bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient Decay from the Steady-State in Microcrystalline Silicon
Authors: Brüggemann R. , Reynolds S. , Main C. 
Published: March 2017

AbstractWe measured the transient photocurrent decay from the steady state in microcrystalline silicon from plasma-enhanced chemical vapor deposition and hot-wire chemical vapour deposition. Samples exhibiting a range of photoconductive properties in terms of both the majority and minority carrier mobility-lifetime products or sub-gap absorption coefficients were studied. Measurements were made over a wide range of steady-state photogeneration rates for which we detail the variation with generation rate of the decay time. Samples with a short steady-state photocarrier lifetime show a long decay time. We relate the slow decay process to the much larger density of traps in the band gap in the poor-quality samples. Trapped carriers are released, undergo emission and trapping processes and eventually recombine in these samples, on a much longer time-scale than in the higher-quality samples so that the decay time cannot be taken as a fingerprint for photo-electronic quality. Analytical and numerical modeling indicate bimolecular recombination behavior during the decay. Results are in agreement with free-carrier interaction with exponentially distributed band-tail states.
The Meyer-Neldel Rule in Conductivity of Microcrystalline Silicon
Authors: Ram Sanjay K. , Kumar Satyendra , Cabarrocas P. Rocai 
Published: March 2017

AbstractThe dark conductivity (σd) has been measured from 300 to 440K on undoped hydrogenated microcrystalline silicon (μc-Si:H) films having different thicknesses. The carrier transport is found to be thermally activated with single activation energy (Ea) in all the samples. The Ea increases as the film thickness decreases. At the same time logarithmic of dark conductivity prefactor (σo) is found to follow a linear relation with activation energy, known as the Meyer-Neldel rule (MNR). Results are explained in terms of increased degree of disorder in thinner samples. Thus change in Ea with the film thickness is directly related to the density of localized states at the Fermi level in grain boundary (GB). Therefore varying the film thickness and, hence, the exponential density of states induces a statistical shift of Fermi level which gives rise to the observed MNR.
The Effect of Aging on Tungsten Filament Surface Kinetics in Hot-Wire Chemical Vapor Deposition of Silicon
Authors: Holt Jason K. , Swiatek Maribeth , Goodwin David G. , Atwater Harry A. , Watson Thomas J. 
Published: March 2017

AbstractWire-desorbed radicals present during hot-wire chemical vapor deposition growth have been measured by quadrupole mass spectrometry. For wire temperatures in excess of 1500 K, Si is the predominant radical desorbed from a new wire, with a minor contribution from SiH3. Aged wires showed profoundly different radical desorption kinetics, consistent with evaporation of Si from liquid silicon. It is proposed that this aging is related to silicide formation at the surface of the wire.
Mapping the Phase-Change Parameter Space of Hot-Wire CVD Si:H Films Using In-Situ Real Time Spectroscopic Ellipsometry
Authors: Levi Dean H. , Nelson Brent P. , Perkins John D. 
Published: March 2017

AbstractIn-situ real-time spectroscopic ellipsometry (RTSE) provides detailed information on the evolution of the structural and optical properties of Si:H films during film growth. We have used in-situ RTSE to characterize the film morphology and crystallinity of hot-wire CVD (HWCVD) Si:H films as a function of hydrogen dilution R=[H]/[H+SiH4], substrate temperature Ts, and film thickness db. Transitions from one mode of film growth to another are indicated by abrupt changes in the magnitude of the surface roughness during film growth. The degree of crystallinity of the film can be determined from the bulk dielectric function. We have studied the growth parameter space consisting of R from 0 to 12, Ts from 150°C to 550°C, and db from 0 to 1 um. For each set of R and Ts values, the structural evolution of the film can be characterized by the shape of the surface roughness thickness ds versus bulk thickness db curve. In contrast to studies done by Collins et al on PECVD growth of Si:H films, our studies of HWCVD growth find no conditions where ds remains constant after coalescence of the initial nucleation centers. Most of the films grown within the range of parameters studied exhibit a secondary nucleation and coalescence signature. The transition between a-Si:H and uc-Si:H growth is near the R=3 to R=4 dividing line. Initial coalescence of purely uc-Si:H material doesn't occur until R>8. We have verified the RTsE crystallinity classification using ex-situ Raman scattering.
High Rate Deposition of Microcrystalline Silicon Solar Cells Using 13.56 MHz PECVD – Prerequisites and Limiting Factors
Authors: Roschek Tobias , Repmann Tobias , Kluth Oliver , Müller Joachim , Rech Bernd , Wagner Heribert 
Published: March 2017

