bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystalline silicon for photovoltaics
Authors: Kaden Thomas , Würzner Sindy , Dreckschmidt Felix , Möller Hans‐Joachim 
Published: January 2009

AbstractCrystalline silicon is currently the basis of about 95% of all solar cells commercially available. Multicrystalline silicon makes up over the half of this amount. The complex defect occurrence and interaction of defects in this material offers a wide field of research and a high potential for material improvement. Extended lattice defects such as dislocations and grain boundaries are important as recombination and storage centres for metallic impurities. Their control is essential to obtain high efficiencies of the solar cell. Important parameters for the assessment of the final efficiency of the solar cells are the distribution and structure of the defects and their impact on the lifetime of minority charge carriers. The current understanding of the nucleation mechanisms of the most important defects during crystal growth will be described. Interaction processes between mobile impurities and extended defects are important for the recombination activity. Measurements of the recombination behaviour and the contamination level will be presented. Effects on the solar cell efficiency shall be discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wafer bonding in silicon electronics
Authors: Reiche Manfred 
Published: January 2009

AbstractSemiconductor wafer bonding offers a new degree of freedom in the design of material combinations without the common restrictions of the structure of the materials bonded. It is already an established method for the industrial production of advanced substrates (SOI) applied as basic material in high‐performance device fabrication. SOI, i.e. a thin device layer on an insulator, is a promising concept for further device developments. The advantages of SOI can be combined with mobility enhancing materials such as strained silicon (SSOI) or germanium on insulator (GOI). The bonding process is not limited to a certain wafer diameter and is applicable to different material combinations which are important to integrate different functions on a chip (system on a chip, SoC). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High power AlGaN/GaN HFETs on 4 inch Si substrates
Authors: Ikeda Nariaki , Kaya Syuusuke , Li Jiang , Sato Yoshihiro , Kokawa Takuya , Kato Sadahiro 
Published: January 2009

AbstractIn this paper, we successfully demonstrate an AlGaN/GaN HFET with a high breakdown voltage on 4‐inch Si substrates. In order to obtain the high breakdown voltage and to improve the crystalline quality of GaN layers, a thick GaN epitaxial layer including a buffer layer was grown. The breakdown voltage and the maximum drain current were achieved to be over 1.3 kV and 120 A, respectively. Furthermore, the suppression of a current collapse phenomenon was examined. The on‐resistance was not significantly increased up to a high drain off‐bias‐stress of 900 V. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature‐dependent droop of electroluminescence efficiency in blue (In,Ga)N quantum‐well diodes
Authors: Fujiwara Kenzo , Jimi Hiroyuki , Kaneda Kei 
Published: January 2009

AbstractTemperature‐dependent electroluminescence (EL) intensity of a blue (In,Ga)N single quantum‐well diode has been extensively investigated as a function of current between 2 nA and 10 mA at 20‐300 K. At 300 K the EL external quantum efficiency (ηex) shows a maximum at a current density of ∼1 A/cm2 and droops under higher injection. However, the current density for the ηex maximum significantly decreases with decreasing temperature, for example, to ∼5 × 10–4 A/cm2 at 20 K, with improved maximum EL efficiency due to reduced nonradiative recombination. This low‐temperature enhancement of the ηex droop at lower injection indicates that the droop phenomena is not involved with high‐density carrier effects like Auger nonradiative recombination, but rather linked with the carrier escape under high forward bias conditions due to the presence of internal piezo‐fields in (In,Ga)N quantum‐well heterostructures. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selective growth of GaN nanodots and nanostripes on 6H‐SiC substrates by metal organic vapor phase epitaxy
Authors: Goh W. H. , Martin J. , Ould‐Saad S. , Gautier S. , Sirenko A. A. , Martinez A. , Le Gratiet L. , Ramdane A. , Maloufi N. , Ougazzaden A. 
Published: January 2009

