bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single crystallization of Ba8AlxSi46-x clathrate by using the flux Czochralski method
Authors: Nakakohara Yusuke , Mugita Naoki , Nagatomo Yuya , Saisho Makoto , Motooka Teruaki , Teranishi Ryo , Munetoh Shinji 
Published: September 2011

ABSTRACTWe have synthesized single crystalline Ba8AlxSix-46 clathrates by using the flux Czochralski (CZ) method with Al-rich melt. The specific electric resistivity, the Seebeck coefficient and the power factor of single crystalline Ba8Al14Si32 were 0.73 mΩcm,70.0μV/K and 6.8×10-4 V2/K2Ωm, respectively. These values are higher than that of single crystalline Ba8Al12Si34 clathrate because of the reduced carrier concentration. It is indicated that Al contents and the carrier concentration of single crystalline Ba8AlxSi46-x can be controlled by using the flux Czochralski method.
Piezoelectric Materials and Devices for Wind Energy Harvesting
Authors: Lake John , Luan Jiyuan , Tanaka Zuki , Liang Bin , Chen Bin 
Published: September 2011

AbstractWe present materials development in fabricating thin film devices for the conversion of wind energy as a sustainable energy source. We demonstrate the feasibility of piezoelectric polymer thin film devices to harvest wind energy in a miniature wind tunnel. Using an example of prototype device based on polyvinylidene fluoride (PVDF) thin film devices, we are able to obtain electrical power from the wind’s energy through the mechanical deformation of PVDF, such as that obtained from the films flapping in the wind. We have obtained a preliminary result of 1 mW power (at 15 mph wind) with a single layer of PVDF of 4 x 2 inches and 50 μm in thickness sandwiched between two thin gold electrode films. Additionally, the fracturing of metallic electrodes over time from the induced strain of this application lead to the significance of examining carbon nanotubes as compliant electrodes offering better mechanical properties while maintaining necessary electrical properties.
Power Generation Efficiency with Extremely Large Z factor Thermoelectric Material
Authors: Yazawa Kazuaki , Shakouri Ali 
Published: September 2011

ABSTRACTA recently developed generic model of a thermoelectric power generation system suggests a promising future for cost effective and scalable power generation. The model is based on co-optimizing the thermoelectric module together with the heat sink. Using this model, efficiency at maximum output power is calculated. It is shown that this approaches the Curzon-Ahlborn limit at very large Z values which is consistent with thermodynamic systems with irreversible heat engines. However, this happens only when the thermal resistances of the thermoelectric device with hot and cold heat sinks exactly match. For asymmetrical thermal resistances, the efficiency at maximum output power is different. This is consistent with the very recent results for the thermodynamic engines. Finally, we study the impact of lowering the thermal conductivity of the thermoelectric material or increasing its power factor and how these affect the performance of the thermoelectric power generation system.
Photonic Crystal Fiber for Efficient Raman Scattering of Thiol-Capped Quantum Dots in Aqueous Solution
Authors: Mak Jacky S. W. , Farah Abdiaziz A. , Chen Feifan , Helmy Amr S. 
Published: September 2011

ABSTRACTA novel hollow-core photonic crystal fiber platform was used for the first time to observe clear vibrational modes of the CdTe core, CdS0.7Te0.3 interface, and carboxylate-metal complexes in dilute aqueous CdTe quantum dot (QD) solutions. These modes demonstrate the presence of crystalline cores, defects and surface passivation responsible for photoluminescent efficiency and stability. In addition, 3-mercaptopropionic acid (MPA)-capped QDs show higher crystallinity and stability than those capped with thioglycolic acid (TGA) and 1-thioglycerol (TG). This detailed, non-destructive characterization was carried out using Raman spectroscopy for solutions with QD concentration of 2 mg/mL, which is similar to their concentration during synthesis process. This platform can be extended to the in-situ studies of any colloidal nanoparticles and aqueous solutions of relevant biological samples using Raman spectroscopy.
Make Carbon nanotube-polymer composite thin: application to water quality
Authors: Villeneuve C. , Pacchini S. , Dilhan M. , Colin D. , Brouzes A. , Boulanger P. , Plana R. 
Published: September 2011

