bluuebunny/crossref_metadata_2025_split huggingface dataset:
EBL/NIL fabrication and characterization of interdigitated electrodes for potential application in combinatorial studies.
Authors: Skjolding Lars Henrik Dæhli , Spégel Christer , Emnéus Jenny , Montelius Lars 
Published: April 2011

AbstractElectrochemical transducers are frequently used to electrochemically deposit, synthesize and/or sense chemical compounds in material science, chemistry and biology. Traditionally this is done in fairly large volumes; generally several milliliters to even full production scale tanks, however, for high throughput measurements and combinatorial experiments smaller volumes are generally preferred. To probe small volumes small electrodes with preferable high density are needed. Presented in this paper is how to fabricate interdigitated electrodes by electron beam lithography (EBL) and also how to make large quantities by nanoimprint lithography (NIL) to enable combinatorial studies of cells or materials in microsystems (Lab-on-a-Chip Systems).Interdigitated electrodes are shown to have additional advantages compared to simple disk or rod electrodes, such as being able to perform redox cycling experiments. The collection efficiency for the electrodes with pitch of 400 nm and width of 200 nm fabricated by EBL has been found to be round 87% when characterized electrochemically using ferro-/ferricyanide. The shape of the cyclic voltammograms for the electrodes are also in good agreement with the theoretical expectations for ultramicroelectrodes. Hence, these electrodes should be ideal candidates for combinatorial and high-throughput studies based on electrochemical methods.Furthermore, a fabrication process based on nanoimprint lithography (NIL) is demonstrated, this could potentially ease fabrication and reduce cost of devices. The NIL process is based on thermal imprinting in PMMA 950k and LOR 0.7A.
ITO-Nanocomposite Thin Film Strain Gages with Low TCR
Authors: Chen Ximing , Chen Ximing 
Published: April 2011

AbstractDynamic strain gages based on alloys of indium tin oxide (ITO) have been developed to monitor the structural integrity of gas turbine engine components operating at temperatures in excess of 1200 °C. Static strain measurements in these harsh environments have been hampered by apparent strain effects that can be mitigated by employing sensors with a low temperature coefficient of resistance (TCR). Since refractory metals typically exhibit a positive TCR and semiconductors such as ITO exhibit a negative TCR, an optimal combination of materials could produce a sensor with little or no apparent strain. These materials were combined in a single strain gage element, in which phase separation occurred at very small length scales. Specifically, nanocomposite strain elements comprised of ITO/(Pt, Pd, W, NiCoCrAlY, Ni and Ir) combinatorial libraries were prepared by co-sputtering from ITO and refractory metal targets onto alumina constant strain beams. TCR was measured from room temperature to 1100 °C and the piezoresistive response of the more promising combinations was measured at strain levels approaching 1000 μm/m and the chemical composition of the most promising combinatorial libraries was analyzed by SEM/EDS. Preliminary results indicated that a strain gage based on an ITO/platinum (12% ITO: 88% Pt) nanocomposite was fabricated with a near zero TCR over the temperature range 500-1100 °C. The gage factor of this nanocomposite remained unchanged (∼-26.0) compared to that of ITO and thus, it appears that a simple additive mixture rule does not apply here and that other physics are controlling the piezoresistive response in these materials.
Estimation of Magnetic Energy Distribution in Co84Cr16Ta4 Magnetic Thin Films from EFTEM
Authors: Al-Sharab Jafar F. , Wittig James E , Bentley James , Evans Neal , Bertero Gerardo , Yamashita Tom 
Published: April 2011

AbstractMagnetic thin films of Co80Cr16Ta4 were sputtered onto identical CrMo seed-layers at −200 V bias and 3 different substrate temperatures (150, 200, and 250°C). Energy-filtered transmission electron microscopy (EFTEM) was performed to analyze Cr levels at the grain boundaries as well as inside the grains. These quantitative Cr measurements were used to estimate the local values of magnetocrystalline anisotropy (Ku) and, together with grain size distributions, calculate the product of Ku and the grain volume (KuV), a quantity which is a measure of thermal stability. The results show that the coercivity as well as the percentage of stable grains increased with increasing substrate temperature. The increase in the number of stable grains is produced by the enhancement in the Ku value from Cr depletion of the grain interiors and the magnetic decoupling between the grains from Cr grain boundary segregation.
Si Ultra Shallow Junctions Dopant Profiling with ADF-STEM
Authors: Parisini Andrea , Giubertoni D. , Bersani M. , Morandi V. , Merli P. G. , van den Berg J. A. 
Published: April 2011