AbstractGaN nanodots and nanostripes with smooth sidewall surfaces have been selectively grown on 6H‐SiC substrates by metal organic vapor phase epitaxy. By varying the growth reactor pressure, we have been able to grow either isolated nanostructures or laterally overgrown structures. As confirmed by the Raman scattering and X‐ray diffraction techniques, the nanostructures have no influence of step bunching that occurs in the unmasked area of the continuous GaN film. The frequency shift of the E2 optical phonons shows that the residual strain in the nanostripes is relaxed compared to the continuous GaN film. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Proposal and simulated results of a normally off AlGaN/GaN HFET structure with a charged floating gate
Authors: Hasegawa Fumio , Kambayashi Hiroshi , Li Jiang , Ikeda Nariaki , Nomura Takehiko , Kato Sadahiro , Yoshida Seiko 
Published: January 2009

AbstractA normally off AlGaN/GaN Hetero‐junction Field Effect Transistor (HFET) structure is proposed. Two dimensional electron gas (2DEG) of more than 1 × 1013 cm–2, which a AlGaN/GaN HFET generally has, can be compensated completely by the negative charge in a floating gate or in a SiO2 layer on the AlGaN. Computer simulation showed that the threshold voltage was shifted from ‐3 V to ‐15 V with 20 nm SiO2 layer between the control gate and the AlGaN layer, but it was also shifted to +5V with 5 × 1013 cm–2 electrons (negative charge) in the middle of the SiO2 layer (a floating gate) or minus ions in the SiO2 layer itself. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Epitaxial design of 475 nm InGaN laser diodes with reduced wavelength shift
Authors: Queren Désirée , Avramescu Adrian , Schillgalies Marc , Peter Matthias , Meyer Tobias , Brüderl Georg , Lutgen Stephan , Strauß Uwe 
Published: January 2009

AbstractWe have analyzed the quantum well stability of blue‐green emitting laser diodes grown on c ‐plane GaN substrates. Different parameters such as the material composition of the surrounding layers of the quantum well and the number of quantum wells were varied. We observed a strong influence of the barrier material composition (AlGaN, GaN, InGaN) on the quality of In rich quantum wells. Our preferred barrier material is GaN. In contrast InGaN barriers result in a higher defect density of 9.6 × 106 cm–2 in the quantum well whereas GaN barriers show a defect density of 1.8 × 106 cm–2. High indium content quantum wells with good crystalline quality were grown by improving the structure of the complete active region. Further enhancement could be achieved by using a double quantum well structure instead of a single quantum well structure. This offers the advantage that the wavelength shift is strongly reduced as a result of the lower current density in each quantum well. With our improvements we could realize laser diodes emitting at 475 nm with threshold current densities of 12 kA/cm2 and a slope efficiency of 500 mW/A. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resonant coupling between a gold‐nanosphere plasmon and localized excitons in InGaN
Authors: Toropov A. A. , Shubina T. V. , Jmerik V. N. , Ivanov S. V. , Ogawa Y. , Minami F. 
Published: January 2009

AbstractWe report on site‐selective enhancement of the emission of localized excitons in an In0.3Ga0.7N solid alloy, induced by a gold nanoparticle attached to an AFM probe and placed at the near‐field distance of the film surface. The InGaN films with a specific rough surface were grown on a GaN buffer layer by molecular beam epitaxy. Most of the amplifying effect is attributed to the local enhancement of the spontaneous emission recombination rate due to the coupling of the exciton emission dipole to the macroscopic dipole in the spheroidal gold nanoparticle at the frequency of the electronic plasma resonance. At low temperatures we demonstrate drastic narrowing of the photoluminescence line due to the selective enhancement of a part of the inhomogeneously broadened emission spectrum by affecting only a limited number of localized excitons. The presented technique allows relatively easy mapping of the distribution of localized excitons in solid alloys and nanostructures with the resolution below the diffraction limit and represents a way to extract and amplify the emission of single quantum emitters (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measurement of misorientation of AlN layer grown on (111)Si for freestanding substrate
Authors: Saito K. , Tajima J. , Kumagai Y. , Ishizuki M. , Takada K. , Morioka H. , Koukitu A. 
Published: January 2009

