bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser Induced Fluorescence Measurement Of Plasma Plume During Pulsed Laser Deposition Of Diamond-Like Carbon
Authors: Yamagata Yukihiko , Kozai Yuji , Mitsugi Fumiaki , Ikegami Tomoaki , Ebihara Kenji , Sharma Ajay , Mayo Robert M. , Narayan Jagdish 
Published: April 2011

AbstractDynamics of carbon ablation plasma plume during the preparation of diamond-like carbon films by KrF excimer pulsed laser deposition was investigated using laser induced fluorescence (LIF) and optical emission spectroscopy. LIF signal from C2molecule (Swan band, d 3Φg – a3Φu) was detected using a photomultiplier tube and an intensified CCD camera. Temporal evolution and spatial distribution of C2 molecules in the ablated plume were measured as a function of laser energy density and ablation area. LIF intensity is found to be weaker in the central part of the plume than that at the periphery at incident energy greater than 6 J/cm2. It is conjectured that some of C2molecules are dissociated by collision with energetic species in central part of the ablation plume. Dynamics of ablation plasma plume is strongly dependent on the size of ablated area.
Surface morphology studies of phthalocyanine thin films: mechanism of the α → β1 phase transition
Authors: Heutz Sandrine , Bayliss Sallie M. , Rumbles Garry , Jones Tim S. 
Published: April 2011

ABSTRACTFree base phthalocyanine films have been grown on glass substrates by organic molecular beam deposition. In situ post-growth annealing of the samples leads to the α → β1 transformation. Different transition states have been identified and their morphological properties studied by atomic force and optical microscopy. The transition occurs via a discrete number of nucleations and is preceded by an elongation of the α crystallites. The β1 crystallites grow but are confined to domains of similar orientation. Increased thickness produces larger domains and better orientation, while only partial transformation occurs below 94 nm.
Angular Fourier Mapping; Highlighting lattice structures without destroying original data
Authors: Kindt Johannes H. , Thompson James B. , Paloczi George T. , Michenfelder Martina , Smith Bettye L. , Stucky Galen , Morse Daniel E. , Hansma Paul K. 
Published: April 2011

ABSTRACTA two-dimensional Fourier transformation, FT, is used to isolate two different lattice structures within one scanning probe microscope, SPM, image. The isolated structures are then used to create a two-color map that encodes the presence of these structures within the image. The color map is normalized in brightness and then used to color-code the original black and white SPM data. The distribution of different structures becomes obvious, while all original brightness information is preserved in this combined image.
Electroluminescent Devices with Nanostructured ZnS:Mn Emission Layer Operated at 20 V0-p
Authors: Toyama Toshihiko , Adachi Daisuke , Okamoto Hiroaki 
Published: April 2011

ABSTRACTWe have developed a new type of a thin-film electroluminescence (TFEL) device with nano- structured (NS)-ZnS:Mn utilizing its enhanced luminescent efficiency due to the quantum confinement (QC) effects. As NS-ZnS:Mn, ZnS:Mn/Si3N4 multilayers with thicknesses of 1.9–3.5 nm for ZnS were prepared by a rf-magnetron sputtering method. From the results of grazing incidence X-ray reflectometry and X-ray diffractmetry, formation of ZnS:Mn nanocrystals in the ZnS layers are confirmed. With a decrease in the ZnS:Mn layer thickness, the photoluminescence (PL) efficiency associated with the Mn2+ transitions is increased, and the PL excitation spectrum is shifted toward higher energies, indicating appearance of the QC effects. As the results of the application of NS-ZnS:Mn to the emission layer of the TFEL device, we have successfully observed reddish-orange emission above the threshold voltage of 12 V0-p, and the maximum luminance is 3.0 cd/m2 operated with the 1-kHz sinusoidal voltage of 20 V0-p.
Photo and Cathodoluminescence in Cerium-Activated Yttrium-Aluminium Borates
Authors: Mordkovich V. Z. 
Published: April 2011

