bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regelung eines elastischen Roboters mit Zwangskräften am Greifer
Authors: Mitterhuber Ralph , Bremer Hartmut 
Published: June 2010

AbstractBei einem Knickarmroboter mit 6 Gelenken und 2 schlanken, elastisch verformbaren Armen, dessen Greifer im Kontakt mit einer bewegten Zwangsfläche steht, werden die Greiferposition und ‐orientierung geregelt.
Arbitrary Pole Assignability by Static Output Feedback under Structural Contraints
Authors: Reinschke K. J. 
Published: June 2010

AbstractUsing a few elementary concepts from algebraic geometry such as multidimensional projective space, quadric hypersurface and its tangential variety, the known problem of arbitrary pole placement is transformed into a system of well‐structured (partly non‐linear) algebraic equations. Necessary and sufficient solvability conditions are derived. Finally, it is outlined how to calculate admissible output feedback matrices which ensure the desired pole assignment.
Enclosure of Algebraic Functions and Bounded–Input Bounded–Output Stability of Linear Time–Discrete Scalar Bivariate Dynamical Systems
Authors: Boese F. G. 
Published: June 2010

AbstractAn enclosure set for the general polynomial in two complex variables is expounded. Based thereupon, BIBO stability criteria for time–discrete, time–constant bivariate linear dynamical systems are set forth.
Electrical and luminescence properties of Mg‐doped p‐type GaPN grown by molecular beam epitaxy
Authors: Mitsuyoshi S. , Umeno K. , Furukawa Y. , Urakami N. , Wakahara A. , Yonezu H. 
Published: June 2010

AbstractWe have demonstrated the acceptor concentration control for p‐type GaPN grown by molecular beam epitaxy (MBE) using Mg as the acceptor element. The hole concentration increases up to 2×1019 cm‐3 at 300 K and does not remarkably vary after thermal treatment and thus Mg is successfully doped into GaPN. Subsequently, we have investigated the electrical and luminescence properties of Mg‐doped p‐type GaPN grown by MBE. The activation energy is estimated to be about 37 meV, indicating Mg is a shallow acceptor element for p‐type GaPN grown by MBE. When the hole concentration is larger than ∼1018 cm‐3, the photoluminescence (PL) intensity decreases with increasing the hole concentration. By time‐resolved PL (TRPL) measurement, this PL quenching is caused by the non‐radiative centres due to Mg doping when the hole concentration is larger than ∼1018 cm‐3. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of rugged 2 GHz power bars delivering more than 100 W and 60% power added efficiency
Authors: Waltereit P. , Bronner W. , Quay R. , Dammann M. , Müller S. , Köhler K. , Mikulla M. , Ambacher O. , Harm L. , Lorenzini M. , Rödle T. , Riepe K. , Bellmann K. , Buchheim C. , Goldhahn R. 
Published: June 2010

AbstractIn this work we systematically study the structural, optical and electrical properties of AlGaN/GaN heterostructures grown by MOCVD 3‐inch on SiC substrates The finally developed HEMTs demonstrate excellent high‐voltage stability, high power performance and large power added efficiencies. For a drain bias of 100 V an output‐power‐density around 26 W/mm with 25 dB linear gain is obtained. On 36 mm gate width devices an output power beyond 100 W is achieved with a power added efficiency above 60% and a linear gain around 17 dB. Ruggedness on these large devices is proven by successfully passing harsh intentional device mismatch tests during operation at 50 V. Reliability is tested at a drain bias of 50 V. Under DC conditions a drain‐current degradation below 20% after 20 years is extrapolated. Under RF stress the observed change in output power is well below 0.1 dB after a test duration of more than 500 h. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Acoustic phonon effects on telecommunication‐band quantum dot exciton Rabi oscillation
Authors: Miyazawa Toshiyuki , Nakaoka Toshihiro , Kodera Tetsuo , Takagi Hiroyuki , Kumagai Naoto , Watanabe Katsuyuki , Arakawa Yasuhiko 
Published: June 2010