AbstractA novel technique for misorientation determination based on energy dispersive X‐ray diffraction is introduced. The energy dispersive diffractometer equips with a silicon drift detector as a energy dispersive detector and a micro focus air cooled X‐ray tube as a source. The diffractometer has advantages in speed of measurement and alignment of sample compared with conventional angular dispersive diffractometer. Dependence of misorientation of AlN layers on misorientation angle and direction of (111) Si starting substrates were investigated by this method. It is found that the AlN has (0001) orientation and the (0001) plane is tilted when the film thickness is thin. Moreover, it is shown that the tilt becomes smaller with increasing the film thickness. The atomic force microscopy (AFM) showed clear difference in surface morphology of obtained AlN layer depending on misorientation direction of Si substrate. The AlN film grown on (111) Si with 1 degree misorientation angle toward [$ \bar 1 \bar 1 2 $] showed the best step and terrace structure compared with those grown on that having larger than 1 degree misorientation angle. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface changes by GaN photoelectrochemical treatment using various electrolytes with and without C2H5OH
Authors: Fujii Katsushi , Sato Keiichi , Kato Takashi , Koike Kayo , Yao Takafumi 
Published: January 2009

AbstractThe surface changes of n‐type GaN during photoelectrochemical treatment were investigated by not only electrochemical measurement but also photoluminescence (PL). The electrolytes used were H2SO4, Na2SO4, and NaOH with and without C2H5OH in order to clarify the reaction difference. The intensity oscillations of deep PL peaks decreased with increasing surface roughness. The D0X peak shift with strain release by the surface roughened were also observed. The surface treated using Na2SO4 with/without C2H5OH were oxidized and caused new PL peaks related to the surface defects. All of the surfaces treated with C2H5OH were observed much less change. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Substituent effect on intramolecular hydrogen bonding in 2‐hydroxybenzaldehyde
Authors: Ebrahimi A. , Habibi S. M. , Neyband R. S. 
Published: January 2009

AbstractThe effect of some substituents on intramolecular hydrogen bonding of 5‐X‐2‐hydroxybenzaldehyde (5‐X‐2‐HBA) has been studied by B3LYP and MP2 methods using 6‐311++G** and AUG‐cc‐PVTZ basis sets. The relationship between hydrogen bond energyEHBand electron donation (or withdrawal) of substituents has been investigated. An approximately good linear relationship has been detected between Hammett coefficients and hydrogen bond formation energy (R2= 0.98). Herein, population analysis has been performed by atoms in molecules (AIM) and natural bond orbital (NBO) methods. The results of AIM and NBO analyses are in a good agreement with calculated energy values. Furthermore, correlation between ring aromaticity and hydrogen bonding has been investigated by nucleus‐independent chemical shift (NICS) at GIAO/B3LYP/6‐311++G** level of theory. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Use of activated graphitized carbon chips for liquid chromatography/mass spectrometric and tandem mass spectrometric analysis of tryptic glycopeptides
Authors: Alley William R. , Mechref Yehia , Novotny Milos V. 
Published: January 2009

AbstractProtein glycosylation has a significant medical importance as changes in glycosylation patterns have been associated with a number of diseases. Therefore, monitoring potential changes in glycan profiles, and the microheterogeneities associated with glycosylation sites, are becoming increasingly important in the search for disease biomarkers. Highly efficient separations and sensitive methods must be developed to effectively monitor changes in the glycoproteome. These methods must not discriminate against hydrophobic or hydrophilic analytes. The use of activated graphitized carbon as a desalting media and a stationary phase for the purification and the separation of glycans, and as a stationary phase for the separation of small glycopeptides, has previously been reported. Here, we describe the use of activated graphitized carbon as a stationary phase for the separation of hydrophilic tryptic glycopeptides, employing a chip‐based liquid chromatographic (LC) system. The capabilities of both activated graphitized carbon and C18 LC chips for the characterization of the glycopeptides appeared to be comparable. Adequate retention time reproducibility was achieved for both packing types in the chip format. However, hydrophilic glycopeptides were preferentially retained on the activated graphitized carbon chip, thus allowing the identification of hydrophilic glycopeptides which were not effectively retained on C18 chips. On the other hand, hydrophobic glycopeptides were better retained on C18 chips. Characterization of the glycosylation sites of glycoproteins possessing both hydrophilic and hydrophobic glycopeptides is comprehensively achieved using both media. This is feasible considering the limited amount of sample required per analysis (<1 pmol). The performance of both media also appeared comparable when analyzing a four‐protein mixture. Similar sequence coverage and MASCOT ion scores were observed for all proteins when using either stationary phase. Copyright © 2009 John Wiley & Sons, Ltd.
Periphyton and invertebrate response to wood placement in large pacific coastal rivers
Authors: Coe Holly J. , Kiffney Peter M. , Pess George R. , Kloehn Kris K. , McHenry Michael L. 
Published: January 2009

