bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of Durability in Silicon Nitride Barrier Films for Flexible OLED Displays under High Temperature and High Humidity Conditions
Authors: Akedo Kunio , Miura Atsushi , Noda Koji , Fujikawa Hisayoshi 
Published: April 2011

AbstractWe have developed a new silicon nitride (SiNx) multilayer barrier film by a plasma-enhanced chemical vapor deposition (CVD) for a flexible organic light emitting diode (OLED), which consists of SiNx films in two different deposition conditions, that is, a transparent SiNx layer (tr-SiNx) deposited with NH3 gas and an ultra-thin SiNx layer (cap-SiNx) deposited without NH3 gas, which caps over the former layer. This barrier film is expected to exhibit high durability under high temperature and high humidity conditions even at high deposition rate over 100 nm / minute, because the transparent SiNx layer, that is easily oxidized under such conditions, is protected by the cap-SiNx layer and the interface between them, and also show good transparency, because the opaque cap-SiNx layer is enough thin to be almost transparent to visible light. Thus, the multi-layer SiNx barrier film indicates the specific features as a high barrier performance, high transparency, and high productivity, and makes it possible to apply flexible OLED displays to automobile use.
Large Area Carbon Nanotube Films
Authors: Konesky Gregory 
Published: April 2011

AbstractCarbon nanotube films can be used in a wide range of applications, from fuel cells, storage batteries, and super-capacitors, electron field emitters for displays, x-ray and beam sources, heat sinks and heat spreaders, and chemically robust filtering membranes, to name a few. Present approaches to carbon nanotube film production rely on filtration of a suspension, but creating this suspension requires the use of toxic and hazardous reagents and lengthy processing times. We describe an approach of uniaxial die pressing that incorporates a sacrificial layer to prevent binding of the carbon nanotube film to the compression surfaces. Water, or other solvents, acts as a release agent. No binder is used. The process is scalable in terms of film thickness and area. Development of an extrusion process employing these principles is described.
Patterning Submicron Features on Flexible Plastic Substrates by Optical Lithography
Authors: Péter Mária , de Laat Wim , Giesen Peter T. M. , Gui Cheng-Qun , Meinders Erwin R. 
Published: April 2011

AbstractManufacturing transistors on thin flexible polymer foils is challenging and differs from standard Si processing due to the dimensional instability of the substrate influenced by moisture uptake, temperature and handling. A thorough analysis of material properties of the tested foil was performed to understand its behavior during lithography and subsequently to improve the processing. Imaging experiments on 100 µm polyethylene naphthalate (PEN) foils were performed with a PAS 5500/100D ASML step and repeat I-line (365 nm) system equipped with reticles having features of several microns and also sub-micrometer dimensions. A foil lamination process was developed to improve the dimensional stability during processing and to achieve a good surface flatness crucial for sub-micrometer imaging. The optimum process window for sub-micrometer critical dimensions was determined by performing a Focus Exposure Matrix (FEM) experiment in which the energy and focus were increased stepwise. The optimum imaging conditions were derived from SEM analysis. The results indicated a reproducible and good patterning accuracy for making patterns below 1µm size.
Environmental Passivation and Temperature Cycling of PCBM - Polymer Solar Cells
Authors: Anctil Annick , Merrill Andrew , Cress Cory , Landi Brian , Raffaelle Ryne 
Published: April 2011

AbstractIn the present work, polymer solar cells were fabricated from composite blends of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly(3-hexylthiophene)-(P3HT with PCBM[60] and PCBM[70]. The composite blends were used as active layers in an ITO/PEDOT:PSS/active layer/Al device structure. Power conversion efficiencies have been measured from current-voltage (I-V) measurements for each of these different composite blends under simulated AM1.5 illumination. In the case of the MEH-PPV devices, the I-V performance has been measured as a function of polymer molecular weight, type of fullerene derivative (C60 or C70), and PCBM:polymer ratios. The highest efficiencies for the ranges used in this study were obtained using the 150,000 g/mol MEH-PPV molecular weight, the C70 PCBM derivative, and a 1:4 MEH-PPV:PCBM ratio. The effect of thermal cycling on the I-V performance for both MEH-PPV and P3HT devices has also been measured from 77K to 330K. The devices exhibited a positive temperature coefficient for the short-circuit current density (Jsc), which dominated the overall efficiency of the device over this temperature range. Finally, the use of a combination of parylene and polymethylmethacralate for device passivation was shown to provide a dramatic reduction in device degradation under ambient conditions as compared to non-passivated devices.
Determination of Nanomaterial Energy Levels for Organic Photovoltaics by Cyclic Voltammetry
Authors: DiLeo Robert Ann , Anctil Annick , Landi Brian , Cress Cory , Raffaelle Ryne P 
Published: April 2011

