bluuebunny/crossref_metadata_2025_split huggingface dataset:
A next generation TCO Material for display systems: Molybdenum doped Indium oxide thin films
Authors: Elangovan E. , Marques A , Martins R , Fortunato E 
Published: April 2011

ABSTRACTThin films of indium molybdenum oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of sputtering power (ranging 40 – 180 W) and sputtering time (ranging 2.5 – 20 min). Thickness of the films found varied between 50 – 400 nm. The films were characterized for their structural (XRD), electrical (Hall measurements) and optical (Transmittance spectra) properties. XRD studies revealed that the films are amorphous for the sputtering power ≤ 100 W and deposition time ≤ 5 min. All the other films are polycrystalline and the strongest refection along (222) plane showing a preferential orientation. A minimum bulk resistivity of 2.65 × 10−3 Ω-cm and a maximum carrier concentration of 4.16 × 1020 cm−3 have been obtained for the films sputtered at 180 W (10 min). Whereas maximum mobility (19.5 cm2 V−1 s−1) has been obtained for the films sputtered at 80 W (10 min). A maximum visible transmittance of 90 % (500 nm) has been obtained for the films sputtered at 80 W (10 min) with a minimum of 27 % for those sputtered at 180 W. The optical band gap of the films found varying between 3.75 and 3.90 eV for various sputtering parameters.
A Study of Oxygen Reduction of Tin- or Zinc-doped Indium Oxide (ITO or IZO) Film Induced by Deposition of Silicon Nitride Film in PECVD Process
Authors: Kim Byoung-June , Choi Youn-Mo , Girotra Kunal , Yang Sung-Hoon , Kim Shi-Yul , Lim Soon-Kwon , Souk Jun-Hyung 
Published: April 2011

ABSTRACTIn the thin film transistor fabrication process, tin doped indium oxide (ITO) or zinc doped indium oxide (IZO) film can be easily exposed to hydrogen-containing plasma during the deposition of silicon nitride (SiNx) film. By this exposure, ITO or IZO can be easily reduced into its corresponding metallic element such as indium, which degrades the optical transmittance and the conductivity. In this study, SiNx was deposited onto ITO or IZO film, and the oxygen reduction of ITO or IZO during PECVD SiNx deposition was analyzed to clarify this phenomenon. The oxygen reduction during PECVD SiNx deposition is mainly induced by decomposed NH3 gas. However, the progress of ITO reduction is different from that of IZO reduction, due to the different atomic composition of In2O3 in the composite and the different critical temperature of reduction initiation between indium oxide, tin oxide, and zinc oxide.
Synthesis and self-assembly of photopolymerizable quarterthiophenes
Authors: Garcia Margarita , Meijer E.W. , Schenning Albertus 
Published: April 2011

ABSTRACTA variety of α, α'-subtituted quaterthiophenes containing ester, amide and polymerizable side chains have been synthesized and fully characterized. The self-assembly properties of these oligothiophenes were studied as function of the side chain. Introduction of amide functionalities highly promotes the self-assembly via π-stacking and hydrogen bond interactions, while the lack of amides prevent aggregate formation. Initial experiments show that by introducing a sorbyl moiety as a polymerizable group it is possible to achieve covalent fixation of the oligothiophene units in the self-assembled state.
Application of Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) for Analysis of Novel Organic Semiconductor Materials
Authors: Shcherbyna Svitlana , Bohme Diethard K. , Baranov Vladimir I. 
Published: April 2011

ABSTRACTICP-MS is a well established analytical technique in the semiconductor industry for essential trace metal characterization in chemical reagents and silicon wafers. Tetracene, Antracene, Pentacene and Rubrene are among the most interesting organic semiconductors for use in molecular electronic devises such as single-crystal Organic Field Effect Transistors (OFETs). One of the most important parameter for fabrication of single-crystal OFETs is the purity of the starting material. As the crystal growth process also results in the chemical purification of the material, several re-growth cycles may be required for improving the field-effect mobility, with the grown crystals used as the starting material for the subsequent re-growth. The number of required re-growth cycles depends strongly on the purity of starting material. We report the application of ICP-MS for impurity analysis in the organic semiconductors. The ICP plasma, where samples are atomized and ionized, generates strong ion current, which is instrumental in achieving exceptional detection limits. Some elements can be measured down to part per trillion range. This study can provide a better characterization of the trace metal impurities in starting material.
Charge Injection into Bottom-Contact Pentacene Thin-Film Transistors
Authors: Hong Yi , Yan Feng , Migliorato Piero , Han S H , Jang Jin 
Published: April 2011

