bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Surface Passivation on Stability of Luminescence from Nanocrystalline Silicon Particles in Pure Water
Authors: Hiruoka Masaki , Sato Keisuke , Hirakuri Kenji 
Published: April 2011

ABSTRACTWe have investigated the stability of luminescence in pure water from a nanocrystalline silicon (nc-Si) particles passivated with various chemical elements such as a hydrogen, carbon and oxygen atoms. Each sample emitted red light with a peak wavelength in a range from 690 to 800 nm. When the hydrogen- and/or carbon-passivated samples were immersed in pure water, the intensity of red luminescence was decreased by aging after a short period of time. At the same time, the peak wavelength was also shifted toward shorter wavelength. These were caused by the generation of defects (Pb-centers) and the reduction of particle size due to the desorption of hydrogen and/or carbon atoms and the replacement from the Si-H and/or Si-C bonds to the Si-O bond, respectively, at the surface of nc-Si particles. On the other hand, the oxygen-passivated sample showed stable luminescence in addition to the slight blue-shift of peak wavelength under the immersion in pure water for 400 hours. The good stability was attributed to the formation of stable surface condition. These results are a strong indication that the stability of the luminescence in pure water can be remarkably improved by the oxygen-passivation to the surface of nc-Si particles.
Time Resolved Photoconduction Studies of Uniformly Doped and p-n Junction Si Nanowires
Authors: Tsakalakos Loucas , Michael Darryl , Fronheiser Jody , Balch Joleyn , Wortman Robert , Wilson Paul , White David , Boone Rolf , LeBoeuf Stephen 
Published: April 2011

ABSTRACTThe time resolved and DC photoconduction characteristics of Si nanowire devices are described. Si nanowires with diameters ranging from 20-100 nm were grown using the vapor-liquid-solid (VLS) growth mechanism under standard conditions and devices were fabricated in a back-gate field effect transistor (FET) configuration using simple photolithography. It is shown that under certain biasing conditions, illumination with light from light emitting diodes with wavelengths ranging from 480 nm to 625 nm causes changes in current as high as 4%. On the other hand, illumination by a broadband incandescent source causes a ∼4.1% percent change in current. Photoconductive decay curves show bi- and tri-exponential behavior, indicative of multiple potential recombination mechanisms occurring within the Si nanowire devices. p-n doped Si nanowires show similar behavior. Studies under various drain and gate voltages provides insight into the proposed mechanism. It is argued that the Shottky barrier plays a strong role in the observed photoconduction process in these wires, as do transitions involving surface and deep level trap states.
Surface Reactions of Metal Catalysts in Ethanol-CVD Ambient at Low-pressure Studied by in-situ Photoelectron Spectroscopy
Authors: Maeda Fumihiko , Suzuki Satoru , Kobayashi Yoshihiro , Takagi Daisuke , Homma Yoshikazu 
Published: April 2011

ABSTRACTWe succeeded in growing carbon nanotubes in a photoelectron spectroscopy analysis system using thermal chemical vapor deposition and analyzed the chemical states of the Co catalysts by in-situ x-ray photoelectron spectroscopy before and after the growth. We found that almost all of the Co particles are metallic after the growth in both cases; Co particles are formed from a Co oxide thin film and a metallic Co thin film. This shows that the metallic state is stable for Co under low-pressure ethanol ambient in our growth condition for carbon nanotubes.
Irradiation assisted interaction behavior of Regioreguler Poly(3-hexylthiophene) nanotube composites
Authors: Adhikari Ananta , Bakhru Hassaram , Chipara Mircea , Ryu Chang Y. , Ajayan Pullickel 
Published: April 2011

ABSTRACTThe basic step to optimize the properties of filler in composite is the interfacial interaction between the matrix and the filler. Irradiation, a novel technique, was used in this work to introduce a wide range of defects in Single-walled Carbon nanotubes (SWNTs) as filler prior to composite formation. The thermal stability along with phase transition behavior of an organic conducting polymer Poly(3-hexylthiophene) (P3HT) loaded with pristine and ion implanted SWNTs has been investigated using Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC), and Electron Spin Resonance (ESR). Interestingly, we observed substantial improvement on the thermal stability and the phase transition behavior of the composite with pristine and irradiated fillers.
Controlled Carbon Nanotube Networks and its Corresponding Channel Effect at High Bias
Authors: Huang Jun , Rao Bangalore Kiran , Vedala Harindra , Kim Do-Hyun , Jeon Minhyon , Park Wanjun , Choi Wonbong 
Published: April 2011

