bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non-Destructive Measurement of Deep Embedded Defects in Silicon using Photoacoustic Microscope (PAM)
Authors: Xu Lu , Lowney Donnacha , McNally Patrick J , Fernandez Eva Gomez , Stopford Jennifer 
Published: April 2011

AbstractAn automatic gas cell photoacoustic microscope has been used to characterize two laser machined air trenches in a silicon substrate from the back side. Both amplitude and phase images reveal the subsurface features. The frequency dependence of the photoacoustic signals with different laser spot sizes was compared with a 1-D model. The effect of lateral heat diffusion on subsurface defect characterization was investigated and the results can be applied to other photothermal techniques.
Benefits and Trade-offs in Multi-Level Air Gap Integration
Authors: Hoofman Romano , Daamen Roel , Nguyenhoang Viet , Michelon Julien , Gosset Laurent G. , Arnal Vincent , de Pontcharra Jean , Gaillard Frederic , Caluwaerts Rudy , Bruynseraede Christophe , Beyer Gerald 
Published: April 2011

AbstractIn this paper, two different air gap integration approaches are discussed in detail. Firstly, air gaps can be created using sacrificial materials, which are selectively removed through a capping layer either by wet- or dry-etching or by thermal decomposition. The second class benefits from the non-conformal deposition of different CVD dielectrics, which creates air gaps for narrow spaced lines. The benefit of air gaps in terms of capacitance reduction in multilevel interconnects is well known, therefore the authors will mainly concentrate on the challenges associated with the introduction of air gaps in interconnect systems. It will be shown that interconnect containing air gaps does not suffer more from reliability challenges than interconnects with porous low-k dielectrics. Therefore, air gaps can be considered as a viable option for the 32nm node and beyond.
Studies of the Coefficient of Thermal Expansion of Low-k ILD Materials by X-Ray Reflectivity
Authors: Antonelli George Andrew , Phung Tran M. , Mortensen Clay D. , Johnson David , Goodner Michael D. , Moinpour Mansour 
Published: April 2011

AbstractThe electrical and mechanical properties of low-k dielectric materials have received a great deal of attention in recent years; however, measurements of thermal properties such as the coefficient of thermal expansion remain minimal. This absence of data is due in part to the limited number of experimental techniques capable of measuring this parameter. Even when data does exist, it has generally not been collected on samples of a thickness relevant to current and future integrated processes. We present a procedure for using x-ray reflectivity to measure the coefficient of thermal expansion of sub-micron dielectric thin films. In particular, we elucidate the thin film mechanics required to extract this parameter for a supported film as opposed to a free-standing film. Results of measurements for a series of plasma-enhanced chemical vapor deposited and spin-on low-k dielectric thin films will be provided and compared.
Applications of Raman Spectroscopy in Cu CMP: In-situ Detection of Chemical Species in the Slurry
Authors: Kondoju Siddartha , Lucas Pierre , Raghavan Srini , Fischer Paul , Moinpour Mansour , Oehler Andrea 
Published: April 2011

AbstractSlurries used for copper CMP have a rich chemistry, which may change during the course of polishing due to consumption and decomposition of molecular species. Various aspects, such as small layer thickness (<50 μm), continuous flow of the slurry, and dynamics of the film removal process pose great challenge to the monitoring of slurry components between the pad and the wafer. The slurry constituents such as oxidants and corrosion inhibitors have unique signatures that can be detected using spectroscopic techniques. In this paper, work carried out to explore the use of Raman spectroscopy to detect and quantitate chemical species such as hydroxylamine, benzotriazole and hydrogen peroxide in-situ will be presented. More detailed study pertaining to the protonation of hydroxylamine with respect to the pH will also be presented. An abrasion cell integrated with a Raman spectrometer was used to make the measurements.
AFM Measurements of Adhesion between CMP Slurry Particles and Copper
Authors: Burtovyy Ruslan , Liu Yong , Zdyrko Bogdan , Tregub Alex , Moinpour Mansour , Buehler Mark , Luzinov Igor 
Published: April 2011