ABSTRACTWe investigate the contact of bottom-contact pentacene-based thin-film transistors, with Au source/drain electrode. By separating the voltage drop at the contact from the source-drain voltage, the current-voltage characteristic of the injection contact is obtained. The contact characteristics are in a good agreement with a model of carrier injection from a metal electrode into a disordered hopping system.
Polymer Gate Dielectrics for High Performance Organic Field-Effect Transistors
Authors: Yildirim Faruk Altan , Meixner Ronald , Schliewe Robert Roman , Bauhofer Wolfgang , Goebel Holger , Krautschneider Wolfgang 
Published: April 2011

ABSTRACTSolution-processed bottom-gate organic field-effect transistors (OFET) with different dielectric materials were produced and characterized. As the active semiconductor layer, regioregular poly(3-hexylthiophene) (rr-P3HT) was used. In addition to the dielectrics which have been reported in literature, various other materials with simple processing conditions were used as gate-dielectrics. Also, the dielectric properties of the polymeric layers were investigated in metal-insulator-metal capacitor structures, where the thicknesses of the films were exactly the same as they were in the OFETs. The specific volume resistivity and dielectric constant values determined were then used to explain the electrical behavior of OFETs. The devices having BCB, SU-8 and NOA74 as the dielectric layers exhibited the desired transistor characteristics, whereas the transistors with Avatrel dielectric did not, due to higher gate-leakages. As a result, SU-8 and NOA74 resins were proven to be good candidates for gate-dielectric usage in solution-processed all-polymer OFETs.
Copper Phthalocyanine Single-crystal Field-effect Transistors Stable Above 100°C
Authors: Yamada Koichi , Takeya Jun , Shigeto Kunji , Tsukagoshi Kazuhito , Aoyagi Yoshinobu , Iwasa Yoshihiro 
Published: April 2011

ABSTRACTIntrinsic charge transport of copper phthalocyanine single-crystal field-effect transistors is measured as function of temperature up to above 100°C. The conduction of the accumulated carriers shows hopping-type transport, so that the field-effect mobility increases with temperature following activation-type temperature dependence throughout the measured temperature region. Due to excellent material stability at the high temperature, the mobility values are precisely reproduced after the heat cycles.
Long n-Alkane Adlayers as Templates for Tailoring Supramolecular Self-Assemblies on Surfaces
Authors: Piot Luc , Marchenko Alexandr , Wu Jishan , Müllen Klaus , Fichou Denis 
Published: April 2011

ABSTRACTIn this paper we report the heteroepitaxial growth and the structural evolution of hexakis-dodecyl-peri-hexabenzocoronene (HBC-C12) adsorbed on a template monolayer (n-C50H102). STM measurements at the liquid/solid interface made it possible to follow in real time the early stage of deposition of the HBC-C12 molecules. Additionally, molecule manipulations were realized using the tip of the STM. Our measurements give direct evidence of two successive phase transitions occurring in the upper HBC monolayer weakly bonded to the underlying template layer.
Nonvolatile Carbon Nanotube Memory Device With Molecular Charge Storage
Authors: Sorger Volker J. , Yao Zhen 
Published: April 2011

ABSTRACTNanoscale, non-volatile, multi-bit memory devices have been fabricated consisting of carbon nanotube field-effect transistors (CNT-FETs) surrounded by redox active molecules (cobalt porphyrin). Charge was stored in the cobalt center atom of the molecule. Write and erase programming was carried out with back-gate pulses. By varying the back-gate amplitude multi-level memory operation was achieved. Programmed devices were read at zero gate voltage showing distinct logic ON and OFF states at room temperature for several hours. At low temperatures strong increase in retention time was observed and single-electron sensitivity was demonstrated. Charge stability tests show insignificant device change after 105 write and erase cycles.
A Novel Non-destructive Interfacing Technique for Molecular Scale Switching Junctions
Authors: Johns Chad , Kimukin Ibrahim , Islam M. Saif , Ohlberg Doug A. A. , Donley Carrie , Stewart Duncan R. , Wang Shih-Yuan , Williams R. Stanley 
Published: April 2011

