bluuebunny/crossref_metadata_2025_split huggingface dataset:
N-Type Hydrogenated Microcrystalline Silicon Oxide Films and Their Applications in Micromorph Silicon Solar Cells
Authors: Limmanee Amornrat , Kittisontirak Songkiate , Piromjit Channarong , Sritharathikhun Jaran , Sriprapha Kobsak 
Published: September 2011

ABSTRACTWe have prepared n-type hydrogenated microcrystalline silicon oxide films (n μc-SiO:H) and investigated their structural, electrical and optical properties. Raman spectra shows that, amorphous phase of the n μc-SiO:H films tends to increase when the CO2/SiH4 ratio increases from 0 to 0.28 resulting in a reduction of the crystalline volume fraction (Xc) from 70 to 12%. Optical bandgap (E04) becomes gradually wider while dark conductivity and refractive index (n) continuously drop with increasing CO2/SiH4 ratio. The n μc-SiO:H films have been practically applied as a n layer in top cell of a-SiO:H/μc-Si:H micromorph silicon solar cells. We found that, open circuit voltage (Voc) and fill factor (FF) of the cells gradually increased, while short circuit current density (Jsc) remained almost the same value with increasing CO2/SiH4 ratio for n top layer deposition up to 0.23. The highest initial cell efficiency of 10.7% is achieved at the CO2/SiH4 ratio of 0.23. The enhancement of the Voc is supposed to be due to a reduction of reverse bias at sub cell connection (n top/p bottom interface). An increase of shunt resistance (Rsh) which is caused by a better tunnel recombination junction contributes to the improvement in the FF. Quantum efficiency (QE) results indicate no difference between the cells using n top μc-SiO:H and the cells with n top μc-Si:H layers. These results reveal that, the n μc-SiO:H films in this study do not work as an intermediate reflector to enhance light scattering inside the solar cells, but mainly play a key role to allow ohmic and low resistive electrical connection between the two adjacent cells in the micromorph silicon solar cells.
Optical Demultiplexer Device: Frequency and optical bias analysis
Authors: Louro P. , Vieira M. , Vieira M. A. , Silva T. 
Published: September 2011

ABSTRACTIn this paper we present results on the use of a multilayered a-SiC:H heterostructure as a device for wavelength-division demultiplexing of optical signals. This device is useful in optical communications applications that use the wavelength division multiplexing technique to encode multiple signals into the same transmission medium. The device is composed of two stacked p-i-n photodiodes, both optimized for the selective collection of photo generated carriers. Band gap engineering was used to adjust the photogeneration and recombination rates profiles of the intrinsic absorber regions of each photodiode to short and long wavelength absorption and carrier collection in the visible spectrum. The photocurrent signal using different input optical channels was analyzed at reverse and forward bias and under steady state illumination. A demux algorithm based on the voltage controlled sensitivity of the device was proposed and tested. The operation frequency of the device was analyzed under different optical bias conditions. An electrical model of the WDM device is presented and supported by the solution of the respective circuit equations.
Influence of the Electrode Spacing on the Plasma Characteristics and Hydrogenated Amorphous Silicon Film Properties Grown in the DC Saddle Field PECVD System
Authors: Leong Keith R. , Kherani Nazir P. , Zukotynski Stefan 
Published: September 2011

ABSTRACTA new plasma deposition system was built with the capability of varying the electrode spacing in the DC Saddle Field plasma enhanced chemical vapor deposition system. An ion mass spectrometer was installed just below the substrate holder to sample the ion species travelling towards the substrate. Silane plasma and amorphous silicon film studies were conducted to shed light on the impinging ion species, ion energy distributions, and film properties with varying electrode spacing. The results indicate that decreasing the distance between the substrate and cathode leads to a reduction in the high energy ion bombardment.
Crack-free III-nitride structures (> 3.5 μm) on silicon
Authors: Tungare Mihir , Leathersich Jeffrey M. , Tripathi Neeraj , Suvarna Puneet , Shahedipour-Sandvik Fatemeh (Shadi) , Walsh Timothy A. , Tompkins Randy P. , Jones Kenneth A. 
Published: September 2011

