bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Chemical Solutions and Surface Wettability on the Stability of Advanced Porous Low-k Materials
Authors: Le Q. T. , Vereecke G. , Bertha A. , Kesters E. , Lux M. , Struyf H. 
Published: September 2011

ABSTRACTThis study focuses on the impact of chemical solutions (hydrogen fluoride and tetramethylammonium hydroxide) on the change in properties of advanced porous low-k films. It was shown that there is no preferential removal of methyl groups during the dissolution process. With regard to wetting agents, the presence of isopropyl alcohol or surfactant (polyoxyethylene ether and alkoxylated diol type) in HF solution slowed down low-k film etching. Complete removal of surfactant residual usually requires an additional rinsing step using a low-molecular weight alcohol such as isopropyl alcohol.
Room temperature sub-diffractional plasmon laser
Authors: Ma R.-M. , Oulton R. F. , Sorger V. J. , Bartal G. , Zhang X. 
Published: September 2011

ABSTRACTWe report plasmon lasers with strong cavity feedback and optical confinement to 1/20th wavelength. Strong feedback arises from total internal reflection of plasmons, while confinement enhances the spontaneous emission rate by up to 18 times.
Control of Materials and Interfaces in μc-Si:H-based Solar Cells Grown at High Rate
Authors: Sobajima Yasushi , Sada Chitose , Matsuda Akihisa , Okamoto Hiroaki 
Published: September 2011

ABSTRACTGrowth process of microcrystalline silicon (μc-Si:H) using plasma-enhanced chemicalvapor- deposition method under high-rate-growth condition has been studied for the control of optoelectronic properties in the resulting materials. We have found two important things for the spatial-defect distribution in the resulting μc-Si:H through a precise dangling-bond-density measurement, e. g., (1) dangling-bond defects are uniformly distributed in the bulk region of μc- Si:H films independent of their crystallite size and (2) large number of dangling bonds are located at the surface of μc-Si:H especially when the film is deposited at high growth rate. Starting procedure of film growth has been investigated as an important process to control the dangling-bond-defect density in the bulk region of resulting μc-Si:H through the change in the electron temperature by the presence of particulates produced at the starting period of the plasma. Deposition of Si-compress thin layer on μc-Si:H grown at high rate followed by thermal annealing has been proposed as an effective method to reduce the defect density at the surface of resulting μc-Si:H. Utilizing the starting-procedure-controlling method and the compress-layerdeposition method together with several interface-controlling methods, we have demonstrated the fabrication of high conversion-efficiency (9.27%) substrate-type (n-i-p) μc-Si:H solar cells whose intrinsic μc-Si:H layer is deposited at high growth rate of 2.3 nm/sec.
A Study of the Post-hydrogenation Passivation Mechanism of Crystallized Poly-Si Films
Authors: Luo Chong , Li Juan , Li He , Meng Zhiguo , Wu Chunya , Huang Qian , Shengzhi Xu , Kwok Hoi Sing , Xiong Shaozhen 
Published: September 2011

ABSTRACTThe roles of hydrogen plasma radicals on passivation of several kinds of crystallized poly-Si thin films were investigated using optical emission spectroscopy (OES) combined with Hall mobility, Raman spectra, and absorption coefficient spectra. It was found that different kinds of hydrogen plasma radicals are responsible for passivation of dissimilar poly-Si crystallized by different method. Radicals Hα with lower energy are mainly responsible for passivating the poly-Si crystallized by solid phase crystallization (SPC) whose crystallization precursor was made by plasma enhanced chemical vapor deposition (PECVD). Higher energy radicals H* are more effective in passivating defects left over by Ni in poly-Si crystallized by Metal Induced Crystallization (MIC). The highest energy radicals Hβ and Hγ are needed to passivate the defects in poly-Si crystallized by SPC but whose precursor was made by low pressure CVD (LPCVD).
Use of a-SiC:H multilayer transducers for detection of fluorescence signals from reactive cyan and yellow fluorophores
Authors: Louro P. , Vieira M. , Vieira M. A. , Costa J. , Fernandes M. , Karmali A. 
Published: September 2011