ABSTRACTThis paper reviews our works about the development of thin composite film based on aligned carbon nanotubes (CNT) forest, embedded in epoxy or PMMA polymer matrix, in order to fabricate membranes dedicated to water purification issue. Indeed, the small internal radius of nanotubes, the smoothness of their inner core and the hydrophobic properties of its interna surface induce remarkable flowing properties for water molecules. In this article, thinnin technology process is investigated to obtain composite film with opened CNT. Different etching techniques as grinding, Chemical Mechanical Polishing (CMP) and isotropic plasma O2ar investigated in term of etching rate and membrane roughness, using AFM and SEM characterizations. Results show CMP process in lapping configuration permits to obtain agreement between high etching rate and membrane roughness. Moreover, to improve water flowing through membrane, O2plasma treatment is used to remove polymer residue spread over CNT. Joint use of lapping and plasma treatment permits to obtain 35μm-thick nanoporous membrane with well-opened protruding nanotubes.
Fabrication of Novel Hollow Micro Needles for Biological Applications
Authors: Sanaee Z. , Mehrvarz S. , Mehran M. , Abdolahad M. , Sohrabi M. , Mohajerzadeh S. 
Published: September 2011

ABSTRACTMicroneedles have applications in drug delivery and biotechnology. We report a novel needle-like hollow cylindrical structure as a base for the growth of carbon nanotubes (CNT) to form a cage-like structure. The formation of hollow microneedle structures is feasible on Si-membranes using proper patterning of the masking layer and combined by a deep reactive ion etching. The formation of highly featured structures at micro and nanometric scale is reported. By controlling the etching parameter one is able to achieve three-dimensional as well as highly vertical structures on silicon substrates. The growth of carbon nanotubes on such structures allows the realization of cage-like carbon-based features which could be suitable for gas and liquid transport.
Block Co-polymer on Graphene: Doping of Graphene and a Robust Chemical Sensor
Authors: Guo Shirui , Ghazinejad Maziar , Ozkan Cengiz S. , Ozkan Mihrimah 
Published: September 2011

ABSTRACTIt is essential to control the electronic properties of a graphene field effect transistor (GFET). And the ability to accurately control the intrinsic electrical transport properties and to locally change the carrier density will be significant for graphene devices. We succeeded in achieving and controlling the Dirac point (neutrality point) simply by doping block co-polymer (BCP) covered GFET with CF4 plasma. By exposing polymer covered GFET to CF4 plasma for a short time the electronic transport was altered significantly. The hexagonal structure of BCP produces patterns with nanoscale spacing for heterogeneous patterns which provides a new approach to tune the electron and the hole conductivity simultaneously. Exploitation of fluorine doping provides a general route to control electronic property of any polymer coated GFET. The BCP protected GFET could detect 1mM NaF solution in “dry” condition in 60s. The sensing property demonstrates that BCP protected GFET could be a good candidate for stable and sensitive chemical or biological sensor. Furthermore, the distinct property of two functional groups within BCP facilitates the selective sensing property. These findings pave the way for developing more stable and sensitive sensors under ambient conditions.
Comparisons and analyses on heterostructures consisting of ZnO and different ferroelectric films
Authors: ZHANG Nai-wen , JIA Ze , ZHANG Ming-ming , REN Tian-ling 
Published: September 2011

ABSTRACTTwo different types of ferroelectric/semiconductor heterostructures, made up of Pb(Zr,Ti)O3/ZnO and BiFeO3/ZnO respectively, were fabricated on Pt(111)/Ti/SiO2/Si(100) by sol-gel process. Obvious diodelike behavior were observed in BiFeO3/ZnO heterostructures when current-voltage characteristics were measured, while Pb(Zr,Ti)O3/ZnO heterostructures exhibited a symmetrical behavior. It is found that Pb(Zr,Ti)O3/ZnO heterostructures showed a large polarization and the remnant polarization was approximately 15μC/cm2. The remnant polarization performed a modulation on the channel resistance. The different properties of two heterostructures might lead to different applications.
Probing the metal gate high k interactions by backside XPS and C-AFM
Authors: Celano U. , Conard T. , Hantschel T. , Vandervorst W. 
Published: September 2011