AbstractMicrocrystalline silicon (μìc-Si:H) solar cells were prepared in a wide range of deposition parameters using high pressure 13.56 MHz plasma-enhanced chemical vapor deposition (PECVD). Focus was on the influence of deposition pressure, electrode distance and the application of a pulsed plasma on high rate deposition of solar cells. At electrode distances between 5 and 20 mm solar cells with efficiencies >8 % were prepared. A medium electrode distance of 10 mm yielded best device performance. Pulsed plasma deposition leads to good results at medium deposition rates of ∼5 Å/s, for higher rates a strong decrease of efficiency was observed. The highest efficiencies in a small area reactor were 8.9 % for CW and 8.4 % for pulsed plasma. We also succeeded in preparing μc-Si:H and a-Si:H/μc-Si:H solar cells in a 30x30 cm2 reactor with efficiencies of 9 % and 12.5 %, respectively.
Amorphous and Microcrystalline Silicon Solar Cells Grown by Pulsed PECVD Technique
Authors: Das Ujjwal K. , Morrison Scott , Madan Arun 
Published: March 2017

AbstractThe Pulsed PECVD technique involves modulating the standard 13.56 MHz RF plasma, in the kHz range. This allows an increase in the electron density during the ‘ON’ cycle, while in the ‘OFF’ cycle neutralizing the ions responsible for dust formation in the plasma. In this work, we report the increase of i-layer growth rate and silane gas utilization rate (GUR) for amorphous Si p-i-n solar cells grown in a large area (30 cm × 40 cm) single chamber deposition system. The i-layer growth rate of 5.4 Å/sec with a GUR of >15% has been achieved, which shows a device efficiency of 8.3% (almost same as of our conventional PECVD grown a-Si:H solar cell with ilayer growth rate of ∼1 Å/sec). We also deposited microcrystalline Si p-i-n devices using the Pulsed PECVD technique. The crystallite orientation of the films changes from a random to a (220) orientation near the microcrystalline-to-amorphous transition. The effects of crystallite orientation, grain boundaries and ion bombardment during growth on the solar cell performances are investigated. An efficiency of 4.8% for single junction μc-Si:H p-i-n device has been achieved for the i-layer thickness of 0.9 μm.
Large Area Electronics for Flat Panel Imagers Progress and Challenges
Authors: Lu J.P. , Schuylenbergh K. Van , Ho J. , Wang Y. , Boyce J. B. , Street R. A. 
Published: March 2017

AbstractThe technology of large area electronics has made significant progress in recent years because of the fast maturing excimer laser annealing process. The new thin film transistors based on laser processed poly silicon provide unprecedented performance over the traditional thin film transistors using amorphous silicon. They open up the possibility of building flat panel displays and imagers with higher integration and performance. In this paper, we will review the progress of poly-Si thin film transistor technology with emphasis on imager applications. We also discuss the challenges of future improvement of flat panel imagers based on this technology.
Microstructure Characterization of a-Si Based Alloys by Effusion of Implanted Helium
Authors: Beyer Wolfhard , Finger Friedhelm 
Published: March 2017

AbstractThe microstructure of amorphous alloys of silicon with oxygen, carbon, nitrogen and germanium is studied by effusion measurements of hydrogen and of implanted rare gases helium, neon, argon. The results suggest a general widening of network openings with increasing alloy concentration. Isolated voids disappear for wide bandgap alloys already at low alloy concentration of 5–10 at.% presumably because interconnected voids are formed. At an alloy concentration near 20–30 at.%, Ne and H2 become mobile at T < 500°C and at higher temperature/alloy concentration Ar becomes mobile, too. Void formation is mainly attributed to an increase in hydrogen incorporation.
Integration of Expanding Thermal Plasma deposited Hydrogenated Amorphous Silicon in Solar Cells
Authors: Korevaar B.A. , Smit C. , Petit A.M.H.N. , van Swaaij R.A.C.M.M. , van de Sanden M.C.M. 
Published: March 2017