AbstractIn this work, we show how the Z-contrast annular dark field scanning transmission electron microscopy technique can provide reliable dopant profiles in ultra shallow junctions in Si. Dopant profiles obtained with this technique are compared with those obtained by spectroscopic techniques like secondary ion mass spectroscopy and medium energy ion scattering.
Lattice-Fringe Fingerprinting: Structural identification of nanocrystals by HRTEM
Authors: Peter Moeck , Bjorge Ruben 
Published: April 2011

AbstractA novel method for the structurally identification of a nanocrystal from a single high resolution (HR) transmission electron microscopy (TEM) micrograph is described. Components of this method are demonstrated on both experimental and simulated HRTEM images. On the experimental side, the structural information that can be extracted from a HRTEM image is the projected reciprocal lattice geometry, the plane symmetry group, a few structure factor amplitudes and phases, and an outline of the projected atomic structure to the limited resolution of the HRTEM (via a Fourier synthesis of the structure factors). Searching for this information in a comprehensive database and matching it with high figures of merit to that of candidate structures should allow for highly discriminatory identifications of nanocrystals, even without additional chemical information as obtainable in analytical TEMs.
Strain measurements in s-Si/SiGe nanostructures by quantitative high-resolution electron microscopy
Authors: Hüe Florian , Hÿtch Martin , Bender Hugo , Hartmann Jean-Michel , Claverie Alain 
Published: April 2011

AbstractWe have studied strained Si layers grown on Si1-xGex virtual substrate (VS) by high-resolution transmission electron microscopy (HRTEM). Aberration-corrected HRTEM coupled with geometric phase analysis (GPA) provides precise measurements of strain. Different parameters are investigated: the VS composition (x=20, 30, 40 and 50%) and the s-Si layer thickness. Finite element method simulations confirm our measurements. Measurements and simulations lead to the conclusion that the strain state of the deposited layer is independent of the layer thickness. We apply the technique to measuring strains in the channel region of a p-MOSFET and show that the technique is a promising metrological tool for nanoelectronic devices.
Effect of Hydroxyl Group on the Characteristics of Solution Processed n- and p-type OFETs using Poly(p-silsesquioxane) Derivatives as a Gate Insulator
Authors: Ohmori Yutaka , Kajii Hirotake , Fukuda Shohei , Ogata Toshiyuki , Takahashi Motoki 
Published: April 2011

AbstractOrganic field effect transistors (OFETs) fabricated on the polymer substrate including conductive organic materials and polymeric gate insulator is one of promising devices for the flexible electronic devices. For OFETs with a conductive organic layer formed on the gate insulating materials, the performance of devices strongly depends on the molecular structure of the gate insulators. In this study, we investigated the effect of hydroxyl group of gate insulating materials on the characteristics of n- and p-type OFETs utilizing [6,6]-phenyl C61-butyric acid methyl ester (PCBM), α, ω-dihexylsexithiophene (DH6T) and pentacene OFETs as a conducting layer, respectively. Poly(p-silsesquioxane) (PSQ) derivatives are used as a polymeric gate insulator, which containes various ratios of phenol-group with a hydroxyl group bonded to a phenyl ring in the side chain of their molecular structures.
Surface Plasmon-mediated Luminescence in Organic Field-effect Transistors
Authors: Watanabe Akira , Tada Hirokazu 
Published: April 2011