ABSTRACTCe3+ luminescence in Ce-activated yttrium aluminium borates was studied. Photoluminescnece was excited by continuous-wave UV or by pulse laser irradiation. Cathodoluminescence was excited at the acceleration voltage in the range 5 to 600 V. These phosphors show under continuous wave UV excitation three emission peaks: in near UV, deep blue and light blue ranges. The light blue peak at around 490 nm which may be connected to forbidden 2D3/2 → 2F7/2 transition appears in continuous wave-excited photoluminescence only and does not appear in cathodoluminescence nor under pulse excitation. The blue-emitting Ce- activated yttrium aluminium borates exhibit unusually strong activator ion-host lattice interaction. As a result a substantial red shift in the emission is induced by Ce concentration increase and complicated concentration dependence of the emission intensity is observed.
Green Emission from Er-Doped AlN Thin Films Prepared by RF Magnetron Sputtering
Authors: Dimitrova V. I. , Perjeru F. , Chen Hong , Kordesch M. E. 
Published: April 2011

ABSTRACTThin films of Er doped AlN, ∼ 200 nm thick, were grown on indium tin oxide/aluminum titanium oxide/glass substrates using RF magnetron sputtering in a pure nitrogen atmosphere. To optically activate Er all films were subject to post-deposition annealing in flowing nitrogen atmosphere at atmospheric pressure at temperatures between 1023-1223 K for 10-60 minutes. The visible cathodoluminescence (CL) in the green was detected at both 11 K and 300K. The strongest CL peaks were observed at 558 nm and 537 nm (11 K), which correspond to the transitions from 4S3/2 and 2H11/2 to the 4I15/2 ground level. Electroluminescence (EL) studies of AlN:Er alternating-current thin-film electroluminescent (ACTFEL) devices were performed at 300 K. The turn-on voltage was found to be around 80-100 V for our ACTFEL devices. The intensity of the EL emission rapidly increases with the voltage increasing in the investigated range of 110-130 V.
Effect of TiO2 Addition on the Secondary Electron Emission and Discharge Properties of MgO Protective Layer
Authors: Kim Younghyun , Kim Rakhwan , Kim Hee Jae , Jeon Hyeongtag , Park Jong-Wan 
Published: April 2011

ABSTRACTSecondary electron emission from a cathode material in AC PDP (Plasma Display Panel) is dominated by potential emission mechanism, which is sensitive to band structure of a protective layer. Therefore, the secondary electron emission property can be modified by a change in the energy band structure of the protective layer. Mg2-2xTixO2 films were prepared by e-beam evaporation method to be used as possible substitutes for the conventional MgO protective layer. The oxygen content in the films and in turn, the ratio of metal to oxygen gradually increased with the increasing TiO2 content in the starting materials. The pure MgO films exhibited the crystallinity with strong (111) orientation. The Mg2-2xTixO2 films, however, had the crystallinity with (311) preferred orientation. The stress relaxation, when the [TiO2/(MgO+TiO2)] ratio in the evaporation starting materials was 0.15, seems to be related to inhomogeneous film surface due to an excessive addition of TiO2 to MgO. When the [TiO2/(MgO+TiO2)] ratios of 0.1 and 0.15 were used, the deposited films exhibited the secondary electron emission yields improved by 50% compared to that of the conventional MgO protective layer, which resulted in reduction in discharge voltage by 12%.
Low Temperature Laser-Doping Process Using PSG and BSG Films for Poly-Si TFTs
Authors: Kim Cheon-Hong , Jung Sang-Hoon , Jeon Jae-Hong , Han Min-Koo 
Published: April 2011

ABSTRACTA simple low-temperature excimer-laser doping process employing phosphosilicate glass (PSG) and borosilicate glass (BSG) films as dopant sources is proposed in order to form source and drain regions for polycrystalline silicon thin film transistors (poly-Si TFTs). We have successfully controlled sheet resistance and dopant depth profile of doped poly-Si films by varying PH3/SiH4 flow ratio, laser energy density and the number of laser pulses. The penetration depth and the surface concentration of dopants were increased with increasing laser energy density and the number of laser pulses. The minimum sheet resistance of 450ω/ for phosphorus (P) doping and 1100ω/ for boron (B) doping were successfully obtained. Our experimental results show that the proposed laser-doping process is suitable for source/drain formation of poly-Si TFTs.
Crystallization of Amorphous Si Thin Films Using a Viscous Ni Solution
Authors: Ahn Jin Hyung , Kim Sung Chul , Ahn Byung Tae 
Published: April 2011