AbstractA cascaded arc expanding thermal plasma is used to deposit intrinsic hydrogenated amorphous silicon at growth rates between 0.2 and 3 nm/s. Incorporation into a single junction p-i-n solar cell resulted in an initial efficiency of 6.7%, whereas all the optical and initial electrical properties of the individual layers are comparable with RF-PECVD deposited films. In this cell the intrinsic layer was deposited at 0.85 nm/s and at a deposition temperature of 250°C, which is the temperature limit for growing the p-i-n sequence. The cell efficiency is limited by the fill factor and using a buffer layer at the p-i interface deposited with RF-PECVD at low growth rate can increase this. The increase in fill factor is a result of a lower initial defect density near the p-i interface then obtained with the expanding thermal plasma, resulting in better charge carrier collection. To use larger growth rates, while maintaining the material properties, higher deposition temperatures are required. Higher deposition temperatures result in a smaller optical bandgap for the intrinsic layer and deterioration of the p-type layer, resulting in a lower opencircuit voltage. First results on applying a buffer layer will also be presented.
Hyrogenated Amorphous Silicon with High Growth Rate, Gas Utilization and Homogeneous Deposition by Amplitude Modulated Vhf-Pecvd for Solar Cell Application
Authors: Rath J.K , Biebericher A.C.W. , Jimenez Zambrano R. , Schropp R.E.I. , van der Weg W. F. , Goedheer W.J. 
Published: March 2017

AbstractHydrogenated amorphous silicon samples have been deposited by very high frequency plasma enhanced chemical vapour deposition (VHF PECVD), using a square-wave amplitudemodulated radio-frequency excitation. It is observed that the gas-utilization efficiency improves by a considerable amount when amplitude modulation is combined with a reduction in the gas flows. Using a conventional continuous wave (cw) 50 MHz plasma with SiH4 and H2 gas flows of 30 sccm each at a pressure of 0.2 mbar, the gas-utilization efficiency is about 8%. It increases up to 50%, by modulating the amplitude of the radio-frequency excitation signal and reducing both gas flows to 10 sccm, keeping the pressure constant. In this case, the deposition rate amounted to 0.55 nm/s; which is twice as large as compared to the deposition rate of a cw deposition. Device-quality opto-electronic properties are obtained under these conditions. The refractive index at 2 eV is about 4.25 and the microstructure parameter has a value around 0.02. The materials exhibited a low defect density (CPM) which is in the order of 3-8x1015 per cubic centimeter and photo-to-dark-conductivity ratio of 4-6x106. N-i-p solar cells of size 0.16 cm2 deposited on 10cmx10cm stainless steel (SS) substrate in the configuration SS/n-a-Si:H/i-a- Si:H/buffer/p-μc-Si/ITO/Ag grid (without back reflector) using amorphous silicon i-layer made by amplitude-modulated VHF plasma CVD showed an efficiency of 6.5%. This is a similar efficiency to the cell with standard device-quality cw a-Si:H in the same n-i-p structure, but at a high growth of 0.55 nm/s and gas utilization of ∼50%.
Reduction of Dark Current Under Reverse Bias in a-Si:H p-i-n Photodetectors
Authors: Morrison S. , Servati P. , Vygranenko Y. , Nathan A. , Madan A. 
Published: March 2017

AbstractThis paper presents the development of low dark current amorphous silicon (a-Si:H) based heterojunction photodiodes. A series of p-i-n and n-i-p structures have been deposited by plasma-enhanced chemical vapor deposition (PECVD). Junction properties and carrier transport are investigated in terms of dark and light current-voltage characteristics, time dependence of the dark current, and spectral photoresponse measurements. It is demonstrated that a thin (∼4 nm) undoped a-SiC:H buffer layer introduced between the p and i layers reduces the leakage current and improves the diode ideality factor. A dark current density of ∼10 pA/cm2 at reverse bias of 1 V was achieved for the n-i-p structure. Optimization of device design for further improvement of dark current and photoresponse is discussed.
Low Temperature Syntheses of Nano-crystalline Silicon Film and Si Nanorods by Hot-Wire CVD
Authors: Wong Te-Chi , Wu Jih-Jen 
Published: March 2017

AbstractLow-temperature growth of nano-crystalline silicon film and silicon nanorods by hot-wire chemical vapor deposition (HWCVD) using SiCl4/H2 gases are reported here. Nano-crystalline silicon films were deposited at a filament temperature of 1800°C, SiCl4/H2 flow rate ratio of 8/37 sccm and a substrate temperature of 150°C. The volume fraction of the crystallinity of the film characterized by Raman spectroscopy is 82%. The TEM analysis reveals that the average size of nano-crystalline silicon film is 5nm. Silicon nanorods with an average diameter of 80 nm were obtained as the SiCl4/H2 flow rate ratio was reduced to 5/30 sccm at substrate temperatures lower than 200°C. TEM analyses reveal that Si nanocrystals are embedded in an amorphous nanorods with fish-born like structure.
The DIVAM Filter: A NMR Signal Selection Method that is Tunable to Various Structural Domains Within Semicrystalline Materials
Authors: Hazendonk Paul , Montina Tony , Iuga Adriana , Wormald Philip 
Published: March 2017

