Local Deplanation Of Double Reinforced Beam Cross Section Under Bending

NASA Astrophysics Data System (ADS)

Baltov, Anguel; Yanakieva, Ana

2015-12-01

Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model's plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).

Formation of the Electric Double Layer and its Effects on Moving Bodies in a Space Plasma Environment

NASA Technical Reports Server (NTRS)

Yang, Qianli; Wu, S. T.; Stone, N. H.; Li, Xiaoquing

1996-01-01

In this paper we solve the self-consistent Vlasov and Poisson equations by a numerical method to determine the local distribution function of the ion and the electron, within a thin layer near the moving body, respectively. Using these ion and electron distributions, the number density for the ions and electrons are determined, such that, the electric potential is obtained within this thin layer (i.e., measured by Debye length). Numerical results are presented for temporal evolution of the electron and ion density and its corresponding electric potential within the layer which shows the formation of electric double layer and its structures. From these numerical results, we are able to determine the maximum conditions of the electric potential, it may create satellite anomaly.

Preparation and characterization of double layer thin films ZnO/ZnO:Ag for methylene blue photodegradation

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

Wibowo, Singgih, E-mail: singgih@st.fisika.undip.ac.id; Sutanto, Heri, E-mail: herisutanto@undip.ac.id

2016-02-08

Double layer (DL) thin films of zinc oxide and silver-doped zinc oxide (ZnO/ZnO:Ag) were deposited on glass substrate by sol-gel spray coating technique. The prepared thin films were subjected for optical and photocatalytic studies. UV-visible transmission spectra shows that the subtitution of Ag in ZnO leads to band gap reduction. The influence of Ag doping on the photocatalytic activity of ZnO for the degradation of methylene blue dye was studied under solar radiation. The light absorption over an extended visible region by Ag ion doping in ZnO film contributed equally to improve the photocatalytic activity up to 98.29%.

Ultrafast atomic layer-by-layer oxygen vacancy-exchange diffusion in double-perovskite LnBaCo2O5.5+δ thin films.

PubMed

Bao, Shanyong; Ma, Chunrui; Chen, Garry; Xu, Xing; Enriquez, Erik; Chen, Chonglin; Zhang, Yamei; Bettis, Jerry L; Whangbo, Myung-Hwan; Dong, Chuang; Zhang, Qingyu

2014-04-22

Surface exchange and oxygen vacancy diffusion dynamics were studied in double-perovskites LnBaCo2O5.5+δ (LnBCO) single-crystalline thin films (Ln = Er, Pr; -0.5 < δ < 0.5) by carefully monitoring the resistance changes under a switching flow of oxidizing gas (O2) and reducing gas (H2) in the temperature range of 250 ~ 800 °C. A giant resistance change ΔR by three to four orders of magnitude in less than 0.1 s was found with a fast oscillation behavior in the resistance change rates in the ΔR vs. t plots, suggesting that the oxygen vacancy exchange diffusion with oxygen/hydrogen atoms in the LnBCO thin films is taking the layer by layer oxygen-vacancy-exchange mechanism. The first principles density functional theory calculations indicate that hydrogen atoms are present in LnBCO as bound to oxygen forming O-H bonds. This unprecedented oscillation phenomenon provides the first direct experimental evidence of the layer by layer oxygen vacancy exchange diffusion mechanism.

Uptake of Light Elements in Thin Metallic Films

NASA Astrophysics Data System (ADS)

Markwitz, Andreas; Waldschmidt, Mathias

Ion beam analysis was used to investigate the influence of substrate temperature on the inclusion of impurities during the deposition process of thin metallic single and double layers. Thin layers of gold and aluminium were deposited at different temperatures onto thin copper layers evaporated on silicon wafer substrates. The uptake of oxygen in the layers was measured using the highly sensitive non-resonant reaction 16O(d,p)170O at 920 keV. Nuclear reaction analysis was also used to probe for carbon and nitrogen with a limit of detection better than 20 ppm. Hydrogen depth profiles were measured using elastic recoil detection on the nanometer scale. Rutherford backscattering spectroscopy was used to determine the depth profiles of the metallic layers and to study diffusion processes. The combined ion beam analyses revealed an uptake of oxygen in the layers depending on the different metallic cap layers and the deposition temperature. Lowest oxygen values were measured for the Au/Cu layers, whereas the highest amount of oxygen was measured in Al/Cu layers deposited at 300°C. It was also found that with single copper layers produced at various temperatures, oxygen contamination occurred during the evaporation process and not afterwards, for example, as a consequence of the storage of the films under normal conditions for several days. Hydrogen, carbon, and nitrogen were found as impurities in the single and double layered metallic films, a finding that is in agreement with the measured oxidation behaviour of the metallic films.

Laser Radiation Pressure Acceleration of Monoenergetic Protons in an Ultra-Thin Foil

NASA Astrophysics Data System (ADS)

Eliasson, Bengt; Liu, Chuan S.; Shao, Xi; Sagdeev, Roald Z.; Shukla, Padma K.

2009-11-01

We present theoretical and numerical studies of the acceleration of monoenergetic protons in a double layer formed by the laser irradiation of an ultra-thin film. The stability of the foil is investigated by direct Vlasov-Maxwell simulations for different sets of laser-plasma parameters. It is found that the foil is stable, due to the trapping of both electrons and ions in the thin laser-plasma interaction region, where the electrons are trapped in a potential well composed of the ponderomo-tive potential of the laser light and the electrostatic potential due to the ions, and the ions are trapped in a potential well composed of the inertial potential in an accelerated frame and the electrostatic potential due to the electrons. The result is a stable double layer, where the trapped ions are accelerated to monoenergetic energies up to 100 MeV and beyond, which makes them suitable for medical applications cancer treatment. The underlying physics of trapped and untapped ions in a double layer is also investigated theoretically and numerically.

Atomic Layer Deposition Alumina-Passivated Silicon Nanowires: Probing the Transition from Electrochemical Double-Layer Capacitor to Electrolytic Capacitor.

PubMed

Gaboriau, Dorian; Boniface, Maxime; Valero, Anthony; Aldakov, Dmitry; Brousse, Thierry; Gentile, Pascal; Sadki, Said

2017-04-19

Silicon nanowires were coated by a 1-5 nm thin alumina layer by atomic layer deposition (ALD) in order to replace poorly reproducible and unstable native silicon oxide by a highly conformal passivating alumina layer. The surface coating enabled probing the behavior of symmetric devices using such electrodes in the EMI-TFSI electrolyte, allowing us to attain a large cell voltage up to 6 V in ionic liquid, together with very high cyclability with less than 4% capacitance fade after 10 6 charge/discharge cycles. These results yielded fruitful insights into the transition between an electrochemical double-layer capacitor behavior and an electrolytic capacitor behavior. Ultimately, thin ALD dielectric coatings can be used to obtain hybrid devices exhibiting large cell voltage and excellent cycle life of dielectric capacitors, while retaining energy and power densities close to the ones displayed by supercapacitors.

Incorporation of layered double nanomaterials in thin film nanocomposite nanofiltration membrane for magnesium sulphate removal

NASA Astrophysics Data System (ADS)

Hanis Tajuddin, Muhammad; Yusof, Norhaniza; Salleh, Wan Norharyati Wan; Fauzi Ismail, Ahmad; Hanis Hayati Hairom, Nur; Misdan, Nurasyikin

2018-03-01

Thin film nanocomposite (TFN) membrane with copper-aluminium layered double hydroxides (LDH) incorporated into polyamide (PA) selective layer has been prepared for magnesium sulphate salt removal. 0, 0.05, 0.1, 0.15, 0.2 wt% of LDH were dispersed in the trimesoyl chloride (TMC) in n-hexane as organic solution and embedded into PA layer during interfacial polymerization with piperazine. The fabricated membranes were further characterized to evaluate its morphological structure and membrane surface hydrophilicity. The TFN membranes performance were evaluated with divalent salt magnesium sulphate (MgSO4) removal and compared with thin film composite (TFC). The morphological structures of TFN membranes were altered and the surface hydrophilicity were enhanced with addition of LDH. Incorporation of LDH has improved the permeate water flux by 82.5% compared to that of TFC membrane with satisfactory rejection of MgSO4. This study has experimentally validated the potential of LDH to improve the divalent salt separation performance for TFN membranes.

Investigation of the superconducting proximity effect (SPE) and magnetic dead layers (MDL) in thin film double layers

NASA Astrophysics Data System (ADS)

Tateishi, Go

When a thin superconducting film (S film) is condensed onto a thin normal conducting film (N film), the first layers of the S film loose their superconductivity. This phenomenon is generally called the "superconducting proximity effect (SPE)". As an investigation of SPE we focus on the transition temperature of extremely thin NS double layers in the thin regime. Normal metal is condensed on top of insulating Sb, then Pb is deposited on it in small steps. The transition temperature is plotted in an inverse Tc-reduction 1/Delta T c =1/(Ts - Tc) versus Pb thickness graph. To compare our experimental results with the theoretical prediction, a numerical calculation of the SN double layer is performed by our group using the linear gap equation. As a result, there are large discrepancies between the experimental and theoretical results generally. The results of the NS double layers can be divided into three groups in terms of their discrepancies between experiment and theory.(1) Non-coupling (Tc = 0 K): N= Mg, Ag, Cu, Au. There are large deviations between experiment and theory by a factor to the order of 2.5. (2) Weak coupling (Tc is low (< 2.5 K)) : N=Cd, Zn, Al. Deviation is present, but only by a factor of 1.5. (3) Intermediate coupling (T c is around half of Pb's (≈ 4.5 K)) : N=In, Sn. The experimental results agree with the theory. Next, we examine the detection of the magnetic dead layer (MDL) of Ni thin films in terms of the anomalous Hall effect (AHE) with several non-magnetic metal substrates. In our results, when Ni film is contact with a polyvalent metal substrate film, the sandwich film has around 2 to 3.5 at.lay. of magnetic dead layers. However we have not observed the magnetic dead Ni layers with the alkali and noble metal substrate film. Finally, we revisit the Pb/Ni system to measure the magnetic scattering of Ni with the method of Weak Localization (WL) to compare with the dephasing rate due to the Tc-reduction. In this series, we use only very thin Pb films between 1.3 and 5 at.lay. deposited on top of the Ag substrate with about 37 at.lay. thickness, because we make the Ag substrate suppress the superconductivity of the extremely thin Pb film with the SPE and avoid the Azlamazov-Larkin fluctuations. After comparison, it becomes clear that the dephasing rate from the Tc-reduction method is much larger than that measured by the weak localization (the factor is around 120). We consider not only "pair breaking" but also "pair weakening", and conclude that the reduction of the superconducting transition temperature is not due to dephasing by magnetic scattering but due to the resonance scattering of Cooper pairs by non-magnetic d-states.

Fabrication and performance of a double layered Mn-Co-Ni-O/Mn-Co-Ni-Cu-O thin film detector

NASA Astrophysics Data System (ADS)

Zhou, Wei; Yin, Yiming; Yao, Niangjuan; Jiang, Lin; Qu, Yue; Wu, Jing; Gao, Y. Q.; Huang, Jingguo; Huang, Zhiming

2018-01-01

A thermal sensitive infrared and THz detector was fabricated by a double layered Mn-Co-Ni-O/Mn-Co-Ni-Cu-O films. The Mn-Co-Ni-O material, as one type of transition metal oxides, has long been used as a candidate for thermal sensors or infrared detectors. The resistivity of a most important Mn-Co-Ni-O thin film, Mn1. 96Co0.96Ni0.48O4(MCN) , is about 200 Ω·cm at room temperature, which ranges about 2 orders larger than that of VOx detectors. Therefore, the thickness of a typical squared Mn-Co-Ni-O IR detector should be about 10 μm, which is too large for focal plane arrays applications. To reduce the resistivity of Mn-Co-Ni-O thin film, 1/6 of Co element was replaced by Cu. Meanwhile, a cover layer of MCN film was deposited onto the Mn-Co-Ni-Cu-O film to improve the long term stability. The detector fabricated by the double layered Mn-Co-Ni-O/Mn-Co-Ni-Cu-O films showed large response to blackbody and 170 GHz radiation. The NEP of the detector was estimated to be the order of 10-8 W/Hz0. 5. By applying thermal isolation structure and additional absorption materials, the detection performance can be largely improved by 1-2 orders according to numerical estimation. The double layered Mn-Co-Ni-O film detector shows great potentials in applications in large scale IR detection arrays, and broad-band imaging.

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.

Role of Al2O3 thin layer on improving the resistive switching properties of Ta5Si3-based conductive bridge random accesses memory device

NASA Astrophysics Data System (ADS)

Kumar, Dayanand; Aluguri, Rakesh; Chand, Umesh; Tseng, Tseung-Yuen

2018-04-01

Ta5Si3-based conductive bridge random access memory (CBRAM) devices have been investigated to improve their resistive switching characteristics for their application in future nonvolatile memory technology. Changes in the switching characteristics by the addition of a thin Al2O3 layer of different thicknesses at the bottom electrode interface of a Ta5Si3-based CBRAM devices have been studied. The double-layer device with a 1 nm Al2O3 layer has shown improved resistive switching characteristics over the single layer one with a high on/off resistance ratio of 102, high endurance of more than 104 cycles, and good retention for more than 105 s at the temperature of 130 °C. The higher thermal conductivity of Al2O3 over Ta5Si3 has been attributed to the enhanced switching properties of the double-layer devices.

Epitaxial growth of YBa2Cu3O7 - delta films on oxidized silicon with yttria- and zirconia-based buffer layers

NASA Astrophysics Data System (ADS)

Pechen, E. V.; Schoenberger, R.; Brunner, B.; Ritzinger, S.; Renk, K. F.; Sidorov, M. V.; Oktyabrsky, S. R.

1993-09-01

A study of epitaxial growth of YBa2Cu3O7-δ films on oxidized Si with yttria- and zirconia-based buffer layers is reported. Using substrates with either SiO2 free or naturally oxidized (100) surfaces of Si it was found that a thin SiO2 layer on top of the Si favors high-quality superconducting film formation. Compared to yttria-stabilized ZrO2 (YSZ) single layers, YSZY2O3 double and YSZ/Y2O3YSZ triple layers allows the deposition of thin YBa2Cu3O7-δ films with improved properties including reduced aging effects. In epitaxial YBa2Cu3O7-δ films grown on the double buffer layers a critical temperature Tc(R=0)=89.5 K and critical current densities of 3.5×106 A/cm2 at 77 K and 1×107 A/cm2 at 66 K were reached.

Performance study of double SOI image sensors

NASA Astrophysics Data System (ADS)

Miyoshi, T.; Arai, Y.; Fujita, Y.; Hamasaki, R.; Hara, K.; Ikegami, Y.; Kurachi, I.; Nishimura, R.; Ono, S.; Tauchi, K.; Tsuboyama, T.; Yamada, M.

2018-02-01

Double silicon-on-insulator (DSOI) sensors composed of two thin silicon layers and one thick silicon layer have been developed since 2011. The thick substrate consists of high resistivity silicon with p-n junctions while the thin layers are used as SOI-CMOS circuitry and as shielding to reduce the back-gate effect and crosstalk between the sensor and the circuitry. In 2014, a high-resolution integration-type pixel sensor, INTPIX8, was developed based on the DSOI concept. This device is fabricated using a Czochralski p-type (Cz-p) substrate in contrast to a single SOI (SSOI) device having a single thin silicon layer and a Float Zone p-type (FZ-p) substrate. In the present work, X-ray spectra of both DSOI and SSOI sensors were obtained using an Am-241 radiation source at four gain settings. The gain of the DSOI sensor was found to be approximately three times that of the SSOI device because the coupling capacitance is reduced by the DSOI structure. An X-ray imaging demonstration was also performed and high spatial resolution X-ray images were obtained.

Electric double-layer capacitance between an ionic liquid and few-layer graphene.

PubMed

Uesugi, Eri; Goto, Hidenori; Eguchi, Ritsuko; Fujiwara, Akihiko; Kubozono, Yoshihiro

2013-01-01

Ionic-liquid gates have a high carrier density due to their atomically thin electric double layer (EDL) and extremely large geometrical capacitance Cg. However, a high carrier density in graphene has not been achieved even with ionic-liquid gates because the EDL capacitance CEDL between the ionic liquid and graphene involves the series connection of Cg and the quantum capacitance Cq, which is proportional to the density of states. We investigated the variables that determine CEDL at the molecular level by varying the number of graphene layers n and thereby optimising Cq. The CEDL value is governed by Cq at n < 4, and by Cg at n > 4. This transition with n indicates a composite nature for CEDL. Our finding clarifies a universal principle that determines capacitance on a microscopic scale, and provides nanotechnological perspectives on charge accumulation and energy storage using an ultimately thin capacitor.

Electric double-layer capacitance between an ionic liquid and few-layer graphene

PubMed Central

Uesugi, Eri; Goto, Hidenori; Eguchi, Ritsuko; Fujiwara, Akihiko; Kubozono, Yoshihiro

2013-01-01

Ionic-liquid gates have a high carrier density due to their atomically thin electric double layer (EDL) and extremely large geometrical capacitance Cg. However, a high carrier density in graphene has not been achieved even with ionic-liquid gates because the EDL capacitance CEDL between the ionic liquid and graphene involves the series connection of Cg and the quantum capacitance Cq, which is proportional to the density of states. We investigated the variables that determine CEDL at the molecular level by varying the number of graphene layers n and thereby optimising Cq. The CEDL value is governed by Cq at n < 4, and by Cg at n > 4. This transition with n indicates a composite nature for CEDL. Our finding clarifies a universal principle that determines capacitance on a microscopic scale, and provides nanotechnological perspectives on charge accumulation and energy storage using an ultimately thin capacitor. PMID:23549208

A Simple Visualization of Double Bond Properties: Chemical Reactivity and UV Fluorescence

ERIC Educational Resources Information Center

Grayson, Scott M.

2012-01-01

A simple, easily visualized thin-layer chromatography (TLC) staining experiment is presented that highlights the difference in reactivity between aromatic double bonds and nonaromatic double bonds. Although the stability of aromatic systems is a major theme in organic chemistry, the concept is rarely reinforced "visually" in the undergraduate…

Strongly nonlinear dynamics of electrolytes in large ac voltages.

PubMed

Højgaard Olesen, Laurits; Bazant, Martin Z; Bruus, Henrik

2010-07-01

We study the response of a model microelectrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes, ignoring any transverse instability or fluid flow. We analyze the resulting one-dimensional problem by matched asymptotic expansions in the limit of thin double layers and extend previous work into the strongly nonlinear regime, which is characterized by two features--significant salt depletion in the electrolyte near the electrodes and, at very large voltage, the breakdown of the quasiequilibrium structure of the double layers. The former leads to the prediction of "ac capacitive desalination" since there is a time-averaged transfer of salt from the bulk to the double layers, via oscillating diffusion layers. The latter is associated with transient diffusion limitation, which drives the formation and collapse of space-charge layers, even in the absence of any net Faradaic current through the cell. We also predict that steric effects of finite ion sizes (going beyond dilute-solution theory) act to suppress the strongly nonlinear regime in the limit of concentrated electrolytes, ionic liquids, and molten salts. Beyond the model problem, our reduced equations for thin double layers, based on uniformly valid matched asymptotic expansions, provide a useful mathematical framework to describe additional nonlinear responses to large ac voltages, such as Faradaic reactions, electro-osmotic instabilities, and induced-charge electrokinetic phenomena.

The Role of Superthermal Electrons in the Formation of Double Layers and their Application in Space Plasmas

NASA Astrophysics Data System (ADS)

Singh, N.

2014-12-01

It is now widely recognized that superthermal electrons commonly exist with the thermal population in most space plasmas. When plasmas consisting of such electron population expand, double layers (DLs) naturally forma due to charge separation; the more mobile superthermal electrons march ahead of the thermal population, leaving a positive charge behind and generating electric fields. Under certain conditions such fields evolve into thin double layers or shocks. The double layers accelerate ions. Such double-layer formation was first invoked to explain expansion of laser produced plasmas. Since then it has been studied in laboratory experiments, and applied to (i) polar wind acceleration,(ii) the existence of low-altitude double layers in the auroral acceleration, (iii) a possible mechanism for the origination of the solar wind, (iv) the helicon double layer thrusters, and (v) the deceleration of electrons after their acceleration in solar flare events. The role of superthermal-electron driven double layers, also known as the low-altitude auroral double layers in the upward current region, in the upward acceleration of ionospheric ions is well-known. In the auroral application the upward moving superthermal electrons consist of backscattered downgoing primary energetic electrons as well as the secondary electrons. Similarly we suggest that such double layers might play roles in the acceleration of ions in the solar wind across the coronal transition region, where the superthermal electrons are supplied by magnetic reconnection events. We will present a unified theoretical view of the superthermal electron-driven double layers and their applications. We will summarize theoretical, experimental, simulation and observational results highlighting the common threads running through the various existing studies.

Indium droplet formation in InGaN thin films with single and double heterojunctions prepared by MOCVD

PubMed Central

2014-01-01

Indium gallium nitride (InGaN) samples with single heterojunction (SH) and double heterojunction (DH) were prepared using metal-organic chemical vapor deposition. SH has a layer of InGaN thin film (thicknesses, 25, 50, 100, and 200 nm) grown on an uGaN film (thickness, 2 μm). The DH samples are distinguished by DH uGaN film (thickness, 120 nm) grown on the InGaN layer. Reciprocal space mapping measurements reveal that the DH samples are fully strained with different thicknesses, whereas the strain in the SH samples are significantly relaxed with the increasing thickness of the InGaN film. Scanning electron microscopy results show that the surface roughness of the sample increases when the sample is relaxed. High-resolution transmission electron microscopy images of the structure of indium droplets in the DH sample indicate that the thickness of the InGaN layer decreases with the density of indium droplets. The formation of these droplets is attributed to the insufficient kinetic energy of indium atom to react with the elements of group V, resulting to aggregation. The gallium atoms in the GaN thin film will not be uniformly replaced by indium atoms; the InGaN thin film has an uneven distribution of indium atoms and the quality of the epitaxial layer is degraded. PMID:25024692

Organic Field Effect Transistor Using Amorphous Fluoropolymer as Gate Insulating Film

NASA Astrophysics Data System (ADS)

Kitajima, Yosuke; Kojima, Kenzo; Mizutani, Teruyoshi; Ochiai, Shizuyasu

Organic field effect transistors are fabricated by the active layer of Regioregular poly (3-hexylthiophene-2,5-diy)(P3HT) thin film. CYTOP thin film made from Amorphous Fluoropolymer and fabricated by spin-coating is adopted to a gate dielectric layer on Polyethylenenaphthalate (PEN) thin film that is the substrate of an organic field effect transistor. The surface morphology and molecular orientation of P3HT thin films is observed by atomic force microscope (AFM) and X-Ray diffractometer (XRD). Grains are observed on the CYTOP thin film via an AFM image and the P3HT molecule is oriented perpendicularly on the CYTOP thin film. Based on the performance of the organic field effect transistor, the carrier mobility is 0.092 cm2/Vs, the ON/OFF ratio is 7, and the threshold voltage is -12 V. The ON/OFF ratio is relatively low and to improve On/Off ratio, the CYTOP/Polyimide double gate insulating layer is adopted to OFET.

Control of Interfacial Phenomena in Artificial Oxide Heterostructures

DTIC Science & Technology

2015-09-01

heterostructures using the field effect to control superconductivity, magnetism, and metal‐insulator transitions. We also identify the existence of double TiO2 ...double TiO2 layers play a crucial role in determining the superconducting states of monolayer FeSe/SrTiO3. 15. SUBJECT TERMS Thin films, conductor...development of oxide‐based electronic devices.  We also identify the existence of double  TiO2   layers at the surface of SrTiO3 in the recently

Improved Epitaxy and Surface Morphology in YBa2Cu3Oy Thin Films Grown on Double Buffered Si Wafers

NASA Astrophysics Data System (ADS)

Gao, J.; Kang, L.; Wong, H. Y.; Cheung, Y. L.; Yang, J.

Highly epitaxial thin films of YBCO have been obtained on silicon wafers using a Eu2CuO4/YSZ (yttrium-stabilized ZrO2) double buffer. Our results showed that application of such a double buffer can significantly enhance the epitaxy of grown YBCO. It also leads to an excellent surface morphology. The average surface roughness was found less than 5 nm in a large range. The results of X-ray small angle reflection and positron spectroscpy demonstrate a very clear and flat interface between YBCO and buffer layers. The Eu2CuO4/YSZ double buffer could be promising for coating high-TC superconducting films on various reactive substrates.

Sol-gel preparation of self-cleaning SiO2-TiO2/SiO2-TiO2 double-layer antireflective coating for solar glass

NASA Astrophysics Data System (ADS)

Lin, Wensheng; Zheng, Jiaxian; Yan, Lianghong; Zhang, Xinxiang

2018-03-01

Self-cleaning SiO2-TiO2/SiO2-TiO2 double-layer antireflective (AR) coating is prepared by sol-gel process. SiO2 sol is prepared by using tetraethyl orthosilicate (TEOS) as precursor and ammonia as catalyst, while TiO2 sol was prepared by using tetrabutyl orthotitanate (TBOT) as precursor and hydrochloric acid as catalyst. The effect of TiO2 content on refractive index, abrasion-resistance and photo-catalytic activity of SiO2-TiO2 hybrid thin films or powders is systematically investigated. It is found that the refractive index of SiO2-TiO2 hybrid thin films increases gradually from 1.18 to 1.53 as the weight ratio of TiO2 to SiO2 increased from 0 to 1.0. The SiO2-TiO2 hybrid thin film and powder possesses good abrasion-resistance and photo-catalytic activity, respectively, as the weight ratio of TiO2 to SiO2 is 0.4. The degradation degree of Rhodamine B by SiO2-TiO2 hybrid powder is 88.3%. Finally, SiO2-TiO2/SiO2-TiO2 double-layer AR coating with high transmittance, abrasion-resistance and self-cleaning property is realized.

Synthesis of bimetallic nanostructures by nanosecond laser ablation of multicomponent thin films in water

NASA Astrophysics Data System (ADS)

Nikov, R. G.; Nedyalkov, N. N.; Atanasov, P. A.; Karashanova, D. B.

2018-03-01

The paper presents results on nanosecond laser ablation of thin films immersed in a liquid. The thin films were prepared by consecutive deposition of layers of different metals by thermal evaporation (first layer) and classical on-axis pulsed laser deposition (second layer); Ni/Au, Ag/Au and Ni/Ag thin films were thus deposited on glass substrates. The as-prepared films were then placed at the bottom of a glass vessel filled with double distilled water and irradiated by nanosecond laser pulses delivered by a Nd:YAG laser system at λ = 355 nm. This resulted in the formation of colloids of the thin films’ material. We also compared the processes of ablation of a bulk target and a thin film in the liquid by irradiating a Au target and a Au thin film by the same laser wavelength and fluence (λ = 355 nm, F = 5 J/cm2). The optical properties of the colloids were evaluated by optical transmittance measurements in the UV– VIS spectral range. Transmission electron microscopy was employed to estimate the particles’ size distribution.

