x)Si only in a very narrow interfacial region. After annealing for 250 hours at 425 C, the surface of the Schottky contact area has much less silicon and carbon contamination than that found on the surface of an annealed Pd/SiC structure. Palladium silicides (Pd(x)Si) formed at a broadened interface after annealing, but a significant layer of alloy film is still free of silicon and carbon. The chromium concentration with respect to palladium is quite uniform down to the deep interface region. A stable catalytic surface and a clean layer of Pd(0.9)Cr(0.1) film are likely responsible for significantly improved device sensitivity.

  17. Semiconducting selenium nanoparticles: Structural, electrical characterization, and formation of a back-to-back Schottky diode device

    NASA Astrophysics Data System (ADS)

    Sinha, Subhojyoti; Kumar Chatterjee, Sanat; Ghosh, Jiten; Kumar Meikap, Ajit

    2013-03-01

    Well crystalline selenium nanoparticles having an optical band gap of 2.95 eV have been synthesized using oxalic acid. Microstructural parameters such as crystallite size, lattice strain, cell parameters, and unit cell volume are estimated from X-ray diffraction line profile analysis by Rietveld refinement technique. dc and ac transport properties of the nanoparticles in the temperature range 300 K ≤ T ≤ 390 K and frequency range 20 Hz ≤ f ≤ 2 MHz have also been studied. The values of dc activation energies in the low and high temperature regions are found to be 0.083 eV and 0.382 eV, respectively. The charge transport mechanism of the sample follows correlated barrier hopping (CBH) model and the calculated value of barrier height and relaxation time is 0.786 eV and 2.023 × 10-11 s, respectively, while grain boundary contribution being greater than the grain contribution. Considering metal electrode-semiconductor contact as a back-to-back Schottky diode device, analysis of the current-voltage and capacitance-voltage characteristics is done to extract the Schottky barrier heights, ideality parameters, built in voltage, and charge density. With ±40 V sweep the capacitance versus voltage characteristics of the sample shows hysteresis behavior which may be attributed to the presence of deep traps.

  18. Characterization of damage on GaAs in a reactive ion beam etching system using Schottky diodes

    SciTech Connect

    Sugata, S.; Asakawa, K.

    1988-05-01

    Chlorine (Cl/sub 2/) reactive ion beam etching (RIBE)-induced damage on the GaAs wafer has been characterized by studing the characteristics of Schottky diodes fabricated on the etched surfaces. The ideality factors and the Schottky barrier heights measured by the current--voltage characteristics for ion extraction voltage range from 30 to 200 V at Cl/sub 2/ gas pressure of 2 x 10/sup -3/ Torr and are comparable to those of the reference sample cleaned by HCl. Both the n value and the barrier height degrade for ion extraction voltage of more than 300 V. For higher Cl/sub 2/ gas pressure, the damage on the etched surface is less. These results suggest that with the low-energy ions and high-Cl/sub 2/ gas pressure, the damage of the GaAs surface is reduced significantly. The electron deep levels induced by RIBE disappear after annealing at 400 /sup 0/C for 10 min.

  19. 1.9 kV AlGaN/GaN Lateral Schottky Barrier Diodes on Silicon

    DOE PAGESBeta

    Zhu, Mingda; Song, Bo; Qi, Meng; Hu, Zongyang; Nomoto, Kazuki; Yan, Xiaodong; Cao, Yu; Johnson, Wayne; Kohn, Erhard; Jena, Debdeep; et al

    2015-02-16

    In this letter, we present AlGaN/GaN lateral Schottky barrier diodes on silicon with recessed anodes and dual field plates. A low specific on-resistance RON,SP (5.12 mΩ · cm2), a low turn-on voltage (<0.7 V) and a high reverse breakdown voltage BV (>1.9 kV), were simultaneously achieved in devices with a 25 μm anode/cathode separation, resulting in a power figure-of-merit (FOM) BV2/RON,SP of 727 MW·cm2. The record high breakdown voltage of 1.9 kV is attributed to the dual field plate structure.

  20. 1.9 kV AlGaN/GaN Lateral Schottky Barrier Diodes on Silicon

    SciTech Connect

    Zhu, Mingda; Song, Bo; Qi, Meng; Hu, Zongyang; Nomoto, Kazuki; Yan, Xiaodong; Cao, Yu; Johnson, Wayne; Kohn, Erhard; Jena, Debdeep; Xing, Grace Huili

    2015-02-16

    In this letter, we present AlGaN/GaN lateral Schottky barrier diodes on silicon with recessed anodes and dual field plates. A low specific on-resistance RON,SP (5.12 mΩ · cm2), a low turn-on voltage (<0.7 V) and a high reverse breakdown voltage BV (>1.9 kV), were simultaneously achieved in devices with a 25 μm anode/cathode separation, resulting in a power figure-of-merit (FOM) BV2/RON,SP of 727 MW·cm2. The record high breakdown voltage of 1.9 kV is attributed to the dual field plate structure.

  1. Current transport mechanisms in lattice-matched Pt/Au-InAlN/GaN Schottky diodes

    SciTech Connect

    Ren, Jian; Yan, Dawei Yang, Guofeng; Wang, Fuxue; Xiao, Shaoqing; Gu, Xiaofeng

    2015-04-21

    Lattice-matched Pt/Au-In{sub 0.17}Al{sub 0.83}N/GaN hetreojunction Schottky diodes with circular planar structure have been fabricated and investigated by temperature dependent electrical measurements. The forward and reverse current transport mechanisms are analyzed by fitting the experimental current-voltage characteristics of the devices with various models. The results show that (1) the forward-low-bias current is mainly due to the multiple trap-assisted tunneling, while the forward-high-bias current is governed by the thermionic emission mechanism with a significant series resistance effect; (2) the reverse leakage current under low electric fields (<6 MV/cm) is mainly carried by the Frenkel-Poole emission electrons, while at higher fields the Fowler-Nordheim tunneling mechanism dominates due to the formation of a triangular barrier.

  2. GaN Schottky diodes with single-crystal aluminum barriers grown by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Tseng, H. Y.; Yang, W. C.; Lee, P. Y.; Lin, C. W.; Cheng, Kai-Yuan; Hsieh, K. C.; Cheng, K. Y.; Hsu, C.-H.

    2016-08-01

    GaN-based Schottky barrier diodes (SBDs) with single-crystal Al barriers grown by plasma-assisted molecular beam epitaxy are fabricated. Examined using in-situ reflection high-energy electron diffractions, ex-situ high-resolution x-ray diffractions, and high-resolution transmission electron microscopy, it is determined that epitaxial Al grows with its [111] axis coincident with the [0001] axis of the GaN substrate without rotation. In fabricated SBDs, a 0.2 V barrier height enhancement and 2 orders of magnitude reduction in leakage current are observed in single crystal Al/GaN SBDs compared to conventional thermal deposited Al/GaN SBDs. The strain induced piezoelectric field is determined to be the major source of the observed device performance enhancements.

  3. Correlation between phonon and impurity scatterings, potential fluctuations and leakage conduction of graphene/n-type Si Schottky diodes

    NASA Astrophysics Data System (ADS)

    Lin, Yow-Jon

    2015-12-01

    A correlation between the temperature-dependent leakage conduction, phonon and impurity scatterings and potential fluctuations of graphene/n-type Si Schottky diodes is identified. For applying a sufficiently high reverse-bias voltage, the significantly increase in the leakage current density with voltage at low temperature is mainly the result of graphene's Fermi-energy shifts. However, the high-field saturating leakage current is observed at high temperature. This is because of the competition among the phonon and impurity scatterings. In the graphene film transferred onto the n-type Si substrate, the Femi energy level is lower and the phonon coupling is stronger, giving a stronger dependence in the carrier velocity with temperature and a weaker dependence in the leakage current density with reserve-bias voltage.

  4. Large barrier, highly uniform and reproducible Ni-Si/4H-SiC forward Schottky diode characteristics: testing the limits of Tung's model

    NASA Astrophysics Data System (ADS)

    Omar, Sabih U.; Sudarshan, Tangali S.; Rana, Tawhid A.; Song, Haizheng; Chandrashekhar, M. V. S.

    2014-07-01

    We report highly ideal (n < 1.1), uniform nickel silicide (Ni-Si)/SiC Schottky barrier (1.60-1.67 eV with a standard deviation <2.8%) diodes, fabricated on 4H-SiC epitaxial layers grown by chemical vapour deposition. The barrier height was constant over a wide epilayer doping range of 1014-1016 cm-3, apart from a slight decrease consistent with image force lowering. This remarkable uniformity was achieved by careful optimization of the annealing of the Schottky interface to minimize non-idealities that could lead to inhomogeneity. Tung's barrier inhomogeneity model was used to quantify the level of inhomogeneity in the optimized annealed diodes. The estimated ‘bulk’ barrier height (1.75 eV) was consistent with the Shockley-Mott limit for the Ni-Si/4H-SiC interface, implying an unpinned Fermi level. But the model was not useful to explain the poor ideality in unoptimized, as-deposited Schottky contacts (n = 1.6 - 2.5). We show analytically and numerically that only idealities n < 1.21 can be explained using Tung's model, irrespective of material system, indicating that the barrier height inhomogeneity is not the only cause of poor ideality in Schottky diodes. For explaining this highly non-ideal behaviour, other factors (e.g. interface traps, morphological defects, extrinsic impurities, etc) need to be considered.

  5. Temperature dependent electrical characterisation of Pt/HfO{sub 2}/n-GaN metal-insulator-semiconductor (MIS) Schottky diodes

    SciTech Connect

    Shetty, Arjun Vinoy, K. J.; Roul, Basanta; Mukundan, Shruti; Mohan, Lokesh; Chandan, Greeshma; Krupanidhi, S. B.

    2015-09-15

    This paper reports an improvement in Pt/n-GaN metal-semiconductor (MS) Schottky diode characteristics by the introduction of a layer of HfO{sub 2} (5 nm) between the metal and semiconductor interface. The resulting Pt/HfO{sub 2}/n-GaN metal-insulator-semiconductor (MIS) Schottky diode showed an increase in rectification ratio from 35.9 to 98.9(@ 2V), increase in barrier height (0.52 eV to 0.63eV) and a reduction in ideality factor (2.1 to 1.3) as compared to the MS Schottky. Epitaxial n-type GaN films of thickness 300nm were grown using plasma assisted molecular beam epitaxy (PAMBE). The crystalline and optical qualities of the films were confirmed using high resolution X-ray diffraction and photoluminescence measurements. Metal-semiconductor (Pt/n-GaN) and metal-insulator-semiconductor (Pt/HfO{sub 2}/n-GaN) Schottky diodes were fabricated. To gain further understanding of the Pt/HfO{sub 2}/GaN interface, I-V characterisation was carried out on the MIS Schottky diode over a temperature range of 150 K to 370 K. The barrier height was found to increase (0.3 eV to 0.79 eV) and the ideality factor decreased (3.6 to 1.2) with increase in temperature from 150 K to 370 K. This temperature dependence was attributed to the inhomogeneous nature of the contact and the explanation was validated by fitting the experimental data into a Gaussian distribution of barrier heights.

  6. Design and characterisations of double-channel GaAs pHEMT Schottky diodes based on vertically stacked MMICs for a receiver protection limiter

    NASA Astrophysics Data System (ADS)

    Haris, Norshakila; Kyabaggu, Peter B. K.; Rezazadeh, Ali A.

    2016-07-01

    A microwave receiver protection limiter circuit has been designed, fabricated and tested using vertically stacked GaAs MMIC technology. The limiter circuit with a dimension of 2.5 × 1.3 mm2 is formed by using double-channel AlGaAs/InGaAs pseudomorphic HEMT (pHEMT) Schottky diodes integrated with a low-loss V-shaped coplanar waveguide multilayer structure. The electrical parameter characteristics of the pHEMT Schottky diodes are presented including the C–V profile showing the presence of a double channel in the device layer structure. This unique feature can also be seen from the double-peak responses of the electron density as a function of the device layer width, which represent the high electron concentration at two different 2-DEG layers of the structure. An equivalent circuit model of pHEMT Schottky diodes is demonstrated showing good agreement with the measurement results. At zero-bias condition, the devices show high performance in diode detector applications with voltage sensitivities of more than 89 mV μW‑1 at 10 GHz and at least 5.4 mV μW‑1 at 35 GHz. The measurement results of the limiter circuit demonstrated the blocking of input power signals greater than 20 dBm input power at 3 GHz. To the best of our knowledge this is the first demonstration of the use of pHEMT Schottky diodes in microwave power limiter applications.

  7. Design and characterisations of double-channel GaAs pHEMT Schottky diodes based on vertically stacked MMICs for a receiver protection limiter

    NASA Astrophysics Data System (ADS)

    Haris, Norshakila; Kyabaggu, Peter B. K.; Rezazadeh, Ali A.

    2016-07-01

    A microwave receiver protection limiter circuit has been designed, fabricated and tested using vertically stacked GaAs MMIC technology. The limiter circuit with a dimension of 2.5 × 1.3 mm2 is formed by using double-channel AlGaAs/InGaAs pseudomorphic HEMT (pHEMT) Schottky diodes integrated with a low-loss V-shaped coplanar waveguide multilayer structure. The electrical parameter characteristics of the pHEMT Schottky diodes are presented including the C-V profile showing the presence of a double channel in the device layer structure. This unique feature can also be seen from the double-peak responses of the electron density as a function of the device layer width, which represent the high electron concentration at two different 2-DEG layers of the structure. An equivalent circuit model of pHEMT Schottky diodes is demonstrated showing good agreement with the measurement results. At zero-bias condition, the devices show high performance in diode detector applications with voltage sensitivities of more than 89 mV μW-1 at 10 GHz and at least 5.4 mV μW-1 at 35 GHz. The measurement results of the limiter circuit demonstrated the blocking of input power signals greater than 20 dBm input power at 3 GHz. To the best of our knowledge this is the first demonstration of the use of pHEMT Schottky diodes in microwave power limiter applications.

  8. Schottky Diode Applications of the Fast Green FCF Organic Material and the Analyze of Solar Cell Characteristics

    NASA Astrophysics Data System (ADS)

    Çaldiran, Z.; Aydoğan, Ş.; İncekara, Ü.

    2016-05-01

    In this study, a device applications of organic material Fast Green FCF (C37H34N2Na2O10S3Na2) has been investigated. After chemical cleaning process of boron doped H-Si crystals, Al metal was coated on the one surface of crystals by thermal evaporation and fast green organic materials were coated on other surface of crystals with spin coating method (coating parameters; 800 rpm for 60 s). Finally, Ni metal was coated on Fast Green by sputtering and we obtained the Ni/Fast Green FCF/n-Si/Al Schottky type diode. And then we calculated the basic diode parameters of device with current-voltage (I-V) and capacitance- voltage (C-V) measurements at the room temperature. We calculated the ideality factory (n), barrier height (Φb) of rectifing contact from I-V measurements using thermionic emission methods. Furthermore, we calculated ideality factory (n), barrier height (Φb) and series resistance (Rs) of device using Cheung and Norde functions too. The diffusion potential, barrier height, Fermi energy level and donor concentration have been determined from the linear 1/C2-V curves at reverse bias, at room temperature and various frequencies. Besides we measured the current-voltage (I-V) at under light and analyzed the characteristics of the solar cell device.

  9. Electrical parameters and series resistance analysis of Au/Y/p-InP/Pt Schottky barrier diode at room temperature

    NASA Astrophysics Data System (ADS)

    Rao, L. Dasaradha; Reddy, V. Rajagopal

    2016-05-01

    The current-voltage (I-V) characteristics of Au/Y/p-InP/Pt Schottky barrier diode (SBD) are analyzed at room temperature. The Au/Y/p-InP/Pt SBD shows a good rectification behavior. The ideality factor (n), barrier height (Φb), series resistance (Rs) and shunt resistance (Rsh) are determined from the I-V measurements. The n and Φb values of Au/Y/p-InP/Pt SBD are found to be 1.32 and 0.62 eV respectively. The value of barrier height (BH) obtained from Norde function is compared with those calculated from Cheung's functions. The series resistance (Rs) is calculated from Cheung's and modified Norde functions. Additionally, it is found that n, Φb, Rs, and Rsh have strong correlation with the applied bias. Furthermore, at low and high voltage regions, ohmic and space-charge-limited conduction mechanisms are found to govern the current flow in the diode.

  10. Probing Hot Electron Flow Generated on Pt Nanoparticles with Au/TiO2 Schottky Diodes during Catalytic CO Oxidation

    SciTech Connect

    Park, Jeong Y.; Lee, Hyunjoo; Renzas, J. Russell; Zhang, Yawen; Somorjai, G.A.

    2008-05-01

    Hot electron flow generated on colloid platinum nanoparticles during exothermic catalytic carbon monoxide oxidation was directly detected with Au/TiO{sub 2} diodes. Although Au/TiO{sub 2} diodes are not catalytically active, platinum nanoparticles on Au/TiO{sub 2} exhibit both chemicurrent and catalytic turnover rate. Hot electrons are generated on the surface of the metal nanoparticles and go over the Schottky energy barrier between Au and TiO{sub 2}. The continuous Au layer ensures that the metal nanoparticles are electrically connected to the device. The overall thickness of the metal assembly (nanoparticles and Au thin film) is comparable to the mean free path of hot electrons, resulting in ballistic transport through the metal. The chemicurrent and chemical reactivity of nanoparticles with citrate, hexadecylamine, hexadecylthiol, and TTAB (Tetradecyltrimethylammonium Bromide) capping agents were measured during catalytic CO oxidation at pressures of 100 Torr O{sub 2} and 40 Torr CO at 373-513 K. We found that chemicurrent yield varies with each capping agent, but always decreases with increasing temperature. We suggest that this inverse temperature dependence is associated with the influence of charging effects due to the organic capping layer during hot electron transport through the metal-oxide interface.

  11. Displacement Damage Induced Catastrophic Second Breakdown in Silicon Carbide Schottky Power Diodes

    NASA Technical Reports Server (NTRS)

    Scheick, Leif; Selva, Luis; Selva, Luis

    2004-01-01

    A novel catastrophic breakdown mode in reversed biased Silicon carbide diodes has been seen for low LET particles. These particles are too low in LET to induce SEB, however SEB was seen from particles of higher LET. The low LET mechanism correlates with second breakdown in diodes due to increase leakage and assisted charge injection from incident particles. Percolation theory was used to predict some basic responses of the devices, but the inherent reliability issue with silicon carbide have proven challenging.

  12. The effect of high temperatures on the electrical characteristics of Au/n-GaAs Schottky diodes

    NASA Astrophysics Data System (ADS)

    Tunhuma, S. M.; Auret, F. D.; Legodi, M. J.; Diale, M.

    2016-01-01

    In this study, the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Au/n-GaAs Schottky diodes have been measured over a wide temperature range, 80-480 K. The diodes were rectifying throughout the range and showed good thermal stability. Room temperature values for the ideality factor, I-V barrier height and C-V barrier height were found to be n=1.10, ϕIV=0.85 eV and ϕCV=0.96 eV, respectively. ϕIV increases and n decreases with an increase in temperature. We investigated the effect of elevated temperatures on the barrier height and ideality factor by measuring the diodes at a high temperature (annealing mode) then immediately afterwards measuring at room temperature (post annealing mode). The measurements indicate I-V characteristics that degrade permanently above 300 K. Permanent changes to the C-V characteristics were observed only above 400 K. We also noted a discrepancy in the C-V barrier height and carrier concentration between 340 and 400 K, which we attribute to the influence of the EL2 defect (positioned 0.83 eV below the conduction band minima) on the free carrier density. Consequently, we were able to fit the ϕCV versus temperature curve into two regions with temperature coefficients -6.9×10-4 eV/K and -2.2×10-4 eV/K above and below 400 K.

  13. Effect of Post Deposition Annealing Treatments on Properties of AZO Thin Films for Schottky Diode Applications.

    PubMed

    Singh, Shaivalini; Park, Si-Hyun

    2016-01-01

    High-quality aluminum (Al) doped ZnO (AZO) thin films were deposited on silicon substrates by RF sputtering at room temperature. The deposited films were annealed from the temperatures 350 °C to 650 °C in pure nitrogen (N₂) ambient. The effects of annealing on the microstructural, optical and electrical properties of the AZO films were investigated. A detailed analysis by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Four Probe and Hall measurements was performed to study the properties of these AZO thin films. It was observed that all of the as-deposited and annealed AZO films have homogenous surfaces and hexagonal wurtzite structures with good crystalline quality. The study also suggested that there was an intermediate post annealing temperature (450 °C) at which the deposited ZnO film exhibit best surface characteristics. Pd/AZO Schottky devices were fabricated with 450 °C annealed AZO thin films and the parameters of Schottky devices were extracted from I-V characteristics. These results indicated that the Pd/AZO films were very much suitable for various optoelectronics applications particularly for metal semiconductor metal based UV detector application. PMID:27398537

  14. Temperature dependence of current-and capacitance-voltage characteristics of an Au/4H-SiC Schottky diode

    NASA Astrophysics Data System (ADS)

    Gülnahar, Murat

    2014-12-01

    In this study, the current-voltage (I-V) and capacitance-voltage (C-V) measurements of an Au/4H-SiC Schottky diode are characterized as a function of the temperature in 50-300 K temperature range. The experimental parameters such as ideality factor and apparent barrier height presents to be strongly temperature dependent, that is, the ideality factor increases and the apparent barrier height decreases with decreasing temperature, whereas the barrier height values increase with the temperature for C-V data. Likewise, the Richardson plot deviates at low temperatures. These anomaly behaviors observed for Au/4H-SiC are attributed to Schottky barrier inhomogeneities. The barrier anomaly which relates to interface of Au/4H-SiC is also confirmed by the C-V measurements versus the frequency measured in 300 K and it is interpreted by both Tung's lateral inhomogeneity model and multi-Gaussian distribution approach. The values of the weighting coefficients, standard deviations and mean barrier height are calculated for each distribution region of Au/4H-SiC using the multi-Gaussian distribution approach. In addition, the total effective area of the patches NAe is obtained at separate temperatures and as a result, it is expressed that the low barrier regions influence meaningfully to the current transport at the junction. The homogeneous barrier height value is calculated from the correlation between the ideality factor and barrier height and it is noted that the values of standard deviation from ideality factor versus q/3kT curve are in close agreement with the values obtained from the barrier height versus q/2kT variation. As a result, it can be concluded that the temperature dependent electrical characteristics of Au/4H-SiC can be successfully commented on the basis of the thermionic emission theory with both models.

  15. Optimal width of barrier region in X/{gamma}-ray Schottky diode detectors based on CdTe and CdZnTe

    SciTech Connect

    Kosyachenko, L. A.; Melnychuk, S. V.; Sklyarchuk, V. M.; Maslyanchuk, O. L.; Sklyarchuk, O. V.; Aoki, T.; Lambropoulos, C. P.; Gnatyuk, V. A.; Grushko, E. V.

    2013-02-07

    The spectral distribution of quantum detection efficiency of X- and {gamma}-ray Schottky diodes based on semi-insulating CdTe or Cd{sub 0.9}Zn{sub 0.1}Te crystals is substantiated and obtained in analytical form. It is shown that the width of the space charge region (SCR) of 6-40 {mu}m at zero bias in CdTe (Cd{sub 0.9}Zn{sub 0.1}Te) Schottky diode is optimal for detecting radiation in the photon energy range above 5-10 keV. Based on the Poisson equation, the relationship between the SCR width and the composition of impurities and the degree of their compensation are investigated. It is shown that the presence of deep levels in the bandgap leads to a considerable increase in space charge density and electric field strength near the crystal surface. However, this effect contributes a small error in the determination of the SCR width using the standard formula for the Schottky diode. It is also shown that the concentration of uncompensated impurities in CdTe and Cd{sub 0.9}Zn{sub 0.1}Te crystals within the 4 Multiplication-Sign 10{sup 11}-10{sup 13} cm{sup -3} range is optimal for the detection efficiency of X- and {gamma}-rays in the photon high-energy range. The record-high values of energy resolution have been obtained in the spectra of {sup 241}Am, {sup 57}Co, {sup 133}Ba and {sup 137}Cs isotopes measured using CdTe crystals with Schottky diodes because the concentration of uncompensated donors in the CdTe crystals (1-2) Multiplication-Sign 10{sup 12} cm{sup -3} falls on an interval of maximum detection efficiency. In the spectrum of {sup 57}Co isotope, the limiting energy resolution has been achieved.

  16. Optimal width of barrier region in X/γ-ray Schottky diode detectors based on CdTe and CdZnTe

    NASA Astrophysics Data System (ADS)

    Kosyachenko, L. A.; Aoki, T.; Lambropoulos, C. P.; Gnatyuk, V. A.; Melnychuk, S. V.; Sklyarchuk, V. M.; Grushko, E. V.; Maslyanchuk, O. L.; Sklyarchuk, O. V.

    2013-02-01

    The spectral distribution of quantum detection efficiency of X- and γ-ray Schottky diodes based on semi-insulating CdTe or Cd0.9Zn0.1Te crystals is substantiated and obtained in analytical form. It is shown that the width of the space charge region (SCR) of 6-40 μm at zero bias in CdTe (Cd0.9Zn0.1Te) Schottky diode is optimal for detecting radiation in the photon energy range above 5-10 keV. Based on the Poisson equation, the relationship between the SCR width and the composition of impurities and the degree of their compensation are investigated. It is shown that the presence of deep levels in the bandgap leads to a considerable increase in space charge density and electric field strength near the crystal surface. However, this effect contributes a small error in the determination of the SCR width using the standard formula for the Schottky diode. It is also shown that the concentration of uncompensated impurities in CdTe and Cd0.9Zn0.1Te crystals within the 4 × 1011-1013 cm-3 range is optimal for the detection efficiency of X- and γ-rays in the photon high-energy range. The record-high values of energy resolution have been obtained in the spectra of 241Am, 57Co, 133Ba and 137Cs isotopes measured using CdTe crystals with Schottky diodes because the concentration of uncompensated donors in the CdTe crystals (1-2) × 1012 cm-3 falls on an interval of maximum detection efficiency. In the spectrum of 57Co isotope, the limiting energy resolution has been achieved.

  17. Effects of Post Annealing on I-V-T Characteristics of (Ni/Au)/Al0.09Ga0.91N Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Akkaya, Abdullah; Ayyıldız, Enise

    2016-04-01

    Post annealing is a simple, effective and suitable method for improving the diode parameters, especially when the used chemically stable substrates like Si, III-N and ternary alloys. In our work, we were applied this method to (Ni/Au)/Al0.09Ga0.91N Schottky Barrier Diodes (SBDs) and investigated by temperature-dependent current-voltage (I-V-T) characteristics at optimum conditions. Optimum annealing temperature was 600°C, which it’s determined with respect to have a highest barrier height value. The temperature-dependent electrical characteristics of the annealed at 600°C (Ni/Au)/Al0.09Ga0.91N SBDs were investigated in the wide temperature range of 95-315K. The diode parameters such as ideality factor (n) and Schottky barrier height (Фb0) were obtained to be strongly temperature dependent. The observed variation in Фb0 and n can be attributed to the spatial barrier inhomogeneities in Schottky barrier height by assuming a triple Gaussian distribution (TGD) of barrier heights (BHs) at 95-145K, 145-230K and 230-315K. The modified Richardson plots and T0 analysis was performed to provide an experimental Richardson constants and bias coefficients of the mean barrier height. Furthermore, the chemical composition of the contacts was examined by the XPS depth profile analysis.

  18. RF-to-DC Characteristics of Direct Irradiated On-Chip Gallium Arsenide Schottky Diode and Antenna for Application in Proximity Communication System

    PubMed Central

    Mustafa, Farahiyah; Hashim, Abdul Manaf

    2014-01-01

    We report the RF-to-DC characteristics of the integrated AlGaAs/GaAs Schottky diode and antenna under the direct injection and irradiation condition. The conversion efficiency up to 80% under direct injection of 1 GHz signal to the diode was achieved. It was found that the reduction of series resistance and parallel connection of diode and load tend to lead to the improvement of RF-to-DC conversion efficiency. Under direct irradiation from antenna-to-antenna method, the output voltage of 35 mV was still obtainable for the distance of 8 cm between both antennas in spite of large mismatch in the resonant frequency between the diode and the connected antenna. Higher output voltage in volt range is expected to be achievable for the well-matching condition. The proposed on-chip AlGaAs/GaAs HEMT Schottky diode and antenna seems to be a promising candidate to be used for application in proximity communication system as a wireless low power source as well as a highly sensitive RF detector. PMID:24561400

  19. RF-to-DC characteristics of direct irradiated on-chip gallium arsenide Schottky diode and antenna for application in proximity communication system.

    PubMed

    Mustafa, Farahiyah; Hashim, Abdul Manaf

    2014-02-20

    We report the RF-to-DC characteristics of the integrated AlGaAs/GaAs Schottky diode and antenna under the direct injection and irradiation condition. The conversion efficiency up to 80% under direct injection of 1 GHz signal to the diode was achieved. It was found that the reduction of series resistance and parallel connection of diode and load tend to lead to the improvement of RF-to-DC conversion efficiency. Under direct irradiation from antenna-to-antenna method, the output voltage of 35 mV was still obtainable for the distance of 8 cm between both antennas in spite of large mismatch in the resonant frequency between the diode and the connected antenna. Higher output voltage in volt range is expected to be achievable for the well-matching condition. The proposed on-chip AlGaAs/GaAs HEMT Schottky diode and antenna seems to be a promising candidate to be used for application in proximity communication system as a wireless low power source as well as a highly sensitive RF detector.

  20. On the electrical characteristics of Au/n-type GaAs Schottky diode

    NASA Astrophysics Data System (ADS)

    Mamor, M.; Bouziane, K.; Tirbiyine, A.; Alhamrashdi, H.

    2014-08-01

    The temperature dependence of the electrical properties of Au/n-type GaAs Schottky contacts have been studied using current-voltage (I-V) and capacitance-voltage (C-V) over a wide temperature range 100-300 K. In the low temperature range 100-140 K, the absence of temperature dependent tunneling parameters has been explained in terms of thermionic field emission. In the high temperature range 140-300 K, the zero-bias barrier height (Φ0bn) was found to decrease and the ideality factor (n) to increase with decreasing temperature. This abnormal temperature dependence of Φ0bn and n is interpreted on the basis of a thermionic emission mechanism by considering the existence of the barrier height inhomogeneities (BHi) at the metal/GaAs interface. From the linear plot of the experimental Schottky barrier height (SBH) vs. 1/T based on the BHi model, the value of the homogeneous SBH (Φ‾0bn) of 1.03 eV and a zero-bias standard deviation (σ0s) of 89 meV were computed. Furthermore the modified Richardson plot according to the Gaussian distribution model resulted in a homogeneous SBH (Φ‾0bn) of 1.02 eV and a Richardson constant (A*) of 7.97 A/cm2 K2, respectively. The value of A* obtained from this plot is in very close agreement with the theoretical reported value of 8.16 A/cm2 K2 for n-type GaAs.

  1. Properties of homoepitaxial 4H-SiC and characteristics of Ti/4H-SiC Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Chen, G.; Li, Z. Y.; Bai, S.; Han, P.

    2008-02-01

    This paper describes the properties of the homoepitaxial 4H-SiC layer, the fabrication and electrical parameters of Ti/4H-SiC Schottky barrier diode (SBD). The 4H-SiC epitaxial layers, grown on the commercially available 8°off-oriented Si-face(0001) single-crystal 4H-SiC wafers, have been performed at 1550~1600°C by using the step controlled epitaxy with low pressure chemical vapor deposition. X-ray diffraction measurement result indicates the single crystal nature of the epilayer, and Raman spectrum shows the typical 4H-SiC feature peaks. When the off-oriented angle of substrate is 8°, the epitaxial growth perfectly replicates the substrate's polytype. High quality 4H-SiC epilayer has been generated on the 4H-SiC substrate. Ti/4H-SiC SBDs with blocking voltage 1kV have been made on an undoped epilayer with 12um in thick and 3×10 15cm -3 in carrier density. The ideality factor n=1.16 and the effective barrier height φ e=0.9V of the Ti/4H-SiC SBDs are measured with method of forward density-voltage (J-V). The diode rectification ratio of forward to reverse (defined at +/-1V) is over 10 7 at room temperature. By using B + implantation, an amorphous layer as the edge termination is formed. The SBDs have on-state current density of 200A/cm2 at a forward voltage drop of about 2V. The specific on-resistance for the rectifier is found to be as 6.6mΩ•cm2.

  2. The Current-Voltage Characteristics of the Au/MBEn-GaAs Schottky Diodes in a Wide Temperature Range

    NASA Astrophysics Data System (ADS)

    EfeoǦLU, Hasan; Turut, Abdulmecit

    2013-07-01

    The Au/MBEn-GaAs Schottky diodes have been fabricated by us. The slope of the conventional ln(I0/T2) versus (kT)-1 plotted in the temperature range of 120-350 K has given a Richardson constant (RC) of 7.69 A (cmK)-2 which is in close agreement with the value of 8.16 A/cm2K2 known for n-type GaAs. The barrier height (BH) value in 40-160 K range has decreased obeying to Gaussian distribution (GD) model of the BH based on thermionic emission current theory. The modified RC plot according to the GD model has given a RC value of 2.45 A (cmK)-2 or a value of 2.38 A (cmK)-2 by taking into account the temperature dependence of the standard deviation. Therefore, we have modified the Richardson's plot using the temperature dependent values of the effective area of the patches introduced by lateral inhomogeneity of the BHs and we have obtained a RC value of 8.10 A (cmK)-2.

  3. Temperature dependent barrier height and ideality factor of electrodeposited n-CdSe/Cu Schottky barrier diode

    SciTech Connect

    Mahato, S. Shiwakoti, N.; Kar, A. K.

    2015-06-24

    This article reports the measurement of temperature-dependent barrier height and ideality factor of n-CdSe/Cu Schottky barrier diode. The Cadmium Selenide (CdSe) thin films have been deposited by simple electrodeposition technique. The XRD measurements ravels the deposited single phase CdSe films are highly oriented on (002) plane and the average particle size has been calculated to be ~18 nm. From SEM characterization, it is clear that the surface of CdSe thin films are continuous, homogeneous and the film is well adhered to the substrate and consists of fine grains which are irregular in shape and size. Current-Voltage characteristics have been measured at different temperatures in the range (298 K – 353 K). The barrier height and ideality factor are found to be strongly temperature dependent. The inhomogenious barrier height increases and ideality factor decreases with increase in temperature. The expectation value has been calculated and its value is 0.30 eV.

  4. The effect of annealing temperature on the electrical characterization of Co/n type GaP Schottky diode

    SciTech Connect

    Orak, İ.; Ejderha, K.; Sönmez, E.; Alanyalıoğlu, M.; Turut, A.

    2015-01-15

    The Co/n-GaP nano-Schottky diodes have been fabricated to investigate effect of annealing temperature on the characteristics of the device. DC Magnetron sputtering technique has been used for Co metallic contact. The samples have been annealed for three minutes at 400 °C and 600 °C. XRD analyzes of the devices subjected to thermal annealing process have been investigated. Surface images have been taken with atomic force microscopy (AFM) in order to examine the morphology of the surface of the metal layer before and after the annealing the sample. The current–voltage (I–V) measurements taken at room temperature have shown that the ideality factor and series resistance decrease with the increasing annealing temperature. The ideality factor was found to be 1.02 for sample annealed at 400 °C. Before and after annealing, depending on the temperature measurement, the capacitance–frequency (C–f), and conductance–frequency (G–f) have been measured, and graphs have been plotted.

  5. Electric field modulation technique for high-voltage AlGaN/GaN Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Tang, Cen; Xie, Gang; Zhang, Li; Guo, Qing; Wang, Tao; Sheng, Kuang

    2013-10-01

    A novel structure of AlGaN/GaN Schottky barrier diode (SBD) featuring electric field optimization techniques of anode-connected-field-plate (AFP) and magnesium-doped p-type buried layer under the two-dimensional electron gas (2DEG) channel is proposed. In comparison with conventional AlGaN/GaN SBDs, the magnesium-doped p-type buried layer in the proposed structure can provide holes that can help to deplete the surface 2DEG. As a result, surface field strength around the electrode edges is significantly suppressed and the electric field along the channel is distributed more evenly. Through 2D numerical analysis, the AFP parameters (field plate length, LAFP, and field plate height, TAFP) and p-type buried layer parameters (p-type layer concentration, NP, and p-type layer thickness, TP) are optimized to achieve a three-equal-peak surface channel field distribution under exact charge balance conditions. A novel structure with a total drift region length of 10.5 μm and a magnesium-doped p-type concentration of 1 × 1017 cm-3 achieves a high breakdown voltage (VB) of 1.8 kV, showing 5 times improvement compared with the conventional SBD with the same device dimension.

  6. SiC Schottky Diode Detectors for Measurement of Actinide Concentrations from Alpha Activities in Molten Salt Electrolyte

    SciTech Connect

    Windl, Wolfgang; Blue, Thomas

    2013-01-28

    In this project, we have designed a 4H-SiC Schottky diode detector device in order to monitor actinide concentrations in extreme environments, such as present in pyroprocessing of spent fuel. For the first time, we have demonstrated high temperature operation of such a device up to 500 °C in successfully detecting alpha particles. We have used Am-241 as an alpha source for our laboratory experiments. Along with the experiments, we have developed a multiscale model to study the phenomena controlling the device behavior and to be able to predict the device performance. Our multiscale model consists of ab initio modeling to understand defect energetics and their effect on electronic structure and carrier mobility in the material. Further, we have developed the basis for a damage evolution model incorporating the outputs from ab initio model in order to predict respective defect concentrations in the device material. Finally, a fully equipped TCAD-based device model has been developed to study the phenomena controlling the device behavior. Using this model, we have proven our concept that the detector is capable of performing alpha detection in a salt bath with the mixtures of actinides present in a pyroprocessing environment.

  7. Broadband terahertz-wave detector implementing zero-biased InGaAsP Schottky-barrier diode

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi

    2015-05-01

    This paper describes two types of terahertz-wave detector modules implementing a zero-biased InGaAsP Schottky barrier diode (SBD). A SBD was monolithically integrated with a short-stub resonant matching circuit for increasing the detection sensitivity, and assembled in a compact J-band (WR-3) rectangular-waveguide-input module. The module could detect signals at frequencies from 200 to 500 GHz, and its sensitivity peaked at 1460 V/W around 350 GHz, which is a record value for the InP-based zero-biased SBD. A polarization-sensitive sub-terahertz-wave detector was also developed by integrating a SBD and an extended bowtie antenna. The fabricated quasi-optical module could detect signals at frequencies ranging from 30 GHz to 1 THz at zero bias. The principal-polarization-axis angle for signal detection was stable within +/-1.5° at frequencies from 80 to 600 GHz, while the degree of polarization was more than 95%.

  8. Forward-bias diode parameters, electronic noise, and photoresponse of graphene/silicon Schottky junctions with an interfacial native oxide layer

    NASA Astrophysics Data System (ADS)

    An, Yanbin; Behnam, Ashkan; Pop, Eric; Bosman, Gijs; Ural, Ant

    2015-09-01

    Metal-semiconductor Schottky junction devices composed of chemical vapor deposition grown monolayer graphene on p-type silicon substrates are fabricated and characterized. Important diode parameters, such as the Schottky barrier height, ideality factor, and series resistance, are extracted from forward bias current-voltage characteristics using a previously established method modified to take into account the interfacial native oxide layer present at the graphene/silicon junction. It is found that the ideality factor can be substantially increased by the presence of the interfacial oxide layer. Furthermore, low frequency noise of graphene/silicon Schottky junctions under both forward and reverse bias is characterized. The noise is found to be 1/f dominated and the shot noise contribution is found to be negligible. The dependence of the 1/f noise on the forward and reverse current is also investigated. Finally, the photoresponse of graphene/silicon Schottky junctions is studied. The devices exhibit a peak responsivity of around 0.13 A/W and an external quantum efficiency higher than 25%. From the photoresponse and noise measurements, the bandwidth is extracted to be ˜1 kHz and the normalized detectivity is calculated to be 1.2 ×109 cm Hz1/2 W-1. These results provide important insights for the future integration of graphene with silicon device technology.

  9. Temperature-Dependent Current-Voltage (I-V) and Capacitance-Voltage (C-V) Characteristics of Ni/Cu/n-InP Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Munikrishana Reddy, Y.; Nagaraj, M. K.; Siva Pratap Reddy, M.; Lee, Jung-Hee; Rajagopal Reddy, V.

    2013-04-01

    The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Ni/Cu/n-InP Schottky barrier diodes are studied over a wide temperature range, from 210 K to 420 K. The I-V characteristics display anomalous thermal behavior. The apparent barrier height decays, and the ideality factor grows at low temperatures, and the series resistances resulting from Cheung's and Norde's procedures are markedly temperature dependent. The nonlinearity of the Richardson plot and the strong temperature dependence of the Schottky-barrier parameters indicate that the interface is spatially inhomogeneous. Plots of the zero-bias barrier height as a function of 1/(2kT) points to a Gaussian distribution of barrier heights with 0.90 eV mean height and 0.014 eV standard deviation. When this distribution is accounted for, a Richardson of 6.5 A/(cm K)2 results, relatively close to the 9.4/(cm K)2 predicted by theory. We conclude that, combined with a Gaussian distribution of barrier heights, the thermionic-emission mechanism explains the temperature-dependent I-V and C-V characteristics of the studied Schottky-barrier diodes.

  10. Analysis of Schottky Contact Formation in Coplanar Au/ZnO/Al Nanogap Radio Frequency Diodes Processed from Solution at Low Temperature.

