Field evaluation of skid resistant surfaces : final report : part I.

DOT National Transportation Integrated Search

1970-06-01

This project was undertaken to establish a thin bituminous surface course that would possess good skid resistant qualities as well as, being both economical and durable. : This is the final report on the evaluation of skid resistant surfaces which wa...

Optoelectronic properties and Seebeck coefficient in SnSe thin films

NASA Astrophysics Data System (ADS)

Urmila, K. S.; Namitha, T. A.; Rajani, J.; Philip, R. R.; Pradeep, B.

2016-09-01

SnSe thin films of thickness 180 nm have been deposited on glass substrates by reactive evaporation at an optimized substrate temperature of 523 ± 5 K and pressure of 10-5 mbar. The as-prepared SnSe thin films are characterized for their structural, optical and electrical properties by various experimental techniques. The p-type conductivity, near-optimum direct band gap, high absorption coefficient and good photosensitivity of the SnSe thin film indicate its suitability for photovoltaic applications. The optical constants, loss factor, quality factor and optical conductivity of the films are evaluated. The results of Hall and thermoelectric power measurements are correlated to determine the density of states, Fermi energy and effective mass of carriers and are obtained as 2.8 × 1017 cm-3, 0.03 eV and 0.05m 0 respectively. The high Seebeck coefficient ≈ 7863 μV/K, reasonably good power factor ≈ 7.2 × 10-4 W/(m·K2) and thermoelectric figure of merit ≈ 1.2 observed at 42 K suggests that, on further work, the prepared SnSe thin films can also be considered as a possible candidate for cryogenic thermoelectric applications.

Influence of sulfurization temperature on Cu2ZnSnS4 absorber layer on flexible titanium substrates for thin film solar cells

NASA Astrophysics Data System (ADS)

Gokcen Buldu, Dilara; Cantas, Ayten; Turkoglu, Fulya; Gulsah Akca, Fatime; Meric, Ece; Ozdemir, Mehtap; Tarhan, Enver; Ozyuzer, Lutfi; Aygun, Gulnur

2018-02-01

In this study, the effect of sulfurization temperature on the morphology, composition and structure of Cu2ZnSnS4 (CZTS) thin films grown on titanium (Ti) substrates has been investigated. Since Ti foils are flexible, they were preferred as a substrate. As a result of their flexibility, they allow large area manufacturing and roll-to-roll processes. To understand the effects of sulfurization temperature on the CZTS formation on Ti foils, CZTS films fabricated with various sulfurization temperatures were investigated with several analyses including x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy and Raman scattering. XRD measurements showed a sharp and intense peak coming from the (112) planes of the kesterite type lattice structure (KS), which is strong evidence for good crystallinity. The surface morphologies of our thin films were investigated using SEM. Electron dispersive spectroscopy was also used for the compositional analysis of the thin films. According to these analysis, it is observed that Ti foils were suitable as substrates for the growth of CZTS thin films with desired properties and the sulfurization temperature plays a crucial role for producing good quality CZTS thin films on Ti foil substrates.

Influence of annealing temperature on structural and magnetic properties of pulsed laser-deposited YIG films on SiO2 substrate

NASA Astrophysics Data System (ADS)

Nag, Jadupati; Ray, Nirat

2018-05-01

Yttrium Iron Garnet (Y3Fe5O12) was synthesized by solid state/ceramic process. Thin films of YIG were deposited on SiO2 substrate at room temperature(RT) and at substrate temperature (Ts) 700 °C using pulsed laser deposition (PLD) technique. RT deposited thin films are amorphous in nature and non-magnetic. After annealing at temperature 800 ° RT deposited thin films showed X-ray peaks as well as the magnetic order. Magnetic ordering is enhanced by annealing temperature(Ta ≥ 750 °C) and resulted good quality of films with high magnetization value.

Preparation, linear and NLO properties of DNA-CTMA-SBE complexes

NASA Astrophysics Data System (ADS)

Manea, Ana-Maria; Rau, Ileana; Kajzar, Francois; Meghea, Aurelia

2013-10-01

Synthesis of deoxyribonucleic acid (DNA) - was cetyltrimethylammonium (CTMA) - sea buckthorn extract (SBE) at different concentrations is decribed. The complexes were processed into good optical quality thin films by spin coating on different substrates such as: glass, silica and ITO covered glass substrates. SBE contains many bioactive substances that can be used in the treatment of several diseases, such as cardiovascular disease, cancer, and acute mountain sickness. The obtained thin films were characterized for their spectroscopic, fluorescent, linear and nonlinear optical properties as function of SBE concentration. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength.

50-mJ, 1-kHz Yb:YAG thin-disk regenerative amplifier with 969-nm pulsed pumping

NASA Astrophysics Data System (ADS)

Chyla, Michal; Miura, Taisuke; Smrž, Martin; Severova, Patricie; Novak, Ondrej; Endo, Akira; Mocek, Tomas

2014-02-01

We are developing a 100-mJ Yb:YAG thin-disk regenerative amplifier operating at 1-kHz repetition rate pumped at zero-phonon-line (968.825-nm1) and delivering 1-2 ps pulses for EUV plasma sources applicable in science and industry. Recently we achieved the output energy of nearly 50-mJ from a single laser-head cavity with good beam quality (M2<1.2) as well as stable beam-pointing (<4μrad). Applying pulsed pumping with the pulse duration shorter than the upper state lifetime of Yb:YAG helps to reduce the ASE and thermal loading of the thin-disk.

MnSi nanostructures obtained from epitaxially grown thin films: magnetotransport and Hall effect

NASA Astrophysics Data System (ADS)

Schroeter, D.; Steinki, N.; Schilling, M.; Fernández Scarioni, A.; Krzysteczko, P.; Dziomba, T.; Schumacher, H. W.; Menzel, D.; Süllow, S.

2018-06-01

We present a comparative study of the (magneto)transport properties, including Hall effect, of bulk, epitaxially grown thin film and nanostructured MnSi. In order to set our results in relation to published data we extensively characterize our materials, this way establishing a comparatively good sample quality. Our analysis reveals that in particular for thin film and nanostructured material, there are extrinsic and intrinsic contributions to the electronic transport properties, which by modeling the data we separate out. Finally, we discuss our Hall effect data of nanostructured MnSi under consideration of the extrinsic contributions and with respect to the question of the detection of a topological Hall effect in a skyrmionic lattice.

Cation disorder and gas phase equilibrium in an YBa 2Cu 3O 7- x superconducting thin film

NASA Astrophysics Data System (ADS)

Shin, Dong Chan; Ki Park, Yong; Park, Jong-Chul; Kang, Suk-Joong L.; Yong Yoon, Duk

1997-02-01

YBa 2Cu 3O 7- x superconducting thin films have been grown by in situ off-axis rf sputtering with varying oxygen pressure, Ba/Y ratio in a target, and deposition temperature. With decreasing oxygen pressure, increasing Ba/Y ratio, increasing deposition temperature, the critical temperature of the thin films decreased and the c-axis length increased. The property change of films with the variation of deposition variables has been explained by a gas phase equilibrium of the oxidation reaction of Ba and Y. Applying Le Chatelier's principle to the oxidation reaction, we were able to predict the relation of deposition variables and the resultant properties of thin films; the prediction was in good agreement with the experimental results. From the relation between the three deposition variables and gas phase equilibrium, a 3-dimensional processing diagram was introduced. This diagram has shown that the optimum deposition condition of YBa 2Cu 3O 7- x thin films is not a fixed point but can be varied. The gas phase equilibrium can also be applied to the explanation of previous results that good quality films were obtained at low deposition temperature using active species, such as O, O 3, and O 2+.

Producing Foils From Direct Cast Titanium Alloy Strip

NASA Technical Reports Server (NTRS)

Stuart, T. A.; Gaspar, T. A.; Sukonnik, I. M.; Semiatan, S. L.; Batawi, E.; Peters, J. A.; Fraser, H. L.

1996-01-01

This research was undertaken to demonstrate the feasibility of producing high-quality, thin-gage, titanium foil from direct cast titanium strip. Melt Overflow Rapid Solidification Technology (MORST) was used to cast several different titanium alloys into 500 microns thick strip, 10 cm wide and up to 3 m long. The strip was then either ground, hot pack rolled or cold rolled, as appropriate, into foil. Gamma titanium aluminide (TiAl) was cast and ground to approximately 100 microns thick foil and alpha-2 titanium aluminide (Ti3AI) was cast and hot pack rolled to approximately 70 microns thick foil. CP Ti, Ti6Al2Sn4Zr2Mo, and Ti22AI23Nb (Orthorhombic), were successfully cast and cold-rolled into good quality foil (less than 125 microns thick). The foils were generally fully dense with smooth surfaces, had fine, uniform microstructures, and demonstrated mechanical properties equivalent to conventionally produced titanium. By eliminating many manufacturing steps, this technology has the potential to produce thin gage, titanium foil with good engineering properties at significantly reduced cost relative to conventional ingot metallurgy processing.

Development of Novel Non-Contact Electrodes for Mobile Electrocardiogram Monitoring System

PubMed Central

Chou, Willy; Wang, Hsing-Yu; Huang, Yan-Jun; Pan, Jeng-Shyang

2013-01-01

Real-time monitoring of cardiac health is helpful for patients with cardiovascular disease. Many telemedicine systems based on ubiquitous computing and communication techniques have been proposed for monitoring the user's electrocardiogram (ECG) anywhere and anytime. Usually, wet electrodes are used in these telemedicine systems. However, wet electrodes require conduction gels and skin preparation that can be inconvenient and uncomfortable for users. In order to overcome this issue, a new non-contact electrode circuit was proposed and applied in developing a mobile electrocardiogram monitoring system. The proposed non-contact electrode can measure bio-potentials across thin clothing, allowing it to be embedded in a user's normal clothing to monitor ECG in daily life. We attempted to simplify the design of these non-contact electrodes to reduce power consumption while continuing to provide good signal quality. The electrical specifications and the performance of monitoring arrhythmia in clinical settings were also validated to investigate the reliability of the proposed design. Experimental results show that the proposed non-contact electrode provides good signal quality for measuring ECG across thin clothes. PMID:27170853

Rheology and stability kinetics of bare silicon nanoparticle inks for low-cost direct printing

DOE Office of Scientific and Technical Information (OSTI.GOV)

More, Priyesh V.; Jeong, Sunho; Seo, Yeong-Hui

2013-12-16

Highly dispersed and stable silicon nanoparticles ink is formulated for its application in direct printing or printable electronics. These dispersions are prepared from free-standing silicon nanoparticles which are not capped with any organic ligand, making it suitable for electronic applications. Silicon nanoparticles dispersions are prepared by suspending the nanoparticles in benzonitrile or ethanol by using polypropylene glycol (PPG) as a binder. All the samples show typical shear thinning behavior while the dispersion samples show low viscosities signifying good quality dispersion. Such thinning behavior favors in fabrication of dense films with spin-coating or patterns with drop casting. The dispersion stability ismore » monitored by turbiscan measurements showing good stability for one week. A low-cost direct printing method for dispersion samples is also demonstrated to obtain micro-sized patterns. Low electrical resistivity of resulting patterns, adjustable viscosity and good stability makes these silicon nanoparticles dispersions highly applicable for direct printing process.« less

Mask-free, vacuum-free fabrication of high-conductivity metallic nanowire by spatially shaped ultrafast laser (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wang, Andong; Li, Xiaowei; Qu, Lianti; Lu, Yongfeng; Jiang, Lan

2017-03-01

Metal nanowire fabrication has drawn tremendous attention in recent years due to its wide application in electronics, optoelectronics, and plasmonics. However, conventional laser fabrication technologies are limited by diffraction limit thus the fabrication resolution cannot meet the increasingly high demand of modern devices. Herein we report on a novel method for high-resolution high-quality metal nanowire fabrication by using Hermite-Gaussian beam to ablate metal thin film. The nanowire is formed due to the intensity valley in the center of the laser beam while the surrounding film is ablated. Arbitrary nanowire can be generated on the substrate by dynamically adjusting the orientation of the intensity valley. This method shows obvious advantages compared to conventional methods. First, the minimum nanowire has a width of 60 nm (≍1/13 of the laser wavelength), which is much smaller than the diffraction limit. The high resolution is achieved by combining the ultrashort nature of the femtosecond laser and the low thermal conductivity of the thin film. In addition, the fabricated nanowires have good inside qualities. No inner nanopores and particle intervals are generated inside the nanowire, thus endowing the nanowire with good electronic characteristics: the conductivity of the nanowires is as high as 1.2×107 S/m (≍1/4 of buck material), and the maximum current density is up to 1.66×108 A/m2. Last, the nanowire has a good adhesion to the substrates, which can withstand ultrasonic bath for a long time. These advantages make our method a good approach for high-resolution high-quality nanowire fabrication as a complementary method to conventional lithography methods.

Pulsed laser deposition of air-sensitive hydride epitaxial thin films: LiH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oguchi, Hiroyuki, E-mail: oguchi@nanosys.mech.tohoku.ac.jp; Micro System Integration Center; Isobe, Shigehito

2015-09-01

We report on the epitaxial thin film growth of an air-sensitive hydride, lithium hydride (LiH), using pulsed laser deposition (PLD). We first synthesized a dense LiH target, which is key for PLD growth of high-quality hydride films. Then, we obtained epitaxial thin films of [100]-oriented LiH on a MgO(100) substrate at 250 °C under a hydrogen pressure of 1.3 × 10{sup −2} Pa. Atomic force microscopy revealed that the film demonstrates a Stranski-Krastanov growth mode and that the film with a thickness of ∼10 nm has a good surface flatness, with root-mean-square roughness R{sub RMS} of ∼0.4 nm.

Effect of Annealing Temperature on Structural, Optical, and Electrical Properties of Sol-Gel Spin-Coating-Derived Cu2ZnSnS4 Thin Films

NASA Astrophysics Data System (ADS)

Hosseinpour, Rabie; Izadifard, Morteza; Ghazi, Mohammad Ebrahim; Bahramian, Bahram

2018-02-01

The effect of annealing temperature on structural, optical, and electrical properties of Cu2ZnSnS4 (CZTS) thin films grown on a glass substrate by spin coating sol-gel technique has been studied. Structural study showed that all samples had kesterite crystalline structure. Scanning electron microscopy images showed that the crystalline quality of the samples was improved by heat treatment. Optical study showed that the energy gap values for the samples ranged from 1.55 eV to 1.78 eV. Moreover, good optical conductivity values (1012 S-1 to 1014 S-1) were obtained for the samples. Investigation of the electrical properties of the CZTS thin films showed that the carrier concentration increased significantly with the annealing temperature. The photoelectrical behavior of the samples revealed that the photocurrent under light illumination increased significantly. Overall, the results show that the CZTS thin films annealed at 500°C had better structural, optical, and electrical properties and that such CZTS thin films are desirable for use as absorber layers in solar cells. The photovoltaic properties of the CZTS layer annealed at 500°C were also investigated and the associated figure of merit calculated. The results showed that the fabricated ZnS-CZTS heterojunction exhibited good rectifying behavior but rather low fill factor.

High-quality crystalline yttria-stabilized-zirconia thin layer for photonic applications

NASA Astrophysics Data System (ADS)

Marcaud, Guillaume; Matzen, Sylvia; Alonso-Ramos, Carlos; Le Roux, Xavier; Berciano, Mathias; Maroutian, Thomas; Agnus, Guillaume; Aubert, Pascal; Largeau, Ludovic; Pillard, Valérie; Serna, Samuel; Benedikovic, Daniel; Pendenque, Christopher; Cassan, Eric; Marris-Morini, Delphine; Lecoeur, Philippe; Vivien, Laurent

2018-03-01

Functional oxides are considered as promising materials for photonic applications due to their extraordinary and various optical properties. Especially, yttria-stabilized zirconia (YSZ) has a high refractive index (˜2.15), leading to a good confinement of the optical mode in waveguides. Furthermore, YSZ can also be used as a buffer layer to expand toward a large family of oxides-based thin-films heterostructures. In this paper, we report a complete study of the structural properties of YSZ for the development of integrated optical devices on sapphire in telecom wavelength range. The substrate preparation and the epitaxial growth using pulsed-laser deposition technique have been studied and optimized. High-quality YSZ thin films with remarkably sharp x-ray diffraction rocking curve peaks in 10-3∘ range have then been grown on sapphire (0001). It was demonstrated that a thermal annealing of sapphire substrate before the YSZ growth allowed controlling the out-of-plane orientation of the YSZ thin film. Single-mode waveguides were finally designed, fabricated, and characterized for two different main orientations of high-quality YSZ (001) and (111). Propagation loss as low as 2 dB/cm at a wavelength of 1380 nm has been demonstrated for both orientations. These results pave the way for the development of a functional oxides-based photonics platform for numerous applications including on-chip optical communications and sensing.

Spectroscopic Study of Deep Level Emissions from Acceptor Defects in ZnO Thin Films with Oxygen Rich Stoichiometry

NASA Astrophysics Data System (ADS)

Ilyas, Usman; Rawat, R. S.; Tan, T. L.

2013-10-01

This paper reports the tailoring of acceptor defects in oxygen rich ZnO thin films at different post-deposition annealing temperatures (500-800°C) and Mn doping concentrations. The XRD spectra exhibited the nanocrystalline nature of ZnO thin films along with inconsistent variation in lattice parameters suggesting the temperature-dependent activation of structural defects. Photoluminescence emission spectra revealed the temperature dependent variation in deep level emissions (DLE) with the presence of acceptors as dominating defects. The concentration of native defects was estimated to be increased with temperature while a reverse trend was observed for those with increasing doping concentration. A consistent decrease in DLE spectra, with increasing Mn content, revealed the quenching of structural defects in the optical band gap of ZnO favorable for good quality thin films with enhanced optical transparency.

Development of highly-ordered, ferroelectric inverse opal films using sol gel infiltration

NASA Astrophysics Data System (ADS)

Matsuura, N.; Yang, S.; Sun, P.; Ruda, H. E.

2005-07-01

Highly-ordered, ferroelectric, Pb-doped Ba0.7Sr0.3TiO3, inverse opal films were fabricated by spin-coating a sol gel precursor into a polystyrene artificial opal template followed by heat treatment. Thin films of the ferroelectric were independently studied and were shown to exhibit good dielectric properties and high refractive indices. The excellent quality of the final inverse opal film using this spin-coating infiltration method was confirmed by scanning electron microscopy images and the good correspondence between optical reflection data and theoretical simulations. Using this method, the structural and material parameters of the final ferroelectric inverse opal film were easily adjusted by template heating and through repeated infiltrations, without changes in the initial template or precursor. Also, crack-free inverse opal thin films were fabricated over areas comparable to that of the initial crack-free polystyrene template (˜100 by 100 μm2).

Annealing temperature effect on electrical properties of MEH-PPV thin film via spin coating method

NASA Astrophysics Data System (ADS)

Azhar, N. E. A.; Shariffudin, S. S.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Organic semiconductor has been discovered in different application devices such as organic light emitting diodes (OLEDs). Poly [2-methoxy-5(2' -ethylhexyloxy)-1, 4-phenylenevinylene), MEH-PPV widely used in this device because its ability to produce a good optical quality films. The MEH-PPV was prepared on glass substrate by spin coating method. The thin film was investigated at different annealing temperatures. The scanning electron micrographs (SEM) revealed that sample annealed at 50°C showed uniformity and less aggregation on morphology polymer thin film. Optical properties showed the intensities of visible emission increased as temperatures increased. The current-voltage (I-V) measurement revealed that the temperature of 50°C showed high conductive and it is suitable for optoelectronic device.

Preparation and characterization of copper telluride thin films by modified chemical bath deposition (M-CBD) method

NASA Astrophysics Data System (ADS)

Pathan, H. M.; Lokhande, C. D.; Amalnerkar, D. P.; Seth, T.

2003-09-01

Copper telluride thin films were deposited using modified chemical method using copper(II) sulphate; pentahydrate [CuSO 4·5H 2O] and sodium tellurite [Na 2TeO 3] as cationic and anionic sources, respectively. Modified chemical method is based on the immersion of the substrate into separately placed cationic and anionic precursors. The preparative conditions such as concentration, pH, immersion time, immersion cycles, etc. were optimized to get good quality copper telluride thin films at room temperature. The films have been characterized for structural, compositional, optical and electrical transport properties by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Rutherford back scattering (RBS), optical absorption/transmission, electrical resistivity and thermoemf measurement techniques.

Ultraviolet electroluminescence from hetero p-n junction between a single ZnO microsphere and p-GaN thin film.

PubMed

Tetsuyama, Norihiro; Fusazaki, Koshi; Mizokami, Yasuaki; Shimogaki, Tetsuya; Higashihata, Mitsuhiro; Nakamura, Daisuke; Okada, Tatsuo

2014-04-21

We report ultraviolet electroluminescence from a hetero p-n junction between a single ZnO microsphere and p-GaN thin film. ZnO microspheres, which have high crystalline quality, have been synthesized by ablating a ZnO sintered target. It was found that synthesized ZnO microspheres had a high-optical property and exhibit the laser action in the whispering gallery mode under pulsed optical pumping. A hetero p-n junction was formed between the single ZnO microsphere/ p-GaN thin film, and a good rectifying property with a turn-on voltage of approximately 6 V was observed in I-V characteristic across the junction. Ultraviolet and visible electroluminescence were observed under forward bias.

High-Quality Professional Development for Teachers: Supporting Teacher Training to Improve Student Learning

ERIC Educational Resources Information Center

DeMonte, Jenny

2013-01-01

Professional development in education has gotten a bad reputation, and for good reason. Everyone on all sides of the education reform and improvement debate agrees that what most teachers receive as professional opportunities to learn are thin, sporadic, and of little use when it comes to improving teaching. This paper is the first of a periodic…

Some aspects over the quality of thin films deposited on special steels used in hydraulic blades

NASA Astrophysics Data System (ADS)

Tugui, C. A.; Vizureanu, P.; Iftimie, N.; Steigmann, R.

2016-08-01

The experimental research involved in this paper consists in the obtaining of superior physical, chemical and mechanical properties of stainless steels used in the construction of hydraulic turbine blades. These properties are obtained by deposition of hard thin films in order to improve the wear resistance, increasing the hardness but maintaining the tenacious core of the material. The chosen methods for deposition are electrospark deposition because it has relatively low costs, are easy to obtain, the layers have a good adherence to support and the thickness can be variable in function of the established conditions and the pulsed laser deposition because high quality films can be obtained at nanometric precision. The samples will be prepared for the analysis of the structure using optical method as well as for the obtaining of the optimal roughness for the deposition. The physical, chemical and mechanical properties will be determined after deposition using SEM and EDX, in order to emphasize the structure film-substrate and repartition of the deposition elements on the surface and in transversal section. The non-destructive testing has emphasized the good adherence between deposited layer and the metallic support, due to double deposition, spallation regions doesn't appear.

High-Quality Solution-Processed Silicon Oxide Gate Dielectric Applied on Indium Oxide Based Thin-Film Transistors.

PubMed

Jaehnike, Felix; Pham, Duy Vu; Anselmann, Ralf; Bock, Claudia; Kunze, Ulrich

2015-07-01

A silicon oxide gate dielectric was synthesized by a facile sol-gel reaction and applied to solution-processed indium oxide based thin-film transistors (TFTs). The SiOx sol-gel was spin-coated on highly doped silicon substrates and converted to a dense dielectric film with a smooth surface at a maximum processing temperature of T = 350 °C. The synthesis was systematically improved, so that the solution-processed silicon oxide finally achieved comparable break downfield strength (7 MV/cm) and leakage current densities (<10 nA/cm(2) at 1 MV/cm) to thermally grown silicon dioxide (SiO2). The good quality of the dielectric layer was successfully proven in bottom-gate, bottom-contact metal oxide TFTs and compared to reference TFTs with thermally grown SiO2. Both transistor types have field-effect mobility values as high as 28 cm(2)/(Vs) with an on/off current ratio of 10(8), subthreshold swings of 0.30 and 0.37 V/dec, respectively, and a threshold voltage close to zero. The good device performance could be attributed to the smooth dielectric/semiconductor interface and low interface trap density. Thus, the sol-gel-derived SiO2 is a promising candidate for a high-quality dielectric layer on many substrates and high-performance large-area applications.

Thin disk laser with unstable resonator and reduced output coupler

NASA Astrophysics Data System (ADS)

Gavili, Anwar; Shayganmanesh, Mahdi

2018-05-01

In this paper, feasibility of using unstable resonator with reduced output coupling in a thin disk laser is studied theoretically. Unstable resonator is modeled by wave-optics using Collins integral and iterative method. An Yb:YAG crystal with 250 micron thickness is considered as a quasi-three level active medium and modeled by solving rate equations of energy levels populations. The amplification of laser beam in the active medium is calculated based on the Beer-Lambert law and Rigrod method. Using generalized beam parameters method, laser beam parameters like, width, divergence, M2 factor, output power as well as near and far-field beam profiles are calculated for unstable resonator. It is demonstrated that for thin disk laser (with single disk) in spite of the low thickness of the disk which leads to low gain factor, it is possible to use unstable resonator (with reduced output coupling) and achieve good output power with appropriate beam quality. Also, the behavior of output power and beam quality versus equivalent Fresnel number is investigated and optimized value of output coupling for maximum output power is achieved.

Design of a thin-plate based tunable high-quality narrow passband filter for elastic transverse waves propagate in metals

NASA Astrophysics Data System (ADS)

Zhang, J.; Zeng, L. H.; Hu, C. L.; Yan, W. S.; Pennec, Yan; Hu, N.

2018-03-01

For the elastic SV (transverse) waves in metals, a high-quality narrow passband filter that consists of aligned parallel thin plates with small gaps is designed. In order to obtain a good performance, the thin plates should be constituted by materials with a smaller mass density and Young's modulus, such as polymethylmethacrylate (PMMA), compared to the embedded materials in which the elastic SV waves propagate. Both the theoretical model and the full numerical simulation show that the transmission spectrum of the designed filter demonstrates several peaks with flawless transmission within 0 KHz ˜20 KHz frequency range. The peaks can be readily tuned by manipulating the geometrical parameters of the plates. Therefore, the current design works well for both low and high frequencies with a controllable size. Even for low frequencies on the order of kilohertz, the size of this filter can be still limited to the order of centimeters, which significantly benefits the real applications. The investigation also finds that the same filter is valid when using different metals and the reason behind this is explained theoretically. Additionally, the effect of bonding conditions of interfaces between thin plates and the base material is investigated using a spring model.

Photonic devices on planar and curved substrates and methods for fabrication thereof

DOEpatents

Bartl, Michael H.; Barhoum, Moussa; Riassetto, David

2016-08-02

A versatile and rapid sol-gel technique for the fabrication of high quality one-dimensional photonic bandgap materials. For example, silica/titania multi-layer materials may be fabricated by a sol-gel chemistry route combined with dip-coating onto planar or curved substrate. A shock-cooling step immediately following the thin film heat-treatment process is introduced. This step was found important in the prevention of film crack formation--especially in silica/titania alternating stack materials with a high number of layers. The versatility of this sol-gel method is demonstrated by the fabrication of various Bragg stack-type materials with fine-tuned optical properties by tailoring the number and sequence of alternating layers, the film thickness and the effective refractive index of the deposited thin films. Measured optical properties show good agreement with theoretical simulations confirming the high quality of these sol-gel fabricated optical materials.

A 6-month, randomized, double-blind, placebo-controlled study evaluating the ability of a marine complex supplement to promote hair growth in men with thinning hair.

PubMed

Ablon, Glynis

2016-12-01

Male pattern baldness, or androgenetic alopecia, affects approximately 50% of the adult population and can cause poor self-image, low self-esteem and have a significant negative impact on the quality of life. An oral nutraceutical supplement based on a marine complex formulation has previously been reported to significantly increase the number of terminal hairs in women with thinning hair. The objective of this double-blind, placebo-controlled study was to confirm the beneficial effects of a similar marine complex supplement in adult male subjects with thinning hair (Viviscal ® Man; Lifes2good, Inc., Chicago, IL, USA). Healthy adult male subjects with thinning hair associated with clinically diagnosed male pattern hair loss were enrolled and randomized to receive study drug or placebo twice daily. At Day 90, subjects indicated a significant improvement in three of six quality of life measures as well as a significant overall improvement in quality of life. After 180 days, significant increases were observed for total hair count, total hair density, and terminal hair density (for each, P = 0.001). The investigator assessments revealed significant improvements in terminal and vellus hair count and terminal hair density. Hair pull test results were significantly lower (fewer hairs removed) for study drug vs. placebo at Days 90 (P < 0.05) and 180 (P < 0.01). There were no reports of treatment-emergent adverse events. The results of this study showed for the first time that a dietary supplement containing a marine complex and other ingredients can decrease hair shedding and promote hair growth in men with thinning hair. © 2016 Wiley Periodicals, Inc.

High-efficiency thin-film GaAs solar cells, phase2

NASA Technical Reports Server (NTRS)

Yeh, Y. C. M.

1981-01-01

Thin GaAs epi-layers with good crystallographic quality were grown using a (100) Si-substrate on which a thin Ge epi-interlayer was grown by CVD from germane. Both antireflection-coated metal oxide semiconductor (AMOS) and n(+)/p homojunction structures were studied. The AMOS cells were fabricated on undoped-GaAs epi-layers deposited on bulk poly-Ge substrates using organo-metallic CVD film-growth, with the best achieved AM1 conversion efficiency being 9.1%. Both p-type and n(+)-type GaAs growth were optimized using 50 ppm dimethyl zinc and 1% hydrogen sulfide, respectively. A direct GaAs deposition method in fabricating ultra-thin top layer, epitaxial n(+)/p shallow homojunction solar cells on (100) GaAs substrates (without anodic thinning) was developed to produce large area (1 sq/cm) cells, with 19.4% AM1 conversion efficiency achieved. Additionally, an AM1 conversion efficiency of 18.4% (17.5% with 5% grid coverage) was achieved for a single crystal GaAs n(+)/p cell grown by OM-CVD on a Ge wafer.

Preferential growth and enhanced dielectric properties of Ba0.7Sr0.3TiO3 thin films with preannealed Pt bottom electrode

NASA Astrophysics Data System (ADS)

Zhu, Xiaohong; Defaÿ, Emmanuel; Aïd, Marc; Ren, Yinjuan; Zhang, Caiyun; Zhu, Jiliang; Zhu, Jianguo; Xiao, Dingquan

2013-03-01

Ba0.7Sr0.3TiO3 (BST) thin films, about 100 nm in thickness, were prepared on unannealed and 700 °C-preannealed Pt bottom electrodes by the ion beam sputtering and post-deposition annealing method. It was found that the preannealed Pt layer has a more compact structure, making it not only a bottom electrode but also a good template for high-quality BST thin film growth. The BST films deposited on preannealed Pt bottom electrodes showed (0 0 l)-preferred orientation, dense and uniform microstructure with no intermediate phase formed at the film/electrode interface, and thus enhanced dielectric properties. As a result, the typical relative dielectric constant and tunability (under a dc electric field of 1 MV cm-1) reach 180 and 50.1%, respectively, for the BST thin films with preannealed Pt bottom electrodes, which are significantly higher than those (166 and 41.3%, respectively) for the BST thin films deposited on unannealed Pt bottom electrodes.

Thermally evaporated methylammonium tin triiodide thin films for lead-free perovskite solar cell fabrication

DOE PAGES

Yu, Yue; Zhao, Dewei; Grice, Corey R.; ...

2016-09-16

Here, we report on the synthesis of methylammonium tin triiodide (MASnI 3) thin films at room temperature by a hybrid thermal evaporation method and their application in fabricating lead (Pb)-free perovskite solar cells. The as-deposited MASnI 3 thin films exhibit smooth surfaces, uniform coverage across the entire substrate, and strong crystallographic preferred orientation along the < 100 > direction. By incorporating this film with an inverted planar device architecture, our Pb-free perovskite solar cells are able to achieve an open-circuit voltage ( V oc) up to 494 mV. The relatively high V oc is mainly ascribed to the excellent surfacemore » coverage, the compact morphology, the good stoichiometry control of the MASnI 3 thin films, and the effective passivation of the electron-blocking and hole-blocking layers. Finally, our results demonstrate the potential capability of the hybrid evaporation method to prepare high-quality Pb-free MASnI 3 perovskite thin films which can be used to fabricate efficient Pb-free perovskite solar cells.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, J.; Nichols, John A.; Lee, Shinbuhm

Metal electrodes are a universal element of all electronic devices. Conducting SrRuO 3 (SRO) epitaxial thin films have been extensively used as electrodes in complex-oxide heterostructures due to good lattice mismatches with perovskite substrates. However, when compared to SRO single crystals, SRO thin films have shown reduced conductivity and Curie temperatures (T C), which can lead to higher Joule heating and energy loss in the devices. In this paper, we report that high-quality SRO thin films can be synthesized by controlling the plume dynamics and growth rate of pulsed laser epitaxy (PLE) with real-time optical spectroscopic monitoring. The SRO thinmore » films grown under the kinetically controlled conditions, down to ca. 16 nm in thickness, exhibit both enhanced conductivity and T C as compared to bulk values, due to their improved stoichiometry and a strain-mediated increase of the bandwidth of Ru 4d electrons. Finally, this result provides a direction for enhancing the physical properties of PLE-grown thin films and paves a way to improved device applications.« less

Spin Seebeck effect in insulating epitaxial γ-Fe2O3 thin films

NASA Astrophysics Data System (ADS)

Jiménez-Cavero, P.; Lucas, I.; Anadón, A.; Ramos, R.; Niizeki, T.; Aguirre, M. H.; Algarabel, P. A.; Uchida, K.; Ibarra, M. R.; Saitoh, E.; Morellón, L.

2017-02-01

We report the fabrication of high crystal quality epitaxial thin films of maghemite (γ-Fe2O3), a classic ferrimagnetic insulating iron oxide. Spin Seebeck effect (SSE) measurements in γ-Fe2O3/Pt bilayers as a function of sample preparation conditions and temperature yield a SSE coefficient of 0.5(1) μV/K at room temperature. Dependence on temperature allows us to estimate the magnon diffusion length in maghemite to be in the range of tens of nanometers, in good agreement with that of conducting iron oxide magnetite (Fe3O4), establishing the relevance of spin currents of magnonic origin in magnetic iron oxides.

Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering

PubMed Central

López-Huerta, Francisco; Cervantes, Blanca; González, Octavio; Hernández-Torres, Julián; García-González, Leandro; Vega, Rosario; Herrera-May, Agustín L.; Soto, Enrique

2014-01-01

We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2) thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C). The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG) of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control substrate during 18 to 24 h. These neurons are activated by electrical stimuli and its ionic currents and action potential activity recorded. Through X-ray diffraction (XRD), the surface of TiO2 thin films showed a good quality, homogeneity and roughness. The XRD results showed the anatase to rutile phase transition in TiO2 thin films at temperatures between 500 and 1100 °C. This phase had a grain size from 15 to 38 nm, which allowed a suitable structural and crystal phase stability of the TiO2 thin films for low and high temperature. The biocompatibility experiments of these films indicated that they were appropriated for culture of living neurons which displayed normal electrical behavior. PMID:28788667

Assembly and evaluation of a pyroelectric detector bonded to vertically aligned multiwalled carbon nanotubes over thin silicon.

PubMed

Theocharous, E; Theocharous, S P; Lehman, J H

2013-11-20

A novel pyroelectric detector consisting of a vertically aligned nanotube array on thin silicon (VANTA/Si) bonded to a 60 μm thick crystal of LiTaO₃ has been fabricated. The performance of the VANTA/Si-coated pyroelectric detector was evaluated using National Physical Laboratory's (NPL's) detector-characterization facilities. The relative spectral responsivity of the detector was found to be spectrally flat in the 0.8-24 μm wavelength range, in agreement with directional-hemispherical reflectance measurements of witness samples of the VANTA. The spatial uniformity of response of the test detector exhibited good uniformity, although the nonuniformity increased with increasing modulation frequency. The nonuniformity may be assigned either to the dimensions of the VANTA or the continuity of the bond between the VANTA/Si coating and the pyroelectric crystal substrate. The test detector exhibited a small superlinear response, which is similar to that of pyroelectric detectors coated with good quality gold-black coatings.

Improved growth of GaN layers on ultra thin silicon nitride/Si (1 1 1) by RF-MBE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Mahesh; Roul, Basanta; Central Research Laboratory, Bharat Electronics, Bangalore 560013

High-quality GaN epilayers were grown on Si (1 1 1) substrates by molecular beam epitaxy using a new growth process sequence which involved a substrate nitridation at low temperatures, annealing at high temperatures, followed by nitridation at high temperatures, deposition of a low-temperature buffer layer, and a high-temperature overgrowth. The material quality of the GaN films was also investigated as a function of nitridation time and temperature. Crystallinity and surface roughness of GaN was found to improve when the Si substrate was treated under the new growth process sequence. Micro-Raman and photoluminescence (PL) measurement results indicate that the GaN filmmore » grown by the new process sequence has less tensile stress and optically good. The surface and interface structures of an ultra thin silicon nitride film grown on the Si surface are investigated by core-level photoelectron spectroscopy and it clearly indicates that the quality of silicon nitride notably affects the properties of GaN growth.« less

The silane depletion fraction as an indicator for the amorphous/crystalline silicon interface passivation quality

NASA Astrophysics Data System (ADS)

Descoeudres, A.; Barraud, L.; Bartlome, R.; Choong, G.; De Wolf, Stefaan; Zicarelli, F.; Ballif, C.

2010-11-01

In silicon heterojunction solar cells, thin amorphous silicon layers passivate the crystalline silicon wafer surfaces. By using in situ diagnostics during plasma-enhanced chemical vapor deposition (PECVD), the authors report how the passivation quality of such layers directly relate to the plasma conditions. Good interface passivation is obtained from highly depleted silane plasmas. Based upon this finding, layers deposited in a large-area very high frequency (40.68 MHz) PECVD reactor were optimized for heterojunction solar cells, yielding aperture efficiencies up to 20.3% on 4 cm2 cells.

Photodeposition of amorphous polydiacetylene films from monomer solutions onto transparent substrates

NASA Technical Reports Server (NTRS)

Paley, M. S.; Frazier, D. O.; Abdeldeyem, H.; Armstrong, S.; McManus, S. P.

1995-01-01

Polydiacetylenes are a very promising class of polymers for both photonic and electronic applications because of their highly conjugated structures. For these applications, high-quality thin polydiacetylene films are required. We have discovered a novel technique for obtaining such films of a polydiacetylene derivative of 2-methyl-4-nitroaniline using photodeposition from monomer solutions onto UV transparent substrates. This heretofore unreported process yields amorphous polydiacetylene films with thicknesses on the order of I micron that have optical quality superior to that of films grown by standard crystal growth techniques. Furthermore, these films exhibit good third-order nonlinear optical susceptibilities; degenerate four-wave mixing experiments give x(3) values on the order of 10(exp -8) - 10(exp -7) esu. We have conducted masking experiments which demonstrate that photodeposition occurs only where the substrate is directly irradiated, clearly indicating that the reaction occurs at the surface. Additionally, we have also been able to carry out photodeposition using lasers to form thin polymer circuits. In this work, we discuss the photodeposition of polydiacetylene thin films from solution, perform chemical characterization of these films, investigate the role of the substrate, speculate on the mechanism of the reaction, and make a preliminary determination of the third-order optical nonlinearity of the films. This simple, straightforward technique may ultimately make feasible the production of polydiacetylene thin films for technological applications.

Nonlinear Optical Properties of Organic and Polymeric Thin Film Materials of Potential for Microgravity Processing Studies

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.; Penn, Benjamin; Witherow, William K.; Bank, Curtis; Shields, Angela; Hicks, Rosline; Ashley, Paul R.

1996-01-01

In this paper, we will take a closer look at the state of the art of polydiacetylene, and metal-free phthalocyanine films, in view of the microgravity impact on their optical properties, their nonlinear optical properties and their potential advantages for integrated optics. These materials have many attractive features with regard to their use in integrated optical circuits and optical switching. Thin films of these materials processed in microgravity environment show enhanced optical quality and better molecular alignment than those processed in unit gravity. Our studies of these materials indicate that microgravity can play a major role in integrated optics technology. Polydiacetylene films are produced by UV irradiation of monomer solution through an optical window. This novel technique of forming polydiacetylene thin films has been modified for constructing sophisticated micro-structure integrated optical patterns using a pre-programmed UV-Laser beam. Wave guiding through these thin films by the prism coupler technique has been demonstrated. The third order nonlinear parameters of these films have been evaluated. Metal-free phthalocyanine films of good optical quality are processed in our laboratories by vapor deposition technique. Initial studies on these films indicate that they have excellent chemical, laser, and environmental stability. They have large nonlinear optical parameters and show intrinsic optical bistability. This bistability is essential for optical logic gates and optical switching applications. Waveguiding and device making investigations of these materials are underway.

Stand quality management of a water oak plantation in Louisiana: preliminary results following thinning

Treesearch

James S. Meadows; Daniel A., Jr. Skojac

2010-01-01

Stand quality management is a new guiding principle in which thinning prescriptions are based on tree quality rather than on residual stand density. We recently initiated a series of hardwood thinning studies to determine the effects of four stand quality management thinning prescriptions on both stand-level and individual-tree-level growth, quality, and value: (1) no...

Studies on the performance of TiO{sub 2} thin films as protective layer to chlorophyll in Ocimum tenuiflorum L from UV radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malliga, P.; Selvi, B. Karunai; Pandiarajan, J.

Thin films of TiO{sub 2} were prepared on glass substrates using sol-gel dip coating technique. The films with 10 coatings were prepared and annealed at temperatures 350°C, 450°C and 550°C for 1 hour in muffle furnace. The annealed films were characterized by X – Ray diffraction (XRD), UV – Visible, AFM, Field Effect Scanning Electron Microscopy (FESEM) and EDAX studies. Chlorophyll has many health benefits due to its structural similarity to human blood and its good chelating ability. It has antimutagenic and anticarcinogenic properties. UV light impairs photosynthesis and reduces size, productivity, and quality in many of the crop plantmore » species. Increased exposure of UV light reduces chlorophyll contents a, b and total content in plants. Titanium Dioxide (TiO{sub 2}) is a wide band gap semiconductor and efficient light harvester. TiO{sub 2} has strong UltraViolet (UV) light absorbing capability. Here, we have studied the performance of TiO{sub 2} thin films as a protective layer to the chlorophyll contents present in medicinal plant, tulsi (Ocimum tenuiflorum L) from UV radiation. The study reveals that crystallite size increases, transmittance decreases and chlorophyll contents increases with increase in annealing temperature. This study showed that TiO{sub 2} thin films are good absorber of UV light and protect the chlorophyll contents a, b and total content in medicinal plants.« less

Surface modifications of crystal-ion-sliced LiNbO3 thin films by low energy ion irradiations

NASA Astrophysics Data System (ADS)

Bai, Xiaoyuan; Shuai, Yao; Gong, Chaoguan; Wu, Chuangui; Luo, Wenbo; Böttger, Roman; Zhou, Shengqiang; Zhang, Wanli

2018-03-01

Single crystalline 128°Y-cut LiNbO3 thin films with a thickness of 670 nm are fabricated onto Si substrates by means of crystal ion slicing (CIS) technique, adhesive wafer bonding using BCB as the medium layer to alleviate the large thermal coefficient mismatch between LiNbO3 and Si, and the X-ray diffraction pattern indicates the exfoliated thin films have good crystalline quality. The LiNbO3 thin films are modified by low energy Ar+ irradiation, and the surface roughness of the films is decreased from 8.7 nm to 3.4 nm. The sputtering of the Ar+ irradiation is studied by scanning electron microscope, atomic force microscope and X-ray photoelectron spectroscopy, and the results show that an amorphous layer exists at the surface of the exfoliated film, which can be quickly removed by Ar+ irradiation. A two-stage etching mechanism by Ar+ irradiation is demonstrated, which not only establishes a new non-contact surface polishing method for the CIS-fabricated single crystalline thin films, but also is potentially useful to remove the residue damage layer produced during the CIS process.

Nanomechanical Behavior of High Gas Barrier Multilayer Thin Films.

PubMed

Humood, Mohammad; Chowdhury, Shahla; Song, Yixuan; Tzeng, Ping; Grunlan, Jaime C; Polycarpou, Andreas A

2016-05-04

Nanoindentation and nanoscratch experiments were performed on thin multilayer films manufactured using the layer-by-layer (LbL) assembly technique. These films are known to exhibit high gas barrier, but little is known about their durability, which is an important feature for various packaging applications (e.g., food and electronics). Films were prepared from bilayer and quadlayer sequences, with varying thickness and composition. In an effort to evaluate multilayer thin film surface and mechanical properties, and their resistance to failure and wear, a comprehensive range of experiments were conducted: low and high load indentation, low and high load scratch. Some of the thin films were found to have exceptional mechanical behavior and exhibit excellent scratch resistance. Specifically, nanobrick wall structures, comprising montmorillonite (MMT) clay and polyethylenimine (PEI) bilayers, are the most durable coatings. PEI/MMT films exhibit high hardness, large elastic modulus, high elastic recovery, low friction, low scratch depth, and a smooth surface. When combined with the low oxygen permeability and high optical transmission of these thin films, these excellent mechanical properties make them good candidates for hard coating surface-sensitive substrates, where polymers are required to sustain long-term surface aesthetics and quality.

Integrating Epitaxial-Like Pb(Zr,Ti)O3 Thin-Film into Silicon for Next-Generation Ferroelectric Field-Effect Transistor

PubMed Central

Park, Jae Hyo; Kim, Hyung Yoon; Jang, Gil Su; Seok, Ki Hwan; Chae, Hee Jae; Lee, Sol Kyu; Kiaee, Zohreh; Joo, Seung Ki

2016-01-01

The development of ferroelectric random-access memory (FeRAM) technology with control of grain boundaries would result in a breakthrough for new nonvolatile memory devices. The excellent piezoelectric and electrical properties of bulk ferroelectrics are degraded when the ferroelectric is processed into thin films because the grain boundaries then form randomly. Controlling the nature of nucleation and growth are the keys to achieving a good crystalline thin-film. However, the sought after high-quality ferroelectric thin-film has so far been thought to be impossible to make, and research has been restricted to atomic-layer deposition which is extremely expensive and has poor reproducibility. Here we demonstrate a novel epitaxial-like growth technique to achieve extremely uniform and large rectangular-shaped grains in thin-film ferroelectrics by dividing the nucleation and growth phases. With this technique, it is possible to achieve 100-μm large uniform grains, even made available on Si, which is large enough to fabricate a field-effect transistor in each grain. The electrical and reliability test results, including endurance and retention test results, were superior to other FeRAMs reported so far and thus the results presented here constitute the first step toward the development of FeRAM using epitaxial-like ferroelectric thin-films. PMID:27005886

Acorn production in red oak

Treesearch

Daniel C. Dey

1995-01-01

Manipulation of stand stocking through thinning can increase the amount of oak in the upper crown classes and enhance individual tree characteristics that promote good acorn production. Identification of good acorn producers before thinning or shelterwood harvests can be used to retain them in a stand. Stocking charts can be used to time thinnings and to estimate acorn...

Reduction of Defects on Microstructure Aluminium Nitride Using High Temperature Annealing Heat Treatment

NASA Astrophysics Data System (ADS)

Tanasta, Z.; Muhamad, P.; Kuwano, N.; Norfazrina, H. M. Y.; Unuh, M. H.

2018-03-01

Aluminium Nitride (AlN) is a ceramic 111-nitride material that is used widely as components in functional devices. Besides good thermal conductivity, it also has a high band gap in emitting light which is 6 eV. AlN thin film is grown on the sapphire substrate (0001). However, lattice mismatch between both materials has caused defects to exist along the microstructure of AlN thin films. The defects have affected the properties of Aluminium Nitride. Annealing heat treatment has been proved by the previous researcher to be the best method to improve the microstructure of Aluminium Nitride thin films. Hence, this method is applied at four different temperatures for two hour. The changes of Aluminium Nitride microstructures before and after annealing is observed using Transmission Electron Microscope. It is observed that inversion domains start to occur at temperature of 1500 °C. Convergent Beam Electron Diffraction pattern simulation has confirmed the defects as inversion domain. Therefore, this paper is about to extract the matters occurred during the process of producing high quality Aluminium Nitride thin films and the ways to overcome this problem.

Electronic Devices Based on Oxide Thin Films Fabricated by Fiber-to-Film Process.

PubMed

Meng, You; Liu, Ao; Guo, Zidong; Liu, Guoxia; Shin, Byoungchul; Noh, Yong-Young; Fortunato, Elvira; Martins, Rodrigo; Shan, Fukai

2018-05-30

Technical development for thin-film fabrication is essential for emerging metal-oxide (MO) electronics. Although impressive progress has been achieved in fabricating MO thin films, the challenges still remain. Here, we report a versatile and general thermal-induced nanomelting technique for fabricating MO thin films from the fiber networks, briefly called fiber-to-film (FTF) process. The high quality of the FTF-processed MO thin films was confirmed by various investigations. The FTF process is generally applicable to numerous technologically relevant MO thin films, including semiconducting thin films (e.g., In 2 O 3 , InZnO, and InZrZnO), conducting thin films (e.g., InSnO), and insulating thin films (e.g., AlO x ). By optimizing the fabrication process, In 2 O 3 /AlO x thin-film transistors (TFTs) were successfully integrated by fully FTF processes. High-performance TFT was achieved with an average mobility of ∼25 cm 2 /(Vs), an on/off current ratio of ∼10 7 , a threshold voltage of ∼1 V, and a device yield of 100%. As a proof of concept, one-transistor-driven pixel circuit was constructed, which exhibited high controllability over the light-emitting diodes. Logic gates based on fully FTF-processed In 2 O 3 /AlO x TFTs were further realized, which exhibited good dynamic logic responses and voltage amplification by a factor of ∼4. The FTF technique presented here offers great potential in large-area and low-cost manufacturing for flexible oxide electronics.

Rotator cuff tear measurement by arthropneumotomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilcoyne, R.F.; Matsen, F.A. III

1983-02-01

Five years of experience with a method of shoulder arthrography using upright tomography in cases of suspected or known rotator cuff tears has demonstrated its effectiveness. The value of the procedure lies in its ability to demonstrate the size of the cuff tear and the thickness of the remaining cuff tissue. This information provides the surgeon with a preoperative estimate of the difficulty of the repair and the prognosis for a good functional recovery. In 33 cases, there was good correlation between the upright thin-section tomogram findings and the surgical results. The tomograms provided better information about the size ofmore » the tear and the quality of the remaining cuff than did plain arthrograms.« less

Organic-Inorganic Hybrid Perovskite with Controlled Dopant Modification and Application in Photovoltaic Device.

PubMed

Zhao, Wangen; Yang, Dong; Liu, Shengzhong Frank

2017-07-01

Organic-inorganic hybrid perovskite as a kind of promising photovoltaic material is booming due to its low-cost, high defect tolerance, and easy fabrication, which result in the huge potential in industrial production. In the pursuit of high efficiency photovoltaic devices, high-quality absorbing layer is essential. Therefore, developing organic-inorganic hybrid perovskite thin films with good coverage, improved uniformity, and crystalline in a single pass deposition is of great concern in realizing good performance of perovskite thin-film solar cell. Here, it is found that the introduction of suitable amounts of LiI plays a dramatically positive role in enlarging the grain size and reducing the grain boundaries of absorbing layer. In addition, the carrier lifetime and built-in potential of the LiI doped perovskite device are observed to increase. Thus, it leads to about 15% gain in solar cell efficiency comparing to that without the LiI doping. Meanwhile, a hysteresis reduction is observed and 18.16% power conversion efficiency is achieved in LiI doped perovskite device, as well. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

GaAs droplet quantum dots with nanometer-thin capping layer for plasmonic applications.

PubMed

Park, Suk In; Trojak, Oliver Joe; Lee, Eunhye; Song, Jin Dong; Kyhm, Jihoon; Han, Ilki; Kim, Jongsu; Yi, Gyu-Chul; Sapienza, Luca

2018-05-18

We report on the growth and optical characterization of droplet GaAs quantum dots (QDs) with extremely-thin (11 nm) capping layers. To achieve such result, an internal thermal heating step is introduced during the growth and its role in the morphological properties of the QDs obtained is investigated via scanning electron and atomic force microscopy. Photoluminescence measurements at cryogenic temperatures show optically stable, sharp and bright emission from single QDs, at visible wavelengths. Given the quality of their optical properties and the proximity to the surface, such emitters are good candidates for the investigation of near field effects, like the coupling to plasmonic modes, in order to strongly control the directionality of the emission and/or the spontaneous emission rate, crucial parameters for quantum photonic applications.

GaAs droplet quantum dots with nanometer-thin capping layer for plasmonic applications

NASA Astrophysics Data System (ADS)

In Park, Suk; Trojak, Oliver Joe; Lee, Eunhye; Song, Jin Dong; Kyhm, Jihoon; Han, Ilki; Kim, Jongsu; Yi, Gyu-Chul; Sapienza, Luca

2018-05-01

We report on the growth and optical characterization of droplet GaAs quantum dots (QDs) with extremely-thin (11 nm) capping layers. To achieve such result, an internal thermal heating step is introduced during the growth and its role in the morphological properties of the QDs obtained is investigated via scanning electron and atomic force microscopy. Photoluminescence measurements at cryogenic temperatures show optically stable, sharp and bright emission from single QDs, at visible wavelengths. Given the quality of their optical properties and the proximity to the surface, such emitters are good candidates for the investigation of near field effects, like the coupling to plasmonic modes, in order to strongly control the directionality of the emission and/or the spontaneous emission rate, crucial parameters for quantum photonic applications.

Evaporated As2S3 Luneburg lenses for LiNbO3:Ti optical waveguides

NASA Technical Reports Server (NTRS)

Busch, J. R.; Wood, V. E.; Kenan, R. P.; Verber, C. M.

1981-01-01

Luneburg lenses of good quality were formed on high index optical waveguides by evaporation of arsenic trisulfide glass through simple masks. Using only two thin circular aperture masks, lenses with focal spots of a few times the diffraction limited width at f/4 were obtained. These lenses were designed for and tested at both visible (633 nm) and infrared wavelengths. Procedures for the design, fabrication, and testing of lenses of this type are described.

III-V Compounds and Alloys: An Update.

PubMed

Woodall, J M

1980-05-23

The III-V compounds and alloys have been studied for three decades. Until recently, these materials have been commercialized for only a few specialized optoelectronic devices and microwave devices. Advances in thin-film epitaxy techniques, such as liquid phase epitaxy and chemical vapor deposition, are now providing the ability to form good quality lattice-matched heterojunctions with III-V materials. New optoelectronic devices, such as room-temperature continuous-wave injection lasers, have already resulted. This newfound ability may also affect the field of highspeed integrated circuits.

Improved removal of blood contamination from ThinPrep cervical cytology samples for Raman spectroscopic analysis.

PubMed

Traynor, Damien; Duraipandian, Shiyamala; Martin, Cara M; O'Leary, John J; Lyng, Fiona M

2018-05-01

There is an unmet need for methods to help in the early detection of cervical precancer. Optical spectroscopy-based techniques, such as Raman spectroscopy, have shown great potential for diagnosis of different cancers, including cervical cancer. However, relatively few studies have been carried out on liquid-based cytology (LBC) pap test specimens and confounding factors, such as blood contamination, have been identified. Previous work reported a method to remove blood contamination before Raman spectroscopy by pretreatment of the slides with hydrogen peroxide. The aim of the present study was to extend this work to excessively bloody samples to see if these could be rendered suitable for Raman spectroscopy. LBC ThinPrep specimens were treated by adding hydrogen peroxide directly to the vial before slide preparation. Good quality Raman spectra were recorded from negative and high grade (HG) cytology samples with no blood contamination and with heavy blood contamination. Good classification between negative and HG cytology could be achieved for samples with no blood contamination (sensitivity 92%, specificity 93%) and heavy blood contamination (sensitivity 89%, specificity 88%) with poorer classification when samples were combined (sensitivity 82%, specificity 87%). This study demonstrates for the first time the improved potential of Raman spectroscopy for analysis of ThinPrep specimens regardless of blood contamination. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Crystallization of Electrodeposited Germanium Thin Film on Silicon (100).

PubMed

Abidin, Mastura Shafinaz Zainal; Matsumura, Ryo; Anisuzzaman, Mohammad; Park, Jong-Hyeok; Muta, Shunpei; Mahmood, Mohamad Rusop; Sadoh, Taizoh; Hashim, Abdul Manaf

2013-11-06

We report the crystallization of electrodeposited germanium (Ge) thin films on n-silicon (Si) (100) by rapid melting process. The electrodeposition was carried out in germanium (IV) chloride: propylene glycol (GeCl₄:C₃H₈O₂) electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD) images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA) at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm -1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm -1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES) reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.

Stand quality management in a late-rotation, red oak-sweetgum stand in east Mississippi: preliminary results following thinning

Treesearch

James S. Meadows; Daniel A. Skojac

2012-01-01

Stand quality management is a new management strategy in which thinning prescriptions are based solely on tree quality rather than a quantitative level of residual stand density. As long as residual density falls within fairly broad limits, prescriptions are based on tree quality alone. We applied four thinning prescriptions based on stand quality management, along...

Acquisition of thin coronal sectional dataset of cadaveric liver.

PubMed

Lou, Li; Liu, Shu Wei; Zhao, Zhen Mei; Tang, Yu Chun; Lin, Xiang Tao

2014-04-01

To obtain the thin coronal sectional anatomic dataset of the liver by using digital freezing milling technique. The upper abdomen of one Chinese adult cadaver was selected as the specimen. After CT and MRI examinations verification of absent liver lesions, the specimen was embedded with gelatin in stand erect position and frozen under profound hypothermia, and the specimen was then serially sectioned from anterior to posterior layer by layer with digital milling machine in the freezing chamber. The sequential images were captured by means of a digital camera and the dataset was imported to imaging workstation. The thin serial section of the liver added up to 699 layers with each layer being 0.2 mm in thickness. The shape, location, structure, intrahepatic vessels and adjacent structures of the liver was displayed clearly on each layer of the coronal sectional slice. CT and MR images through the body were obtained at 1.0 and 3.0 mm intervals, respectively. The methodology reported here is an adaptation of the milling methods previously described, which is a new data acquisition method for sectional anatomy. The thin coronal sectional anatomic dataset of the liver obtained by this technique is of high precision and good quality.

Quality control and in vitro antioxidant potential of Coriandrum sativum Linn.

PubMed Central

Singh, Mhaveer; Tamboli, E. T.; Kamal, Y. T.; Ahmad, Wasim; Ansari, S. H.; Ahmad, Sayeed

2015-01-01

Background: Coriandrum sativum Linn., commonly known as coriander, is a well-known spice and drug in India. It has various health-related benefits and used in various Unani formulations. In this present study, quality assessment of coriander fruits was carried out by studying anatomical characters, physicochemical tests, and chemoprofiling using high performance thin layer chromatography (HPTLC) and gas chromatography-mass spectroscopy (GC-MS) along with in vitro antioxidant potential. Materials and Methods: Standardization was carried out as per the pharmacopeial guidelines. Estimation of heavy metals, pesticides, and aflatoxins was carried out to ascertain the presence of any contaminant in the sample. Chemoprofiling was achieved by thin layer chromatography (TLC) by optimizing the mobile phase for different extracts. The most of the pharmacological activities of coriander are based on volatile oil constituents. Hence, GC-MS profiling was also carried out using hexane-soluble fraction of hydro-alcoholic extract. The total phenolic contents and in vitro antioxidant efficacy were determined using previously established methods. Results: The quality control and anatomical studies were very valuable for the identification whereas good antioxidant potential was observed when compared to ascorbic acid. The drug was found free of contaminant when analyzed for pesticides and aflatoxins whereas heavy metals were found under reported limits. Conclusion: The work embodied in this present research can be utilized for the identification and the quality control of the coriander fruit. PMID:26681883

Insight into the epitaxial encapsulation of Pd catalysts in an oriented metalloporphyrin network thin film for tandem catalysis.

PubMed

Vohra, M Ismail; Li, De-Jing; Gu, Zhi-Gang; Zhang, Jian

2017-06-14

A palladium catalyst (Pd-Cs) encapsulated metalloporphyrin network PIZA-1 thin film with bifunctional properties has been developed through a modified epitaxial layer-by-layer encapsulation approach. Combining the oxidation activity of Pd-Cs and the acetalization activity of the Lewis acidic sites in the PIZA-1 thin film, this bifunctional catalyst of the Pd-Cs@PIZA-1 thin film exhibits a good catalytic activity in a one-pot tandem oxidation-acetalization reaction. Furthermore, the surface components can be controlled by ending the top layer with different precursors in the thin film preparation procedures. The catalytic performances of these thin films with different surface composites were studied under the same conditions, which showed different reaction conversions. The result revealed that the surface component can influence the catalytic performance of the thin films. This epitaxial encapsulation offers a good understanding of the tandem catalysis for thin film materials and provides useful guidance to develop new thin film materials with catalytic properties.