Streaming potential generated by a pressure-driven flow over a super-hydrophobic surface

NASA Astrophysics Data System (ADS)

Zhao, Hui

2010-11-01

The streaming potential generated by a pressured-driven flow over a weakly charged striped slip-stick surface (the zeta potential of the surface is smaller than the thermal potential (25 mV) with an arbitrary double layer thickness is theoretically studied by solving the Poisson-Boltzmann equation and Stokes equation. A series solution of the streaming potential is derived. Approximate expressions for the streaming potential in the limits of thin double layers and thick double layers are also presented, in excellent agreement with the full solution. The streaming potential is compared against that over a homogenously charged smooth surface. Our results indicate that the streaming potential over a super-hydrophobic surface only can be enhanced when the liquid-gas interface is charged. In addition, as the double layer thickness increases, the advantage of the super-hydrophobic surface diminishes. The impact of a slip-stick surface on the streaming potential might provide guidance for designing novel and efficient microfludic energy conversion devices using a super-hydrophobic surface.

Control of excitons in multi-layer van der Waals heterostructures

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

Calman, E. V., E-mail: ecalman@gmail.com; Dorow, C. J.; Fogler, M. M.

2016-03-07

We report an experimental study of excitons in a double quantum well van der Waals heterostructure made of atomically thin layers of MoS{sub 2} and hexagonal boron nitride. The emission of neutral and charged excitons is controlled by gate voltage, temperature, and both the helicity and the power of optical excitation.

Scintillating fibres coupled to silicon photomultiplier prototypes for fast beam monitoring and thin timing detectors

NASA Astrophysics Data System (ADS)

Papa, A.; Kettle, P.-R.; Ripiccini, E.; Rutar, G.

2016-07-01

Several scintillating fibre prototypes (single- and double-layers) made of 250 μm multi-clad square fibres coupled to silicon photomultiplier have been studied using electrons, positrons and muons at different energies. Current measurements show promising results: already for a single fibre layer and minimum ionizing particles we obtain a detection efficiency ≥ 95 % (mean collected light/fibre ≈ 8 phe), a timing resolution of 550 ps/fibre and a foreseen spatial resolution < 100 μm, based on the achieved negligible optical cross-talk between fibres (< 1 %). We will also discuss the performances of a double-layer staggered prototype configuration, for which a full detection efficiency (≥ 99 %) has been measured together with a timing resolution of ≈ 400 ps for double hit events.

Emergence of a Stern Layer from the Incorporation of Hydration Interactions into the Gouy-Chapman Model of the Electrical Double Layer.

PubMed

Brown, Matthew A; Bossa, Guilherme Volpe; May, Sylvio

2015-10-27

In one of the most commonly used phenomenological descriptions of the electrical double layer, a charged solid surface and a diffuse region of mobile ions are separated from each other by a thin charge-depleted Stern layer. The Stern layer acts as a capacitor that improves the classical Gouy-Chapman model by increasing the magnitude of the surface potential and limiting the maximal counterion concentration. We show that very similar Stern-like properties of the diffuse double layer emerge naturally from adding a nonelectrostatic hydration repulsion to the electrostatic Coulomb potential. The interplay of electrostatic attraction and hydration repulsion of the counterions and the surface leads to the formation of a diffuse counterion layer that remains well separated from the surface. In addition, hydration repulsions between the ions limit and control the maximal ion concentration and widen the width of the diffuse double layer. Our mean-field model, which we express in terms of electrostatic and hydration potentials, is physically consistent and conceptually similar to the classical Gouy-Chapman model. It allows the incorporation of ion specificity, accounts for hydration properties of charged surfaces, and predicts Stern layer properties, which we analyze in terms of the effective size of the hydrated counterions.

Superfluidity of dipolar excitons in a transition metal dichalcogenide double layer

NASA Astrophysics Data System (ADS)

Berman, Oleg L.; Kezerashvili, Roman Ya.

2017-09-01

We study formation and superfluidity of dipolar excitons in double layer heterostructures formed by two transition metal dichalcogenide (TMDC) atomically thin layers. Considering screening effects for an electron-hole interaction via the harmonic oscillator approximation for the Keldysh potential, the analytical expressions for the exciton energy spectrum and the mean field critical temperature Tc for the superfluidity are obtained. It is shown that binding energies of A excitons are larger than for B excitons. The mean field critical temperature for a two-component dilute exciton system in a TMDC double layer is analyzed and shown that the latter is an increasing function of the factor Q , determined by the effective masses of A and B excitons and their reduced mass. Comparison of the calculations for Tc performed by employing the Coulomb and Keldysh interactions demonstrates the importance of screening effects in TMDC.

Optimization of the Solution-Based Indium-Zinc Oxide/Zinc-Tin Oxide Channel Layer for Thin-Film Transistors.

PubMed

Lim, Kiwon; Choi, Pyungho; Kim, Sangsub; Kim, Hyunki; Kim, Minsoo; Lee, Jeonghyun; Hyeon, Younghwan; Koo, Kwangjun; Choi, Byoungdeog

2018-09-01

Double stacked indium-zinc oxide (IZO)/zinc-tin oxide (ZTO) active layers were employed in amorphous-oxide-semiconductor thin-film transistors (AOS TFTs). Channel layers of the TFTs were optimized by varying the molarity of ZTO back channel layers (0.05, 0.1, 0.2, 0.3 M) and the electrical properties of IZO/ZTO double stacked TFTs were compared to single IZO and ZTO TFTs with varying the molarity and molar ratio. On the basis of the results, IZO/ZTO (0.1 M) TFTs showed the excellent electrical properties of saturation mobility (13.6 cm2/V·s), on-off ratio (7×106), and subthreshold swing (0.223 V/decade) compared to ZTO (0.1 M) of 0.73 cm2/V · s, 1 × 107, 0.416 V/decade and IZO (0.04 M) of 0.10 cm2/V · s, 5 × 106, 0.60 V/decade, respectively. This may be attributed to diffusing Sn into front layer during annealing process. In addition, with varying molarity of ZTO back channel layer, from 0.1 M to 0.3 M ZTO back channel TFTs, electrical properties and positive bias stability deteriorated with increasing molarity of back channel layer because of increasing total trap states. On the other hand, 0.05 M ZTO back channel TFT had inferior electrical properties than that of 0.1 M ZTO back channel TFT. It was related to back channel effect because of having thin thickness of channel layer. Among these devices, 0.1 M ZTO back channel TFT had a lowest total trap density, outstanding electrical properties and stability. Therefore, we recommended IZO/ZTO (0.1 M) TFT as a promising channel structure for advanced display applications.

Lifetime Improvement of Organic Light Emitting Diodes using LiF Thin Film and UV Glue Encapsulation

NASA Astrophysics Data System (ADS)

Huang, Jian-Ji; Su, Yan-Kuin; Chang, Ming-Hua; Hsieh, Tsung-Eong; Huang, Bohr-Ran; Wang, Shun-Hsi; Chen, Wen-Ray; Tsai, Yu-Sheng; Hsieh, Huai-En; Liu, Mark O.; Juang, Fuh-Shyang

2008-07-01

This work demonstrates the use of lithium fluoride (LiF) as a passivation layer and a newly developed UV glue for encapsulation on the LiF passivation layer to enhance the stability of organic light-emitting devices (OLEDs). Devices with double protective layers showed a 25-fold increase in operational lifetime compared to those without any packaging layers. LiF has a low melting point and insulating characteristics and it can be adapted as both a protective layer and pre-encapsulation film. The newly developed UV glue has a fast curing time of only 6 s and can be directly spin-coated onto the surface of the LiF passivation layer. The LiF thin film plus spin-coated UV glue is a simple packaging method that reduces the fabrication costs of OLEDs.

Effect of Ionic Strength and Surface Charge Density on the Kinetics of Cellulose Nanocrystal Thin Film Swelling.

PubMed

Reid, Michael S; Kedzior, Stephanie A; Villalobos, Marco; Cranston, Emily D

2017-08-01

This work explores cellulose nanocrystal (CNC) thin films (<50 nm) and particle-particle interactions by investigating film swelling in aqueous solutions with varying ionic strength (1-100 mM). CNC film hydration was monitored in situ via surface plasmon resonance, and the kinetics of liquid uptake were quantified. The contribution of electrostatic double-layer forces to film swelling was elucidated by using CNCs with different surface charges (anionic sulfate half ester groups, high and low surface charge density, and cationic trimethylammonium groups). Total water uptake in the thin films was found to be independent of ionic strength and surface chemistry, suggesting that in the aggregated state van der Waals forces dominate over double-layer forces to hold the films together. However, the rate of swelling varied significantly. The water uptake followed Fickian behavior, and the measured diffusion constants decreased with the ionic strength gradient between the film and the solution. This work highlights that nanoparticle interactions and dispersion are highly dependent on the state of particle aggregation and that the rate of water uptake in aggregates and thin films can be tailored based on surface chemistry and solution ionic strength.

Characteristic of skin formation using zircon- and graphite-coated mold in thin wall ductile iron fabrication

NASA Astrophysics Data System (ADS)

Dhaneswara, Donanta; Suharno, Bambang; Nugroho, Janu Ageng; Ariobimo, Rianti Dewi S.; Sofyan, Nofrijon

2017-03-01

One of the problems in thin wall ductile iron (TWDI) fabrication is skin formation during the casting. The presence of this skin will decrease strength and strain of the TWDI. One of the ways to control this skin formation is to change the cooling rate during the process through a mold coating. In testing the effectiveness of skin prevention, the following variables were used for the mold coating i.e. (i) graphite: (ii) zirconium; and (iii) double layer of graphite-zirconium. After the process, the plates were characterized by non-etching, etching, tensile test, and SEM observation. The results showed that the average skin formation using graphite: 65 µm; zirconium: 13.04 µm; and double layer of graphite-zirconium: 33.25 µm. It seems that zirconium has the most effect on the skin prevention due to sulfur binding and magnesium locked, which then prevented rapid cooling resulting in less skin formation. The results also showed the number of nodules obtained in specimen with graphite: 703 nodules/mm2 with average diameter of 12.57 µm, zirconium: 798 nodules/mm2 with average diameter of 12.15 µm, and double layer of graphite-zirconium: 697 nodules/mm2 with average diameter of 11.9 µm and nodularity percentage of 82.58%, 84.53%, and 84.22%, respectively. Tensile test showed that the strength of the specimen with graphite is 301.1 MPa, with zirconium is 388.8 MPa, and with double layer of graphite-zirconium is 304 MPa. In overall, zirconium give the best performance on the skin formation prevention in TWDI fabrication.

Delaminating and restacking MgAl-layered double hydroxide monitored and characterized by a range of instrumental methods

NASA Astrophysics Data System (ADS)

Muráth, Szabolcs; Somosi, Zoltán; Tóth, Ildikó Y.; Tombácz, Etelka; Sipos, Pál; Pálinkó, István

2017-07-01

The delamination-restacking properties of MgAl-layered double hydroxide (MgAl-LDH) were studied in various solvents. The LDH samples were successfully delaminated in polar amides (formamide, N-methylformamide, N-methylacetamide). Usually, delamination was finalized by ultrasonic treatment. As rehydrating solutions, numerous Na-salts with single-, double- and triple-charged anions were used. Reconstruction was accomplished with anions of one or two negative charges, but triple-charged ones generally disrupted the rebuilding process, likely, because their salts with the metals of the LDH are very stable, and the thin layers can more readily transform to salts than the ordered materials. Samples and delamination-restacking processes were characterized by X-ray diffractometry (XRD), infrared spectroscopy (IR), dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX).

Effect of ZrO2 film thickness on the photoelectric properties of mixed-cation perovskite solar cells

NASA Astrophysics Data System (ADS)

Li, Yanyan; Zhao, Li; Wei, Shoubin; Xiao, Meng; Dong, Binghai; Wan, Li; Wang, Shimin

2018-05-01

In this work, perovskite solar cells (PSCs) were fabricated in the ambient air, with a scaffold layer composed of TiO2/ZrO2 double layer as the mesoscopic layer and carbon as the counter electrode. The effect of ZrO2 thin film thickness on the photovoltaic performances of PSCs was also studied in detail. Results showed that the photoelectric properties of as-prepared PSCs largely depend on the thin film thickness due to a series of factors, including surface roughness, charge transport resistance, and electron-hole recombination rate. The power conversion efficiency of PSCs increased from 8.37% to 11.33% by varying the thin film thickness from 75 nm to 305 nm, and the optimal power conversion efficiency was realized up to the 11.33% with a thin film thickness of 167 nm. This research demonstrates a promising route for the high-efficiency and low-cost photovoltaic technology.

Improving the properties of zinc oxide thin-film surface acoustic wave device on glass substrate by introducing double alumina layers

NASA Astrophysics Data System (ADS)

Shih, Wen-Ching; Huang, Yi-Fan; Wu, Mu-Shiang

2017-10-01

ZnO films with c-axis (0002) orientation have been successfully grown by RF magnetron sputtering on Al2O3/glass substrates. The alumina films were firstly deposited on glass substrates, and then secondly deposited on interdigital transducer/ZnO film/alumina film/glass substrates by electron beam evaporation. The crystalline structure and surface roughness of the films were investigated by X-ray diffraction and atomic force microscopy, respectively. The phase velocity and coupling coefficient of the surface acoustic wave (SAW) device were both increased when we deposited the double alumina layers. On the other hand, the temperature coefficient of frequency becomes better if we increase the thickness of the lower alumina film. The experimental result is beneficial for improving the performance of the ZnO thin-film SAW devices on inexpensive glass substrates.

Temperature dependent optical properties of (002) oriented ZnO thin film using surface plasmon resonance

NASA Astrophysics Data System (ADS)

Saha, Shibu; Mehan, Navina; Sreenivas, K.; Gupta, Vinay

2009-08-01

Temperature dependent optical properties of c-axis oriented ZnO thin film were investigated using surface plasmon resonance (SPR) technique. SPR data for double layer (prism-Au-ZnO-air) and single layer (prism-Au-air) systems were taken over a temperature range (300-525 K). Dielectric constant at optical frequency and real part of refractive index of the ZnO film shows an increase with temperature. The bandgap of the oriented ZnO film was found to decrease with rise in temperature. The work indicates a promising application of the system as a temperature sensor and highlights an efficient scientific tool to study optical properties of thin film under varying ambient conditions.

Ex vivo optical characterization of in vivo grown tissues on dummy sensor implants using double integrating spheres measurement

NASA Astrophysics Data System (ADS)

Sharma, Sandeep; Goodarzi, Mohammad; Aernouts, Ben; Gellynck, Karolien; Vlaminck, Lieven; Bockstaele, Ronny; Cornelissen, Maria; Ramon, Herman; Saeys, Wouter

2014-05-01

Near infrared spectroscopy offers a promising technological platform for continuous glucose monitoring in the human body. NIR measurements can be performed in vivo with an implantable single-chip based optical NIR sensor. However, the application of NIR spectroscopy for accurate estimation of the analyte concentration in highly scattering biological systems still remains a challenge. For instance, a thin tissue layer may grow in the optical path of the sensor. As most biological tissues allow only a small fraction of the collimated light to pass, this might result in a large reduction of the light throughput. To quantify the effect of presence of a thin tissue layer in the optical path, the bulk optical properties of tissue samples grown on sensor dummies which had been implanted for several months in goats were characterized using Double Integrating Spheres and unscattered transmittance measurements. The measured values of diffuse reflectance, diffuse transmittance and collimated transmittance were used as input to Inverse Adding-Doubling algorithm to estimate the bulk optical properties of the samples. The estimates of absorption and scattering coefficients were then used to calculate the light attenuation through a thin tissue layer. Based on the lower reduction in unscattered transmittance and higher absorptivity of glucose molecules, the measurement in the combination band was found to be the better option for the implantable sensor. As the tissues were found to be highly forward scattering with very low unscattered transmittance, the diffuse transmittance measurement based sensor configuration was recommended for the implantable glucose sensor.

Synthesis and magnetic properties of the thin film exchange spring system of MnBi/FeCo

NASA Astrophysics Data System (ADS)

Sabet, S.; Hildebrandt, E.; Alff, L.

2017-10-01

Manganese bismuth thin films with a nominal thickness of ∼40 nm were grown at room temperature onto quartz glass substrate in a DC magnetron sputtering unit. In contrast to the usual multilayer approach, the MnBi films were deposited using a single sputtering target with a stoichiometry of Mn55Bi45 (at. %). A subsequent in-situ annealing step was performed in vacuum in order to form the ferromagnetic LTP of MnBi. X-ray diffraction confirmed the formation of a textured LTP MnBi hard phase after annealing at 330 °C. This film shows a maximum saturation magnetization of 530 emu/cm3, high out-of-plane coercivity of 15 kOe induced by unreacted bismuth. The exchange coupling effect was investigated by deposition of a second layer of FeCo with 1 nm and 2 nm thickness onto the LTP MnBi films. The MnBi/FeCo double layer showed as expected higher saturation magnetization with increasing thickness of the FeCo layer while the coercive field remained constant. The fabrication of the MnBi/FeCo double layer for an exchange spring magnet was facilitated by deposition from a single stoichiometric target.

Magnetic properties and crystal texture of Co alloy thin films prepared on double bias Cr

NASA Astrophysics Data System (ADS)

Deng, Y.; Lambeth, D. N.; Lee, L.-L.; Laughlin, D. E.

1993-05-01

A double layer Cr film structure has been prepared by sputter depositing Cr on single crystal Si substrates first without substrate bias and then with various substrate bias voltages. Without substrate bias, Cr{200} texture grows on Si at room temperature; thus the first Cr layer acts like a seed Cr layer with the {200} texture, and the second Cr layer, prepared with substrate bias, tends to replicate the {200} texture epitaxially. CoCrTa and CoNiCr films prepared on these double Cr underlayers, therefore, tend to have a {112¯0} texture with their c-axes oriented in the plane of the film. At the same time, the bias sputtering of the second Cr layer increases the coercivity of the subsequently deposited magnetic films significantly. Comparison studies of δM curves show that the use of the double Cr underlayers reduces the intergranular exchange interactions. The films prepared on the Si substrates have been compared with the films prepared on canasite and glass substrates. It has also been found that the magnetic properties are similar for films on canasite and on glass.

Theoretical Study of Monolayer and Double-Layer Waveguide Love Wave Sensors for Achieving High Sensitivity.

PubMed

Li, Shuangming; Wan, Ying; Fan, Chunhai; Su, Yan

2017-03-22

Love wave sensors have been widely used for sensing applications. In this work, we introduce the theoretical analysis of the monolayer and double-layer waveguide Love wave sensors. The velocity, particle displacement and energy distribution of Love waves were analyzed. Using the variations of the energy repartition, the sensitivity coefficients of Love wave sensors were calculated. To achieve a higher sensitivity coefficient, a thin gold layer was added as the second waveguide on top of the silicon dioxide (SiO₂) waveguide-based, 36 degree-rotated, Y-cut, X-propagating lithium tantalate (36° YX LiTaO₃) Love wave sensor. The Love wave velocity was significantly reduced by the added gold layer, and the flow of wave energy into the waveguide layer from the substrate was enhanced. By using the double-layer structure, almost a 72-fold enhancement in the sensitivity coefficient was achieved compared to the monolayer structure. Additionally, the thickness of the SiO₂ layer was also reduced with the application of the gold layer, resulting in easier device fabrication. This study allows for the possibility of designing and realizing robust Love wave sensors with high sensitivity and a low limit of detection.

The double capsules in macro-textured breast implants.

PubMed

Giot, Jean-Philippe; Paek, Laurence S; Nizard, Nathanael; El-Diwany, Mostafa; Gaboury, Louis A; Nelea, Monica; Bou-Merhi, Joseph S; Harris, Patrick G; Danino, Michel A

2015-10-01

Breast implants are amongst the most widely used types of permanent implants in modern medicine and have both aesthetic and reconstructive applications with excellent biocompatibility. The double capsule is a complication associated with textured prostheses that leads to implant displacement; however, its etiology has yet to be elucidated. In this study, 10 double capsules were sampled from breast expander implants for in-depth analysis; histologically, the inner capsular layer demonstrated highly organized collagen in sheets with delamination of fibers. At the prosthesis interface (PI) where the implant shell contacts the inner capsular layer, scanning electron microscopy (SEM) revealed a thin layer which mirrored the three-dimensional characteristics of the implant texture; the external surface of the inner capsular layer facing the intercapsular space (ICS) was flat. SEM examination of the inner capsule layer revealed both a large bacterial presence as well as biofilm deposition at the PI; a significantly lower quantity of bacteria and biofilm were found at the ICS interface. These findings suggest that the double capsule phenomenon's etiopathogenesis is of mechanical origin. Delamination of the periprosthetic capsule leads to the creation of the ICS; the maintained separation of the 2 layers subsequently alters the biostability of the macro-textured breast implant. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mixed Valence Perovskite Cs2 Au2 I6 : A Potential Material for Thin-Film Pb-Free Photovoltaic Cells with Ultrahigh Efficiency.

PubMed

Debbichi, Lamjed; Lee, Songju; Cho, Hyunyoung; Rappe, Andrew M; Hong, Ki-Ha; Jang, Min Seok; Kim, Hyungjun

2018-03-01

New light is shed on the previously known perovskite material, Cs 2 Au 2 I 6 , as a potential active material for high-efficiency thin-film Pb-free photovoltaic cells. First-principles calculations demonstrate that Cs 2 Au 2 I 6 has an optimal band gap that is close to the Shockley-Queisser value. The band gap size is governed by intermediate band formation. Charge disproportionation on Au makes Cs 2 Au 2 I 6 a double-perovskite material, although it is stoichiometrically a single perovskite. In contrast to most previously discussed double perovskites, Cs 2 Au 2 I 6 has a direct-band-gap feature, and optical simulation predicts that a very thin layer of active material is sufficient to achieve a high photoconversion efficiency using a polycrystalline film layer. The already confirmed synthesizability of this material, coupled with the state-of-the-art multiscale simulations connecting from the material to the device, strongly suggests that Cs 2 Au 2 I 6 will serve as the active material in highly efficient, nontoxic, and thin-film perovskite solar cells in the very near future. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sub-Grid Modeling of Electrokinetic Effects in Micro Flows

NASA Technical Reports Server (NTRS)

Chen, C. P.

2005-01-01

Advances in micro-fabrication processes have generated tremendous interests in miniaturizing chemical and biomedical analyses into integrated microsystems (Lab-on-Chip devices). To successfully design and operate the micro fluidics system, it is essential to understand the fundamental fluid flow phenomena when channel sizes are shrink to micron or even nano dimensions. One important phenomenon is the electro kinetic effect in micro/nano channels due to the existence of the electrical double layer (EDL) near a solid-liquid interface. Not only EDL is responsible for electro-osmosis pumping when an electric field parallel to the surface is imposed, EDL also causes extra flow resistance (the electro-viscous effect) and flow anomaly (such as early transition from laminar to turbulent flow) observed in pressure-driven microchannel flows. Modeling and simulation of electro-kinetic effects on micro flows poses significant numerical challenge due to the fact that the sizes of the double layer (10 nm up to microns) are very thin compared to channel width (can be up to 100 s of m). Since the typical thickness of the double layer is extremely small compared to the channel width, it would be computationally very costly to capture the velocity profile inside the double layer by placing sufficient number of grid cells in the layer to resolve the velocity changes, especially in complex, 3-d geometries. Existing approaches using "slip" wall velocity and augmented double layer are difficult to use when the flow geometry is complicated, e.g. flow in a T-junction, X-junction, etc. In order to overcome the difficulties arising from those two approaches, we have developed a sub-grid integration method to properly account for the physics of the double layer. The integration approach can be used on simple or complicated flow geometries. Resolution of the double layer is not needed in this approach, and the effects of the double layer can be accounted for at the same time. With this approach, the numeric grid size can be much larger than the thickness of double layer. Presented in this report are a description of the approach, methodology for implementation and several validation simulations for micro flows.

Multi-layer thin-film electrolytes for metal supported solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Haydn, Markus; Ortner, Kai; Franco, Thomas; Uhlenbruck, Sven; Menzler, Norbert H.; Stöver, Detlev; Bräuer, Günter; Venskutonis, Andreas; Sigl, Lorenz S.; Buchkremer, Hans-Peter; Vaßen, Robert

2014-06-01

A key to the development of metal-supported solid oxide fuel cells (MSCs) is the manufacturing of gas-tight thin-film electrolytes, which separate the cathode from the anode. This paper focuses the electrolyte manufacturing on the basis of 8YSZ (8 mol.-% Y2O3 stabilized ZrO2). The electrolyte layers are applied by a physical vapor deposition (PVD) gas flow sputtering (GFS) process. The gas-tightness of the electrolyte is significantly improved when sequential oxidic and metallic thin-film multi-layers are deposited, which interrupt the columnar grain structure of single-layer electrolytes. Such electrolytes with two or eight oxide/metal layers and a total thickness of about 4 μm obtain leakage rates of less than 3 × 10-4 hPa dm3 s-1 cm-2 (Δp: 100 hPa) at room temperature and therefore fulfill the gas tightness requirements. They are also highly tolerant with respect to surface flaws and particulate impurities which can be present on the graded anode underground. MSC cell tests with double-layer and multilayer electrolytes feature high power densities more than 1.4 W cm-2 at 850 °C and underline the high potential of MSC cells.

Enhanced Laser-Driven Ion Acceleration by Superponderomotive Electrons Generated from Near-Critical-Density Plasma

NASA Astrophysics Data System (ADS)

Bin, J. H.; Yeung, M.; Gong, Z.; Wang, H. Y.; Kreuzer, C.; Zhou, M. L.; Streeter, M. J. V.; Foster, P. S.; Cousens, S.; Dromey, B.; Meyer-ter-Vehn, J.; Zepf, M.; Schreiber, J.

2018-02-01

We report on the experimental studies of laser driven ion acceleration from a double-layer target where a near-critical density target with a few-micron thickness is coated in front of a nanometer-thin diamondlike carbon foil. A significant enhancement of proton maximum energies from 12 to ˜30 MeV is observed when a relativistic laser pulse impinges on the double-layer target under linear polarization. We attributed the enhanced acceleration to superponderomotive electrons that were simultaneously measured in the experiments with energies far beyond the free-electron ponderomotive limit. Our interpretation is supported by two-dimensional simulation results.

Flexible nanoporous tunable electrical double layer biosensors for sweat diagnostics.