    PubMed

    Semple, James; Rossbauer, Stephan; Anthopoulos, Thomas D

    2016-09-01

    Much work has been carried out in recent years in fabricating and studying the Schottky contact formed between various metals and the n-type wide bandgap semiconductor zinc oxide (ZnO). In spite of significant progress, reliable formation of such technologically interesting contacts remains a challenge. Here, we report on solution-processed ZnO Schottky diodes based on a coplanar Al/ZnO/Au nanogap architecture and study the nature of the rectifying contact formed at the ZnO/Au interface. Resultant diodes exhibit excellent operating characteristics, including low-operating voltages (±2.5 V) and exceptionally high current rectification ratios of >10(6) that can be independently tuned via scaling of the nanogap's width. The barrier height for electron injection responsible for the rectifying behavior is studied using current-voltage-temperature and capacitance-voltage measurements (C-V) yielding values in the range of 0.54-0.89 eV. C-V measurements also show that electron traps present at the Au/ZnO interface appear to become less significant at higher frequencies, hence making the diodes particularly attractive for high-frequency applications. Finally, an alternative method for calculating the Richardson constant is presented yielding a value of 38.9 A cm(-2) K(-2), which is close to the theoretically predicted value of 32 A cm(-2) K(-2). The implications of the obtained results for the use of these coplanar Schottky diodes in radio frequency applications is discussed. PMID:27530144

  11. Analysis of Schottky Contact Formation in Coplanar Au/ZnO/Al Nanogap Radio Frequency Diodes Processed from Solution at Low Temperature.

    PubMed

    Semple, James; Rossbauer, Stephan; Anthopoulos, Thomas D

    2016-09-01

    Much work has been carried out in recent years in fabricating and studying the Schottky contact formed between various metals and the n-type wide bandgap semiconductor zinc oxide (ZnO). In spite of significant progress, reliable formation of such technologically interesting contacts remains a challenge. Here, we report on solution-processed ZnO Schottky diodes based on a coplanar Al/ZnO/Au nanogap architecture and study the nature of the rectifying contact formed at the ZnO/Au interface. Resultant diodes exhibit excellent operating characteristics, including low-operating voltages (±2.5 V) and exceptionally high current rectification ratios of >10(6) that can be independently tuned via scaling of the nanogap's width. The barrier height for electron injection responsible for the rectifying behavior is studied using current-voltage-temperature and capacitance-voltage measurements (C-V) yielding values in the range of 0.54-0.89 eV. C-V measurements also show that electron traps present at the Au/ZnO interface appear to become less significant at higher frequencies, hence making the diodes particularly attractive for high-frequency applications. Finally, an alternative method for calculating the Richardson constant is presented yielding a value of 38.9 A cm(-2) K(-2), which is close to the theoretically predicted value of 32 A cm(-2) K(-2). The implications of the obtained results for the use of these coplanar Schottky diodes in radio frequency applications is discussed.

  12. (In,Sn)2O3/TiO2/Pt Schottky-type diode switch for the TiO2 resistive switching memory array

    NASA Astrophysics Data System (ADS)

    Shin, Yong Cheol; Song, Jaewon; Kim, Kyung Min; Choi, Byung Joon; Choi, Seol; Lee, Hyun Ju; Kim, Gun Hwan; Eom, Taeyong; Hwang, Cheol Seong

    2008-04-01

    A Schottky-type diode switch consisting of a Pt /(In,Sn)2O3/TiO2/Pt stack was fabricated for applications to cross-bar type resistive-switching memory arrays. The high (0.55eV) and low potential barrier at the TiO2/Pt and TiO2/(In,Sn)2O3 junctions, respectively, constitute the rectifying properties of the stacked structure. The forward/reverse current ratio was as high as ˜1.6×104 at an applied voltage of ˜1V. When Pt /TiO2/Pt memory was connected to this diode in series, there was an insignificant interference on the memory function from the diode under the forward bias and virtually no resistive switching under a reverse bias.

  13. Roles of lightly doped carbon in the drift layers of vertical n-GaN Schottky diode structures on freestanding GaN substrates

    NASA Astrophysics Data System (ADS)

    Tanaka, Takeshi; Kaneda, Naoki; Mishima, Tomoyoshi; Kihara, Yuhei; Aoki, Toshichika; Shiojima, Kenji

    2015-04-01

    We studied the roles of lightly doped carbon in a series of n-GaN Schottky diode epitaxial structures on freestanding GaN substrates, and evaluated the effects of the doping on diode performances. A large variation of compensation ratio was observed for carbon doping at (1-2) × 1016 cm-3. A model was proposed to explain this phenomenon, in which a vulnerable balance between donor-type CGa and deep acceptor CN strongly affected the free-carrier generation. Application of Norde plots and reverse biased leakage current in current-voltage measurements suggested provisional optimization for a free-carrier concentration of 8 × 1015 cm-3 to achieve a tradeoff between breakdown voltage and on-resistance of the n-GaN diodes.

  14. The Effect of Etching Time on Rectifying Characteristic in SnO2/p-Si and SnO2/p-PoSi Heterojunction Schottky Diodes

    NASA Astrophysics Data System (ADS)

    Biaram, Alireza; Eshghi, Hosein

    2013-03-01

    We have fabricated SnO2/p-Si and SnO2/p-PoSi heterojunction diodes by spray pyrolysis method. To prepare porous Si substrates, the etching time was varied from 10 to 20 and 30 mins. In these samples, the SEM micrographs showed a distributed pore areas surrounded by columnar walls with various height. The data analysis of the rectified I-V characteristic, using thermionic emission Schottky diode theory, showed that although the barrier height is about 0.5-0.6 eV in all samples other two important diode parameters, i.e. the ideality factor n and the series resistance rs, are strongly etching time-dependant and are increased with increasing the etching time.

  15. Dynamics of modification of Ni/n-GaN Schottky barrier diodes irradiated at low temperature by 200 MeV Ag{sup 14+} ions

    SciTech Connect

    Kumar, Ashish; Kumar, Tanuj; Kanjilal, D.; Hähnel, A.; Singh, R.

    2014-01-20

    Ni/GaN Schottky barrier diodes were irradiated with 200 MeV Ag ions up to fluence of 1 × 10{sup 11} ions/cm{sup 2} at the substrate temperature of 80 K. Post-irradiation current-voltage measurements showed that the ideality factor, n increased and the reverse leakage current, I{sub R} decreased with increase in fluence. But Schottky barrier height, ϕ{sub b} increased only marginally with increase in ion fluence. In situ resistivity measurements showed orders of magnitude increase in resistivity of GaN epitaxial film with irradiation fluence. Cross-sectional transmission electron microscopy images revealed the presence of defect clusters in bulk GaN after irradiation.

  16. Phase transition induced double-Gaussian barrier height distribution in Schottky diode

    NASA Astrophysics Data System (ADS)

    Bobby, A.; Verma, S.; Asokan, K.; Sarun, P. M.; Antony, B. K.

    2013-12-01

    The charge transport mechanisms of Hg contact on n-type silicon crystal having <1 0 0> orientation were investigated in the temperature range of 160-293 K by the thermionic emission theory. The temperature variation of barrier height and ideality factor illustrates an inhomogeneous interface with a Gaussian barrier height distribution. The plots of temperature dependent zero-bias barrier height, ideality factor, series resistance and reverse leakage current show a discontinuity below 240 K. The experimental barrier height and ideality factor versus 1/T plot gives two slopes, one in the 160-220 K region and the other in the 240-293 K region, thereby revealing a double Gaussian distribution of barrier heights. The observed discontinuity in the diode parameters and the existence of double Gaussian barrier heights are interpreted on the basis of phase transition of mercury from its liquid state to solid form.

  17. The Richardson constant and barrier inhomogeneity at Au/Si3N4/n-Si (MIS) Schottky diodes

    NASA Astrophysics Data System (ADS)

    Tataroğlu, A.; Pür, F. Z.

    2013-07-01

    Si3N4 films were deposited on n-type silicon substrate by the radio frequency magnetron sputtering technique. The current-voltage (I-V) characteristics of Au/Si3N4/n-Si (metal-insulator-semiconductor) Schottky diodes were investigated in the temperature range of 160-400 K. Experimental results show an abnormal increase in the zero-bias barrier height (BH) (ΦBo) and a decrease in the ideality factor (n) with increasing temperature. This behavior is attributed to barrier inhomogeneities by assuming a Gaussian distribution (GD) of BHs. The conventional Richardson plot (ln(Io/T2) versus 1000/T) exhibits a linearity above about 300 K. The values of activation energy (Ea) and Richardson constant (A*) were found to be 0.350 eV and 1.242 × 10-3 A cm-2 K-2 from the slope and the intercept at the ordinate of the linear region of this plot, respectively. Also, we attempted to draw a ΦBo versus q/2kT plot to determine evidence of the GD of BHs, and the values of \\bar \\Phi _{{\\rm{Bo}}} = 0.999\\,{\\rm{eV}} and σs = 0.137 eV for the mean BH and zero-bias standard deviation, respectively, were obtained from this plot; then, a modified ln(Io/T2) - q2σs2/2k2T2 versus q/kT plot gives \\bar \\Phi _{{\\rm{Bo}}} and A* as 0.992 eV and 108.228 A cm-2 K-2, respectively. This value of A* is very close to the theoretical value of 112 A cm-2 K-2 for n-type Si.

  18. Investigation of 1/f Noise and Superimposed RTS Noise in Ti-Au/n-Type GaAs Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Klyuev, Alexey V.; Yakimov, Arkady V.

    2015-10-01

    Low frequency noise characteristics of Schottky diodes are investigated. Two noise components were found in experimental noise records: random telegraph signal (RTS), caused by burst noise, and 1/f Gaussian noise. The noise is sampled and recorded on a PC. Then, in addition to the spectrum, the probability density function (pdf) of the total noise is analyzed. In the case of the mixture of the burst noise and Gaussian (1/f) noise, the pdf has two maxima separated by a local minimum. Extraction of burst noise component from Gaussian noise background was performed using the pdf, standard signal detection theory, and advanced signal-processing techniques. It is concluded that the RTS noise and 1/f noise have different physical origins in Schottky diodes. The raw noise is split into two components. One appeared to be burst noise with a Lorentzian-like spectral shape. The other component is 1/f noise. Having extracted 1/f noise, we have studied the dependence of noise spectral values on the current across the diode.

  19. I-V characteristics of high-voltage 4H-SiC diodes with a 1.1-eV Schottky barrier

    SciTech Connect

    Ivanov, P. A. Grekhov, I. V.; Kon'kov, O. I.; Potapov, A. S.; Samsonova, T. P.; Semenov, T. V.

    2011-10-15

    The I-V characteristics of high-voltage 4H-SiC diodes with a Schottky barrier {approx}1.1 eV in height are measured and analyzed. The forward I-V characteristics proved to be close to 'ideal' in the temperature range of 295-470 K. The reverse I-V characteristics are adequately described by the model of thermionic emission at the voltages to 2 kV in the temperature range of 361-470 K if, additionally, a barrier lowering with an increase in the band bending in the semiconductor is taken into account.

  20. Gaussian distribution of inhomogeneous barrier height in Al/SiO2/p-Si Schottky diodes

    NASA Astrophysics Data System (ADS)

    Yıldız, D. E.; Altındal, Ş.; Kanbur, H.

    2008-06-01

    The forward and reverse bias current-voltage (I-V) characteristics of Al/SiO2/p-Si (metal-insulator-semiconductor) type Schottky diodes (SDs) were measured in the temperature range of 200-400 K. Evaluation of the experimental I-V data reveals a decrease in ΦB0 and Rs but an increase in n, with a decrease in temperature. To explain this behavior of ΦB0 with temperature, we have reported a modification which included n and the tunneling parameter αχ1/2δ in the expression of reverse saturation current I0. Thus, a corrected effective barrier height ΦB eff(I -V) vs T has a negative temperature coefficient (α ≈-5×10-4 eV/K), and it is in good agreement with α=-4.73×10-4 eV/K of Si band gap. Such behavior of Rs estimated from Cheung's method could be expected for semiconductors in the temperature region, where there is no carrier freezing out, which is non-negligible at low temperatures. Also, there is a linear correlation between ΦB0(I -V) and n due to the inhomogeneities of the barrier heights (BHs). The conventional activation energy (Ea) plot exhibits nonlinearity below 320 K with the linear portion corresponding to Ea of 0.275 eV. An A∗ value of 1.45×10-5 A cm-2 K-2,which is much lower than the known value of 32 A cm-2 K-2 for p-type Si, is determined from the intercept at the ordinate of this experimental plot. Such behavior is attributed to Schottky barrier inhomogeneities by assuming a Gaussian distribution (GD) of BHs due to BH inhomogeneities that prevail at the interface. We attempted to draw a ΦB0 vs q /2kT plot to obtain evidence of a GD of the BHs, and the values of Φ¯B0=1.136 eV and σ0=0.159 V for the mean BH and standard deviation at zero bias have been obtained from this plot. Therefore, the modified ln (I0/T2)-q2σ02/2k2T2 vs q /kT plot gives Φ¯B0 and A∗ values of 1.138 eV and 37.23 A cm-2 K-2, respectively, without using the temperature coefficient of the BH. This A∗ value of 37.23 A cm-2 K-2 is very close to the theoretical

  1. Growth and Characterization of CuO Nanostructures on Si for the Fabrication of CuO/p-Si Schottky Diodes

    PubMed Central

    Çetinkaya, S.; Çetinkara, H. A.; Bayansal, F.; Kahraman, S.

    2013-01-01

    CuO interlayers in the CuO/p-Si Schottky diodes were fabricated by using CBD and sol-gel methods. Deposited CuO layers were characterized by SEM and XRD techniques. From the SEM images, it was seen that the film grown by CBD method is denser than the film grown by sol-gel method. This result is compatible with XRD results which show that the crystallization in CBD method is higher than it is in sol-gel method. For the electrical investigations, current-voltage characteristics of the diodes have been studied at room temperature. Conventional I-V and Norde's methods were used in order to determine the ideality factor, barrier height, and series resistance values. It was seen that the morphological and structural analysis are compatible with the results of electrical investigations. PMID:23766670

  2. The explanation of barrier height inhomogeneities in Au/n-Si Schottky barrier diodes with organic thin interfacial layer

    NASA Astrophysics Data System (ADS)

    Taşçıoǧlu, Ilke; Aydemir, Umut; Altındal, Şemsettin

    2010-09-01

    The forward bias current-voltage (I-V) characteristics of Au/n-Si Schottky barrier diodes (SBDs) with Zn doped poly(vinyl alcohol) (PVA:Zn) interfacial layer have been investigated in the wide temperature range of 80-400 K. The conventional Richardson plot of the ln(Io/T2) versus q /kT has two linear regions: the first region (200-400 K) and the second region (80-170 K). The values of activation energy (Ea) and Richardson constant (A∗) were obtained from this plot and especially the values of A∗ are much lower than the known theoretical value for n-type Si. Also the value of Ea is almost equal to the half of the band gap energy of Si. Therefore, the Φap versus q /2kT plot was drawn to obtain the evidence of a Gaussian distribution (GD) of barrier heights (BHs) and it shows two linear region similar to ln(Io)/T2 versus q /kT plot. The analysis of I-V data based on thermionic emission of the Au/PVA:Zn/n-Si SBDs has revealed the existence of double GD with mean BH values (Φ¯B0) of 1.06 eV and 0.86 eV with standard deviation (σ ) of 0.110 eV and 0.087 V, respectively. Thus, we modified ln(Io/T2)-(qσ)2/2(kT)2 versus q /kT plot for two temperature regions (200-400 K and 80-170 K) and it gives renewed mean BHs Φ¯B0 values as 1.06 eV and 0.85 eV with Richardson constant (A∗) values 121 A/cm2 K2 and 80.4 A/cm2 K2, respectively. This obtained value of A∗=121 A/cm2 K2 is very close to the known theoretical value of 120 A/cm2 K2 for n-type Si.

  3. Spectroscopic properties and radiation damage investigation of a diamond based Schottky diode for ion-beam therapy microdosimetry

    NASA Astrophysics Data System (ADS)

    Verona, C.; Magrin, G.; Solevi, P.; Grilj, V.; Jakšić, M.; Mayer, R.; Marinelli, Marco; Verona-Rinati, G.

    2015-11-01

    In this work, a detailed analysis of the properties of a novel microdosimeter based on a synthetic single crystal diamond is reported. Focused ion microbeams were used to investigate the device spectropscopic properties as well as the induced radiation damage effects. A diamond based Schottky diode was fabricated by chemical vapor deposition with a very thin detecting region, about 400 nm thick (approximately 1.4 μm water equivalent thickness), corresponding to the typical size in microdosimetric measurements. A 200 × 200 μm2 square metallic contact was patterned on the diamond surface by standard photolithography to define the sensitive area. Experimental measurements were carried out at the Ruder Bo\\vskovic' Institute microbeam facility using 4 MeV carbon and 5 MeV silicon ions. Ion beam induced charge maps were employed to characterize the microdosimeter response in terms of its charge collection properties. A stable response with no evidence of polarization or memory effects was observed up to the maximum investigated ion beam flux of about 1.7 × 109 ions.cm-2.s-1. A homogeneity of the response about 6% was found over the sensitive region with a well-defined confinement of the response within the active area. Tests of the radiation damage effect were performed by selectively irradiating small areas of the device with different ion fluences, up to about 1012 ions/cm2. An exponential decrease of the charge collection efficiency was observed with a characteristic decay constant of about 4.8 MGy and 1 MGy for C and Si ions, respectively. The experimental data were analyzed by means of GEANT4 Monte Carlo simulations. A direct correlation between the diamond damaging effect and the Non Ionizing Energy Loss (NIEL) fraction was found. In particular, an exponential decay of the charge collection efficiency with an exponential decay as a function of NIEL is observed, with a characteristic constant of about 9.3 kGy-NIEL for both carbon and silicon ions.

  4. Spectroscopic properties and radiation damage investigation of a diamond based Schottky diode for ion-beam therapy microdosimetry

    SciTech Connect

    Verona, C.; Marinelli, Marco; Verona-Rinati, G.; Magrin, G.; Solevi, P.; Mayer, R.; Grilj, V.; Jakšić, M.

    2015-11-14

    In this work, a detailed analysis of the properties of a novel microdosimeter based on a synthetic single crystal diamond is reported. Focused ion microbeams were used to investigate the device spectropscopic properties as well as the induced radiation damage effects. A diamond based Schottky diode was fabricated by chemical vapor deposition with a very thin detecting region, about 400 nm thick (approximately 1.4 μm water equivalent thickness), corresponding to the typical size in microdosimetric measurements. A 200 × 200 μm{sup 2} square metallic contact was patterned on the diamond surface by standard photolithography to define the sensitive area. Experimental measurements were carried out at the Ruder Boškovic′ Institute microbeam facility using 4 MeV carbon and 5 MeV silicon ions. Ion beam induced charge maps were employed to characterize the microdosimeter response in terms of its charge collection properties. A stable response with no evidence of polarization or memory effects was observed up to the maximum investigated ion beam flux of about 1.7 × 10{sup 9} ions·cm{sup −2}·s{sup −1}. A homogeneity of the response about 6% was found over the sensitive region with a well-defined confinement of the response within the active area. Tests of the radiation damage effect were performed by selectively irradiating small areas of the device with different ion fluences, up to about 10{sup 12} ions/cm{sup 2}. An exponential decrease of the charge collection efficiency was observed with a characteristic decay constant of about 4.8 MGy and 1 MGy for C and Si ions, respectively. The experimental data were analyzed by means of GEANT4 Monte Carlo simulations. A direct correlation between the diamond damaging effect and the Non Ionizing Energy Loss (NIEL) fraction was found. In particular, an exponential decay of the charge collection efficiency with an exponential decay as a function of NIEL is observed, with a characteristic constant of about

  5. Analysis of temperature-dependant current-voltage characteristics and extraction of series resistance in Pd/ZnO Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Mayimele, M. A.; van Rensburg, J. P. Janse; Auret, F. D.; Diale, M.

    2016-01-01

    We report on the analysis of current voltage (I-V) measurements performed on Pd/ZnO Schottky barrier diodes (SBDs) in the 80-320 K temperature range. Assuming thermionic emission (TE) theory, the forward bias I-V characteristics were analysed to extract Pd/ZnO Schottky diode parameters. Comparing Cheung's method in the extraction of the series resistance with Ohm's law, it was observed that at lower temperatures (T<180 K) the series resistance decreased with increasing temperature, the absolute minimum was reached near 180 K and increases linearly with temperature at high temperatures (T>200 K). The barrier height and the ideality factor decreased and increased, respectively, with decrease in temperature, attributed to the existence of barrier height inhomogeneity. Such inhomogeneity was explained based on TE with the assumption of Gaussian distribution of barrier heights with a mean barrier height of 0.99 eV and a standard deviation of 0.02 eV. A mean barrier height of 0.11 eV and Richardson constant value of 37 A cm-2 K-2 were determined from the modified Richardson plot that considers the Gaussian distribution of barrier heights.

  6. Comparative study of the electrical properties of Au/n-Si (MS) and Au/Si3N4/n-Si (MIS) Schottky diodes

    NASA Astrophysics Data System (ADS)

    Adem, Tataroğlu

    2013-06-01

    In this paper, the electrical parameters of Au/n-Si (MS) and Au/Si3N4/n-Si (MIS) Schottky diodes are obtained from the forward bias current—voltage (I—V) and capacitance—voltage (C—V) measurements at room temperature. Experimental results show that the rectifying ratios of the MS and MIS diodes at ± 5 V are found to be 1.25 × 103 and 1.27 × 104, respectively. The main electrical parameters of the MS and MIS diodes, such as the zero-bias barrier height (ΦBo) and ideality factor (n), are calculated to be 0.51 eV (I—V), 0.53 eV (C—V), and 4.43, and 0.65 eV (I—V), 0.70 eV (C—V), and 3.44, respectively. In addition, the energy density distribution profile of the interface states (Nss) is obtained from the forward bias I—V, and the series resistance (Rs) values for the two diodes are calculated from Cheung's method and Ohm's law.

  7. Nano-scale NiSi and n-type silicon based Schottky barrier diode as a near infra-red detector for room temperature operation

    SciTech Connect

    Roy, S.; Midya, K.; Duttagupta, S. P.; Ramakrishnan, D.

    2014-09-28

    The fabrication of nano-scale NiSi/n-Si Schottky barrier diode by rapid thermal annealing process is reported. The characterization of the nano-scale NiSi film was performed using Micro-Raman Spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The thickness of the film (27 nm) has been measured by cross-sectional Secondary Electron Microscopy and XPS based depth profile method. Current–voltage (I–V) characteristics show an excellent rectification ratio (I{sub ON}/I{sub OFF} = 10⁵) at a bias voltage of ±1 V. The diode ideality factor is 1.28. The barrier height was also determined independently based on I–V (0.62 eV) and high frequency capacitance–voltage technique (0.76 eV), and the correlation between them has explained. The diode photo-response was measured in the range of 1.35–2.5 μm under different reverse bias conditions (0.0–1.0 V). The response is observed to increase with increasing reverse bias. From the photo-responsivity study, the zero bias barrier height was determined to be 0.54 eV.

  8. Nano-scale NiSi and n-type silicon based Schottky barrier diode as a near infra-red detector for room temperature operation

    NASA Astrophysics Data System (ADS)

    Roy, S.; Midya, K.; Duttagupta, S. P.; Ramakrishnan, D.

    2014-09-01

    The fabrication of nano-scale NiSi/n-Si Schottky barrier diode by rapid thermal annealing process is reported. The characterization of the nano-scale NiSi film was performed using Micro-Raman Spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The thickness of the film (27 nm) has been measured by cross-sectional Secondary Electron Microscopy and XPS based depth profile method. Current-voltage (I-V) characteristics show an excellent rectification ratio (ION/IOFF = 105) at a bias voltage of ±1 V. The diode ideality factor is 1.28. The barrier height was also determined independently based on I-V (0.62 eV) and high frequency capacitance-voltage technique (0.76 eV), and the correlation between them has explained. The diode photo-response was measured in the range of 1.35-2.5 μm under different reverse bias conditions (0.0-1.0 V). The response is observed to increase with increasing reverse bias. From the photo-responsivity study, the zero bias barrier height was determined to be 0.54 eV.

  9. Analysis of temperature dependent forward characteristics of Ni/(\\bar{2}01) β-Ga2O3 Schottky diodes

    NASA Astrophysics Data System (ADS)

    Jayawardena, Asanka; Ahyi, Ayayi C.; Dhar, Sarit

    2016-11-01

    In this paper, the temperature dependence of the turn-on characteristics of Schottky barrier diodes fabricated on (\\bar{2}01) oriented n-type β-Ga2O3 is reported. The barrier height (qΦbn) and ideality factor (n) for Ni- β-Ga2O3 was found to be 1.08 ± 0.05 eV and 1.19 respectively at room temperature. The effective Richardson constant (A **) is determined to be 42.96 A cm-2 K-2, in close agreement with the theoretical value. At low temperatures (85-273 K), the current-voltage characteristics reveal a strong temperature dependence of Schottky barrier heights and ideality factors and a corresponding deviation from the barrier height extracted from capacitance-voltage measurements. A detailed analysis is presented, which suggest that these effects can be attributed to a large barrier inhomogeneity at metal/β-Ga2O3 interfaces, possibly resulting from interfacial defects, which can be modeled using a potential fluctuation model.

  10. Properties of Schottky Barrier Diodes on (In(x)Ga(1-x))₂O₃ for 0.01 ≤ x ≤ 0.85 Determined by a Combinatorial Approach.

    PubMed

    von Wenckstern, H; Splith, D; Werner, A; Müller, S; Lorenz, M; Grundmann, M

    2015-12-14

    We investigated properties of an (In(x)Ga(1-x))2O3 thin film with laterally varying cation composition that was realized by a large-area offset pulsed laser deposition approach. Within a two inch diameter thin film, the composition varies between 0.01 ≤ x ≤ 0.85, and three crystallographic phases (cubic, hexagonal, and monoclinic) were identified. We observed a correlation between characteristic parameters of Schottky barrier diodes fabricated on the thin film and its chemical and structural material properties. The highest Schottky barriers and rectification of the diodes were found for low indium contents. The thermal stability of the diodes is also best for Ga-rich parts of the sample. Conversely, the series resistance is lowest for large In content. Overall, the (In(x)Ga(1-x))2O3 alloy is well-suited for potential applications such as solar-blind photodetectors with a tunable absorption edge.

  11. An Integrated 520-600 GHz Sub-Harmonic Mixer and Tripler Combination Based on GaAs MMIC Membrane Planar Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Thomas, B.; Gill, J.; Maestrini, A.; Lee, C.; Lin, R.; Sin, S.; Peralta, A.; Mehdi, I.

    2011-01-01

    We present here the design, development and test of an integrated sub-millimeter front-end featuring a 520-600 GHz sub-harmonic mixer and a 260-300 GHz frequency tripler in a single cavity. Both devices used GaAs MMIC membrane planar Schottky diode technology. The sub-harmonic mixer/tripler circuit has been tested using conventional machined as well as silicon micro-machined blocks. Measurement results on the metal block give best DSB mixer noise temperature of 2360 K and conversion losses of 7.7 dB at 520 GHz. Preliminary results on the silicon micro-machined blocks give a DSB mixer noise temperature of 4860 K and conversion losses of 12.16 dB at 540 GHz. The LO input power required to pump the integrated tripler/sub-harmonic mixer for both packages is between 30 and 50 mW

  12. An Integrated 520-600 GHz Sub-Harmonic Mixer and Tripler Combination Based on GaAs MMIC Membrane Planar Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Thomas, B.; Gill, J.; Maestrini, A.; Lee, C.; Lin, R.; Sin, S.; Peralta, A.; Mehdi, I.

    2010-01-01

    We present here the design, development and test of an integrated sub-millimeter front-end featuring a 520-600 GHz sub-harmonic mixer and a 260-300 GHz frequency tripler in a single cavity. Both devices used GaAs MMIC membrane planar Schottky diode technology. The sub-harmonic mixer/tripler circuit has been tested using conventional machined as well as silicon micro-machined blocks. Measurement results on the metal block give best DSB mixer noise temperature of 2360 K and conversion losses of 7.7 dB at 520 GHz. Preliminary results on the silicon micro-machined blocks give a DSB mixer noise temperature of 4860 K and conversion losses of 12.16 dB at 540 GHz. The LO input power required to pump the integrated tripler/sub-harmonic mixer for both packages is between 30 and 50 mW.

  13. Increased effective barrier heights in Schottky diodes by molecular-beam epitaxy of CoSi2 and Ga-doped Si on Si(111)

    NASA Technical Reports Server (NTRS)

    Fathauer, R. W.; Lin, T. L.; Grunthaner, P. J.; Andersson, P. O.; Iannelli, J. M.

    1988-01-01

    Increasing the effective Schottky-barrier height of epitaxial CoSi2/Si(111) diodes by the use of thin, highly doped Si layers in close proximity to the metal-semiconductor interface has been studied. Intrinsic Si, Si doped by coevaporation of Ga, and epitaxial CoSi2 layers have all been grown in the same molecular-beam epitaxy system. Current-voltage and photoresponse characterization yield barrier heights ranging from 0.61 eV for a sample with no p(+) layer to 0.89 eV for a sample with a 20-nm-thick p(+) layer. These results are compared to theoretical values based on a one-dimensional solution of Poisson's equation under the depletion approximation.

  14. Schottky barrier diodes of corundum-structured gallium oxide showing on-resistance of 0.1 mΩ·cm2 grown by MIST EPITAXY®

    NASA Astrophysics Data System (ADS)

    Oda, Masaya; Tokuda, Rie; Kambara, Hitoshi; Tanikawa, Tomochika; Sasaki, Takahiro; Hitora, Toshimi

    2016-02-01

    Thin-film corundum-structured gallium oxide (α-Ga2O3) Schottky barrier diodes (SBDs) were fabricated by growing α-Ga2O3 layers on sapphire substrates by the safe, low-cost, and energy-saving MIST EPITAXY® technique, followed by lifting off the α-Ga2O3 layers from the substrates. The SBDs exhibited on-resistance and breakdown voltage of 0.1 mΩ·cm2 and 531 V (SBD1) or 0.4 mΩ·cm2 and 855 V (SBD2), respectively. These results will encourage the future evolution of low-cost and high-performance SBDs with α-Ga2O3.

  15. Frequency dependent negative capacitance effect and dielectric properties of swift heavy ion irradiated Ni/oxide/n-GaAs Schottky diode

    NASA Astrophysics Data System (ADS)

    Bobby, A.; Shiwakoti, N.; Verma, S.; Asokan, K.; Antony, B. K.

    2016-05-01

    The Ni/n-GaAs Schottky barrier diode having thin interfacial oxide layer was subjected to 25 MeV C4+ ion irradiation at selected fluences. The in-situ capacitance and dielectric properties were investigated in the 1 KHz to 5 MHz frequency range. The results show a decrease in capacitance with increase in ion fluence at low frequencies. Interestingly, a negative capacitance effect was also observed in this frequency range in all the samples. As a consequence, changes were observed in parameters like series resistance, conductance, dielectric loss, dielectric constant, loss tangent and ac electrical conductivity. At high frequencies, the capacitance reaches the geometric value 'C0'. The results were interpreted in terms of the generation of irradiation induced traps, carrier capture and emission from deep and shallow states and its frequency dependent saturation effects.

  16. CoPt ferromagnetic injector in light-emitting Schottky diodes based on InGaAs/GaAs nanostructures

    SciTech Connect

    Zdoroveyshchev, A. V. Dorokhin, M. V.; Demina, P. B.; Kudrin, A. V.; Vikhrova, O. V.; Ved’, M. V.; Danilov, Yu. A.; Erofeeva, I. V.; Krjukov, R. N.; Nikolichev, D. E.

    2015-12-15

    The possibility of fabricating a ferromagnetic injector based on a near-equiatomic CoPt alloy with pronounced perpendicular magnetization anisotropy in the InGaAs/GaAs spin light-emitting diode is shown. The physical properties of experimental spin light-emitting diode prototypes are comprehensively studied. Circularly polarized electroluminescence of fabricated diodes is obtained in zero magnetic field due to the remanent magnetization of CoPt layers.

  17. Illumination Dependent Admittance Characteristics of Au/Zinc Acetate Doped Polyvinyl Alcohol (PVA:Zn)/n-Si Schottky Barrier Diodes (SBDs)

    NASA Astrophysics Data System (ADS)

    Taşçıoǧlu, I.; Aydemir, U.; Altındal, Ş.; Tunç, T.

    2011-12-01

    This study presents the effect of illumination on main electrical parameters of Schottky barrier diode (SBD). The admittance (capacitance-voltage (C-V) and conductance-voltage (G/ω-V)) characteristics of Au/Zinc acetate doped polyvinyl alcohol (PVA:Zn)/n-Si SBD were investigated in dark and under various illumination intensities. Experimental results demonstrate that the C-V plots give a peak due to the illumination induced interface states or electron-hole pairs at metal/semiconductor (M/S) interface. The C-2-V plots were also drawn to determine main electrical parameters such as doping concentration (ND), depletion layer width (WD) and barrier height (ΦB(C-V)) of device. In addition, the voltage dependence Rs values were obtained from C-V and G/ω-V data by using Nicollian and Brews method. In order to obtain the real diode capacitance and conductance, the high frequency (1 MHz) Cm and Gm/w values were corrected for the effect of series resistance. All these observations confirm that both C-V and G/w-V characteristics were strongly affected by illumination.

  18. Temperature dependent I-V characteristics of an Au/n-GaAs Schottky diode analyzed using Tung’s model

    NASA Astrophysics Data System (ADS)

    Korucu, Demet; Turut, Abdulmecit; Efeoglu, Hasan

    2013-04-01

    The current-voltage (I-V) characteristics of Au/n-GaAs contacts prepared with photolithography technique have been measured in the temperature range of 80-320 K. The ideality factor and barrier height (BH) values have remained almost unchanged between 1.04 and 1.10 and at a value of about 0.79 eV at temperatures above 200 K, respectively. Therefore, the ideality factor values near unity say that the experimental I-V data are almost independent of the sample temperature, that is, contacts have shown excellent Schottky diode behavior above 200 K. An abnormal decrease in the experimental BH Φb and an increase in the ideality factor with a decrease in temperature have been observed below 200 K. This behavior has been attributed to the barrier inhomogeneity by assuming a Gaussian distribution of nanometer-sized patches with low BH at the metal-semiconductor interface. The barrier inhomogeneity assumption is also confirmed by the linear relationship between the BH and the ideality factor. According to Tung’s barrier inhomogeneity model, it has been seen that the value of σT=7.41×10-5 cm2/3 V1/3from ideality factor versus (kT)-1 curve is in close agreement with σT=7.95×10-5 cm2/3 V1/3 value from the Φeff versus (2kT)-1 curve in the range of 80-200 K. The modified Richardson ln(J0/T2)-(qσT)2(Vb/η)2/3/[2(kT)2] versus (kT)-1 plot, from Tung’s Model, has given a Richardson constant value of 8.47 A cm-2 K-2which is in very close agreement with the known value of 8.16 A cm-2 K-2 for n-type GaAs; considering the effective patch area which is significantly lower than the entire geometric area of the Schottky contact, in temperature range of 80-200 K. Thus, it has been concluded that the use of Tung’s lateral inhomogeneity model is more appropriate to interpret the temperature-dependent I-V characteristics in the Schottky contacts.

  19. Comparative study of the temperature-dependent dielectric properties of Au/PPy/n-Si (MPS)-type Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Gümüş, Ahmet; Ersöz, Gülçin; Yücedağ, İbrahim; Bayrakdar, Sümeyye; Altindal, Şemsettin

    2015-09-01

    The dielectric properties of Au/PPy/n-Si metal-polymer-semiconductor (MPS)-type Schottky barrier diodes (SBDs) were investigated by using capacitance-voltage ( C-V) and conductancevoltage ( G/ω-V) measurements at various temperatures and voltages at frequencies of 100 kHz and 500 kHz. Both the real and the imaginary parts of the complex dielectric constant and dielectric loss ( ɛ', ɛ″) and of the electric modulus ( M', M″), as well as the conductivity (σ ac ), were found to depend strongly on the temperature and the voltage. Both the C and G/ω values increased with increasing applied voltage and had inversion, depletion, and accumulation regions as with a metal-insulator-semiconductor (MIS) type behavior. Both the dielectric constant ( ɛ') and the dielectric loss ( ɛ″) increased with increasing temperature and decreased with increasing frequency. The loss tangent (tan δ) vs. temperature curve had a peak at about 200 K for both frequencies. The M' and the M″ values decreased with increasing temperature and became independent of the frequency at high temperatures. The series resistance ( R s ) of the diode decreased with increasing temperature for the two frequencies while the σ ac increased. Such behaviors of the dielectric properties with temperature were attributed to the restructuring and reordering of charges at interface states/traps due to the varying temperature, the interfacial polarization, and the interfacial polymer layer. ln(σ ac ) vs. q/kT plots had two distinct linear regions with different slopes for the two frequencies. Such behaviors of these plots confirmed the existence of two different conduction mechanisms corresponding to low and high temperatures. The values of the activation energy ( E a ) were obtained from the slopes of these plots, and its value at low temperatures was considerably lower than that at high temperatures.

  20. Low-Temperature Growth of Well-Aligned ZnO Nanorod Arrays by Chemical Bath Deposition for Schottky Diode Application

    NASA Astrophysics Data System (ADS)

    Yuan, Zhaolin

    2015-04-01

    A well-aligned ZnO nanorod array (ZNRA) was successfully grown on an indium tin oxide (ITO) substrate by chemical bath deposition at low temperature. The morphology, crystalline structure, transmittance spectrum and photoluminescence spectrum of as-grown ZNRA were investigated by field emission scanning electron microscopy, x-ray diffraction, ultraviolet-visible spectroscopy and spectrophotometer, respectively. The results of these measurements showed that the ZNRA contained densely packed, aligned nanorods with diameters from 30 nm to 40 nm and a wurtzite structure. The ZNRA exhibited good optical transparency within the visible spectral range, with >80% transmission. Gold (Au) was deposited on top of the ZNRA, and the current-voltage characteristics of the resulting ITO/ZNRA/Au device in the dark were evaluated in detail. The ITO/ZNRA/Au device acted as a Schottky barrier diode with rectifying behaviour, low turn-on voltage (0.6 V), small reverse-bias saturation current (3.73 × 10-6 A), a high ideality factor (3.75), and a reasonable barrier height (0.65 V) between the ZNRA and Au.

  1. Optical pumping of deep traps in AlGaN/GaN-on-Si HEMTs using an on-chip Schottky-on-heterojunction light-emitting diode

    SciTech Connect

    Li, Baikui; Tang, Xi; Chen, Kevin J.

    2015-03-02

    In this work, by using an on-chip integrated Schottky-on-heterojunction light-emitting diode (SoH-LED) which is seamlessly integrated with the AlGaN/GaN high electron mobility transistor (HEMT), we studied the effect of on-chip light illumination on the de-trapping processes of electrons from both surface and bulk traps. Surface trapping was generated by applying OFF-state drain bias stress, while bulk trapping was generated by applying positive substrate bias stress. The de-trapping processes of surface and/or bulk traps were monitored by measuring the recovery of dynamic on-resistance R{sub on} and/or threshold voltage V{sub th} of the HEMT. The results show that the recovery processes of both dynamic R{sub on} and threshold voltage V{sub th} of the HEMT can be accelerated by the on-chip SoH-LED light illumination, demonstrating the potentiality of on-chip hybrid opto-HEMTs to minimize the influences of traps during dynamic operation of AlGaN/GaN power HEMTs.

  2. Frequency and gate voltage effects on the dielectric properties and electrical conductivity of Al∕SiO(2)∕p-Si metal-insulator-semiconductor Schottky diodes.

    PubMed

    Yıldız, D E; Dökme, I

    2011-07-01

    The dielectric properties and electrical conductivity of Al∕SiO(2)∕p-Si (MIS) Schottky diodes (SDs) in the frequency range of 10 kHz to 10 MHz and the gate voltage range of -2 to 6 V have been investigated in detail using experimental C-V and G∕w-V measurements. Experimental results indicated that the voltage dependence of the real part of the dielectric constant (ɛ') and loss tangent (tan δ) characteristics have a peak at each frequency. The values of ɛ' increase with decreasing frequency and tend to be frequency independent in the negative voltage region. However, the values of the dielectric loss (ɛ″) increase with decreasing frequency at each voltage. In contrast, ɛ' and ɛ″ are almost found to decrease, and the ac electrical conductivity (σ(ac)) and the real part of the electric modulus (M') increase, with increasing frequency. In addition, the imaginary part of the electric modulus (M″) showed a peak that shifts to a higher frequency with increasing applied voltage. It can be concluded that interfacial polarization can more easily occur at low frequencies, and consequently the majority of interface states at the Si-SiO(2) interface contribute to the deviation of the dielectric properties of Al∕SiO(2)∕p-Si (MIS) SDs.

  3. Dielectric properties and electric modulus of Au/PPy/n-Si (MPS) type Schottky barrier diodes (SBDS) as a function of frequency and applied bias voltage

    NASA Astrophysics Data System (ADS)

    Yücedağ, Ibrahim; Ersöz, Gülçin; Gümüş, Ahmet; Altındal, Şemsettin

    2015-03-01

    Au/PPy/n-Si Schottky barrier diodes (SBDs) were fabricated by forming polypyrrole (PPy) organic layer on n-Si using the spin coating technique. Frequency-dependent dielectric constant (ɛ‧), dielectric loss (ɛ″), loss tangent (tan δ), real and imaginary parts of electrical modulus (M‧ and M″) and AC electrical conductivity (σac) parameters of the structure were investigated in the frequency range of 10-500 kHz. It was found that the values of the ɛ‧, ɛ″ and tan δ, in general, decrease with increasing frequency while an increase is observed in σac, M‧ and M″. The tanδ and M″ also exhibit a peak at about zero-bias voltage, while peak intensity weakens with increasing frequency. The values of ɛ‧ and M‧ decrease with increasing voltage while an increase is observed in ɛ″, tan δ, σac and M″. These changes in ɛ‧, ɛ″, tan δ, M‧, M″ and σac values was attributed to surface charge polarization and the particular density distribution of surface states localized at PPy/n-Si interface.