ABSTRACTThe metal gate high k interaction is one of the dominant processes influencing the electrical performance (Vt, charge accumulation,..) of advanced gate stacks. These interactions are influenced by the entire thermal budget and the presence of reactive elements (on top/ within the material gate) such that relevant measurements can only be performed after a full processing cycle and on a complete gate stack.In such cases the relevant metal gate high k interface is a buried interface located below the metal gate (+ Si cap) and is not accessible for standard characterization methods like x-ray photoemission spectroscopy (XPS) due the limited escape depth of the photoelectrons. Moreover the presence of a conductive metal gate prevents the application of techniques such as conductive atomic force microscopy (C-AFM), to probe the local distribution of the defects, trapping sites and local degradation upon stressing. XPS in combination with layer removal steps like ion beam sputtering will destroy the bonding information and is thus not applicable. Chemical etching of the metal gate stack prior to the XPS measurements requires an extremely precious control of the etching in order to stop 1-2 nm before the high k metal interface.As an alternative we have developed a backside removal approach, that allows us to investigate using techniques such as XPS and C-AFM, the metal gate high k interface.
Planar Non-Volatile Memory based on Metal Nanoparticles
Authors: Kiazadeh A. , Gomes H. L. , Da Costa A. R. , Rocha P. , Chen Q. , Moreira J. A. , De Leeuw D. M. , Meskers S. C. J. 
Published: September 2011

ABSTRACTResistive switching properties of silver nanoparticles hosted in an insulating polymer matrix (poly(N-vinyl-2-pyrrolidone) are reported. Planar devices structures using interdigitated gold electrodes were fabricated. These devices have on/off resistance ratio as high as 103 , retention times reaching to months and good endurance cycles. Temperature-dependent measurements show that the charge transport is weakly thermal activated (73 meV) for both states suggesting that nanoparticles will not aggregate into a metallic filament.
Immobilization of oligonucleotide-functionalized magnetic nanobeads in DNA-coils studied by electron microscopy and atomic force microscopy
Authors: Strömberg Mattias , Akhtar Sultan , Gunnarsson Klas , Russell Camilla , Herthnek David , Svedlindh Peter , Nilsson Mats , Strømme Maria , Leifer Klaus 
Published: September 2011

ABSTRACTImmobilization of oligonucleotide-functionalized magnetic nanobeads by hybridization in DNA-coils formed by rolling circle amplification has been investigated using transmission electron microscopy (TEM) and atomic force microscopy (AFM). The TEM results supported earlier made observations that small beads with low oligonucleotide surface coverage preferably immobilize in the interior of the DNA-coils and do not tend to link several DNA-coils together whereas large beads with high surface coverage to a larger extent connect several DNA-coils together to clusters of several DNA-coils with beads. AFM provided direct visualization of the DNA-coils as thread-like objects. DNA-coils with immobilized beads appeared as a collection of beads with thread-like features in their near vicinity.
Effect of the Cross-Linking with Calcium Ions on the Structural and Thermo-Mechanical Properties of Alginate Films
Authors: Vidal Urquiza Turner K. , Perales Pérez O. , Gálvez Saldaña M. 
Published: September 2011

ABSTRACTThe present research discusses the thermal and structural properties of calcium alginate films synthesized by cross linking precursor sodium alginate films with Ca2+ ions. Raman and FTIR spectroscopy analyses evinced the interchange of Na ions with Ca ions. Both techniques revealed a shift of the COO- vibration modes; the symmetrical COO- peak of calcium alginate exhibited a shift towards higher wavenumber (∼14 cm−1) from 1415 cm−1 to 1429 cm−1 in the Raman spectra. TGA and TMA analyses performed under a nitrogen atmosphere revealed that increasing the Ca-molarity and immersion time resulted in an increase in the glass transition temperature (Tg) and the strain deformation of the Ca-alginate film. The increase in Tg can be attributed to the Ca-cross-linking that could restrict the molecular response to temperature change whereas the increased strain could be due to the enhanced entrapment of water between the molecular chains of the polymer.
CdSxTe1-x Alloying in CdS/CdTe Solar Cells
Authors: Duenow Joel N. , Dhere Ramesh G. , Moutinho Helio R. , To Bobby , Pankow Joel W. , Kuciauskas Darius , Gessert Timothy A. 
Published: September 2011