PubMed

Munje, Rujuta D; Muthukumar, Sriram; Panneer Selvam, Anjan; Prasad, Shalini

2015-09-30

An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

Flexible nanoporous tunable electrical double layer biosensors for sweat diagnostics

NASA Astrophysics Data System (ADS)

Munje, Rujuta D.; Muthukumar, Sriram; Panneer Selvam, Anjan; Prasad, Shalini

2015-09-01

An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

Phase inversion and frequency doubling of reflection high-energy electron diffraction intensity oscillations in the layer-by-layer growth of complex oxides

NASA Astrophysics Data System (ADS)

Mao, Zhangwen; Guo, Wei; Ji, Dianxiang; Zhang, Tianwei; Gu, Chenyi; Tang, Chao; Gu, Zhengbin; Nie*, Yuefeng; Pan, Xiaoqing

In situ reflection high-energy electron diffraction (RHEED) and its intensity oscillations are extremely important for the growth of epitaxial thin films with atomic precision. The RHEED intensity oscillations of complex oxides are, however, rather complicated and a general model is still lacking. Here, we report the unusual phase inversion and frequency doubling of RHEED intensity oscillations observed in the layer-by-layer growth of SrTiO3 using oxide molecular beam epitaxy. In contacts to the common understanding that the maximum(minimum) intensity occurs at SrO(TiO2) termination, respectively, we found that both maximum or minimum intensities can occur at SrO, TiO2, or even incomplete terminations depending on the incident angle of the electron beam, which raises a fundamental question if one can rely on the RHEED intensity oscillations to precisely control the growth of thin films. A general model including surface roughness and termination dependent mean inner potential qualitatively explains the observed phenomena, and provides the answer to the question how to prepare atomically and chemically precise surface/interfaces using RHEED oscillations for complex oxides. We thank National Basic Research Program of China (No. 11574135, 2015CB654901) and the National Thousand-Young-Talents Program.

Transparent Thin-Film Transistors Based on Sputtered Electric Double Layer

PubMed Central

Cai, Wensi; Ma, Xiaochen; Zhang, Jiawei; Song, Aimin

2017-01-01

Electric-double-layer (EDL) thin-film transistors (TFTs) have attracted much attention due to their low operation voltages. Recently, EDL TFTs gated with radio frequency (RF) magnetron sputtered SiO2 have been developed which is compatible to large-area electronics fabrication. In this work, fully transparent Indium-Gallium-Zinc-Oxide-based EDL TFTs on glass substrates have been fabricated at room temperature for the first time. A maximum transmittance of about 80% has been achieved in the visible light range. The transparent TFTs show a low operation voltage of 1.5 V due to the large EDL capacitance (0.3 µF/cm2 at 20 Hz). The devices exhibit a good performance with a low subthreshold swing of 130 mV/dec and a high on-off ratio > 105. Several tests have also been done to investigate the influences of light irradiation and bias stress. Our results suggest that such transistors might have potential applications in battery-powered transparent electron devices. PMID:28772789

Transparent Thin-Film Transistors Based on Sputtered Electric Double Layer.

PubMed

Cai, Wensi; Ma, Xiaochen; Zhang, Jiawei; Song, Aimin

2017-04-20

Electric-double-layer (EDL) thin-film transistors (TFTs) have attracted much attention due to their low operation voltages. Recently, EDL TFTs gated with radio frequency (RF) magnetron sputtered SiO₂ have been developed which is compatible to large-area electronics fabrication. In this work, fully transparent Indium-Gallium-Zinc-Oxide-based EDL TFTs on glass substrates have been fabricated at room temperature for the first time. A maximum transmittance of about 80% has been achieved in the visible light range. The transparent TFTs show a low operation voltage of 1.5 V due to the large EDL capacitance (0.3 µF/cm² at 20 Hz). The devices exhibit a good performance with a low subthreshold swing of 130 mV/dec and a high on-off ratio > 10⁵. Several tests have also been done to investigate the influences of light irradiation and bias stress. Our results suggest that such transistors might have potential applications in battery-powered transparent electron devices.

Three-dimensional SnO2@TiO2 double-shell nanotubes on carbon cloth as a flexible anode for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Haifeng; Ren, Weina; Cheng, Chuanwei

2015-07-01

In this study, three-dimensional SnO2@TiO2 double-shell nanotubes on carbon cloth are synthesized by a combination of the hydrothermal method for ZnO nanorods and a subsequent SnO2 and TiO2 thin film coating with atomic layer deposition (ALD). The as-prepared SnO2@TiO2 double-shell nanotubes are further tested as a flexible anode for Li ion batteries. The SnO2@TiO2 double-shell nanotubes/carbon cloth electrode exhibited a high initial discharge capacity (e.g. 778.8 mA h g-1 at a high current density of 780 mA g-1) and good cycling performance, which could be attributed to the 3D double-layer nanotube structure. The interior space of the stable TiO2 hollow tube can accommodate the large internal stress caused by volume expansion of SnO2 and protect SnO2 from pulverization and exfoliation.

Development of organic-inorganic double hole-transporting material for high performance perovskite solar cells

NASA Astrophysics Data System (ADS)

Jo, Jea Woong; Seo, Myung-Seok; Jung, Jae Woong; Park, Joon-Suh; Sohn, Byeong-Hyeok; Ko, Min Jae; Son, Hae Jung

2018-02-01

The control of the optoelectronic properties of the interlayers of perovskite solar cells (PSCs) is crucial for achieving high photovoltaic performances. Of the solution-processable interlayer candidates, NiOx is considered one of the best inorganic hole-transporting layer (HTL) materials. However, the power conversion efficiencies (PCEs) of NiOx-based PSCs are limited by the unfavorable contact between perovskite layers and NiOx HTLs, the high density of surface trap sites, and the inefficient charge extraction from perovskite photoactive layers to anodes. Here, we introduce a new organic-inorganic double HTL consisting of a Cu:NiOx thin film passivated by a conjugated polyelectrolyte (PhNa-1T) film. This double HTL has a significantly lower pinhole density and forms better contact with perovskite films, which results in enhanced charge extraction. As a result, the PCEs of PSCs fabricated with the double HTL are impressively improved up to 17.0%, which is more than 25% higher than that of the corresponding PSC with a Cu:NiOx HTL. Moreover, PSCs with the double HTLs exhibit similar stabilities under ambient conditions to devices using inorganic Cu:NiOx. Therefore, this organic-inorganic double HTL is a promising interlayer material for high performance PSCs with high air stability.

A double-layer based model of ion confinement in electron cyclotron resonance ion source.

PubMed

Mascali, D; Neri, L; Celona, L; Castro, G; Torrisi, G; Gammino, S; Sorbello, G; Ciavola, G

2014-02-01

The paper proposes a new model of ion confinement in ECRIS, which can be easily generalized to any magnetic configuration characterized by closed magnetic surfaces. Traditionally, ion confinement in B-min configurations is ascribed to a negative potential dip due to superhot electrons, adiabatically confined by the magneto-static field. However, kinetic simulations including RF heating affected by cavity modes structures indicate that high energy electrons populate just a thin slab overlapping the ECR layer, while their density drops down of more than one order of magnitude outside. Ions, instead, diffuse across the electron layer due to their high collisionality. This is the proper physical condition to establish a double-layer (DL) configuration which self-consistently originates a potential barrier; this "barrier" confines the ions inside the plasma core surrounded by the ECR surface. The paper will describe a simplified ion confinement model based on plasma density non-homogeneity and DL formation.

Shock-wave structure for a polyatomic gas with large bulk viscosity

NASA Astrophysics Data System (ADS)

Kosuge, Shingo; Aoki, Kazuo

2018-02-01

The structure of a standing plane shock wave in a polyatomic gas is investigated on the basis of kinetic theory, with special interest in gases with large bulk viscosities, such as CO2 gas. The ellipsoidal statistical model for a polyatomic gas is employed. First, the shock structure is computed numerically for various upstream Mach numbers and for various (large) values of the ratio of the bulk viscosity to the shear viscosity, and different types of profiles, such as the double-layer structure consisting of a thin upstream layer with a steep change and a much thicker downstream layer with a mild change, are obtained. Then, an asymptotic analysis for large values of the ratio is carried out, and an analytical solution that describes the different types of profiles obtained by the numerical analysis, such as the double-layer structure, correctly is obtained.

Doping Nitrogen in InGaZnO Thin Film Transistor with Double Layer Channel Structure.

PubMed

Chang, Sheng-Po; Shan, Deng

2018-04-01

This paper presents the electrical characteristics of doping nitrogen in an amorphous InGaZnO thin film transistor. The IGZO:N film, which acted as a channel layer, was deposited using RF sputtering with a nitrogen and argon gas mixture at room temperature. The optimized parameters of the IGZO:N/IGZO TFT are as follows: threshold voltage is 0.5 V, field effect mobility is 14.34 cm2V-1S-1. The on/off current ratio is 106 and subthreshold swing is 1.48 V/decade. The positive gate bias stress stability of InGaZnO doping with nitrogen shows improvement compared to doping with oxygen.

Two-Dimensional Layered Oxide Structures Tailored by Self-Assembled Layer Stacking via Interfacial Strain.

PubMed

Zhang, Wenrui; Li, Mingtao; Chen, Aiping; Li, Leigang; Zhu, Yuanyuan; Xia, Zhenhai; Lu, Ping; Boullay, Philippe; Wu, Lijun; Zhu, Yimei; MacManus-Driscoll, Judith L; Jia, Quanxi; Zhou, Honghui; Narayan, Jagdish; Zhang, Xinghang; Wang, Haiyan

2016-07-06

Study of layered complex oxides emerge as one of leading topics in fundamental materials science because of the strong interplay among intrinsic charge, spin, orbital, and lattice. As a fundamental basis of heteroepitaxial thin film growth, interfacial strain can be used to design materials that exhibit new phenomena beyond their conventional forms. Here, we report a strain-driven self-assembly of bismuth-based supercell (SC) with a two-dimensional (2D) layered structure. With combined experimental analysis and first-principles calculations, we investigated the full SC structure and elucidated the fundamental growth mechanism achieved by the strain-enabled self-assembled atomic layer stacking. The unique SC structure exhibits room-temperature ferroelectricity, enhanced magnetic responses, and a distinct optical bandgap from the conventional double perovskite structure. This study reveals the important role of interfacial strain modulation and atomic rearrangement in self-assembling a layered singe-phase multiferroic thin film, which opens up a promising avenue in the search for and design of novel 2D layered complex oxides with enormous promise.

Ultrathin Graphene Membranes as Flexible Electrodes for Electrochemical Double Layer Capacitors

NASA Astrophysics Data System (ADS)

Talapatra, Saikat; Kar, Swastik; Shah, Rakesh; Ghosh, Sujoy; An, Xiaohong; Simmons, Trevor; Washington, Morris; Nayak, Saroj

2010-03-01

We will present the results of our investigations of electrochemical double layer capacitors (EDLCs) or supercapacitors (SC) fabricated using graphene based ultra thin membranes. These EDLC's show far superior performance compared to other carbon nanomaterials based EDLC's devices. We found that the graphene based devices possess specific capacitance values as high as 120 F/g, with impressive power densities (˜105 kW/kg) and energy densities (˜9.2 Wh/kg). Further, these devices indicated rapid charge transfer response even without the use of any binders or specially prepared current collectors. Our ultracapacitors reflect a significant improvement over previously reported graphene-based ultracapacitors and are substantially better than those obtained with carbon nanotubes.

A comparative study between different approaches to improve the RCS of a compact double-layer absorber

NASA Astrophysics Data System (ADS)

El-Hakim, H. A.; Mahmoud, K. R.

2017-10-01

In this paper, straightforward and efficient techniques have been addressed into double-layer structure to enlarge the operating bandwidth to include the X, Ku and K bands, in addition to increase the electromagnetic wave absorption for wide varieties of incident angles and both polarization types. To increase the band-stop resonating frequency up to 26 GHz, an additional layer of meta-surface, circuit analog radar absorber material (CAR), or a thin radar absorber material (RAM) layer is engineered. The synthesized layers are designed based on optimization process with genetic algorithm (GA) through numerical technique (Ansoft design software HFSS) for both transmission line (T.L) and the free space method to get optimal material properties suitable for the design. For different approaches, the designed structures achieved a reflectivity value less than -16 dB on average in the desired bandwidth from 8 to 26 GHz for TE/TM modes with incidence angle up to 50o.

Time-dependent electrophoresis of a dielectric spherical particle embedded in Brinkman medium

NASA Astrophysics Data System (ADS)

Saad, E. I.; Faltas, M. S.

2018-04-01

An expression for electrophoretic apparent velocity slip in the time-dependent flow of an electrolyte solution saturated in a charged porous medium within an electric double layer adjacent to a dielectric plate under the influence of a tangential uniform electric field is derived. The velocity slip is used as a boundary condition to solve the electrophoretic motion of an impermeable dielectric spherical particle embedded in an electrolyte solution saturated in porous medium under the unsteady Darcy-Brinkman model. Throughout the system, a uniform electric field is applied and maintains with constant strength. Two cases are considered, when the electric double layer enclosing the particle is thin, but finite and when of a particle with a thick double layer. Expressions for the electrophoretic mobility of the particle as functions of the relevant parameters are found. Our results indicate that the time scale for the growth of mobility is significant and small for high permeability. Generally, the effect of the relaxation time for starting electrophoresis is negligible, irrespective of the thickness of the double layer and permeability of the medium. The effects of the elapsed time, permeability, mass density and Debye length parameters on the fluid velocity, the electrophoretic mobility and the acceleration are shown graphically.

Development of a double-layered ceramic filter for aerosol filtration at high-temperatures: the filter collection efficiency.

PubMed

de Freitas, Normanda L; Gonçalves, José A S; Innocentini, Murilo D M; Coury, José R

2006-08-25

The performance of double-layered ceramic filters for aerosol filtration at high temperatures was evaluated in this work. The filtering structure was composed of two layers: a thin granular membrane deposited on a reticulate ceramic support of high porosity. The goal was to minimize the high pressure drop inherent of granular structures, without decreasing their high collection efficiency for small particles. The reticulate support was developed using the technique of ceramic replication of polyurethane foam substrates of 45 and 75 pores per inch (ppi). The filtering membrane was prepared by depositing a thin layer of granular alumina-clay paste on one face of the support. Filters had their permeability and fractional collection efficiency analyzed for filtration of an airborne suspension of phosphatic rock in temperatures ranging from ambient to 700 degrees C. Results revealed that collection efficiency decreased with gas temperature and was enhanced with filtration time. Also, the support layer influenced the collection efficiency: the 75 ppi support was more effective than the 45 ppi. Particle collection efficiency dropped considerably for particles below 2 microm in diameter. The maximum collection occurred for particle diameters of approximately 3 microm, and decreased again for diameters between 4 and 8 microm. Such trend was successfully represented by the proposed correlation, which is based on the classical mechanisms acting on particle collection. Inertial impaction seems to be the predominant collection mechanism, with particle bouncing/re-entrainment acting as detachment mechanisms.

Fabrication and evaluation of plasmonic light-emitting diodes with thin p-type layer and localized Ag particles embedded by ITO

NASA Astrophysics Data System (ADS)

Okada, N.; Morishita, N.; Mori, A.; Tsukada, T.; Tateishi, K.; Okamoto, K.; Tadatomo, K.

2017-04-01

Light-emitting diodes (LEDs) have been demonstrated with a thin p-type layer using the plasmonic effect. Optimal LED device operation was found when using a 20-nm-thick p+-GaN layer. Ag of different thicknesses was deposited on the thin p-type layer and annealed to form the localized Ag particles. The localized Ag particles were embedded by indium tin oxide to form a p-type electrode in the LED structure. By optimization of the plasmonic LED, the significant electroluminescence enhancement was observed when the thickness of Ag was 9.5 nm. Both upward and downward electroluminescence intensities were improved, and the external quantum efficiency was approximately double that of LEDs without the localized Ag particles. The time-resolved photoluminescence (PL) decay time for the LED with the localized Ag particles was shorter than that without the localized Ag particles. The faster PL decay time should cause the increase in internal quantum efficiency by adopting the localized Ag particles. To validate the localized surface plasmon resonance coupling effect, the absorption of the LEDs was investigated experimentally and using simulations.

Cu2ZnSnSe4 Thin Film Solar Cell with Depth Gradient Composition Prepared by Selenization of Sputtered Novel Precursors.

PubMed

Lai, Fang-I; Yang, Jui-Fu; Chen, Wei-Chun; Kuo, Shou-Yi

2017-11-22

In this study, we proposed a new method for the synthesis of the target material used in a two stage process for preparation of a high quality CZTSe thin film. The target material consisting of a mixture of Cu x Se and Zn x Sn 1-x alloy was synthesized, providing a quality CZTSe precursor layer for highly efficient CZTSe thin film solar cells. The CZTSe thin film can be obtained by annealing the precursor layers through a 30 min selenization process under a selenium atmosphere at 550 °C. The CZTSe thin films prepared by using the new precursor thin film were investigated and characterized using X-ray diffraction, Raman scattering, and photoluminescence spectroscopy. It was found that diffusion of Sn occurred and formed the CTSe phase and Cu x Se phase in the resultant CZTSe thin film. By selective area electron diffraction transmission electron microscopy images, the crystallinity of the CZTSe thin film was verified to be single crystal. By secondary ion mass spectroscopy measurements, it was confirmed that a double-gradient band gap profile across the CZTSe absorber layer was successfully achieved. The CZTSe solar cell with the CZTSe absorber layer consisting of the precursor stack exhibited a high efficiency of 5.46%, high short circuit current (J SC ) of 37.47 mA/cm 2 , open circuit voltage (V OC ) of 0.31 V, and fill factor (F.F.) of 47%, at a device area of 0.28 cm 2 . No crossover of the light and dark current-voltage (I-V) curves of the CZTSe solar cell was observed, and also, no red kink was observed under red light illumination, indicating a low defect concentration in the CZTSe absorber layer. Shunt leakage current with a characteristic metal/CZTSe/metal leakage current model was observed by temperature-dependent I-V curves, which led to the discovery of metal incursion through the CdS buffer layer on the CZTSe absorber layer. This leakage current, also known as space charge-limited current, grew larger as the measurement temperature increased and completely overwhelmed the diode current at a measurement temperature of 200 °C. This is due to interlayer diffusion of metal that increases the shunt leakage current and decreases the efficiency of the CZTSe thin film solar cells.

Bioplasmonic Alloyed Nanoislands Using Dewetting of Bilayer Thin Films.

PubMed

Kang, Minhee; Ahn, Myeong-Su; Lee, Youngseop; Jeong, Ki-Hun

2017-10-25

Unlike monometallic materials, bimetallic plasmonic materials offer extensive benefits such as broadband tuning capability or high environmental stability. Here we report a broad range tuning of plasmon resonance of alloyed nanoislands by using solid-state dewetting of gold and silver bilayer thin films. Thermal dewetting after successive thermal evaporation of thin metal double-layer films readily forms AuAg-alloyed nanoislands with a precise composition ratio. The complete miscibility of alloyed nanoislands results in programmable tuning of plasmon resonance wavelength in a broadband visible range. Such extraordinary tuning capability opens up a new direction for plasmonic enhancement in biophotonic applications such as surface-enhanced Raman scattering or plasmon-enhanced fluorescence.

Determination of diffusion coefficients in polypyrrole thin films using a current pulse relaxation method

NASA Technical Reports Server (NTRS)

Penner, Reginald M.; Vandyke, Leon S.; Martin, Charles R.

1987-01-01

The current pulse E sub oc relaxation method and its application to the determination of diffusion coefficients in electrochemically synthesized polypyrrole thin films is described. Diffusion coefficients for such films in Et4NBF4 and MeCN are determined for a series of submicron film thicknesses. Measurement of the double-layer capacitance, C sub dl, and the resistance, R sub u, of polypyrrole thin films as a function of potential obtained with the galvanostatic pulse method is reported. Measurements of the electrolyte concentration in reduced polypyrrole films are also presented to aid in the interpretation of the data.

Materials science and integration bases for fabrication of (BaxSr1-x)TiO3 thin film capacitors with layered Cu-based electrodes

NASA Astrophysics Data System (ADS)

Fan, W.; Kabius, B.; Hiller, J. M.; Saha, S.; Carlisle, J. A.; Auciello, O.; Chang, R. P. H.; Ramesh, R.

2003-11-01

The synthesis and fundamental material properties of layered TiAl/Cu/Ta electrodes were investigated to achieve the integration of Cu electrodes with high-dielectric constant (κ) oxide thin films for application to the fabrication of high-frequency devices. The Ta layer is an excellent diffusion barrier to inhibit deleterious Cu diffusion into the Si substrate, while the TiAl layer provides an excellent barrier against oxygen diffusion into the Cu layer to inhibit Cu oxidation during the growth of the high-κ layer in an oxygen atmosphere. Polycrystalline (BaxSr1-x)TiO3 (BST) thin films were grown on the Cu-based bottom electrode by rf magnetron sputtering at temperatures in the range 400-600 °C in oxygen, to investigate the performance of BST/Cu-based capacitors. Characterization of the Cu-based layered structure using surface analytical methods showed that two amorphous oxide layers were formed on both sides of the TiAl barrier, such that the oxide layer on the free surface of the TiAl layer correlates with TiAlOx, while the oxide layer at the TiAl/Cu interface is an Al2O3-rich layer. This double amorphous barrier layer structure effectively prevents oxygen penetration towards the underlying Cu and Ta layers. The TiAlOx interfacial layer, which has a relatively low dielectric constant compared with BST, reduced the total capacitance of the BST thin film capacitors. In addition, the layered electrode-oxide interface roughening observed during the growth of BST films at high temperature, due to copper grain growth, resulted in large dielectric loss on the fabricated BST capacitors. These problems were solved by growing the BST layer at 450 °C followed by a rapid thermal annealing at 700 °C. This process significantly reduced the thickness of the TiAlOx layer and interface roughness resulting in BST capacitors exhibiting properties suitable for the fabrication of high-performance high-frequency devices. In summary, relatively high dielectric constant (280), low dielectric loss (0.007), and low leakage current (<2×10-8 A/cm2 at 100 kV/cm) were achieved for BST thin film capacitors with Cu-based electrodes.

Electrochemical impedance spectroscopy analysis of a thin polymer film-based micro-direct methanol fuel cell

NASA Astrophysics Data System (ADS)

Schulz, Tobias; Weinmüller, Christian; Nabavi, Majid; Poulikakos, Dimos

A single cell micro-direct methanol fuel cell (micro-DMFC) was investigated using electrochemical impedance spectroscopy. The electrodes consisted of thin, flexible polymer (SU8) film microchannel structures fabricated in-house using microfabrication techniques. AC impedance spectroscopy was used to separate contributions to the overall cell polarization from the anode, cathode and membrane. A clear distinction between the different electrochemical phenomena occurring in the micro-DMFC, especially the distinction between double layer charging and Faradaic reactions was shown. The effect of fuel flow rate, temperature, and anode flow channel structure on the impedance of the electrode reactions and membrane/electrode double layer charging were investigated. Analysis of impedance data revealed that the performance of the test cell was largely limited by the presence of intermediate carbon monoxide in the anode reaction. Higher temperatures increase cell performance by enabling intermediate CO to be oxidized at much higher rates. The results also revealed that serpentine anode flow microchannels show a lower tendency to intermediate CO coverage and a more stable cell behavior than parallel microchannels.

Highly Crystalline C8-BTBT Thin-Film Transistors by Lateral Homo-Epitaxial Growth on Printed Templates.

PubMed

Janneck, Robby; Pilet, Nicolas; Bommanaboyena, Satya Prakash; Watts, Benjamin; Heremans, Paul; Genoe, Jan; Rolin, Cedric

2017-11-01

Highly crystalline thin films of organic semiconductors offer great potential for fundamental material studies as well as for realizing high-performance, low-cost flexible electronics. The fabrication of these films directly on inert substrates is typically done by meniscus-guided coating techniques. The resulting layers show morphological defects that hinder charge transport and induce large device-to-device variability. Here, a double-step method for organic semiconductor layers combining a solution-processed templating layer and a lateral homo-epitaxial growth by a thermal evaporation step is reported. The epitaxial regrowth repairs most of the morphological defects inherent to meniscus-guided coatings. The resulting film is highly crystalline and features a mobility increased by a factor of three and a relative spread in device characteristics improved by almost half an order of magnitude. This method is easily adaptable to other coating techniques and offers a route toward the fabrication of high-performance, large-area electronics based on highly crystalline thin films of organic semiconductors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

I-III-VI.sub.2 based solar cell utilizing the structure CuInGaSe.sub.2 CdZnS/ZnO

DOEpatents

Chen, Wen S.; Stewart, John M.

1992-01-07

A thin film I-III-VI.sub.2 based solar cell having a first layer of copper indium gallium selenide, a second layer of cadmium zinc sulfide, a double layer of zinc oxide, and a metallization structure comprised of a layer of nickel covered by a layer of aluminum. An optional antireflective coating may be placed on said metallization structure. The cadmium zinc sulfide layer is deposited by means of an aqueous solution growth deposition process and may actually consist of two layers: a low zinc content layer and a high zinc content layer. Photovoltaic efficiencies of 12.5% at Air Mass 1.5 illumination conditions and 10.4% under AMO illumination can be achieved.

Copper Benzenetricarboxylate Metal-Organic Framework Nucleation Mechanisms on Metal Oxide Powders and Thin Films formed by Atomic Layer Deposition.

PubMed

Lemaire, Paul C; Zhao, Junjie; Williams, Philip S; Walls, Howard J; Shepherd, Sarah D; Losego, Mark D; Peterson, Gregory W; Parsons, Gregory N

2016-04-13

Chemically functional microporous metal-organic framework (MOF) crystals are attractive for filtration and gas storage applications, and recent results show that they can be immobilized on high surface area substrates, such as fiber mats. However, fundamental knowledge is still lacking regarding initial key reaction steps in thin film MOF nucleation and growth. We find that thin inorganic nucleation layers formed by atomic layer deposition (ALD) can promote solvothermal growth of copper benzenetricarboxylate MOF (Cu-BTC) on various substrate surfaces. The nature of the ALD material affects the MOF nucleation time, crystal size and morphology, and the resulting MOF surface area per unit mass. To understand MOF nucleation mechanisms, we investigate detailed Cu-BTC MOF nucleation behavior on metal oxide powders and Al2O3, ZnO, and TiO2 layers formed by ALD on polypropylene substrates. Studying both combined and sequential MOF reactant exposure conditions, we find that during solvothermal synthesis ALD metal oxides can react with the MOF metal precursor to form double hydroxy salts that can further convert to Cu-BTC MOF. The acidic organic linker can also etch or react with the surface to form MOF from an oxide metal source, which can also function as a nucleation agent for Cu-BTC in the mixed solvothermal solution. We discuss the implications of these results for better controlled thin film MOF nucleation and growth.

Electrical responses of artificial DNA nanostructures on solution-processed In-Ga-Zn-O thin-film transistors with multistacked active layers.

PubMed

Jung, Joohye; Kim, Si Joon; Yoon, Doo Hyun; Kim, Byeonghoon; Park, Sung Ha; Kim, Hyun Jae

2013-01-01

We propose solution-processed In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) with multistacked active layers for detecting artificial deoxyribonucleic acid (DNA). Enhanced sensing ability and stable electrical performance of TFTs were achieved through use of multistacked active layers. Our IGZO TFT had a turn-on voltage (V(on)) of -0.8 V and a subthreshold swing (SS) value of 0.48 V/decade. A dry-wet method was adopted to immobilize double-crossover DNA on the IGZO surface, after which an anomalous hump effect accompanying a significant decrease in V(on) (-13.6 V) and degradation of SS (1.29 V/decade) was observed. This sensing behavior was attributed to the middle interfaces of the multistacked active layers and the negatively charged phosphate groups on the DNA backbone, which generated a parasitic path in the TFT device. These results compared favorably with those reported for conventional field-effect transistor-based DNA sensors with remarkable sensitivity and stability.