  4. A theoretical model for Schottky diodes for excluding the sneak current in cross bar array resistive memory

    NASA Astrophysics Data System (ADS)

    Kim, Gun Hwan; Kim, Kyung Min; Seok, Jun Yeong; Lee, Hyun Ju; Cho, Deok-Yong; Han, Jeong Hwan; Hwang, Cheol Seong

    2010-09-01

    Kirchhoff's law was used to examine the electrical specifications of selection diodes, which are essential for suppressing the read interference problems in nano-scale resistive switching cross bar arrays with a high block density. The diode in the cross bar array with a 100 Mb block density should have a reverse/forward resistance ratio of > 108, and a forward current density of > 105 A cm - 2 for stable reading and writing operation. Whilst normal circuit simulators are heavily overloaded when the number of cells (m) connected to one bit and word line is larger (m\\gg 100 ), which is the desired range for high density cross bar arrays, the present model can provide a simple simulation. The validity of this new method was confirmed by a comparison with the previously reported method based on a voltage estimation.

  5. Response of Ni/4H-SiC Schottky barrier diodes to alpha-particle irradiation at different fluences

    NASA Astrophysics Data System (ADS)

    Omotoso, E.; Meyer, W. E.; Auret, F. D.; Diale, M.; Ngoepe, P. N. M.

    2016-01-01

    Irradiation experiments have been carried out on 1.9×1016 cm-3 nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.6×1010 to 9.2×1011 cm-2. Current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements have been carried out to study the change in characteristics of the devices and free carrier removal rate due to alpha-particle irradiation, respectively. As radiation fluence increases, the ideality factors increased from 1.20 to 1.85 but the Schottky barrier height (SBHI-V) decreased from 1.47 to 1.34 eV. Free carrier concentration, Nd decreased with increasing fluence from 1.7×1016 to 1.1×1016 cm-2 at approximately 0.70 μm depth. The reduction in Nd shows that defects were induced during the irradiation and have effect on compensating the free carrier. The free carrier removal rate was estimated to be 6480±70 cm-1. Alpha-particle irradiation introduced two electron traps (E0.39 and E0.62), with activation energies of 0.39±0.03 eV and 0.62±0.08 eV, respectively. The E0.39 as attribute related to silicon or carbon vacancy, while the E0.62 has the attribute of Z1/Z2.

  6. Calculation of the Electronic Parameters of an Al/DNA/p-Si Schottky Barrier Diode Influenced by Alpha Radiation

    PubMed Central

    Al-Ta’ii, Hassan Maktuff Jaber; Amin, Yusoff Mohd; Periasamy, Vengadesh

    2015-01-01

    Many types of materials such as inorganic semiconductors have been employed as detectors for nuclear radiation, the importance of which has increased significantly due to recent nuclear catastrophes. Despite the many advantages of this type of materials, the ability to measure direct cellular or biological responses to radiation might improve detector sensitivity. In this context, semiconducting organic materials such as deoxyribonucleic acid or DNA have been studied in recent years. This was established by studying the varying electronic properties of DNA-metal or semiconductor junctions when exposed to radiation. In this work, we investigated the electronics of aluminium (Al)/DNA/silicon (Si) rectifying junctions using their current-voltage (I-V) characteristics when exposed to alpha radiation. Diode parameters such as ideality factor, barrier height and series resistance were determined for different irradiation times. The observed results show significant changes with exposure time or total dosage received. An increased deviation from ideal diode conditions (7.2 to 18.0) was observed when they were bombarded with alpha particles for up to 40 min. Using the conventional technique, barrier height values were observed to generally increase after 2, 6, 10, 20 and 30 min of radiation. The same trend was seen in the values of the series resistance (0.5889–1.423 Ω for 2–8 min). These changes in the electronic properties of the DNA/Si junctions could therefore be utilized in the construction of sensitive alpha particle detectors. PMID:25730484

  7. Temperature-dependent capacitance-voltage and current-voltage characteristics of Pt/Ga2O3 (001) Schottky barrier diodes fabricated on n--Ga2O3 drift layers grown by halide vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Higashiwaki, Masataka; Konishi, Keita; Sasaki, Kohei; Goto, Ken; Nomura, Kazushiro; Thieu, Quang Tu; Togashi, Rie; Murakami, Hisashi; Kumagai, Yoshinao; Monemar, Bo; Koukitu, Akinori; Kuramata, Akito; Yamakoshi, Shigenobu

    2016-03-01

    We investigated the temperature-dependent electrical properties of Pt/Ga2O3 Schottky barrier diodes (SBDs) fabricated on n--Ga2O3 drift layers grown on single-crystal n+-Ga2O3 (001) substrates by halide vapor phase epitaxy. In an operating temperature range from 21 °C to 200 °C, the Pt/Ga2O3 (001) Schottky contact exhibited a zero-bias barrier height of 1.09-1.15 eV with a constant near-unity ideality factor. The current-voltage characteristics of the SBDs were well-modeled by thermionic emission in the forward regime and thermionic field emission in the reverse regime over the entire temperature range.

  8. Electrical Characteristics of an Ag/n-InP Schottky Diode Based on Temperature-Dependent Current-Voltage and Capacitance-Voltage Measurements

    NASA Astrophysics Data System (ADS)

    Gülnahar, Murat

    2015-09-01

    The rectifying junction properties of an Ag/n-InP Schottky diode are investigated in a wide temperature range from 10 K to 300 K (-263 °C to 27 °C). The electronic structure of the junction is analyzed by the techniques of current-voltage I- V and capacitance-voltage C- V measurement as a function of temperature. The electrical parameters are characterized with the standard thermionic emission theory. The main electrical characteristics including the values of apparent barrier height and ideality factor n are found to be 0.414 eV and 1.008 at 300 K (27 °C), respectively, even though the value of barrier height at 300 K (27 °C) from C- V data is 0.417 eV. The , n, and Richardson plot demonstrate strong temperature dependency; that is, the decreases, n increases, and the Richardson plot deviates with decreasing temperature. Such behaviors are attributed to Schottky barrier anomalies, which are explained by assuming the existence of a Gaussian distribution of nanometer-sized patches with low barrier height at the interface. The accurate theoretical models such as Tung's lateral inhomogeneity and multi-Gaussian distribution to comment the barrier inhomogeneity on the electron transport across the interface are applied, and the comparisons between these approaches for the present experimental results are carried out. According to the multi-Gaussian distribution approach, the double-Gaussian nature of Ag/n-InP/In is commented by the values of the weighting coefficients, standard deviations, and mean barrier height calculated for each distribution. The total effective area of the patches is calculated for high and low temperatures, and as a result, it is found that the low barrier regions influence significantly the electron transport at the interface of the junction. The discrepancy between I- V and C- V barrier heights is discussed based on a Gaussian approach. From the linear relationship between and n, the homogeneous barrier height is noted to be 0.418 eV. The

  9. Influence of dry-etching damage on the electrical properties of an AlGaN/GaN Schottky barrier diode with recessed anode

    NASA Astrophysics Data System (ADS)

    Zhong, Jian; Yao, Yao; Zheng, Yue; Yang, Fan; Ni, Yi-Qiang; He, Zhi-Yuan; Shen, Zhen; Zhou, Gui-Lin; Zhou, De-Qiu; Wu, Zhi-Sheng; Zhang, Bai-Jun; Liu, Yang

    2015-09-01

    The influences of dry-etching damage on the electrical properties of an AlGaN/GaN Schottky barrier diode with ICP-recessed anode was investigated for the first time. It was found that the turn-on voltage is decreased with the increase of dry-etching power. Furthermore, the leakage currents in the reverse bias region above pinch-off voltage rise as radio frequency (RF) power increases, while below pinch-off voltage, leakage currents tend to be independent of RF power. Based on detailed current-voltage-temperature (I-V-T) measurements, the barrier height of thermionic-field emission (TFE) from GaN is lowered as RF power increases, which results in early conduction. The increase of leakage current can be explained by Frenkel-Poole (FP) emission that higher dry-etching damage in the sidewall leads to the higher tunneling current, while below pinch-off voltage, the leakage is only related to the AlGaN surface, which is independent of RF power. Project supported by the National Natural Science Foundation of China (Grant Nos. 51177175 and 61274039), the National Basic Research Program of China (Grant Nos. 2010CB923200 and 2011CB301903), the Ph. D. Programs Foundation of Ministry of Education of China (Grant No. 20110171110021), the International Science and Technology Collaboration Program of China (Grant No. 2012DFG52260), the National High Technology Research and Development Program of China (Grant No. 2014AA032606), the Science and Technology Plan of Guangdong Province, China (Grant No. 2013B010401013), and the Opened Fund of the State Key Laboratory on Integrated Optoelectronics, China (Grant No. IOSKL2014KF17).

  10. Capacitance behavior of InAlN Schottky diodes in presence of large concentrations of shallow and deep states related to oxygen

    NASA Astrophysics Data System (ADS)

    Py, M. A.; Lugani, L.; Taniyasu, Y.; Carlin, J.-F.; Grandjean, N.

    2015-05-01

    The capacitance-voltage-temperature characteristics of nonintentionally doped In0.16Al0.84N/n+-GaN Schottky diodes were measured at 1 MHz and in the 90-400 K range. They are discussed in the framework of existing theories, which properly treat the Poisson's equation, especially near the edge of the space-charge region, the so-called transition region. The concentration of a shallow donor and of a deep DX-like center, previously reported, is properly determined. The key parameter to discuss the temperature dependence of the capacitance is the ratio between the frequency of the small ac modulating signal and the temperature-dependent emission rate associated to each level. The capacitance-voltage C-Va curves were successfully fitted using a three parameters expression over the full range of temperatures. The concentration of both shallow and deep levels exceeds a few 1018 cm-3. Based on secondary ion mass spectrometry profiling, we assign both levels to the dominant oxygen impurity. This result supports our previous assignment of the shallow donor to a substitutional oxygen atom on a nitrogen site and the deep state to an O-related DX center, naturally explaining its high concentration. The sluggish kinetics at low temperatures, associated to the large concentration of deep levels located near the transition region, is illustrated by hysteresis loops in the C-Va curves below 270 K. Furthermore, the contribution of free carriers to the capacitance is revealed below 150 K, when both shallow and deep donors cannot respond anymore due to an emission rate lower than the 1 MHz modulating frequency. Finally, the presence of a highly doped thin surface barrier, as already reported in other III-nitrides, finds further support.

  11. Capacitance behavior of InAlN Schottky diodes in presence of large concentrations of shallow and deep states related to oxygen

    SciTech Connect

    Py, M. A. Lugani, L.; Taniyasu, Y.; Carlin, J.-F.; Grandjean, N.

    2015-05-14

    The capacitance-voltage-temperature characteristics of nonintentionally doped In{sub 0.16}Al{sub 0.84 }N/n{sup +}-GaN Schottky diodes were measured at 1 MHz and in the 90–400 K range. They are discussed in the framework of existing theories, which properly treat the Poisson's equation, especially near the edge of the space-charge region, the so-called transition region. The concentration of a shallow donor and of a deep DX-like center, previously reported, is properly determined. The key parameter to discuss the temperature dependence of the capacitance is the ratio between the frequency of the small ac modulating signal and the temperature-dependent emission rate associated to each level. The capacitance-voltage C-V{sub a} curves were successfully fitted using a three parameters expression over the full range of temperatures. The concentration of both shallow and deep levels exceeds a few 10{sup 18} cm{sup −3}. Based on secondary ion mass spectrometry profiling, we assign both levels to the dominant oxygen impurity. This result supports our previous assignment of the shallow donor to a substitutional oxygen atom on a nitrogen site and the deep state to an O-related DX center, naturally explaining its high concentration. The sluggish kinetics at low temperatures, associated to the large concentration of deep levels located near the transition region, is illustrated by hysteresis loops in the C-V{sub a} curves below 270 K. Furthermore, the contribution of free carriers to the capacitance is revealed below 150 K, when both shallow and deep donors cannot respond anymore due to an emission rate lower than the 1 MHz modulating frequency. Finally, the presence of a highly doped thin surface barrier, as already reported in other III-nitrides, finds further support.

  12. Analysis of temperature dependent current-conduction mechanisms in Au/TiO2/n-4H-SiC (metal/insulator/semiconductor) type Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Alialy, S.; Altındal, Ş.; Tanrıkulu, E. E.; Yıldız, D. E.

    2014-08-01

    In order to determine the effective current-conduction mechanisms in Au/TiO2/n-4H-SiC (metal-insulator semiconductor) type Schottky barrier diodes (SBDs), their current-voltage (I-V) measurements were carried out in the temperature range of 200-380 K. Some electrical parameters, such as ideality factor (n), zero-bias barrier height (BH) (ΦBo), series and shunt resistances (Rs, Rsh), were obtained as 5.09, 0.81 eV, 37.43 Ω, and 435 kΩ at 200 K and 2.68, 0.95 eV, 5.99 Ω, and 73 kΩ at 380 K, respectively. The energy density distribution profile of surface states (Nss) was extracted from the forward-bias I-V data by taking into account voltage dependent of the ideality factor (nV), effective BH (Φe), and Rs for 200, 300, and 380 K. The Ln(I) vs V plots are completely parallel in the intermediate bias voltages, which may be well explained by field emission (FE) mechanism for each temperature. On the other hand, the high value of n cannot be explained with this mechanism. Therefore, to explain the change in BH and n with temperature, ΦBo vs q/2kT plot was drawn to obtain an evidence of a Gaussian distribution (GD) of the BHs and thus the mean value of BH (Φ¯Bo) and standard deviation (σso) values were found from this plot as 1.396 eV and 0.176 V, respectively. The Φ¯Bo and Richardson constant (A*) values were found as 1.393 eV and 145.5 A.cm-2 K-2 using modified Ln(Io/T2)-(q2σs2/2k2T2) vs q/kT plot, respectively. It is clear that all of the obtained main electrical parameters were found as a strong function of temperature. These results indicated that the current conduction mechanism in Au/TiO2/n-4 H-SiC (SBD) well obey the FE and GD mechanism rather than other mechanisms.

  13. High-voltage AlGaN/GaN Schottky barrier diodes on silicon using a post-process O2 treatment

    NASA Astrophysics Data System (ADS)

    Seok, Ogyun; Han, Min-Koo; Byun, Young-Chul; Kim, Jiyoung; Shin, Hyun-Chang; Ha, Min-Woo

    2015-01-01

    High-voltage AlGaN/GaN Schottky barrier diodes (SBDs) were fabricated using on a silicon (1 1 1) substrate, and a post-process O2 treatment was carried out to reduce the leakage current and increase the breakdown voltage. Time-of-flight secondary ion mass spectroscopy revealed that, following the post-process O2 treatment, oxygen diffused into an AlGaN barrier and AlO was generated. A significant suppression of the leakage current (of approximately 6 orders of magnitude) occurred in the buffer isolation structures following the O2 treatment. Our method also resulted in suppression of the surface leakage current through the mesa-etched surface. A virgin GaN SBD exhibited a leakage current of 1.76 × 10-2 A/cm2, whereas the equivalent O2-treated device had a leakage current of 1.75 × 10-4 A/cm2 (the anode-cathode distance was LAC = 10 μm, and the applied bias was -100 V). This reduction in the leakage current was caused by surface passivation at the anode and cathode. The post-process O2 treatment also increased the breakdown voltage from Vb = 808 V to Vb = 1590 V for a device with LAC = 10 μm. GaN SBDs with and without the post-process O2 treatment exhibited low specific on-resistance of Ron,sp = 2.51 mΩ cm2 and Ron,sp = 2.48 mΩ cm2, respectively, with LAC = 10 μm. Devices with the post-process O2 treatment exhibited a figure of merit of Vb2/Ron,sp = 1006 MW/cm2, whereas devices without the O2 treatment exhibited a figure of merit of Vb2/Ron,sp = 263 MW/cm2. These high-voltage GaN SBDs employing the post-process O2 treatment are suitable for applications including DC-DC converters, inverters, and power factor correction circuits, where high voltage operation is required with low leakage currents.

  14. Deep traps and temperature effects on the capacitance of p-type Si-doped GaAs Schottky diodes on (2 1 1) and (3 1 1) oriented GaAs substrates

    NASA Astrophysics Data System (ADS)

    Boumaraf, R.; Sengouga, N.; Mari, R. H.; Meftah, Af.; Aziz, M.; Jameel, Dler; Al Saqri, Noor; Taylor, D.; Henini, M.

    2014-01-01

    The SILVACO-TCAD numerical simulator is used to explain the effect of different types of deep levels on the temperature dependence of the capacitance of p-type Si-doped GaAs Schottky diodes grown on high index GaAs substrates, namely (3 1 1)A and (2 1 1)A oriented GaAs substrates. For the (3 1 1)A diodes, the measured capacitance-temperature characteristics at different reverse biases show a large peak while the (2 1 1)A devices display a much smaller one. This peak is related to the presence of different types of deep levels in the two structures. These deep levels are characterized by the Deep Level Transient Spectroscopy (DLTS) technique. In the (3 1 1)A structure only majority deep levels (hole deep levels) were observed while both majority and minority deep levels were present in the (2 1 1)A diodes. The simulation software, which calculates the capacitance-voltage and the capacitance-temperature characteristics in the absence and presence of different types of deep levels, agrees well with the experimentally observed behavior of the capacitance-temperature properties. A further evidence to confirm that deep levels are responsible for the observed phenomenon is provided by a simulation of the capacitance-temperature characteristics as a function of the ac-signal frequency.

  15. Influence of Hot Carrier Transport on the Transient Response of an InGaAs/InAlAs Metal-Semiconductor Schottky Diode Structure

    NASA Technical Reports Server (NTRS)

    Salem, Ali F.; Brennan, Kevin F.

    1996-01-01

    The calculated transient characteristic of a heterostructure, rectifying contact is theoretically examined. It is found that hot carrier transport drastically affects the output terminal characteristics of the heterostructure Schottky contact and, hence, the working of a blocking contact. This is of importance to the understanding of InGaAs MSM devices in particular, as well as any structure which contains a blocking contact in general.

  16. Schottky Barrier with Liquid Metal

    NASA Astrophysics Data System (ADS)

    Modi, B. P.; Patel, K. D.

    2011-12-01

    Schottky barrier with liquid metal may provide an attractive and new opportunity to look into various aspect of the evolution of Schottky interfaces in a relatively beneficial manner [1]. Here gallium-silicon diode has been fabricated and investigated especially around the melting point of gallium. Analysis of data no barrier height exhibits an anomalous change in the sense that there is a sharp deterioration in the rectifying nature near this temperature. It is believed to be related changes the phase transition driven physical process e.g. breaking of bonds both between gallium atoms and between gallium atoms and silicon interface; change from long range to short range order in gallium. Strain relaxations at the interface etc.

  17. Magnetic tunnel transistor with a perpendicular Co/Ni multilayer sputtered on a Si/Cu(1 0 0) Schottky diode

    NASA Astrophysics Data System (ADS)

    Vautrin, C.; Lu, Y.; Robert, S.; Sala, G.; Lenoble, O.; Petit-Watelot, S.; Devaux, X.; Montaigne, F.; Lacour, D.; Hehn, M.

    2016-09-01

    We have studied a magnetic tunnel transistor (MTT) structure based on a MgO tunnelling barrier emitter and a [Co/Ni]5/Cu multilayer base on a Si (0 0 1) substrate. Evident links between the Schottky barrier preparation techniques and the properties of perpendicular magnetic anisotropy (PMA) in the [Co/Ni] multilayer have been revealed by combined x-ray diffraction and magnetometry analyses. The Si surface treated by hydrofluoric acid (HF) is found to favour a Cu [1 0 0] texture growth which is detrimental to the [Co/Ni]5 PMA properties. However, a Ta layer insertion can restore the [1 1 1] texture required for the PMA appearance. By carefully engineering the base crystallographic texture structure, we obtain both a good quality of Schottky barrier and PMA property; a magneto-current ratio of 162% has been measured for MTTs with a spin-valve base composed of one magnetic layer having in-plane anisotropy and another one with out-of-plane anisotropy.

  18. A comparative study on the electrical parameters of Au/n-Si Schottky diodes with and without interfacial (Ca1.9Pr0.1Co4Ox) layer

    NASA Astrophysics Data System (ADS)

    Kaya, A.; Çetinkaya, H. G.; Altındal, Ş.; Uslu, I.

    2016-05-01

    In order to compare the main electrical parameters such as ideality factor (n), barrier height (BH) (ΦI-V), series (Rs) and shunt (Rsh) resistances and energy density distribution profile of surface states (Nss), the Au/n-Si (MS) Schotthy diodes (SDs), with and without interfacial (Ca1.9Pr0.1Co4Ox) layer were obtained from the current-voltage (I-V ) measurements at room temperature. The other few electrical parameters such as Fermi energy level (EF), BH (ΦC-V), Rs and voltage dependence of Nss profile were also obtained from the capacitance-voltage (C-V ) measurements. The voltage dependence of Nss profile has two distinctive peaks in the depletion region for two diodes and they were attributed to a particular distribution of Nss located at metal-semiconductor (MS) interface. All of these results have been investigated at room temperature and results have been compared with each other. Experimental results confirmed that interfacial (Ca1.9Pr0.1Co4Ox) layer enhanced diode performance in terms of rectifier rate (RR = IF/IR at ± 3.4V), Nss (at 0.5eV) and Rsh (‑3.4V) with values of 265, 5.38 × 1013eV‑1 ṡcm‑2 and 7.87 × 104Ω for MS type Schottky barrier diode and 2.56 × 106, 1.15 × 1013eV‑1 ṡcm‑2 and 7.50 × 108Ω for metal-insulator-semiconductor (MIS) type SBD, respectively. It is clear that the rectifying ratio of MIS type SBD is about 9660 times greater than MS type SBD. The value of barrier height (BH) obtained from C-V data is higher than the forward bias I-V data and it was attributed to the nature of measurements. These results confirmed that the interfacial (Ca1.9Pr0.1Co4Ox) layer has considerably improved the performance of SD.

  19. A comparative study on the electrical parameters of Au/n-Si Schottky diodes with and without interfacial (Ca1.9Pr0.1Co4Ox) layer

    NASA Astrophysics Data System (ADS)

    Kaya, A.; Çetinkaya, H. G.; Altındal, Ş.; Uslu, I.

    2016-05-01

    In order to compare the main electrical parameters such as ideality factor (n), barrier height (BH) (ΦI-V), series (Rs) and shunt (Rsh) resistances and energy density distribution profile of surface states (Nss), the Au/n-Si (MS) Schotthy diodes (SDs), with and without interfacial (Ca1.9Pr0.1Co4Ox) layer were obtained from the current-voltage (I-V ) measurements at room temperature. The other few electrical parameters such as Fermi energy level (EF), BH (ΦC-V), Rs and voltage dependence of Nss profile were also obtained from the capacitance-voltage (C-V ) measurements. The voltage dependence of Nss profile has two distinctive peaks in the depletion region for two diodes and they were attributed to a particular distribution of Nss located at metal-semiconductor (MS) interface. All of these results have been investigated at room temperature and results have been compared with each other. Experimental results confirmed that interfacial (Ca1.9Pr0.1Co4Ox) layer enhanced diode performance in terms of rectifier rate (RR = IF/IR at ± 3.4V), Nss (at 0.5eV) and Rsh (-3.4V) with values of 265, 5.38 × 1013eV-1 ṡcm-2 and 7.87 × 104Ω for MS type Schottky barrier diode and 2.56 × 106, 1.15 × 1013eV-1 ṡcm-2 and 7.50 × 108Ω for metal-insulator-semiconductor (MIS) type SBD, respectively. It is clear that the rectifying ratio of MIS type SBD is about 9660 times greater than MS type SBD. The value of barrier height (BH) obtained from C-V data is higher than the forward bias I-V data and it was attributed to the nature of measurements. These results confirmed that the interfacial (Ca1.9Pr0.1Co4Ox) layer has considerably improved the performance of SD.

  20. A 640 GHz Planar-Diode Fundamental Mixer/Receiver

    NASA Technical Reports Server (NTRS)

    Siegel, P.; Mehdi, I.; Dengler, R.; Lee, T.; Humphrey, D.; Pease, A.

    1998-01-01

    The design and performance of a 640 GHz solid-state receiver using a fundamental planar-Schottky-diode mixer, InP Gunn diode oscillator, whisker-contacted Schottky-varactor-diode sextupler and folded-Fabry-Perot diplexer are reported.

  1. Electrically pumped random lasing based on an Au-ZnO nanowire Schottky junction.

    PubMed

    Gao, Fan; Morshed, Muhammad M; Bashar, Sunayna B; Zheng, Youdou; Shi, Yi; Liu, Jianlin

    2015-06-01

    Electrically pumped random lasing based on an Au-ZnO nanowire Schottky junction diode is demonstrated. The device exhibits typical Schottky diode current-voltage characteristics with a turn-on voltage of 0.7 V. Electroluminescence characterization shows good random lasing behavior and the output power is about 67 nW at a drive current of 100 mA. Excitonic recombination is responsible for lasing generation. Zn plasma is only observed under high applied bias, which can be distinguished from the random lasing spectral features near 380 nm. The laser diode based on the Schottky junction provides an alternative approach towards semiconductor random lasers. PMID:25946977

  2. Fluorine plasma treatment induced deep level traps and their effect on current transportation in Al0.83In0.17N/AlN/GaN Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Xiang, Yong; Yu, Tongjun; Ji, Cheng; Cheng, Yutian; Yang, Xuelin; Kang, Xiangning; Shen, Bo; Zhang, Guoyi

    2016-08-01

    The deep level traps and the electrical properties of fluorine plasma treated (F-treated) and non-treated Al0.83In0.17N/AlN/GaN Schottky barrier diodes (SBDs) were investigated by the temperature-dependent current-voltage (I-V) and deep level transient spectroscopy (DLTS) measurements. Three deep level traps were detected in the SBD after F-treatment at ~E c  -  0.17 eV, ~E c  -  0.27 eV and ~E c  -  1.14 eV. One of the deep level traps at ~E c  -  1.14 eV is mainly located in the Al0.83In0.17N barrier layer with a captured cross section (σ) of ~6.50  ×  10-18 cm2. This F-related deep level trap has 3-4 orders of magnitude of the larger σ and ~0.46 eV greater active energy than that of the dislocation-related one at ~E c  -  0.68 eV with σ of ~1.92  ×  10-21 cm2. Meanwhile, the leakage current of F-treated SBD at  -5 V is reduced by ~2 orders of magnitude compared with that of the non-treated one. This leakage current reduction is mainly attributed to the increase of the Poole-Frenkel emission barrier height from ~0.09 eV in non-treated SBD to ~0.46 eV in the F-treated one. It is believed that the main reverse current transportation is the Poole-Frenkel emission from the F-related deep level trap states into the continuum states of the dislocations in F-treated Al0.83In0.17N/AlN/GaN SBD.

  3. Fluorine plasma treatment induced deep level traps and their effect on current transportation in Al0.83In0.17N/AlN/GaN Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Xiang, Yong; Yu, Tongjun; Ji, Cheng; Cheng, Yutian; Yang, Xuelin; Kang, Xiangning; Shen, Bo; Zhang, Guoyi

    2016-08-01

    The deep level traps and the electrical properties of fluorine plasma treated (F-treated) and non-treated Al0.83In0.17N/AlN/GaN Schottky barrier diodes (SBDs) were investigated by the temperature-dependent current–voltage (I–V) and deep level transient spectroscopy (DLTS) measurements. Three deep level traps were detected in the SBD after F-treatment at ~E c  ‑  0.17 eV, ~E c  ‑  0.27 eV and ~E c  ‑  1.14 eV. One of the deep level traps at ~E c  ‑  1.14 eV is mainly located in the Al0.83In0.17N barrier layer with a captured cross section (σ) of ~6.50  ×  10‑18 cm2. This F-related deep level trap has 3–4 orders of magnitude of the larger σ and ~0.46 eV greater active energy than that of the dislocation-related one at ~E c  ‑  0.68 eV with σ of ~1.92  ×  10‑21 cm2. Meanwhile, the leakage current of F-treated SBD at  ‑5 V is reduced by ~2 orders of magnitude compared with that of the non-treated one. This leakage current reduction is mainly attributed to the increase of the Poole–Frenkel emission barrier height from ~0.09 eV in non-treated SBD to ~0.46 eV in the F-treated one. It is believed that the main reverse current transportation is the Poole–Frenkel emission from the F-related deep level trap states into the continuum states of the dislocations in F-treated Al0.83In0.17N/AlN/GaN SBD.

  4. Silicon Schottky Diode Safe Operating Area

    NASA Technical Reports Server (NTRS)

    Casey, Megan C.; Lauenstein, Jean-Marie; Ladbury, Raymond L.; Wilcox, Edward P.; Phan, Anthony M.; Label, Kenneth A.

    2016-01-01

    Vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacementdamage is studied. Devices tested include optoelectronics, digital, analog, linear bipolar devices, and hybrid devices.

  5. Silicon Schottky Diode Safe Operating Area

    NASA Technical Reports Server (NTRS)

    Casey, Megan C.; Campola, Michael J.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Phan, Anthony M.; LaBel, Kenneth A.

    2016-01-01

    Vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage is studied. Devices tested include optoelectronics, digital, analog, linear bipolar devices, and hybrid devices.

  6. Scalability of Schottky barrier metal-oxide-semiconductor transistors

    NASA Astrophysics Data System (ADS)

    Jang, Moongyu

    2016-05-01

    In this paper, the general characteristics and the scalability of Schottky barrier metal-oxide-semiconductor field effect transistors (SB-MOSFETs) are introduced and reviewed. The most important factors, i.e., interface-trap density, lifetime and Schottky barrier height of erbium-silicided Schottky diode are estimated using equivalent circuit method. The extracted interface trap density, lifetime and Schottky barrier height for hole are estimated as 1.5 × 1013 traps/cm2, 3.75 ms and 0.76 eV, respectively. The interface traps are efficiently cured by N2 annealing. Based on the diode characteristics, various sizes of erbium-silicided/platinum-silicided n/p-type SB-MOSFETs are manufactured and analyzed. The manufactured SB-MOSFETs show enhanced drain induced barrier lowering (DIBL) characteristics due to the existence of Schottky barrier between source and channel. DIBL and subthreshold swing characteristics are comparable with the ultimate scaling limit of double gate MOSFETs which shows the possible application of SB-MOSFETs in nanoscale regime.

  7. Varactor diodes for millimeter and submillimeter wavelengths

    NASA Technical Reports Server (NTRS)

    Rizzi, Brian J.; Hesler, Jeffrey L.; Dossal, Hasan; Crowe, Thomas W.

    1992-01-01

    Whisker-contacted GaAs Schottky barrier varactor diodes are the most common high-frequency multiplier element in use today. They are inherently simple devices that have very high frequency response and have been used to supply local oscillator power for Schottky heterodyne receivers to frequencies approaching 700 GHz. This paper discusses the development of improved varactor diode technology for space based applications at millimeter and submillimeter wavelengths.

  8. Bypass diode integration

    NASA Technical Reports Server (NTRS)

    Shepard, N. F., Jr.

    1981-01-01

    Protective bypass diodes and mounting configurations which are applicable for use with photovoltaic modules having power dissipation requirements in the 5 to 50 watt range were investigated. Using PN silicon and Schottky diode characterization data on packaged diodes and diode chips, typical diodes were selected as representative for each range of current carrying capacity, an appropriate heat dissipating mounting concept along with its environmental enclosure was defined, and a thermal analysis relating junction temperature as a function of power dissipation was performed. In addition, the heat dissipating mounting device dimensions were varied to determine the effect on junction temperature. The results of the analysis are presented as a set of curves indicating junction temperature as a function of power dissipation for each diode package.

  9. Analysis and modelling of GaN Schottky-based circuits at millimeter wavelengths

    NASA Astrophysics Data System (ADS)

    Pardo, D.; Grajal, J.

    2015-11-01

    This work presents an analysis of the capabilities of GaN Schottky diodes for frequency multipliers and mixers at millimeter wavelengths. By using a Monte Carlo (MC) model of the diode coupled to a harmonic balance technique, the electrical and noise performances of these circuits are investigated. Despite the lower electron mobility of GaN compared to GaAs, multipliers based on GaN Schottky diodes can be competitive in the first stages of multiplier chains, due to the excellent power handling capabilities of this material. The performance of these circuits can be improved by taking advantage of the lateral Schottky diode structures based on AlGaN/GaN HEMT technology.

  10. Electrical properties of bulk-barrier diodes

    NASA Astrophysics Data System (ADS)

    Mader, H.

    1982-11-01

    Like Schottky-barrier diodes, bulk-barrier diodes (BBD's) are majority-carrier devices and can, therefore, be used up to very high frequencies. In both types of diodes, charge-carrier transportation is determined by an energy barrier. In Schottky-barrier diodes the barrier is located at the metal/semiconductor boundary, whereas in BBD's it is found inside the semiconductor and is the result of a space-charge zone in a three-layered n-p-n or p-n-p structure with a very thin base region. The height of the barrier is determined by technological parameters such as doping density and layer thickness. As the current in BBD's, just as in Schottky-barrier diodes, is an exponential function of barrier height, the current-voltage characteristic can be adjusted by technological means.

  11. Schottky barrier formation and band bending revealed by first- principles calculations

    PubMed Central

    Jiao, Yang; Hellman, Anders; Fang, Yurui; Gao, Shiwu; Käll, Mikael

    2015-01-01

    The formation of a Schottky barrier at the metal-semiconductor interface is widely utilised in semiconductor devices. With the emerging of novel Schottky barrier based nanoelectronics, a further microscopic understanding of this interface is in high demand. Here we provide an atomistic insight into potential barrier formation and band bending by ab initio simulations and model analysis of a prototype Schottky diode, i.e., niobium doped rutile titania in contact with gold (Au/Nb:TiO2). The local Schottky barrier height is found to vary between 0 and 1.26 eV depending on the position of the dopant. The band bending is caused by a dopant induced dipole field between the interface and the dopant site, whereas the pristine Au/TiO2 interface does not show any band bending. These findings open the possibility for atomic scale optimisation of the Schottky barrier and light harvesting in metal-semiconductor nanostructures. PMID:26065401

  12. Electron-beam studies of Schottky-barrier detector surfaces

    NASA Technical Reports Server (NTRS)

    Peckerar, M. C.

    1973-01-01

    Review of the surface anomalies occurring in Schottky-barrier particle detectors identifiable by means of an electron beam technique employed by Czaja (1965) for analyzing defects in diode structures. The technique is shown to make possible the detection and identification of the following anomalies: (1) chemical contamination of the detector surface; (2) mechanical damage of the wafer substrates; (3) damage introduced in semiconductor surface preparation; (4) radiation damage; and (5) defective surface metallization.

  13. High Voltage GaN Schottky Rectifiers

    SciTech Connect

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

    1999-10-25

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

  14. Position and mode dependent coupling of terahertz quantum cascade laser fields to an integrated diode

    NASA Astrophysics Data System (ADS)

    Dyer, Gregory C.; Nordquist, Christopher D.; Cich, Michael J.; Ribaudo, Troy; Grine, Albert D.; Fuller, Charles T.; Reno, John L.; Wanke, Michael C.

    2013-10-01

    A Schottky diode integrated into a terahertz quantum cascade laser waveguide couples directly to the internal laser fields. In a multimode laser, the diode response is correlated with both the instantaneous power and the coupling strength to the diode of each lasing mode. Measurements of the rectified response of diodes integrated in two quantum cascade laser cavities at different locations indicate that the relative diode position strongly influences the laser-diode coupling.

  15. Schottky barrier solar cell

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.; Yeh, Y. C. M. (Inventor)

    1981-01-01

    A method of fabricating a Schottky barrier solar cell is described. The cell consists of a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive. A thin layer of heavily doped n-type polycrystalling germanium is deposited on the substrate after a passivation layer is deposited to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes to serve as a base layer on which a thin layer of gallium arsenide is vapor-epitaxilly grown followed by a thermally-grown oxide layer. A metal layer is deposited on the oxide layer and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer.

  16. Schottky barrier solar cell

    SciTech Connect

    Stirn, R.J.; Yeh, Y.C.M.

    1981-07-01

    A method of fabricating a Schottky barrier solar cell is described. The cell consists of a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive. A thin layer of heavily doped n-type polycrystalling germanium is deposited on the substrate after a passivation layer is deposited to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes to serve as a base layer on which a thin layer of gallium arsenide is vapor-epitaxilly grown followed by a thermally-grown oxide layer. A metal layer is deposited on the oxide layer and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer. Official Gazette of the U.S. Patent and Trademark Office

  17. A user oriented computer program for the analysis of microwave mixers, and a study of the effects of the series inductance and diode capacitance on the performance of some simple mixers

    NASA Technical Reports Server (NTRS)

    Siegel, P. H.; Kerr, A. R.

    1979-01-01

    A user oriented computer program for analyzing microwave and millimeter wave mixers with a single Schottky barrier diode of known I-V and C-V characteristics is described. The program first performs a nonlinear analysis to determine the diode conductance and capacitance waveforms produced by the local oscillator. A small signal linear analysis is then used to find the conversion loss, port impedances, and input noise temperature of the mixer. Thermal noise from the series resistance of the diode and shot noise from the periodically pumped current in the diode conductance are considered. The effects of the series inductance and diode capacitance on the performance of some simple mixer circuits using a conventional Schottky diode, a Schottky diode in which there is no capacitance variation, and a Mott diode are studied. It is shown that the parametric effects of the voltage dependent capacitance of a conventional Schottky diode may be either detrimental or beneficial depending on the diode and circuit parameters.

  18. Effect of ultrasonic loading on current in Mo/n-n{sup +}-Si with Schottky barriers

    SciTech Connect

    Olikh, O. Ya.

    2013-07-15

    The results obtained in experimental studies of the operation of silicon Schottky diodes subjected to ultrasonic loading (oscillations frequency of 9.6 MHz; intensity of longitudinal waves as high as 0.7 W/cm{sup 2}) are reported. A reversible acoustically induced decrease in the Schottky barrier height (to 0.13 V) and an increase in the saturation and reverse current (by as much as 60%) are observed. It is shown that ultrasound does not affect the ideality factor of the diodes and the tunneling component of the reverse current. The process of electron transport is considered within the context of the model of an inhomogeneous Schottky barrier; it is shown that the observed effects can be related to the acoustically induced ionization of defects, which are located at the metal-semiconductor interface.

  19. Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

    SciTech Connect

    Čermák, Jan Rezek, Bohuslav; Koide, Yasuo; Takeuchi, Daisuke

    2014-02-07

    Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent.

  20. Graphene/GaN diodes for ultraviolet and visible photodetectors

    NASA Astrophysics Data System (ADS)

    Lin, Fang; Chen, Shaowen; Meng, Jie; Tse, Geoffrey; Fu, Xuewen; Xu, Fujun; Shen, Bo; Liao, Zhimin; Yu, Dapeng; Nanolab Team

    2015-03-01

    The Schottky diodes based on graphene/GaN interface are fabricated and demonstrated for the dual-wavelength photodetection of ultraviolet (UV) and green lights. The physical mechanisms of the photoelectric response of the diodes with different light wavelengths are different. For UV illumination, the photo-generated carriers lower the Schottky barrier and increase the photocurrent. For green light illumination, as the photon energy is smaller than the bandgap of GaN, the hot electrons excited in graphene via internal photoemission are responsible for the photoelectric response. Using graphene as a transparent electrode, the diodes show a ~ mS photoresponse, providing an alternative route toward multi-wavelength photodetectors.

  1. CORRIGENDUM: The formation and characterization of electrical contacts (Schottky and Ohmic) on gallium nitride nanowires

    NASA Astrophysics Data System (ADS)

    Hwang, Chanoh; Hyung, Jung-Hwan; Lee, Seung-Yong; Jang, Chan-Oh; Kim, Tae-Hong; Choi, Pyung; Lee, Sang-Kwon

    2008-08-01

    The authors acknowledge that the content of this paper is closely related to that of a previous publication, by two of the same authors, which was not cited in their later publication. They agree that their statement '... little work has been reported on nanoscale Ohmic and Schottky contacts to 1D semiconductor nanowires [12, 14]' should also have included the following citation to the work that they had themselves reported: Seung-Yong Lee and Sang-Kwon Lee Current transport mechanism in a metal-GaN nanowire Schottky diode 2008 Nanotechnology 18 495701

  2. The Tevatron resonant Schottky detectors

    SciTech Connect

    Marriner, John; /Fermilab

    1995-09-01

    The following is a description of some studies the author made on the resonant Schottky detectors in the Tevatron. The author doubts that this document contains any information that wasn't known previously, but the hope is that this document will serve as a useful self-contained reference for users of the system.

  3. Plastic Schottky barrier solar cells

    DOEpatents

    Waldrop, James R.; Cohen, Marshall J.

    1984-01-24

    A photovoltaic cell structure is fabricated from an active medium including an undoped, intrinsically p-type organic semiconductor comprising polyacetylene. When a film of such material is in rectifying contact with a magnesium electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates the magnesium layer on the undoped polyacetylene film.

  4. Fluctuations in Schottky barrier heights

    NASA Astrophysics Data System (ADS)

    Mahan, G. D.

    1984-02-01

    A double Schottky barrier is often formed at the grain boundary in polycrystalline semiconductors. The barrier height is shown to fluctuate in value due to the random nature of the impurity positions. The magnitude of the fluctuations is 0.1 eV, and the fluctuations cause the barrier height measured by capacitance to differ from the one measured by electrical conductivity.

  5. Consideration of velocity saturation in the design of GaAs varactor diodes

    NASA Technical Reports Server (NTRS)

    Crowe, Thomas W.; Peatman, William C. B.; Zimmermann, Ruediger; Zimmermann, Ralph

    1993-01-01

    The design of GaAs Schottky barrier varactor diodes is reconsidered in light of the recent discovery of velocity saturation effects in these devices. Experimental data is presented which confirms that improved multiplier performance can be achieved.