Debris-free rear-side picosecond laser ablation of thin germanium wafers in water with ethanol

NASA Astrophysics Data System (ADS)

Zhang, Dongshi; Gökce, Bilal; Sommer, Steffen; Streubel, René; Barcikowski, Stephan

2016-03-01

In this paper, we perform liquid-assisted picosecond laser cutting of 150 μm thin germanium wafers from the rear side. By investigating the cutting efficiency (the ability to allow an one-line cut-through) and quality (characterized by groove morphologies on both sides), the pros and cons of this technique under different conditions are clarified. Specifically, with laser fluence fixed, repetition rate and scanning speed are varied to show quality and efficiency control by means of laser parameter modulation. It is found that low repetition rate ablation in liquid gives rise to a better cut quality on the front side than high repetition rate ablation since it avoids dispersed nanoparticles redeposition resulting from a bubble collapse, unlike the case of 100 kHz which leads to large nanorings near the grooves resulting from a strong interaction of bubbles and the case of 50 kHz which leads to random cutting due to the interaction of the former pulse induced cavitation bubble and the subsequent laser pulse. Furthermore, ethanol is mixed with pure distilled water to assess the liquid's impact on the cutting efficiency and cutting quality. The results show that increasing the ethanol fraction decreases the ablation efficiency but simultaneously, greatly improves the cutting quality. The improvement of cut quality as ethanol ratio increases may be attributed to less laser beam interference by a lower density of bubbles which adhere near the cut kerf during ablation. A higher density of bubbles generated from ethanol vaporization during laser ablation in liquid will cause stronger bubble shielding effect toward the laser beam propagation and therefore result in less laser energy available for the cut, which is the main reason for the decrease of cut efficiency in water-ethanol mixtures. Our findings give an insight into under which condition the rear-side laser cutting of thin solar cells should be performed: high repetition, pure distilled water and high laser power are favorable for high-speed rough cutting but the cut kerf suffers from strong side effects of ripples, nanoredeposition occurrence, while low laser power at low repetition rate (10 kHz), mixed solution (1 wt% ethanol in water) and moderate scanning speed (100 μm/s) are preferable for ultrafine high-quality debris-free cutting. The feasibility of high-quality cut is a good indication of using rear laser ablation in liquid to cut thinner wafers. More importantly, this technique spares any post cleaning steps to reduce the risk to the contamination or crack of the thin wafers.

Effect of Hydrogen in Zinc Oxide Thin-Film Transistor Grown by Metal Organic Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Jo, Jungyol; Seo, Ogweon; Jeong, Euihyuk; Seo, Hyunseok; Lee, Byeongon; Choi, Yearn-Ik

2007-04-01

We studied the transport characteristics of ZnO grown by metal organic chemical vapor deposition (MOCVD) at temperatures between 200 and 500 °C. The crystal quality, measured by X-ray diffraction, improved as the growth temperature increased. However, the mobility measured in the thin-film transistor (TFT) decreased in films grown at higher temperatures. In our experiments, a ZnO TFT grown at 250 °C showed good electrical characteristics, with a 13 cm2 V-1 s-1 mobility and a 103 on/off ratio. We conclude that hydrogen incorporated during MOCVD growth plays an important role in determining the transistor characteristics. This was supported by results of secondary ion mass spectroscopy (SIMS), where a higher hydrogen concentration was observed in films grown at lower temperatures.

Optical and sensing properties of sol-gel derived vanadium pentoxide thin films with porous and dense structures

NASA Astrophysics Data System (ADS)

Babeva, T.; Awala, H.; Grand, J.; Lazarova, K.; Vasileva, M.; Mintova, S.

2018-03-01

The sol-gel and spin-coating methods were used for deposition of thin transparent V2O5 films on optical glass substrates and silicon wafers. Different synthesis and deposition conditions, including synthesis temperatures and post-deposition annealing, were used aiming at obtaining transparent films with high refractive index and good optical quality. The surface morphology and structure of the films were studied by SEM and XRD. The optical properties (refractive index, extinction coefficient and optical band gap) and thickness of the V2O5 films were determined from their transmittance and reflectance spectra. The potential application of the films as building blocks of optical sensors was demonstrated by preparation of multilayered structures comprising both V2O5 and BEA-type zeolite films and testing their response towards acetone vapors.

Polycrystalline Superconducting Thin Films: Texture Control and Critical Current Density

NASA Astrophysics Data System (ADS)

Yang, Feng

1995-01-01

The growth processes of polycrystalline rm YBa_2CU_3O_{7-X} (YBCO) and yttria-stabilized-zirconia (YSZ) thin films have been developed. The effectiveness of YSZ buffer layers on suppression of the reaction between YBCO thin films and metallic substrates was carefully studied. Grown on the chemically inert surfaces of YSZ buffer layers, YBCO thin films possessed good quality of c-axis alignment with the c axis parallel to the substrate normal, but without any preferred in-plane orientations. This leads to the existence of a large percentage of the high-angle grain boundaries in the YBCO films. The critical current densities (rm J_{c}'s) found in these films were much lower than those in single crystal YBCO thin films, which was the consequence of the weak -link effect of the high-angle grain boundaries in these films. It became clear that the in-plane alignment is vital for achieving high rm J_{c }s in polycrystalline YBCO thin films. To induce the in-plane alignment, ion beam-assisted deposition (IBAD) technique was integrated into the conventional pulsed laser deposition process for the growth of the YSZ buffer layers. It was demonstrated that using IBAD the in-plane orientations of the YSZ grains could be controlled within a certain range of a common direction. This ion -bombardment induced in-plane texturing was explained using the anisotropic sputtering yield theory. Our observations and analyses have provided valuable information on the optimization of the IBAD process, and shed light on the texturing mechanism in YSZ. With the in-plane aligned YSZ buffer layers, YBCO thin films grown on metallic substrates showed improved rm J_{c}s. It was found that the in-plane alignment of YSZ and that of YBCO were closely related. A direct correlation was revealed between the rm J_{c} value and the degree of the in-plane alignment for the YBCO thin films. To explain this correlation, a numerical model was applied to multi-grain superconducting paths with different textures to determine the expected rm J_{c}s. The good agreement between the experimental data and numerical results confirmed that the rm J_{c} improvement directly resulted from the reduction of the number of high-angle grain boundaries in the in-plane aligned polycrystalline YBCO thin films, and provided a guideline on the further improvement of the rm J_ {c}s of polycrystalline YBCO thin films.

Effect of Pr3+doping on key properties of CdO thin films deposited by spray pyrolysis using perfume atomizer

NASA Astrophysics Data System (ADS)

Ravikumar, M.; Chandramohan, R.; Kumar, K. Deva Arun; Valanarasu, S.; Kathalingam, A.; Ganesh, V.; Shkir, Mohd.; AlFaify, S.; Algarni, H.

2018-07-01

High quality Cadmium oxide thin films doped with Praseodymium (Pr) were prepared using perfume atomizer based spray pyrolysis technique at substrate temperature near 350 °C. Structural analysis of films was examined by XRD and confirmed that the films are cubic in structure. All un-doped and doped films were good crystalline in nature with smooth and flat surface without significant modifications owed to doping. Optical transmittances of doped films was decrease in the visible and IR range with increasing Pr doping concentration. Band gap widened from 2.42 to 2.20 eV when doped with Pr from 0 to 5 at. %. In addition, the photoluminescence property of the films was also observed. Further, the electrical studies were performed on pure and doped samples Viz., the electrical resistivity, carrier concentration (ρ) and Hall mobility (μ). It confirmed that the deposited films has good structural environments in terms of grain size, absolute stress correspond and low resistivity. Current-voltage measurements on the nanostructured Al/Pr-nCdO/p-Si/Al device showed a non-linear electric characteristics indicating diode like behavior.

Study of the photovoltaic effect in thin film barium titanate

NASA Technical Reports Server (NTRS)

Grannemann, W. W.; Dharmadhikari, V. S.

1981-01-01

The photoelectric effect in structures consisting of metal deposited barium titanate film silicon is described. A radio frequency sputtering technique is used to deposit ferroelectric barium titantate films on silicon and quartz. Film properties are measured and correlated with the photoelectric effect characteristics of the films. It was found that to obtain good quality pin hole free films, it is necessary to reduce the substrate temperature during the last part of the deposition. The switching ability of the device with internal applied voltage is improved when applied with a ferroelectric memory device.

DOE Office of Scientific and Technical Information (OSTI.GOV)

He Liang; Xiu Faxian; Huang Guan

In this paper, we report the epitaxial growth of Bi{sub 2}Se{sub 3} thin films on Si (111) substrate, using molecular beam epitaxy (MBE). We show that the as-grown samples have good crystalline quality, and their surfaces exhibit terracelike quintuple layers. Angel-resolved photoemission experiments demonstrate single-Dirac-conelike surface states. These results combined with the temperature- and thickness-dependent magneto-transport measurements, suggest the presence of a shallow impurity band. Below a critical temperature of {approx}100K, the surface states of a 7 nm thick film contribute up to 50% of the total conduction.

Physics and chemistry in the process of hot-wire deposition of thin film silicon

NASA Astrophysics Data System (ADS)

Zheng, Wengang

Hotwire Chemical Vapor Deposition (CVD) has been used in preparing high quality low hydrogen content hydrogenated amorphous or polycrystalline silicon thin film in recent years. Comparing to the most commonly used glow discharge method, Hotwire CVD has the potential of high speed deposition avoiding the damage caused by ion bombardment associated with plasma. Although device quality thin films have been prepared by this method, and some empirical optimized deposition conditions have been established, the mechanisms controlling this technique are not clear. A homebuild threshold ionization mass spectrometer was constructed in this lab, allowing the radicals to be observed with high sensitivity. Hydrogen dissociation on the hot metal surface was studied first both by the direct detection of hydrogen atoms from the hot surface and the temperature change due to the hydrogen dissociation, it was confirmed that the activation energy of this process is around 2.25eV, the same as the dissociation in the gas phase. Further, we observed a first order dependence of hydrogen dissociation probability on the hydrogen pressure. This observation contradicts previously reported models of second order desorption. The monosilicon radicals Si and SiH3 were observed. It was observed that the silane decomposition on the hot surface is mainly a function of filament temperature, but the species released from that surface also depend on the surface condition, and thus on the silane exposure history of that piece of filament. Si is believed to deteriorate the film quality, by comparing the depleted silane and the Si flux, it is observed that Si experienced a lot of gas phase reactions before reaching the substrate, which leads to less reactive precursors. This observation is consistence with Molenbroek's study on the optimization of deposition condition. The dominant disilicon radical is identified as Si2H2, which in the form of lowest energy isomer, is suppose to be much less reactive than Si, and thus contributes to good quality thin film deposition. The corresponding Si insert reaction Si + SiH4 was also studied and an effective reaction coefficient of KSeff = 5 x 10-12( cm3/s was established.

Chemical bath deposition of II-VI compound thin films

NASA Astrophysics Data System (ADS)

Oladeji, Isaiah Olatunde

II-VI compounds are direct bandgap semiconductors with great potentials in optoelectronic applications. Solar cells, where these materials are in greater demand, require a low cost production technology that will make the final product more affordable. Chemical bath deposition (CBD) a low cost growth technique capable of producing good quality thin film semiconductors over large area and at low temperature then becomes a suitable technology of choice. Heterogeneous reaction in a basic aqueous solution that is responsible for the II-VI compound film growth in CBD requires a metal complex. We have identified the stability constant (k) of the metal complex compatible with CBD growth mechanism to be about 106.9. This value is low enough to ensure that the substrate adsorbed complex relax for subsequent reaction with the chalcogen precursor to take place. It is also high enough to minimize the metal ion concentration in the bath participating in the precipitation of the bulk compounds. Homogeneous reaction that leads to precipitation in the reaction bath takes place because the solubility products of bulk II-VI compounds are very low. This reaction quickly depletes the bath of reactants, limit the film thickness, and degrade the film quality. While ZnS thin films are still hard to grow by CBD because of lack of suitable complexing agent, the homogeneous reaction still limits quality and thickness of both US and ZnS thin films. In this study, the zinc tetraammine complex ([Zn(NH3) 4]2+) with k = 108.9 has been forced to acquire its unsaturated form [Zn(NH3)3]2+ with a moderate k = 106.6 using hydrazine and nitrilotriacetate ion as complementary complexing agents and we have successfully grown ZnS thin films. We have also, minimized or eliminated the homogeneous reaction by using ammonium salt as a buffer and chemical bath with low reactant concentrations. These have allowed us to increase the saturation thickness of ZnS thin film by about 400% and raise that of US film form 0.2 to 0.5 mum with improved quality. A novel chemical activated diffusion of Cd into ZnS thin film at temperature lower than 100°C is also developed. This in conjunction with thermal activated diffusion at 400°C has enabled us to synthesize Cd1-xZn xS thin films suitable for solar cells from CBD grown CdS/ZnS multilayer. The potential application of the new Cd1-xZnxS/CdS/CdTe solar cell structure is also demonstrated. The unoptimized structure grown on transparent conducting oxide coated soda lime glass of 3mm thickness with no antireflection coating yielded a 10% efficiency. This efficiency is the highest ever recorded in any Cd1-xZnxS film containing CdTe solar cells.

Atomic Layer-Deposited Titanium-Doped Vanadium Oxide Thin Films and Their Thermistor Applications

DOE PAGES

Wang, Shuyu; Yu, Shifeng; Lu, Ming; ...

2016-11-30

In this paper, we report the enhancement in the temperature coefficient of resistance (TCR) of atomic layer-deposited vanadium oxide thin films through the doping of titanium oxide. The Hall effect measurement provides a potential explanation for the phenomenon. The composition and morphology of the thin films are investigated by x-ray diffraction and scanning electron microscopy techniques. The high TCR, good uniformity, and low processing temperature of the material make it a good candidate for thermistor application.

Multilayer SnSb4-SbSe Thin Films for Phase Change Materials Possessing Ultrafast Phase Change Speed and Enhanced Stability.

PubMed

Liu, Ruirui; Zhou, Xiao; Zhai, Jiwei; Song, Jun; Wu, Pengzhi; Lai, Tianshu; Song, Sannian; Song, Zhitang

2017-08-16

A multilayer thin film, comprising two different phase change material (PCM) components alternatively deposited, provides an effective means to tune and leverage good properties of its components, promising a new route toward high-performance PCMs. The present study systematically investigated the SnSb 4 -SbSe multilayer thin film as a potential PCM, combining experiments and first-principles calculations, and demonstrated that these multilayer thin films exhibit good electrical resistivity, robust thermal stability, and superior phase change speed. In particular, the potential operating temperature for 10 years is shown to be 122.0 °C and the phase change speed reaches 5 ns in the device test. The good thermal stability of the multilayer thin film is shown to come from the formation of the Sb 2 Se 3 phase, whereas the fast phase change speed can be attributed to the formation of vacancies and a SbSe metastable phase. It is also demonstrated that the SbSe metastable phase contributes to further enhancing the electrical resistivity of the crystalline state and the thermal stability of the amorphous state, being vital to determining the properties of the multilayer SnSb 4 -SbSe thin film.

Effect of two different treatments for reducing grape yield in Vitis vinifera cv Syrah on wine composition and quality: berry thinning versus cluster thinning.

PubMed

Gil, M; Esteruelas, M; González, E; Kontoudakis, N; Jiménez, J; Fort, F; Canals, J M; Hermosín-Gutiérrez, I; Zamora, F

2013-05-22

The influence of two treatments for reducing grape yield, cluster thinning and berry thinning, on red wine composition and quality were studied in a Vitis vinifera cv Syrah vineyard in AOC Penedès (Spain). Cluster thinning reduced grape yield per vine by around 40% whereas berry thinning only reduced it by around 20%. Cluster thinning grapes had higher soluble solids content than control grapes, and their resultant wines have greater anthocyanin and polysaccharide concentrations than the control wine. Wine obtained from berry thinning grapes had a higher total phenolic index, greater flavonol, proanthocyanidin, and polysaccharide concentrations, and lower titratable acidity than the control wine. Wines obtained from both treatments were sufficiently different from the control wine to be significantly distinguished by a trained panel in a triangular test. Even though both treatments seem to be effective at improving the quality of wine, berry thinning has the advantage because it has less impact on crop yield reduction.

Effect of polyvinyl alcohol on electrochemically deposited ZnO thin films for DSSC applications

NASA Astrophysics Data System (ADS)

Marimuthu, T.; Anandhan, N.

2017-05-01

Nanostructures of zinc oxide (ZnO) thin film are electrochemically deposited in the absence and presence of polyvinyl alcohol (PVA) on fluorine doped tin oxide (FTO) substrate. X-ray diffraction (XRD) patterns and Raman spectroscopy confirmed the formation of hexagonal structure of ZnO. The film prepared in the presence of PVA showed a better crystallinity and its crystalline growth along the (002) plane orientation. Field emission scanning electron microscope (FE-SEM) images display nanowire arrays (NWAs) and sponge like morphology for films prepared in the absence and presence of PVA, respectively. Photoluminescence (PL) spectra depict the film prepared in the presence PVA having less atomic defects with good crystal quality compared with other film. Dye sensitized solar cell (DSSC) is constructed using low cost eosin yellow dye and current-voltage (J-V) curve is recorded for optimized sponge like morphology based solar cell.

Preparation of Langmuir-Blodgett thin films of calix[6]arenes and p-tert butyl group effect on their gas sensing properties

NASA Astrophysics Data System (ADS)

Ozmen, Mustafa; Ozbek, Zikriye; Bayrakci, Mevlut; Ertul, Seref; Ersoz, Mustafa; Capan, Rifat

2015-12-01

Organic vapor sensing properties of Langmuir-Blodgett (LB) thin films of p-tert-butyl calix[6]arene and calix[6]arene, and their certain characterization are reported in this work. LB films of these calixarenes have been characterized by contact angle measurement, quartz crystal microbalance (QCM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). QCM system was used for the measurement of sensor response against chloroform, benzene, toluene and ethanol vapors. Forming of stable monolayers was observed at the water surface using surface pressure-area isotherm graph. The results indicate that good quality, uniform LB films can be prepared with a transfer ratio of over 0.95. Due to the adsorption of vapors into the LB film structures; they yield a response to all vapors as of large, fast, and reproducible.

Titanium nitride as a seed layer for Heusler compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niesen, Alessia, E-mail: aniesen@physik.uni-bielefeld.de; Glas, Manuel; Ludwig, Jana

Titanium nitride (TiN) shows low resistivity at room temperature (27 μΩ cm), high thermal stability and thus has the potential to serve as seed layer in magnetic tunnel junctions. High quality TiN thin films with regard to the crystallographic and electrical properties were grown and characterized by x-ray diffraction and 4-terminal transport measurements. Element specific x-ray absorption spectroscopy revealed pure TiN inside the thin films. To investigate the influence of a TiN seed layer on a ferro(i)magnetic bottom electrode in magnetic tunnel junctions, an out-of-plane magnetized Mn{sub 2.45}Ga as well as in- and out-of-plane magnetized Co{sub 2}FeAl thin films were depositedmore » on a TiN buffer, respectively. The magnetic properties were investigated using a superconducting quantum interference device and anomalous Hall effect for Mn{sub 2.45}Ga. Magneto optical Kerr effect measurements were carried out to investigate the magnetic properties of Co{sub 2}FeAl. TiN buffered Mn{sub 2.45}Ga thin films showed higher coercivity and squareness ratio compared to unbuffered samples. The Heusler compound Co{sub 2}FeAl showed already good crystallinity when grown at room temperature on a TiN seed-layer.« less

Electrical properties of thin film transistors with zinc tin oxide channel layer

NASA Astrophysics Data System (ADS)

Hong, Seunghwan; Oh, Gyujin; Kim, Eun Kyu

2017-10-01

We have investigated thin film transistors (TFTs) with zinc tin oxide (ZTO) channel layer fabricated by using an ultra-high vacuum radio frequency sputter. ZTO thin films were grown at room temperature by co-sputtering of ZnO and SnO2, which applied power for SnO2 target was varied from 15 W to 90 W under a fixed sputtering power of 70 W for ZnO target. A post-annealing treatment to improve the film quality was done at temperature ranges from 300 to 600 °C by using the electrical furnace. The ZTO thin films showed good electrical and optical properties such as Hall mobility of more than 9 cm2/V·s, specific resistivity of about 2 × 102 Ω·cm, and optical transmittance of 85% in visible light region by optical bandgap of 3.3 eV. The ZTO-TFT with an excellent performance of channel mobility of 19.1 cm2/V·s and on-off ratio ( I on / I off ) of 104 was obtained from the films grown with SnO2 target power of 25 W and post-annealed at 450 °C. This result showed that ZTO film is promising on application to a high performance transparent TFTs.

Development and manufacture of reactive-transfer-printed CIGS photovoltaic modules

NASA Astrophysics Data System (ADS)

Eldada, Louay; Sang, Baosheng; Lu, Dingyuan; Stanbery, Billy J.

2010-09-01

In recent years, thin-film photovoltaic (PV) companies started realizing their low manufacturing cost potential, and grabbing an increasingly larger market share from multicrystalline silicon companies. Copper Indium Gallium Selenide (CIGS) is the most promising thin-film PV material, having demonstrated the highest energy conversion efficiency in both cells and modules. However, most CIGS manufacturers still face the challenge of delivering a reliable and rapid manufacturing process that can scale effectively and deliver on the promise of this material system. HelioVolt has developed a reactive transfer process for CIGS absorber formation that has the benefits of good compositional control, high-quality CIGS grains, and a fast reaction. The reactive transfer process is a two stage CIGS fabrication method. Precursor films are deposited onto substrates and reusable print plates in the first stage, while in the second stage, the CIGS layer is formed by rapid heating with Se confinement. High quality CIGS films with large grains were produced on a full-scale manufacturing line, and resulted in high-efficiency large-form-factor modules. With 14% cell efficiency and 12% module efficiency, HelioVolt started to commercialize the process on its first production line with 20 MW nameplate capacity.

Tunability of p- and n-channel TiOx thin film transistors.

PubMed

Peng, Wu-Chang; Chen, Yao-Ching; He, Ju-Liang; Ou, Sin-Liang; Horng, Ray-Hua; Wuu, Dong-Sing

2018-06-18

To acquire device-quality TiO x films usually needs high-temperature growth or additional post-thermal treatment. However, both processes make it very difficult to form the p-type TiO x even under oxygen-poor growth condition. With the aid of high energy generated by high power impulse magnetron sputtering (HIPIMS), a highly stable p-type TiO x film with good quality can be achieved. In this research, by varying the oxygen flow rate, p-type γ-TiO and n-type TiO 2 films were both prepared by HIPIMS. Furthermore, p- and n-type thin film transistors employing γ-TiO and TiO 2 as channel layers possess the field-effect carrier mobilities of 0.2 and 0.7 cm 2 /Vs, while their on/off current ratios are 1.7 × 10 4 and 2.5 × 10 5 , respectively. The first presented p-type γ-TiO TFT is a major breakthrough for fabricating the TiO x -based p-n combinational devices. Additionally, our work also confirms HIPIMS offers the possibility of growing both p- and n-type conductive oxides, significantly expanding the practical usage of this technique.

Fabrication of interdigitated high-performance zinc oxide nanowire modified electrodes for glucose sensing.

PubMed

Haarindraprasad, R; Hashim, Uda; Gopinath, Subash C B; Perumal, Veeradasan; Liu, Wei-Wen; Balakrishnan, S R

2016-06-21

Diabetes is a metabolic disease with a prolonged elevated level of glucose in the blood leads to long-term complications and increases the chances for cardiovascular diseases. The present study describes the fabrication of a ZnO nanowire (NW)-modified interdigitated electrode (IDE) to monitor the level of blood glucose. A silver IDE was generated by wet etching-assisted conventional lithography, with a gap between adjacent electrodes of 98.80 μm. The ZnO-based thin films and NWs were amended by sol-gel and hydrothermal routes. High-quality crystalline and c-axis orientated ZnO thin films were observed by XRD analyses. The ZnO thin film was annealed for 1, 3 and 5 h, yielding a good-quality crystallite with sizes of 50, 100 and 110 nm, and the band gaps were measured as 3.26, 3.20 and 3.17 eV, respectively. Furthermore, a flower-modeled NW was obtained with the lowest diameter of 21 nm. Our designed ZnO NW-modified IDE was shown to have a detection limit as low as 0.03 mg/dL (correlation coefficient = 0.98952) of glucose with a low response time of 3 s, perform better than commercial glucose meter, suitable to instantly monitor the glucose level of diabetes patients. This study demonstrated the high performance of NW-mediated IDEs for glucose sensing as alternative to current glucose sensors. Copyright © 2016 Elsevier B.V. All rights reserved.

High quality superconducting titanium nitride thin film growth using infrared pulsed laser deposition

NASA Astrophysics Data System (ADS)

Torgovkin, A.; Chaudhuri, S.; Ruhtinas, A.; Lahtinen, M.; Sajavaara, T.; Maasilta, I. J.

2018-05-01

Superconducting titanium nitride (TiN) thin films were deposited on magnesium oxide, sapphire and silicon nitride substrates at 700 °C, using a pulsed laser deposition (PLD) technique, where infrared (1064 nm) pulses from a solid-state laser were used for the ablation from a titanium target in a nitrogen atmosphere. Structural studies performed with x-ray diffraction showed the best epitaxial crystallinity for films deposited on MgO. In the best films, superconducting transition temperatures, T C, as high as 4.8 K were observed, higher than in most previous superconducting TiN thin films deposited with reactive sputtering. A room temperature resistivity down to ∼17 μΩ cm and residual resistivity ratio up to 3 were observed in the best films, approaching reported single crystal film values, demonstrating that PLD is a good alternative to reactive sputtering for superconducting TiN film deposition. For less than ideal samples, the suppression of the film properties were correlated mostly with the unintended incorporation of oxygen (5–10 at%) in the film, and for high oxygen content films, vacuum annealing was also shown to increase the T C. On the other hand, superconducting properties were surprisingly insensitive to the nitrogen content, with high quality films achieved even in the highly nitrogen rich, Ti:N = 40/60 limit. Measures to limit oxygen exposure during deposition must be taken to guarantee the best superconducting film properties, a fact that needs to be taken into account with other deposition methods, as well.

[Herbal textual research on relationship between Chinese medicine"Shihu" (Dendrobium spp.) and "Tiepi Shihu" (D. catenatum)].

PubMed

Si, Jin-Ping; Zhang, Yuan; Luo, Yi-Bo; Liu, Jing-Jing; Liu, Zhong-Jian

2017-05-01

Dendrobium species on the ancient Chinese herbal texts were investigated in this paper, including their dscriptions of original species, producing areas and quality. Our results indicated that the major producing areas were Lu'an, Anhui province and Wenzhou, Taizhou, Zhejiang province. In addition, the sweet flavor, short, thin and solid stems were standing for good quality. Based on the stable producing areas and quality descriptions, D. catenatum (D. officinale) ("Tiepi Shihu") and D. houshanense were high quality medicinal Dendrobium species ("Shihu" ) in ancient China. Besides, there were 3 scientific names for "Tiepi Shihu", including D. candidum, D. officinale, D. catenatum. After textual investigation, We suggest that D. catenatum should be its scientific name, and D. officinale was synonyms published later. However, the name "D. officinale" could be reserved as it is much more popular used in publication and commodities. Moreover, its Chinese name should be "Tiepi Shihu". Copyright© by the Chinese Pharmaceutical Association.

Effect of thinning on growth and potential quality of young white oak crop trees

Treesearch

Martin E. Dale; David L. Sonderman

1984-01-01

Relative change in several types of stem defects were studied over a 16-year period to determine the effect of thinning intensity on the development of tree quality. We studied quality changes on sample white oak crop trees that were selected from five density levels created in a 1961 thinning. Branch-related and other stem defects on the butt 16-foot section were...

An Aquifer Thermal Energy Storage (ATES) System for Continuous and Sustainable Cold Supply in Oman

NASA Astrophysics Data System (ADS)

Winterleitner, G.; Schütz, F.; Huenges, E.

2016-12-01

The aim of the GeoSolCool research programme between the German Research Centre for Geoscience (GFZ) and The Research Council of Oman (TRC) is the development of an innovative and sustainable cooling system in combination with an aquifer thermal energy storage system in northern Oman. An integral part of this project is the design of a subsurface aquifer reservoir system for storage of thermal energy through hot water injection. An accurate characterisation of potential storage horizons is thus essential to ensure optimal efficiency of the cooling system. The study area, 40 km west of Muscat is characterised by a thick Cenozoic mixed carbonate-siliciclastic sedimentary succession, containing at least 3 aquifer horizons. We used a multidisciplinary approach for the initial ATES development phase, including geological fieldwork dovetailed with remote sensing analyses, thin-section analyses, geological modelling and reservoir fluid flow forecasting. First results indicate two potential storage horizons: (1) a Miocene-aged clastic-dominated alluvial fan system and (2) an Eocene carbonate sequence. The alluvial fan system is a more than 300 m thick, coarse clastic (mainly gravels and sandstones) succession of coalesced individual fans. Thin-section analyses showed that hydraulic parameters are favourable for the gravel and sandstone intervals but reservoir architecture is complex due to multiple generations of interconnecting fans with highly heterogeneous facies distributions. The Eocene carbonates were deposited in a carbonate ramp setting, strongly influenced by currents and storm events. Individual facies belts extend over kilometres and thus horizontal reservoir connectivity is expected to be good with minor facies variability. Thin-section analyses showed that especially the fossil-rich sections show good storage qualities. Fluid flow forecasting indicate that both potential horizons have good to very good storage characteristics. However, intense diagenetic overprint of the succession and a complex reservoir architecture of the Miocene clastics might pose challenges for the ATES implementation. In order to decide which storage horizon will be developed as an ATES system, drilling of an exploration well and subsequent well-logging and hydraulic testing is underway.

PV cells electrical parameters measurement

NASA Astrophysics Data System (ADS)

Cibira, Gabriel

2017-12-01

When measuring optical parameters of a photovoltaic silicon cell, precise results bring good electrical parameters estimation, applying well-known physical-mathematical models. Nevertheless, considerable re-combination phenomena might occur in both surface and intrinsic thin layers within novel materials. Moreover, rear contact surface parameters may influence close-area re-combination phenomena, too. Therefore, the only precise electrical measurement approach is to prove assumed cell electrical parameters. Based on theoretical approach with respect to experiments, this paper analyses problems within measurement procedures and equipment used for electrical parameters acquisition within a photovoltaic silicon cell, as a case study. Statistical appraisal quality is contributed.

Development and application of free pretreatment container steel

NASA Astrophysics Data System (ADS)

Yang, Y.; Liu, Y.; Han, B.; Wei, B.; Wang, S. Z.

2017-12-01

Due to economic and environmental advantages pre-treatment containers have good big development prospects, which can avoid shot blasting processes, and decrease the noise and dust pollution. By analyzing requirements of the container steel surface quality, target oxide scale structure of free pretreatment container steel has been determined. Trial process was carried out, and test results showed that the oxide scale achieved the desired objects, oxide scale with outer thin Fe3O4 layer and inner eutectoid α-Fe+Fe3O4. Salt spray test, second adhesion test, and modeling performance basically corroborated the container feasibility.

Evaluating effects of thinning on wood quality in southeast Alaska

Treesearch

Eini C. Lowell; Dennis P. Dykstra; Robert A. Monserud

2012-01-01

We examined the effect of thinning on wood quality of western hemlock (Tsuga heterophylla) and Sitka spruce (Picea sitchensis) located on Prince of Wales and Mitkof Islands in southeast Alaska. Sample trees came from paired plots (thinned versus unthinned) in eight naturally regenerated, mixed stands of young-growth western...

Cortical Thinning and Altered Cortico-Cortical Structural Covariance of the Default Mode Network in Patients with Persistent Insomnia Symptoms.

PubMed

Suh, Sooyeon; Kim, Hosung; Dang-Vu, Thien Thanh; Joo, Eunyeon; Shin, Chol

2016-01-01

Recent studies have suggested that structural abnormalities in insomnia may be linked with alterations in the default-mode network (DMN). This study compared cortical thickness and structural connectivity linked to the DMN in patients with persistent insomnia (PI) and good sleepers (GS). The current study used a clinical subsample from the longitudinal community-based Korean Genome and Epidemiology Study (KoGES). Cortical thickness and structural connectivity linked to the DMN in patients with persistent insomnia symptoms (PIS; n = 57) were compared to good sleepers (GS; n = 40). All participants underwent MRI acquisition. Based on literature review, we selected cortical regions corresponding to the DMN. A seed-based structural covariance analysis measured cortical thickness correlation between each seed region of the DMN and other cortical areas. Association of cortical thickness and covariance with sleep quality and neuropsychological assessments were further assessed. Compared to GS, cortical thinning was found in PIS in the anterior cingulate cortex, precentral cortex, and lateral prefrontal cortex. Decreased structural connectivity between anterior and posterior regions of the DMN was observed in the PIS group. Decreased structural covariance within the DMN was associated with higher PSQI scores. Cortical thinning in the lateral frontal lobe was related to poor performance in executive function in PIS. Disrupted structural covariance network in PIS might reflect malfunctioning of antero-posterior disconnection of the DMN during the wake to sleep transition that is commonly found during normal sleep. The observed structural network alteration may further implicate commonly observed sustained sleep difficulties and cognitive impairment in insomnia. © 2016 Associated Professional Sleep Societies, LLC.

Preparation of LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries by a mist CVD process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tadanaga, Kiyoharu, E-mail: tadanaga@chem.osakafu-u.ac.jp; Yamaguchi, Akihiro; Sakuda, Atsushi

2014-05-01

Highlights: • LiMn{sub 2}O{sub 4} thin films were prepared by using the mist CVD process. • An aqueous solution of lithium and manganese acetates is used for the precursor solution. • The cell with the LiMn{sub 2}O{sub 4} thin films exhibited a capacity of about 80 mAh/g. • The cell showed good cycling performance during 10 cycles. - Abstract: LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries were prepared by using so-called the “mist CVD process”, employing an aqueous solution of lithium acetate and manganese acetate, as the source of Li and Mn, respectively. The aqueousmore » solution of starting materials was ultrasonically atomized to form mist particles, and mists were transferred by nitrogen gas to silica glass substrate to form thin films. FE-SEM observation revealed that thin films obtained by this process were dense and smooth, and thin films with a thickness of about 750 nm were obtained. The electrochemical cell with the thin films obtained by sintering at 700 °C exhibited a capacity of about 80 mAh/g, and the cell showed good cycling performance during 10 cycles.« less

Structural characterization of niobium oxide thin films grown on SrTiO3 (111) and (La,Sr)(Al,Ta)O3 (111) substrates

NASA Astrophysics Data System (ADS)

Dhamdhere, Ajit R.; Hadamek, Tobias; Posadas, Agham B.; Demkov, Alexander A.; Smith, David J.

2016-12-01

Niobium oxide thin films have been grown by molecular beam epitaxy on SrTiO3 (STO) (111) and (La0.18Sr0.82)(Al0.59Ta0.41)O3 (LSAT) (111) substrates. Transmission electron microscopy (TEM) confirmed the formation of high quality films with coherent interfaces. Films grown with higher oxygen pressure on STO (111) resulted in a (110)-oriented NbO2 phase with a distorted rutile structure, which can be described as body-centered tetragonal. The a lattice parameter of NbO2 was determined to be ˜13.8 Å in good agreement with neutron diffraction results published in the literature. Films grown on LSAT (111) at lower oxygen pressure produced the NbO phase with a defective rock salt cubic structure. The NbO lattice parameter was determined to be a ≈ 4.26 Å. The film phase/structure identification from TEM was in good agreement with in situ x-ray photoelectron spectroscopy measurements that confirmed the dioxide and monoxide phases, respectively. The atomic structure of the NbO2/STO and NbO/LSAT interfaces was determined based on comparisons between high-resolution electron micrographs and image simulations.

A sextuple-band ultra-thin metamaterial absorber with perfect absorption

NASA Astrophysics Data System (ADS)

Yu, Dingwang; Liu, Peiguo; Dong, Yanfei; Zhou, Dongming; Zhou, Qihui

2017-08-01

This paper presents the design, simulation and measurement of a sextuple-band ultra-thin metamaterial absorber (MA). The unit cell of this proposed structure is composed of triangular spiral-shaped complementary structures imprinted on the dielectric substrate backed by a metal ground. The measured results are in good agreement with simulations with high absorptivities of more than 90% at all six absorption frequencies. In addition, this proposed absorber has good performances of ultra-thin, polarization insensitivity and a wide-angle oblique incidence, which can easily be used in many potential applications such as detection, imaging and sensing.

Crystallization of amorphous silicon thin films deposited by PECVD on nickel-metalized porous silicon.

PubMed

Ben Slama, Sonia; Hajji, Messaoud; Ezzaouia, Hatem

2012-08-17

Porous silicon layers were elaborated by electrochemical etching of heavily doped p-type silicon substrates. Metallization of porous silicon was carried out by immersion of substrates in diluted aqueous solution of nickel. Amorphous silicon thin films were deposited by plasma-enhanced chemical vapor deposition on metalized porous layers. Deposited amorphous thin films were crystallized under vacuum at 750°C. Obtained results from structural, optical, and electrical characterizations show that thermal annealing of amorphous silicon deposited on Ni-metalized porous silicon leads to an enhancement in the crystalline quality and physical properties of the silicon thin films. The improvement in the quality of the film is due to the crystallization of the amorphous film during annealing. This simple and easy method can be used to produce silicon thin films with high quality suitable for thin film solar cell applications.

Crystallization of amorphous silicon thin films deposited by PECVD on nickel-metalized porous silicon

PubMed Central

2012-01-01

Porous silicon layers were elaborated by electrochemical etching of heavily doped p-type silicon substrates. Metallization of porous silicon was carried out by immersion of substrates in diluted aqueous solution of nickel. Amorphous silicon thin films were deposited by plasma-enhanced chemical vapor deposition on metalized porous layers. Deposited amorphous thin films were crystallized under vacuum at 750°C. Obtained results from structural, optical, and electrical characterizations show that thermal annealing of amorphous silicon deposited on Ni-metalized porous silicon leads to an enhancement in the crystalline quality and physical properties of the silicon thin films. The improvement in the quality of the film is due to the crystallization of the amorphous film during annealing. This simple and easy method can be used to produce silicon thin films with high quality suitable for thin film solar cell applications. PMID:22901341

Programmable permanent data storage characteristics of nanoscale thin films of a thermally stable aromatic polyimide.

PubMed

Kim, Dong Min; Park, Samdae; Lee, Taek Joon; Hahm, Suk Gyu; Kim, Kyungtae; Kim, Jin Chul; Kwon, Wonsang; Ree, Moonhor

2009-10-06

We have synthesized a new thermally and dimensionally stable polyimide, poly(4,4'-amino(4-hydroxyphenyl)diphenylene hexafluoroisopropylidenediphthalimide) (6F-HTPA PI). 6F-HTPA PI is soluble in organic solvents and is thus easily processed with conventional solution coating techniques to produce good quality nanoscale thin films. Devices fabricated with nanoscale thin PI films with thicknesses less than 77 nm exhibit excellent unipolar write-once-read-many-times (WORM) memory behavior with a high ON/OFF current ratio of up to 10(6), a long retention time and low power consumption, less than +/-3.0 V. Furthermore, these WORM characteristics were found to persist even at high temperatures up to 150 degrees C. The WORM memory behavior was found to be governed by trap-limited space-charge limited conduction and local filament formation. The conduction processes are dominated by hole injection. Thus the hydroxytriphenylamine moieties of the PI polymer might play a key role as hole trapping sites in the observed WORM memory behavior. The properties of 6F-HTPA PI make it a promising material for high-density and very stable programmable permanent data storage devices with low power consumption.

Located in the Thin of It: Young Children's Use of Thin Moral Concepts

ERIC Educational Resources Information Center

Wright, Jennifer Cole; Sedlock, Trisha; West, Jenny; Saulpaugh, Kelly; Hopkins, Michelle

2016-01-01

One important socio-cultural medium through which young children's moral understanding is cultivated is parent/child discourse. Of particular interest to us was young children's use of basic ("thin") evaluative concepts ("good," "bad," "right" and "wrong"), which are ubiquitous in everyday…

Controle des proprietes des couches optiques par bombardement ionique

NASA Astrophysics Data System (ADS)

Marushka, Viktor

The manufacture of optical coatings presents many challenges such as the control over the film properties and microstructure, the optimization for the production of thin films with high quality, and the research on new materials. Ion-assisted evaporation is one of the principal methods used for the fabrication of optical coatings as a response to these challenges. It allows for good process control, and it permits us to predict and put on an industrial scale the deposition process by considering the direct and quantitative relation between the energies of the incident ions, and the performance of the deposited materials. This work is devoted to the study of the effect of ion bombardment on the microstructure and properties of optical thin films of silicon dioxide and titanium dioxide, which are widely used in optical interference filters, in particular with the use of a Hall effect ion source. These studies include a systematic evaluation of the mechanical and optical properties and of the density of thin films using different complementary techniques - the Quartz Crystal Microbalance, Rutherford Backscattering Spectroscopy, and Infrared Variable Angle Spectroscopic Ellipsometry among others. Different approaches (Spectroscopic Ellipsometry and Infrared Ellipsometry, the measurement of mechanical stress) have been used to evaluate the amount of water in thin films. The results on the density of films and the presence of water in the films obtained by the different methods are in good agreement. It was found that the critical energy values giving rise to dense and stable optical coatings of silicon dioxide and titanium dioxide are 25 eV/atom and 45 eV/atom, respectively. Moreover, this work presents the methodology developed to determine the ion current density distribution on the surface of a substrate holder of a dome shape for different positions relative to the ion source. The proposed analysis can be used as an effective tool for the construction of an industrial reactor and for its appropriate optimization.

Cortical Thinning and Altered Cortico-Cortical Structural Covariance of the Default Mode Network in Patients with Persistent Insomnia Symptoms

PubMed Central

Suh, Sooyeon; Kim, Hosung; Dang-Vu, Thien Thanh; Joo, Eunyeon; Shin, Chol

2016-01-01

Study Objectives: Recent studies have suggested that structural abnormalities in insomnia may be linked with alterations in the default-mode network (DMN). This study compared cortical thickness and structural connectivity linked to the DMN in patients with persistent insomnia (PI) and good sleepers (GS). Methods: The current study used a clinical subsample from the longitudinal community-based Korean Genome and Epidemiology Study (KoGES). Cortical thickness and structural connectivity linked to the DMN in patients with persistent insomnia symptoms (PIS; n = 57) were compared to good sleepers (GS; n = 40). All participants underwent MRI acquisition. Based on literature review, we selected cortical regions corresponding to the DMN. A seed-based structural covariance analysis measured cortical thickness correlation between each seed region of the DMN and other cortical areas. Association of cortical thickness and covariance with sleep quality and neuropsychological assessments were further assessed. Results: Compared to GS, cortical thinning was found in PIS in the anterior cingulate cortex, precentral cortex, and lateral prefrontal cortex. Decreased structural connectivity between anterior and posterior regions of the DMN was observed in the PIS group. Decreased structural covariance within the DMN was associated with higher PSQI scores. Cortical thinning in the lateral frontal lobe was related to poor performance in executive function in PIS. Conclusion: Disrupted structural covariance network in PIS might reflect malfunctioning of antero-posterior disconnection of the DMN during the wake to sleep transition that is commonly found during normal sleep. The observed structural network alteration may further implicate commonly observed sustained sleep difficulties and cognitive impairment in insomnia. Citation: Suh S, Kim H, Dang-Vu TT, Joo E, Shin C. Cortical thinning and altered cortico-cortical structural covariance of the default mode network in patients with persistent insomnia symptoms. SLEEP 2016;39(1):161–171. PMID:26414892

Cr:ZnSe planar waveguide mid-IR laser

NASA Astrophysics Data System (ADS)

Willimas, J. E.; Martyshkin, D. V.; Fedorov, V. V.; Moskalev, I. S.; Camata, R. P.; Mirov, S. B.

2011-02-01

Middle infrared (mid-IR) chromium-doped zinc selenide (Cr:ZnSe) bulk lasers have attracted a lot of attention due to their unique combination of optical and laser properties facilitating a wide range of potential scientific, industrial, and medical applications. Utilization of thin film waveguide geometry enabling good thermal management and control of beam quality is a viable pathway for compact chip-integrated optical laser design. Cr:ZnSe thin films are also promising as saturable absorbers and mode-lockers of the cavities of solid state lasers operating over 1.3-2.1 μm. We recently reported the first successful demonstration of mid-IR Cr:ZnSe planar waveguide lasing at 2.6 μm under gain-switched short-pulse (5 ns) 1.56 μm excitation as well as the passive Q-switching of the cavity of a fiber-pumped Er:YAG laser operating at 1645 nm using a highly doped Cr:ZnSe thin film. PLD grown Cr:ZnSe waveguide were fabricated on sapphire substrates (Cr:ZnSe/sapphire) with chromium concentration of 1018-1019 cm-3. Further development of mid-IR lasing in the Cr:ZnSe planar waveguide under continuous wave excitation were investigated. In addition, deposition of Cr:ZnSe-based thin film structures on n-type GaAs substrates were also investigated for possible mid-IR electroluminescence.

High-performance thin layer chromatography to assess pharmaceutical product quality.

PubMed

Kaale, Eliangiringa; Manyanga, Vicky; Makori, Narsis; Jenkins, David; Michael Hope, Samuel; Layloff, Thomas

2014-06-01

To assess the sustainability, robustness and economic advantages of high-performance thin layer chromatography (HPTLC) for quality control of pharmaceutical products. We compared three laboratories where three lots of cotrimoxazole tablets were assessed using different techniques for quantifying the active ingredient. The average assay relative standard deviation for the three lots was 1.2 with a range of 0.65-2.0. High-performance thin layer chromatography assessments are yielding valid results suitable for assessing product quality. The local pharmaceutical manufacturer had evolved the capacity to produce very high quality products. © 2014 John Wiley & Sons Ltd.

Growth temperature modulated phase evolution and functional characteristics of high quality Pb1-x Lax (Zr0.9Ti0.1)O3 thin films

NASA Astrophysics Data System (ADS)

Kumar, Anuj; Pawar, Shuvam; Singh, Kirandeep; Kaur, Davinder

2018-05-01

In this study, we have reported the influence of growth temperature on perovskite phase evolution in sputtered deposited high quality Pb1-x Lax (Zr0.9 Ti0.1)O3 (PLZT) thin films on Pt/Ti/SiO2/Si substrate. PLZT thin films were fabricated at substrate temperature ranging from 400 to 700 °C. We have investigated the structural, dielectric, ferroelectric and leakage current characteristics of these thin films. XRD patterns reveal that 600 °C is the optimized temperature to deposit highly (110) oriented perovskite phase PLZT thin film. The further increase in temperature (700 °) causes reappearance of additional peaks corresponding to lead deficient pyrochlore phase. All PLZT thin films show decrease in dielectric constant with frequency. However, PLZT thin film fabricated at 600 °C displays dielectric constant ˜532 at 1 MHz frequency which is relatively higher than other deposited thin films. The P-E loops of these PLZT thin films exhibit strong dependence on deposition temperature. The pure perovskite PZLT thin film shows saturation polarization of ˜51.2µC/cm2 and coercive field (2Ec) ˜67.85 kV/cm. These high quality PLZT thin films finds their applications in non-volatile memory and nano-electro-mechanical systems (NEMS).

Growth and Development of Thinned Versus Unthinned Yellow-Poplar Sprout Clumps

Treesearch

Donald E. Beck

1977-01-01

Yellow-poplar stump sprouts are capable of very rapid growth and often dominate stands on good sites following harvest cutting. Thinning to one stem per stump at 6 years of age did not affect either height or diameter growth over the succeeding 18 years. The untreated clumps thinned themselves to an average of two stems per clump during the same time period. Thinning...

A versatile route to polymer-reinforced, broadband antireflective and superhydrophobic thin films without high-temperature treatment.

PubMed

Ren, Tingting; Geng, Zhi; He, Junhui; Zhang, Xiaojie; He, Jin

2017-01-15

Broadband high transmittance, good mechanical robustness as well as simple and low temperature fabrication are three important aspects that dictate the practical applications of superhydrophobic thin films, especially on organic substrates. However, it has proved difficult to meet these challenges. In the present work, superhydrophobic thin films were prepared by first dip-coating solid silica nanoparticles, then spray-coating hollow silica nanoparticles, followed by spray-coating mesoporous silica nanosheets & poly(vinyl alcohol) (PVA), and eventually chemical vapor deposition of 1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) at 90°C. The optimized thin film has a maximum transmittance of 96.0% in the wavelength range of 300-2500nm and a WCA of 164° and a RA of 1°. The thin film also shows good mechanical robustness toward water droplet impact test, sand impact abrasion test and tape adhesion tests, which results from PVA as a binder, the formation of covalent bond between the hydroxyl group of PVA and the ethoxy group of POTS and the chemical inertness of CC, CF bonds of POTS molecules. To our best knowledge, it is the first example where antireflective and superhydrophobic thin films of excellent mechanical robustness were realized at low temperature on organic substrates (PMMA, PC). The current work would provide a promising route to meet the challenges in practical applications simultaneously posed by the requirements of broadband antireflection, good mechanical robustness as well as simple and low temperature fabrication of superhydrophobic thin films. Copyright © 2016 Elsevier Inc. All rights reserved.

Welding with the thin disc laser: new processing and application potentials

NASA Astrophysics Data System (ADS)

Hügel, H.; Ruβ, A.; Weberpals, J.; Dausinger, F.

2005-09-01

Thin disc lasers represent a new class of welding lasers in that they combine the beneficial characteristics of CO2- and Nd:YAG-lasers. Their good focusability--values of M2 around 20 are typical for devices in the multi kW power range--can be utilized in several ways to improve the welding performance: compared to lamp-pumped Nd:YAG-lasers, the laser power required at the threshold to the deep penetration regime can be reduced, the welding depth can be increased and far higher values of traverse speed are applicable at prescribed welding depths. Alternatively, the high beam quality allows the use of focusing optics with large focal lengths, hence enabling the realization of "remote welding" concepts. At the same time, a wavelength of 1.03 μm (Yb:YAG) provides, in comparison to CO2-lasers, a high absorptivity at metallic workpieces and a low sensitivity against plasma production; both effects contribute to the efficiency, stability and achievable quality of the welding process. Further, beam delivery via flexible glass fibers with core diameters of 100 μm to 150 μm is possible. With these features and an overall (plug) efficiency of more than 20 %, this laser offers a large potential for many applications.

Thin-Film Ferro Electric-Coupled Microstripline Phase Shifters With Reduced Device Hysteresis

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Romanofsky, Robert; Mueller, Carl H.; VanKeuls, Frederick

2010-01-01

This work deals with the performance of coupled microstripline phase shifters (CMPS) fabricated using BaxSr 1 -xTiO 3 (BST) ferroelectric thin films. The CMPS were fabricated using commercially available pulsed laser deposition BST films with Ba:Sr ratios of 30:70 and 20:80. Microwave characterization of these CMPS was performed at upper Kuband frequencies, particularly at frequencies near 16 and 18 GHz. X-ray diffraction studies indicate that the 30:70 films exhibit almost a 1:1 ratio between the in-plane and out-of-plane lattice parameters, suggesting that their cubics create strain -free films suitable for producing CMPS devices with reduced hysteresis in the paraelectric state. The quality of performance of the CMPS was studied based on their relative phase shift and insertion loss within the DC bias range of 0 to 400 V (i.e., E-field ranges within 0 to 53 V/micron). The performance of the CMPS was tested as a function of temperature to investigate their operation in the paraelectric, as well as in the ferroelectric, state (i.e., above and below the Curie temperature, respectively). The novel behavior discussed here is based on the experimental observation of the CMPS. This behavior, observed for the aforementioned cation ratio, highlights the relevance of good crystalline structure for high-quality CMPS.

Investigation into the influence of laser energy input on selective laser melted thin-walled parts by response surface method

NASA Astrophysics Data System (ADS)

Liu, Yang; Zhang, Jian; Pang, Zhicong; Wu, Weihui

2018-04-01

Selective laser melting (SLM) provides a feasible way for manufacturing of complex thin-walled parts directly, however, the energy input during SLM process, namely derived from the laser power, scanning speed, layer thickness and scanning space, etc. has great influence on the thin wall's qualities. The aim of this work is to relate the thin wall's parameters (responses), namely track width, surface roughness and hardness to the process parameters considered in this research (laser power, scanning speed and layer thickness) and to find out the optimal manufacturing conditions. Design of experiment (DoE) was used by implementing composite central design to achieve better manufacturing qualities. Mathematical models derived from the statistical analysis were used to establish the relationships between the process parameters and the responses. Also, the effects of process parameters on each response were determined. Then, a numerical optimization was performed to find out the optimal process set at which the quality features are at their desired values. Based on this study, the relationship between process parameters and SLMed thin-walled structure was revealed and thus, the corresponding optimal process parameters can be used to manufactured thin-walled parts with high quality.

Epitaxial Ferroelectric Ba(0.5)Sr(0.5)TiO3 Thin Films for Room-Temperature High-Frequency Tunable Element Applications

NASA Technical Reports Server (NTRS)

Chen, C. L.; Feng, H. H.; Zhang, Z.; Brazdeikis, A.; Miranda, F. A.; VanKeuls, F. W.; Romanofsky, R. R.; Huang, Z. J.; Liou, Y.; Chu, W. K.;

Effect of solvent volume on the physical properties of aluminium doped nanocrystalline zinc oxide thin films deposited using a simplified spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Jabena Begum, N.; Mohan, R.; Ravichandran, K.

2013-01-01

Aluminium doped zinc oxide (AZO) thin films were deposited by employing a low cost and simplified spray technique using a perfume atomizer from starting solutions having different volumes (10, 20, … , 50 mL) of solvent. The effect of solvent volume on the structural, electrical, optical, photoluminescence (PL) and surface morphological properties was studied. The electrical resistivity of the AZO films is remarkably influenced by the variation in the solvent volume. The X-ray diffraction profiles clearly showed that all the films have preferential orientation along the (0 0 2) plane irrespective of the solvent volume. The crystallite size was found to be in the nano range of 35-46 nm. The optical transmittance in the visible region is desirably high (>85%). The AFM images show columnar morphology with varying grain size. The PL studies revealed that the AZO film deposited from 50 mL of solvent volume has good quality with lesser defect density.

Image degradation by glare in radiologic display devices

NASA Astrophysics Data System (ADS)

Badano, Aldo; Flynn, Michael J.

1997-05-01

No electronic devices are currently available that can display digital radiographs without loss of visual information compared to traditional transilluminated film. Light scattering within the glass faceplate of cathode-ray tube (CRT) devices causes excessive glare that reduces image contrast. This glare, along with ambient light reflection, has been recognized as a significant limitation for radiologic applications. Efforts to control the effect of glare and ambient light reflection in CRTs include the use of absorptive glass and thin film coatings. In the near future, flat panel displays (FPD) with thin emissive structures should provide very low glare, high performance devices. We have used an optical Monte Carlo simulation to evaluate the effect of glare on image quality for typical CRT and flat panel display devices. The trade-off between display brightness and image contrast is described. For CRT systems, achieving good glare ratio requires a reduction of brightness to 30-40 percent of the maximum potential brightness. For FPD systems, similar glare performance can be achieved while maintaining 80 percent of the maximum potential brightness.

Microstructure-related properties at 193 nm of MgF2 and GdF3 films deposited by a resistive-heating boat.

PubMed

Liu, Ming-Chung; Lee, Cheng-Chung; Kaneko, Masaaki; Nakahira, Kazuhide; Takano, Yuuichi

2006-03-01

MgF2 and GdF3 materials, used for a single-layer coating at 193 nm, are deposited by a resistive-heating boat at specific substrate temperatures. Optical characteristics (transmittance, refractive index, extinction coefficient, and optical loss) and microstructures (morphology and crystalline structure) are investigated and discussed. Furthermore, MgF2 is used as a low-index material, and GdF3 is used as a high-index material for multilayer coatings. Reflectance, stress, and the laser-induced damage threshold (LIDT) are studied. It is shown that MgF2 and GdF3 thin films, deposited on the substrate at a temperature of 300 degrees C, obtain good quality thin films with high transmittance and little optical loss at 193 nm. For multilayer coatings, the stress mainly comes from MgF2, and the absorption comes from GdF3. Among those coatings, the sixteen-layer design, sub/(1.4L 0.6H)8/air, shows the largest LIDT.

Inkjet printing of metal-oxide-based transparent thin-film capacitors

NASA Astrophysics Data System (ADS)

Matavž, A.; Malič, B.; Bobnar, V.

2017-12-01

We report on the inkjet printing of transparent, thin-film capacitors (TTFCs) composed of indium-zinc-oxide electrodes and a tantalum-oxide-based dielectric on glass substrates. The printing parameters were adapted for the sequential deposition of functional layers, resulting in approximately 100-nm-thick transparent capacitors with a uniform thickness. The relatively high electrical resistivity of the electrodes is reflected in the frequency dispersive dielectric behaviour, which is explained in terms of an equivalent circuit. The resistivity of the electrode strongly decreases with the number of printing passes; consequently, any misalignment of the printed layers is detected in the measured response. At low frequency, the TTFCs show a stable intrinsic dielectric response and a high capacitance density of ˜280 nF/cm2. The good dielectric performance as well as the low leakage-current density (8 × 10-7 A/cm2 at 1 MV cm-1) of our capacitors indicates that inkjet printing can be used to produce all-printed, high-quality electrical devices.

Thinning sprout clumps

Treesearch

Robert Rogers

1989-01-01

Only stump sprouts originating in clearcuts or extremely heavily thinned stands have significant potential for developing into good trees. Stump sprouts can account for as many as half the stems after a clearcut of central hardwoods.

Ultracompact low-threshold organic laser.

PubMed

Deotare, Parag B; Mahony, Thomas S; Bulović, Vladimir

2014-11-25

We report an ultracompact low-threshold laser with an Alq3:DCM host:guest molecular organic thin film gain layer. The device uses a photonic crystal nanobeam cavity which provides a high quality factor to mode volume (Q/V) ratio and increased spontaneous emission factor along with a small footprint. Lasing is observed with a threshold of 4.2 μJ/cm(2) when pumped by femtosecond pulses of λ = 400 nm wavelength light. We also model the dynamics of the laser and show good agreement with the experimental data. The inherent waveguide geometry of the structure enables easy on-chip integration with potential applications in biochemical sensing, inertial sensors, and data communication.

Monolayer-crystal streptavidin support films provide an internal standard of cryo-EM image quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Bong-Gyoon; Watson, Zoe; Cate, Jamie H. D.

Analysis of images of biotinylated Escherichia coli 70S ribosome particles, bound to streptavidin affinity grids, demonstrates that the image-quality of particles can be predicted by the image-quality of the monolayer crystalline support film. Also, the quality of the Thon rings is a good predictor of the image-quality of particles, but only when images of the streptavidin crystals extend to relatively high resolution. When the estimated resolution of streptavidin was 5 Å or worse, for example, the ribosomal density map obtained from 22,697 particles went to only 9.5 Å, while the resolution of the map reached 4.0 Å for the samemore » number of particles, when the estimated resolution of streptavidin crystal was 4 Å or better. It thus is easy to tell which images in a data set ought to be retained for further work, based on the highest resolution seen for Bragg peaks in the computed Fourier transforms of the streptavidin component. The refined density map obtained from 57,826 particles obtained in this way extended to 3.6 Å, a marked improvement over the value of 3.9 Å obtained previously from a subset of 52,433 particles obtained from the same initial data set of 101,213 particles after 3-D classification. These results are consistent with the hypothesis that interaction with the air-water interface can damage particles when the sample becomes too thin. Finally, streptavidin monolayer crystals appear to provide a good indication of when that is the case.« less

Effect of Zn and Te beam intensity upon the film quality of ZnTe layers on severely lattice mismatched sapphire substrates by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Nakasu, Taizo; Sun, W.; Kobayashi, M.; Asahi, T.

2017-06-01

Zinc telluride layers were grown on highly-lattice-mismatched sapphire substrates by molecular beam epitaxy, and their crystallographic properties were studied by means of X-ray diffraction pole figures. The crystal quality of the ZnTe thin film was further studied by scanning electron microscopy, X-ray rocking curves and low-temperature photoluminescence measurements. These methods show that high-crystallinity (111)-oriented single domain ZnTe layers with the flat surface and good optical properties are realized when the beam intensity ratio of Zn and Te beams is adjusted. The migration of Zn and Te was inhibited by excess surface material and cracks were appeared. In particular, excess Te inhibited the formation of a high-crystallinity ZnTe film. The optical properties of the ZnTe layer revealed that the exciton-related features were dominant, and therefore the film quality was reasonably high even though the lattice constants and the crystal structures were severely mismatched.

Qualitative and quantitative analysis of seven oligosaccharides in Morinda officinalis using double-development HPTLC and scanning densitometry.

PubMed

Zhou, Bin; Chang, Jun; Wang, Ping; Li, Jie; Cheng, Dan; Zheng, Peng-Wu

2014-01-01

The quality of Morindaofficinalis, which has been used as a Yang-tonic agent for a long time in China, can be evaluated. A double-development high performance thin layer chromatography (HPTLC) method has been established to simultaneously analyze quality and quantity of seven inulin-type oligosaccharides (DP=3-9) in Morindaofficinalis. The chromatography was performed on a silica gel 60 plate with the 7:5:2:1 proportion (v/v) of n-butanol-isopropanol-water-acetic acid for the first and second developments, respectively. The bands were visualized by the reaction with aniline-diphenylamine-phosphoric acid solution and analyzed by densitometric TLC at 540 nm. Quantification of seven oligosaccharides was achieved by densitometry at 540 nm. The investigated standard sugar had good linearity (R2>0.99) within test ranges. The amounts of seven oligosaccharides were calculated by the relative correction factor (RCF). Therefore, the developed TLC method could be used for quality control of Morindaofficinalis.

Fabrication and characterization of {110}-oriented Pb(Zr,Ti)O3 thin films on Pt/SiO2/Si substrates using PdO//Pd buffer layer

NASA Astrophysics Data System (ADS)

Oshima, Naoya; Uchiyama, Kiyoshi; Ehara, Yoshitaka; Oikawa, Takahiro; Ichinose, Daichi; Tanaka, Hiroki; Sato, Tomoya; Uchida, Hiroshi; Funakubo, Hiroshi

2017-10-01

A strongly {110}-oriented perovskite-type thin film of tetragonal Pb(Zr0.4Ti0.6)O3 (PZT) was successfully obtained on a (100)Si substrate using a {101}PdO//{111}Pd thin film as a buffer layer. The {101}PdO//{111}Pd thin film buffer layer was obtained by oxidizing {111}Pd after depositing {111}Pd on a {111}Pt/TiO x /SiO2/{100}Si substrate. Using this buffer layer, a {110} c -oriented SrRuO3 (SRO) thin film was deposited by sputtering as a bottom electrode of PZT thin films. Subsequently, the {110}-oriented PZT thin film can be deposited on a (110) c SRO thin film by metal-organic chemical deposition (MOCVD) and its properties can be compared with those of PZT thin films with other orientations of {100} and {111}. Among the {100}, {110}, {111}-oriented PZT films, the {100}-oriented one showed the largest remnant polarization, which is in good agreement with those of the PZTs epitaxially grown in the 〈100〉, 〈110〉, and 〈111〉 directions. The other properties, i.e., piezoelectricity and dielectric constants, also showed similar anisotropic tendencies, which is in good agreement with the data reported in the epitaxially grown PZTs.

