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Voltage Measurements (voltage + measurement)
Selected AbstractsInfluence of a Measuring System to a Transient Voltage on a Vertical ConductorIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 2 2010Peerawut Yutthagowith Student Member Abstract This paper studies the effect of a horizontal reference voltage wire, a current lead wire, and the impedance of a voltage probe when measuring a transient voltage on a vertical conductor. A hybrid frequency-time domain (HFTD) method and a finite-different time domain (FDTD) method with the help of VSTL are applied to investigate the effect of the horizontal reference voltage wire, the current lead wire, and the impedance of the voltage probe on measurement at the top of the vertical conductor. The obtained results show that the horizontal reference voltage wire perpendicular to the vertical conductor causes a minor effect, but the input capacitance of the voltage probe affects significantly the voltage measurement. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Scanning capacitance microscopy as a tool for the assessment of unintentional doping in GaNPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009Rachel A. Oliver Abstract Scanning capacitance microscopy (SCM) is a technique based on atomic force microscopy which provides information about the concentration and distribution of charge carriers in a semiconducting sample. As an imaging technique it provides an advantage over more conventional approaches such as secondary ion mass spectrometry and depth-profiling Hall voltage measurement since it provides a two-dimensional dataset rather than a one dimensional line profile. Here, we demonstrate the utility of SCM for GaN-based materials by assessing the unintentionally doped layer at the GaN/sapphire interface in a series of samples in which the growth conditions initially favoured the formation of three-dimensional islands, which later coalesced to form a two-dimensional film. Using SCM we observe that the width of the resulting conductive layer at the GaN/sapphire interface depends on the time taken to achieve coalescence but that the carrier density does not. We also assess and attempt to explain the roughness of the top surface of the conductive interface layer, which can only be addressed using an imaging technique. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] International comparison test in Asia-Pacific region for impulse voltage measurementsELECTRICAL ENGINEERING IN JAPAN, Issue 3 2009Takayuki Wakimoto Abstract The national standard class divider for the lightning impulse voltage measurements in Japan was developed in 1998. After three years, the standard impulse voltage calibrator has also been manufactured. These standard equipment are used as an industrial standard, and the performance had been evaluated annually supported by the Ministry of Economy, Trade and Industry (METI). The standard impulse measuring system including the standard divider participated in the worldwide comparison test and its good performance was confirmed in 1999. Another international comparison test was carried out among three countries in the Asia-Pacific region in 2004 again and the standard measuring system participated in the test. In this paper, the details and the results of the international comparison tests in 2004 are described. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(3): 46, 54, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20677 [source] The dynamic voltage/current characteristics of vacuum arcs after breakdown at currents in the lower kHz-rangeEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2002N. Hardt A test set-up is presented which is able to measure the arc voltage of vacuum interrupters after breakdown with currents in the lower kHz-range. Arc voltage measurements from this set-up are presented. The obtained dynamic voltage/current characteristics are discussed and compared to the known voltage current characteristic of a power frequency arc in vacuum. A simple vacuum arc model is presented describing the voltage current characteristic. The model is applied to assess the energy dissipation in the arc. [source] Nanostructure and Optoelectronic Characterization of Small Molecule Bulk Heterojunction Solar Cells by Photoconductive Atomic Force MicroscopyADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Xuan-Dung Dang Abstract Photoconductive atomic force microscopy is employed to study the nanoscale morphology and optoelectronic properties of bulk heterojunction solar cells based on small molecules containing a benzofuran substituted diketopyrrolopyrrole (DPP) core (3,6-bis(5-(benzofuran-2-yl)thiophen-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione, DPP(TBFu)2, and [6,6],phenyl-C71 -butyric acid methyl ester (PC71BM), which were recently reported to have power conversion efficiencies of 4.4%. Electron and hole collection networks are visualized for blends with different donor:acceptor