AbstractWe investigated the effect of acoustic phonon mediated damping on a telecommunication‐band excitonic Rabi oscillation in a single quantum dot (QD). The InAs/GaAs QDs were capped with an InGaAs strain‐reducing layer (SRL) to shift the exciton energy to the O‐band (the lowest dispersion band; 1.26‐1.36 mm). They were also embedded in an n ‐i ‐Schottky diode in order to prove the excitonic state in a single photo‐excited QD by photocurrent spectroscopy. The observed exciton linewidth increased linearly at the low temperature due to the exciton‐acoustic phonon coupling, and increased drastically above 40 K due to the nonlinear increment of the exciton‐LO phonon coupling. We successfully observed excitonic Rabi oscillation up to 40 K even though the acoustic phonon‐mediated damping increased with temperature. This result suggests that the telecommunication‐band QDs are useful in constructing the exciton‐based qubits under the influence of the coupling between excitons and acoustic‐phonons. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of growth temperature of AlN interlayers on the properties of GaN epilayers grown on c‐plane sapphire by metal organic chemical vapor deposition
Authors: Xue J. S. , Hao Y. , Zhang J. C. , Yang L. A. 
Published: June 2010

AbstractThe effect of growth temperature of AlN interlayers on the properties of GaN epilayers grown on c‐plane sapphire by metal organic chemical vapor deposition has been investigated by high resolution X‐ray diffraction (HRXRD) and Raman spectroscopy. It is concluded that the crystalline quality of GaN epilayers is improved significantly by using the high temperature AlN (HT‐AlN) interlayer in GaN buffers. The density of threading dislocation is reduced especially for edge type dislocations. Higher compressive stress exists in GaN epilayers with HT‐AlN interlayer than with low temperature AlN (LT‐AlN) interlayer, which is related to the reduction of strain relaxation caused by the formation of misfit dislocation. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hg(1‐x)CdxTe from short to long wave infrared on Si substrates grown by MBE
Authors: Vilela M. F. , Olsson K. R. , Reddy M. , Peterson J. M. , Franklin J. J. , Vang T. , Lofgreen D. D. , Johnson S. M. 
Published: June 2010

AbstractIn this paper, we show the power of using molecular beam epitaxy (MBE) for the growth of the mercury cadmium telluride (HgCdTe) system. Abrupt composition profiles, changes in doping levels, or switching doping types are easily performed. It is shown that high quality material is achieved with Hg(1‐x)CdxTe grown by MBE from a cadmium mole fraction of x =0.15 to x =0.72. Doping elements incorporation as low as 1015 cm‐3 for both n‐type and p‐type material as well as high incorporation levels >1018cm‐3 for both carrier types were achieved. Secondary ion mass spectrometry (SIMS) data, x‐ray data, Hall data, the influence of doping incorporation with cadmium content and growth rate, etch pit density (EPD), composition uniformity determined from Fourier transform infrared (FTIR) transmission spectroscopy, and surface defect maps from low to high x values are presented to illustrate the versatility and quality of HgCdTe material grown by MBE. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Space‐charge‐limited current transport in nitride HFETs
Authors: Schimizzi R. D. , Trew R. J. , Bilbro G. L. 
Published: June 2010

AbstractHigh‐voltage microwave AlGaN/GaN HFETs operating under high‐power conditions suffer from degraded RF performance and linearity due to a nonlinear resistance effect in the gate‐source region. During RF operation, the nonlinear resistance is due to the onset a of space‐charge‐limited current (SCLC) transport mechanism within the device channel. Under high current injection conditions, SCLC transport can set in and, consequently, the source resistance becomes a function of the injected charge causing a rapid increase and limiting device performance. The threshold for SCL current is dependent on the donor‐like states on the AlGaN surface which are responsible for supplying electrons to the channel. To alleviate the effect of nonlinear source resistance we show on an un‐gated HFET channel model that the critical current density of space‐charge effects and thus the onset of nonlinear source resistance can be shifted above the normal operating current density of the device by modification of the charge on the AlGaN surface. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear‐mode operation of the quantum‐dot avalanche photodiode (QDAP)
Authors: Ramirez David A. , Shao Jiayi , Hayat Majeed M. , Krishna Sanjay 
Published: June 2010

AbstractWe report new results on the design, fabrication and characterization of a novel midinfrared sensor called quantum dot avalanche photodiode (QDAP). The QDAP consists of a quantum dots‐in‐a‐well (DWELL) detector coupled with an avalanche photodiode (APD) through a tunnel barrier. In the QDAP, the photons are absorbed in the DWELL active region while the APD section provides gain.Photocurrent and noise measurements at 77 K were taken to characterize the response of the device. The nonlinear increase in the photocurrent as the APD voltage increases support theoretical predictions about the QDAP capability to work in applications with low photon flux levels. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Short‐period AlN/GaN p‐type superlattices: hole transport use in p‐n junctions
Authors: Simon John , Cao Yu , Jena Debdeep 
Published: June 2010