ABSTRACTGeometrically controlled single-walled carbon nanotube (SWNT) and multi-walled carbon nanotube (MWNT) networks were fabricated by a width confinement technique to characterize their electrical characteristics. The results demonstrated non-linear resistance decay with the number of conducting channels. The current-voltage characteristics at high field were studied until the electrical breakdown took place. Large current (∼2 mA), low resistance (∼5 KΩ) and current densities exceeding ∼108 A/cm2 were demonstrated from multi-channel MWNT networks confined in a 10 μm × 15 μm trench. Additionally, chronological SEM imaging was used to identify the breakdown sequences in the carbon nanotube networks, which revealed a strong tendency for CNT breakdown to occur in the vicinity of CNT-CNT intersections. Our results offer insights for interconnect applications using CNT networks.
A Compact Single-Walled Carbon Nanotube Transistor Integrated with a Silicon MOSFET Using a Single Common Gate
Authors: Lin Hao , Park Yong Wook , Tiwari Sandip 
Published: April 2011

ABSTRACTSingle-walled carbon nanotubes have been integrated on top of an individual CMOS device using lithography, chemical vapor deposition and chemical mechanical planarization. Hybrid integration of silicon and nanotube transistors is demonstrated for the first time by making an inverter with a p-type CNTFET placed on top of an n-type MOSFET. A polysilicon gate is positioned between the silicon device channel and carbon nanotube for dense integration of opposite-polarity devices. Such a configuration offers many advantages for high-density electronics and ultra-sensitive detection.
EDLC Properties Depend on the Diameter of Mass Produced Multi-walled Carbon Nanotubes
Authors: Kim Yong-Jung , Abe Yusuke , Yanagiura Takashi , Kitani Massaki , Kodama Tsuyoshi , Higuchi Keita , Endo Morinobu 
Published: April 2011

ABSTRACTMass produced multi-walled carbon nanotubes have examined their feasibility as an electrode for supercapacitors. Activation behavior of MWNTs with different diameter is quite different. In this study, the effect by diameter on KOH activation of MWNTs are confirmed.
Wide Bandgap Semiconductors - Nanowires of p- and n-type Silicon Carbide
Authors: Friedel Bettina , Greulich-Weber Siegmund 
Published: April 2011

ABSTRACTMonocrystalline nanowires of cubic silicon carbide were synthesized using a combined sol-gel and carbothermal reduction process in which tetraethoxysilane was used as primary sili-con and sucrose as carbon source. The diameters of the as-grown nanowires varied depending on process parameters from several tens to several hundreds nanometers, whereas the length of the wires was located in the millimetre region. By precisely controlling the atomic ratio of Si / C, silicon carbide nano wires were synthesized exclusively and pure without the presence of resid-ual carbon or unwanted silica, thus leads to semi-insulating behaviour. Supported by their consis-tence the silicon carbide micro or nano wires can be processed to textile or felt structures and are therefore usable for many applications such as for fireproof clothing, high temperature or chemi-cal filters and composite materials. Additionally during sol-gel synthesis the silicon carbide mi-cro / nano wires were easily doped to achieve p- or n-conduction, guiding to new applications in the field of wide bandgap semiconductors. The structure of 3C-SiC micro and nano wires was determined using scanning electron microscopy, X-ray diffraction, nuclear magnetic resonance and fourier transform infrared spectroscopy. The electronic properties were studied using elec-tron paramagnetic resonance spectroscopy, Hall effect and current-voltage measurements.
Micromachined Silicon Grids for Direct TEM Characterization of Carbon Nanotubes Grown by CVD
Authors: Choi Yongho , Johnson Jason , Moreau Ryan , Perozziello Eric , Ural Ant 
Published: April 2011