ratios. Formation of nanostructures in the blends leads to a higher interfacial area for charge dissociation, while maintaining bicontinuous collection networks; conditions that lead to the high efficiency observed in the devices. An excellent agreement between nanoscale and bulk open-circuit voltage measurements is achieved by surface modification of the indium tin oxide (ITO) substrate by using aminopropyltrimethoxysilane. The local open-circuit voltage is linearly dependent on the cathode work function. These results demonstrate that photoconductive atomic force microscopy coupled with surface modification of ITO substrate can be used to study nanoscale optoelectronic phenomena of organic solar cells. [source] Nanostructure and Optoelectronic Characterization of Small Molecule Bulk Heterojunction Solar Cells by Photoconductive Atomic Force MicroscopyADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Xuan-Dung Dang Abstract Photoconductive atomic force microscopy is employed to study the nanoscale morphology and optoelectronic properties of bulk heterojunction solar cells based on small molecules containing a benzofuran substituted diketopyrrolopyrrole (DPP) core (3,6-bis(5-(benzofuran-2-yl)thiophen-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione, DPP(TBFu)2, and [6,6],phenyl-C71 -butyric acid methyl ester (PC71BM), which were recently reported to have power conversion efficiencies of 4.4%. Electron and hole collection networks are visualized for blends with different donor:acceptor ratios. Formation of nanostructures in the blends leads to a higher interfacial area for charge dissociation, while maintaining bicontinuous collection networks; conditions that lead to the high efficiency observed in the devices. An excellent agreement between nanoscale and bulk open-circuit voltage measurements is achieved by surface modification of the indium tin oxide (ITO) substrate by using aminopropyltrimethoxysilane. The local open-circuit voltage is linearly dependent on the cathode work function. These results demonstrate that photoconductive atomic force microscopy coupled with surface modification of ITO substrate can be used to study nanoscale optoelectronic phenomena of organic solar cells. [source] The Role of Transition Metal Oxides in Charge-Generation Layers for Stacked Organic Light-Emitting DiodesADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Sami Hamwi Abstract The mechanism of charge generation in transition metal oxide (TMO)-based charge-generation layers (CGL) used in stacked organic light-emitting diodes (OLEDs) is reported upon. An interconnecting unit between two vertically stacked OLEDs, consisting of an abrupt heterointerface between a Cs2CO3 -doped 4,7-diphenyl-1,10-phenanthroline layer and a WO3 film is investigated. Minimum thicknesses are determined for these layers to allow for simultaneous operation of both sub-OLEDs in the stacked device. Luminance,current density,voltage measurements, angular dependent spectral emission characteristics, and optical device simulations lead to minimum thicknesses of the n-type doped layer and the TMO layer of 5 and 2.5,nm, respectively. Using data on interface energetic determined by ultraviolet photoelectron and inverse photoemission spectroscopy, it is shown that the actual charge generation occurs between the WO3 layer and its neighboring hole-transport material, 4,4',4"-tris(N -carbazolyl)-triphenyl amine. The role of the adjacent n-type doped electron transport layer is only to facilitate electron injection from the TMO into the adjacent sub-OLED. [source] Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-DopantADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Kyoung Soo Yook Abstract Cesium azide (CsN3) is employed as a novel n-dopant because of its air stability and low deposition temperature. CsN3 is easily co-deposited with the electron transporting materials in an organic molecular beam deposition chamber so that it works well as an n-dopant in the electron transport layer because its evaporation temperature is similar to that of common organic materials. The driving voltage of the p-i-n device with the CsN3 -doped n-type layer and a MoO3 -doped p-type layer is greatly reduced, and this device exhibits a very high power efficiency (57,lm W,1). Additionally, an n-doping mechanism study reveals that CsN3 was decomposed into Cs and N2 during the evaporation. The charge injection mechanism was investigated using transient electroluminescence and capacitance,voltage measurements. A very highly efficient tandem organic light-emitting diodes (OLED; 84,cd A,1) is also created using an n,p junction that is composed of the CsN3 -doped n-type organic layer/MoO3 p-type inorganic layer as the interconnecting unit. This work demonstrates that an air-stable and low-temperature-evaporable inorganic n-dopant can very effectively enhance the device performance in p-i-n and tandem OLEDs, as well as simplify the material handling for the vacuum deposition