AbstractA wide variety of nanomaterials and associated nanomaterial/polymer composites are being developed in an effort to produce higher efficiency organic solar cells. This development requires a fundamental understanding of the energy levels for the individual materials, and their composites, to enable device designs which posess appropriate energy level matching. Cyclic voltammetry (CV) allows for the determination of the band gaps (Eg) and energy levels of these various nanomaterials and composites by measuring their oxidation and reduction potentials. These potentials correspond to a given material's ionization potential (IP) and electron affinity (EA), respectively. The results for the EA, IP, and Eg have been determined by CV for derivatized fullerenes and CdSe quantum dots (QD), measured in isolation, and in conjugated polymer composites with MEH-PPV. In addition, CV measurements conducted under dark and illuminated conditions were used to investigate the relationship between energy levels within the composites.
Thermal Dependence of Quantum Dot Solar Cells
Authors: Cress Cory , Hubbard Seth M. , Bailey Christopher , Robinson Ross , Landi Brian J. , Raffaelle Ryne P. 
Published: April 2011

AbstractVarious temperature dependent optoelectronic properties were measured for GaAs-based p-type / intrinsic / n-type (pin) solar cell devices containing 5-layers of InAs quantum dots (QDs) grown with strain-compensation layers. Curve fitting of the dark diode characteristics allowed for the temperature dependence of the saturation current and the ideality parameter to be determined. The resulting parameter values indicate high material quality. Air mass zero illuminated current density vs. voltage measurements were used to determine the temperature coefficients of the open circuit voltage, short circuit current, maximum power, and fill factor. A strong correlation between the temperature dependent quantum dot electroluminescence peak emission wavelength and the sub-GaAs bandgap spectral response was observed.
Electrophoretic Deposition of CdSe Nanocrystals for Photovoltaic Applications
Authors: Smith Nathanael , Emmett Kevin J , Rosenthal Sandra J 
Published: April 2011

AbstractCdSe nanocrystals chemically linked to nanocrystalline titanium dioxide substrates form a promising material for nanostructured photovoltaic devices. The usual method for attaching the nanocrystals to the titanium dioxide substrate is by means of a linking molecule (such as mercaptopropionic acid) or in-situ growth. In this paper, we report the use of an alternative technique, electrophoretic deposition (EPD), to directly deposit already formed CdSe nanocrystals onto the substrate. In EPD, a voltage is established between two electrodes that are immersed in a solution of nanocrystals. At room temperature, a fraction of the nanocrystals are thermally charged, and these charged nanocrystals migrate to the electrodes and adhere to the surface. A significant advantage of EPD over the use of linking molecules is the speed with which the nanocrystals are deposited: EPD takes only a few minutes, compared to the several hours required for the alternative techniques. Additionally, we have fabricated initial photovoltaic devices based on electrophoretically deposited CdSe nanocrystals on a planar TiO2 thin film.
Novel spin-dimer system of a microporous polyborate NaCuB7O12.nH2O
Authors: Ju Jing , Sasaki Juns , Toyota Naoki , Tanigaki Katsumi 
Published: April 2011

AbstractA new microporous polyborate, NaCuB7O12.nH2O, is synthesized using boric acid as a flux. It contains a 14-membered ring framework built up by CuO6 octahedra, BO4 tetrahedra and BO3 triangles. The spin-1/2 dimers of Cu2+ ions are connected by BO3 to form an infinite ladder along the b-axis. Magnetic susceptibility data between 2 and 330 K are presented, and the data are accurately fitted by theoretical predictions of Bleaney-Bowers for the spin-1/2 dimer, with J/kB = -153.8 K, and g = 1.98, where J is the intradimer exchange interaction constant and g is the Landé g factor.
Magnetic Spin Valve Sensors with Different Geometry to Magnetic Bead Detection for Biosensor Application
Authors: Suh Jeong Dae , Chung Myung Ae 
Published: April 2011