Electronic absorption band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment

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

Kim, Jinhyun; Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr

2012-10-15

Variations in the electronic absorption (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the absorption bands as well as a large increase in the surface roughnessmore » and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc absorption.« less

A Basin-Wide Examination of the Arctic Ocean's Double-Diffusive Staircase

NASA Astrophysics Data System (ADS)

Shibley, N.; Timmermans, M. L.; Carpenter, J. R.; Toole, J. M.

2016-02-01

The Arctic Ocean thermohaline stratification frequently exhibits a staircase structure above the Atlantic Water Layer consisting of multiple mixed layers of order 1-m in height separated by sharp interfaces. This double-diffusive staircase structure is characterized across the entire Arctic Ocean through a detailed analysis of Ice-Tethered Profiler measurements acquired between 2004 and 2013. Staircase properties (mixed layer thicknesses and temperature-salinity jumps across interfaces) are examined in relation to a bulk vertical density ratio for 50-m spanning the staircase stratification. It is shown that the Lomonosov Ridge serves as an approximate boundary between regions of low density ratio (on the Eurasian side) and higher density ratio (on the Canadian side). We find that the diffusive staircase in the Eurasian Basin is characterized by fewer, thinner mixed layers than that in the Canadian Basin, although the margins of all basins are characterized by relatively thin staircase mixed layers. Using a double-diffusive 4/3 flux law parameterization, the distribution of vertical heat fluxes through the staircase is estimated across the Arctic; it is found that heat fluxes in the Eurasian Basin [O(1) W/m^2] are generally an order of magnitude larger than those in the Canadian Basin [O(0.1) W/m^2].

In situ fabrication of nickel aluminum-layered double hydroxide nanosheets/hollow carbon nanofibers composite as a novel electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

He, Fang; Hu, Zhibiao; Liu, Kaiyu; Zhang, Shuirong; Liu, Hongtao; Sang, Shangbin

2014-12-01

This paper introduces a new design route to fabricate nickel aluminum-layered double hydroxide (NiAl-LDH) nanosheets/hollow carbon nanofibers (CNFs) composite through an in situ growth method. The NiAl-LDH thin layers which grow on hollow carbon nanofibers have an average thickness of 13.6 nm. The galvanostatic charge-discharge test of the NiAl-LDH/CNFs composite yields an impressive specific capacitance of 1613 F g-1 at 1 A g-1 in 6 M KOH solution, the composite shows a remarkable specific capacitance of 1110 F g-1 even at a high current density of 10 A g-1. Furthermore, the composite remains a specific capacitance of 1406 F g-1 after 1000 cycles at 2 A g-1, indicating the composite has excellent high-current capacitive behavior and good cycle stability in compared to pristine NiAl-LDH.

Self-organized layered hydrogenation in black Mg2NiHx switchable mirrors.

PubMed

Lohstroh, W; Westerwaal, R J; Noheda, B; Enache, S; Giebels, I A M E; Dam, B; Griessen, R

2004-11-05

In addition to a mirrorlike (Mg2Ni) and a transparent (Mg2NiH4) state, thin films of Mg2NiHx exhibit a remarkable black state with low reflection over the entire visible spectrum, essentially zero transmission and a low electrical resistivity. Such a black state is not explicable for a homogeneous layer since a large absorption coefficient always yields substantial reflection. We show that it results from a self-organized and reversible double layering of metallic Mg2NiH0.3 and semiconducting Mg2NiH4.

Enhancing sound absorption and transmission through flexible multi-layer micro-perforated structures.

PubMed

Bravo, Teresa; Maury, Cédric; Pinhède, Cédric

2013-11-01

Theoretical and experimental results are presented into the sound absorption and transmission properties of multi-layer structures made up of thin micro-perforated panels (ML-MPPs). The objective is to improve both the absorption and insulation performances of ML-MPPs through impedance boundary optimization. A fully coupled modal formulation is introduced that predicts the effect of the structural resonances onto the normal incidence absorption coefficient and transmission loss of ML-MPPs. This model is assessed against standing wave tube measurements and simulations based on impedance translation method for two double-layer MPP configurations of relevance in building acoustics and aeronautics. Optimal impedance relationships are proposed that ensure simultaneous maximization of both the absorption and the transmission loss under normal incidence. Exhaustive optimization of the double-layer MPPs is performed to assess the absorption and/or transmission performances with respect to the impedance criterion. It is investigated how the panel volumetric resonances modify the excess dissipation that can be achieved from non-modal optimization of ML-MPPs.

On the Discontinuity of Polycrystalline Silicon Thin Films Realized by Aluminum-Induced Crystallization of PECVD-Deposited Amorphous Si

NASA Astrophysics Data System (ADS)

Pan, Qingtao; Wang, Tao; Yan, Hui; Zhang, Ming; Mai, Yaohua

2017-04-01

Crystallization of glass/Aluminum (50, 100, 200 nm) /hydrogenated amorphous silicon (a-Si:H) (50, 100, 200 nm) samples by Aluminum-induced crystallization (AIC) is investigated in this article. After annealing and wet etching, we found that the continuity of the polycrystalline silicon (poly-Si) thin films was strongly dependent on the double layer thicknesses. Increasing the a-Si:H/Al layer thickness ratio would improve the film microcosmic continuity. However, too thick Si layer might cause convex or peeling off during annealing. Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) are introduced to analyze the process of the peeling off. When the thickness ratio of a-Si:H/Al layer is around 1 to 1.5 and a-Si:H layer is less than 200 nm, the poly-Si film has a good continuity. Hall measurements are introduced to determine the electrical properties. Raman spectroscopy and X-ray diffraction (XRD) results show that the poly-Si film is completely crystallized and has a preferential (111) orientation.

Improved Efficiency of Polymer Solar Cells by means of Coating Hole Transporting Layer as Double Layer Deposition

NASA Astrophysics Data System (ADS)

Chonsut, T.; Kayunkid, N.; Rahong, S.; Rangkasikorn, A.; Wirunchit, S.; Kaewprajak, A.; Kumnorkaew, P.; Nukeaw, J.

2017-09-01

Polymer solar cells is one of the promising technologies that gain tremendous attentions in the field of renewable energy. Optimization of thickness for each layer is an important factor determining the efficiency of the solar cells. In this work, the optimum thickness of Poly(3,4-ethylenedioxythione): poly(styrenesulfonate) (PEDOT:PSS), a famous polymer widely used as hole transporting layer in polymer solar cells, is determined through the analyzing of device’s photovoltaic parameters, e.g. short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF) as well as power conversion efficiency (PCE). The solar cells were prepared with multilayer of ITO/PEDOT:PSS/PCDTBT:PC70BM/TiOx/Al by rapid convective deposition. In such preparation technique, the thickness of the thin film is controlled by the deposition speed. The faster deposition speed is used, the thicker film is obtained. Furthermore, double layer deposition of PEDOT:PSS was introduced as an approach to improve solar cell efficiency. The results obviously reveal that, with the increase of PEDOT:PSS thickness, the increments of Jsc and FF play the important role to improve PCE from 3.21% to 4.03%. Interestingly, using double layer deposition of PEDOT:PSS shows the ability to enhance the performance of the solar cells to 6.12% under simulated AM 1.5G illumination of 100 mW/cm2.

On the Impact of Electrostatic Correlations on the Double-Layer Polarization of a Spherical Particle in an Alternating Current Field.

PubMed

Alidoosti, Elaheh; Zhao, Hui

2018-05-15

At concentrated electrolytes, the ion-ion electrostatic correlation effect is considered an important factor in electrokinetics. In this paper, we compute, in theory and simulation, the dipole moment for a spherical particle (charged, dielectric) under the action of an alternating electric field using the modified continuum Poisson-Nernst-Planck (PNP) model by Bazant et al. [ Double Layer in Ionic Liquids: Overscreening Versus Crowding . Phys. Rev. Lett. 2011 , 106 , 046102 ] We investigate the dependency of the dipole moment in terms of frequency and its variation with such quantities like ζ-potential, electrostatic correlation length, and double-layer thickness. With thin electric double layers, we develop simple models through performing an asymptotic analysis of the modified PNP model. We also present numerical results for an arbitrary Debye screening length and electrostatic correlation length. From the results, we find a complicated impact of electrostatic correlations on the dipole moment. For instance, with increasing the electrostatic correlation length, the dipole moment decreases and reaches a minimum and then it goes up. This is because of initially decreasing of surface conduction and finally increasing due to the impact of ion-ion electrostatic correlations on ion's convection and migration. Also, we show that in contrast to the standard PNP model, the modified PNP model can qualitatively explain the data from the experimental results in multivalent electrolytes.

New results of GridPix TPCs

NASA Astrophysics Data System (ADS)

van der Graaf, Harry

2009-07-01

The Gossip detector, being a GridPix TPC equipped with a thin layer of gas, is a promising alternative for Si tracking detectors. In addition, GridPix would be an interesting way to read out the gaseous phase volume of bi-phase Liquid Xe cryostats of v-less double beta decay and rare event (i.e. WIMP) search experiments.

Head-on collision of drops: A numerical investigation

NASA Technical Reports Server (NTRS)

Nobari, M. R.; Jan, Y.-J.; Tryggvason, G.

1993-01-01

The head-on collision of equal sized drops is studied by full numerical simulations. The Navier-Stokes equations are solved for fluid motion both inside and outside the drops using a front tracking/finite difference technique. The drops are accelerated toward each other by a body force that is turned off before the drops collide. When the drops collide, the fluid between them is pushed outward leaving a thin later bounded by the drop surface. This layer gets progressively thinner as the drops continue to deform and in several of the calculations this double layer is artificially removed once it is thin enough, thus modeling rupture. If no rupture takes place, the drops always rebound, but if the film is ruptured the drops may coalesce permanently or coalesce temporarily and then split again.

Achieving 14.4% Alcohol-Based Solution-Processed Cu(In,Ga)(S,Se)2 Thin Film Solar Cell through Interface Engineering.

PubMed

Park, Gi Soon; Chu, Van Ben; Kim, Byoung Woo; Kim, Dong-Wook; Oh, Hyung-Suk; Hwang, Yun Jeong; Min, Byoung Koun

2018-03-28

An optimization of band alignment at the p-n junction interface is realized on alcohol-based solution-processed Cu(In,Ga)(S,Se) 2 (CIGS) thin film solar cells, achieving a power-conversion-efficiency (PCE) of 14.4%. To obtain a CIGS thin film suitable for interface engineering, we designed a novel "3-step chalcogenization process" for Cu 2- x Se-derived grain growth and a double band gap grading structure. Considering S-rich surface of the CIGS thin film, an alternative ternary (Cd,Zn)S buffer layer is adopted to build favorable "spike" type conduction band alignment instead of "cliff" type. Suppression of interface recombination is elucidated by comparing recombination activation energies using a dark J- V- T analysis.

Low-voltage electric-double-layer paper transistors gated by microporous SiO2 processed at room temperature

NASA Astrophysics Data System (ADS)

Sun, Jia; Wan, Qing; Lu, Aixia; Jiang, Jie

2009-11-01

Battery drivable low-voltage SnO2-based paper thin-film transistors with a near-zero threshold voltage (Vth=0.06 V) gated by microporous SiO2 dielectric with electric-double-layer (EDL) effect are fabricated at room temperature. The operating voltage is found to be as low as 1.5 V due to the huge gate specific capacitance (1.34 μF/cm2 at 40 Hz) related to EDL formation. The subthreshold gate voltage swing and current on/off ratio is found to be 82 mV/decade and 2.0×105, respectively. The electron field-effect mobility is estimated to be 47.3 cm2/V s based on the measured gate specific capacitance at 40 Hz.

Unusual photoelectric behaviors of Mo-doped TiO2 multilayer thin films prepared by RF magnetron co-sputtering: effect of barrier tunneling on internal charge transfer

NASA Astrophysics Data System (ADS)

Yan, B. X.; Luo, S. Y.; Mao, X. G.; Shen, J.; Zhou, Q. F.

2013-01-01

Mo-doped TiO2 multilayer thin films were prepared by RF magnetron co-sputtering. Microstructures, crystallite parameters and the absorption band were investigated with atomic force microscopy, X-ray diffraction and ultraviolet-visible spectroscopy. Internal carrier transport characteristics and the photoelectric property of different layer-assemble modes were examined on an electrochemical workstation under visible light. The result indicates that the double-layer structure with an undoped surface layer demonstrated a red-shifted absorption edge and a much stronger photocurrent compared to the uniformly doped sample, signifying that the electric field implanted at the interface between particles in different layers accelerated internal charge transfer effectively. However, a heavily doped layer implanted at the bottom of the three-layer film merely brought about negative effects on the photoelectric property, mainly because of the Schottky junction existing above the substrate. Nevertheless, this obstacle was successfully eliminated by raising the Mo concentration to 1020 cm-3, where the thickness of the depletion layer fell into the order of angstroms and the tunneling coefficient manifested a dramatic increase. Under this circumstance, the Schottky junction disappeared and the strongest photocurrent was observed in the three-layer film.

The finite layer method for modelling the sound transmission through double walls

NASA Astrophysics Data System (ADS)

Díaz-Cereceda, Cristina; Poblet-Puig, Jordi; Rodríguez-Ferran, Antonio

2012-10-01

The finite layer method (FLM) is presented as a discretisation technique for the computation of noise transmission through double walls. It combines a finite element method (FEM) discretisation in the direction perpendicular to the wall with trigonometric functions in the two in-plane directions. It is used for solving the Helmholtz equation at the cavity inside the double wall, while the wall leaves are modelled with the thin plate equation and solved with modal analysis. Other approaches to this problem are described here (and adapted where needed) in order to compare them with the FLM. They range from impedance models of the double wall behaviour to different numerical methods for solving the Helmholtz equation in the cavity. For the examples simulated in this work (impact noise and airborne sound transmission), the former are less accurate than the latter at low frequencies. The main advantage of FLM over the other discretisation techniques is the possibility of extending it to multilayered structures without changing the interpolation functions and with an affordable computational cost. This potential is illustrated with a calculation of the noise transmission through a multilayered structure: a double wall partially filled with absorbing material.

A grid-doubling finite-element technique for calculating dynamic three-dimensional spontaneous rupture on an earthquake fault

USGS Publications Warehouse

Barall, Michael

2009-01-01

We present a new finite-element technique for calculating dynamic 3-D spontaneous rupture on an earthquake fault, which can reduce the required computational resources by a factor of six or more, without loss of accuracy. The grid-doubling technique employs small cells in a thin layer surrounding the fault. The remainder of the modelling volume is filled with larger cells, typically two or four times as large as the small cells. In the resulting non-conforming mesh, an interpolation method is used to join the thin layer of smaller cells to the volume of larger cells. Grid-doubling is effective because spontaneous rupture calculations typically require higher spatial resolution on and near the fault than elsewhere in the model volume. The technique can be applied to non-planar faults by morphing, or smoothly distorting, the entire mesh to produce the desired 3-D fault geometry. Using our FaultMod finite-element software, we have tested grid-doubling with both slip-weakening and rate-and-state friction laws, by running the SCEC/USGS 3-D dynamic rupture benchmark problems. We have also applied it to a model of the Hayward fault, Northern California, which uses realistic fault geometry and rock properties. FaultMod implements fault slip using common nodes, which represent motion common to both sides of the fault, and differential nodes, which represent motion of one side of the fault relative to the other side. We describe how to modify the traction-at-split-nodes method to work with common and differential nodes, using an implicit time stepping algorithm.

Coated Porous Si for High Performance On-Chip Supercapacitors

NASA Astrophysics Data System (ADS)

Grigoras, K.; Keskinen, J.; Grönberg, L.; Ahopelto, J.; Prunnila, M.

2014-11-01

High performance porous Si based supercapacitor electrodes are demonstrated. High power density and stability is provided by ultra-thin TiN coating of the porous Si matrix. The TiN layer is deposited by atomic layer deposition (ALD), which provides sufficient conformality to reach the bottom of the high aspect ratio pores. Our porous Si supercapacitor devices exhibit almost ideal double layer capacitor characteristic with electrode volumetric capacitance of 7.3 F/cm3. Several orders of magnitude increase in power and energy density is obtained comparing to uncoated porous silicon electrodes. Good stability of devices is confirmed performing several thousands of charge/discharge cycles.

High density circuit technology, part 4

NASA Technical Reports Server (NTRS)

Wade, T. E.

1982-01-01

An accurate study and evaluation of dielectric thin films is conducted in order to find the material or combination of materials which would optimize NASA'S double layer metal process. Emphasis is placed on polyimide dielectrics because of their reported outstanding dielectric characteristics (including electrical, chemical, thermal, and mechanical) and ease of processing, as well as their rapid acceptance by the semiconductor industry.

Enhanced electron mobility at the two-dimensional metallic surface of BaSnO3 electric-double-layer transistor at low temperatures

NASA Astrophysics Data System (ADS)

Fujiwara, Kohei; Nishihara, Kazuki; Shiogai, Junichi; Tsukazaki, Atsushi

2017-05-01

Wide-bandgap oxides exhibiting high electron mobility hold promise for the development of useful electronic and optoelectronic devices as well as for basic research on two-dimensional electron transport phenomena. A perovskite-type tin oxide, BaSnO3, is currently one of such targets owing to distinctly high mobility at room temperature. The challenge to overcome towards the use of BaSnO3 thin films in applications is suppression of dislocation scattering, which is one of the dominant scattering origins for electron transport. Here, we show that the mobility of the BaSnO3 electric-double-layer transistor reaches 300 cm2 V-1 s-1 at 50 K. The improved mobility indicates that charged dislocation scattering is effectively screened by electrostatically doped high-density charge carriers. We also observed metallic conduction persisting down to 2 K, which is attributed to the transition to the degenerate semiconductor. The experimental verification of bulk-level mobility at the densely accumulated surface sheds more light on the importance of suppression of dislocation scattering by interface engineering in doped BaSnO3 thin films for transparent electrode applications.

Impact of Sequential Ammonia Fiber Expansion (AFEX) Pretreatment and Pelletization on the Moisture Sorption Properties of Corn Stover

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

Bonner, Ian J.; Thompson, David N.; Teymouri, Farzaneh

Combining ammonia fiber expansion (AFEX™) pretreatment with a depot processing facility is a promising option for delivering high-value densified biomass to the emerging bioenergy industry. However, because the pretreatment process results in a high moisture material unsuitable for pelleting or storage (40% wet basis), the biomass must be immediately dried. If AFEX pretreatment results in a material that is difficult to dry, the economics of this already costly operation would be at risk. This work tests the nature of moisture sorption isotherms and thin-layer drying behavior of corn (Zea mays L.) stover at 20°C to 60°C before and after sequentialmore » AFEX pretreatment and pelletization to determine whether any negative impacts to material drying or storage may result from the AFEX process. The equilibrium moisture content to equilibrium relative humidity relationship for each of the materials was determined using dynamic vapor sorption isotherms and modeled with modified Chung-Pfost, modified Halsey, and modified Henderson temperature-dependent models as well as the Double Log Polynomial (DLP), Peleg, and Guggenheim Anderson de Boer (GAB) temperature-independent models. Drying kinetics were quantified under thin-layer laboratory testing and modeled using the Modified Page's equation. Water activity isotherms for non-pelleted biomass were best modeled with the Peleg temperature-independent equation while isotherms for the pelleted biomass were best modeled with the Double Log Polynomial equation. Thin-layer drying results were accurately modeled with the Modified Page's equation. The results of this work indicate that AFEX pretreatment results in drying properties more favorable than or equal to that of raw corn stover, and pellets of superior physical stability in storage.« less

Spatial variability of the Arctic Ocean's double-diffusive staircase

NASA Astrophysics Data System (ADS)

Shibley, N. C.; Timmermans, M.-L.; Carpenter, J. R.; Toole, J. M.

2017-02-01

The Arctic Ocean thermohaline stratification frequently exhibits a staircase structure overlying the Atlantic Water Layer that can be attributed to the diffusive form of double-diffusive convection. The staircase consists of multiple layers of O(1) m in thickness separated by sharp interfaces, across which temperature and salinity change abruptly. Through a detailed analysis of Ice-Tethered Profiler measurements from 2004 to 2013, the double-diffusive staircase structure is characterized across the entire Arctic Ocean. We demonstrate how the large-scale Arctic Ocean circulation influences the small-scale staircase properties. These staircase properties (layer thicknesses and temperature and salinity jumps across interfaces) are examined in relation to a bulk vertical density ratio spanning the staircase stratification. We show that the Lomonosov Ridge serves as an approximate boundary between regions of low density ratio (approximately 3-4) on the Eurasian side and higher density ratio (approximately 6-7) on the Canadian side. We find that the Eurasian Basin staircase is characterized by fewer, thinner layers than that in the Canadian Basin, although the margins of all basins are characterized by relatively thin layers and the absence of a well-defined staircase. A double-diffusive 4/3 flux law parametrization is used to estimate vertical heat fluxes in the Canadian Basin to be O(0.1) W m-2. It is shown that the 4/3 flux law may not be an appropriate representation of heat fluxes through the Eurasian Basin staircase. Here molecular heat fluxes are estimated to be between O(0.01) and O(0.1) W m-2. However, many uncertainties remain about the exact nature of these fluxes.

Interfacial thin films rupture and self-similarity

NASA Astrophysics Data System (ADS)

Ward, Margaret H.

2011-06-01

Two superposed thin layers of fluids are prone to interfacial instabilities due to London-van der Waals forces. Evolution equations for the film thicknesses are derived using lubrication theory. Using the intrinsic scales, for a single layer, results in a system with parametric dependence of four ratios of the two layers: surface tension, Hamaker constant, viscosity, and film thickness. In contrast to the single layer case, the bilayer system has two unstable eigenmodes: squeezing and bending. For some particular parameter regimes, the system exhibits the avoided crossing behavior, where the two eigenmodes are interchanged. Based on numerical analysis, the system evolves into four different rupture states: basal layer rupture, upper layer rupture, double layer rupture, and mixed layer rupture. The ratio of Hamaker constants and the relative film thickness of the two layers control the system dynamics. Remarkably, the line of avoided crossing demarks the transition region of mode mixing and energy transfer, affecting the scaling of the dynamical regime map consequentially. Asymptotic and numerical analyses are used to examine the self-similar ruptures and to extract the power law scalings for both the basal layer rupture and the upper layer rupture. The scaling laws for the basal layer rupture are the same as those of the single layer on top of a substrate. The scaling laws for the upper layer rupture are different: the lateral length scale decreases according to (tr-t)1/3 and the film thickness decreases according to (tr-t)1/6.

Transport Properties of Anatase-TiO2 Polycrystalline-Thin-Film Field-Effect Transistors with Electrolyte Gate Layers

NASA Astrophysics Data System (ADS)

Horita, Ryohei; Ohtani, Kyosuke; Kai, Takahiro; Murao, Yusuke; Nishida, Hiroya; Toya, Taku; Seo, Kentaro; Sakai, Mio; Okuda, Tetsuji

2013-11-01

We have fabricated anatase-TiO2 polycrystalline-thin-film field-effect transistors (FETs) with poly(vinyl alcohol) (PVA), ion-liquid (IL), and ion-gel (IG) gate layers, and have tried to improve the response to gate voltage by varying the concentration of mobile ions in these electrolyte gate layers. The increase in the concentration of mobile ions by doping NaOH into the PVA gate layer or reducing the gelator in the IG gate layer markedly increases the drain-source current and reduces the driving gate voltage, which show that the mobile ions in the PVA, IL, and IG gate layers cause the formation of electric double layers (EDLs), which act as nanogap capacitors. In these TiO2-EDL-FETs, the slow formation of EDLs and the oxidation reaction at the interface between the surface of the TiO2 film and the electrolytes cause unideal FET properties. In the optimized IL and IG TiO2-EDL-FETs, the driving gate voltage is less than 1 V and the ON/OFF ratios of the transfer characteristics are about 1×104 at RT, and the nearly metallic state is realized at the interface purely by applying a gate voltage.

Spectroscopic Studies of Double Beta Decays and MOON

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

Ejiri, H.; Nuclear Science, Czech Technical University, Brehova, Prague, Czech Republic, National Institute of Radiological Sciences, Chiba, 263-8555

2007-10-12

This is a brief review of future spectroscopic experiments of neutrino-less double beta decays (0{nu}{beta}{beta}) and the MOON (Mo Observatory Of Neutrinos) project. Spectroscopic 0{nu}{beta}{beta} experiments of MOON, SuperNEMO and DCBA are planned to study Majorana masses in the quasi-degenerate (QD) and inverted mass hierarchy (IH) regions. MOON aims at 0{nu}{beta}{beta} studies with the {nu}-mass sensitivities of 100-30 meV by means of a super ensemble of multi-layer modules, each being consist of a scintillator plate, two tracking detector planes and a thin {beta}{beta} source film.

Amorphous indium-gallium-zinc-oxide thin-film transistors using organic-inorganic hybrid films deposited by low-temperature plasma-enhanced chemical vapor deposition for all dielectric layers

NASA Astrophysics Data System (ADS)

Hsu, Chao-Jui; Chang, Ching-Hsiang; Chang, Kuei-Ming; Wu, Chung-Chih

2017-01-01

We investigated the deposition of high-performance organic-inorganic hybrid dielectric films by low-temperature (close to room temperature) inductively coupled plasma chemical vapor deposition (ICP-CVD) with hexamethyldisiloxane (HMDSO)/O2 precursor gas. The hybrid films exhibited low leakage currents and high breakdown fields, suitable for thin-film transistor (TFT) applications. They were successfully integrated into the gate insulator, the etch-stop layer, and the passivation layer for bottom-gate staggered amorphous In-Ga-Zn-O (a-IGZO) TFTs having the etch-stop configuration. With the double-active-layer configuration having a buffer a-IGZO back-channel layer grown in oxygen-rich atmosphere for better immunity against plasma damage, the etch-stop-type bottom-gate staggered a-IGZO TFTs with good TFT characteristics were successfully demonstrated. The TFTs showed good field-effect mobility (μFE), threshold voltage (V th), subthreshold swing (SS), and on/off ratio (I on/off) of 7.5 cm2 V-1 s-1, 2.38 V, 0.38 V/decade, and 2.2 × 108, respectively, manifesting their usefulness for a-IGZO TFTs.

Effect of target composition on proton acceleration in ultraintense laser-thin foil interaction

NASA Astrophysics Data System (ADS)

Liu, Qingcao; Liu, Meng; Yu, Tongpu; Ding, Pengji; Liu, Zuoye; Sun, Shaohua; Liu, Xiaoliang; Lu, Xing; Guo, Zeqin; Hu, Bitao

2012-09-01

The interactions of ultraintense circularly polarized laser pulses with a mixed solid target and a double-layer target are studied by two-dimensional particle-in-cell simulations. Different carbon and proton compositions in the targets are used in the simulations. It is shown that the proton acceleration mechanisms in both targets are very sensitive to the ion density ratios between protons and carbon ions. For a mixed solid target, a relatively low proton density gives rise to monoenergetic peaks in the proton energy spectrum while a high proton density leads to a large cut-off energy and wide energy spread. With the increase of the ratio, the so-called directed-Coulomb-explosion becomes dominated over the radiation pressure. Surprisingly, for a double-layer target with a front proton layer and an ultrathin rear carbon layer, a highly monoenergetic proton beam with a peak energy of 1.7 GeV/u, an energy spread of ˜4%, and a divergency angle of 2° can be obtained, which might have diverse applications in medical therepy and proton imaging in future.