ABSTRACTWe prepared a viscous Ni solution by dissolving NiCl2 in 1N HCl and mixing it with propylene glycol to control the amount of Ni on Si surface. A uniform film was formed after spin coating and oven dry. The a-Si films deposited by LPCVD with Si2H6 gas were crystallized more uniformly and more reproducibly. And the crystallization was enhanced from 600°C, 30h to 500°C, 10h. The surface roughness of poly-Si film crystallized with the viscous solution was much smaller than that of poly-Si film crystallized from Ni/Si direct contact. The TFT mobility was improved even though the crystallization temperature was much lower.
Crystal Growth of Laser Annealed Polycrystalline Silicon as a Function of Hydrogen Content of Precursors
Authors: Tamura Takuo , Ogata Kiyoshi , Takahashi Michiko , Suzuki Kenkichi , Yamaguchi Hironaru , Todoroki Satoru 
Published: April 2011

ABSTRACTThe influence of hydrogen in a precursor on excimer laser crystallization behavior was investigated. The crystal orientation and lattice constant of polycrystalline silicon films were analyzed by X-ray diffraction measurement. An intensity ratio of 111 to 220 was used as an index of the (111) preferred orientation. A randomly oriented film with an index of 2 at lower energy density changed to the highly (111) oriented phase with an index of more than 15 at higher energy density. It was observed in the PE-CVD films that increasing the hydrogen in the precursor films decreased the orientation index. The lattice constant of the laser-annealed PE-CVD silicon was found to be larger than that of the PVD silicon and to decrease with an increase in laser energy density. The network structure of as-deposited PVD film with less hydrogen content was denser than that of as-deposited PE-CVD. The network structure of the precursor strongly affected the crystal growth, and the structure of the ELC poly-Si was still affected by the precursors, even though the hydrogen content decreased after laser annealing.
Sequential Lateral Solidification of PECVD and Sputter Deposited a-Si Films
Authors: Crowder M. A. , Sposili Robert S. , Limanov A. B. , Im James S. 
Published: April 2011

ABSTRACTWe have investigated sequential lateral solidification (SLS) of amorphous Si films that have been prepared via PECVD and sputter deposition methods. The focus of the work was on identifying and analyzing the energy density and per-pulse translation distance parameter space that permits SLS of these films. Experimental details include the use of a two-axisprojection irradiation system to image a straight-slit beamlet pattern onto the sample, and analyzing the resulting microstructures by SEM and optical microscopy of Secco-etched samples. High-temperature-deposited LPCVD films were also examined to enable further comparative analysis. We conclude from these results that there are no major differences in both the SLS process characteristics and the resulting microstructure among the investigated films (provided that the films are dehydrogenated in the case of PECVD a-Si). Based on the controlled super-lateral growth (C-SLG) model of the SLS process, we attribute these findings to the fact that the SLS method involves—as one of its essential features—complete melting of the Si film at fluences that are sufficient to thoroughly melt crystalline Si films, during which all pre-irradiation phase and microstructural details are erased.
Chemical effects observed in the SERS spectra of single wall nanotubes
Authors: Baibarac Michaela , Baltog Ioan , Lefrant Serge , Chauvet Olivier , Mévellec Jean-Yves , Vaccarini Laetitia , Bernier Patrick 
Published: April 2011

AbstractIn this paper, we present results obtained by Surface Enhanced Raman Scattering (SERS) on SWNTs films with different thicknesses. We show that the “D” band associated to disorder in graphitic compounds can also be due to intrinsic defects in SWNTs. In addition, we put in evidence strong interfacial reactions at the SWNTs/metallic support interface when NMP is used as solvent to disperse the tubes. Our observations suggest that these reactions can induce a breaking of the SWNTs. Presumably a reconstruction of compounds close to C60 molecules can occur.
Time and Space Evolution of Emitting Carbon Nanoparticles – Correlation with the Formation of Fullerenes and Carbon Nanotubes –
Authors: Suzuki Shinzo , Sen Rahul , Yamaguchi Hirofumi , Ishigaki Toshinobu , Ohtsuka Yohsuke , Achiba Yohji , Kataura Hiromichi 
Published: April 2011

AbstractThe temporal and spatial evolution of emitting carbon nanoparticles were investigated using a laser furnace apparatus combined with a high-speed video camera. An apparent increase in the blackbody emission intensity at Δt > 400 [.proportional]sec after laser vaporization of a graphite rod was clearly recognized. Also, it was found that this increasing tendency corresponds well to that of the fullerene yield, where fullerene species was obtained as sublimed carbon material using in situ sublimation method. These findings suggest that a certain exothermic process related to the formation of C60, other higher fullerenes, and carbon nanotubes should occur at Δt > 400 νsec inside the furnace.
Gas Molecules Adsorption on Carbon Nanotubes
Authors: Zhao Jijun , Buldum Alper , Han Jie , Lu Jian Ping 
Published: April 2011

