bluuebunny/crossref_metadata_2025_split huggingface dataset:
InxGa1−xAs quantum wire network‐like and ordered checker board‐like nanostructures on GaAs (311) by low In composition multi‐layer stacking
Authors: Lee Jihoon , Wang Zhiming , Yazdanpanah V. , Kim Eun‐Soo , Koo Sang‐Mo , Salamo Gregory J. 
Published: November 2010

AbstractUnique quantum wire (QWR) network‐like nanostructures (QWRNNs) and ordered checker board‐like nanostructures (OCBNs) were demonstrated on GaAs (311) A and B by applying a low In composition multiple‐layer stacking technique. More specifically, the combination of low In composition and multilayer systems, [In0.18Ga0.82As/GaAs]m where m = 1, 4, 8, 10, 12, and 16 periods, have been investigated on GaAs (311) A and B by molecular beam epitaxy (MBE). Under a same growth condition, QWRNNs were demonstrated on GaAs (311)A while OCBNs were fabricated on GaAs (311)B as a result of the strain accumulation and transfer through the multiple layers stacked. An appropriate control of the number of layers stacked and spacer thickness can result in an improved ordering and uniformity of QWRNNs and OCBNs.
Analyses of the As doping of SiO2/Si/SiO2 nanostructures
Authors: Ruffino Francesco , Tomasello Mario Vincenzo , Miritello Maria , De Bastiani Riccardo , Nicotra Giuseppe , Spinella Corrado , Grimaldi Maria Grazia 
Published: November 2010

AbstractWe illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO2(70nm)/Si(30nm)/SiO2(70nm) multilayer and its spatial redistribution when annealing processes are performed. By Rutherford backscattering spectrometry and Z‐contrast transmission electron microscopy we found an As accumulation at the Si/SiO2 interfaces and at the Si grain boundaries with no segregation of the As in the Si layer.Such an effect is in agreement with a model that assumes a traps distribution in the Si in the first 2–3 nm above the SiO2/Si interfaces and along the Si grain boundaries. The traps concentration at the Si/SiO2 interfaces was estimated in 1014 traps/cm2. The outlined results can open perspectives on the doping properties of As in Si nanocrystals, whose applications in nanoelectronics and optoelectronics are widely investigated (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical characterisation of Si‐SiO2 structures
Authors: Capan Ivana , Pivac Branko , Slunjski Robert 
Published: November 2010

AbstractThe possibility of studying the Si‐SiO2 structures by means of deep level transient spectroscopy (DLTS) has been presented. Contrary to the standard application of this technique, the temperature interval has to be reduced. In order to minimize the influence, and possible errors due to the capacitance base line shift and the Fermi level pinning, C‐V characterization at different temperatures is crucial prior the DLTS measurement. The interface traps related to the Pb centers, distributed around 0.35 eV below the conduction band, have been observed (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observation of breather and soliton in a substituted polythiophene with a degenerate ground state
Authors: Kobayashi Takayoshi , Du Juan , Feng Wei , Yoshino Katsumi , Tretiak Sergei , Saxena Avadh , Bishop Alan R. 
Published: November 2010

AbstractThe ultrafast dynamics of a unique polythiophene derivative that has a degenerate ground state due to a quantum mechanical resonance was investigated using a sub‐5‐fs pulse laser. The method allowed us to study the electronic relaxation and vibrational dynamics in completely same conditions at the same time. The dynamics of a breather composed of a dynamic bound state of solitons generated immediately after photoexcitation was time‐resolved to reveal coupling between the vibrational modes and the solitons. The C‐C and C=C stretching modes were found to be modulated by the breather, whose lifetime was determined to be 30‐50 fs. The results of quantum‐chemical excited‐state molecular dynamics simulation are consistent with experimental results. Our modeling results allow to identify related vibrational normal modes strongly coupled to the electronic degrees of freedom. Moreover, analysis of calculated trajectories of excited state shows appearance of short‐lived breather excitation decaying due to intramolecular vibrational energy equilibration on a timescale of hundreds of femtoseconds, which also agrees well with the experimental results. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and magnetic properties of diluted magnetic semiconductor GaGdN nanorods
Authors: Tambo H. , Hasegawa S. , Higashi K. , Kakimi R. , Tawil S. N. M. , Zhou Y. K. , Emura S. , Asahi H. 
Published: November 2010