AbstractAdhesion between abrasive particles and surfaces being polished plays an important role in chemical mechanical planarization (CMP) processes. The changes in particle - surface and particle – particle interactions can significantly influence the effectiveness of material removal and cleaning methods. To determine the adhesion between actual abrasive particles and different surfaces treated by the CMP process a method employing atomic force microscopy (AFM) technique is being developed.The monolayer of silica abrasive nanoparticles was deposited on silicon wafer covered with polymer anchoring layer. High affinity of the thin polymer film to the particles and wafer ensures the stability of particles monolayer on the surface during measurements. AFM cantilever was modified with attachment of 20-40 microns hollow glass bead (representing a flat surface), which then was covered with copper using physical vapor deposition technique. Force-distance curves were collected employing AFM force volume mode and used to calculate the adhesion value. The effect of different factors (such as pH, presence of surfactants) on adhesion between copper surface and silica slurry has been studied.
Anomalous pH Actuation of a Chitosan/SWNT Microfiber Hydrogel with Improved Mechanical Property
Authors: Shin Su Ryon , Park Sang Jun , Yoon Seong Gil , Lee Chang Kee , Shin Kwang Min , Gu Bon Kang , Shin Min Kyoon , Kim Min Sup , Kim Yu Jin , Kim Seon Jeong 
Published: April 2011

AbstractComposite fibers composed of chitosan and single-wall carbon nanotubes (CNTs) have been fabricated using a wet spinning method. The dispersion was improved by the sonic agitation of the CNTs in a chitosan solution followed by centrifugation to remove tube aggregates and any residual catalyst. The mechanical behavior was investigated using a dynamic mechanical analyzer (DMA). The mechanical tests showed a dramatic increase in Young's modulus for the chitosan/CNT composite fibers fabricated using the improved dispersion method. The strain on the microfibers was determined from tensile load measurements during pH switching in acidic or basic electrolyte solutions. The microfibers showed a general actuation behavior of expanding at pH = 2 and contracting at pH = 7 under low tensile loads. However, a reverse of this actuation behavior was exhibited under high tensile loads. This anomalous pH actuation is both new and surprising. It was explained from an analysis of the differences in sample stiffness and Poisson’s ratio under tensile load in electrolyte solutions with different pH values.
Pore Size Dependence of Proteinase K Diffusion Through Sol-Gel Derived Silica
Authors: Dong Winny , Lin Weijen , Contreras Nicole , Elmatari Doja , Lin YiHsuan , Torres Maria 
Published: April 2011

AbstractSol-gel derived silica particles are candidates for vehicles for injectable controlled drug-delivery. In this study, Proteinase K was the model biomolecule encapsulated in the silica xerogel, ambigel, and aerogel particles. The surface area and average pore diameter of these particles are reported. Both the amount of Proteinase K released from the particles and the activity of the released Proteinase K were measured as a function of time. The primary finding of this study is the effect of pore diameter on the specific activity of Proteinase K released from these particles.
Embedded Piezoresistive Microcantilever Sensors: Materials for Sensing Hydrogen Cyanide Gas
Authors: Porter Timothy , Vail Tim , Eastman Michael , Stewart Ray , Reed Jim , Delinger William 
Published: April 2011

AbstractWe have used embedded piezoresistive microcantilever (EPM) sensors in the detection of hydrogen cyanide gas. EPM sensors are small, MEMS-based devices consisting of a tiny piezoresistive microcantilever partially embedded into a “sensing material” designed to respond volumetrically when exposed to the desired analyte. These EPM sensors may be very small, operate on simple and inexpensive support electronics, are highly resistant to movement or shock, may be operated by hardwire connection or wirelessly in large numbers, and are capable of detecting many different analytes. In this study, we have used EPM sensors to detect hydrogen cyanide gas. Preliminary results indicate that the EPM sensors provide a fast response (less than 5 seconds) to levels of HCN that may be lethal to humans.
Aromatic Hydrocarbon Detection Using Self-Assembled Monolayer Coated Cantilevers
Authors: Riley Andrew E , Schilowitz Alan M , Yablon Dalia G , Disko Mark M 
Published: April 2011

AbstractThe presence of toluene and xylene is sensed via surface stress induced deflection of microcantilevers functionalized with self-assembled monolayers (SAMs). Monolayers are formed on gold coated cantilevers using alkanethiols, mercaptanols, and aromatic thiols. These coatings create a variety of chemical functionalities at the cantilever surface, which impact the interactions between target molecules and the cantilever. The differential responses of the cantilevers are investigated as a means to selectively detect aromatic vapors at parts per thousands (ppth) levels.
Tin Dioxide Nanodimensional Film Based H2 sensor
Authors: Dmitriev Serghei 
Published: April 2011