Growth and nonlinear optical characterization of organic single crystal films

NASA Astrophysics Data System (ADS)

Zhou, Ligui

1997-12-01

Organic single crystal films are important for various future applications in photonics and integrated optics. The conventional method for inorganic crystal growth is not suitable for organic materials, and the high temperature melting method is not good for most organic materials due to decomposition problems. We developed a new method-modified shear method-to grow large area organic single crystal thin films which have exceptional nonlinear optical properties and high quality surfaces. Several organic materials (NPP, PNP and DAST) were synthesized and purified before the thin film crystal growth. Organic single crystal thin films were grown from saturated organic solutions using modified shear method. The area of single crystal films were about 1.5 cm2 for PNP, 1 cm2 for NPP and 5 mm2 for DAST. The thickness of the thin films which could be controlled by the applied pressure ranged from 1μm to 10 μm. The single crystal thin films of organic materials were characterized by polarized microscopy, x-ray diffraction, polarized UV-Visible and polarized micro-FTIR spectroscopy. Polarized microscopy showed uniform birefringence and complete extinction with the rotation of the single crystal thin films under crossed- polarization, which indicated high quality single crystals with no scattering. The surface orientation of single crystal thin films was characterized by x-ray diffraction. The molecular orientation within the crystal was further studied by the polarized UV-Visible and Polarized micro-FTIR techniques combined with the x-ray and polarized microscopy results. A Nd:YAG laser with 35 picosecond pulses at 1064nm wavelength was employed to perform the nonlinear optical characterization of the organic single crystal thin films. Two measurement techniques were used to study the crystal films: second harmonic generation (SHG) and electro-optic (EO) effect. SHG results showed that the nonlinear optical coefficient of NPP was 18 times that of LiNbO3, a standard inorganic crystal material, and the nonlinear optical coefficient of PNP was 11 times that of LiNbO3. Electro-optic measurements showed that r11 = 65 pm/V for NPP and r12 = 350 pm/V for DAST. EO modulation effect was also observed using Fabry-Perot interferometry. Waveguide devices are very important for integrated optics. But the fabrication of waveguide devices on the organic single crystal thin films was difficult due to the solubility of the film in common organic solvents. A modified photolithographic technique was employed to make channel waveguides and poly(vinyl alcohol) (PVA) was used as a protective layer in the fabrication of the waveguides. Waveguides with dimensions about 7/mum x 1μm x 1mm were obtained.

Interaction of initial litter quality and thinning intensity on litter decomposition rate, nitrogen accumulation and release in a pine plantation

Treesearch

Xiao Chen; Deborah Page-Dumroese; Ruiheng Lv; Weiwei Wang; Guolei Li; Yong Liu

2014-01-01

Thinning alters litter quality and microclimate under forests. Both of these two changes after thinning induce alterations of litter decomposition rates and nutrient cycling. However, a possible interaction between these two changes remains unclear. We placed two types of litter (LN, low N concentration litter; HN, high N concentration litter) in a Chinese pine (Pinus...

Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

DOEpatents

Repins, Ingrid L.; Kuciauskas, Darius

2015-07-07

A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

Strengthening of national capacity in implementation of antimalarial drug quality assurance in Thailand.

PubMed

Vijaykadga, Saowanit; Cholpol, Sawat; Sitthimongkol, Saipin; Pawaphutanan, Anusorn; Pinyoratanachot, Arunya; Rojanawatsirivet, Chaiporn; Kovithvattanapong, Rojana; Thimasarn, Krongthong

2006-01-01

Substandard and counterfeit pharmaceutical products, including antimalarial drugs, appear to be widespread internationally and affect both the developing and developed countries. The aim of the study was to investigate the quality of antimalarial drugs, ie, artesunate (ART), chloroquine (CHL), mefloquine (MEF), quinine (QUI), sulfadoxine/pyrimethamine (S/P) and tetracycline (TT) obtained from the government sector and private pharmacies in 4 Thai provinces: Mae Hong Son, Kanchanaburi, Ranong, and Chanthaburi. Three hundred sixty-nine samples of 6 antimalarial drugs from 27 government hospitals, 27 malaria clinics, and 53 drugstores, were collected. Drug quality was assessed by simple disintegration test and semi-quantitative thin-layer chromatography in each province; 10% passed, 100% failed and doubtful samples were sent to be verified by high performance liquid chromatography (HPLC) at the Thai National Drug Analysis Laboratory, (NL). Fifteen point four percent of ART, 11.1% of CHL and 29.4% of QUI were substandard. Based on the finding, drug regulatory authorities in the country took appropriate action against violators to ensure that antimalarial drugs consumed by malaria patients are of good quality.

Bioenergy from trees: using cost-effective thinning to reduce forest fire hazards

Treesearch

Marie Oliver; Jeremy Fried; Jamie Barbour

2009-01-01

Increasingly large and severe wildfires threaten millions of forested acres throughout the West. Under certain conditions, mechanical thinning can address these hazardous conditions while providing opportunitiesto create renewable energy and reduce our carbon footprint but how do land managers decide whether thinning is a good idea? How do they decide where to begin,...

7 CFR 29.3152 - Lugs or Cutters (C Group).

Code of Federal Regulations, 2010 CFR

2010-01-01

... intensity, narrow, 70 percent uniform, and 30 percent injury tolerance. C1F Choice Tan Lugs. Medium to thin... uniform, and 5 percent injury tolerance. C2F Fine Tan Lugs. Medium to thin body, ripe, open, smooth... injury tolerance. C3F Good Tan Lugs. Medium to thin body, ripe, open, even, clear finish, moderate color...

7 CFR 29.3152 - Lugs or Cutters (C Group).

Code of Federal Regulations, 2011 CFR

2011-01-01

... intensity, narrow, 70 percent uniform, and 30 percent injury tolerance. C1F Choice Tan Lugs. Medium to thin... uniform, and 5 percent injury tolerance. C2F Fine Tan Lugs. Medium to thin body, ripe, open, smooth... injury tolerance. C3F Good Tan Lugs. Medium to thin body, ripe, open, even, clear finish, moderate color...

An acoustics operations study for Loblolly pine (Pinus taeda) standing saw timber with different thinning history

Treesearch

Charles Essien; Qingzheng Cheng; Brian K. Via; Edward F. Loewenstein; Xiping Wang

2016-01-01

There is currently a request from landowners in southeastern USA to provide a non-destructive tool that can differentiate the quality between stands of 25 and 30 years of age subjected to different thinning treatments. A typical site with various thinning regimes was used to vary the wood quality and to determine whether acoustics had the ability to seperate for...

Quality response of even-aged 80-year-old white oak trees after thinning

Treesearch

David L. Sonderman

1984-01-01

Stem defects were studied over an 18-year period to determine the effect of thinning intensity on quality development of 80-year-old white oak trees. Seventy-nine white oak trees from a thinning study in Kentucky were analyzed from stereo photographs taken in 1960 and 1978. Stem-related defects were measured on the butt 8-foot and second 8-foot sections of each tree....

7 CFR 29.3648 - Thin Leaf (C Group).

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Thin Leaf (C Group). 29.3648 Section 29.3648... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.3648 Thin Leaf (C Group). This group consists of leaves... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth...

7 CFR 29.3648 - Thin Leaf (C Group).

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 2 2012-01-01 2012-01-01 false Thin Leaf (C Group). 29.3648 Section 29.3648... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.3648 Thin Leaf (C Group). This group consists of leaves... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth...

7 CFR 29.3648 - Thin Leaf (C Group).

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 2 2013-01-01 2013-01-01 false Thin Leaf (C Group). 29.3648 Section 29.3648... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.3648 Thin Leaf (C Group). This group consists of leaves... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth...

7 CFR 29.3648 - Thin Leaf (C Group).

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 2 2011-01-01 2011-01-01 false Thin Leaf (C Group). 29.3648 Section 29.3648... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.3648 Thin Leaf (C Group). This group consists of leaves... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth...

7 CFR 29.3648 - Thin Leaf (C Group).

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 2 2014-01-01 2014-01-01 false Thin Leaf (C Group). 29.3648 Section 29.3648... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.3648 Thin Leaf (C Group). This group consists of leaves... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth...

Solvent-Assisted Surface Engineering for High-Performance All-Inorganic Perovskite Nanocrystal Light-Emitting Diodes.

PubMed

Wang, Lin; Liu, Baiquan; Zhao, Xin; Demir, Hilmi Volkan; Gu, Haoshuang; Sun, Handong

2018-06-13

All-inorganic cesium halide perovskite nanocrystals have attracted much interest in optoelectronic applications for the sake of the readily adjustable band gaps, high photoluminescence quantum yield, pure color emission, and affordable cost. However, because of the ineluctable utilization of organic surfactants during the synthesis, the structural and optical properties of CsPbBr 3 nanocrystals degrade upon transforming from colloidal solutions to solid thin films, which plagues the device operation. Here, we develop a novel solvent-assisted surface engineering strategy, producing high-quality CsPbBr 3 thin films for device applications. A good solvent is first introduced as an assembly trigger to conduct assembly in a one-dimensional direction, which is then interrupted by adding a nonsolvent. The nonsolvent drives the adjacent nanoparticles connecting in a two-dimensional direction. Assembled CsPbBr 3 nanocrystal thin films are densely packed and very smooth with a surface roughness of ∼4.8 nm, which is highly desirable for carrier transport in a light-emitting diode (LED) device. Meanwhile, the film stability is apparently improved. Benefiting from this facile and reliable strategy, we have achieved remarkably improved performance of CsPbBr 3 nanocrystal-based LEDs. Our results not only enrich the methods of nanocrystal surface engineering but also shed light on developing high-performance LEDs.

MgB2-Based Bolometer Array for Far Infra-Red Thermal Imaging and Fourier Transform Spectroscopy Applications

NASA Technical Reports Server (NTRS)

Lakew, B.; Aslam, S.; Brasunas, J.

2012-01-01

The mid-superconducting critical temperature (T(sub c) approximately 39 K) of the simple binary, intermetallic MgB, [1] makes it a very good candidate for the development of the next generation of electrooptical devices (e.g. [2]). In particular, recent advances in thin film deposition teclmiques to attain higb quality polycrystalline thin film MgB, deposited on SiN-Si substrates, with T(sub c) approximately 38K [3] coupled with the low voltage noise performance of the film [4] makes it higbly desirable for the development of moderately cooled bolometer arrays for integration into future space-bourne far infra-red (FIR) spectrometers and thermal mappers for studying the outer planets, their icy moons and other moons of interest in the 17-250 micrometer spectral wavelength range. Presently, commercially available pyroelectric detectors operating at 300 K have specific detectivity, D(*), around 7 x 10(exp 8) to 2 x 10(exp 9) centimeters square root of Hz/W. However, a MgB2 thin film based bolometer using a low-stress (less than 140 MPa) SiN membrane isolated from the substrate by a small thermal conductive link, operating at 38 K, promises to have two orders of magnitude higher specific detectivity [5][6].

Thinning and mounting a Texas Instruments 3-phase CCD

NASA Technical Reports Server (NTRS)

Lesser, M. P.; Leach, R. W.; Angel, J. R. P.

1986-01-01

Thin CCDs with precise control of thickness and surface quality allow astronomers to optimize chips for specific applications. A means of mechanically thinning a TI 800 x 800 CCD with an abrasive slurry of aluminum oxide is presented. Using the same techniques, the abrasives can be replaced with a chemical solution to eliminate subsurface damage. A technique of mounting the CCD which retains the high quality surface generated during thinning is also demonstrated. This requires the backside of the chip to be bonded to a glass window which closely matches silicon's thermal expansion properties. Thinned CCDs require backside treatment to enhance blue and UV quantum efficiency. Two methods are discussed which may be effective with this mounting system.

High quality atomically thin PtSe2 films grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

2017-12-01

Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

High performance batch production of LREBa 2Cu 3O y using novel thin film Nd-123 seed

NASA Astrophysics Data System (ADS)

Muralidhar, M.; Suzuki, K.; Fukumoto, Y.; Ishihara, A.; Tomita, M.

2011-11-01

A batch production for fabrication of LREBa2Cu3Oy (LRE: Sm, Gd, NEG) "LRE-123" pellets are developed in air and Ar-1% O2 using a novel thin film Nd-123 seeds grown on MgO crystals. The SEM and XRD results conformed that the quality and orientation of the seed crystals are excellent. On the other hand, new seeds can withstand temperatures >1100 °C, as a result, the cold seeding process was applied even to grow Sm-123 material in Air. The trapped field observed in the best 45 mm single-grain puck of Gd-123 was in the range of 1.35 T and 0.35 T at 77.3 K and 87.3 K, respectively. The average trapped field at 77.3 K in the 24 mm diameter NEG-123 samples batch lies between 0.9 and 1 T. The maximum trapped field of 1.2 T was recorded at the sample surface. Further, the maximum trapped field of 0.23 T at 77 K was recorded in a sample with 16 mm diameter of Sm-123 with 3 mol% BaO2 addition. As a result we made more then 130 single grain pucks within a couple of months. Taking advantage of the single grain batch processed material, we constructed self-made chilled levitation disk, which was used on the open day of railway technical research Institute. More then 150 children stood on the levitation disk and revel the experience of levitation. The present results prove that a high-performance good-quality class of LREBa2Cu3Oy material can be made by using a novel thin film Nd-123 seeds.

Ultrafast electron diffraction optimized for studying structural dynamics in thin films and monolayers

PubMed Central

Badali, D. S.; Gengler, R. Y. N.; Miller, R. J. D.

2016-01-01

A compact electron source specifically designed for time-resolved diffraction studies of free-standing thin films and monolayers is presented here. The sensitivity to thin samples is achieved by extending the established technique of ultrafast electron diffraction to the “medium” energy regime (1–10 kV). An extremely compact design, in combination with low bunch charges, allows for high quality diffraction in a lensless geometry. The measured and simulated characteristics of the experimental system reveal sub-picosecond temporal resolution, while demonstrating the ability to produce high quality diffraction patterns from atomically thin samples. PMID:27226978

Growth control of the oxidation state in vanadium oxide thin films

DOE PAGES

Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; ...

2014-12-05

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.« less

Growth control of the oxidation state in vanadium oxide thin films

NASA Astrophysics Data System (ADS)

Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

2014-12-01

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V2 + 3 O 3 , V + 4 O 2 , and V2 + 5 O 5 . A well pronounced MIT was only observed in VO2 films grown in a very narrow range of oxygen partial pressure P(O2). The films grown either in lower (<10 mTorr) or higher P(O2) (>25 mTorr) result in V2O3 and V2O5 phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO2 thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

Microwave response of high transition temperature superconducting thin films

NASA Technical Reports Server (NTRS)

Miranda, Felix Antonio

1991-01-01

We have studied the microwave response of YBa2Cu3O(7 - delta), Bi-Sr-Ca-Cu-O, and Tl-Ba-Ca-Cu-O high transition temperature superconducting (HTS) thin films by performing power transmission measurements. These measurements were carried out in the temperature range of 300 K to 20 K and at frequencies within the range of 30 to 40 GHz. Through these measurements we have determined the magnetic penetration depth (lambda), the complex conductivity (sigma(sup *) = sigma(sub 1) - j sigma(sub 2)) and the surface resistance (R(sub s)). An estimate of the intrinsic penetration depth (lambda approx. 121 nm) for the YBa2Cu3O(7 - delta) HTS has been obtained from the film thickness dependence of lambda. This value compares favorably with the best values reported so far (approx. 140 nm) in single crystals and high quality c-axis oriented thin films. Furthermore, it was observed that our technique is sensitive to the intrinsic anisotropy of lambda in this superconductor. Values of lambda are also reported for Bi-based and Tl-based thin films. We observed that for the three types of superconductors, both sigma(sub 1) and sigma(sub 2) increased when cooling the films below their transition temperature. The measured R(sub s) are in good agreement with other R(sub S) values obtained using resonant activity techniques if we assume a quadratic frequency dependence. Our analysis shows that, of the three types of HTS films studied, the YBa2Cu3O(7 - delta) thin film, deposited by laser ablation and off-axis magnetron sputtering are the most promising for microwave applications.

Growth control of the oxidation state in vanadium oxide thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Shinbuhm; Meyer, Tricia L.; Lee, Ho Nyung, E-mail: hnlee@ornl.gov

2014-12-01

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V{sub 2}{sup +3}O{sub 3}, V{sup +4}O{sub 2}, and V{sub 2}{sup +5}O{sub 5}. A well pronounced MIT was only observed in VO{sub 2} films grown in a very narrow range of oxygen partial pressure P(O{sub 2}). The films grown either in lower (<10 mTorr) or higher P(O{sub 2}) (>25 mTorr) result in V{sub 2}O{sub 3} and V{sub 2}O{sub 5} phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO{sub 2} thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.« less

Controlled electrodeposition of Cu-Ga from a deep eutectic solvent for low cost fabrication of CuGaSe2 thin film solar cells.

PubMed

Steichen, Marc; Thomassey, Matthieu; Siebentritt, Susanne; Dale, Phillip J

2011-03-14

The electrochemical deposition of Ga and Cu-Ga alloys from the deep eutectic solvent choline chloride/urea (Reline) is investigated to prepare CuGaSe(2) (CGS) semiconductors for their use in thin film solar cells. Ga electrodeposition is difficult from aqueous solution due to its low standard potential and the interfering hydrogen evolution reaction (HER). Ionic liquid electrolytes offer a better thermal stability and larger potential window and thus eliminate the interference of solvent breakdown reactions during Ga deposition. We demonstrate that metallic Ga can be electrodeposited from Reline without HER interference with high plating efficiency on Mo and Cu electrodes. A new low cost synthetic route for the preparation of CuGaSe(2) absorber thin films is presented and involves the one-step electrodeposition of Cu-Ga precursors from Reline followed by thermal annealing. Rotating disk electrode (RDE) cyclic voltammetry (CV) is used in combination with viscosity measurements to determine the diffusion coefficients of gallium and copper ions in Reline. The composition of the codeposited Cu-Ga precursor layers can be controlled to form Cu/Ga thin films with precise stoichiometry, which is important for achieving good optoelectronic properties of the final CuGaSe(2) absorbers. The morphology, the chemical composition and the crystal structure of the deposited thin films are analysed by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD). Annealing of the Cu-Ga films in a selenium atmosphere allowed the formation of high quality CuGaSe(2) absorber layers. Completed CGS solar cells achieved a 4.1% total area power conversion efficiency.

Fabrication of high-quality single-crystal Cu thin films using radio-frequency sputtering.

PubMed

Lee, Seunghun; Kim, Ji Young; Lee, Tae-Woo; Kim, Won-Kyung; Kim, Bum-Su; Park, Ji Hun; Bae, Jong-Seong; Cho, Yong Chan; Kim, Jungdae; Oh, Min-Wook; Hwang, Cheol Seong; Jeong, Se-Young

2014-08-29

Copper (Cu) thin films have been widely used as electrodes and interconnection wires in integrated electronic circuits, and more recently as substrates for the synthesis of graphene. However, the ultra-high vacuum processes required for high-quality Cu film fabrication, such as molecular beam epitaxy (MBE), restricts mass production with low cost. In this work, we demonstrated high-quality Cu thin films using a single-crystal Cu target and radio-frequency (RF) sputtering technique; the resulting film quality was comparable to that produced using MBE, even under unfavorable conditions for pure Cu film growth. The Cu thin film was epitaxially grown on an Al2O3 (sapphire) (0001) substrate, and had high crystalline orientation along the (111) direction. Despite the 10(-3) Pa vacuum conditions, the resulting thin film was oxygen free due to the high chemical stability of the sputtered specimen from a single-crystal target; moreover, the deposited film had >5× higher adhesion force than that produced using a polycrystalline target. This fabrication method enabled Cu films to be obtained using a simple, manufacturing-friendly process on a large-area substrate, making our findings relevant for industrial applications.

Effect of K-doping on structural and optical properties of ZnO thin films

NASA Astrophysics Data System (ADS)

Xu, Linhua; Li, Xiangyin; Yuan, Jun

2008-09-01

In this work, K-doped ZnO thin films were prepared by a sol-gel method on Si(111) and glass substrates. The effect of different K-doping concentrations on structural and optical properties of the ZnO thin films was studied. The results showed that the 1 at.% K-doped ZnO thin film had the best crystallization quality and the strongest ultraviolet emission ability. When the concentration of K was above 1 at.%, the crystallization quality and ultraviolet emission ability dropped. For the K-doped ZnO thin films, there was not only ultraviolet emission, but also a blue emission signal in their photoluminescent spectra. The blue emission might be connected with K impurity or/and the intrinsic defects (Zn interstitial and Zn vacancy) of the ZnO thin films.

Thinning and fertilizing red pine to increase growth and cone production.

Treesearch

John H. Cooley

1970-01-01

Cone production and growth were increased more by heavy thinning than by fertilizing in 53- and 55-year-old natural red pine stands growing on medium sites, and in a 20-year-old plantation on a good site.

Metallic alternative to glass mirrors (active mirrors in aluminium) - A review

NASA Astrophysics Data System (ADS)

Rozelot, Jean P.; Leblanc, Jean-M.

1991-09-01

Present-day glass mirrors for telescopes, including the most recent results obtained with aluminum mirrors developed within the European EUREKA procedure (LAMA program) are reviewed. The major advantages of the aluminum-alloy solution, which can be extrapolated today for large size, are discussed. It is shown that aluminum-alloy meniscus blanks, polished on a thin nickel coating, are appropriate to manufacture mirrors of astronomical quality. With the technique of electron-beam welding, large sizes can be envisaged. The development of active optics makes it possible to easily compensate for real-time deformations. The good thermal diffusivity of aluminum alloys leads to a better and faster thermal equilibrium than all other glass structures.

Sinusoidal nanotextures for light management in silicon thin-film solar cells.

PubMed

Köppel, G; Rech, B; Becker, C

2016-04-28

Recent progresses in liquid phase crystallization enabled the fabrication of thin wafer quality crystalline silicon layers on low-cost glass substrates enabling conversion efficiencies up to 12.1%. Because of its indirect band gap, a thin silicon absorber layer demands for efficient measures for light management. However, the combination of high quality crystalline silicon and light trapping structures is still a critical issue. Here, we implement hexagonal 750 nm pitched sinusoidal and pillar shaped nanostructures at the sun-facing glass-silicon interface into 10 μm thin liquid phase crystallized silicon thin-film solar cell devices on glass. Both structures are experimentally studied regarding their optical and optoelectronic properties. Reflection losses are reduced over the entire wavelength range outperforming state of the art anti-reflective planar layer systems. In case of the smooth sinusoidal nanostructures these optical achievements are accompanied by an excellent electronic material quality of the silicon absorber layer enabling open circuit voltages above 600 mV and solar cell device performances comparable to the planar reference device. For wavelengths smaller than 400 nm and higher than 700 nm optical achievements are translated into an enhanced quantum efficiency of the solar cell devices. Therefore, sinusoidal nanotextures are a well-balanced compromise between optical enhancement and maintained high electronic silicon material quality which opens a promising route for future optimizations in solar cell designs for silicon thin-film solar cells on glass.

Electrical contacts to thin layers of Bi2Sr2CaCu2O8+δ

NASA Astrophysics Data System (ADS)

Suzuki, Shota; Taniguchi, Hiroki; Kawakami, Tsukasa; Cosset-Cheneau, Maxen; Arakawa, Tomonori; Miyasaka, Shigeki; Tajima, Setsuko; Niimi, Yasuhiro; Kobayashi, Kensuke

2018-05-01

Thin layers of Bi2Sr2CaCu2O8+δ (Bi2212) were fabricated using the mechanical exfoliation technique. Good electrical contacts to the thin Bi2212 films with low contact resistance were realized by depositing Ag and Au electrodes onto the Bi2212 films and annealing them with an oxygen flow at 350 °C for 30 min. We observed cross-section images of the Bi2212 thin film device using a transmission electron microscope to characterize the diffusion of Ag and Au atoms into the Bi2212 thin film.

Chemical vapor deposition of silicon, silicon dioxide, titanium and ferroelectric thin films

NASA Astrophysics Data System (ADS)

Chen, Feng

Various silicon-based thin films (such as epitaxial, polycrystalline and amorphous silicon thin films, silicon dioxide thin films and silicon nitride thin films), titanium thin film and various ferroelectric thin films (such as BaTiO3 and PbTiO3 thin films) play critical roles in the manufacture of microelectronics circuits. For the past few years, there have been tremendous interests to search for cheap, safe and easy-to-use methods to develop those thin films with high quality and good step coverage. Silane is a critical chemical reagent widely used to deposit silicon-based thin films. Despite its wide use, silane is a dangerous material. It is pyrophoric, extremely flammable and may explode from heat, shock and/or friction. Because of the nature of silane, serious safety issues have been raised concerning the use, transportation, and storage of compressed gas cylinders of silane. Therefore it is desired to develop safer ways to deposit silicon-based films. In chapter III, I present the results of our research in the following fields: (1) Silane generator, (2) Substitutes of silane for deposition of silicon and silicon dioxide thin films, (3) Substitutes of silane for silicon dioxide thin film deposition. In chapter IV, hydropyridine is introduced as a new ligand for use in constructing precursors for chemical vapor deposition. Detachement of hydropyridine occurs by a low-temperature reaction leaving hydrogen in place of the hydropyridine ligands. Hydropyridine ligands can be attached to a variety of elements, including main group metals, such as aluminum and antimony, transition metals, such as titanium and tantalum, semiconductors such as silicon, and non-metals such as phosphorus and arsenic. In this study, hydropyridine-containing titanium compounds were synthesized and used as chemical vapor deposition precursors for deposition of titanium containing thin films. Some other titanium compounds were also studied for comparison. In chapter V, Chemical Vapor Depositions (CVD) of many oxide thin films including ferroelectric and high dielectric constant BaTiO3, SrTiO 3 and PbTiO3 films had been carried out under reduced pressure (30 torr--80 torr) using liquid precursors containing beta-diketone ligands. The relative reactivities of Ba(beta-diketonate)2, Sr(beta-diketonate) 2, Pb(beta-diketonate)2, Ti(beta-diketonate)3, TiO(beta-diketonate)2 and Ti(OiPr)2(beta-diketonate) 2 had been studied individually prior to the deposition of BaTiO 3, SrTiO3 and PbTiO3 thin films from the mixtures of corresponding precursors. By using multi-step deposition method, carbon free stoichiometric BaTiO3 thin films uniform in large area have been achieved.

Effect of drying conditions on drying kinetics and quality of aromatic Pandanus amaryllifolius leaves.

PubMed

Rayaguru, Kalpana; Routray, Winny

2010-12-01

Pandanus amaryllifolius is a plant with aromatic leaves, which impart the characteristic flavour of aromatic rice. The quality of aromatic Pandanus leaves dried at low temperature (35 °C) and low RH (27%) in a heat pump dryer was evaluated and compared with those obtained from hot air drying at 45 °C. Thin-layer drying kinetics has been studied for both the conditions. To determine the kinetic parameters, the drying data were fitted to various semi-theoretical models. The goodness of fit was determined using the coefficient of determination, reduced chi square, and root mean square error. Aroma, colour, and overall acceptability determination of fresh and dried leaves were made using sensory evaluation. Drying of leaves took place mainly under the falling-rate period. The Page equation was found to be best among the proposed models to describe the thin-layer drying of Pandanus leaves with higher coefficient of determination. The effective moisture diffusivity values were also determined. The effect of low RH was prominent during the initial drying when the product was moist. The effect of temperature was prominent in the later part of drying, which acted as a driving force for moisture diffusion and hence the total drying time was reduced. Retention of aromatic compound 2-acetyl-1-pyrroline content was more in low temperature dried samples with higher sensory scores.

Effect of thinning on mixed-oak stem quality

Treesearch

David L. Sonderman; Everette D. Rast; Everette D. Rast

1988-01-01

Changes in limb-;elated stem defect were studied from 1977 to 1982 on 595 mixed-oak trees fbllowing a schedule of thinnings dating back to 1962. All of the thinnings were controlled by stocking goals rather than predetermined time intervals. Results show that heavy and moderate thinnings, as opposed to light thinnings,lhad an adverse effect on the number and size of...

Wire Detection Algorithms for Navigation

NASA Technical Reports Server (NTRS)

Kasturi, Rangachar; Camps, Octavia I.

2002-01-01

In this research we addressed the problem of obstacle detection for low altitude rotorcraft flight. In particular, the problem of detecting thin wires in the presence of image clutter and noise was studied. Wires present a serious hazard to rotorcrafts. Since they are very thin, their detection early enough so that the pilot has enough time to take evasive action is difficult, as their images can be less than one or two pixels wide. Two approaches were explored for this purpose. The first approach involved a technique for sub-pixel edge detection and subsequent post processing, in order to reduce the false alarms. After reviewing the line detection literature, an algorithm for sub-pixel edge detection proposed by Steger was identified as having good potential to solve the considered task. The algorithm was tested using a set of images synthetically generated by combining real outdoor images with computer generated wire images. The performance of the algorithm was evaluated both, at the pixel and the wire levels. It was observed that the algorithm performs well, provided that the wires are not too thin (or distant) and that some post processing is performed to remove false alarms due to clutter. The second approach involved the use of an example-based learning scheme namely, Support Vector Machines. The purpose of this approach was to explore the feasibility of an example-based learning based approach for the task of detecting wires from their images. Support Vector Machines (SVMs) have emerged as a promising pattern classification tool and have been used in various applications. It was found that this approach is not suitable for very thin wires and of course, not suitable at all for sub-pixel thick wires. High dimensionality of the data as such does not present a major problem for SVMs. However it is desirable to have a large number of training examples especially for high dimensional data. The main difficulty in using SVMs (or any other example-based learning method) is the need for a very good set of positive and negative examples since the performance depends on the quality of the training set.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eaton, Craig; Brahlek, Matthew; Engel-Herbert, Roman, E-mail: rue2@psu.edu

The authors report the growth of stoichiometric SrVO{sub 3} thin films on (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.7} (001) substrates using hybrid molecular beam epitaxy. This growth approach employs a conventional effusion cell to supply elemental A-site Sr and the metalorganic precursor vanadium oxytriisopropoxide (VTIP) to supply vanadium. Oxygen is supplied in its molecular form through a gas inlet. An optimal VTIP:Sr flux ratio has been identified using reflection high-energy electron-diffraction, x-ray diffraction, atomic force microscopy, and scanning transmission electron microscopy, demonstrating stoichiometric SrVO{sub 3} films with atomically flat surface morphology. Away from the optimal VTIP:Sr flux, characteristic changes inmore » the crystalline structure and surface morphology of the films were found, enabling identification of the type of nonstoichiometry. For optimal VTIP:Sr flux ratios, high quality SrVO{sub 3} thin films were obtained with smallest deviation of the lattice parameter from the ideal value and with atomically smooth surfaces, indicative of the good cation stoichiometry achieved by this growth technique.« less

Fabrication of superconducting MgB2 nanostructures by an electron beam lithography-based technique

NASA Astrophysics Data System (ADS)

Portesi, C.; Borini, S.; Amato, G.; Monticone, E.

2006-03-01

In this work, we present the results obtained in fabrication and characterization of magnesium diboride nanowires realized by an electron beam lithography (EBL)-based method. For fabricating MgB2 thin films, an all in situ technique has been used, based on the coevaporation of B and Mg by means of an e-gun and a resistive heater, respectively. Since the high temperatures required for the fabrication of good quality MgB2 thin films do not allow the nanostructuring approach based on the lift-off technique, we structured the samples combining EBL, optical lithography, and Ar milling. In this way, reproducible nanowires 1 μm long have been obtained. To illustrate the impact of the MgB2 film processing on its superconducting properties, we measured the temperature dependence of the resistance on a nanowire and compared it to the original magnesium diboride film. The electrical properties of the films are not degraded as a consequence of the nanostructuring process, so that superconducting nanodevices may be obtained by this method.

Influence of annealing temperature on Raman and photoluminescence spectra of electron beam evaporated TiO₂ thin films.

PubMed

Vishwas, M; Narasimha Rao, K; Chakradhar, R P S

2012-12-01

Titanium dioxide (TiO(2)) thin films were deposited on fused quartz substrates by electron beam evaporation method at room temperature. The films were annealed at different temperatures in ambient air. The surface morphology/roughness at different annealing temperatures were analyzed by atomic force microscopy (AFM). The crystallinity of the film has improved with the increase of annealing temperature. The effect of annealing temperature on optical, photoluminescence and Raman spectra of TiO(2) films were investigated. The refractive index of TiO(2) films were studied by envelope method and reflectance spectra and it is observed that the refractive index of the films was high. The photoluminescence intensity corresponding to green emission was enhanced with increase of annealing temperature. The peaks in Raman spectra depicts that the TiO(2) film is of anatase phase after annealing at 300°C and higher. The films show high refractive index, good optical quality and photoluminescence characteristics suggest that possible usage in opto-electronic and optical coating applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of thin wraparound junction silicon solar cells

NASA Technical Reports Server (NTRS)

Ho, F.; Iles, P. A.

1981-01-01

The state of the art technologies was applied to fabricate 50 micro thick 2x4 cm, coplanar back contact (CBC) solar cells with AMO efficiency above 12%. A requirement was that the cells have low solar absorptance. A wraparound junction (WAJ) with wraparound metallization was chosen. This WAJ approach avoided the need for very complex fixturing, especially during rotation of the cells for providing adequate contacts over dielectric edge layers. The contact adhesion to silicon was considered better than to an insulator. It is indicated that shunt resistance caused by poor WAJ diode quality, and series resistance from the WAJ contact, give good cell performance. The cells developed reached 14 percent AMO efficiency (at 25 C), with solar absorptance values of 0.73. Space/cell environmental tests were performed on these cells and the thin CSC cells performed well. The optimized design configuration and process sequence were used to make 50 deliverable CBC cells. These cells were all above 12 percent efficiency and had an average efficiency of -13 percent. Results of environmental tests (humidity-temperature, thermal shock, and contact adherence) are also given.

Controlled thickness and dielectric constant titanium-doped SiO2 thin films on silicon by sol gel process

NASA Astrophysics Data System (ADS)

Liu, H. L.; Wang, S. S.; Zhou, Yan; Lam, Yee Loy; Chan, Yuen Chuen; Kam, Chan Hin

1997-08-01

In this paper, we report the preparation of crack-free relatively thick SiO2-TiO2 thin films on silicon substrates using the sol-gel spin-coating method. The influence of the process parameters on the quality of the film, such as the solution condition, the spin-coating speed, the heat treatment temperature and time, have been studied. We found that the cracking of the film could be avoided by selecting the right sol composition ratios, adding PVA to the sold and properly controlling the heat treatment. Most importantly, we discovered that by polishing the edges of the film after the deposition of each single layer, the number of such layers that deposited without crack formation could be substantially increased. The refractive index profile and thickness of the film have been determined using prism coupling technique and the inverse WKB method. The refractive index was found to depend on the content of TiO2 as well as the heat treatment condition. Using an AFM, the surface morphology of the film was found to be good.

Influence of Mn concentration on magnetic topological insulator Mn xBi 2−xTe 3 thin-film Hall-effect sensor

DOE PAGES

Ni, Y.; Zhang, Z.; Nlebedim, I. C.; ...

2015-06-11

Hall-effect (HE) sensors based on high-quality Mn-doped Bi 2Te 3 topological insulator (TI) thin films have been systematically studied in this paper. Improvement of Hall sensitivity is found after doping the magnetic element Mn into Bi 2Te 3. The sensors with low Mn concentrations, Mn xBi 2-xTe 3, x = 0.01 and 0.08 show the linear behavior of Hall resistance with sensitivity about 5 Ω/T. And their Hall sensitivity shows weak dependence on temperature. For sensors with high Mn concentration (x = 0.23), the Hall resistance with respect to magnetic field shows a hysteretic behavior. Moreover, its sensitivity shows almostmore » eight times as high as that of the HE sensors with low Mn concentration. The highest sensitivity can reach 43 Ω/T at very low magnetic field. This increase of Hall sensitivity is caused by the occurrence of anomalous HE (AHE) after ferromagnetic phase transition. Our work indicates that the magnetic-element-doped TIs with AHE are good candidates for HE sensors.« less

Grain sorghum stillage recycling: Effect on ethanol yield and stillage quality.

PubMed

Egg, R P; Sweeten, J M; Coble, C G

1985-12-01

Stillage obtained from ethanol production of grain sorghum was separated into two fractions: thin stillage and wet solids. A portion of the thin stillage was recycled as cooking water in subsequent fermentation runs using both bench- and full-scale ethanol production plants. When thin stillage replaced 50-75% of the cooking water, large increases occurred in solids content, COD, and EC of the resulting thin stillage. It was found that while the volume of thin stillage requiring treatment or disposal was reduced, there was little reduction in the total pollutant load. Stillage rcycling had little effect on the quality of the stillage wet solids fraction. At the high levels of stillage recycle used, ethanol yield was reduced after three to five runs of consecutive recycling.

Investigation into the Fiber Orientation Effect on the Formability of GLARE Materials in the Stamp Forming Process

NASA Astrophysics Data System (ADS)

Liu, Shichen; Lang, Lihui; Sherkatghanad, Ehsan; Wang, Yao; Xu, Wencai

2018-04-01

Glass-reinforced aluminum laminate (GLARE) is a new class of fiber metal laminates (FMLs) which has the advantages such as high tensile strength, outstanding fatigue, impact resistance, and excellent corrosion properties. GLARE has been extensively applied in advanced aerospace and automobile industries. However, the deformation behavior of the glass fiber during forming must be studied to the benefits of the good-quality part we form. In this research, we focus on the effect of fiber layer orientation on the GLARE laminate formability in stamp forming process. Experimental and numerical analysis of stamping a hemisphere part in different fiber orientation is investigated. The results indicate that unidirectional and multi-directional fiber in the middle layer make a significant effect on the thinning and also surface forming quality of the three layer sheet. Furthermore, the stress-strain distribution of the aluminum alloy and the unique anisotropic property of the fiber layer exhibit that fiber layer orientation can also affect the forming depths as well as the fracture modes of the laminate. According to the obtained results, it is revealed that multi-directional fiber layers are a good alternative compared to the unidirectional fibers especially when a better formability is the purpose.

High temperature thermocouple and heat flux gauge using a unique thin film-hardware hot juncture

NASA Technical Reports Server (NTRS)

Liebert, C. H.; Holanda, R.; Hippensteele, S. A.; Andracchio, C. A.

1984-01-01

A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high temperature and high flux flat plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 of operation.

High-temperature thermocouple and heat flux gauge using a unique thin film-hardware hot junction

NASA Technical Reports Server (NTRS)

Liebert, C. H.; Holanda, R.; Hippensteele, S. A.; Andracchio, C. A.

1985-01-01

A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high temperature and high flux flat plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 of operation.

Novel high-energy physics studies using intense lasers and plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leemans, Wim P.; Bulanov, Stepan; Esarey, Eric

2015-06-29

In the framework of the project “Novel high-energy physics studies using intense lasers and plasmas” we conducted the study of ion acceleration and “flying mirrors” with high intensity lasers in order to develop sources of ion beams and high frequency radiation for different applications. Since some schemes of laser ion acceleration are also considered a good source of “flying mirrors”, we proposed to investigate the mechanisms of “mirror” formation. As a result we were able to study the laser ion acceleration from thin foils and near critical density targets. We identified several fundamental factors limiting the acceleration in the RPAmore » regime and proposed the target design to compensate these limitations. In the case of near critical density targets, we developed a concept for the laser driven ion source for the hadron therapy. Also we studied the mechanism of “flying mirror” generation during the intense laser interaction with thin solid density targets. As for the laser-based positron creation and capture we initially proposed to study different regimes of positron beam generation and positron beam cooling. Since the for some of these schemes a good quality electron beam is required, we studied the generation of ultra-low emittance electron beams. In order to understand the fundamental physics of high energy electron beam interaction with high intensity laser pulses, which may affect the efficient generation of positron beams, we studied the radiation reaction effects.« less

Conjugated foldamers with unusually high space-charge-limited current hole mobilities.

PubMed

Li, Yong; Dutta, Tanmoy; Gerasimchuk, Nikolay; Wu, Shijie; Shetye, Kuldeep; Jin, Lu; Wang, Ruixin; Zhu, Da-Ming; Peng, Zhonghua

2015-05-13

Charge carrier mobility and its optimization play a critical role in the development of cutting-edge organic electronic and optoelectronic devices. Even though space-charge-limited current (SCLC) hole mobilities as high as 1.4 cm(2) V(-1) s(-1) have been reported for microscopically sized highly ordered liquid-crystalline conjugated small molecules, the SCLC hole mobility of device-sized thin films of conjugated polymers is still much lower, ranging from 10(-6) to 10(-3) cm(2) V(-1) s(-1). Herein, we report the synthesis, characterizations, and thin-film SCLC mobility of three discotic conjugated polymers, INDT-TT, INDT-BT, and INDT-NDT. Optical studies indicate that polymer INDT-NDT adopts a folded conformation in solutions of good or poor solvents, whereas polymer INDT-TT stays as random monomeric chains in good solvents and interchain aggregates in poor solvents. INDT-BT polymer chains, however, stay as foldamers in dilute solutions of good solvents but interchain aggregates in concentrated solutions or poor solvents. Circular dichroism spectroscopy provides clear evidence for the helical folding of INDT-NDT in solutions. Thin films spin-coated from 1,2-dichlorobenzene solutions of the polymers show SCLC hole mobility of 2.20 × 10(-6), 8.79 × 10(-5), and 2.77 × 10(-2) cm(2) V(-1) s(-1) for INDT-TT, INDT-BT, and INDT-NDT, respectively. HRTEM and powder XRD measurements show that INDT-NDT pristine thin films contain nanocrystalline domains, whereas the INDT-TT and INDT-BT films are amorphous. Thin films of INDT-NDT:PC71BM blends show increased crystallinity and further improved SCLC hole mobility up to 1.29 × 10(-1) cm(2) V(-1) s(-1), one of the highest SCLC mobility values ever recorded on solution-processed organic semiconducting thin films. The persistent folding conformation of INDT-NDT is believed to be responsible for the high crystallinity of its thin films and its high SCLC mobilities.

Separation of pigment formulations by high-performance thin-layer chromatography with automated multiple development.

PubMed

Stiefel, Constanze; Dietzel, Sylvia; Endress, Marc; Morlock, Gertrud E

2016-09-02

Food packaging is designed to provide sufficient protection for the respective filling, legally binding information for the consumers like nutritional facts or filling information, and an attractive appearance to promote the sale. For quality and safety of the package, a regular quality control of the used printing materials is necessary to get consistently good print results, to avoid migration of undesired ink components into the food and to identify potentially faulty ink batches. Analytical approaches, however, have hardly been considered for quality assurance so far due to the lack of robust, suitable methods for the analysis of rarely soluble pigment formulations. Thus, a simple and generic high-performance thin-layer chromatography (HPTLC) method for the separation of different colored pigment formulations was developed on HPTLC plates silica gel 60 by automated multiple development. The gradient system provided a sharp resolution for differently soluble pigment constituents like additives and coating materials. The results of multi-detection allowed a first assignment of the differently detectable bands to particular chemical substance classes (e.g., lipophilic components), enabled the comparison of different commercially available pigment batches and revealed substantial variations in the composition of the batches. Hyphenation of HPTLC with high resolution mass spectrometry and infrared spectroscopy allowed the characterization of single unknown pigment constituents, which may partly be responsible for known quality problems during printing. The newly developed, precise and selective HPTLC method can be used as part of routine quality control for both, incoming pigment batches and monitoring of internal pigment production processes, to secure a consistent pigment composition resulting in consistent ink quality, a faultless print image and safe products. Hyphenation of HPTLC with the A. fischeri bioassay gave first information on the bioactivity or rather on the toxicological potential of different compounds of the pigment formulations. The results of the bioassay might be helpful to choose pigment compositions that provide both, a high printing quality but at the same time guarantee a high consumer safety, especially in regard to smaller pigment components, which tend to migrate through the packaging. Copyright © 2016 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gelinck, G. H., E-mail: Gerwin.Gelinck@tno.nl; Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven; Breemen, A. J. J. M. van

Ferroelectric polarization switching of poly(vinylidene difluoride-trifluoroethylene) is investigated in different thin-film device structures, ranging from simple capacitors to dual-gate thin-film transistors (TFT). Indium gallium zinc oxide, a high mobility amorphous oxide material, is used as semiconductor. We find that the ferroelectric can be polarized in both directions in the metal-ferroelectric-semiconductor (MFS) structure and in the dual-gate TFT under certain biasing conditions, but not in the single-gate thin-film transistors. These results disprove the common belief that MFS structures serve as a good model system for ferroelectric polarization switching in thin-film transistors.

Magnetic field dependence of the internal quality factor and noise performance of lumped-element kinetic inductance detectors

NASA Astrophysics Data System (ADS)

Flanigan, D.; Johnson, B. R.; Abitbol, M. H.; Bryan, S.; Cantor, R.; Day, P.; Jones, G.; Mauskopf, P.; McCarrick, H.; Miller, A.; Zmuidzinas, J.

2016-10-01

We present a technique for increasing the internal quality factor of kinetic inductance detectors (KIDs) by nulling ambient magnetic fields with a properly applied magnetic field. The KIDs used in this study are made from thin-film aluminum, they are mounted inside a light-tight package made from bulk aluminum, and they are operated near 150 mK. Since the thin-film aluminum has a slightly elevated critical temperature (Tc = 1.4 K), it therefore transitions before the package (Tc = 1.2 K), which also serves as a magnetic shield. On cooldown, ambient magnetic fields as small as approximately 30 µT can produce vortices in the thin-film aluminum as it transitions because the bulk aluminum package has not yet transitioned and therefore is not yet shielding. These vortices become trapped inside the aluminum package below 1.2 K and ultimately produce low internal quality factors in the thin-film superconducting resonators. We show that by controlling the strength of the magnetic field present when the thin film transitions, we can control the internal quality factor of the resonators. We also compare the noise performance with and without vortices present, and find no evidence for excess noise beyond the increase in amplifier noise, which is expected with increasing loss.

Hall effect measurements of high-quality M n3CuN thin films and the electronic structure

NASA Astrophysics Data System (ADS)

Matsumoto, Toshiki; Hatano, Takafumi; Urata, Takahiro; Iida, Kazumasa; Takenaka, Koshi; Ikuta, Hiroshi

2017-11-01

The physical properties of M n3CuN were studied using thin films. We found that an annealing process was very effective to improve the film quality, the key of which was the use of Ti that prevented the formation of oxide impurities. Using these high-quality thin films, we found strong strain dependence for the ferromagnetic transition temperature (TC) and a sign change of the Hall coefficient at TC. The analysis of Hall coefficient data revealed a sizable decrease of hole concentration and a large increase of electron mobility below TC, which is discussed in relation to the electronic structure of this material.

QUALITY ASSURANCE STUDY OF MARINE LIPID CLASS DETERMINATION USING CHROMAROD/IATROSCAN( REG. TRADEMARK) THIN-LAYER CHROMATOGRAPHY-FLAME IONIZATION DETECTOR

EPA Science Inventory

An Iatroscan thin-layer chromatorgraphy-flame ionization detector has been utilized to quantify lipid classes in marine samples. This method was evaluated relative to established quality assurance (QA) procedures used for the gas chromatographic analysis of PCBs. A method for ext...

Design and performance evaluation of very thin overlays in Texas.

DOT National Transportation Integrated Search

2009-06-01

Very thin overlays 1-inch thick or less were placed as surface layers on five major highways in Texas. : These mixes were designed in the laboratory to have a balance of good rut resistance as measured by : TxDOTs Hamburg Wheel Tracking test and g...

Third-Year Growth and Bole Quality Responses to Thinning in a Red Oak-Sweetgum Stand on a Minor Streambottom Site in West-Central Alabama

Treesearch

James S. Meadows; J.C.G. Goelz

1999-01-01

Four thinning treatments were applied to a red oak-sweetgum (Quercus spp.-Liquidambar styraciflua L.) stand on a minor streambottom site in west-central Alabama in 1994: (1) unthinned control; (2) light thinning to 70-75 percent residual stocking; (3) heavy thinning to 50-55 percent residual stocking; and (4) B-line thinning to...

Micro pulling down growth of very thin shape memory alloys single crystals

NASA Astrophysics Data System (ADS)

López-Ferreño, I.; Juan, J. San; Breczewski, T.; López, G. A.; Nó, M. L.

Shape memory alloys (SMAs) have attracted much attention in the last decades due to their thermo-mechanical properties such as superelasticity and shape memory effect. Among the different families of SMAs, Cu-Al-Ni alloys exhibit these properties in a wide range of temperatures including the temperature range of 100-200∘C, where there is a technological demand of these functional materials, and exhibit excellent behavior at small scale making them more competitive for applications in Micro Electro-Mechanical Systems (MEMS). However, polycrystalline alloys of Cu-based SMAs are very brittle so that they show their best thermo-mechanical properties in single-crystal state. Nowadays, conventional Bridgman and Czochralski methods are being applied to elaborate single-crystal rods up to a minimum diameter of 1mm, but no works have been reported for smaller diameters. With the aim of synthesizing very thin single-crystals, the Micro-Pulling Down (μ-PD) technique has been applied, for which the capillarity and surface tension between crucible and the melt play a critical role. The μ-PD method has been successfully applied to elaborate several cylindrical shape thin single-crystals down to 200μm in diameter. Finally, the martensitic transformation, which is responsible for the shape memory properties of these alloys, has been characterized for different single-crystals. The experimental results evidence the good quality of the grown single-crystals.

Evaluation of the structural, optical and electrical properties of AZO thin films prepared by chemical bath deposition for optoelectronics

NASA Astrophysics Data System (ADS)

Kumar, K. Deva Arun; Valanarasu, S.; Rosario, S. Rex; Ganesh, V.; Shkir, Mohd.; Sreelatha, C. J.; AlFaify, S.

2018-04-01

Aluminum doped zinc oxide (AZO) thin films for electrode applications were deposited on glass substrates using chemical bath deposition (CBD) method. The influence of deposition time on the structural, morphological, and opto-electrical properties of AZO films were investigated. Structural studies confirmed that all the deposited films were hexagonal wurtzite structure with polycrystalline nature and exhibited (002) preferential orientation. There is no other impurity phases were detected for different deposition time. Surface morphological images shows the spherically shaped grains are uniformly arranged on to the entire film surface. The EDS spectrum confirms the presence of Zn, O and Al elements in deposited AZO film. The observed optical transmittance is high (87%) in the visible region, and the calculated band gap value is 3.27 eV. In this study, the transmittance value is decreased with increasing deposition time. The room temperature PL spectrum exposed that AZO thin film deposited at (60 min) has good optical quality with less defect density. The minimum electrical resistivity and maximum carrier concentration values were observed as 8.53 × 10-3(Ω cm) and 3.53 × 1018 cm-3 for 60 min deposited film, respectively. The obtained figure of merit (ϕ) value 3.05 × 10-3(Ω/sq)- 1 is suggested for an optoelectronic device.

Transnasal endoscopy: Technical considerations, advantages and limitations.

PubMed

Atar, Mustafa; Kadayifci, Abdurrahman

2014-02-16

Transnasal endoscopy (TNE) is an upper endoscopy method which is performed by the nasal route using a thin endoscope less than 6 mm in diameter. The primary goal of this method is to improve patient tolerance and convenience of the procedure. TNE can be performed without sedation and thus eliminates the risks associated with general anesthesia. In this way, TNE decreases the cost and total duration of endoscopic procedures, while maintaining the image quality of standard caliber endoscopes, providing good results for diagnostic purposes. However, the small working channel of the ultra-thin endoscope used for TNE makes it difficult to use for therapeutic procedures except in certain conditions which require a thinner endoscope. Biopsy is possible with special forceps less than 2 mm in diameter. Recently, TNE has been used for screening endoscopy in Far East Asia, including Japan. In most controlled studies, TNE was found to have better patient tolerance when compared to unsedated endoscopy. Nasal pain is the most significant symptom associated with endoscopic procedures but can be reduced with nasal pretreatment. Despite the potential advantage of TNE, it is not common in Western countries, usually due to a lack of training in the technique and a lack of awareness of its potential advantages. This paper briefly reviews the technical considerations as well as the potential advantages and limitations of TNE with ultra-thin scopes.

Transnasal endoscopy: Technical considerations, advantages and limitations

PubMed Central

Atar, Mustafa; Kadayifci, Abdurrahman

2014-01-01

Transnasal endoscopy (TNE) is an upper endoscopy method which is performed by the nasal route using a thin endoscope less than 6 mm in diameter. The primary goal of this method is to improve patient tolerance and convenience of the procedure. TNE can be performed without sedation and thus eliminates the risks associated with general anesthesia. In this way, TNE decreases the cost and total duration of endoscopic procedures, while maintaining the image quality of standard caliber endoscopes, providing good results for diagnostic purposes. However, the small working channel of the ultra-thin endoscope used for TNE makes it difficult to use for therapeutic procedures except in certain conditions which require a thinner endoscope. Biopsy is possible with special forceps less than 2 mm in diameter. Recently, TNE has been used for screening endoscopy in Far East Asia, including Japan. In most controlled studies, TNE was found to have better patient tolerance when compared to unsedated endoscopy. Nasal pain is the most significant symptom associated with endoscopic procedures but can be reduced with nasal pretreatment. Despite the potential advantage of TNE, it is not common in Western countries, usually due to a lack of training in the technique and a lack of awareness of its potential advantages. This paper briefly reviews the technical considerations as well as the potential advantages and limitations of TNE with ultra-thin scopes. PMID:24567791

A tutorial solution to scattering of radiation in a thin atmosphere bounded below by a diffusely reflecting, absorbing surface

NASA Technical Reports Server (NTRS)

Buglia, J. J.

1982-01-01

A simple tutorial method, based on a photon tracking procedure, is described to determine the spherical albedo for a thin atmosphere overlying a reflecting surface. This procedure is used to provide a physical structure with which to interpret the more detailed but highly mathematical analyses presented. The final equations are shown to be in good numerical agreement with more exact solutions for thin atmospheres.

Electrochemically synthesized nanocrystalline spinel thin film for high performance supercapacitor

NASA Astrophysics Data System (ADS)

Gupta, Vinay; Gupta, Shubhra; Miura, Norio

Spinels are not known for their supercapacitive nature. Here, we have explored electrochemically synthesized nanostructured NiCo 2O 4 spinel thin-film electrode for electrochemical supercapacitors. The nanostructured NiCo 2O 4 spinel thin film exhibited a high specific capacitance value of 580 F g -1 and an energy density of 32 Wh kg -1 at the power density of 4 kW kg -1, accompanying with good cyclic stability.

Thin-film Rechargeable Lithium Batteries

DOE R&D Accomplishments Database

Dudney, N. J.; Bates, J. B.; Lubben, D.

1995-06-01

Thin film rechargeable lithium batteries using ceramic electrolyte and cathode materials have been fabricated by physical deposition techniques. The lithium phosphorous oxynitride electrolyte has exceptional electrochemical stability and a good lithium conductivity. The lithium insertion reaction of several different intercalation materials, amorphous V{sub 2}O{sub 5}, amorphous LiMn{sub 2}O{sub 4}, and crystalline LiMn{sub 2}O{sub 4} films, have been investigated using the completed cathode/electrolyte/lithium thin film battery.

Effect of cluster thinning and prohexadione calcium applications on phenolic composition and sensory properties of red wines.

PubMed

Avizcuri-Inac, José-Miguel; Gonzalo-Diago, Ana; Sanz-Asensio, Jesús; Martínez-Soria, María-Teresa; López-Alonso, Miguel; Dizy-Soto, Marta; Echávarri-Granado, José-Federico; Vaquero-Fernández, Luis; Fernández-Zurbano, Purificación

2013-02-06

The overall objective of this study was to investigate the effect of manual cluster thinning (CT) and the application of the growth regulator Prohexadione calcium (ProCa) on the phenolic composition and the sensory profile of Tempranillo and Grenache wines produced from treated vines in La Rioja (Spain). ProCa was applied at preblooming and CT was carried out at veraison in two consecutive years. Different physicochemical parameters and analyses of phenolic compounds were carried out in control, CT and ProCa grapes and wines and wine sensory was performed. Thinning treatments decreased crop yield, besides ProCa application reduced berry size, and berry weight. Color and phenolic composition of Grenache and Tempranillo wines in general were affected by thinning treatments, with an increase in anthocyanin, flavanol and flavonol concentrations. In sensory analysis, wines obtained from thinned vines presented higher values for several aromatic (e.g., white and yellow fruits, fresh flowers) and taste attributes (i.e., astringency, bitternes, persistence). CT and ProCa treatments resulted in an improvement in wine quality. In general, similar results in phenolic composition, sensory properties and quality of wines were obtained by manual and chemical cluster thinning. ProCa as a growth regulator may be an option for a quality vitiviniculture.

Randomized Trial Comparing Amniotic Membrane Transplantation with Lamellar Corneal Graft for the Treatment of Corneal Thinning.

PubMed

de Farias, Charles C; Allemann, Norma; Gomes, José Á P

2016-04-01

There are few studies comparing different surgical procedures for the treatment of corneal thinning. Lamellar corneal transplantation (LCT) has been reported to be efficient, but its results can be jeopardized by allograft rejection, opacification, or high astigmatism. Amniotic membrane transplantation (AMT) has been considered a good alternative, but it is not as resistant as LCT and the tissue can be reabsorbed after surgery. A prospective, randomized, interventional, and comparative study of consecutive patients with corneal thinning over 6 months was performed. Ophthalmological examination was performed before transplant surgery and then repeated 1, 7, 15, 30, 90, and 180 days after surgery and ultrasound biomicroscopy was performed before and then 30, 90, and 180 days after surgery to assess corneal thinning. Herpes simplex infection was the main cause of corneal thinning (9 eyes), followed by surgery (cataract, glaucoma, 5 cases), rheumatoid arthritis (1), chemical burn (1), perforating trauma (1), previous band keratopathy treatment (1), and Stevens-Johnson syndrome (1). Although all patients showed significant increase in final thickness in the area of thinning, it was higher in those submitted to LCT at 180 days postoperatively. Regardless of the surgical technique, all patients showed epithelialization. Patients undergoing AMT showed an 89% decrease in neovascularization. Final corrected distance visual acuity was better in patients submitted to AMT. LCT proved to be the best option for treating corneal thinning. AMT represents an alternative that allows good visual recovery but does not restore corneal thickness as efficiently as LCT.

State-of-the-art pancreatic MRI.

PubMed

Sandrasegaran, Kumaresan; Lin, Chen; Akisik, Fatih M; Tann, Mark

2010-07-01

The purpose of this article is to discuss the most current techniques used for pancreatic imaging, highlighting the advantages and disadvantages of state-of-the-art and emerging pulse sequences and their application to pancreatic disease. Given the technologic advances of the past decade, pancreatic MRI protocols have evolved. Most sequences can now be performed in one or a few breath-holds; 3D sequences with thin, contiguous slices offer improved spatial resolution; and better fat and motion suppression allow improved contrast resolution and image quality. The diagnostic potential of MRCP is now almost as good as ERCP, with pancreatic MRI as the main imaging technique to investigate biliopancreatic pain, chronic pancreatitis, and cystic pancreatic tumors at many institutions. In addition, functional information is provided with secretin-enhanced MRCP.

Tungsten-encapsulated gadolinium nanoislands with enhanced magnetocaloric response

DOE PAGES

Logan, Jonathan M.; Rosenmann, Daniel; Sangpo, Tenzin; ...

2017-07-03

Here, we report a method for growing chemically pure, oxide-free, air-stable Gd nanoislands with enhanced magnetic properties. These nanoislands are grown by solid-state dewetting and are fully encapsulated in tungsten such that they remain stable in ambient environments. They display good crystalline properties with hexagonally close-packed crystal structure and strong preferential orientation. We show that the choice of substrate strongly affects their shape, crystal orientation, and magnetic properties. The temperature-dependent magnetic coercivity and remanence of the Gd islands can vary by as much as a factor of three depending on the substrate used. The magneto- caloric properties of Gd islandsmore » grown on a sapphire substrate exceed those of high-quality Gd thin films.« less

Electrospun bismuth ferrite nanofibers for potential applications in ferroelectric photovoltaic devices.

PubMed

Fei, Linfeng; Hu, Yongming; Li, Xing; Song, Ruobing; Sun, Li; Huang, Haitao; Gu, Haoshuang; Chan, Helen L W; Wang, Yu

2015-02-18

Bismuth ferrite (BFO) nanofibers were synthesized via a sol-gel-based electrospinning process followed by thermal treatment. The influences of processing conditions on the final structure of the samples were investigated. Nanofibers prepared under optimized conditions were found to have a perovskite structure with good quality of crystallization and free of impurity phase. Ferroelectric and piezoelectric responses were obtained from individual nanofiber measured on a piezoelectric force microscope. A prototype photovoltaic device using laterally aligned BFO nanofibers and interdigital electrodes was developed and its performance was examined on a standard photovoltaic system. The BFO nanofibers were found to exhibit an excellent ferroelectric photovoltaic property with the photocurrent several times larger than the literature data obtained on BFO thin films.

Stress polishing of thin shells for adaptive secondary mirrors. Application to the Very Large Telescope deformable secondary

NASA Astrophysics Data System (ADS)

Hugot, E.; Ferrari, M.; Riccardi, A.; Xompero, M.; Lemaître, G. R.; Arsenault, R.; Hubin, N.