AbstractConsiderable attention has recently been paid to light-emitting organic filed-effect transistors (LEOFETs) because of their potential applications to novel opto-electronic devices. In most LEOFETs, light emission occurs through the recombination of carriers injected from electrodes. Various efforts have been, thus, made to improve injection and transport properties of minority carriers in organic materials. On the other hand, light emission was frequently observed when we applied reverse bias voltages, that is, positive bias voltages, to the drain electrode for p-type FETs with grounded source and negatively biased gate electrodes. In this circuit, minority carriers were not injected into organic semiconductors. Nevertheless, the luminous intensity increased with drain voltage.In the present work, we have prepared such novel type LEOFETs with various device structures. We have inserted thin metal wires between the source and drain electrodes in the channel region of pentacene FETs. It was found that the light emission was observed around the metal wires inserted and the luminous efficiency was improved with the number of wires. The luminescence spectrum was identical to that of pentacene films. The light emission was thought to be generated by via energy transfer to the pentacene films from plasmon excited on metal surfaces by current injection.
High-Performance Scan-Type Stage for Large Substrates
Authors: Takashi Ohno , Azuma K. , Mizutani T. , Kobayashi H. 
Published: April 2011

AbstractDue to the steady increase in substrate sizes for low-temperature poly-Si devices and LSIs, there are strong demands for larger substrate handling, more accurate positioning and shorter tact time for many processes such as laser crystallization scan exposure, [3], and dopant activation [4] and so on. In order to satisfy such demands, we have developed a high-performance scan-type stage for large substrates. In this paper, we describe the outline of the mechanical structure and also the performance of this stage.The XY moving stage was installed on an air slider of planarized granite. Stroke sizes of the stage were more than 920 mm and 730 mm for scan and step directions, respectively; the stage size was matched to the large glass substrates (4th generation). The stroke in the vertical direction was more than 32 mm, and the stage could rotate for more than ±0.3 degree for alignment.The stage is driven by a newly introduced shaft-type linear motor, which consists of a fixed stainless-steel pipe shaft and a moving cylindrical coil rounded around the shaft. There are thin annular permanent magnets stacked inside the shaft. Since this coaxially aligned structure of permanent magnets and the coil is a nearly ideal configuration for efficient magnetic coupling, this motor could generate a stronger driving force; this enabled rapid acceleration and deceleration of the stage. Since stacked magnets generate parallel and uniform magnetic field along the shaft surface but slight field for transverse direction, electromagnetic force slightly fluctuated along the shaft, independent of the pitch of the magnet plate. This introduced another important advantage of the shaft-type linear motor that cogging, which has a serious impact on processing, was almost eliminated. This fluctuation was further reduced by introducing a real-time feedback system. The shaft-type motor, however, had been said to have the serious difficulty of elongation since its own weight bends the shaft. This problem was solved by using new magnetic materials and an optimized design of physical dimensions of the motor.Experiments have been conducted under stabilized temperature conditions. The maximum scan speed of the stage was more than 500 mm/s with a speed stability of 0.03%, about one order of magnitude better than the reported value of about 0.5%. Acceleration and deceleration times from the halt condition to the constant velocity condition and vise versa were 1.0 s; the scan time was as short as 1.8 s for a 920 mm stroke. The “straight extent” was always better than ±0.5 mm Projection optics is commercially available for shaping a 30-mm-long excimer laser light beam on a sample surface. If we combine this stage and such optics, the whole area of a 4th-generation substrate surface can be scanned within a little more than 1 minute; that is, extremely high throughput can be expected. For example, to grow arrays of large Si grains, two-dimensional position control is the most important subject.
Mechanical Limitations of Materials for Steel Foil Based Flexible Electronics
Authors: Kuo Po-Chin , Chouvardas Vasilios G. , Spirko Jeff A. , Hatalis Konstantinos M. , Hatalis Miltiadis K. 
Published: April 2011

AbstractThin steel foils have been successfully demonstrated as outstanding substrate materials for flexible electronics because of their high mechanical strength, flexibility, light weight and thermal stability. This work investigates mechanical limitations of thin film materials on steel foil substrates. We characterize a three layer structure consisting of 100μgm thick stainless steel foil as the substrate, followed by 1μgm thick spin-on-glass passivation layer and 0.3μgm thick patterned aluminum interconnect layer on top with varying widths between 10- 35μgm by means of a bending experiment. A collapsing radius test method was adopted for the bending experiment and an elliptical curve fit was used to facilitate the strain measurement. The failure strain of aluminum interconnect layer was detected by monitoring the continuity of the test circuit during the experiment. The corresponding results reveal that the passivation layer cracked at a tensile strain of 0.46% and delaminated at a compressive strain of 0.68%. The metal interconnect layer ruptured at a tension strain of 1.26% and delaminated from substrate at a compressive strain of 1.22% due to the delamination of the passivation layer underneath. We determined that the failure of the aluminum interconnect under tension was due to localized elongation caused by cracking of the passivation layer underneath and concluded that a wider interconnect could withstand a larger strain. The stainless steel foil plastically deformed at a relatively small strain of 0.13%; thus, the use of stainless steel with reversible bending capability for flexible electronics is mostly limited by the minimum elastic bending radius of the steel substrate. The flexibility of steel foil based devices can be effectively improved by decreasing the substrate thickness.
Flipchip Bonding of Si Chip on Flexible PEN Foil using Novel Electronic 100 μm Pitch Fan-out Circuitry
Authors: Brand Jeroen van den , Veninga Erik , Kusters Roel , Podprocky Tomas , Dietzel Andreas 
Published: April 2011