ABSTRACTThe transducer consists of a p-i’(a-SiC:H)-n/p-i(a-Si:H)-n heterostructures produced by PECVD and optimized for the detection of the fluorescence resonance energy transfer between fluorophores with excitation in the violet(400 nm) and emissions in the cyan (470 nm) and yellow (588 nm) range of the spectrum. The thickness and the absorption coefficient of the i’- and i- layers were tailored for cyan and yellow optical confinement, respectively in the front and back photodiodes acting both as optical filters. The devices were characterized through transmittance and spectral response measurements and under different electrical.To simulate the FRET pairs and the excitation light a chromatic time dependent combination of violet, cyan and yellow wavelengths was applied to the device. The generated photocurrent was measured under negative and positive bias to readout the combined spectra. The independent test signals were chosen in order to sample all the possible chromatic. Different wavelength backgrounds were also superimposed.Results show that under negative bias the phorocurrent signal presents eight separate levels each one assigned to the different polychromatic mixtures. If a blue background is superimposed the yellow channel is enhanced and the cyan suppressed while under red irradiation the opposite behavior occurs. So under appropriated steady state optical bias the sensor will detect separately the cyan and yellow fluorescence pairs. An electrical model, supported by a numerical simulation, gives insight into the transduction mechanism.
Copper Indium Diselenide thin films using a hybrid method of chemical bath deposition and thermal evaporation
Authors: Ornelas A R. Ernesto , Shaji Sadasivan , Arato Omar , Avellaneda David , Castillo Alan , Das Roy Tushar Kanti , Krishnan Bindu 
Published: September 2011

ABSTRACTCopper indium diselenide (CIS) based solar cells are one among the promising thin film solar cells. Most of the processes reported for the preparation of CIS directly or indirectly involve Se vapor or H2Se gases which are extremely toxic to health and environment. In this work, we report the preparation of CIS thin films by stacked layers of Glass/In/Se/Cu2Se and Glass/In/Se/Cu2Se/Se. For this, first indium (In) thin film was thermally evaporated on glass substrate on which selenium (Se) and copper selenide (Cu2Se) thin films were deposited sequentially by chemical bath deposition. Selenium thin films were grown from an aqueous solution containing Na2SeSO3 and CH3COOH at room temperature, triple deposition for 7, 7 and 10 min from consecutive baths. Copper selenide thin films were deposited at 35 °C for 1 hour from an aqueous bath containing CuSO4, Na2SeSO3 and NH4OH. Analysis of the X-ray diffraction patterns of the thin films formed at 400 °C from the precursor layer containing extra selenium layer showed the presence of chalcopyrite CuInSe2, without any secondary phase. Morphology of all the samples was analyzed using Scanning Electron Microscopy. Optical band gap was evaluated from the UV-Visible absorption spectra of these films and the values were 1.1 eV and 1 eV respectively for CIS thin films formed at 400 °C from the selenium deficient and selenium rich precursor layers. Electrical characterizations were done using photocurrent measurements. Thus preparation of a CuInSe2 absorber material by a non-toxic selenization process may open up a low cost technique for the fabrication of CIS based solar cells.
Surface Properties, Crystal Morphology, and Reactivity of La2Zr2O7-based Cathode Infiltrate in Solid Oxide Fuel Cells: A Theoretical Study
Authors: Mantz Yves A. 
Published: September 2011

ABSTRACTSelected properties of the lanthanum zirconate (La2Zr2O7, LZ) low-index faces, representing the first theoretical attempt to characterize the surfaces of a pyrochlore oxide, as well as oxygen (O2) interacting with LZ are predicted at the level of density-functional theory. All possible surface terminations formed by cleaving a perfect crystal are considered, as well as selected defective surfaces. After deriving the expression for the free energy of an LZ surface, surface free energies are computed. The most stable surfaces are identified, and it is suggested how to refine the ratios of surface free energies for comparison to experimental results obtained by the analysis of x-ray diffraction (XRD) patterns. The interaction of O2 with selected faces is examined. A strong dependence of the binding energy on surface oxygen content is predicted.
Electrical Through-Hole and Planar Interconnect Generation in Roll-to-Roll LED Lighting Manufacturing using Industrial Inkjet Printheads
Authors: Reinhold Ingo , Thielen Moritz , Voit Wolfgang , Zapka Werner , Götzen Reiner , Bohlmann Helge 
Published: September 2011