  6. Embedding plasmonic nanostructure diodes enhances hot electron emission.

    PubMed

    Knight, Mark W; Wang, Yumin; Urban, Alexander S; Sobhani, Ali; Zheng, Bob Y; Nordlander, Peter; Halas, Naomi J

    2013-04-10

    When plasmonic nanostructures serve as the metallic counterpart of a metal-semiconductor Schottky interface, hot electrons due to plasmon decay are emitted across the Schottky barrier, generating measurable photocurrents in the semiconductor. When the plasmonic nanostructure is atop the semiconductor, only a small percentage of hot electrons are excited with a wavevector permitting transport across the Schottky barrier. Here we show that embedding plasmonic structures into the semiconductor substantially increases hot electron emission. Responsivities increase by 25× over planar diodes for embedding depths as small as 5 nm. The vertical Schottky barriers created by this geometry make the plasmon-induced hot electron process the dominant contributor to photocurrent in plasmonic nanostructure-diode-based devices. PMID:23452192

  7. Planar GaAs diodes for THz frequency mixing applications

    NASA Technical Reports Server (NTRS)

    Bishop, William L.; Crowe, Thomas W.; Mattauch, Robert J.; Dossal, Hasan

    1992-01-01

    Schottky barrier diodes for terahertz applications are typically fabricated as a micron to sub-micron circular anode metallization on GaAs which is contacted with a sharp wire (whisker). This structure has the benefits of the simplicity of the fabrication of the diode chip, the minimal shunt capacitance of the whisker contact and the ability of the whisker wire to couple energy to the diode. However, whisker-contacted diodes are costly to assembly and difficult to qualify for space applications. Also, complex receiver systems which require many diodes are difficult to assemble. The objective of this paper is to discuss the advantages of planar Schottky diodes for high frequency receiver applications and to summarize the problems of advancing the planar technology to the terahertz frequency range. Section 2 will discuss the structure, fabrication and performance of state-of-the-art planar Schottky diodes. In Section 3 the problems of designing and fabricating planar diodes for terahertz frequency operation are discussed along with a number of viable solutions. Section 4 summarizes the need for further research and cooperation between diode designers and RF engineers.

  8. Measurements of Schottky barrier heights formed from metals and 2D transition metal dichalcogedides

    NASA Astrophysics Data System (ADS)

    Kim, Changsik; Moon, Inyong; Nam, Seunggeol; Cho, Yeonchoo; Shin, Hyeon-Jin; Park, Seongjun; Yoo, Won Jong

    Schottky barrier height (SBH) is an important parameter that needs to be considered for designing electronic devices. However, for two dimensional (2D) materials based devices, SBH control is limited by 2D structure induced quantum confinement and 2D surface induced Fermi level pinning. In this work, we explore differences in measuring SBH between 2D and 3D materials. Recently, low temperature I-V measurement has been reported to extract SBH based on thermionic emission equation for Schottky diode. However, 2D devices are not real Schottky diode in that both source and drain metal electrodes make Schottky contact. According to our experimental results, SBH extracted from linear slope of ln (I/T3/2) against 1/T show widely diverse values, dependent on applied voltage bias and tested temperature which affect carrier transport including tunneling or thermionic emission across the metal-2D material interface. In this work, we wish to demonstrate the method to determine SBH and Fermi level pinning which are attributed to 2D transition metal dichalcogedides, differently from conventional 3D materials. .

  9. Fabrication and characterization of graphene/AlGaN/GaN ultraviolet Schottky photodetector

    NASA Astrophysics Data System (ADS)

    Kumar, M.; Jeong, H.; Polat, K.; Okyay, A. K.; Lee, D.

    2016-07-01

    We report on the fabrication and characterization of a Schottky ultraviolet graphene/AlGaN/GaN photodetector (PD). The fabricated device clearly exhibits rectification behaviour, indicating that the Schottky barrier is formed between the AlGaN and the mechanically transferred graphene. The Schottky parameters are evaluated using an equivalent circuit with two diodes connected back-to-back in series. The PD shows a low dark current of 4.77  ×  10-12 A at a bias voltage of  -2.5 V. The room temperature current-voltage (I-V) measurements of the graphene/AlGaN/GaN Schottky PD exhibit a large photo-to-dark contrast ratio of more than four orders of magnitude. Furthermore, the device shows peak responsivity at a wavelength of 350 nm, corresponding to GaN band edge and a small hump at 300 nm associated to the AlGaN band edge. In addition, we examine the behaviour of Schottky PDs with responsivities of 0.56 and 0.079 A W-1 at 300 and 350 nm, respectively, at room temperature.

  10. Monolithic watt-level millimeter-wave diode-grid frequency tripler array

    NASA Technical Reports Server (NTRS)

    Hwu, R. J.; Luhmann, N. C., Jr.; Rutledge, D. B.; Hancock, B.; Lieneweg, U.

    1988-01-01

    In order to provide watt-level CW output power throughout the millimeter and submillimeter wave region, thousands of solid-state diodes have been monolithically integrated using a metal grid to produce a highly efficient frequency multiplier. Devices considered include GaAs Schottky diodes, thin MOS diodes, and GaAs Barrier-Intrinsic-N(+)diodes. The performance of the present compact low-cost device has been theoretically and experimentally validated.

  11. Modelling the inhomogeneous SiC Schottky interface

    NASA Astrophysics Data System (ADS)

    Gammon, P. M.; Pérez-Tomás, A.; Shah, V. A.; Vavasour, O.; Donchev, E.; Pang, J. S.; Myronov, M.; Fisher, C. A.; Jennings, M. R.; Leadley, D. R.; Mawby, P. A.

    2013-12-01

    For the first time, the I-V-T dataset of a Schottky diode has been accurately modelled, parameterised, and fully fit, incorporating the effects of interface inhomogeneity, patch pinch-off and resistance, and ideality factors that are both heavily temperature and voltage dependent. A Ni/SiC Schottky diode is characterised at 2 K intervals from 20 to 320 K, which, at room temperature, displays low ideality factors (n < 1.01) that suggest that these diodes may be homogeneous. However, at cryogenic temperatures, excessively high (n > 8), voltage dependent ideality factors and evidence of the so-called "thermionic field emission effect" within a T0-plot, suggest significant inhomogeneity. Two models are used, each derived from Tung's original interactive parallel conduction treatment of barrier height inhomogeneity that can reproduce these commonly seen effects in single temperature I-V traces. The first model incorporates patch pinch-off effects and produces accurate and reliable fits above around 150 K, and at current densities lower than 10-5 A cm-2. Outside this region, we show that resistive effects within a given patch are responsible for the excessive ideality factors, and a second simplified model incorporating these resistive effects as well as pinch-off accurately reproduces the entire temperature range. Analysis of these fitting parameters reduces confidence in those fits above 230 K, and questions are raised about the physical interpretation of the fitting parameters. Despite this, both methods used are shown to be useful tools for accurately reproducing I-V-T data over a large temperature range.

  12. Silicon Carbide Diodes Characterization at High Temperature and Comparison With Silicon Devices

    NASA Technical Reports Server (NTRS)

    Lebron-Velilla, Ramon C.; Schwarze, Gene E.; Gardner, Brent G.; Adams, Jerry D., Jr.

    2004-01-01

    Commercially available silicon carbide (SiC) Schottky diodes from different manufacturers rated at 200, 300, 600, and 1200 V, were electrically tested and characterized as a function of temperature up to 300 C. Electrical tests included both steady state and dynamic tests. Steady state tests produced forward and reverse I-V characteristic curves. Transient tests evaluated the switching performance of the diodes in either a hard-switched DC to DC buck converter or a half-bridge boost converter. For evaluation and comparison purposes, the same tests were performed with current state-of-the-art ultra fast silicon (Si) pn-junction diodes of similar ratings and also a Si Schottky diode. The comparisons made were forward voltage drop at rated current, reverse current at rated voltage, and turn-off peak reverse recovery current and reverse recovery time. In addition, efficiency measurements were taken for the buck DC to DC converter using both the SiC Schottky diodes and the Si pn-junction diodes at different temperatures and frequencies. The test results showed that at high temperature, the forward voltage drop for SiC Schottky diodes is higher than the forward drop of the ultra fast Si pn-junction diodes. As the temperature increased, the forward voltage drop of the SiC Schottky increased while for the ultra fast Si pn-junction diodes, the forward voltage drop decreased as temperature increased. For the elevated temperature steady state reverse voltage tests, the SiC Schottky diodes showed low leakage current at their rated voltage. Likewise, for the transient tests, the SiC Schottky diodes displayed low reverse recovery currents over the range of temperatures tested. Conversely, the Si pn-junction diodes showed increasing peak reverse current values and reverse recovery times with increasing temperature. Efficiency measurements in the DC to DC buck converter showed the advantage of the SiC Schottky diodes over the ultra fast Si pn-junction diodes, especially at the

  13. Characterization of vertical Au/β-Ga2O3 single-crystal Schottky photodiodes with MBE-grown high-resistivity epitaxial layer

    NASA Astrophysics Data System (ADS)

    X, Z. Liu; C, Yue; C, T. Xia; W, L. Zhang

    2016-01-01

    High-resistivity β-Ga2O3 thin films were grown on Si-doped n-type conductive β-Ga2O3 single crystals by molecular beam epitaxy (MBE). Vertical-type Schottky diodes were fabricated, and the electrical properties of the Schottky diodes were studied in this letter. The ideality factor and the series resistance of the Schottky diodes were estimated to be about 1.4 and 4.6× 106 Ω. The ionized donor concentration and the spreading voltage in the Schottky diodes region are about 4 × 1018 cm-3 and 7.6 V, respectively. The ultra-violet (UV) photo-sensitivity of the Schottky diodes was demonstrated by a low-pressure mercury lamp illumination. A photoresponsivity of 1.8 A/W and an external quantum efficiency of 8.7 × 102% were observed at forward bias voltage of 3.8 V, the proper driving voltage of read-out integrated circuit for UV camera. The gain of the Schottky diode was attributed to the existence of a potential barrier in the i-n junction between the MBE-grown highly resistive β-Ga2O3 thin films and the n-type conductive β-Ga2O3 single-crystal substrate. Project supported by the National Nature Science Foundation of China (Grant No. 61223002) the Science and Technology Commission of Shanghai Municipality, China (Grant No. 13111103700), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 2012018530003).

  14. X-Ray Photoelectron Spectroscopy Study of the Heating Effects on Pd/6H-SiC Schottky Structure

    NASA Technical Reports Server (NTRS)

    Chen, Liang-Yu; Hunter, Gary W.; Neudeck, Philip G.; Knight, Dak

    1998-01-01

    X-ray photoelectron spectroscopy is used to study the effects of heat treatment on the Pd/6H-SiC Schottky diode structure. After heating the structure at 425 C for 140 h, a very thin surface layer of PdO mixed with SiO(x) formed on the palladium surface of the Schottky structure. Heat treatment promoted interfacial diffusion and reaction which significantly broadened the interfacial region. In the interfacial region, the palladium concentration decreases with depth, and the interfacial products are Pd(x)Si (x = 1,2,3,4). In the high Pd concentration regions, Pd4Si is the major silicide component while gr and Pd2Si are major components in the low Pd concentration region. At the center of the interface, where the total palladium concentration equals that of silicon, the concentrations of palladium associated with various palladium silicides (Pd(x)Si, x= 1,2,3,4) are approximately equal. The surface passivation layer composed of PdO and SiO, may significantly affect the electronic and catalytic properties of the surface of the Schottky diode which plays a major role in gas detection. The electronic properties of the Schottky structure may be dominated by a (Pd+Pd(x)Si)/SiC interface. In order to stabilize the properties of the Schottky structure the surface and interface diffusion and reactions must be controlled.

  15. Schottky Barrier CdTe(Cl) Detectors for Planetary Missions

    NASA Astrophysics Data System (ADS)

    Eisen, Yosef; Floyd, Samuel

    2002-10-01

    Schottky barrier cadmium telluride (CdTe) radiation detectors of dimensions 2mm × 2mm × 1mm and segmented monolithic 3cm × 3 cm × 1mm are under study at GSFC for future NASA planetary instruments. These instruments will perform x-ray fluorescence spectrometry of the surface and monitor the solar x-ray flux spectrum, the excitation source for the characteristic x-rays emitted from the planetary body. The Near Earth Asteroid Rendezvous (NEAR) mission is the most recent example of such a remote sensing technique. Its x-ray fluorescence detectors were gas proportional counters with a back up Si PIN solar monitor. Analysis of NEAR data has shown the necessity to develop a solar x-ray detector with efficiency extending to 30keV. Proportional counters and Si diodes have low sensitivity above 9keV. Our 2mm × 2mm × 1mm CdTe operating at -30°C possesses an energy resolution of 250eV FWHM for 55Fe with unit efficiency to up to 30keV. This is an excellent candidate for a solar monitor. Another ramification of the NEAR data is a need to develop a large area detector system, 20-30 cm2, with cosmic ray charged particle rejection, for measuring the characteristic radiation. A 3cm × 3cm × 1mm Schottky CdTe segmented monolithic detector is under investigation for this purpose. A tiling of 2-3 such detectors will result in the desired area. The favorable characteristics of Schottky CdTe detectors, the system design complexities when using CdTe and its adaptation to future missions will be discussed.

  16. Temperature dependence of Schottky diode characteristics prepared with photolithography technique

    NASA Astrophysics Data System (ADS)

    Korucu, Demet; Turut, Abdulmecit

    2014-11-01

    A Richardson constant (RC) of 8.92 Acm-2K-2 from the conventional Richardson plot has been obtained because the current-voltage data of the device quite well obey the thermionic emission (TE) model in 190-320 K range. The experimental nT versus T plot of the device has given a value of T0 = 7.40 K in temperature range of 160-320 K. The deviations from the TE current mechanism at temperatures below 190 K have been ascribed to the patches introduced by lateral inhomogeneity of the barrier heights. Therefore, an experimental RC value of 7.49 A(cmK)-2 has been obtained by considering Tung's patch model in the temperature range of 80-190 K. This value is in very close agreement with the known value of 8.16 Acm-2K-2 for n-type GaAs.

  17. Improved cell design for Schottky barrier infrared detector arrays

    NASA Astrophysics Data System (ADS)

    Shepherd, Freeman D.; Mooney, Jonathan M.; Tzannes, Alexis P.; Murguia, James E.

    1995-09-01

    The responsivity of large scale platinum silicide arrays, having small pixels, is low compared to the responsivity of large area test diodes fabricated on the same wafer. Often, the responsivity loss is described by assigning a lower Fowler emission coefficient to the detectors. We find the reduced responsivity to be the direct result of a reduction in the effective active area of the detector. This reduction in effective active area becomes more pronounced as the detector cell size is reduced. We provide a simple model for the area reduction in terms of modulation of detector Schottky potential by the underlying depletion region of the detector guard ring. We also suggest changes in the detector array unit cell design, which will maximize responsivity.

  18. Silicon Carbide Diodes Performance Characterization and Comparison With Silicon Devices

    NASA Technical Reports Server (NTRS)

    Lebron-Velilla, Ramon C.; Schwarze, Gene E.; Trapp, Scott

    2003-01-01

    Commercially available silicon carbide (SiC) Schottky diodes from different manufacturers were electrically tested and characterized at room temperature. Performed electrical tests include steady state forward and reverse I-V curves, as well as switching transient tests performed with the diodes operating in a hard switch dc-to-dc buck converter. The same tests were performed in current state of the art silicon (Si) and gallium arsenide (GaAs) Schottky and pn junction devices for evaluation and comparison purposes. The SiC devices tested have a voltage rating of 200, 300, and 600 V. The comparison parameters are forward voltage drop at rated current, reverse current at rated voltage and peak reverse recovery currents in the dc to dc converter. Test results show that steady state characteristics of the tested SiC devices are not superior to the best available Si Schottky and ultra fast pn junction devices. Transient tests reveal that the tested SiC Schottky devices exhibit superior transient behavior. This is more evident at the 300 and 600 V rating where SiC Schottky devices showed drastically lower reverse recovery currents than Si ultra fast pn diodes of similar rating.

  19. Direct probing of Schottky barriers in Si nanowire Schottky barrier field effect transistors.

    PubMed

    Martin, Dominik; Heinzig, Andre; Grube, Matthias; Geelhaar, Lutz; Mikolajick, Thomas; Riechert, Henning; Weber, Walter M

    2011-11-18

    This work elucidates the role of the Schottky junction in the electronic transport of nanometer-scale transistors. In the example of Schottky barrier silicon nanowire field effect transistors, an electrical scanning probe technique is applied to examine the charge transport effects of a nanometer-scale local top gate during operation. The results prove experimentally that Schottky barriers control the charge carrier transport in these devices. In addition, a proof of concept for a reprogrammable nonvolatile memory device based on band bending at the Schottky barriers will be shown.

  20. Extreme ultraviolet detection using AlGaN-on-Si inverted Schottky photodiodes

    SciTech Connect

    Malinowski, Pawel E.; Mertens, Robert; Van Hoof, Chris; Duboz, Jean-Yves; Semond, Fabrice; Frayssinet, Eric; Verhoeve, Peter; Giordanengo, Boris; BenMoussa, Ali

    2011-04-04

    We report on the fabrication of aluminum gallium nitride (AlGaN) Schottky diodes for extreme ultraviolet (EUV) detection. AlGaN layers were grown on silicon wafers by molecular beam epitaxy with the conventional and inverted Schottky structure, where the undoped, active layer was grown before or after the n-doped layer, respectively. Different current mechanisms were observed in the two structures. The inverted Schottky diode was designed for the optimized backside sensitivity in the hybrid imagers. A cut-off wavelength of 280 nm was observed with three orders of magnitude intrinsic rejection ratio of the visible radiation. Furthermore, the inverted structure was characterized using a EUV source based on helium discharge and an open electrode design was used to improve the sensitivity. The characteristic He I and He II emission lines were observed at the wavelengths of 58.4 nm and 30.4 nm, respectively, proving the feasibility of using the inverted layer stack for EUV detection.

  1. Schottky barrier height tuning using P+ DSS for NMOS contact resistance reduction

    NASA Astrophysics Data System (ADS)

    Khaja, Fareen Adeni; Rao, K. V.; Ni, Chi-Nung; Muthukrishnan, Shankar; Lei, Jianxin; Darlark, Andrew; Peidous, Igor; Brand, Adam; Henry, Todd; Variam, Naushad

    2012-11-01

    Nickel silicide (NiSi) contacts are adopted in advanced CMOS technology nodes as they demonstrate several benefits such as low resistivity, low Si consumption and formation temperature. But a disadvantage of NiSi contacts is that they exhibit high electron Schottky barrier height (SBH), which results in high contact resistance (Rc) and reduces the NMOS drive current. To reduce SBH for NMOS, we used phosphorous (P) ion implantation into NiPt silicide with optimized anneal in order to form dopant segregated Schottky (DSS). Electrical characterization was performed using test structures such as Transmission Line Model, Cross-Bridge Kelvin Resistor, Van der Pauw and diodes to extract Rc and understand the effects of P+ DSS on ΦBn tuning. Material characterization was performed using SIMS, SEM and TEM analysis. We report ˜45% reduction in Rc over reference sample by optimizing ion implantation and anneal conditions (spike RTA, milli-second laser anneals (DSA)).

  2. Aspects of SiC diode assembly using Ag technology

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Marcin; Guziewicz, Marek; Kisiel, Ryszard

    2013-07-01

    The aim of our paper is to consider the possibility of applying pure Ag technology for assembly of SiC Schottky diode into a ceramic package able to work at temperatures up to 350°C. Ag micropowder was used for assembly SiC structure to DBC interposer of the ceramic package. Ag wire bonds as well as flip-chip technology using Ag balls were used as material for interconnection systems. The parameters of I-V characteristics were used as a quality factor to determine the Schottky diode after hermetization into ceramic package as well as after ageing in air at 350°C in comparison with characteristics of bare SiC diode.

  3. Graphene/GaN diodes for ultraviolet and visible photodetectors

    SciTech Connect

    Lin, Fang; Chen, Shao-Wen; Meng, Jie; Tse, Geoffrey; Fu, Xue-Wen; Xu, Fu-Jun; Shen, Bo; Liao, Zhi-Min E-mail: yudp@pku.edu.cn; Yu, Da-Peng E-mail: yudp@pku.edu.cn

    2014-08-18

    The Schottky diodes based on graphene/GaN interface are fabricated and demonstrated for the dual-wavelength photodetection of ultraviolet (UV) and green lights. The physical mechanisms of the photoelectric response of the diodes with different light wavelengths are different. For UV illumination, the photo-generated carriers lower the Schottky barrier and increase the photocurrent. For green light illumination, as the photon energy is smaller than the bandgap of GaN, the hot electrons excited in graphene via internal photoemission are responsible for the photoelectric response. Using graphene as a transparent electrode, the diodes show a ∼mS photoresponse, providing an alternative route toward multi-wavelength photodetectors.

  4. Graphene/GaN diodes for ultraviolet and visible photodetectors

    NASA Astrophysics Data System (ADS)

    Lin, Fang; Chen, Shao-Wen; Meng, Jie; Tse, Geoffrey; Fu, Xue-Wen; Xu, Fu-Jun; Shen, Bo; Liao, Zhi-Min; Yu, Da-Peng

    2014-08-01

    The Schottky diodes based on graphene/GaN interface are fabricated and demonstrated for the dual-wavelength photodetection of ultraviolet (UV) and green lights. The physical mechanisms of the photoelectric response of the diodes with different light wavelengths are different. For UV illumination, the photo-generated carriers lower the Schottky barrier and increase the photocurrent. For green light illumination, as the photon energy is smaller than the bandgap of GaN, the hot electrons excited in graphene via internal photoemission are responsible for the photoelectric response. Using graphene as a transparent electrode, the diodes show a ˜mS photoresponse, providing an alternative route toward multi-wavelength photodetectors.

  5. Schottky barrier MOSFET systems and fabrication thereof

    DOEpatents

    Welch, J.D.

    1997-09-02

    (MOS) device systems-utilizing Schottky barrier source and drain to channel region junctions are disclosed. Experimentally derived results which demonstrate operation of fabricated N-channel and P-channel Schottky barrier (MOSFET) devices, and of fabricated single devices with operational characteristics similar to (CMOS) and to a non-latching (SRC) are reported. Use of essentially non-rectifying Schottky barriers in (MOS) structures involving highly doped and the like and intrinsic semiconductor to allow non-rectifying interconnection of, and electrical accessing of device regions is also disclosed. Insulator effected low leakage current device geometries and fabrication procedures therefore are taught. Selective electrical interconnection of drain to drain, source to drain, or source to source, of N-channel and/or P-channel Schottky barrier (MOSFET) devices formed on P-type, N-type and Intrinsic semiconductor allows realization of Schottky Barrier (CMOS), (MOSFET) with (MOSFET) load, balanced differential (MOSFET) device systems and inverting and non-inverting single devices with operating characteristics similar to (CMOS), which devices can be utilized in modulation, as well as in voltage controlled switching and effecting a direction of rectification. 89 figs.

  6. Schottky barrier MOSFET systems and fabrication thereof

    DOEpatents

    Welch, James D.

    1997-01-01

    (MOS) device systems-utilizing Schottky barrier source and drain to channel region junctions are disclosed. Experimentally derived results which demonstrate operation of fabricated N-channel and P-channel Schottky barrier (MOSFET) devices, and of fabricated single devices with operational characteristics similar to (CMOS) and to a non-latching (SRC) are reported. Use of essentially non-rectifying Schottky barriers in (MOS) structures involving highly doped and the like and intrinsic semiconductor to allow non-rectifying interconnection of, and electrical accessing of device regions is also disclosed. Insulator effected low leakage current device geometries and fabrication procedures therefore are taught. Selective electrical interconnection of drain to drain, source to drain, or source to source, of N-channel and/or P-channel Schottky barrier (MOSFET) devices formed on P-type, N-type and Intrinsic semiconductor allows realization of Schottky Barrier (CMOS), (MOSFET) with (MOSFET) load, balanced differential (MOSFET) device systems and inverting and non-inverting single devices with operating characteristics similar to (CMOS), which devices can be utilized in modulation, as well as in voltage controled switching and effecting a direction of rectification.

  7. Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature

    NASA Astrophysics Data System (ADS)

    Villa, E.; Aja, B.; de la Fuente, L.; Artal, E.

    2016-01-01

    This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

  8. Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature.

    PubMed

    Villa, E; Aja, B; de la Fuente, L; Artal, E

    2016-01-01

    This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

  9. Room-Temperature Electrical Characteristics of Pd/SiC Diodes with Embedded Au Nanoparticles at the Interface

    NASA Astrophysics Data System (ADS)

    Ruffino, F.; Crupi, I.; Irrera, A.; Grimaldi, M. G.

    2010-11-01

    We investigate the effects of localized controlled nanometric inhomogeneities, represented by Au nanoparticles, on the electrical properties of Pd/SiC Schottky diodes. In particular, we investigate the effects of the nanoparticle radius R on the current-voltage characteristics. The main result concerns the strong dependence of the effective Schottky barrier height of the Pd/SiC contact on R, giving a practical technique to tailor, in a wide range, such a barrier height by simply changing the process parameters during the diode preparation. Then, from a basic understanding point of view, such data allow us to test the Tung model describing the effects of inhomogeneities on the electrical properties of Schottky diodes. These nanostructured diodes are proposed as possible components of integrated complex nanoelectronic devices.

  10. The nature of electrical interaction of Schottky contacts

    SciTech Connect

    Torkhov, N. A.

    2011-08-15

    Electrical interaction between metal-semiconductor contacts combined in a diode matrix with a Schottky barrier manifests itself in an appreciable variation in their surface potentials and static current-volt-characteristics. The necessary condition for appearance of electrical interaction between such contacts consists in the presence of a peripheral electric field (a halo) around them; this field propagates to a fairly large distances (<30 {mu}m). The sufficient condition is the presence of regions where the above halos overlap. It has been shown that variation in the surface potential and the current-voltage characteristics of contacts occurs under the effect of the intrinsic electric field of the contact's periphery and also under the effect of an electric field at matrix periphery; the latter field is formed as a result of superposition of electric fields of halos which form its contacts. The degree of the corresponding effect is governed by the distance between contacts and by the total charge of the space charge regions for all contacts of the matrix: their number, sizes (diameter D{sub i,j}), concentration of doping impurities in the semiconductor N{sub D}, and physical nature of a metal-semiconductor system with a Schottky barrier (with the barrier height {phi}{sub b}). It is established that bringing the contacts closer leads to a relative decrease in the threshold value of the 'dead' zone in the forward current-voltage characteristics, an increase in the effective height of the barrier, and an insignificant increase in the nonideality factor. An increase in the total area of contacts (a total electric charge in the space charge region) in the matrix brings about an increase in the threshold value of the 'dead' zone, a relative decrease in the effective barrier height, and an insignificant increase in the ideality factor.

  11. Giant spin-torque diode sensitivity in the absence of bias magnetic field.

    PubMed

    Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A; Krivorotov, Ilya N; Ocker, Berthold; Langer, Juergen; Wang, Kang L; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

    2016-01-01

    Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW(-1) at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors. PMID:27052973

  12. Giant spin-torque diode sensitivity in the absence of bias magnetic field.

    PubMed

    Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A; Krivorotov, Ilya N; Ocker, Berthold; Langer, Juergen; Wang, Kang L; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

    2016-04-07

    Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW(-1) at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors.

  13. Giant spin-torque diode sensitivity in the absence of bias magnetic field

    PubMed Central

    Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A.; Krivorotov, Ilya N.; Ocker, Berthold; Langer, Juergen; Wang, Kang L.; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

    2016-01-01

    Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW−1 at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors. PMID:27052973

  14. A Unique 520-590 GHz Biased Subharmonically-pumped Schottky Mixer

    NASA Technical Reports Server (NTRS)

    Schlecht, Erich; Gill, John; Dengler, Robert; Lin, Robert; Tsang, Ray; Mehdi, Imran

    2007-01-01

    We report on the design and performance of a novel broadband, biased, subharmonic 520-590 GHz fix-tuned frequency mixer that utilizes planar Schottky diodes. The suspended stripline circuit is fabricated on a GaAs membrane mounted in a split waveguide block. The chip is supported by thick beam leads that are also used to provide precise radio frequency (RF) grounding, RF coupling and dc/intermediate frequency connections. At room temperature, the mixer has a measured double sideband noise temperature of 3000 to 4000 K across the design band.

  15. Schottky contact formation on polar and non-polar AlN

    SciTech Connect

    Reddy, Pramod; Bryan, Isaac; Bryan, Zachary; Tweedie, James; Kirste, Ronny; Collazo, Ramon; Sitar, Zlatko

    2014-11-21

    The interfaces of m- and c-plane AlN with metals of different work functions and electro-negativities were characterized and the Schottky barrier heights were measured. The Schottky barrier height was determined by measuring the valence band maximum (VBM) with respect to the Fermi level at the surface (interface) before (after) metallization. VBM determination included accurate modeling and curve fitting of density of states at the valence band edge with the XPS data. The experimental behavior of the barrier heights could not be explained by the Schottky-Mott model and was modeled using InterFace-Induced Gap States (IFIGS). A slope parameter (S{sub X}) was used to incorporate the density of surface states and is a measure of Fermi level pinning. The experimental barriers followed theoretical predictions with a barrier height at the surface Fermi level (Charge neutrality level (CNL)) of ∼2.1 eV (∼2.7 eV) on m-plane (c-plane) and S{sub X} ∼ 0.36 eV/Miedema unit. Slope parameter much lower than 0.86 implied a surface/interface states dominated behavior with significant Fermi level pinning and the measured barrier heights were close to the CNL. Titanium and zirconium provided the lowest barriers (1.6 eV) with gold providing the highest (2.3 eV) among the metals analyzed on m-plane. It was consistently found that barrier heights decreased from metal polar to non-polar surfaces, in general, due to an increasing CNL. The data indicated that charged IFIGS compensate spontaneous polarization charge. These barrier height and slope parameter measurements provided essential information for designing Schottky diodes and other contact-based devices on AlN.

  16. Schottky contact formation on polar and non-polar AlN

    SciTech Connect

    Reddy, P; Bryan, I; Bryan, Z; Tweedie, J; Kirste, R; Collazo, R; Sitar, Z

    2014-11-21

    The interfaces of m-and c-plane AlN with metals of different work functions and electro-negativities were characterized and the Schottky barrier heights were measured. The Schottky barrier height was determined by measuring the valence band maximum (VBM) with respect to the Fermi level at the surface (interface) before (after) metallization. VBM determination included accurate modeling and curve fitting of density of states at the valence band edge with the XPS data. The experimental behavior of the barrier heights could not be explained by the Schottky-Mott model and was modeled using InterFace-Induced Gap States (IFIGS). A slope parameter (S-X) was used to incorporate the density of surface states and is a measure of Fermi level pinning. The experimental barriers followed theoretical predictions with a barrier height at the surface Fermi level (Charge neutrality level (CNL)) of similar to 2.1 eV (similar to 2.7 eV) on m-plane (c-plane) and S-X similar to 0.36 eV/Miedema unit. Slope parameter much lower than 0.86 implied a surface/interface states dominated behavior with significant Fermi level pinning and the measured barrier heights were close to the CNL. Titanium and zirconium provided the lowest barriers (1.6 eV) with gold providing the highest (2.3 eV) among the metals analyzed on m-plane. It was consistently found that barrier heights decreased from metal polar to non-polar surfaces, in general, due to an increasing CNL. The data indicated that charged IFIGS compensate spontaneous polarization charge. These barrier height and slope parameter measurements provided essential information for designing Schottky diodes and other contact-based devices on AlN. (C) 2014 AIP Publishing LLC.

  17. P-doping-free III-nitride high electron mobility light-emitting diodes and transistors

    SciTech Connect

    Li, Baikui; Tang, Xi; Chen, Kevin J.; Wang, Jiannong

    2014-07-21

    We report that a simple metal-AlGaN/GaN Schottky diode is capable of producing GaN band-edge ultraviolet emission at 3.4 eV at a small forward bias larger than ∼2 V at room temperature. Based on the surface states distribution of AlGaN, a mature impact-ionization-induced Fermi-level de-pinning model is proposed to explain the underlying mechanism of the electroluminescence (EL) process. By experimenting with different Schottky metals, Ni/Au and Pt/Au, we demonstrated that this EL phenomenon is a “universal” property of metal-AlGaN/GaN Schottky diodes. Since this light-emitting Schottky diode shares the same active structure and fabrication processes as the AlGaN/GaN high electron mobility transistors, straight-forward and seamless integration of photonic and electronic functional devices has been demonstrated on doping-free III-nitride heterostructures. Using a semitransparent Schottky drain electrode, an AlGaN/GaN high electron mobility light-emitting transistor is demonstrated.

  18. The 20 GHz solid state transmitter design, impatt diode development and reliability assessment

    NASA Technical Reports Server (NTRS)

    Picone, S.; Cho, Y.; Asmus, J. R.

    1984-01-01

    A single drift gallium arsenide (GaAs) Schottky barrier IMPATT diode and related components were developed. The IMPATT diode reliability was assessed. A proof of concept solid state transmitter design and a technology assessment study were performed. The transmitter design utilizes technology which, upon implementation, will demonstrate readiness for development of a POC model within the 1982 time frame and will provide an information base for flight hardware capable of deployment in a 1985 to 1990 demonstrational 30/20 GHz satellite communication system. Life test data for Schottky barrier GaAs diodes and grown junction GaAs diodes are described. The results demonstrate the viability of GaAs IMPATTs as high performance, reliable RF power sources which, based on the recommendation made herein, will surpass device reliability requirements consistent with a ten year spaceborne solid state power amplifier mission.

  19. Analysis of Carbon Nanotube Metal-Semiconductor Diode Device

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryan (Technical Monitor)

    2002-01-01

    We study recently reported drain current Id-drain voltage Vd characteristics of a carbon nanotube metal semiconductor diode device with the gate voltage Vg applied to modulate the carrier density in the nanotube. The diode was kink-shaped at the metal-semiconductor interface. It was shown that (1) larger negative Vg blocked Id more effectively in the negative Vd region, resulting in the rectifying Id-Vd characteristics, and that (2) positive Vg allowed Id in the both Vd polarities, resulting in the non-rectifying characteristics. The negative Vd was the Schottky reverse direction, judging from the negligible Id behavior for a wide region of -4 V less than Vd less than 0 V, with Vg = -4 V. Such negative Vg would attract positive charges from the metallic electrodes (charge reservoir) to the nanotube and lower the nanotube Fermi energy (EF). With larger negative Vg, the experiment showed that the Schottky forward direction (Vd greater than 0) had a smaller turn-on voltage and the Schottky reverse direction (Vd less than 0) was more resistant to the tunneling breakdown. Therefore, the majority carriers in the transport would be electrons since they can see a lower tunneling barrier (shallower built-in potential) in the forward direction when EF is lowered, and a thicker tunneling barrier (Schottky barrier) in the reverse direction due to the reduction in the electron density when EF is lowered.

  20. Plastic Schottky-barrier solar cells

    DOEpatents

    Waldrop, J.R.; Cohen, M.J.

    1981-12-30

    A photovoltaic cell structure is fabricated from an active medium including an undoped polyacetylene, organic semiconductor. When a film of such material is in rectifying contact with a metallic area electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates a magnesium layer on the undoped polyacetylene film. With the proper selection and location of elements a photovoltaic cell structure and solar cell are obtained.

  1. Liquid junction schottky barrier solar cell

    DOEpatents

    Williams, Richard

    1980-01-01

    A mixture of ceric ions (Ce.sup.+4) and cerous ions (Ce.sup.+3) in an aqueous electrolyte solution forms a Schottky barrier at the interface between an active region of silicon and the electrolyte solution. The barrier height obtained for hydrogenated amorphous silicon using the Ce.sup.+4 /Ce.sup.+3 redox couple is about 1.7 eV.

  2. Analysis of leakage current mechanisms in Pt/Au Schottky contact on Ga-polarity GaN by Frenkel-Poole emission and deep level studies

    SciTech Connect

    Rao, Peta Koteswara; Park, Byungguon; Lee, Sang-Tae; Noh, Young-Kyun; Kim, Moon-Deock; Oh, Jae-Eung

    2011-07-01

    We report the Frenkel-Poole emission in Pt/Au Schottky contact on Ga-polarity GaN grown by molecular beam epitaxy using current-voltage-temperature (I-V-T) characteristics in the temperature ranging from 200 K to 375 K. Using thermionic emission model, the estimated Schottky barrier height is 0.49 eV at 200 K and 0.83 eV at 375 K, respectively, and it is observed that the barrier height increases with increase in temperature. The extracted emission barrier height ({phi}{sub t}) for Ga-polarity GaN Schottky diode by Frenkel-Poole theory is about 0.15 eV. Deep level transient spectroscopy study shows a deep level with activation energy of 0.44 eV, having capture cross-section 6.09 x 10{sup -14} cm{sup 2}, which is located between the metal and semiconductor interface, and trap nature is most probably associated with dislocations in Ga-polarity GaN. The analysis of I-V-T characteristics represents that the leakage current is due to effects of electrical field and temperature on the emission of electron from a trap state near the metal-semiconductor interface into continuum states associated with conductive dislocations in Ga-polarity GaN Schottky diode.

  3. Temperature-dependent current-voltage characteristics in thermally annealed ferromagnetic Co/n-GaN Schottky contacts

    NASA Astrophysics Data System (ADS)

    Ejderha, Kadir; Yıldırm, N.; Turut, A.

    2014-11-01

    Co/n-GaN SDs has been prepared by magnetron DC sputtering technique. The Co/n-GaN SDs have annealed at 600 °C after a post-deposition. The diode parameters such as the ideality factor, barrier height and Richardson constant have been determined by thermionic emission (TE) equation within the measurement temperature range 60-320 K by the steps of 20 K in the dark. It has been seen that the parameters depend on the measurement temperature indicating the presence of a lateral inhomogeneity in the Schottky barrier. Therefore, it has been modified the experimental data by the thermionic emission (TE) mechanism with Gaussian distribution of the barrier heights by using Tung's theoretical approach that the Schottky barrier consists of laterally inhomogeneous patches of different barrier heights. Thus, the modified Richardson plot according to Tung's barrier inhomogeneity model [8] has given a Richardson constant of 27.66 A/(cm2 K2).

  4. Schottky barrier amorphous silicon solar cell with thin doped region adjacent metal Schottky barrier

    DOEpatents

    Carlson, David E.; Wronski, Christopher R.

    1979-01-01

    A Schottky barrier amorphous silicon solar cell incorporating a thin highly doped p-type region of hydrogenated amorphous silicon disposed between a Schottky barrier high work function metal and the intrinsic region of hydrogenated amorphous silicon wherein said high work function metal and said thin highly doped p-type region forms a surface barrier junction with the intrinsic amorphous silicon layer. The thickness and concentration of p-type dopants in said p-type region are selected so that said p-type region is fully ionized by the Schottky barrier high work function metal. The thin highly doped p-type region has been found to increase the open circuit voltage and current of the photovoltaic device.

  5. Millimeter-wave diode-grid phase shifters

    NASA Technical Reports Server (NTRS)

    Lam, Wayne W.; Stolt, Kjell S.; Jou, Christina F.; Luhmann, Neville C., Jr.; Chen, Howard Z.

    1988-01-01

    Monolithic diode grids have been fabricated on 2-cm square gallium-arsenide wafers with 1600 Schottky-barrier varactor diodes. Shorted diodes are detected with a liquid-crystal technique, and the bad diodes are removed with an ultrasonic probe. A small-aperture reflectometer that uses wavefront division interference was developed to measure the reflection coefficient of the grids. A phase shift of 70 deg with a 7-dB loss was obtained at 93 GHz when the bias on the diode grid was changed from -3 V to 1 V. A simple transmission-line grid model, together with the measured low-frequency parameters for the diodes, was shown to predict the measured performance over the entire capacitive bias range of the diodes, as well as over the complete reactive tuning range provided by a reflector behind the grid, and over a wide range of frequencies from 33 GHz to 141 GHz. This shows that the transmission-line model and the measured low-frequency diode parameters can be used to design an electronic beam-steering array and to predict its performance. An electronic beam-steering array made of a pair of grids using state-of-the-art diodes with 5-ohm series resistances would have a loss of 1.4 dB at 90 GHz.

  6. Monolithic millimeter-wave diode grid frequency multiplier arrays

    NASA Technical Reports Server (NTRS)

    Liu, Hong-Xia L.; Qin, X.-H.; Sjogren, L. B.; Wu, W.; Chung, E.; Domier, C. W.; Luhmann, N. C., Jr.

    1992-01-01

    Monolithic diode frequency multiplier arrays, including barrier-N-N(+) (BNN) doubler, multi-quantum-barrier-varactor (MQBV) tripler, Schottky-quantum-barrier-varactor (SQBV) tripler, and resonant-tunneling-diode (RTD) tripler arrays, have been successfully fabricated with yields between 85 and 99 percent. Frequency doubling and/or tripling have been observed for all the arrays. Output powers of 2.4-2.6 W (eta = 10-18 percent) at 66 GHz with the BNN doubler and 3.8-10 W (eta = 1.7-4 percent) at 99 GHz with the SQBV tripler have been achieved.

  7. From synchrotron radiation to I-V measurements of GaAs schottky barrier formation

    NASA Astrophysics Data System (ADS)

    Spicer, W. E.; Cao, R.; Miyano, K.; Kendelewicz, T.; Lindau, I.; Weber, E.; Liliental-Weber, Z.; Newman, N.