ABSTRACTIII-nitride structures on Si are of great technological importance due to the availability of large area, epi ready Si substrates and the ability to heterointegrate with mature silicon micro and nanoelectronics. High voltage, high power density, and high frequency attributes of GaN make the III-N on Si platform the most promising technology for next-generation power devices. However, the large lattice and thermal mismatch between GaN and Si (111) introduces a large density of dislocations and cracks in the epilayer. Cracking occurs along three equivalent {1−100} planes which limits the useable device area. Hence, efforts to obtain crack-free GaN on Si have been put forth with the most commonly reported technique being the insertion of low temperature (LT) AlN interlayers. However, these layers tend to further degrade the quality of the devices due to the poor quality of films grown at a lower temperature using metal organic chemical vapor deposition (MOCVD). Our substrate engineering technique shows a considerable improvement in the quality of 2 μm thick GaN on Si (111), with a simultaneous decrease in dislocations and cracks. Dislocation reduction by an order of magnitude and crack separation of > 1 mm has been achieved. Here we combine our method with step-graded AlGaN layers and LT AlN interlayers to obtain crack-free structures greater than 3.5 μm on 2” Si (111) substrates. A comparison of these film stacks before and after substrate engineering is done using atomic force microscopy (AFM) and optical microscopy. High electron mobility transistor (HEMT) devices developed on a systematic set of samples are tested to understand the effects of our technique in combination with crack reduction techniques. Although there is degradation in the quality upon the insertion of LT AlN interlayers, this degradation is less prominent in the stack grown on the engineered substrates. Also, this methodology enables a crack-free surface with the capability of growing thicker layers.
Fabrication and Optical Properties of Green emission semipolar {101̅1} InGaN/GaN MQWs Selective Grown on GaN Nanopyramid Arrays
Authors: Chang Shih-Pang , Chang Jet-Rung , Huang Ji-Kai , Li Jinchai , Chen Yi-Chen , Sou Kuok-Pan , Li Yun-Jing , Yang Hung-Chih , Hsu Ta-Cheng , Lu Tien-Chang , Kuo Hao-Chung , Chang Chun-Yen 
Published: September 2011

AbstractWe report that the high crystalline and high efficiency green emission semipolar {101̅1} InGaN/GaN multiple quantum wells (MQWs) grown on the {101̅1} facets of GaN nanopyramid arrays by selective area epitaxy. Clear and sharp interfaces of the semipolar {101̅1} InGaN/GaN MQWs was observed by transmission electron microscopy images. As comparing with (0001) MQWs, the internal electric field of {101̅1} MQWs was remarkably reduced from 1.7 MV/cm to 0.5 MV/cm, and the room temperature (RT) internal quantum efficiency (IQE) at green emission was enhanced by about 80%. This greatly enhancement of IQE is due to suppress the polarization effect in the {101̅1} MQWs which shorten the radiative recombination to compete with nonradiative recombination at RT. These results evince that the {101̅1} planes are promising for solving the efficiency green gap of III-nitride light emitters.
Research Highlights from the U.S. Department of Energy’s Working Group on Photoelectrochemical Hydrogen Production
Authors: Miller Eric L. , Garland Roxanne , Dillich Sara 
Published: September 2011

ABSTRACTThe US Department of Energy (DOE) hydrogen production research and development portfolio focuses on low-cost, highly efficient and environmentally friendly production technologies based on diverse, domestic resources. Within the DOE, work on hydrogen production technologies integrates basic and applied research, as well as technology development and demonstration. The integration of basic and applied research is of particular importance in “transformational” production technologies, such as photoelectrochemical (PEC) hydrogen production, where scientific advances are needed for achieving the long-term DOE performance and cost targets. In the case of renewable hydrogen production via PEC solar water splitting, high solar-to-hydrogen conversion efficiency has been demonstrated to date on the laboratory scale, but only with high-cost, low-durability material systems. In order to identify and develop the appropriate high-efficiency, low-cost, durable and scalable PEC material systems, research and development efforts in the DOE EERE (Energy Efficiency and Renewable Energy) Office have keyed in on specific focus areas, including: 1) the engineering of solar energy absorption properties in PEC semiconductor materials, such as the bandgap lowering in stable metal oxides as well as bandgap raising in nanostructured sulfide catalysts; 2) the engineering of PEC solid-liquid interfaces for optimal reaction rates and stability, such as surface nitrogenation in III-V semiconductor systems; 3) the standardization of PEC measurement and reporting methodologies, using national and international peer-review process, for facilitating research progress; and 4) the design and analysis of integrated PEC device and system configurations for scalable hydrogen production. As described in this presentation, all of these research and development areas rely heavily on collaborative efforts among academia, industry and national laboratory partners, utilizing state of the art resources in materials theory, synthesis, characterization and analysis. The collaboration extends nationally among research programs supported by the DOE EERE as well as Office of Science; and internationally via networking through the International Energy Agency’s Hydrogen Implementation Agreement Annex-26. Key and encouraging accomplishments resulting from the collaborative work are highlighted in this presentation.
Costing out light source and product collection during evaluation of materials for renewable fuels
Authors: Palanivelu Karthikayini , Ramalingam Meenakshi , Ramanathan Ramnarayanan 
Published: September 2011