AbstractWood abundance in aquatic systems has been dramatically reduced compared to historical levels due to anthropogenic activities that led to wood removal and stream simplification. As a result, reintroduction of wood to aquatic systems is now a widely used and relatively well‐studied restoration technique for increasing habitat complexity. Although stream periphyton (biofilm) and invertebrates serve as food sources for a variety of predators including fish, birds and bats, data on how lower trophic levels respond to wood placement are relatively scarce. The purpose of this study was to test the hypothesis that periphyton biomass and aquatic invertebrate density were higher on Engineered Log Jams (ELJs) than on inorganic substrates in two large Pacific Northwest river systems. Among years and rivers, periphyton biomass and invertebrate densities were significantly higher on ELJs than on cobbles within the same reach. Invertebrate communities on ELJs were dominated by meiofauna (<500 µm), whereas cobbles were dominated by larger chironomids. We attribute these trophic level differences to substrate type, as we did not detect taxonomic differences between cobbles in reaches with and without ELJs. We show that adding wood to reaches with little or no naturally occurring wood increased overall habitat surface area and thereby the potential for increased productivity relative to reaches with low levels of wood. Finally, wood supports a unique community of invertebrates that are often overlooked in lotic system studies but may be contributing substantially to overall biological diversity. Published in 2009 by John Wiley & Sons, Ltd.
Verification-guided modelling of salience and cognitive load
Authors: Rukšėnas Rimvydas , Back Jonathan , Curzon Paul , Blandford Ann 
Published: January 2009

Abstract
Well-designed interfaces use procedural and sensory cues to increase the cognitive salience of appropriate actions. However, empirical studies suggest that cognitive load can influence the strength of those cues. We formalise the relationship between salience and cognitive load revealed by empirical data. We add these rules to our abstract cognitive architecture, based on higher-order logic and developed for the formal verification of usability properties. The interface of a fire engine dispatch task from the empirical studies is then formally modelled and verified. The outcomes of this verification and their comparison with the empirical data provide a way of assessing our salience and load rules. They also guide further iterative refinements of these rules. Furthermore, the juxtaposition of the outcomes of formal analysis and empirical studies suggests new experimental hypotheses, thus providing input to researchers in cognitive science.
Induction of labor versus expectant management for post‐date pregnancy: Is there sufficient evidence for a change in clinical practice?
Authors: WENNERHOLM ULLA‐BRITT , HAGBERG HENRIK , BRORSSON BENGT , BERGH CHRISTINA 
Published: January 2009