AbstractWe have demonstrated the use of highly sensitive spin valve sensors for the detection of micron magnetic beads. By using a ring type, cross type, and meander line type sensors, we were able to detect the presence of 2.8 μm size magnetic beads in real time by direct measurement of magnetic dipole fields from magnetic beads. The sensitivity of the ring, cross and meander line sensors were obtained about 50 μV/Oe, 7 μV/Oe, 30 μV/Oe and sensor output signals of 50 μV , 30 μV, 90 μV were obtained in an external applied field of 10 Oe and 1 mA sense current. Our results shows that ring, cross, and meander line shape spin valve sensors are very promising candidates for the detection of biomolecules with magnetic labels.
Vertically Aligned Mn-doped Fe3O4 Nanowire Arrays: Magnetic Properties and Gas Sensing at Room Temperature
Authors: Hwang Seon Oh , Kim Chang Hyun , Myung Yoon , Park Seong-Hun , Park Jeunghee , Hahn Chang Soo , Kim Jae-Young 
Published: April 2011

AbstractVertically-aligned Mn (10%)-doped Fe3O4 (Fe2.7Mn0.3O4) nanowire arrays were produced by the reduction/substitution of pre-grown Fe2O3 nanowires. These nanowires were ferromagnetic with a Verwey temperature of 129 K. X-ray magnetic circular dichroism measurements revealed that the Mn2+ ions preferentially occupy the tetrahedral sites, substituting for the Fe3+ ions. We observed that the Mn substitution decreases the magnetization, but increases the electrical conductivity. We developed highly sensitive gas sensors using these nanowire arrays, operating at room temperature, whose sensitivity showed a correlation with their bond strength of diatomic/triatomic molecules. Based on the fact that the sensitivity was highest toward water vapor, an excellent-performance humidity sensor was fabricated.
Biomedical Engineered Ferrofluids
Authors: Fischer Birgit , Mao Leidong , Gungormus Mustafa , Tamerler-Behar Candan , Sarikaya Mehmet , Koser Hur 
Published: April 2011

AbstractThe characteristic of combining liquid behavior with and magnetic properties makes ferrofluids unique and it provides them a variety of applications, in particular in the medial field. For medical application ferrofluids are required to be stable at neutral pH and against high salt concentration. Here we present a new approach to stabilize water-based ferrofluids by using genetically engineered peptides for inorganics (GEPI's). Such GEPI's selected for specific and strong binding to the surface of nanoparticles not only increase colloidal stability by acting as a thin surfactant, but they also enable an efficient route for rendering the ferrofluid bio-functional and bio-compatible. The stability of a ferrofluid was characterized by the ac-susceptibility and by using it in a ferro-microfluidic device. This chip actuates the ferrofluid directly via magnetic fields alone, and the pumping spectrum as a function of frequency reveals information about the size of the magnetic nanoparticles. An ideal ferrofluid with monodisperse particles displays a single and clear pumping peak. Agglomeration can directly be observed as a broadening of the pumping spectrum.
Preparation of Lateral Organic Spin-valve Devices with La0.7Sr0.3MnO3
Authors: Ikegami Tomonori , Kawayama Iwao , Tonouchi Masayoshi , Yamashita Yoshiro , Tada Hirokazu 
Published: April 2011

AbstractSpin injection and transport characteristics of low-molecular-weight organic semiconductors such as pentacene and bis(l,2,5-thiadiazolo)-p-quinobis(l,3-dithiole) (BTQBT) have been studied utilizing lateral type spin-valve devices with half metal electrodes, LaA0.67Sr0.33MnO3 (LSMO). The LSMO electrodes with a spacing of 200 nm were prepared by electron-beam lithography and dry etching of the epitaxial films grown on MgO substrates. The devices showed clear spin-valve behaviors with a magneto-resistance (MR) ratio up to 29 % at 9.1K. It was found that the MR ratio depended on the crystallinity of organic films as well as on temperature and applied bias voltages
Effect of 3d Transition Metals Addition on the Ferroelectric Properties in Bi Ferrite Thin Films
Authors: Naganuma Hiroshi , Miura Jun , Okamura Soichiro 
Published: April 2011

AbstractCr, Mn, Co, Ni and Cu of 5 at % s added BiFeO3 films were fabricated by chemical solution deposition on 111-textured Pt/Ti/SiO2/Si(100) substrates. Only the diffraction peaks attributed to BiFeO3 structure could obtain except the Ni and Cr additions. The BiFeO3 films became almost amorphous by adding Ni, and non ferroelectric Bi7CrO12.5 phase was formed by adding Cr. AFM images indicated the surface morphology of the films was drastically changed by the additives. The leakage current was reduced by adding Mn, Cu and Co, although the electric coercive field increased in the case of Co addition. Therefore, it could be concluded that Mn and Cu additives improved not only the leakage current properties but also the ferroelectric properties in the course of CSD process. It should be noted that this is the first report showing the improvement of ferroelectricity of BiFeO3 films by adding Cu.
Epitaxial Growth of Spinel Ferrite Oxide (Al,Ru,Fe)3O4 on a GaAs(001) Substrate Using a MgO Buffer Layer
Authors: Kanki Teruo , Kawahara Toshio , Asakawa Naoki , Hotta Yasushi , Terai Yoshikazu , Fujiwara Yasufumi , Tabata Hitoshi , Kawai Tomoji 
Published: April 2011