ABSTRACTA CdSxTe1-x layer forms by interdiffusion of CdS and CdTe during the fabrication of thinfilm CdTe photovoltaic (PV) devices. The CdSxTe1-x layer is thought to be important because it relieves strain at the CdS/CdTe interface that would otherwise exist due to the 10% lattice mismatch between these two materials. Our previous work [1] has indicated that the electrical junction is located in this interdiffused CdSxTe1-x region. Further understanding, however, is essential to predict the role of this CdSxTe1-x layer in the operation of CdS/CdTe devices. In this study, CdSxTe1-x alloy films were deposited by radio-frequency magnetron sputtering and coevaporation from CdTe and CdS sources. Both radio-frequency-magnetron-sputtered and coevaporated CdSxTe1-x films of lower S content (x<0.3) have a cubic zincblende (ZB) structure akin to CdTe, whereas those of higher S content have a hexagonal wurtzite (WZ) structure like that of CdS. Films become less preferentially oriented as a result of a CdCl2 heat treatment at ∼400°C for 5 min. Films sputtered in a 1% O2/Ar ambient are amorphous as deposited, but show CdTe ZB, CdS WZ, and CdTe oxide phases after a CdCl2 heat treatment. Films sputtered in O2 partial pressure have a much wider bandgap than expected. This may be explained by nanocrystalline size effects seen previously [2] for sputtered oxygenated CdS (CdS:O) films.
Properties of CuIn1-xGaxSe2 films prepared by the rapid thermal annealing of spray-deposited CuIn1-xGaxS2 and Se
Authors: Slaymaker Laura E. , Hoffman Nathan M. , Ingersoll Matthew A. , Jensen Matthew R. , Olejníček Jiří , Exstrom Christopher L. , Darveau Scott A. , Soukup Rodney J. , Ianno Natale J. , Sarkar Amitabha , Kment Štěpán 
Published: September 2011

ABSTRACTMany reported CuIn1-xGaxSe2 (CIGS) thin films for high-efficiency solar cells have been prepared via a two-stage process that consists of a high-vacuum film deposition step followed by selenization with excess H2Se gas or Se vapor. Removing toxic gas and high-vacuum requirements from this process would greatly simplify it and make it less hazardous. We report the formation of CuIn1-xGaxSe2 (x = 0, 0.25, 0.50, 0.75, 1.0) thin films achieved by rapid thermal annealing of spray-deposited CuIn1-xGaxS2 and Se in the absence of an additional selenium source. To prepare the Se layer, commercial Se powder was dissolved by refluxing in ethylenediamine/2,2-dimethylimidizolidine. After cooling to room temperature, this mixture was combined with 2-propanol and the resulting colloidal Se suspension was sprayed by airbrush onto a heated glass substrate. The resulting film was coated with nanocrystalline CuIn1-xGaxS2 via spray deposition of a toluene-based “nanoink” suspension. The two-layer sample was annealed at 550 oC in an argon atmosphere for 60 minutes to form the final CIGS product. Scanning electron microscopy images reveal that film grains are 200-300 nm in diameter and comparable to sizes of the reactant CuIn1-xGaxS2 nanoparticles. XRD patterns are consistent with the chalcopyrite unit cell and calculated lattice parameters and A1 phonon frequencies change nearly linearly between those for CuInSe2 and CuGaSe2.
Site Selective Magneto-Optical Studies of Eu ions in Gallium Nitride
Authors: Woodward Nathaniel , Nishikawa Atsushi , Fujiwara Yasufumi , Dierolf Volkmar 
Published: September 2011

ABSTRACTWe report site-selective studies of the Zeeman splittings that are observed for magnetic fields up to 6.6T for different Eu incorporation sites in GaN. Utilizing resonant excitation with visible light, we are able to distinguish the site and find for one center (Eu1) a splitting into five components as expected for C3v symmetry. The corresponding g-values are 1.66 and 1.90. The two lines of another center Eu2 each split into two levels corresponding to g-values of 1.9 and 2.84. Most surprisingly a third center, for which only one line is clearly identified, a g-value of 6.16 is found which is larger than can be explained for a 7F2 purely ionic Eu state.
Materials Characterization of CIGS solar cells on Top of CMOS chips
Authors: Lu J. , Liu W. , Kovalgin A. Y. , Sun Y. , Schmitz J. 
Published: September 2011

ABSTRACTIn the current work, we present a detailed study on the material properties of the CIGS layers, fabricated on top of the CMOS chips, and compare the results with the fabrication on standard glass substrates. Almost identical elemental composition on both glass and CMOS chips (within measurement error). From X-ray diffraction measurement, except two peaks from the Si <100> substrate, the diffraction peaks from CIGS solar cell CMOS chip and that on glass substrate coincide for all three temperatures. Helium ion microscope images of the cross-section and top view of the CIGS layers, shows that the grain size is suitable for high efficiency solar cells.
Development of a High-Durability Silver Mirror Coating System
Authors: Hashimoto Satoru , Hirano Teruyoshi O. , Okitsu Osamu , Kim Tae-Youb , Maeda Shuichi 
Published: September 2011