Sound transmission through double cylindrical shells lined with porous material under turbulent boundary layer excitation

NASA Astrophysics Data System (ADS)

Zhou, Jie; Bhaskar, Atul; Zhang, Xin

2015-11-01

This paper investigates sound transmission through double-walled cylindrical shell lined with poroelastic material in the core, excited by pressure fluctuations due to the exterior turbulent boundary layer (TBL). Biot's model is used to describe the sound wave propagating in the porous material. Three types of constructions, bonded-bonded, bonded-unbonded and unbonded-unbonded, are considered in this study. The power spectral density (PSD) of the inner shell kinetic energy is predicted for two turbulent boundary layer models, different air gap depths and three types of polyimide foams, respectively. The peaks of the inner shell kinetic energy due to shell resonance, hydrodynamic coincidence and acoustic coincidence are discussed. The results show that if the frequency band over the ring frequency is of interest, an air gap, even if very thin, should exist between the two elastic shells for better sound insulation. And if small density foam has a high flow resistance, a superior sound insulation can still be maintained.

Pulsed—Laser Deposition Of Oxide Thin Films And Laser—Induced Breakdown Spectroscopy Of Multi—Element Materials

NASA Astrophysics Data System (ADS)

Pedarnig, Johannes D.

2010-10-01

New results of the Linz group on pulsed—laser deposition (PLD) of oxide thin films and on laser—induced breakdown spectroscopy (LIBS) of multi-element materials are reported. High-Tc superconducting (HTS) films with enhanced critical current density Jc are produced by laser ablation of novel nano-composite ceramic targets. The targets contain insulating nano-particles that are embedded into the YBa2Cu3O7 matrix. Epitaxial double-layers of lithium-doped and aluminum-doped ZnO are deposited on r-cut sapphire substrates. Acoustic over-modes in the GHz range are excited by piezoelectric actuation of layers. Smooth films of rare-earth doped glass are produced by F2—laser ablation. The transport properties of HTS thin films are modified by light—ion irradiation. Thin film nano—patterning is achieved by masked ion beam irradiation. LIBS is employed to analyze trace elements in industrial iron oxide powder and reference polymer materials. Various trace elements of ppm concentration are measured in the UV/VIS and vacuum-UV spectral range. Quantitative LIBS analysis of major components in oxide materials is performed by calibration-free methods.

Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

NASA Astrophysics Data System (ADS)

Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

2015-11-01

Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5-2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0-2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed.

Low-temperature sol-gel oxide TFT with a fluoropolymer dielectric to enhance the effective mobility at low operation voltage

NASA Astrophysics Data System (ADS)

Yu, Shang-Yu; Wang, Kuan-Hsun; Zan, Hsiao-Wen; Soppera, Olivier

2017-06-01

In this article, we propose a solution-processed high-performance amorphous indium-zinc oxide (a-IZO) thin-film transistor (TFT) gated with a fluoropolymer dielectric. Compared with a conventional IZO TFT with a silicon nitride dielectric, a fluoropolymer dielectric effectively reduces the operation voltage to less than 3 V and greatly increases the effective mobility 40-fold. We suggest that the dipole layer formed at the dielectric surface facilitates electron accumulation and induces the electric double-layer effect. The dipole-induced hysteresis effect is also investigated.

Effect of band-aligned double absorber layers on photovoltaic characteristics of chemical bath deposited PbS/CdS thin film solar cells.

PubMed

Ho Yeon, Deuk; Chandra Mohanty, Bhaskar; Lee, Seung Min; Soo Cho, Yong

2015-09-23

Here we report the highest energy conversion efficiency and good stability of PbS thin film-based depleted heterojunction solar cells, not involving PbS quantum dots. The PbS thin films were grown by the low cost chemical bath deposition (CBD) process at relatively low temperatures. Compared to the quantum dot solar cells which require critical and multistep complex procedures for surface passivation, the present approach, leveraging the facile modulation of the optoelectronic properties of the PbS films by the CBD process, offers a simpler route for optimization of PbS-based solar cells. Through an architectural modification, wherein two band-aligned junctions are stacked without any intervening layers, an enhancement of conversion efficiency by as much as 30% from 3.10 to 4.03% facilitated by absorption of a wider range of solar spectrum has been obtained. As an added advantage of the low band gap PbS stacked over a wide gap PbS, the devices show stability over a period of 10 days.

Role of indium tin oxide electrode on the microstructure of self-assembled WO3-BiVO4 hetero nanostructures

NASA Astrophysics Data System (ADS)

Song, Haili; Li, Chao; Van, Chien Nguyen; Dong, Wenxia; Qi, Ruijuan; Zhang, Yuanyuan; Huang, Rong; Chu, Ying-Hao; Duan, Chun-Gang

2017-11-01

Self-assembled WO3-BiVO4 nanostructured thin films were grown on a (001) yttrium stabilized zirconia (YSZ) substrate by the pulsed laser deposition method with and without the indium tin oxide (ITO) bottom electrode. Their microstructures including surface morphologies, crystalline phases, epitaxial relationships, interface structures, and composition distributions were investigated by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray energy dispersive spectroscopy. In both samples, WO3 formed nanopillars embedded into the monoclinic BiVO4 matrix with specific orientation relationships. In the sample with the ITO bottom electrode, an atomically sharp BiVO4/ITO interface was formed and the orthorhombic WO3 nanopillars were grown on a relaxed BiVO4 buffer layer with a mixed orthorhombic and hexagonal WO3 transition layer. In contrast, a thin amorphous layer appears at the interfaces between the thin film and the YSZ substrate in the sample without the ITO electrode. In addition, orthorhombic Bi2WO6 lamellar nanopillars were formed between WO3 and BiVO4 due to interdiffusion. Such a WO3-Bi2WO6-BiVO4 double heterojunction photoanode may promote the photo-generated charge separation and further improve the photoelectrochemical water splitting properties.

Preliminary Analysis of Lipids and Fatty Acids of Green Bacteria and Chloroflexus aurantiacus

PubMed Central

Kenyon, Christine N.; Gray, Alane M.

1974-01-01

The complex lipids and fatty acids of the seven type species of green bacteria and three strains of Chloroflexus aurantiacus were analyzed. The green bacteria contained lipids that behaved as cardiolipin and phosphatidylglycerol on thin-layer chromatography. They did not contain phosphatidylethanolamine or phosphatidylserine. Similarly, Chloroflexus contained lipids that behaved as phosphatidylglycerol and phosphatidylinositol on thin-layer chromatography and did not contain phosphatidylethanolamine or phosphatidylserine. The green bacteria contained glycolipids I and II of Constantopoulos and Bloch (monogalactosyldiglyceride and a galactose- and rhamnose-containing diglyceride). Chloroflexus exhibited galactose-containing glycolipids that behaved identically with the mono- and digalactosyldiglycerides of spinach on thin-layer chromatography, and each contained galactose as well as at least one other sugar. The fatty acids of both groups of bacteria consisted entirely of saturated and monounsaturated fatty acids. In the green bacteria, myristic, palmitic, and hexadecenoic acids predominated. In Chloroflexus, palmitic, stearic, and oleic acids predominated. The positions of the double bonds in the monounsaturated fatty acids of Chloroflexus indicated synthesis by the anaerobic pathway. The lipid analyses suggest a close relationship between the green bacteria and Chloroflexus and further suggest that these groups of photosynthetic bacteria are more closely related to the blue-green algae than are the purple bacteria. Images PMID:4421249

A numerical method for electro-kinetic flow with deformable fluid interfaces

NASA Astrophysics Data System (ADS)

Booty, Michael; Ma, Manman; Siegel, Michael

2013-11-01

We consider two-phase flow of ionic fluids whose motion is driven by an imposed electric field. At a fluid interface, a screening cloud of ions develops and forms an electro-chemical double layer or Debye layer. The imposed field acts on this induced charge distribution, resulting in a strong slip flow near the interface. We formulate a ``hybrid'' or multiscale numerical method in the thin Debye layer limit that incorporates an asymptotic analysis of the electrostatic potential and fluid dynamics in the Debye layer into a boundary integral solution of the full moving boundary problem. Results of the method are presented that show time-dependent deformation and steady state drop interface shapes when the timescale for charge-up of the Debye layer is either much less than or comparable to the timescale of the flow.

Applications for alliform carbon

DOEpatents

Gogotsi, Yury; Mochalin, Vadym; McDonough, IV, John Kenneth; Simon, Patrice; Taberna, Pierre Louis

2017-02-21

This invention relates to novel applications for alliform carbon, useful in conductors and energy storage devices, including electrical double layer capacitor devices and articles incorporating such conductors and devices. Said alliform carbon particles are in the range of 2 to about 20 percent by weight, relative to the weight of the entire electrode. Said novel applications include supercapacitors and associated electrode devices, batteries, bandages and wound healing, and thin-film devices, including display devices.

Simulations of induced-charge electro-osmosis in microfluidic devices

NASA Astrophysics Data System (ADS)

Ben, Yuxing

2005-03-01

Theories of nonlinear electrokinetic phenomena generally assume a uniform, neutral bulk electroylte in contact with a polarizable thin double layer near a metal or dielectric surface, which acts as a "capacitor skin". Induced-charge electro-osmosis (ICEO) is the general effect of nonlinear electro-osmotic slip, when an applied electric field acts on its own induced (diffuse) double-layer charge. In most theoretical and experimental work, ICEO has been studied in very simple geometries, such as colloidal spheres and planar, periodic micro-electrode arrays. Here we use finite-element simulations to predict how more complicated geometries of polarizable surfaces and/or electrodes yield flow profiles with subtle dependence on the amplitude and frequency of the applied voltage. We also consider how the simple model equations break down, due to surface conduction, bulk diffusion, and concentration polarization, for large applied voltages (as in most experiments).

Pulse electrodeposition of CoFe thin films covered with layered double hydroxides as a fast route to prepare enhanced catalysts for oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Sakita, Alan M. P.; Noce, Rodrigo Della; Vallés, Elisa; Benedetti, Assis V.

2018-03-01

A novel, ultra-fast, and one-step method for obtaining an effective catalyst for oxygen evolution reaction is proposed. The procedure consists in direct electrodeposition, in a free-nitrate bath, of CoFe alloy films covered with layered double hydroxides (LDH), by potentiostatic mode, in continuous or pulsed regime. The catalyst is directly formed on glassy carbon substrates. The best-prepared catalyst material reveals a mixed morphology with granular and dendritic CoFe alloy covered with a sponge of CoFe-LDH containing a Cl interlayer. An overpotential of η10 mA = 286 mV, with a Tafel slope of 48 mV dec-1, is obtained for the OER which displays the enhanced properties of the catalyst. These improved results demonstrate the competitiveness and efficacy of our proposal for the production of OER catalysts.

Fabrication of nanocomposites by collagen templated synthesis of layered double hydroxides assisted by an acrylic silane coupling agent

NASA Astrophysics Data System (ADS)

Sun, Yanqing; Zhou, Yuming; Wang, Zhiqiang; Ye, Xiaoyun

2009-02-01

The purpose of this study was to control the fabrication of nanocomposites at the nanoscale interface by collagen templated synthesis of Zn-Al layered double hydroxides (LDHs) assisted by γ-methacryloxypropyl trimethoxy silane (KH570) with further treatment of graft polymerization. The results show that collagen directs the growth of LDHs into curved nanorods by length of 300 nm in perfect consistency with collagen chain in both the size and flexility under the essential hydrophobic environment on the solid surface provided by KH570. The nanorods are aggregated into thin curved platelets due to strong interaction between collagen molecules themselves and strong interaction between collagen and LDH sheets. By further treatment of graft polymerization, the adjacent curved platelets encircle into numerous hollows via chemical linkage, achieving polyporous nanocomposites. Nanohybrid materials with this structure are especially interesting for applications as biosensors or supported catalysis.

Holey nickel-cobalt layered double hydroxide thin sheets with ultrahigh areal capacitance

NASA Astrophysics Data System (ADS)

Zhi, Lei; Zhang, Wenliang; Dang, Liqin; Sun, Jie; Shi, Feng; Xu, Hua; Liu, Zonghuai; Lei, Zhibin

2018-05-01

Strong coupling of electroactive components on conductive carbonaceous matrix to fabricate flexible hybrid electrodes represents a promising approach towards high performance supercapacitors. This work reports the fabrication of holey nickel cobalt layered double hydroxide (NiCo-LDH) nanosheets that are vertically grown on the cotton cloth-derived activated textile carbon (aTC). The abundant nanoholes on the thin-sheet NiCo-LDH not only enhance the electrode efficiency for efficient Faradaic redox reactions but also facilitate access of electrolyte to the electrode surface, thus giving rise to 70% capacitance arising from their outer surface. As a result, the aTC-NiCo hybrid electrode is capable of simultaneously achieving extremely high areal capacitance (6.37 F cm-2), mass capacitance (525 F g-1) and volumetric capacitance (249 F cm-3) at a practical level of mass loading (6.72 mg cm-2). Moreover, a solid-state asymmetric capacitor built with aTC-NiCo as positive electrode and active carbon-coated on aTC as negative electrode can deliver a volumetric energy density of 7.4 mWh cm-3 at a power density of 103 mW cm-3, while preserving a superior power performance, satisfying cycling stability and good mechanical flexibility.

Diffuse-charge dynamics of ionic liquids in electrochemical systems.

PubMed

Zhao, Hui

2011-11-01

We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant et al., Phys. Rev. Lett. 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our simple scaling analysis suggests that the length scale √(λ*(D)l*(c)) accurately characterizes the double-layer structure of ionic liquids with strong electrostatic correlations where l*(c) is the electrostatic correlation length (in contrast, the Debye screening length λ*(D) is the primary double-layer length for electrolytes) and the response time of λ(D)(*3/2)L*/(D*l(c)(1/2)) (not λ*(D)L*/D* that is the primary charging time of electrolytes) is the correct charging time scale of ionic liquids with strong electrostatic correlations where D* is the diffusivity and L* is the separation length of the cell. With these two new scales, data of both electric potential versus distance from the electrode and the total diffuse charge versus time collapse onto each individual master curve in the presence of strong electrostatic correlations. In addition, the dependance of the total diffuse charge on steric effects, short-range correlations, and driving voltages is thoroughly examined. The results from the asymptotic analysis are compared favorably with those from full numerical simulations. Finally, the absorption of excess salt by the double layer creates a depletion region outside the double layer. Such salt depletion may bring a correction to the leading order terms and break down the weakly nonlinear analysis. A criterion which justifies the weakly nonlinear analysis is verified with numerical simulations.

Quality improvements of ZnxCdyMg1-x-ySe layers grown on InP substrates by a thin ZnCdSe interfacial layer

NASA Astrophysics Data System (ADS)

Zeng, L.; Yang, B. X.; Tamargo, M. C.; Snoeks, E.; Zhao, L.

1998-03-01

The quality of lattice-matched ZnxCdyMg1-x-ySe epitaxial layers grown on (001) InP substrates with a III-V buffer layer has been improved by initially growing a ZnCdSe interfacial layer (50 Å) at low temperature. The widths of double crystal x-ray rocking curves for ZnxCdyMg1-x-ySe epilayers with band gaps as high as 3.05 eV were reduced to about 70 arcsec. The defect density evaluated from etch pit density and plan-view transmission electron microscopy measurements was reduced by two orders of magnitude, to 106-107cm-2. The photoluminescence band edge emission became more symmetric and slightly narrower. It is proposed that an initial two-dimensional growth mode has been achieved by incorporating such a lattice-matched ZnCdSe layer.

Sound transmission through double panel constructions lined with elastic porous materials

NASA Astrophysics Data System (ADS)

Bolton, J. S.; Green, E. R.

1986-07-01

Attention is given to a theory governing one-dimensional wave motion in elastic porous materials which is capable of reproducing experimental transmission measurements for unfaced polyurethane foam layers. Calculations of the transmission loss of fuselage-like foam-lined double panels are presented and it is shown that the foam/panel boundary conditions have a large effect on the panel performance; a hybrid arrangement whereby the foam is bonded directly to one panel and separated from the other by a thin air gap appears to be the most advantageous under practical circumstances. With this configuratiom, the mass-air-mass resonance is minimized and increased low-frequency performance is offered.

Ballistic Phonon Penetration Depth in Amorphous Silicon Dioxide.

PubMed

Yang, Lin; Zhang, Qian; Cui, Zhiguang; Gerboth, Matthew; Zhao, Yang; Xu, Terry T; Walker, D Greg; Li, Deyu

2017-12-13

Thermal transport in amorphous silicon dioxide (a-SiO 2 ) is traditionally treated as random walks of vibrations owing to its greatly disordered structure, which results in a mean free path (MFP) approximately the same as the interatomic distance. However, this picture has been debated constantly and in view of the ubiquitous existence of thin a-SiO 2 layers in nanoelectronic devices, it is imperative to better understand this issue for precise thermal management of electronic devices. Different from the commonly used cross-plane measurement approaches, here we report on a study that explores the in-plane thermal conductivity of double silicon nanoribbons with a layer of a-SiO 2 sandwiched in-between. Through comparing the thermal conductivity of the double ribbon samples with that of corresponding single ribbons, we show that thermal phonons can ballistically penetrate through a-SiO 2 of up to 5 nm thick even at room temperature. Comprehensive examination of double ribbon samples with various oxide layer thicknesses and van der Waals bonding strengths allows for extraction of the average ballistic phonon penetration depth in a-SiO 2 . With solid experimental data demonstrating ballistic phonon transport through a-SiO 2 , this work should provide important insight into thermal management of electronic devices.

Magnetoelectric effect in concentric quantum rings induced by shallow donor

NASA Astrophysics Data System (ADS)

Escorcia, R.; García, L. F.; Mikhailov, I. D.

2018-05-01

We study the alteration of the magnetic and electric properties induced by the off-axis donor in a double InAs/GaAs concentric quantum ring. To this end we consider a model of an axially symmetrical ring-like nanostructure with double rim, in which the thickness of the InAs thin layer is varied smoothly in the radial direction. The energies and of contour plots of the density of charge for low-lying levels we find by using the adiabatic approximation and the double Fourier-Bessel series expansion method and the Kane model. Our results reveal a possibility of the formation of a giant dipole momentum induced by the in-plane electric field, which in addition can be altered by of the external magnetic field applied along the symmetry axis.

Efficient semitransparent perovskite solar cells for 23.0%-efficiency perovskite/silicon four-terminal tandem cells

DOE PAGES

Chen, Bo; Bai, Yang; Yu, Zhengshan; ...

2016-07-19

Here, we have investigated semi-transparent perovskite solar cells and infrared enhanced silicon heterojunction cells for high-efficiency tandem devices. A semi-transparent metal electrode with good electrical conductivity and optical transparency has been fabricated by thermal evaporation of 7 nm of Au onto a 1-nm-thick Cu seed layer. For this electrode to reach its full potential, MAPbI3 thin films were formed by a modified one-step spin-coating method, resulting in a smooth layer that allowed the subsequent metal thin film to remain continuous. The fabricated semi-transparent perovskite solar cells demonstrated 16.5% efficiency under one-sun illumination, and were coupled with infrared-enhanced silicon heterojunction cellsmore » tuned specifically for perovskite/Si tandem devices. A double-layer antireflection coating at the front side and MgF2 reflector at rear side of the silicon heterojunction cells reduced parasitic absorption of near-infrared light, leading to 6.5% efficiency after filtering with a perovskite device and 23.0% summed efficiency for the perovskite/Si tandem device.« less

Assembly of luminescent ordered multilayer thin-films based on oppositely-charged MMT and magnetic NiFe-LDHs nanosheets with ultra-long lifetimes

PubMed Central

Liu, Meitang; Wang, Tianlei; Ma, Hongwen; Fu, Yu; Hu, Kunran; Guan, Chao

2014-01-01

In this present report, luminescent ordered multilayer thin films (OMFs) based on oppositely-charged inorganic nanosheets and the different oppositely-charged chromophores were fabricated via layer-by-layer assembly method. Exfoliated layered double hydroxides (LDHs) and montmorillonite (MMT) nanosheets with opposite charges can be expected to provide a pseudo electronic microenvironment (PEM) which has not been declared in previous literatures, and transition metal-bearing LDHs nanosheets can offer an additional ferromagnetic effect (FME) for the chromophores at the same time. Surprisingly, the luminescent lifetimes of those OMFs with PEM and FME are significantly prolonged compared with that of the pristine chromophores, even much longer than those of OMFs without oppositely-charged and ferromagnetic architecture. Therefore, it is highly expected that the PEM and FME formed by oppositely-charged and transition metal-bearing inorganic nanosheets have remarkable influence on obtaining better optical property, which suggests a new potential way to manipulate, control and develop the novel light-emitting materials and optical devices. PMID:25413710

Efficient semitransparent perovskite solar cells for 23.0%-efficiency perovskite/silicon four-terminal tandem cells

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

Chen, Bo; Bai, Yang; Yu, Zhengshan

Here, we have investigated semi-transparent perovskite solar cells and infrared enhanced silicon heterojunction cells for high-efficiency tandem devices. A semi-transparent metal electrode with good electrical conductivity and optical transparency has been fabricated by thermal evaporation of 7 nm of Au onto a 1-nm-thick Cu seed layer. For this electrode to reach its full potential, MAPbI3 thin films were formed by a modified one-step spin-coating method, resulting in a smooth layer that allowed the subsequent metal thin film to remain continuous. The fabricated semi-transparent perovskite solar cells demonstrated 16.5% efficiency under one-sun illumination, and were coupled with infrared-enhanced silicon heterojunction cellsmore » tuned specifically for perovskite/Si tandem devices. A double-layer antireflection coating at the front side and MgF2 reflector at rear side of the silicon heterojunction cells reduced parasitic absorption of near-infrared light, leading to 6.5% efficiency after filtering with a perovskite device and 23.0% summed efficiency for the perovskite/Si tandem device.« less

Epitaxial growth of (001)-oriented Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films on a-plane sapphire with an MgO/ZnO bridge layer

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

Xiao Bo; Liu Hongrui; Avrutin, Vitaliy

2009-11-23

High quality (001)-oriented Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) thin films have been grown on a-plane sapphire (1120) by rf magnetron sputtering using a double bridge layer consisting of (0001)-oriented ZnO (50 nm) and (001)-oriented MgO (10 nm) prepared by plasma-assisted molecular beam epitaxy. X-ray diffraction revealed the formation of three sets of in-plane BST domains, offset from one another by 30 deg., which is consistent with the in-plane symmetry of the MgO layer observed by in situ reflective high electron energy diffraction. The in-plane epitaxial relationship of BST, MgO, and ZnO has been determined to be BST [110]//MgO [110]//ZnO [1120]more » and BST [110]/MgO [110]//ZnO [1100]. Capacitance-voltage measurements performed on BST coplanar interdigitated capacitor structures revealed a high dielectric tunability of up to 84% at 1 MHz.« less

Effective electromagnetic properties of microheterogeneous materials with surface phenomena

NASA Astrophysics Data System (ADS)

Levin, Valery; Markov, Mikhail; Mousatov, Aleksandr; Kazatchenko, Elena; Pervago, Evgeny

2017-10-01

In this paper, we present an approach to calculate the complex dielectric permittivity of a micro-heterogeneous medium composed of non-conductive solid inclusions embedded into the conductive liquid continuous host. To take into account the surface effects, we approximate the inclusion by a layered ellipsoid consisting of a dielectric core and an infinitesimally thin outer shell corresponding to an electrical double layer (EDL). To predict the effective complex dielectric permittivity of materials with a high concentration of inclusions, we have modified the Effective Field Method (EFM) for the layered ellipsoidal particles with complex electrical properties. We present the results of complex permittivity calculations for the composites with randomly and parallel oriented ellipsoidal inclusions. To analyze the influence of surface polarization, we have accomplished modeling in a wide frequency range for different existing physic-chemical models of double electrical layer. The results obtained show that the tensor of effective complex permittivity of a micro-heterogeneous medium with surface effects has complicate dependences on the component electrical properties, spatial material texture, and the inclusion shape (ellipsoid aspect ratio) and size. The dispersion of dielectric permittivity corresponds to the frequency dependence for individual inclusion of given size, and does not depend on the inclusion concentration.

Nickel-Aluminum Layered Double Hydroxide Coating on the Surface of Conductive Substrates by Liquid Phase Deposition.

PubMed

Maki, Hideshi; Takigawa, Masashi; Mizuhata, Minoru

2015-08-12

The direct synthesis of the adhered Ni-Al LDH thin film onto the surface of electrically conductive substrates by the liquid phase deposition (LPD) reaction is carried out for the development of the positive electrode. The complexation and solution equilibria of the dissolved species in the LPD reaction have been clarified by a theoretical approach, and the LPD reaction conditions for the Ni-Al LDH depositions are shown to be optimized by controlling the fluoride ion concentration and the pH of the LPD reaction solutions. The yields of metal oxides and hydroxides by the LPD method are very sensitive to the supersaturation state of the hydroxide in the reaction solution. The surfaces of conductive substrates are completely covered by the minute mesh-like Ni-Al LDH thin film; furthermore, there is no gap between the surfaces of conductive substrates and the deposited Ni-Al LDH thin film. The active material layer thickness was able to be controlled within the range from 100 nm to 1 μm by the LPD reaction time. The high-crystallinity and the arbitrary-thickness thin films on the conductive substrate surface will be beneficial for the interface control of charge transfer reaction fields and the internal resistance reduction of various secondary batteries.

Near-infrared bulk optical properties of goat wound tissue and human serum: consequences for an implantable optical glucose sensor.

PubMed

Aernouts, Ben; Sharma, Sandeep; Gellynck, Karolien; Vlaminck, Lieven; Cornelissen, Maria; Saeys, Wouter

2016-10-01

Near-infrared (NIR) spectroscopy offers a promising technological platform for continuous glucose monitoring in the human body. Moreover, these measurements could be performed in vivo with an implantable single-chip based optical sensor. However, a thin tissue layer may grow in the optical path of the sensor. As most biological tissues are highly scattering, they only allow a small fraction of the collimated light to pass, significantly reducing the light throughput. To quantify the effect of a thin tissue layer in the optical path, the bulk optical properties of serum and tissue samples grown on implanted dummy sensors were characterized using double integrating sphere and unscattered transmittance measurements. The estimated bulk optical properties were then used to calculate the light attenuation through a thin tissue layer. The combination band of glucose was found to be the better option, relative to the first overtone band, as the absorptivity of glucose molecules is higher, while the reduction in unscattered transmittance due to tissue growth is less. Additionally, as the wound tissue was found to be highly scattering, the unscattered transmittance of the tissue layer is expected to be very low. Therefore, a sensor configuration which measures the diffuse transmittance and/or reflectance instead was recommended. (a) Dummy sensor; (b) explanted dummy sensor in tissue lump; (c) removal of dummy sensor from tissue lump; and (d) 900 µm slices of tissue lump. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensor development for in situ detection of concentration polarization and fouling of reverse osmosis membranes

NASA Astrophysics Data System (ADS)

Detrich, Kahlil T.; Goulbourne, Nakhiah C.

