bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polycrystalline and Amorphous Chromium Oxide MOCVD
Authors: Chang Yuneng , Huang Shengfu , Huang Minche 
Published: April 2011

AbstractThis paper will report the methods to deposit polycrystalline or amorphous chromium oxide (Cr2O3) thin films, which have potential applications in optoelectronics such as components for flat panel display devices. An atmospheric cold wall chemical vapor deposition (CVD) system was used to thermally decompose sublimed chromium acetylacetonate(Cr(C5H7O2)3) precursor, which gave Cr2O3 films. Oxygen concentration in gas phase is the key factor determining chromia film structure. In oxygen containing CVD system, the deposited films were polycrystalline Cr2O3, with (006), and (110) orientations. In inert, O2 free environment, the grown films were amorphous chromium oxide, as identified by XPS and XRD results. Based on depth profiling AES results, even in an oxygen free ambient, the elemental Cr/O ratio in films still remained stoichiometry(Cr:O = 2:3). Oxygen atoms might originate from acetylacetonyl (C5H7O2) ligands in the Cr(C5H7O2)3precursor.
Enhanced Low-Temperature Crystallization of Amorphous Si Films Using AlCl3 Vapor
Authors: Ahn Jin Hyung , Eom Ji Hye , Ahn Byung Tae 
Published: April 2011

AbstractIt is known that the direct contact between Al and a-Si enhances the crystallization of a-Si film. But the poly-Si films crystallized by the direct contact of Al metal film suffer the problems of rough surface and pores. In our study, we utilized the vapor from AlCl3 instead of Al metal film. The crystallization was enhanced by annealing a-Si films with AlCl3 that the crystallization was completed in 5h at 540. And the surface was as smooth as that of the a-Si film. The Al incorporation into the poly-Si film took place, but the content was below the detection limit of AES.
Thermal Stability of Strained Si on Relaxed Si1−xGex Buffer Layers
Authors: Mooney P.M. , Koester S.J. , Ott J.A. , Jordan-Sweet J.L. , Chu J.O. , Chan K.K. 
Published: April 2011

AbstractThe thermal stability of strained Si on relaxed Si1−xGex structures annealed at 1000 °C was investigated using high-resolution x-ray diffraction, Raman spectroscopy and transmission electron microscopy. Interdiffusion at the Si/Si1−xGex interface is negligible for annealing times <30 sec and is independent of the initial Si layer thickness and the composition of the Si1−xGex layer. In all cases the Si layers remained nearly fully strained, but a significant density of misfit dislocations was seen in layers that exceeded the critical thickness for dislocation glide. The Si layer thickness could be measured for layers as thin as 7 nm.
Process-Structure Relationships of Nitrided Oxides and Oxynitrides
Authors: Dasgupta Anindya , Takoudis Christos G. 
Published: April 2011

AbstractThe presence of nitrogen in the dielectric films is known to impart highly desirable properties in the ultra-large-scale-integration era; the position, amount and concentration profiles of nitrogen are therefore of great interest. In this work, we investigate two-step processes leading to bimodal nitrogen profiles, with one nitrogen peak near the Si/dielectric interface and the other near the dielectric surface. At 1000°C and 1 atm, a nitridation step with NH3 following either an oxidation (in O2) or oxynitridation (in N2O) step is found to result in a bimodal nitrogen concentration profile for short nitridation times. Increasing the duration of the nitridation step with NH3 is found to completely nitridate the entire film. Secondary Ion Mass, Angle Resolved X-Ray Photoelectron, and Fourier Transform Infrared Spectroscopic studies are shown to support these observations. Therefore, based on such process-property-structure relationships, the engineering of desired nitrogen concentration profiles in nano-dielectric materials of interest becomes possible. Such knowledge may have significant implications on micro- and nano-electronic applications of silicon oxynitrides.
On the Mechanism of Fatigue in Micron-Scale Structural Films of Polycrystalline Silicon
Authors: Muhlstein C. L. , Stach E. A. , Ritchie R. O. 
Published: April 2011