ABSTRACTDespite the availability of many high-volume and low-cost manufacturing processes for LED-based lighting applications, relying mainly on fixed patterns such as LED-backlights and RGB-pixelated displays, novel applications, such as “mood lighting” or interior wall displays call for more complicated and shaped LED arrangements. The presented work is based of a novel roll-to-roll (R2R) process to adaptively and cost-efficiently generate LED arrangements on RMPD® substrates.Inkjet printing of planar and though-hole electrical interconnections is of high importance to the process, as it provides a fully digital way of interconnecting devices electrically, accounting for the actual position of the component and spatially provide different ink film thicknesses.Xaar’s industrial inkjet printheads are used to dispense defined volumes of 50 pL of a silver nanoparticle ink in order to provide high reliability and good positioning accuracy while main-taining low satellite drop densities. Specific printing strategies are investigated at a print speed of 0.1 m/s to allow for a reliable electrical connection in case of up to 50 μm deep via connections to the buried component.Due to the low glass-transition nature of the underlying substrates, low sintering tempera-tures are required to preserve the mechanical properties of the substrate. Low temperature oven sintering yielding sufficient conductivity to drive a current of 40 mA will be discussed.
Magnetic and dielectric properties study of cobalt ferrite nanoparticles synthesized by co-precipitation method
Authors: Krishna Surendra M. , Kannan D. , Ramachandra Rao M. S. 
Published: September 2011

Abstract:Cobalt ferrite nanoparticles were prepared by co-precipitation method and were heat treated at 100 oC, 200 oC, 400 oC and 600 oC for 2 h to increase the particle size. Phase purity of samples was confirmed by X-ray diffraction. Scherrer formula calculations showed crystallite size varied from 12 to 24 nm when heated from 100 oC to 600 oC. Transmission electron microscopy reveals a uniform and narrow particle size distribution about 12 nm for as-prepared cobalt ferrite particles. Room temperature saturation magnetization was found to vary from 40.8 to 67.0 emu/g as the particle size increased from12 nm to 24 nm. Increase in saturation magnetization with increase in particle size was attributed to the presence of magnetic inert layer on the surface of nanoparticles. Inert layer thickness calculated at 10 K and 300 K was 6 Å and 11 Å respectively. The dielectric properties ε’, tanδ, Z and θ have been studied as a function of frequency and particles size. For the 12 nm grain size, the dielectric constant is one order higher than that of bulk cobalt ferrite. Increase in the grain size showed an increase in the dielectric constant. The increase in the conductivity with grain size is mainly due to the grain size effects. The present study shows that the dielectric properties can be tailor-made to suit the requirement of a particular application by controlling the grain size.
High Rate Deposition of High Quality ZnO:Al by Filtered Cathodic Arc
Authors: Mendelsberg Rueben J. , Lim Sunnie H.N. , Milliron Delia J. , Anders André 
Published: September 2011

ABSTRACTHigh quality ZnO:Al (AZO) thin films were prepared on glass substrates by direct current filtered cathodic arc deposition. Substrate temperature was varied from room temperature to 425°C, and samples were grown with and without the assistance of low power oxygen plasma (75W). For each growth condition, at least 3 samples were grown to give a statistical look at the effect of the growth environment on the film properties and to explore the reproducibility of the technique. Growth rate was in the 100-400 nm/min range but was apparently random and could not be easily traced to the growth conditions explored. For optimized growth conditions, 300-600 nm AZO films had resistivities of 3-6 x 10-4 Ωcm, carrier concentrations in the range of 2-4 x 1020 cm3, Hall mobility as high as 55 cm2/Vs, and optical transmittance greater than 90%. These films are also highly oriented with the c-axis perpendicular to the substrate and a surface roughness of 2-4 nm.
Effective Medium Analysis of Plasmonic Silver Nanoparticle Films
Authors: Santbergen Rudi , Sap Jeroen , Temple Tristan , Solntsev Serge , Smets Arno HM , van Swaaij René , Zeman Miro 
Published: September 2011

ABSTRACTFilms of silver nanoparticles have optical properties that are useful for applications such as plasmonic light trapping in solar cells. We illustrate experimentally and by means of simulations how the particle shape affects the optical properties. In addition we show that these nanoparticle films can be represented by an effective medium layer with an almost identical reflectance and transmittance. The Bergman effective medium theory that we used provides a link between the nanoparticle shape and the optical properties. This insight can be used for the optical analysis of nanoparticle films and for further optimization of plasmonic solar cells.
EXPLORING THE LIMITS OF PHOSPHOR-BASED SPECTRAL MANAGEMENT FOR PHOTOVOLTAIC APPLICATIONS
Authors: Magsi Komal , Lee Rose , Shank Jason , Kang Yeona , Fortmann C.M. 
Published: September 2011