AbstractPaper presents results of investigation aimed at the development of tin dioxide nanodimensional film gas sensors (NDFGS) with high sensitivity to hydrogen. Specifics of the performed research consist in the approach based on the combination of utilization nanodimensional metal oxide film, as gas sensitive element of device, and group electron technology methods that allows to arranging from small to large scale manufacturing of given NDFGS.Gas sensitive nanodimensional film (NDF) had been formatted by means of chemical spray pyrolysis method on the both ceramic substrate for study and optimization of electrophysical and gas sensitive characteristics and “chip” of gas sensor (GS) preliminarily produced through group electron technology. Films were deposited at the temperatures in interval 400-500°C from water solutions of SnCl4.5H2O precursor. The thickness of SnO2 films was varied in the range 40-80 nm.Study of electrophysical characteristics of obtained layers has shown that the last one possess resistance on the level 105-106 Ohm/ at the working temperatures of GS. Gas sensitivity was determined as ratio of SnO2 film resistance in the pure air and in the presence of gas impurity in atmosphere (S=Rgas/Rair). Values of R were determined through Van-der-Pauw method.X-ray and SEM investigation has allowed establishing the interconnection between technologic parameters, nanostructure and gas sensitive characteristics of obtained films.Gas sensitivity S of the deposited undoped films has amounted 9-10 relative units to the 100 ppm of hydrogen in air. Modification of gas sensitive properties of tin dioxide NDF through bulk and surface doping with Pd has allowed to increasing hydrogen sensitivity up to almost 104 rel. units, providing the detection of hydrogen at the concentration on the level 1 ppm and shift of the sensitivity maximum from 350°C (in the case of undoped films) to 150°C (Pd doped NDF).Performed sensor chip thermal regimes modeling has allowed developing of the NDFGS topology with reduced power consumption (< 30 mW).
Inverse Opal Nanoassemblies: Novel Architectures for Gas Sensors The SnO2:Zn Case
Authors: Sutti Alessandra , Calestani Gianluca , Dionigi Chiara , Baratto Camilla , Ferroni Matteo , Faglia Guido , Sberveglieri Giorgio 
Published: April 2011

AbstractA novel technique is here presented, based on inverse opal metal oxide structures for the production of high quality macro and meso-porous structures for gas sensing. Taking advantage of a sol-gel templated approach, different mixed semiconducting oxides with high surface area, commonly used in chemical sensing application, were synthesized. In this work we report the comparison between SnO2 and SnO2:Zn. As witnessed by Scanning and Transmission Electron Microscopy (SEM and TEM) analyses and by Powder x-ray Diffraction (PXRD), highly ordered meso-porous structures were formed with oxide crystalline size never exceeding 20 nm. The filled templates, in form of thick films, were bound to allumina substrate with Pt interdigitated contacts and Pt heater, through in situ calcination,in order to perform standard electrical characterization. Pollutant gases like CO and NO2 and methanol, as interfering gas, were used for the targeted electrical gas tests. All samples showed low detection limits towards both reducing and oxidizing species in low temperature measurements. Moreover, the addiction of high molar percentages of Zn(II) affected the behaviour of electrical response improving the selectivity of the proposed system.
Chain Morphologies in Blue-Emitting Polyfluorenes: Impact on Light-Emitting Diodes
Authors: Guha Suchi , Arif M. , Volz C. 
Published: April 2011

AbstractDioctyl-substituted polyfluorene (PF) is especially well known for the presence of an unusual spectral feature identified as the beta phase, known to originate in regions of enhanced chain planarity. Although this phase appears as a minority constituent it dominates the emission, resulting in a red shift of the luminescence. We present Raman scattering studies of poly[9,9'-(di n, octyl) fluorene] as a function of thermal cycling that establish a connection between the conformational isomers and chain morphology. Density-functional theory calculations of the vibrational spectra of single chain oligomers in conjunction with our experimental results demonstrate the incompatibility of the beta phase with the overall alpha crystalline phase. Further, electroluminescence and photoluminescence measurements from PF-based light-emitting diodes are presented and discussed in terms of the crystalline phases and chain morphologies in the PFs.
Pb2+ and Ce3+ Doped SrZnO2: New Blue Luminescent Phosphors
Authors: Manavbasi Alp , LaCombe Jeffrey C 
Published: April 2011