Abstract2-νm thick structural films of polycrystalline silicon are shown to display “metal-like” stress- life fatigue behavior in room air, with failures occurring after >1011 cycles at stresses as low as half the fracture strength. Using in situ measurements of the specimen compliance and transmission electron microscopy to characterize such damage, the mechanism of thin-film silicon fatigue is deduced to be sequential oxidation and moisture-assisted cracking in the native SiO2 layer. This mechanism can also occur in bulk silicon but it is only relevant in thin films where the critical crack size for catastrophic failure can be exceeded within the oxide layer. The fatigue susceptibility of thin-film silicon is shown to be suppressed by alkene-based self- assembled monolayer coatings that prevent the formation of the native oxide.
Microfabricated Crevice Former with a Sensor Array
Authors: Wang Xiaoyan , Kelly Robert G. , Reed Michael L. 
Published: April 2011

AbstractMicrofabrication of crevice corrosion samples is of importance in developing an accurate, comprehensive, and reliable crevice corrosion model, and real-time acquisition of corrosion information is also essential. Solid-state microsensor arrays have been used for detecting potential, pH, and ion concentrations, and their integration into crevice corrosion testing samples will provide real-time spatial information of crevice corrosion. The crevice corrosion testing sample is constructed by coupling a crevice former to a crevice substrate and has a uniform crevice gap. In this paper we present a crevice former incorporating a potentiometric, ion- selective membrane microelectrode pH sensor array. The crevice former is built on a silicon wafer using microelectromechanical systems (MEMS) fabrication and thin film semiconductor processing techniques, and consists of an array of five independent sensing microelectrodes. The array configuration allows for in-situ spatial pH analysis of crevice corrosion based on information from each sensor. The fabrication details of the crevice former with microelectrode sensor will be elaborated.
Peak effect at microwave frequencies in swift heavy ion irradiated YBa2Cu3O7-δthin films - investigation of vortex dynamics
Authors: Banerjee Tamalika , Bhangale A. R. , Raychaudhuri P. , Kanjilal D. , Pinto R. 
Published: April 2011

ABSTRACTThe vortex dynamics at microwave frequencies in YBa2Cu3O7-δ(YBCO) films has been studied. We observe a peak in the microwave surface resistance Rs vs. T (temperature) plots at 4.88 GHz in some films in magnetic fields (upto 0.8 T) whereas a few films do not show a pronounced peak in their surface resistance. This is associated with the ‘peak-effect’ phenomenon and reflects the order-disorder transformation of the flux-line lattice near the transition temperature. Introduction of artificial pinning centers like columnar defects as a result of irradiation with 200 MeV Ag ion leads to the suppression of the peak in films exhibiting the ‘peak-effect’. Interestingly, a peak is seen to develop in those films that initially did not show a peak in the surface resistance before irradiation. These results and the dynamics of the vortices at microwave frequencies for the unirradiated and irradiated films will be discussed.
AC susceptibility of the sintered Bi1.6Pb0.4Sr2(Ca1-xMx)2Cu3Oδbulk high-Tc superconductors
Authors: Adam Malik I , Shaari Abdul Halim , Hassan Zainul A , Khalid Kaida 
Published: April 2011

ABSTRACTAC susceptibility measurements as a function of temperature, frequency and applied ac field amplitude were performed on two rectangular bar shaped samples of nominal composition Bi1.6Pb0.4Sr2(Ca1-xMx)2Cu3Oδ, with M=Pr, Gd, and x=0.01, obtained by the usual solid state reaction route. The incorporation of the rare earth elements at low concentration stage results in an improvement of grain connectivity for the sample doped with Pr. On the other end, the ac field amplitude and frequency dependence of the susceptibility curves disclosed bulk pinning hystersis loss feature. The potential barrier height, activation energy at the grain boundary extracted from the low temperature peak revealed that flux creep is governing the pinning mechanism inside the samples. Qualitative discussion in the framework of the critical state model was highlighted
New conductive IBAD buffer for HTS applications
Authors: Thiele Karola , Sievers Sibylle , Dzick Juergen , Kautschor Lars-Oliver , Jooss Christian , Hoffmann Joerg , Freyhardt Herbert C. 
Published: April 2011