    1990-01-01

    Through the use of synchrotron radiation photoemission spectroscopy (PES) and related techniques, we have gained detailed knowledge of Fermi level pinning, interfacial chemistry and disruption of GaAs for coverages up to several monolayers (ML). A link has been made between these data and that in the thick layer regime (hundreds of ML), which characterizes practical Schottky diodes. PES results for thin layers deposited at room temperature (RT) and low temperatures of about 80 K (LT) as well as thick films deposited at RT and annealed to higher temperatures are considered. At LT where GaAs disruption is minimized for thin films, metal-induced gap states seem to dominate the Fermi level pinning process except where GaAs metal reactions are strong. For RT thin and thick films, the effects of defects must be considered, and the advanced unified defect model (AUDM) is applied. In the AUDM the key defects are identified as the AsGa (double donor with levels at 0.75 and 0.5 eV above the valence band maximum) and the GaAs antisite (double acceptor) with the AsGa normally dominating due to the excess As which characterizes LEC GaAs crystals. The literature is reviewed and a number of phenomena are explained in terms of this model including the Fermi level position on MBE grown GaAs observed by Svensson et al. and the anomolously high Schottky barrier height (SBH) of thick Ga on n-GaAs observed by several groups. By performing electrical, TEM, and chemical studies of thick diodes and by evaluating the changes upon thermal annealing of diodes it is found that the AUDM successfully predicts the increase or decrease of barrier height on annealing.

  8. From synchrotron radiation to I-V measurements of GaAs schottky barrier formation

    NASA Astrophysics Data System (ADS)

    Spicer, W. E.; Cao, R.; Miyano, K.; Kendelewicz, T.; Lindau, I.; Weber, E.; Liliental-Weber, Z.; Newman, N.

    1989-11-01

    Through the use of synchrotron radiation photoemission spectroscopy (PES) and related techniques, we have gained detailed knowledge of Fermi level pinning, interfacial chemistry and disruption of GaAs for coverages up to several monolayers (ML). A link has been made between these data and that in the thick layer regime (hundreds of ML), which characterizes practical Schottky diodes. PES results for thin layers deposited at room temperature (RT) and low temperatures of about 80 K (LT) as well as thick films deposited at RT and annealed to higher temperatures are considered. At LT where GaAs disruption is minimized for thin films, metal-induced gap states seem to dominate the Fermi level pinning process except where GaAs metal reactions are strong. For RT thin and thick films, the effects of defects must be considered, and the advanced unified defect model (AUDM) is applied. In the AUDM the key defects are identified as the As Ga (double donor with levels at 0.75 and 0.5 eV above the valence band maximum) and the Ga As antisite (double acceptor) with the As Ga normally dominating due to the excess As which characterizes LEC GaAs crystals. The literature is reviewed and a number of phenomena are explained in terms of this model including the Fermi level position on MBE grown GaAs observed by Svensson et al. and the anomolously high Schottky barrier height (SBH) of thick Ga on n-GaAs observed by several groups. By performing electrical, TEM, and chemical studies of thick diodes and by evaluating the changes upon thermal annealing of diodes it is found that the AUDM successfully predicts the increase or decrease of barrier height on annealing.

  9. Phase interaction in GaAs contacts with group I metals and its relationship to the degradation of structures with a schottky barrier

    SciTech Connect

    Bozhkov, V.G.; Ivonin, I.V.; Soldatenko, K.V.; Yakbenya, M.P.

    1986-03-01

    This paper uses the methods of Rutherford back scattering of helium ions and x-ray diffraction and electron microscope analysis to study phase interaction in GaAs contacts with layers of group I metals (Cu, Ag, Au) with annealings in a hydrogen atmosphere. The nature of the interactions and the mechanisms of degradation of the volt-ampere characteristics of Schottky barrier diodes are discussed.

  10. Electrical characteristics of p-Si/TiO2/Al and p-Si/TiO2-Zr/Al Schottky devices

    NASA Astrophysics Data System (ADS)

    Hüdai Taşdemir, İbrahim; Vural, Özkan; Dökme, İlbilge

    2016-06-01

    Electrical devices involve different types of diode in prospective electronics is of great importance. In this study, p-type Si surface was covered with thin film of TiO2 dispersion in H2O to construct p-Si/TiO2/Al Schottky barrier diode (D1) and the other one with TiO2 dispersion doped with zirconium to construct p-Si/TiO2-Zr/Al diode (D2) by drop-casting method in the same conditions. Electrical properties of as-prepared diodes and effect of zirconium as a dopant were investigated. Current-voltage (I-V) characteristics of these devices were measured at ambient conditions. Some parameters including ideality factor (n), barrier height (ΦB0), series resistance (Rs) and interface state density (Nss) were calculated from I-V behaviours of diodes. Structural comparisons were based on SEM and EDX measurements. Experimental results indicated that electrical parameters of p-Si/TiO2/Al Schottky device were influenced by the zirconium dopant in TiO2.

  11. Si/IrSi3 Schottky-Barrier Infrared Detectors

    NASA Technical Reports Server (NTRS)

    Lin, True-Lon

    1991-01-01

    Si/IrSi or Si/IrSi3 Schottky-barrier detector fabricated by stoichiometric codeposition of Ir and Si on p Si substrate. Includes p+ substrate contact, silicide electrode, and n Si guard ring, which suppresses leakage around periphery of silicide electrode. Part of continuing effort to develop imaging arrays of Schottky-barrier detectors operating at far-infrared wavelengths.

  12. Data Diode

    SciTech Connect

    2014-11-07

    The Data Diode is a data security technology that can be deployed within an organization's defense-in-depth computer network strategy for information assurance. For internal security, the software creates an environment within the network where an organization's approved users can work freely inside an enclave of protected data, but file transfers out of the enclave is restricted. For external security, once a network intruder has penetrated the network, the intruder is able to "see" the protected data, but is unable to download the actual data. During the time it takes for the intruder to search for a way around the obstacle created by the Data Diode, the network's intrusion detection technologies can locate and thwart the malicious intent of the intruder. Development of the Data Diode technology was made possible by funding from the Intelligence Advanced Research Projects Activity (IARPA).

  13. Data Diode

    2014-11-07

    The Data Diode is a data security technology that can be deployed within an organization's defense-in-depth computer network strategy for information assurance. For internal security, the software creates an environment within the network where an organization's approved users can work freely inside an enclave of protected data, but file transfers out of the enclave is restricted. For external security, once a network intruder has penetrated the network, the intruder is able to "see" the protectedmore » data, but is unable to download the actual data. During the time it takes for the intruder to search for a way around the obstacle created by the Data Diode, the network's intrusion detection technologies can locate and thwart the malicious intent of the intruder. Development of the Data Diode technology was made possible by funding from the Intelligence Advanced Research Projects Activity (IARPA).« less

  14. Hot carrier multiplication on graphene/TiO2 Schottky nanodiodes

    PubMed Central

    Lee, Young Keun; Choi, Hongkyw; Lee, Hyunsoo; Lee, Changhwan; Choi, Jin Sik; Choi, Choon-Gi; Hwang, Euyheon; Park, Jeong Young

    2016-01-01

    Carrier multiplication (i.e. generation of multiple electron–hole pairs from a single high-energy electron, CM) in graphene has been extensively studied both theoretically and experimentally, but direct application of hot carrier multiplication in graphene has not been reported. Here, taking advantage of efficient CM in graphene, we fabricated graphene/TiO2 Schottky nanodiodes and found CM-driven enhancement of quantum efficiency. The unusual photocurrent behavior was observed and directly compared with Fowler’s law for photoemission on metals. The Fowler’s law exponent for the graphene-based nanodiode is almost twice that of a thin gold film based diode; the graphene-based nanodiode also has a weak dependence on light intensity—both are significant evidence for CM in graphene. Furthermore, doping in graphene significantly modifies the quantum efficiency by changing the Schottky barrier. The CM phenomenon observed on the graphene/TiO2 nanodiodes can lead to intriguing applications of viable graphene-based light harvesting. PMID:27271245

  15. Polycrystalline silicon carbide dopant profiles obtained through a scanning nano-Schottky contact

    NASA Astrophysics Data System (ADS)

    Golt, M. C.; Strawhecker, K. E.; Bratcher, M. S.; Shanholtz, E. R.

    2016-07-01

    The unique thermo-electro-mechanical properties of polycrystalline silicon carbide (poly-SiC) make it a desirable candidate for structural and electronic materials for operation in extreme environments. Necessitated by the need to understand how processing additives influence poly-SiC structure and electrical properties, the distribution of lattice defects and impurities across a specimen of hot-pressed 6H poly-SiC processed with p-type additives was visualized with high spatial resolution using a conductive atomic force microscopy approach in which a contact forming a nano-Schottky interface is scanned across the sample. The results reveal very intricate structures within poly-SiC, with each grain having a complex core-rim structure. This complexity results from the influence the additives have on the evolution of the microstructure during processing. It was found that the highest conductivities localized at rims as well as at the interface between the rim and the core. The conductivity of the cores is less than the conductivity of the rims due to a lower concentration of dopant. Analysis of the observed conductivities and current-voltage curves is presented in the context of nano-Schottky contact regimes where the conventional understanding of charge transport to diode operation is no longer valid.

  16. Hot carrier multiplication on graphene/TiO2 Schottky nanodiodes

    NASA Astrophysics Data System (ADS)

    Lee, Young Keun; Choi, Hongkyw; Lee, Hyunsoo; Lee, Changhwan; Choi, Jin Sik; Choi, Choon-Gi; Hwang, Euyheon; Park, Jeong Young

    2016-06-01

    Carrier multiplication (i.e. generation of multiple electron–hole pairs from a single high-energy electron, CM) in graphene has been extensively studied both theoretically and experimentally, but direct application of hot carrier multiplication in graphene has not been reported. Here, taking advantage of efficient CM in graphene, we fabricated graphene/TiO2 Schottky nanodiodes and found CM-driven enhancement of quantum efficiency. The unusual photocurrent behavior was observed and directly compared with Fowler’s law for photoemission on metals. The Fowler’s law exponent for the graphene-based nanodiode is almost twice that of a thin gold film based diode; the graphene-based nanodiode also has a weak dependence on light intensity—both are significant evidence for CM in graphene. Furthermore, doping in graphene significantly modifies the quantum efficiency by changing the Schottky barrier. The CM phenomenon observed on the graphene/TiO2 nanodiodes can lead to intriguing applications of viable graphene-based light harvesting.

  17. Correlation of microstructure with electrical behavior of Ti/GaN Schottky contacts

    SciTech Connect

    Hirsch, M.T.; Duxstad, K.J.; Haller, E.E.; Ruvimov, S.; Liliental-Weber, Z.

    1998-11-01

    The authors correlate structural and electrical characteristics of as-deposited and low-temperature annealed Ti contacts on GaN. Temperature dependent current-voltage measurements are used to determine the effective barrier heights of the respective contacts, while high-resolution transmission electron microscopy is utilized for structural characterization. As-deposited Ti contacts are slightly rectifying with an effective barrier height of {approximately}200 meV. After annealing at 230 C, the barrier height increases to values of {approximately}450 meV. A similar behavior of Schottky contacts with more strongly rectifying diodes upon low-temperature annealing is observed for Zr metal contacts on GaN. As-deposited Ti already forms a thin TiN layer at the GaN interface. After annealing at 230 C, the average thickness and the distribution of TiN grains remain practically unchanged, but the interface with GaN roughens. The authors correlate the observed barrier height changes with interface roughness and phase formation and they discuss the results in terms of interface damage and the Schottky-Mott theory.

  18. Active charge state control of single NV centres in diamond by in-plane Al-Schottky junctions

    PubMed Central

    Schreyvogel, C.; Polyakov, V.; Wunderlich, R.; Meijer, J.; Nebel, C. E.

    2015-01-01

    In this paper, we demonstrate an active control of the charge state of a single nitrogen-vacancy (NV) centre by using in-plane Schottky-diode geometries with aluminium on hydrogen-terminated diamond surface. A switching between NV+, NV0 and NV− can be performed with the Al-gates which apply electric fields in the hole depletion region of the Schottky junction that induces a band bending modulation, thereby shifting the Fermi-level over NV charge transition levels. We simulated the in-plane band structure of the Schottky junction with the Software ATLAS by solving the drift-diffusion model and the Poisson-equation self-consistently. We simulated the IV-characteristics, calculated the width of the hole depletion region, the position of the Fermi-level intersection with the NV charge transition levels for different reverse bias voltages applied on the Al-gate. We can show that the field-induced band bending modulation in the depletion region causes a shifting of the Fermi-level over NV charge transition levels in such a way that the charge state of a single NV centre and thus its electrical and optical properties is tuned. In addition, the NV centre should be approx. 1–2 μm away from the Al-edge in order to be switched with moderate bias voltages. PMID:26177799

  19. Enhanced barrier height GaInAs MSM Schottky barrier photodiodes

    NASA Astrophysics Data System (ADS)

    Averin, S. V.; Kohl, A.; Mesquida Kusters, A.; Heime, Klaus

    1994-01-01

    The p+-cap layer of InP together with 80 nm of undoped (Nb equals 5 1014 cm-3) assist layer of InP for the first time were used to increase the Schottky barrier height (up to 0.73 e.V.) on GaInAs and to create high speed MSM photodetectors on it. The average dark current density is 1.6 10-4 A/cm2 -- the lowest known value on the GaInAs semiconductor material. A rise time of 37 ps for the impulse response at (lambda) equals 1.3 micrometers was measured for a MSM diode with 2 micrometers fingers and 2 micrometers gaps and an active area of 30 X 30 micrometers 2.

  20. Simulation of phosphorene Schottky-barrier transistors

    NASA Astrophysics Data System (ADS)

    Wan, Runlai; Cao, Xi; Guo, Jing

    2014-10-01

    Schottky barrier field-effect transistors (SBFETs) based on few and mono layer phosphorene are simulated by the non-equilibrium Green's function formalism. It is shown that scaling down the gate oxide thickness results in pronounced ambipolar I-V characteristics and significant increase of the minimal leakage current. The problem of leakage is especially severe when the gate insulator is thin and the number of layer is large, but can be effectively suppressed by reducing phosphorene to mono or bilayer. Different from two-dimensional graphene and layered dichalcogenide materials, both the ON-current of the phosphorene SBFETs and the metal-semiconductor contact resistance between metal and phosphorene strongly depend on the transport crystalline direction.

  1. Photonic crystal cavities with metallic Schottky contacts

    SciTech Connect

    Quiring, W.; Al-Hmoud, M.; Reuter, D.; Zrenner, A.; Rai, A.; Wieck, A. D.

    2015-07-27

    We report about the fabrication and analysis of high Q photonic crystal cavities with metallic Schottky-contacts. The structures are based on GaAs n-i membranes with an InGaAs quantum well in the i-region and nanostructured low ohmic metal top-gates. They are designed for photocurrent readout within the cavity and fast electric manipulations. The cavity structures are characterized by photoluminescence and photocurrent spectroscopy under resonant excitation. We find strong cavity resonances in the photocurrent spectra and surprisingly high Q-factors up to 6500. Temperature dependent photocurrent measurements in the region between 4.5 K and 310 K show an exponential enhancement of the photocurrent signal and an external quantum efficiency up to 0.26.

  2. Proposal of a broadband, polarization-insensitive and high-efficiency hot-carrier schottky photodetector integrated with a plasmonic silicon ridge waveguide

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Kou, Pengfei; Shen, Jianqi; Lee, El Hang; He, Sailing

    2015-12-01

    We propose a broadband, polarization-insensitive and high-efficiency plasmonic Schottky diode for detection of sub-bandgap photons in the optical communication wavelength range through internal photoemission (IPE). The distinctive features of this design are that it has a gold film covering both the top and the sidewalls of a dielectric silicon ridge waveguide with the Schottky contact formed at the gold-silicon interface and the sidewall coverage of gold can be easily tuned by an insulating layer. An extensive physical model on IPE of hot carriers is presented in detail and is applied to calculate and examine the performance of this detector. In comparison with a diode having only the top gold contact, the polarization sensitivity of the responsivity is greatly minimized in our photodetector with gold film covering both the top and the sidewall. Much higher responsivities for both polarizations are also achieved over a broad wavelength range of 1.2-1.6 μm. Moreover, the Schottky contact is only 4 μm long, leading to a very small dark current. Our design is very promising for practical applications in high-density silicon photonic integration.

  3. Modeling of Carbon Nanotube Schottky Barrier Modulation Due to Oxidation

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryan (Technical Monitor)

    2002-01-01

    A model is proposed for the experimentally observed lower Schottky barrier for holes in air than in vacuum at a metallic electrode - semiconducting carbon nanotube (CNT) junction. In oxidation occurring in air, the negatively charged oxygen molecules on a material usually enhance the surface dipole and provide stronger electron confinement within the bulk. Thus the CNT electron affinity will increase in air. Then the Schottky barrier for holes will have to increase according to the standard band-alignment theory, but this is against the experiment. In order to overcome this difficulty, we propose a new Schottky barrier model, assuming there is a transition region between the electrode and the CNT and an appreciable potential can drop there. The role of the oxidation is to increase this potential drop with negatively charged oxygen molecules, leading to a lower Schottky barrier for holes. This mechanism prevails for both p- and n-CNTs. The model consistently explains all the reported CNT device experiments.

  4. Electrical properties of Ge crystals and effective Schottky barrier height of NiGe/Ge junctions modified by P and chalcogen (S, Se, or Te) co-doping

    NASA Astrophysics Data System (ADS)

    Koike, Masahiro; Kamimuta, Yuuichi; Tezuka, Tsutomu; Yamabe, Kikuo

    2016-09-01

    The electrical properties of Ge crystals and the effective Schottky barrier height (SBH) of NiGe/Ge diodes fabricated by P and/or chalcogen (S, Se, or Te) doping were investigated for Ge n-channel metal-oxide-semiconductor field-effect transistors with a NiGe/n+Ge junction. The electron concentration in Ge was increased more by co-doping with chalcogen and P than by doping with P alone. Moreover, SBH values were decreased in NiGe/nGe diodes and increased in NiGe/pGe diodes compared with undoped NiGe/Ge by both P doping and P and chalcogen co-doping. Co-doping with Te and P was most effective in modifying the SBH.

  5. Analysis of Carbon Nanotube Metal-Semiconductor Diode Device

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Biegel, Bryan (Technical Monitor)

    2001-01-01

    We study recently reported drain current I(sub d)-drain voltage V(sub d) characteristics of a carbon nanotube metal-semiconductor diode device with the gate voltage V(sub g) applied to modulate the carrier density in the nanotube. The diode was kink-shaped at the metal-semiconductor interface. It was shown that (1) larger negative V(sub g) blocked I(sub d) more effectively in the negative V(sub d) region, resulting in the rectifying I(sub d)-V(sub d) characteristics, and that (2) positive V(sub g) allowed I(sub d) in the both V(sub d) polarities, resulting in the non-rectifying characteristics. The negative V(sub d) was the Schottky reverse direction, judging from the negligible I(sub d) behavior for a wide region of -4 V (is less than) V(sub d) (is less than) 0 V, with V(sub g) = -4 V. Such negative V(sub g) would attract positive charges from the metallic electrodes (charge reservoir) to the nanotube and lower the nanotube Fermi energy (E(sub F)). With larger negative V(sub g), the experiment showed that the Schottky forward direction (V(sub d) (is greater than) 0) had a smaller turn-on voltage and the Schottky reverse direction (V(sub d) (is less than) 0) was more resistant to the tunneling breakdown. Therefore, the majority carriers in the transport would be electrons since they can see a lower tunneling barrier (shallower built-in potential) in the forward direction when E(sub F) is lowered, and a thicker tunneling barrier (Schottky barrier) in the reverse direction due to the reduction in the electron density when E(sub F) is lowered.

  6. Probing the nanoscale Schottky barrier of metal/semiconductor interfaces of Pt/CdSe/Pt nanodumbbells by conductive-probe atomic force microscopy.

    PubMed

    Kwon, Sangku; Lee, Seon Joo; Kim, Sun Mi; Lee, Youngkeun; Song, Hyunjoon; Park, Jeong Young

    2015-08-01

    The electrical nature of the nanoscale contact between metal nanodots and semiconductor rods has drawn significant interest because of potential applications for metal-semiconductor hybrid nanostructures in energy conversion or heterogeneous catalysis. Here, we studied the nanoscale electrical character of the Pt/CdSe junction in Pt/CdSe/Pt nanodumbbells on connected Au islands by conductive-probe atomic force microscopy under ultra-high vacuum. Current-voltage plots measured in contact mode revealed Schottky barrier heights of individual nanojunctions of 0.41 ± 0.02 eV. The measured value of the Schottky barrier is significantly lower than that of planar thin-film diodes because of a reduction in the barrier width and enhanced tunneling probability at the interface.

  7. Gold nanoparticles deposited on linker-free silicon substrate and embedded in aluminum Schottky contact.

    PubMed

    Gorji, Mohammad Saleh; Razak, Khairunisak Abdul; Cheong, Kuan Yew

    2013-10-15

    Given the enormous importance of Au nanoparticles (NPs) deposition on Si substrates as the precursor for various applications, we present an alternative approach to deposit Au NPs on linker-free n- and p-type Si substrates. It is demonstrated that, all conditions being similar, there is a significant difference between densities of the deposited NPs on both substrates. The Zeta-potential and polarity of charges surrounding the hydroxylamine reduced seeded growth Au NPs, are determined by a Zetasizer. To investigate the surface properties of Si substrates, contact angle measurement is performed. Field-emission scanning electron microscope is then utilized to distinguish the NPs density on the substrates. Finally, Al/Si Schottky barrier diodes with embedded Au NPs are fabricated, and their structural and electrical characteristics are further evaluated using an energy-filtered transmission electron microscope and current-voltage measurements, respectively. The results reveal that the density of NPs is significantly higher on n-type Si substrate and consequently has more pronounced effects on the electrical characteristics of the diode. It is concluded that protonation of Si-OH group on Si surface in low pH is responsible for the immobilization of Au NPs, which eventually contributes to the lowering of barrier height and enhances the electrical characteristics.

  8. Probing the nanoscale Schottky barrier of metal/semiconductor interfaces of Pt/CdSe/Pt nanodumbbells by conductive-probe atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Kwon, Sangku; Lee, Seon Joo; Kim, Sun Mi; Lee, Youngkeun; Song, Hyunjoon; Park, Jeong Young

    2015-07-01

    The electrical nature of the nanoscale contact between metal nanodots and semiconductor rods has drawn significant interest because of potential applications for metal-semiconductor hybrid nanostructures in energy conversion or heterogeneous catalysis. Here, we studied the nanoscale electrical character of the Pt/CdSe junction in Pt/CdSe/Pt nanodumbbells on connected Au islands by conductive-probe atomic force microscopy under ultra-high vacuum. Current-voltage plots measured in contact mode revealed Schottky barrier heights of individual nanojunctions of 0.41 +/- 0.02 eV. The measured value of the Schottky barrier is significantly lower than that of planar thin-film diodes because of a reduction in the barrier width and enhanced tunneling probability at the interface.The electrical nature of the nanoscale contact between metal nanodots and semiconductor rods has drawn significant interest because of potential applications for metal-semiconductor hybrid nanostructures in energy conversion or heterogeneous catalysis. Here, we studied the nanoscale electrical character of the Pt/CdSe junction in Pt/CdSe/Pt nanodumbbells on connected Au islands by conductive-probe atomic force microscopy under ultra-high vacuum. Current-voltage plots measured in contact mode revealed Schottky barrier heights of individual nanojunctions of 0.41 +/- 0.02 eV. The measured value of the Schottky barrier is significantly lower than that of planar thin-film diodes because of a reduction in the barrier width and enhanced tunneling probability at the interface. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02285a

  9. Silicon Carbide Diodes Performance Characterization at High Temperatures

    NASA Technical Reports Server (NTRS)

    Lebron-Velilla, Ramon C.; Schwarze, Gene E.; Gardner, Brent G.; Adams, Jerry

    2004-01-01

    NASA Glenn Research center's Electrical Systems Development branch is working to demonstrate and test the advantages of Silicon Carbide (SiC) devices in actual power electronics applications. The first step in this pursuit is to obtain commercially available SiC Schottky diodes and to individually test them under both static and dynamic conditions, and then compare them with current state of the art silicon Schottky and ultra fast p-n diodes of similar voltage and current ratings. This presentation covers the results of electrical tests performed at NASA Glenn. Steady state forward and reverse current-volt (I-V) curves were generated for each device to compare performance and to measure their forward voltage drop at rated current, as well as the reverse leakage current at rated voltage. In addition, the devices were individually connected as freewheeling diodes in a Buck (step down) DC to DC converter to test their reverse recovery characteristics and compare their transient performance in a typical converter application. Both static and transient characterization tests were performed at temperatures ranging from 25 C to 300 C, in order to test and demonstrate the advantages of SiC over Silicon at high temperatures.

  10. Schottky Heterodyne Receivers With Full Waveguide Bandwidth

    NASA Technical Reports Server (NTRS)

    Hesler, Jeffrey; Crowe, Thomas

    2011-01-01

    Compact THz receivers with broad bandwidth and low noise have been developed for the frequency range from 100 GHz to 1 THz. These receivers meet the requirements for high-resolution spectroscopic studies of planetary atmospheres (including the Earth s) from spacecraft, as well as airborne and balloon platforms. The ongoing research is significant not only for the development of Schottky mixers, but also for the creation of a receiver system, including the LO chain. The new receivers meet the goals of high sensitivity, compact size, low total power requirement, and operation across complete waveguide bands. The exceptional performance makes these receivers ideal for the broader range of scientific and commercial applications. These include the extension of sophisticated test and measurement equipment to 1 THz and the development of low-cost imaging systems for security applications and industrial process monitoring. As a particular example, a WR-1.9SHM (400-600 GHz) has been developed (see Figure 1), with state-of-the-art noise temperature ranging from 1,000-1,800 K (DSB) over the full waveguide band. Also, a Vector Network Analyzer extender has been developed (see Figure 2) for the WR1.5 waveguide band (500 750 GHz) with 100-dB dynamic range.

  11. Dye-sensitized Schottky barrier solar cells

    DOEpatents

    Skotheim, Terje A.

    1978-01-01

    A low-cost dye-sensitized Schottky barrier solar cell comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent.

  12. Contact Whiskers for Millimeter Wave Diodes

    NASA Technical Reports Server (NTRS)

    Kerr, A. R.; Grange, J. A.; Lichtenberger, J. A.

    1978-01-01

    Several techniques are investigated for making short conical tips on wires (whiskers) used for contacting millimeter-wave Schottky diodes. One procedure, using a phosphoric and chromic acid etching solution (PCE), is found to give good results on 12 microns phosphor-bronze wires. Full cone angles of 60 degrees-80 degrees are consistently obtained, compared with the 15 degrees-20 degrees angles obtained with the widely used sodium hydroxide etch. Methods are also described for cleaning, increasing the tip diameter (i.e. blunting), gold plating, and testing the contact resistance of the whiskers. The effects of the whisker tip shape on the electrical resistance, inductance, and capacitance of the whiskers are studied, and examples given for typical sets of parameters.

  13. Characteristics of metal/sputtered CdTe/ n-GaAs diode structures

    NASA Astrophysics Data System (ADS)

    Das, M. B.; Krishnaswamy, S. V.; Petkie, R.; Elmuradi, M.

    1983-02-01

    Incorporation of a thin layer of r.f. sputtered CdTe between the metal and n-GaAs, has resulted in diode structures with MIS and Schottky barrier types C/V characteristics and low-current forward and reverse I/V characteristics. These structures have the potential to be useful in improving the performance of GaAs FET's for microwave and high speed applications.

  14. Back contact and reach-through diode effects in thin-film photovoltaics

    NASA Astrophysics Data System (ADS)

    Roussillon, Y.; Karpov, V. G.; Shvydka, Diana; Drayton, J.; Compaan, A. D.

    2004-12-01

    The physics of back contact effects in photovoltaic devices is revisited. We show that the back contact Schottky barrier can act in either back-diode or reach-through diode regimes. This understanding predicts that rare local spots with low back barrier hole transparency and/or weak main junctions can shunt the photocurrent thus decreasing the measured open-circuit voltage and device efficiency. We derive several more specific predictions of our model and verify them experimentally for the case of thin-film CdTe photovoltaics. Our concept has practical implications: a simple recipe leading to an efficient (13%) copper-free CdTe solar cell.

  15. Richardson-Schottky transport mechanism in ZnS nanoparticles

    NASA Astrophysics Data System (ADS)

    Ali, Hassan; Khan, Usman; Rafiq, M. A.; Falak, Attia; Narain, Adeela; Jing, Tang; Xu, Xiulai

    2016-05-01

    We report the synthesis and electrical transport mechanism in ZnS semiconductor nanoparticles. Temperature dependent direct current transport measurements on the compacts of ZnS have been performed to investigate the transport mechanism for temperature ranging from 300 K to 400 K. High frequency dielectric constant has been used to obtain the theoretical values of Richardson-Schottky and Poole-Frenkel barrier lowering coefficients. Experimental value of the barrier lowering coefficient has been calculated from conductance-voltage characteristics. The experimental value of barrier lowering coefficient βexp lies close to the theoretical value of Richardson-Schottky barrier lowering coefficient βth,RS showing Richardson-Schottky emission has been responsible for conduction in ZnS nanoparticles for the temperature range studied.

  16. Fabrication of Au/p-Si Schottky barrier for EBIC study.

    PubMed

    Zhang, X; Joy, D

    1994-09-01

    A simple method for the fabrication of a Au/p-Si Schottky barrier suitable for electron beam induced current (EBIC) study has been developed. The mechanical and electrical properties of the fabricated Au/p-Si Schottky barriers have been tested, and EBIC measurements of the dislocation contrast have been conducted using the fabricated Schottky barriers.

  17. Analysis of Hyperabrupt and Uniform Junctions in GaAs for the Application of Varactor Diode.

    PubMed

    Heo, Jun-Woo; Hong, Sejun; Choi, Seok-Gyu; Kim, Hyun-Seok

    2015-10-01

    In this study, we present a GaAs varactor diode with a hyperabrupt junction for the enhancement of breakdown voltage and capacitance variation in a reverse bias state. The hyperabrupt doping profile in the n-type active layer is prepared in a controlled nonlinear manner, with the density of the dopants increasing towards the Schottky junction. The hyperabrupt GaAs varactor diode is fabricated and characterized for breakdown voltage and capacitance over the electric field, induced by an applied reverse bias voltage. A reduced value of the electric field is observed owing to the nonlinear behavior of the electric field at the hyperabrupt junction, although the device has a larger doping density at the Schottky junction. Furthermore, the capacitance ratio of the hyperabrupt junction diode is also improved. Variation in the device capacitance is affected by variation in the depletion region across the junction. Technology CAD is used to understand the experimental phenomena by considering the magnitude of charge density as a function of the doping profile. A higher breakdown voltage and greater capacitance modulation are shown in the hyperabrupt junction diode compared to the uniform junction diode.

  18. High-voltage (3.3 kV) 4H-SiC JBS diodes

    SciTech Connect

    Ivanov, P. A. Grekhov, I. V.; Il'inskaya, N. D.; Kon'kov, O. I.; Potapov, A. S.; Samsonova, T. P.; Serebrennikova, O. U.

    2011-05-15

    High-voltage 4H-SiC junction-barrier Schottky (JBS) diodes have been fabricated and studied. The working area of the diodes (anode contact area) is 1.44 mm{sup 2}. At currents in the range from 10{sup -11} to 1.5 A, the forward current-voltage characteristic of the diodes is described in terms of the thermionic emission model, with the series resistance taken into account: Schottky barrier height {Phi}{sub B} = 1.16 eV, ideality factor n = 1.01, and series resistance R{sub s} = 2.2 {Omega} (32 m{Omega} cm{sup 2}). The value of R{sub s} is governed by the resistance of the blocking epitaxial n-base (impurity concentration N = 9 Multiplication-Sign 10{sup 14} cm{sup -3}, n-layer thickness d = 34 {mu}m). The diodes can block a reverse voltage of at least 3.3 kV (with a leakage current at room temperature on the order of 1 {mu}A). It is suggested that the leakage mechanism is associated with crystal lattice defects (dislocations) in SiC. It is shown that the reverse-recovery characteristics of the diodes are determined by the flow of a purely capacitive reverse current.

  19. Electronic properties of Al/p-Si/C70/Au MIS-type diode

    NASA Astrophysics Data System (ADS)

    Gedikpınar, M.; Çavaş, M.; Alahmed, Zayed A.; Yakuphanoglu, F.

    2013-07-01

    The electrical characteristics of the Al/p-Si/C70/Au diode were investigated by current-voltage and capacitance-voltage measurements. The current-voltage characteristics confirm that the diode is a metal-insulator-semiconductor type device. The decrease in ideality factor and increase in barrier height values of the diode were observed with temperature. This behavior was explained on the basis of Schottky barrier height inhomogeneities. The zero-bias mean barrier height ϕ and Richardson values for the diode were found to be 1.06 eV and 33.12 A/cm2 K2, respectively. The obtained Richardson constant (A* = 33.12 A/cm2 K2) is in agreement with the theoretical value of A* = 32 A/cm2 K2. The interface state density properties of the diode were analyzed and the shape of the interface state density is changed with temperature. The ϕB value obtained from C-V measurement is higher than that of ϕB value obtained from I-V measurements. The discrepancy between ϕB(C-V) and ϕB(I-V) values was explained by distribution of Schottky barrier height due the inhomogeneities.

  20. The polarization mechanism in CdTe Schottky detectors

    SciTech Connect

    Cola, Adriano; Farella, Isabella

    2009-03-09

    Schottky CdTe nuclear detectors are affected by bias-induced polarization phenomena when operating at room temperature. A space charge buildup occurs at the blocking contact causing the degradation in detection performance. By means of Pockels effect, we study the electric field distribution inside the detector and its variation with time and temperature. The analysis of the space charge has allowed us to point out the role of the Schottky contact and of carrier detrapping from deep levels in the polarization mechanism. Moreover, measured current transients have been quantitatively accounted for by the increase in the electric field at the blocking junction.

  1. Electromechanical resistive switching via back-to-back Schottky junctions

    SciTech Connect

    Li, Lijie

    2015-09-15

    The physics of the electromechanical resistive switching is uncovered using the theory of back-to-back Schottky junctions combined with the quantum domain space charge transport. A theoretical model of the basic element of resistive switching devices realized by the metal-ZnO nanowires-metal structure has been created and analyzed. Simulation results show that the reverse biased Schottky junction and the air gap impedance dominate the current-voltage relation at higher external voltages; thereby electromechanically varying the air gap thickness causes the device exhibit resistive tuning characteristics. As the device dimension is in nanometre scale, investigation of the model based on quantum mechanics has also been conducted.

  2. High voltage, high current Schottky barrier solar cell

    NASA Technical Reports Server (NTRS)

    Stirn, R. J. (Inventor)

    1977-01-01

    A Schottky barrier solar cell was described, which consists of a layer of wide band gap semiconductor material on which a very thin film of semitransparent metal was deposited to form a Schottky barrier. The layer of the wide band gap semiconductor material is on top of a layer of narrower band gap semiconductor material, to which one of the cell's contacts may be attached directly or through a substrate. The cell's other contact is a grid structure which is deposited on the thin metal film.

  3. Effect of temperature on series resistance of organic/inorganic semiconductor junction diode

    NASA Astrophysics Data System (ADS)

    Tripathi, Udbhav; Kaur, Ramneek; Bharti, Shivani

    2016-05-01

    The paper reports the fabrication and characterization of CuPc/n-Si organic/inorganic semiconductor diode. Copper phthalocyanine, a p-type organic semiconductor layer has been deposited on Si substrate by thermal evaporation technique. The detailed analysis of the forward and reverse bias current-voltage characteristics has been provided. Temperature dependence of the schottky diode parameters has been studied and discussed in the temperature range, 303 K to 353 K. Series resistance of the diode has been determined using Cheung's function method. Series resistance decreases with increase in temperature. The large value of series resistance at low temperature has been explained on the basis of barrier inhomogeneities in the diode.

  4. A new fabrication technique for back-to-back varactor diodes

    NASA Technical Reports Server (NTRS)

    Smith, R. Peter; Choudhury, Debabani; Martin, Suzanne; Frerking, Margaret A.; Liu, John K.; Grunthaner, Frank A.

    1992-01-01

    A new varactor diode process has been developed in which much of the processing is done from the back of an extremely thin semiconductor wafer laminated to a low-dielectric substrate. Back-to-back BNN diodes were fabricated with this technique; excellent DC and low-frequency capacitance measurements were obtained. Advantages of the new technique relative to other techniques include greatly reduced frontside wafer damage from exposure to process chemicals, improved capability to integrate devices (e.g. for antenna patterns, transmission lines, or wafer-scale grids), and higher line yield. BNN diodes fabricated with this technique exhibit approximately the expected capacitance-voltage characteristics while showing leakage currents under 10 mA at voltages three times that needed to deplete the varactor. This leakage is many orders of magnitude better than comparable Schottky diodes.

  5. Millimeter-wave diode-grid frequency doubler

    NASA Technical Reports Server (NTRS)

    Jou, Christina F.; Luhmann, Neville C., Jr.; Lam, Wayne W.; Stolt, Kjell S.; Chen, Howard Z.

    1988-01-01

    Monolithic diode grids were fabricated on 2-cm square gallium-arsenide wafers in a proof-of-principle test of a quasi-optical varactor millimeter-wave frequency multiplier array concept. An equivalent circuit model based on a transmission-line analysis of plane wave illumination was applied to predict the array performance. The doubler experiments were performed under far-field illumination conditions. A second-harmonic conversion efficiency of 9.5 percent and output powers of 0.5 W were achieved at 66 GHz when the diode grid was pumped with a pulsed source at 33 GHz. This grid had 760 Schottky-barrier varactor diodes. The average series resistance was 27 ohms, the minimum capacitance was 18 fF at a reverse breakdown voltage of -3 V. The measurements indicate that the diode grid is a feasible device for generating watt-level powers at millimeter frequencies and that substantial improvement is possible by improving the diode breakdown voltage.

  6. Transport of majority and minority carriers in 2-micron-diameter Pt-GaAs Schottky barriers

    NASA Technical Reports Server (NTRS)

    Chan, E. Y.; Card, H. C.; Yang, E. S.; Kerr, A. R.; Mattauch, R. J.

    1979-01-01

    An experimental study of small area (2-micron diameter) Pt-GaAs Schottky barrier diodes has been made, by using a wafer chip with a matrix of these diodes lying within approximately a minority carrier diffusion length of one another. Using one diode as collector and another as emitter, transistor measurements indicated that the dominant contribution to the current is the majority-carrier thermionic field emission current for large forward-bias voltage of the emitter junction (V-EB no less than about 0.4 V), whereas the smaller forward-bias (V-EB no greater than about 0.4 V) recombination in the space-charge region was most important. The minority carrier injection ratio is measurable only for large forward-bias voltages, decreasing from about 0.02 to 0.00001 as VEB increases from 0.5 to 1.0 V. The minority carrier diffusion length was measured to be about 1.3 microns. These results are of considerable significance for the understanding and optimization of the performance of these devices as classical detectors and mixers.

  7. Soft X-ray detection and photon counting spectroscopy with commercial 4H-SiC Schottky photodiodes

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Gohil, T.; Lioliou, G.; Barnett, A. M.

    2016-09-01

    The results of electrical characterisation and X-ray detection measurements of two different active area (0.06 mm2 and 0.5 mm2) commercial 4H-SiC Schottky photodiodes at room temperature are reported. The devices exhibited low dark currents (less than 10 pA) even at a high electric field strengths (403 kV/cm for 0.06 mm2 diodes; 227 kV/cm for 0.5 mm2 diodes). The results of the X-ray measurements indicate that the diodes can be used as photon counting spectroscopic X-ray detectors with modest energy resolutions: FWHM at 5.9 keV of 1.8 keV and 3.3 keV, for the 0.06 mm2 and 0.5 mm2 devices, respectively. Noise analysis of the photodiodes coupled to a custom low noise charge sensitive preamplifier is also presented.

  8. Infrared detection with point contact-metal semiconductor diodes

    NASA Astrophysics Data System (ADS)

    Eisenstein, G.

    1980-03-01

    Point contact Schottky barrier diodes, operating as video detectors and harmonic mixers at infrared frequencies, are studied, and theoretical models are developed and tested. A model extending the frequency response of the nonlinear barrier into the infrared is developed. Conductive and capacitive detection in highly doped semiconductors is considered. A model in which the low frequency spreading resistance is replaced by a complex spreading impedance is developed. The model predicts that optimal operation requires a semiconductor whose plasma frequency is one-third the operation frequency. Physical processes taking place simultaneously in the active region and in general thermal in nature are investigated. A thermo-electric detection model is developed and confirmed experimentally. The manufacturing of bulk point contact diodes is described in detail. Experimental results are compared with theoretical predictions. A method for producing thin crystaline semiconducting films on a metallic substrate is described.

  9. Solid State Reaction and Operational Stability of Ruthenium Schottky Contact-on-6H-SiC Under Argon Annealing

    NASA Astrophysics Data System (ADS)

    Munthali, Kinnock V.; Theron, Chris; Auret, F. Danie; Coelho, Sergio M. M.; Njoroge, Eric

    2015-10-01

    Thin films of ruthenium-on-6-hexagonal silicon carbide (6H-SiC) were analysed by Rutherford backscattering spectroscopy (RBS) at various annealing temperatures. Some thin film samples were also analysed by scanning electron microscope (SEM). RBS analysis indicated minimal element diffusion, and formation of ruthenium oxide after annealing at 500°C. Large-scale diffusion of ruthenium (Ru) was observed to commence at 700°C. The SEM images indicated that the as-deposited Ru was disorderly and amorphous. Annealing of the thin film improved the grain quality of Ru. The fabricated Ru-6H-SiC Schottky barrier diodes (SBD) with nickel ohmic contacts showed excellent rectifying behaviour and linear capacitance-voltage characteristics up to an annealing temperature of 900°C. The SBDs degraded after annealing at 1000°C. The degradation of the SBDs is attributed to the inter-diffusion of Ru and Si at the Schottky-substrate interface.