AbstractA novel, cost effective technology to manufacture high density embedded electronic circuitry is demonstrated. The process consists of laser photoablation of the circuitry into a substrate through a mask and subsequent filling using a polymer thick film paste. Because the volume of the substrate is used it is possible to make thick and thereby highly conductive lines using low cost materials and processes. The process is demonstrated for a fan out circuitry in 100 µm thick polyethylene naphthalate (PEN). The fan out circuitry has linewidths of 50 µm and line spacings of 100 µm. The usability of the circuitry is demonstrated by the successful flipchip bonding of a thinned Si daisy chain dummy chip with 176 IO's.
Principal Pilot Line Manufacturing Challenges and Solutions in Direct Fabrication of a-Si:H TFT Arrays on Flexible Substrates
Authors: O¡¯Rourke Shawn M. , Loy Douglas E. , Moyer Curt , Ageno Scott K. , O'Brien Barry P. , Bawolek Edward J. , Bottesch Dirk , Marrs Michael , Dailey Jeff , Cordova Rita , Trujillo Jovan , Kaminski Jann , Allee David R. , Venugopal Sameer , Raupp Gregory B. 
Published: April 2011

AbstractPrincipal challenges to direct fabrication of high performance a-Si:H transistor arrays on flexible substrates include automated handling through bonding-debonding processes, substrate-compatible low temperature fabrication processes, management of dimensional instability of plastic substrates, and planarization and management of CTE mismatch for stainless steel foils. In collaboration with our industrial and academic partners, we have developed viable solutions to address these challenges, as described in this paper.
TiO2 Surface State Control for Dye Sensitized Solar Cells with High Efficiency and the Solidification -Fabrication of Charge Carrier Path
Authors: Inakazu Fumi , Ogomi Yuhei , Noma Yusuke , Fujita Yoshihisa , Kono Mitsuru , Yamaguchi Yoshihiro , Kashiwa Yohie , Kogo Takeshi , Hayase Shuzi 
Published: April 2011

AbstractImprovement of photovoltaic performance for dye sensitized solar cells (DSC) is discussed in terms of electron-path and ion-path. In order to make electron path, we focused on passivation of TiO2 surface states which are observed by thermally stimulated current (TSC). The TiO2 surface was well-passivated with dye molecules under pressurized CO2 atmosphere. It was found that DSC cells prepared by a CO2 process (Cell-CO2) had higher efficiency than those prepared by a conventional dipping process (Cell-DIP) and the higher efficiency was associated with low TiO2-surface state, high electron diffusion coefficient and long electron life time in TiO2 for the Cell-CO2. In addition, dye-staining under pressurized CO2 atmosphere had advantages over a conventional dipping process on rapid dye-uptake and less dye aggregation. In order to fabricate ion-path in solidified electrolyte, we focused on surface modification of nano-materials. Surface of nano-materials such as TiO2-nanoparticles and porous alumina films were modified with imidazolium iodide moieties consisting of long alkyl chains which render surface-molecules self-organized. Redox-species are concentrated on the self-organized molecules and make ion-path. We propose quasi-solid electrolyte system consisting of two layers having different charge carrier concentration to keep high photoconversion efficiencies even after solidification.
Synthetic approaches to study aggregation of tripodal linkers on semiconductor surfaces
Authors: Taratula Olena , Thyagarajan Sujatha , Galoppini Elena 
Published: April 2011