ABSTRACTTransmission electron microscopy (TEM) is a key technique in the structural characterization of carbon nanotubes. For device applications, carbon nanotubes are typically grown by chemical vapor deposition (CVD) on silicon substrates. However, TEM requires very thin samples, which are electron transparent. Therefore, for TEM analysis, CVD grown nanotubes are typically deposited on commercial TEM grids by post-processing. This procedure has two problems: It can damage the nanotubes, and it does not work reliably if the nanotube density is too low. The ability to do TEM directly on as-grown nanotubes lying on the silicon substrate would solve these two problems. In this work, for this purpose, we have fabricated micromachined TEM grids from silicon substrates. In particular, we have wet-etched large membranes from the back side of silicon wafers with a thin layer of thermal oxide on them. We have then etched a large array of long and narrow open slits on these membranes from the top side using a deep silicon etcher. Subsequently, we have grown nanotubes on these micromachined TEM grids by CVD, and characterized the nanotubes by high resolution TEM (HRTEM), micro-Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Since the nanotubes grown on the micromachined substrates are completely suspended over the width of the open slits, these substrates form a natural TEM grid for direct imaging of CVD-grown nanotubes. Furthermore, the signal from the substrate is significantly reduced during micro-Raman spectroscopy, resulting in a better signal-to-noise ratio. In addition, the silicon membranes are strong enough to support AFM and SEM characterization. As a result, these substrates provide a low cost, mass producible, efficient, and reliable platform for direct TEM, Raman, AFM, and SEM analysis of as-grown nanotubes or other nanomaterials on the same substrate, eliminating the need for any post-processing after CVD growth.
Reactive Force Field Studies of Large-Deformation of Hybrid Carbon Nanotube-Metal Nanowires
Authors: Wang Xin , King Ryan , Buehler Markus J. 
Published: April 2011

ABSTRACTWe use the ReaxFF reactive force field to model extreme tensile deformation of a (10,10) armchair carbon nanotube. The ReaxFF force field has been developed based on DFT quantum mechanical calculations without any empirical parameters (Duin et al., 2001). We report an analysis of the stress-strain relationship for the elastic and plastic regime, including a description of the microscopic fracture mechanisms. We find Young's modulus to be around 1 TPa, close to experimental values. Our modeling yields a fracture tensile strain of approximately 30%, with a maximum tensile stress of approximately 300 GPa. Fracture of the CNT originates from formation of 5-7 Stone-Wales-like defects, leading to formation of micro-cracks. We also report preliminary results of straining hybrid CNTs embedding a nickel nanowire.
Characterization of TFT-LCD and OLEDs Devices by Phase Modulated Spectroscopic Ellipsometry for Display Applications
Authors: Teboul Eric , Yan Li , Gaillet Melanie 
Published: April 2011

ABSTRACTSpectroscopic ellipsometry is one of the most accurate and reliable optical technique to characterize polymers, liquid crystals (LCs) and organic light emitting diodes (OLEDs). Because these devices are formed by complex structure including optical anisotropy, absorbing and graded materials, the correct use of spectroscopic ellipsometer required a combination of the proper choice of hardware and the appropriate ellipsometric model. In this work, we presents ellipsometric results obtained by a commercially available phase modulated spectroscopic ellipsometer (PMSE) on a full TFT-LCD structure characterized from UV to NIR. As expected, strong anisotropy and inhomogeneous optical properties were found respectively on LCs and ITO materials. We also presents measurements of film thickness and optical constants of each layer constituing an OLED structure
Study on Electron Injection Effect of Low Molecular Organic Light-emitting Diodes Utilizing LiF/Al and Li/Al Cathode
Authors: Kin Zenken , Kajii Hirotake , Ohmori Yutaka 
Published: April 2011

ABSTRACTThe electron injection effects of organic light-emitting diodes (OLED) from the cathode interface between LiF or Li and Al on the tris-(8-hydroxyquinolinato) aluminum (Alq3) emissive layer have been investigated. Efficient electron injection was achieved in the case of thin layer of LiF or Li deposited on Alq3 emissive layer at the thickness of 0.5 nm and 2 nm, respectively. The results indicate that the coexistence of LiF and Al layer or the Li and Al layer on the Alq3 emissive layer result in the efficient electron injection. Electron injection effect in the case of LiF/Al and Li/Al electrode configurations and also the effect of air explosion during the electrode formation have been discussed. In the case of the device with Li, the diffused Li in the Al layer acts as the efficient carrier injection process.
New Concepts for the Development of Active Functional Polymers for p and n-Type OFET- Applications
Authors: Janietz Silvia , Assawapirom Udom , Sainova Dessislava 
Published: April 2011