AbstractSpinel ferrite oxides doping non-magnetic ions show the photo-induced magnetization (PIM) effect at high temperature [1-3]. Such a magnetization enhancement by light irradiation is a unique property in this material. In order effectively to use the PIM effect and precisely to control the magnetism, direct light-emission from light-emitting element substrates would be a useful technique. In this study, spinel ferrite Al0.2Ru0.8Fe2O4 (ARFO) thin films, with the high temperature PIM effect, were prepared on GaAs(001) substrates by a pulsed laser deposition technique to aim integration with light-emitting devices based on GaAs lattice-matched materials in the future. Results showed that (001)-oriented ARFO thin films were successfully grown by using MgO buffer layers. The magnetic properties were approximately the same as ARFO films using other substrates such as Al2O3(0001) or MgO(001).
Synthesis and Characterization of Multiferroic Composites Based on Manganate Perovskite Ceramics
Authors: Song Gonbao , Li Jian , Kholkin Andrei 
Published: April 2011

AbstractIn this paper, phase separation and crystal structure of (x) La0.625Sr0.375MnO3 − (1-x) LuMnO3 system (LSMO-LMO), and (1-x) La0.9Ca0.1MnO3-(x) LuMnO3 system (LCMO-LMO) were studied by XRD and SEM. The results confirm that there are solid solutions in both of these two systems. There is a solid solution of monoclinic phase of space group P1121/a for x=0.980∼1.0 in LSMO-LMO system. There is a solid solution of hexagonal phase of space group P63cm for x=0.0∼0.24 in LCMO-LMO. Selected compositions were tested in terms of their magnetization, dielectric constant and ferroelectric properties at low temperatures.
Dielectric Properties of Ba0.5Sr0.5TiO3-P(VDF-CTFE) Nanocomposites
Authors: Wu Peixuan , Shan Xiaobing , Cheng Zhong-yang 
Published: April 2011

AbstractCeramic/polymer composite made of nanosize Ba0.5Sr0.5TiO3 (BST) powders and P(VDF-CTFE) copolymers as matrix. The concentration of the composites with BST from 0% to 50% in volume was investigated. The dielectric properties and structure as well as the morphology of the composites were characterized over a broad temperature range. It is found that the wetability between the polymer and ceramic powder is not good. The approach to improve the uniformity of composites was investigated. Due to the dielectric-constant-maximum temperature of the BST is different from that of copolymer, a weak dependence of the dielectric constant on temperature was observed over temperature from 10 °C to 100 °C.
Synthesis of the Ferroelectric Solid Solution, Pb(Zr1−xTix)O3 on a Single Substrate Using a Modified Molecular Beam Epitaxy Technique
Authors: Anderson Piers , Guerin Samuel , Hayden Brian E. , Khan Mikael A. , Bell Andrew J. , Han Yisong , Pasha Ashu , Whittle Karl R , Reaney Ian M. 
Published: April 2011

AbstractHigh-throughput synthesis of the ferroelectric solid solution Pb(Zr1−xTix)O3 (PZT) on single Pt/Ti/SiO2/Si substrates was demonstrated using a modified molecular beam epitaxy (MBE) system. The PZT films exhibited a phase transition from rhombohehdral (R) to tetragonal (T) symmetry as a function of Zr:Ti ratio, across the substrate diagonal. This was consistent with the presence of a morphotropic phase boundary (MPB) at a Zr:Ti ratio of 0.64:0.36, different from the value of 0.53:0.47 observed for bulk ceramics. All points on the films exhibited ferroelectric hysteresis loops. The results demonstrate the feasibility of high-throughput MBE for deposition of complex ferroelectric oxides, and pave the way for further materials discovery, in particular Pb-free piezoceramics.
Comparative Study of Thin PZT Sol-gel Films Deposited on Pt and GaN Substrates
Authors: Chevtchenko Serguei A. , Agra Francisco A. , Xie Jinqiao , Morkoç Hadis 
Published: April 2011