AbstractHole transport properties of short‐period Mg‐doped AlN/GaN superlattices are compared with bulk Mg‐doped GaN layers. Due to polarization‐induced reduction in acceptor ionization energy, the superlattice structures are observed to result in a nearly temperatureindependent in‐plane p‐type conductivity as opposed to a 100‐fold decrease in bulk p‐type GaN as temperature drops from 300 K to 100 K.Moreover, significant vertical p‐type conductivity is facilitated by the ultrathin AlN barriers due to possible hole tunneling & miniband formation: p‐n junctions are demonstrated by replacing the p‐type GaN layer by a superlattice. The results indicate the feasibility of enhancement of both vertical and lateral p‐type conductivity in bipolar transistors and deep‐UV optical devices. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heterostructure engineering in Type II InAs/GaSb strained layer superlattices
Authors: Myers Stephen , Plis Elena , Kim Ha Sul , Khoshakhlagh Arezou , Gautam Nutan , Lee Sang Jun , Noh Sam Kyu , Krishna Sanjay 
Published: June 2010

AbstractThe background carrier concentration is an important factor in the performance of detectors. We have investigated the effect of a variable background doping concentration in the absorber region of an nBn type‐II InAs/GaSb superlattice infrared detector. The doping concentrations were 5 × 1016 cm‐3 (non‐intentionally doped, n.i.d.), 1.4 × 1017 cm‐3, 4.0 × 1017 cm‐3, and 3.5 × 1018 cm‐3. The specific detectivity of the detectors was found to dramatically decrease as the doping concentration was increased. This was caused by an increase in dark current density which is attributed to the presence of a quantum well (QW) formed in the valence band. This QW allowed for enhanced electron‐hole recombination at higher doping concentrations. Consequently the n.i.d. device demonstrated the best performance with a zero bias specific detectivity (D*) equal to 1.2 × 1011 Jones at 77 K. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of c‐axis oriented Ga‐doped MgZnO‐based UV transparent electrodes by molecular precursor method
Authors: Honda Tohru , Oda Takuto , Mashiyama Yoshihiro , Hara Hiroki , Sato Mitsunobu 
Published: June 2010

AbstractMgZnO films were fabricated by the molecular precursor method (MPM) for their application as UV transparent electrodes. It was clarified that annealing under suitable conditions using an Ar gas flow is effective for the realization of c‐axis‐oriented MgZnO films in the time of a pyrolysis reaction. The resistivity of the Ga‐doped Mg0.1Zn0.9O film was 2.5 × 10‐2 Ω · cm. The resistivity of the c‐axis‐oriented MgZnO films was lower than that of polycrystalline films. This is due to the reduction of the potential barrier at the boundaries of the crystallites. The spontaneous polarization affects the potential barrier. The c‐axis orientation reduces the potential barrier along the deposition plane (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical Kerr signals of GaAs/AlAs multilayer cavities with two‐photon resonant quantum wells in the half‐wavelength layer
Authors: Isu Toshiro , Kanbara Toshiyuki , Takahashi Tomoya , Morita Ken , Kitada Takahiro 
Published: June 2010

AbstractOptical Kerr signals from GaAs/AlAs multilayer micro‐cavities with GaAs/AlGaAs multi‐quantum wells (MQW) in the half‐wavelength cavity layer were investigated. The cavity‐mode‐wavelengths were set at the resonance region of two‐photon absorption of the MQWs in the 1.5‐μm band. The measured intensities of the signals depended strongly on the cavity‐mode wavelength, although the cavity layers including the MQW and multilayers maintained approximately the same structure. The nonlinearity of the MQW is considered to vary considerably at the resonant wavelength of the two‐photon absorption. The results indicate that the optical Kerr signal of the multilayer micro‐cavity is dominated by the nonlinearity of the cavity layer, although the cavity layer is only a small part of the total cavity thickness. This experimentally confirms the results of a previous simulation study on the multilayer cavities. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of the extraction of short diffusion lengths from simulated electron‐beam induced current
Authors: Wee D. , Parish G. , Nener B. 
Published: June 2010