ABSTRACTCharacterization of molecular scale electronic devices generally involves deposition of a metal top electrode onto an organic film. During the evaporation process, high energetic granules of metals may lead to unwanted reactions between the organic molecules and deposited top electrodes. This can cause, as commonly reported, lasting damage which leaves most junctions either short or open. To overcome this important issue of physical damage to the molecules, we developed a novel technique of interfacing molecules by laying prefabricated metallic electrodes on top of a monolayer of molecules. For the bottom electrode a monolayer of cadmium stearate ((C17H35COO)2Cd) was deposited, using the Langmuir-Blodgett technique, onto platinum (Pt) electrodes which further rested on 200nm of oxide used for isolation. A separate set of Aluminum (Al) electrodes were fabricated on a different oxide free, highly doped substrate and was gently placed on the cadmium stearate monolayer in room ambient. Conduction to the top electrode was accomplished by probing the backside of the highly doped wafer whereas the bottom electrodes were individually addressed. Pressure was applied to ensure firm contact between the molecules and the top electrodes. Preliminary results showed an observed switching voltage of 3.5V. Most of the devices with Al as the top electrodes exhibited a gradual progression from switching on the positive side, closing, and then switching towards the negative side.
The Explanation of Interfacial Property in Liquid Lens with Multilayer System: Molecular View
Authors: Shim Jihye , Park Sung Soo , Kim Jong Yun , Jung Hayong , Bae Jae Young 
Published: April 2011

ABSTRACTIn order to design liquid lens which works in a severe environment such as high temperature and high humidity, several layered liquid systems are investigated. Especially, the change of the interface between conducting and non-conducting liquid layers has been traced by using empirical molecular dynamics simulation and density-functional theory calculation. The stability of the liquid layers at high temperature was evaluated by simulation results such as the density profile of liquid components, their distribution near the interface, the interface thickness and chemical reactivity between them, which depends on the molecular species consisting of liquid and their concentrations. We found that the organic solvent including halogen atoms, alkyl halide, easily penetrates into conducting liquid layer and reacts with its substances, which is added to increase refractive index and density of non-conducting liquid. We also presented an optimized solution including the minimum organic solvent and satisfying the requisites for an optical device.
Morphology Study of a Hybrid Structure Based on Porous Silicon and Polypyrrole
Authors: Arenas Ma. Concepcion , Hu Hailin , del Río J. Antonio , Nicho M. E. 
Published: April 2011

AbstractDouble layer structures of porous silicon (PS) and polypyrrole (PPy) were prepared in order to study their electrical properties. PS was prepared by electrochemical etching in a HF/Ethanol solution from n-type silicon wafer and PPy by galvanstatic method in a lithium perchlorate/monomer solution. The experimental parameters for preparation of PS and PPy were varied to obtain different morphology of the PS/PPy structures. The surface topography of these structures was analyzed by Atomic Force Morphology (AFM). Tip- and agglomerate-like morphologies of PPy were obtained on PS layers with different pore diameters. The electrical and AFM characterization of PS were studied with and without PPy. Current-voltage (I-V) curves of PS/PPy structures were obtained in dark and under illumination. PS without PPy shows an exponential behavior in the current ((+)Al/n-Si/PS/Cu(-)), but it is almost linear when the PPy layer is deposited over the PS layer ((+)Al/n-Si/PS-PPy/Cu(-)). All structures present photovoltage under illumination conditions. However, this parameter is smaller in Al/n-Si/PS-PPy/Cu structure than Al/n-Si/PS/Cu. The open circuit voltage (VOC) and short circuit current density (JSC) of these structures decrease when the surface morphology of PPy is tip-like, but JSC increase when the surface morphology of PPy is agglomerate-like.
Nitride and Oxide Based Nanowires Grown by Plasma-Assisted Molecular Beam Epitaxy
Authors: Kendrick Chito E , Carder Damian , Miller Pual , Reeves Roger J. , Tilley Richard , Durbin Steven M. 
Published: April 2011