AbstractDiluted magnetic semiconductor GaGdN nanorods were grown on Si (001) substrates with native silicon oxides by molecular‐beam epitaxy with radio frequency nitrogen plasma. The Gd cell temperature dependences of their structural and magnetic properties were systematically studied. It was found that higher Gd fluxes suppress the growth of nanorods along the c‐direction and form GdN secondary phase. Magnetic measurement also revealed that nanorods of high content Gd showed small magnetization, indicating that GdN come to form and therefore the amount of Gd atoms substituted for Ga sites in GaGdN decreases. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface analysis of n‐GaN crystal damaged by RF‐plasma‐etching with Ar, Kr, and Xe gases
Authors: Niibe Masahito , Maeda Yoshie , Kawakami Retsuo , Inaoka Takeshi , Tominaga Kikuo , Mukai Takashi 
Published: November 2010

AbstractTo understand the etching phenomenon or preferential etching in the GaN crystal that consisted of two elemental atoms, dry etchings were carried out using rare gases with a simple structure. n‐type GaN crystals were RF‐plasma‐etched with Ar, Kr, and Xe gases at various gas pressures and etching times. The etched surfaces were analysed with the XPS method. The surface composition (N/Ga ratio) of the samples etched at Ar pressure of 10 mTorr and 200 mTorr almost agreed with the calculation values of the plasma particle model (PIS). N/Ga ratio of Ar etched sample at the pressure of 50 – 100 mTorr was approximately one and did not agree with the PIS calculation. This discrepancy seems to be related to the pit‐like defect formation at the pressure range. The values of the N/Ga ratio of the samples etched with Kr and Xe gases were approximately one and did not agree with the theoretical PIS calculation, which predicts N/Ga > 1. This discrepancy may have occurred by N2 molecule formation with excess N atoms, and which may have been desorbed from the surface. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic characterization of thin aluminum nitride microstructures
Authors: Knöbber F. , Bludau O. , Röhlig C.‐C. , Sah R. E. , Williams O. A. , Kirste L. , Leopold S. , Pätz D. , Cimalla V. , Ambacher O. , Lebedev V. 
Published: November 2010

AbstractIn this work we report on the mechanical and material properties of membranes made of AlN and nanodiamond for the use in tunable micro‐optics. AlN membranes with and without metal contacts have been studied in dynamic mode by laser Doppler vibrometry. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The optimization of TiO2 compact layer in dye‐sensitized solar cell by the analysis of performance and internal impedance
Authors: Kim Jin‐Kyoung , Seo Hyunwoong , Son Min‐Kyu , Shin Inyoung , Choi Jin‐Ho , Choi Seok‐Won , Kim Hee‐Je 
Published: November 2010

AbstractThe working electrode of a Dye–sensitized Solar Cell (DSC) is a fluorine‐doped tin oxide (FTO) glass substrate pasted with nano‐porous TiO2. Under the illumination, dye molecules are excited and electrons are emitted. The electrons pass through two interfaces of dye/TiO2 and TiO2/FTO. Therefore, electron of the TiO2 conduction band combines with I3‐ ion of the electrolyte. A compact layer between the FTO and nano‐porous TiO2 layer makes adherence of TiO2 to FTO surface improved, and the electron recombination reduced because it blocks the direct contact between the redox electrolyte and the FTO surface. Although some researches have studied the insertion of compact layer so far, only materials and the coating methods were studied. To the best of our knowledge, there was no study of a correlation between thickness and efficiency. Therefore, in this study, we investigated on the change in the output characteristics of DSCs according to thickness of TiO2 compact layer fabricated by coating in TiCl4 aqueous solution. The thickness of compact layer was controlled by repetitive coatings and measured by field emission scanning electron microscopy. The effects in terms of the I‐V characteristics and the electrochemical impedance spectroscopy (EIS) were examined for the analysis of the change in the thickness of TiO2 compact layer. As a result, the optimum thickness which has the highest output in the I‐V characteristics and the smallest area of EIS semi‐circle was derived. And the photovoltaic performance of DSC with an optimum compact layer was maximized (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction between conduction‐band edge and nitrogen‐related localized levels in nitrogen δ ‐doped GaAs
Authors: Harada Yukihiro , Kojima Osamu , Kita Takashi , Wada Osamu 
Published: November 2010

