bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of A-(Si,Ge) Materials and Devices grown using Chemical Annealing
Authors: Shyam Ashutosh , Congreve Daniel , Noack Max , Dalal Vikram 
Published: September 2011

ABSTRACTChemical annealing is a powerful technique for controlling H bonding and optical absorption in amorphous semiconductors. We have shown previously that the use of careful chemical annealing by Argon can lower the bandgap of a-Si:H while maintaining electronic properties in both films and devices. In this work, we describe new work on chemical annealing of A-(Si,Ge):H films and devices. The technique consists in growing very thin layers (1-3 nm) of A-(Si,Ge) from mixtures of hydrogen, Silane and Germane, and then subjecting this thin layer to ion bombardment by Ar. The cycle is repeated many times to achieve the desired thickness of the intrinsic layer. The resulting film and device were measured for their composition using energy dispersive spectroscopy (EDS) analysis. We discovered that the composition itself, namely the Ge:Si ratio in the film, could be varied by changing the ion bombardment conditions. Lower energy bombardment led to a higher Ge:Si ratio for the same germane/Silane ratio in the gas phase. By controlling ion bombardment during the Ar annealing cycle, we were able to reduce the H content of the film and achieve good electronic properties. It will be shown that by appropriate control over ion energies, one can obtain films and devices which are of good quality and low bandgap as well.
Silicon Thin-Films from Nanoparticle dispersion: Tailoring Morphological, Electrical and Optical Characteristics.
Authors: Drahi Etienne , Blayac Sylvain , Benaben Patrick 
Published: September 2011

ABSTRACTAmorphous and microcrystalline silicon are currently used for electronic devices such as solar cells and thin-film transistors. This paper shows that silicon nanoparticle dispersion has the potential to be used as source material for polycrystalline silicon thin-film thus opening a route to solution processed silicon devices. After deposition, a classical thermal or microwave annealing step is used to induce the coalescence of the silicon nanoparticles. Both sintering techniques are studied in terms of morphology, electrical and optical properties.
Photoluminescence of Surface Modified Silicon Carbide Nanowires
Authors: Stewart Polite D. , Rich Ryan , Nemashkalo A. , Zerda T. W. 
Published: September 2011

ABSTRACTSiC nanowires were produced from carbon nanotubes and nanosize silicon powder in a tube furnace at temperatures between 1100°C and 1350°C. SiC nanowires had average diameter of 30 nm and very narrow size distribution. The surface of the SiC nanowires is covered by an amorphous layer composed of amorphous SiC and various carbon and silicon compounds. The objective of the research was to modify the surface structure of the SiC nanowires, a step necessary for future surface functionalization. The acid etched nanowires were analyzed using FTIR, TEM, x-ray diffraction, and photoluminescence. The concentration of Si-Ox groups in untreated specimens was estimated to account for 1% of the total mass of a 2 nm thick amorphous layer wrapping around all structures. After treatment in HF this concentration was negligibly small. TEM images show that after treatment the amorphous layer was removed but the diameter of the core remained unchanged. The surface was roughened and multiple pits formed on that surface. X-ray line broadening analysis indicates a significant contribution due to stress caused by dislocations and planar faults. After acid etching line narrowing was observed and attributed to stress reduction and elimination of the smallest wires. The photoluminescence signal from as received samples was very weak but increased greatly after acid treatment, indicating that the signal is related to surface defects. Measurements at low temperatures, 8 K, showed peaks due to point and planar defects.
III-V CMOS technologies on Si platform
Authors: Takenaka M. , Takagi S. 
Published: September 2011

ABSTRACTThe heterogeneous integration of III-V semiconductors with the Si platform is expected to provide high performance CMOS logic for future technology nodes because of high electron mobility and low electron effective mass in III-V semiconductors. However, there are many technology issues to be addressed for integrating III-V MOSFETs on the Si platform as follow; high-quality MOS interface formation, low resistivity source/drain formation, and high-quality III-V film formation on Si substrates. In this paper, we present several possible solutions for the above critical issues of III-V MOSFETs on the Si platform. In addition, we present the III-V CMOS photonics platform on which III-V MOSFETs and III-V photonics can be monolithically integrated for ultra-large scale electric-optic integrated circuits.
Feasibility studies of using PED deposited Sn-doped In2O3 Films for Organic Electronic Devices
Authors: Kotru Sushma , Frazier Rachel M. , Chen Mengwei , Nampoori Harshan V. , Daly Daniel T. 
Published: September 2011