2009-03-01

The purpose of this research is to evaluate three polymer electroding techniques in developing a novel in situ sensor for an RO system using the electrical response of a thin film composite sensor. Electrical impedance spectroscopy (EIS) was used to measure the sensor response when exposed to sodium chloride solutions with concentrations from 0.1 M to 0.8 M in both single and double bath configurations. An insulated carbon grease sensor was mechanically stable while a composite Direct Assembly Process (DAP) sensor was fragile upon hydration. Scanning electron microscopy results from an impregnation-reduction technique showed gold nanoparticles were deposited most effectively when presoaked in a potassium hydroxide solution and on an uncoated membrane; surface resistances remained too high for sensor implementation. Through thickness carbon grease sensors showed a transient response to changes in concentration, and no meaningful concentration sensitivity was noted for the time scales over which EIS measurements were taken. Surface carbon grease electrodes attached to the polyamide thin film were not sensitive to concentration. The impedance spectra indicated the carbon grease sensor was unable to detect changes in concentration in double bath experiments when implemented with the polyamide surface exposed to salt solutions. DAP sensors lacked a consistent response to changes in concentration too. A reverse double bath experiment with the polysulfone layer exposed to a constant concentration exhibited a transient impedance response similar to through thickness carbon grease sensors in a single bath at constant concentration. These results suggest that the microporous polysulfone layer is responsible for sensor response to concentration.

Double Layers in Astrophysics

NASA Technical Reports Server (NTRS)

Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

1987-01-01

Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

High-sensitivity pH sensor using separative extended-gate field-effect transistors with single-walled carbon-nanotube networks

NASA Astrophysics Data System (ADS)

Pyo, Ju-Young; Cho, Won-Ju

2018-04-01

We fabricate high-sensitivity pH sensors using single-walled carbon-nanotube (SWCNT) network thin-film transistors (TFTs). The sensing and transducer parts of the pH sensor are composed of separative extended-sensing gates (ESGs) with SnO2 ion-sensitive membranes and double-gate structure TFTs with thin SWCNT network channels of ∼1 nm and AlO x top-gate insulators formed by the solution-deposition method. To prevent thermal process-induced damages on the SWCNT channel layer due to the post-deposition annealing process and improve the electrical characteristics of the SWCNT-TFTs, microwave irradiation is applied at low temperatures. As a result, a pH sensitivity of 7.6 V/pH, far beyond the Nernst limit, is obtained owing to the capacitive coupling effect between the top- and bottom-gate insulators of the SWCNT-TFTs. Therefore, double-gate structure SWCNT-TFTs with separated ESGs are expected to be highly beneficial for high-sensitivity disposable biosensor applications.

Light/negative bias stress instabilities in indium gallium zinc oxide thin film transistors explained by creation of a double donor

NASA Astrophysics Data System (ADS)

Migliorato, Piero; Delwar Hossain Chowdhury, Md; Gwang Um, Jae; Seok, Manju; Jang, Jin

2012-09-01

The analysis of current-voltage (I-V) and capacitance-voltage (C-V) characteristics for amorphous indium gallium zinc oxide Thin film transistors as a function of active layer thickness shows that negative bias under illumination stress (NBIS) is quantitatively explained by creation of a bulk double donor, with a shallow singly ionized state ɛ(0/+) > EC-0.073 eV and a deep doubly ionized state ɛ(++/+) < EC-0.3 eV. The gap density of states, extracted from the capacitance-voltage curves, shows a broad peak between EC-E = 0.3 eV and 1.0 eV, which increases in height with NBIS stress time and corresponds to the broadened transition energy between singly and doubly ionized states. We propose that the center responsible is an oxygen vacancy and that the presence of a stable singly ionized state, necessary to explain our experimental results, could be due to the defect environment provided by the amorphous network.

Strain relaxation of thin Si{sub 0.6}Ge{sub 0.4} grown with low-temperature buffers by molecular beam epitaxy

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

Zhao, M.; Hansson, G. V.; Ni, W.-X.

A double-low-temperature-buffer variable-temperature growth scheme was studied for fabrication of strain-relaxed thin Si{sub 0.6}Ge{sub 0.4} layer on Si(001) by using molecular beam epitaxy (MBE), with particular focuses on the influence of growth temperature of individual low-temperature-buffer layers on the relaxation process and final structural qualities. The low-temperature buffers consisted of a 40 nm Si layer grown at an optimized temperature of {approx}400 deg. C, followed by a 20 nm Si{sub 0.6}Ge{sub 0.4} layer grown at temperatures ranging from 50 to 550 deg. C. A significant relaxation increase together with a surface roughness decrease both by a factor of {approx}2, accompaniedmore » with the cross-hatch/cross-hatch-free surface morphology transition, took place for the sample containing a low-temperature Si{sub 0.6}Ge{sub 0.4} layer that was grown at {approx}200 deg. C. This dramatic change was explained by the association with a certain onset stage of the ordered/disordered growth transition during the low-temperature MBE, where the high density of misfit dislocation segments generated near surface cusps largely facilitated the strain relaxation of the top Si{sub 0.6}Ge{sub 0.4} layer.« less

Enhanced sensitivity to dielectric function and thickness of absorbing thin films by combining total internal reflection ellipsometry with standard ellipsometry and reflectometry

NASA Astrophysics Data System (ADS)

Lizana, A.; Foldyna, M.; Stchakovsky, M.; Georges, B.; Nicolas, D.; Garcia-Caurel, E.

2013-03-01

High sensitivity of spectroscopic ellipsometry and reflectometry for the characterization of thin films can strongly decrease when layers, typically metals, absorb a significant fraction of the light. In this paper, we propose a solution to overcome this drawback using total internal reflection ellipsometry (TIRE) and exciting a surface longitudinal wave: a plasmon-polariton. As in the attenuated total reflectance technique, TIRE exploits a minimum in the intensity of reflected transversal magnetic (TM) polarized light and enhances the sensitivity of standard methods to thicknesses of absorbing films. Samples under study were stacks of three films, ZnO : Al/Ag/ZnO : Al, deposited on glass substrates. The thickness of the silver layer varied from sample to sample. We performed measurements with a UV-visible phase-modulated ellipsometer, an IR Mueller ellipsometer and a UV-NIR reflectometer. We used the variance-covariance formalism to evaluate the sensitivity of the ellipsometric data to different parameters of the optical model. Results have shown that using TIRE doubled the sensitivity to the silver layer thickness when compared with the standard ellipsometry. Moreover, the thickness of the ZnO : Al layer below the silver layer can be reliably quantified, unlike for the fit of the standard ellipsometry data, which is limited by the absorption of the silver layer.

Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification.

PubMed

Lassnig, R; Hollerer, M; Striedinger, B; Fian, A; Stadlober, B; Winkler, A

2015-11-01

In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p ++ -silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3-4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact-channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility.

Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification

PubMed Central

Lassnig, R.; Hollerer, M.; Striedinger, B.; Fian, A.; Stadlober, B.; Winkler, A.

2015-01-01

In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p++-silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3–4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact–channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility. PMID:26543442

Two-band induced superconductivity in single-layer graphene and topological insulator bismuth selenide

NASA Astrophysics Data System (ADS)

Talantsev, E. F.; Crump, W. P.; Tallon, J. L.

2018-01-01

Proximity-induced superconductivity in single-layer graphene (SLG) and in topological insulators represent almost ideal examples of superconductivity in two dimensions. Fundamental mechanisms governing superconductivity in the 2D limit are of central interest for modern condensed-matter physics. To deduce fundamental parameters of superconductor/graphene/superconductor and superconductor/bismuth selenide/superconductor junctions we investigate the self-field critical currents in these devices using the formalism of the Ambegaokar-Baratoff model. Our central finding is that the induced superconducting state in SLG and bismuth selenide each exhibits gapping on two superconducting bands. Based on recent results obtained on ultra-thin films of natural superconductors, including single-atomic layer of iron selenide, double and triple atomic layers of gallium, and several atomic layer tantalum disulphide, we conclude that a two-band induced superconducting state in SLG and bismuth selenide is part of a wider, more general multiple-band phenomenology of currently unknown origin.

A novel antiproliferative drug coating for glaucoma drainage devices.

PubMed

Ponnusamy, Thiruselvam; Yu, Haini; John, Vijay T; Ayyala, Ramesh S; Blake, Diane A

2014-01-01

The implantation of a glaucoma drainage device (GDD) is often necessary for intractable cases of glaucoma. Currently, the success rate of GDD implants is relatively low because fibrosis that develops during the wound-healing process ultimately blocks fluid drainage. We describe herein a novel porous coating for Ahmed glaucoma valves based on biodegradable poly(lactic-co-glycolic acid) (PLGA). Thin films of PLGA were fabricated using a spin-coating technique. The procedure led to an asymmetric pore structure that was exploited to control the rate of dissolution. Double-layered porous films were constructed to achieve continuous drug release. A cell culture system was used to test the efficacy of these coatings. Double-layered films were manufactured to provide a burst of mitomycin C (MMC) release followed by a slow release of 5-fluorouracil (5-FU), which together prevented fibrosis over the most active period of postoperative wound healing (0 to 28 d). Double-layered films containing 5-FU only in the bottom layer showed a 3- to 5-day delay in drug release, followed by a sharp increase that continued for ~28 days. MMC was stable only when surface-loaded, and this drug was therefore surface-loaded onto the top PLGA layer to provide a continuous release of antifibrotics over the wound-healing period. The combined use of both MMC and 5-FU in a biodegradable device inhibits cell proliferation in a tissue culture model and has the potential to reduce fibrosis and increase the success rate of GDD implants. The design is simple and can be scaled for commercial production.

Superficial Macromolecular Arrays on the Cell Wall of Spirillum putridiconchylium

PubMed Central

Beveridge, T. J.; Murray, R. G. E.

1974-01-01

Electron microscopy of the cell envelope of Spirillum putridiconchylium, using negatively stained, thin-sectioned, and replicated freeze-etched preparations, showed two superficial wall layers forming a complex macromolecular pattern on the external surface. The outer structured layer was a linear array of particles overlying an inner tetragonal array of larger subunits. They were associated in a very regular fashion, and the complex was bonded to the outer, pitted surface of the lipopolysaccharide tripartite layer of the cell wall. The relationship of the components of the two structured layers was resolved with the aid of optical diffraction, combined with image filtering and reconstruction and linear and rotary integration techniques. The outer structural layer consisted of spherical 1.5-nm units set in double lines determined by the size and arrangement of 6- by 3-nm inner structural layer subunits, which bore one outer structural layer unit on each outer corner. The total effect of this arrangement was a double-ridged linear structure that was evident in surface replicas and negatively stained fragments of the whole wall. The packing of these units was not square but skewed by 2° off the perpendicular so that the “unit array” described by optical diffraction and linear integration appeared to be a deformed tetragon. The verity of the model was checked by using a photographically reduced image to produce an optical diffraction pattern for comparison with that of the actual layers. The correspondence was nearly perfect. Images PMID:4137219

Effects of A Weak Crustal Layer in a Transtensional Pull-Apart Basin: Results from a Scaled Physical Modeling Study

NASA Astrophysics Data System (ADS)

Dooley, T. P.; Monastero, F. C.; McClay, K. R.

2007-12-01

Results of scaled physical models of a releasing bend in the transtensional, dextral strike-slip Coso geothermal system located in the southwest Basin and Range, U.S.A., are instructive for understanding crustal thinning and heat flow in such settings. The basic geometry of the Coso system has been approximated to a 30? dextral releasing stepover. Twenty-four model runs were made representing successive structural iterations that attempted to replicate geologic structures found in the field. The presence of a shallow brittle-ductile transition in the field known from a well-documented seismic-aseismic boundary, was accommodated by inclusion of layers of silicone polymer in the models. A single polymer layer models a conservative brittle-ductile transition in the Coso area at a depth of 6 km. Dual polymer layers impose a local elevation of the brittle-ductile transition to a depth of 4 km. The best match to known geologic structures was achieved with a double layer of silicone polymers with an overlying layer of 100 µm silica sand, a 5° oblique divergent motion across the master strike-slip faults, and a thin-sheet basal rubber décollement. Variation in the relative displacement of the two base plates resulted in some switching in basin symmetry, but the primary structural features remained essentially the same. Although classic, basin-bounding sidewall fault structures found in all pull-apart basin analog models formed in our models, there were also atypical complex intra-basin horst structures that formed where the cross-basin fault zone is situated. These horsts are flanked by deep sedimentary basins that were the locus of maximum crustal thinning accomplished via high-angle extensional and oblique-extensional faults that become progressively more listric with depth as the brittle-ductile transition was approached. Crustal thinning was as much as 50% of the original model depth in dual polymer models. The weak layer at the base of the upper crust appears to focus brittle deformation and facilitate formation of listric normal faults. The implications of these modeling efforts are that: 1) Releasing stepovers that have associated weak upper crust will undergo a more rapid rate of crustal thinning due to the strain focusing effect of this ductile layer; 2) The origin of listric normal faults in these analog models is related to the presence of the weak, ductile layer; and, 3) Due to high dilatency related to major intra-basin extension these stepover structures can be the loci for high heat flow.

Permeation of 70% isopropyl alcohol through surgical gloves: comparison of the standard methods ASTM F739 and EN 374.

PubMed

Mäkelä, Erja A; Vainiotalo, Sinikka; Peltonen, Kimmo

2003-06-01

Standard test methods ASTM F739 and EN 374 were compared by assessing the permeation of 70% isopropyl alcohol (2-propanol) through seven brands of surgical gloves. The two standards differ in the flow rates of the collection medium and in the chemical permeation rate at which the breakthrough time (BTT) is detected, the EN detection level being 10 times higher than the permeation rate used by ASTM. In a departure from the EN standard method, a 4 h testing time was used instead of 8 h. All of the tested gloves were from the same manufacturer and were made from either natural rubber (NR) (six brands) or chloroprene rubber (CR) (one brand). Two of the NR glove brands were double layered. For the thin NR gloves (0.22, 0.28 and 0.27 mm) the permeation rates were higher throughout the tests with a flow rate of 474 ml/min (EN) of the collection medium (nitrogen) compared with the permeation rates obtained with a flow rate of 52 ml/min (ASTM). These resulted in BTTs of 4.6, 6.5 and 7.6 min (EN) and 4.8, 6.5 and 9.1 min (ASTM), respectively. No statistical difference could be observed between the BTT values obtained with the two standard methods for any of the thin gloves. Thus, although the ASTM standard has a lower criterion for the detection of permeation, it does not necessarily produce shorter BTTs. For the better barriers the methods yielded more equivalent permeation rate curves and thus the EN BTTs were longer than the ASTM BTTs: the EN results were 21, 80, 122 and >240 min compared with the ASTM results of 12, 32, 38 and 103 min for glove thicknesses of 0.37 (NR), 0.22 + 0.22 (double layered NR), 0.31 + 0.29 (double layered NR) and 0.19 mm (CR), respectively.

On the parameterization of interleaving and turbulent mixing using CTD data from the Azores Frontal Zone

NASA Astrophysics Data System (ADS)

Kuzmina, N. P.

2000-01-01

CTD-data obtained in the Azores Frontal Zone using a towed undulating vehicle are analyzed to study the relationship between characteristics of intrusions and mean parameters of the thermohaline field. A self-similar dependence between intrusion intensity and hydrological parameters is obtained. The most well-founded interpretation of the empirical dependence is as follows: (a) the main source supporting intrusive layering is the salt finger convection; (b) the abrupt decrease of intrusion intensity with the reduction of geostrophic Richardson number obtained from the analysis is explained by the beginning of turbulence when salt fingers do not work any longer, so the "driving force" for intrusive motion disappears. These results are consistent with the conclusions of the paper [Kuzmina N.P., Rodionov V.B., 1992. About the influence of baroclinicity upon generation of the thermohaline intrusions in the oceanic frontal zones. Izvestiya Akad. Nauk SSSR, Atmosperic and Oceanic Physics 28 (10-11), 1077-1086]. These conclusions imply that there are three main mechanisms of intrusive layering at oceanic fronts, namely the 2D baroclinic instability of geostrophic flow, the vertical shear instability and the thermohaline instability where the driving source of intrusive motion is double diffusive convection. The baroclinic and thermohaline instabilities can generate intrusions of large vertical scale, while vertical shear instability usually gives rise to thin turbulent layers. Turbulence in these thin layers can prevent salt finger convection and thus destroy the energy source of the intrusive motion conditioned by thermoclinicity. Therefore, the baroclinicity plays two parts in the processes of the intrusive layering: (1) it prevents double-diffusion interleaving by means of turbulence, and (2) it generates intrusions due to the 2D baroclinic instability of geostrophic current. Using features of thermohaline interleaving as a specific tracer of turbulent mixing, we have estimated turbulent mixing coefficient as k t˜ Ri-0.8 ( Ri>1), where Ri is the geostrophic Richardson number. Application of the proposed approach to other frontal zones is discussed.

Realizing high-performance metamaterial absorber based on the localized surface plasmon resonance in the terahertz regime

NASA Astrophysics Data System (ADS)

Yunfeng, Lin; Xiaoqi, Hu; Lin, Hu

2018-04-01

A composite structure design metamaterial absorber is designed and simulated. The proposed composite structure consists of a double-hole sub-structure and a double-metallic particle sub-structure. The damping constant of bulk gold layer is optimized to eliminate the adverse effects of the grain boundary and the surface scattering of thin films on the absorption property. Two absorption peaks (A1 = 58%, A2 = 23%) are achieved based on the localized surface plasmon (LSP) modes resonance. Moreover, the plasmonic hybridization phenomenon between LSP modes is found, which leads to the absorption enhancement between two absorption peaks. The proposed metamaterial absorber holds the property of wide-angle incidence.

System for analysis of explosives

DOEpatents

Haas, Jeffrey S [San Ramon, CA

2010-06-29

A system for analysis of explosives. Samples are spotted on a thin layer chromatography plate. Multi-component explosives standards are spotted on the thin layer chromatography plate. The thin layer chromatography plate is dipped in a solvent mixture and chromatography is allowed to proceed. The thin layer chromatography plate is dipped in reagent 1. The thin layer chromatography plate is heated. The thin layer chromatography plate is dipped in reagent 2.

Effect of spin-orbit coupling on excitonic levels in layered chalcogenide-fluorides

NASA Astrophysics Data System (ADS)

Zakutayev, Andriy; Kykyneshi, Robert; Kinney, Joseph; McIntyre, David H.; Schneider, Guenter; Tate, Janet

2008-03-01

BaCuChF (Ch=S,Se,Te) comprise a family of wide-bandgap p-type semiconductors. Due to their high transparency and conductivity, they have potential applications as components of transparent thin-film transistors, solar cells and light-emitting devices. Thin films of BaCuChF have been deposited on MgO by pulsed laser deposition (PLD). Solid solutions BaCuS1-xSexTeF and BaCuSe1-xTex have been prepared by PLD of alternating thin BaCuChF layers. All films were deposited at elevated substrate temperatures. They are preferentially c-axis oriented, conductive and transparent in the visible part of the spectrum. Double excitonic peaks have been observed in the absorption spectrum of these films in the temperature range from 80 to 300K. The separation between the peaks in the doublet increases with the increase of atomic mass of the chalcogen. It also increases with the increase of the heavy chalcogen component x in the solid solutions. This separation most likely is caused by the effect of spin-orbit coupling in the chalcogen atoms on excitonic levels in BaCuChF.

Geophysical Investigation at Gathright Dam.

DTIC Science & Technology

1982-03-01

a limestone, is actually a calcareous and dolomitic siltstone. The siltstone is thin-bedded and in areas al- most fissile. The jointing of the...voltage across the Helmholtz double layer (laminar flow con- dition in a capillary tube) n = viscosity of the pore fluid AP = pressure drop along...spring RB-2 only. c. In RS-3, the fractured and clayey zone at el 1370 pro- duced muddy flow in the river spring. d. Core boring RS-4 caused muddy flow in

Colloidal models. A bit of history.

PubMed

Lyklema, Johannes

2015-05-15

This paper offers an anthology on developments in colloid and interface science emphasizing themes that may be of direct or indirect interest to Interfaces Against Pollution. Topics include the determination of Avogadro's number, development in the insight into driving forces for double layer formation, colloid stability, thin films, and thermodynamic approaches in interfacial electrochemistry. Some personal reminiscences of key players in the field are included, partly to illustrate historical developments. Copyright © 2014 Elsevier Inc. All rights reserved.

Explosive Magnetic Reconnection in Double-current Sheet Systems: Ideal versus Resistive Tearing Mode

NASA Astrophysics Data System (ADS)

Baty, Hubert

2017-03-01

Magnetic reconnection associated with the tearing instability occurring in double-current sheet systems is investigated within the framework of resistive magnetohydrodynamics (MHD) in a two-dimensional Cartesian geometry. A special emphasis on the existence of fast and explosive phases is taken. First, we extend the recent theory on the ideal tearing mode of a single-current sheet to a double-current layer configuration. A linear stability analysis shows that, in long and thin systems with (length to shear layer thickness) aspect ratios scaling as {S}L9/29 (S L being the Lundquist number based on the length scale L), tearing modes can develop on a fast Alfvénic timescale in the asymptotic limit {S}L\\to ∞ . The linear results are confirmed by means of compressible resistive MHD simulations at relatively high S L values (up to 3× {10}6) for different current sheet separations. Moreover, the nonlinear evolution of the ideal double tearing mode (IDTM) exhibits a richer dynamical behavior than its single-tearing counterpart, as a nonlinear explosive growth violently ends up with a disruption when the two current layers interact trough the merging of plasmoids. The final outcome of the system is a relaxation toward a new state, free of magnetic field reversal. The IDTM dynamics is also compared to the resistive double tearing mode dynamics, which develops in similar systems with smaller aspect ratios, ≳ 2π , and exhibits an explosive secondary reconnection, following an initial slow resistive growth phase. Finally, our results are used to discuss the flaring activity in astrophysical magnetically dominated plasmas, with a particular emphasis on pulsar systems.

Removal of long-lived 222Rn daughters by electropolishing thin layers of stainless steel

NASA Astrophysics Data System (ADS)

Schnee, R. W.; Bowles, M. A.; Bunker, R.; McCabe, K.; White, J.; Cushman, P.; Pepin, M.; Guiseppe, V. E.

2013-08-01

Long-lived alpha and beta emitters in the 222Rn decay chain on detector surfaces may be the limiting background in many experiments attempting to detect dark matter or neutrinoless double beta decay. Removal of tens of microns of material via electropolishing has been shown to be effective at removing radon daughters implanted into material surfaces. Some applications, however, require the removal of uniform and significantly smaller thicknesses. Here, we demonstrate that electropolishing < 1 μm from stainless-steel plates reduces the contamination efficiently, by a factor > 100. Examination of electropolished wires with a scanning electron microscope confirms that the thickness removed is reproducible and reasonably uniform. Together, these tests demonstrate the effectiveness of removal of radon daughters for a proposed low-radiation, multi-wire proportional chamber (the BetaCage), without compromising the screener's energy resolution. More generally, electropolishing thin layers of stainless steel may effectively remove radon daughters without compromising precision-machined parts.

Purely electronic mechanism of electrolyte gating of indium tin oxide thin films

DOE PAGES

Leng, X.; Bozovic, I.; Bollinger, A. T.

2016-08-10

Epitaxial indium tin oxide films have been grown on both LaAlO 3 and yttria-stabilized zirconia substrates using RF magnetron sputtering. Electrolyte gating causes a large change in the film resistance that occurs immediately after the gate voltage is applied, and shows no hysteresis during the charging/discharging processes. When two devices are patterned next to one another and the first one gated through an electrolyte, the second one shows no changes in conductance, in contrast to what happens in materials (like tungsten oxide) susceptible to ionic electromigration and intercalation. These findings indicate that electrolyte gating in indium tin oxide triggers amore » pure electronic process (electron depletion or accumulation, depending on the polarity of the gate voltage), with no electrochemical reactions involved. Electron accumulation occurs in a very thin layer near the film surface, which becomes highly conductive. These results contribute to our understanding of the electrolyte gating mechanism in complex oxides and may be relevant for applications of electric double layer transistor devices.« less

Superconductivity in ion-beam-mixed layered Au-Si thin films

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

Jisrawi, N.M.; McLean, W.L.; Stoffel, N.G.

The superconducting properties of thin films made by mixing alternating layers of Au and Si using ion-beam bombardment correlate with the formation of metastable metallic phases in what is otherwise a simple eutectic system. Transmission-electron-microscopy measurements reveal the superconducting phases to be amorphous. Compound formation and the nature of Au-Si bonding in these metastable phases are demonstrated from x-ray photoelectron spectroscopy and from a previous study of x-ray-absorption spectroscopy. After mixing with a beam of Xe ions, multilayered films with an average nominal composition Au{sub {ital x}}Si{sub 1{minus}{ital x}}, where {ital x}=0.2, 0.4, 0.5, 0.72, and 0.8, exhibited superconducting transitionmore » temperatures in the range 0.2--1.2 K. A double transition feature in the magnetic field dependence of the resistivity is attributed to the formation of more than one metastable metallic phase in the same sample as the ion dose increases.« less

Removal of long-lived {sup 222}Rn daughters by electropolishing thin layers of stainless steel

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

Schnee, R. W.; Bowles, M. A.; Bunker, R.