ABSTRACTThe growth of nanostructured material continues to attract attention for a number of applications, including highly sensitive gas sensors (due to the increased surface area), and photonic crystals (which require arrays of nanostructures). Even though nanostructures can be formed through self-assembly, they often do not possess the high crystal quality of those grown using vapour liquid solid (VLS) techniques; also, with VLS the feature size and placement can be easily controlled. To achieve VLS growth, however, several parameters have to be considered specific to the material of interest. In this study, we examine VLS growth of both InN (infrared) and ZnO (ultraviolet) nanostructures.
Domain Structures and Current-Controlled Switching Characteristics of Micron Sized Permalloy Structures with Varying Aspect Ratio
Authors: Seah S. C. , Soh Y S , Ng V 
Published: April 2011

ABSTRACTPermalloy magnetic structures were fabricated using electron beam lithography and then deposited by evaporation followed by lift-off. The structures were studied for their magnetic domain properties with respect to their aspect ratio. Instead of conventional switching using a magnetic field, a current carrying conductor was used to switch the structures. The current value was gradually increased and magnetic force microscopy was used to study the domain changes of the remanent structures after every increment. At the same time, simulation is done using object-oriented micro-magnetic framework to compare with the experimental results.
First Principles Study of the Phase Transitions of MnAs
Authors: Rungger Ivan , Sanvito Stefano 
Published: April 2011

ABSTRACTThe magnetic and structural properties of MnAs are investigated by mapping ab initio total energies onto a Heisenberg Hamiltonian. We study the dependence of the Curie temperature over the unit cell volume and an orthorhombic distortion by using the mean field approximation, and find that for orthorhombically distorted cells the Curie temperature is much smaller than for hexagonal cells. We provide an explanation for the structural changes of both the first order phase transition at 318 K and the second order phase transition at 400 K, with the cell volume driving the stability of the different structures in the paramagnetic state. The stable cell is found to be orthorhombic up to a critical lattice constant of about 3.7 Å, above which it remains hexagonal.
The Effects of Surfactants on the Morphology of Colloidal Crystals in Self-assembly
Authors: Zhou Zuocheng , Li Qin , Wang Likui , Zhao Xiusong 
Published: April 2011

AbstractIn this research, sodium dodecyl sulfates (SDS) and N-cetyl-n,n,n-trimethyammonium bromide (CTAB) surfactant solutions are used as solvents of polystyrene (PS) colloidal suspension during the fabrication of colloidal crystals. The effects of the surfactant on the quality and the morphology of the colloidal crystals are studied. It was found that surfactants not only change the charge of PS colloidal particles, but also significantly changed the surface tension and the 3 phase contact angle of the suspension with respect to the glass substrate, in turn they change the thickness of the formed crystal as well as the crystal structure. The derived knowledge will be potentially useful in clarifying the mechanisms involved in the formation of colloidal crystals.
Surface Molecularly Imprinted TiO2 Nanoparticle for Photoreduction of Viologen
Authors: Sagawa Takashi , Kudo Mayu , Steinke Joachim H. G. , Morii Takashi 
Published: April 2011