AbstractThe selection mechanism in the Discrimination Induced by Variable Angle Minipulse (DIVAM) sequence as a domain filter is investigated using spin dynamics simulations. Experiments on poly(vinylidinefluoride) (PVDF) show that 19F DIVAM selects on the basis of relaxation and the chemical shielding anisotropy interaction, where the role of the latter was confirmed by the simulations. The DIVAM filter was applied in domain selective 13C{1H,19F} experiments on poly[bis(trifluoroethoxy)-phosphazene] (PBFP). The resulting spectra were sensitive to morphological changes in the crystalline domain, which was not previously observed with 19F and 31P methods.
Penetrant Diffusion in Triblock Polymer by Pulse-Field-Gradient NMR and Lattice Model Simulation
Authors: Kong Xueqian , Hargrove Tabitha , Ouellette Sara , Giotto Marcus V. , Aucoin Darryl , Lin Gouxing , Jones Alan A. 
Published: March 2017

AbstractThe three versions of poly-styrene-ethylene/butylene-styrene (SEBS) triblock copolymers under investigation have different micro-scale morphologies: polystyrene (PS) spheres in poly-ethylene/butylene (EB) matrix, PS cylinders in EB matrix and EB cylinders in PS matrix. The diffusion phenomena of 2,2,4-trimethyl pentane (TMP) in SEBS probed with pulse field gradient NMR show distinct features related to the morphological characteristics. The micron scale size of grain boundaries may be obtained. In addition, the lattice model simulation was performed for the TMP diffusion in the membrane with spherical morphology.
Solid State NMR as A Probe of Inorganic Materials:Examples From Glasses and Sol-Gels
Authors: Guerry Paul , Carroll Donna L , Gunawidjaja Phillips N , Bhattacharya Prodipta , Carta Daniela , Pickup David M , Ahmed Ifty , Abouneel Ensanya , Thomas Pam A , Knowles Jonathan C , Newport Robert J , Smith Mark E. 
Published: March 2017

AbstractTo understand amorphous and structurally disordered materials requires the application of a wide-range of advanced physical probe techniques and herein a combined methodology is outlined. The relatively short-range structural sensitivity of solid state NMR means that it is a core probe technique for characterizing such materials. The aspects of the solid state NMR contribution are emphasized here with examples given from a number of systems, with especial emphasis on the information available from 17O NMR in oxygen-containing materials. 17O NMR data for crystallization of pure sol-gel prepared oxides is compared, with new data presented from In2O3 and Sc2O3. Sol-gel formed oxide mixtures containing silica have been widely studied, but again the role and effect of the other added oxide varies widely. In a ternary ZrO2-TiO2-SiO2 silicate sol-gel the level of Q4 formation is dependent not only on the composition, as expected, but also the nature of the second added oxide. Sol-gel formed phosphates have been much less widely studied than silicates and some 31P NMR data from xerogel, sonogel and melt-quench glasses of the same composition are compared. The effect of small amounts of added antibacterial copper on phosphate glass networks is also explored.
FMR Effects on Integrated Ferromagnetic Thin-film RF Inductors
Authors: Ni Weiping , Kim Jinsook , Kan Edwin 
Published: March 2017

AbstractFerromagnetic inductors with various geometries and permalloy thin film patterns were fabricated on the standard silicon substrate with a fully CMOS compatible process. The ferromagnetic resonance effects on the inductors were studied with the applied magnetic fields in different orientations. It showed that with the properly applied magnetic field, the ferromagnetic resonance for the patterned permalloy thin films can be pushed higher and the maximum quality factor for the ferromagnetic inductors can be improved. However, because the relative permeability decreases with increasing applied field, the trade-off between the effective inductance and the quality factor needs to be optimized for the practical designs.
Analysis of diagnostic laparoscopy in chronic right iliac fossa pain
Authors: Vaishnav Umesh , Patel Harshad S. 
Published: March 2017

