bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amorphous Ta-N as a Diffusion Barrier for Cu Metallization
Authors: Dalili Neda , Liu Qi , Ivey Douglas G. 
Published: September 2011

ABSTRACTAmorphous Ta-N thin films (14 and 62 nm thick) are deposited on Si substrates by reactive magnetron sputtering followed by Cu film deposition. The interlayer reaction and failure mechanism of the annealed metallization stacks are investigated by resistance measurements, xray diffraction (XRD) and detailed electron microscopy analysis accompanied with electron energy-loss spectroscopy (EELS). Amorphous Ta-N crystallizes at 600°C by a polymorphous transformation to Ta2N. The crystallized Ta2N barrier prevents Cu-Si interaction and intermixing up to 700-800°C, depending on the barrier thickness. Copper appears to be the main diffusing species and reacts with Si at the Ta-N/Si interface to form η˝-Cu3Si. Local Cu-Si reaction enhances the formation of TaSi2 precipitates. Silicon also diffuses, though at a much slower rate, to the surface and reacts with Cu. Local oxidation of Cu3Si occurs upon exposure to air, accompanied by SiO2 formation.
Growth of Ultra-High Density 3C-SiC Nanowires via Single Source CVD
Authors: Teker Kasif , Oxenham Joseph A. 
Published: September 2011

ABSTRACTSilicon carbide (SiC) nanostructures attract interest due to their applications in optoelectronic devices, sensors, and high-power/high temperature electronics. The synthesis of SiC nanowires by chemical vapor deposition using hexamethyldisilane (HMDS) as a source material on SiO2/Si substrate has been investigated. Various catalyst materials, including iron (film and nanoparticles), nickel (film and nanoparticles), and cobalt nanoparticles have been used. The growth runs have been carried out at temperatures between 900 and 1100°C under H2 as carrier gas. 3C-SiC nanowires have successfully been grown at even lower temperatures despite the lower efficiency of source decomposition at low temperatures. The SiC nanowire diameters are in the range of 8 nm to 60 nm, as determined by transmission electron microscopy (TEM). In general, the efficiency of nanowire growth has increased with temperature except the growth on Ni film, which has occasionally resulted in SiC flowers. Higher nanowire density at high temperatures can be attributed to more efficient decomposition of the source at higher temperatures. Further, optical properties of the nanowires have been studied by Fourier transform infrared spectroscopy (FTIR). The fabricated nanowires have also been characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray diffraction (XRD).
How to Grow a Startup Company – Nano or Otherwise
Authors: Cesario Frank J. 
Published: September 2011

ABSTRACTNew ventures in the nanomaterials industry are subject to the same laws of physics as all other entities – they compete for capital, customers, and work through similar variables. Ultimately, success is determined by the degree to which customers prefer the new venture product(s) to alternatives, thus, thinking from the perspective of the customer is critical to success. Often we focus on what the idea is, how it improves on alternatives in the marketplace, and don’t spend adequate time considering the world from the customer’s view. In reviewing choices that must be made and examples of successes and failures, the case for a thorough business plan is presented.
Modeling of approximated electron transport across ion beam patterned quantum dot nanostructures
Authors: Lassiter J. , Chacha J. , Muntele C. , Budak S. , Elsamadicy A. , ILA D. 
Published: September 2011

AbstractHigh energy ion beams are used to modify co-deposited nanolayer films of alternated materials (e.g. insulator and metal, two different semiconductors, even more complex arrangements) to form nanodots through localized nucleation. The particular application being considered here is for high efficiency thermoelectric conversion systems. The performance of a thermoelectric converter is generally given by the figure of merit, ZT, which is a function of the Seebeck coefficient, electrical conductivity, and thermal conductivity. A high performance device would have a maximized electrical conductivity and a minimized thermal conductivity (maximum electron transport, minimal phonon transport). The current models of electron and phonon transportation through 1D, 2D, 3D quantum regimented structures assume an infinitely repetitive perfect structural “cell”, with complicated algorithms requiring intensive computing power. The main focus for this modeling effort is to reduce the three-dimensional problem to a single dimensional approximation without sacrificing the quality of the result. The nanostructure being investigated has Si and Ge quantum dots arranged with perfect periodicity in all three Cartesian directions, with the heat and electricity flow monitored in the z-direction (cross-plane as initially layered). Non-Equilibrium Green’s Functions Formalism (NEGF) is the mode for calculating the theoretical electrical properties assuming a one-dimensional quantum well arrangement in the z-direction (with finite boundaries in the x and y directions) with tight binding (nearest neighbor approximation). The results are to be compared with experimental measurements on such structures.
High Performance Nanostructured Coatings and Nanopowders by NanoSpraySM Combustion Processing
Authors: Jiang Yong Dong , Venugopal Ganesh , White Marvis , Choi Kwang , Hunt Andrew T. 
Published: September 2011