Long-lived alpha and beta emitters in the {sup 222}Rn decay chain on detector surfaces may be the limiting background in many experiments attempting to detect dark matter or neutrinoless double beta decay. Removal of tens of microns of material via electropolishing has been shown to be effective at removing radon daughters implanted into material surfaces. Some applications, however, require the removal of uniform and significantly smaller thicknesses. Here, we demonstrate that electropolishing < 1 μm from stainless-steel plates reduces the contamination efficiently, by a factor > 100. Examination of electropolished wires with a scanning electron microscope confirms that the thicknessmore » removed is reproducible and reasonably uniform. Together, these tests demonstrate the effectiveness of removal of radon daughters for a proposed low-radiation, multi-wire proportional chamber (the BetaCage), without compromising the screener’s energy resolution. More generally, electropolishing thin layers of stainless steel may effectively remove radon daughters without compromising precision-machined parts.« less

Thin liquid films in improved oil recovery from low-salinity brine

DOE PAGES

Myint, Philip C.; Firoozabadi, Abbas

2015-03-19

Low-salinity waterflooding is a relatively new method for improved oil recovery that has generated much interest. It is generally believed that low-salinity brine alters the wettability of oil reservoir rocks towards a wetting state that is optimal for recovery. The mechanism(s) by which the wettability alteration occurs is currently an unsettled issue. This study reviews recent studies on wettability alteration mechanisms that affect the interactions between the brine/oil and brine/rock interfaces of thin brine films that wet the surface of reservoir rocks. Of these mechanisms, we pay particular attention to double-layer expansion, which is closely tied to an increase inmore » the thickness and stability of the thin brine films. Our review examines studies on both sandstones and carbonate rocks. We conclude that the thin-brine-film mechanisms provide a good qualitative, though incomplete, picture of this very complicated problem. Finally, we give suggestions for future studies that may help provide a more quantitative and complete understanding of low-salinity waterflooding.« less

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

Hsu, Chih-Hao; Yue, Kan; Wang, Jing

Controlling self-assembled nanostructures in thin films allows the bottom-up fabrication of ordered nanoscale patterns. Here we report the unique thickness-dependent phase behavior in thin films of a bolaform-like giant surfactant, which consists of butyl- and hydroxyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS and DPOSS) cages telechelically located at the chain ends of a polystyrene (PS) chain with 28 repeating monomers on average. In the bulk, BPOSS-PS28-DPOSS forms a double gyroid (DG) phase. Both grazing incidence small angle X-ray scattering and transmission electron microscopy techniques are combined to elucidate the thin film structures. Interestingly, films with thicknesses thinner than 200 nm exhibit anmore » irreversible phase transition from hexagonal perforated layer (HPL) to compressed hexagonally packed cylinders (c-HEX) at 130 °C, while films with thickness larger than 200 nm show an irreversible transition from HPL to DG at 200 °C. The thickness-controlled transition pathway suggests possibilities to obtain diverse patterns via thin film self-assembly.« less

Organic and inorganic passivation of p-type SnO thin-film transistors with different active layer thicknesses

NASA Astrophysics Data System (ADS)

Qu, Yunxiu; Yang, Jia; Li, Yunpeng; Zhang, Jiawei; Wang, Qingpu; Song, Aimin; Xin, Qian

2018-07-01

Bottom gated thin-film transistors (TFTs) with various sputtered SnO active layer thicknesses ranging from 10 to 30 nm and different passivation layers have been investigated. The device with 20 nm SnO showed the highest on/off ratio of 1.7 × 104 and the smallest subthreshold swing of 8.43 V dec‑1, and the mobility (0.76 cm2 V‑1 s‑1) was only slightly lower than in TFTs with a thicker SnO layer. However, both the mobility and the on/off ratio of the 15 nm SnO TFT dropped significantly by one order of magnitude. This indicated a strong influence of the top surface on the carrier transport, and we thus applied an organic or an inorganic encapsulation material to passivate the top surface. In the 20 nm TFT, the on/off ratio was doubled after passivation. The performance of the 15 nm TFT was improved even more dramatically with the on/off ratio increased by one order of magnitude and the mobility increased also significantly. Our experiment shows that polymethyl methacrylate passivation is more effective to reduce the shallow trap states, and Al2O3 is more effective in reducing the deep traps in the SnO channel.

4D in situ visualization of electrode morphology changes during accelerated degradation in fuel cells by X-ray computed tomography

NASA Astrophysics Data System (ADS)

White, Robin T.; Wu, Alex; Najm, Marina; Orfino, Francesco P.; Dutta, Monica; Kjeang, Erik

2017-05-01

A four-dimensional visualization approach, featuring three dimensions in space and one dimension in time, is proposed to study local electrode degradation effects during voltage cycling in fuel cells. Non-invasive in situ micro X-ray computed tomography (XCT) with a custom fuel cell fixture is utilized to track the same cathode catalyst layer domain throughout various degradation times from beginning-of-life (BOL) to end-of-life (EOL). With this unique approach, new information regarding damage features and trends are revealed, including crack propagation and catalyst layer thinning being quantified by means of image processing and analysis methods. Degradation heterogeneities as a result of local environmental variations under land and channel are also explored, with a higher structural degradation rate under channels being observed. Density and compositional changes resulting from carbon corrosion and catalyst layer collapse and thinning are observed by changes in relative X-ray attenuation from BOL to EOL, which also indicate possible vulnerable regions where crack initiation and propagation may occur. Electrochemical diagnostics and morphological features observed by micro-XCT are correlated by additionally collecting effective catalyst surface area, double layer capacitance, and polarization curves prior to imaging at various stages of degradation.

Increased Curie Temperature Induced by Orbital Ordering in La0.67Sr0.33MnO3/BaTiO3 Superlattices.

PubMed

Zhang, Fei; Wu, Biao; Zhou, Guowei; Quan, Zhi-Yong; Xu, Xiao-Hong

2018-01-17

Recent theoretical studies indicated that the Curie temperature of perovskite manganite thin films can be increased by more than an order of magnitude by applying appropriate interfacial strain to control orbital ordering. In this work, we demonstrate that the regular intercalation of BaTiO 3 layers between La 0.67 Sr 0.33 MnO 3 layers effectively enhances ferromagnetic order and increases the Curie temperature of La 0.67 Sr 0.33 MnO 3 /BaTiO 3 superlattices. The preferential orbital occupancy of e g (x 2 -y 2 ) in La 0.67 Sr 0.33 MnO 3 layers induced by the tensile strain of BaTiO 3 layers is identified by X-ray linear dichroism measurements. Our results reveal that controlling orbital ordering can effectively improve the Curie temperature of La 0.67 Sr 0.33 MnO 3 films and that in-plane orbital occupancy is beneficial to the double exchange ferromagnetic coupling of thin-film samples. These findings create new opportunities for the design and control of magnetism in artificial structures and pave the way to a variety of novel magnetoelectronic applications that operate far above room temperature.

Comparative measurements of piezoelectric coefficient of PZT films by Berlincourt, interferometer, and vibrometer methods.

PubMed

Huang, Zhaorong; Zhang, Qi; Corkovic, Silvana; Dorey, Robert; Whatmore, Roger W

2006-12-01

Chemical solution deposition (CSD) techniques were used to prepare lead zirconate (Zr) titanate (Ti) (PZT) thin films with Zr/Ti ratios of 30/70 and 52/48. Usually CSD processing is restricted to making crack-free, single-layer films of 70-nm thick, but modifications to the sol-gel process have permitted the fabrication of dense, crack-free, single layers up to 200 to 300 nm thick, which can be built-up into layers up to 3-microm thick. Thicker PZT films (> 2-microm single layer) can be produced by using a composite sol-gel/ceramic process. Knowledge of the electroactive properties of these materials is essential for modeling and design of novel micro-electromechanical systems (MEMS) devices, but accurate measurement of these properties is by no means straightforward. A novel, double-beam, common-path laser interferometer has been developed to measure the longitudinal (d33) piezoelectric coefficient in films; the results were compared with the values obtained by Berlin-court and laser scanning vibrometer methods. It was found that, for thin-film samples, the d(33,f) values obtained from the Berlincourt method are usually larger: than those obtained from the interferometer and the vibrometer methods; the reasons for this are discussed.

Robust optical properties of sandwiched lateral composition modulation GaInP structure grown by molecular beam epitaxy

DOE PAGES

Park, Kwangwook; Kang, Seokjin; Ravindran, Sooraj; ...

2016-12-26

Double-hetero structure lateral composition modulated (LCM) GaInP and sandwiched LCM GaInP having the same active layer thickness were grown and their optical properties were compared. Sandwiched LCM GaInP showed robust optical properties due to periodic potential nature of the LCM structure, and the periodicity was undistorted even for thickness far beyond the critical layer thickness. A thick LCM GaInP structure with undistorted potential that could preserve the properties of native LCM structure was possible by stacking thin LCM GaInP structures interspaced with strain compensating GaInP layers. Furthermore, the sandwiched structure could be beneficial in realizing the LCM structure embedded highmore » efficiency solar cells.« less

Improving Osteoblast Response In Vitro by a Nanostructured Thin Film with Titanium Carbide and Titanium Oxides Clustered around Graphitic Carbon.

PubMed

Longo, Giovanni; Ioannidu, Caterina Alexandra; Scotto d'Abusco, Anna; Superti, Fabiana; Misiano, Carlo; Zanoni, Robertino; Politi, Laura; Mazzola, Luca; Iosi, Francesca; Mura, Francesco; Scandurra, Roberto

2016-01-01

Recently, we introduced a new deposition method, based on Ion Plating Plasma Assisted technology, to coat titanium implants with a thin but hard nanostructured layer composed of titanium carbide and titanium oxides, clustered around graphitic carbon. The nanostructured layer has a double effect: protects the bulk titanium against the harsh conditions of biological tissues and in the same time has a stimulating action on osteoblasts. The aim of this work is to describe the biological effects of this layer on osteoblasts cultured in vitro. We demonstrate that the nanostructured layer causes an overexpression of many early genes correlated to proteins involved in bone turnover and an increase in the number of surface receptors for α3β1 integrin, talin, paxillin. Analyses at single-cell level, by scanning electron microscopy, atomic force microscopy, and single cell force spectroscopy, show how the proliferation, adhesion and spreading of cells cultured on coated titanium samples are higher than on uncoated titanium ones. Finally, the chemistry of the layer induces a better formation of blood clots and a higher number of adhered platelets, compared to the uncoated cases, and these are useful features to improve the speed of implant osseointegration. In summary, the nanostructured TiC film, due to its physical and chemical properties, can be used to protect the implants and to improve their acceptance by the bone.

Electrical properties of double layer dielectric structures for space technology

NASA Astrophysics Data System (ADS)

Lian, Anqing

1993-04-01

Polymeric films such as polyimide (PI) and polyethylene terephthalate (PET) are used in space technology as thermal blankets. Thin SiO2 and SiN coatings plasma deposited onto PI and PET surfaces were proposed to protect the blanket materials against the space environment. The electrical properties of this kind of dual layer dielectric structure were investigated to understand the mechanisms for suppressing charge accumulation and flashover. Bulk and surface electrical conductivities of thin single-layer PI and PET samples and of the dual layer SiO2 and SiN combinations with PI and PET were measured in a range of applied electrical fields. The capacitance voltage (CV) technique was used for analyzing charge transport and distribution in the structures. The electric current in the bulk of the SiO2/PI and SiN/PI samples was found to depend on the polarity of the electric field. Other samples did not exhibit any such polarity effect. The polarity dependence is attributed to charge trapping at the PI/plasma deposit interface. The CV characteristics of the Al-PI-SiO2-Si structure confirm that charges which can modify the local electric field can be trapped near the interface. A model is proposed to interpret the properties of the currents in dual layer structures. This model can semi-quantitatively explain all the observed results.

Citrate bridges between mineral platelets in bone

PubMed Central

Davies, Erika; Müller, Karin H.; Wong, Wai Ching; Pickard, Chris J.; Reid, David G.; Skepper, Jeremy N.; Duer, Melinda J.

2014-01-01

We provide evidence that citrate anions bridge between mineral platelets in bone and hypothesize that their presence acts to maintain separate platelets with disordered regions between them rather than gradual transformations into larger, more ordered blocks of mineral. To assess this hypothesis, we take as a model for a citrate bridging between layers of calcium phosphate mineral a double salt octacalcium phosphate citrate (OCP-citrate). We use a combination of multinuclear solid-state NMR spectroscopy, powder X-ray diffraction, and first principles electronic structure calculations to propose a quantitative structure for this material, in which citrate anions reside in a hydrated layer, bridging between apatitic layers. To assess the relevance of such a structure in native bone mineral, we present for the first time, to our knowledge, 17O NMR data on bone and compare them with 17O NMR data for OCP-citrate and other calcium phosphate minerals relevant to bone. The proposed structural model that we deduce from this work for bone mineral is a layered structure with thin apatitic platelets sandwiched between OCP-citrate–like hydrated layers. Such a structure can explain a number of known structural features of bone mineral: the thin, plate-like morphology of mature bone mineral crystals, the presence of significant quantities of strongly bound water molecules, and the relatively high concentration of hydrogen phosphate as well as the maintenance of a disordered region between mineral platelets. PMID:24706850

21 CFR 862.2270 - Thin-layer chromatography system for clinical use.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Thin-layer chromatography system for clinical use... Instruments § 862.2270 Thin-layer chromatography system for clinical use. (a) Identification. A thin-layer... a mixture. The mixture of compounds is absorbed onto a stationary phase or thin layer of inert...

Nonlinear dynamics of capacitive charging and desalination by porous electrodes.

PubMed

Biesheuvel, P M; Bazant, M Z

2010-03-01

The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) valid in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory for the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes with different time scales: (i) in the "supercapacitor regime" of small voltages and/or early times, the porous electrode acts like a transmission line, governed by a linear diffusion equation for the electrostatic potential, scaled to the RC time of a single pore, and (ii) in the "desalination regime" of large voltages and long times, the porous electrode slowly absorbs counterions, governed by coupled, nonlinear diffusion equations for the pore-averaged potential and salt concentration.

Nonlinear dynamics of capacitive charging and desalination by porous electrodes

NASA Astrophysics Data System (ADS)

Biesheuvel, P. M.; Bazant, M. Z.

2010-03-01

The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) valid in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory for the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes with different time scales: (i) in the “supercapacitor regime” of small voltages and/or early times, the porous electrode acts like a transmission line, governed by a linear diffusion equation for the electrostatic potential, scaled to the RC time of a single pore, and (ii) in the “desalination regime” of large voltages and long times, the porous electrode slowly absorbs counterions, governed by coupled, nonlinear diffusion equations for the pore-averaged potential and salt concentration.

Substituted Quaternary Ammonium Salts Improve Low-Temperature Performance of Double-Layer Capacitors

NASA Technical Reports Server (NTRS)

Brandon, Erik J.; Smart, Marshall C.; West, William C.

2011-01-01

Double-layer capacitors are unique energy storage devices, capable of supporting large current pulses as well as a very high number of charging and discharging cycles. The performance of doublelayer capacitors is highly dependent on the nature of the electrolyte system used. Many applications, including for electric and fuel cell vehicles, back-up diesel generators, wind generator pitch control back-up power systems, environmental and structural distributed sensors, and spacecraft avionics, can potentially benefit from the use of double-layer capacitors with lower equivalent series resistances (ESRs) over wider temperature limits. Higher ESRs result in decreased power output, which is a particular problem at lower temperatures. Commercially available cells are typically rated for operation down to only 40 C. Previous briefs [for example, Low Temperature Supercapacitors (NPO-44386), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), p. 32, and Supercapacitor Electrolyte Solvents With Liquid Range Below 80 C (NPO-44855), NASA Tech Briefs, Vol. 34, No. 1 (January 2010), p. 44] discussed the use of electrolytes that employed low-melting-point co-solvents to depress the freezing point of traditional acetonitrile-based electrolytes. Using these modified electrolyte formulations can extend the low-temperature operational limit of double-layer capacitors beyond that of commercially available cells. This previous work has shown that although the measured capacitance is relatively insensitive to temperature, the ESR can rise rapidly at low temperatures, due to decreased electrolyte conductance within the pores of the high surface- area carbon electrodes. Most of these advanced electrolyte systems featured tetraethylammonium tetrafluoroborate (TEATFB) as the salt. More recent work at JPL indicates the use of the asymmetric quaternary ammonium salt triethylmethylammonium tetrafluoroborate (TEMATFB) or spiro-(l,l')-bipyrrolidium tetrafluoroborate (SBPBF4) in a 1:1 by volume solvent mixture of acetonitrile (AN) and methyl formate (MF) enables double-layer capacitor cells to operate well below -40 C with a relatively low ESR. Typically, a less than twofold increase in ESR is observed at -65 C relative to room-temperature values, when these modified electrolyte blends are used in prototype cells. Double-layer capacitor coin cells filled with these electrolytes have displayed the lowest measured ESR for an organic electrolyte to date at low temperature (based on a wide range of electrolyte screening studies at JPL). The cells featured high-surface-area (approximately equal to 2,500 m/g) carbon electrodes that were 0.50 mm thick and 1.6 cm in diameter, and coated with a thin layer of platinum to reduce cell resistance. A polyethylene separator was used to electrically isolate the electrodes.

Method of transferring a thin crystalline semiconductor layer

DOEpatents

Nastasi, Michael A [Sante Fe, NM; Shao, Lin [Los Alamos, NM; Theodore, N David [Mesa, AZ

2006-12-26

A method for transferring a thin semiconductor layer from one substrate to another substrate involves depositing a thin epitaxial monocrystalline semiconductor layer on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the thin semiconductor layer is bonded to a second substrate and the thin layer is separated away at the interface, which results in transferring the thin epitaxial semiconductor layer from one substrate to the other substrate.

Band structure of one-dimensional photonic crystal with graphene layers using the Fresnel coefficients method

NASA Astrophysics Data System (ADS)

Jafari, A.; Rahmat, A.

2018-04-01

In this paper, we have calculated the band structure of an instance of one-dimensional photonic crystal (1DPC) composed of double-layered dielectrics via the Fresnel coefficients method. Then, we supposed the addition of a thin layer of graphene to each dielectric layer and the given photonic crystal (PC) composed of dielectric-graphene composites. The effects of graphene layers on the PC band structure were evaluated. We found out that according to the effective medium theory unlike the TE polarization, the electric permittivity of the dielectric layers changed at TM polarization. As such, the band structure of PC for TM polarization changed, too. Moreover, instead of bandgap related to “zero averaged refractive index” an approximately omnidirectional bandgap appeared and a related bandgap to “𝜀 = 0” disappeared. In addition, a new angular gap branch appeared at a new frequency at TM polarization in which the width of gap increased as the angle increased.

Enhancement of superconducting transition temperature in FeSe electric-double-layer transistor with multivalent ionic liquids

NASA Astrophysics Data System (ADS)

Miyakawa, Tomoki; Shiogai, Junichi; Shimizu, Sunao; Matsumoto, Michio; Ito, Yukihiro; Harada, Takayuki; Fujiwara, Kohei; Nojima, Tsutomu; Itoh, Yoshimitsu; Aida, Takuzo; Iwasa, Yoshihiro; Tsukazaki, Atsushi

2018-03-01

We report on an enhancement of the superconducting transition temperature (Tc) of the FeSe-based electric-double-layer transistor (FeSe-EDLT) by applying the multivalent oligomeric ionic liquids (ILs). The IL composed of dimeric cation (divalent IL) enables a large amount of charge accumulation on the surface of the FeSe ultrathin film, resulting in inducing electron-rich conduction even in a rather thick 10 nm FeSe channel. The onset Tc in FeSe-EDLT with the divalent IL is enhanced to be approaching about 50 K at the thin limit, which is about 7 K higher than that in EDLT with conventional monovalent ILs. The enhancement of Tc is a pronounced effect of the application of the divalent IL, in addition to the large capacitance, supposing preferable interface formation of ILs driven by geometric and/or Coulombic effect. The present finding strongly indicates that multivalent ILs are powerful tools for controlling and improving physical properties of materials.

Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

NASA Astrophysics Data System (ADS)

Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali

2017-02-01

A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

Extended-gate-type IGZO electric-double-layer TFT immunosensor with high sensitivity and low operation voltage

NASA Astrophysics Data System (ADS)

Liang, Lingyan; Zhang, Shengnan; Wu, Weihua; Zhu, Liqiang; Xiao, Hui; Liu, Yanghui; Zhang, Hongliang; Javaid, Kashif; Cao, Hongtao

2016-10-01

An immunosensor is proposed based on the indium-gallium-zinc-oxide (IGZO) electric-double-layer thin-film transistor (EDL TFT) with a separating extended gate. The IGZO EDL TFT has a field-effect mobility of 24.5 cm2 V-1 s-1 and an operation voltage less than 1.5 V. The sensors exhibit the linear current response to label-free target immune molecule in the concentrations ranging from 1.6 to 368 × 10-15 g/ml with a detection limit of 1.6 × 10-15 g/ml (0.01 fM) under an ultralow operation voltage of 0.5 V. The IGZO TFT component demonstrates a consecutive assay stability and recyclability due to the unique structure with the separating extended gate. With the excellent electrical properties and the potential for plug-in-card-type multifunctional sensing, extended-gate-type IGZO EDL TFTs can be promising candidates for the development of a label-free biosensor for public health applications.

Resonant and nondissipative tunneling in independently contacted graphene structures

NASA Astrophysics Data System (ADS)

Vasko, F. T.

2013-02-01

The tunneling processes between independently contacted graphene sheets separated by thin insulator are restricted by the momentum and energy conservation laws. Because of this, both dissipative tunneling transitions, with momentum transfer due to disorder scattering, and nondissipative regime of tunneling, which appears due to intersection of electron and hole branches of energy spectrum, must be taken into account. The tunneling current density is calculated for the graphene-boron nitride-graphene layers, which is described by the tight-binding approach, and for the predominant momentum scattering by static disorder. Dependencies of current on concentrations in top and bottom graphene layers, which are governed by the voltages applied through independent contacts and gates, are considered for the back- and double-gated structures. The current-voltage characteristics of the back-gated structure are in agreement with the recent experiment [ScienceSCIEAS0036-807510.1126/science.1218461 335, 947 (2012)]. For the double-gated structures, the resonant dissipative tunneling causes a 10-fold enhancement of response which is important for transistor applications.

Investigation on dynamical interaction between a heavy vehicle and road pavement

NASA Astrophysics Data System (ADS)

Yang, Shaopu; Li, Shaohua; Lu, Yongjie

2010-08-01

This paper presents a model for three-dimensional, heavy vehicle-pavement-foundation coupled system, which is modelled as a seven-DOF vehicle moving along a simply supported double-layer rectangular thin plate on a linear viscoelastic foundation. The vertical tyre force is described by a single point-contact model, while the pavement-foundation is modelled as a double-layer plate on a linear viscoelastic foundation. Using the Galerkin method and quick direct integral method, the dynamical behaviour of the vehicle-pavement-foundation coupled system is investigated numerically and compared with that of traditional vehicle system and pavement system. The effects of coupling action on vehicle body vertical acceleration, suspension deformations, tyre forces and pavement displacements are also obtained. The investigation shows that the coupling action could not be neglected even on a smooth road surface, such as highway. Thus, it is necessary to investigate the dynamics of vehicle and pavement simultaneously based on the vehicle-pavement-foundation coupled system.

Triboelectric generator

DOEpatents

Wang, Zhong L; Fan, Fengru; Lin, Long; Zhu, Guang; Pan, Caofeng; Zhou, Yusheng

2015-11-03

A generator includes a thin first contact charging layer and a thin second contact charging layer. The thin first contact charging layer includes a first material that has a first rating on a triboelectric series. The thin first contact charging layer has a first side with a first conductive electrode applied thereto and an opposite second side. The thin second contact charging layer includes a second material that has a second rating on a triboelectric series that is more negative than the first rating. The thin first contact charging layer has a first side with a first conductive electrode applied thereto and an opposite second side. The thin second contact charging layer is disposed adjacent to the first contact charging layer so that the second side of the second contact charging layer is in contact with the second side of the first contact charging layer.

Effect of active-layer composition and structure on device performance of coplanar top-gate amorphous oxide thin-film transistors

NASA Astrophysics Data System (ADS)

Yue, Lan; Meng, Fanxin; Chen, Jiarong

2018-01-01

The thin-film transistors (TFTs) with amorphous aluminum-indium-zinc-oxide (a-AIZO) active layer were prepared by dip coating method. The dependence of properties of TFTs on the active-layer composition and structure was investigated. The results indicate that Al atoms acted as a carrier suppressor in IZO films. Meanwhile, it was found that the on/off current ratio (I on/off) of TFT was improved by embedding a high-resistivity AIZO layer between the low-resistivity AIZO layer and gate insulator. The improvement in I on/off was attributed to the decrease in off-state current of double-active-layer TFT due to an increase in the active-layer resistance and the contact resistance between active layer and source/drain electrode. Moreover, on-state current and threshold voltage (V th) can be mainly controlled through thickness and Al content of the low-resistivity AIZO layer. In addition, the saturation mobility (μ sat) of TFTs was improved with reducing the size of channel width or/and length, which was attributed to the decrease in trap states in the semiconductor and at the semiconductor/gate-insulator interface with the smaller channel width or/and shorter channel length. Thus, we can demonstrate excellent TFTs via the design of active-layer composition and structure by utilizing a low cost solution-processed method. The resulting TFT, operating in enhancement mode, has a high μ sat of 14.16 cm2 V-1 s-1, a small SS of 0.40 V/decade, a close-to-zero V th of 0.50 V, and I on/off of more than 105.

Thin film femtosecond laser damage competition

NASA Astrophysics Data System (ADS)

Stolz, Christopher J.; Ristau, Detlev; Turowski, Marcus; Blaschke, Holger

2009-10-01

In order to determine the current status of thin film laser resistance within the private, academic, and government sectors, a damage competition was started at the 2008 Boulder Damage Symposium. This damage competition allows a direct comparison of the current state of the art of high laser resistance coatings since they are tested using the same damage test setup and the same protocol. In 2009 a high reflector coating was selected at a wavelength of 786 nm at normal incidence at a pulse length of 180 femtoseconds. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials and layer count, and spectral results will also be shared.

BDS thin film damage competition

NASA Astrophysics Data System (ADS)

Stolz, Christopher J.; Thomas, Michael D.; Griffin, Andrew J.

2008-10-01

A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

A fluid collection system for dermal wounds in clinical investigations

PubMed Central

Klopfer, Michael; Li, G.-P.; Widgerow, Alan; Bachman, Mark

2016-01-01

In this work, we demonstrate the use of a thin, self adherent, and clinically durable patch device that can collect fluid from a wound site for analysis. This device is manufactured from laminated silicone layers using a novel all-silicone double-molding process. In vitro studies for flow and delivery were followed by a clinical demonstration for exudate collection efficiency from a clinically presented partial thickness burn. The demonstrated utility of this device lends itself for use as a research implement used to clinically sample wound exudate for analysis. This device can serve as a platform for future integration of wearable technology into wound monitoring and care. The demonstrated fabrication method can be used for devices requiring thin membrane construction. PMID:27051470

Determining and Controlling the Magnesium Composition in CdTe/CdMgTe Heterostructures

DOE PAGES

LeBlanc, E. G.; Edirisooriya, M.; Ogedengbe, O. S.; ...

2017-06-05

The relationships between Mg composition, band gap, and lattice characteristics are investigated for Cd 1-xMg xTe barrier layers using a combination of cathodoluminescence, energy dispersive x-ray spectroscopy, variable angle spectral ellipsometry, and atom probe tomography. The use of a simplified, yet accurate, variable angle spectral ellipsometry analysis is shown to be appropriate for fast determination of composition in thin Cd 1-xMg xTe layers. The validity of using high-resolution x-ray diffraction for CdTe/Cd 1-xMg xTe double heterostructures is discussed. Furthermore, the stability of CdTe/Cd 1-xMg xTe heterostructures are investigated with respect to thermal processing.

Determining and Controlling the Magnesium Composition in CdTe/CdMgTe Heterostructures

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

LeBlanc, E. G.; Edirisooriya, M.; Ogedengbe, O. S.

The relationships between Mg composition, band gap, and lattice characteristics are investigated for Cd 1-xMg xTe barrier layers using a combination of cathodoluminescence, energy dispersive x-ray spectroscopy, variable angle spectral ellipsometry, and atom probe tomography. The use of a simplified, yet accurate, variable angle spectral ellipsometry analysis is shown to be appropriate for fast determination of composition in thin Cd 1-xMg xTe layers. The validity of using high-resolution x-ray diffraction for CdTe/Cd 1-xMg xTe double heterostructures is discussed. Furthermore, the stability of CdTe/Cd 1-xMg xTe heterostructures are investigated with respect to thermal processing.

Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

NASA Astrophysics Data System (ADS)

Decraene, Carolina; Dijckmans, Arne; Reynders, Edwin P. B.