AbstractTwo new blue emitting phosphors, SrZnO2:Pb2+ and Ce3+ were synthesized by adipic acid and sucrose templated sol-gel routes, respectively. The resulting phosphor particles were fine, nanocrystalline and pure. The optimum activator concentrations were found to be 1 mol% Pb2+ and 12 mol% Ce3+. Two excitation bands centered at 283 and 317 nm, plus a weak shoulder at 275 nm were observed for Pb2+ doped samples, however only one broad excitation band with a maximum at 294 nm was observed for Ce3+ doped samples fired at 1000 °C for 2h. The emission spectra of SrZnO2:Pb2+ showed a very broad band extending from 374 to 615 nm with a maximum at ~455 nm which was ascribed to the 3P1 ¡æ 1S0 transition on the Pb2+ ions allowed by the strong spin-orbit (SO) coupling. Similarly, SrZnO2:Ce3+ showed a broad emission band extending from 374 to 609 nm and centered at 467 nm. This broad emission was attributed to the 5d1 ¡æ 4f1 transition of Ce3+ ions. The lower level 2F5/2 of the 4f1 is populated but the level 2F7/2 is almost empty at room temperature where all measurements were taken. The luminescence properties of Ce3+, K+ co-doped SrZnO2 revealed that the characteristic band locations remained the same and the ratio of emission to excitation intensities were constant. X-ray diffraction patterns showed that the SrZnO2 phase started to form at 900 °C (after 2 hrs), and the single-phase SrZnO2 obtained at 1000 °C. SEM micrographs of both phosphors have a rounded and filled morphology for individual particles with an approximate diameter of 50-250 nm. Dynamic light scattering studies revealed that average particle size is around 1 ¥ìm for both phosphors.
UV and VUV Spectroscopy of ns2-type Ions Co-doped YBO3:Eu3+ Red Phosphor
Authors: Wang L.L. , Wang Y.H. , Hua W.X. 
Published: April 2011

AbstractYBO3:5% Eu3+ co-doped with some ns2-type ions were synthesized by solid-state reaction and their luminescence properties under ultraviolet (UV) and vacuum ultraviolet (VUV) region were investigated. The results indicated that in the excitation spectrum of YBO3:5%Eu3+, the strong charge transfer (CT) band of Eu3+ was located in the UV region and the absorption band of the host lattice lay in the VUV region. When the ns2-type ions, such as Sn2+ and Sb3+(n=5), Tl+, Pb2+ and Bi3+(n=6) were co-doped into the host lattice of YBO3:5%Eu3+, the CTS band of Eu3+ was shifted. The intensity of the host lattice absorption band was improved with the incorporation of Tl+, Pb2+ or Bi3+, while decreased with Sn2+ or Sb3+. These luminescent phenomena were analyzed in detail and possible reasons were given.
Optical Properties of Alkali Doped Group IV Nano Materials
Authors: Gokturk Hal 
Published: April 2011

AbstractOptical properties of sodium and other alkali metals (lithium & potassium) incorporated into nano hosts of group 4 elements (carbon, silicon & germanium) were investigated as candidates for solid state light emitting materials. First, optical properties were calculated by quantum mechanical simulations using TDDFT method. Results of the simulations indicate that alkali doped group 4 nano hosts exhibit optical transitions in and around the visible range whereas, undoped nano hosts do not have any at similar wavelengths. Some combinations of alkali dopant and nano host give rise to multiple transitions in the visible. One of the simulated combinations, Li dopant and carbon nano host was chosen to be synthesized for experimental verification. Optical absorption and emission characteristics of the synthesized material were measured and compared with those obtained from quantum mechanical calculations. Both the wavelength and the relative intensity of the measured optical transitions were found to be in good agreement with the results of the calculations. Alkali metals which have good light emission characteristics can be combined with group 4 indirect semiconductors to obtain new nano materials which have interesting optical properties in the visible.
Improvement of Organic Light-emitting Devices by Controlling Deposition Temperature and Inclusion of Carbon Nanotubes
Authors: Wang Guangfeng , Tao XiaoMing , Chen Wei 
Published: April 2011