ABSTRACTnGimat has commercialized a number of nanotechnology applications with all being based on its core competence of fabricating low cost high quality nanomaterials. The company offers a wide range of compositions as coatings and also in both nanopowder and dispersion forms. A few of these nanomaterials and applications will be covered as examples including superhydrophobic coatings, various nanopowders (including Li-battery based), high temperature thin wire coatings, and tunable RF components.The combustion chemical vapor deposition (CCVD) technique, which is the thin film NanoSpraySM combustion process, can be easily scaled up to large substrates and integrated into an existing production line, thus enabling a license business model. The combustion chemical vapor condensation (CCVC) technique or NanoSpraySM CCVC (nCCVC), which is the nanopowder NanoSpraySM combustion process, is also readily scalable. The manufacture of these nanopowder based products is internationally competitive even when made in the USA.
Emerging Potential and Challenges of Convergence, Heterogeneity, and Hierarchical Integration of Nanotechnologies in Commercial Applications
Authors: Vaseashta Ashok 
Published: September 2011

ABSTRACTParadigmatically, the convergence of science has exceptionally high potential for transforming the manner in which state-of-the-art information is gathered, analyzed, and leveraged to enable future advances and applications. Highlighting the potential and challenges of hierarchically integrating nanotechnologies is essential for realizing commercial applications. The heterogeneity of structures and compositions of nanomaterials present limitless possibilities; yet these envisioned benefits may be accompanied by certain technological limitations of integrating nanomaterials in commercial products. A balanced overview is presented of the realistic capabilities and potential, as well as the limitations, challenges of system engineering nanomaterials in platform integration. Examples of integrating nanomaterials in useable platforms are also presented. Most notably, the review suggests that nanomaterial based systems and devices that do not require a nano to micro/macro interface integration have reached commercialization whereas those needing a nano-to-micro/macro interface require further investigations. These selected studies provide an insight in obstacles and challenges presented by hierarchical integration of nanomaterials in commercial systems/devices and are crucial for commercialization as the research transitions from laboratory to marketplace, having the potential to transform into a multi-billion dollar niche market.
A Finite Element Model of Self-Resonating Bimorph Microcantilever for Fast Temperature Cycling in A Pyroelectric Energy Harvester.
Authors: Mostafa Salwa , Lavrik Nicolay , Bannuru Thirumalesh , Rajic Slo , Islam Syed K. , Datskos Panos G. , Hunter Scott R. 
Published: September 2011

ABSTRACTA self resonating bimorph cantilever structure for fast temperature cycling in a pyroelectric energy harvester has been modeled using finite element method. Effect of constituting material properties and system parameters on the frequency and magnitude of temperature cycling and the efficiency of energy recycling using the proposed structure has been investigated. Results show that thermal contact conductance and heat source temperature play a key role in dominating the cycling frequency and efficiency of energy recycling. Studying the performance trend with various parameters such as thermal contact conductance, heat source temperature, device aspect ratio and constituent material of varying thermal conductivity and expansion coefficient, an optimal solution for most efficient energy scavenging process has been sought.
Ozone Treatment on Nanoporous Ultralow Dielectric Materials to Optimize their Mechanical and Dielectrical Properties
Authors: Kang Il-Yong , Shin Bo-Ra , Rhee Hee-Woo 
Published: September 2011