AbstractThis paper reports on the investigations via 2‐D simulation into the accuracy of diffusion length extraction from scanning electron‐beam induced current measurements when the diffusion length, L is very short. L is extracted by using the direct method proposed by Chan et al. [1] and later refined by Kurniawan and Ong [2] to take finite junction depth into account. The 2‐D simulations were undertaken using Synopsys® Sentaurus TCAD and a realistic electron‐hole pair generation volume was created using CASINO v2.42 [3], a Monte Carlo Scanning Electron Microscope interaction simulation software, and imported into Sentaurus. The voltage and diameter of the electron beam and diffusion length and surface recombination velocity of the semiconductor materials were varied in the simulations to determine the errors in the diffusion length extracted from the EBIC signals as a function of these parameters. The results of the simulation show that the accuracy of the method proposed in [1] is reasonably accurate and that the beam voltage and spot size do not have significant effects on the accuracy (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of polar direction of AlN grown on (0001) sapphire and 6H‐SiC substrates by high‐temperature metal‐organic vapor phase epitaxy using coaxial impact collision ion scattering spectroscopy
Authors: Imura Masataka , Ohnishi Tsuyoshi , Sumiya Masatomo , Liao Meiyong , Koide Yasuo , Amano Hiroshi , Lippmaa Mikk 
Published: June 2010

AbstractHigh‐crystalline quality AlN layers with an atomically flat surface are grown on (0001) sapphire and 6H‐SiC substrates by metal‐organic vapor phase epitaxy at 1400 °C without low‐temperature buffer layer. The polar direction of AlN layers is investigated by coaxial impact‐collision ion scattering spectroscopy (CAICISS). For AlN growth on sapphire substrate, trimethylaluminum (TMAl) is supplied for 10 sec before introducing ammonia (NH3). For AlN growth on SiC substrate, TMAl and NH3 are supplied at the same time. The CAICISS spectrum of AlN layers is analyzed by measuring the dependence of the Al atoms signal intensity on the angle of ion beam incidence considering the shadowing and focusing effects for determining the polar direction of AlN layers. The CAICISS spectra clearly indicate the polar direction of AlN layers and both AlN layers are found to be had the Al‐polarity. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Normally‐on/off AlN/GaN high electron mobility transistors
Authors: Chang C. Y. , Lo C. F. , Ren F. , Pearton S. J. , Kravchenko I. I. , Dabiran A. M. , Cui B. , Chow P. P. 
Published: June 2010

AbstractWe report on the novel normally‐on/off AlN/GaN high electron mobility transistors (HEMTs) grown by plasma‐assisted molecular beam epitaxy. With simple oxygen exposure, the threshold voltage can be tuned from ‐2.76 V to +1.13 V depending on the treatment time. The gate current was reduced and current‐voltage curves show metal‐oxide semiconductor diode‐like characteristics after oxygen plasma exposure. The extrinsic transconductance of HEMTs decrease with increasing oxygen plasma exposure time due to the thicker Al oxide formed on the gate area. The unity current gain cut‐off frequency, fT, and maximum frequency of oscillation, fmax, were 20.4 GHz and 36.5 GHz, respectively for an enhancement‐mode HEMT with the gate dimension of 0.4 × 100 μm2. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Suppression of current collapse for millimeter‐wave GaN‐HEMTs
Authors: Yamada Atsushi , Makiyama Kozo , Ohki Toshihiro , Kanamura Masahito , Joshin Kazukiyo , Imanishi Kenji , Hara Naoki , Kikkawa Toshihide 
Published: June 2010

AbstractThis paper describes a technique to improve the drain leakage current and current collapse problems with GaN high electron mobility transistors (GaN‐HEMTs) for millimeter‐wave high‐power and high‐efficiency amplifiers with very short gate‐periphery. To investigate the relationships between the drain leakage, current collapse and crystal quality of an AlGaN buffer structure with a GaN channel layer, we performed analyses with an atomic force microscope (AFM) and examined photoluminescence (PL), lattice strain and electrical characteristics of devices. Through these analyses, we obtained an optimum epitaxial structure to reduce deep‐level defect formation in a GaN channel layer. We have clarified the effects of our work for the first time by looking at the correlation between the YL intensity and c‐axis lattice constant of a GaN channel layer. Using the optimum epitaxial structure, we minimized the drain leakage current and current collapse of a GaN‐HEMT (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical and structural characterization of GaN/AlGaN quantum wells for intersubband device applications
Authors: Driscoll Kristina , Liao Yitao , Bhattacharyya Anirban , Moustakas Theodore D. , Paiella Roberto , Zhou Lin , Smith David J. 
Published: June 2010