AbstractWe have studied sharp emission lines created by interacting between the GaAs host‐matrix conduction‐band edge and nitrogen‐related localized levels in nitrogen δ ‐doped GaAs by using magneto‐photoluminescence spectroscopy. According to the decreased diamagnetic coefficient of 75 μeV/T2 at the 1.515‐eV line, the interaction between the conduction‐band edge and localized levels has been confirmed. Furthermore, we have observed a linear polarization anisotropy for these emission lines. This polarization splitting demonstrates that the electronic states of the nitrogen pair couple with the GaAs conduction‐band edge. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
1/f noise models and low‐frequency noise characteristics of InAlAs/InGaAs devices
Authors: Pavelka Jan , Tacano Munecazu , Tanuma Nobuhisa , Šikula Josef 
Published: November 2010

AbstractTransport and low frequency noise characteristics of In0.52Al0.48As/InxGa1‐xAs heterostructures were measured in wide temperature range (15 K to 450 K) and experimental results compared with intrinsic 1/f noise models, estimating mobility fluctuations due to various scattering processes. The 1/f phonon energy partition fluctuation model predicts the value of Hooge parameter given as the ratio of the lattice constant and mean free path and several p‐type and n‐type samples reveal corresponding values of αH ≅ 0.5 and αH ≅ 4×10‐3, respectively. Most of the lattice‐matched n‐type samples however give much lower αH of about 10‐5 for temperature below 200 K, which is closer to the quantum 1/f noise theory limit. At elevated temperatures g‐r noise was observed with trap activation energy 0.63 eV. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Broadband light sources using InAs quantum dots with InGaAs strain‐reducing layers
Authors: Tsuda Megumi , Inoue Tomoya , Kita Takashi , Wada Osamu 
Published: November 2010

AbstractWe fabricated broadband superluminescent diodes (SLDs) for optical coherence tomography (OCT). We used three kinds of quantum dot (QD) layers with different emission peak wavelengths in the active region of SLD. The emission wavelength was controlled by reducing the strain in QDs; by using the In0.1Ga0.9 As strain‐reducing layer, the peak wavelength shifted toward the longer‐wavelength side, and the photoluminescence peak intensity becomes strong in contrast to QDs on GaAs.By stacking these strain‐controlled QD layers, the SLD device shows a broad electroluminescence spectrum with the center wavelength of 1130 nm and the spectral linewidth of approximately 240 nm at the injection of 1A caused by the increased emission intensity from the excited states. This corresponds to an resolution of 2.3 μm in OCT. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature‐insensitive photoluminescence emission wavelength in GaAs1–xBix/GaAs multiquantum wells
Authors: Tominaga Yoriko , Oe Kunishige , Yoshimoto Masahiro 
Published: November 2010

AbstractGaAs1–xBix/GaAs multiquantum wells (MQWs) were grown on GaAs substrate by molecular beam epitaxy at a growth temperature of 350 ºC. The MQWs showed clear satellite peaks and interference fringes between the satellite peaks in their high‐resolution x‐ray diffraction patterns. It was confirmed that photoluminescence (PL) emission wavelengths in GaAs1–xBix/GaAs MQWs have temperature insensitivity. The temperature coefficient of the PL peak energy in GaAs1–xBix/GaAs MQWs decreased with increasing GaBi molar fraction. For GaAs0.946Bi0.054/GaAs MQWs, the temperature coefficient of the PL peak energy was confirmed to be –0.19 meV/K (180–300 K) that is 40% of the value for the band gap of GaAs. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A dynamical model of drying process of a polymer solution having plural solvents and plural solutes (polymers) coated on a flat substrate for a flat and homogeneous polymer film fabrication
Authors: Kagami Hiroyuki , Kubota Hiroshi 
Published: November 2010

AbstractFlat and homogeneous polymer film fabrication such as resist coating in photo lithography process is very important for minute fabrication. In many cases, a polymer solution having plural solvents and plural solutes (polymers) is generally used there. So we modify the former dynamical model of drying process of polymer solution coated on a flat substrate for flat and homogeneous polymer film fabrication so as to deal with drying process of solution having plural solutes and plural solvents. As a result, we see that when there are over two kinds of solvents and over two kinds of solutes, solute's distribution after drying obeys the mean value of over two kinds of solvents' parameters through numerical simulations of the modified model. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Epitaxial graphene growth on 4H‐SiC (0001) with precisely controlled step‐ terrace surface by high temperature annealing above 2000 °C in UHV
Authors: Ushio Shoji , Yoshii Arata , Tamai Naoto , Ohtani Noboru , Kaneko Tadaaki 
Published: November 2010