process. [source] Perfluorinated Subphthalocyanine as a New Acceptor Material in a Small-Molecule Bilayer Organic Solar CellADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Hans Gommans Abstract The complex refractive index of fluorinated subphthalocyanines (SubPcs) deposited by vacuum sublimation is determined by spectral ellipsometry. Their performance as acceptor material is characterized in a range of donor/acceptor heterojunctions in organic photovoltaic cells (OPVCs) by current,voltage measurements under 1,sun AM 1.5D simulated solar illumination and spectral response. Both electron and hole transfer between donor and acceptor materials is demonstrated. Power conversion efficiencies of 0.96% are found with an open-circuit bias of 940,mV. Hence, it is shown that fluorinated SubPcs can be considered as an acceptor material in OPVCs with an absorption in the visible comparable to that of well-known metallophthalocyanines. [source] Size Effect on Properties of Varistors Made From Zinc Oxide Nanoparticles Through Low Temperature Spark Plasma SinteringADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Léna Saint Macary Abstract Conditions for the elaboration of nanostructured varistors by spark plasma sintering (SPS) are investigated, using 8-nm zinc oxide nanoparticles synthesized following an organometallic approach. A binary system constituted of zinc oxide and bismuth oxide nanoparticles is used for this purpose. It is synthesized at room temperature in an organic solution through the hydrolysis of dicyclohexylzinc and bismuth acetate precursors. Sintering of this material is performed by SPS at various temperatures and dwell times. The determination of the microstructure and the chemical composition of the as-prepared ceramics are based on scanning electron microscopy and X-ray diffraction analysis. The nonlinear electrical characteristics are evidenced by current,voltage measurements. The breakdown voltage of these nanostructured varistors strongly depends on grain sizes. The results show that nanostructured varistors are obtained by SPS at sintering temperatures ranging from 550 to 600,°C. [source] Self-Assembly of DNA-Templated Polypyrrole Nanowires: Spontaneous Formation of Conductive Nanoropes,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2008Stela Pruneanu Abstract Polypyrrole nanowires formed by polymerization of pyrrole on a DNA template self-assemble into rope-like structures. These ,nanoropes' may be quite smooth (diameters 5,30,nm) or may show frayed ends where individual strands are visible. A combination of electric force microscopy, conductive atomic force microscopy and two-terminal current,voltage measurements show that they are conductive. Nanoropes adhere more weakly to hydrophobic surfaces prepared by silanization of SiO2 than to the clean oxide; this effect can be used to aid the combing of the nanoropes across microelectrode devices for electrical characterization. [source] Latest research activity on the standard of high-voltage impulse in JapanIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 5 2007Takayuki Wakimoto Member Abstract A national-standard-class impulse voltage measuring system in Japan was developed in the consignment research of the Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO) from 1998 to 2006. The standard measuring system for the impulse voltage measurements is to be managed by the Japan High-voltage Impulse testing Laboratories Liaison (JHILL) established under the Japan Electric Machine Industry Association (JEMA). In this paper, the composition of this standard measuring system, its performances and international compatibility, the domestic traceability system and related latest activities are described. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Photogalvanic effect in aqueous Methylene blue nickel mesh systems: Conversion of light into electricityINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2001Ilker S. Bayer Abstract The photogalvanic effect in electrochemical cells, employing aqueous Methylene blue and Fe(II)/Fe(III) couple electrolyte and nickel-mesh electrodes, were experimentally investigated. Five different standard H-cell configurations were set-up by modifying the electrolyte. Long-term open-circuit voltage measurements were conducted in order to test the stability of the cells. Light on,off reproducibility experiments were also carried out during lengthy cell operations. By comparing experimental quantum yield with theoretical predictions, it was found that the cells operate on differential electrode kinetics. Oxidation of the illuminated electrode was detected. This affected the current,voltage characteristics of the cells after a sufficiently long cell operation. Schottky junction treatment was used to model the electrolyte,electrode junction. After calculating the ratio between the majority carrier (electron) current density and minority carrier (hole) current density, we concluded that the oxidation of the electrodes contributes