ABSTRACTBiaxially aligned Indium Tin Oxide (ITO) thin films to be used as electrically conductive buffer layers were prepared by an Ion-Beam Assisted Deposition (IBAD) process on various substrates. Two Kaufman ion sources with 2.5 cm diameter were employed for the assisting and the sputtering beam, respectively. All deposited films revealed (001) oriented film growth with a strong in-plane alignment. The degree of the in-plane orientation was studied depending on the ion-beam parameters and the incident angle. Investigations (TEM and X-ray) of the texture evolution of these IBAD films during film growth were carried out. An in-plane texture of 12.6°FWHM for a 1 μm thick film has been achieved so far. The quality of the buffer has been demonstrated by the subsequent deposition of high-current carrying YBCO-films deposited by thermal coevaporation using a 3–5 nm thick Y2O3 interlayer. A jc of 0.76 MA/cm2 (77K, 0T) has been obtained for a 1 cm × 1 cm sample with ITO of 20° FWHM.
Imaging Transport Current Distribution in High Temperature Superconductors Using Room Temperature Scanning Laser Microscope
Authors: Kwon C. , Klein B. E. , Seo S. , Park B. H. , Jia Q. X. 
Published: April 2011

ABSTRACTWe report the feasibility of room temperature scanning laser microscopy (RTSLM) for the study of high temperature superconducing films. RTSLM images from SmBa2Cu3O7 and how that the ac–voltage response exists only in the section of the bridge where the transport current produces a voltage drop. A photolithographically defined 60 μm × 60 μm void in a 300 μm–wide bridge was clearly visible in a RTSLM image giving the spatial resolution smaller than 60 μm. In addition, the void disturbs the transport current distribution beyond itself generating an elongated shape void of 64 μm × 85 μm with the longer side along the direction of current flow in the RTSLM image. Our results indicate that the RTSLM is a useful tool to investigate the transport current distribution in high temperature superconductors.
Doping and Alloying Trends in New Thermoelectric Materials
Authors: Loo Sim , Lal Sangeeta , Kyratsi Theodora , Chung Duck-Young , Hsu Kuei-Fang , Kanatzidis Mercouri G. , Hogan Timothy P. 
Published: April 2011

ABSTRACTNew thermoelectric bulk materials such as CsBi4Te6 have shown superior properties to traditional materials, however, optimal performance requires continuing investigations of doping and alloying trends. A recently modified high throughput measurement system is presented for doping and alloying investigations in several new thermoelectric materials. The modification includes a four-probe configuration for more accurate measurements while maintaining a relatively short sample preparation time. The system is fully computer controlled and provides flexible contacts to accommodate various sample dimensions. Optimal compositions are then identified for further investigations in thermoelectric prototype modules. The most promising materials will be further characterized for electrical conductivity, thermoelectric power, thermal conductivity, and Hall effect measurements as a function of temperature.
Microstructure and Thermoelectric Properties of p-Type Bi0.5Sb1.5Te3 and n-Type Bi2Te2.7Se0.3 Films Deposited by Pulsed Laser Ablation
Authors: Makala Raghuveer S. , Jagannadham K. , Sales B.C. , Wang Hsin 
Published: April 2011

ABSTRACTThin films of p-type Bi0.5Sb1.5Te3, n-type Bi2Te2.7Se0.3 and n-type with SbI3 doping were deposited on mica substrates using Nd-YAG pulsed laser ablation at temperatures ranging from 300°C to 500°C. These films were characterized using X-ray diffraction, SEM and TEM. X-ray mapping and EDS were used to determine the composition. The films showed uniform thickness and high crystalline quality with a preferred (00n) alignment with the substrates. The film quality in terms of composition and crystal perfection is studied as a function of growth temperature. It was found that films deposited at 350°C gave improved crystallinity and thermoelectric characteristics. The Seebeck coefficient, electrical resistivity and Hall mobility were measured as a function of temperature and compared with the measurements on the bulk. Correlation of thermoelectric properties with microstructure is discussed.
Discrete State Simulation of Electrical Conductivity and the Peltier Effect for Arbitrary Band Structures
Authors: Radkowski Peter P. F. , Sands Timothy D. 
Published: April 2011

ABSTRACTAn object-oriented, discrete state method for simulating coupled systems was defined. A proof-of-principle simulation of the effect of acoustic phonon scattering on electrical current was performed. Steady-state and relaxation processes were numerically simulated. A relaxation time constant was measured. The numerical simulation of Peltier cooling and heating was defined as a special case of the scattering and transport physics of the proof-of-principle simulation. The scattering terms were designed to account for local interface conditions.
Defect Formation in Boron Carbide-An ab-initio Electronic Structure Study
Authors: Wang Jun , Marshall D.S. 
Published: April 2011