  10. Electrical Characteristics of Schottky Contacts to p-Type (001) GaP: Understanding of Carrier Transport Mechanism

    NASA Astrophysics Data System (ADS)

    Song, Sungjoo; Kim, Dae-Hyun; Kang, Daesung; Seong, Tae-Yeon

    2016-10-01

    Formation of low-resistance ohmic contacts to p-GaP is important for development of high-efficiency AlGaInP light-emitting diodes (LEDs), which emit light from red to yellow-green and have a wide variety of applications such as traffic light lamps, automobile tail lamps, and in biotherapy. The current flow behavior can be understood by investigating the effect of the Schottky barrier height (SBH; ΦB) on the work function of metals (ΦM). In this work, SBHs and their dependence on ΦM at (001) p-GaP surfaces were investigated. With increasing temperature, the SBH increased, while the ideality factor decreased. This behavior is explained by means of a thermionic field-emission (TFE) model. The SBH and ideal factor ranged from 0.805 eV to 0.852 eV and from 1.18 to 1.50, respectively, for different Schottky metals. The S-parameter (dΦB/dΦM) was estimated to be 0.025, with this approximately zero value implying that the surface Fermi level is virtually perfectly pinned at the surface states at ~0.85 eV above the valence-band edge.

  11. Electrical Characteristics of Schottky Contacts to p-Type (001) GaP: Understanding of Carrier Transport Mechanism

    NASA Astrophysics Data System (ADS)

    Song, Sungjoo; Kim, Dae-Hyun; Kang, Daesung; Seong, Tae-Yeon

    2016-06-01

    Formation of low-resistance ohmic contacts to p-GaP is important for development of high-efficiency AlGaInP light-emitting diodes (LEDs), which emit light from red to yellow-green and have a wide variety of applications such as traffic light lamps, automobile tail lamps, and in biotherapy. The current flow behavior can be understood by investigating the effect of the Schottky barrier height (SBH; ΦB) on the work function of metals (ΦM). In this work, SBHs and their dependence on ΦM at (001) p-GaP surfaces were investigated. With increasing temperature, the SBH increased, while the ideality factor decreased. This behavior is explained by means of a thermionic field-emission (TFE) model. The SBH and ideal factor ranged from 0.805 eV to 0.852 eV and from 1.18 to 1.50, respectively, for different Schottky metals. The S-parameter (dΦB/dΦM) was estimated to be 0.025, with this approximately zero value implying that the surface Fermi level is virtually perfectly pinned at the surface states at ~0.85 eV above the valence-band edge.

  12. Temperature dependent electrical properties of rare-earth metal Er Schottky contact on p-type InP

    NASA Astrophysics Data System (ADS)

    Rao, L. Dasaradha; Reddy, N. Ramesha; Kumar, A. Ashok; Reddy, V. Rajagopal

    2013-06-01

    The current-voltage (I-V) characteristics of the Er/p-InP Schottky barrier diodes (SBDs) have been investigated in the temperature range of 300-400K in steps of 25K. The electrical parameters such as ideality factor (n) and zero-bias barrier height (Φbo) are found to be strongly temperature dependent. It is observed that ΦI-V decreases whereas n increases with decreasing temperature. The series resistance is also calculated from the forward I-V characteristics of Er/p-InP SBD and it is found to be strongly dependent on temperature. Further, the temperature dependence of energy distribution of interface state density (NSS) profiles is determined from the forward I-V measurements by taking into account the bias dependence of the effective barrier height and ideality factor. It is observed that the NSS values increase with a decrease in temperature.

  13. Comparative Study of Interfacial Effects in Photovoltaic Diodes.

    NASA Astrophysics Data System (ADS)

    Tavakolian, Hossein

    1988-12-01

    Several different type of photodiodes (NASA standard n-p, p-on-n single crystal silicon, GaAs homojunction, ITO/p-Si, Au/n-GaAs Schottky diode and CdS/CuInSe _2) have been examined. Measurements of current vs. voltage as a function of temperature and light intensity, plus capacitance vs. voltage and frequency were an attempt to identify the causes on non-ideal behavior. An automatic, computer controlled system greatly enhanced the precision of measurements and the ability to separate non-ideal effects. No dispersion in capacitance with frequency was observed in single crystal homojunction diodes and Au/n -GaAs Schottky barrier, indicating near zero interfacial states for these devices. High efficiency (about 12%) ITO/Si showed interfacial states densities in the range of 10^9-10^{10 } cm^{-2} -eV^{-1}. This number increased to 2.5 times 10 ^{12} for cells with low efficiency (about 5%). CdS/CuInSe_2 cells from ARCO Solar, Boeing and IEC all showed interfacial states with a wide range of time constants and zero bias densities at the Fermi level in the junction of 10^ {10} to 10^{11} states/cm^2-eV. In reverse bias, however, the density of states, decreased by an order of magnitude. Under illumination, this number increased with increasing light intensity and saturated near 100 mW/cm^2. The CdS/CuInSe_2 solar cell is modeled as a heterojunction diode with charge at the junction interface. The low open-circuit voltage and the shift to lower voltage (about 125 mV) observed in some photodiodes is explained by this model. A circuit model for the photovoltaic diodes is proposed which includes the effect of traps as parallel resistance and capacitance elements.

  14. High-Efficiency Harmonically Terminated Diode and Transistor Rectifiers

    SciTech Connect

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

    2012-12-01

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

  15. Header For Laser Diode

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1990-01-01

    Header designed to contain laser diode. Output combined incoherently with outputs of other laser diodes in grating laser-beam combiner in optical communication system. Provides electrical connections to laser diode, cooling to thermally stabilize laser operation, and optomechanical adjustments that steer and focus laser beam. Range of adjustments provides for correction of worst-case decentering and defocusing of laser beam encountered with laser diodes. Mechanical configuration made simple to promote stability and keep cost low.

  16. Diode and Diode Circuits, a Programmed Text.

    ERIC Educational Resources Information Center

    Balabanian, Norman; Kirwin, Gerald J.

    This programed text on diode and diode circuits was developed under contract with the United States Office of Education as Number 4 in a series of materials for use in an electrical engineering sequence. It is intended as a supplement to a regular text and other instructional material. (DH)

  17. Giant Electroresistive Ferroelectric Diode on 2DEG.

    PubMed

    Kim, Shin-Ik; Jin Gwon, Hyo; Kim, Dai-Hong; Keun Kim, Seong; Choi, Ji-Won; Yoon, Seok-Jin; Jung Chang, Hye; Kang, Chong-Yun; Kwon, Beomjin; Bark, Chung-Wung; Hong, Seong-Hyeon; Kim, Jin-Sang; Baek, Seung-Hyub

    2015-05-27

    Manipulation of electrons in a solid through transmitting, storing, and switching is the fundamental basis for the microelectronic devices. Recently, the electroresistance effect in the ferroelectric capacitors has provided a novel way to modulate the electron transport by polarization reversal. Here, we demonstrate a giant electroresistive ferroelectric diode integrating a ferroelectric capacitor into two-dimensional electron gas (2DEG) at oxide interface. As a model system, we fabricate an epitaxial Au/Pb(Zr(0.2)Ti(0.8))O3/LaAlO3/SrTiO3 heterostructure, where 2DEG is formed at LaAlO3/SrTiO3 interface. This device functions as a two-terminal, non-volatile memory of 1 diode-1 resistor with a large I+/I- ratio (>10(8) at ± 6 V) and I(on)/I(off) ratio (>10(7)). This is attributed to not only Schottky barrier modulation at metal/ferroelectric interface by polarization reversal but also the field-effect metal-insulator transition of 2DEG. Moreover, using this heterostructure, we can demonstrate a memristive behavior for an artificial synapse memory, where the resistance can be continuously tuned by partial polarization switching, and the electrons are only unidirectionally transmitted. Beyond non-volatile memory and logic devices, our results will provide new opportunities to emerging electronic devices such as multifunctional nanoelectronics and neuromorphic electronics.

  18. Giant Electroresistive Ferroelectric Diode on 2DEG

    PubMed Central

    Kim, Shin-Ik; Jin Gwon, Hyo; Kim, Dai-Hong; Keun Kim, Seong; Choi, Ji-Won; Yoon, Seok-Jin; Jung Chang, Hye; Kang, Chong-Yun; Kwon, Beomjin; Bark, Chung-Wung; Hong, Seong-Hyeon; Kim, Jin-Sang; Baek, Seung-Hyub

    2015-01-01

    Manipulation of electrons in a solid through transmitting, storing, and switching is the fundamental basis for the microelectronic devices. Recently, the electroresistance effect in the ferroelectric capacitors has provided a novel way to modulate the electron transport by polarization reversal. Here, we demonstrate a giant electroresistive ferroelectric diode integrating a ferroelectric capacitor into two-dimensional electron gas (2DEG) at oxide interface. As a model system, we fabricate an epitaxial Au/Pb(Zr0.2Ti0.8)O3/LaAlO3/SrTiO3 heterostructure, where 2DEG is formed at LaAlO3/SrTiO3 interface. This device functions as a two-terminal, non-volatile memory of 1 diode-1 resistor with a large I+/I− ratio (>108 at ±6 V) and Ion/Ioff ratio (>107). This is attributed to not only Schottky barrier modulation at metal/ferroelectric interface by polarization reversal but also the field-effect metal-insulator transition of 2DEG. Moreover, using this heterostructure, we can demonstrate a memristive behavior for an artificial synapse memory, where the resistance can be continuously tuned by partial polarization switching, and the electrons are only unidirectionally transmitted. Beyond non-volatile memory and logic devices, our results will provide new opportunities to emerging electronic devices such as multifunctional nanoelectronics and neuromorphic electronics. PMID:26014446

  19. Gaussian distribution of inhomogeneous barrier height in Al/p-GaAs Schottky Barrier Diodes (SBDs)

    NASA Astrophysics Data System (ADS)

    Alialy, Sahar; Altindal, Semsettin

    2015-03-01

    The forward bias current-voltage (I-V) characteristics of Al/p-GaAs SBDs have been investigated in the temperature range of 240-360 K. The main electrical parameters such as zero-bias barrier height (ΦBo) , ideality factor (n) and series resistance (Rs) determined from the forward bias I-V data. These values are strong function of temperature and voltage. The analysis of I-V data based on the thermionic emission (TE) mechanism show that while the n decreases, the ΦBo and Rs increases with increasing temperature. ΦBo and n versus q/2kT plots were drown to obtain an evidence of GD of BH. The mean value of BH and standard deviation (σo) values were found from the intercept and slope of ΦBo vs q/2kT plot, respectively. Furthermore, the mean value of BH and the effective Richardson constant A* were obtained from the intercept and slope of the modified ln(Io/T2) -q2σ02 /2(kT)2 versus q/kT plot. The obtained value of A* is closed to theoretical value of p-GaAs. As a result, the I-V characteristics in Al/p-GaAs successfully have been explained based on TE theory with GD of BHs.

  20. Investigation of Light Induced Carrier Transport Phenomena Through ZnCdS Nanocomposite Based Schottky Diode

    NASA Astrophysics Data System (ADS)

    Das, Mrinmay; Middya, Somnath; Datta, Joydeep; Dey, Arka; Jana, Rajkumar; Layek, Animesh; Ray, Partha Pratim

    2016-08-01

    Here, we have discussed the electron transport phenomena through the interface formed by aluminium and hydrothermally synthesized Zinc-Cadmium-Sulphide (ZnCdS) nanocomposite. In this background, the structural, optical, and electrical characterization of the synthesized material were studied. The estimated optical band gap energy (=3.14 eV) and the room temperature conductivity (1.6 × 10-6 S cm-1) of the synthesized nanomaterial motivated us to explore the metal/inorganic-semiconductor interface. The carrier transport mechanism under dark and light-illuminated conditions was analyzed by the thermionic emission theory of the metal-semiconductor junction. Significant changes in rectification ratio, barrier potential, and the ideality factor were observed under light irradiance. The effect of incident radiation on mobility-lifetime ( μτ) product and the diffusion length ( L D) was demonstrated for the device.

  1. Graphene Based Reversible Nano-Switch/Sensor Schottky Diode (NANOSSSD) Device

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A. (Inventor); Theofylaktos, Onoufrios (Inventor); Pinto, Nicholas J. (Inventor); Mueller, Carl H. (Inventor); Santos, Javier (Inventor); Meador, Michael A. (Inventor)

    2015-01-01

    A nanostructure device is provided and performs dual functions as a nano-switching/sensing device. The nanostructure device includes a doped semiconducting substrate, an insulating layer disposed on the doped semiconducting substrate, an electrode formed on the insulating layer, and at least one layer of graphene formed on the electrode. The at least one layer of graphene provides an electrical connection between the electrode and the substrate and is the electroactive element in the device.

  2. Optical spectroscopy of site-controlled quantum dots in a Schottky diode

    NASA Astrophysics Data System (ADS)

    Yang, Lily; Carter, Samuel G.; Bracker, Allan S.; Yakes, Michael K.; Kim, Mijin; Kim, Chul Soo; Vora, Patrick M.; Gammon, Daniel

    2016-06-01

    The optical quality of site-controlled quantum dots is typically assessed by off-resonant photoluminescence spectroscopy, and emission linewidth is the most common figure of merit. Here, we combine photoluminescence and resonance fluorescence spectroscopy to obtain a more complete picture of site-controlled quantum dots embedded in a charge injection device. Although resonant and non-resonant linewidths are nearly as small as those of randomly nucleated dots, other optical properties show clear evidence of influence from defects introduced by the nanofabrication process. We demonstrate optical spin pumping and spin-flip Raman processes, which are important functions for use in quantum information applications.

  3. Effect of dielectric coating on current-voltage characteristics of Schottky barrier diodes at low temperature

    SciTech Connect

    Bozhkov, V.G.; Malakhovskii, O.Yu.

    1984-05-01

    It is shown that dielectric coatings (SiO/sub 2/, Si/sub 3/Ni/sub 4/) with rectifying Pd-GaAs contacts in ''windows'' have a significant effect on the low temperature (77/sup 0/K) current-voltage characteristic (CVC). Potential barrier height decreases and the idealness index of the CVC increases. The effect is more intense the greater the metallization thickness. For an Au-GaAs contact the effect is absent even at a metal thickness >1 um. A possible cause of this effect at low temperature is the action of mechanical stresses about the contact periphery.

  4. Mn5Ge3C0.6 /Ge(1 1 1) Schottky contacts tuned by an n-type ultra-shallow doping layer

    NASA Astrophysics Data System (ADS)

    Petit, Matthieu; Hayakawa, Ryoma; Wakayama, Yutaka; Le Thanh, Vinh; Michez, Lisa

    2016-09-01

    Mn5Ge3C x compound is of great interest for spintronics applications. The various parameters of Au/Mn5Ge3C0.6/Ge(1 1 1) and Au/Mn5Ge3C0.6/δ-doped Ge(1 1 1) Schottky diodes were measured in the temperature range of 30-300 K by using current-voltage and capacitance-voltage techniques. The Schottky barrier heights and ideality factors were found to be temperature dependent. These anomalous behaviours were explained by Schottky barrier inhomogeneities and interpreted by means of a Gaussian distribution model of the Schottky barrier heights. Following this approach we show that the Mn5Ge3C0.6/Ge contact is described with a single Gaussian distribution and a conduction mechanism mainly based on the thermoionic emission. On the other hand the Mn5Ge3C0.6/δ-doped Ge contact is depicted with two Gaussian distributions according to the temperature and a thermionic-field emission process. The differences between the two types of contacts are discussed according to the distinctive features of the growth of heavily doped germanium thin films.

  5. Mn5Ge3C0.6 /Ge(1 1 1) Schottky contacts tuned by an n-type ultra-shallow doping layer

    NASA Astrophysics Data System (ADS)

    Petit, Matthieu; Hayakawa, Ryoma; Wakayama, Yutaka; Le Thanh, Vinh; Michez, Lisa

    2016-09-01

    Mn5Ge3C x compound is of great interest for spintronics applications. The various parameters of Au/Mn5Ge3C0.6/Ge(1 1 1) and Au/Mn5Ge3C0.6/δ-doped Ge(1 1 1) Schottky diodes were measured in the temperature range of 30–300 K by using current–voltage and capacitance–voltage techniques. The Schottky barrier heights and ideality factors were found to be temperature dependent. These anomalous behaviours were explained by Schottky barrier inhomogeneities and interpreted by means of a Gaussian distribution model of the Schottky barrier heights. Following this approach we show that the Mn5Ge3C0.6/Ge contact is described with a single Gaussian distribution and a conduction mechanism mainly based on the thermoionic emission. On the other hand the Mn5Ge3C0.6/δ-doped Ge contact is depicted with two Gaussian distributions according to the temperature and a thermionic-field emission process. The differences between the two types of contacts are discussed according to the distinctive features of the growth of heavily doped germanium thin films.

  6. Reduction of Schottky barrier height at metal/n-Ge interface by introducing an ultra-high Sn content Ge1-xSnx interlayer

    NASA Astrophysics Data System (ADS)

    Suzuki, Akihiro; Nakatsuka, Osamu; Shibayama, Shigehisa; Sakashita, Mitsuo; Takeuchi, Wakana; Kurosawa, Masashi; Zaima, Shigeaki

    2015-11-01

    We investigated the impact of introducing an ultra-high Sn content Ge1-xSnx interlayer on the electrical properties at the metal/Ge interface. We achieved epitaxial growth of a Ge1-xSnx thin layer with an ultra-high substitutional Sn content of up to 46% on a Ge(001) substrate by considering the misfit strain between Ge1-xSnx and Ge. From the current-voltage characteristics of Al/Ge1-xSnx/n-Ge Schottky diodes, we found an increase in the forward current density of the thermionic emission current with increasing Sn content in the Ge1-xSnx interlayer. The Schottky barrier height estimated in Al/Ge1-xSnx/n-Ge diodes decreases to 0.49 eV with an increase in the Sn content up to 46% of the Ge1-xSnx interlayer. The reduction of the barrier height may be due to the shift of the Fermi level pinning position at the metal/Ge interface with a Ge1-xSnx interlayer whose valence band edge is higher than that of Ge. This result enables the effective reduction of the contact resistivity by introducing a group-IV semiconductor alloy interlayer of Ge1-xSnx into the metal/n-Ge interface.

  7. Electrochemical growth of GaSe nanostructures and their Schottky barrier characteristics

    NASA Astrophysics Data System (ADS)

    Mahmoud, Waleed E.; Al-Ghamdi, A. A.; Shirbeeny, W.; Al-Hazmi, F. S.; Khan, Shamshad A.

    2013-11-01

    Highly crystalline GaSe thin film was synthesized by electrochemical deposition technique on a silicon substrate. The X-ray diffractions showed a hexagonal crystal structure with preferential orientation along (0 0 4) plane. The scanning electron microscopy confirmed the homogenous distribution of deposited GaSe film along the silicon substrate. The high resolution electron microscopy showed that the GaSe nanoparticles have mean diameter of 23 nm. The energy dispersion X-ray spectroscopy revealed a high purity of the as-deposited film. The junction characteristics of GaSe/n-Si diode were investigated. The current-voltage characteristics of the GaSe/n-Si were investigated in the temperature range 23-120 °C. The I-V characteristics exhibit non-linearity indicating Schottky contact at the GaSe and n-Si interface. It was noticed the increase of current under the impact of light. Various device parameters such as series resistance, ideality factor and barrier height were estimated. The effect of temperature on the values of junction parameters was analyzed.

  8. Laser Diode Ignition (LDI)

    NASA Technical Reports Server (NTRS)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  9. Analysis of the Electrical Properties of an Electron Injection Layer in Alq3-Based Organic Light Emitting Diodes.

    PubMed

    Kim, Soonkon; Choi, Pyungho; Kim, Sangsub; Park, Hyoungsun; Baek, Dohyun; Kim, Sangsoo; Choi, Byoungdeog

    2016-05-01

    We investigated the carrier transfer and luminescence characteristics of organic light emitting diodes (OLEDs) with structure ITO/HAT-CN/NPB/Alq3/Al, ITO/HAT-CN/NPB/Alq3/Liq/Al, and ITO/HAT-CN/NPB/Alq3/LiF/A. The performance of the OLED device is improved by inserting an electron injection layer (EIL), which induces lowering of the electron injection barrier. We also investigated the electrical transport behaviors of p-Si/Alq3/Al, p-Si/Alq3/Liq/Al, and p-Si/Alq3/LiF/Al Schottky diodes, by using current-voltage (L-V) and capacitance-voltage (C-V) characterization methods. The parameters of diode quality factor n and barrier height φ(b) were dependent on the interlayer materials between Alq3 and Al. The barrier heights φ(b) were 0.59, 0.49, and 0.45 eV, respectively, and the diode quality factors n were 1.34, 1.31, and 1.30, respectively, obtained from the I-V characteristics. The built in potentials V(bi) were 0.41, 0.42, and 0.42 eV, respectively, obtained from the C-V characteristics. In this experiment, Liq and LiF thin film layers improved the carrier transport behaviors by increasing electron injection from Al to Alq3, and the LiF schottky diode showed better I-V performance than the Liq schottky diode. We confirmed that a Liq or LiF thin film inter-layer governs electron and hole transport at the Al/Alq3 interface, and has an important role in determining the electrical properties of OLED devices.

  10. Polymer/metal hybrid multilayers modified Schottky devices

    SciTech Connect

    Torrisi, V.; Isgrò, G.; Li Destri, G.; Marletta, G.; Ruffino, F.; Grimaldi, M. G.; Crupi, I.

    2013-11-04

    Insulating, polymethylmethacrylate (PMMA), and semiconducting, poly(3-hexylthiophene) (P3HT), nanometer thick polymers/Au nanoparticles based hybrid multilayers (HyMLs) were fabricated on p-Si single-crystal substrate. An iterative method, which involves, respectively, spin-coating (PMMA and P3HT deposition) and sputtering (Au nanoparticles deposition) techniques to prepare Au/HyMLs/p-Si Schottky device, was used. The barrier height and the ideality factor of the Au/HyMLs/p-Si Schottky devices were investigated by current-voltage measurements in the thickness range of 1–5 bilayers. It was observed that the barrier height of such hybrid layered systems can be tuned as a function of bilayers number and its evolution was quantified and analyzed.

  11. Circuit Compatible Model for Electrostatic Doped Schottky Barrier CNTFET

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Khosla, Mamta; Raj, Balwinder

    2016-10-01

    This paper proposes a circuit compatible model for electrostatic doped Schottky barrier carbon nanotube field effect transistor (ED-SBCNTFET). The proposed model is an extension of the Schottky barrier carbon nanotube field effect transistor (SBCNTFET) to ED-SBCNTFET by adding polarity gates, which are used to create electrostatic doping. In ED-SBCNTFET, electrostatic doping is responsible for a fermi level shift of source and drain regions. A mathematical relation has been developed between fermi level shift and polarity gate bias. Both current-voltage ( I- V) and capacitance-voltage ( C- V) characteristics have been efficiently modeled. The results are compared with the reported semi-classical model and simulations from NanoTCAD ViDES for validation. The proposed model is much faster than numerical models as it denies self consistent equations. Finally, circuit application is demonstrated by simulating inverter using the proposed model in HSPICE.

  12. Schottky Barrier Inhomogeneities in Nickel Silicide Transrotational Contacts

    NASA Astrophysics Data System (ADS)

    Alberti, Alessandra; Roccaforte, Fabrizio; Libertino, Sebania; Bongiorno, Corrado; La Magna, Antonino

    2011-11-01

    Ni-silicide/silicon Schottky contacts have been realised by promoting low-temperature Ni-Si interdiffusion during deposition (˜50 °C) and reaction (450 °C) on an oxygen-free [001] silicon surface. A 14 nm transrotational NiSi layer was produced made of extremely flat pseudo-epitaxial domains (˜200 nm in diameter). The current-voltage (I-V) characteristics (340-80 K) have indicated the presence of structural inhomogeneities which lower the Schottky barrier by Δ≈0.1 eV. They have been associated with the core regions of the trans-domains (wherein the silicide lattice is epitaxially aligned to that of Si) since their density (˜2.5×109 cm-2) and dimension (˜10 nm) fit the I-V curves vs temperature following the Tung's approach.

  13. Schottky barriers and interface structure at silicide-silicon interfaces

    NASA Astrophysics Data System (ADS)

    Matthai, C. C.; Rees, N. V.; Shen, T. H.

    Schottky barriers at metal-semiconductor interfaces have attracted much interest in recent years. One of the principal interests has centred on the mechanism for Fermi level pinning. The sililcide-silicon interface has been proposed as a system which is described by the metal induced gap states model. We have performed calculations on the NiSi 2/Si(111) type A and type B interfaces as well as the NiSi 2/Si(100) interface. In addition we have also studied the CoSi 2/Si interface. For the NiSi 2/Si(111) interface, we have further investigated the influence of point defects and hydrostatic pressure on the Schottky barrier height. Based on the results of our calculations we conclude that these interfaces do indeed subscribe to the MIGS model. We also present the results of some total energy calculations and discuss these with experimental observations.

  14. ITON Schottky contacts for GaN based UV photodetectors

    NASA Astrophysics Data System (ADS)

    Vanhove, N.; John, J.; Lorenz, A.; Cheng, K.; Borghs, G.; Haverkort, J. E. M.

    2006-12-01

    Lateral Schottky ultraviolet detectors were fabricated in GaN using indium-tin-oxynitride (ITON) as a contact metal. The GaN semiconductor material was grown on 2 in. sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The Schottky contact has been realized using ITON that has been deposited using sputter techniques. I- V characteristics have been measured with and without UV illumination. The device shows photo-to-dark current ratios of 10 3 at -1 V bias. The spectral responsivity of the UV detectors has been determined. The high spectral responsivity of more than 30 A/W at 240 nm is explained by a high internal gain caused by generation-recombination centers at the ITON/GaN interface. Persistent photocurrent effect has been observed in UV light (on-off) switching operation, time constant and electron capture coefficient of the transition has been determined.

  15. Circuit Compatible Model for Electrostatic Doped Schottky Barrier CNTFET

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Khosla, Mamta; Raj, Balwinder

    2016-06-01

    This paper proposes a circuit compatible model for electrostatic doped Schottky barrier carbon nanotube field effect transistor (ED-SBCNTFET). The proposed model is an extension of the Schottky barrier carbon nanotube field effect transistor (SBCNTFET) to ED-SBCNTFET by adding polarity gates, which are used to create electrostatic doping. In ED-SBCNTFET, electrostatic doping is responsible for a fermi level shift of source and drain regions. A mathematical relation has been developed between fermi level shift and polarity gate bias. Both current-voltage (I-V) and capacitance-voltage (C-V) characteristics have been efficiently modeled. The results are compared with the reported semi-classical model and simulations from NanoTCAD ViDES for validation. The proposed model is much faster than numerical models as it denies self consistent equations. Finally, circuit application is demonstrated by simulating inverter using the proposed model in HSPICE.

  16. Silver nanowires-templated metal oxide for broadband Schottky photodetector

    NASA Astrophysics Data System (ADS)

    Patel, Malkeshkumar; Kim, Hong-Sik; Park, Hyeong-Ho; Kim, Joondong

    2016-04-01

    Silver nanowires (AgNWs)-templated transparent metal oxide layer was applied for Si Schottky junction device, which remarked the record fastest photoresponse of 3.4 μs. Self-operating AgNWs-templated Schottky photodetector showed broad wavelength photodetection with high responsivity (42.4 A W-1) and detectivity (2.75 × 1015 Jones). AgNWs-templated indium-tin-oxide (ITO) showed band-to-band excitation due to the internal photoemission, resulting in significant carrier collection performances. Functional metal oxide layer was formed by AgNWs-templated from ITO structure. The grown ITO above AgNWs has a cylindrical shape and acts as a thermal protector of AgNWs for high temperature environment without any deformation. We developed thermal stable AgNWs-templated transparent oxide devices and demonstrated the working mechanism of AgNWs-templated Schottky devices. We may propose the high potential of hybrid transparent layer design for various photoelectric applications, including solar cells.

  17. Barrier heights of GaN Schottky contacts

    NASA Astrophysics Data System (ADS)

    Kampen, Thorsten U.; Mönch, Winfried

    1997-06-01

    Silver and lead contacts prepared by evaporation onto clean n-GaN(0001) surfaces are rectifying. Their zero-bias barrier heights and ideality factors were determined from the current-voltage characteristics. The observed linear correlation between the barrier heights and the ideality factors is attributed to nonuniform distributions of barrier heights along the interfaces. The barrier heights of ideal Schottky contacts depend on the applied voltage due to the image-force lowering only and their ideally factors nif are approximately 1.01. By extrapolation of our experimental data to n = 1.01, we obtain barrier heights of 0.82 eV and 0.73 eV for uniform Ag- and Pb/n-GaN(0001) contacts, respectively. By applying the idea of metal-induced gap states (MIGS), the barrier heights of ideal Schottky contacts have been predicted to vary linearly as a function of the difference of the metal and the semiconductor electronegativities. The zero-charge-transfer barrier height and slope parameter are characteristic of the respective semiconductor. The zero-charge-transfer barrier heights have been calculated using an empirical tight-binding approach and the slope parameters are given by the optical dielectric constants. The experimental barrier heights of GaN Schottky contacts confirm the predictions of the MIGS-and-electronegativity model.

  18. Watt-level millimeter-wave monolithic diode-grid frequency multipliers

    NASA Technical Reports Server (NTRS)

    Hwu, J. R.; Jou, C. F.; Luhmann, N. C., Jr.; Lam, W. W.; Rutledge, D. B.; Hancock, B.; Lieneweg, U.; Maserjian, J.

    1988-01-01

    Wall-level CW solid-state sources in the millimeter-wave region are needed for plasma diagnostics. Monolithic metal-grid arrays containing in excess of 1000 Schottky diodes have produced watt-level output at 66 GHz in a doubler configuration, in excellent agreement with the large-signal predictions of the frequency multiplication. Current efforts are concentrated on fabricating and developing arrays of a novel barrier-intrinsic-N+ (BIN) diode which promise increased performance in a tripler configuration. Initial tests will be made for a configuration where a tripling efficiency of 35 percent at an output frequency of 100 GHz is predicted. Eventual goals are monolithic BIN diode grids operating at 1 THz.

  19. A Novel Low-Ringing Monocycle Picosecond Pulse Generator Based on Step Recovery Diode

    PubMed Central

    Zhou, Jianming; Yang, Xiao; Lu, Qiuyuan; Liu, Fan

    2015-01-01

    This paper presents a high-performance low-ringing ultra-wideband monocycle picosecond pulse generator, formed using a step recovery diode (SRD), simulated in ADS software and generated through experimentation. The pulse generator comprises three parts, a step recovery diode, a field-effect transistor and a Schottky diode, used to eliminate the positive and negative ringing of pulse. Simulated results validate the design. Measured results indicate an output waveform of 1.88 peak-to-peak amplitude and 307ps pulse duration with a minimal ringing of -22.5 dB, providing good symmetry and low level of ringing. A high degree of coordination between the simulated and measured results is achieved. PMID:26308450

  20. Broadband and high-sensitivity terahertz-wave detection using Fermi-level managed barrier diode

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi; Ishibashi, Tadao

    2016-04-01

    An all-semiconductor-based hetero-barrier rectifier, named a Fermi-level managed barrier diode (FMB diode), was developed for enabling broadband and low-noise THz-wave detection. The barrier height was controlled by the doping in n-type InGaAs so that a very small height barrier (about 53 meV) could be realized for obtaining a small intrinsic differential resistance (about 23 Ω/m2) and a large output current density (more than 5 X 103 A/cm2). The fabricated quasi-optical module was operated at frequencies from 200 GHz to 1 THz at room temperature. The typical zero-biased voltage sensitivity was 1280 V/W at 300 GHz, which was higher than the reported best results for InP-based zero-biased broadband Schottky barrier diodes.

  1. Optoelectronic properties of Ni-GaP diodes with a modified surface

    NASA Astrophysics Data System (ADS)

    Horley, Paul; Vorobiev, Yuri V.; Makhniy, Viktor P.; Sklyarchuk, Valeriy M.

    2016-09-01

    We report the promising results for Ni-GaP Schottky diode structures manufactured on the substrates with chemically-etched nano-scale surface formations that are responsible for a clearly marked luminescence band located at the energy exceeding the band gap of the bulk GaP. The other peculiarity produced by surface patterning concerns a remarkable redshift of material's optical absorption edge. At the room temperature, the height of potential barrier for Ni-GaP structure is 1.8 eV, with the monochromatic sensitivity peaking at 0.35 A/W. The comparative study of diode performance under different light sources exhibited the pronounced linear photocurrent-illumination dependence for about five orders of illumination magnitude, evidencing good optical and electrical quality of Ni-GaP diodes with surface-modified semiconductor substrate.

  2. Integral diode solar cells

    SciTech Connect

    Mardesich, W.; Gillanders, M.S.

    1984-05-01

    To achieve high power at minimum weight, innovative array designs are needed. In the case where shadows fall across a series element in a simple circuit, the effective power will be reduced or eliminated. The conventional method of eliminating this loss is the introduction of bypass diodes. This method increases cost and weight and reduces available surface area. An alternative solution to the shadowing problem is to use integral diode solar cells. The integral diode cell has a built-in diode on the back that protects the adjacent cell and passes the current if it is shadowed. This paper will describe the effort to produce the integral diode cells in a production facility with a minimum cost impact. The electrical characterization of the cell as well as the diode will be presented. These cells can be readily manufactured in a production facility using photoresist defined contacting process.

  3. Coaxial foilless diode

    SciTech Connect

    Kong, Long; Liu, QingXiang; Li, XiangQiang; Wang, ShaoMeng

    2014-05-15

    A kind of coaxial foilless diode is proposed in this paper, with the structure model and operating principle of the diode are given. The current-voltage relation of the coaxial foilless diode and the effects of structure parameters on the relation are studied by simulation. By solving the electron motion equation, the beam deviation characteristic in the presence of external magnetic field in transmission process is analyzed, and the relationship between transverse misalignment with diode parameters is obtained. These results should be of interest to the area of generation and propagation of radial beam for application of generating high power microwaves.

  4. Carbon nanotube intramolecular p-i-n junction diodes with symmetric and asymmetric contacts

    NASA Astrophysics Data System (ADS)

    Chen, Changxin; Liao, Chenghao; Wei, Liangming; Zhong, Hanqing; He, Rong; Liu, Qinran; Liu, Xiaodong; Lai, Yunfeng; Song, Chuanjuan; Jin, Tiening; Zhang, Yafei

    2016-02-01

    A p-i-n junction diode based on the selectively doped single-walled carbon nanotube (SWCNT) had been investigated, in which two opposite ends of individual SWCNT channel were doped into the p- and n-type SWCNT respectively while the middle segment of SWCNT was kept as the intrinsic. The symmetric and asymmetric contacts were used to fabricate the p-i-n junction diodes respectively and studied the effect of the contact on the device characteristics. It was shown that a low reverse saturation current of ~20 pA could be achieved by these both diodes. We found that the use of the asymmetric contact can effectively improve the performance of the p-i-n diode, with the rectification ratio enhanced from ~102 for the device with the Au/Au symmetric contact to >103 for the one with the Pd/Al asymmetric contact. The improvement of the device performance by the asymmetric-contact structure was attributed to the decrease of the effective Schottky-barrier height at the contacts under forward bias, increasing the forward current of the diode. The p-i-n diode with asymmetric contact also had a higher rectification ratio than its counterpart before doping the SWCNT channel, which is because that the p-i-n junction in the device decreased the reverse saturated current.

  5. Carbon nanotube intramolecular p-i-n junction diodes with symmetric and asymmetric contacts

    PubMed Central

    Chen, Changxin; Liao, Chenghao; Wei, Liangming; Zhong, Hanqing; He, Rong; Liu, Qinran; Liu, Xiaodong; Lai, Yunfeng; Song, Chuanjuan; Jin, Tiening; Zhang, Yafei

    2016-01-01

    A p-i-n junction diode based on the selectively doped single-walled carbon nanotube (SWCNT) had been investigated, in which two opposite ends of individual SWCNT channel were doped into the p- and n-type SWCNT respectively while the middle segment of SWCNT was kept as the intrinsic. The symmetric and asymmetric contacts were used to fabricate the p-i-n junction diodes respectively and studied the effect of the contact on the device characteristics. It was shown that a low reverse saturation current of ~20 pA could be achieved by these both diodes. We found that the use of the asymmetric contact can effectively improve the performance of the p-i-n diode, with the rectification ratio enhanced from ~102 for the device with the Au/Au symmetric contact to >103 for the one with the Pd/Al asymmetric contact. The improvement of the device performance by the asymmetric-contact structure was attributed to the decrease of the effective Schottky-barrier height at the contacts under forward bias, increasing the forward current of the diode. The p-i-n diode with asymmetric contact also had a higher rectification ratio than its counterpart before doping the SWCNT channel, which is because that the p-i-n junction in the device decreased the reverse saturated current. PMID:26915400

  6. Vortex diode jet

    DOEpatents

    Houck, Edward D.

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  7. Diodes stabilize LED output

    NASA Technical Reports Server (NTRS)

    Deters, R. A.

    1977-01-01

    Small-signal diodes are placed in series with light-emitting diodes (LED's) to stabilize LED output against temperature fluctuations. Simple inexpensive method compensates for thermal fluctuations over a broad temperature range. Requiring few components, technique is particularly useful where circuit-board space is limited.

  8. Relativistic Bursian diode equilibria

    SciTech Connect

    Ender, A. Y.; Kuznetsov, V. I.; Schamel, H.

    2011-03-15

    A comprehensive study of steady-states of a planar vacuum diode driven by a cold relativistic electron beam is presented. The emitter electric field as a characteristic function for their existence is evaluated in dependence of the diode length, the applied potential V, and the relativistic beam factor at injection {gamma}{sub 0}. It is used to classify the different branches of possible solutions, which encompass electron flows that are (i) transmitted through the diode completely, (ii) partially reflected from a virtual cathode (VC) either within the diode region or at the collector side, and (iii) reflected totally. As a byproduct, the V and {gamma}{sub 0} dependences of both bifurcation points of the minimum potential and of the transmitted current are obtained and the ultrarelativistic limit, {gamma}{sub 0}>>1, is performed. In this highly relativistic regime, the density of electrons appears to be constant across the diode region except for a small area around the VC.

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

    DOEpatents

    Carlson, David E.

    1980-01-01

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

  10. Solar and laser energy conversion with Schottky barrier solar cells

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.; Yeh, Y.-C. M.

    1974-01-01

    Photovoltaic devices have been fabricated for solar and short-wavelength laser energy conversion using the thin metal film-semiconductor (Schottky barrier) approach. Studies of the metal film optical characteristics and the voltage outputs were emphasized. Air mass zero efficiencies of 8 to 9% in GaAs and laser conversion efficiencies of 25% at 4880 A in GaAs(0.6)P(0.4) are presently measured, with projected efficiencies of 15 and 45%, respectively. The techniques, if applied successfully to semiconductor thin films, could have an impact in solar energy terrestrial application.

  11. Systematic tuning of silicon Schottky barrier height by atomic interlayers with low electronegativities

    NASA Astrophysics Data System (ADS)

    Long, Wei

    The Schottky barrier height (SBH) is of great importance to the functionality of semiconductor devices, as it governs the carrier transport across the metal-semiconductor (MS) interface. The presence of the Fermi level (FL) pinning phenomena makes tuning the SBH a difficult goal to achieve. The technique of "partisan interlayer" (PI) was proposed recently to modify the SBH, where stable adsorbate-terminated semiconductor (ATS) surfaces were used to form SBs with subsequently applied metal. When elements with large electronegativities were used to form the ATS, the PI technique was effective in reducing the n-type SBH and increasing the p-type SBH, driven by the expected transfer of charge from the semiconductor to the adsorbates. In this thesis work, elements with electronegativities smaller than that of the semiconductor are used as surface termination. SBHs for Ag, Au and In on Si surfaces are found to increase for the n-type and decrease for the p-type interfaces, by as much as 0.25eV, when Ga, Mg and K are used to terminate the Si surfaces. The present results are thus in agreement with the expected charge transfers from elements with smaller electronegativities to silicon and illustrate the general validity of the PI technique. The chemical stability of these surfaces likely weakens the MS interaction and leads to the (partial) preservation of the surface dipole at the MS interface. However, large degrees of SBH inhomogeneity are observed for diodes on these surfaces, likely due to insufficient stability of these surfaces to completely withstand metal interaction. These results are discussed within the basic models of SBH formation and the implications of these results for SBH control of MS systems are also addressed.

  12. Investigation of current transport parameters of Ti/4H-SiC MPS diode with inhomogeneous barrier

    NASA Astrophysics Data System (ADS)

    Song, Qing-Wen; Zhang, Yu-Ming; Zhang, Yi-Men; Chen, Feng-Ping; Tang, Xiao-Yan

    2011-05-01

    The current transport parameters of 4H-SiC merged PiN Schottky (MPS) diode are investigated in a temperature range of 300-520 K. Evaluation of the experimental current-voltage (I—V) data reveals the decrease in Schottky barrier height Φb but an increase in ideality factor n, with temperature decreasing, which suggests the presence of an inhomogeneous Schottky barrier. The current transport behaviours are analysed in detail using the Tung's model and the effective area of the low barrier patches is extracted. It is found that small low barrier patches, making only 4.3% of the total contact, may significantly influence the device electrical characteristics due to the fact that a barrier height of 0.968 eV is much lower than the average barrier height 1.39 eV. This shows that ion implantation in the Schottky contact region of MPS structure may result in a poor Ti/4H-SiC interface quality. In addition, the temperature dependence of the specific on-resistance (Ron—sp), T2.14, is determined between 300 K and 520 K, which is similar to that predicted by a reduction in electron mobility.

  13. PIN Diode Detectors

    NASA Astrophysics Data System (ADS)

    Ramírez-Jiménez, F. J.

    2008-07-01

    A review of the application of PIN diodes as radiation detectors in particle counting, X- and γ-ray spectroscopy, medical applications and charged particle spectroscopy is presented. As a practical example of its usefulness, a PIN diode and a low noise preamplifier are included in a nuclear spectroscopy chain for X-ray measurements. This is a laboratory session designed to review the main concepts needed to set up the detector-preamplifier array and to make measurements of X-ray energy spectra with a room temperature PIN diode. The results obtained are compared with those obtained with a high resolution cooled Si-Li detector.