ABSTRACTThe continual miniaturization of microprocessors has resulted in increased RC delay and cross talk noise. To solve these problems ultralow nanoporous dielectric materials are required but have not developed yet. To develop ultralow dielectric materials with required mechanical and dielectrical properties for next generation semiconductors, it is essential to control the pore size in nm range and its morphology by preventing porogen aggregation. Thus we have used ozone treatment during thermal curing process of the nanoporous dielectrics in order to increase the reactivity between the matrix and reactive porogens and to possibly induced changes in Si bond structures.Ozone treatment was quite effective in enhancing the reactivity of the low-k matrix and the reactive porogen, which converted effectively the alkoxy or alkyl groups into Si-OH groups, which mostly converted to the formation of Si-O-Si network structures. Therefore, ozone treatment greatly increased modulus up to 11.25 GPa at the same porogen loading (60 vol%). The modulus increased by more than 23% compared with non-treated samples (9.1 GPa). The porosity of the ozone-treated sample reduced to 19.3 vol% at the same porogen loading. Solid state Si-NMR showed that less porosity was related to the breakage of methyl groups in the matrix by ozone irradiation, which also resulted in a little sacrificed dielectric constant.In general, the mechanical properties of nanoporous dielectrics deteriorate sharply above certain high porosity ca. 15 ~20 vol% due to non-uniform distribution of nanopores, their aggregation and resultant open pores. Therefore, this result may suggest the possibility of increasing mechanical properties of nanoporous dielectrics. However, we need to experimentally control processing variables such as irradiation time, intensity, temperature and so forth in order to optimize both mechanical and dielectrical properties.
Optical Interconnect Technologies based on Silicon Photonics
Authors: Bogaerts Wim , Absil Philippe , Van Thourhout Dries , Van Campenhout Joris , Selvaraja Shankar Kumar , Dumon Pieter , Yu Hui , Masood Adil , Roelkens Gunther , Baets Roel 
Published: September 2011

ABSTRACTWe discuss the principles of Optical interconnects, and discuss the potential of silicon photonics to provide all the necessary building blocks to construct dense, high-bandwidth, lowpower optical links. We discuss waveguides, wavelength division multiplexing, modulators and photodetectors. We also take a look at the options for implementing light sources, a function which silicon cannot natively provide, with a focus on implementations in the IMEC silicon photonics platform.
Two-stage Laser Thermal Processing of Nanoparticle Inks on Flexible Substrates for High Performance Electronics
Authors: Willemann Michael H. , Thompson Michael O. 
Published: September 2011

ABSTRACTZinc oxide is a promising semiconductor film for active devices on flexible substrates, and synthesis routes using nanoparticle inks enable greater variety of applications. We introduce and characterize a two-step transient laser annealing process to create fully densified zinc oxide films from nanoparticle ink precursors. A low temperature sub-millisecond calcining step to remove solvent and organic stabilizing ligands was followed by a high-temperature pulsed laser sintering step to form densified 50-100 nm thin films with resistivities of 10-1 to 10-3 Ω-cm. Film microstructures can be varied between crystalline and amorphous without significant film damage by adjusting the fluence of the high-temperature sintering step. These processes would be compatible with a variety of nanoparticle species, deposition methods, and patterning methods, including roll-to-roll processing paradigms.
Defects in Low-k Insulators (κ=2.5 – 2.0): ESR Analysis and Charge Injection
Authors: Afanas’ev V. V. , Keunen K. , Nguyen A. P. D. , Jivanescu M. , Stesmans A. , Tokei Zs. , Baklanov M. R. , Beyer G. P. 
Published: September 2011

AbstractElectron spin resonance study of low-κ insulating layers reveals that from a defect perspective these materials resemble oxygen-rich silicon dioxide matrices. The films fabricated using chemical vapor deposition in combination with porogen technology also contain a considerable amount of residual carbon in the form of clusters. Furthermore, ion sputtering damage generates additional defects provisionally identified as dangling bonds in the silicon oxycarbide clusters. The density of these defects is found to increase with increasing porosity of the low-κ insulator. Nevertheless, a lower defect density may be attained if using a porogen-free self-assembly technology.
Characterization of Dye-Sensitized Solar Cell with Different Nanoparticle sizes
Authors: Htun Aung , Munukutla Lakshmi V. , Radhakrishnan Sailaja , Jen Chih Y. , Kannan Arunachalanadar M. , Kinhal Karthik 
Published: September 2011