ABSTRACTWe examined LEDs as a cheap and test lamp source to simulate monochromatic laser radiation to help us cost out optics while evaluating materials for renewable fuels. The light source spectrum was recorded using a fiber optic spectrophotometer and a calibrated silicon photodiode was used to determine the intensity. Photon flux from the LEDs was recorded using actinometry. We chose CdS and Fe3O4 as photocatalysts. The as-prepared and annealed samples were characterised using X-Ray Diffraction, UV-Visible spectroscopy, UV-Visible Diffuse reflectance spectroscopy, Fourier Transform Infra-red spectroscopy, Attenuated Total Reluctance -FTIR spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). CdS and Fe3O4 were evaluated for hydrogen evolution using DI water, sacrificial agents and an electron donor (methyl viologen) using three light sources (LEDs, sunlight and mercury vapour lamp). Products were collected by an inverted burette (Generation1), balloons with a B-14 adapter (Generation2) and septum cells (Generation3). Developing an analytical technique to quantify products continues to remain a challenge.
Growth and In-line Characterization of Silicon Nanodots Integrated in Discrete Charge Trapping Non-volatile Memories
Authors: Amouroux J. , Della Marca V. , Petit E. , Deleruyelle D. , Putero M. , Muller Ch. , Boivin P. , Jalaguier E. , Colonna J-P. , Maillot P. , Fares L. 
Published: September 2011

ABSTRACTNon-Volatile Memories (NVM) integrating silicon nanodots (noted SDs) are considered as an emerging solution to extend Flash memories downscaling. In this alternative memory technology, silicon nanocrystals act as discrete traps for injected charges.Si-dots were grown by Low Pressure Chemical Vapor Deposition (LPCVD) on top of tunnel oxide. Depending on the pre-growth surface treatment, tunnel oxide surface may present either siloxane or silanol groups. SDs deposition relies on a 2–steps process: nucleation by SiH4 and selective growth with SiH2Cl2.In a context of technological industrialization, it is of primary importance to develop in-line metrology tools dedicated to Si-dots growth process control. Hence, silicon-dots were observed in top view by using an in-line Critical Dimension Scanning Electron Microscopy CDSEM and their average size and density were extracted from image processing. In addition, Haze measurement, generally used for bare silicon surface characterization, was customized to quantify Si-dots deposition uniformity over the wafer. Finally, Haze value was correlated to Si nanodots density and size determined by CDSEM.
Matrix Density Effect on Morphology of Germanium Nanocrystals Embedded in Silicon Dioxide Thin Films
Authors: Alagoz Arif S. , Genisel Mustafa F. , Foss Steinar , Finstad Terje G. , Turan Rasit 
Published: September 2011