AbstractResearch was conducted to improve performance of organic light-emitting devices (OLEDs) on flexible polyethylene terephthalate (PET) substrates based on tris-(8-hydroxyquinoline)¨Caluminum (Alq3). Based on double layer structure, indium tin oxide(ITO)/N,N’Diphenyl-N-N’-di(m-tdyl) benzidine (TPD)/Alq3/Al, flexible OLEDs on polyethylene terephthalate (PET) substrates were fabricated by physical vapor deposition (PVD) method, with the Alq3 layer deposited at 90°C , 120°C and 150°C, respectively. It was found that the temperature had great effect on the surface morphology of Alq3 and the devices fabricated at high temperature (150°C) showed a higher external efficiency than those fabricated at low temperature (90°C , 120°C).Multi wall carbon nanotubes (MWCNTs) doping poly(3,4-ethylene dioxythiophene) (PEDOT) : poly(styrene sulfonate) (PSS) was used as hole injection layer to improve performance of OLEDs based on Alq3. PEDOT:PSS, which was doped by 0.2 wt.%, 0.4 wt.%, 0.6 wt.%, 0.8 wt.% and 1 wt.% MWCNTs, was coated on clean PET substrate with ITO by spin- coating method. The light-emitting layer (Alq3) and cathode layer (Al) were deposited by PVD method. It was found that the electroluminescence (EL) intensity of the OLEDs were highly improved by adopting MWCNTs doping PEDOT:PSS as hole injection layer. The luminous intensity obtained from the device with a concentration of 0.4 wt.% MWCNTs in the PEDOT:PSS layer was three folds as those adopted from device without MWCNTS doping in the PEDOT:PSS layer.
Effect of HVPE GaN Substrate Condition on the Characteristics and Performance of 405 nm LEDs
Authors: Grandusky James R , Jamil Muhammad , Jindal Vibhu , Shahedipour-Sandvik Fatemeh , Lu Hai , Cao Xian-An , Kaminsky Edmund B 
Published: April 2011

AbstractThis article reports on the effects of HVPE GaN substrate condition on the performance of 405 nm LEDs grown by MOCVD. Three 1 cm2 HVPE GaN substrates were received from a commercially available source and characterized for the substrate condition. AFM and optical microscope were used to characterize the surface morphology and this was found to vary from a “moonscaped” morphology to a smooth surface. The presence of nanoscale pits and substrate bowing were also found. XRD measurements showed a variation in crystalline quality of the substrates with the FWHM of the (0002) rocking curve varying from 87 arcsec to 192 arcsec with some substrates showing multiple peaks in the rocking curve. Photoluminescence was used to measure the optical quality of the substrates and both band edge luminescence and yellow luminescence were found to vary greatly within one substrate as well as from substrate to substrate. After characterization of each individual substrate a 405 nm LED structure was grown using identical growth conditions on each substrate, in separate growth runs. A GaN template was included in each growth for consistency. The surface morphology and crystalline quality of the device structures were then measured. Following this devices were fabricated and tested for electroluminescence optical output power and current-voltage characteristics. The device characteristics and performance as related to starting substrate quality will be presented with respect to substrate surface morphology and crystalline structure.
The Development of Zero-temperature-gradient Zero-bias Thermally Stimulated Current (ZTGZBTSC) Spectroscopy Technique for the Detection of Defect States in Ultra-thin High-k Dielectric Films
Authors: Lau Wai Shing , Wong Kum Fai , Han Taejoon , Sandler N. P. 
Published: April 2011

AbstractPreviously, we have reported our application of the zero-bias thermally stimulated current (ZBTSC) spectroscopy technique to study defect states in high-dielectric constant insulator films like tantalum oxide (Ta2O5) with much less parasitic current which can be a serious limitation for the conventional thermally stimulated current (TSC) method. However, a parasitic current can still be observed for ZBTSC because of a small parasitic temperature gradient across the sample. The thermal design of the ZBTSC system can be improved, resulting in zero-temperature-gradient ZBTSC (ZTGZBTSC) which can be used to detect deeper traps than ZBTSC.
Interfacial layer bonding and Dielectric properties of Hf-O-N gate dielectric thin films
Authors: Ramani Karthik , Essary Chad Robert , Craciun Valentin , Singh Rajiv K 
Published: April 2011

AbstractThe electrical response and interfacial layer characterization of nitrogen doped HfO2 gate dielectric thin films are reported. The films were processed at relatively low temperature (~ 400 0C) by pulsed laser deposition and ultra-violet radiation assisted oxidation technique. Nitrogen incorporation in the hafnia films led to O-N and Hf-Si-O-N bonding in the bulk and at hafnia-Si interface respectively. The nitrogen doped hafnia films exhibited a leakage current density lower than 10E-5 A/sq cm at -1 V and a simulated equivalent oxide thickness of 9.4 Å.