AbstractWe study electronic properties of single-walled carbon nanotubes (SWNTs) upon gas molecules adsorption with first principles methods. The adsorption energy, charge transfer, and electronic structures are studied for various gas molecules (NO2, O2, NH3, N2, CO2, CO, H2O, H2, He). Most molecules adsorb weakly on SWNTs and can be either charge donor or accepter to the nanotubes. The electronic properties of nanotubes are sensitive to the adsorption of certain molecules such as NO2 and O2. Charge transfer and gas-induced charge fluctuations are found to significantly affect the transport properties of SWNTs. Our results are consistent with recent experiments.
Catalyst-Free Synthesis of Single-Wall Boron Nitride Nanotubes via Laser Ablation
Authors: Lee Roland S. , Gavillet Julie , Chapelle Marc Lamy de la , Cochon Jean-Lou , Pigache Daniel , Thibault Jany , Willaime François , Loiseau Annick 
Published: April 2011

AbstractBoron nitride nanotubes (BN-NTs) were synthesized in “mass” quantities (∼0.6 g/h) using a continuous CO2 laser ablation reactor described in the literature [1]. High-resolution electron microscopy (HRTEM) analyses have shown the nanotubes to be organized in “ropes” comprising ∼10 tubes. Analysis of HRTEM images indicate that the majority of the tubes are zig-zag. The chemical composition of the tubes was confirmed using electron energy loss spectroscopy (EELS) analysis, which also determined that nanoparticles terminating tube ends were composed of pure boron covered by BN fullerene-like “cages”. The growth mechanism of the nanotubes seems to be “root-based” with tubes growing from boron nanoparticles dispersed throughout the samples; the non-particle-terminated ends of the tubes exhibit flat “caps” characteristic of BN-NTs [2].
Magnetic Properties of 100 NM-Period Nickel Nanowire Arrays Obtained from Ordered Porous-Alumina Templates
Authors: Nielsch K. , Wehrspohn R.B. , Fischer S.F. , Kronmüller H. , Barthel J. , Kirschner J. , Gösele U. 
Published: April 2011

AbstractNi nanowires were grown in highly-ordered anodic alumina templates using pulsed electrodeposition. This technique yields completely metal-filled alumina membranes. The magnetic behavior of 100 nm period arrays of Ni nanowires with a length of 1 μ and different diameters has been characterized using SQUID magnetometry and magnetic force microscopy. Reducing the diameter from initially 50 to 25 nm while keeping the interwire distance constant leads to increasing coercive fields from 600 Oe to 1200 Oe and to increasing remanence from 30% to 100% of the hysteresis. The deposition of Ni65Fe35 gave a further improvement of the coercive fields up to 1350 Oe.
Fabricating Two-Dimensional Metal Nanocrystal Arrays Using Pulsed-Laser Deposition and Focused Ion-Beam Technologies
Authors: Haglund Richard F. , Weller Robert A. , Heiner Cynthia E. , McMahon Matthew D. , Magruder Robert H. , Newton Allen T. , Shen Liyong , Feldman Leonard C. 
Published: April 2011

AbstractWe describe recent experiments in which we attempted the initial steps for fabricating twodimensional arrays of metal nanocrystals. We use a commercial pulsed-laser deposition system in concert with a focused ion beam to attempt control over both lateral and vertical dimensions at the nanometer length scale. In our experiments, regular arrays of holes typically 80 nm in diameter were drilled in Si substrates using the focused ion beam. Silver atoms were then deposited onto these substrates by pulsed laser evaporation from a metallic target in high vacuum. Under certain conditions of substrate temperature, laser pulse repetition rate, and fluence, small silver nanoclusters form preferentially around the structures previously etched in the silicon surfaces by the focused ion beam.
Nanofabrication of Planar High Temperature Superconducting Josephson Junctions Using Focused Ion Beam Technology
Authors: Zhai Hong-Ying , Chen Quark Y. , Liu Jiarui , Chu Wei-Kan 
Published: April 2011

AbstractSuperconductor-normal metal-superconductor (SNS) high-Tc Josephson junctions have been fabricated on c-oriented YBa2Cu3O7-δ (YBCO) films. Focused ion beam (FIB) nano-structure modification (cutting of the film and local deposition of a metal) was used to form the junction with tungsten barrier. The junctions exhibit resistively shunted junction (RSJ) -like I-V characteristics.
A New Simple Method for Fabrication of Fine Metal Patterns
Authors: Hotta Yasuyuki , Asakawa Koji , Matake Shigeru , Hiraoka Toshiro 
Published: April 2011