ABSTRACTThe electronic structure of a crystalline boron carbide has an energy forbidden gap of ∼ 3 eV and is hence a good insulator. But, on the other hand, the electrical conductivity of boron carbide is measurable. It is therefore believed that the defects formation in boron carbide is responsible for its electrical conductivity and a theory of hopping conduction of bipolaron through localized defects were developed, accordingly. Although the bipolaron electrical conductivity model does not rely on any specific type of defect, the bipolaron formation in boron carbide is believed to be a defective CBB intraicosahedral chain in connection with an B11C icosahedron. The current study examined the existing theory of bipolaron electrical conductivity by performing a systematical study on the formation energies of the defects in boron carbide using a state-of-the-art ab-initio electronic structure method. The studied defects cover a) stoichiometric variations of carbon concentration, b) missing boron atoms, and c) distribution of carbon atoms in the materials. It is found that the ground state of a fully carbonated boron carbide consists of B11C icosahedra connected by CBC intraicosahedral chains, i.e. consistent with the reported structural model of B4C. When carbon concentration is reduced, however, the population of CBC chain is found to be intact, while the population of B11C icosahedron is reduced by the replacements of B12 icosahedron. This observation is fundamentally different from the existing model of boron-rich boron carbide. The localized states associated with missing boron atoms are identified and the electrical conductivity through these localized defects states is studied.
The Microstructure and Wear Behavior of Cr- and W-DLC Coatings Sputter-Deposited onto AISI 52100 Substrates as Elucidated using Focused-Ion-Beam SEM
Authors: Cooper Clark V. , Wang Rizhi , Yoon Hyung K. , Taher Mahmoud A. 
Published: April 2011

AbstractMagnetron sputtering has been used to deposit metal-containing, diamond-like-carbon (Me-DLC) coatings onto substrates composed of AISI 52100 steel in quenched-and-tempered condition. Coatings of two distinctly different compositions, one containing Was the metallic constituent and the second containing Cr, have been deposited in a plasma containing Ar and C2H2.Interrupted, unidirectional sliding experiments of the block-on-ring type have been conducted in a poly-alpha-olefin (PAO) lubricant at a load of 667 N for discrete numbers of cycles, N, of between 10 and 1000. Focused-ion-beam, scanning electron microscopy (FIB/SEM) has been applied to characterize the morphology of as-deposited and worn Me-DLC coatings. This technique has resulted in the determination that the Cr-DLC coating, deposited using the investigated processing parameters, fractures in a brittle manner through the formation and propagation of “tunnel cracks,” which unzip in a direction parallel to the grinding direction outside of the region of contact. Conversely, the application of specific processing parameters to deposit W-DLC produces a coating that wears by gradual recession, consistent with polishing wear. First-principles-based analysis shows that the state of residual stress is critically important in the behavior of the coating.
Low friction W-C:H coatings for wear resistance in roller bearings
Authors: Kacsich Thorsten , Gold Peter Werner , Loos Jörg 
Published: April 2011

AbstractLife time limiting effects in roller bearings and gear wheel applications are wear, sizing, and fatigue damages like micro pitting. These mechanisms are related to a number of parameters: lubrication conditions, surface roughness, and the hardness of the bulk material. Nowadays, Me-DLC coatings like MAXITÓ W-C:H offer surface protection under dry, mixed, and hydrodynamic conditions. This allows the increase of load capacities, respectively the decrease of gearing size. Moreover, a reduction of toxic lubrication additives can be achieved. The performance of the MAXITÓ W-C:H coatings in roller bearings was investigated on the FE8 test rig under mixed friction conditions. The W-C:H was deposited via the PVD technique of magnetron sputtering onto case hardened steel. The coating thickness was varied from 1.5 to 5 m m with respect to optimised wear resistance. The wear was drastically reduced by powers of ten as compared to uncoated roller bearings.
Laser Writing of Nanostructures on Magnetic Film Surfaces With Optical Near Field Effects
Authors: Huang S. M. , Hong M. H. , Luk'yanchuk B. S. , Song W. D. , Lu Y. F. , Chong T.C. 
Published: April 2011