ABSTRACTIn this work, pulsed electron deposition was used to prepare thin films of ITO on plastic substrates. These films were used as electrodes for organic photovoltaic devices to determine the feasibility of using PED deposited ITO as electrodes. ITO films deposited on plastic showed optical transmission values as high as 85% for films deposited at high pressures. Films deposited on plastic substrates were further used to prepare a test organic solar cell, with ITO as the bottom electrode. The device performance was seen to depend on the quality of the ITO electrode, and the ITO film deposited at the lowest oxygen pressure was found to be the best electrode for the organic photovoltaic device.
RF-Sputtered ZnO Thin Films: The Tailoring of Structural, Electrical and Optical Properties
Authors: Besleaga Cristina , Stan George E. , Ion Lucian , Antohe Stefan 
Published: September 2011

ABSTRACTWe report on the influence of radio-frequency magnetron sputtering variables (working pressure and deposition atmosphere) and post-deposition thermal treatment processing upon the structural, optical and electrical properties of c-axis highly textured ZnO thin films. The films’ crystallinity increased progressively with argon pressure for the inert atmosphere experiments and with the oxygen dilution in the working atmosphere (up to 10%) for the reactive atmosphere experiments. The post-deposition annealing treatment at 450°C/1h in air reduced the strain in the ZnO films and enhanced their crystallinity and texturing. The ZnO films had an average transmittance of ∼90% in visible range and an average band-gap of ∼3.4 eV, regardless of the sputtering variables used. The samples prepared at the higher argon pressure (0.45 Pa) had a resistivity with one order of magnitude smaller than the samples prepared at the lower pressures.
Modeling the Sputter Deposition of Thin Film Photovoltaics using Long Time Scale Dynamics Techniques
Authors: Blackwell S. , Smith R. , Kenny S. D. , Walls J. M. 
Published: September 2011

ABSTRACTResults are presented for modeling the deposition of Ag and rutile TiO2. The model can be used to examine the effect of varying experimental parameters, such as the substrate bias in the magnetron and the stoichiometry of the deposition species. We illustrate how long time scale dynamics techniques can be used to model the process over experimental time scales. Long time dynamics is achieved through an on-the-fly Kinetic Monte Carlo (otf-KMC) method, which determines diffusion pathways and barriers, in parallel, with no prior knowledge of the involved transitions. Using this otf-KMC method we have modeled the deposition of Ag and TiO2 for various plasma deposition energies, in the range 1 eV to 100 eV. It was found that Ag {111} produces the most crystalline growth when deposited at 40 eV. TiO2 growth showed that at energies of 1 eV and 100 eV a porous structure occurs with void formation. At deposition energies of 30 eV and 40 eV, a more dense and crystalline rutile growth forms. The results show that deposition energy plays an important role in the resulting thin film quality and surface morphology.
ATMOSPHERIC PRESSURE MICROWAVE PLASMA ENHANCED COATING OF CARBON NANOTUBE RIBBONS
Authors: Kotecha Rutvij , Davison Gilpin A. , Jayasinghe Chaminda , Schulz Mark , Shanov Vesselin 
Published: September 2011

ABSTRACTCNT arrays were synthesized by Chemical Vapor Deposition (CVD) and spun into ribbons, which were coated using Atmospheric Pressure Microwave Plasma system. Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) characterization of CNT ribbons indicated the presence of polymer films with CF2 as a repeat unit. Atomic concentration of C, F and O in the coated films was estimated from X-ray Photoelectron Spectroscopy (XPS) data. Types of bonding between the elements in the coated films was studied by curve fitting of C 1s XPS spectra.
Vacuum Deposited Erbium-Doped NIR Luminescent Organic Thin Films For 1.5 μm Optical Amplification Applications
Authors: Divay Laurent , Galindo Christophe , Chastaing Evelyne , Bisaro Renato , Wyczisk Frédéric , Le Barny Pierre 
Published: September 2011