AbstractSurface graphitization of 4H‐SiC (0001) at high temperature up to 2100 °C in ultra high vacuum (UHV) was observed for the first time in this study. From precisely controlled SiC step‐terrace surfaces, uniform graphitized surface morphologies with large terraces appeared at anneal temperatures above 2000 °C. All the high‐temperature processes were performed by using a newly constructed all metal chamber which enables to elevate temperature from 800 °C to 2000 °C within a minute in UHV. Initial step‐terrace surfaces consisting of 1.0nm step height were achieved on 4H‐SiC (0001) by utilizing newly proposed Si‐vapor etching in a “semi‐closed” TaC container. By estimations of Raman spectra, mainly bilayer graphene was obtained at temperatures from 1600 °C to 2100 °C. Estimation of Raman spectra also indicated that larger domain size graphene grows at higher temperatures, which coincides well with the results of morphological changes observed by AFM measurements. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence properties of CdSe/ZnS/TOPO nanocrystals in full‐ and half‐microcavity structures
Authors: Oda Masaru , Kazita Hiroyuki , Obara Yuki , Tani Toshiro 
Published: November 2010

AbstractWe report a recent study on photoluminescence (PL) properties of CdSe/ZnS/TOPO nanocrystals (NCs) in a planar full microcavity composed of top and bottom two metal (Ag) mirrors, and also in a similar structure but without top mirror, i.e. half‐microcavity, respectively. Angular‐dependencies of PL spectra and PL decay curves have been measured to investigate PL modifications due to light‐matter coupling in the microcavities. Obtained results indicate that PL dynamics are drastically changed depending on the microcavity structures. In the full‐microcavity, PL emission is directed at particular angles and its decay‐time is shortened, both of which can be described in terms of so‐called Purcell effect, i.e. the interaction between photon‐modes and confined excitons in the NCs. As for the half‐microcavity, anomalous PL band appears at low energy side of a main PL band associated with the confined excitons. The origin of the anomalous PL will be interpreted as due to the interaction between specific photon‐modes in the half‐microcavity structure and excitons associated with surface states. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of substrate temperature on ZnO thin film fabrication by using an atmospheric pressure cold plasma generator
Authors: Suzaki Yoshifumi , Kawaguchi Akiou , Murase Takehiko , Yuji Toshifumi , Shikama Tomokazu , Shin Dong‐Bum , Kim Yoon‐Kee 
Published: November 2010

AbstractUnder atmospheric pressure, homogeneous non‐equilibrium cold plasma was generated stably by high voltage pulsed power (1 kV, 20 kHz) excitation of He and O2 gases. By feeding Zn‐MOPD (C18H30O6Zn) into this plasma with He carrier gas, transparent flat ZnO films about 240 nm thick were successfully fabricated on glass substrates directly under a slit made into the cathode. Transmittance of the film is about 80% in the wavelength range from 400 to 600 nm. An XRD measurement revealed that these ZnO films had a c‐axis oriented polycrystalline structure. By increasing the substrate temperature from 250 to 400 °C, electrical resistivity of the film decreased from 0.42 Ωm to 9.4 × 10–4 Ωm. A high temperature of the substrate may change the growth pattern of ZnO film and its microstructure. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical and ferromagnetic properties of GdN thin films
Authors: Yoshitomi Hiroaki , Kitayama Shinya , Kita Takashi , Wada Osamu , Fujisawa Masashi , Ohta Hitoshi , Sakurai Takahiro 
Published: November 2010

AbstractWe studied the ferromagnetic phase transition and the resultant change in the optical band gap of GdN thin films grown by a reactive sputtering technique in an ultra‐high vacuum process. The GdN thin film exhibited two phases of spin ordering; the short correlation of spins starts to develop below ∼60 K, and the long‐range ferromagnetic ordering emerges below the Curie temperature of 37 K. GdN has been confirmed to be an indirect band gap semiconductor. We found that the band‐gap is dramatically reduced with the ferromagnetic spin ordering. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
“MBE‐Litho”: 3 nm‐thick amorphous GaAs oxidized thin film functioning as highly sensitive inorganic resist for EB lithography and oxide mask for selective processes
Authors: Matsuda Kazuhiro , Hirokawa Yuki , Ushio Shoji , Kaneko Tadaaki 
Published: November 2010