  14. Quantum Confinement by Schottky Barriers and its Consequences

    NASA Astrophysics Data System (ADS)

    Chiang, T.-C.

    2005-03-01

    Atomically uniform Pb and Ag films have been successfully grown on Si(111) and Ge(111), respectively, despite a large lattice mismatch in each case. The resulting Schottky barrier at the interface confines the electrons in the film to form quantum well states or subbands. The electronic structure of the film including the ground state wave function can be significantly different from the bulk case, leading to substantial variations in physical properties as a function of film thickness. These variations generally follow a damped oscillatory curve riding on an approximately 1 / 1 N^x . - N^x baseline function, with the exponent x often close to unity. The oscillatory behavior is similar to the shell effect associated with the periodic property variations of elements in the period table. This talk discusses the basic electronic structure of thin metal films as measured by angle-resolved photoemission and the connections to physical properties including the surface energy, thermal stability, density of states, electron-phonon coupling, etc. Quantum size effects can also affect morphological evolution during film growth and heat treatment. The Schottky barrier can be modified by the use of interfactants, and experimental results will be presented to illustrate the utility of this method for quantum control and engineering. In collaboration with M. Upton, D. Ricci, P. Czoschke, L. Basile, S. J. Tang, Hawoong Hong, J. J. Paggel, D.-A. Luh, and T. Miller.

  15. All-back-Schottky-contact thin-film photovoltaics

    NASA Astrophysics Data System (ADS)

    Nardone, Marco

    2016-02-01

    The concept of All-Back-Schottky-Contact (ABSC) thin-film photovoltaic (TFPV) devices is introduced and evaluated using 2D numerical simulation. Reach-through Schottky junctions due to two metals of different work functions in an alternating, side-by-side pattern along the non-illuminated side generate the requisite built-in field. It is shown that our simulation method quantitatively describes existing data for a recently demonstrated heterojunction thin-film cell with interdigitated back contacts (IBCs) of one metal type. That model is extended to investigate the performance of ABSC devices with bimetallic IBCs within a pertinent parameter space. Our calculations indicate that 20% efficiency is achievable with micron-scale features and sufficient surface passivation. Bimetallic, micron-scale IBCs are readily fabricated using photo-lithographic techniques and the ABSC design allows for optically transparent surface passivation layers that need not be electrically conductive. The key advantages of the ABSC-TFPV architecture are that window layers, buffer layers, heterojunctions, and module scribing are not required because both contacts are located on the back of the device.

  16. Growth of ultrahigh-Sn-content Ge1- x Sn x epitaxial layer and its impact on controlling Schottky barrier height of metal/Ge contact

    NASA Astrophysics Data System (ADS)

    Suzuki, Akihiro; Nakatsuka, Osamu; Shibayama, Shigehisa; Sakashita, Mitsuo; Takeuchi, Wakana; Kurosawa, Masashi; Zaima, Shigeaki

    2016-04-01

    We examined the epitaxial growth of an ultrahigh-Sn-content Ge1- x Sn x layer on a Ge substrate and investigated the impact of a Ge1- x Sn x interlayer on the Schottky barrier height (SBH) of the metal/Ge contact. In this study, we considered guidelines of the strain energy and growth temperature to realize a high-Sn-content Ge1- x Sn x layer while keeping the epitaxial growth and suppressing the Sn precipitation. By reducing the film thickness and keeping a low growth temperature, we formed an atomically flat and uniform Ge1- x Sn x epitaxial layer with a Sn content up to 46% on a Ge(001) substrate. We also performed the current density-voltage measurement for Al/Ge1- x Sn x /n-Ge Schottky diodes to estimate the SBH. We found that the SBH of Al/Ge1- x Sn x /n-Ge contact decreases with increasing Sn content in the Ge1- x Sn x interlayer. The shift of the pinning position towards the conduction band edge of Ge is one of the reasons for the SBH reduction of Al/Ge1- x Sn x /n-Ge contact because the valence band edge of Ge1- x Sn x would rise as the Sn content increases.

  17. Inelastic tunnel diodes

    NASA Technical Reports Server (NTRS)

    Anderson, L. M. (Inventor)

    1984-01-01

    Power is extracted from plasmons, photons, or other guided electromagnetic waves at infrared to midultraviolet frequencies by inelastic tunneling in metal-insulator-semiconductor-metal diodes. Inelastic tunneling produces power by absorbing plasmons to pump electrons to higher potential. Specifically, an electron from a semiconductor layer absorbs a plasmon and simultaneously tunnels across an insulator into metal layer which is at higher potential. The diode voltage determines the fraction of energy extracted from the plasmons; any excess is lost to heat.

  18. Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Schubert, E. Fred

    2003-06-01

    Light emitting diodes (LEDs) are devices that are used in a myriad of applications, such as indicator lights in instruments, signage, illuminations, and communication. This graduate textbook covers all aspects of the technology and physics of infrared, visible-spectrum, and white light-emitting diodes (LEDs) made from III-V semiconductors. It reviews elementary properties of LEDs such as the electrical and optical characteristics. Exercises and illustrative examples reinforce the topics discussed.

  19. Explanation of the barrier heights of graphene Schottky contacts by the MIGS-and-electronegativity concept

    NASA Astrophysics Data System (ADS)

    Mönch, Winfried

    2016-09-01

    Graphene-semiconductor contacts exhibit rectifying properties and, in this respect, they behave in exactly the same way as a "conventional" metal-semiconductor or Schottky contacts. It will be demonstrated that, as often assumed, the Schottky-Mott rule does not describe the reported barrier heights of graphene-semiconductor contacts. With "conventional" Schottky contacts, the same conclusion was reached already in 1940. The physical reason is that the Schottky-Mott rule considers no interaction between the metal and the semiconductor. The barrier heights of "conventional" Schottky contacts were explained by the continuum of metal-induced gap states (MIGSs), where the differences of the metal and semiconductor electronegativities describe the size and the sign of the intrinsic electric-dipoles at the interfaces. It is demonstrated that the MIGS-and-electronegativity concept unambiguously also explains the experimentally observed barrier heights of graphene Schottky contacts. This conclusion includes also the barrier heights reported for MoS2 Schottky contacts with "conventional" metals as well as with graphene.

  20. Light-emitting Diodes

    PubMed Central

    Opel, Daniel R.; Hagstrom, Erika; Pace, Aaron K.; Sisto, Krisanne; Hirano-Ali, Stefanie A.; Desai, Shraddha

    2015-01-01

    Background: In the early 1990s, the biological significance of light-emitting diodes was realized. Since this discovery, various light sources have been investigated for their cutaneous effects. Study design: A Medline search was performed on light-emitting diode lights and their therapeutic effects between 1996 and 2010. Additionally, an open-label, investigator-blinded study was performed using a yellow light-emitting diode device to treat acne, rosacea, photoaging, alopecia areata, and androgenetic alopecia. Results: The authors identified several case-based reports, small case series, and a few randomized controlled trials evaluating the use of four different wavelengths of light-emitting diodes. These devices were classified as red, blue, yellow, or infrared, and covered a wide range of clinical applications. The 21 patients the authors treated had mixed results regarding patient satisfaction and pre- and post-treatment evaluation of improvement in clinical appearance. Conclusion: Review of the literature revealed that differing wavelengths of light-emitting diode devices have many beneficial effects, including wound healing, acne treatment, sunburn prevention, phototherapy for facial rhytides, and skin rejuvenation. The authors’ clinical experience with a specific yellow light-emitting diode device was mixed, depending on the condition being treated, and was likely influenced by the device parameters. PMID:26155326

  1. Hydrogen sensitivity of Pt-Pd/rho-CaFe/sub 2/O/sub 4/ diode

    SciTech Connect

    Matsumoto, Y.; Hombo, J. . Faculty of Engineering); Yoshikawa, T.; Sato, E. . Faculty of Engineering)

    1989-03-01

    Hydrogen sensitivity of the current at the Pt-Pd/rho-CaFe/sub 2/O/sub 4/ diode has been studied and compared with that of the Pt-Pd/eta-TiO/sub 2/ diode. The current decreased by H/sub 2/-on in air, but was not recovered by H/sub 2/-off at room temperature. The latter result is different from that for the Pt-Pd/TiO/sub 2/ diode, indicating a mechanism other than the change of the work function of the metal is involved. The Schottky barrier was estimated from activation energy and photocurrent measurements. A surface state mechanism for the H/sub 2/ response of the Pt-Pd/CaFe/sub 2/O/sub 4/ diode is proposed. In this case, the Pt-Pd acts as the catalyst for the reaction of H/sub 2/ with surface states. This mechanism is important for the diode type gas sensor using the semiconductors which show the Fermi level pinning.

  2. Interlayer coupling effects on Schottky barrier in the arsenene-graphene van der Waals heterostructures

    SciTech Connect

    Xia, Congxin Xue, Bin; Wang, Tianxing; Peng, Yuting; Jia, Yu

    2015-11-09

    The electronic characteristics of arsenene-graphene van der Waals (vdW) heterostructures are studied by using first-principles methods. The results show that a linear Dirac-like dispersion relation around the Fermi level can be quite well preserved in the vdW heterostructures. Moreover, the p-type Schottky barrier (0.18 eV) to n-type Schottky barrier (0.31 eV) transition occurs when the interlayer distance increases from 2.8 to 4.5 Å, which indicates that the Schottky barrier can be tuned effectively by the interlayer distance in the vdW heterostructures.

  3. Optical properties of thin gold films applied to Schottky barrier solar cells

    NASA Technical Reports Server (NTRS)

    YEH Y. M.

    1974-01-01

    The Schottky barrier solar cell is considered a possible candidate for converting solar to electrical energy both for space and terrestrial applications. Knowledge of the optical constants of the ultrathin metal film used in the cell is essential for analyzing and designing higher efficiency Schottky barrier cells. The optical constants of 7.5 -nm (75-A) gold films on gallium arsenide have been obtained. In addition, the absolute collection efficiency of Schottky barrier solar cells has been determined from measured spectral response and optical constants of the gold film.

  4. The physics and chemistry of the Schottky barrier height

    SciTech Connect

    Tung, Raymond T.

    2014-03-15

    The formation of the Schottky barrier height (SBH) is a complex problem because of the dependence of the SBH on the atomic structure of the metal-semiconductor (MS) interface. Existing models of the SBH are too simple to realistically treat the chemistry exhibited at MS interfaces. This article points out, through examination of available experimental and theoretical results, that a comprehensive, quantum-mechanics-based picture of SBH formation can already be constructed, although no simple equations can emerge, which are applicable for all MS interfaces. Important concepts and principles in physics and chemistry that govern the formation of the SBH are described in detail, from which the experimental and theoretical results for individual MS interfaces can be understood. Strategies used and results obtained from recent investigations to systematically modify the SBH are also examined from the perspective of the physical and chemical principles of the MS interface.

  5. Silicon-based Coulomb blockade thermometer with Schottky barriers

    NASA Astrophysics Data System (ADS)

    Tuboltsev, V.; Savin, A.; Rogozin, V. D.; Räisänen, J.

    2014-04-01

    A hybrid Coulomb blockade thermometer (CBT) in form of an array of intermittent aluminum and silicon islands connected in series via tunnel junctions was fabricated on a thin silicon-on-insulator (SOI) film. Tunnel barriers in the micrometer size junctions were formed by metal-semiconductor Schottky contacts between aluminium electrodes and heavily doped silicon. Differential conductance through the array vs. bias voltage was found to exhibit characteristic features of competing thermal and charging effects enabling absolute temperature measurements over the range of ˜65 to ˜500 mK. The CBT performance implying the primary nature of the thermometer demonstrated for rather trivial architecture attempted in this work paves a route for introduction of Coulomb blockade thermometry into well-developed contemporary SOI technology.

  6. The physics and chemistry of the Schottky barrier height

    NASA Astrophysics Data System (ADS)

    Tung, Raymond T.

    2014-03-01

    The formation of the Schottky barrier height (SBH) is a complex problem because of the dependence of the SBH on the atomic structure of the metal-semiconductor (MS) interface. Existing models of the SBH are too simple to realistically treat the chemistry exhibited at MS interfaces. This article points out, through examination of available experimental and theoretical results, that a comprehensive, quantum-mechanics-based picture of SBH formation can already be constructed, although no simple equations can emerge, which are applicable for all MS interfaces. Important concepts and principles in physics and chemistry that govern the formation of the SBH are described in detail, from which the experimental and theoretical results for individual MS interfaces can be understood. Strategies used and results obtained from recent investigations to systematically modify the SBH are also examined from the perspective of the physical and chemical principles of the MS interface.

  7. Electronic Transport of an Ni/ n-GaAs Diode Analysed Over a Wide Temperature Range

    NASA Astrophysics Data System (ADS)

    Guzel, A.; Duman, S.; Yildirim, N.; Turut, A.

    2016-06-01

    We have reported a study on current-voltage ( I-V) characteristics and capacitance-voltage ( C-V) of an Ni/ n-GaAs Schottky barrier diode in a wide temperature ( T) range of 100-320 K in steps of 20 K, which is prepared by a magnetron direct current sputtering technique. The ideality factor decreases and barrier height (BH) increases with an increase in the temperature. The variation of the diode parameters with the sample temperature has been attributed to the presence of the lateral inhomogeneities in the BH. It has been seen that the junction current is dominated by thermionic field emission. The carrier concentration, diffusion potential, BH, Fermi energy level and the temperature coefficient of the BH have been calculated from the temperature-dependent C-V-T characteristics.

  8. Influence of the carrier concentration on the piezotronic effect in a ZnO/Au Schottky junction.

    PubMed

    Lu, Shengnan; Qi, Junjie; Gu, Yousong; Liu, Shuo; Xu, Qiankun; Wang, Zengze; Liang, Qijie; Zhang, Yue

    2015-03-14

    The piezotronic effect, which utilizes the piezopotential to engineer the interface characteristics, has been widely exploited to design novel functional device or to optimize the device performance, which is intimately related to the carrier concentration. Here, by constructing a general Schottky diode, the piezotronic effect dependence on the carrier concentration was investigated systematically using ultraviolet (UV) illumination. Scanning Kelvin Probe Microscopy was employed to quantify the carrier concentration in ZnO nanorods under UV illumination. The results showed that the carrier concentration increases with increasing light intensity and an average value of up to 5.6 × 10(18) cm(-3) under 1.2 mW cm(-2) light illumination was obtained. Furthermore, with increasing UV light intensity, an increasingly imperceptible variation in the current-voltage characteristics under strain was observed, which finally disappeared under 1.2 mW cm(-2) light illumination. This phenomenon was attributed to the weakened modulation ability of the piezopotential due to the strengthened screening effect. In addition, the gradual disappearing in the barrier also contributed to the gradual disappearance of the piezotronic effect. This study provides an in-depth understanding of piezotronics, which could be extended to other piezoelectric devices and guide the design and optimization of piezotronic and even piezophototronic devices.

  9. Photovoltaic module bypass diode encapsulation

    NASA Technical Reports Server (NTRS)

    Shepard, N. J., Jr.

    1983-01-01

    The design and processing techniques necessary to incorporate bypass diodes within the module encapsulant are presented. The Semicon PN junction diode cells were selected. Diode junction to heat spreader thermal resistance measurements, performed on a variety of mounted diode chip types and sizes, have yielded values which are consistently below 1 deg C per watt, but show some instability when thermally cycled over the temperature range from -40 to 150 deg C. Three representative experimental modules, each incorporating integral bypass diode/heat spreader assemblies of various sizes, were designed. Thermal testing of these modules enabled the formulation of a recommended heat spreader plate sizing relationship. The production cost of three encapsulated bypass diode/heat spreader assemblies were compared with similarly rated externally mounted packaged diodes. It is concluded that, when proper designed and installed, these bypass diode devices will improve the overall reliability of a terrestrial array over a 20 year design lifetime.

  10. On-Chip Integrated, Silicon–Graphene Plasmonic Schottky Photodetector with High Responsivity and Avalanche Photogain

    NASA Astrophysics Data System (ADS)

    Goykhman, Ilya; Sassi, Ugo; Desiatov, Boris; Mazurski, Noa; Milana, Silvia; de Fazio, Domenico; Eiden, Anna; Khurgin, Jacob; Shappir, Joseph; Levy, Uriel; Ferrari, Andrea C.

    2016-05-01

    We report an on-chip integrated metal-graphene-silicon plasmonic Schottky photodetector with 85mA/W responsivity at 1.55 um and 7% internal quantum efficiency. This is one order of magnitude higher than metal-silicon Schottky photodetectors operated in the same conditions. At a reverse bias of 3V, we achieve avalanche multiplication, with 0.37A/W responsivity and avalanche photogain~2. This paves the way to graphene integrated silicon photonics.

  11. Resistance of 4H-SiC Schottky barriers at high forward-current densities

    SciTech Connect

    Ivanov, P. A. Samsonova, T. P.; Il’inskaya, N. D.; Serebrennikova, O. Yu.; Kon’kov, O. I.; Potapov, A. S.

    2015-07-15

    The resistance of Schottky barriers based on 4H-SiC is experimentally determined at high forward-current densities. The measured resistance is found to be significantly higher than the resistance predicted by classical mechanisms of electron transport in Schottky contacts. An assumption concerning the crucial contribution of the tunnel-transparent intermediate oxide layer between the metal and semiconductor to the barrier resistance is proposed and partially justified.

  12. Hydrogen Sensors Using Nitride-Based Semiconductor Diodes: The Role of Metal/Semiconductor Interfaces

    PubMed Central

    Irokawa, Yoshihiro

    2011-01-01

    In this paper, I review my recent results in investigating hydrogen sensors using nitride-based semiconductor diodes, focusing on the interaction mechanism of hydrogen with the devices. Firstly, effects of interfacial modification in the devices on hydrogen detection sensitivity are discussed. Surface defects of GaN under Schottky electrodes do not play a critical role in hydrogen sensing characteristics. However, dielectric layers inserted in metal/semiconductor interfaces are found to cause dramatic changes in hydrogen sensing performance, implying that chemical selectivity to hydrogen could be realized. The capacitance-voltage (C–V) characteristics reveal that the work function change in the Schottky metal is not responsible mechanism for hydrogen sensitivity. The interface between the metal and the semiconductor plays a critical role in the interaction of hydrogen with semiconductor devises. Secondly, low-frequency C–V characterization is employed to investigate the interaction mechanism of hydrogen with diodes. As a result, it is suggested that the formation of a metal/semiconductor interfacial polarization could be attributed to hydrogen-related dipoles. In addition, using low-frequency C–V characterization leads to clear detection of 100 ppm hydrogen even at room temperature where it is hard to detect hydrogen by using conventional current-voltage (I–V) characterization, suggesting that low-frequency C–V method would be effective in detecting very low hydrogen concentrations. PMID:22346597

  13. Hydrogen sensors using nitride-based semiconductor diodes: the role of metal/semiconductor interfaces.

    PubMed

    Irokawa, Yoshihiro

    2011-01-01

    In this paper, I review my recent results in investigating hydrogen sensors using nitride-based semiconductor diodes, focusing on the interaction mechanism of hydrogen with the devices. Firstly, effects of interfacial modification in the devices on hydrogen detection sensitivity are discussed. Surface defects of GaN under Schottky electrodes do not play a critical role in hydrogen sensing characteristics. However, dielectric layers inserted in metal/semiconductor interfaces are found to cause dramatic changes in hydrogen sensing performance, implying that chemical selectivity to hydrogen could be realized. The capacitance-voltage (C-V) characteristics reveal that the work function change in the Schottky metal is not responsible mechanism for hydrogen sensitivity. The interface between the metal and the semiconductor plays a critical role in the interaction of hydrogen with semiconductor devises. Secondly, low-frequency C-V characterization is employed to investigate the interaction mechanism of hydrogen with diodes. As a result, it is suggested that the formation of a metal/semiconductor interfacial polarization could be attributed to hydrogen-related dipoles. In addition, using low-frequency C-V characterization leads to clear detection of 100 ppm hydrogen even at room temperature where it is hard to detect hydrogen by using conventional current-voltage (I-V) characterization, suggesting that low-frequency C-V method would be effective in detecting very low hydrogen concentrations. PMID:22346597

  14. The development of monolithic alternating current light-emitting diode

    NASA Astrophysics Data System (ADS)

    Yeh, Wen-Yung; Yen, Hsi-Hsuan; Chan, Yi-Jen

    2011-02-01

    The monolithic alternating current light emitting diode (ACLED) has been revealed for several years and was regarded as a potential device for solid state lighting. In this study, we will discuss the characteristics, development status, future challenges, and ITRI's development strategy about ACLED, especially focusing on the development progress of the monolithic GaN-based Schottky barrier diodes integrated ACLED (SBD-ACLED). The SBD-ACLED design can not only improve the chip area utilization ratio but also provide much higher reverse breakdown voltage by integrating four SBDs with the micro-LEDs array in a single chip, which was regarded as a good on-chip ACLED design. According to the experimental results, higher chip efficiency can be reached through SBD-ACLED design since the chip area utilization ratio was increased. Since the principle and the operation condition of ACLED is quite different from those of the typical DCLED, critical issues for ACLED like the current droops, the flicker phenomenon, the safety regulations, the measurement standards and the power fluctuation have been studied for getting a practical and reliable ACLED design. Besides, the "AC LED application and research alliance" (AARA) lead by ITRI in Taiwan for the commercialization works of ACLED has also been introduced.

  15. Tuning the Schottky contacts in the phosphorene and graphene heterostructure by applying strain.

    PubMed

    Liu, Biao; Wu, Li-Juan; Zhao, Yu-Qing; Wang, Lin-Zhi; Caii, Meng-Qiu

    2016-07-20

    The structures and electronic properties of the phosphorene and graphene heterostructure are investigated by density functional calculations using the hybrid Heyd-Scuseria-Ernzerhof (HSE) functional. The results show that the intrinsic properties of phosphorene and graphene are preserved due to the weak van der Waals contact. But the electronic properties of the Schottky contacts in the phosphorene and graphene heterostructure can be tuned from p-type to n-type by the in-plane compressive strains from -2% to -4%. After analyzing the total band structure and density of states of P atom orbitals, we find that the Schottky barrier height (SBH) is determined by the P-pz orbitals. What is more, the variation of the work function of the phosphorene monolayer and the graphene electrode and the Fermi level shift are the nature of the transition of Schottky barrier from n-type Schottky contact to p-type Schottky contact in the phosphorene and graphene heterostructure under different in-plane strains. We speculate that these are general results of tuning of the electronic properties of the Schottky contacts in the phosphorene and graphene heterostructure by controlling the in-plane compressive strains to obtain a promising method to design and fabricate a phosphorene-graphene based field effect transistor.

  16. Heat pipes - Thermal diodes

    NASA Astrophysics Data System (ADS)

    Aptekar, B. F.; Baum, J. M.; Ivanovskii, M. N.; Kolgotin, F. F.; Serbin, V. I.

    The performance concept and peculiarities of the new type of thermal diode with the trap and with the wick breakage are dealt with in the report. The experimental data were obtained and analysed for the working fluid mass and the volume of the liquid in the wick on the forward-mode limiting heat transfer. The flow rate pulsation of the working fluid in the wick was observed visually on the setup with the transparent wall. The quantitative difference on the data on the investigated thermal diode and on the identical heat pipes without the wick breakage is found experimentally concerning the forward-mode limiting heat transfer.

  17. Dual function conducting polymer diodes

    DOEpatents

    Heeger, Alan J.; Yu, Gang

    1996-01-01

    Dual function diodes based on conjugated organic polymer active layers are disclosed. When positively biased the diodes function as light emitters. When negatively biased they are highly efficient photodiodes. Methods of preparation and use of these diodes in displays and input/output devices are also disclosed.

  18. Annealing temperature influence on the degree of inhomogeneity of the Schottky barrier in Ti/4H—SiC contacts

    NASA Astrophysics Data System (ADS)

    Han, Lin-Chao; Shen, Hua-Jun; Liu, Ke-An; Wang, Yi-Yu; Tang, Yi-Dan; Bai, Yun; Xu, Heng-Yu; Wu, Yu-Dong; Liu, Xin-Yu

    2014-12-01

    Tung's model was used to analyze anomalies observed in Ti/SiC Schottky contacts. The degree of the inhomogeneous Schottky barrier after annealing at different temperatures is characterized by the ‘T0 anomaly’ and the difference (△Φ) between the uniformly high barrier height (ΦB0) and the effective barrier height (ΦBeff). Those two parameters of Ti Schottky contacts on 4H—SiC were deduced from I-V measurements in the temperature range of 298 K-503 K. The increase in Schottky barrier (SB) height (ΦB) and decrease in the ideality factor (n) with an increase measurement temperature indicate the presence of an inhomogeneous SB. The degree of inhomogeneity of the Schottky barrier depends on the annealing temperature, and it is at its lowest for 500-°C thermal treatment. The degree of inhomogeneity of the SB could reveal effects of thermal treatments on Schottky contacts in other aspects.

  19. THz operation of self-switching nano-diodes and nano-transistors

    NASA Astrophysics Data System (ADS)

    Mateos, J.; Song, A. M.; Vasallo, B. G.; Pardo, D.; Gonzalez, T.

    2005-06-01

    By means of the microscopic transport description supplied by a semiclassical 2D Monte Carlo simulator, we provide an in depth explanation of the operation (based on electrostatic effects) of the nanoscale unipolar rectifying diode, so called self-switching diode (SSD), recently proposed in [A. M. Song, M. Missous, P. Omling, A. R. Peaker, L. Samuelson, and W. Seifert, Appl. Phys. Lett. 83, 1881 (2003)]. This device provides a rectifying behavior without the use of any doping junction or barrier structure (like in p-n or Schottky barrier diodes) and can be fabricated with a simple single-step lithographic process. The simple downscaling of this device and the use of materials providing high electron velocity (like high In content InGaAs channels) allows to envisage the fabrication of structures working in the THz range. With a slight modification of the geometry of the SSD, a lateral gate contact can be added, so that a nanometer self-switching transistor (SST) can be easily fabricated. We analyze the high frequency performance of the diodes and transistors and provide design considerations for the optimization of the downscaling process.

  20. The effect of oscillation amplitudes on the noise of IMPATT-diode oscillators with uniformly doped GaAs

    NASA Astrophysics Data System (ADS)

    Kornilov, S. A.; Pavlov, V. M.

    Experimental results are presented concerning the effect of load conditions on the spectral densities of fluctuations of the oscillation amplitude and frequency of uniformly doped GaAs Schottky-barrier IMPATT diode oscillators. It is shown that at frequencies of the order of hundreds of Hz to several MHz (where avalanche noise occurs) the character of the dependence of noise levels on oscillation amplitude is determined by the ratio of operating current to nominal current. This dependence becomes very sharp when the operator current approaches the nominal current.

  1. A 492 GHz cooled Schottky receiver for radio-astronomy

    NASA Technical Reports Server (NTRS)

    Hernichel, J.; Schieder, R.; Stutzki, J.; Vowinkel, B.; Winnewisser, G.; Zimmermann, Peter

    1992-01-01

    We developed a 492 GHz cooled GaAs Schottky receiver driven by a solid state local oscillator with a DSB noise temperature of 550 K measured at the telescope. The receiver-bandwidth is approx. equal to 1.0 GHz. Quasi-optical mirrors focus the sky and local oscillator radiation into the mixer. Stability analysis via the Allan variance method shows that the total system including a 1 GHz bandwidth acousto-optical spectrometer built in Cologne allows integration times up to 100 sec per half switching cycle. We successfully used the receiver at the KOSMA 3 m telescope on Gornergrat (3150m) located in the central Swiss Alps near Zermatt during January-February 1992 for observations of the 492 GHz, (CI) (3)P1 to (3)P0 fine structure line in several galactic sources. These observations confirm that Gornergrat is an excellent winter submillimeter site in accordance with previous predictions based on the atmospheric opacity from KOSMA 345 GHz measurements.

  2. Abrupt Schottky Junctions in Al/Ge Nanowire Heterostructures

    PubMed Central

    2015-01-01

    In this Letter we report on the exploration of axial metal/semiconductor (Al/Ge) nanowire heterostructures with abrupt interfaces. The formation process is enabled by a thermal induced exchange reaction between the vapor–liquid–solid grown Ge nanowire and Al contact pads due to the substantially different diffusion behavior of Ge in Al and vice versa. Temperature-dependent I–V measurements revealed the metallic properties of the crystalline Al nanowire segments with a maximum current carrying capacity of about 0.8 MA/cm2. Transmission electron microscopy (TEM) characterization has confirmed both the composition and crystalline nature of the pure Al nanowire segments. A very sharp interface between the ⟨111⟩ oriented Ge nanowire and the reacted Al part was observed with a Schottky barrier height of 361 meV. To demonstrate the potential of this approach, a monolithic Al/Ge/Al heterostructure was used to fabricate a novel impact ionization device. PMID:26052733

  3. Cooling of radioactive isotopes for Schottky mass spectrometry

    SciTech Connect

    Steck, M.; Beckert, K.; Eickhoff, H.; Franzke, B.; Nolden, F.; Reich, H.; Schlitt, B.; Winkler, T.

    1999-01-15

    Nuclear masses of radioactive isotopes can be determined by measurement of their revolution frequency relative to the revolution frequency of reference ions with well-known masses. The resolution of neighboring frequency lines and the accuracy of the mass measurement is dependent on the achievable minimum longitudinal momentum spread of the ion beam. Electron cooling allows an increase of the phase space density by several orders of magnitude. For high intensity beams Coulomb scattering in the dense ion beam limits the beam quality. For low intensity beams a regime exists in which the diffusion due to intrabeam scattering is not dominating any more. The minimum momentum spread {delta}p/p=5x10{sup -7} which is observed by Schottky noise analysis is considerably higher than the value expected from the longitudinal electron temperature. The measured frequency spread results from fluctuations of the magnetic field in the storage ring magnets. Systematic mass measurements have started and can be presently used for ions with half-lives of some ten seconds. For shorter-lived nuclei a stochastic precooling system is in preparation.

  4. Black Phosphorus Transistors with Near Band Edge Contact Schottky Barrier.

    PubMed

    Ling, Zhi-Peng; Sakar, Soumya; Mathew, Sinu; Zhu, Jun-Tao; Gopinadhan, K; Venkatesan, T; Ang, Kah-Wee

    2015-01-01

    Black phosphorus (BP) is a new class of 2D material which holds promise for next generation transistor applications owing to its intrinsically superior carrier mobility properties. Among other issues, achieving good ohmic contacts with low source-drain parasitic resistance in BP field-effect transistors (FET) remains a challenge. For the first time, we report a new contact technology that employs the use of high work function nickel (Ni) and thermal anneal to produce a metal alloy that effectively reduces the contact Schottky barrier height (ΦB) in a BP FET. When annealed at 300 °C, the Ni electrode was found to react with the underlying BP crystal and resulted in the formation of nickel-phosphide (Ni2P) alloy. This serves to de-pin the metal Fermi level close to the valence band edge and realizes a record low hole ΦB of merely ~12 meV. The ΦB at the valence band has also been shown to be thickness-dependent, wherein increasing BP multi-layers results in a smaller ΦB due to bandgap energy shrinkage. The integration of hafnium-dioxide high-k gate dielectric additionally enables a significantly improved subthreshold swing (SS ~ 200 mV/dec), surpassing previously reported BP FETs with conventional SiO2 gate dielectric (SS > 1 V/dec). PMID:26667402

  5. Black Phosphorus Transistors with Near Band Edge Contact Schottky Barrier

    PubMed Central

    Ling, Zhi-Peng; Sakar, Soumya; Mathew, Sinu; Zhu, Jun-Tao; Gopinadhan, K.; Venkatesan, T.; Ang, Kah-Wee

    2015-01-01

    Black phosphorus (BP) is a new class of 2D material which holds promise for next generation transistor applications owing to its intrinsically superior carrier mobility properties. Among other issues, achieving good ohmic contacts with low source-drain parasitic resistance in BP field-effect transistors (FET) remains a challenge. For the first time, we report a new contact technology that employs the use of high work function nickel (Ni) and thermal anneal to produce a metal alloy that effectively reduces the contact Schottky barrier height (ΦB) in a BP FET. When annealed at 300 °C, the Ni electrode was found to react with the underlying BP crystal and resulted in the formation of nickel-phosphide (Ni2P) alloy. This serves to de-pin the metal Fermi level close to the valence band edge and realizes a record low hole ΦB of merely ~12 meV. The ΦB at the valence band has also been shown to be thickness-dependent, wherein increasing BP multi-layers results in a smaller ΦB due to bandgap energy shrinkage. The integration of hafnium-dioxide high-k gate dielectric additionally enables a significantly improved subthreshold swing (SS ~ 200 mV/dec), surpassing previously reported BP FETs with conventional SiO2 gate dielectric (SS > 1 V/dec). PMID:26667402

  6. A 492 GHz cooled Schottky receiver for radio-astronomy

    NASA Astrophysics Data System (ADS)

    Hernichel, J.; Schieder, R.; Stutzki, J.; Vowinkel, B.; Winnewisser, G.; Zimmermann, Peter

    We developed a 492 GHz cooled GaAs Schottky receiver driven by a solid state local oscillator with a DSB noise temperature of 550 K measured at the telescope. The receiver-bandwidth is approx. equal to 1.0 GHz. Quasi-optical mirrors focus the sky and local oscillator radiation into the mixer. Stability analysis via the Allan variance method shows that the total system including a 1 GHz bandwidth acousto-optical spectrometer built in Cologne allows integration times up to 100 sec per half switching cycle. We successfully used the receiver at the KOSMA 3 m telescope on Gornergrat (3150m) located in the central Swiss Alps near Zermatt during January-February 1992 for observations of the 492 GHz, (CI) (3)P1 to (3)P0 fine structure line in several galactic sources. These observations confirm that Gornergrat is an excellent winter submillimeter site in accordance with previous predictions based on the atmospheric opacity from KOSMA 345 GHz measurements.

  7. Thermionic field emission in gold nitride Schottky nanodiodes

    NASA Astrophysics Data System (ADS)

    Spyropoulos-Antonakakis, N.; Sarantopoulou, E.; Kollia, Z.; Samardžija, Z.; Kobe, S.; Cefalas, A. C.

    2012-11-01

    We report on the thermionic field emission and charge transport properties of gold nitride nanodomains grown by pulsed laser deposition with a molecular fluorine laser at 157 nm. The nanodomains are sandwiched between the metallic tip of a conductive atomic force microscope and a thin gold layer forming thus a metal-semiconductor-metal junction. Although the limited existing data in the literature indicate that gold nitride was synthesized previously with low efficiency, poor stability, and metallic character; in this work, it is shown that gold nitride nanodomains exhibit semiconducting behavior and the metal-semiconductor-metal contact can be modeled with the back-to-back Schottky barrier model. From the experimental I-V curves, the main charge carrier transport process is found to be thermionic field emission via electron tunneling. The rectifying, near symmetric and asymmetric current response of nanocontacts is related to the effective contact area of the gold nitride nanodomains with the metals. A lower limit for the majority charge carriers concentration at the boundaries of nanodomains is also established using the full depletion approximation, as nanodomains with thickness as low as 6 nm were found to be conductive. Current rectification and charge memory effects are also observed in "quite small" conductive nanodomains (6-10 nm) due to stored charges. Indeed, charges near the surface are identified as inversion domains in the phase shift mapping performed with electrostatic force microscopy and are attributed to charge trapping at the boundaries of the nanodomains.

  8. Analytical modeling of trilayer graphene nanoribbon Schottky-barrier FET for high-speed switching applications

    NASA Astrophysics Data System (ADS)

    Rahmani, Meisam; Ahmadi, Mohammad Taghi; Abadi, Hediyeh Karimi Feiz; Saeidmanesh, Mehdi; Akbari, Elnaz; Ismail, Razali

    2013-01-01

    Recent development of trilayer graphene nanoribbon Schottky-barrier field-effect transistors (FETs) will be governed by transistor electrostatics and quantum effects that impose scaling limits like those of Si metal-oxide-semiconductor field-effect transistors. The current-voltage characteristic of a Schottky-barrier FET has been studied as a function of physical parameters such as effective mass, graphene nanoribbon length, gate insulator thickness, and electrical parameters such as Schottky barrier height and applied bias voltage. In this paper, the scaling behaviors of a Schottky-barrier FET using trilayer graphene nanoribbon are studied and analytically modeled. A novel analytical method is also presented for describing a switch in a Schottky-contact double-gate trilayer graphene nanoribbon FET. In the proposed model, different stacking arrangements of trilayer graphene nanoribbon are assumed as metal and semiconductor contacts to form a Schottky transistor. Based on this assumption, an analytical model and numerical solution of the junction current-voltage are presented in which the applied bias voltage and channel length dependence characteristics are highlighted. The model is then compared with other types of transistors. The developed model can assist in comprehending experiments involving graphene nanoribbon Schottky-barrier FETs. It is demonstrated that the proposed structure exhibits negligible short-channel effects, an improved on-current, realistic threshold voltage, and opposite subthreshold slope and meets the International Technology Roadmap for Semiconductors near-term guidelines. Finally, the results showed that there is a fast transient between on-off states. In other words, the suggested model can be used as a high-speed switch where the value of subthreshold slope is small and thus leads to less power consumption.

  9. Analytical modeling of trilayer graphene nanoribbon Schottky-barrier FET for high-speed switching applications.

    PubMed

    Rahmani, Meisam; Ahmadi, Mohammad Taghi; Abadi, Hediyeh Karimi Feiz; Saeidmanesh, Mehdi; Akbari, Elnaz; Ismail, Razali

    2013-01-01

    Recent development of trilayer graphene nanoribbon Schottky-barrier field-effect transistors (FETs) will be governed by transistor electrostatics and quantum effects that impose scaling limits like those of Si metal-oxide-semiconductor field-effect transistors. The current-voltage characteristic of a Schottky-barrier FET has been studied as a function of physical parameters such as effective mass, graphene nanoribbon length, gate insulator thickness, and electrical parameters such as Schottky barrier height and applied bias voltage. In this paper, the scaling behaviors of a Schottky-barrier FET using trilayer graphene nanoribbon are studied and analytically modeled. A novel analytical method is also presented for describing a switch in a Schottky-contact double-gate trilayer graphene nanoribbon FET. In the proposed model, different stacking arrangements of trilayer graphene nanoribbon are assumed as metal and semiconductor contacts to form a Schottky transistor. Based on this assumption, an analytical model and numerical solution of the junction current-voltage are presented in which the applied bias voltage and channel length dependence characteristics are highlighted. The model is then compared with other types of transistors. The developed model can assist in comprehending experiments involving graphene nanoribbon Schottky-barrier FETs. It is demonstrated that the proposed structure exhibits negligible short-channel effects, an improved on-current, realistic threshold voltage, and opposite subthreshold slope and meets the International Technology Roadmap for Semiconductors near-term guidelines. Finally, the results showed that there is a fast transient between on-off states. In other words, the suggested model can be used as a high-speed switch where the value of subthreshold slope is small and thus leads to less power consumption. PMID:23363692

  10. Study of basic mechanisms of single event upset in low-capacitance Si and GaAs diodes using high-energy microbeams

    NASA Astrophysics Data System (ADS)

    Nishijima, T.; Sekiguchi, H.; Matsuda, S.; Takeuchi, M.; Shiono, N.; Anayama, H.; Mirio, A.

    1995-09-01

    Current transients induced in Si and GaAs diodes by 2 MeV helium ions were studied by a high-speed digitizing technique (time resolution = 55 ps) using a NbPb superconducting delay-line. We designed and prepared three different types of silicon {P}/{N} junction diodes and GaAs Schottky diodes for the present work. An optimum beam position on the diodes was set using a high-resolution ion beam induced charge (IBIC) imaging system. The space resolving power of the measurement system was confirmed with a small SSD (50 μm ⊘) made on an epi substrate with 20 μm thickness. Current transients were observed for all diodes tested in this work. In the case of {P}/{N} junction diode on a thin (1.5 μm) epi substrate, the collected charge was constant for the bias voltage in a range from - 3 to - 15 V. A funneling factor for a bulk GaAs diode was 1.5.

  11. The current–voltage and capacitance–voltage characteristics at high temperatures of Au Schottky contact to n-type GaAs

    SciTech Connect

    Özerli, Halil; Karteri, İbrahim; Karataş, Şükrü; Altindal, Şemsettin

    2014-05-01

    Highlights: • The electronic parameters of the diode under temperature were investigated. • The barrier heights have a Gaussian distribution. • Au/n-GaAs diode exhibits a rectification behavior. - Abstract: We have investigated the temperature-dependent current–voltage (I–V) and capacitance–voltage (C–V) characteristics of Au/n-GaAs Schottky barrier diodes (SBDs) in the temperature range of 280–415 K. The barrier height for the Au/n-type GaAs SBDs from the I–V and C–V characteristics have varied from 0.901 eV to 0.963 eV (I–V) and 1.234 eV to 0.967 eV (C–V), and the ideality factor (n) from 1.45 to 1.69 in the temperature range 280–415 K. The conventional Richardson plots are found to be linear in the temperature range measured. Both the ln(I{sub 0}/T{sup 2}) versus (kT){sup −1} and ln(I{sub 0}/T{sup 2}) versus (nkT){sup −1} plots gives a straight line corresponding to activation energies 0.773 eV and 0.870 eV, respectively. A Φ{sub b0} versus 1/T plot was drawn to obtain evidence of a Gaussian distribution of the BHs, and values of Φ{sup ¯}{sub b0} = 1.071 eV and σ{sub 0} = 0.094 V for the mean BH and zero-bias standard deviation have been obtained from this plot.