2011-03-01

Context. Adaptive secondary mirrors (ASM) are, or will be, key components on all modern telescopes, providing improved seeing conditions or diffraction limited images, thanks to the high-order atmospheric turbulence correction obtained by controlling the shape of a thin mirror. Their development is a key milestone towards future extremely large telescopes (ELT) where this technology is mandatory for successful observations. Aims: The key point of actual adaptive secondaries technology is the thin glass mirror that acts as a deformable membrane, often aspheric. On 6 m - 8 m class telescopes, these are typically 1 m-class with a 2 mm thickness. The optical quality of this shell must be sufficiently good not to degrade the correction, meaning that high spatial frequency errors must be avoided. The innovative method presented here aims at generating aspherical shapes by elastic bending to reach high optical qualities. Methods: This method is called stress polishing and allows generating aspherical optics of a large amplitude with a simple spherical polishing with a full sized lap applied on a warped blank. The main advantage of this technique is the smooth optical quality obtained, free of high spatial frequency ripples as they are classically caused by subaperture toolmarks. After describing the manufacturing process we developed, our analytical calculations lead to a preliminary definition of the geometry of the blank, which allows a precise bending of the substrate. The finite element analysis (FEA) can be performed to refine this geometry by using an iterative method with a criterion based on the power spectral density of the displacement map of the optical surface. Results: Considering the specific case of the Very Large Telescope (VLT) deformable secondary mirror (DSM), extensive FEA were performed for the optimisation of the geometry. Results are showing that the warping will not introduce surface errors higher than 0.3 nm rms on the minimal spatial scale considered on the mirror. Simulations of the flattening operation of the shell also demonstrate that the actuators system is able to correct manufacturing surface errors coming from the warping of the blank with a residual error lower than 8 nm rms.

Silvicultural aspects intermediate cuttings

Treesearch

Kenneth L. Carvell

1971-01-01

Correct timing of the first thinning in mixed oak stands depends largely on the composition and condition of the stands and on available markets for small wood products. Delaying first thinnings in high-quality seedling-origin stands until a long, straight, clear bole has developed is of primary importance in assuring high quality of the final crop trees. However, many...

Synthesis and performance of Zn-Ni-P thin films

NASA Astrophysics Data System (ADS)

Soare, V.; Burada, M.; Constantin, I.; Ghita, M.; Constantin, V.; Miculescu, F.; Popescu, A. M.

2015-03-01

The electroplating of Zn-Ni-P thin film alloys from a sulfate bath containing phosphoric and phosphorous acid was investigated. The bath composition and the deposition parameters were optimized through Hull cell experiments, and the optimum experimental conditions were determined (pH = 2, temperature = 298-313 K, zinc sulfate concentration = 30 g·L-1, EDTA concentration = 15 g·L-1, and current density, = ,1.0-2.0 A·dm-2). The SEM analysis of the coating deposited from the optimum bath revealed fine-grained deposits of the alloy in the presence of EDTA. Optical microscopy analysis indicated an electrodeposited thin film with uniform thickness and good adhesion to the steel substrate. The good adherence of the coatings was also demonstrated by the scratch tests that were performed, with a maximum determined value of 25 N for the critical load. Corrosion resistance tests revealed good protection of the steel substrate by the obtained Zn-Ni-P coatings, with values up to 85.89% for samples with Ni contents higher than 76%. The surface analysis of the thin film samples before and after corrosion was performed by X-ray photoelectron spectroscopy (XPS). Project support by the Partnership Romanian Research Program (PNCDI2), CORZIFILM Project nr.72-221/2008-2011 and “EU (ERDF) and Romanian Government” that allowed for acquisition of the research infrastructure under POS-CEEO 2.2.1 project INFRANANOCHEM-Nr.19/01.03.2009.

Flexible Solar Cells

NASA Technical Reports Server (NTRS)

1994-01-01

Solar cell "modules" are plastic strips coated with thin films of photovoltaic silicon that collect solar energy for instant conversion into electricity. Lasers divide the thin film coating into smaller cells to build up voltage. Developed by Iowa Thin Film Technologies under NASA and DOE grants, the modules are used as electrical supply for advertising displays, battery rechargers for recreational vehicles, and to power model airplanes. The company is planning other applications both in consumer goods and as a power source in underdeveloped countries.

Thin-slice vision: inference of confidence measure from perceptual video quality

NASA Astrophysics Data System (ADS)

Hameed, Abdul; Balas, Benjamin; Dai, Rui

2016-11-01

There has been considerable research on thin-slice judgments, but no study has demonstrated the predictive validity of confidence measures when assessors watch videos acquired from communication systems, in which the perceptual quality of videos could be degraded by limited bandwidth and unreliable network conditions. This paper studies the relationship between high-level thin-slice judgments of human behavior and factors that contribute to perceptual video quality. Based on a large number of subjective test results, it has been found that the confidence of a single individual present in all the videos, called speaker's confidence (SC), could be predicted by a list of features that contribute to perceptual video quality. Two prediction models, one based on artificial neural network and the other based on a decision tree, were built to predict SC. Experimental results have shown that both prediction models can result in high correlation measures.

Elaboration and properties of hierarchically structured optical thin films of MIL-101(Cr).

PubMed

Demessence, Aude; Horcajada, Patricia; Serre, Christian; Boissière, Cédric; Grosso, David; Sanchez, Clément; Férey, Gérard

2009-12-14

Stable nanoparticles dispersions of the porous hybrid MIL-101(Cr) allow dip-coating of high quality optical thin films with dual hierarchical porous structure. Moreover, for the first time, mechanical and sorption properties of mesoporous MOFs based thin films are evaluated.

Chemical bath deposited (CBD) CuO thin films on n-silicon substrate for electronic and optical applications: Impact of growth time

NASA Astrophysics Data System (ADS)

Sultana, Jenifar; Paul, Somdatta; Karmakar, Anupam; Yi, Ren; Dalapati, Goutam Kumar; Chattopadhyay, Sanatan

2017-10-01

Thin film of p-type cupric oxide (p-CuO) is grown on silicon (n-Si) substrate by using chemical bath deposition (CBD) technique and a precise control of thickness from 60 nm to 178 nm has been achieved. The structural properties and stoichiometric composition of the grown films are observed to depend significantly on the growth time. The chemical composition, optical properties, and structural quality are investigated in detail by employing XRD, ellipsometric measurements and SEM images. Also, the elemental composition and the oxidation states of Cu and O in the grown samples have been studied in detail by XPS measurements. Thin film of 110 nm thicknesses exhibited the best performance in terms of crystal quality, refractive index, dielectric constant, band-gap, and optical properties. The study suggests synthesis route for developing high quality CuO thin film using CBD method for electronic and optical applications.

Multi-objective optimization of laser-scribed micro grooves on AZO conductive thin film using Data Envelopment Analysis

NASA Astrophysics Data System (ADS)

Kuo, Chung-Feng Jeffrey; Quang Vu, Huy; Gunawan, Dewantoro; Lan, Wei-Luen

2012-09-01

Laser scribing process has been considered as an effective approach for surface texturization on thin film solar cell. In this study, a systematic method for optimizing multi-objective process parameters of fiber laser system was proposed to achieve excellent quality characteristics, such as the minimum scribing line width, the flattest trough bottom, and the least processing edge surface bumps for increasing incident light absorption of thin film solar cell. First, the Taguchi method (TM) obtained useful statistical information through the orthogonal array with relatively fewer experiments. However, TM is only appropriate to optimize single-objective problems and has to rely on engineering judgment for solving multi-objective problems that can cause uncertainty to some degree. The back-propagation neural network (BPNN) and data envelopment analysis (DEA) were utilized to estimate the incomplete data and derive the optimal process parameters of laser scribing system. In addition, analysis of variance (ANOVA) method was also applied to identify the significant factors which have the greatest effects on the quality of scribing process; in other words, by putting more emphasis on these controllable and profound factors, the quality characteristics of the scribed thin film could be effectively enhanced. The experiments were carried out on ZnO:Al (AZO) transparent conductive thin film with a thickness of 500 nm and the results proved that the proposed approach yields better anticipated improvements than that of the TM which is only superior in improving one quality while sacrificing the other qualities. The results of confirmation experiments have showed the reliability of the proposed method.

Preparation of nickel oxide thin films at different annealing temperature by sol-gel spin coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdullah, M. A. R., E-mail: ameerridhwan89@gmail.com; Mamat, M. H., E-mail: hafiz-030@yahoo.com; Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com

2016-07-06

Preparation of NiO thin films at different annealing temperature by sol-gel method was conducted to synthesize the quality of the surface thin films. The effects of annealing temperature on the surface topology were systematically investigated. Our studies confirmed that the surface roughness of the thin films was increased whenever annealing temperature was increase. NiO thin films morphology structure analysis was confirmed by field emission scanning electron microscope. Surface roughness of the thin films was investigated by atomic force microscopy.

Electrical Nanocontact Between Bismuth Nanowire Edges and Electrodes

NASA Astrophysics Data System (ADS)

Murata, Masayuki; Nakamura, Daiki; Hasegawa, Yasuhiro; Komine, Takashi; Uematsu, Daisuke; Nakamura, Shinichiro; Taguchi, Takashi

2010-09-01

Three methods for attaching electrodes to a bismuth nanowire sample were investigated. In the first and second methods, thin layers of titanium and copper were deposited by ion plating under vacuum onto the edge surface of individual bismuth nanowire samples that were encapsulated in a quartz template. Good electrical contact between the electrodes and the nanowire was achieved using silver epoxy and conventional solder on the thin-film layers in the first and second methods, respectively. In the third method, a low-melting-point solder was utilized and was also successful in achieving good electrical contact in air atmosphere. The connection methods showed no difference in terms of resistivity temperature dependence or Seebeck coefficient. The third method has an advantage in that nanocontact is easily achieved; however, diffusion of the solder into the nanowire allows contamination near the melting point of the solder. In the first and second methods, the thin-film layer enabled electrical contact to be more safely achieved than the direct contact used in the third method, because the thin-film layer prevented diffusion of binder components.

Thinning and site quality influence aboveground tree carbon stocks in yellow-poplar forests of the southern Appalachians.

Treesearch

Tara Keyser

2010-01-01

Little information exists regarding the effects of intermediate stand management activities (e.g., thinning) on C storage. This lack of information has created uncertainty regarding trade-offs between the benefits observed following thinning and C storage. Using long-term growth data, this study examines the effect of thinning on C storage while controlling for the...

Third-year growth and bole-quality responses to thinning in a late-rotation red oak-sweetgum stand in East Texas

Treesearch

James S. Meadows; Daniel A. Skojac

2006-01-01

Three thinning treatments were applied to an 80- to 90-year-old stand dominated by red oaks (Quercus spp.) and sweetgum (Liquidambar styraciflua L.) along the Neches River in East Texas: (1) unthinned control, (2) light thinning (70 to 75 percent residual stocking), and (3) heavy thinning (50 to 55 percent residual stocking). Three...

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, III, Jerome J.; Halpern, Bret L.

1993-01-01

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures.

Multiphonon Raman scattering and photoluminescence studies of CdS nanocrystals grown by thermal evaporation

NASA Astrophysics Data System (ADS)

Farid, Sidra; Stroscio, Michael A.; Dutta, Mitra

2018-03-01

Thermal evaporation growth technique is presented as a route to grow cost effective high quality CdS thin films. We have successfully grown high quality CdS thin films on ITO coated glass substrates by thermal evaporation technique and analyzed the effects of annealing and excitation dependent input of CdS thin film using Raman and photoluminescence spectroscopy. LO phonon modes have been analyzed quantitatively considering the contributions due to anneal induced effects on film quality using phonon spatial correlation model, line shape and defect state analysis. Asymmetry in the Raman line shape towards the low frequency side is related to the phonon confinement effects and is modeled by spatial correlation model. Calculations of width (FWHM), integrated intensity, and line shape for the longitudinal (LO) optical phonon modes indicate improved crystalline quality for the annealed films as compared to the as grown films. With increase in laser power, intensity ratio of 2-LO to 1-LO optical phonon modes is found to increase while multiple overtones upto fourth order are observed. Power dependent photoluminescence data indicates direct band-to-band transition in CdS thin films.

Thermoelectric properties of epitaxial β-FeSi2 thin films grown on Si(111) substrates with various film qualities

NASA Astrophysics Data System (ADS)

Watanabe, Kentaro; Taniguchi, Tatsuhiko; Sakane, Shunya; Aoki, Shunsuke; Suzuki, Takeyuki; Fujita, Takeshi; Nakamura, Yoshiaki

2017-05-01

Si-based epitaxial β-FeSi2 thin films are attractive as materials for on-chip thermoelectric power generators. We investigated the structure, crystallinity, and thermoelectric properties of β-FeSi2 thin films epitaxially grown on Si(111) substrates by using three different techniques: conventional reactive deposition epitaxy followed by molecular beam epitaxy (RDE+MBE), solid phase epitaxy (SPE) based on codeposition of Fe and Si presented previously, and SPE followed by MBE (SPE+MBE) presented newly by this work. Their epitaxial growth temperatures were fixed at 530 °C for comparison. RDE+MBE thin films exhibited high crystalline quality, but rough surfaces and rugged β-FeSi2/Si(111) interfaces. On the other hand, SPE thin films showed flat surfaces and abrupt β-FeSi2/Si(111) interfaces but low crystallinity. We found that SPE+MBE thin films realized crystallinity higher than SPE thin films, and also had flatter surfaces and sharper interfaces than RDE+MBE thin films. In SPE+MBE thin film growth, due to the initial SPE process with low temperature codeposition, thermal interdiffusion of Fe and Si was suppressed, resulting in the surface flatness and abrupt interface. Second high temperature MBE process improved the crystallinity. We also investigated thermoelectric properties of these β-FeSi2 thin films. Structural factors affecting the thermoelectric properties of RDE+MBE, SPE, and SPE+MBE thin films were investigated.

Cognitive Distortions Associated with Imagination of the Thin Ideal: Validation of the Thought-Shape Fusion Body Questionnaire (TSF-B)

PubMed Central

Wyssen, Andrea; Debbeler, Luka J.; Meyer, Andrea H.; Coelho, Jennifer S.; Humbel, Nadine; Schuck, Kathrin; Lennertz, Julia; Messerli-Bürgy, Nadine; Biedert, Esther; Trier, Stephan N.; Isenschmid, Bettina; Milos, Gabriella; Whinyates, Katherina; Schneider, Silvia; Munsch, Simone

2017-01-01

Thought-shape fusion (TSF) describes the experience of body-related cognitive distortions associated with eating disorder (ED) pathology. In the laboratory TSF has been activated by thoughts about fattening/forbidden foods and thin ideals. This study aims at validating a questionnaire to assess the trait susceptibility to TSF (i.e., body-related cognitive distortions) associated with the imagination of thin ideals, and developing an adapted version of the original TSF trait questionnaire, the Thought-Shape Fusion Body Questionnaire (TSF-B). Healthy control women (HC, n = 317) and women diagnosed with subthreshold and clinical EDs (n = 243) completed an online-questionnaire. The factor structure of the TSF-B questionnaire was examined using exploratory (EFA) and subsequent confirmatory factor analysis (CFA). EFA pointed to a two-factor solution, confirmed by CFA. Subscale 1 was named Imagination of thin ideals, containing five items referring to the imagination of female thin ideals. Subscale 2 was named Striving for own thin ideal, with seven items about pursuing/abandoning attempts to reach one’s own thin ideal. The total scale and both subscales showed good convergent validity, excellent reliability, and good ability to discriminate between individuals with subthreshold/clinical EDs and HCs. Results indicate that cognitive distortions are also related to the imagination of thin ideals, and are associated with ED pathology. With two subscales, the TSF-B trait questionnaire appropriately measures this construct. Future studies should clarify whether TSF-B is predictive for the development and course of EDs. Assessing cognitive distortions with the TSF-B questionnaire could improve understanding of EDs and stimulate the development of cognitively oriented interventions. Clinical Trial Registration Number: DRKS-ID: DRKS00005709. PMID:29312059

Thin film concentrator panel development

NASA Technical Reports Server (NTRS)

Zimmerman, D. K.

1982-01-01

The development and testing of a rigid panel concept that utilizes a thin film reflective surface for application to a low-cost point-focusing solar concentrator is discussed. It is shown that a thin film reflective surface is acceptable for use on solar concentrators, including 1500 F applications. Additionally, it is shown that a formed steel sheet substrate is a good choice for concentrator panels. The panel has good optical properties, acceptable forming tolerances, environmentally resistant substrate and stiffeners, and adaptability to low to mass production rates. Computer simulations of the concentrator optics were run using the selected reflector panel design. Experimentally determined values for reflector surface specularity and reflectivity along with dimensional data were used in the analysis. The simulations provided intercept factor and net energy into the aperture as a function of aperture size for different surface errors and pointing errors. Point source and Sun source optical tests were also performed.

Effect of glow DBD modulation on gas and thin film chemical composition: case of Ar/SiH4/NH3 mixture

NASA Astrophysics Data System (ADS)

Vallade, Julien; Bazinette, Remy; Gaudy, Laura; Massines, Françoise

2014-06-01

In recent years, atmospheric pressure plasma-enhanced chemical vapour deposition has been identified as a convenient way to deposit good quality thin films. With this type of process, where the gas mixture is injected on one side of the electrodes, the chemical composition of the gas evolves with the gas residence time in the plasma. The consequence is a possible gradient in the chemical composition over the thickness of in-line coatings. The present work shows that the modulation of the plasma with a square signal significantly reduces this gradient while the drawback of low growth rate is avoided by increasing the discharge power. This study deals with plane/plane glow dielectric barrier discharges (DBDs) in an Ar/NH3/SiH4 gas mixture to make thin films. The 50 kHz discharge power of the glow DBD was varied by increasing voltage and modulating excitation. The impact on (i) the plasma development was observed through emission spectroscopy and (ii) the thin film coating through Fourier transform infrared measurements. It is shown that the modulation significantly decreases the time and the energy needed to achieve stable chemistry, enhances secondary chemistry and limits disturbance induced by impurities because of a slower decrease of SiH4 concentration and thus a higher ratio of SiH4/impurities, all very important points for in-line AP-PECVD development. When the growth rate is limited by diffusion, coating growth continues when the discharge is off, so long as there is a precursor gradient between the surface and the gas bulk. A higher discharge power steepens this gradient, which enhances diffusion from the bulk and thus growth rate.

The Work Softening by Deformation-Induced Disordering and Cold Rolling of 6.5 wt pct Si Steel Thin Sheets

NASA Astrophysics Data System (ADS)

Wang, Xianglong; Li, Haoze; Zhang, Weina; Liu, Zhenyu; Wang, Guodong; Luo, Zhonghan; Zhang, Fengquan

2016-09-01

As-cast strip of 6.5 wt pct Si steel was fabricated by twin-roll strip casting. After hot rolling at 1323 K (1050 °C), thin sheets with the thickness of 0.35 mm were produced by warm rolling at 373 K (100 °C) with rolling reductions of 15, 25, 35, 45, 55, and 65 pct. Influence of warm rolling reduction on ductility was investigated by room temperature bending test. The measurement of macro-hardness showed that "work softening" could begin when the warm rolling reduction exceeded 35 pct. The room temperature ductility of the thin sheets gradually increased with the increase of warm rolling reductions, and the plastic deformation during bending began to form when the warm rolling reduction was greater than 45 pct, the 65 pct rolled thin sheet exhibited the maximum plastic deformation of about 0.6 pct during bending at room temperature, with a few small dimples having been observed on the fracture surfaces. B2-ordered domains were formed in the 15, 25, 35, 45, and 55 pct rolled specimens, and their average size decreased with the increase of warm rolling reductions. By contrast, no B2-ordered domain could be found in the 65 pct rolled specimen. It had been observed that large-ordered domains could be split into several small parts by the slip of partial super-dislocations during warm rolling, which led to significant decrease of the order degree to cause the phenomenon of deformation-induced disordering. On the basis of these results, cold rolling schedule was developed to successfully fabricate 0.25-mm-thick sheets with good surface qualities and magnetic properties from warm rolled sheets.

Electron transport properties in fluorinated copper-phthalocyanine films: importance of vibrational reorganization energy and molecular microstructure.

PubMed

Wu, Fu-Chiao; Cheng, Horng-Long; Yen, Chen-Hsiang; Lin, Jyu-Wun; Liu, Shyh-Jiun; Chou, Wei-Yang; Tang, Fu-Ching

2010-03-07

Electron transport (ET) properties of a series of fluorinated copper-phthalocyanine (F(16)CuPc) thin films, which were deposited at different substrate temperatures (T(sub)) ranging from 30 to 150 degrees C, have been investigated by quantum mechanical calculations of the reorganization energy (lambda(reorg)), X-ray diffraction (XRD), atomic force microscopy (AFM), and microRaman spectroscopy. Density functional theory calculations were used to predict the vibrational frequencies, normal mode displacement vectors, and electron-vibrational lambda(reorg) for the F(16)CuPc molecule. The electron mobilities (mu(e)) of F(16)CuPc thin films are strongly dependent on the T(sub), and the value of mu(e) increases with increasing T(sub) from 30 to 120 degrees C, at which point it reaches its maximum value. The importance of electron-vibrational coupling and molecular microstructures for ET properties in F(16)CuPc thin films are discussed on the basis of theoretical vibrational lambda(reorg) calculations and experimental observations of resonance Raman spectra. We observed a good correlation between mu(e) and the full-width-at-half-maximum of the vibrational bands, which greatly contributed to lambda(reorg) and/or which reflects the molecular microstructural quality of the active channel. In contrast, the crystal size analysis by XRD and surface grain morphology by AFM did not reveal a clear correlation with the ET behaviours for these different F(16)CuPc thin films. Therefore, we suggest that for organic films with weak intermolecular interactions, such as F(16)CuPc, optimized microscopic molecular-scale parameters are highly important for efficient long-range charge transport in the macroscopic devices.

Advanced morphological analysis of patterns of thin anodic porous alumina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toccafondi, C.; Istituto Italiano di Tecnologia, Department of Nanostructures, Via Morego 30, Genova I 16163; Stępniowski, W.J.

2014-08-15

Different conditions of fabrication of thin anodic porous alumina on glass substrates have been explored, obtaining two sets of samples with varying pore density and porosity, respectively. The patterns of pores have been imaged by high resolution scanning electron microscopy and analyzed by innovative methods. The regularity ratio has been extracted from radial profiles of the fast Fourier transforms of the images. Additionally, the Minkowski measures have been calculated. It was first observed that the regularity ratio averaged across all directions is properly corrected by the coefficient previously determined in the literature. Furthermore, the angularly averaged regularity ratio for themore » thin porous alumina made during short single-step anodizations is lower than that of hexagonal patterns of pores as for thick porous alumina from aluminum electropolishing and two-step anodization. Therefore, the regularity ratio represents a reliable measure of pattern order. At the same time, the lower angular spread of the regularity ratio shows that disordered porous alumina is more isotropic. Within each set, when changing either pore density or porosity, both regularity and isotropy remain rather constant, showing consistent fabrication quality of the experimental patterns. Minor deviations are tentatively discussed with the aid of the Minkowski measures, and the slight decrease in both regularity and isotropy for the final data-points of the porosity set is ascribed to excess pore opening and consequent pore merging. - Highlights: • Thin porous alumina is partly self-ordered and pattern analysis is required. • Regularity ratio is often misused: we fix the averaging and consider its spread. • We also apply the mathematical tool of Minkowski measures, new in this field. • Regularity ratio shows pattern isotropy and Minkowski helps in assessment. • General agreement with perfect artificial patterns confirms the good manufacturing.« less

Laser cutting of ultra-thin glasses based on a nonlinear laser interaction effect

NASA Astrophysics Data System (ADS)

Chen, Jian; Wu, Zhouling

2013-07-01

Glass panel substrates have been widely used in consumer electronics such as in flat panel TVs, laptops, and cell phones. With the advancement in the industry, the glass substrates are becoming thinner and stronger for reduced weight and volume, which brings great challenges for traditional mechanical processes in terms of cut quality, yield, and throughput. Laser glass cutting provides a non-contact process with minimum impact and superior quality compared to the mechanical counterparts. In this paper, we presented recent progresses in advanced laser processing of ultra-thin glass substrates, especially laser-cutting of ultra-thin glasses by a high power laser through a nonlinear interaction effect. Our results indicate that this technique has great potential of application for mass production of ultra-thin glass substrates.

Modification of opto-electronic properties of ZnO by incorporating metallic tin for buffer layer in thin film solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deepu, D. R.; Jubimol, J.; Kartha, C. Sudha

2015-06-24

In this report, the effect of incorporation of metallic tin (Sn) on opto-electronic properties of ZnO thin films is presented. ZnO thin films were deposited through ‘automated chemical spray pyrolysis’ (CSP) technique; later different quantities of ‘Sn’ were evaporated on it and subsequently annealed. Vacuum annealing showed a positive effect on crystallinity of films. Creation of sub band gap levels due to ‘Sn’ diffusion was evident from the absorption and PL spectra. The tin incorporated films showed good photo response in visible region. Tin incorporated ZnO thin films seem to satisfy the desirable criteria for buffer layer in thin filmmore » solar cells.« less

Effect of solution concentration on MEH-PPV thin films

NASA Astrophysics Data System (ADS)

Affendi, I. H. H.; Sarah, M. S. P.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

MEH-PPV thin films were prepared with a mixture of THF (tetrahydrofuran) solution deposited by spin coating method. The surface topology of MEH-PPV thin film were characterize by atomic force microscopy (AFM) and optical properties of absorption spectra were characterized by using Ultraviolet-visible-near-infrared (UV-Vis-NIR). The MEH-PPV concentration variation affects the surface and optical properties of the thin film where 0.5 mg/ml MEH-PPV concentration have a good surface topology provided the same film also gives the highest absorption coefficient were then deposited to a TiO2 thin film forming composite layer. The composite layer then shows low current flow of short circuit current of Isc = -5.313E-7 A.

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J. III; Halpern, B.L.

1993-10-26

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures. 5 figures.

Growth and bole quality responses to thinning in a red oak-sweetgum stand in southeastern Arkansas: nine-year results

Treesearch

James S. Meadows

2012-01-01

Science-based guidelines for thinning in southern bottomland hardwood stands are inadequate. To address this need, we established a series of thinning studies based on stand density management in hardwood stands on minor streambottom sites across the South. In the third study in this series, four thinning treatments were applied to a poletimber-sized, red oak-sweetgum...

[Modification and luminescence properties of transparent Lu2SiO5 : Ce3+ thin-film phosphors].

PubMed

Fan, Yang-Yang; Liu, Xiao-Lin; Gu, Mu; Ni, Chen; Huang, Shi-Ming; Liu, Bo

2011-02-01

To achieve high-spatial-resolution for X-ray imaging and flat panel display, transparent thin-film phosphors have been attracted much attention in recent years. In comparison with conventional powder phosphors, the transparent thin-film phosphors have some outstanding advantages such as high contrast and resolution, superior thermal conductivity and better adhesion. Cerium-doped lutetium oxyorthosilicate Lu2 SiO5 (LSO) is one promising candidate due to its high density (7.4 g x cm(-3)), high light yield (27 300 photons x MeV(-1)), short decay time (40 ns), and excellent chemical stability. The sol-gel method is one of the most important techniques for deposition of functional thin films, because it possesses a number of advantages over conventional film formation techniques, such as low processing temperature, easy coating of large surfaces, homogenous multicomponent films, and cheap equipments. In X-ray imaging application, the thickness of the thin-film phosphor is the most important factor, which can increase X-ray absorption of the film and then strengthen its luminescence intensity. In the present work, transparent LSO : Ce film was successfully prepared using sol-gel method and spin-coating technique by using inorganic salts as raw materials, 2-methoxyethanol as solvent, and poly (ethylene glycol) (PEG) as modifier without inert atmosphere. The effect of PEG on the luminescence properties of the film was investigated in detail. The results indicated that PEG200 played an important role in the formation of LSO : Ce film, improving its quality and luminescent intensity. The film thickness of 0.9 microm was achieved after 5 times of coating. The luminescence properties of the film were studied. Their performances were good, which implied that the film would have promising applications in high-spatial-resolution X-ray imaging and flat panel display devices.

Homoepitaxial growth of β-Ga{sub 2}O{sub 3} thin films by low pressure chemical vapor deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rafique, Subrina; Han, Lu; Zhao, Hongping, E-mail: hongping.zhao@case.edu

2016-05-02

This paper presents the homoepitaxial growth of phase pure (010) β-Ga{sub 2}O{sub 3} thin films on (010) β-Ga{sub 2}O{sub 3} substrate by low pressure chemical vapor deposition. The effects of growth temperature on the surface morphology and crystal quality of the thin films were systematically investigated. The thin films were synthesized using high purity metallic gallium (Ga) and oxygen (O{sub 2}) as precursors for gallium and oxygen, respectively. The surface morphology and structural properties of the thin films were characterized by atomic force microscopy, X-ray diffraction, and high resolution transmission electron microscopy. Material characterization indicates the growth temperature played anmore » important role in controlling both surface morphology and crystal quality of the β-Ga{sub 2}O{sub 3} thin films. The smallest root-mean-square surface roughness of ∼7 nm was for thin films grown at a temperature of 950 °C, whereas the highest growth rate (∼1.3 μm/h) with a fixed oxygen flow rate was obtained for the epitaxial layers grown at 850 °C.« less

Cluster Beam Studies.

DTIC Science & Technology

1988-04-01

Continue on reverse if necessary and identify by block number) Cluster beams offer a means of depositing high-quality thin films at low...either directly inclustered vapors of nonvolatile materials or Indirectly by bombarding the film duringdeposition with clusters of inert gases. When a...electron volt energy per atom. The suprathermal energy of thej depositing atoms is thought to produce unique thin films (either in quality, or in the ability

Development of validated high-performance thin layer chromatography for quantification of aristolochic acid in different species of the Aristolochiaceae family.

PubMed

Agrawal, Poonam; Laddha, Kirti

2017-04-01

This study was undertaken to isolate and quantify aristolochic acid in Aristolochia indica stem and Apama siliquosa root. Aristolochic acid is an important biomarker component present in the Aristolochiaceae family. The isolation method involved simple solvent extraction, precipitation and further purification, using recrystallization. The structure of the compound was confirmed using infrared spectroscopy, mass spectrometry and nuclear magnetic resonance. A specific and rapid high-performance thin layer chromatography (HPTLC) method was developed for analysis of aristolochic acid. The method involved separation on the silica gel 60 F 254 plates using the single solvent system of n-hexane: chloroform: methanol. The method showed good linear relationship in the range 0.4-2.0 μg/spot with r 2  = 0.998. The limit of detection and limit of quantification were 62.841 ng/spot and 209.47 ng/spot, respectively. The proposed validated HPTLC method was found to be an easy to use, accurate and convenient method that could be successfully used for standardization and quality assessment of herbal material as well as formulations containing different species of the Aristolochiaceae family. Copyright © 2016. Published by Elsevier B.V.

Synthesis and characterization of electron doped La{sub 0.85}Te{sub 0.15}MnO{sub 3} thin film grown on LaAlO{sub 3} substrate by pulsed laser deposition technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhat, Irshad, E-mail: bhat.amu85@gmail.com; Husain, Shahid; Patil, S. I.

2015-06-24

We report the structural, morphological and magneto-transport properties of electron doped La{sub 0.85}Te{sub 0.15}MnO{sub 3} (LTMO) thin film grown on (001) LaAlO{sub 3} single crystal substrate by pulsed laser deposition (PLD). X-ray diffraction (XRD) results confirm that the film has good crystalline quality, single phase, and c-axis orientation. The atomic force microscopy (AFM) results have revealed that the film consists of grains with the average size in a range of 20–30 nm and root-mean square (rms) roughness of 0.27nm. The resistivity versus temperature measurement exhibits an insulator to metal transition (MIT). We have noticed a huge value of magnetoresistance (∼93%)more » close to MIT in presence of 8T field. X-ray photoemission spectroscopy confirms the electron doping and suggests that Te ions could be in the Te{sup 4+} state, while the Mn ions stay in the Mn{sup 2+} and Mn{sup 3+} valence state.« less

Room-Temperature and Solution-Processable Cu-Doped Nickel Oxide Nanoparticles for Efficient Hole-Transport Layers of Flexible Large-Area Perovskite Solar Cells.

PubMed

He, Qiqi; Yao, Kai; Wang, Xiaofeng; Xia, Xuefeng; Leng, Shifeng; Li, Fan

2017-12-06

Flexible perovskite solar cells (PSCs) using plastic substrates have become one of the most attractive points in the field of thin-film solar cells. Low-temperature and solution-processable nanoparticles (NPs) enable the fabrication of semiconductor thin films in a simple and low-cost approach to function as charge-selective layers in flexible PSCs. Here, we synthesized phase-pure p-type Cu-doped NiO x NPs with good electrical properties, which can be processed to smooth, pinhole-free, and efficient hole transport layers (HTLs) with large-area uniformity over a wide range of film thickness using a room-temperature solution-processing technique. Such a high-quality inorganic HTL allows for the fabrication of flexible PSCs with an active area >1 cm 2 , which have a power conversion efficiency over 15.01% without hysteresis. Moreover, the Cu/NiO x NP-based flexible devices also demonstrate excellent air stability and mechanical stability compared to their counterpart fabricated on the pristine NiO x films. This work will contribute to the evolution of upscaling flexible PSCs with a simple fabrication process and high device performances.

Final report for project "Next-Generation Semiconductors for Solar Photoelectrolysis"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalifah, Peter

2016-09-15

In this paper, effective methods have been developed for preparing high-quality LaTiO 2N films on conductive La 5Ti 5O 17 substrates that can serve as photoanodes for photoelectrochemical water oxidation. One paper has been written by the post-doc who completed this comprehensive, interdisciplinary study, and it is presently being finalized for submission. Our approach to this system integrates expertise that we have developed in single crystal growth, thin film growth, and thin film post-processing. Through this work, LTON films have been fully optimized for light harvesting, as their band gap is optimally matched with the incident solar spectrum and themore » film thicknesses have been optimized based on the absolute absorption coefficients that we have measured for this system. The next step is to optimize the co-catalyst functionalization and the solution conditions to maximize the catalytic activity for water oxidation. Since the preliminary tests described here were done without a water oxidation co-catalyst, and since good water oxidation catalysts have previously been identified based on studies of powder samples, this next step is highly likely to be successful.« less

Deposition and Characterization of Hermetic, Biocompatible Thin Film Coatings for Implantable, Electrically Active Devices

NASA Astrophysics Data System (ADS)

Sweitzer, Robyn K.

Retinal prostheses may be used to support patients suffering from Age-related macular degeneration or retinitis pigmentosa. A hermetic encapsulation of the poly(imide )-based prosthesis is important in order to prevent the leakage of water and ions into the electric circuitry embedded in the poly(imide) matrix. The deposition of amorphous aluminum oxide (by sputtering) and diamond like carbon (by pulsed laser ablation and vacuum arc vapor deposition) were studied for the application in retinal prostheses. The resulting thin films were characterized for composition, thickness, adhesion and smoothness by scanning electron microscopy-energy dispersive spectroscopy, atomic force microscopy, profilometry and light microscopy. Electrical stability was evaluated and found to be good. The as-deposited films prevented incursion of salinated fluids into the implant over two (2) three month trials soaking in normal saline at body temperature, Biocompatibility was tested in vivo by implanting coated specimen subretinally in the eye of Yucatan pigs. While amorphous aluminum oxide is more readily deposited with sufficient adhesion quality, biocompatibility studies showed a superior behavior of diamond-like carbon. Amorphous aluminum oxide had more adverse effects and caused more severe damage to the retinal tissue.

Non-resonant microwave absorption in high-T c thin films

NASA Astrophysics Data System (ADS)

Durny, R.; Dulcic, A.; Crepeau, R. H.; Freed, J. H.; Kus, P.

1990-11-01

Magnetic-field-dependent non-resonant microwave absorption in thin film samples of various high- Tc superconductors is reported. Complex types of signals were observed as the temperature was lowered from Tc to ≈ 10 K. Possible correlation between the thin film quality and the occurrence of the signals is suggested.

Paper-based transparent flexible thin film supercapacitors.

PubMed

Gao, Kezheng; Shao, Ziqiang; Wu, Xue; Wang, Xi; Zhang, Yunhua; Wang, Wenjun; Wang, Feijun

2013-06-21

Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm(-2)), and a transmittance of about 56% (at 550 nm).

Response of 55-year-old lodgepole pine to thinning.

Treesearch

James W. Barrett

1961-01-01

Does lodgepole pine (Pinus contorta) as old as 55 years respond to thinning? Very little research has been done to answer this question for central Oregon stands because until recently they have been considered largely unmerchantable. Now, however, this species is recognized as a good potential source of pulpwood and small saw logs, and information...

Al-/Ga-Doped ZnO Window Layers for Highly Efficient Cu₂ZnSn(S,Se)₄ Thin Film Solar Cells.

PubMed

Seo, Se Won; Seo, Jung Woo; Kim, Donghwan; Cheon, Ki-Beom; Lee, Doh-Kwon; Kim, Jin Young

2018-09-01

The successful use of Al-/Ga-doped ZnO (AGZO) thin films as a transparent conducting oxide (TCO) layer of a Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cell is demonstrated. The AGZO thin films were prepared by radio frequency (RF) sputtering. The structural, crystallographic, electrical, and optical properties of the AGZO thin films were systematically investigated. The photovoltaic properties of CZTSSe thin film solar cells incorporating the AGZO-based TCO layer were also reported. It has been found that the RF power and substrate temperature of the AGZO thin film are important factors determining the electrical, optical, and structural properties. The optimization process involving the RF power and the substrate temperature leads to good electrical and optical transmittance of the AGZO thin films. Finally, the CZTSSe solar cell with the AGZO TCO layer demonstrated a high conversion efficiency of 9.68%, which is higher than that of the conventional AZO counterpart by 12%.

LPCVD homoepitaxy of Si doped β-Ga2O3 thin films on (010) and (001) substrates

NASA Astrophysics Data System (ADS)

Rafique, Subrina; Karim, Md Rezaul; Johnson, Jared M.; Hwang, Jinwoo; Zhao, Hongping

2018-01-01

This paper presents the homoepitaxy of Si-doped β-Ga2O3 thin films on semi-insulating (010) and (001) Ga2O3 substrates via low pressure chemical vapor deposition with a growth rate of ≥1 μm/h. Both high resolution scanning transmission electron microscopy and X-ray diffraction measurements demonstrated high crystalline quality homoepitaxial growth of these thin films. Atomic resolution STEM images of the as-grown β-Ga2O3 thin films on (010) and (001) substrates show high quality material without extended defects or dislocations. The charge carrier transport properties of the as-grown Si-doped β-Ga2O3 thin films were characterized by the temperature dependent Hall measurement using van der Pauw patterns. The room temperature carrier concentrations achieved for the (010) and (001) homoepitaxial thin films were ˜1.2 × 1018 cm-3 and ˜9.5 × 1017 cm-3 with mobilities of ˜72 cm2/V s and ˜42 cm2/V s, respectively.

Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates

NASA Astrophysics Data System (ADS)

de Jong, M. M.

2013-01-01

In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic substrates can be a solution. In this thesis, we investigate the possibilities of depositing thin film solar cells directly onto cheap plastic substrates. Micro-textured glass and sheets, which have a wide range of applications, such as in green house, lighting etc, are applied in these solar cells for light trapping. Thin silicon films can be produced by decomposing silane gas, using a plasma process. In these types of processes, the temperature of the growing surface has a large influence on the quality of the grown films. Because plastic substrates limit the maximum tolerable substrate temperature, new methods have to be developed to produce device-grade silicon layers. At low temperature, polysilanes can form in the plasma, eventually forming dust particles, which can deteriorate device performance. By studying the spatially resolved optical emission from the plasma between the electrodes, we can identify whether we have a dusty plasma. Furthermore, we found an explanation for the temperature dependence of dust formation; Monitoring the formation of polysilanes as a function of temperature using a mass-spectrometer, we observed that the polymerization rate is indeed influenced by the substrate temperature. For solar cell substrate material, our choice was polycarbonate (PC), because of its low cost, its excellent transparency and its relatively high glass transition temperature of 130-140°C. At 130°C we searched for deposition recipes for device quality silicon, using a very high frequency plasma enhanced chemical deposition process. By diluting the feedstock silane with hydrogen gas, the silicon quality can be improved for amorphous silicon (a-Si), until we reach the nanocrystalline silicon (nc-Si) regime. In the nc-Si regime, the crystalline fraction can be further controlled by changing the power input into the plasma. With these layers, a-Si thin film solar cells were fabricated, on glass and PC substrates. The adverse effect of the low temperature growth on the photoactive material is further mitigated by using thinner silicon layers, which can deliver a good current only with an adequate light trapping technique. We have simulated and experimentally tested three light trapping techniques, using embossed structures in PC substrates and random structures on glass: regular pyramid structures larger than the wavelength of light (micropyramids), regular pyramid structures comparable to the wavelength of light (nanopyramids) and random nano-textures (Asahi U-type). The use of nanostructured polycarbonate substrates results in initial conversion efficiencies of 7.4%, compared to 7.6% for cells deposited under identical conditions on Asahi U-type glass. The potential of manufacturing thin film solar cells at processing temperatures lower than 130oC is further illustrated by obtained results on texture-etched aluminium doped zinc-oxide (ZnO:Al) on glass: we achieved 6.9% for nc-Si cells using a very thin absorber layer of only 750 nm, and by combining a-Si and nc-Si cells in tandem solar cells we reached an initial conversion efficiency of 9.5%.

Structural and optical characterization of p-type highly Fe-doped SnO2 thin films and tunneling transport on SnO2:Fe/p-Si heterojunction

NASA Astrophysics Data System (ADS)

Ben Haj Othmen, Walid; Ben Hamed, Zied; Sieber, Brigitte; Addad, Ahmed; Elhouichet, Habib; Boukherroub, Rabah

2018-03-01

Nanocrystalline highly Fe-doped SnO2 thin films were prepared using a new simple sol-gel method with iron amounts of 5, 10, 15 and 20%. The obtained gel offers a long durability and high quality allowing to reach a sub-5 nm nanocrystalline size with a good crystallinity. The films were structurally characterized through X-ray diffraction (XRD) that confirms the formation of rutile SnO2. High Resolution Transmission Electron Microscopy (HRTEM) images reveals the good crystallinity of the nanoparticles. Raman spectroscopy shows that the SnO2 rutile structure is maintained even for high iron concentration. The variation of the PL intensity with Fe concentration reveals that iron influences the distribution of oxygen vacancies in tin oxide. The optical transmittance results indicate a redshift of the SnO2 band gap when iron concentration increases. The above optical results lead us to assume the presence of a compensation phenomenon between oxygen vacancies and introduced holes following Fe doping. From current-voltage measurements, an inversion of the conduction type from n to p is strongly predicted to follow the iron addition. Electrical characterizations of SnO2:Fe/p-Si and SnO2:Fe/n-Si heterojunctions seem to be in accordance with this deduction. The quantum tunneling mechanism is expected to be important at high Fe doping level, which was confirmed by current-voltage measurements at different temperatures. Both optical and electrical properties of the elaborated films present a particularity for the same iron concentration and adopt similar tendencies with Fe amount, which strongly correlate the experimental observations. In order to evaluate the applicability of the elaborated films, we proceed to the fabrication of the SnO2:Fe/SnO2 homojunction for which we note a good rectifying behavior.

A Simple Process for Synthesis of Transparent Thin Films of Molybdenum Trioxide in the Orthorhombic Phase ( α-MoO3)

NASA Astrophysics Data System (ADS)

Chibane, Loundja; Belkaid, Mohamed Said; Zirmi, Rachid; Moussi, Abderrahmane

2017-04-01

Transparent orthorhombic molybdenum trioxide (α-MoO3) thin films were prepared on glass substrates by sol-gel dip coating technique of a quality comparable to those prepared by more sophisticated techniques regarded as very costly and difficult to carry out. The prepared films were annealed in air at different temperatures in the range of 150-350°C. X-ray diffraction analysis of the films prepared at 250°C and 350°C confirmed the formation of a single-phase of MoO3 in an orthorhombic crystal system (α-MoO3). Scanning electron microscopy of the films annealed at 350°C indicated a stack of nano-layers with thickness of approximately 30 nm-40 nm. Fourier transform infrared transmittance analysis revealed the Mo=O stretching vibration, which is an indicator of the layered orthorhombic MoO3 phase. Energy dispersive x-ray analysis confirmed the existence of Mo and O in the deposited films. A maximum optical transmittance of 82% in the visible range was obtained from the films annealed at 350°C. The band gap value of the films was evaluated and it was in the range of 3.28 eV-3.40 eV. The obtained results showed that the α-MoO3 thin films prepared at 350°C exhibit good structural, chemical, and optical properties, which might be of interest to the photovoltaic and optoelectronic devices.

Experimental study and analytical model of deformation of magnetostrictive films as applied to mirrors for x-ray space telescopes.

PubMed

Wang, Xiaoli; Knapp, Peter; Vaynman, S; Graham, M E; Cao, Jian; Ulmer, M P

2014-09-20

The desire for continuously gaining new knowledge in astronomy has pushed the frontier of engineering methods to deliver lighter, thinner, higher quality mirrors at an affordable cost for use in an x-ray observatory. To address these needs, we have been investigating the application of magnetic smart materials (MSMs) deposited as a thin film on mirror substrates. MSMs have some interesting properties that make the application of MSMs to mirror substrates a promising solution for making the next generation of x-ray telescopes. Due to the ability to hold a shape with an impressed permanent magnetic field, MSMs have the potential to be the method used to make light weight, affordable x-ray telescope mirrors. This paper presents the experimental setup for measuring the deformation of the magnetostrictive bimorph specimens under an applied magnetic field, and the analytical and numerical analysis of the deformation. As a first step in the development of tools to predict deflections, we deposited Terfenol-D on the glass substrates. We then made measurements that were compared with the results from the analytical and numerical analysis. The surface profiles of thin-film specimens were measured under an external magnetic field with white light interferometry (WLI). The analytical model provides good predictions of film deformation behavior under various magnetic field strengths. This work establishes a solid foundation for further research to analyze the full three-dimensional deformation behavior of magnetostrictive thin films.

Novel back-reflector architecture with nanoparticle based buried light-scattering microstructures for improved solar cell performance

NASA Astrophysics Data System (ADS)

Desta, Derese; Ram, Sanjay K.; Rizzoli, Rita; Bellettato, Michele; Summonte, Caterina; Jeppesen, Bjarke R.; Jensen, Pia B.; Tsao, Yao-Chung; Wiggers, Hartmut; Pereira, Rui N.; Balling, Peter; Larsen, Arne Nylandsted

2016-06-01

A new back-reflector architecture for light-management in thin-film solar cells is proposed that includes a morphologically smooth top surface with light-scattering microstructures buried within. The microstructures are pyramid shaped, fabricated on a planar reflector using TiO2 nanoparticles and subsequently covered with a layer of Si nanoparticles to obtain a flattened top surface, thus enabling growth of good quality thin-film solar cells. The optical properties of this back-reflector show high broadband haze parameter and wide angular distribution of diffuse light-scattering. The n-i-p amorphous silicon thin-film solar cells grown on such a back-reflector show enhanced light absorption resulting in improved external quantum efficiency. The benefit of the light trapping in those solar cells is evidenced by the gains in short-circuit current density and efficiency up to 15.6% and 19.3% respectively, compared to the reference flat solar cells. This improvement in the current generation in the solar cells grown on the flat-topped (buried pyramid) back-reflector is observed even when the irradiation takes place at large oblique angles of incidence. Finite-difference-time-domain simulation results of optical absorption and ideal short-circuit current density values agree well with the experimental findings. The proposed approach uses a low cost and simple fabrication technique and allows effective light manipulation by utilizing the optical properties of micro-scale structures and nanoscale constituent particles.

Equilibrium Passive Sampling of POP in Lipid-Rich and Lean Fish Tissue: Quality Control Using Performance Reference Compounds.

PubMed

Rusina, Tatsiana P; Carlsson, Pernilla; Vrana, Branislav; Smedes, Foppe

2017-10-03

Passive sampling is widely used to measure levels of contaminants in various environmental matrices, including fish tissue. Equilibrium passive sampling (EPS) of persistent organic pollutants (POP) in fish tissue has been hitherto limited to application in lipid-rich tissue. We tested several exposure methods to extend EPS applicability to lean tissue. Thin-film polydimethylsiloxane (PDMS) passive samplers were exposed statically to intact fillet and fish homogenate and dynamically by rolling with cut fillet cubes. The release of performance reference compounds (PRC) dosed to passive samplers prior to exposure was used to monitor the exchange process. The sampler-tissue exchange was isotropic, and PRC were shown to be good indicators of sampler-tissue equilibration status. The dynamic exposures demonstrated equilibrium attainment in less than 2 days for all three tested fish species, including lean fish containing 1% lipid. Lipid-based concentrations derived from EPS were in good agreement with lipid-normalized concentrations obtained using conventional solvent extraction. The developed in-tissue EPS method is robust and has potential for application in chemical monitoring of biota and bioaccumulation studies.

Visible electroluminescence from a ZnO nanowires/p-GaN heterojunction light emitting diode.

PubMed

Baratto, C; Kumar, R; Comini, E; Faglia, G; Sberveglieri, G

2015-07-27

In the current paper we apply catalyst assisted vapour phase growth technique to grow ZnO nanowires (ZnO nws) on p-GaN thin film obtaining EL emission in reverse bias regime. ZnO based LED represents a promising alternative to III-nitride LEDs, as in free devices: the potential is in near-UV emission and visible emission. For ZnO, the use of nanowires ensures good crystallinity of the ZnO, and improved light extraction from the interface when the nanowires are vertically aligned. We prepared ZnO nanowires in a tubular furnace on GaN templates and characterized the p-n ZnO nws/GaN heterojunction for LED applications. SEM microscopy was used to study the growth of nanowires and device preparation. Photoluminescence (PL) and Electroluminescence (EL) spectroscopies were used to characterize the heterojunction, showing that good quality of PL emission is observed from nanowires and visible emission from the junction can be obtained from the region near ZnO contact, starting from onset bias of 6V.

Operation of low-noise single-gap RPC modules exposed to ionisation rates up to 1 kHz /cm2

NASA Astrophysics Data System (ADS)

Ćwiok, M.; Dominik, W.; Górski, M.; Królikowski, J.

2004-11-01

Two single gap medium-size RPC modules, made of bakelite plates of very good mechanical quality of the surface and having initial volume resistivity of 1 ×1010 Ω cm, were tested in the Gamma Irradiation Facility at CERN at ionisation rates up to 1 kHz /cm2. The internal surfaces facing the gas volume of one RPC module were cladded with a thin layer of linseed oil varnish for comparison of oiled and non-oiled RPC operation. The results refer to the gas mixture of C2H2F4/isobutane (97:3) with SF6 addition below 1%. The single gap modules exhibited full detection efficiency plateau for the high voltage range of about 1 kV at full intensity of gamma rays. Good timing characteristics allowed to reach 95% efficiency at fully opened irradiation source with time window of 20 ns. The intrinsic noise rate for a non-oiled and an oiled RPC gap was, respectively, below 5 and 1 Hz /cm2 at full efficiency over 1 kV voltage range.

Thinning shock and response to fertilizer less than expected in young Douglas-fir stand at Wind River Experimental Forest.

Treesearch

Dean S. DeBell; Constance A. Harrington; John. Shumway

2002-01-01

Three thinning treatments (thinned to 3.7 by 3.7 m, thinned to 4.3 by 4.3 m, and an unthinned control treatment with nominal spacing averaging 2.6 by 2.6 m) were installed in a 10-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantation growing on a low-quality site at the Wind River Experimental Forest in southwest Washington. Two...

Thinning, Age, and Site Quality Influence Live Tree Carbon Stocks in Upland Hardwood Forests of the Southern Appalachians

Treesearch

Tara L. Keyser; Stanley J. Zarnoch

2012-01-01

This study examines the effects of thinning, age, and site quality on aboveground live tree carbon (ATC) (Mg/ha) stocks in upland hardwood forests of mixed-species composition in the southern Appalachian Mountains. In 1974, 80 plots ranging in size from 0.06 to 0.1 ha were established in even-aged, mixed-hardwood forests throughout the southern Appalachians. All trees...

Design of Polymers with Semiconductor, NLO and Structural Properties.

DTIC Science & Technology

1991-04-22

polymer thin films. + 14 KV Needle electrod Polymer layer ITO electrode Substrate Heater and temperature control unit The second harmonic coefficients of...the solubily and processability through utilization of derivitization and precursor routes we have been able to form the first optical quality films...ethylene spacer, and therefore 14 possesses a great degree of solubility in organic solvents, necessary for the fabrication of optical quality thin films

Thinning even-aged, upland oak stands

Treesearch

Donald E. Hilt; Martin E. Dale

1989-01-01

Thinning produces bigger and better trees faster. Thinning removes poor quality trees and concentrates growth on the best. Total wood production increases because trees that would otherwise die from competition are harvested. Rotation ages for sawtimber can be shortened as much as 20 years. Or, we can grow bigger, more valuable trees using the same rotation age as an...

Polycrystalline BiFeO{sub 3} thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogle, K. A., E-mail: kashinath.bogle@gmail.com; Narwade, R. D.; Mahabole, M. P.

2016-05-06

We are reporting photosensitivity property of BiFeO{sub 3} thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO{sub 3}/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

Multiferroic YCrO3 thin films grown on glass substrate: Resistive switching characteristics

NASA Astrophysics Data System (ADS)

Seo, Jeongdae; Ahn, Yoonho; Son, Jong Yeog

2016-01-01

Polycrystalline YCrO3 thin films were deposited on (111) Pt/Ta/glass substrates by pulsed laser deposition. The YCrO3 thin films exhibited good ferroelectric properties with remnant polarization of about 5 µC/cm2. Large leakage current was observed by I- V curve and ferroelectric hysteresis loop. The YCrO3 resistive random access memory (RRAM) capacitor showed unipolar switching behaviors with SET and RESET voltages higher than those of general NiO RRAM capacitors. [Figure not available: see fulltext.

Soft Magnetic Multilayered Thin Films for HF Applications

NASA Astrophysics Data System (ADS)

Loizos, George; Giannopoulos, George; Serletis, Christos; Maity, Tuhin; Roy, Saibal; Lupu, Nicoleta; Kijima, Hanae; Yamaguchi, Masahiro; Niarchos, Dimitris

Multilayered thin films from various soft magnetic materials were successfully prepared by magnetron sputtering in Ar atmosphere. The magnetic properties and microstructure were investigated. It is found that the films show good soft magnetic properties: magnetic coercivity of 1-10 Oe and saturation magnetization higher than 1T. The initial permeability of the films is greater than 300 and flattens up to 600 MHz. The multilayer thin film properties in combination with their easy, fast and reproducible fabrication indicate that they are potential candidates for high frequency applications.

Pre-commercial thinning not recommended for Virginia pine stands in southern Maryland

Treesearch

R. H. Fenton; A. R. Bond

1965-01-01

Virginia pine (Pinus virginiana Mill.) normally develops such dense stands on suitable sites, as in old fields, that thinning would seem to be a good silvicultural practice. Seedling stands may have 10,000 or more stems per acre, and stands 20 years old may still contain 2,000 trees. Even though rapid differentiation of crowns occurs in this...

The effect of certification and preparation on teacher quality.

PubMed

Boyd, Donald; Goldhaber, Daniel; Lankford, Hamilton; Wyckoff, James

2007-01-01

To improve the quality of the teacher workforce, some states have tightened teacher preparation and certification requirements while others have eased requirements and introduced "alternative" ways of being certified to attract more people to teaching. Donald Boyd, Daniel Goldhaber, Hamilton Lankford, and James Wyckoff evaluate these seemingly contradictory strategies by examining how preparation and certification requirements affect student achivement. If strong requirements improve student outcomes and deter relatively few potential teachers, the authors say, then they may well be good policy. But if they have little effect on student achievement, if they seriously deter potential teachers, or if schools are able to identify applicants who will produce good student outcomes, then easing requirements becomes a more attractive policy. In reviewing research on these issues, the authors find that evidence is often insufficient to draw conclusions. They do find that highly selective alternative route programs can produce effective teachers who perform about the same as teachers from traditional routes after two years on the job. And they find that teachers who score well on certification exams can improve student outcomes somewhat. Limited evidence suggests that certification requirements can diminish the pool of applicants, but there is no evidence on how they affect student outcomes. And the authors find that schools have a limited ability to identify attributes in prospective teachers that allow them to improve student achievement. The authors conclude that the research evidence is simply too thin to have serious implications for policy. Given the enormous investment in teacher preparation and certification and given the possibility that these requirements may worsen student outcomes, the lack of convincing evidence is disturbing. The authors urge researchers and policymakers to work together to move to a more informed position where good resource decisions can be made.

Optical and structural properties of Al-doped ZnO thin films by sol gel process.

PubMed

Jun, Min-Chul; Koh, Jung-Hyuk

2013-05-01

Transparent conducting oxide (TCO) materials with high transmittance and good electrical conductivity have been attracted much attention due to the development of electronic display and devices such as organic light emitting diodes (OLEDs), and dye-sensitized solar cells (DSSCs). Aluminum doped zinc oxide thin films (AZO) have been well known for their use as TCO materials due to its stability, cost-effectiveness, good optical transmittance and electrical properties. Especially, AZO thin film, which have low resistivity of 2-4 x 10(-4) omega x cm which is similar to that of ITO films with wide band gap semiconductors. The AZO thin films were deposited on glass substrates by sol-gel spin-coating process. As a starting material, zinc acetate dihydrate (Zn(CH3COO)2 x 2H2O) and aluminum chloride hexahydrate (AlCl3 6H2O) were used. 2-methoxyethanol and monoethanolamine (MEA) were used as solvent and stabilizer, respectively. After deposited, the films were preheated at 300 degrees C on a hotplate and post-heated at 650 degrees C for 1.5 hrs in the furnace. We have studied the structural and optical properties as a function of Al concentration (0-2.5 mol.%).

The effect of K and Na excess on the ferroelectric and piezoelectric properties of K0.5Na0.5NbO3 thin films

NASA Astrophysics Data System (ADS)

Ahn, C. W.; Y Lee, S.; Lee, H. J.; Ullah, A.; Bae, J. S.; Jeong, E. D.; Choi, J. S.; Park, B. H.; Kim, I. W.

2009-11-01

We have fabricated K0.5Na0.5NbO3 (KNN) thin films on Pt substrates by a chemical solution deposition method and investigated the effect of K and Na excess (0-30 mol%) on ferroelectric and piezoelectric properties of KNN thin film. It was found that with increasing K and Na excess in a precursor solution from 0 to 30 mol%, the leakage current and ferroelectric properties were strongly affected. KNN thin film synthesized by using 20 mol% K and Na excess precursor solution exhibited a low leakage current density and well saturated ferroelectric P-E hysteresis loops. Moreover, the optimized KNN thin film had good fatigue resistance and a piezoelectric constant of 40 pm V-1, which is comparable to that of polycrystalline PZT thin films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Dong-Suk; Kang, Yu-Jin; Park, Jae-Hyung

Highlights: • We developed and investigated source/drain electrodes in oxide TFTs. • The Mo S/D electrodes showed good output characteristics. • Intrinsic TFT parameters were calculated by the transmission line method. - Abstract: This paper investigates the feasibility of a low-resistivity electrode material (Mo) for source/drain (S/D) electrodes in thin film transistors (TFTs). The effective resistances between Mo source/drain electrodes and amorphous zinc–tin-oxide (a-ZTO) thin film transistors were studied. Intrinsic TFT parameters were calculated by the transmission line method (TLM) using a series of TFTs with different channel lengths measured at a low source/drain voltage. The TFTs fabricated with Momore » source/drain electrodes showed good transfer characteristics with a field-effect mobility of 10.23 cm{sup 2}/V s. In spite of slight current crowding effects, the Mo source/drain electrodes showed good output characteristics with a steep rise in the low drain-to-source voltage (V{sub DS}) region.« less

7 CFR 51.485 - Good internal quality.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Good internal quality. 51.485 Section 51.485... STANDARDS) United States Standards for Grades of Cantaloups 1 Definitions § 51.485 Good internal quality. Good internal quality means that the combined juice from the edible portion of a sample of cantaloups...

Ferroelectric switching of poly(vinylidene difluoride-trifluoroethylene) in metal-ferroelectric-semiconductor non-volatile memories with an amorphous oxide semiconductor

NASA Astrophysics Data System (ADS)

Gelinck, G. H.; van Breemen, A. J. J. M.; Cobb, B.

2015-03-01

Ferroelectric polarization switching of poly(vinylidene difluoride-trifluoroethylene) is investigated in different thin-film device structures, ranging from simple capacitors to dual-gate thin-film transistors (TFT). Indium gallium zinc oxide, a high mobility amorphous oxide material, is used as semiconductor. We find that the ferroelectric can be polarized in both directions in the metal-ferroelectric-semiconductor (MFS) structure and in the dual-gate TFT under certain biasing conditions, but not in the single-gate thin-film transistors. These results disprove the common belief that MFS structures serve as a good model system for ferroelectric polarization switching in thin-film transistors.

Effects of thinning on hydrology and water quality of a drained pine forest in coastal North Carolina

Treesearch

D.M. Amatya; R.W. Skaggs

2008-01-01

A study was conducted to examine the effects of commercial thinning on hydrology and water quality of a 28-year old (in 2002) drained loblolly pine (Pinus taeda L.) plantation watershed (D3) using another adjacent watershed (D1) as a control. A paired watershed approach was used with data from two periods (1988-90 and 2000-02) for calibration and data from 2002-07 as...

Method for producing high quality thin layer films on substrates

DOEpatents

Strongin, Myron; Ruckman, Mark; Strongin, Daniel

1994-01-01

A method for producing high quality, thin layer films of inorganic compounds upon the surface of a substrate is disclosed. The method involves condensing a mixture of preselected molecular precursors on the surface of a substrate and subsequently inducing the formation of reactive species using high energy photon or charged particle irradiation. The reactive species react with one another to produce a film of the desired compound upon the surface of the substrate.