AbstractMolecular beam epitaxy (MBE) is one of the growth methods, which has been widely used for single crystalline semiconductor materials. In this study, we report a novel function of a 3 nm‐thick amorphous GaAs thin layer deposited using MBE at room temperature. Its oxidized region exposed to H2O‐vapor ambient works as a highly sensitive inorganic resist film for low‐energy electron‐beam (LE‐EB) lithography of 1‐5 keV. In this method, the surface area modified by LE‐EB direct writing provides a thermally stable oxide pattern, which can be directly applied to successive selective processes such as etching and growth under MBE environment. All the condition required for its selective etching/growth is to remove the background residual GaAs oxide of EB non‐irradiated area in the same UHV chamber. Thus, MBE gives the simplest and most efficient solution to all the processes including the resist film pre‐depositing, the background oxide removing and the successive etching/growth functions. We call this solution “MBE‐Litho ”. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Infrared reflection study of the photodissociation of donor‐acceptor pairs in the low‐temperature phase of tetratiafulvalene‐tetrabromo‐p ‐benzoquinone crystal
Authors: Nakata Y. , Kubota N. , Itoh C. 
Published: November 2010

AbstractWe have studied the 532‐nm laser‐pulses‐induced changes in the infrared reflection of the single crystal of the charge‐transfer complex of tetrathiafulvalene (TTF)‐tetrabromo‐p ‐benzoquinone (BA) at several temperatures. The laser excitation gave rise to reduction of the peaks attributed to the ag‐mode vibrations of TTF+ and BA–.The fractional reduction of the reflectance (ΔR /R) of these peaks showed a power‐law dependence on the excitation power, and its power index was found to decrease with the temperature rise. The magnitude of the ΔR /R at the given excitation power showed a peak around 38 K irrespective to the excitation power. This behavior was discussed in relation to the temperature dependence of the reflection intensity of the ag‐mode structures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Substrate dependence of Purcell enhancement in ZnO‐Ag multilayers
Authors: Lawrie B. J. , Mu R. , Haglund R. F. 
Published: November 2010

AbstractAg films in Ag‐MgO‐ZnO thin film multilayers support surface‐plasmon‐polaritons whose evanescent fields can dramatically affect the ZnO exciton recombination rate. Ultraviolet femtosecond pump‐probe spectroscopy and photoluminescence spectroscopy on these multilayers demonstrate that for MgO film thicknesses of 30 nm or less, the ZnO photoluminescence is enhanced, while the recombination rate is dramatically reduced for film thicknesses of 40‐60 nm, resulting in quenched photoluminescence. A comparison of heterostructures grown on Si and Al2O3 confirms that this phenomenon is substrate independent, though Si substrates do allow for surface plasmon polariton outcoupling through Si waveguide modes. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laparoendoscopic single‐site surgery using a multi‐functional miniaturein vivorobot
Authors: Wortman Tyler D. , Strabala Kyle W. , Lehman Amy C. , Farritor Shane M. , Oleynikov Dmitry 
Published: November 2010

AbstractBackgroundExisting methods used to perform laparoendoscopic single‐site surgery (LESS) require multiple laparoscopic tools that are inserted into the peritoneal cavity through a single, specialized port. These methods are inherently limited in visualization and dextrous capabilities by working through a single access point. A miniaturein vivorobotic platform that is completely inserted into the peritoneal cavity through a single incision can address these limitations, providing more intuitive manipulation capabilities and improved visualization.MethodsThe miniaturein vivorobotic platform for LESS consists of a multi‐functional robot and a remote surgeon interface. The robot has two arms and specialized end effectors that can be interchanged to provide monopolar cautery, tissue manipulation, and intracorporeal suturing capabilities.ResultsThis robot has been demonstrated in multiple non‐survival procedures in a porcine model, including four cholecystectomies.ConclusionThis study demonstrates the effectiveness of using a multi‐functional miniaturein vivorobot platform to perform LESS. Copyright © 2010 John Wiley & Sons, Ltd.
Highly nonrepetitive sequences: Winning strategies from the local lemma
Authors: Pegden Wesley 
Published: November 2010

AbstractWe prove game‐theoretic versions of several classical results on nonrepetitive sequences, showing the existence of winning strategies using an extension of the Lovász Local Lemma which can dramatically reduce the number of edges needed in a dependency graph when there is an ordering underlying the significant dependencies of events. This appears to represent the first successful application of a Local Lemma to games. © 2010 Wiley Periodicals, Inc. Random Struct. Alg., 2011