AbstractInorganic erbium-doped glasses are widely used in telecommunications due to the sharp intra-atomic 4I13/2 → 4I15/2 transition in the 4f orbital of erbium resulting in an emission at ∼ 1.5 μm, which is the low loss window of silica optical fibres. The limited erbium concentration of about 1020 ions.cm−3 in inorganic erbium-doped glasses and the low absorption coefficient of the Er3+ ions, imply that relatively long lengths of fibre are required. The organic erbium complexes present higher absorption cross sections due to the photosensitization of erbium by organic conjugated ligands and broader emission bands than those of the free Er3+ ion. Such properties open the possibility to develop compact, low power and broadband infrared emitting devices. We present the study of a highly doped organic thin film obtained from organic erbium complexes deposited by a vacuum sublimation technique. This deposition method allows the realization of an erbium-doped thin film without the help of an organic polymer matrix, which is a potential source of vibrationnal luminescence quenching. The ligands used in the present study are fluorinated in order to limit the vibrationnal quenching of the ligand itself, and to increase the volatility of the complexes. In this paper, we report the synthesis, the sublimation process and the characterization of the thin films.
Nanotextured Electrical Immunoassays for Ultrasensitive Protein Detection
Authors: Mertz Timothy O. , Vattipalli Krishna , Barrett Tom , Carruthers John , Prasad Shalini 
Published: September 2011

ABSTRACTThis paper describes the development of nanomonitors, which are electrical immunoassays for detection of multiple protein biomarkers. These devices are hybrid sensors with micro-fabricated electrode arrays on a silicon substrate, and integrated nanoporous alumina membranes to provide protein confinement and signal amplification. The disease biomarkers C-reactive protein and Myeloperoxidase have been detected by the nanomonitors in ultra-low concentrations. Proteins were detected in pure samples, human serum, and patient blood samples. The detection accuracy and sensitivity of the nanomonitors in patient samples was comparable to the Enzyme Linked Immunosorbent Assay (ELISA) method of protein detection. Nanomonitors provide the additional benefits of being rapid, label-free, sensitive, and cost effective, providing improvements over traditional protein detection methods, and having potential applications in disease diagnosis.
Recent Progress in Thermoelectric Power Generation Systems for Commercial Applications
Authors: LaGrandeur John W. , Bell Lon E. , Crane Douglas T. 
Published: September 2011

ABSTRACTThermoelectric (TE) devices are solid state heat engines that directly convert thermal to electrical power (Seebeck Effect) and the reverse, electrical to thermal power (Peltier Effect). The phenomena were first discovered over 150 years ago and until recently have been more of a scientific curiosity than a practical technology of commercial interest. However, as governments impose regulations on greenhouse gas emissions and as the long-term availability of fossil fuels is questioned, alternative technologies, including thermoelectrics, are being explored to meet the challenges that arise from these new conditions.Amerigon, the parent of BSST, is the largest supplier of thermoelectric (TE) devices to the automotive market. Over the last ten years BSST has been developing TE technology for the transportation market. Recent advancements at the system level made by BSST and improvements in TE materials made by several organizations indicate a path to improved performance and economic feasibility. This report discusses development of TE Generator (TEG) technology and of a TEG system installed in the power train of internal combustion engines for the purpose of converting waste heat to electric power. Our work has been made possible, in part, through sponsorship by the United States Department of Energy Office of Vehicle Technologies. The BMW Group, Ford Motor Company and Faurecia are partners in the BSST-led program.
Semimetal-Semiconductor Transitions in Semimetal Bismuth-Antimony Nanowires Induced by Size Quantization, Strain, and Magnetic Field
Authors: Nikolaeva Albina A. , Konopko Leonid A. , Huber Tito E. , Bodiul Pavel P. , Popov Ivan A. , Moloshnik Eugen F. 
Published: September 2011

ABSTRACTIn this work, we study glass-coated single-crystal Bi98Sb02 wires obtained by liquid phase casting.Semimetal Bi98Sb02 nanowires exhibited a "semiconductor" behavior of the temperature dependence R(T) for wire diameters <400 nm, which is significantly higher than the critical diameter (70 nm) for similar dependences R(T) of pure bismuth nanowires. The thermopower sign reversal in the temperature dependence α(T) was found to depend on the wire diameter d. The effect is interpreted in terms of manifestation of the quantum size effect, based on the appearance a new scattering channel stimulated by fluctuations in the diameter d.The effect of negative magnetoresistance in a perpendicular magnetic field was observed for the first time both at H | | C3 and H | | C2 in magnetic fields of 1 T.It is shown that a semimetal-semiconductor transition can be controlled using an elastic strain and a strong magnetic field, which lead to a significant shift of the band boundaries of the energy extrema in the bands
Simultaneous gene delivery and tracking of cells using fluorescent upconversion nanoparticles for cell therapy
Authors: Jayakumar Muthu Kumara Gnanasammandhan , Zhang Yong 
Published: September 2011