High quality thin films of thermoelectric misfit cobalt oxides prepared by a chemical solution method

PubMed Central

Rivas-Murias, Beatriz; Manuel Vila-Fungueiriño, José; Rivadulla, Francisco

2015-01-01

Misfit cobaltates ([Bi/Ba/Sr/Ca/CoO]nRS[CoO2]q) constitute the most promising family of thermoelectric oxides for high temperature energy harvesting. However, their complex structure and chemical composition makes extremely challenging their deposition by high-vacuum physical techniques. Therefore, many of them have not been prepared as thin films until now. Here we report the synthesis of high-quality epitaxial thin films of the most representative members of this family of compounds by a water-based chemical solution deposition method. The films show an exceptional crystalline quality, with an electrical conductivity and thermopower comparable to single crystals. These properties are linked to the epitaxial matching of the rock-salt layers of the structure to the substrate, producing clean interfaces free of amorphous phases. This is an important step forward for the integration of these materials with complementary n-type thermoelectric oxides in multilayer nanostructures. PMID:26153533

Surface morphology of ultrathin graphene oxide films obtained by the SAW atomization

NASA Astrophysics Data System (ADS)

Balachova, Olga V.; Balashov, Sergey M.; Costa, Carlos A. R.; Pavani Filho, A.

2015-08-01

Lately, graphene oxide (GO) thin films have attracted much attention: they can be used as humidity-sensitive coatings in the surface acoustic wave (SAW) sensors; being functionalized, they can be used in optoelectronic or biodevices, etc. In this research we study surface morphology of small-area thin GO films obtained on Si and quartz substrates by deposition of very small amounts of H2O-GO aerosols produced by the SAW atomizer. An important feature of this method is the ability to work with submicrovolumes of liquids during deposition that provides relatively good control over the film thickness and quality, in particular, minimization of the coffee ring effect. The obtained films were examined using AFM and electron microscopy. Image analysis showed that the films consist of GO sheets of different geometry and sizes and may form discrete or continuous coatings at the surface of the substrates with the minimum thickness of 1.0-1.8 nm which corresponds to one or two monolayers of GO. The thickness and quality of the deposited films depend on the parameters of the SAW atomization (number of atomized droplets, a volume of the initial droplet, etc.) and on sample surface preparation (activation in oxygen plasma). We discuss the structure of the obtained films, uniformity and the surface coverage as a function of parameters of the film deposition process and sample preparation. Qualitative analysis of adhesion of GO films is made by rinsing the samples in DI water and subsequent evaluation of morphology of the remained films.

Atomic-scale analysis of deposition and characterization of a-Si:H thin films grown from SiH radical precursor

NASA Astrophysics Data System (ADS)

Sriraman, Saravanapriyan; Aydil, Eray S.; Maroudas, Dimitrios

2002-07-01

Growth of hydrogenated amorphous silicon films (a-Si:H) on an initial H-terminated Si(001)(2 x1) substrate at T=500 K was studied through molecular-dynamics (MD) simulations of repeated impingement of SiH radicals to elucidate the effects of reactive minority species on the structural quality of the deposited films. The important reactions contributing to film growth were identified through detailed visualization of radical-surface interaction trajectories. These reactions include (i) insertion of SiH into Si-Si bonds, (ii) adsorption onto surface dangling bonds, (iii) surface H abstraction by impinging SiH radicals through an Eley-Rideal mechanism, (iv) surface adsorption by penetration into subsurface layers or dissociation leading to interstitial atomic hydrogen, (v) desorption of interstitial hydrogen into the gas phase, (vi) formation of higher surface hydrides through the exchange of hydrogen, and (vii) dangling-bond-mediated dissociation of surface hydrides into monohydrides. The MD simulations of a-Si:H film growth predict an overall surface reaction probability of 95% for the SiH radical that is in good agreement with experimental measurements. Structural and chemical characterization of the deposited films was based on the detailed analysis of evolution of the films' structure, surface morphology and roughness, surface reactivity, and surface composition. The analysis revealed that the deposited films exhibit high dangling bond densities and rough surface morphologies. In addition, the films are abundant in voids and columnar structures that are detrimental to producing device-quality a-Si:H thin films.

Electromagnetic Interactions in a Shielded PET/MRI System for Simultaneous PET/MR Imaging in 9.4 T: Evaluation and Results

NASA Astrophysics Data System (ADS)

Maramraju, Sri Harsha; Smith, S. David; Rescia, Sergio; Stoll, Sean; Budassi, Michael; Vaska, Paul; Woody, Craig; Schlyer, David

2012-10-01

We previously integrated a magnetic resonance-(MR-) compatible small-animal positron emission tomograph (PET) in a Bruker 9.4 T microMRI system to obtain simultaneous PET/MR images of a rat's brain and of a gated mouse-heart. To minimize electromagnetic interactions in our MR-PET system, viz., the effect of radiofrequency (RF) pulses on the PET, we tested our modular front-end PET electronics with various shield configurations, including a solid aluminum shield and one of thin segmented layers of copper. We noted that the gradient-echo RF pulses did not affect PET data when the PET electronics were shielded with either the aluminum- or the segmented copper-shields. However, there were spurious counts in the PET data resulting from high-intensity fast spin-echo RF pulses. Compared to the unshielded condition, they were attenuated effectively by the aluminum shield ( 97%) and the segmented copper shield ( 90%). We noted a decline in the noise rates as a function of increasing PET energy-discriminator threshold. In addition, we observed a notable decrease in the signal-to-noise ratio in spin-echo MR images with the segmented copper shields in place; however, this did not substantially degrade the quality of the MR images we obtained. Our results demonstrate that by surrounding a compact PET scanner with thin layers of segmented copper shields and integrating it inside a 9.4 T MR system, we can mitigate the impact of the RF on PET, while acquiring good-quality MR images.

Nanostructure and strain effects in active thin films for novel electronic device applications

NASA Astrophysics Data System (ADS)

Yuan, Zheng

2007-12-01

There are many potential applications of ferroelectric thin films that take advantage of their unique dielectric and piezoelectric properties, such as tunable microwave devices and thin-film active sensors for structural health monitoring (SHM). However, many technical issues still restrict practical applications of ferroelectric thin films, including high insertion loss, limited figure of merit, soft mode effect, large temperature coefficients, and others. The main theme of this thesis is the advanced technique developments, and the new ferroelectric thin films syntheses and investigations for novel device applications. A novel method of additional doping has been adopted to (Ba,Sr)TiO 3 (BSTO) thin films on MgO. By introducing 2% Mn into the stoichiometric BSTO, Mn:BSTO thin films have shown a greatly enhanced dielectric tunability and a reduced insertion loss at high frequencies (10-30 GHz). A new record of a large tunability of 80% with a high dielectric constant of 3800 and an extra low dielectric loss of 0.001 at 1 MHz at room-temperature was achieved. Meanwhile, the new highly epitaxial ferroelectric (Pb,Sr)TiO3 (PSTO) thin films have been synthesized on (001) MgO substrates. PSTO films demonstrated excellent high frequency dielectric properties with high dielectric constants above 1420 and large dielectric tunabilities above 34% at room-temperature up to 20 GHz. In addition, a smaller temperature coefficient from 80 K to 300 K was observed in PSTO films compared to BSTO films. These results indicate that the Mn:BSTO and PSTO films are both good candidates for developing room-temperature tunable microwave devices. Furthermore, crystalline ferroelectric BaTiO3 (BTO) thin films have been deposited directly on metal substrate Ni through a unique in-situ substrate pre-oxidation treatment. The highly oriented nanopillar structural BTO films were grown on the buffered layers created by the pre-oxidation treatment. No interdiffusion or reaction was observed at the interface. As-grown BTO films demonstrated good ferroelectric properties and an extremely large piezoelectric response of 130 (x 10-12 C/N). These excellent preliminary results enable the long-term perspective on the unobtrusive ferroelectric thin-film active sensors for SHM applications.

A Low Temperature, Solution-Processed Poly(4-vinylphenol), YO(x) Nanoparticle Composite/Polysilazane Bi-Layer Gate Insulator for ZnO Thin Film Transistor.

PubMed

Shin, Hyeonwoo; Kang, Chan-Mo; Chae, Hyunsik; Kim, Hyun-Gwan; Baek, Kyu-Ha; Choi, Hyoung Jin; Park, Man-Young; Do, Lee-Mi; Lee, Changhee

2016-03-01

Low temperature, solution-processed metal oxide thin film transistors (MEOTFTs) have been widely investigated for application in low-cost, transparent, and flexible electronics. To enlarge the application area, solution-processed gate insulators (GI) have been investigated in recent years. We investigated the effects of the organic/inorganic bi-layer GI to ZnO thin film transistors (TFTs). PVP, YO(x) nanoparticle composite, and polysilazane bi-layer showed low leakage current (-10(-8) A/cm2 in 2 MV), which are applicable in low temperature processed MEOTFTs. Polysilazane was used as an interlayer between ZnO and PVP, YO(x) nanoparticle composite as a good charge transport interface with ZnO. By applying the PVP, YO(x), nanoparticle composite/polysilazane bi-layer structure to ZnO TFTs, we successfully suppressed the off current (I(off)) to -10(-11) and fabricated good MEOTFTs in 180 degrees C.

A comparative study: Effect of plasma on V2O5 nanostructured thin films

NASA Astrophysics Data System (ADS)

Singh, Megha; Kumar, Prabhat; Sharma, Rabindar K.; Reddy, G. B.

2016-05-01

Vanadium pentoxide nanostructured thin films (NSTs) have been studied to analyze the effect of plasma on nanostructures grown and morphology of films deposited using sublimation process. Nanostructured thin films were deposited on glass substrates, one in presence of oxygen plasma and other in oxygen environment (absence of plasma). Films were characterized using XRD, Raman spectroscopy, SEM and HRTEM. XRD studies revealed α-V2O5 films (orthorhombic phase) with good crystallinity. However, film deposited in presence of plasma have higher peak intensities as compared to those deposited in absence of plasma. Raman studies also support these finding following same trends of considerable increase in intensity in case of film deposited in presence of plasma. SEM micrographs makes the difference more visible, as film deposited in plasma have well defined plate like structures whereas other film have not-clearly-defined petal-like structures. HRTEM results show orthorhombic phase with 0.39 nm interplanar spacing, as reported by XRD. Results are hereby in good agreement with each other.

Sol-gel spin coated well adhered MoO3 thin films as an alternative counter electrode for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Mutta, Geeta R.; Popuri, Srinivasa R.; Wilson, John I. B.; Bennett, Nick S.

2016-11-01

In this work, we aim to develop a viable, inexpensive and non-toxic material for counter electrodes in dye sensitized solar cells (DSSCs). We employed an ultra-simple synthesis process to deposit MoO3 thin films at low temperature by sol-gel spin coating technique. These MoO3 films showed good transparency. It is predicted that there will be 150 times reduction of precursors cost by realizing MoO3 thin films as a counter electrode in DSSCs compared to commercial Pt. We achieved a device efficiency of about 20 times higher than that of the previous reported values. In summary we develop a simple low cost preparation of MoO3 films with an easily scaled up process along with good device efficiency. This work encourages the development of novel and relatively new materials and paves the way for massive reduction of industrial costs which is a prime step for commercialization of DSSCs.

Structural properties 3,16-bis triisopropylsilylethynyl (pentacene) (TIPS-pentacene) thin films onto organic dielectric layer using slide coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rusnan, Fara Naila; Mohamad, Khairul Anuar; Seria, Dzul Fahmi Mohd Husin

3,16-bis triisopropylsilylethynyl (Pentacene) (TIPS-Pentacene) compactable interface property is important in order to have a good arrangement of molecular structure. Comparison for TIPS-Pentacene deposited between two different surface layers conducted. 0.1wt% TIPS-Pentacene diluted in chloroform were deposited onto poly(methylmeaclyrate) (PMMA) layered transparent substrates using slide coating method. X-ray diffraction (XRD) used to determine crystallinity of thin films. Series of (00l) diffraction peaks obtained with sharp first peaks (001) for TIPS-Pentacene deposited onto PMMA layer at 5.35° and separation of 16.3 Å. Morphology and surface roughness were carried out using scanning electron microscope (SEM) and surface profilemeter LS500, respectively.TIPS-Pentacene deposited onto PMMAmore » layer formed needled-like-shape grains with 10.26 nm surface roughness. These properties were related as thin film formed and its surface roughness plays important role towards good mobility devices.« less

Thinning northern hardwoods in New England by dominant-tree removal — early results

Treesearch

William Leak

2007-01-01

Commercial thinning is a widely accepted practice in northern hardwood stands of New England. Commercial thinning guidelines for eastern hardwoods generally recommend releasing selected crop trees or the removal of trees in less-than-dominant crown classes unless they are of poor health or quality. However, many northern hardwood stands in New England have a dominant...

Girdling eastern black walnut to increase heartwood width

Treesearch

Larry D. Godsey; W.D. " Dusty" Walter; H.E. " Gene" Garrett

2004-01-01

Eastern black walnut (Juglans nigra L.) has often been planted at spacings that require pre-commercial thinning. These thinnings are deemed pre-commercial due to the small diameter of the trees and the low ratio of dark wood to light wood. As a consequence of size and wood quality, these thinnings are often an expense rather than a source of revenue...

First-year growth and quality response of residual ahrdwood poletimber trees following thinning in an even-aged sawtimber stand

Treesearch

Daniel A. Jr. Skojac; Andrew W. Ezell; James S. Meadows; John D. Hodges

2007-01-01

First-year diameter growth and epicormic branching responses of hardwood poletimber trees retained following thinning- in a sawtimber stand are reported. Poletimber trees were classified as either superior or inferior poletimber, and then retained on separate plots receiving identical thinning treatments. Comparison of responses by the two classes of poletimber was...

Condition and deterioration rate of precommercial thinning slash at False Island, Alaska.

Treesearch

Michael H. McClellan; Paul E. Hennon; Patrick G. Heuer; Kenneth W. Coffin

2014-01-01

We examined slash from thinning treatments in a 21-year chronosequence of young-growth stands in southeast Alaska to determine the strength and persistence of slash effects on two key features of deer habitat quality: forage availability and deer mobility within thinned areas. We describe the main deterioration processes and their dynamics over time. We measured wood...

Mill demonstration of TMP production from forest thinnings : pulp quality, refining energy, and handsheet properties

Treesearch

J.Y. Zhu; C. Tim Scott; Roland Gleisner; Doreen Mann; D.P. Dykstra; G. Holton Quinn; Louis L. Edwards

2007-01-01

High-value, large-volume utilization of forest thinning materials from U.S. National Forests is a potentially important contributor to sustainable forest health. This study demonstrated the utilization of wood chips produced from thinnings for the production of thermomechanical pulp (TMP). Both whole-log chips (primarily from small-diameter logs, tops, and reject logs...

Mill demonstration of TMP production from forest thinnings: pulp quality, refining energy, and handsheet properties

Treesearch

J.Y. Zhu; C. Tim Scott; Roland Gleisner; Doreen Mann; D.P. Dykstra; G. Holton Quinn; Louis L. Edwards

2007-01-01

High-value, large-volume utilization of forest thinning materials from U.S. national forests is a potentially important contributor to sustainable forest health. This study demonstrated the utilization of wood chips produced from thinnings for the production of thermomechanical pulp (TMP). Both whole-log chips (primarily from small-diameter logs, tops, and reject logs...

Effects of thinning intensity and crown class on cherrybark oak epicormic branching five years after treatment

Treesearch

Luben D. Dimov; Erika Stelzer; Kristi Wharton; James S. Meadows; Jim L. Chambers; Kenny Ribbeck; E. Barry Moser

2006-01-01

Thinning in oak-dominated stands may have many desirable consequences, including increases in tree growth and mast production. One of the potential disadvantages, however, is the proliferation of epicormic branches, which leads to reduction in lumber quality and value. We assessed the effects of thinning intensity and initial crown class on cherrybark oak (...

Achieving Ohmic Contact for High-quality MoS2 Devices on Hexagonal Boron Nitride

NASA Astrophysics Data System (ADS)

Cui, Xu

MoS2, among many other transition metal dichalcogenides (TMDCs), holds great promise for future applications in nano-electronics, opto-electronics and mechanical devices due to its ultra-thin nature, flexibility, sizable band-gap, and unique spin-valley coupled physics. However, there are two main challenges that hinder careful study of this material. Firstly, it is hard to achieve Ohmic contacts to mono-layer MoS2, particularly at low temperatures (T) and low carrier densities. Secondly, materials' low quality and impurities introduced during the fabrication significantly limit the electron mobility of mono- and few-layer MoS2 to be substantially below theoretically predicted limits, which has hampered efforts to observe its novel quantum transport behaviours. Traditional low work function metals doesn't necessary provide good electron injection to thin MoS2 due to metal oxidation, Fermi level pinning, etc. To address the first challenge, we tried multiple contact schemes and found that mono-layer hexagonal boron nitride (h-BN) and cobalt (Co) provide robust Ohmic contact. The mono-layer spacer serves two advantageous purposes: it strongly interacts with the transition metal, reducing its work function by over 1 eV; and breaks the metal-TMDCs interaction to eliminate the interfacial states that cause Fermi level pinning. We measure a flat-band Schottky barrier of 16 meV, which makes thin tunnel barriers upon doping the channels, and thus achieve low-T contact resistance of 3 kohm.um at a carrier density of 5.3x10. 12/cm. 2. Similar to graphene, eliminating all potential sources of disorder and scattering is the key to achieving high performance in MoS2 devices. We developed a van der Waals heterostructure device platform where MoS2 layers are fully encapsulated within h-BN and electrically contacted in a multi-terminal geometry using gate-tunable graphene electrodes. The h-BN-encapsulation provides excellent protection from environmental factors, resulting in highly stable device performance, even at elevated temperatures. Both optical and electrical characterization confirms our high quality devices, including an ultra-clean interface, a record-high Hall mobility reaching 34,000 cm. 2/Vs, and first observation of Shubnikov–de Haas oscillations. The development of Ohmic contact and fabrication of high quality devices are critical to MoS2 application and studying its intrinsic properties. Therefore, the progress made in this work will facilitate efforts to study novel physical phenomena of MoS2 that were not accessible before.

Crop trees and quality in bottomland hardwoods ten years after an early thinning in a young sprout-origin stand in south carolina

Treesearch

Lawrence E. Nix

2006-01-01

A 23-year-old, mostly sprout-origin stand in the Congaree river bottom near Columbia, SC, was commercially thinned in 1994 using three methods of thinning: (1) the "Leave tree", (2) “Trainer tree”, and (3) “Corridor” methods. The stand was created in 1971 by KG-blade shearing a 90-year-old, heavily cutover bottomland hardwood stand. Before thinning, the stand...

Thinning young oak stands for small mine timbers - at a profit

Treesearch

Stanley M. Filip

1949-01-01

Young red oak-white oak stands in the Anthracite Forest Region of Pennsylvania occupy nearly 3/4 million acres of land (fig. 1). At present they are a source of lagging, forepoles, and small props used in the coal mines. Under good cutting practice, a substantial quantity of these mine timbers could be produced by thinning these stands, which would at the same time...

Development of plasma assisted thermal vapor deposition technique for high-quality thin film.

PubMed

Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

2016-12-01

The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10 -3 Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance <20 Ω sq -1 and a visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

Development of plasma assisted thermal vapor deposition technique for high-quality thin film

NASA Astrophysics Data System (ADS)

Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

2016-12-01

The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10-3 Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance <20 Ω sq-1 and a visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

[Separation and identification of specific components and quality standard of stem of Dendrobium officinale].

PubMed

Ye, Zi; Lu, Ye; Xue, Ya-Fu; Xu, Hong; Wang, Zheng-Tao

2016-07-01

The violanthin, a specific component, was separated and identified from the stems of Dendrobium officinale by chromatographic technique and spectroscopic method for the first time. The microscopic characteristics of D. officinale powder were examined under a microscopy and described. Thin layer chromatography (TLC) method was used for qualitative analysis of the violanthin from D. officinale stems with a mixture of ethyl acetate, butanone, formic acid and water (4∶3∶1∶1) as the developing solvent on high performance silica gel precoated plate (SGF254) and using aluminium trichloride as a chromagenic agent. The results showed significant characteristics of violanthin from D. officinale stems on TLC, with certain specificity, and could be used to distinguish it from other easily confusing processed medicinal stems of D. devonianum, D. gratiosissimum and D. aphyllum. The content of naringenin, an active ingredient in D. officinale stems was determined by HPLC analysis on a Bischoff Chromatography HIPAK NC-04 ODS AB column (4.4 mm×250 mm, 5 mm) with acetonitrile-0.1% phosphoric acid solution as the mobile phase for gradient elution. The wavelength was set at 226 nm and column temperature was 25 ℃. The HPLC method showed good linearity within the range of 3.90-250.00 g•mL⁻¹ (r = 0.999 9) for naringenin. The average recovery of naringenin was 99.20% with 0.17% of RSD. The mass fraction of 20 batches of D. officinale stems was between 0.190 and 0.498 mg•g⁻¹. The established qualitative and quantitative method was simple and rapid with good repeatability and accuracy, providing experimental basis for improving the quality standard of D. officinale, with a very important significance to ensure its quality and clinical effect. Copyright© by the Chinese Pharmaceutical Association.

Trade-off between Photon Management Efficacy and Material Quality in Thin-Film Solar Cells on Nanostructured Substrates of High Aspect Ratio Structures

DOE PAGES

Chin, Alan; Keshavarz, Majid; Wang, Qi

2018-04-13

Although texturing of the transparent electrode of thin-film solar cells has long been used to enhance light absorption via light trapping, such texturing has involved low aspect ratio features. With the recent development of nanotechnology, nanostructured substrates enable improved light trapping and enhanced optical absorption via resonances, a process known as photon management, in thin-film solar cells. Despite the progress made in the development of photon management in thin-film solar cells using nanostructures substrates, the structural integrity of the thin-film solar cells deposited onto such nanostructured substrates is rarely considered. Here, we report the observation of the reduction in themore » open circuit voltage of amorphous silicon solar cells deposited onto a nanostructured substrate with increasing areal number density of high aspect ratio structures. For a nanostructured substrate with the areal number density of such nanostructures increasing in correlation with the distance from one edge of the substrate, a correlation between the open circuit voltage reduction and the increase of the areal number density of high aspect ratio nanostructures of the front electrode of the small-size amorphous silicon solar cells deposited onto different regions of the substrate with graded nanostructure density indicates the effect of the surface morphology on the material quality, i.e., a trade-off between photon management efficacy and material quality. Lastly, this observed trade-off highlights the importance of optimizing the morphology of the nanostructured substrate to ensure conformal deposition of the thin-film solar cell.« less

Trade-off between Photon Management Efficacy and Material Quality in Thin-Film Solar Cells on Nanostructured Substrates of High Aspect Ratio Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, Alan; Keshavarz, Majid; Wang, Qi

Although texturing of the transparent electrode of thin-film solar cells has long been used to enhance light absorption via light trapping, such texturing has involved low aspect ratio features. With the recent development of nanotechnology, nanostructured substrates enable improved light trapping and enhanced optical absorption via resonances, a process known as photon management, in thin-film solar cells. Despite the progress made in the development of photon management in thin-film solar cells using nanostructures substrates, the structural integrity of the thin-film solar cells deposited onto such nanostructured substrates is rarely considered. Here, we report the observation of the reduction in themore » open circuit voltage of amorphous silicon solar cells deposited onto a nanostructured substrate with increasing areal number density of high aspect ratio structures. For a nanostructured substrate with the areal number density of such nanostructures increasing in correlation with the distance from one edge of the substrate, a correlation between the open circuit voltage reduction and the increase of the areal number density of high aspect ratio nanostructures of the front electrode of the small-size amorphous silicon solar cells deposited onto different regions of the substrate with graded nanostructure density indicates the effect of the surface morphology on the material quality, i.e., a trade-off between photon management efficacy and material quality. Lastly, this observed trade-off highlights the importance of optimizing the morphology of the nanostructured substrate to ensure conformal deposition of the thin-film solar cell.« less

Film analysis employing subtarget effect using 355 nm Nd-YAG laser-induced plasma at low pressure

NASA Astrophysics Data System (ADS)

Hedwig, Rinda; Budi, Wahyu Setia; Abdulmadjid, Syahrun Nur; Pardede, Marincan; Suliyanti, Maria Margaretha; Lie, Tjung Jie; Kurniawan, Davy Putra; Kurniawan, Koo Hendrik; Kagawa, Kiichiro; Tjia, May On

2006-12-01

The applicability of spectrochemical analysis for liquid and powder samples of minute amount in the form of thin film was investigated using ultraviolet Nd-YAG laser (355 nm) and low-pressure ambient air. A variety of organic samples such as commercial black ink usually used for stamp pad, ginseng extract, human blood, liquid milk and ginseng powder was prepared as film deposited on the surface of an appropriate hard substrate such as copper plate or glass slide. It was demonstrated that in all cases studied, good quality spectra were obtained with very low background and free from undesirable contamination by the substrate elements, featuring ppm or even sub-ppm sensitivity and worthy of application for quantitative analysis of organic samples. The proper preparation of the films was found to be crucial in achieving the high quality spectra. It was further shown that much inferior results were obtained when the atmospheric-pressure (101 kPa) operating condition of laser-induced breakdown spectroscopy or the fundamental wavelength of the Nd-YAG laser was employed due to the excessive or improper laser ablation process.

Method for producing high quality thin layer films on substrates

DOEpatents

Strongin, M.; Ruckman, M.; Strongin, D.

1994-04-26

A method for producing high quality, thin layer films of inorganic compounds upon the surface of a substrate is disclosed. The method involves condensing a mixture of preselected molecular precursors on the surface of a substrate and subsequently inducing the formation of reactive species using high energy photon or charged particle irradiation. The reactive species react with one another to produce a film of the desired compound upon the surface of the substrate. 4 figures.

An investigation of flow-limited field-injection electrostatic spraying (FFESS) and its applications to thin film deposition

NASA Astrophysics Data System (ADS)

Singh, Ravindra Pratap

Electrostatic spraying is the process of controlled disruption of a liquid surface due to excess surface charge density. The technique has found applications in a wide range of fields from agricultural sprays to fuel injectors to colloidal thrusters for space vehicle propulsion. Over the past 20 years, the technique has been intensely studied in material processing for synthesis of ceramic and metal powders, nanoparticles and thin films. The importance of the technique lies in its simple setup, high deposition efficiency, and ambient atmosphere operation. In conventional electrostatic spraying (CESS), one uses a conducting nozzle to charge the liquid, mostly by induction charging. CESS is therefore restricted to the single jet mode of spraying which occurs at low spray currents. It lacks stability and reproducibility in the high current, multiple jet regime, which can generate much finer sprays. In flow-limited field-injection electrostatic spraying (FFESS), one uses a field-injection electrode to stably and controllably inject higher currents into the liquid, a la Fowler-Nordheim, using an otherwise insulating nozzle. This way, it is possible to stably electrospray in the multiple jet mode. In addition to producing much finer sprays, the multi-jet mode atomizes liquids at higher rates, and spreads the spray over a wider region and more uniformly than single jet sprays, thus paving way for large-area uniform thin film deposition. A simple yet comprehensive theory is formulated to describe the multi jet formation. The theory, which is based on the energy minimization principle, takes into account, for the first time, the interactions between charged jets which leads to saturation in the number of jets at high spray currents. The possibility of using an array of nozzles to obtain uniform large-area high-throughput thin film deposition is also investigated. A large number of FFESS nozzles with alternating positive and negative polarities arranged in a periodic 2-dimensional array are found to produce uniform thin films over large areas. Deposition of TiO2 and silver thin films using multi jet FFESS is studied, demonstrating great control on film morphology and properties. TiO2 thin films deposited on high-intensity discharge arc lamps are found to improve the quality of its light output. Silver thin films of high purity and conductivity, and with good adhesion, could be deposited at relatively high deposition rates and high deposition efficiency as compared to CVD techniques.

Synthesis of ALD zinc oxide and thin film materials optimization for UV photodetector applications

NASA Astrophysics Data System (ADS)

Tapily, Kandabara Nouhoum

Zinc oxide (ZnO) is a direct, wide bandgap semiconductor material. It is thermodynamically stable in the wurtzite structure at ambient temperature conditions. ZnO has very interesting optical and electrical properties and is a suitable candidate for numerous optoelectronic applications such as solar cells, LEDs and UV-photodetectors. ZnO is a naturally n-type semiconductor. Due to the lack of reproducible p-type ZnO, achieving good homojunction ZnO-based photodiodes such as UV-photodetectors remains a challenge. Meanwhile, heterojunction structures of ZnO with p-type substrates such as SiC, GaN, NiO, AlGaN, Si etc. are used; however, those heterojunction diodes suffer from low efficiencies. ZnO is an n-type material with numerous intrinsic defect levels responsible for the electrical and optical behaviors. Presently, there is no clear consensus about the origin of those defects. In this work, ZnO was synthesized by atomic layer deposition (ALD). ALD is a novel deposition technique suitable for nanotechnology engineering that provides unique features such as precise control of ZnO thin film with atomic resolution, high uniformity, good conformity and high aspect ratio. Using this novel deposition technique, the ALD ZnO deposition process was developed and optimized using diethyl zinc as the precursor for zinc and water vapor as the oxygen source. In order to optimize the film quality for use in electronic applications, the physical, mechanical and electrical properties were investigated. The structural and mechanical properties of the ALD ZnO thin films were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), scanning electron microscopy (SEM), spectroscopic Ellipsometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-VIS absorption and nanoindentation. The electrical characterizations were performed using C-V, I-V, DLTS, Hall Effect, and four-point probe. The intrinsic defects responsible for the electrical and optical properties of the ALD ZnO films were analyzed and identified. ALD ZnO based electronic devices were fabricated, optimized and their electrical characteristics measured. The photocurrent characteristics of ALD ZnO were also optimized, and high efficiency UV-photodetectors were achieved.

Y1Ba2Cu3O(7-delta) thin film dc SQUIDs (superconducting quantum interference device)

NASA Astrophysics Data System (ADS)

Racah, Daniel

1991-03-01

Direct current superconducting quantum interferometers (SQUIDs) based on HTSC thin films have been measured and characterized. The thin films used were of different quality: (1) Granular films on Sapphire substrates, prepared either by e-gun evaporation, by laser ablation or by MOCVD (metal oxide chemical vapor deposition), (2) Epitaxial films on MgO substrates. Modulations of the voltage on the SQUIDs as a function of the applied flux have been observed in a wide range of temperatures. The nature of the modulation was found to be strongly dependent on the morphology of the film and on its critical current. The SQUIDs based on granular films were relatively noisy, hysteretic and with a complicated V-phi shape. Those devices based on low quality (lowIc) granular films could be measured only at low temperatures (much lower than 77 K). While those of higher quality (granular films with high Ic) could be measured near to the superconductive transition. The SQUID based on high quality epitaxial film was measured near Tc and showed an anomalous, time dependent behavior.

TiN-buffered substrates for photoelectrochemical measurements of oxynitride thin films

NASA Astrophysics Data System (ADS)

Pichler, Markus; Pergolesi, Daniele; Landsmann, Steve; Chawla, Vipin; Michler, Johann; Döbeli, Max; Wokaun, Alexander; Lippert, Thomas

2016-04-01

Developing novel materials for the conversion of solar to chemical energy is becoming an increasingly important endeavour. Perovskite compounds based on bandgap tunable oxynitrides represent an exciting class of novel photoactive materials. To date, literature mostly focuses on the characterization of oxynitride powder samples which have undeniable technological interest but do not allow the investigation of fundamental properties such as the role of the crystalline quality and/or the surface crystallographic orientation toward photo-catalytic activity. The challenge of growing high quality oxynitride thin films arises from the availability of a suitable substrate, owing to strict material and processing requirements: effective lattice matching, sufficiently high conductivities, stability under high temperatures and in strongly reducing environments. Here, we have established the foundations of a model system incorporating a TiN-buffer layer which enables fundamental investigations into crystallographic surface orientation and crystalline quality of the photocatalyst against photo(electro)chemical performance to be effectively performed. Furthermore, we find that TiN as current collector enables control over the nitrogen content of oxynitride thin films produced by a modified pulsed laser deposition method and allows the growth of highly ordered LaTiO3-xNx thin films.

Effects of thinning a 55-year-old western white pine stand

Treesearch

Marvin W. Foiles

1956-01-01

The first experiment in thinning western white pine (Pinus monticola Dougl.) was planned and established by J. A. Larson and D. R. Brewster in 1914 in a 55-year-old stand on the Priest River Experimental Forest, Idaho. It was designed to compare the effects of three thinning treatments on volume and quality growth, and on total volume production with an unthinned stand...

Growth after precommercial thinning in two stands of Douglas-fir.

Treesearch

Robert W. Steele

1955-01-01

Twenty years ago, portions of two young Douglas-fir stands on the Wind River Experimental Forest in Skamania County, Washington, were thinned by removing some of the trees in the suppressed and intermediate crown classes. At time of thinning, one stand, (A), was 23 years old and the second, (B), was 30 years old. In both cases site quality is IV. The trees taken out...

Thinning from below in a 60-year-old western white pine stand

Treesearch

Marvin W. Foiles

1955-01-01

Thirty-year results from a test of thinning a 60-year-old western white pine stand indicate that thinning does not appreciably change total volume growth, but it does improve the quality of the final product by increasing diameter growth and improving stand composition. This test was established in 1919 on the Priest River Experimental Forest, Idaho, to test three...

Investigation on V2O5 Thin Films Prepared by Spray Pyrolysis Technique

NASA Astrophysics Data System (ADS)

Anasthasiya, A. Nancy Anna; Gowtham, K.; Shruthi, R.; Pandeeswari, R.; Jeyaprakash, B. G.

The spray pyrolysis technique was employed to deposit V2O5 thin films on a glass substrate. By varying the precursor solution volume from 10mL to 50mL in steps of 10mL, films of various thicknesses were prepared. Orthorhombic polycrystalline V2O5 films were inferred from the XRD pattern irrespective of precursor solution volume. The micro-Raman studies suggested that annealed V2O5 thin film has good crystallinity. The effect of precursor solution volume on morphological and optical properties were analysed and reported.

A unified physical model of Seebeck coefficient in amorphous oxide semiconductor thin-film transistors

NASA Astrophysics Data System (ADS)

Lu, Nianduan; Li, Ling; Sun, Pengxiao; Banerjee, Writam; Liu, Ming

2014-09-01

A unified physical model for Seebeck coefficient was presented based on the multiple-trapping and release theory for amorphous oxide semiconductor thin-film transistors. According to the proposed model, the Seebeck coefficient is attributed to the Fermi-Dirac statistics combined with the energy dependent trap density of states and the gate-voltage dependence of the quasi-Fermi level. The simulation results show that the gate voltage, energy disorder, and temperature dependent Seebeck coefficient can be well described. The calculation also shows a good agreement with the experimental data in amorphous In-Ga-Zn-O thin-film transistor.

Streptavidin Modified ZnO Film Bulk Acoustic Resonator for Detection of Tumor Marker Mucin 1

NASA Astrophysics Data System (ADS)

Zheng, Dan; Guo, Peng; Xiong, Juan; Wang, Shengfu

2016-09-01

A ZnO-based film bulk acoustic resonator has been fabricated using a magnetron sputtering technology, which was employed as a biosensor for detection of mucin 1. The resonant frequency of the thin-film bulk acoustic resonator was located near at 1503.3 MHz. The average electromechanical coupling factor {K}_{eff}^2 and quality factor Q were 2.39 % and 224, respectively. Using the specific binding system of avidin-biotin, the streptavidin was self-assembled on the top gold electrode as the sensitive layer to indirectly test the MUC1 molecules. The resonant frequency of the biosensor decreases in response to the mass loading in range of 20-500 nM. The sensor modified with the streptavidin exhibits a high sensitivity of 4642.6 Hz/nM and a good selectivity.

Zero lattice mismatch and twin-free single crystalline ScN buffer layers for GaN growth on silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lupina, L.; Zoellner, M. H.; Dietrich, B.

2015-11-16

We report the growth of thin ScN layers deposited by plasma-assisted molecular beam epitaxy on Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111) substrates. Using x-ray diffraction, Raman spectroscopy, and transmission electron microscopy, we find that ScN films grown at 600 °C are single crystalline, twin-free with rock-salt crystal structure, and exhibit a direct optical band gap of 2.2 eV. A high degree of crystalline perfection and a very good lattice matching between ScN and GaN (misfit < 0.1%) makes the ScN/Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} buffer system a very promising template for the growth of high quality GaN layers on silicon.

Design, fabrication and characterization of an a-Si:H-based UV detector for sunburn applications

NASA Astrophysics Data System (ADS)

Bayat, Khadijeh; Vygranenko, Yuriy; Sazonov, Andrei; Farrokh-Baroughi, Mahdi

2006-12-01

A thin-film a-Si:H pin detector was developed for selective detection of UVA (320-400 nm) radiation. In order for the fabrication technology to be transferable onto flexible substrates, all of the processing steps were conducted at temperatures less than 125 °C. The measured saturation current as low as 2 pA cm-2 and the ideality factor of 1.47 show that the pin diodes have a good quality i-layer as well as p-i and n-i interfaces. The film thicknesses were optimized to suppress the detector sensitivity in the visible spectral range, and the peak of spectral response was observed at 410 nm. The selectivity estimated from the ratio of the photocurrent generated by UVA absorption to the total photocurrent is 21%.

Terahertz thickness determination with interferometric vibration correction for industrial applications.

PubMed

Pfeiffer, Tobias; Weber, Stefan; Klier, Jens; Bachtler, Sebastian; Molter, Daniel; Jonuscheit, Joachim; Von Freymann, Georg

2018-05-14

In many industrial fields, like automotive and painting industry, the thickness of thin layers is a crucial parameter for quality control. Hence, the demand for thickness measurement techniques continuously grows. In particular, non-destructive and contact-free terahertz techniques access a wide range of thickness determination applications. However, terahertz time-domain spectroscopy based systems perform the measurement in a sampling manner, requiring fixed distances between measurement head and sample. In harsh industrial environments vibrations of sample and measurement head distort the time-base and decrease measurement accuracy. We present an interferometer-based vibration correction for terahertz time-domain measurements, able to reduce thickness distortion by one order of magnitude for vibrations with frequencies up to 100 Hz and amplitudes up to 100 µm. We further verify the experimental results by numerical calculations and find very good agreement.

Thin-film-based optical fiber Fabry-Perot interferometer used for humidity sensing.

PubMed

Peng, Jiankun; Qu, Yapeng; Wang, Weijia; Sun, Tengpeng; Yang, Minghong

2018-04-20

A thin-film-based optical fiber Fabry-Perot interferometer that consists of ZrO 2 and SiO 2 porous thin films is designed and fabricated by electron beam physical vapor deposition. Since the SiO 2 porous thin film has the capability of water adsorption, the proposed Fabry-Perot interferometer is appropriate to detect humidity. Experimental results show that the prepared sensor has a humidity detection range from 0.06% RH to 70% RH. A cycling test shows that the humidity sensor has a responding or recover time of 4 s and good repeatability among different humidity environments. Especially, the proposed humidity sensor is insensitive to temperature variation and suitable for the detection of low relative humidity.

Diagnostic value and cost-effectiveness of good quality digital images accompanying electronic referrals for suspected skin malignancies.

PubMed

Ng, Michael F Y; Stevenson, J Howard

2011-04-01

The aim of this study was to investigate the outcome and cost-effectiveness of good and poor quality photographs accompanying the electronic referrals for suspected skin malignancies. A retrospective study of 100 patients, divided into 2 groups, 50 with good quality photographs and 50 with poor quality photographs. Patients with no digital images, or who failed to attend, or patients with incomplete notes were excluded from the study. The treatment pathway, waiting times, and estimated cost between the 2 groups were compared. Good photographs were more likely to be treated at the 1-Stop Clinic (P = 0.05). Good images had a better positive predictive value than poor quality images (62.55% vs. 42.86%). Good quality images are more accurate than poor quality images in triaging of patients, and thus more effective in facilitating the treatment of malignant lesions timely. Good quality photographs allow a delayed appropriate treatment of benign lesions. This increases the safety for patients in a queue in a rationed health care system, and improves patient flow.

Experiments on elastic cloaking in thin plates.

PubMed

Stenger, Nicolas; Wilhelm, Manfred; Wegener, Martin

2012-01-06

Following a theoretical proposal [M. Farhat et al., Phys. Rev. Lett. 103, 024301 (2009)], we design, fabricate, and characterize a cloaking structure for elastic waves in 1 mm thin structured polymer plates. The cloak consists of 20 concentric rings of 16 different metamaterials, each being a tailored composite of polyvinyl chloride and polydimethylsiloxane. By using stroboscopic imaging with a camera from the direction normal to the plate, we record movies of the elastic waves for monochromatic plane-wave excitation. We observe good cloaking behavior for carrier frequencies in the range from 200 to 400 Hz (one octave), in good agreement with a complete continuum-mechanics numerical treatment. This system is thus ideally suited for demonstration experiments conveying the ideas of transformation optics.

Thin overlay guidelines : project selection, design, and construction.

DOT National Transportation Integrated Search

2015-04-01

Thin hot mix asphalt (HMA) overlays are : cost-effective, high-performance maintenance : treatments. They can be laid at 1.0 to 0.5 inches : thick and consist of quality aggregate and binder : materials. The costs are generally more (per ton) : than ...

Applications of thin-film sandwich crystallization platforms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Axford, Danny, E-mail: danny.axford@diamond.ac.uk; Aller, Pierre; Sanchez-Weatherby, Juan

2016-03-24

Crystallization via sandwiches of thin polymer films is presented and discussed. Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal samplemore » intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.« less

High frequency scattering from a thin lossless dielectric slab. M.S. Thesis

NASA Technical Reports Server (NTRS)

Burgener, K. W.

1979-01-01

A solution for scattering from a thin dielectric slab is developed based on geometrical optics and the geometrical theory of diffraction with the intention of developing a model for a windshield of a small private aircraft for incorporation in an aircraft antenna code. Results of the theory are compared with experimental measurements and moment method calculations showing good agreement. Application of the solution is also addressed.

Analysis of the Sensing Properties of a Highly Stable and Reproducible Ozone Gas Sensor Based on Amorphous In-Ga-Zn-O Thin Film.

PubMed

Wu, Chiu-Hsien; Jiang, Guo-Jhen; Chang, Kai-Wei; Deng, Zu-Yin; Li, Yu-Ning; Chen, Kuen-Lin; Jeng, Chien-Chung

2018-01-09

In this study, the sensing properties of an amorphous indium gallium zinc oxide (a-IGZO) thin film at ozone concentrations from 500 to 5 ppm were investigated. The a-IGZO thin film showed very good reproducibility and stability over three test cycles. The ozone concentration of 60-70 ppb also showed a good response. The resistance change (Δ R ) and sensitivity ( S ) were linearly dependent on the ozone concentration. The response time ( T 90-res ), recovery time ( T 90-rec ), and time constant (τ) showed first-order exponential decay with increasing ozone concentration. The resistance-time curve shows that the maximum resistance change rate (dRg/dt) is proportional to the ozone concentration during the adsorption. The results also show that it is better to sense rapidly and stably at a low ozone concentration using a high light intensity. The ozone concentration can be derived from the resistance change, sensitivity, response time, time constant (τ), and first derivative function of resistance. However, the time of the first derivative function of resistance is shorter than other parameters. The results show that a-IGZO thin films and the first-order differentiation method are promising candidates for use as ozone sensors for practical applications.

Analysis of the Sensing Properties of a Highly Stable and Reproducible Ozone Gas Sensor Based on Amorphous In-Ga-Zn-O Thin Film

PubMed Central

Wu, Chiu-Hsien; Jiang, Guo-Jhen; Chang, Kai-Wei; Deng, Zu-Yin; Li, Yu-Ning; Chen, Kuen-Lin; Jeng, Chien-Chung

2018-01-01

In this study, the sensing properties of an amorphous indium gallium zinc oxide (a-IGZO) thin film at ozone concentrations from 500 to 5 ppm were investigated. The a-IGZO thin film showed very good reproducibility and stability over three test cycles. The ozone concentration of 60–70 ppb also showed a good response. The resistance change (ΔR) and sensitivity (S) were linearly dependent on the ozone concentration. The response time (T90-res), recovery time (T90-rec), and time constant (τ) showed first-order exponential decay with increasing ozone concentration. The resistance–time curve shows that the maximum resistance change rate (dRg/dt) is proportional to the ozone concentration during the adsorption. The results also show that it is better to sense rapidly and stably at a low ozone concentration using a high light intensity. The ozone concentration can be derived from the resistance change, sensitivity, response time, time constant (τ), and first derivative function of resistance. However, the time of the first derivative function of resistance is shorter than other parameters. The results show that a-IGZO thin films and the first-order differentiation method are promising candidates for use as ozone sensors for practical applications. PMID:29315218

Probing the bulk ionic conductivity by thin film hetero-epitaxial engineering

NASA Astrophysics Data System (ADS)

Pergolesi, Daniele; Roddatis, Vladimir; Fabbri, Emiliana; Schneider, Christof W.; Lippert, Thomas; Traversa, Enrico; Kilner, John A.

2015-02-01

Highly textured thin films with small grain boundary regions can be used as model systems to directly measure the bulk conductivity of oxygen ion conducting oxides. Ionic conducting thin films and epitaxial heterostructures are also widely used to probe the effect of strain on the oxygen ion migration in oxide materials. For the purpose of these investigations a good lattice matching between the film and the substrate is required to promote the ordered film growth. Moreover, the substrate should be a good electrical insulator at high temperature to allow a reliable electrical characterization of the deposited film. Here we report the fabrication of an epitaxial heterostructure made with a double buffer layer of BaZrO3 and SrTiO3 grown on MgO substrates that fulfills both requirements. Based on such template platform, highly ordered (001) epitaxially oriented thin films of 15% Sm-doped CeO2 and 8 mol% Y2O3 stabilized ZrO2 are grown. Bulk conductivities as well as activation energies are measured for both materials, confirming the success of the approach. The reported insulating template platform promises potential application also for the electrical characterization of other novel electrolyte materials that still need a thorough understanding of their ionic conductivity.

Ultrafast 3D balanced steady-state free precession MRI of the lung: Assessment of anatomic details in comparison to low-dose CT.

PubMed

Heye, Tobias; Sommer, Gregor; Miedinger, David; Bremerich, Jens; Bieri, Oliver

2015-09-01

To evaluate the anatomical details offered by a new single breath-hold ultrafast 3D balanced steady-state free precession (uf-bSSFP) sequence in comparison to low-dose chest computed tomography (CT). This was an Institutional Review Board (IRB)-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant prospective study. A total of 20 consecutive patients enrolled in a lung cancer screening trial underwent same-day low-dose chest CT and 1.5T MRI. The presence of pulmonary nodules and anatomical details on 1.9 mm isotropic uf-bSSFP images was compared to 2 mm lung window reconstructions by two readers. The number of branching points on six predefined pulmonary arteries and the distance between the most peripheral visible vessel segment to the pleural surface on thin slices and 50 mm maximum intensity projections (MIP) were assessed. Image quality and sharpness of the pulmonary vasculature were rated on a 5-point scale. The uf-bSSFP detection rate of pulmonary nodules (32 nodules visible on CT and MRI, median diameter 3.9 mm) was 45.5% with 21 false-positive findings (pooled data of both readers). Uf-bSSFP detected 71.2% of branching points visible on CT data. The mean distance between peripheral vasculature and pleural surface was 13.0 ± 4.2 mm (MRI) versus 8.5 ± 3.3 mm (CT) on thin slices and 8.6 ± 3.9 mm (MRI) versus 4.6 ± 2.5 mm (CT) on MIPs. Median image quality and sharpness were rated 4 each. Although CT is superior to MRI, uf-bSSFP imaging provides good anatomical details with sufficient image quality and sharpness obtainable in a single breath-hold covering the entire chest. © 2014 Wiley Periodicals, Inc.

Preparation of high-quality planar FeRh thin films for in situ TEM investigations

NASA Astrophysics Data System (ADS)

Almeida, Trevor P.; McGrouther, Damien; Pivak, Yevheniy; Perez Garza, Hector Hugo; Temple, Rowan; Massey, Jamie; Marrows, Christopher H.; McVitie, Stephen

2017-10-01

The preparation of a planar FeRh thin film using a focused ion beam (FIB) secondary electron microscope (SEM) for the purpose of in situ transmission electron microscopy (TEM) is presented. A custom SEM stub with 45° faces allows for the transfer and milling of the sample on a TEM heating chip, whilst Fresnel imaging within the TEM revealed the presence of the magnetic domain walls, confirming the quality of the FIB-prepared sample.

The protective role of general self-determination against 'thin ideal' media exposure on women's body image and eating-related concerns.

PubMed

Mask, Lisa; Blanchard, Céline M

2011-04-01

Women's responses to 'thin ideal' media pending their level of general self-determination (GSD) were examined. High and low GSD women (N = 99) viewed a 'thin physique salient' (TPS) video or a 'thin physique non-salient' (TPNS) video. Following exposure to the TPS video, perceptions of pressure from the media to be thin, body dissatisfaction, and concerns over quantity of food were greater for low but not high GSD women. However, high GSD women reported greater concerns over the quality of food they eat following exposure to the TPNS video. Prevention efforts aimed at enhancing GSD are discussed.

Photoluminescence and cathodoluminescence properties of green emitting SrGa2{S}4 : Eu2+ thin film

NASA Astrophysics Data System (ADS)

Chartier, Céline; Benalloul, Paul; Barthou, Charles; Frigerio, Jean-Marc; Mueller, Gerd O.; Mueller-Mach, Regina; Trottier, Troy

2002-02-01

Photoluminescence and cathodoluminescence properties of SrGa2S4 : Eu2+ thin films prepared by reactive RF magnetron sputtering are investigated. Luminescence performances of the phosphor in the thin film form are compared to those of powder samples: the brightness efficiency of thin films is found to be about 30% of the efficiency of powder at low current density. A ratio higher than 40% is expected at higher current density. Thin film screens for FEDs will become a positive alternative to powder screens provided that film quality and light extraction could be improved by optimization of thickness and deposition parameters.

Thin film absorber for a solar collector

DOEpatents

Wilhelm, William G.

1985-01-01

This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

High-performance and scalable metal-chalcogenide semiconductors and devices via chalco-gel routes

PubMed Central

Jo, Jeong-Wan; Kim, Hee-Joong; Kwon, Hyuck-In; Kim, Jaekyun; Ahn, Sangdoo; Kim, Yong-Hoon; Lee, Hyung-ik

2018-01-01

We report a general strategy for obtaining high-quality, large-area metal-chalcogenide semiconductor films from precursors combining chelated metal salts with chalcoureas or chalcoamides. Using conventional organic solvents, such precursors enable the expeditious formation of chalco-gels, which are easily transformed into the corresponding high-performance metal-chalcogenide thin films with large, uniform areas. Diverse metal chalcogenides and their alloys (MQx: M = Zn, Cd, In, Sb, Pb; Q = S, Se, Te) are successfully synthesized at relatively low processing temperatures (<400°C). The versatility of this scalable route is demonstrated by the fabrication of large-area thin-film transistors (TFTs), optoelectronic devices, and integrated circuits on a 4-inch Si wafer and 2.5-inch borosilicate glass substrates in ambient air using CdS, CdSe, and In2Se3 active layers. The CdSe TFTs exhibit a maximum field-effect mobility greater than 300 cm2 V−1 s−1 with an on/off current ratio of >107 and good operational stability (threshold voltage shift < 0.5 V at a positive gate bias stress of 10 ks). In addition, metal chalcogenide–based phototransistors with a photodetectivity of >1013 Jones and seven-stage ring oscillators operating at a speed of ~2.6 MHz (propagation delay of < 27 ns per stage) are demonstrated. PMID:29662951

Microstructure and dielectric properties of piezoelectric magnetron sputtered w-Sc{sub x}Al{sub 1-x}N thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zukauskaite, Agne; Wingqvist, Gunilla; Palisaitis, Justinas

2012-05-01

Piezoelectric wurtzite Sc{sub x}Al{sub 1-x}N (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al{sub 2}O{sub 3}(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 deg. C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 deg. C, the crystal structure is poor and leakage current is high. Transmission electron microscopymore » with energy dispersive x-ray spectroscopy mapping shows a mass separation into ScN-rich and AlN-rich domains for x {>=} 0.2 when substrate temperature is increased from 400 to 800 deg. C. The piezoelectric response of epitaxial Sc{sub x}Al{sub 1-x}N films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.« less

Microstructure and dielectric properties of piezoelectric magnetron sputtered w-ScxAl1-xN thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zukauskaite, Agne; Wingqvist, Gunilla; Palisaitis, Justinas

2012-01-01

Piezoelectric wurtzite ScxAl1 xN (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al2O3(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 C, the crystal structure is poor and leakage current is high. Transmission electron microscopy with energy dispersive x-ray spectroscopymore » mapping shows a mass separation into ScN-rich and AlN-rich domains for x 0.2 when substrate temperature is increased from 400 to 800 C. The piezoelectric response of epitaxial ScxAl1 xN films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.« less

ZnO synthesized in air by fs laser irradiation on metallic Zn thin films

NASA Astrophysics Data System (ADS)

Esqueda-Barrón, Y.; Herrera, M.; Camacho-López, S.

2018-05-01

We present results on rapid femtosecond laser synthesis of nanostructured ZnO. We used metallic Zn thin films to laser scan along straight tracks, until forming nanostructured ZnO. The synthesis dependence on laser irradiation parameters such as the per pulse fluence, integrated fluence, laser scan speed, and number of scans were explored carefully. SEM characterization showed that the morphology of the obtained ZnO is dictated by the integrated fluence and the laser scan speed; micro Raman and XRD results allowed to identify optimal laser processing conditions for getting good quality ZnO; and cathodoluminescence measurements demonstrated that a single laser scan at high per pulse laser fluence, but a medium integrated laser fluence and a medium laser scan speed favors a low density of point-defects in the lattice. Electrical measurements showed a correlation between resistivity of the laser produced ZnO and point-defects created during the synthesis. Transmittance measurements showed that, the synthesized ZnO can reach down to the supporting fused silica substrate under the right laser irradiation conditions. The physical mechanism for the formation of ZnO, under ultrashort pulse laser irradiation, is discussed in view of the distinct times scales given by the laser pulse duration and the laser pulse repetition rate.

A proposal for epitaxial thin film growth in outer space

NASA Technical Reports Server (NTRS)

Ignatiev, Alex; Chu, C. W.

1988-01-01

A new concept for materials processing in space exploits the ultravacuum component of space for thin film epitaxial growth. The unique low earth orbit space environment is expected to yield 10 to the -14th torr or better pressures, semiinfinite pumping speeds, and large ultravacuum volume without walls. These space ultravacuum properties promise major improvement in the quality, unique nature, and the throughput of epitaxially grown materials. Advanced thin film materials to be epitaxially grown in space include semiconductors, magnetic materials, and thin film high temperature superconductors.

Growth front nucleation of rubrene thin films for high mobility organic transistors

NASA Astrophysics Data System (ADS)

Hsu, C. H.; Deng, J.; Staddon, C. R.; Beton, P. H.

2007-11-01

We demonstrate a mode of thin film growth in which amorphous islands crystallize into highly oriented platelets. A cascade of crystallization is observed, in which platelets growing outward from a central nucleation point impinge on neighboring amorphous islands and provide a seed for further nucleation. Through control of growth parameters, it is possible to produce high quality thin films which are well suited to the formation of organic transistors. We demonstrate this through the fabrication of rubrene thin film transistors with high carrier mobility.

Advanced germanium layer transfer for ultra thin body on insulator structure

NASA Astrophysics Data System (ADS)

Maeda, Tatsuro; Chang, Wen-Hsin; Irisawa, Toshifumi; Ishii, Hiroyuki; Hattori, Hiroyuki; Poborchii, Vladimir; Kurashima, Yuuichi; Takagi, Hideki; Uchida, Noriyuki

2016-12-01

We present the HEtero-Layer Lift-Off (HELLO) technique to obtain ultra thin body (UTB) Ge on insulator (GeOI) substrates. The transferred ultra thin Ge layers are characterized by the Raman spectroscopy measurements down to the thickness of ˜1 nm, observing a strong Raman intensity enhancement for high quality GeOI structure in ultra thin regime due to quantum size effect. This advanced Ge layer transfer technique enabled us to demonstrate UTB-GeOI nMOSFETs with the body thickness of only 4 nm.

Development and Validation of the Pride in Eating Pathology Scale (PEP-S).

PubMed

Faija, Cintia L; Fox, John R E; Tierney, Stephanie; Peters, Sarah; Gooding, Patricia A

2017-01-01

There is a growing body of theoretical and clinical literature highlighting the role of pride in maintaining eating disordered behaviours. Despite its clinical importance, there are no measures to assess feelings of pride associated with eating psychopathology. This study describes the development and validation of the Pride in Eating Pathology Scale (PEP-S), a self-report questionnaire that examines feelings of pride towards eating disordered symptoms (e.g., pride in food restriction, thinness and weight loss). Participants were 390 females, recruited from university and community populations, whose mean age was 26.99 years. Respondents rated pride in eating pathology on a 7-point Likert-scale. Principal Component Analysis indicated that the 60-item scale comprised a four component structure: (1) pride in weight loss, food control and thinness, (2) pride in healthy weight and healthy eating, (3) pride in outperforming others and social recognition and (4) pride in capturing other people's attention due to extreme thinness. These four components explained a total of 65.31% of the variance. The PEP-S demonstrated very good internal reliability (α ranging from 0.88 to 0.98) and very good test-retest reliability over a 3-week time-span (r ranging from 0.81 to 0.93). The PEP-S also showed excellent convergent and discriminant validity. Furthermore, the scale discriminated between women with high and low levels of eating psychopathology. The PEP-S is a psychometrically robust measure of pride in eating pathology. It has the potential to advance theoretical understanding and may also be clinically useful. Copyright © 2015 John Wiley & Sons, Ltd. The PEP-S is a valid, reliable, quick and easy to administer self-report questionnaire that measures pride related to eating pathology. The PEP-S assesses four clinically relevant dimensions: (1) pride in weight loss, food control and thinness, (2) pride in healthy weight and healthy eating, (3) pride in outperforming others and social recognition and (4) pride in capturing other people's attention due to extreme thinness. The PEP-S has very good internal and test-retest reliability, and very good convergent and discriminant validity. The PEP-S distinguishes between women with higher and lower levels of eating psychopathology. The PEP-S makes an important contribution to understanding pride in eating psychopathology, which is essential from both clinical and theoretical perspectives. Copyright © 2015 John Wiley & Sons, Ltd.

Study on the radial vibration of a piezoelectric ceramic thin ring with an inner metal disc

NASA Astrophysics Data System (ADS)

Lin, Shuyu

2006-11-01

In this paper, a piezoelectric ceramic thin ring with an inner metal disc is studied. The radial vibrations of a metal thin disc and a piezoelectric ceramic thin ring are analysed. Their electro-mechanical equivalent circuits in radial vibration are obtained. Based on the electro-mechanical equivalent circuits and the radial boundary conditions, the composite electro-mechanical equivalent circuit of the combination of a piezoelectric ceramic thin ring and a metal disc is obtained and the resonance and anti-resonance frequency equations are derived. The relationship between the resonance frequency, the anti-resonance frequency, the effective electro-mechanical coupling coefficient and the geometrical dimensions is analysed. The resonance and anti-resonance frequencies are measured using the Agilent Precision Impedance Analyzer. It is illustrated that the measured radial resonance and anti-resonance frequencies are in good agreement with the theoretical results.

Chemical Vapor Deposition for Ultra-lightweight Thin-film Solar Arrays for Space

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Raffaelle, Ryne P.; Banger, Kulbinder K.; Jin, Michael H.; Lau, Janice E.; Harris, Jerry D.; Cowen, Jonathan E.; Duraj, Stan A.

2002-01-01

The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power, (W/kg). The use of a polycrystalline chalcopyrite absorber layer for thin film solar cells is considered as the next generation photovoltaic devices. A key technical issues outlined in the 2001 U.S. Photovoltaic Roadmap, is the need to develop low cost, high throughput manufacturing for high-efficiency thin film solar cells. At NASA GRC we have focused on the development of new single-source-precursors (SSPs) and their utility to deposit the chalcopyrite semi-conducting layer (CIS) onto flexible substrates for solar cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering is described. Thin-film fabrication studies demonstrate the SSPs can be used in a spray CVD process, for depositing CIS at reduced temperatures, which display good electrical properties, suitable for PV devices.

Effect of substrate bending on the piezoelectric measurement of PZT thin film

NASA Astrophysics Data System (ADS)

Xu, Xiaohui; Tang, Jianhong; He, Liangna

2009-05-01

Bonding conditions between PZT thin film and sample holder greatly affect the strain measurement of the PZT sample. The influence of various bonding conditions on the measured displacement were analyzed using finite element analysis (FEA). One-end fixed sample induces the maximum bending displacement. Experiments were performed on sol-gel derived PZT thin film. The voltage-displacement curve and "butterfly" loop were measured using laser Doppler method with phase detection. Experimental results agreed well with the simulated ones. The measured frequency dependence of piezoelectric response of PZT thin film indicated that, if the operating frequency was lower than 2 kHz, good bonding effect could be obtained when the entire back surface of the sample was glued to a rigid supporter using epoxy resin. A simple bonding model which considered the adhesives as a spring was used to estimate the frequency response of PZT thin film sample.

Miniature all-silica optical fiber pressure sensor with an ultrathin uniform diaphragm.

PubMed

Wang, Wenhui; Wu, Nan; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

2010-04-26

This paper presents an all-silica miniature optical fiber pressure/acoustic sensor based on the Fabry-Perot (FP) interferometric principle. The endface of the etched optical fiber tip and silica thin diaphragm on it form the FP structure. The uniform and thin silica diaphragm was fabricated by etching away the silicon substrate from a commercial silicon wafer that has a thermal oxide layer. The thin film was directly thermally bonded to the endface of the optical fiber thus creating the Fabry-Perot cavity. Thin films with a thickness from 1microm to 3microm have been bonded successfully. The sensor shows good linearity and hysteresis during measurement. A sensor with 0.75 microm-thick diaphragm thinned by post silica etching was demonstrated to have a sensitivity of 11 nm/kPa. The new sensor has great potential to be used as a non-intrusive pressure sensor in a variety of sensing applications.