ABSTRACTWhen small organic molecules (e.g. amino acids, nucleotides, and so on) are incorporated in metal oxide particles formed from metal alkoxide in the sol-gel process, the organic moieties can be removed readily by solvent washing or by degradative oxidation. Under proper conditions, nano-sized cavities corresponding to the shape of the individual organic moiety are produced within the metal oxide network as molecularly imprinted material such as surface molecularly imprinted TiO2. We tried to fabricate nano-sized particle of TiO2 to increase the effective contact area for the reactants, and further additional function for molecular recognition was intended to introduce through the surface modification of the molecular imprinting method in order to enhance the photoreduction of viologen. In this context, we prepared viologen imprinted TiO2 as an active and stable photocatalyst for photoreduction of viologen as a well-defined and readily identifiable and reversible electron carrier with appropriate redox potential for photoactivated TiO2. The basic concept of molecularly imprinting in this system is as follows. Oxidized viologen is generally twisted and dication molecule. While, reduced viologen is planar and monocation radical. Once TiO2 has such recognition site on its surface, it would be distinguishable through shape or charge recognition or both factors and facilitate the inclusion or exclusion of the target molecule result the enhancement of the reduction. After the preparation of the template, sol-gel imprinting was performed. Measuring its dynamic light scattering monitored changes of the particle sizes and the diameter was stabilized ca 120 nm after 1 week stirring. X-ray diffraction pattern of the TiO2 powder after the dryness without calcination indicates the dominant peak for anatase. Removal of the template was almost 36% after the alkaline rinsing by measuring its UV vis spectra of the washings. A buffered solution of Tris including viologen was irradiated through a xenon lamp under stirring in a quartz cuvett in Ar with or without the TiO2 with cut-off filter at room temperature. The formation of viologen monocation radical whose color is blue was easily recognized only in the reaction with TiO2. The formation of viologen monocation radicals from three types of (methyl, hexyl, and pentacarboxyl) viologens with time in the presence of the imprinted TiO2 and blank one was monitored spectrophotometrically. Blank means that it was fabricated similar way to the imprinted one without the template. Among these results, aliphatic C6 side chains of bipyridinium and terminal carboxyl groups were not effective to enhance. On the other hand, the less bulkiness methyl viologen resulted the highest yield. The most important result is that higher conversion was observed in every case of imprinted TiO2 compared with blank one. Therefore, the key point for recognition is not peripheral part, but bipyridinium part of the viologen.
Time Induced Changes in Phase Transition Behavior and Stability of Zn4Sb3
Authors: Pedersen Birgitte Lodberg , Birkedal Henrik , Nishibori Eiji , Sakata Makoto , Iversen Bo Brummerstedt 
Published: April 2011

ABSTRACTThe stability of high performance thermoelectric Zn4Sb3 has been studied, by using synchrotron powder diffraction to establish differences in phase transition temperatures of two samples. High resolution multi temperature diffraction data has been collected, with a time interval of 13 months, and the phase transition temperature was determined based on the results of Rietveld refinements. The refinements show a difference in transition temperature from data collected the first time till data collected the second time. Furthermore the samples showed impurity peaks after being exposed to air for 13 months, indicating that the sample decomposes over time.
Time Resolved Magneto-Optical Imaging in High Frequency AC Currents of YBa2Cu3O7-&[delta]Thin Films
Authors: Lucarelli Andrea , Frey Alexander , Yang Ran , Luepke Gunter , Haugan Timothy J , Levin George A , Barnes Paul N 
Published: April 2011

ABSTRACTWe present a time-resolved magneto-optical (MO) imaging study of high-temperature superconductor (HTS) in high-frequency alternating current (AC) regime. The evolution of the magnetic flux density distribution in YBa2Cu3O7-d (YBCO) thin film samples is studied in small steps of the phase of the applied AC current. The flux distribution at 10 K exhibits instabilities including flux jumps and flux creep. A quantitative analysis of the data allows us to obtain the current density evolution. The current profile changes considerably with the phase differently from the prediction of the critical state model. These observations can be explained by the higher self-field at the sample edge and the effects of flux creep.
Preparation and Characterization Silver and Copper Layers on Polyimide Prepared by Electroless Copper Plating
Authors: Ji Eun Sun , Kim Young Hwan , Kang Young Soo 
Published: April 2011

ABSTRACTAg particles were generated on Ag+-doped polyimide film by ion exchanging, followed by copper deposition using metallic silver particles as seeds. The Cu layers were coated on the surface of polyimide films by electroless plating method. The surface image and morphology of Cu layers on the polyimide films were characterized with scanning electron microscopy (SEM), and atomic force microscopy (AFM). The chemical composition on the PI film was investigated energy dispersive X-ray (EDX) spectrometer.
A General Approach to Patterning Micron-Scale Particles
Authors: Sieb Nathanael , Gates Byron D. 
Published: April 2011

ABSTRACTMultiple techniques have been developed to assemble micro- or nanostructured materials into well-defined patterns. These techniques are, however, often dependent on the size, shape, composition and/or surface chemistry of the structures being patterned. We have developed a general approach to pattern materials with a wide range of physical and chemical characteristics. We are able to assemble these materials into isolated or interconnected patterns covering areas up to ∼1 mm2.