ABSTRACTCell therapy has attained new heights with the current developments in the field of stem cell therapy and is often done in combination with gene therapy. Much research has gone into developing safe vectors to deliver genes to the cells used for cell therapy and also in tracking the transplanted cells and determining their fate. Even though viral vectors are very efficient in gene delivery, there are major safety concerns related to it. Herein, we report the use of novel fluorescent upconversion nanoparticles (UCNs) for simultaneous gene delivery and tracking of cells for cell-based therapies. It is a safe alternative to viral vectors and offers imaging capabilities too, which will give an insight on the fate of transplanted cells.
Ion Irradiation on Phase Change Materials
Authors: Rimini Emanuele , Carria Egidio , Mio Antonio Massimiliano , Miritello Maria , Gibilisco Santo , Bongiorno Corrado , D’Arrigo Giuseppe , Spinella Corrado , D’Acapito Francesco , Grimaldi Maria Grazia 
Published: September 2011

ABSTRACTIon irradiation with 130 keV Ge+ or 120 keV Sb+ has modified, by thermal spike effect, the local atomic arrangement in the structure of as-deposited sputtered amorphous GeTe and Ge2Sb2Te5 thin films. The changes in the local order have been analyzed by Raman and EXAFS spectroscopy. In addition the crystallization kinetic, measured by “in situ” time resolved reflectivity and optical microscope analysis, is found to be faster in the irradiated samples. The nucleation rate and the grain growth velocity are enhanced by a factor of about ten with respect to the unirradiated samples in the investigated temperature range (120°C –170°C).
Post-CMOS Integration of Nanomechanical Devices by Direct Ion Beam Irradiation of Silicon
Authors: Pérez-Murano Francesc , Rius G. , Llobet J. , Borrisé X. 
Published: September 2011

ABSTRACTWe present the development of CMOS compatible focused ion beam (FIB)-based method for the fabrication of nanomechanical devices. With only two step process, (i) patterning by direct exposure of silicon by the gallium beam and (ii) transfer of features to the structural layer by standard microfabrication silicon etching processes, operational devices are obtained. The ion beam modified silicon, acting as the etching mask, presents an outstanding robustness for both chemical and reactive ion etching process, enabling a simplified fabrication of nanomechanical devices with sub-micron resolution. As an example, single and double clamped silicon beams have been successfully produced. The compatibility check to guarantee the integrity of the electronic performance of CMOS circuits after the energetic beam irradiation is also investigated. Patterning based on direct ion beam exposure of silicon and etching presents advantages in comparison with more conventional lithography methods, such as electron beam lithography, since it is realized without the use of any resist media, which is especially challenging for the non-flat CMOS pre-fabricated substrates.
Structural Changes Induced by Swift Heavy Ion Beams in tensile strained Al (1-x)InxN /GaN Hetero-structures
Authors: Devaraju G. , Pathak Anand P. , Srinivasa Rao N. , Saikiran V. , Sathish N. , Nageswara Rao S. V.S 
Published: September 2011

ABSTRACTWe report here swift heavy ion (SHI) irradiation induced effects on structural and surface properties of III-nitrides. Tensile strained Al(1-x)InxN/GaN Hetero-Structures (HS) were realized using Metal Organic Chemical Vapour Despotion (MOCVD) technique with indium composition as 12%. Ion species and energies are chosen such that electronic energy deposition rates differ significantly in Al(1-x)InxN and are essential for understanding the ion beam interactions at the interfaces. Thus the samples were irradiated with 80 MeV Ni6+ and 100 MeV Ag7+ ions at varied fluence (1×1012 and 3 ×1012 ions/cm2) to alter the structural properties. Under this energy regime, the structural changes in Al(1-x)InxN would occur due to the intense ultrafast excitations of electrons along the ion path. We employed different characterization techniques like High Resolution X- ray Diffraction (HRXRD) and Rutherford back scattering spectrometry (RBS) for composition, thickness and strain. HRXRD and RBS experimental spectra have been fitted with Philip’s epitaxy SIMNRA code, which yields thickness and composition from compound semiconductors. The surface morphology of pristine and irradiated samples is studied and compared by Atomic Force Microscopy (AFM).
Ion Beams for synthesis and modification of nanostructures in semiconductors
Authors: Pathak Anand P. , Srinivasa Rao N. , Devaraju G. , Saikiran V. , Nageswara Rao S. V. S. 
Published: September 2011