AbstractDue to their large conduction‐band offsets of up to 1.75 eV, GaN/Al(Ga)N quantum wells can support intersubband transitions at record short wavelengths, well into the low‐loss transmission window of optical fibers. As a result, these quantum structures are promising to enable new intersubband device applications, including all‐optical switching for ultra‐broadband fiber‐optic networks and emission of short‐wave infrared radiation. Here we report our work on the development of high‐quality GaN/Al(Ga)N quantum well structures designed for such applications. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Use of epitaxial unipolar barriers to block surface leakage currents in photodetectors
Authors: Savich G. R. , Pedrazzani J. R. , Maimon S. , Wicks G. W. 
Published: June 2010

AbstractSurface leakage currents are one of the many causes of dark current exhibited by semiconductor devices and are a common limiting factor to device performance for many types of devices. Traditionally, these surface leakage currents are controlled through the post‐epitaxial insertion of a surface passivation layer, but surface passivation is often expensive, time consuming, and not entirely effective. Unipolar barriers may be incorporated into electronic devices as a less expensive and more effective alternative way to control surface leakage currents. Unipolar barrier devices are demonstrated here using MBE‐grown InAs nBn detectors and unipolar barrier photodiodes. A commercial InAs photodiode becomes surface leakage current limited at 220 K while the nBn detector shows no surface leakage current down to at least 135 K. The unipolar barrier photodiode shows no detectable surface leakage down to at least 130 K while a matching conventional photodiode is limited by surface conduction at a temperature of 150 K. This indicates the greatly improved performance of the unipolar barrier devices (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐performance nanoparticle‐enhanced tunnel junctions for photonic devices
Authors: Crook Adam M. , Nair Hari P. , Bank Seth R. 
Published: June 2010

AbstractWe describe GaAs‐based tunnel junctions that are compatible with photonic devices, including long‐wavelength vertical‐cavity surface‐emitting lasers and multi‐junction solar cells. Tunneling was enhanced with semimetallic ErAs nanoparticles, particularly when grown at reduced substrate temperatures. Additionally, we present the first direct measurement of the quality of III‐V layers grown above ErAs nanoparticles. Photoluminescence measurements indicate that III‐V material quality does not degrade when grown above ErAs nanoparticles, despite the mismatch in crystal structures. These findings validate these tunnel junctions as attractive candidates for GaAs‐based photonic devices (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A method for obtaining randomized block designs in preclinical studies with multiple quantitative blocking variables
Authors: Iturria Stephen J. 
Published: June 2010

AbstractA method is proposed for block randomization of treatments to experimental units that can accommodate both multiple quantitative blocking variables and unbalanced designs. Hierarchical clustering in conjunction with leaf‐order optimization is used to block experimental units in multivariate space. The method is illustrated in the context of a diabetic mouse assay. A simulation study is presented to explore the utility of the proposed randomization method relative to that of a completely randomized approach, both in the presence and absence of covariate adjustment. An example R function is provided to illustrate the implementation of the method. Copyright © 2010 John Wiley & Sons, Ltd.
The clinical effectiveness of chokeberry: a systematic review
Authors: Chrubasik C. , Li G. , Chrubasik S. 
Published: June 2010

AbstractProducts derived from the black chokeberry, Aronia melanocarpa, are claimed to be beneficial in disorders or diseases associated with oxidative stress. The claims are based on evidence from in vitro studies and animal experiments. The active principle – a mixture of procyanidins, anthocyanins and phenolic acids – constitutes one of the most potent natural antioxidants. A systematic review was carried out of the quality of the clinical trials on chokeberry products that had been published up to December 2009, and conventionally established criteria were used to assess the strength of the evidence for their clinical effectiveness. Thirteen studies were identified. The quality of most of the trials and, correspondingly, the evidence of effectiveness for Aronia products is poor. Though laboratory and clinical data indicate that chokeberry products may well be useful as ‘functional food’ for disorders or diseases related to oxidative stress, these promising indications need to be confirmed in more rigorous studies before putative therapeutic uses can be confidently recommended for chokeberry products. Copyright © 2010 John Wiley & Sons, Ltd.