AbstractLaser directly writing of nanostrucrures on magnetic film surfaces with optical near field effects has been investigated. Spherical 0.99 m or 0.47 m silica particles were placed on Cr/CoCrPt multilayers. After laser illumination with an excimer laser for a single shot, pits were obtained at the original position of the particles using different laser fluences or particle size parameters. The mechanism of the formation of nanostructure pattern was discussed and found to be the near-field optical resonance effect induced by particles on the surface. A comparison with accurate theoretical calculations of near-field light intensity distribution showed good agreement with the experiment results. The method of particle enhanced laser irradiation allows the study of field enhancement effects as well as its potential applications for nanolithography.
Resist Requirements for Electron Projection and Direct Write Nanolithography
Authors: Ocola Leonidas E. 
Published: April 2011

AbstractThis paper will discuss aspects of resist properties required for nanolithography using high-energy electrons. A comprehensive image formation model is presented for positive and negative chemically amplified resists where most aspects have been considered (from exposure through development) for e-beam nanolithography (EPL, DWL). A series of optimization studies are performed using the modulation of soluble site density after PEB as a metric to characterize resist imaging performance. Base loading, blocking fraction and acid diffusion properties are investigated. Slower acid diffusion near regions with deprotected sites dominates during PEB and contributes to a sharp image modulation. Electron beam exposed nanostructures exhibit spatial fluctuations of soluble sites in the material left after development, which may alter etch resistance and pattern collapse. Soluble site fluctuations arise from the low statistics involved in the image formation and are significant contributors to the sidewall roughness.
Towards the Use of Biologically Inspired Techniques for the Assembly of Electronic Devices
Authors: McNally H. , Pingle M. , Lee S. W. , Guo D. , Bergstrom D. , Bashir R. 
Published: April 2011

AbstractNature assembles nano-scale components using molecular recognition. In the case of DNA, hydrogen bonding is the driving force behind the matching of complementary pairs of single-stranded (SS) DNA to hybridize into a double strand of helical DNA. For the case of antibodies/antigens and ligands/receptors, binding takes places by a combination of electrostatic forces, chemical bonding, and shape mediated effects. In this project, the assembly of micron sized and smaller particles using biologically inspired events such as DNA hybridization and interactions of ligands and receptors is being investigated. Following the case of DNA, a single strand sequence can be attached to the device surfaces, which is complementary to a single strand sequence previously attached to a patterned surface. Using the natural hybridization of DNA, the devices are expected to assemble in solution as designed onto the substrate surface. Single strands of DNA can be used to provide charge on the devices so that long-range electrostatic forces may be used to bring the devices close to the assembly site. We have also used a less complex molecule to add negative charges to the particles allowing them to be guided into place using electric fields. Attachment of these molecules to surfaces is a critical step in the assembly process. Various factors affecting the attachment are being investigated and will be reported. These include sample preparation and conditions for attachment. We have used polystyrene beads as test objects and optimized the capture of the beads using DNA and Avidin/Biotin interactions. When successful, this approach can be used to assemble micro and nano-scale electronic circuitry including heterogeneous integration of materials. Y6.5.1
Planar Molecular and Macromolecular Gradients: Preparation and Properties
Authors: Genzer J. , Wu T. , Efimenko K. 
Published: April 2011

AbstractWe present a method for fabricating polymer brushes with a gradual variation of grafting density on solid substrates. The technique for generating such structures consists of: i) deposition of a molecular gradient of polymerization initiator on the solid substrate, and ii) polymerization from the substrate bound initiator centers (“grafting from”). In this publication we describe the preparation of gradient polymer brushes of poly(acryl amide) on silica-covered substrates. We show that the polymer density within the gradient polymer brush can be varied by controlling the polymerization time.
Optical Studies of Artificial Opals as 3D Photonic Crystals
Authors: Comoretto D. , Cavallo D. , Dellepiane G. , Grassi R. , Marabelli F. , Andreani L.C. , Brabec C.J. , Andreev A. , Zakhidov A.A. 
Published: April 2011

ABSTRACTArtificial opal films have been prepared by sedimentation of monodisperse silica spheres in water suspension. Atomic force microscope images show a triangular packing of the spheres at the surface of the films. The presence and the energy position of an optical pseudo gap in incidence-angle-dependent transmittance and reflectance spectra is observed and accounted for by theoretical calculations of the photonic band structure. These calculations indicate that the pseudo gap is due to the splitting of the photonic bands in the L point of the Brillouin zone. The spectroscopic data show additional loss structures due to both other features of the Brillouin zone and the diffraction of the light from the regular surface of the sample. The effect of the infiltration of opals with polydiacetylene solutions is also reported.