positively to the cell performance since the electrode,electrolyte interface shows unipolar Schottky diode characteristics. Copyright © 2001 John Wiley & Sons, Ltd. [source] Sliding mode control of DC-to-DC power converters using integral reconstructorsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 13 2002H. Sira-Ramirez Abstract A sliding mode feedback controller, based on integral reconstructors is developed for the regulation of the ,boost' DC-to-DC power converter circuit conduction in continuous conduction mode. The feedback control scheme uses only output capacitor voltage measurements, as well as knowledge of the available input signal, represented by the switch positions. The robustness of the feedback scheme is tested with abusively large, unmodelled, sudden load resistance variations. Copyright © 2002 John Wiley & Sons, Ltd. [source] Microstructural Morphology and Electrical Properties of Copper- and Niobium-Doped Tin Dioxide Polycrystalline VaristorsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2006Chun-Ming Wang The influence of a Nb2O5 additive on the densification, microstructural morphology, and nonlinear electrical properties of the CuO-doped SnO2 -based varistors was investigated. It was found that copper oxide significantly improves the densification of the SnO2 ceramics. The effects of Nb2O5 on tin dioxide varistors were analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and capacitance,voltage measurements, as well as impedance spectroscopy. Copper oxide segregates at the grain boundaries and precipitates at triple points, and niobium makes the tin dioxide grain semi-conductive. The copper oxide intergranular insulating layer separates two semi-conductive tin dioxide grains and forms the barriers. The reason for the nonlinearity of SnO2 -based ceramics was explained. [source] 3D EIT for breast cancer imaging: System, measurements, and reconstructionMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008Gang Ye Abstract Electrical impedance tomography (EIT) is a developing imaging modality for early detection of breast cancer. In an EIT system, a low-frequency current is applied sequentially between different electrode pairs while voltage measurements are made at other electrodes to arrive at the electrical impedance values. The set of impedance measurement data is then computed to produce a 3D electrical conductivity map of the volume to be imaged. In this work, the design, measurements, and inversion of a full 3D EIT system are discussed. Experimentally determined EIT images of phantom objects are presented. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3261,3271, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23932 [source] Electrical Characteristics of an Electronic Control Device Under a Physiologic Load: A Brief ReportPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2010DONALD M. DAWES M.D. Background:,Law enforcement officers use electronic control devices (ECDs), such as the TASER X26 (TASER International, Inc., Scottsdale, AZ, USA), to control resisting subjects. Some of the debate on the safety of the devices has centered on the electrical characteristics of the devices. The electrical characteristics published by TASER International have historically based on discharges into a 400 , resistor. There are no studies that the authors are aware of that report the electrical characteristics under a physiologic load. In this study, we make an initial attempt to determine the electrical characteristics of the TASER X26 during a 5-second exposure in human volunteers. Methods:,Subjects received an exposure to the dry, bare chest (top probe), and abdomen (bottom probe) with a standard TASER X26 in the probe deployment mode for 5 seconds. There were 10,11 pulse captures during the 5 seconds. Resistance was calculated using the sum of the absolute values of the instantaneous voltage measurements divided by the sum of the absolute values of the instantaneous current measurements (Ohm's Law). Results:,For the eight subjects, the mean spread between top and bottom probes was 12.1 inches (30.7 cm). The mean resistance was 602.3 ,, with a range of 470.5,691.4 ,. The resistance decreased slightly over the 5-second discharge with a mean decrease of 8.0%. The mean rectified charge per pulse was 123.0 ,C. The mean main phase charge per pulse was 110.5 ,C. The mean pulse width was 126.9 ,s. The mean voltage per pulse was 580.1 V. The mean current per pulse was 0.97 A. The average peak main phase voltage was 1899.2 V and the average peak main phase current was 3.10 A. Conclusions:,The mean tissue resistance was 602.3 , in this study. There was a decrease in resistance of 8% over the 5-second exposure. This physiologic load is different than the 400 , laboratory load used historically by the manufacturer. We recommend future characterization of these devices use a physiologic load for reporting electrical characteristics. We also recommend that all the electrical characteristics be