  12. Spin-Wave Diode

    NASA Astrophysics Data System (ADS)

    Lan, Jin; Yu, Weichao; Wu, Ruqian; Xiao, Jiang

    2015-10-01

    A diode, a device allowing unidirectional signal transmission, is a fundamental element of logic structures, and it lies at the heart of modern information systems. The spin wave or magnon, representing a collective quasiparticle excitation of the magnetic order in magnetic materials, is a promising candidate for an information carrier for the next-generation energy-saving technologies. Here, we propose a scalable and reprogrammable pure spin-wave logic hardware architecture using domain walls and surface anisotropy stripes as waveguides on a single magnetic wafer. We demonstrate theoretically the design principle of the simplest logic component, a spin-wave diode, utilizing the chiral bound states in a magnetic domain wall with a Dzyaloshinskii-Moriya interaction, and confirm its performance through micromagnetic simulations. Our findings open a new vista for realizing different types of pure spin-wave logic components and finally achieving an energy-efficient and hardware-reprogrammable spin-wave computer.

  13. Analysing black phosphorus transistors using an analytic Schottky barrier MOSFET model

    PubMed Central

    Penumatcha, Ashish V.; Salazar, Ramon B.; Appenzeller, Joerg

    2015-01-01

    Owing to the difficulties associated with substitutional doping of low-dimensional nanomaterials, most field-effect transistors built from carbon nanotubes, two-dimensional crystals and other low-dimensional channels are Schottky barrier MOSFETs (metal-oxide-semiconductor field-effect transistors). The transmission through a Schottky barrier-MOSFET is dominated by the gate-dependent transmission through the Schottky barriers at the metal-to-channel interfaces. This makes the use of conventional transistor models highly inappropriate and has lead researchers in the past frequently to extract incorrect intrinsic properties, for example, mobility, for many novel nanomaterials. Here we propose a simple modelling approach to quantitatively describe the transfer characteristics of Schottky barrier-MOSFETs from ultra-thin body materials accurately in the device off-state. In particular, after validating the model through the analysis of a set of ultra-thin silicon field-effect transistor data, we have successfully applied our approach to extract Schottky barrier heights for electrons and holes in black phosphorus devices for a large range of body thicknesses. PMID:26563458

  14. Analysing black phosphorus transistors using an analytic Schottky barrier MOSFET model.

    PubMed

    Penumatcha, Ashish V; Salazar, Ramon B; Appenzeller, Joerg

    2015-01-01

    Owing to the difficulties associated with substitutional doping of low-dimensional nanomaterials, most field-effect transistors built from carbon nanotubes, two-dimensional crystals and other low-dimensional channels are Schottky barrier MOSFETs (metal-oxide-semiconductor field-effect transistors). The transmission through a Schottky barrier-MOSFET is dominated by the gate-dependent transmission through the Schottky barriers at the metal-to-channel interfaces. This makes the use of conventional transistor models highly inappropriate and has lead researchers in the past frequently to extract incorrect intrinsic properties, for example, mobility, for many novel nanomaterials. Here we propose a simple modelling approach to quantitatively describe the transfer characteristics of Schottky barrier-MOSFETs from ultra-thin body materials accurately in the device off-state. In particular, after validating the model through the analysis of a set of ultra-thin silicon field-effect transistor data, we have successfully applied our approach to extract Schottky barrier heights for electrons and holes in black phosphorus devices for a large range of body thicknesses. PMID:26563458

  15. Perforated diode neutron sensors

    NASA Astrophysics Data System (ADS)

    McNeil, Walter J.

    A novel design of neutron sensor was investigated and developed. The perforated, or micro-structured, diode neutron sensor is a concept that has the potential to enhance neutron sensitivity of a common solid-state sensor configuration. The common thin-film coated diode neutron sensor is the only semiconductor-based neutron sensor that has proven feasible for commercial use. However, the thin-film coating restricts neutron counting efficiency and severely limits the usefulness of the sensor. This research has shown that the perforated design, when properly implemented, can increase the neutron counting efficiency by greater than a factor of 4. Methods developed in this work enable detectors to be fabricated to meet needs such as miniaturization, portability, ruggedness, and adaptability. The new detectors may be used for unique applications such as neutron imaging or the search for special nuclear materials. The research and developments described in the work include the successful fabrication of variant perforated diode neutron detector designs, general explanations of fundamental radiation detector design (with added focus on neutron detection and compactness), as well as descriptive theory and sensor design modeling useful in predicting performance of these unique solid-state radiation sensors. Several aspects in design, fabrication, and operational performance have been considered and tested including neutron counting efficiency, gamma-ray response, perforation shapes and depths, and silicon processing variations. Finally, the successfully proven technology was applied to a 1-dimensional neutron sensor array system.

  16. Silicon nanowire Esaki diodes.

    PubMed

    Schmid, Heinz; Bessire, Cedric; Björk, Mikael T; Schenk, Andreas; Riel, Heike

    2012-02-01

    We report on the fabrication and characterization of silicon nanowire tunnel diodes. The silicon nanowires were grown on p-type Si substrates using Au-catalyzed vapor-liquid-solid growth and in situ n-type doping. Electrical measurements reveal Esaki diode characteristics with peak current densities of 3.6 kA/cm(2), peak-to-valley current ratios of up to 4.3, and reverse current densities of up to 300 kA/cm(2) at 0.5 V reverse bias. Strain-dependent current-voltage (I-V) measurements exhibit a decrease of the peak tunnel current with uniaxial tensile stress and an increase of 48% for 1.3 GPa compressive stress along the <111> growth direction, revealing the strain dependence of the Si band structure and thus the tunnel barrier. The contributions of phonons to the indirect tunneling process were probed by conductance measurements at 4.2 K. These measurements show phonon peaks at energies corresponding to the transverse acoustical and transverse optical phonons. In addition, the low-temperature conductance measurements were extended to higher biases to identify potential impurity states in the band gap. The results demonstrate that the most likely impurity, namely, Au from the catalyst particle, is not detectable, a finding that is also supported by the excellent device properties of the Esaki diodes reported here.

  17. Interface properties of an O2 annealed Au/Ni/n-Al0.18Ga0.82N Schottky contact

    NASA Astrophysics Data System (ADS)

    Legodi, M. J.; Meyer, W. E.; Auret, F. D.

    2012-05-01

    We oxidized a Ni/Au metal bi-layer contact fabricated on HVPE Al0.18Ga0.82N from 373 K to 573 K in 100 K steps. In the range 1 kHz to 2 MHz, the Capacitance-Voltage-Frequency (C-V-f) measurements reveal a frequency dispersion of the capacitance and the presence of an anomalous peak at 0.4 V owing to the presence of interface states in the as deposited contact system. The dispersion was progressively removed by O2 anneals from temperatures as low as 373 K. These changes are accompanied by an improvement in the overall quality of the Schottky system: the ideality factor, n, improves from 2.09 to 1.26; the Schottky barrier height (SBH), determined by the Norde [1] method, increases from 0.72 eV to 1.54 eV. From the Nicollian and Goetzberger model [2], we calculated the energy distribution of the density of interface states, NSS. Around 1 eV above the Al0.18Ga0.82N valence band, NSS, decreases from 2.3×1012 eV-1 cm-2 for the un-annealed diodes to 1.3×1012 eV-1 cm-2 after the 573 K anneal. Our results suggest the formation of an insulating NiO leading to a MIS structure for the oxidized Au/Ni/Al0.18Ga0.82N contact.

  18. Cryogenic thermal diode heat pipes

    NASA Technical Reports Server (NTRS)

    Alario, J.

    1979-01-01

    The development of spiral artery cryogenic thermal diode heat pipes was continued. Ethane was the working fluid and stainless steel the heat pipe material in all cases. The major tasks included: (1) building a liquid blockage (blocking orifice) thermal diode suitable for the HEPP space flight experiment; (2) building a liquid trap thermal diode engineering model; (3) retesting the original liquid blockage engineering model, and (4) investigating the startup dynamics of artery cryogenic thermal diodes. An experimental investigation was also conducted into the wetting characteristics of ethane/stainless steel systems using a specially constructed chamber that permitted in situ observations.

  19. A new cryogenic diode thermometer

    NASA Astrophysics Data System (ADS)

    Courts, S. S.; Swinehart, P. R.; Yeager, C. J.

    2002-05-01

    While the introduction of yet another cryogenic diode thermometer is not earth shattering, a new diode thermometer, the DT-600 series, recently introduced by Lake Shore Cryotronics, possesses three features that make it unique among commercial diode thermometers. First, these diodes have been probed at the chip level, allowing for the availability of a bare chip thermometer matching a standard curve-an important feature in situations where real estate is at a premium (IR detectors), or where in-situ calibration is difficult. Second, the thermometry industry has assumed that interchangeability should be best at low temperatures. Thus, good interchangeability at room temperatures implies a very good interchangeability at cryogenic temperature, resulting in a premium priced sensor. The DT-600 series diode thermometer is available in an interchangeability band comparable to platinum RTDs with the added advantage of interchangeability to 2 K. Third, and most important, the DT-600 series diode does not exhibit an instability in the I-V characteristic in the 8 K to 20 K temperature range that is observed in other commercial diode thermometer devices [1]. This paper presents performance characteristics for the DT-600 series diode thermometer along with a comparison of I-V curves for this device and other commercial diode thermometers exhibiting an I-V instability.

  20. Dopant-segregated Schottky barrier MOSFETs with an insulated dielectric oxide

    NASA Astrophysics Data System (ADS)

    Shih, Chun-Hsing; Lin, Ching-Chang

    2010-06-01

    An insulated dielectric oxide (IDO) is presented for the dopant-segregated Schottky barrier MOSFETs (DS-SBMOS) to suppress the unwanted on- and off-state leakage currents in short-channel DS-SBMOS. The effects of the IDO on DS-SBMOS are investigated using two-dimensional device simulations. Although the dopant segregation technique can efficiently modify a Schottky barrier to improve Schottky barrier MOSFETs, the performance of scaled DS-SBMOS suffers from degraded short-channel behavior and ambipolar conduction from the extension of a heavily doped segregation layer. With sidewall IDO insulators between the heavily doped N+ segregation layer and P+ halo region, band-to-band and ambipolar leakage currents are simultaneously minimized. Thus, an optimal halo can be utilized to control the short-channel effect without any constraints in problematic leakage currents. Using the IDO architecture, DS-SBMOS can be successfully scaled as a promising candidate for next-generation CMOS devices.

  1. Voltage tunable multiple quantum well distributed feedback filter with an electron beam written Schottky grating

    NASA Astrophysics Data System (ADS)

    Zia, O.; Bhattacharya, P. K.; Singh, J.; Brock, T.

    1994-08-01

    A novel optoelectronic filter voltage-tunable characteristics has been developed and implemented in a multiquantum well waveguide device. By virtue of the quantum-confined Stark effect, the refractive index in quantum wells at the periphery of a guiding region can be given a periodicity in the guiding direction by application of a bias on an electron-beam patterned Schottky grating atop the guide. If the period of the Schottky grating and associated index profile satisfies the Bragg condition, as in a resonant distributed feedback structure, band-reject filtering results. Aftering the bias on the Schottky grating changes the refractive index in the wells, thereby providing tunability of the wavelength at which Bragg diffraction occurs.

  2. ON current enhancement of nanowire Schottky barrier tunnel field effect transistors

    NASA Astrophysics Data System (ADS)

    Takei, Kohei; Hashimoto, Shuichiro; Sun, Jing; Zhang, Xu; Asada, Shuhei; Xu, Taiyu; Matsukawa, Takashi; Masahara, Meishoku; Watanabe, Takanobu

    2016-04-01

    Silicon nanowire Schottky barrier tunnel field effect transistors (NW-SBTFETs) are promising structures for high performance devices. In this study, we fabricated NW-SBTFETs to investigate the effect of nanowire structure on the device characteristics. The NW-SBTFETs were operated with a backgate bias, and the experimental results demonstrate that the ON current density is enhanced by narrowing the width of the nanowire. We confirmed using the Fowler-Nordheim plot that the drain current in the ON state mainly comprises the quantum tunneling component through the Schottky barrier. Comparison with a technology computer aided design (TCAD) simulation revealed that the enhancement is attributed to the electric field concentration at the corners of cross-section of the NW. The study findings suggest an effective approach to securing the ON current by Schottky barrier width modulation.

  3. Photoheat-induced Schottky nanojunction and indirect Mott transition in VO2: photocurrent analysis

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Tak; Kim, Minjung; Sohn, Ahrum; Slusar, Tetiana; Seo, Giwan; Cheong, Hyeonsik; Kim, Dong-Wook

    2016-03-01

    In order to elucidate a mechanism of the insulator-to-metal transition (IMT) for a Mott insulator VO2 (3d 1), we present Schottky nanojunctions and the structural phase transition (SPT) by simultaneous nanolevel measurements of photocurrent and Raman scattering in microlevel devices. The Schottky nanojunction with the monoclinic metallic phase between the monoclinic insulating phases is formed by the photoheat-induced IMT not accompanied with the SPT. The temperature dependence of the Schottky junction reveals that the Mott insulator has an electronic structure of an indirect subband between the main Hubbard d bands. The IMT as reverse process of the Mott transition occurs by temperature-induced excitation of bound charges in the indirect semiconductor band, most likely formed by impurities such as oxygen deficiency. The metal band (3d 1) for the Mott insulator is screened (trapped) by the indirect band (impurities).

  4. Ultra-short channel GaN high electron mobility transistor-like Gunn diode with composite contact

    SciTech Connect

    Wang, Ying; Yang, Lin'an Wang, Zhizhe; Chen, Qing; Huang, Yonghong; Dai, Yang; Chen, Haoran; Zhao, Hongliang; Hao, Yue

    2014-09-07

    We present a numerical analysis on an ultra-short channel AlGaN/GaN HEMT-like planar Gunn diode based on the velocity-field dependence of two-dimensional electron gas (2-DEG) channel accounting for the ballistic electron acceleration and the inter-valley transfer. In particular, we propose a Schottky-ohmic composite contact instead of traditional ohmic contact for the Gunn diode in order to significantly suppress the impact ionization at the anode side and shorten the “dead zone” at the cathode side, which is beneficial to the formation and propagation of dipole domain in the ultra-short 2-DEG channel and the promotion of conversion efficiency. The influence of the surface donor-like traps on the electron domain in the 2-DEG channel is also included in the simulation.

  5. A high-frequency Schottky detector for use in the Tevatron

    SciTech Connect

    Goldberg, D.A.; Lambertson, G.R.

    1990-09-01

    A vexing problem associated with detection of Schottky signals from a bunched beam is the presence of the coherent signal, which can be 10 or more orders of magnitude greater than the Schottky signal. To overcome this difficulty, we have constructed a Schottky detector for the Tevatron collider in the form of a high-Q ({approx}5000) resonant cavity which operates at roughly 2 GHz, well above the frequency at which the single-bunch frequency spectrum begins to roll off ({approx}200--300 MHz for the Tevatron). The detector is capable of sensing independently the vertical and horizontal particle motions. The 2 GHz Schottky signals are down-converted to frequencies below 100 kHz to permit relatively rapid high-resolution analysis using a FFT spectrum analyzer. The initial installation consists of a single cavity; a second detector will be built which employs a pair of phased cavities to permit discrimination between p's and {bar p}'s. Details of the design of both the cavity and the associated electronics are presented. Spectra obtained from the detector show clearly observable Schottky betatron lines, free of coherent contaminants; also seen are the common-mode'' longitudinal signals due to the offset of the beam from the detector center. The latter signals indicate that at 2 GHz, the coherent single-bunch spectrum from the detector is reduced by >80 dB; therefore, in normal collider operation, the Schottky betatron lines are essentially entirely free of coherent contaminants. Experimental data will be presented showing how the detector spectra can be used to measure such properties as transverse emittance and synchrotron frequency. 3 refs., 4 figs., 5 tabs.

  6. A high-frequency Schottky detector for use in the Tevatron

    SciTech Connect

    Goldberg, D.A.; Lambertson, G.R. )

    1991-06-01

    A vexing problem associated with detection of Schottky signals from a bunched beam is the presence of the coherent signal, which can be 10 or more orders of magnitude greater than the Schottky signal. To overcome this difficulty, we have constructed a Schottky detector for the Tevatron collider in the form of a high-Q({approx}5000) resonant cavity which operates at roughly 2 GHz, well above the frequency at which the single-bunch frequency spectrum begins to roll off ({approx}200--300 MHz for the Tevatron). The detector is capable of sensing independently the vertical and horizontal particle motions. The 2 GHz Schottky signals are down-converted to frequencies below 100 kHz to permit relatively rapid high-resolution analysis using a FFT spectrum analyzer. The initial installation consists of a single cavity; a second detector will be built which employs a pair of phased cavities to permit discrimination between p's and {bar p}'s. Details of the design of both the cavity and the associated electronics are presented. Spectra obtained from the detector show clearly observable Schottky betatron lines, free of coherent contaminants; also seen are the common-mode'' longitudinal signals due to the offset of the beam from the detector center. The latter signals indicate that at 2 GHz, the coherent single-bunch spectrum from the detector is reduced by {gt}80 dB; therefore, in normal collider operation, the Schottky betatron lines are essentially entirely free of coherent contaminants. Experimental data will be presented showing how the detector spectra can be used to measure such properties as transverse emittance and synchrotron frequency.

  7. Schottky Junctions Studied Using Korringa-Kohn-Rostoker Nonequilibrium Green's Function Method

    NASA Astrophysics Data System (ADS)

    Ogura, Masako; Akai, Hisazumi

    2016-10-01

    A scheme that combines the nonequilibrium Green's function method with the Korringa-Kohn-Rostoker Green's function method is proposed. The method is applied to Schottky junctions composed of an Al/GaN/Al trilayer. The results show that a Schottky barrier is formed at an undoped GaN and Al interface. The transport property of this system under various finite bias voltages is calculated. It is shown that the asymmetric behavior of electron transport against the direction of bias voltage occurs in this system, confirming the feature of rectification.

  8. Tunable schottky barrier in blue phosphorus-graphene heterojunction with normal strain

    NASA Astrophysics Data System (ADS)

    Zhu, Jiaduo; Zhang, Jincheng; Hao, Yue

    2016-08-01

    The graphene-blue phosphorus van deer Waals (vDW) heterojunction was studied by using density functional theory. Our calculations reveal that the intrinsic electronic structure of blue phosphorus and graphene is well preserved and forms an n-type schottky barrier at equilibrium state. With increasing of normal tensile strain, the n-type is well kept. With compressive strain, the Dirac cone of graphene gradually shifts from conduction band minimum to valance band maximum of blue phosphorus, leading a turning of schottky barrier from n-type to p-type, which indicates an effective way to tune the electronic structure of vDW heterojunction.

  9. A Silicon Nanocrystal Schottky Junction Solar Cell produced from Colloidal Silicon Nanocrystals.

    PubMed

    Liu, Chin-Yi; Kortshagen, Uwe R

    2010-05-20

    Solution-processed semiconductors are seen as a promising route to reducing the cost of the photovoltaic device manufacture. We are reporting a single-layer Schottky photovoltaic device that was fabricated by spin-coating intrinsic silicon nanocrystals (Si NCs) from colloidal suspension. The thin-film formation process was based on Si NCs without any ligand attachment, exchange, or removal reactions. The Schottky junction device showed a photovoltaic response with a power conversion efficiency of 0.02%, a fill factor of 0.26, short circuit-current density of 0.148 mA/cm2, and open-circuit voltage of 0.51 V.

  10. On-Chip Integrated, Silicon-Graphene Plasmonic Schottky Photodetector with High Responsivity and Avalanche Photogain.

    PubMed

    Goykhman, Ilya; Sassi, Ugo; Desiatov, Boris; Mazurski, Noa; Milana, Silvia; de Fazio, Domenico; Eiden, Anna; Khurgin, Jacob; Shappir, Joseph; Levy, Uriel; Ferrari, Andrea C

    2016-05-11

    We report an on-chip integrated metal graphene-silicon plasmonic Schottky photodetector with 85 mA/W responsivity at 1.55 μm and 7% internal quantum efficiency. This is one order of magnitude higher than metal-silicon Schottky photodetectors operated in the same conditions. At a reverse bias of 3 V, we achieve avalanche multiplication, with 0.37A/W responsivity and avalanche photogain ∼2. This paves the way to graphene integrated silicon photonics.

  11. On-Chip Integrated, Silicon–Graphene Plasmonic Schottky Photodetector with High Responsivity and Avalanche Photogain

    PubMed Central

    2016-01-01

    We report an on-chip integrated metal graphene–silicon plasmonic Schottky photodetector with 85 mA/W responsivity at 1.55 μm and 7% internal quantum efficiency. This is one order of magnitude higher than metal–silicon Schottky photodetectors operated in the same conditions. At a reverse bias of 3 V, we achieve avalanche multiplication, with 0.37A/W responsivity and avalanche photogain ∼2. This paves the way to graphene integrated silicon photonics. PMID:27053042

  12. A model to non-uniform Ni Schottky contact on SiC annealed at elevated temperatures

    SciTech Connect

    Pristavu, G.; Brezeanu, G.; Badila, M.; Pascu, R.; Danila, M.; Godignon, P.

    2015-06-29

    Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by a mixed barrier on the contact area and interface states. A simple analytical model that establishes a quantitative correlation between Schottky contact parameter variation with temperature and barrier height non-uniformity is proposed. A Schottky contact surface with double Schottky barrier is considered. The main model parameters are the lower barrier (Φ{sub Bn,l}) and a p factor which quantitatively evaluates the barrier non-uniformity on the Schottky contact area. The model is validated on Ni/4H-SiC Schottky contacts, post metallization sintered at high temperatures. The measured I{sub F}–V{sub F}–T characteristics, selected so as not to be affected by interface states, were used for model correlation. An inhomogeneous double Schottky barrier (with both nickel silicide and Ni droplets at the interface) is formed by a rapid thermal annealing (RTA) at 750 °C. High values of the p parameter are obtained from samples annealed at this temperature, using the proposed model. A significant improvement in the electrical properties occurs following RTA at 800 °C. The expansion of the Ni{sub 2}Si phase on the whole contact area is evinced by an X-Ray diffraction investigation. In this case, the p factor is much lower, attesting the uniformity of the contact. The model makes it possible to evaluate the real Schottky barrier, for a homogenous Schottky contact. Using data measured on samples annealed at 800 °C, a true barrier height of around 1.73 V has been obtained for Ni{sub 2}Si/4H-SiC Schottky contacts.

  13. Cylindrical electron beam diode

    DOEpatents

    Bolduc, Paul E.

    1976-01-01

    A diode discharge device may include a tubular anode concentrically encircled by and spaced from a tubular cathode electrode with ends intermediate the ends of said anode electrode, and a metal conductive housing having a tubular wall disposed around the cathode electrode with end walls connected to the anode electrode. High energy electron current coupling is through an opening in the housing tubular wall to a portion of the cathode electrode intermediate its ends. Suitable utilization means may be within the anode electrode at positions to be irradiated by electrons emitted from the cathode electrode and transmitted through the anode walls.

  14. Semiconductor laser diode

    SciTech Connect

    Amann, M.C.

    1982-09-28

    A semiconductor laser diode is disclosed with a connection electrode consisting of a chromium/gold alloy on a highly-doped gallium arsenide layer. The gallium arsenide layer is strip shaped and overlies a further lesser doped layer of gallium aluminum arsenide. The chromium/gold contact has a low-resistance junction only in the region of the more highly doped layer so that a strip shaped restriction of the current path occurs in the semiconductor body. Accordingly, a laser-active zone which is only strip-shaped is achieved.

  15. Making an ultrastable diode laser

    NASA Astrophysics Data System (ADS)

    Archibald, James; Washburn, Matt; van Zijll, Marshall; Erickson, Christopher; Neyenhuis, Brian; Doermann, Greg; Durfee, Dallin

    2006-10-01

    We have constructed a 657nm diode laser with excellent stability for use in an atom interferometer. The laser is a grating-stabilized diode laser is locked to a high-finesse cavity using the Pound-Drever-Hall method. We have measured a linewidth of about 1 kHz and are working on several improvements which should further reduce our linewidth.

  16. Diode laser applications in urology

    NASA Astrophysics Data System (ADS)

    Sam, Richard C.; Esch, Victor C.

    1995-05-01

    Diode lasers are air-cooled, efficient, compact devices which have the potential of very low cost when produced in quantity. The characteristics of diode lasers are discussed. Their applications in interstitial thermal treatment of the prostate, and laser ablation of prostate tissues, will be presented.

  17. Gallium phosphide high temperature diodes

    NASA Technical Reports Server (NTRS)

    Chaffin, R. J.; Dawson, L. R.

    1981-01-01

    High temperature (300 C) diodes for geothermal and other energy applications were developed. A comparison of reverse leakage currents of Si, GaAs, and GaP was made. Diodes made from GaP should be usable to 500 C. A Liquid Phase Epitaxy (LPE) process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers were cut into die and metallized to make the diodes. These diodes produce leakage currents below ten to the -9th power A/sq cm at 400 C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  18. Simplified ZrTiO x -based RRAM cell structure with rectifying characteristics by integrating Ni/n + -Si diode

    PubMed Central

    2014-01-01

    A simplified one-diode one-resistor (1D1R) resistive switching memory cell that uses only four layers of TaN/ZrTiO x /Ni/n+-Si was proposed to suppress sneak current where TaN/ZrTiO x /Ni can be regarded as a resistive-switching random access memory (RRAM) device while Ni/n+-Si acts as an Schottky diode. This is the first RRAM cell structure that employs metal/semiconductor Schottky diode for current rectifying. The 1D1R cell exhibits bipolar switching behavior with SET/RESET voltage close to 1 V without requiring a forming process. More importantly, the cell shows tight resistance distribution for different states, significantly rectifying characteristics with forward/reverse current ratio higher than 103 and a resistance ratio larger than 103 between two states. Furthermore, the cell also displays desirable reliability performance in terms of long data retention time of up to 104 s and robust endurance of 105 cycles. Based on the promising characteristics, the four-layer 1D1R structure holds the great potential for next-generation nonvolatile memory technology. PMID:24936165

  19. Light Emitting Diode (LED)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  20. Thermally Stable Silver Nanowires-Embedding Metal Oxide for Schottky Junction Solar Cells.

    PubMed

    Kim, Hong-Sik; Patel, Malkeshkumar; Park, Hyeong-Ho; Ray, Abhijit; Jeong, Chaehwan; Kim, Joondong

    2016-04-01

    Thermally stable silver nanowires (AgNWs)-embedding metal oxide was applied for Schottky junction solar cells without an intentional doping process in Si. A large scale (100 mm(2)) Schottky solar cell showed a power conversion efficiency of 6.1% under standard illumination, and 8.3% under diffused illumination conditions which is the highest efficiency for AgNWs-involved Schottky junction Si solar cells. Indium-tin-oxide (ITO)-capped AgNWs showed excellent thermal stability with no deformation at 500 °C. The top ITO layer grew in a cylindrical shape along the AgNWs, forming a teardrop shape. The design of ITO/AgNWs/ITO layers is optically beneficial because the AgNWs generate plasmonic photons, due to the AgNWs. Electrical investigations were performed by Mott-Schottky and impedance spectroscopy to reveal the formation of a single space charge region at the interface between Si and AgNWs-embedding ITO layer. We propose a route to design the thermally stable AgNWs for photoelectric device applications with investigation of the optical and electrical aspects.

  1. Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy.

    PubMed

    Lee, Jung Ah; Lim, Young Rok; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

    2016-10-21

    To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes. PMID:27640642

  2. Flat-Band Potential of a Semiconductor: Using the Mott-Schottky Equation

    ERIC Educational Resources Information Center

    Gelderman, K.; L. Lee; Donne, S. W.

    2007-01-01

    An experiment is suitable for fourth-year undergraduate and graduate students in which the nature of the semiconductor materials through determination of flat-band potential using the Mott-Schottky equation is explored. The experiment confirms the soundness of the technique.

  3. Controlling the Schottky barrier at MoS2/metal contacts by inserting a BN monolayer

    NASA Astrophysics Data System (ADS)

    Farmanbar, Mojtaba; Brocks, Geert

    2015-04-01

    Making a metal contact to the two-dimensional semiconductor MoS2 without creating a Schottky barrier is a challenge. Using density functional calculations we show that, although the Schottky barrier for electrons obeys the Schottky-Mott rule for high work function (≳4.7 eV) metals, the Fermi level is pinned at 0.1-0.3 eV below the conduction band edge of MoS2 for low work function metals, due to the metal-MoS2 interaction. Inserting a boron nitride (BN) monolayer between the metal and the MoS2 disrupts this interaction, and restores the MoS2 electronic structure. Moreover, a BN layer decreases the metal work function of Co and Ni by ˜2 eV, and enables a lineup of the Fermi level with the MoS2 conduction band. Surface modification by adsorbing a single BN layer is a practical method to attain vanishing Schottky barrier heights.

  4. Quantifying the barrier lowering of ZnO Schottky nanodevices under UV light

    PubMed Central

    Lu, Ming-Yen; Lu, Ming-Pei; You, Shuen-Jium; Chen, Chieh-Wei; Wang, Ying-Jhe

    2015-01-01

    In this study we measured the degrees to which the Schottky barrier heights (SBHs) are lowered in ZnO nanowire (NW) devices under illumination with UV light. We measured the I–V characteristics of ZnO nanowire devices to confirm that ZnO is an n-type semiconductor and that the on/off ratio is approximately 104. From temperature-dependent I–V measurements we obtained a SBH of 0.661 eV for a ZnO NW Schottky device in the dark. The photosensitivity of Schottky devices under UV illumination at a power density of 3 μW/cm2 was 9186%. Variations in the SBH account for the superior characteristics of n-type Schottky devices under illumination with UV light. The SBH variations were due to the coupled mechanism of adsorption and desorption of O2 and the increase in the carrier density. Furthermore, through temperature-dependent I–V measurements, we determined the SBHs in the dark and under illumination with UV light at power densities of 0.5, 1, 2, and 3 μW/cm2 to be 0.661, 0.216, 0.178, 0.125, and 0.068 eV, respectively. These findings should be applicable in the design of highly sensitive nanoscale optoelectronic devices. PMID:26456370

  5. Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jung Ah; Rok Lim, Young; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

    2016-10-01

    To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes.

  6. Thermally Stable Silver Nanowires-Embedding Metal Oxide for Schottky Junction Solar Cells.

    PubMed

    Kim, Hong-Sik; Patel, Malkeshkumar; Park, Hyeong-Ho; Ray, Abhijit; Jeong, Chaehwan; Kim, Joondong

    2016-04-01

    Thermally stable silver nanowires (AgNWs)-embedding metal oxide was applied for Schottky junction solar cells without an intentional doping process in Si. A large scale (100 mm(2)) Schottky solar cell showed a power conversion efficiency of 6.1% under standard illumination, and 8.3% under diffused illumination conditions which is the highest efficiency for AgNWs-involved Schottky junction Si solar cells. Indium-tin-oxide (ITO)-capped AgNWs showed excellent thermal stability with no deformation at 500 °C. The top ITO layer grew in a cylindrical shape along the AgNWs, forming a teardrop shape. The design of ITO/AgNWs/ITO layers is optically beneficial because the AgNWs generate plasmonic photons, due to the AgNWs. Electrical investigations were performed by Mott-Schottky and impedance spectroscopy to reveal the formation of a single space charge region at the interface between Si and AgNWs-embedding ITO layer. We propose a route to design the thermally stable AgNWs for photoelectric device applications with investigation of the optical and electrical aspects. PMID:26971560

  7. Energetic initiators with narrow firing thresholds using Al/CuO Schottky junctions

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Zhu, Peng; Li, Jie; Hu, Bo; Shen, Ruiqi; Ye, Yinghua

    2016-07-01

    We designed and prepared Schottky-junction-based Al/CuO energetic initiators with narrow firing thresholds according to Schottky barrier theory. Using various characterization methods, we preliminarily investigated the electrical breakdown property, withstand strike current ability, and multiple-firing performance of the energetic initiators. The breakdown voltage of the Al/CuO Schottky junction was ~8 V; and electrical breakdown in the initiators occurred one by one rather than simultaneously. The withstand strike current ability of the initiator mainly depended on the heat capacity of its ceramic plug when the electrical stimulus is more than ~8 V, its breakdown voltage. The ceramic plug can absorb heat from the initiator chip, letting the initiator withstand a constant current of 0.5 A for 20 s. More importantly, the initiators might be able to withstand hard electromagnetic interference by coupling the multiple-firing performance with an out-of-line slider in the explosive train. This knowledge of the characteristics of Schottky-junction-based Al/CuO energetic initiators will help in preparing highly insensitive, efficient initiating explosive devices for weapon systems.

  8. Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy.

    PubMed

    Lee, Jung Ah; Lim, Young Rok; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

    2016-10-21

    To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes.

  9. Current-Temperature Scaling for a Schottky Interface with Nonparabolic Energy Dispersion

    NASA Astrophysics Data System (ADS)

    Ang, Y. S.; Ang, L. K.

    2016-09-01

    In this paper, we study the Schottky transport in a narrow-gap semiconductor and few-layer graphene in which the energy dispersions are highly nonparabolic. We propose that the contrasting current-temperature scaling relation of J ∝T2 in the conventional Schottky interface and J ∝T3 in graphene-based Schottky interface can be reconciled under Kane's k .p nonparabolic band model for narrow-gap semiconductors. Our model suggests a more general form of J ∝(T2+γ kBT3) , where the nonparabolicty parameter γ provides a smooth transition from T2 to T3 scaling. For few-layer graphene, we find that N -layer graphene with A B C stacking follows J ∝T2 /N +1 , while A B A stacking follows a universal form of J ∝T3 regardless of the number of layers. Intriguingly, the Richardson constant extracted from the Arrhenius plot using an incorrect scaling relation disagrees with the actual value by 2 orders of magnitude, suggesting that correct models must be used in order to extract important properties for many Schottky devices.

  10. Electrical properties of single CuO nanowires for device fabrication: Diodes and field effect transistors

    SciTech Connect

    Florica, Camelia; Costas, Andreea; Boni, Andra Georgia; Negrea, Raluca; Preda, Nicoleta E-mail: encu@infim.ro; Pintilie, Lucian; Enculescu, Ionut E-mail: encu@infim.ro; Ion, Lucian

    2015-06-01

    High aspect ratio CuO nanowires are synthesized by a simple and scalable method, thermal oxidation in air. The structural, morphological, optical, and electrical properties of the semiconducting nanowires were studied. Au-Ti/CuO nanowire and Pt/CuO nanowire electrical contacts were investigated. A dominant Schottky mechanism was evidenced in the Au-Ti/CuO nanowire junction and an ohmic behavior was observed for the Pt/CuO nanowire junction. The Pt/CuO nanowire/Pt structure allows the measurements of the intrinsic transport properties of the single CuO nanowires. It was found that an activation mechanism describes the behavior at higher temperatures, while a nearest neighbor hopping transport mechanism is characteristic at low temperatures. This was also confirmed by four-probe resistivity measurements on the single CuO nanowires. By changing the metal/semiconductor interface, devices such as Schottky diodes and field effect transistors based on single CuO p-type nanowire semiconductor channel are obtained. These devices are suitable for being used in various electronic circuits where their size related properties can be exploited.

  11. AlGaN/GaN MOSHFET power switching transistor with embedded fast recovery diode

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Yeon; Park, Bong-Ryeol; Kim, Hyungtak; Kim, Jaehan; Cha, Ho-Young

    2014-11-01

    In this study, a novel AlGaN/GaN power-switching device is proposed for use in high-efficiency DC-DC converters. The proposed structure is composed of a normally-off AlGaN/GaN metal-oxide-semiconductor heterojunction field-effect transistor (MOSHFET) and an embedded freewheeling Schottky barrier diode (SBD). The effects of the embedded freewheeling SBD on conversion efficiency were investigated based on circuit simulation of DCDC synchronous buck converters. The SBD embedment not only reduces the chip size and cost, but also improves the power conversion efficiency at high operation frequencies, due to the reduced off-state power loss. [Figure not available: see fulltext.

  12. On the explanation of the barrier heights of InP Schottky contacts by metal-induced gap states

    NASA Astrophysics Data System (ADS)

    Mönch, Winfried

    2008-10-01

    The barrier heights of metal-semiconductor or Schottky contacts are explained by the continuum of metal-induced gap states (MIGSs). A verification of the theoretically predicted values requires experimental barrier heights of Schottky contacts, which are not only intimate, abrupt, and free of impurities but also laterally homogeneous. Such data may be obtained from current-voltage and capacitance-voltage characteristics. Results of corresponding studies with Ag, Au, Cr, Pd, and Ti contacts on InP were recently published. The barrier heights of the respective laterally homogeneous Schottky contacts evaluated from those experimental data quantitatively confirm the predictions of the MIGS theory.

  13. A 4-W 56-dB gain microstrip amplifier at 15 GHz utilizing GaAs FET's and IMPATT diodes

    NASA Technical Reports Server (NTRS)

    Sokolov, V.; Namordi, M. R.; Doerbeck, F. H.

    1979-01-01

    Performance results and design considerations are presented for an all solid-state Ku-band power amplifier which is feasible for use in PM communication systems for airborne or spacecraft transmitter applications. A six-stage GaAs FET preamplifier and a driver and balanced power amplifier utilizing GaAs IMPATT diodes operating in the injection locked oscillator mode are discussed. For high power and efficiency Schottky-Read IMPATT's with low-high-low doping profiles are employed. For improved reliability the IMPATT's incorporate a TiW barrier metallization to retard degradation of the IMPATT's. Results of accelerated life testing of the IMPATT devices are also presented.

  14. Emitron: microwave diode

    DOEpatents

    Craig, G.D.; Pettibone, J.S.; Drobot, A.T.

    1982-05-06

    The invention comprises a new class of device, driven by electron or other charged particle flow, for producing coherent microwaves by utilizing the interaction of electromagnetic waves with electron flow in diodes not requiring an external magnetic field. Anode and cathode surfaces are electrically charged with respect to one another by electron flow, for example caused by a Marx bank voltage source or by other charged particle flow, for example by a high energy charged particle beam. This produces an electric field which stimulates an emitted electron beam to flow in the anode-cathode region. The emitted electrons are accelerated by the electric field and coherent microwaves are produced by the three dimensional spatial and temporal interaction of the accelerated electrons with geometrically allowed microwave modes which results in the bunching of the electrons and the pumping of at least one dominant microwave mode.

  15. Nanofluidic osmotic diodes

    NASA Astrophysics Data System (ADS)

    Bocquet, Lyderic; Picallo, Clara; Gravelle, Simon; Joly, Laurent; Charlaix, Elisabeth

    2013-11-01

    Osmosis describes the flow of water across semipermeable membranes powered by the chemical free energy extracted from salinity gradients. While osmosis can be expressed in simple terms via the van't Hoff ideal gas formula for the osmotic pressure, it is a complex phenomenon taking its roots in the subtle interactions occurring at the scale of the membrane nanopores. Here we use new opportunities offered by nanofluidic systems to create an osmotic diode exhibiting asymmetric water flow under reversal of osmotic driving. We show that a surface charge asymmetry built on a nanochannel surface leads to non-linear couplings between water flow and the ion dynamics, which are capable of water flow rectification. This phenomenon opens new opportunities for water purification and complex flow control in nanochannels.

  16. White light emitting diodes

    NASA Astrophysics Data System (ADS)

    Baur, J.; Schlotter, P.; Schneider, J.

    Using blue-emitting GaN LEDs on SiC substrate chips as primary light sources, we have fabricated green, yellow, red and white light emitting diodes (LUCOLEDs). The generation of mixed colors, as turquoise and magenta, is also demonstrated. The underlying physical principle is that of luminescence downconversion (Stokes shift), as typical for organic dye molecules and many inorganic phosphors. For white light generation via the LUCOLED principle, the phosphor Y3Al5O12:Ce3+(4f1) is ideally suited. The optical characteristics of Ce3+(4f1) in Y3Al5O12(YAG) are discussed in detail. Possibilities to "tune" the white color by various substitutions in the garnet lattice are shortly outlined.

  17. Laterally injected light-emitting diode and laser diode

    SciTech Connect

    Miller, Mary A.; Crawford, Mary H.; Allerman, Andrew A.

    2015-06-16

    A p-type superlattice is used to laterally inject holes into an III-nitride multiple quantum well active layer, enabling efficient light extraction from the active area. Laterally-injected light-emitting diodes and laser diodes can enable brighter, more efficient devices that impact a wide range of wavelengths and applications. For UV wavelengths, applications include fluorescence-based biological sensing, epoxy curing, and water purification. For visible devices, applications include solid state lighting and projection systems.

  18. Enhanced vbasis laser diode package

    DOEpatents

    Deri, Robert J.; Chen, Diana; Bayramian, Andy; Freitas, Barry; Kotovsky, Jack

    2014-08-19

    A substrate having an upper surface and a lower surface is provided. The substrate includes a plurality of v-grooves formed in the upper surface. Each v-groove includes a first side and a second side perpendicular to the first side. A laser diode bar assembly is disposed within each of the v-grooves and attached to the first side. The laser diode bar assembly includes a first adhesion layer disposed on the first side of the v-groove, a metal plate attached to the first adhesion layer, a second adhesion layer disposed over the metal plate, and a laser diode bar attached to the second adhesion layer. The laser diode bar has a coefficient of thermal expansion (CTE) substantially similar to that of the metal plate.

  19. Thermometric Property of a Diode.

    ERIC Educational Resources Information Center

    Inman, Fred W.; Woodruff, Dan

    1995-01-01

    Presents a simple way to implement the thermometric property of a semiconductor diode to produce a thermometer with a nearly linear dependence upon temperature over a wide range of temperatures. (JRH)

  20. Diode-pumped dye laser

    NASA Astrophysics Data System (ADS)

    Burdukova, O. A.; Gorbunkov, M. V.; Petukhov, V. A.; Semenov, M. A.

    2016-10-01

    This letter reports diode pumping for dye lasers. We offer a pulsed dye laser with an astigmatism-compensated three-mirror cavity and side pumping by blue laser diodes with 200 ns pulse duration. Eight dyes were tested. Four dyes provided a slope efficiency of more than 10% and the highest slope efficiency (18%) was obtained for laser dye Coumarin 540A in benzyl alcohol.