ABSTRACTSwift heavy ion irradiation is one of the most versatile techniques to alter and monitor the properties of materials in general and at nanoscale in particular. The materials modification can be controlled by a suitable choice of ion beam parameters such as ion species, fluence and incident energy. It is also possible to choose these ion beam parameters in such a way that ion beam irradiation can cause annealing of defects or creation of defects at a particular depth. Here, we present a review of our work on swift heavy ion induced modifications of III-V semiconductor heterostructures and multi-quantum wells in addition to synthesis of Ge nanocrystals using atom beam co-sputtering, RF magnetron sputtering followed by RTA, swift heavy ion irradiation, respectively. We also present the growth of GeO2 nanocrystals by microwave annealing. These samples were studied by using XRD, Raman, PL, RBS and TEM. The observed results and their explanation using possible mechanisms are discussed in detail.
Biocompatible luminescent nanoparticles on the basis of calcium phosphate
Authors: Dembski Sofia , Milde Moritz , Dassonneville Emeline , Gellermann Carsten , Klockenbring Torsten , Dyrba Marcel , Schweizer Stefan 
Published: September 2011

ABSTRACTLuminescent lanthanide doped SiO2/Hydroxylapatite (HAp) core/shell nanoparticles (NPs) were synthesized by sol-gel technology. The resulting NPs exhibited an amorphous SiO2 core and a crystalline luminescent shell. The formation of the HAp layer was possible at pH 8.5. The characterization of the resulting NPs was done by transmission electron microscopy, X-ray diffraction analysis, inductively-coupled plasma combined with optical emission spectrometry, and photoluminescence spectroscopy. Additionally, the newly developed SiO2/HAp:Ln3+ core/shell NPs were tested for their biocompatibility, e. g. by an in vitro cell culture based assay.
How do different surface modification strategies affect the properties of MnO nanoparticles for biomedical applications? Comparison of PEGylated and SiO2-coated MnO nanoparticles
Authors: Schladt Thomas D. , Koll Kerstin , Bauer Heiko , Weber Stefan , Schreiber Laura M. , Tremel Wolfgang 
Published: September 2011

ABSTRACTMnO nanoparticles (NPs) were surface functionalized by two different approaches, (1) using a dopamine-poly(ethylene glycol) (PEG) (DA-PEG) ligand and (2) by encapsulation within a thin silica shell applying a novel approach. Both MnO@DA-PEG and MnO@SiO2 NPs exhibited excellent long-term stability in physiological solutions. In addition, the cytotoxic potential of both materials was comparatively low. Furthermore, owing to the magnetic properties of MnO NPs, both MnO@DA-PEG and MnO@SiO2 lead to a shortening of the longitudinal relaxation time T1 in MRI. In comparison to the PEGylated MnO NPs, the presence of a thin silica shell led to a greater stability of the MnO core itself by preventing excessive Mn ion leaching into aqueous solution.
Structural and Magnetic Properties of Cobal Ferrite - Barium Titanate Nanotube Arrays
Authors: Bueno-Baques Dario , Corral-Flores Veronica , Morales-Carrillo Norma A. , Torres Alejandro , Camacho-Montes Hector , Ziolo Ronald F. 
Published: September 2011

ABSTRACTCobalt Ferrite/Barium Titanate nanotube arrays were obtained in anodic aluminum oxide templates (AAO) of 100 nm pore diameter by a two step sol-gel process. Each phase was grown in several wetting – drying cycles starting from the cobalt ferrite layers with the barium titanate on top. As-dried composite structures were sintered at 700 C. The composite nanotubes showed a fine polycrystalline microstructure with an average grain size of 5 nm. The formation of both spinel and perovskite structures was verified by High Resolution Transmission Electron Microscopy (HR-TEM) on isolated nanotubes. The growing rate by layer was found to be lower for the BaTiO3 on top of CoFe2O4 than the later on top of the AAO. Wall sizes were estimated by Z-contrast as 9.8 nm for one layer of CoFe2O4 and 6.6 nm for six layers of BaTiO3. Magnetic properties were studied by VSM. Samples showed ferromagnetic behavior with low coercive values. By means of a finite element model the deformation and stress on the piezoelectric phase was estimated and used to simulate the magnetization reversal under stress in the composite nanotubes, using an updated micromagnetic framework to include the magnetostriction effect. Simulation results showed that a curling mode is expected with opposite vortex states at the end of the nanotubes. The change in the vortex domain structure under voltage driven applied stress is presented and discussed.