ABSTRACTFlash type electronic memories are the preferred format in code storage at complex programs running on fast processors and larger media files in portable electronics due to fast write/read operations, long rewrite life, high density and low cost of fabrication. Scaling limitations of top-down fabrication approaches can be overcome in next generation flash memories by replacing continuous floating gate with array of nanocrystals. Germanium (Ge) is a good candidate for nanocrystal based flash memories due its small band gap. In this work, we present effect of silicon dioxide (SiO2) host matrix density on Ge nanocrystals morphology. Low density Ge+SiO2 layers are deposited between high density SiO2 layers by using off-angle magnetron sputter deposition. After high temperature post-annealing, faceted and elongated Ge nanocrystals formation is observed in low density layers. Effects of Ge concentration and annealing temperature on nanocrystal morphology and mean size were investigated by using transmission electron microscopy. Positive correlation between stress development and nanocrystal size is observed at Raman spectroscopy measurements. We concluded that non-uniform stress distribution on nanocrystals during growth is responsible from faceted and elongated nanocrystal morphology.
Interface Characterization of Metals and Metal-nitrides to Phase Change Materials
Authors: Roy Deepu , Gravesteijn Dirk J. , Wolters Rob A. M. 
Published: September 2011

ABSTRACTWe have investigated the interfacial contact properties of the CMOS compatible electrode materials W, TiW, Ta, TaN and TiN to doped-Sb2Te phase change material (PCM). This interface is characterized both in the amorphous and in the crystalline state of the doped-Sb2Te. The electrical nature of the interface is characterized by contact resistance measurements and is expressed in terms of specific interfacial contact resistance (ρC). These measurements are performed on four-terminal Kelvin Resistor test structures. Knowledge of the ρC is useful for selection of the electrode in the integration and optimization of the phase change memory cells.
Electro-forming of vacancy-doped metal-SrTiO3-metal structures
Authors: Hanzig Florian , Seibt Juliane , Stoecker Hartmut , Abendroth Barbara , Meyer Dirk C. 
Published: September 2011

ABSTRACTResistance switching in metal – insulator - metal (MIM) structures with transition metal oxides as the insulator material is a promising concept for upcoming non-volatile memories. The electronic properties of transition metal oxides can be tailored in a wide range by doping and external fields. In this study SrTiO3 single crystals are subjected to high temperature vacuum annealing. The vacuum annealing introduces oxygen vacancies, which act as donor centers. MIM stacks are produced by physical vapor deposition of Au and Ti contacts on the front and rear face of the SrTiO3 crystal. The time dependent forming of the MIM stacks under an external voltage is investigated for crystals with varying bulk conductivities. For continued formation, the resistivity increases up to failure of the system where no current can be measured anymore and switching becomes impossible.
Manipulation of amorphous Ge2Sb2Te5 nano-structures in isolated and crystalline environment.
Authors: Mio A. M. , D’Arrigo G. , Carria E. , Bongiorno C. , Rossini S. , Spinella C. , Grimaldi M. G. , Rimini E. 
Published: September 2011

ABSTRACTWe have investigated the stability of nano-amorphous region of Ge2Sb2Te5 (GST), fabricated by Electron Beam Lithography (EBL), dry etching, and ion implantation. Nano-structures, less than 100 nm in diameter and 20 nm thick, were either embedded in a crystalline environment or just isolated. We have observed nano-structure crystallization by in situ Transmission Electron Microscopy (TEM) in the 75°C-150°C temperature range. Re-crystallization of amorphous dots embedded in a crystalline region (either in the cubic or hexagonal phase) occurs by the movement of the interface at relatively low temperature (about 90°C). Instead, in the isolated structures the transition occurs at about 145°C by nucleation and growth. These results might be of relevance for the data retention of sub-50nm devices. Indeed, the more stable amorphous phase in self-standing regions indicates the better retention properties of isolated cells with respect to the traditional mushroom cell configuration.
Efficient near-infrared luminescence and energy transfer in Nd-Bi codoped zeolites
Authors: Bai Zhenhua , Fujii Minoru , Mori Yuki , Miwa Yuji , Mizuhata Minoru , Sun Hong-Tao , Hayashi Shinji 
Published: September 2011

ABSTRACTWe prepare Nd-Bi codoped zeolites by a method consisting of a simple ion-exchange process and subsequent high-temperature annealing. The emission covers the range of 970∼1450 nm, corresponding to the electronic transitions of Nd3+ ions and Bi-related active centers (BiRAC), respectively. The introduction of Bi distinctly broadens the excitation band of Nd3+ in the visible region, and the lifetime of Nd3+ reaches as long as 354 μs. In the zeolite matrix, Bi ions exist as BiRAC and Bi oxide agglomerates. The former one act as a sensitizer of Nd3+ ions, and the latter one act as a blockage to avoid the quenching effect of coordinated water, which enable Nd3+ ions to show efficient near-infrared (NIR) emission even the zeolites contain large amount of coordinated water. The excellent optical and structural properties make these NIR emitting nanoparticles promising in application as laser materials and biological probes.
Photoluminescence of Eu-doped GaN
Authors: O’Donnell K.P. 
Published: September 2011