AbstractA detailed analysis of photovoltaic front surface phosphor-based spectral modification and light scattering by hetero-structure was conducted. Phosphor based spectral downconversion is a well known laser technology. The analysis assumes that both sunlight energy and photovoltaic performance are at peak sunlight photon flux within the spectral range. Further, the analysis presented here indicates that parasitic losses and light scattering within the spectral range are large enough to offset any expected gains. For example, analysis of up-conversion phosphor-based approaches indicates that these are likely to suffer unexpectedly large losses in the peak spectral region due to parasitic absorption when attempting to down convert UV light.
Thermal Annealing Effect on P3HT:PCBM Free Polarons Lifetime and Charge Transport
Authors: Li Kejia , Shen Yang , Li Lijun , Khlyabich Petr , Reifler Ellen S. , Thompson Barry C. , Campbell Joe C. 
Published: September 2011

ABSTRACTA transient response technique has been employed to investigate the lifetime of free polarons in bulk heterojunction blends of regioregular poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methylester (PCBM) at different annealing temperatures. Device efficiency and charge mobility were also measured. The longest lifetime, ∼ 1.5 microseceonds, was achieved for an annealing temperature of 140˚C; this represents a 2.5 x increase in lifetime relative to unannealed samples. The 140˚C annealing temperature also yields the highest efficiency. These measurements provide an estimate of the mobility-lifetime product, a figure of merit for charge transport in organic bulk heterojunctions.
Growth of AZO on flexible substrate using ALD system as a transparent conducting oxide for solar cells
Authors: Dhakal Tara , Nandur Abhishek , Christian Rachel , Vanhart Daniel , Vasekar Parag , Westgate Charles R. 
Published: September 2011

ABSTRACTAluminum doped zinc oxide (AZO) thin film is gaining momentum as a transparent conducting oxide because its optical and electrical properties are optimal for a photovoltaic device. We report growth of AZO thin film using an Atomic Layer Deposition (ALD) system, which is known to deposit layers on a substrate with atomic layer precision. The precursors used for aluminum and zinc were Trimethylaluminum (TMA) and Dimethylzinc (DMZ) respectively. Alternating cycles of TMA and DMZ were introduced to the heated deposition chamber such that a desired aluminum doping was obtained on the AZO films grown. The films were grown on flexible substrates like PET and also on single crystalline Si(100) and float-glass substrates. An optimal aluminum doping (3 at.%) on the AZO film of thickness 575 nm gave a sheet resistance (Rs) of 97 Ω/□ with corresponding resistivity of 5.6 x 10-3 Ω.cm. The value of the carrier concentration and hall mobility were 1.86 x 1020 cm-3 and 6.5 cm2V-1s-1 respectively. Optical measurement showed 90% transmission in most of the visible spectrum. X-ray diffraction spectra of the film showed all characteristic ZnO hexagonal lattice peaks.
Influence of dopant nature on the TCO properties of ZnO:M (M=Al, Ga, Sn, Si, Ge) thin films
Authors: Clatot J. , Campet G. , Jean M. , Nistor M. , Rougier A. 
Published: September 2011

ABSTRACTAiming at clarifying the opto-electronic properties of ZnO based n-type Transparent Conducting Oxides, TCOs, properties of ZnO thin films are studied as a function of cationic doping. In addition to commonly reported, Al and Ga trivalent dopant, similar performances are reported for Si doping. In the visible region, ZnO:Si (3 %) thin film exhibit a transmittance higher than 80 % for a resistivity as low as 8x10-4 Ω.cm when grown at 100 °C under 1.0 Pa oxygen pressure. The influence of tetravalent cations as dopant is also investigated through Sn and Ge additions. It shows that not only the oxidation state plays a role but also the cation nature. Indeed, ZnO:Sn thin films are insulating whereas the ZnO:Ge thin films are conductive with resistivity values higher than the ones of ZnO:Si thin films.
Simulation of Symmetrically Doped Silicon Nanowire Solar Cells
Authors: Voigt Felix , Stelzner Thomas , Christiansen Silke H. 
Published: September 2011