ABSTRACTA high-quality silver mirror coating technology capable of offering various colors for the decoration of molding items is desirable. We have developed both chemical reagents and procedures for improving the silver mirror coating layers. Treatment A with a sodium thiosulfate aqueous solution is a cleaning process for the silver layers. Treatment B with a water-based solution of silane coupling agent is a process for improving the adhesion property of mirror coating layers. Both treatments improve the durability of the silver mirror coating.
Effect of Substrate Temperature on Hardness and Transparency of SiOC(–H) Thin Films Synthesized by Atmospheric Pressure Plasma Enhanced CVD Method
Authors: Noborisaka Mayui , Nagashima So , Hayashi Hidetaka , Ueda Naoharu , Kumagai Kyoko , Shirakura Akira , Suzuki Tetsuya 
Published: September 2011

ABSTRACTSilicon-based films have gained much interest as protective coatings for transparent polymeric materials. In this study, SiOC(–H) thin films were deposited on polycarbonate (PC) or Si substrates from trimethylsilane (TrMS) gas diluted with He gas by atmospheric pressure plasma enhanced CVD (AP-PECVD) method with varying substrate temperature, and transparency and hardness of the films were investigated. The films exhibited a good optical transparency with an optical transmittance of about 90% irrespective of the substrate temperature, and the hardness increased from 0.6 to 1.3 GPa as the substrate temperature increased from 60 to 140°C. The results are discussed in terms of chemical structural changes in the films according to the substrate temperature.
Improvement of the power conversion efficiency of polymeric solar cells based on P3HT:PCBM through interfacial modification
Authors: Zheng Shizhao , Deng Xianyu , Wong King Y. 
Published: September 2011

ABSTRACTWe report the study of a process which enhances the power conversion efficiency (PCE) of solar cells employing poly(3-hexythiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM). In this process, the spin-coated solution of the active material was maintained in the liquid state for a prolonged duration. It was observed that through this process, the PCE of the device was enhanced by 31% for the case of a fast-grown film. It also provided a further 19% enhancement on top of the enhancement obtained by the familiar solvent annealing process. We found that this process depends critically on the presence of a poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) buffer layer. It is hypothesized that the action of this enhancement process involves the interfacial interactions between P3HT and PEDOT polymers.
Pt-CdS/TiO2 nanotube catalyst for photocatalytic reduction of CO2 with water under visible light irradiation
Authors: Yuan Jian , Zhang Chuanzhao , Li Caolong , Chen Mingxia , Shangguan Wenfeng 
Published: September 2011

ABSTRACTTitanate nanotube (TNT) was prepared by alkaline hydrothermal method starting from TiO2 (P25), and then CdS-TNT was prepared for visible light harvesting by immersing TNT in Cd(CH3COO)2 and then (NH2)2CS aqueous solutions subsequently and heat treated at specialtemperature. After loading with Pt, photocatalytic reduction of gas phase CO2 with water vapor was carried out under UV-VIS and visible light irradiation. The results showed that the main reaction products were CH4, C2H4, C2H6 and H2, which were online characterized by gaschromatography when the flow rate of 5000 ppm CO2 is 0.35 ml/min. The hydrogenation process also realized under visible light illumination for Pt-CdS/TNT and producted 0.44 μmol/min CH4. The maximum yield of methane reached about 130 μmol/min when Pt-CdS/TNTwas irradiated with UV-Vis light. The time profile for production yield increased steadily with time up to about 6–7 h, then a decrease of the reaction rate occurred. It is suggested that thadsorption of intermediate products CO, O2 etc. on Pt and the oxidation of Pt might be the reasons for the photocatalytic reaction deterioration.
Specific contact resistance of ohmic contacts to n-type SiC membranes
Authors: Mohd Nasir N.F. , Holland A.S. , Reeves G.K. , Leech P.W. , Collins A. , Tanner P. 
Published: September 2011

ABSTRACTMembranes of epitaxial SiC have been used as a means of eliminating the leakage current into the Si substrate during circular transmission line model (CTLM) measurements. In the n+-3C-SiC/Si wafers, the Si substrate was etched in a patterned window with dimensions up to 10 mm × 15 mm2. An array of CTLM metal contacts was then deposited onto the upper surface of the n+-SiC membrane. The CTLM contacts on the membrane have shown an ohmic current/voltage response while electrodes located on the adjacent substrate were non-ohmic. Values of ρc were measured directly on the membranes. These results have shown a significant increase in the current flow below the metal contacts due to the presence of the Si substrate.