reported. (PACE 2010; 33:330,336) [source] Microstructured horizontal alumina pore arrays as growth templates for large area few and single nanowire devicesPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 2 2008Ying Xiang Abstract We demonstrate the fabrication of horizontally aligned and well-defined nanopore structures by anodic oxidation of aluminum thin films and micro stripes on a Si substrate. We are able to control both, the pore diameters and interpore distances from 10 nm to 130 nm and from 30 nm to 275 nm, respectively. The anisotropy of the system induces some deviations in the pore configuration from the typical honeycomb structure. By decreasing the dimensions of the Al structures, the final pore diameter and interpore distance remains constant, enabling the transition from multiple to a few nanowire porous structures. Finally, we successfully filled the nanopores by pulsed electroplating, as demonstrated both by Scanning Electron Microscopy and by current,voltage measurements. Having full control over the size, the density, the position and the orientation of the porous structure, our approach is promising for many exciting applications, including nanoelectronics and sensing. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dependence on substrate temperature of the conformation and structure of a poly[3-(4-octyloxyphenyl)thiophene] (POOPT) thin film obtained by matrix assisted pulsed laser evaporation (MAPLE)PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2009Valeria Califano Abstract In this paper, the substrate temperature influence on the structural and main opto-electronic properties of poly[3-(4-octyloxyphenyl)thiophene] (POOPT) films, deposited by matrix assisted pulsed laser evaporation (MAPLE), was analyzed. Fourier transform infrared analysis of films was performed to verify that laser irradiation has not induced polymer modifications or decomposition, confirming the reliability and high control of the MAPLE deposition technique. UV,Visible spectroscopy allowed gaining insights about films conformation and packing, while conductivity values have been measured by basic current,voltage measurements. In agreement with the experimental observations reported for other growth techniques, our results highlight the substrate temperature effect in promoting the film structural organization and improving their charge transport capability. At substrate temperature of 453,K, films deposited by MAPLE show a higher conjugation length in comparison with spin-coated films. The substrate temperature increase also favors side-chains commutation to different steric configurations. [source] Enhancing nanocrystalline diamond surface conductivity by deposition temperature and chemical post-processingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2009H. Kozak Abstract The surface conductivity of nanocrystalline diamond (NCD) films as a function of deposition temperature and chemical post-processing was characterized by current,voltage measurements using co-planar Au electrodes. Raman spectroscopy was applied to investigate the bulk quality of NCD films and characterize the relative amount of sp3 diamond phase in the volume. The surface material properties and morphology were studied using atomic force microscopy (AFM) in tapping and phase detection regimes. The results indicate that the chemical post-processing of as-grown NCD films by boiling in acid and re-hydrogenation leads to a significant increase in the surface conductivity by three orders of magnitude, in the order of 10,7 (,/,),1. As a function of the deposition temperature (with re-hydrogenation temperature kept constant) the surface conductivity of nanocrystalline diamond films shows optimum around 600 °C. This enhancement is attributed to the lowest amount of sp2 phase on the surface. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Compensation in boron-doped CVD diamondPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2008Markus Gabrysch Abstract Hall-effect measurements on single crystal boron-doped CVD diamond in the temperature interval 80,450 K are presented together with SIMS measurements of the dopant concentration. Capacitance,voltage measurements on rectifying Schottky junctions manufactured on the boron-doped structures are also presented in this context. Evaluation of the compensating donor (ND) and acceptor concentrations (NA) show that in certain samples very low compensation ratios (ND/NA below 10,4) have been achieved. The influence of compensating donors on majority carrier transport and the significance for diamond device performance are briefly discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Mg-doped InN and InGaN , Photoluminescence, capacitance,voltage and thermopower measurementsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2008J. W. Ager III Abstract The bandgap range of InGaN extends from the near-IR (InN, 0.65 eV) to the ultraviolet. To exploit this wide tuning range in light generation and conversion applications, pn junctions are required. The large electron affinity of InN (5.8 eV) leads to preferential formation of native donor defects, resulting in excess electron concentration in the bulk and at surfaces and interfaces. This creates difficulties for p-type doping and/or measuring of the bulk p-type activity. Capacitance,voltage measurements, which deplete the n-type surface inversion layer, have been used to show that Mg is an active acceptor in InN and Inx Ga1,xN for 0.2 < x < 1.0, i.e. over the entire composition range. Mg acceptors can be compensated by irradiation-induced native donors. Thermopower measurements were used to provide definitive evidence that Mg-doped InN has mobile holes between 200 K and 300 K. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical, electrical and structural characterization of CuInSe2 thin filmsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2005C. Calderón Abstract Structural, optical and electrical properties of polycrystalline p-type CuInSe2 (CIS) thin films, grown by a process including a chemical reaction between Cu and InxSey thin films deposited sequentially by evaporation, followed by annealing in a Se environment, were studied through XRD (X-ray diffraction), transmittance and Hall voltage measurements. The conditions to grow CIS thin films in the , phase of the chalcopyrite structure were found through a parameter study. CIS films with these characteristics are usually used for the fabrication of high efficiency solar cells. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] M -plane InGaN/GaN light emitting diodes fabricated by MOCVD regrowth on c -plane patterned templatesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008Christopher A. Schaake Abstract In this work we demonstrate a light emitting diode (LED) with m -plane quantum wells fabricated on a (000) template. N-polar, n-type GaN was grown by MOCVD on vicinal sapphire substrates. Stripes, measuring 500 nm wide, 500 nm tall and spaced 2 ,m apart, were etched parallel to the ,110, direction leading to sidewalls that are approximately {100}. Sputtered AlN was used as a regrowth mask on the c -plane surfaces. An active region consisting of 5 InGaN quantum wells and GaN barriers followed by p-type was grown. The regrowth occurred mostly on the exposed m -plane sidewalls, leading to lateral growth in the ,100, direction. The LED was processed using conventional methods. A thick metal contact was used to connect the p-regions together. Current vs. voltage measurements showed good rectifying behavior with a turn on of about 6 volts. On-wafer electroluminescence measurements revealed a peak wavelength of 422 nm. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fabrication of AlGaN/GaN MIS-HFET using an Al2O3 high k dielectricPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003Ki-Yeol Park Abstract We report on a metal,insulator,semiconductor AlGaN/GaN heterostructure field-effect transistor (MIS-HFET) using Al2O3 simultaneously for channel passivation layer and as a gate insulator which was deposited by plasma enhanced atomic layer deposition(PE-ALD). Capacitance,voltage measurements show successful surface passivation by the Al2O3 dielectric layer. For a gate length 1.2 ,m with 15 ,m source-to-drain spacing the maximum drain current was 1.22 A/mm, the maximum transconductance was 166 mS/mm and the gate leakage current was 4 nA/mm at Vgs = ,20 V which is at least three orders of magnitude lower than that of conventional AlGaN/GaN HFETs. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Hot-electron transport in III,V nitride based two-dimensional gasesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003S. A. Vitusevich Abstract We report on experimental and theoretical studies of low and high field transport in AlGaN/GaN two-dimensional electron gas (2DEG). Magnetotransport of 2DEG created as a result of polarization effects at the heterointerface has been studied. The velocity-electric field characteristics extracted from pulsed current,voltage measurements in AlGaN/GaN heterostructures are in good agreement with transport calculations up to fields as high as 100 kV/cm. [source] A GLOBAL EXPONENTIAL OUTPUT-FEEDBACK CONTROLLER FOR INDUCTION MOTORSASIAN JOURNAL OF CONTROL, Issue 4 2000M. Feemster ABSTRACT In this paper, we design an output-feedback, rotor position/rotor flux controller for the full-order, nonlinear dynamic model of an induction motor. The singularity free controller does not require measurement of rotor flux or rotor velocity and yields global exponential rotor position and rotor flux tracking. The proposed controller is termed output-feedback due to the inexpensive/simplistic manner in which stator current measurements can be obtained (e.g., the most primitive method of measuring current can be achieved through simple voltage measurements across known resistive elements). Experimental results are included to verify the effectiveness of the proposed controller. [source] | ||||||||||||||||