Background: Chronic right iliac fossa pain with normal radiological and laboratory finding is common indication for diagnostic laparoscopy by general surgeon. Most common cause of chronic right iliac fossa pain is appendicitis. Laparoscopic appendectomy is commonly done in diagnostic laparoscopy if other cause is not found.Methods: Patients of all the age group and either gender, undergone diagnostic laparoscopy for chronic right iliac fossa pain longer than 3 months with normal radiological finding in the surgical department. Diagnostic and therapeutic role of laparoscope was assessed.Results: 83% patients were showing visible positive finding on diagnostic laparoscopy. On follow up after 1 month, 90% patients show reliving of pain.Conclusions: Diagnostic laparoscopy is minimal invasive surgical procedure. It is useful when other pathological and radiological investigations are inclusive.
Abdominal skin incision closure with non-absorbable sutures versus staples- a comparative study
Authors: Muthukumar Vamseedharan , Venugopal Sarveswaran , Subramaniam Sureeskumar 
Published: March 2017

Background: Bacterial smartness and innovations have clearly outsmarted and drained the antibiotic discovery pipelines of pharmaceutical brains throughout the globe. Postoperative infection is a major cause of antibiotic use. The aim of the study was to compare the effects of using non-absorbable suture materials and staples for abdominal skin incision closure in terms of the occurrence rate of surgical site infections, the level of comfort experienced by patient and the cosmetic acceptability of scar by the patient.Methods: A randomized control study conducted at the general surgical department of a tertiary hospital in Southern India. The final scores of the study in the categories of surgical site infection, pain and cosmesis were analyzed using Students t-test or Anova test.Results: The use of staples to close skin incision in laparotomy cases reduces surgical site infection, improves the perception of cosmetic appearance of scar to the patient and adds to the comfort of patient by reducing the pain experienced by the patient. The subgroup of population who may comprehensively benefit are patients below 40 years, middle and high socio economic status population, clean and clean contaminated surgeries where incision length is more than 5cm.Conclusions: The results of this study illustrated the fact that the use of staples in closure of skin incision in laparotomy case especially in selected subgroup of population significantly reduces the surgical site infection, hence slashing the use of antibiotics and in turn has the potential to reduce the incidence of antibiotic resistance.
Przemysł meblarski w Polsce i jego międzynarodowa pozycja konkurencyjna
Authors: Ulbrych Marta 
Published: March 2017

Zagadnienie międzynarodowej konkurencyjności ma kluczowe znaczenie we współczesnej gospodarce światowej. Przy tym coraz większą popularność zyskuje przekonanie, że o konkurencyjności gospodarki narodowej decydują jej poszczególne sektory, które tę konkurencyjność kształtują. Celem artykułu jest określenie pozycji konkurencyjnej polskiego przemysłu meblarskiego za pomocą analizy statystycznej. Przeprowadzone badania wskazują, że Polska jest jednym z najszybciej rozwijających się pod względem poziomu produkcji rynków meblarskich w Unii Europejskiej. Potencjał produkcyjny branży sytuuje Polskę na wysokiej pozycji zarówno wśród producentów, jak i eksporterów. Ponadto zagregowane dane potwierdzają poprawę pozycji konkurencyjnej polskiej branży meblarskiej w badanym okresie.
Impact of Innovative Financial Products on Financial Systems: Exchange Traded Products and the Polish Financial System
Authors: Marszk Adam 
Published: March 2017

Exchange Traded Products (ETPs) are one of the most recent and most rapidly developing financial products. As their assets grow they have an increasing impact on financial systems in many countries, including the USA, UK or Japan. Development of ETPs is linked with many opportunities and threats for the local financial systems. Their correct assessment is becoming more difficult due to the growing complexity of the available products, thus posing problems not only for the participants of the financial markets (including buyers and sellers of ETPs as well as intermediaries) but also for the supervising authorities. The main ETP development trends (e.g. size of the global assets under management) are outlined in this article. Structural changes are discussed in the context of their impact on both local and global financial systems. One of the key topics is the consequences of the changing landscape of the most popular type of ETP – Exchange Traded Funds (ETFs). Simple and safe physical ETFs are being replaced by complicated synthetic ETFs, significantly increasing possible risks for the holders of such products, for other entities involved in their creation and distribution, and, consequently, for the whole financial system. The last part of the article is devoted to the Polish perspective on this topic. It may be argued that in Poland the role of ETPs (even ETFs) is still marginal. ETPs can influence the Polish financial system, however, through a number of links between Polish and foreign financial institutions and markets. As a result, fast transmission of the future shocks caused by such products is increasingly more probable.