MAPLE fabrication of thin films based on kanamycin functionalized magnetite nanoparticles with anti-pathogenic properties

NASA Astrophysics Data System (ADS)

Grumezescu, Valentina; Andronescu, Ecaterina; Holban, Alina Maria; Mogoantă, Laurenţiu; Mogoşanu, George Dan; Grumezescu, Alexandru Mihai; Stănculescu, Anca; Socol, Gabriel; Iordache, Florin; Maniu, Horia; Chifiriuc, Mariana Carmen

2015-05-01

In this study we aimed to evaluate the biocompatibility and antimicrobial activity of kanamycin functionalized 5 nm-magnetite (Fe3O4@KAN) nanoparticles thin films deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. A laser deposition regime was established in order to stoichiometrically transfer Fe3O4@KAN thin films on silicone and glass substrates. Morphological and physico-chemical properties of powders and coatings were characterized by XRD, TEM, SEM, AFM and IR microscopy (IRM). Our nanostructured thin films have proved efficiency in the prevention of microbial adhesion and mature biofilms development as a result of antibiotic release in its active form. Furthermore, kanamycin functionalized nanostructures exhibit a good biocompatibility, both in vivo and in vitro, demonstrating their potential for implants application. This is the first study reporting the assessment of the in vivo biocompatibility of a magnetite-antimicrobial thin films produced by MAPLE technique.

In-situ deposition of sodium titanate thin film as anode for sodium-ion micro-batteries developed by pulsed laser deposition.

PubMed

Rambabu, A; Senthilkumar, B; Sada, K; Krupanidhi, S B; Barpanda, P

2018-03-15

Sodium-ion thin-film micro-batteries form a niche sector of energy storage devices. Sodium titanate, Na 2 Ti 6 O 13 (NTO) thin films were deposited by pulsed laser deposition (PLD) using solid-state synthesized polycrystalline Na 2 Ti 6 O 13 compound. The phase-purity and crystallinity of NTO in bulk and thin-film forms were confirmed by Rietveld refinement. Electron microscopy and atomic force microscopy revealed the formation of uniform ∼100 nm thin film with roughness of ∼4 nm consisting of homogeneous nanoscale grains. These PLD-deposited NTO thin-films, when tested in Na-half cell architecture, delivered a near theoretical reversible capacity close to 42 mA h g -1 involving Ti 4+ /Ti 3+ redox activity along with good cycling stability and rate kinetics. Na 2 Ti 6 O 13 can work as an efficient and safe anode in designing sodium-ion thin-film micro-batteries. Copyright © 2017 Elsevier Inc. All rights reserved.

Influence of Nb doping on the phase transition properties of VO2 thin films prepared by ion beam co-sputtering deposition

NASA Astrophysics Data System (ADS)

Zhu, Huiqun; Li, Pengfei; Zhao, Lite; Liu, Jiahuan

2016-03-01

The Nb-doped VO2 thin films were successfully prepared on the glass substrates by ion beam co-sputtering at room temperature and post annealing under the air condition. The effects of the preparation processing and Nb doping on the thermal hysteresis loop and phase transition temperature of the VO2 thin films were analyzed by resistancetemperature measurement. The results show that Nb doping significantly changes the surface morphologies of VO2 thin films, and Nb-doped VO2 thin films exhibit VO2(002) preferred orientation growth with greatly improved crystallinity and orientation. Compared with pure VO2, the phase transition temperature of Nb-doped VO2 thin films drops to 40 ºC, and the width of thermal hysteresis loop narrows to 8 ºC. It is demonstrated that Nb-doped VO2 thin films prepared by ion beam co-sputtered at room temperature have an obvious thermal sensitive effect, and keep a good characteristic from metal to semiconductor phase transition.

Oxide-based thin film transistors for flexible electronics

NASA Astrophysics Data System (ADS)

He, Yongli; Wang, Xiangyu; Gao, Ya; Hou, Yahui; Wan, Qing

2018-01-01

The continuous progress in thin film materials and devices has greatly promoted the development in the field of flexible electronics. As one of the most common thin film devices, thin film transistors (TFTs) are significant building blocks for flexible platforms. Flexible oxide-based TFTs are well compatible with flexible electronic systems due to low process temperature, high carrier mobility, and good uniformity. The present article is a review of the recent progress and major trends in the field of flexible oxide-based thin film transistors. First, an introduction of flexible electronics and flexible oxide-based thin film transistors is given. Next, we introduce oxide semiconductor materials and various flexible oxide-based TFTs classified by substrate materials including polymer plastics, paper sheets, metal foils, and flexible thin glass. Afterwards, applications of flexible oxide-based TFTs including bendable sensors, memories, circuits, and displays are presented. Finally, we give conclusions and a prospect for possible development trends. Project supported in part by the National Science Foundation for Distinguished Young Scholars of China (No. 61425020), in part by the National Natural Science Foundation of China (No. 11674162).

A facile fabrication of chemically converted graphene oxide thin films and their uses as absorber materials for solar cells

NASA Astrophysics Data System (ADS)

Adelifard, Mehdi; Darudi, Hosein

2016-07-01

There is a great interest in the use of graphene sheets in thin film solar cells with low-cost and good-optoelectronic properties. Here, the production of absorbent conductive reduced graphene oxide (RGO) thin films was investigated. RGO thin films were prepared from spray-coated graphene oxide (GO) layers at various substrate temperature followed by a simple hydrazine-reducing method. The structural, morphological, optical, and electrical characterizations of graphene oxide (GO) and RGO thin films were investigated. X-ray diffraction analysis showed a phase shift from GO to RGO due to hydrazine treatment, in agreement with the FTIR spectra of the layers. FESEM images clearly exhibited continuous films resulting from the overlap of graphene nanosheets. The produced low-cost thin films had high absorption coefficient up to 1.0 × 105 cm-1, electrical resistance as low as 0.9 kΩ/sq, and effective optical band gap of about 1.50 eV, close to the optimum value for solar conversion. The conductive absorbent properties of the reduced graphene oxide thin films would be useful to develop photovoltaic cells.

Structure evolution of zinc oxide thin films deposited by unbalance DC magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aryanto, Didik, E-mail: didi027@lipi.go.id; Materials Research Group, Physics Department, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah; Marwoto, Putut

Zinc oxide (ZnO) thin films are deposited on corning glass substrates using unbalanced DC magnetron sputtering. The effect of growth temperature on surface morphology and crystallographic orientation of ZnO thin film is studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The surface morphology and crystallographic orientation of ZnO thin film are transformed against the increasing of growth temperature. The mean grain size of film and the surface roughness are inversely and directly proportional towards the growth temperature from room temperature to 300 °C, respectively. The smaller grain size and finer roughness of ZnO thin film are obtainedmore » at growth temperature of 400 °C. The result of AFM analysis is in good agreement with the result of XRD analysis. ZnO thin films deposited in a series of growth temperatures have hexagonal wurtzite polycrystalline structures and they exhibit transformations in the crystallographic orientation. The results in this study reveal that the growth temperature strongly influences the surface morphology and crystallographic orientation of ZnO thin film.« less

Reflectance confocal microscopy features of thin versus thick melanomas.

PubMed

Kardynal, Agnieszka; Olszewska, Małgorzata; de Carvalho, Nathalie; Walecka, Irena; Pellacani, Giovanni; Rudnicka, Lidia

2018-01-24

In vivo reflectance confocal microscopy (RCM) plays an increasingly important role in differential diagnosis of melanoma. The aim of the study was to assess typical confocal features of thin (≤1mm according to Breslow index) versus thick (>1mm) melanomas. 30 patients with histopathologically confirmed cutaneous melanoma were included in the study. Reflectance confocal microscopy was performed with Vivascope equipment prior to excision. Fifteen melanomas were thin (Breslow thickness ≤ 1mm) and 15 were thick melanomas (Breslow thickness >1mm). In the RCM examination, the following features were more frequently observed in thin compared to thick melanomas: edged papillae (26.7% vs 0%, p=0.032) and areas with honeycomb or cobblestone pattern (33.3% vs 6.7%, p=0.068). Both features are present in benign melanocytic lesions, so in melanoma are good prognostic factors. The group of thick melanomas compared to the group of thin melanomas in the RCM images presented with greater frequency of roundish cells (100% vs 40%, p=0.001), non-edged papillae (100% vs 60%, p=0.006), numerous pagetoid cells (73.3% vs 33.3%, p=0.028), numerous atypical cells at dermal-epidermal junction (53.3% vs 20%, p=0.058) and epidermal disarray (93.3% vs 66.7%, p=0.068). Non-invasive imaging methods helps in deepening of knowledge about the evolution and biology of melanoma. The most characteristic features for thin melanomas in confocal examination are: fragments of cobblestone or honeycomb pattern and edged papillae (as good prognostic factors). The features of thick melanomas in RCM examination are: roundish cells, non-edged papillae, numerous pagetoid cells at dermal-epidermal junction and epidermal disarray.

Site quality changes in response to slash retention and prescribed fire in thinned ponderosa pine forests

Treesearch

Matt Busse

2010-01-01

The ecological effects of post-thinning slash retention on vegetation, wildlife browse, and soil were evaluated in sixty-year-old stands of second-growth pine in central Oregon. Three slash-retention treatments were compared: whole-tree removal, bole-only removal, and thin no removal (boles and slash scattered on site). The study intent was to create a wide gradient of...

The effect of silvicultural thinning on tree grade distributions of five hardwood species in West Virginia

Treesearch

Gary W. Miller; Kurt W. Gottschalk; Aaron T. Graves; John E. Baumgras; John E. Baumgras

2001-01-01

It is well established that silvicultural thinning can increase tree growth and wood volume utilization in hardwoodstands, but the effects on tree quality and value are less clear. This study measured the effect of silvicultural thinning on tree grades over a period of 12 to 15 years for 803 black cherries (Prunus serotina, Ehrh.), 424 northern red oaks (Quercus rubra...

Two-dimensional X-ray diffraction and transmission electron microscopy study on the effect of magnetron sputtering atmosphere on GaN/SiC interface and gallium nitride thin film crystal structure

NASA Astrophysics Data System (ADS)

Shen, Huaxiang; Zhu, Guo-Zhen; Botton, Gianluigi A.; Kitai, Adrian

2015-03-01

The growth mechanisms of high quality GaN thin films on 6H-SiC by sputtering were investigated by X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The XRD θ-2θ scans show that high quality ( 0002 ) oriented GaN was deposited on 6H-SiC by reactive magnetron sputtering. Pole figures obtained by 2D-XRD clarify that GaN thin films are dominated by ( 0002 ) oriented wurtzite GaN and { 111 } oriented zinc-blende GaN. A thin amorphous silicon oxide layer on SiC surfaces observed by STEM plays a critical role in terms of the orientation information transfer from the substrate to the GaN epilayer. The addition of H2 into Ar and/or N2 during sputtering can reduce the thickness of the amorphous layer. Moreover, adding 5% H2 into Ar can facilitate a phase transformation from amorphous to crystalline in the silicon oxide layer and eliminate the unwanted { 3 3 ¯ 02 } orientation in the GaN thin film. Fiber texture GaN thin films can be grown by adding 10% H2 into N2 due to the complex reaction between H2 and N2.

Gravitational Effects on the Morphology and Kinetics of Photodeposition of Polydiacetylene Thin Films From Monomer Solutions

NASA Technical Reports Server (NTRS)

Paley, Mark S.; Antar, Basil; Witherow, William K.; Frazier, Donald O.

1999-01-01

The goal of this proposed work is to study gravitational effects on the photodeposition of polydiacetylene thin films from monomer solutions onto transparent substrates. Polydiacetylenes have been an extensively studied class of organic polymers because they exhibit many unusual and interesting properties, including electrical conductivity and optical nonlinearity. Their long polymeric chains render polydiacetylenes readily conducive to thin film formation, which is necessary for many applications. These applications require thin polydiacetylene films possessing uniform thicknesses, high purity, minimal inhomogeneities and defects (such as scattering centers), etc. Also, understanding and controlling the microstructure and morphology of the films is important for optimizing their electronic and optical properties. The lack of techniques for processing polydiacetylenes into such films has been the primary limitation to their commercial use. We have recently discovered a novel method for the formation of polydiacetylene thin films using photo-deposition from monomer solutions onto transparent substrates with UV light. This technique is very simple to carry out, and can yield films with superior quality to those produced by conventional methods. Furthermore, these films exhibit good third-order properties and are capable of waveguiding. We have been actively studying the chemistry of diacetylene polymerization in solution and the photo-deposition of polydiacetylene thin films from solution. It is well-known that gravitational factors such as buoyancy-driven convection and sedimentation can affect chemical and mass transport processes in solution. One important aspect of polydiacetylene thin film photodeposition in solution, relevant to microgravity science, is that heat generated by absorption of UV radiation induces thermal density gradients that under the influence of gravity, can cause fluid flows (buoyancy-driven convection). Additionally, changes in the chemical composition of the solution during polymerization may cause solutal convection. These fluid flows affect transport of material to and from the film surface and thereby affect the kinetics of the growth process. This manifests itself in the morphology of the resulting films; films grown under the influence of convection tend to have less uniform thicknesses, and can possess greater inhomogeneities and defects. Specifically, polydiacetylene films photodeposited from solution, when viewed under a microscope, exhibit very small particles of solid polymer which get transported by convection from the bulk solution to the surface of the growing film and become embedded. Even when carried out under conditions designed to minimize unstable density gradients (i.e., irradiating the solution from the top), some fluid flow still takes place (particles remain present in the films). It is also possible that defect nucleation may be occurring within the films or on the surface of the substrate; this, too, can be affected by convection (as is the case with crystal growth). Hence films grown in 1-g will, at best, still possess some defects. The objective of this proposal is to investigate, both in 1-g and in low-g, the effects of gravitational factors (primarily convection) on the dynamics of these processes, and on the quality, morphology, and properties of the films obtained.

The Implementation of "The n-term" Formula to Improve Student Ability in Determining the Rules of a Numeric Sequence

ERIC Educational Resources Information Center

In'am, Akhsanul; Hajar, Siti

2013-01-01

A good-quality teacher may determines a good-quality learning, thus good-quality students will be the results. In order to have a good-quality learning, a lot of strategies and methods can be adopted. The objective of this research is to improve students' ability in determining the rules of a numeric sequence and analysing the effectiveness of the…

Optical and electrical responses of magnetron-sputtered amorphous Nb-doped TiO2 thin films annealed at low temperature

NASA Astrophysics Data System (ADS)

Quynh, Luu Manh; Tien, Nguyen Thi; Thanh, Pham Van; Hieu, Nguyen Minh; Doanh, Sai Cong; Thuat, Nguyen Tran; Tuyen, Nguyen Viet; Luong, Nguyen Hoang; Hoang, Ngoc Lam Huong

2018-03-01

Nb-doped TiO2 (TNO) thin films were prepared by annealing at 300 °C for 30 min after a magnetron-sputter process. A laser-irradiated post-annealing Raman scattering analysis indirectly showed the possible formation of small size anatase TNO clusters within the thin film matrix Although the TNO thin films were not crystallized, oxygen vacancies were created by adding H2 into the sputter gas during the deposition process. This improved the conductivity and carrier concentration of the thin films. As the ratio of H2 in sputter gas is f(H2) = [H2/Ar+H2] = 10%, the carrier concentration of the amorphous TNO thin film reached 1022 (cm-3) with the resistivity being about 10-2 (Ω.cm). Even though a new methodology to decrease the fabrication temperature is not presented; this study demonstrates an efficient approach to shorten the annealing process, which ends prior to the crystallization of the thin films. Besides, in situ H2 addition into the sputter atmosphere is proven to be a good solution to enhance the electrical conductivity of semiconductor thin films like TNOs, despite the fact that they are not well crystallized.

Effect of substrate temperature and oxygen partial pressure on RF sputtered NiO thin films

NASA Astrophysics Data System (ADS)

Cheemadan, Saheer; Santhosh Kumar, M. C.

2018-04-01

Nickel oxide (NiO) thin films were deposited by RF sputtering process and the physical properties were investigated for varying substrate temperatures and oxygen partial pressure. The variation of the crystallographic orientation and microstructure of the NiO thin films with an increase in substrate temperature were studied. It was observed that NiO thin films deposited at 350 °C shows relatively good crystalline characteristics with a preferential orientation along (111) plane. With the optimum substrate temperature of 350 °C, the NiO thin films were deposited under various oxygen partial pressures at the same experimental conditions. The structural, optical and electrical properties of NiO thin films under varying oxygen partial pressure of 10%–50% were investigated. From XRD it is clear that the films prepared in the pure argon atmosphere were amorphous while the films in oxygen partial pressure exhibited polycrystalline NiO phase. SEM and AFM investigations unveil that the higher substrate temperature improves the microstructure of the thin films. It is revealed that the NiO thin films deposited at oxygen partial pressure of 40% and a substrate temperature of 350 °C, showed higher electrical conductivity with p-type characteristics.

7 CFR 51.481 - Very good internal quality.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Very good internal quality. 51.481 Section 51.481 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... quality. Very good internal quality means that the combined juice from the edible portion of a sample of...

Development of Seaweed-based Biopolymers for Edible Films and Lectins

NASA Astrophysics Data System (ADS)

Praseptiangga, D.

2017-04-01

Marine macroalgae (seaweeds) as one of important groups of biopolymers play an important role in human life. Biopolymers have been studied regarding their film-forming properties to produce edible films intended as food packaging and active ingredient carriers. Edible film, a thin layer or which is an integral part of food and can be eaten together with, have been used to avoid food quality deterioration due to physico-chemical changes, texture changes, or chemical reactions. Film-forming materials can be utilized individually or as mixed composite blends. Proteins and polysaccharides used for their mechanical and structural properties, and hydrophobic substances (lipids, essential oils, and emulsifiers) to provide good moisture barrier properties. In addition, bioactive substances from marine natural products, including seaweeds, have been explored for being used in the fields of medicine, food science, pharmaceutical science, biochemistry, and glycobiology. Among them, lectins or carbohydrate-binding proteins from seaweeds have recently been remarked. Lectins (hemagglutinins) are widely distributed in nature and also good candidates in such prospecting of seaweeds. They are useful as convenient tools to discriminate differences in carbohydrate structures and reveal various biological activities through binding and interacting to carbohydrates, suggesting that they are promising candidates for medicinal and clinical application.

Technology development of high-quality semiconductor devices using solution-processed crystallization of pentacene

NASA Astrophysics Data System (ADS)

Liu, Hung-Wei

Organic electronic materials and processing techniques have attracted considerable attention for developing organic thin-film transistors (OTFTs), since they may be patterned on flexible substrates which may be bent into a variety of shapes for applications such as displays, smart cards, solar devices and sensors Various fabrication methods for building pentacene-based OTFTs have been demonstrated. Traditional vacuum deposition and vapor deposition methods have been studied for deposition on plastic and paper, but these are unlikely to scale well to large area printing. Researchers have developed methods for processing OTFTs from solution because of the potential for low-cost and large area device manufacturing, such as through inkjet or offset printing. Most methods require the use of precursors which are used to make pentacene soluble, and these methods have typically produced much lower carrier mobility than the best vacuum deposited devices. We have investigated devices built from solution-processed pentacene that is locally crystallized at room temperature on the polymer substrates. Pentacene crystals grown in this manner are highly localized at pre-determined sites, have good crystallinity and show good carrier mobility, making this an attractive method for large area manufacturing of semiconductor devices.

[Effect of thinning intensities on fruiting regularities of Quercus liaotungensis forests in Huang-long and Qiaoshan mountains.

PubMed

Huang, Cai Zhi; Zhang, Wen Hui; Li, Gang; Yu, Shi Chuan; You, Jian Jian

2016-11-18

In order to clarify the impact of thinning intensities on fruiting regularity of Quercus liaotungensis forests, we took the Q. liaotungensis half-mature forests in Huanglong and Qiaoshan mountains on south of the Loess Plateau as the object of study, which were under close-to-natural management of different thinning intensities (CK, 10%, 20% and 30%). An analysis was made on stand density and percent of seed trees, seed number of sample tree and unit area, seed spatial distributions, seed characteristics of the Q. liaotungensis forests after 5 years of thinning. The results showed that, percent of seed trees, seed number per sample tree and percent of developed seeds of Q. liaotungensis forests increased with the increasing intensity, and showed a pattern of 30%>20%>10%>CK. Seed number per area reached the maximum number under 20% thinning, and showed a pattern of 20%>30%>CK>10%. From the seed spatial distribution in the canopy, the upper accounted for 73.6%, while the lower had 26.4%. The sunny side of canopy layer set relatively the most fruits of 65.8%, shady side only had 34.2%. Under thinning, further improving was geater under lower canopy than under upper canopy and so was on shady side than on sunny side. The seed long diameter, seed short diameter and 1000-seed mass of Q. liaotungensis forests increased with the increasing intensity, which reached the maximum under 30% thinning. 10% thinning did not significantly impact Q. liaotungensis fruiting, the thinning intensity of 20% was most conducive to the seed quantity and quality improvement of Q. liaotungensis, while the thinning intensity of 30% did not improve the fruiting, and lowered the total number of seeds. It was proposed that 20% thinning should be chosen (canopy density of 0.7) to effectively improve fruiting and quality of Q. liaotungensis.

Durable high strength cement concrete topping for asphalt roads

NASA Astrophysics Data System (ADS)

Vyrozhemskyi, Valerii; Krayushkina, Kateryna; Bidnenko, Nataliia

2017-09-01

Work on improving riding qualities of pavements by means of placing a thin cement layer with high roughness and strength properties on the existing asphalt pavement were conducted in Ukraine for the first time. Such pavement is called HPCM (High Performance Cementitious Material). This is a high-strength thin cement-layer pavement of 8-9 mm thickness reinforced with metal or polymer fiber of less than 5 mm length. Increased grip properties are caused by placement of stone material of 3-5 mm fraction on the concrete surface. As a result of the research, the preparation and placement technology of high-strength cement thin-layer pavement reinforced with fiber was developed to improve friction properties of existing asphalt pavements which ensures their roughness and durability. It must be emphasized that HPCM is a fundamentally new type of thin-layer pavement in which a rigid layer of 10 mm thickness is placed on a non-rigid base thereby improving riding qualities of asphalt pavement at any season of a year.

Positron lifetime spectroscopy for investigation of thin polymer coatings

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Sprinkle, Danny R.; Eftekhari, Abe

1993-01-01

In the aerospace industry, applications for polymer coatings are increasing. They are now used for thermal control on aerospace structures and for protective insulating layers on optical and microelectronic components. However, the effectiveness of polymer coatings depends strongly on their microstructure and adhesion to the substrates. Currently, no technique exists to adequately monitor the quality of these coatings. We have adapted positron lifetime spectroscopy to investigate the quality of thin coatings. Results of measurements on thin (25-micron) polyurethane coatings on aluminum and steel substrates have been compared with measurements on thicker (0.2-cm) self-standing polyurethane discs. In all cases, we find positron lifetime groups centered around 560 psec, which corresponds to the presence of 0.9-A(exp 3) free-volume cells. However, the number of these free-volume cells in thin coatings is larger than in thick discs. This suggests that some of these cells may be located in the interfacial regions between the coatings and the substrates. These results and their structural implications are discussed in this report.

Single Source Precursors for Thin Film Solar Cells

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Hollingsworth, Jennifer A.; Harris, Jerry D.; Cowen, Jonathan; Buhro, William E.; Hepp, Aloysius F.

2002-01-01

The development of thin film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power, (W/kg). The use of a polycrystalline chalcopyrite absorber layer for thin film solar cells is considered as the next generation photovoltaic devices. At NASA GRC we have focused on the development of new single source precursors (SSP) and their utility to deposit the chalcopyrite semi-conducting layer (CIS) onto flexible substrates for solar cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering is described. Thin-film fabrication studies demonstrate the SSPs can be used in a spray CVD (chemical vapor deposition) process, for depositing CIS at reduced temperatures, which display good electrical properties, suitable for PV (photovoltaic) devices.

Ternary Precursors for Depositing I-III-VI2 Thin Films for Solar Cells via Spray CVD

NASA Technical Reports Server (NTRS)

Banger, K. K.; Hollingsworth, J. A.; Jin, M. H.-C.; Harris, J. D.; Duraj, S. A.; Smith, M.; Scheiman, D.; Bohannan, E. W.; Switzer, J. A.; Buhro, W. E.

2002-01-01

The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power (W/kg). Thin-film fabrication studies demonstrate that ternary single source precursors (SSP's) can be used in either a hot or cold-wall spray chemical vapour deposition (CVD) reactor, for depositing CuInS2, CuGaS2, and CuGaInS2 at reduced temperatures (400 to 450 C), which display good electrical and optical properties suitable for photovoltaic (PV) devices. X-ray diffraction studies, energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) confirmed the formation of the single phase CIS, CGS, CIGS thin-films on various substrates at reduced temperatures.

Optimization of high quality Cu2ZnSnS4 thin film by low cost and environment friendly sol-gel technique for thin film solar cells applications

NASA Astrophysics Data System (ADS)

Chaudhari, J. J.; Joshi, U. S.

2018-05-01

In this study kesterite Cu2ZnSnS4 (CZTS) thin films suitable for absorber layer in thin film solar cells (TFSCs) were successfully fabricated on glass substrate by sol-gel method. The effects of complexing agent on formation of CZTS thin films have been investigated. X-ray diffraction (XRD) analysis confirms formation of polycrystalline CZTS thin films with single phase kesterite structure. XRD and Raman spectroscopy analysis of CZTS thin films with optimized concentration of complexing agent confirmed formation of kesterite phase in CZTS thin films. The direct optical band gap energy of CZTS thin films is found to decrease from 1.82 to 1.50 eV with increase of concentration of complexing agent triethanolamine. Morphological analysis of CZTS thin films shows smooth, uniform and densely packed CZTS grains and increase in the grain size with increase of concentration of complexing agent. Hall measurements revealed that concentration of charge carrier increases and resistivity decreases in CZTS thin films as amount of complexing agent increases.

Paper-based transparent flexible thin film supercapacitors

NASA Astrophysics Data System (ADS)

Gao, Kezheng; Shao, Ziqiang; Wu, Xue; Wang, Xi; Zhang, Yunhua; Wang, Wenjun; Wang, Feijun

2013-05-01

Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm-2), and a transmittance of about 56% (at 550 nm).Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm-2), and a transmittance of about 56% (at 550 nm). Electronic supplementary information (ESI) available: Experimental, TEM image, IR spectra, and XRD spectra of cellulose nanofibers, TEM image, and XRD spectra of RGO, graphite, GO nanosheets, CNF paper, and CNF-[RGO]20 hybrid paper, high-resolution C1s spectra of GO, Raman spectra of GO nanosheets, cross-sectional FESEM image of CNF-[RGO]20 hybrid paper and stress-strain curve of T-SC-20. See DOI: 10.1039/c3nr00674c

Production of thin glass mirrors by hot slumping for x-ray telescopes: present process and ongoing development

NASA Astrophysics Data System (ADS)

Salmaso, B.; Basso, S.; Brizzolari, C.; Civitani, M.; Ghigo, M.; Pareschi, G.; Spiga, D.; Tagliaferri, G.; Vecchi, G.

2014-07-01

Thin glass foils are considered good candidates to build a segmented X-ray telescope with effective area as large as 2 m2 and angular resolution better than 5 arcsec. In order to produce thin glass mirror segments, we developed a direct hot slumping technique assisted by pressure, in which the shape of a mould is replicated onto the optical surface of the glass. In this paper we present the result obtained with AF32 (by Schott) and EAGLE XG (by Corning) glass types. The selected mould material is Zerodur K20, as it does not require any anti-sticking layer and has a good matching, in terms of Coefficient of Thermal Expansion, with both glass types. Our group already produced a few prototypes, reaching angular resolution near 20 arcsec. In this work, relevant steps forward aimed at attaining a 5 arcsec angular resolution are described, along with the tuning of few key parameters in the slumping process. The results obtained on a newly procured cylindrical Zerodur K20 mould are presented.

In-situ ellipsometry: applications to thin film research, development, and production

NASA Astrophysics Data System (ADS)

Kief, M. T.

1999-07-01

Many industries including the optics industry, semiconductor industry, and magnetic storage industry are deeply rooted in the science and technology of thin film materials and thin film based devices. Research in novel thin film systems and the engineering of artificial structures increasingly requires a control on the atomic scale in both thickness and lateral order. Development of the deposition and fabrication processes for these thin film structures requires technical sophistication and efficiency combined with an understanding of the multi-faceted process interactions. The production of these materials necessitates a remarkable degree of control to minimize scrap and assure good performance. Furthermore, in today's industry these operations must occur at an ever accelerating pace. In this article, we will review one technique which can make these challenges more tractable - insitu ellipsometry. This is a very powerful tool which is capable of characterizing thin film processes in real-time. We review the art and illustrate with novel applications to metal thin film growth. In addition, we will illustrate how information obtained with insitu ellipsometry can predict the end use thin film properties such as the transport properties. In conclusion, further advances in insitu ellipsometry and its applications will be discussed in terms of needs and trends as a tool for thin film research, development and production.

Highway pavement performance test for colored thin anti-skidding layers

NASA Astrophysics Data System (ADS)

Gao, Wei; Cui, Wei; Xu, Ming

2018-03-01

Based on the actual service condition of highway pavement colored thin anti-skidding layers, with materials of color quartz sand and two-component acrylic resin as basis, we designed such tests as the bond strength, shearing strength, tear strength, fatigue performance and aggregate polished value, and included the freeze-thaw cycle and de-icing salt and other factors in the experiment, connecting with the climate characteristics of circumpolar latitude and low altitude in Heilongjiang province. Through the pavement performance test, it is confirmed that the colored thin anti-skidding layers can adapt to cold and humid climate conditions, and its physical mechanical properties are good.

Analysis of the tunable asymmetric fiber F-P cavity for fiber sensor edge-filter demodulation

NASA Astrophysics Data System (ADS)

Chen, Haitao; Liang, Youcheng

2014-12-01

An asymmetric fiber (Fabry-Pérot,F-P) interferometric cavity with good linearity and wide dynamic range is successfully designed basing on optical thin film characteristic matrix theory; by choosing the material of two different thin metallic layers, the asymmetric fiber F-P interferometric cavity is fabricated by depositing the multi-layer thin films on the optical fiber's end face. The demodulation method for the wavelength shift of fiber Bragg grating (FBG) sensor basing on the F-P cavity is demonstrated and a theoretical formula is obtained. And the experimental results coincide well with computational results obtained from the theoretical model.

The Integration Process of Very Thin Mirror Shells with a Particular Regard to Simbol-X

NASA Astrophysics Data System (ADS)

Basso, S.; Pareschi, G.; Tagliaferri, G.; Mazzoleni, F.; Valtolina, R.; Citterio, O.; Conconi, P.

2009-05-01

The optics of Simbol-X are very thin compared to previous X-ray missions (like XMM). Therefore their shells floppy and are unable to maintain the correct shape. To avoid the deformations of their very thin X-ray optics during the integration process we adopt two stiffening rings with a good roundness. In this article the procedure used for the first three prototypes of the Simbol-X optics is presented with a description of the problems involved and with an analysis of the degradation of the performances during the integration. This analysis has been performed with the UV vertical bench measurements at INAF-OAB.

Epitaxial thin film growth in outer space

NASA Technical Reports Server (NTRS)

Ignatiev, Alex; Chu, C. W.

1988-01-01

A new concept for materials processing in space exploits the ultravacuum component of space for thin-film epitaxial growth. The unique LEO space environment is expected to yield 10-ftorr or better pressures, semiinfinite pumping speeds, and large ultravacuum volume (about 100 cu m) without walls. These space ultravacuum properties promise major improvement in the quality, unique nature, and throughput of epitaxially grown materials, including semiconductors, magnetic materials, and thin-film high-temperature superconductors.

Effects of cluster thinning on vine photosynthesis, berry ripeness and flavonoid composition of Cabernet Sauvignon.

PubMed

Wang, Yu; He, Yan-Nan; Chen, Wei-Kai; He, Fei; Chen, Wu; Cai, Xiao-Dong; Duan, Chang-Qing; Wang, Jun

2018-05-15

Cluster thinning is a common practice for regulating vine yield and grape quality. The effects of cluster thinning on vine photosynthesis, berry ripeness and flavonoid composition of V. vinifera L. Cabernet Sauvignon were evaluated during two seasons. Half of the clusters were removed at pea-size and veraison relative to two controls, respectively. Both cluster thinning treatments significantly increased pruning weight and decreased yield. No effects of cluster thinning on berry growth, ripeness and flavonol composition were observed. Early cluster thinning decreased the photosynthetic rate at pea-size, but the effect diminished at post-veraison. Early cluster thinning significantly promoted the biosynthesis of anthocyanins but decreased the proportion of 3'5'-hydroxylated and acylated anthocyanins at veraison. Late cluster thinning decreased the proportions of 3'5'-hydroxylated and acylated anthocyanins. Additionally, Cluster thinning showed inconsistent effects on flavan-3-ol composition over the two seasons. Copyright © 2017 Elsevier Ltd. All rights reserved.

Qualities of a psychiatric mentor: a quantitative Singaporean survey.

PubMed

Tor, Phern-Chern; Goh, Lee-Gan; Ang, Yong-Guan; Lim, Leslie; Winslow, Rasaiah-Munidasa; Ng, Beng-Yeong; Wong, Sze-Tai; Ng, Tse-Pin; Kia, Ee-Heok

2011-11-01

Psychiatric mentors are an important part of the new, seamless training program in Singapore. There is a need to assess the qualities of a good psychiatric mentor vis-à-vis those of a good psychiatrist. An anonymous survey was sent out to all psychiatry trainees and psychiatrists in Singapore to assess quantitatively the relative importance of 40 qualities for a good psychiatrist and a good mentor. The response rate was 48.7% (74/152). Factor analysis showed four themes among the qualities assessed (professional, personal values, relationship, academic-executive). A good mentor is defined by professional, relationship, and personal-values qualities. Mentors have significantly higher scores than psychiatrists for two themes (relationship and academic-executive). Being a good mentor, in Asia, means being a good psychiatrist first and foremost but also requires additional relationship and academic-executive skills. Mentors should be formally trained in these additional skills that were not part of the psychiatric curriculum.

A method to monitor the quality of ultra-thin nitride for trench DRAM with a buried strap structure

NASA Astrophysics Data System (ADS)

Wu, Yung-Hsien; Wang, Chun-Yao; Chang, Ian; Kao, Chien-Kang; Kuo, Chia-Ming; Ku, Alex

2007-02-01

A new approach to monitor the quality of an ultra-thin nitride film has been proposed. The nitride quality is monitored by observing the oxide thickness for the nitride film after wet oxidation since the resistance to oxidation strongly depends on its quality. To obtain a stable oxide thickness without interference from extrinsic factors for process monitoring, monitor wafers without dilute HF solution clean are suggested because the native-oxide containing surface is less sensitive to oxygen and therefore forms the nitride film with stable quality. In addition, the correlation between variable retention time (VRT) performance of a real dynamic random access memory (DRAM) product and oxide thickness from different nitride process temperatures can be successfully explained and this correlation can also be used to establish the appropriate oxide thickness range for process monitoring.

Optical-to-optical interface device. [consisting of two transparent electrodes on glass substrates that enclose thin film photoconductor and thin layer of nematic liquid crystal

NASA Technical Reports Server (NTRS)

Jacobson, A. D.

1973-01-01

Studies were conducted on the performance of a photoactivated dc liquid crystal light valve. The dc light valve is a thin film device that consists of two transparent electrodes, deposited on glass substrates, that enclose a thin film photoconductor (cadmium sulfide) and a thin layer of a nematic liquid crystal that operates in the dynamic scattering mode. The work was directed toward application of the light valve to high resolution non-coherent light to coherent light image conversion. The goal of these studies was to improve the performance and quality of the already existing dc light valve device and to evaluate quantitatively the properties and performance of the device as they relate to the coherent optical data processing application. As a result of these efforts, device sensitivity was improved by a factor of ten, device resolution was improved by a factor of three, device lifetime was improved by two-orders of magnitude, undesirable secondary liquid crystal scattering effects were eliminated, the scattering characteristics of the liquid crystal were thoroughly documented, the cosmetic quality of the devices was dramatically improved, and the performance of the device was fully documented.

Ion Beam Assisted Deposition of Thin Epitaxial GaN Films.

PubMed

Rauschenbach, Bernd; Lotnyk, Andriy; Neumann, Lena; Poppitz, David; Gerlach, Jürgen W

2017-06-23

The assistance of thin film deposition with low-energy ion bombardment influences their final properties significantly. Especially, the application of so-called hyperthermal ions (energy <100 eV) is capable to modify the characteristics of the growing film without generating a large number of irradiation induced defects. The nitrogen ion beam assisted molecular beam epitaxy (ion energy <25 eV) is used to deposit GaN thin films on (0001)-oriented 6H-SiC substrates at 700 °C. The films are studied in situ by reflection high energy electron diffraction, ex situ by X-ray diffraction, scanning tunnelling microscopy, and high-resolution transmission electron microscopy. It is demonstrated that the film growth mode can be controlled by varying the ion to atom ratio, where 2D films are characterized by a smooth topography, a high crystalline quality, low biaxial stress, and low defect density. Typical structural defects in the GaN thin films were identified as basal plane stacking faults, low-angle grain boundaries forming between w-GaN and z-GaN and twin boundaries. The misfit strain between the GaN thin films and substrates is relieved by the generation of edge dislocations in the first and second monolayers of GaN thin films and of misfit interfacial dislocations. It can be demonstrated that the low-energy nitrogen ion assisted molecular beam epitaxy is a technique to produce thin GaN films of high crystalline quality.

CT, MR, and ultrasound image artifacts from prostate brachytherapy seed implants: The impact of seed size

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertson, Andrew K. H.; Basran, Parminder S.; Thomas, Steven D.

Purpose: To investigate the effects of brachytherapy seed size on the quality of x-ray computed tomography (CT), ultrasound (US), and magnetic resonance (MR) images and seed localization through comparison of the 6711 and 9011 {sup 125}I sources. Methods: For CT images, an acrylic phantom mimicking a clinical implantation plan and embedded with low contrast regions of interest (ROIs) was designed for both the 0.774 mm diameter 6711 (standard) and the 0.508 mm diameter 9011 (thin) seed models (Oncura, Inc., and GE Healthcare, Arlington Heights, IL). Image quality metrics were assessed using the standard deviation of ROIs between the seeds andmore » the contrast to noise ratio (CNR) within the low contrast ROIs. For US images, water phantoms with both single and multiseed arrangements were constructed for both seed sizes. For MR images, both seeds were implanted into a porcine gel and imaged with pelvic imaging protocols. The standard deviation of ROIs and CNR values were used as metrics of artifact quantification. Seed localization within the CT images was assessed using the automated seed finder in a commercial brachytherapy treatment planning system. The number of erroneous seed placements and the average and maximum error in seed placements were recorded as metrics of the localization accuracy. Results: With the thin seeds, CT image noise was reduced from 48.5 {+-} 0.2 to 32.0 {+-} 0.2 HU and CNR improved by a median value of 74% when compared with the standard seeds. Ultrasound image noise was measured at 50.3 {+-} 17.1 dB for the thin seed images and 50.0 {+-} 19.8 dB for the standard seed images, and artifacts directly behind the seeds were smaller and less prominent with the thin seed model. For MR images, CNR of the standard seeds reduced on average 17% when using the thin seeds for all different imaging sequences and seed orientations, but these differences are not appreciable. Automated seed localization required an average ({+-}SD) of 7.0 {+-} 3.5 manual corrections in seed positions for the thin seed scans and 3.0 {+-} 1.2 manual corrections in seed positions for the standard seed scans. The average error in seed placement was 1.2 mm for both seed types and the maximum error in seed placement was 2.1 mm for the thin seed scans and 1.8 mm for the standard seed scans. Conclusions: The 9011 thin seeds yielded significantly improved image quality for CT and US images but no significant differences in MR image quality.« less

Large-area SnO{sub 2}: F thin films by offline APCVD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yan; Wu, Yucheng, E-mail: ycwu@hfut.edu.cn; Qin, Yongqiang

2011-08-15

Highlights: {yields} Large-area (1245 mm x 635 mm) FTO thin films were successfully deposited by offline APCVD process. {yields} The as-prepared FTO thin films with sheet resistance 8-11 {Omega}/{open_square} and direct transmittance more than 83% exhibited better than that of the online ones. {yields} The maximum quantum efficiency of the solar cells based on offline FTO substrate was 0.750 at wavelength 540 nm. {yields} The power of the solar modules using the offline FTO as glass substrates was 51.639 W, higher than that of the modules based on the online ones. -- Abstract: In this paper, we reported the successfulmore » preparation of fluorine-doped tin oxide (FTO) thin films on large-area glass substrates (1245 mm x 635 mm x 3 mm) by self-designed offline atmospheric pressure chemical vapor deposition (APCVD) process. The FTO thin films were achieved through a combinatorial chemistry approach using tin tetrachloride, water and oxygen as precursors and Freon (F-152, C2H4F2) as dopant. The deposited films were characterized for crystallinity, morphology (roughness) and sheet resistance to aid optimization of materials suitable for solar cells. We got the FTO thin films with sheet resistance 8-11 {Omega}/{open_square} and direct transmittance more than 83%. X-ray diffraction (XRD) characterization suggested that the as-prepared FTO films were composed of multicrystal, with the average crystal size 200-300 nm and good crystallinity. Further more, the field emission scanning electron microscope (FESEM) images showed that the films were produced with good surface morphology (haze). Selected samples were used for manufacturing tandem amorphous silicon (a-Si:H) thin film solar cells and modules by plasma enhanced chemical vapor deposition (PECVD). Compared with commercially available FTO thin films coated by online chemical vapor deposition, our FTO coatings show excellent performance resulting in a high quantum efficiency yield for a-Si:H solar cells and ideal open voltage and short circuit current for a-Si:H solar modules.« less

Silicon-integrated thin-film structure for electro-optic applications

DOEpatents

McKee, Rodney A.; Walker, Frederick Joseph

2000-01-01

A crystalline thin-film structure suited for use in any of an number of electro-optic applications, such as a phase modulator or a component of an interferometer, includes a semiconductor substrate of silicon and a ferroelectric, optically-clear thin film of the perovskite BaTiO.sub.3 overlying the surface of the silicon substrate. The BaTiO.sub.3 thin film is characterized in that substantially all of the dipole moments associated with the ferroelectric film are arranged substantially parallel to the surface of the substrate to enhance the electro-optic qualities of the film.

Sample preparation and EFTEM of Meat Samples for Nanoparticle Analysis in Food

NASA Astrophysics Data System (ADS)

Lari, L.; Dudkiewicz, A.

2014-06-01

Nanoparticles are used in industry for personal care products and the preparation of food. In the latter application, their functions include the prevention of microbes' growth, increase of the foods nutritional value and sensory quality. EU regulations require a risk assessment of the nanoparticles used in foods and food contact materials before the products can reach the market. However, availability of validated analytical methodologies for detection and characterisation of the nanoparticles in food hampers appropriate risk assessment. As part of a research on the evaluation of the methods for screening and quantification of Ag nanoparticles in meat we have tested a new TEM sample preparation alternative to resin embedding and cryo-sectioning. Energy filtered TEM analysis was applied to evaluate thickness and the uniformity of thin meat layers acquired at increasing input of the sample demonstrating that the protocols used ensured good stability under the electron beam, reliable sample concentration and reproducibility.

Phase locked multiple rings in the radiation pressure ion acceleration process

NASA Astrophysics Data System (ADS)

Wan, Y.; Hua, J. F.; Pai, C.-H.; Li, F.; Wu, Y. P.; Lu, W.; Zhang, C. J.; Xu, X. L.; Joshi, C.; Mori, W. B.

2018-04-01

Laser contrast plays a crucial role for obtaining high quality ion beams in the radiation pressure ion acceleration (RPA) process. Through one- and two-dimensional particle-in-cell (PIC) simulations, we show that a plasma with a bi-peak density profile can be produced from a thin foil on the effects of a picosecond prepulse, and it can then lead to distinctive modulations in the ion phase space (phase locked double rings) when the main pulse interacts with the target. These fascinating ion dynamics are mainly due to the trapping effect from the ponderomotive potential well of a formed moving standing wave (i.e. the interference between the incoming pulse and the pulse reflected by a slowly moving surface) at nodes, quite different from the standard RPA process. A theoretical model is derived to explain the underlying mechanism, and good agreements have been achieved with PIC simulations.

Helicity multiplexed broadband metasurface holograms.

PubMed

Wen, Dandan; Yue, Fuyong; Li, Guixin; Zheng, Guoxing; Chan, Kinlong; Chen, Shumei; Chen, Ming; Li, King Fai; Wong, Polis Wing Han; Cheah, Kok Wai; Pun, Edwin Yue Bun; Zhang, Shuang; Chen, Xianzhong

2015-09-10

Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices.

Phase locked multiple rings in the radiation pressure ion acceleration process

DOE PAGES

Wan, Y.; Hua, J. F.; Pai, C. -H.; ...

2018-03-05

Laser contrast plays a crucial role for obtaining high quality ion beams in the radiation pressure ion acceleration (RPA) process. Through one- and two-dimensional particle-in-cell (PIC) simulations, we show that a plasma with a bi-peak density profile can be produced from a thin foil on the effects of a picosecond prepulse, and it can then lead to distinctive modulations in the ion phase space (phase locked double rings) when the main pulse interacts with the target. These fascinating ion dynamics are mainly due to the trapping effect from the ponderomotive potential well of a formed moving standing wave (i.e. themore » interference between the incoming pulse and the pulse reflected by a slowly moving surface) at nodes, quite different from the standard RPA process. Here, a theoretical model is derived to explain the underlying mechanism, and good agreements have been achieved with PIC simulations.« less

Structural-dependent thermal conductivity of aluminium nitride produced by reactive direct current magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belkerk, B. E.; Soussou, A.; Carette, M.

This Letter reports the thermal conductivity of aluminium nitride (AlN) thin-films deposited by reactive DC magnetron sputtering on single-crystal silicon substrates (100) with varying plasma and magnetic conditions achieving different crystalline qualities. The thermal conductivity of the films was measured at room temperature with the transient hot-strip technique for film thicknesses ranging from 100 nm to 4000 nm. The thermal conductivity was found to increase with the thickness depending on the synthesis conditions and film microstructure. The conductivity in the bulk region of the films, so-called intrinsic conductivity, and the boundary resistance were in the range [120-210] W m{sup -1}more » K{sup -1} and [2-30 Multiplication-Sign 10{sup -9}] K m{sup 2} W{sup -1}, respectively, in good agreement with microstructures analysed by x-ray diffraction, high-resolution-scanning-electron-microscopy, and transmission-electron-microscopy.« less

Helicity multiplexed broadband metasurface holograms

PubMed Central

Wen, Dandan; Yue, Fuyong; Li, Guixin; Zheng, Guoxing; Chan, Kinlong; Chen, Shumei; Chen, Ming; Li, King Fai; Wong, Polis Wing Han; Cheah, Kok Wai; Yue Bun Pun, Edwin; Zhang, Shuang; Chen, Xianzhong

2015-01-01

Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices. PMID:26354497

The Fine Wire Technique for Flexor Tenolysis.

PubMed

Rosenblum, Matthew K; Baltodano, Pablo A; Weinberg, Maxene H; Whipple, Lauren A; Gemmiti, Amanda L; Whipple, Richard E

2017-11-01

Flexor tenolysis surgery for flexor digitorum profundus and superficialis adhesions is a common procedure performed by hand surgeons. Releasing these adhered tendons can greatly improve hand function and improve quality of life. Recent evidence, however, has shown that the outcomes of tenolysis surgeries are often suboptimal and can result in relapsing adhesions or even tendon ruptures. This article describes a new technique with potential for reduced complication rates: The Fine Wire Technique for Flexor Tenolysis (FWT). Following FWT, the patient detailed in this article had an excellent recovery of function and no complications: including tendon rupture, infection, hematomas, or any other complications. She reported a major improvement from her preoperative functionality and continues to have this level of success. The wire's thinness allows for a swift tenolysis. The FWT is a new option available to the hand surgeon associated with good functional results. The wire is readily available to the clinician and is also inexpensive.

Preparation and Characterization of Silanes Films to Protect Electrogalvanized Steel

NASA Astrophysics Data System (ADS)

Seré, Pablo R.; Egli, Walter; Di Sarli, Alejandro R.; Deyá, Cecilia

2018-03-01

Silanes are an interesting alternative to chromate-based surface treatments for temporary protection of electrogalvanized steel. In this work, the protective behavior of 3-mercaptopropyltrimethoxysilane (MTMO), 3-aminopropyltriethoxysilane (AMEO), or 3-glycidoxypropyltrimethoxysilane (GLYMO) films applied on electrogalvanized automotive quality steel sheets has been studied. The silane coating morphology, composition, and porosity were characterized by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), x-ray fluorescence, immersion in copper sulfate, and cyclic voltammetry. The corrosion protection was evaluated by polarization curves, electrochemical noise measurements, electrochemical impedance spectrometry, and accelerated humidity chamber tests. The results showed that the silanes protect temporarily electrogalvanized steel from corrosion. MTMO forms a relatively thick and cracked film. AMEO and GLYMO films were so thin that they could not be observed by SEM but silicon was detected by EDS. MTMO provided good temporary protection, being an alternative to replace Cr(VI) as protector of electrogalvanized steel.

Low-pressure CVD-grown β-Ga2O3 bevel-field-plated Schottky barrier diodes

NASA Astrophysics Data System (ADS)

Joishi, Chandan; Rafique, Subrina; Xia, Zhanbo; Han, Lu; Krishnamoorthy, Sriram; Zhang, Yuewei; Lodha, Saurabh; Zhao, Hongping; Rajan, Siddharth

2018-03-01

We report (010)-oriented β-Ga2O3 bevel-field-plated mesa Schottky barrier diodes grown by low-pressure chemical vapor deposition (LPCVD) using a solid Ga precursor and O2 and SiCl4 sources. Schottky diodes with good ideality and low reverse leakage were realized on the epitaxial material. Edge termination using beveled field plates yielded a breakdown voltage of -190 V, and maximum vertical electric fields of 4.2 MV/cm in the center and 5.9 MV/cm at the edge were estimated, with extrinsic R ON of 3.9 mΩ·cm2 and extracted intrinsic R ON of 0.023 mΩ·cm2. The reported results demonstrate the high quality of homoepitaxial LPCVD-grown β-Ga2O3 thin films for vertical power electronics applications, and show that this growth method is promising for future β-Ga2O3 technology.

Li diffusion in epitaxial (11 $bar 2$ 0) ZnO thin films

NASA Astrophysics Data System (ADS)

Wu, P.; Zhong, J.; Emanetoglu, N. W.; Chen, Y.; Muthukumar, S.; Lu, Y.

2004-06-01

Zinc oxide (ZnO) possesses many interesting properties, such as a wide energy bandgap, large photoconductivity, and high excitonic binding energy. Chemical-vapor-deposition-grown ZnO films generally show n-type conductivity. A compensation doping process is needed to achieve piezoelectric ZnO, which is needed for surface acoustic wave (SAW), bulk acoustic wave, and micro-electromechanical system devices. In this work, a gas-phase diffusion process is developed to achieve piezoelectric (11bar 20) ZnO films. Comparative x-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements confirmed that high crystal quality and good surface morphology were preserved after diffusion. Photoluminescence (PL) measurements show a broad band emission with a peak wavelength at ˜580 nm, which is associated with Li doping. The SAW, including both Rayleigh-wave and Love-wave modes, is achieved along different directions in piezoelectric (11bar 20) ZnO films grown on an r-plane sapphire substrate.

Phase locked multiple rings in the radiation pressure ion acceleration process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Y.; Hua, J. F.; Pai, C. -H.

Laser contrast plays a crucial role for obtaining high quality ion beams in the radiation pressure ion acceleration (RPA) process. Through one- and two-dimensional particle-in-cell (PIC) simulations, we show that a plasma with a bi-peak density profile can be produced from a thin foil on the effects of a picosecond prepulse, and it can then lead to distinctive modulations in the ion phase space (phase locked double rings) when the main pulse interacts with the target. These fascinating ion dynamics are mainly due to the trapping effect from the ponderomotive potential well of a formed moving standing wave (i.e. themore » interference between the incoming pulse and the pulse reflected by a slowly moving surface) at nodes, quite different from the standard RPA process. Here, a theoretical model is derived to explain the underlying mechanism, and good agreements have been achieved with PIC simulations.« less

Dip-coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

NASA Technical Reports Server (NTRS)

Zook, J. D.; Heaps, J. D.; Maciolek, R. B.; Koepke, B. G.; Gutter, C. D.; Schuldt, S. B.

1977-01-01

The objective of this research program is to investigate the technical and economic feasibility of producing solar-cell-quality sheet silicon by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. The past quarter demonstrated significant progress in several areas. Seeded growth of silicon-on-ceramic (SOC) with an EFG ribbon seed was demonstrated. Different types of mullite were successfully coated with silicon. A new method of deriving minority carrier diffusion length, L sub n from spectral response measurements was evaluated. ECOMOD cost projections were found to be in good agreement with the interim SAMIS method proposed by JPL. On the less positive side, there was a decrease in cell performance which we believe to be due to an unidentified source of impurities.

Synthesis and annealing study of RF sputtered ZnO thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Shushant Kumar, E-mail: singhshushant86@gmail.com; Sharma, Himanshu; Singhal, R.

2016-05-23

In this paper, we have investigated the annealing effect on optical and structural properties of ZnO thin films, synthesized by RF magnetron sputtering. ZnO thin films were deposited on glass and silicon substrates simultaneously at a substrate temperature of 300 °C using Argon gas in sputtering chamber. Thickness of as deposited ZnO thin film was found to be ~155 nm, calculated by Rutherford backscattering spectroscopy (RBS). These films were annealed at 400 °C and 500 °C temperature in the continuous flow of oxygen gas for 1 hour in tube furnace. X-ray diffraction analysis confirmed the formation of hexagonal wurtzite structuremore » of ZnO thin film along the c-axis (002) orientation. Transmittance of thin films was increased with increasing the annealing temperature estimated by UV-visible transmission spectroscopy. Quality and texture of the thin films were improved with annealing temperature, estimated by Raman spectroscopy.« less

Fabrication of ATO/Graphene Multi-layered Transparent Conducting Thin Films

NASA Astrophysics Data System (ADS)

Li, Na; Chen, Fei; Shen, Qiang; Wang, Chuanbin; Zhang, Lianmeng

2013-03-01

A novel transparent conducting oxide based on the ATO/graphene multi-layered thin films has been developed to satisfy the application of transparent conductive electrode in solar cells. The ATO thin films are prepared by pulsed laser deposition method with high quality, namely the sheet resistance of 49.5 Ω/sq and average transmittance of 81.9 %. The prepared graphene sheet is well reduced and shows atomically thin, spotty distributed appearance on the top of the ATO thin films. The XRD and optical micrographs are used to confirm the successfully preparation of the ATO/graphene multi-layered thin films. The Hall measurements and UV-Vis spectrophotometer are conducted to evaluate the sheet resistance and optical transmittance of the innovative structure. It is found that graphene can improve the electrical properties of the ATO thin films with little influence on the optical transmittance.

Simple method for forming thin-wall pressure vessels

NASA Technical Reports Server (NTRS)

Erickson, A. L.; Guist, L. R.

1972-01-01

Application of internal hydrostatic pressure to seam-welded circular cylindrical tanks having corner-welded, flat, circular ends forms large thin-walled high quality tanks. Form limits expansion of cylindrical portion of final tank while hemispherical ends develop freely; no external form or restraint is required to fabricate spherical tanks.

Thin film processing of photorefractive BaTiO3

NASA Technical Reports Server (NTRS)

Schuster, Paul R.; Potember, Richard S.

1991-01-01

The principle objectives of this ongoing research involve the preparation and characterization of polycrystalline single-domain thin films of BaTiO3 for photorefractive applications. These films must be continuous, free of cracks, and of high optical quality. The two methods proposed are sputtering and sol-gel related processing.

Basic and Applied Research in the Field of Electronics and Communications.

DTIC Science & Technology

1986-03-19

301 Theses ?9. N. P. Vlannes, "Optical and :nduction Probing of aSagnezos:atic -vaves in Thin Films of Yttrium :ron Garnet ," ?H D Thesis, Departrment f...used in high-quality, single-crystal ferrite thin films . Both experimental and theoretical analyses verified several new transmission modes, and...4-amD :urrent at 160 kilohertz. (References: 52, 61, 134). X’NM. Control of Microstructure in Thin- Film Electronic Materials Professor C. Thompson

The effect of initial number of trees per acre and thinning densities on timber yields from red pine plantations in the Lake States.

Treesearch

Allen L. Lundgren

1981-01-01

Describes an analysis of initial density and subsequent thinning options for red pine (Pinus resinosa Ait.) plantations in the Lake States. Results showed that the initial number of established trees per acres has a major impact on the amount and quality of timber product yields, with 200 trees per acre (500/ha) thinned to 120 square feet of basal area per acre (27.5...

Growth of young saligna eucalyptus in Hawaii: 6 years after thinning

Treesearch

Craig D. Whitesell

1975-01-01

The effect of thinning on growth rate and quality of a 6-year-old Eucalyptus saligna Sm. stand on Maui, Hawaii, was studied by testing three levels of thinning from below: 100, 85, and 70 sq ft per acre (23, 19.5, and 16 sq m/ha). The stand had an average basal area of 102 sq ft per acre (23 sq m/ha). Initial spacing was about 10 by 10 feet. During...

High-performance formamidinium-based perovskite solar cells via microstructure-mediated δ-to-α phase transformation

DOE PAGES

Liu, Tanghao; Zong, Yingxia; Zhou, Yuanyuan; ...

2017-03-14

The δ → α phase transformation is a crucial step in the solution-growth process of formamidinium-based lead triiodide (FAPbI 3) hybrid organic–inorganic perovskite (HOIP) thin films for perovskite solar cells (PSCs). Because the addition of cesium (Cs) stabilizes the α phase of FAPbI 3-based HOIPs, here our research focuses on FAPbI 3(Cs) thin films. We show that having a large grain size in the δ-FAPbI 3(Cs) non-perovskite intermediate films is essential for the growth of high-quality α-FAPbI 3(Cs) HOIP thin films. Here grain coarsening and phase transformation occur simultaneously during the thermal annealing step. A large starting grain size inmore » the δ-FAPbI 3(Cs) thin films suppresses grain coarsening, precluding the formation of voids at the final α-FAPbI 3(Cs)–substrate interfaces. PSCs based on the interface void-free α-FAPbI 3(Cs) HOIP thin films are much more efficient and stable in the ambient atmosphere. This interesting finding inspired us to develop a simple room-temperature aging method for preparing coarse-grained δ-FAPbI 3(Cs) intermediate films, which are subsequently converted to coarse-grained, high-quality α-FAPbI 3(Cs) HOIP thin films. As a result, this study highlights the importance of microstructure meditation in the processing of formamidinium-based PSCs.« less

Silicon Nitride Deposition for Flexible Organic Electronic Devices by VHF (162 MHz)-PECVD Using a Multi-Tile Push-Pull Plasma Source.

PubMed

Kim, Ki Seok; Kim, Ki Hyun; Ji, You Jin; Park, Jin Woo; Shin, Jae Hee; Ellingboe, Albert Rogers; Yeom, Geun Young

2017-10-19

Depositing a barrier film for moisture protection without damage at a low temperature is one of the most important steps for organic-based electronic devices. In this study, the authors investigated depositing thin, high-quality SiN x film on organic-based electronic devices, specifically, very high-frequency (162 MHz) plasma-enhanced chemical vapor deposition (VHF-PECVD) using a multi-tile push-pull plasma source with a gas mixture of NH 3 /SiH 4 at a low temperature of 80 °C. The thin deposited SiN x film exhibited excellent properties in the stoichiometry, chemical bonding, stress, and step coverage. Thin film quality and plasma damage were investigated by the water vapor transmission rate (WVTR) and by electrical characteristics of organic light-emitting diode (OLED) devices deposited with SiN x , respectively. The thin deposited SiN x film exhibited a low WVTR of 4.39 × 10 -4  g (m 2 · day) -1 for a single thin (430 nm thick) film SiN x and the electrical characteristics of OLED devices before and after the thin SiN x film deposition on the devices did not change, which indicated no electrical damage during the deposition of SiN x on the OLED device.

Is cryopreservation of embryos a legitimate surrogate marker of embryo quality in studies of assisted reproductive technology conducted using national databases?

PubMed

Stern, Judy E; Lieberman, Ellice S; Macaluso, Maurizio; Racowsky, Catherine

2012-04-01

To investigate whether cryopreservation of supernumerary embryos is a good surrogate for embryo quality. Retrospective study of 6,859 assisted reproductive technology (ART) cycles from women aged <35 years with two fresh day 3 embryos transferred. National Society for Assisted Reproductive Technology Clinic Outcome Reporting System data from 2006-2008. Women undergoing ART. None. Embryo quality (good, fair, or poor), cell number, and live births were compared for cycles with and without cryopreservation, using χ(2) to evaluate statistical significance. The association of freezing with embryo quality was examined using multiple logistic regression after adjusting for confounders (patient age, oocyte yield, intracytoplasmic sperm injection [ICSI], assisted hatching, male factor infertility). Cycles with cryopreservation were more likely to have two embryos of good quality transferred (81.3% vs. 48.5%) and had more 8-cell embryos transferred (76.0% vs. 50.1%). Relative to cycles with two good embryos (good-good), the adjusted odds ratios (OR) for cryopreservation were: good-fair (OR = 0.301, 95% confidence interval [CI] = 0.257-0.354), fair-fair (OR = 0.308, 95% CI = 0.258-0.367), and any poor (OR = 0.058, 95% CI = 0.040-0.083). The live birth rate was 52.4% for cycles with freezing and 40.6% for cycles without. Embryo quality and cell number were both associated with embryo cryopreservation. However, although cryopreservation was a strong marker for good quality, not having cryopreservation did not reliably indicate poor quality, as almost half of those cycles had two good quality embryos. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Investigation of graphene-on-metal substrates for SPR-based sensor using finite-difference time domain.