ABSTRACTHere we present a concept to improve the field effect transistor performance of P3HT in terms of threshold voltage stability as well as the stability in ambient atmosphere by introducing a strong acceptor dopant in the main polymer chain. In our concept the direct introduction of the acceptor dopant in the polymer main chain ensures the strucural stability against diffusion processes. P3HTs with different contents of acceptor molecules which are fixed linked in the main chain of the polymer , have been synthesized using the McCullough Grignard metathesis method. As acceptor unit has been integrated tetrafluorbenzene (TFB). The introduced dopant amount has been varied in order to obtain an optimum between the processability of the polymers and the resultant transistor performance.Compared to the p-type semionducting polymers the n-type organic materials are markedly less developed. Recently an interesting solution to this task has been proposed in the form of a conjugated ladder-type poly (benzo-bisimidazobenzo-phenanthroline) (BBL) showing either ambipolar or n-type field effect properties dependent upon the sample preparation and processing. However this rigid-chain ladder polymer is not soluble in the common organic solvents resulting in a rather complicated technological transfer. We report the significant improvement of the BBL-processing utilizing aqueous colloidal dispersions and their OFET-application. The resultant devices demonstrate ambipolar electronic transport with charge carrier mobilities in the range of 10−5 cm2/Vs without specific optimization procedures..
Extracting the Device Parameters from Organic Thin Film Transistors
Authors: Park Eung Seok , Kang Pil Soo , Kim Gyu Tae 
Published: April 2011

ABSTRACTOrganic thin film transistors(OTFTs) were simulated by a SPICE model adopted in hydrogenated amorphous TFTs(a-Si:H). The gate voltage-dependent mobilities were assumed to fit the representative current-voltage characteristics. The optimal fitting procedures were suggested to compare the experimental data with the mathematical expressions used in the amorphous TFTs. Each SPICE parameter explains the gate dependent mobilities in OTFTs originating from the distribution of trap sites for the hopping conduction.
Orientation Control of Standing Epitaxial Pentacene Monolayers Using Surface Steps and In-plane Band Dispersion Analysis by Angle Resolved Photoelectron Spectroscopy
Authors: Suzuki Tadamasa , Shimada Toshihiro , Ueno Keiji , Ikeda Susumu , Saiki Koichiro , Hasegawa Tetsuya 
Published: April 2011

ABSTRACTWe prepared quasi single crystalline pentacene monolayer films on Bi-terminated Si(111) by using bunched steps on vicinally-cut surfaces as an orientation template. Band dispersion in the conduction plane of pentacene was clearly observed by angle-resolved photoelectron spectroscopy.
Interfacial Phenomena Affecting Charge Transport In Small Molecule Organic Thin-Film Transistors
Authors: Facchetti Antonio , Kim Choongik , Yoon Myung-han , Marks Tobin J 
Published: April 2011

ABSTRACTOrganic semiconductors exhibiting p-, n-type, or ambipolar majority charge transport are grown on six different bilayer dielectric structures consisting of various spin-coated polymers / HMDS on 300 nm SiO2/p+-Si, and are characterized by AFM, SEM, and WAXRD, followed by field-effect transistor (FET) electrical characterization. It is observed that in case of air-sensitive n-type semiconductors, dielectric surface modifications induce large variations in the corresponding OTFT performance parameters although the film morphologies and microstructures remain similar. In marked contrast, the device performance of air-stable n-type and p-type semiconductors is not significantly affected by the same dielectric surface modifications. This study provides key information on the chemical origin of the charge trapping sites at the FET dielectric-semiconductor interface. In parallel, bottom-contact FETs of n-type oligothiophenes were investigated by a combination of microscopy/electrical measurements and new insights for the poor electron injection efficiency from the Au contacts are presented
Electronic Memory Effects in Zinc Oxide Nanoparticle -Polystyrene Devices with a Calcium Top Electrode
Authors: Verbakel Frank , Meskers Stefan C. J. , Janssen René A. J. 
Published: April 2011

ABSTRACTDiodes with an active layer of solution processed zinc oxide (ZnO) nanoparticles and polystyrene are studied. Poly(3,4-ethylenedioxythiophene)- polystyrenesulfonate (PEDOT:PSS) on indium doped tin oxide (ITO) is used as the bottom electrode and aluminum or calcium are used as top electrode. Pristine devices show diode behavior in their current-voltage characteristics. The conductivity of the device in reverse bias can be raised three orders of magnitude by applying a positive voltage or by illumination with UV light. In this high conductivity state we observe reversible electronic memory effects. The electronic memory effects are attributed to a reversible electrochemical process at the PEDOT:PSS/ZnO interface. Memory effects in diodes with Al and Ca metal electrode are found to be very similar, consistent with the view that the memory effects arise at the PEDOT:PSS/ZnO interface.
Organic Field-Effect Based Devices for Pressure Detection
Authors: Manunza Ileana , Bonfiglio Annalisa 
Published: April 2011