ABSTRACTThe Dye-sensitized Solar Cell (DSSC) has been regarded as the next-generation solar cell because of its simple and low cost fabrication process. The experiments for optimizing the cell efficiency were carried out in this work include varying the TiO2 layer thickness on the working electrode and determining the most favorable nanoparticle size in the TiO2 paste. The TiO2 electrode or working electrode was fabricated using screen printing technique with the Coatema tool with thicknesses ranging from ~20 to 66 μm. It was observed that both open circuit voltage and short circuit current were found to have measurable dependence on the TiO2 layer thickness. The open circuit voltage changed from 0.77 to 0.82 V and correspondingly the short circuit current also varied from ~19 to 23 mA/cm2 depending on the TiO2 layer thickness. Additionally, the cell with 40 μm TiO2 thickness showed 9.06% photo conversion efficiency compared to 6.4% and 8.5% efficiency obtained for the cells with 20 μm and 66 μm TiO2 thicknesses respectively. The second part of the experiment was conducted using three different nanoparticle sizes of 13 nm, 20 nm and 37nm in the TiO2 layer to identify optimum nanoparticle size by maintaining the TiO2 film thickness at 40 μm. The cell with 20 nm size nanoparticle, in combination with 40 μm TiO2 thickness showed 11.2% efficiency that is in par or slightly better than the efficiency value reported for the DSSC in the literature as of now. The work described in this paper showed best possible values for the TiO2 layer thickness and nanoparticle size in the TiO2 for obtaining improved cell efficiency of 11.2%.
Gold Nanolayers Embedded in Zinc Oxide for Large Area Flexible Photovoltaics
Authors: Alford T. L. , Sivaramakrishnan K. 
Published: September 2011

ABSTRACTTransparent conducting ZnO/Au/ZnO thin film structures were grown by the magnetron sputtering technique on flexible polymer substrates. These films displayed a seven orders of magnitude drop in resistivity (200 to 5.2×10-5 Ω-cm) upon increase of the Au layer thickness from 0 nm to 12 nm. The sheet resistance also showed a substantial decrease to a value of 6.5 _/sq. These films displayed a photopically average transmittance between 75% and 85% depending upon the gold thickness, and a peak transmittance of up to 93%. The best Haacke figure of merit was 15.1×10-3 Ω−1. As the Au layer thickness was increased, the conduction changed from conduction through the substrate when the nanometal islands are small and far apart to activated tunneling between discontinuous islands, and finally to direct tunneling between larger islands and metallic conduction through a near-continuous layer. Optical transmission behavior of the films was described in terms of the Au’s absorption due to interband electronic transitions in the shorter visible wavelengths, and free carrier absorption losses at the longer red wavelengths. This was combined with the limitation of the mean free path in discontinuous films and the size-dependent dielectric constant of the Au particles that enhances absorption in the longer visible wavelengths.
Chalcogenide Glass Thin Films for Nanodipole Junctionless Photovoltaics
Authors: Junaghadwala Sakina , Georgiev Daniel G. , Karpov Victor G. , Todorov Rossen , Jiang Nanke 
Published: September 2011

ABSTRACTWe examine the potential of Bi-Ge-Se chalcogenide glass films as materials for a new type of photovoltaic devices, referred to as junctionless nanodipole PV. Glasses of a chemical composition providing a significant optical absorption were synthesized in quartz ampoules from high-purity Bi, Ge, and Se elements by a conventional melt quenching technique. This material was then used to deposit thin films with different thicknesses on various substrates by thermal evaporation under high-vacuum conditions. The original bulk glasses and the films were characterized by electron microscopy with EDS, XRD, Raman spectroscopy, differential scanning calorimetry, and spectrophotometry. Open-circuit voltage (Voc) readings under incandescent illumination were obtained from the as-deposited and annealed films. Results from this characterization work are presented and discussed. Although the efficiency of nanodipole PV material structures, based on this material remains of no practical interest, our initial results indicate a possible path for the implementation of the nanodipole PV concept.
Dependence on the parameters of the equivalent electrical circuit model with the thickness of viologen-based electrochromic mixture on glass substrate devices
Authors: Barrios David , Vergaz Ricardo , Torres Juan Carlos , Sánchez-Pena José-Manuel , Viñuales Ana , Salsamendi M. 
Published: September 2011