AbstractTwo tripod-shaped adamantane derivatives carrying a pyrene chromophore and three carboxylic acid binding groups, and varying in footprint size (∼ 0.7 and 2.7 nm2), were synthesized as models to study how the footprint size can influence the aggregation of organic dyes bound to ZrO2 thin films. Synthetic approaches and binding properties of large footprint tripodal linkers are discussed.
Polaron Pair Dissociation and Polaron Recombination in Polymer: Fullerene Solar Cells
Authors: Deibel Carsten , Baumann Andreas , Lorrmann Jens , Dyakonov Vladimir 
Published: April 2011

AbstractIn polymer:fullerene solar cells, the field-dependent photocurrent is due to a combination of polaron pair dissociation, competing with monomolecular recombination, and bimolecular recombination. We compare of the experimental photocurrent of P3HT:PCBM bulk heterojunction solar cells to Monte Carlo simulations of bilayer and bulk heterojunction devices. The shape of the photocurrent can be reproduced, the high quantum yield, however, cannot be explained with help of the simulations. In order to analyse the dominant experimental recombination mechanism, we apply the photo-CELIV technique. Our data can be fitted with bimolecular recombination, but only if a reduced Langevin recombination factor is assumed. Thermalisation is accounted for by measuring the time-dependent charge carrier mobility.
Analysis of Strain Compensation in Quantum Dot Embedded GaAs Solar Cells
Authors: Bailey Christopher , Cress Cory , Raffaelle Ryne , Hubbard Seth , Maurer William , Wilt David , Bailey Sheila 
Published: April 2011

AbstractThe effects of strain within stacked layers of InAs quantum dots (QDs) were investigated. InAs QD test structures with and without strain compensation (SC) were analyzed using atomic force microscopy, transmission electron microscopy, and X-ray diffraction. The affects of strain compensation on test structure morphology and on GaAs-based QD solar cell performance was studied as a function of the thickness of the SC layer. X-ray diffraction analysis of the QD embedded test structures reveals a relationship between the SC thickness and the observed crystalline quality. Air mass zero illuminated current vs. voltage data and spectral responsivity measurements were used for the solar cell comparison. When SC is employed, QD insertion shows a lower open circuit voltage, in reference to a baseline device without QDs, but leads to an enhancement in the short circuit current of the device.
Copper Phthalocyanine Nanowire Based Solar Cells
Authors: Singh Vijay , Rajaputra Suresh , Phok Sovannary , Chintakula Goutham , Sagi Gayatri 
Published: April 2011

AbstractPhotovoltaic devices based on organic semiconductors are of interest because of their potential as flexible, lightweight and inexpensive devices. One of the promising devices, involves the heterojunction between copper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic bis-benz-imidazole (PTCBI). Earlier, we reported, the highest Voc (1.125V) in a single organic heterojunction solar cell in an ITO/PEDOT:PSS/CuPc/PTCBI/Al structure. Results were interpreted in terms of a modified CuPc-Al Schottky diode for this thin PTCBI layer case and a CuPc-PTCBI heterojunction for the thick PTCBI case. We also reported the device characteristics of Copper phthalocyanine (CuPc)/Aluminum (Al) Schottky diode solar cells. Here, open circuit voltages (Voc) increased from 220 mV at 15 nm to 907 mV at 140 nm. Analysis of the current-voltage characteristics indicated that tunneling and interface recombination mechanisms are important components of the current transport at the CuPc/Al junction. With the objective of higher short circuit current densities in mind, we have extended our earlier work on organic semiconductors to nanowire based designs. In this paper, we report the fabrication, materials and electrical characterization of CuPc nanowire based solar cells in AAO templates by electro-deposition. The CuPc nanowires were electrochemically deposited into the AAO templates using CHCl3 (Chloroform) containing 10-4 M CuPc with 0.5 ml of CF3COOH (Trifluoro acetic acid). The nanowires were characterized by XRD, UV-Vis absorption spectroscopy, electron microscopy and electrical measurements. CuPc nanowires were also electrodeposited onto ITO/glass substrates and compared with templated nanowires for their structural, optical and electrical properties. Effect of the PEDOT: PSS buffer layer on the nanowire based device characteristics was also investigated.