ABSTRACTSilicon nanowire solar cells were simulated using the Silvaco TCAD software kit. For optimization of speed the simulations were performed in cylinder coordinates with cylindrical symmetry. Symmetric doping was assumed with a dopant density of 1018 cm-3 in the p-type core and inside the n-type shell. In the implementation a cathode contact was wrapped around the semiconductor nanorod and an anode was assumed at the bottom of the rod. Optimization of cell efficiency was performed with regard to the rod radius and the rod length. In both optimization processes clear maxima in efficiency were visible, resulting in an optimal radius of 66 nm with the pn junction at 43.5 nm and an optimal rod length of about 48 μm. The maximum of efficiency with respect to the rod radius is due to a decrease of short-circuit current density (Jsc) and an increase of open-circuit voltage (Uoc) with radius, while the maximum with respect to the rod length is explained by the combination of an increase of Jsc and a decrease of Uoc. Fill factors stay rather constant at values between 0.6 and 0.8. Further, the influence of a back surface field (BSF) layer was surveyed in simulations. Positioning the BSF next to the cathode contact considerably improved cell efficiency. In addition, simulations with a cathode contact on top of the nanowire structure were undertaken. No severe deterioration of cell performance with increasing radius was observed so far in this configuration. Hence, nanorods with much larger radii can be used for solar cells using this contact scheme. In comparison to simulations with wrapped cathode contacts, Jsc and Uoc and therefore efficiency is considerably improved.
Diameter Dependent Current-Voltage Characteristics of InSb Nanowires
Authors: Penchev Miroslav , Zhong Jiebin , Lin Jian , Ozkan Cengiz S. , Ozkan Mihrimah 
Published: September 2011

ABSTRACTSingle crystalline Indium Antimonide (InSb) nanowires were synthesized by chemical vapor deposition (CVD) technique, using gold (Au) nanoparticles as catalyst, via a vapor liquid solid mechanism. Structural properties of the as-grown InSb nanowires were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Nanowire field effect transistors (NWFETs) were fabricated in back-gate configuration, on Si/SO2 substrates, using SiO2 as gate insulator. The diameter of InSb nanowires used in the fabricated devices varied from 15-80 nm. Current-voltage measurements were conducted to determine the dependence of NWFETs parameters on the InSb nanowire diameter. Carrier mobility was shown to decrease with decrease of nanowire diameter. Temperature dependen current-voltage measurements were conducted to determine the effect of operating temperature on the InSb NWFET device performance.
Functionalization and Environmental Stabilization of ZnO Nanobridge Sensors Fabricated using Carbonized Photoresist
Authors: Mason Ashley D. , Huang Chien-Chih , Koesdjojo Myra T. , Stephon Nate D. , Remcho Vincent T. , Conley John F. 
Published: September 2011

ABSTRACTZnO nanobridge sensors were selectively grown and electrically connected using lithographically patterned carbonized photoresist (C-PR). As ZnO is known to dissolve in deionized (DI) water, parylene-A was investigated as a moisture barrier and potential functionalization platform. A chemical vapor deposition (CVD) process for parylene-A was developed and it was demonstrated that parylene-A coated ZnO NWs do not show any signs of dissolution after 24 hours in an aqueous solution. The impact of the parylene-A coating on the electrical performance and sensitivity of ZnO nanobridge devices was investigated. A comparison of UV, O2, and H2O sensitivity between uncoated and coated devices revealed that a thin coating of parylene-A attenuated all of these responses, suggesting the ability to modulate environmental sensitivity using this non-covalently bound polymer passivation layer.
Electrochemical performance of anodized TiO2Nanotubes for rechargeable Lithium Batteries
Authors: Prasada Rao R. , Kangle L. , Adams S. , Reddy M.V. , Chowdari B.V.R. 
Published: September 2011

ABSTRACTThe electrochemical storage performance of anatase TiO2nanotubes (NT) is compared to the performance of TiO2nanotubes covered by sulfur. Charge/discharge curves and cycling performance of TiO2NT with and without sulfur deposition with respect to lithium anodes are demonstrated in electrochemical test cells. At 0.5C cycle rate the TiO2NT exhibited a first cycle specific charge/discharge capacity of 180/155 mAh/g, whereas the TiO2NT deposited with sulfur showed a remarkably higher performance at 0.5C cycle rate with first cycle charge/ discharge specific capacities of 258/260 mAh/g and a coulombic efficiency of 98%.
5MeV Si Ion Modification on Thermoelectric SiO2/SiO2+Cu Multilayer Films
Authors: Smith C. , Budak S. , Jordan T. , Chacha J. , Chhay B. , Heidary K. , Johnson R. B. , Muntele C. , ILA D. 
Published: September 2011

AbstractWe prepared samples by electron beam physical vapor deposition EB-PVD followed by ion bombardment. The samples were than characterized by photoluminescence (PL), x-ray photoelectron spectroscopy (XPS). PL was used to characterize the available energy states. XPS was used to determine the binding energies. The ML’s are comprised of 100 alternating layers of SiO2/SiO2+Cu.