AbstractWe developed a new method for easy fabrication of micrometer-scale fine metal patterns on substrates. The patterns can be fabricated at low cost, at low processing temperature, and on uneven substrates as well as on plane surfaces. The method involves, first, forming hydrophilic and hydrophobic patterns on the substrates, and, second, depositing metal by electroless plating on the hydrophilic area. Hydrophilic and hydrophobic patterns were formed on a sensitizer containing naphthoquinonediazide (NQD) units coated on the substrates by the exposure. In the exposed areas, metal particles that are catalysts for electroless copper plating were adsorbed in the ion-exchange reaction and then the reduction treatment was performed. Copper was selectively deposited by the self-catalyst mechanism, according to the exposed patterns. All experimental processes can be carried out at room temperature. Using this new method, copper line patterns of 25 μm and copper dot patterns of 15 μm diameter were fabricated on the substrate.
Low Pressure Band Tuning in Wurtzite CdSe Quantum Dots
Authors: Meulenberg R.W. , Offen H.W. , Strouse G.F. 
Published: April 2011

AbstractSeveral studies to date have probed structural phase transitions in quantum dots (QDs) at high pressure. At low pressure (< 1 GPa), the optical properties of solvated nanomaterials are modulated by pressure induced electronic level tuning, particularly for surface and trap states. In fact, low pressure studies on solvated CdSe QDs may provide insight into the participation of surface hole traps and electron traps on the excited state optical properties in these materials. We report findings of QD size dependent pressure coefficients and postulate that trap state tuning, surface reconstruction events, and electron-hole exchange interactions may play a role in the low-pressure regime.
Self-Assembled Monolayers as High-Resolution Etch Masks and Templates for Organic Molecular Assembly
Authors: Harnett C. K. , Lopez A. G. , Satyalakshmi K. M. , Chen Y.-F. , Craighead H. G. 
Published: April 2011

AbstractWe have used a variety of self-assembled monolayers as resists for low energy electron beam patterning. These compounds can be used as high-resolution patternable linker molecules for selected area binding of proteins and other organic compounds, as well as nanoparticles with organic chemical coatings. Because these systems can be aligned in registry to existing patterns, the organic systems may be positioned with the accuracy of electron-beam lithography. We have also explored the use of self-assembled monolayers for the creation of sub-wavelength artificial dielectric systems. The ultra-thin patterned monolayer is combined with a contrast-enhancing etch process to create high aspect ratio structures. This technique can be used to fabricate diffractive optical devices in a single-step process.
Photoluminescence and ESR study of Si1−xGex alloy nanocrystals
Authors: Toshikiyo K. , Tokunaga M. , Takeoka S. , Fujii M. , Hayashi S. 
Published: April 2011

AbstractDangling bond defects in Si1−xGex alloy nanocrystals (nc-Si1−xGex) as small as 4 nm in diameter embedded in SiO2 thin films were studied by electron spin resonance (ESR), and the effects of the defects on photoluminescence (PL) properties were discussed. It was found that the ESR spectrum is a superposition of signals from Si and Ge dangling bonds at the interfaces between nc-Si1−xGex and SiO2 matrices (Si and Ge Pb centers). As Ge concentration increased, the intensity of the signal from the Ge Pb centers increased, while that from the Si Pb centers was almost independent of Ge concentration. The increase in the number of Ge Pb centers was accompanied by strong quenching of the PL. The observed correlation between the two measurements suggests that Ge Pb centers act as efficient non-radiative recombination centers for photogenerated carriers, resulting in the quenching of the PL.
Formation of Ge Nanocrystals Passivated with Si by Gas Evaporation of Si and Ge
Authors: Si Junjie , Ono H. , Uchida K. , Nozaki S. , Morisaki H. 
Published: April 2011

AbstractTwo methods are employed in the gas evaporation technique to form Ge nanocrystals with the Si-passivated surface. One uses one boat with a SiGe alloy as a source, and the other uses two boats each with Si and Ge. As a result of characterization by the x-ray diffraction (XRD) measurement, Raman scattering and x-ray photoelectron spectroscopy (XPS), it is found that Ge nanocrystals with the Si-passivated surface were formed by coevaporation of Si and Ge from two boats, while SiGe alloy nanocrystals were formed by evaporation of the Si-Ge alloy source from one boat.