PubMed

Said, Fairus Atida; Menon, Pulliyaseri Susthitha; Rajendran, Venkatachalam; Shaari, Sahbudin; Majlis, Burhanuddin Y

2017-12-01

In this study, the authors investigated the effects of a single layer graphene as a coating layer on top of metal thin films such as silver, gold, aluminum and copper using finite-difference time domain method. To enhance the resolution of surface plasmon resonance (SPR) sensor, it is necessary to increase the SPR reflectivity and decrease the full-width-half maximum (FWHM) of the SPR curve so that there is minimum uncertainty in the determination of the resonance dip. Numerical data was verified with analytical and experimental data where all the data were in good agreement with resonance angle differing in <10% due to noise present in components such as humidity and temperature. In further analysis, reflectivity and FWHM were compared among four types of metal with various thin film thicknesses where graphene was applied on top of the metal layers, and data was compared against pure conventional metal thin films. A 60 nm-thick Au thin film results in higher performance with reflectivity of 92.4% and FWHM of 0.88° whereas single layer graphene-on-60 nm-thick Au gave reflectivity of 91.7% and FWHM of 1.32°. However, a graphene-on-40 nm-thick Ag also gave good performance with narrower FWHM of 0.88° and reflection spectra of 89.2%.

Nanocrystalline mesoporous SMO thin films prepared by sol gel process for MEMS-based hydrogen sensor

NASA Astrophysics Data System (ADS)

Gong, Jianwei; Fei, Weifeng; Seal, Sudipta; Chen, Quanfang

2004-01-01

MEMS based SnO2 gas sensor with sol gel synthesized mesoporous nanocrystalline (<10 nm) semiconductor thin (100~150 nm) film has been recently developed. The SnO2 nano film is fabricated with the combination of polymeric sol gel chemistry with block copolymers used for structure directing agents. The novel hydrogen sensor has a fast response time (1s) and quick recovery time (3s), as well as good sensitivity (about 90%), comparing to other hydrogen sensors developed. The improved capabilities are credited to the large surface to volume ratio of gas sensing thin film with nano sized porous surface topology, which can greatly increase the sensitivity even at relatively low working temperature. The gas sensing film is deposited onto a thin dielectric membrane of low thermal conductivity, which provides good thermal isolation between substrate and the gas-sensitive heated area on the membrane. In this way the power consumption can be kept very low. Since the fabrication process is completely compatible with IC industry, it makes mass production possible and greatly reduces the cost. The working temperature of the new sensor can be reduced as low as 100°C. The low working temperature posse advantages such as lower power consumption, lower thermal induced signal shift as well as safe detection in certain environments where temperature is strictly limited.

Standardization of blood smears prepared in transparent acetate: an alternative method for the microscopic diagnosis of malaria.

PubMed

Mello, Marcia B C; Luz, Francisco C; Leal-Santos, Fabio A; Alves, Eduardo R; Gasquez, Thamires M; Fontes, Cor J F

2014-06-17

Due to students' initial inexperience, slides are frequently broken and blood smears are damaged in microscopy training, leading to the need for their constant replacement. To minimize this problem a method of preparing blood smears on transparent acetate sheets was developed with the goal of implementing appropriate and more readily available teaching resources for the microscopic diagnosis of malaria. Acetate sheets derived from polyester were used to standardize the preparation and staining of thin and thick blood smears on transparent acetate sheets. Thick and thin blood smears were also prepared using the conventional method on glass slides. The staining was conducted using Giemsa staining for the thick and thin smears. Microscopic examination (1,000x) of the thin and thick blood smears prepared on transparent acetate produced high-quality images for both the parasites and the blood cells. The smears showed up on a clear background and with minimal dye precipitation. It was possible to clearly identify the main morphological characteristics of Plasmodium, neutrophils and platelets. After 12 months of storage, there was no change in image quality or evidence of fungal colonization. Preparation of thin and thick blood smears in transparent acetate for the microscopic diagnosis of malaria does not compromise the morphological and staining characteristics of the parasites or blood cells. It is reasonable to predict the applicability of transparent acetate in relevant situations such as the training of qualified professionals for the microscopic diagnosis of malaria and the preparation of positive specimens for competency assessment (quality control) of professionals and services involved in the diagnosis of malaria.

a Brief Survey on Basic Properties of Thin Films for Device Application

NASA Astrophysics Data System (ADS)

Rao, M. C.; Shekhawat, M. S.

Thin film materials are the key elements of continued technological advances made in the fields of optoelectronic, photonic and magnetic devices. Thin film studies have directly or indirectly advanced many new areas of research in solid state physics and chemistry which are based on phenomena uniquely characteristic of the thickness, geometry and structure of the film. The processing of materials into thin films allows easy integration into various types of devices. Thin films are extremely thermally stable and reasonably hard, but they are fragile. On the other hand organic materials have reasonable thermal stability and are tough, but are soft. Thin film mechanical properties can be measured by tensile testing of freestanding films and by the micro beam cantilever deflection technique, but the easiest way is by means of nanoindentation. Optical experiments provide a good way of examining the properties of semiconductors. Particularly measuring the absorption coefficient for various energies gives information about the band gaps of the material. Thin film materials have been used in semiconductor devices, wireless communications, telecommunications, integrated circuits, rectifiers, transistors, solar cells, light-emitting diodes, photoconductors and light crystal displays, lithography, micro- electromechanical systems (MEMS) and multifunctional emerging coatings, as well as other emerging cutting technologies.

Strain, temperature, and electric-field effects on the phase transition and piezoelectric responses of K0.5Na0.5NbO3 thin films

NASA Astrophysics Data System (ADS)

Zhou, Meng-Jun; Wang, Jian-Jun; Chen, Long-Qing; Nan, Ce-Wen

2018-04-01

A KNbO3-based solid solution system is environmentally friendly with good electromechanical performance. This work established the misfit strain-strain and temperature-strain phase diagrams for K0.5Na0.5NbO3 thin films and calculated the polarization switching, phase transition, and piezoelectric responses of K0.5Na0.5NbO3 thin films under various strains, temperatures, and electric fields. The results show that the piezoelectric coefficient d33 can be enhanced near the phase boundaries. For the ferroelectric phase with a nonzero out-of-plane polarization component, an optimal electric field is identified for maximizing d33, which is desired in applications such as thin-film piezoelectric micro-electromechanical systems, transducers for ultrasound medical imaging, and energy harvesting. The present results are expected to provide guidance for the future experimental study of KxNa1-xNbO3 thin films and the optimization of ferroelectric thin film-based devices.

Epitaxial growth and dielectric properties of Pb0.4Sr0.6TiO3 thin films on (00l)-oriented metallic Li0.3Ni0.7O2 coated MgO substrates

NASA Astrophysics Data System (ADS)

Li, X. T.; Du, P. Y.; Mak, C. L.; Wong, K. H.

2007-06-01

Highly (00l)-oriented Li0.3Ni0.7O2 thin films have been fabricated on (001) MgO substrates by pulsed laser deposition. The Pb0.4Sr0.6TiO3 (PST40) thin film deposited subsequently also shows a significant (00l)-oriented texture. Both the PST40 and Li0.3Ni0.7O2 have good epitaxial behavior. The epitaxial growth of the PST40 thin film is more perfect with the Li0.3Ni0.7O2 buffer layer due to the less distortion in the film. The dielectric tunability of the PST40 thin film with Li0.3Ni0.7O2 buffer layer therefore reaches 70%, which is 75% higher than that without Li0.3Ni0.7O2 buffer layer, and the dielectric loss of the PST40 thin film is 0.06.

Lα and Mαβ X-ray production cross-sections of Bi by 6-30 keV electron impact

NASA Astrophysics Data System (ADS)

Liang, Y.; Xu, M. X.; Yuan, Y.; Wu, Y.; Qian, Z. C.; Chang, C. H.; Mei, C. S.; Zhu, J. J.; Moharram, K.

2017-12-01

In this paper, the Lα and Mαβ X-ray production cross-sections for Bi impacted by 6-30 keV electron have been measured. The experiments were performed at a Scanning Electron Microscope equipped with a silicon drift detector. The thin film with thick C substrate and the thin film deposited on self-supporting thin C film were both used as the targets to make a comparison. For the thick carbon substrate target, the Monte Carlo method has been used to eliminate the contribution of backscattering particles. The measured data are compared with the DWBA theoretical model and the experimental results in the literature. The experimental data for the thin film with thick C substrate target and the thin film deposited on self-supporting thin C film target are within reasonable gaps. The DWBA theoretical model gives good fit to the experimental data both for L- and M- shells. Besides, we also analyze the reasons why the discrepancies exist between our measurements and the experimental results in the literature.

Structural and spectroscopic analysis of ex-situ annealed RF sputtered aluminium doped zinc oxide thin films

NASA Astrophysics Data System (ADS)

Otieno, Francis; Airo, Mildred; Erasmus, Rudolph M.; Billing, David G.; Quandt, Alexander; Wamwangi, Daniel

2017-08-01

Aluminium doped zinc oxide thin films are prepared by Radio Frequency magnetron sputtering in pure argon atmosphere at 100 W. The structural results reveal good film adhesion on a silicon substrate (001). The thin films were then subjected to heat treatment in a furnace under ambient air. The structural, morphological, and optical properties of the thin films as a function of deposition time and annealing temperatures have been investigated using Grazing incidence X-Ray Diffraction (GIXRD), Atomic Force Microscopy, and Scanning Electronic Microscopy. The photoluminescence properties of the annealed films showed significant changes in the optical properties attributed to mid gap defects. Annealing increases the crystallite size and the roughness of the film. The crystallinity of the films also improved as evident from the Raman and XRD studies.

Advantages of thin silicon solar cells for use in space

NASA Technical Reports Server (NTRS)

Denman, O. S.

1978-01-01

A system definition study on the Solar Power Satellite System showed that a thin, 50 micrometers, silicon solar cell has significant advantages. The advantages include a significantly lower performance degradation in a radiation environment and high power-to-mass ratios. The advantages of such cells for an employment in space is further investigated. Basic questions concerning the operation of solar cells are considered along with aspects of radiation induced performance degradation. The question arose in this connection how thin a silicon solar cell had to be to achieve resistance to radiation degradation and still have good initial performance. It was found that single-crystal silicon solar cells could be as thin as 50 micrometers and still develop high conversion efficiencies. It is concluded that the use of 50 micrometer silicon solar cells in space-based photovoltaic power systems would be advantageous.

Superthin Solar Cells Based on AIIIBV/Ge Heterostructures

NASA Astrophysics Data System (ADS)

Pakhanov, N. A.; Pchelyakov, O. P.; Vladimirov, V. M.

2017-11-01

A comparative analysis of the prospects of creating superthin, light-weight, and highly efficient solar cells based on AIIIBV/InGaAs and AIIIBV/Ge heterostructures is performed. Technological problems and prospects of each variant are discussed. A method of thinning of AIIIBV/Ge heterostructures with the use of an effective temporary carrier is proposed. The method allows the process to be performed almost with no risk of heterostructure fracture, thinning of the Ge junction down to several tens of micrometers (or even several micrometers), significant enhancement of the yield of good structures, and also convenient and reliable transfer of thinned solar cells to an arbitrary light and flexible substrate. Such a technology offers a possibility of creating high-efficiency thin and light solar cells for space vehicles on the basis of mass-produced AIIIBV/Ge heterostructures.

Gold-carbon composite thin films for electrochemical gas sensor prepared by reactive plasma sputtering

NASA Astrophysics Data System (ADS)

Okamoto, A.; Suzuki, Y.; Yoshitake, M.; Ogawa, S.; Nakano, N.

1997-01-01

We have investigated the properties of gold-carbon composite thin films prepared by a plasma sputtering deposition using argon and methane mixture gas. These composite films have an uneven surface in submicron scale or consist of nano-scale particles of gold polycrystalline. Such morphological properties can be controlled by the sputtering voltage and the partial pressure of methane gas. The working electrode of electrochemical gas sensor has needed a stable gas sensitivity and a good gas selectivity. Our composite film is one of the excellent candidates for a thin film working electrode of electrochemical gas sensor. It is described that the output current of sensor is related to the preparation conditions of the thin films and increase linearly as the concentration of PH 3 gas ranging from 0.1 to 1.0 ppm is increasing.

ZnS thin films deposition by thermal evaporation for photovoltaic applications

NASA Astrophysics Data System (ADS)

Benyahia, K.; Benhaya, A.; Aida, M. S.

2015-10-01

ZnS thin films were deposited on glass substrates by thermal evaporation from millimetric crystals of ZnS. The structural, compositional and optical properties of the films are studied by X-ray diffraction, SEM microscopy, and UV-VIS spectroscopy. The obtained results show that the films are pin hole free and have a cubic zinc blend structure with (111) preferential orientation. The estimated optical band gap is 3.5 eV and the refractive index in the visible wavelength ranges from 2.5 to 1.8. The good cubic structure obtained for thin layers enabled us to conclude that the prepared ZnS films may have application as buffer layer in replacement of the harmful CdS in CIGS thin film solar cells or as an antireflection coating in silicon-based solar cells.

Solar collector

DOEpatents

Wilhelm, W.G.

The invention pertains to a flat plate collector that employs high performance thin films. The solar collector of this invention overcomes several problems in this field, such as excessive hardware, cost and reliability, and other prior art drawbacks outlined in the specification. In the preferred form, the apparatus features a substantially rigid planar frame. A thin film window is bonded to one planar side of the frame. An absorber of laminate construction is comprised of two thin film layers that are sealed perimetrically. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. Absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

Synthesis of Germanium-Tin Alloys by Ion Implantation and Pulsed Laser Melting: Towards a Group IV Direct Band Gap Semiconductor

NASA Astrophysics Data System (ADS)

Tran, Tuan Thien

The germanium-tin (Ge1-xSnx) material system is expected to be a direct bandgap group IV semiconductor at a Sn content of 6.5-11 at.%. Hence there has been much interest in preparing such alloys since they are compatible with silicon and they raise the possibility of integrating photonics functionality into silicon circuitry. However, the maximum solid solubility of Sn in Ge is around 0.5 at.% and non-equilibrium deposition techniques such as molecular beam epitaxy or chemical vapour deposition have been used to achieve the desired high Sn concentrations. In this PhD work, the combination of ion implantation and pulsed laser melting (PLM) is demonstrated to be an alternative promising method to produce a highly Sn concentrated alloy with good crystal quality. In initial studies, it was shown that 100 keV Sn implants followed by PLM produced high quality alloys with up to 6.2 at.%Sn but above these Sn concentrations the crystal quality was poor. The structural properties of the ≤6.2 at.% alloys such as soluble Sn concentration, strain distribution and crystal quality have been characterised by Rutherford backscattering spectrometry (RBS), Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The optical properties and electronic band structure have been studied by spectroscopic ellipsometry. The introduction of substitutional Sn into Ge is shown to either induce a splitting between light and heavy hole subbands or lower the conduction band at the Gamma valley. However, at higher implant doses needed to achieve >6.2 at.% Sn, ion-beam-induced porosity in Ge starts to occur, which drastically reduces the retained amount of the implanted Sn and such microstructure also hinders good crystallisation of the material during PLM. To solve this problem, it was shown that a nanometer thick SiO2 layer deposited on the Ge substrate prior to the implantation can largely eliminate the formation of porosity. This capping SiO2 layer also helps to increase the retained Sn concentration up to 15 at.% after implantation, as well as significantly improving the crystal quality of the Ge-Sn layer after PLM. With the use of the capping layer, a good quality Ge-Sn layer with 9 at.% Sn has been achieved using Sn implants at an energy of 120 keV. However, the thin film alloys produced by 100 keV or 120 keV Sn implantation and PLM are shown to contain compressive strain as a result of the large lattice mismatch between Ge and high Sn content alloys. Such strain compromises the tendency towards a direct bandgap material and hence strain relaxation is highly desirable. A thermal stability study showed that the thin film strained material is metastable up to 400°C, but thereafter Sn comes out of solution and diffuses to the material surface. To investigate a possible pathway to the synthesis of strain-relaxed material, a higher Sn implant energy of 350 keV was used to produce thicker alloy layers. XRD/reciprocal space mapping showed that this thicker alloy material is largely relaxed after PLM, which is beneficial for the direct band gap transition and solves the trade-off between higher Sn concentration and compressive strain. However, RBS indicates a sub-surface band of disorder which suggested a possible mechanism for the strain relaxation. Indeed, TEM examination of such material showed the material relaxed via the generation of non-equilibrium threading defects. Despite such defects, a PL study of this relaxed material found photon emission at a wavelength of 2150 nm for 6-9 at.% Sn alloys. However, the intensity of the emission was variable across different Sn content alloys, presumably as a result of the threading defects. A possible pathway to removing such defects is given that may enable both photodetectors and lasers to be fabricated at wavelengths above 2mum.

In-situ ellipsometry: applications to thin film research, development, and production

NASA Astrophysics Data System (ADS)

Kief, Mark T.

1999-07-01

Many industries including the optics industry, semiconductor industry, and magnetic storage industry are deeply rooted in the science and technology of the film materials and thin film based devices. Research in novel thin film systems and the engineering of artificial structures increasingly requires a control on the atomic scale in both thickness and lateral order. Development of the deposition and fabrication processes for these thin film structures requires technical sophistication and efficiency combined with an understanding of the multi-faceted process interactions. The production of these materials necessitates a remarkable degree of control to minimize scrap and assure good performance. Furthermore, in today's industry these operations must occur at an ever accelerating pace. In this article, we will review one technique which can make these challenges more tractable-- insitu ellipsometry. This is a very powerful tool which is capable of characterizing thin film processes in real-time. We review the art and illustrate with novel applications to metal thin film growth. In addition, we will illustrate how information obtained with insitu ellipsometry can predict the end use thin film properties such as the transport properties. In conclusion, further advances in insitu ellipsometry and its applications will be discussed in terms of needs and trends as a tool for thin film research, development and production.

Effects of bacteria on CdS thin films used in technological devices

NASA Astrophysics Data System (ADS)

Alpdoğan, S.; Adıgüzel, A. O.; Sahan, B.; Tunçer, M.; Metin Gubur, H.

2017-04-01

Cadmium sulfide (CdS) thin films were fabricated on glass substrates by the chemical bath deposition method at 70 {}^\\circ \\text{C} considering deposition times ranging from 2 h to 5 h. The optical band gaps of CdS thin films were found to be in the 2.42-2.37 eV range. CdS thin films had uniform spherical nano-size grains which had polycrystalline, hexagonal and cubic phases. The films had a characteristic electrical resistivity of the order of {{10}5} Ω \\text{cm} and n-type conductivity at room condition. CdS thin films were incubated in cultures of B.domonas aeruginosa and Staphylococcus aureus, which exist abundantly in the environment, and form biofilms. SEM images showed that S. aureus and K. pneumonia were detected significantly on the film surfaces with a few of P. aeruginosa and B. subtilis cells attached. CdS thin film surface exhibits relatively good resistance to the colonization of P. aeruginosa and B. subtilis. Optical results showed that the band gap of CdS thin films which interacted with the bacteria is 2.42 \\text{eV} . The crystal structure and electrical properties of CdS thin films were not affected by bacterial adhesion. The antimicrobial effect of CdS nanoparticles was different for different bacterial strains.

Surfactant mediated synthesis of bismuth selenide thin films for photoelectrochemical solar cell applications.

PubMed

Desai, Neha D; Khot, Kishorkumar V; Ghanwat, Vishvanath B; Kharade, Suvarta D; Bhosale, Popatrao N

2018-03-15

In the present report, nanostructured bismuth selenide (Bi 2 Se 3 ) thin films have been successfully deposited by using arrested precipitation technique (APT) at room temperature. The effect of three different surfactants on the optostructural, morphological, compositional and photoelectrochemical properties of Bi 2 Se 3 thin films were investigated. Optical absorption data indicates direct and allowed transition with a band gap energy varied from 1.4 eV to 1.8 eV. The X-ray diffraction pattern (XRD) revealed that Bi 2 Se 3 thin films are crystalline in nature and confirmed rhombohedral crystal structure. SEM micrographs shows morphological transition from interconnected mesh to nanospheres like and finally granular morphology. Surface topography of Bi 2 Se 3 thin films was determined by AFM. Compositional analysis of all samples was carried out by energy dispersive X-ray spectroscopy (EDS). Finally, all Bi 2 Se 3 thin films shows good PEC performance with highest photoconversion efficiency 1.47%. In order to study the stability of Bi 2 Se 3 thin films four cycles are repeated after gap of one week each. Further PEC performance of all Bi 2 Se 3 thin films are also supported by electrochemical impedance (EIS) measurement study. Copyright © 2017 Elsevier Inc. All rights reserved.

Construction and performance of the sTGC and MicroMegas chambers for ATLAS NSW upgrade

NASA Astrophysics Data System (ADS)

Sekhniaidze, G.

2017-03-01

The innermost stations of the current ATLAS muon end-cap system, the Small Wheels, must be upgraded in 2019 to retain their good precision tracking and trigger capabilities in the high background environment expected with the upcoming luminosity increase of the LHC. The New Small Wheels (NSW) will employ two chamber technologies: eight layers of MicroMegas (MM) arranged in two quadruplets, sandwiched between two quadruplets of small-strip Thin Gap Chambers (sTGC) for a total of about 2400 m2 of detection planes. All quadruplets have trapezoidal shapes with surface areas between 1 and 3 m2. Both MM and sTGC systems will independently provide trigger and tracking capabilities. The readout boards are industrially produced for both technologies and an accurate quality control is needed. In order to achieve a 15% transverse momentum resolution for 1 TeV muons, in addition to an excellent intrinsic resolution (010 μm), the mechanical precision of each plane of the assembled modules must be as good as 30 μm along the precision coordinate and 80 μm perpendicular to the chamber. In 2016 the milestone to build the first module-0 prototypes for both technologies has been reached. The construction procedure of the module-0 detectors will be reviewed, along with the results of the quality control checks performed during construction. The module-0 have been measured and subjected to a thorough validation. Results obtained with high-energy particle beams, with cosmic rays and with X-rays will be presented.

Control of Reaction Surface in Low Temperature CVD to Enhance Nucleation and Conformal Coverage

ERIC Educational Resources Information Center

Kumar, Navneet

2009-01-01

The Holy Grail in CVD community is to find precursors that can afford the following: good nucleation on a desired substrate and conformal deposition in high AR features. Good nucleation is not only necessary for getting ultra-thin films at low thicknesses; it also offers films that are smooth at higher thickness values. On the other hand,…

Structural, optical and nonlinear optical studies of AZO thin film prepared by SILAR method for electro-optic applications

NASA Astrophysics Data System (ADS)

Edison, D. Joseph; Nirmala, W.; Kumar, K. Deva Arun; Valanarasu, S.; Ganesh, V.; Shkir, Mohd.; AlFaify, S.

2017-10-01

Aluminium doped (i.e. 3 at%) zinc oxide (AZO) thin films were prepared by simple successive ionic layer adsorption and reaction (SILAR) method with different dipping cycles. The structural and surface morphology of AZO thin films were studied by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical parameters such as, transmittance, band gap, refractive index, extinction coefficient, dielectric constant and nonlinear optical properties of AZO films were investigated. XRD pattern revealed the formation of hexagonal phase ZnO and the intensity of the film was found to increase with increasing dipping cycle. The crystallite size was found to be in the range of 29-37 nm. Scanning Electron Microscope (SEM) images show the presence of small sized grains, revealing that the smoothest surface was obtained at all the films. The EDAX spectrum of AZO conforms the presence of Zn, O and Al. The optical transmittance in the visible region is high 87% and the band gap value is 3.23 eV. The optical transmittance is decreased with respect to dipping cycles. The room temperature PL studies revealed that the AZO films prepared at (30 cycles) has good film quality with lesser defect density. The third order nonlinear optical parameters were also studied using Z-scan technique to know the applications of deposited films in nonlinear devices. The third order nonlinear susceptibility value is found to be 1.69 × 10-7, 3.34 × 10-8, 1.33 × 10-7and 2.52 × 10-7 for AZO films deposited after 15, 20, 25 and 30 dipping cycles.

Optimizing pulsed Nd:YAG laser beam welding process parameters to attain maximum ultimate tensile strength for thin AISI316L sheet using response surface methodology and simulated annealing algorithm

NASA Astrophysics Data System (ADS)

Torabi, Amir; Kolahan, Farhad

2018-07-01

Pulsed laser welding is a powerful technique especially suitable for joining thin sheet metals. In this study, based on experimental data, pulsed laser welding of thin AISI316L austenitic stainless steel sheet has been modeled and optimized. The experimental data required for modeling are gathered as per Central Composite Design matrix in Response Surface Methodology (RSM) with full replication of 31 runs. Ultimate Tensile Strength (UTS) is considered as the main quality measure in laser welding. Furthermore, the important process parameters including peak power, pulse duration, pulse frequency and welding speed are selected as input process parameters. The relation between input parameters and the output response is established via full quadratic response surface regression with confidence level of 95%. The adequacy of the regression model was verified using Analysis of Variance technique results. The main effects of each factor and the interactions effects with other factors were analyzed graphically in contour and surface plot. Next, to maximum joint UTS, the best combinations of parameters levels were specified using RSM. Moreover, the mathematical model is implanted into a Simulated Annealing (SA) optimization algorithm to determine the optimal values of process parameters. The results obtained by both SA and RSM optimization techniques are in good agreement. The optimal parameters settings for peak power of 1800 W, pulse duration of 4.5 ms, frequency of 4.2 Hz and welding speed of 0.5 mm/s would result in a welded joint with 96% of the base metal UTS. Computational results clearly demonstrate that the proposed modeling and optimization procedures perform quite well for pulsed laser welding process.

Single-crystal-like, c-axis oriented BaTiO3 thin films with high-performance on flexible metal templates for ferroelectric applications

NASA Astrophysics Data System (ADS)

Shin, Junsoo; Goyal, Amit; Jesse, Stephen; Kim, Dae Ho

2009-06-01

Epitaxial, c-axis oriented BaTiO3 thin films were deposited using pulsed laser ablation on flexible, polycrystalline Ni alloy tape with biaxially textured oxide buffer multilayers. The high quality of epitaxial BaTiO3 thin films with P4mm group symmetry was confirmed by x-ray diffraction. The microscopic ferroelectric domain structure and the piezoelectric domain switching in these films were confirmed via spatially resolved piezoresponse mapping and local hysteresis loops. Macroscopic measurements demonstrate that the films have well-saturated hysteresis loops with a high remanent polarization of ˜11.5 μC/cm2. Such high-quality, single-crystal-like BaTiO3 films on low-cost, polycrystalline, flexible Ni alloy substrates are attractive for applications in flexible lead-free ferroelectric devices.

Reflexion on linear regression trip production modelling method for ensuring good model quality

NASA Astrophysics Data System (ADS)

Suprayitno, Hitapriya; Ratnasari, Vita

2017-11-01

Transport Modelling is important. For certain cases, the conventional model still has to be used, in which having a good trip production model is capital. A good model can only be obtained from a good sample. Two of the basic principles of a good sampling is having a sample capable to represent the population characteristics and capable to produce an acceptable error at a certain confidence level. It seems that this principle is not yet quite understood and used in trip production modeling. Therefore, investigating the Trip Production Modelling practice in Indonesia and try to formulate a better modeling method for ensuring the Model Quality is necessary. This research result is presented as follows. Statistics knows a method to calculate span of prediction value at a certain confidence level for linear regression, which is called Confidence Interval of Predicted Value. The common modeling practice uses R2 as the principal quality measure, the sampling practice varies and not always conform to the sampling principles. An experiment indicates that small sample is already capable to give excellent R2 value and sample composition can significantly change the model. Hence, good R2 value, in fact, does not always mean good model quality. These lead to three basic ideas for ensuring good model quality, i.e. reformulating quality measure, calculation procedure, and sampling method. A quality measure is defined as having a good R2 value and a good Confidence Interval of Predicted Value. Calculation procedure must incorporate statistical calculation method and appropriate statistical tests needed. A good sampling method must incorporate random well distributed stratified sampling with a certain minimum number of samples. These three ideas need to be more developed and tested.

Voltage Scaling of Graphene Device on SrTiO3 Epitaxial Thin Film.

PubMed

Park, Jeongmin; Kang, Haeyong; Kang, Kyeong Tae; Yun, Yoojoo; Lee, Young Hee; Choi, Woo Seok; Suh, Dongseok

2016-03-09

Electrical transport in monolayer graphene on SrTiO3 (STO) thin film is examined in order to promote gate-voltage scaling using a high-k dielectric material. The atomically flat surface of thin STO layer epitaxially grown on Nb-doped STO single-crystal substrate offers good adhesion between the high-k film and graphene, resulting in nonhysteretic conductance as a function of gate voltage at all temperatures down to 2 K. The two-terminal conductance quantization under magnetic fields corresponding to quantum Hall states survives up to 200 K at a magnetic field of 14 T. In addition, the substantial shift of charge neutrality point in graphene seems to correlate with the temperature-dependent dielectric constant of the STO thin film, and its effective dielectric properties could be deduced from the universality of quantum phenomena in graphene. Our experimental data prove that the operating voltage reduction can be successfully realized due to the underlying high-k STO thin film, without any noticeable degradation of graphene device performance.

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagul, Sagar B., E-mail: nano.sbbagul@gmail.com; Upadhye, Deepak S.; Sharma, Ramphal, E-mail: rps.phy@gmail.com

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology ofmore » Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.« less

Microstructure evolution and coercivity enhancement in Nd-Fe-B thin films diffusion-processed by R-Al alloys (R=Nd, Pr)

NASA Astrophysics Data System (ADS)

Xie, Yigao; Yang, Yang; Zhang, Tongbo; Fu, Yanqing; Jiang, Qingzheng; Ma, Shengcan; Zhong, Zhenchen; Cui, Weibin; Wang, Qiang

2018-05-01

Diffusion process by Nd-Al and Pr-Al alloys was compared and investigated in Nd-Fe-B thin films. Enhanced coercivity 2.06T and good squareness was obtained by using Pr85Al15 and Nd85Al15 alloys as diffusion sources. But the coercivity of diffusion-processed thin films by Pr70Al30 and Pr55Al45 alloys decreased to 2.04T and 1.82T. High ambient coercivity of 2.26T was achieved in diffusion-processed thin film by Nd70Al30 leading to an improved coercivity thermal stability because Nd2Fe14B grains were enveloped by Nd-rich phase as seen by transmission electron microscopy Nd-loss image. Meanwhile, microstructure-dependent parameters α and Neff were improved. However, high content of Al in diffusion-processed thin film by Nd55Al45 lead to degraded texture and coercivity.

Dielectric Scattering Patterns for Efficient Light Trapping in Thin-Film Solar Cells.

PubMed

van Lare, Claire; Lenzmann, Frank; Verschuuren, Marc A; Polman, Albert

2015-08-12

We demonstrate an effective light trapping geometry for thin-film solar cells that is composed of dielectric light scattering nanocavities at the interface between the metal back contact and the semiconductor absorber layer. The geometry is based on resonant Mie scattering. It avoids the Ohmic losses found in metallic (plasmonic) nanopatterns, and the dielectric scatterers are well compatible with nearly all types of thin-film solar cells, including cells produced using high temperature processes. The external quantum efficiency of thin-film a-Si:H solar cells grown on top of a nanopatterned Al-doped ZnO, made using soft imprint lithography, is strongly enhanced in the 550-800 nm spectral band by the dielectric nanoscatterers. Numerical simulations are in good agreement with experimental data and show that resonant light scattering from both the AZO nanostructures and the embedded Si nanostructures are important. The results are generic and can be applied on nearly all thin-film solar cells.

Low-cost ultra-thin broadband terahertz beam-splitter.

PubMed

Ung, Benjamin S-Y; Fumeaux, Christophe; Lin, Hungyen; Fischer, Bernd M; Ng, Brian W-H; Abbott, Derek

2012-02-27

A low-cost terahertz beam-splitter is fabricated using ultra-thin LDPE plastic sheeting coated with a conducting silver layer. The beam splitting ratio is determined as a function of the thickness of the silver layer--thus any required splitting ratio can be printed on demand with a suitable rapid prototyping technology. The low-cost aspect is a consequence of the fact that ultra-thin LDPE sheeting is readily obtainable, known more commonly as domestic plastic wrap or cling wrap. The proposed beam-splitter has numerous advantages over float zone silicon wafers commonly used within the terahertz frequency range. These advantages include low-cost, ease of handling, ultra-thin thickness, and any required beam splitting ratio can be readily fabricated. Furthermore, as the beam-splitter is ultra-thin, it presents low loss and does not suffer from Fabry-Pérot effects. Measurements performed on manufactured prototypes with different splitting ratios demonstrate a good agreement with our theoretical model in both P and S polarizations, exhibiting nearly frequency-independent splitting ratios in the terahertz frequency range.

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

NASA Astrophysics Data System (ADS)

Bagul, Sagar B.; Upadhye, Deepak S.; Sharma, Ramphal

2016-05-01

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology of Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.

Growth of <111>-oriented Cu layer on thin TaWN films

NASA Astrophysics Data System (ADS)

Takeyama, Mayumi B.; Sato, Masaru

2017-07-01

In this study, we examine the growth of a <111>-oriented Cu layer on a thin TaWN ternary alloy barrier for good electromigration reliability. The strongly preferentially oriented Cu(111) layer is observed on a thin TaWN barrier even in the as-deposited Cu (100 nm)/TaWN (5 nm)/Si system. Also, this system tolerates annealing at 700 °C for 1 h without silicide reaction. It is revealed that the TaWN film is one of the excellent barriers with thermal stability and low resistivity. Simultaneously, the TaWN film is a candidate for a superior underlying material to achieve the Cu(111) preferential orientation.

Optical, wetting and electrical properties of functionalized fulleropyrrolidine thin films

NASA Astrophysics Data System (ADS)

Abdulrazack, Parveen; Venkatesan, Sughanya; Chellasamy, Manoharan; Samuthira, Nagarajan

2017-12-01

Fulleropyrrolidine derivatives acts as an electron acceptor in the fabrication of solar cells and other optoelectronic devices. In this investigation thin film of functionalized fulleropyrrolidines were fabricated and studied their photo-physical properties. Surface morphology of the thin films was investigated through AFM and FE-SEM. The results suggested that large dependence on structure vs molecular packing. The long alkyl chain substituted C60 were assembled in the form of nanorods. C60- C60 intermolecular distance were measured, the films were with good absorption and exhibits n-type semiconducting behavior. The films were having high contact angle and can be effectively used for fabricating semiconducting devices with self- cleaning property.

Effects of thermochemical treatment on CuSbS 2 photovoltaic absorber quality and solar cell reproducibility

DOE PAGES

de Souza Lucas, Francisco Willian; Welch, Adam W.; Baranowski, Lauryn L.; ...

2016-08-01

CuSbS 2 is a promising nontoxic and earth-abundant photovoltaic absorber that is chemically simpler than the widely studied Cu 2ZnSnS 4. However, CuSbS 2 photovoltaic (PV) devices currently have relatively low efficiency and poor reproducibility, often due to suboptimal material quality and insufficient optoelectronic properties. To address these issues, here we develop a thermochemical treatment (TT) for CuSbS 2 thin films, which consists of annealing in Sb 2S 3 vapor followed by a selective KOH surface chemical etch. The annealed CuSbS 2 films show improved structural quality and optoelectronic properties, such as stronger band-edge photoluminescence and longer photoexcited carrier lifetime.more » These improvements also lead to more reproducible CuSbS 2 PV devices, with performance currently limited by a large cliff-type interface band offset with CdS contact. Altogether, these results point to the potential avenues to further increase the performance of CuSbS 2 thin film solar cell, and the findings can be transferred to other thin film photovoltaic technologies.« less

Electronic packaging: new results in singulation by Laser Microjet

NASA Astrophysics Data System (ADS)

Wagner, Frank; Sibailly, Ochelio; Richerzhagen, Bernold

2004-07-01

Cutting electronic packages that are produced in a matrix array fashion is an important process and deals with the ready-to-use devices. Thus an increase in the singulation yield is directly correlated to an increase in benefit. Due to the usage of different substrate materials, the saws encounter big problems in terms of lifetime and constancy of cut quality in these applications. Today"s equipment manufacturers are not yet in the position to propose an adequate solution for all types of packages. Compared to classical laser cutting, the water-jet guided laser technology minimizes the heat damages in any kind of sample. This new material processing method consists in guiding a laser beam inside a hair thin, lowpressure water-jet by total internal reflection, and is applied to package singulation since two years approximately. Using a frequency doubled Nd:YAG laser guided by a water jet, an LTCC-ceramics based package is singulated according to a scribe and break process. Speeds of 2-10 mm/s are reached in the LTTC and 40 mm/s in the mold compound. The process is wear-free and provides very good edge quality of the LTCC and the mold compound as well as reliable separation of the packages.

Hot-filament chemical vapor deposition chamber and process with multiple gas inlets

DOEpatents

Deng, Xunming; Povolny, Henry S.

2004-06-29

A thin film deposition method uses a vacuum confinement cup that employs a dense hot filament and multiple gas inlets. At least one reactant gas is introduced into the confinement cup both near and spaced apart from the heated filament. An electrode inside the confinement cup is used to generate plasma for film deposition. The method is used to deposit advanced thin films (such as silicon based thin films) at a high quality and at a high deposition rate.

Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides.

PubMed

Sivakumar, Sai; Zwier, Elizabeth; Meisenheimer, Peter Benjamin; Heron, John T

2018-05-29

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (Cu variant) entropy-stabilized oxides. Phase pure and chemically homogeneous (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (x = 0.20, 0.27, 0.33) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (x = 0.11, 0.27) ceramic pellets are synthesized and used in the deposition of ultra-high quality, phase pure, single crystalline thin films of the target stoichiometry. A detailed methodology for the deposition of smooth, chemically homogeneous, entropy-stabilized oxide thin films by pulsed laser deposition on (001)-oriented MgO substrates is described. The phase and crystallinity of bulk and thin film materials are confirmed using X-ray diffraction. Composition and chemical homogeneity are confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The surface topography of thin films is measured with scanning probe microscopy. The synthesis of high quality, single crystalline, entropy-stabilized oxide thin films enables the study of interface, size, strain, and disorder effects on the properties in this new class of highly disordered oxide materials.

Proceedings of the eleventh biennial southern silvicultural research conference

Treesearch

Kenneth W. Outcalt; [Editor

2002-01-01

One hundred and twenty-four papers and three poster summaries address a range of issues affecting southern forests. Papers are grouped in 19 sessions that include pine nutrition, nurseries/seed and seedlings, ecophysiology, fire, pine thinning and spacing, wood quality/technology, hardwood thinning and spacing, hardwood nutrition, competition, pine natural regeneration...

Polymer-assisted aqueous deposition of metal oxide films

DOEpatents

Li, DeQuan [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM

2003-07-08

An organic solvent-free process for deposition of metal oxide thin films is presented. The process includes aqueous solutions of necessary metal precursors and an aqueous solution of a water-soluble polymer. After a coating operation, the resultant coating is fired at high temperatures to yield optical quality metal oxide thin films.

Volume, value, and thinning: logs for the future.

Treesearch

Sally Duncan

2002-01-01

Thinning is one of our most important ways to influence tree and stand development. The objectives may include increasing the volume, size, and quality of wood produced from a forest and developing particular stand structures and characteristics for other values, such as wildlife or aesthetics.The Levels-of-Growing-Stock (LOGS) Cooperative was initiated in...

Moisture removal characteristics of thin layer rough rice under sequenced infrared radiation heating and cooling

USDA-ARS?s Scientific Manuscript database

Rice drying with infrared (IR) radiation has been investigated during recent years and showed promising potential with improved quality and energy efficiency. The objective of this study was to further investigate the moisture removal characteristics of thin layer rough rice heated by IR and cooled ...

Composite Yb:YAG/SiC-prism thin disk laser.

PubMed

Newburgh, G A; Michael, A; Dubinskii, M

2010-08-02

We report the first demonstration of a Yb:YAG thin disk laser wherein the gain medium is intracavity face-cooled through bonding to an optical quality SiC prism. Due to the particular design of the composite bonded Yb:YAG/SiC-prism gain element, the laser beam impinges on all refractive index interfaces inside the laser cavity at Brewster's angles. The laser beam undergoes total internal reflection (TIR) at the bottom of the Yb(10%):YAG thin disk layer in a V-bounce cavity configuration. Through the use of TIR and Brewster's angles, no optical coatings, either anti-reflective (AR) or highly reflective (HR), are required inside the laser cavity. In this first demonstration, the 936.5-nm diode pumped laser performed with approximately 38% slope efficiency at 12 W of quasi-CW (Q-CW) output power at 1030 nm with a beam quality measured at M(2) = 1.5. This demonstration opens up a viable path toward novel thin disk laser designs with efficient double-sided room-temperature heatsinking via materials with the thermal conductivity of copper on both sides of the disk.

Thermal oxidation of silicon in a residual oxygen atmosphere—the RESOX process—for self-limiting growth of thin silicon dioxide films

NASA Astrophysics Data System (ADS)

Wright, Jason T.; Carbaugh, Daniel J.; Haggerty, Morgan E.; Richard, Andrea L.; Ingram, David C.; Kaya, Savas; Jadwisienczak, Wojciech M.; Rahman, Faiz

2016-10-01

We describe in detail the growth procedures and properties of thermal silicon dioxide grown in a limited and dilute oxygen atmosphere. Thin thermal oxide films have become increasingly important in recent years due to the continuing down-scaling of ultra large scale integration metal oxide silicon field effect transistors. Such films are also of importance for organic transistors where back-gating is needed. The technique described here is novel and allows self-limited formation of high quality thin oxide films on silicon surfaces. This technique is easy to implement in both research laboratory and industrial settings. Growth conditions and their effects on film growth have been described. Properties of the resulting oxide films, relevant for microelectronic device applications, have also been investigated and reported here. Overall, our findings are that thin, high quality, dense silicon dioxide films of thicknesses up to 100 nm can be easily grown in a depleted oxygen environment at temperatures similar to that used for usual silicon dioxide thermal growth in flowing dry oxygen.

Characterization of PET preforms using spectral domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Hosseiny, Hamid; Ferreira, Manuel João.; Martins, Teresa; Carmelo Rosa, Carla

2013-11-01

Polyethylene terephthalate (PET) preforms are massively produced nowadays with the purpose of producing food and beverages packaging and liquid containers. Some varieties of these preforms are produced as multilayer structures, where very thin inner film(s) act as a barrier for nutrients leakage. The knowledge of the thickness of this thin inner layer is important in the production line. The quality control of preforms production requires a fast approach and normally the thickness control is performed by destructive means out of the production line. A spectral domain optical coherence tomography (SD-OCT) method was proposed to examine the thin layers in real time. This paper describes a nondestructive approach and all required signal processing steps to characterize the thin inner layers and also to improve the imaging speed and the signal to noise ratio. The algorithm was developed by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This GPU-accelerated white light interferometry technique nondestructively assesses the samples and has high imaging speed advantage, overcoming the bottlenecks in PET performs quality control.

Chemical solution synthesis and ferromagnetic resonance of epitaxial thin films of yttrium iron garnet

NASA Astrophysics Data System (ADS)

Lucas, Irene; Jiménez-Cavero, Pilar; Vila-Fungueiriño, J. M.; Magén, Cesar; Sangiao, Soraya; de Teresa, José Maria; Morellón, Luis; Rivadulla, Francisco

2017-12-01

We report the fabrication of epitaxial Y3F e5O12 (YIG) thin films on G d3G a5O12 (111) using a chemical solution method. Cubic YIG is a ferrimagnetic material at room temperature, with excellent magneto-optical properties, high electrical resistivity, and a very narrow ferromagnetic resonance, which makes it particularly suitable for applications in filters and resonators at microwave frequencies. But these properties depend on the precise stoichiometry and distribution of F e3 + ions among the octahedral/tetrahedral sites of a complex structure, which hampered the production of high-quality YIG thin films by affordable chemical methods. Here we report the chemical solution synthesis of YIG thin films, with excellent chemical, crystalline, and magnetic homogeneity. The films show a very narrow ferromagnetic resonance (long spin relaxation time), comparable to that obtained from high-vacuum physical deposition methods. These results demonstrate that chemical methods can compete to develop nanometer-thick YIG films with the quality required for spintronic devices and other high-frequency applications.

Synthesis of nanocrystalline ZnO thin films by electron beam evaporation

NASA Astrophysics Data System (ADS)

Kondkar, V.; Rukade, D.; Bhattacharyya, V.

2018-05-01

Nanocrystalline ZnO thin films have potential for applications in variety of optoelectronic devices. In the present study, nanocrystalline thin films of ZnO are grown on fused silica substrate using electron beam (e-beam) evaporation technique. Phase identification is carried out using Glancing angle X-ray diffraction (GAXRD) and Raman spectroscopy. Ultraviolet-Visible (UV-Vis) spectroscopic analysis is carried out to calculate energy band gap of the ZnO film. Surface morphology of the film is investigated using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). Highly quality nanocrystalline thin films of hexagonal wurtzite ZnO are synthesized using e-beam evaporation technique.

Flexural waves induced by electro-impulse deicing forces

NASA Technical Reports Server (NTRS)

Gien, P. H.

1990-01-01

The generation, reflection and propagation of flexural waves created by electroimpulsive deicing forces are demonstrated both experimentally and analytically in a thin circular plate and a thin semicylindrical shell. Analytical prediction of these waves with finite element models shows good correlation with acceleration and displacement measurements at discrete points on the structures studied. However, sensitivity to spurious flexural waves resulting from the spatial discretization of the structures is shown to be significant. Consideration is also given to composite structures as an extension of these studies.

Use of aluminum oxide as a permeation barrier for producing thin films on aluminum substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Provo, James L., E-mail: jlprovo@verizon.net

2016-07-15

Aluminum has desirable characteristics of good thermal properties, good electrical characteristics, good optical properties, and the characteristic of being nonmagnetic and having a low atomic weight (26.98 g atoms), but because of its low melting point (660 °C) and ability as a reactive metal to alloy with most common metals in use, it has been ignored as a substrate material for use in processing thin films. The author developed a simple solution to this problem, by putting a permeation barrier of alumina (Al{sub 2}O{sub 3}) onto the surface of pure Al substrates by using a standard chemical oxidation process of the surfacemore » (i.e., anodization), before additional film deposition of reactive metals at temperatures up to 500 °C for 1-h, without the formation of alloys or intermetallic compounds to affect the good properties of Al substrates. The chromic acid anodization process used (MIL-A-8625) produced a film barrier of ∼(500–1000) nm of alumina. The fact that refractory Al{sub 2}O{sub 3} can inhibit the reaction of metals with Al at temperatures below 500 °C suggests that Al is a satisfactory substrate if properly oxidized prior to film deposition. To prove this concept, thin film samples of Cr, Mo, Er, Sc, Ti, and Zr were prepared on anodized Al substrates and studied by x-ray diffraction, Rutherford ion back scattering, and Auger/argon sputter surface profile analysis to determine any film substrate interactions. In addition, a major purpose of our study was to determine if ErD{sub 2} thin films could be produced on Al substrates with fully hydrided Er films. Thus, a thin film of ErD{sub 2} on an anodized Al substrate was prepared and studied, with and without the alumina permeation barrier. Films for study were prepared on 1.27 cm diameter Al substrates with ∼500 nm of the metals studied after anodization. Substrates were weighed, cleaned, and vacuum fired at 500 °C prior to use. The Al substrates were deposited using standard electron beam cold crucible evaporation techniques, and after deposition the Er film was hydrided with D{sub 2} gas using a standard nonair exposure hydriding technique. All processing was conducted in an all metal ion pumped ultrahigh vacuum system. Results showed that e-beam deposition of films studied onto Al substrates could be successfully performed, if a permeation barrier of Al{sub 2}O{sub 3} from 500 to 1000 nm was made prior to thin film deposition up to temperatures of 500 °C for 1-h. Hydrides also, could be produced with full gas/metal atomic ratios of ∼2.0 as evidenced by the ErD{sub 2} films produced. Thus, the use of a simple permeation barrier of Al{sub 2}O{sub 3} on Al substrates prior to additional metal film deposition was proven to be a successful method of producing both thin metal films and hydride films of various types for many applications.« less

A Thin Film Flexible Supercapacitor Based on Oblique Angle Deposited Ni/NiO Nanowire Arrays.

PubMed

Ma, Jing; Liu, Wen; Zhang, Shuyuan; Ma, Zhe; Song, Peishuai; Yang, Fuhua; Wang, Xiaodong

2018-06-11

With high power density, fast charging-discharging speed, and a long cycling life, supercapacitors are a kind of highly developed novel energy-storage device that has shown a growing performance and various unconventional shapes such as flexible, linear-type, stretchable, self-healing, etc. Here, we proposed a rational design of thin film, flexible micro-supercapacitors with in-plane interdigital electrodes, where the electrodes were fabricated using the oblique angle deposition technique to grow oblique Ni/NiO nanowire arrays directly on polyimide film. The obtained electrodes have a high specific surface area and good adhesion to the substrate compared with other in-plane micro-supercapacitors. Meanwhile, the as-fabricated micro-supercapacitors have good flexibility and satisfactory energy-storage performance, exhibiting a high specific capacity of 37.1 F/cm³, a high energy density of 5.14 mWh/cm³, a power density of up to 0.5 W/cm³, and good stability during charge-discharge cycles and repeated bending-recovery cycles, respectively. Our micro-supercapacitors can be used as ingenious energy storage devices for future portable and wearable electronic applications.

Growth of Monolayer Graphene on Nanoscale Copper-Nickel Alloy Thin Films

PubMed Central

Cho, Joon Hyong; Gorman, Jason J.; Na, Seung Ryul; Cullinan, Michael

2017-01-01

Growth of high quality and monolayer graphene on copper thin films on silicon wafers is a promising approach to massive and direct graphene device fabrication in spite of the presence of potential dewetting issues in the copper film during graphene growth. Current work demonstrates roles of a nickel adhesion coupled with the copper film resulting in mitigation of dewetting problem as well as uniform monolayer graphene growth over 97 % coverage on films. The feasibility of monolayer graphene growth on Cu-Ni alloy films as thin as 150 nm in total is also demonstrated. During the graphene growth on Cu-Ni films, the nickel adhesion layer uniformly diffuses into the copper thin film resulting in a Cu-Ni alloy, helping to promote graphene nucleation and large area surface coverage. Furthermore, it was found that the use of extremely thin metal catalyst films also constraint the total amount of carbon that can be absorbed into the film during growth, which helps to eliminate adlayer formation and promote monolayer growth regardless of alloying content, thus improving the monolayer fraction of graphene coverage on the thinner films. These results suggest a path forward for the large scale integration of high quality, monolayer graphene into nanoelectronic and nanomechanical devices. PMID:28669999

Influence of Mn contents in 0Cr18Ni10Ti thin wall stainless steel tube on TIG girth weld quality

NASA Astrophysics Data System (ADS)

Liu, Bo

2017-03-01

Three kinds of cold worked 0Cr18Ni10Ti thin wall stainless steel tubes with the manganese contents of 1.27%, 1.35% and 1.44% and the cold worked 0Cr18Ni10Ti stainless steel end plug with manganese content of 1.35% were used for TIG girth welding in the present investigation. The effect of different manganese contents in stainless steel tube on weld quality was studied. The results showed that under the same welding conditions, the metallographic performance of the girth weld for the thin wall stainless steel tube with the manganese element content 1.44% welded with end plug was the best. Under the appropriate welding conditions, the quality of the girth weld increased with the increase of the manganese content till 1.44%. It was found that in the case of the Mn content of 1.44%, and under the proper welding condition the welding defects, such as welding cracks were effectively avoided, and the qualified weld penetration can be obtained.. It is concluded that the appropriate increase of the manganese content can significantly improve the TIG girth weld quality of the cold worked 0Cr18Ni10Ti stainless steel tube.

Fabrication of high-quality superconductor-insulator-superconductor junctions on thin SiN membranes

NASA Technical Reports Server (NTRS)

Garcia, Edouard; Jacobson, Brian R.; Hu, Qing

1993-01-01

We have successfully fabricated high-quality and high-current density superconductor-insulator-superconductor (SIS) junctions on freestanding thin silicon nitride (SIN) membranes. These devices can be used in a novel millimeter-wave and THz receiver system which is made using micromachining. The SIS junctions with planar antennas were fabricated first on a silicon wafer covered with a SiN membrane, the Si wafer underneath was then etched away using an anisotropic KOH etchant. The current-voltage characteristics of the SIS junctions remained unchanged after the whole process, and the junctions and the membrane survived thermal cycling.

Effect of residual gas on structural, electrical and mechanical properties of niobium films deposited by magnetron sputtering deposition

NASA Astrophysics Data System (ADS)

Wang, Lanruo; Zhong, Yuan; Li, Jinjin; Cao, Wenhui; Zhong, Qing; Wang, Xueshen; Li, Xu

2018-04-01

Magnetron sputtering is an important method in the superconducting thin films deposition. The residual gas inside the vacuum chamber will directly affect the quality of the superconducting films. In this paper, niobium films are deposited by magnetron sputtering under different chamber residual gas conditions. The influence of baking and sputtering process on residual gas are studied as well. Surface morphology, electrical and mechanical properties of the films are analysed. The residual gas analysis result before the sputtering process could be regarded as a reference condition to achieve high quality superconducting thin films.

Properties of Superconducting Mo, Mo2n and Trilayer Mo2n-Mo-Mo2n Thin Films

NASA Technical Reports Server (NTRS)

Barrentine, E. M.; Stevenson, T. R.; Brown, A. D.; Lowitz, A. E.; Noroozian, O.; U-Yen, K.; Eshan, N.; Hsieh, W. T.; Moseley, S. H.; Wollack, E. J.

2014-01-01

We present measurements of the properties of thin film superconducting Mo, Mo2N and Mo2N/Mo/Mo2N trilayers of interest for microwave kinetic inductance detector (MKID) applications. Using microwave resonator devices, we investigate the transition temperature, energy gaps, kinetic inductance, and internal quality factors of these materials. We present an Usadel-based interpretation of the trilayer transition temperature as a function of trilayer thicknesses, and a 2-gap interpretation to understand the change in kinetic inductance and internal resonance quality factor (Q) as a function of temperature.

Numerical investigation of tube hyroforming of TWT using Corner Fill Test

NASA Astrophysics Data System (ADS)

Zribi, Temim; Khalfallah, Ali

2018-05-01

Tube hydroforming presents a very good alternative to conventional forming processes for obtaining good quality mechanical parts used in several industrial fields, such as the automotive and aerospace sectors. Research in the field of tube hydroforming is aimed at improving the formability, stiffness and weight reduction of manufactured parts using this process. In recent years, a new method of hydroforming appears; it consists of deforming parts made from welded tubes and having different thicknesses. This technique which contributes to the weight reduction of the hydroformed tubes is a good alternative to the conventional tube hydroforming. This technique makes it possible to build rigid and light structures with a reduced cost. However, it is possible to improve the weight reduction by using dissimilar tailor welded tubes (TWT). This paper is a first attempt to analyze by numerical simulation the behavior of TWT hydroformed in square cross section dies, commonly called (Corner Fill Test). Considered tubes are composed of two materials assembled by butt welding. The present analysis will focus on the effect of loading paths on the formability of the structure by determining the change in thickness in several sections of the part. A comparison between the results obtained by hydroforming the butt joint of tubes made of dissimilar materials and those obtained using single-material tube is achieved. Numerical calculations show that the bi-material welded tube has better thinning resistance and a more even thickness distribution in the circumferential directions when compared to the single-material tube.

Sol concentration effect on ZnO nanofibers photocatalytic activity synthesized by sol-gel dip coating method

NASA Astrophysics Data System (ADS)

Toubane, M.; Tala-Ighil, R.; Bensouici, F.; Bououdina, M.; Souier, M.; Liu, S.; Cai, W.; Iratni, A.

2017-03-01

ZnO thin films were deposited onto glass substrate by sol-gel dip coating method. The initial sol concentrations were varied from 0.2 to 0.5 M. Zinc acetate dihydrate, ethanol and Diethanolamine (DEA) were used as staring material, solvent and stabilizer respectively. The evolution of structural, optical properties and methylene blue (MB) photodegradation of the as-deposited films on sol concentration was investigated. Rietveld refinements of x-ray patterns reveal that all the as-prepared thin films have a Zincite-type structure with grain orientation along to c-axis. The strongest sol concentration is favorable for the highest crystallization quality. However, the high preferred orientation factor (POF) occurs for 0.3 M sol concentration. The field emission scanning electron microscopy observations reveals nanofibrous morphology with different lengths. The nanofibers density increases with increasing sols concentrations until forming a flower-like morphology. The EDS analysis confirms the high purity of the as-deposited ZnO films. It is found that all films present good transparency greater than 95% in the visible range; the optical band gap is slightly reduced with the increase in sol concentration. The photocatalytic degradation is enhanced by 90% with the sol concentration. The K app rate reaction increased with increasing sol concentration. The films stability is found to slightly decrease after the third cycle, especially for 0.5 M sol concentration.

Fabrication and electrochemistry characteristics of nickel-doped diamond-like carbon film toward applications in non-enzymatic glucose detection

NASA Astrophysics Data System (ADS)

Liu, Chi-Wen; Chen, Wei-En; Sun, Yin Tung Albert; Lin, Chii-Ruey

2018-04-01

This research work focused on the fabrication of nickel-doped diamond-like carbon (DLC) films and their characteristics including of surface morphology, microstructure, and electrochemical aiming at applications in non-enzymatic glucose detection. Novel nanodiamond target was employed in unbalanced magnetron radio-frequency co-sputtering process to prepared high quality Ni-doped DLC thin film at room temperature. TEM analysis reveals a highly uniform distribution of Ni crystallites in amorphous carbon matrix with fraction ranged from 3 to 11.5 at.% which is considered as active sites for the glucose detection. Our cyclic voltammetry measurements using 0.1 M H2SO4 solution demonstrated that the as-prepared Ni-doped DLC films possess large electrochemical potential window of 2.12 V, and this was also observed to be significantly reduced at high Ni doping level owing to lower sp3 fraction. The non-enzymatic glucose detection investigation indicates that the Ni-doped DLC thin film electrode prepared under 7 W of DC sputtering power on Ni target possesses good detecting performance, high stability, and high sensitivity to glucose concentration up to 10 mM, even with the existence of uric acid and ascorbic acid. The peak current was observed to be proportional to glucose concentration and scanning rate, demonstrating highly reversibility redox process of the film electrode and glucose.

Epitaxial patterning of nanometer-thick Y 3Fe 5O 12 films with low magnetic damping

DOE PAGES

Li, Shaozhen; Zhang, Wei; Ding, Junjia; ...

2016-11-27

Magnetic insulators such as yttrium iron garnet, Y 3Fe 5O 12, with extremely low magnetic damping have opened the door for low power spin-orbitronics due to their low energy dissipation and effcient spin current generation and transmission. We demonstrate reliable and effcient epitaxial growth and nanopatterning of Y 3Fe 5O 12 thin-film based nanostructures on insulating Gd 3Ga 5O 12 substrates. In particular, our fabrication process is compatible with conventional sputtering and liftoff, and does not require aggressive ion milling which may be detrimental to the oxide thin films. Structural and magnetic properties indicate good qualities, in particular low magneticmore » damping of both films and patterned structures. The dynamic magnetic properties of the nanostructures are systematically investigated as a function of the lateral dimension. By comparing to ferromagnetic nanowire structures, a distinct edge mode in addition to the main mode is identified by both experiments and simulations, which also exhibits cross-over with the main mode upon varying the width of the wires. In conclusion, the non-linear evolution of dynamic modes over nanostructural dimensions highlights the important role of size confinement to their material properties in magnetic devices where Y 3Fe 5O 12 nanostructures serve as the key functional component.« less

Ultra-high aspect ratio copper nanowires as transparent conductive electrodes for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Zhu, Zhaozhao; Mankowski, Trent; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

2016-09-01

We report the synthesis of ultra-high aspect ratio copper nanowires (CuNW) and fabrication of CuNW-based transparent conductive electrodes (TCE) with high optical transmittance (>80%) and excellent sheet resistance (Rs <30 Ω/sq). These CuNW TCEs are subsequently hybridized with aluminum-doped zinc oxide (AZO) thin-film coatings, or platinum thin film coatings, or nickel thin-film coatings. Our hybrid transparent electrodes can replace indium tin oxide (ITO) films in dye-sensitized solar cells (DSSCs) as either anodes or cathodes. We highlight the challenges of integrating bare CuNWs into DSSCs, and demonstrate that hybridization renders the solar cell integrations feasible. The CuNW/AZO-based DSSCs have reasonably good open-circuit voltage (Voc = 720 mV) and short-circuit current-density (Jsc = 0.96 mA/cm2), which are comparable to what is obtained with an ITO-based DSSC fabricated with a similar process. Our CuNW-Ni based DSSCs exhibit a good open-circuit voltage (Voc = 782 mV) and a decent short-circuit current (Jsc = 3.96 mA/cm2), with roughly 1.5% optical-to-electrical conversion efficiency.

Combined membrane bioreactor (MBR) and reverse osmosis (RO) system for thin-film transistor-liquid crystal display TFT-LCD, industrial wastewater recycling.