ABSTRACTSeveral viologen electrochromic devices with different thicknesses on glass substrates were constructed, using a mixture of 4,4’-bipyridine and 1-bromoethane. The thickness of each device was fixed using a thermoplastic spacer. The devices were electrochemically tested with optical and impedance analysis. The range of the transmittance change is highly dependent on thickness. The electrical behavior of the material and the physical and chemical characteristics are derived from the proposed electrical equivalent circuit model. A simple Randles circuit including a Warburg diffusion impedance element, a charge transfer resistance and a double layer capacitive element is proposed for the fittings process. Variations on thickness of internal layer of devices lead to use a short or an open circuit Warburg element. A threshold potential, from which the device is colored, indicates the charge diffusion effects.
Effect of Substrate Temperature on the Electrochromic Properties of Cobalt Hydroxide Thin Films Prepared by Reactive Sputtering
Authors: Lee KyoungMoo , Abe Yoshio , Kawamura Midori , Itoh Hidenobu 
Published: September 2011

ABSTRACTCobalt hydroxide thin films with a thickness of 100 nm were deposited onto glass, Si and indium tin oxide (ITO)-coated glass substrates by reactively sputtering a Co target in H2O gas. The substrate temperature was varied from -20 to +200°C. The EC performance of the films was investigated in 0.1 M KOH aqueous solution. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy of the samples indicated that Co3O4 films were formed at substrate temperatures above 100°C, and amorphous CoOOH films were deposited in the range from 10 to -20°C. A large change in transmittance of approximately 26% and high EC coloration efficiency of 47 cm2/C were obtained at a wavelength of 600 nm for the CoOOH thin film deposited at -20°C. The good EC performance of the CoOOH films is attributed to the low film density and amorphous structure.
Au-assisted Growth of Indium Antimonide Nanowires by Chemical Vapor Deposition: Temperature and Growth Duration Effects
Authors: Zhong Jiebin , Lin Jian , Penchev Miroslav , Ozkan Mihrimah , Ozkan Cengiz S. 
Published: September 2011

ABSTRACTIn this paper, we investigate the morphology variation of Au-assisted epitaxial InSb nanowires (NWs) dependence on growth temperature and growth duration by chemical vapor deposition (CVD). The NW length and tapering factor correlated to the NW morphology are determined as a function of growth temperature (300°C-480°C). Higher density and longer NWs were observed on the substrate as proportional to the growth duration. The growth direction of the NWs is <110> by Transmission Electron Microscopy (TEM) studies. The aim of this study is to gain better understanding of the III-V NWs growth mechanism and achieve control over the growth of InSb NWs.
Eosin Y-sensitized ZnO/TiO2 for efficient visible light photocatalytic hydrogen evolution
Authors: Liu Haipei , Jing Dengwei , Guo Liejin 
Published: September 2011

ABSTRACTIn this work a series of Eosin Y-ZnO(x%)/TiO2 were prepared. ZnO well dispersed on the surface of TiO2, which improves the adsorption of Eosin Y and the excited electron to transfer to the conduction band of TiO2. Therefore the visible light activity of 0.2%Pt-Eosin Y-ZnO(x%)/TiO2 is much higher than that of the 0.2%Pt-Eosin Y-TiO2 and 0.2%Pt-Eosin Y-ZnO. The 0.2%Pt-Eosin Y- ZnO(1.5%)/TiO2 has the highest visible light activity among the catalysts coupled with various ZnO amount, whose activity is increased by a factor of 3.5 compared to that of 0.2%Pt-Eosin Y-TiO2. It is proposed that, 0.2%Pt-Eosin Y-ZnO(1.5%)/TiO2 has the optimal trapping sites of carriers and thickness of the space-charge layer on the TiO2 particle surface, so these factors result a more efficient charge separation, an increased lifetime of the charge carriers, and the enhanced of hydrogen production .
Experimental Demonstration of Thermal Management of High-Power GaN Transistors with Graphene Lateral Heat Spreaders
Authors: Yan Zhong , Liu Guanxiong , Khan Javed , Yu Jie , Subrina Samia , Balandin Alexander 
Published: September 2011

ABSTRACTGraphene is a promising candidate material for thermal management of high-power electronics owing to its high intrinsic thermal conductivity. Here we report preliminary results of the proof-of-concept demonstration of graphene lateral heat spreaders. Graphene flakes were transferred on top of GaN devices through the mechanical exfoliation method. The temperature rise in the GaN device channels was monitored in-situ using micro-Raman spectroscopy. The local temperature was measured from the shift in the Raman peak positions. By comparing Raman spectra of GaN devices with and without graphene heat spreader, we demonstrated that graphene lateral heat spreaders effectively reduced the local temperature by ~ 20oC for a given dissipated power density. Numerical simulation of heat dissipation in the considered device structures gave results consistent with the experimental data.