ABSTRACTWe describe pressure sensors realised starting from completely flexible organic thin film transistors (OTFTs). A flexible and transparent plastic foil (Mylar) is employed both as substrate and gate dielectric; gold source and drain electrodes are patterned on the upper side of the foil while the gate electrode lies on the opposite side; a vacuum-sublimed pentacene film acts as active layer. The pressure dependence of the output current has been investigated by applying to the gate side of the device a mechanical stimulus by means of a pressurized air flow. Experimental results show a reversible current dependence on pressure; further data analysis suggests that current variations are due to pressure-induced variations of mobility and threshold voltage.
The Control of Electronic States Spreading Outside the Conjugated Polymer Surface
Authors: Hao Xiao Tao , Hosokai Takuya , Mitsuo Noritaka , Kera Satoshi , Sakamoto Kazuyuki , Okudaira Koji Kamiya , Ueno Nobuo 
Published: April 2011

ABSTRACTThe surface electronic structures of conjugated regio regular and regio random poly (3- hexylthiophene) (rr-P3HT and rra-P3HT) thin films were studied by near edge X-ray absorption fine structure spectroscopy, ultraviolet photoelectron spectroscopy and Penning ionization electron spectroscopy (PIES). The distribution of the surface electronic states was controlled on rr-P3HT and rra-P3HT thin films with different molecular ordering by varying the coating process and PIES was adopted to observe the electronic states existing outside the surface.
Structural Transformation in PECVD Ultralow-k Material during Porogen Removal by UV Assisted Thermal Curing
Authors: Zenasni Aziz , Jousseaume Vincent , Gourhant Olivier , Favennec Laurent , Maury Patrick , Mage Lucile 
Published: April 2011

ABSTRACTNext-generation microelectronic interconnects require the use of dielectrics with continuously lower permittivity (k) to overcome limitations induced by crosstalk parasitic signal delay. Using PECVD, Ultralow-k film (ULK, k ≤ 2.5) can be developed by creating pore inclusions within an organosilicate matrix through porogen approach. Both ULK deposition and subsequent curing process has to be adjusted in order to achieve optimized mechanical and electrical properties and maintain stability during integration. For this concern, the attention was recently focused on ultraviolet (UV) radiation to sustain the thermal curing. In the present work, a fundamental understanding of structural transformations occurring during porogen extraction from as-deposited ULK materials when exposed to thermal-assisted UV radiation is proposed. This thermal-assisted UV cure technique is very efficient in porogen removal since in a few minutes the desired porosity is reached. During the first stage of curing, the film shrinks strongly whereas the porosity is created. After porogen removal step, the porous film continues shrinking under UV radiation leading to an increase of SiOSi bonds concentration (film densification). The normalized FTIR SiOSi peak increase during UV curing (related in literature to an improvement of mechanical properties) is mainly due to the film densification, in addition to the SiOSi bridging bond creation. In this case, correlation is found between shrinkage and elastic modulus.
Electrical and Structural Properties of Ruthenium Film Grown by Atomic Layer Deposition Using Liquid-Phase Ru(CO)3(C6H8) Precursor
Authors: Chung Sung-Hoon , Vasilyev Vladislav , Gorokhov Evgeni , Song Yong-Won , Jang Hyuk-Kyoo 
Published: April 2011

ABSTRACTWe investigated effects of thermal annealing on Ru films deposited on the 8 inch Si substrates using a volatile liquid-phase Ru precursor, tricarbonyl-1,3-cyclohexadienyl ruthenium (Ru(CO)3(C6H8)) by an atomic layer deposition (ALD) technique. Structural and electrical properties of the films were characterized by scanning probe microscopy, X-ray diffractometry, sheet resistance. Grazing incidence X-ray diffraction (GIXRD) patterns show typical Ru hexagonal polycrystalline peaks as annealing temperature was increased. At the highest annealing temperature condition, Ta = 700 °C electrical resistivity become 6 times less than in as-deposited films.