PubMed

Chen, T K; Chen, J N

2004-01-01

In TFT-LCD industry, water plays a variety of roles as a cleaning agent and reaction solvent. As good quality water is increasingly a scarce resource and wastewater treatment costs rises, the once-through use of industrial water is becoming uneconomical and environmentally unacceptable. Instead, recycling of TFT-LCD industrial wastewater is become more attractive from both an economic and environmental perspective. This research is mainly to explore the capacity of TFT-LCD industrial wastewater recycling by the process combined with membrane bioreactor and reverse osmosis processes. Over the whole experimental period, the MBR process achieved a satisfactory organic removal. The COD could be removed with an average of over 97.3%. For TOC and BOD5 items, the average removal efficiencies were 97.8 and 99.4% respectively. The stable effluent quality and satisfactory removal performance were ensured by the efficient interception performance of the UF membrane device incorporated with biological reactor. Moreover, the MBR effluent did not contain any suspended solids and the SDI value was under 3. After treatment of RO, excellent water quality of permeate were under 5 mg/l, 2.5 mg/l and 150 micros/cm for COD, TOC and conductivity respectively. The treated water can be recycled for the cooling tower make-up water or other purposes.

Plasmonic-enhanced graphene flake counter electrodes for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Kim, Hyun-Young; Lee, Myung Woo; Song, Da Hyun; Yoon, Hyeok Jin; Suh, Jung Sang

2017-06-01

A plasmonic-enhanced graphene flake counter electrode for dye-sensitized solar cells (DSSCs) was fabricated by immobilization of gold nanoparticles (NPs) on fluorine-doped tin oxide (FTO) glass and the deposition of a thin layer of graphene flakes. The graphene flakes, fabricated using a thermal plasma jet system, were very thin and pure and had good crystallinity. Even though their average size is larger than 100 nm, they had great dispersibility in common solvents. Their relatively large size and good crystallinity resulted in good conductivity, and their good dispersibility allowed us to fabricate relatively uniform films. The efficiency of the DSSC with a graphene flake/Au NP/FTO counter electrode was as much as 9.78%, which is higher than that with a conventional Pt/FTO (9.08%) or graphene flake/FTO (8.98%) counter electrode. Using cyclic voltammograms and electrochemical impedance spectroscopy and by measuring the incident photo-conversion efficiency, we proved that by the localized surface plasmon resonance effect of the Au NPs included between the graphene flakes and FTO, the charge-transfer resistance at the electrode/electrolyte interface was decreased. Consequently, the catalytic rate for I- regeneration improved, and the energy conversion efficiency of the DSSC with a graphene flake/Au NP/FTO counter electrode improved.

Characterization of MAPLE deposited WO3 thin films for electrochromic applications

NASA Astrophysics Data System (ADS)

Boyadjiev, S. I.; Stefan, N.; Szilágyi, I. M.; Mihailescu, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Besleaga, C.; Iliev, M. T.; Gesheva, K. A.

2017-01-01

Tungsten trioxide (WO3) is a widely studied material for electrochromic applications. The structure, morphology and optical properties of WO3 thin films, grown by matrix assisted pulsed laser evaporation (MAPLE) from monoclinic WO3 nano-sized particles, were investigated for their possible application as electrochromic layers. A KrF* excimer (λ=248 nm, ζFWHM=25 ns) laser source was used in all experiments. The MAPLE deposited WO3 thin films were studied by atomic force microscopy (AFM), grazing incidence X-ray diffraction (GIXRD) and Fourier transform infrared spectroscopy (FTIR). Cyclic voltammetry measurements were also performed, and the coloring and bleaching were observed. The morpho-structural investigations disclosed the synthesis of single-phase monoclinic WO3 films consisting of crystalline nano-grains embedded in an amorphous matrix. All thin films showed good electrochromic properties, thus validating application of the MAPLE deposition technique for the further development of electrochromic devices.

Turbine Blade Temperature Measurements Using Thin Film Temperature Sensors

NASA Technical Reports Server (NTRS)

Grant, H. P.; Przybyszewski, J. S.; Claing, R. G.

1981-01-01

The development of thin film temperature sensors is discussed. The technology for sputtering 2 micron thin film platinum versus platinum 10 percent rhodium thermocouples on alumina forming coatings was improved and extended to applications on actual turbine blades. Good adherence was found to depend upon achieving a proper morphology of the alumina surface. Problems of adapting fabrication procedures to turbine blades were uncovered, and improvements were recommended. Testing at 1250 K at one atmosphere pressure was then extended to a higher Mach No. (0.5) in combustor flow for 60 hours and 71 thermal cycles. The mean time to failure was 47 hours accumulated during 1 hour exposures in the combustor. Calibration drift was about 0.1 percent per hour, attributable to oxidation of the rhodium in the thin films. An increase in film thickness and application of a protective overcoat are recommended to reduce drift in actual engine testing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pawar, C. S., E-mail: charudutta-p@yahoo.com; Gujar, M. P.; Mathe, V. L.

Nano crystalline Nickel Zinc ferrite (Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4}) thin films were synthesized by Sol Gel method for gas response. The phase and microstructure of the obtained Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The nanostructured Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film shows single spinel phase. Magnetic study was obtained with the help of VSM. The effects of working temperature on the gas response were studied. The results reveal that the Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film gas sensor shows good selectivity to chlorine gas at roommore » temperature. The sensor shows highest sensitivity (∼50%) at room temperature, indicating its application in detecting chlorine gas at room temperature in the future.« less

Drive for muscularity and disordered eating among French adolescent boys: a sociocultural model.

PubMed

Rodgers, Rachel F; Ganchou, Camille; Franko, Debra L; Chabrol, Henri

2012-06-01

The pursuit of muscularity is an important body image concern among boys which has been described within sociocultural models of risk for eating disorders. This study explored a sociocultural model of disordered eating in which drive for thinness and pursuit of muscularity were both pathways to disordered eating among French adolescent boys. A sample of 146 adolescents completed a questionnaire assessing drive for thinness, drive for muscularity, media-ideal internalization, appearance comparison, and sociocultural pressure. The model was a good fit to the data and both drive for thinness and the pursuit of muscularity were related to disordered eating. Furthermore, internalization and appearance comparison mediated the relationships between pressure to increase muscle and both drive for muscularity and drive for thinness. Longitudinal research could help clarify the role of the pursuit of muscularity in the development of disordered eating and extreme body shape changing behaviors. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fabrication of micromachined ceramic thin-film-type pressure sensors for overpressure tolerance and its characteristics

NASA Astrophysics Data System (ADS)

Chung, Gwiy-Sang; Kim, Jae-Min

2004-04-01

This paper describes the fabrication process and characteristics of ceramic thin-film pressure sensors based on Ta-N strain gauges for harsh environment applications. The Ta-N thin-film strain gauges are sputter-deposited on a thermally oxidized micromachined Si diaphragm with buried cavities for overpressure tolerance. The proposed device takes advantage of the good mechanical properties of single-crystalline Si as a diaphragm fabricated by SDB and electrochemical etch-stop technology, and in order to extend the temperature range, it has relatively higher resistance, stability and gauge factor of Ta-N thin-films more than other gauges. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low nonlinearity and excellent temperature stability. The sensitivity is 1.21-1.097 mV/V×kgf/cm2 in temperature ranges of 25-200°C and a maximum non-linearity is 0.43 %FS.

Thin-film chip-to-substrate interconnect and methods for making same

DOEpatents

Tuckerman, D.B.

1988-06-06

Integrated circuit chips are electrically connected to a silicon wafer interconnection substrate. Thin film wiring is fabricated down bevelled edges of the chips. A subtractive wire fabrication method uses a series of masks and etching steps to form wires in a metal layer. An additive method direct laser writes or deposits very thin lines which can then be plated up to form wires. A quasi-additive or subtractive/additive method forms a pattern of trenches to expose a metal surface which can nucleate subsequent electrolytic deposition of wires. Low inductance interconnections on a 25 micron pitch (1600 wires on a 1 cm square chip) can be produced. The thin film hybrid interconnect eliminates solder joints or welds, and minimizes the levels of metallization. Advantages include good electrical properties, very high wiring density, excellent backside contact, compactness, and high thermal and mechanical reliability. 6 figs.

Thin-film chip-to-substrate interconnect and methods for making same

DOEpatents

Tuckerman, David B.

1991-01-01

Integrated circuit chips are electrically connected to a silica wafer interconnection substrate. Thin film wiring is fabricated down bevelled edges of the chips. A subtractive wire fabrication method uses a series of masks and etching steps to form wires in a metal layer. An additive method direct laser writes or deposits very thin metal lines which can then be plated up to form wires. A quasi-additive or subtractive/additive method forms a pattern of trenches to expose a metal surface which can nucleate subsequent electrolytic deposition of wires. Low inductance interconnections on a 25 micron pitch (1600 wires on a 1 cm square chip) can be produced. The thin film hybrid interconnect eliminates solder joints or welds, and minimizes the levels of metallization. Advantages include good electrical properties, very high wiring density, excellent backside contact, compactness, and high thermal and mechanical reliability.

Junctionless Thin-Film Transistors Gated by an H₃PO₄-Incorporated Chitosan Proton Conductor.

PubMed

Liu, Huixuan; Xun, Damao

2018-04-01

We fabricated an H3PO4-incorporated chitosan proton conductor film that exhibited the electric double layer effect and showed a high specific capacitance of 4.42 μF/cm2. Transparent indium tin oxide thin-film transistors gated by H3PO4-incorporated chitosan films were fabricated by sputtering through a shadow mask. The operating voltage was as low as 1.2 V because of the high specific capacitance of the H3PO4-incorporated chitosan dielectrics. The junctionless transparent indium tin oxide thin film transistors exhibited good performance, including an estimated current on/off ratio and field-effect mobility of 1.2 × 106 and 6.63 cm2V-1s-1, respectively. These low-voltage thin-film electric-double-layer transistors gated by H3PO4-incorporated chitosan are promising for next generation battery-powered "see-through" portable sensors.

Synthesis of ZnO thin film by sol-gel spin coating technique for H2S gas sensing application

NASA Astrophysics Data System (ADS)

Nimbalkar, Amol R.; Patil, Maruti G.

2017-12-01

In this present work, zinc oxide (ZnO) thin film synthesized by a simple sol-gel spin coating technique. The structural, morphology, compositional, microstructural, optical, electrical and gas sensing properties of the film were studied by using XRD, FESEM, EDS, XPS, HRTEM, Raman, FTIR and UV-vis techniques. The ZnO thin film shows hexagonal wurtzite structure with a porous structured morphology. Gas sensing performance of synthesized ZnO thin film was tested initially for H2S gas at different operating temperatures as well as concentrations. The maximum gas response is achieved towards H2S gas at 300 °C operating temperature, at 100 ppm gas concentration as compared to other gases like CH3OH, Cl2, NH3, LPG, CH3COCH3, and C2H5OH with a good stability.

Sol-gel preparation of silica and titania thin films

NASA Astrophysics Data System (ADS)

Thoř, Tomáš; Václavík, Jan

2016-11-01

Thin films of silicon dioxide (SiO2) and titanium dioxide (TiO2) for application in precision optics prepared via the solgel route are being investigated in this paper. The sol-gel process presents a low cost approach, which is capable of tailoring thin films of various materials in optical grade quality. Both SiO2 and TiO2 are materials well known for their application in the field of anti-reflective and also highly reflective optical coatings. For precision optics purposes, thickness control and high quality of such coatings are of utmost importance. In this work, thin films were deposited on microscope glass slides substrates using the dip-coating technique from a solution based on alkoxide precursors of tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TIP) for SiO2 and TiO2, respectively. As-deposited films were studied using spectroscopic ellipsometry to determine their thickness and refractive index. Using a semi-empirical equation, a relationship between the coating speed and the heat-treated film thickness was described for both SiO2 and TiO2 thin films. This allows us to control the final heat-treated thin film thickness by simply adjusting the coating speed. Furthermore, films' surface was studied using the white-light interferometry. As-prepared films exhibited low surface roughness with the area roughness parameter Sq being on average of 0.799 nm and 0.33 nm for SiO2 and TiO2, respectively.

Influence of substrate temperatures on the properties of GdF(3) thin films with quarter-wave thickness in the ultraviolet region.

PubMed

Jin, Jingcheng; Jin, Chunshui; Li, Chun; Deng, Wenyuan; Yao, Shun

2015-06-01

High-quality coatings of fluoride materials are in extraordinary demand for use in deep ultraviolet (DUV) lithography. Gadolinium fluoride (GdF₃) thin films were prepared by a thermal boat evaporation process at different substrate temperatures. GdF₃ thin film was set at quarter-wave thickness (∼27  nm) with regard to their common use in DUV/vacuum ultraviolet optical stacks; these thin films may significantly differ in nanostructural properties at corresponding depositing temperatures, which would crucially influence the performance of the multilayers. The measurement and analysis of optical, structural, and mechanical properties of GdF₃ thin films have been performed in a comprehensive characterization cycle. It was found that depositing GdF₃ thin films at relative higher temperature would form a rather dense, smooth, homogeneous structure within this film thickness scale.

Pulsed photonic fabrication of nanostructured metal oxide thin films

NASA Astrophysics Data System (ADS)

Bourgeois, Briley B.; Luo, Sijun; Riggs, Brian C.; Adireddy, Shiva; Chrisey, Douglas B.

2017-09-01

Nanostructured metal oxide thin films with a large specific surface area are preferable for practical device applications in energy conversion and storage. Herein, we report instantaneous (milliseconds) photonic synthesis of three-dimensional (3-D) nanostructured metal oxide thin films through the pulsed photoinitiated pyrolysis of organometallic precursor films made by chemical solution deposition. High wall-plug efficiency-pulsed photonic irradiation (xenon flash lamp, pulse width of 1.93 ms, fluence of 7.7 J/cm2 and frequency of 1.2 Hz) is used for scalable photonic processing. The photothermal effect of subsequent pulses rapidly improves the crystalline quality of nanocrystalline metal oxide thin films in minutes. The following paper highlights pulsed photonic fabrication of 3-D nanostructured TiO2, Co3O4, and Fe2O3 thin films, exemplifying a promising new method for the low-cost and high-throughput manufacturing of nanostructured metal oxide thin films for energy applications.

Thin Blue Lines and Red Crosses: Signposts to Quality in Family Day Care?

ERIC Educational Resources Information Center

White, Jayne

2005-01-01

This paper explores some of the findings of a study focussing on constructions of family day care from the perspectives of caregivers/educators and coordinators as they engaged in a quality review process using a recently developed resource--The Quality Journey/He haerenga whai hua (2000). The paper positions quality review as a part of a…

Surface-emitting stimulated emission in high-quality ZnO thin films

NASA Astrophysics Data System (ADS)

Zhang, X. Q.; Suemune, Ikuo; Kumano, H.; Wang, J.; Huang, S. H.

2004-10-01

High-quality ZnO thin films were grown by plasma-enhanced molecular-beam epitaxy on sapphire substrates. Three excitonic transitions associated with the valence bands A, B, and C were clearly revealed in the reflectance spectrum measured at 33K. This result indicates that the ZnO thin films have the wurtzite crystalline structure. The emission spectra were measured with backscattering geometry at room temperature. When the excitation exceeded a certain value, linewidth narrowing, nonlinear rise of emission intensity, and the shortening of the carrier lifetime were clearly observed and these demonstrate the onset of stimulated emission. Together with the ZnO thickness dependence, we conclude that the observation of a stimulated emission in a direction perpendicular to the film surface is predominantly due to scattering of the in-plane stimulated emission by slightly remaining surface undulations in the ZnO films.

Chemical vapor deposition of high T(sub c) superconducting films in a microgravity environment

NASA Technical Reports Server (NTRS)

Levy, Moises; Sarma, Bimal K.

1994-01-01

Since the discovery of the YBaCuO bulk materials in 1987, Metalorganic Chemical Vapor Deposition (MOCVD) has been proposed for preparing HTSC high T(sub c) films. This technique is now capable of producing high-T(sub c) superconducting thin films comparable in quality to those prepared by any other methods. The MOCVD technique has demonstrated its superior advantage in making large area high quality HTSC thin films and will play a major role in the advance of device applications of HTSC thin films. The organometallic precursors used in the MOCVD preparation of HTSC oxide thin films are most frequently metal beta-diketonates. High T(sub c) superconductors are multi-component oxides which require more than one component source, with each source, containing one kind of precursor. Because the volatility and stability of the precursors are strongly dependent on temperature, system pressure, and carrier gas flow rate, it has been difficult to control the gas phase composition, and hence film stoichiometry. In order circumvent these problems we have built and tested a single source MOCVD reactor in which a specially designed vaporizer was employed. This vaporizer can be used to volatilize a stoichiometric mixture of diketonates of yttrium, barium and copper to produce a mixed vapor in a 1:2:3 ratio respectively of the organometellics. This is accomplished even though the three compounds have significantly different volatilities. We have developed a model which provides insight into the process of vaporizing mixed precursors to produce high quality thin films of Y1Ba2Cu3O7. It shows that under steady state conditions the mixed organometallic vapor must have a stoichiometric ratio of the individual organometallics identical to that in the solid mixture.

Are prescribed fire and thinning dominant processes affecting snag occurrence at a landscape scale?

DOE PAGES

Zarnoch, Stanley J.; Blake, John I.; Parresol, Bernard R.

2014-11-01

Snags are standing dead trees that are an important component in the nesting habitat of birds and other species. Although snag availability is believed to limit populations in managed and non-managed forests, little data are available to evaluate the relative effect of stand conditions and management on snag occurrence. We analyzed point sample data from an intensive forest inventory within an 80,000 ha landscape for four major forest types to support the hypotheses that routine low-intensity prescribed fire would increase, and thinning would decrease, snag occurrence. We employed path analysis to define a priori causal relationships to determine the directmore » and indirect effects of site quality, age, relative stand density index and fire for all forest types and thinning effects for loblolly pine and longleaf pine. Stand age was an important direct effect for loblolly pine, mixed pine-hardwoods and hardwoods, but not for longleaf pine. Snag occurrence in loblolly pine was increased by prescribed fire and decreased by thinning which confirmed our initial hypotheses. Although fire was not important in mixed pine-hardwoods, it was for hardwoods but the relationship depended on site quality. For longleaf pine the relative stand density index was the dominant variable affecting snag occurrence, which increased as the density index decreased. Site quality, age and thinning had significant indirect effects on snag occurrence in longleaf pine through their effects on the density index. Although age is an important condition affecting snag occurrence for most forest types, path analysis revealed that fire and density management practices within certain forest types can also have major beneficial effects, particularly in stands less than 60 years old.« less

Morphological and crystalline characterization of pulsed laser deposited pentacene thin films for organic transistor applications

NASA Astrophysics Data System (ADS)

Pereira, Antonio; Bonhommeau, Sébastien; Sirotkin, Sergey; Desplanche, Sarah; Kaba, Mamadouba; Constantinescu, Catalin; Diallo, Abdou Karim; Talaga, David; Penuelas, Jose; Videlot-Ackermann, Christine; Alloncle, Anne-Patricia; Delaporte, Philippe; Rodriguez, Vincent

2017-10-01

We show that high-quality pentacene (P5) thin films of high crystallinity and low surface roughness can be produced by pulsed laser deposition (PLD) without inducing chemical degradation of the molecules. By using Raman spectroscopy and X-ray diffraction measurements, we also demonstrate that the deposition of P5 on Au layers result in highly disordered P5 thin films. While the P5 molecules arrange within the well-documented 1.54-nm thin-film phase on high-purity fused silica substrates, this ordering is indeed destroyed upon introducing an Au interlayer. This observation may be one explanation for the low electrical performances measured in P5-based organic thin film transistors (OTFTs) deposited by laser-induced forward transfer (LIFT).

Exceptional Morphology-Preserving Evolution of Formamidinium Lead Triiodide Perovskite Thin Films via Organic-Cation Displacement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yuanyuan; Yang, Mengjin; Pang, Shuping

Here we demonstrate a radically different chemical route for the creation of HC(NH2)2PbI3 (FAPbI3) perovskite thin films. This approach entails a simple exposure of as-synthesized CH3NH3PbI3 (MAPbI3) perovskite thin films to HC(=NH)NH2 (formamidine or FA) gas at 150 degrees C, which leads to rapid displacement of the MA+ cations by FA+ cations in the perovskite structure. The resultant FAPbI3 perovskite thin films preserve the microstructural morphology of the original MAPbI3 thin films exceptionally well. Importantly, the myriad processing innovations that have led to the creation of high-quality MAPbI3 perovskite thin films are directly adaptable to FAPbI3 through this simple, rapidmore » chemical-conversion route. Accordingly, we show that efficiencies of perovskite solar cells fabricated with FAPbI3 thin films created using this route can reach -18%.« less

The uniformity study of non-oxide thin film at device level using electron energy loss spectroscopy

NASA Astrophysics Data System (ADS)

Li, Zhi-Peng; Zheng, Yuankai; Li, Shaoping; Wang, Haifeng

2018-05-01

Electron energy loss spectroscopy (EELS) has been widely used as a chemical analysis technique to characterize materials chemical properties, such as element valence states, atoms/ions bonding environment. This study provides a new method to characterize physical properties (i.e., film uniformity, grain orientations) of non-oxide thin films in the magnetic device by using EELS microanalysis on scanning transmission electron microscope. This method is based on analyzing white line ratio of spectra and related extended energy loss fine structures so as to correlate it with thin film uniformity. This new approach can provide an effective and sensitive method to monitor/characterize thin film quality (i.e., uniformity) at atomic level for thin film development, which is especially useful for examining ultra-thin films (i.e., several nanometers) or embedded films in devices for industry applications. More importantly, this technique enables development of quantitative characterization of thin film uniformity and it would be a remarkably useful technique for examining various types of devices for industrial applications.

Electron-beam-evaporated thin films of hafnium dioxide for fabricating electronic devices

DOE PAGES

Xiao, Zhigang; Kisslinger, Kim

2015-06-17

Thin films of hafnium dioxide (HfO 2) are widely used as the gate oxide in fabricating integrated circuits because of their high dielectric constants. In this paper, the authors report the growth of thin films of HfO 2 using e-beam evaporation, and the fabrication of complementary metal-oxide semiconductor (CMOS) integrated circuits using this HfO 2 thin film as the gate oxide. The authors analyzed the thin films using high-resolution transmission electron microscopy and electron diffraction, thereby demonstrating that the e-beam-evaporation-grown HfO 2 film has a polycrystalline structure and forms an excellent interface with silicon. Accordingly, we fabricated 31-stage CMOS ringmore » oscillator to test the quality of the HfO 2 thin film as the gate oxide, and obtained excellent rail-to-rail oscillation waveforms from it, denoting that the HfO 2 thin film functioned very well as the gate oxide.« less

Qualities of a good Singaporean psychiatrist: Qualitative differences between psychiatrists and patients.

PubMed

Tor, Phern-Chern; Tan, Jacinta O A

2015-06-01

Pilot studies in Singapore established four themes (personal values, professional, relationship, academic-executive) relating to the qualities of a good psychiatrist, and suggested potential differences of opinion between patients and psychiatrists. We sought to explore differences between patients and psychiatrists regarding the qualities of a good psychiatrist. Qualitative analysis of interviews using a modified grounded theory approach with 21 voluntary psychiatric inpatients and 18 psychiatrists. One hundred thirty-one separate qualities emerged from the data. The qualities of a good psychiatrist were viewed in the context of motivations, functions, methods, and results obtained, mirroring the themes established in the pilot studies. Patients and psychiatrists mostly concurred on the qualities of a good psychiatrist, with 62.6% of the qualities emerging from both groups. However significant differences existed. Patient-specific qualities included proof of altruistic motives, diligence, clinical competence, and positive results. What the psychiatrist represented to patients in relation to gender, culture, and clinical prestige also mattered to patients. Psychiatrist-specific qualities related to societal (e.g. public protection) and professional concerns (e.g. boundary issues). The results of this study demonstrate that patients and psychiatrists have different views about the qualities of a good psychiatrist. Patients may expect proof of care, diligence, and competence from the psychiatrist, along with positive results. In addition, psychiatrists should be mindful of what they represent to patients and how that can impact the doctor-patient relationship. © 2014 Wiley Publishing Asia Pty Ltd.

Development and Validation of Chronopotentiometric Method for Imidacloprid Determination in Pesticide Formulations and River Water Samples

PubMed Central

Đurović, Ana; Stojanović, Zorica; Kravić, Snežana; Grahovac, Nada; Bursić, Vojislava; Vuković, Gorica; Suturović, Zvonimir

2016-01-01

A new electrochemical method for determination of imidacloprid using chronopotentiometry on thin film mercury and glassy carbon electrode was presented. The most important experimental parameters of chronopotentiometry were examined and optimized with respect to imidacloprid analytical signal. Imidacloprid provided well-defined reduction peak in Britton-Robinson buffer on thin film mercury electrode at −1.0 V (versus Ag/AgCl (KCl, 3.5 mol/L)) and on glassy carbon electrode at −1.2 V (versus Ag/AgCl (KCl, 3.5 mol/L)). The reduction time was linearly proportional to concentrations from 0.8 to 30.0 mg/L on thin film mercury electrode and from 7.0 to 70.0 mg/L on glassy carbon electrode. The detection limits were 0.17 mg/L and 0.93 mg/L for thin film mercury and glassy carbon electrode, respectively. The estimation of method precision as a function of repeatability and reproducibility showed relative standard deviations values lower than 3.73%. Recovery values from 97.3 to 98.1% confirmed the accuracy of the proposed method, while the constancy of the transition time with deliberated small changes in the experimental parameters indicated a very good robustness. A minor influence of possible interfering compounds proved good selectivity of the method. Developed method was applied for imidacloprid determination in commercial pesticide formulations and river water samples. PMID:27042181

Vineyard floor management and cluster thinning inconsistently affect ‘Pinot noir’ crop load, berry composition, and wine quality

USDA-ARS?s Scientific Manuscript database

A 3-year field study was developed to determine relationships between crop load metrics and berry composition for ‘Pinot noir’ in a cool-climate through the manipulation of vegetative growth and fruit yield using competitive cover cropping and cluster thinning, respectively. To alter vine vigor, per...

Harvesting costs and environmental impacts associated with skyline yarding shelterwood harvests and thinning in Appalachian hardwoods

Treesearch

J. E. Baumgras; C. B. LeDoux; J. R. Sherar

1993-01-01

To evaluate the potential for moderating the visual impact and soil disturbance associated with timber harvesting on steep-slope hardwood sites, thinning and shelterwood harvests were conducted with a skyline yarding system. Operations were monitored to document harvesting production, residual stand damage, soil disturbance, and visual quality. Yarding costs for...

Hydrologic and water quality effects of thinning Loblolly Pine

Treesearch

Johnny M. Grace; R. W. Skaggs; G. M. Chescheir

2006-01-01

Forest operations such as harvesting, thinning, and site preparation can affect the hydrologic behavior of watersheds on poorly drained soils. The influence of these operations conducted on organic soil sites can be more pronounced than on mineral soil sites due to the differences in bulk density and soil moisture relationships that exist between mineral and organic...

The central Appalachian hardwoods experience provides silvicultural tools for Ontario

Treesearch

Gary W. Miller; Ken A Elliott; Eric P. Boysen

1998-01-01

Cultural practices can be applied in even-age stands to reallocate site resources to selected crop trees. Precommercial thinning in sapling stands can increase diameter growth and improve species composition of trees in the main canopy. Commercial thinning in sawtimber stands also increases diameter growth of crop trees, improves residual stand quality, and removes...

Magnesium Diboride thin Films, multilayers, and coatings for SRF cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xi, Xiaoxing

Superconducting radio frequency (SRF) cavities currently use low-temperature superconductor niobium, and the Nb SRF cavities have approached the performance levels predicted theoretically. Compared to Nb, MgB 2 becomes superconducting at a much higher temperature and promises a better RF performance in terms of higher quality factor Q and higher acceleration capability. An MgB 2 SRF technology can significantly reduce the operating costs of particle accelerators when these potentials are realized. This project aimed to advance the development of an MgB 2 SRF technology. It had two main objectives: (1) materials issues of MgB 2 thin films and multilayers related tomore » their applications in SRF cavities; and (2) coating single-cell cavities for testing at RF frequencies. The key technical thrust of the project is the deposition of high quality clean MgB 2 films and coatings by the hybrid physical-chemical vapor deposition (HPCVD) technique, which was developed in my group. We have achieved technical progress in each of the two areas. For the first objective, we have confirmed that MgB 2 thin film coatings can be used to effectively enhance the vortex penetration field of an SRF cavity. A vortex is a normal region in the shape of spaghetti that threads through a superconductor. Its existence is due to an applied magnetic field that is greater than a so-called lower critical field, H c1. Once a vortex enters the superconductor, its movement leads to loss. This has been shown to be the reason for an SRF cavity to break down. Thus, enhancing the magnetic field for a vortex to enter the superconductor that forms the SRF cavity has be a goal of intense research. To this end, Gurevich proposed that a coating of thin superconductor layer can impede the vortex entrance. In this project, we have done two important experiment to test this concept. One, we showed that the enhancement of H c1 can be achieved by using in both epitaxial and polycrystalline MgB 2 films. Although H c1 is low for bulk MgB 2 samples, about 600 Oe at 5 K, it increases with decreasing film thickness, reaching 1880 Oe when the film thickness is 100 nm. Two, we coated Nb ellipsoids with MgB 2 films to achieve an “inverse cavity” configuration, mimicking the coating of an actual RF cavity. Our results demonstrate that it is indeed possible to increase the vortex penetration field of a cavity by a substantial amount (~600 Oe) by coating it with a thin MgB 2 film. For the second objective, we modified the existing HPCVD system to be able to coat a 3.9 GHz SRF cavity, and using a stainless steel mock cavity showed that a uniform film with good superconducting property can be grown across the cavity interior. Further, we successfully deposited MgB 2 on Cu disc. The two results combined demonstrate that it is possible to coat Cu cavities with high quality MgB 2 films using HPCVD. MgB 2 coated Cu could open up a possibility of using SRF cavities at 20–25 K with cryocoolers.« less

Electrical and structural characterization of plasma polymerized polyaniline/TiO2 heterostructure diode: a comparative study of single and bilayer TiO2 thin film electrode.

PubMed

Ameen, Sadia; Akhtar, M Shaheer; Kimi, Young Soon; Yang, O-Bong; Shin, Hyung-Shik

2011-04-01

A heterostructure was fabricated using p-type plasma polymerized polyaniline (PANI) and n-type (single and bilayer) titanium dioxide (TiO2) thin film on FTO glass. The deposition of single and bilayer TiO2 thin film on FTO substrate was achieved through doctor blade followed by dip coating technique before subjected to plasma enhanced polymerization. To fabricate p-n heterostructure, a plasma polymerization of aniline was conducted using RF plasma at 13.5 MHz and at the power of 120 W on the single and bilayer TiO2 thin film electrodes. The morphological, optical and the structural characterizations revealed the formation of p-n heterostructures between PANI and TiO2 thin film. The PANI/bilayer TiO2 heterostructure showed the improved current-voltage (I-V) characteristics due to the substantial deposition of PANI molecules into the bilayer TiO2 thin film which provided good conducting pathway and reduced the degree of excitons recombination. The change of linear I-V behavior of PANI/TiO2 heterostructure to non linear behavior with top Pt contact layer confirmed the formation of Schottky contact at the interfaces of Pt layer and PANI/TiO2 thin film layers.

Coherent Fe-rich nano-scale perovskite oxide phase in epitaxial Sr2FeMoO6 films grown on cubic and scandate substrates

NASA Astrophysics Data System (ADS)

Deniz, Hakan; Preziosi, Daniele; Alexe, Marin; Hesse, Dietrich

2017-01-01

We report the growth of high-quality epitaxial Sr2FeMoO6 (SFMO) thin films on various unconventional oxide substrates, such as TbScO3, DyScO3, and Sr2Al0.3Ga0.7TaO6 (SAGT) as well as on the most commonly used one, SrTiO3 (STO), by pulsed laser deposition. The films were found to contain a foreign nano-scale phase coherently embedded inside the SFMO film matrix. Through energy dispersive X-ray spectroscopy and scanning transmission electron microscopy, we identified the foreign phase to be Sr2-xFe1+yMo1-yO6, an off-stoichiometric derivative of the SFMO compound with Fe rich content (y ≈ 0.6) and a fairly identical crystal structure to SFMO. The films on STO and SAGT exhibited very good magnetic properties with high Curie temperature values. All the samples have fairly good conducting behavior albeit the presence of a foreign phase. Despite the relatively large number of items of the foreign phase, there is no significant deterioration in the properties of the SFMO films. We discuss in detail how magneto-transport properties are affected by the foreign phase.

Effect of shortening replacement with oleogels on the rheological and tomographic characteristics of aerated baked goods.

PubMed

Lim, Jeongtaek; Jeong, Sungmin; Lee, JaeHwan; Park, Sungkwon; Lee, Jonggil; Lee, Suyong

2017-08-01

A great deal of effort has been made to reduce the use of shortening owing to the high level of saturated fats as well as the presence of trans fats. Grape seed oil high in unsaturated fats was structured with candelilla wax to form solid-like oleogels that were utilized as a shortening replacer in aerated baked goods, specifically muffins. Muffin batters with greater amounts of oleogels exhibited lower viscosity, greater shear-thinning behavior and less elastic nature. The shortening replacement with oleogels significantly increased the specific gravity of the batters, consequently affecting the muffin volume after baking. X-ray tomography indicated a lower fragmentation index (i.e. a more connected solid structure) in the oleogel-incorporated muffins, which was correlated with more enclosed and isolated air cells. A stress relaxation test showed that the shortening replacement with oleogels produced muffins with a firmer and springier texture. Based on fatty acid compositions, the ratio of saturated to unsaturated fatty acids was significantly reduced from 2.81 to 0.41. Use of the oleogels as a shortening replacer at a ratio of 1:3 by weight was effective in producing muffins with comparable quality attributes to the control with shortening. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Impedance matched thin metamaterials make metals absorbing.

PubMed

Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

2013-11-13

Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin (<1 micron), polarization independent, extremely efficient absorbers (in principle being capable to reach A > 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others.

Polycrystalline silicon thin-film transistors with location-controlled crystal grains fabricated by excimer laser crystallization

NASA Astrophysics Data System (ADS)

Tsai, Chun-Chien; Lee, Yao-Jen; Chiang, Ko-Yu; Wang, Jyh-Liang; Lee, I.-Che; Chen, Hsu-Hsin; Wei, Kai-Fang; Chang, Ting-Kuo; Chen, Bo-Ting; Cheng, Huang-Chung

2007-11-01

In this paper, location-controlled silicon crystal grains are fabricated by the excimer laser crystallization method which employs amorphous silicon spacer structure and prepatterned thin films. The amorphous silicon spacer in nanometer-sized width formed using spacer technology is served as seed crystal to artificially control superlateral growth phenomenon during excimer laser irradiation. An array of 1.8-μm-sized disklike silicon grains is formed, and the n-channel thin-film transistors whose channels located inside the artificially-controlled crystal grains exhibit higher performance of field-effect-mobility reaching 308cm2/Vs as compared with the conventional ones. This position-manipulated silicon grains are essential to high-performance and good uniformity devices.

Highly crystalline MoS{sub 2} thin films grown by pulsed laser deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serrao, Claudy R.; You, Long; Gadgil, Sushant

2015-02-02

Highly crystalline thin films of MoS{sub 2} were prepared over large area by pulsed laser deposition down to a single monolayer on Al{sub 2}O{sub 3} (0001), GaN (0001), and SiC-6H (0001) substrates. X-ray diffraction and selected area electron diffraction studies show that the films are quasi-epitaxial with good out-of-plane texture. In addition, the thin films were observed to be highly crystalline with rocking curve full width half maxima of 0.01°, smooth with a RMS roughness of 0.27 nm, and uniform in thickness based on Raman spectroscopy. From transport measurements, the as-grown films were found to be p-type.

Analysis of the tunable asymmetric fiber F-P cavity for fiber strain sensor edge-filter demodulation

NASA Astrophysics Data System (ADS)

Chen, Haotao; Liang, Youcheng

2014-12-01

An asymmetric fiber (Fabry-Pérot, F-P) interferometric cavity with the good linearity and wide dynamic range was successfully designed based on the optical thin film characteristic matrix theory; by adjusting the material of two different thin metallic layers, the asymmetric fiber F-P interferometric cavity was fabricated by depositing the multi-layer thin films on the optical fiber's end face. The asymmetric F-P cavity has the extensive potential application. In this paper, the demodulation method for the wavelength shift of the fiber Bragg grating (FBG) sensor based on the F-P cavity is demonstrated, and a theoretical formula is obtained. And the experimental results coincide well with the computational results obtained from the theoretical model.

Amorphous and Crystalline Vanadium Oxides as High-Energy and High-Power Cathodes for Three-Dimensional Thin-Film Lithium Ion Batteries.

PubMed

Mattelaer, Felix; Geryl, Kobe; Rampelberg, Geert; Dendooven, Jolien; Detavernier, Christophe

2017-04-19

Flexible wearable electronics and on-chip energy storage for wireless sensors drive rechargeable batteries toward thin-film lithium ion batteries. To enable more charge storage on a given surface, higher energy density materials are required, while faster energy storage and release can be obtained by going to thinner films. Vanadium oxides have been examined as cathodes in classical and thin-film lithium ion batteries for decades, but amorphous vanadium oxide thin films have been mostly discarded. Here, we investigate the use of atomic layer deposition, which enables electrode deposition on complex three-dimensional (3D) battery architectures, to obtain both amorphous and crystalline VO 2 and V 2 O 5 , and we evaluate their thin-film cathode performance. Very high volumetric capacities are found, alongside excellent kinetics and good cycling stability. Better kinetics and higher volumetric capacities were observed for the amorphous vanadium oxides compared to their crystalline counterparts. The conformal deposition of these vanadium oxides on silicon micropillar structures is demonstrated. This study shows the promising potential of these atomic layer deposited vanadium oxides as cathodes for 3D all-solid-state thin-film lithium ion batteries.

Optimization of an asymmetric thin-walled tube in rotary draw bending process

NASA Astrophysics Data System (ADS)

Xue, Xin; Liao, Juan; Vincze, Gabriela; Gracio, Jose J.

2013-12-01

The rotary draw bending is one of the advanced thin-walled tube forming processes with high efficiency, low consumption and good flexibility in several industries such as automotive, aerospace and shipping. However it may cause undesirable deformations such as over-thinning and ovalization, which bring the weakening of the strength and difficulties in the assembly process respectively. Accurate modeling and effective optimization design to eliminate or reduce undesirable deformations in tube bending process have been a challenging topic. In this paper, in order to study the deformation behaviors of an asymmetric thin-walled tube in rotary draw bending process, a 3D elastic-plastic finite element model has been built under the ABAQUS environment, and the reliability of the model is validated by comparison with experiment. Then, the deformation mechanism of thin-walled tube in bending process was briefly analysis and the effects of wall thickness ratio, section height width ratio and mandrel extension on wall thinning and ovalization in bending process were investigated by using Response Surface Methodology. Finally, multi-objective optimization method was used to obtain an optimum solution of design variables based on simulation results.

Thermal conductivity model for nanoporous thin films

NASA Astrophysics Data System (ADS)

Huang, Congliang; Zhao, Xinpeng; Regner, Keith; Yang, Ronggui

2018-03-01

Nanoporous thin films have attracted great interest because of their extremely low thermal conductivity and potential applications in thin thermal insulators and thermoelectrics. Although there are some numerical and experimental studies about the thermal conductivity of nanoporous thin films, a simplified model is still needed to provide a straightforward prediction. In this paper, by including the phonon scattering lifetimes due to film thickness boundary scattering, nanopore scattering and the frequency-dependent intrinsic phonon-phonon scattering, a fitting-parameter-free model based on the kinetic theory of phonon transport is developed to predict both the in-plane and the cross-plane thermal conductivities of nanoporous thin films. With input parameters such as the lattice constants, thermal conductivity, and the group velocity of acoustic phonons of bulk silicon, our model shows a good agreement with available experimental and numerical results of nanoporous silicon thin films. It illustrates that the size effect of film thickness boundary scattering not only depends on the film thickness but also on the size of nanopores, and a larger nanopore leads to a stronger size effect of the film thickness. Our model also reveals that there are different optimal structures for getting the lowest in-plane and cross-plane thermal conductivities.

Highly uniform resistive switching properties of amorphous InGaZnO thin films prepared by a low temperature photochemical solution deposition method.

PubMed

Hu, Wei; Zou, Lilan; Chen, Xinman; Qin, Ni; Li, Shuwei; Bao, Dinghua

2014-04-09

We report on highly uniform resistive switching properties of amorphous InGaZnO (a-IGZO) thin films. The thin films were fabricated by a low temperature photochemical solution deposition method, a simple process combining chemical solution deposition and ultraviolet (UV) irradiation treatment. The a-IGZO based resistive switching devices exhibit long retention, good endurance, uniform switching voltages, and stable distribution of low and high resistance states. Electrical conduction mechanisms were also discussed on the basis of the current-voltage characteristics and their temperature dependence. The excellent resistive switching properties can be attributed to the reduction of organic- and hydrogen-based elements and the formation of enhanced metal-oxide bonding and metal-hydroxide bonding networks by hydrogen bonding due to UV irradiation, based on Fourier-transform-infrared spectroscopy, X-ray photoelectron spectroscopy, and Field emission scanning electron microscopy analysis of the thin films. This study suggests that a-IGZO thin films have potential applications in resistive random access memory and the low temperature photochemical solution deposition method can find the opportunity for further achieving system on panel applications if the a-IGZO resistive switching cells were integrated with a-IGZO thin film transistors.

Developing high-transmittance heterojunction diodes based on NiO/TZO bilayer thin films

PubMed Central

2013-01-01

In this study, radio frequency magnetron sputtering was used to deposit nickel oxide thin films (NiO, deposition power of 100 W) and titanium-doped zinc oxide thin films (TZO, varying deposition powers) on glass substrates to form p(NiO)-n(TZO) heterojunction diodes with high transmittance. The structural, optical, and electrical properties of the TZO and NiO thin films and NiO/TZO heterojunction devices were investigated with scanning electron microscopy, X-ray diffraction (XRD) patterns, UV-visible spectroscopy, Hall effect analysis, and current-voltage (I-V) analysis. XRD analysis showed that only the (111) diffraction peak of NiO and the (002) and (004) diffraction peaks of TZO were observable in the NiO/TZO heterojunction devices, indicating that the TZO thin films showed a good c-axis orientation perpendicular to the glass substrates. When the sputtering deposition power for the TZO thin films was 100, 125, and 150 W, the I-V characteristics confirmed that a p-n junction characteristic was successfully formed in the NiO/TZO heterojunction devices. We show that the NiO/TZO heterojunction diode was dominated by the space-charge limited current theory. PMID:23634999

Incorporation of N-doped TiO2 nanorods in regenerated cellulose thin films fabricated from recycled newspaper as a green portable photocatalyst.

PubMed

Mohamed, Mohamad Azuwa; Salleh, W N W; Jaafar, Juhana; Ismail, A F; Abd Mutalib, Muhazri; Jamil, Siti Munira

2015-11-20

In this work, an environmental friendly RC/N-TiO2 nanocomposite thin film was designed as a green portable photocatalyst by utilizing recycled newspaper as sustainable cellulose resource. Investigations on the influence of N-doped TiO2 nanorods incorporation on the structural and morphological properties of RC/N-TiO2 nanocomposite thin film are presented. The resulting nanocomposite thin film was characterized by FESEM, AFM, FTIR, UV-vis-NIR spectroscopy, and XPS analysis. The results suggested that there was a remarkable compatibility between cellulose and N-doped TiO2 nanorods anchored onto the surface of the RC/N-TiO2 nanocomposite thin film. Under UV and visible irradiation, the RC/N-TiO2 nanocomposite thin film showed remarkable photocatalytic activity for the degradation of methylene blue solution with degradation percentage of 96% and 78.8%, respectively. It is crucial to note that the resulting portable photocatalyst produced via an environmental and green technique in its fabrication process has good potential in the field of water and wastewater treatment application. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simulations of shear-thinning frictional non-Brownian suspensions

NASA Astrophysics Data System (ADS)

Lemaire, Elisabeth; Lobry, Laurent; Blanc, Frederic; Peters, Francois; RSC Team

2017-11-01

Most non-Brownian suspensions exhibit non-Newtonian behaviours such as anisotropic normal stresses, shear-thickening or shear-thinning. The later is still largely an open question. Acrivos wet al. (JoR 1994) proposed that particle resuspension is responsible for the apparent shear-thinning behavior in a cylindrical Couette rheometer. Another explanation has been suggested by Vasquez-Quesada et al. (PRL 2017), who noticed that some polymeric suspending liquids themselves are shear-thinning for the high shear-rate values involved in the narrow gaps between particles. Here we propose that the shear-thinning behaviour is directly connected to the solid contact between particles that has been shown to play a crucial role in the rheological behaviour of concentrated non-Brownian suspensions. In particular, it has been recently shown that frictional contact between particles greatly enhances the viscosity. Even though the friction coefficient between macroscopic surfaces does not depend on the load, it may be not the case at the scale of the low load contact between particles in suspensions. Here, we present discrete numerical simulations where the friction coefficient decreases with the interparticle forces. The obtained shear-thinning behaviour is in good agreement with our experiments.

Definition of the Spatial Resolution of X-Ray Microanalysis in Thin Foils

NASA Technical Reports Server (NTRS)

Williams, D. B.; Michael, J. R.; Goldstein, J. I.; Romig, A. D., Jr.

1992-01-01

The spatial resolution of X-ray microanalysis in thin foils is defined in terms of the incident electron beam diameter and the average beam broadening. The beam diameter is defined as the full width tenth maximum of a Gaussian intensity distribution. The spatial resolution is calculated by a convolution of the beam diameter and the average beam broadening. This definition of the spatial resolution can be related simply to experimental measurements of composition profiles across interphase interfaces. Monte Carlo calculations using a high-speed parallel supercomputer show good agreement with this definition of the spatial resolution and calculations based on this definition. The agreement is good over a range of specimen thicknesses and atomic number, but is poor when excessive beam tailing distorts the assumed Gaussian electron intensity distributions. Beam tailing occurs in low-Z materials because of fast secondary electrons and in high-Z materials because of plural scattering.

Ion assisted deposition of SiO2 film from silicon

NASA Astrophysics Data System (ADS)

Pham, Tuan. H.; Dang, Cu. X.

2005-09-01

Silicon dioxide, SiO2, is one of the preferred low index materials for optical thin film technology. It is often deposited by electron beam evaporation source with less porosity and scattering, relatively durable and can have a good laser damage threshold. Beside these advantages the deposition of critical optical thin film stacks with silicon dioxide from an E-gun was severely limited by the stability of the evaporation pattern or angular distribution of the material. The even surface of SiO2 granules in crucible will tend to develop into groove and become deeper with the evaporation process. As the results, angular distribution of the evaporation vapor changes in non-predicted manner. This report presents our experiments to apply Ion Assisted Deposition process to evaporate silicon in a molten liquid form. By choosing appropriate process parameters we can get SiO2 film with good and stable property.

Patterning Conjugated Polymers by Laser: Synergy of Nanostructure Formation in the All-Polymer Heterojunction P3HT/PCDTBT.

PubMed

Rodríguez-Rodríguez, Álvaro; Rebollar, Esther; Ezquerra, Tiberio A; Castillejo, Marta; Garcia-Ramos, Jose V; García-Gutiérrez, Mari-Cruz

2018-01-09

In this work we report a broad scenario for the patterning of semiconducting polymers by laser-induced periodic surface structures (LIPSS). Based on the LIPSS formation in the semicrystalline poly(3-hexylthiophene) (P3HT), we have extended the LIPSS fabrication to an essentially amorphous semiconducting polymer like poly[N-90-heptadecanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT). This polymer shows a good quality and well-ordered nanostructures not only at the 532 nm laser wavelength, as in the case of P3HT, but also at 266 nm providing gratings with smaller pitch. In addition, we have proven the feasibility of fabricating LIPSS in the P3HT/PCDTBT (1:1) blend, which can be considered as a model bulk-heterojunction for all-polymer solar cells. In spite of the heterogeneous roughness, due to phase separation in the blend, both P3HT and PCDTBT domains present well-defined LIPSS as well as a synergy for both components in the blend when irradiating at wavelengths of 532 and 266 nm. Both, P3HT and PCDTBT in the blend require lower fluence and less pulses in order to optimize LIPSS morphology than in the case of irradiating the homopolymers separately. Near edge X-ray absorption fine structure and Raman spectroscopy reveal a good chemical stability of both components in the blend thin films during LIPSS formation. In addition, scanning transmission X-ray spectro-microscopy shows that the mechanisms of LIPSS formation do not induce a further phase segregation neither a mixture of the components. Conducting atomic force microscopy reveals a heterogeneous electrical conductivity for the irradiated homopolymer and for the blend thin films, showing higher electrical conduction in the trenches than in the ridge regions of the LIPSS.

Optical Properties and Electrochemical Performance of LiFePO4 Thin Films Deposited on Transparent Current Collectors.

PubMed

Lee, HyunSeok; Yim, Haena; Kim, Kwang-Bum; Choi, Ji-Won

2015-11-01

LiFePO4 thin film cathodes are deposited on various transparent conducting oxide thin films on glass, which are used as cathode current collectors. The XRD patterns show that the thin films have the phase of LiFePO4 with an ordered olivine structure indexed to the orthorhombic Pmna space group. LiFePO4 thin film deposited on various TCO glass substrates exhibits transmittance of about 53%. The initial specific discharge capacities of LiFePO4 thin films are 25.0 μAh/cm2 x μm on FTO, 33.0 μAh/cm2 x μm on ITO, and 13.0 μAh/cm2 x μm on AZO coated glass substrates. Interestingly, the retention capacities of LiFePO4 thin films are 76.0% on FTO, 31.2% on ITO, and 37.7% on AZO coated glass substrates at 20th cycle. The initial specific discharge capacity of the LiFePO4/FTO electrode is slightly lower, but the discharge capacities of the LiFePO4/FTO electrode relatively decrease less than those of the others such as LiFePO4/ITO and LiFePO4/AZO with cycling. The results reported here provide the high transparency of LiFePO4 thin films cathode materials and the good candidate as FTO current collector of the LiFePO4 thin film cathode of transparent thin film rechargeable batteries due to its high transparency and cyclic retention.

Lactate: creatinine ratio in babies with thin meconium staining of amniotic fluid.

PubMed

Ojha, Rishi Kant; Singh, Saroj K; Batra, Sanjay; Sreenivas, V; Puliyel, Jacob M

2006-04-20

ACOG states meconium stained amniotic fluid (MSAF) as one of the historical indicators of perinatal asphyxia. Thick meconium along with other indicators is used to identify babies with severe intrapartum asphyxia. Lactate creatinine ratio (L:C ratio) of 0.64 or higher in first passed urine of babies suffering severe intrapartum asphyxia has been shown to predict Hypoxic Ischaemic Encephalopathy (HIE). Literature review shows that meconium is passed in distress and thin meconium results from mixing and dilution over time, which may be hours to days. Thin meconium may thus be used as an indicator of antepartum asphyxia. We tested L:C ratios in a group of babies born through thin and thick meconium, and for comparison, in a group of babies without meconium at birth. 86 consecutive newborns, 36 to 42 weeks of gestation, with meconium staining of liquor, were recruited for the study. 52 voided urine within 6 hours of birth; of these 27 had thick meconium and 25 had thin meconium at birth. 42 others, who did not have meconium or any other signs of asphyxia at birth provided controls. Lactate and creatinine levels in urine were tested by standard enzymatic methods in the three groups. Lactate values are highest in the thin MSAF group followed by the thick MSAF and controls. Creatinine was lowest in the thin MSAF, followed by thick MSAF and controls. Normal babies had an average L:C ratio of 0.13 (+/- 0.09). L:C ratio was more among thin MSAF babies (4.3 +/- 11.94) than thick MSAF babies (0.35 +/- 0.35). Median L:C ratio was also higher in the thin MSAF group. Variation in the values of these parameters is observed to be high in the thin MSAF group as compared to other groups. L:C ratio was above the cutoff of 0.64 of Huang et al in 40% of those with thin meconium. 2 of these developed signs of HIE with convulsions (HIE Sarnat and Sarnat Stage II) during hospital stay. One had L:C Ratio of 93 and the other of 58.6. A smaller proportion (20%) of those with thick meconium had levels above the cutoff and 2 developed HIE and convulsions with L:C ratio of 1.25 and 1.1 respectively. In evolving a cutoff of L:C ratios that would be highly sensitive and specific (0.64), Huang et al studied it in a series of babies with severe intrapartum asphyxia. Our study shows that the specificity may not be as good if babies born through thin meconium are also included. L:C ratios are much higher in babies with thin meconium. It may be that meconium alone is not a good indicator of asphyxia and the risk of HIE. However, if the presence of meconium implies asphyxia then perhaps a higher cut-off than 0.64 is needed. L:C ratios should be tested in a larger sample that includes babies with thin meconium, before L:C ratios can be applied universally.

Lactate: creatinine ratio in babies with thin meconium staining of amniotic fluid

PubMed Central

Ojha, Rishi Kant; Singh, Saroj K; Batra, Sanjay; Sreenivas, V; Puliyel, Jacob M

2006-01-01

Background ACOG states meconium stained amniotic fluid (MSAF) as one of the historical indicators of perinatal asphyxia. Thick meconium along with other indicators is used to identify babies with severe intrapartum asphyxia. Lactate creatinine ratio (L: C ratio) of 0.64 or higher in first passed urine of babies suffering severe intrapartum asphyxia has been shown to predict Hypoxic Ischaemic Encephalopathy (HIE). Literature review shows that meconium is passed in distress and thin meconium results from mixing and dilution over time, which may be hours to days. Thin meconium may thus be used as an indicator of antepartum asphyxia. We tested L: C ratios in a group of babies born through thin and thick meconium, and for comparison, in a group of babies without meconium at birth. Methods 86 consecutive newborns, 36 to 42 weeks of gestation, with meconium staining of liquor, were recruited for the study. 52 voided urine within 6 hours of birth; of these 27 had thick meconium and 25 had thin meconium at birth. 42 others, who did not have meconium or any other signs of asphyxia at birth provided controls. Lactate and creatinine levels in urine were tested by standard enzymatic methods in the three groups. Results Lactate values are highest in the thin MSAF group followed by the thick MSAF and controls. Creatinine was lowest in the thin MSAF, followed by thick MSAF and controls. Normal babies had an average L: C ratio of 0.13 (± 0.09). L: C ratio was more among thin MSAF babies (4.3 ± 11.94) than thick MSAF babies (0.35 ± 0.35). Median L: C ratio was also higher in the thin MSAF group. Variation in the values of these parameters is observed to be high in the thin MSAF group as compared to other groups. L: C ratio was above the cutoff of 0.64 of Huang et al in 40% of those with thin meconium. 2 of these developed signs of HIE with convulsions (HIE Sarnat and Sarnat Stage II) during hospital stay. One had L: C Ratio of 93 and the other of 58.6. A smaller proportion (20%) of those with thick meconium had levels above the cutoff and 2 developed HIE and convulsions with L: C ratio of 1.25 and 1.1 respectively. Conclusion In evolving a cutoff of L: C ratios that would be highly sensitive and specific (0.64), Huang et al studied it in a series of babies with severe intrapartum asphyxia. Our study shows that the specificity may not be as good if babies born through thin meconium are also included. L: C ratios are much higher in babies with thin meconium. It may be that meconium alone is not a good indicator of asphyxia and the risk of HIE. However, if the presence of meconium implies asphyxia then perhaps a higher cut-off than 0.64 is needed. L: C ratios should be tested in a larger sample that includes babies with thin meconium, before L: C ratios can be applied universally. PMID:16626486

Technical Note: A novel interdigital transparent thin-film detector for medical dosimetry.

PubMed

Brivio, Davide; Sajo, Erno; Zygmanski, Piotr

2017-05-01

A new type of thin-film interdigital detector (TFID) for medical dosimetry is investigated. The focus of this study was to characterize the detector response as a function of detector geometry in an attempt to optimize it and to understand the underlying radio-electrical effects leading to signal formation. We characterize the detector response to kilovoltage x-ray beams used in fluoroscopy and computed tomography. Each element (pixel) of the detector is composed of conductive intercombing digits deposited on a thin-film dielectric substrate by nanofabrication or using a printing process. The detector is practically transparent to x-ray radiation, yet it generates sufficient signal for many types of medical dosimetry and quality assurance tasks. The thin-film detector has negligible surface mass density (about 2.5 mg/cm 2 for a 1-μm-thick Cu TFID on 12.5-μm-thick Kapton substrate) and it is conformable to curved geometries found in the medical x-ray equipment or on patient skin surface. The prototype detectors were made using glass and Kapton substrates with copper-copper and copper-aluminum interdigits. Although in principle the detector can be operated without any external bias voltage when the digits are made of disparate materials (e.g., Cu-Al), we also characterized the detector properties under small electric fields via its current-voltage curve (IV curve). Using 120 kVp, 25 mA x-ray beam with 10V external bias, the Cu-Cu detector response was about 0.2 nA/cm 2 . We also measured a one-dimensional transmitted dose profile for a phantom under fluoroscopic x-rays and found relatively good agreement with a commercial photodiode (XR R12-0191, IBA Dosimetry). We demonstrated the potential of TFID detectors for kilovoltage dosimetry and we defined its optimal geometry. For digits made of the same material and for digit width equal to the separation between them, we found that the thin-film detector has optimal performance when the distance between the digit centers is about 1 mm, while in the fixed digit width cases we observed that the signal is higher when their edge-to-edge separation is as small as possible. © 2017 American Association of Physicists in Medicine.

Stem-quality changes on young, mixed upland hardwoods after crop-tree release

Treesearch

David L. Sonderman; David L. Sonderman

1987-01-01

Relative change of several types of stem defects was studied over an 8-year period to determine the effects of crop-tree thinning on the development of tree quality. Special interest was given to changes in relative quality associated with defect indicators of crop trees compared to trees in unthinned plots. The relative quality classes of the crop trees went from...

Into Thin Air.

ERIC Educational Resources Information Center

Kennedy, Mike

2001-01-01

Shows how schools are working to avoid the types of equipment, supplies, and maintenance practices that harm indoor air quality. Simple steps to maintaining a cleaner indoor air environment are highlighted as are steps to reducing the problem air quality and the occurrence of asthma. (GR)

How to run a successful Journal

PubMed Central

Jawaid, Shaukat Ali; Jawaid, Masood

2017-01-01

Publishing and successfully running a good quality peer reviewed biomedical scientific journal is not an easy task. Some of the pre-requisites include a competent experienced editor supported by a team. Long term sustainability of a journal will depend on good quality manuscripts, active editorial board, good quality of reviewers, workable business model to ensure financial support, increased visibility which will ensure increased submissions, indexation in various important databases, online availability and easy to use website. This manuscript outlines the logistics and technical issues which need to be resolved before starting a new journal and ensuring sustainability of a good quality peer reviewed journal. PMID:29492089

Crystalline, Highly Oriented MOF Thin Film: the Fabrication and Application.

PubMed

Fu, Zhihua; Xu, Gang

2017-05-01

The thin film of metal-organic frameworks (MOFs) is a rapidly developing research area which has tremendous potential applications in many fields. One of the major challenges in this area is to fabricate MOF thin film with good crystallinity, high orientation and well-controlled thickness. In order to address this challenge, different appealing approaches have been studied intensively. Among various oriented MOF films, many efforts have also been devoted to developing novel properties and broad applications, such as in gas separator, thermoelectric, storage medium and photovoltaics. As a result, there has been a large demand for fundamental studies that can provide guidance and experimental data for further applications. In this account, we intend to present an overview of current synthetic methods for fabricating oriented crystalline MOF thin film and bring some updated applications. We give our perspective on the background, preparation and applications that led to the developments in this area and discuss the opportunities and challenges of using crystalline, highly oriented MOF thin film. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High performance VO2 thin films fabricated by room-temperature reactive magnetron sputtering and rapid thermal annealing

NASA Astrophysics Data System (ADS)

Zhan, Yongjun; Xiao, Xiudi; Lu, Yuan; Cao, Ziyi; Cheng, Haoliang; Shi, Jifu; Xu, Gang

2017-10-01

The VOx thin films are successfully prepared on glass substrate by reactive magnetron sputtering at room-temperature, and subsequently annealed by rapid thermal annealing system in N2 from 0.5Pa to 10000Pa. The effects of annealing pressure on the optical performance and phase transition temperature (Tc) of VOx thin films are systematically investigated. The results show that the VOx thin films exhibit good performance with Tlum of 28.17%, ΔTsol of 12.69%, and Tc of 42. The annealing pressure had an obvious influence on the grain size, which can be attributed to light scattering effects by gas molecule. Compared with oxygen vacancy defects, the grain size plays a decisive role in the regulation of Tc. The restricting the growth of grain can be reduced the Tc, and a little deterioration effect on optical performance can be observed. In addition, the method in this paper not only depressed the Tc, but also simplified the process and improved efficiency, which will provide guidance for the preparation and application of VOx thin films.

Effect of film thickness on soft magnetic behavior of Fe2CoSi Heusler alloy for spin transfer torque device applications

NASA Astrophysics Data System (ADS)

Asvini, V.; Saravanan, G.; Kalaiezhily, R. K.; Raja, M. Manivel; Ravichandran, K.

2018-04-01

Fe2CoSi based Heusler alloy thin films were deposited on Si (111) wafer (substrate) of varying thickness using ultra high vacuum DC magnetron sputtering. The structural behavior was observed and found to be hold the L21 structure. The deposited thin films were characterized magnetic properties using vibrating sample magnetometer; the result shows a very high saturated magnetization (Ms), lowest coercivity (Hc), high curie transition temperature (Tc) and low hysteresis loss. Thin film thickness of 75 nm Fe2CoSi sample maintained at substrate temperature 450°C shows the lowest coercivity (Hc=7 Oe). In general, Fe2CoSi Heusler alloys curie transition temperature is very high, due to strong exchange interaction between the Fe and Co atoms. The substrate temperature was kept constant at 450°C for varying thickness (e.g. 5, 20, 50, 75 and 100 nm) of thin film sample. The 75 nm thickness thin film sample shows well crystallanity and good magnetic properties, further squareness ratio in B-H loop increases with the increase in film thickness.