AbstractWe provide a comparative study of the piezoresponse in thin Pb(ZrxTi1−x)O3 (PZT) films deposited onto GaN/sapphire and Pt/Ti/SiO2/Si substrates using the sol-gel process. The effective piezoelectric coefficient was measured by Piezoresponse Force Microscopy. The resulting effective piezoelectric coefficient obtained for PZT(∼180 nm)/GaN/sapphire structure is 16.7 ± 3.4 pm/V and for PZT(∼180 nm)/Pt/Ti/SiO2/Si structure is 7.8 ± 0.8 pm/V. We also discuss the substrate clamping effect of both structures and explain the relatively stronger piezoresponse of PZT on GaN by different orientation of films formed on the two types of substrates. In this investigation, the PZT thin films crystallized with preferred (100) and (110) orientations on platinum and GaN, respectively. The phase mode of the Piezoresponse Force Microscopy was used to demonstrate remanent polarization in PZT/GaN/sapphire structure.
Growth and Evaluation of Magnetoelectric Cr2O3 Single Crystal Thin Films
Authors: Iwata Nobuyuki , Asada Takeshi , Ootsuki Shunpei , Yamamoto Hiroshi 
Published: April 2011

AbstractThe Cr2O3 thin films were grown on Al2O3(1102)(r-cut sapphire), Al2O3(1120)(a-cut sapphire), and Al2O3(0001)(c-cut sapphire) substrates to apply magnetoelectric oxides to oxides electronics. The Cr2O3 is a representative magnetoelectric material with antiferromagnetic insulator with the Néel temperature of 308 K. From the results of X-ray diffraction and the reflection high energy electron diffraction, epitaxial Cr2O3 thin films were obtained on all cut sapphire substrates using off-axis DC-RF magnetron sputtering method. The epitaxial relationship was Cr2O3[1120]//Al2O3[1120] and Cr2O3(1102)//Al2O3(1102) on r-cut, and Cr2O3[1100]//Al2O3[1100] and Cr2O3(1120)//Al2O3(1120) on a-cut, and Cr2O3[1120]//Al2O3[1120] and Cr2O3(0001)//Al2O3(0001) on c-cut. Optimized Cr2O3 film was obtained grown at 600°C on c-cut sapphire substrate. The surface roughness (Ra) of the film was 0.28 nm, and full width at half maximum of rocking curve for Cr2O3(0006) Bragg reflection was 0.23°. Growth difference is expected to be caused by the stacking order of atoms normal to the substrate surface and arrangement of atoms of the substrate surface.
Evidence of different conduction channels in bulk ZnO using f-MEMSA Analysis of transport properties
Authors: Tavares Chevalier Celine , Rothman J. , Feuillet G. 
Published: April 2011

AbstractThe characterization of transport properties in Zn0 is known to be challenging, particularly due to surface (in the case of bulk) or interface (in the case of heteroepitaxial layers) conduction channels, which puts severe limitations on the interpretation of Hall Effect measurements. In this communication, we report on the study of transport properties of n-type ZnO bulk material using Hall mobility spectrum analysis estimated through the algorithm known as full Maximum Entropy Mobility Spectrum Analysis, f-MEMSA. The electrical properties of bulk Zn0 are measured using a Hall setup for applied magnetic fields µ0H in the range 0T-9T and for temperatures between 50K and 400K. The f-MEMSA analysis highlights the existence of two types of conduction channels in the considered ZnO substrate. We also show that surface conductive channel can be suppressed using appropriate annealing conditions.
Role of Neutral Impurity Scattering in the Analysis of Hall Data from ZnO and Other II-VI Materials
Authors: Yang Xiaocheng , Xu Chunchuan , Giles N. C. 
Published: April 2011

AbstractTo determine donor and acceptor concentrations affecting electrical properties in ZnO crystals, the relaxation time approximation (RTA) has been used to analyze mobility and carrier concentration data measured from 80 to 400 K. Five scattering mechanisms are included: polar-optical-phonon, piezoelectric potential, deformation potential, ionized impurity, and neutral impurity scattering. Temperature dependences of intrinsic mobilities and Hall r factors are determined. Neutral impurity (ni) scattering can play an important role in limiting the total mobility in ZnO single crystals. By including ni scattering, the experimental deformation potential E1 = 3.8 eV for ZnO can be used, rather than treating E1 as a fitting parameter. This approach yields “intrinsic” mobilities for n-type and p-type ZnO, and other II-VI materials. At 300 K, the intrinsic electron Hall mobility in ZnO is predicted to be 230 cm2/Vs. The results of fitting the temperature dependences of mobility and carrier concentrations from representative ZnO and CdSe bulk samples are shown. Intrinsic results for n-type CdS and ZnS will also be discussed. The 300-K intrinsic hole Hall mobility in ZnO is predicted to be about 50 cm2/Vs.