AbstractObjectives. To compare perinatal and maternal outcomes between elective induction of labor versus expectant management of pregnancies at 41 weeks and beyond. Design. Systematic review and meta‐analysis. Methods. We searched PubMed, CINAHL, Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts of Reviews of Effectiveness (DARE) and PsycINFO (1980 to November, 2007). Inclusion criteria were systematic reviews and randomized controlled trials comparing elective induction of labor versus expectant management of pregnancies at 41 weeks and beyond. Three or more reviewers independently read and evaluated all selected studies. Data were extracted and analyzed using Review Manager Software. Main outcome measures. Perinatal mortality. Results. Thirteen trials fulfilled the inclusion criteria for the meta‐analysis. Elective induction of labor was not associated with lower risk of perinatal mortality compared to expectant management (relative risks (RR): 0.33; 95% confidence intervals (CI): 0.10–1.09). Elective induction was associated with a significantly lower rate of meconium aspiration syndrome (RR: 0.43; 95% CI: 0.23–0.79). More women randomized to expectant management were delivered by cesarean section (RR: 0.87; 95% CI: 0.80–0.96). Conclusions. The meta‐analysis illustrated a problem with rare outcomes such as perinatal mortality. No individual study with adequate sample size has been published, nor would a meta‐analysis based on the current literature be sufficient. The optimal management of pregnancies at 41 weeks and beyond is thus unknown.
Early signs of maternal iron deficiency do not influence the iron status of the newborn, but are associated with higher infant birthweight
Authors: ERVASTI MARI , SANKILAMPI ULLA , HEINONEN SEPPO , PUNNONEN KARI 
Published: January 2009

AbstractObjective. To investigate the associations between maternal iron status, pregnancy outcome and newborn iron status using sensitive and specific red blood cell indices reflecting iron‐deficient erythropoiesis. Design and setting. Cross‐sectional study in Kuopio University Hospital, Finland. Population. One hundred and ninety‐two pregnant women and their full‐term newborns (cord blood). Methods. Quartile analysis and Spearman correlations were used to investigate the associations of the iron status of pregnant women with that of their newborns, and with pregnancy outcome. Main outcome measures. Maternal and cord blood analysis including indices reflecting the hemoglobin (Hb) content of red blood cells as well as serum iron, transferrin saturation, transferrin receptor and ferritin. Gestational age, birthweight and placental weight. Results. The highest quartile of the maternal percentage of hypochromic red blood cells (%HYPOm) indicating the lowest iron status was associated with a high birthweight and a long duration of pregnancy. The newborns in this group did not show any signs of iron deficiency even though the maternal %HYPOm was elevated. Conclusions. In a well‐nourished maternal population, lower maternal iron status did not affect the iron accumulation on the fetal side. However, longer duration of pregnancy and growth of the fetus appeared to be associated with a lower amount of iron for Hb synthesis in maternal red blood cells, as reflected by the increased maternal %HYPOm, birthweight and length of gestation.
Red blood cell n‐3 polyunsaturated fatty acids in first trimester of pregnancy are inversely associated with placental weight
Authors: MAGNUSARDOTTIR ANNA R. , STEINGRIMSDOTTIR LAUFEY , THORGEIRSDOTTIR HOLMFRIDUR , HAUKSSON ARNAR , SKULADOTTIR GUDRUN V. 
Published: January 2009

AbstractObjective. To investigate pregnancy outcome in relation to red blood cell (RBC) level of long‐chain n‐3 polyunsaturated fatty acids (PUFA) in the first trimester of pregnancy and the influence of lifestyle factors on the RBC level of long‐chain n‐3 PUFA. Design and setting. Observational study in a community with traditional fish and cod liver oil consumption. Population. Seventy‐seven healthy pregnant women. Methods. The PUFA composition of RBC was measured in the 11th to 15th week of pregnancy. The women answered food frequency and lifestyle questionnaires. Information on pregnancy outcome was collected from birth records. Main outcome measures. Placental weight, long‐chain n‐3 PUFA in diet and RBC, smoking. Results. Of all the pregnancy outcome variables tested, placental weight was the only one associated with long‐chain n‐3 PUFA in RBC. Inverse association was found between the proportion of long‐chain n‐3 PUFA in RBC and placental weight, adjusted for birthweight (p = 0.035). The proportion of long‐chain n‐3 PUFA in RBC was positively related to long‐chain n‐3 PUFA intake (p<0.001) and negatively related to smoking (p = 0.011). Conclusion. The human fetus relies on maternal supply and placental delivery of long‐chain n‐3 PUFA for optimal development and function, particularly of the central nervous system. Given the importance of dietary n‐3 PUFA during pregnancy, further studies are warranted to investigate the relationship between placental weight, maternal long‐chain n‐3 PUFA status and smoking.