ABSTRACTThis talk reviews work on the optical properties of Eu-doped GaN at the Semiconductor Spectroscopy laboratory of the University of Strathclyde. The principal experimental technique used has been lamp-based Photoluminescence/Excitation (PL/E) spectroscopy on samples produced mainly by high-energy ion implantation and annealing, either at low or high pressures of nitrogen, as described by Lorenz et al. [1]. These have been supplemented by samples doped in-situ either by Molecular Beam Epitaxy or Metallorganic Vapour Phase Epitaxy. Magneto-optic experiments on GaN:Eu were carried out in collaboration with the University of Bath.
Erythropoiesis-Stimulating Agents in Renal Medicine
Authors: Locatelli Francesco , Del Vecchio Lucia 
Published: September 2011

Abstract
The four currently available erythropoiesis-stimulating agents (ESAs), the main drugs for correcting anemia in patients with chronic kidney disease (CKD), are epoetin alfa, epoetin beta, darbepoetin alfa, and continuous erythropoietin receptor activator. The last two have much longer half-lives, which means they can be administered less frequently. The expiry of the patents for epoetin alfa and epoetin beta some years ago opened up the way for the production of a number of biosimilars that are now marketed in the European Union. Because biosimilars cannot be identical to their originator, a complex and still-evolving regulatory policy has been generated, but there are still a number of issues concerning international naming, automatic substitution, and safety.
All ESAs are effective in correcting renal anemia and increasing hemoglobin levels, but the choice of which to use should also take into account their pharmacokinetics and pharmacodynamics, their administration route, and economic issues.
Following the publication of a number of trials indicating no benefit (and even possible harm) when ESAs are used to aim at near-normal hemoglobin levels in CKD patients, the hemoglobin target has become a major subject of discussion. According to the position statement of the Anemia Group of the European Renal Best Practice, it should generally be about 11–12 g/dL; however, a risk–benefit evaluation is warranted in individual patients, and high ESA doses driven by hyporesponsiveness should be avoided.
Clinical Use of Erythropoietic Stimulating Agents in Myelodysplastic Syndromes
Authors: Santini Valeria 
Published: September 2011

Abstract
Myelodysplastic syndromes (MDS) are heterogeneous clonal diseases characterized by cytopenias resulting from ineffective hemopoiesis. Anemia affects the vast majority of patients with MDS and contributes substantially to their symptoms. For more than 20 years, recombinant human erythropoietin has been available for clinical use, and it has been employed in an attempt to relieve MDS-related anemia. Erythropoietin-alpha, erythropoietin-beta, and more recently darbepoetin have been found to increase hemoglobin levels and abolish transfusion dependence in 19%–68% of MDS cases. This wide range in clinical response depends on several biological and clinical variables that allow the selection of patients with the highest probability of successful treatment. These agents are a mainstay in MDS therapy, but many issues are still open in terms of the initiation of therapy, the optimal dosage of erythropoietic stimulating agents (ESAs), the most efficient type of ESA, and the duration and outcome of such treatments. In this review, the mechanisms of response and predictive factors as well as an analysis of the clinical activity of ESAs in MDS therapy are presented.
Demanding Customers: Consumerist Patients and Quality of Care
Authors: Fang Hai , Miller Nolan H. , Rizzo John , Zeckhauser Richard 
Published: September 2011

Abstract
Consumerism arises when patients acquire and use medical information from sources other than their physicians. This practice has been hailed as a means of improving quality. This need not be the result. Our theoretical model identifies a channel through which consumerism may reduce quality: consumerist patients place additional demands on their doctors’ time, thus imposing a negative externality on other patients. Relative to a world in which consumerism does not exist, consumerism may harm other consumerists, non-consumerists, or both. Data from a large national survey of physicians confirm the negative effects of consumerism: high levels of consumerist patients are associated with lower perceived quality among physicians.