2018-05-01

A method is developed for computing the mean and variance of the diffuse field sound transmission loss of finite-sized layered wall and floor systems that consist of solid, fluid and/or poroelastic layers. This is achieved by coupling a transfer matrix model of the wall or floor to statistical energy analysis subsystem models of the adjacent room volumes. The modal behavior of the wall is approximately accounted for by projecting the wall displacement onto a set of sinusoidal lateral basis functions. This hybrid modal transfer matrix-statistical energy analysis method is validated on multiple wall systems: a thin steel plate, a polymethyl methacrylate panel, a thick brick wall, a sandwich panel, a double-leaf wall with poro-elastic material in the cavity, and a double glazing. The predictions are compared with experimental data and with results obtained using alternative prediction methods such as the transfer matrix method with spatial windowing, the hybrid wave based-transfer matrix method, and the hybrid finite element-statistical energy analysis method. These comparisons confirm the prediction accuracy of the proposed method and the computational efficiency against the conventional hybrid finite element-statistical energy analysis method.

On-chip broadband spectral filtering using planar double high-contrast grating reflectors

NASA Astrophysics Data System (ADS)

Horie, Yu; Arbabi, Amir; Faraon, Andrei

2015-02-01

We propose a broadband free-space on-chip spectrometer based on an array of integrated narrowband filters consisting of Fabry-Perot resonators formed by two high-contrast grating (HCG) based reflectors separated by a low-index thin layer with a fixed cavity thickness. Using numerical simulations, broadband tunability of resonance wavelengths was achieved only by changing the in-plane grating parameters such as period or duty cycle of HCGs while the substrate geometry was kept fixed. Experimentally, the HCG reflectors were fabricated on silicon on insulator (SOI) substrates and high reflectivity was measured, fabrication process for the proposed double HCG-based narrowband filter array was developed. The filtering function that can be spanned over a wide range of wavelengths was measured.

Optical and solid state characterizaion of chemically deposited CuO/PbS double layer thin film

NASA Astrophysics Data System (ADS)

Chukwuemeka, Augustine; Nnabuchi Mishark, Nnamdi

2018-02-01

Optical and solid state characteristics of novel CuO/PbS double layer thin films were studied. Rutherford backscattering (RBS) technique deciphered the thicknesses of the films as 650 nm, 471 nm and 482 nm for as-deposited, annealed at 473 K and 673 K respectively. The XRD analysis depicts increase in grain size and peak intensity as temperature increases. The results of optical characterization show that thermal annealing has profound effects on all the optical and solid state parameters investigated. The absorbance increased with increase in temperature exhibiting maximum for the film annealed at 673 K. The transmittance of the film samples showed a decreasing trend with increase in temperature exhibiting minimum for the film annealed at 673 K. The absorption coefficient increases from 0.001 × 106 m-1 to 0.006 × 106 m-1 for as-deposited, 0.0025 × 106 m-1 to 0.0175 × 106 m-1 for the annealed at 473 K and 0.003 × 106 m-1 to 0.020 × 106 m-1 for the annealed at 673 K. The extinction coefficient increased with increased in temperature exhibiting a maximum for the film annealed at 673 K. The refractive index, real and imaginary dielectric constant do not have a trend with increase in annealing temperature. Increase in annealing temperature lowers the band gap from 4.13 eV for the as-deposited to 4.05 eV and 3.90 eV for the annealed at 473 K and 673 K respectively. The wide- bandgap materials permits devices to operate at much higher voltages, frequencies and temperatures than convection semiconductor materials. Thus, this film could be used for high power applications, light-emitting diodes, transducers and window layers for solar cell fabrication.

Biological UV dosimeters in simulated space irradiation conditions

NASA Astrophysics Data System (ADS)

Rontó, G.; Bérces, A.; Fekete, A.; Kovács, G.; Lammer, H.

For the measurement of the harmful biological effect of solar UV radiation bacteriophage T7 and polycrystalline uracil dosimeters were used. For terrestrial dosimetric purposes bacteriophage T7 has been applied in solution, while uracil in the form of thin layers. For space irradiation dosimetry the uracil, phage T7-DNA and bacteriophage T7 thin layer samples were prepared in vacuum tightly closed sandwich forms covered either by calciumfluoride or quartz windows. The experimental conditions tested correspond to the conditions planned in the EXPOSE facility: the samples were surrounded by nitrogen atmosphere at various humidities, their vacuum stability was tested in the vacuum chamber of the Institute of Space Research,, Graz. All kinds of the thin film samples have been stored in an atmosphere containing Nitrogen and Hidrogen, in quality control no change in the structure of them has been found. To attenuate the high extraterrestrial irradiance neutral filters of 0.5 and 1.0 optical densities have been tested. Irradiation of the samples has been performed with various UV sources: solar simulator, low pressure Mercury lamp, Deuterium lamp. Dose-effect functions have been determined using for the evaluation spectrophotometry in the characteristic UV range, HPLC of photoproducts, PCR of two different primer sequences of phage T7-DNA. Photoproduct formation kinetics was followed by the saturation level of uracil thin layer. Attenuation ability of the neutral filters was controlled with low pressure Mercury lamp by the exposure necessary for saturation of uracil dosimeters. A three and tenfold increase in the exposure was found respectively, while the influence of spectral composition of the irradiation source was tested using Deuterium lamp supplied with Ca F2 and quartz filters respectively. A doubling of the irradiance was necessary for the saturation of uracil with quartz filter.

Characteristics of a 1.6 W Gifford-McMahon Cryocooler with a Double Pipe Regenerator

NASA Astrophysics Data System (ADS)

Masuyama, S.; Numazawa, T.

2017-12-01

This paper focuses on the second stage regenerator of a 4 K Gifford-McMahon (G-M) cryocooler. A three-layer layout of lead (Pb), HoCu2 and Gd2O2S spheres in the second stage regenerator derives a good performance at 4 K. After some modifications, we confirmed that the cooling power of 1.60 W at 4.2 K was achieved by using this three-layer layout. A two-stage G-M cryocooler is RDK-408D2 (SHI) and a compressor is C300G (SUZUKISHOKAN) with a rated electric input power of 7.3 kW at 60 Hz. In order to further improve, a double pipe regenerator was applied to the second stage regenerator. As a double pipe, a stainless steel pipe with thin wall was inserted in the coaxial direction into the second stage regenerator. The helium flow in the second stage regenerator is expected to be non-uniform flow because of the distribution of helium density and the imperfect packing of regenerator material. The double pipe regenerator is considered to have an effect of restraining the non-uniform flow. From the experimental results, the second stage cooling power of 1.67 W at 4.2 K and the first stage cooling power of 64.9 W at 50 K were achieved.

High-energy asymmetric supercapacitors based on free-standing hierarchical Co-Mo-S nanosheets with enhanced cycling stability.

PubMed

Balamurugan, Jayaraman; Li, Chao; Peera, Shaik Gouse; Kim, Nam Hoon; Lee, Joong Hee

2017-09-21

Layered transition metal sulfides (TMS) are emerging as advanced materials for energy storage and conversion applications. In this work, we report a facile and cost-effective anion exchange technique to fabricate a layered, multifaceted, free standing, ultra-thin ternary cobalt molybdenum sulfide nanosheet (Co-Mo-S NS) architecture grown on a 3D porous Ni foam substrate. The unique Co-Mo layered double hydroxides are first synthesized as precursors and consequently transformed into ultra-thin Co-Mo-S NS. When employed as an electrode for supercapacitors, the Co-Mo-S NS delivered an ultra-high specific capacitance of 2343 F g -1 at a current density of 1 mA cm -2 with tremendous rate capability and extraordinary cycling performance (96.6% capacitance retention after 20 000 cycles). Furthermore, assembled Co-Mo-S/nitrogen doped graphene nanosheets (NGNS) in an asymmetric supercapacitor (ASC) device delivered an excellent energy density of 89.6 Wh kg -1 , an amazing power density of 20.07 kW kg -1 , and superior cycling performance (86.8% capacitance retention after 50 000 cycles). Such exceptional electrochemical performance of Co-Mo-S NS is ascribed to the good electrical contact with the 3D Ni foam, ultra-high contact area with the electrolyte, and enhanced architectural softening during the charging/discharging process. It is expected that the fabricated, unique, ultra-thin Co-Mo-S NS have great potential for future energy storage devices.

The double layers in the plasma sheet boundary layer during magnetic reconnection

NASA Astrophysics Data System (ADS)

Guo, J.; Yu, B.

2014-11-01

We studied the evolutions of double layers which appear after the magnetic reconnection through two-dimensional electromagnetic particle-in-cell simulation. The simulation results show that the double layers are formed in the plasma sheet boundary layer after magnetic reconnection. At first, the double layers which have unipolar structures are formed. And then the double layers turn into bipolar structures, which will couple with another new weak bipolar structure. Thus a new double layer or tripolar structure comes into being. The double layers found in our work are about several ten Debye lengths, which accords with the observation results. It is suggested that the electron beam formed during the magnetic reconnection is responsible for the production of the double layers.

Effect of the co-spun anode functional layer on the performance of the direct-methane microtubular solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Meng, Xiuxia; Gong, Xun; Yin, Yimei; Yang, Naitao; Tan, Xiaoyao; Ma, Zi-Feng

2014-02-01

NiO-YSZ/porous YSZ (NiO-YSZ/p-YSZ) dual-layer hollow fibers have been fabricated by a co-spinning-sintering method, on which a dense YSZ films has been formed by a dip-coating and sintering process. A LSM-YSZ ink has been dip-coated on the dense YSZ films as cathode, while the Cu-CeO2 carbon-resistant catalyst has been impregnated in the p-YSZ layer to form double-anode supported micro tubular fuel cells (MT-SOFCs). The thickness of the Ni-YSZ layer, so called anode functional layer (AFL), is controlled from 74 μm to 13 μm by varying the spinning rates of the NiO-YSZ dopes. The maximum power density of an MT-SOFC, which is fabricated based on a thin co-spun AFL, reaches 566 mW cm-2 operated at 850 °C fed with dry methane, and is stably operated for 85 h without power declination.

Nanostructured antistatic and antireflective thin films made of indium tin oxide and silica over-coat layer

NASA Astrophysics Data System (ADS)

Cho, Young-Sang; Hong, Jeong-Jin; Yang, Seung-Man; Choi, Chul-Jin

2010-08-01

Stable dispersion of colloidal indium tin oxide nanoparticles was prepared by using indium tin oxide nanopowder, organic solvent, and suitable dispersants through attrition process. Various comminution parameters during the attrition step were studied to optimize the process for the stable dispersion of indium tin oxide sol. The transparent and conductive films were fabricated on glass substrate using the indium tin oxide sol by spin coating process. To obtain antireflective function, partially hydrolyzed alkyl silicate was deposited as over-coat layer on the pre-fabricated indium tin oxide film by spin coating technique. This double-layered structure of the nanostructured film was characterized by measuring the surface resistance and reflectance spectrum in the visible wavelength region. The final film structure was enough to satisfy the TCO regulations for EMI shielding purposes.

Contrast and Raman spectroscopy study of single- and few-layered charge density wave material: 2H-TaSe2

PubMed Central

Hajiyev, Parviz; Cong, Chunxiao; Qiu, Caiyu; Yu, Ting

2013-01-01

In this article, we report the first successful preparation of single- and few-layers of tantalum diselenide (2H-TaSe2) by mechanical exfoliation technique. Number of layers is confirmed by white light contrast spectroscopy and atomic force microscopy (AFM). Vibrational properties of the atomically thin layers of 2H-TaSe2 are characterized by micro-Raman spectroscopy. Room temperature Raman measurements demonstrate MoS2-like spectral features, which are reliable for thickness determination. E1g mode, usually forbidden in backscattering Raman configuration is observed in the supported TaSe2 layers while disappears in the suspended layers, suggesting that this mode may be enabled because of the symmetry breaking induced by the interaction with the substrate. A systematic in-situ low temperature Raman study, for the first time, reveals the existence of incommensurate charge density wave phase transition in single and double-layered 2H-TaSe2 as reflected by a sudden softening of the second-order broad Raman mode resulted from the strong electron-phonon coupling (Kohn anomaly). PMID:24005335

Vertical distribution of overpotentials and irreversible charge losses in lithium ion battery electrodes.

PubMed

Klink, Stefan; Schuhmann, Wolfgang; La Mantia, Fabio

2014-08-01

Porous lithium ion battery electrodes are characterized using a vertical distribution of cross-currents. In an appropriate simplification, this distribution can be described by a transmission line model (TLM) consisting of infinitely thin electrode layers. To investigate the vertical distribution of currents, overpotentials, and irreversible charge losses in a porous graphite electrode in situ, a multi-layered working electrode (MWE) was developed as the experimental analogue of a TLM. In this MWE, each layer is in ionic contact but electrically insulated from the other layers by a porous separator. It was found that the negative graphite electrodes get lithiated and delithiated stage-by-stage and layer-by-layer. Several mass-transport- as well as non-mass-transport-limited processes could be identified. Local current densities can reach double the average, especially on the outermost layer at the beginning of each intercalation stage. Furthermore, graphite particles close to the counter electrode act as "electrochemical sieve" reducing the impurities present in the electrolyte such as water. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low stress polysilicon film and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor)

2001-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin film may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films.

Low stress polysilicon film and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor)

2002-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin film may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films.

A thermal microprobe fabricated with wafer-stage processing

NASA Astrophysics Data System (ADS)

Zhang, Yongxia; Zhang, Yanwei; Blaser, Juliana; Sriram, T. S.; Enver, Ahsan; Marcus, R. B.

1998-05-01

A thermal microprobe has been designed and built for high resolution temperature sensing. The thermal sensor is a thin-film thermocouple junction at the tip of an atomic force microprobe (AFM) silicon probe needle. Only wafer-stage processing steps are used for the fabrication. For high resolution temperature sensing it is essential that the junction be confined to a short distance at the AFM tip. This confinement is achieved by a controlled photoresist coating process. Experiment prototypes have been made with an Au/Pd junction confined to within 0.5 μm of the tip, with the two metals separated elsewhere by a thin insulating oxide layer. Processing begins with double-polished, n-type, 4 in. diameter, 300-μm-thick silicon wafers. Atomically sharp probe tips are formed by a combination of dry and wet chemical etching, and oxidation sharpening. The metal layers are sputtering deposited and the cantilevers are released by a combination of KOH and dry etching. A resistively heated calibration device was made for temperature calibration of the thermal microprobe over the temperature range 25-110 °C. Over this range the thermal outputs of two microprobes are 4.5 and 5.6 μV/K and is linear. Thermal and topographical images are also obtained from a heated tungsten thin film fuse.

Near-field radiative transfer in spectrally tunable double-layer phonon-polaritonic metamaterials

NASA Astrophysics Data System (ADS)

Didari, Azadeh; Elçioğlu, Elif Begüm; Okutucu-Özyurt, Tuba; Mengüç, M. Pinar

2018-06-01

Understanding of near-field radiative transfer is crucial for many advanced applications such as nanoscale energy harvesting, nano-manufacturing, thermal imaging, and radiative cooling. Near-field radiative transfer has been shown to be dependent on the material and morphological characteristics of systems, the gap distances between structures, and their temperatures. Surface interactions of phononic materials in close proximity of each other has led to promising results for novel near-field radiative transfer applications. For systems involving thin films and small structures, as the dimension(s) through which the heat transfer takes place is/are on the order of sub-micrometers, it is important to identify the impacts of size-related parameters on the results. In this work, we investigated the impact of geometric design and characteristics in a double-layer metamaterial system made up of GaN, SiC, h-BN; all of which have potential importance in micro-and nano-technological systems. The numerical study is performed using the NF-RT-FDTD algorithm, which is a versatile method to study near-field thermal radiation performances of advanced configurations of materials, even with arbitrary shapes. We have systematically investigated the thin film thickness, the substrate material, and the nanostructured surfaces effects, and reported on the best combination of scenarios among the studied cases to obtain maximum enhancement of radiative heat transfer rate. The findings of this work may be used in design and fabrication of new corrugated surfaces for energy harvesting purposes.

Patch testing with thin-layer chromatograms of chamomile tea in patients allergic to sesquiterpene lactones.

PubMed

Lundh, Kerstin; Gruvberger, Birgitta; Möller, Halvor; Persson, Lena; Hindsén, Monica; Zimerson, Erik; Svensson, Ake; Bruze, Magnus

2007-10-01

Patients with contact allergy to sesquiterpene lactones (SLs) are usually hypersensitive to Asteraceae plant products such as herbal teas. The objective of this study was to show sensitizers in chamomile tea by patch testing with thin-layer chromatograms. Tea made from German chamomile was separated by thin-layer chromatography. Strips of the thin-layer chromatograms were used for patch testing SL-positive patients. 15 (43%) of 35 patients tested positively to 1 or more spots on the thin-layer chromatogram, with many individual reaction patterns. Patch testing with thin-layer chromatograms of German chamomile tea showed the presence of several allergens.

Bone regeneration in 3D printing bioactive ceramic scaffolds with improved tissue/material interface pore architecture in thin-wall bone defect.

PubMed

Shao, Huifeng; Ke, Xiurong; Liu, An; Sun, Miao; He, Yong; Yang, Xianyan; Fu, Jianzhong; Liu, Yanming; Zhang, Lei; Yang, Guojing; Xu, Sanzhong; Gou, Zhongru

2017-04-12

Three-dimensional (3D) printing bioactive ceramics have demonstrated alternative approaches to bone tissue repair, but an optimized materials system for improving the recruitment of host osteogenic cells into the bone defect and enhancing targeted repair of the thin-wall craniomaxillofacial defects remains elusive. Herein we systematically evaluated the role of side-wall pore architecture in the direct-ink-writing bioceramic scaffolds on mechanical properties and osteogenic capacity in rabbit calvarial defects. The pure calcium silicate (CSi) and dilute Mg-doped CSi (CSi-Mg6) scaffolds with different layer thickness and macropore sizes were prepared by varying the layer deposition mode from single-layer printing (SLP) to double-layer printing (DLP) and then by undergoing one-, or two-step sintering. It was found that the dilute Mg doping and/or two-step sintering schedule was especially beneficial for improving the compressive strength (∼25-104 MPa) and flexural strength (∼6-18 MPa) of the Ca-silicate scaffolds. The histological analysis for the calvarial bone specimens in vivo revealed that the SLP scaffolds had a high osteoconduction at the early stage (4 weeks) but the DLP scaffolds displayed a higher osteogenic capacity for a long time stage (8-12 weeks). Although the DLP CSi scaffolds displayed somewhat higher osteogenic capacity at 8 and 12 weeks, the DLP CSi-Mg6 scaffolds with excellent fracture resistance also showed appreciable new bone tissue ingrowth. These findings demonstrate that the side-wall pore architecture in 3D printed bioceramic scaffolds is required to optimize for bone repair in calvarial bone defects, and especially the Mg doping wollastontie is promising for 3D printing thin-wall porous scaffolds for craniomaxillofacial bone defect treatment.

Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer

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

Yang, Weiquan; Becker, Jacob; Liu, Shi

2014-05-28

This paper reports the proposal, design, and demonstration of ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer to optimize light management and minimize non-radiative recombination. According to our recently developed semi-analytical model, this design offers one of the highest potential achievable efficiencies for GaAs solar cells possessing typical non-radiative recombination rates found among commercially available III-V arsenide and phosphide materials. The structure of the demonstrated solar cells consists of an In{sub 0.49}Ga{sub 0.51}P/GaAs/In{sub 0.49}Ga{sub 0.51}P double-heterostructure PN junction with an ultra-thin 300 nm thick GaAs absorber, combined with a 5 μm thick Al{sub 0.52}In{sub 0.48}P layer with amore » textured as-grown surface coated with Au used as a reflective back scattering layer. The final devices were fabricated using a substrate-removal and flip-chip bonding process. Solar cells with a top metal contact coverage of 9.7%, and a MgF{sub 2}/ZnS anti-reflective coating demonstrated open-circuit voltages (V{sub oc}) up to 1.00 V, short-circuit current densities (J{sub sc}) up to 24.5 mA/cm{sup 2}, and power conversion efficiencies up to 19.1%; demonstrating the feasibility of this design approach. If a commonly used 2% metal grid coverage is assumed, the anticipated J{sub sc} and conversion efficiency of these devices are expected to reach 26.6 mA/cm{sup 2} and 20.7%, respectively.« less

Improving Osteoblast Response In Vitro by a Nanostructured Thin Film with Titanium Carbide and Titanium Oxides Clustered around Graphitic Carbon

PubMed Central

Longo, Giovanni; Ioannidu, Caterina Alexandra; Scotto d’Abusco, Anna; Superti, Fabiana; Misiano, Carlo; Zanoni, Robertino; Politi, Laura; Mazzola, Luca; Iosi, Francesca; Mura, Francesco; Scandurra, Roberto

2016-01-01

Introduction Recently, we introduced a new deposition method, based on Ion Plating Plasma Assisted technology, to coat titanium implants with a thin but hard nanostructured layer composed of titanium carbide and titanium oxides, clustered around graphitic carbon. The nanostructured layer has a double effect: protects the bulk titanium against the harsh conditions of biological tissues and in the same time has a stimulating action on osteoblasts. Results The aim of this work is to describe the biological effects of this layer on osteoblasts cultured in vitro. We demonstrate that the nanostructured layer causes an overexpression of many early genes correlated to proteins involved in bone turnover and an increase in the number of surface receptors for α3β1 integrin, talin, paxillin. Analyses at single-cell level, by scanning electron microscopy, atomic force microscopy, and single cell force spectroscopy, show how the proliferation, adhesion and spreading of cells cultured on coated titanium samples are higher than on uncoated titanium ones. Finally, the chemistry of the layer induces a better formation of blood clots and a higher number of adhered platelets, compared to the uncoated cases, and these are useful features to improve the speed of implant osseointegration. Conclusion In summary, the nanostructured TiC film, due to its physical and chemical properties, can be used to protect the implants and to improve their acceptance by the bone. PMID:27031101

Role of ion hydration for the differential capacitance of an electric double layer.

PubMed

Caetano, Daniel L Z; Bossa, Guilherme V; de Oliveira, Vinicius M; Brown, Matthew A; de Carvalho, Sidney J; May, Sylvio

2016-10-12

The influence of soft, hydration-mediated ion-ion and ion-surface interactions on the differential capacitance of an electric double layer is investigated using Monte Carlo simulations and compared to various mean-field models. We focus on a planar electrode surface at physiological concentration of monovalent ions in a uniform dielectric background. Hydration-mediated interactions are modeled on the basis of Yukawa potentials that add to the Coulomb and excluded volume interactions between ions. We present a mean-field model that includes hydration-mediated anion-anion, anion-cation, and cation-cation interactions of arbitrary strengths. In addition, finite ion sizes are accounted for through excluded volume interactions, described either on the basis of the Carnahan-Starling equation of state or using a lattice gas model. Both our Monte Carlo simulations and mean-field approaches predict a characteristic double-peak (the so-called camel shape) of the differential capacitance; its decrease reflects the packing of the counterions near the electrode surface. The presence of hydration-mediated ion-surface repulsion causes a thin charge-depleted region close to the surface, which is reminiscent of a Stern layer. We analyze the interplay between excluded volume and hydration-mediated interactions on the differential capacitance and demonstrate that for small surface charge density our mean-field model based on the Carnahan-Starling equation is able to capture the Monte Carlo simulation results. In contrast, for large surface charge density the mean-field approach based on the lattice gas model is preferable.

Low-power logic computing realized in a single electric-double-layer MoS2 transistor gated with polymer electrolyte

NASA Astrophysics Data System (ADS)

Guo, Junjie; Xie, Dingdong; Yang, Bingchu; Jiang, Jie

2018-06-01

Due to its mechanical flexibility, large bandgap and carrier mobility, atomically thin molybdenum disulphide (MoS2) has attracted widespread attention. However, it still lacks a facile route to fabricate a low-power high-performance logic gates/circuits before it gets the real application. Herein, we reported a facile and environment-friendly method to establish the low-power logic function in a single MoS2 field-effect transistor (FET) configuration gated with a polymer electrolyte. Such low-power and high-performance MoS2 FET can be implemented by using water-soluble polyvinyl alcohol (PVA) polymer as proton-conducting electric-double-layer (EDL) dielectric layer. It exhibited an ultra-low voltage (1.5 V) and a good performance with a high current on/off ratio (Ion/off) of 1 × 105, a large electron mobility (μ) of 47.5 cm2/V s, and a small subthreshold swing (S) of 0.26 V/dec, respectively. The inverter can be realized by using such a single MoS2 EDL FET with a gain of ∼4 at the operation voltage of only ∼1 V. Most importantly, the neuronal AND logic computing can be also demonstrated by using such a double-lateral-gate single MoS2 EDL transistor. These results show an effective step for future applications of 2D MoS2 FETs for integrated electronic engineering and low-energy environment-friendly green electronics.

Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer

DOEpatents

Carlson, David E.

1980-01-01

Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

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.

Maple prepared organic heterostructures for photovoltaic applications

NASA Astrophysics Data System (ADS)

Stanculescu, A.; Socol, M.; Socol, G.; Mihailescu, I. N.; Girtan, M.; Stanculescu, F.

2011-09-01

In this study, we present the deposition of ZnPc, Alq3, and PTCDA thin films using Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. We also report the realisation of multilayer structures, made by the successive application of MAPLE. The films have been characterized by spectroscopic (UV-VIS and Photoluminescence) and microscopic (SEM and AFM) methods, and the effect of different deposition conditions such as fluence, number of pulses, and target concentration on the properties has been analysed. This paper also presents some investigations on the electrical conduction in sandwich type structures ITO or Si/organic layer/Au or Cu and ITO/double organic layer/Cu, emphasising the dominant effect of the height of the energetic barriers at the inorganic/organic and organic/organic interfaces.

Carrier transport and sensitivity issues in heterojunction with intrinsic thin layer solar cells on N-type crystalline silicon: A computer simulation study

NASA Astrophysics Data System (ADS)

Rahmouni, M.; Datta, A.; Chatterjee, P.; Damon-Lacoste, J.; Ballif, C.; Roca i Cabarrocas, P.

2010-03-01

Heterojunction with intrinsic thin layer or "HIT" solar cells are considered favorable for large-scale manufacturing of solar modules, as they combine the high efficiency of crystalline silicon (c-Si) solar cells, with the low cost of amorphous silicon technology. In this article, based on experimental data published by Sanyo, we simulate the performance of a series of HIT cells on N-type crystalline silicon substrates with hydrogenated amorphous silicon (a-Si:H) emitter layers, to gain insight into carrier transport and the general functioning of these devices. Both single and double HIT structures are modeled, beginning with the initial Sanyo cells having low open circuit voltages but high fill factors, right up to double HIT cells exhibiting record values for both parameters. The one-dimensional numerical modeling program "Amorphous Semiconductor Device Modeling Program" has been used for this purpose. We show that the simulations can correctly reproduce the electrical characteristics and temperature dependence for a set of devices with varying I-layer thickness. Under standard AM1.5 illumination, we show that the transport is dominated by the diffusion mechanism, similar to conventional P/N homojunction solar cells, and tunneling is not required to describe the performance of state-of-the art devices. Also modeling has been used to study the sensitivity of N-c-Si HIT solar cell performance to various parameters. We find that the solar cell output is particularly sensitive to the defect states on the surface of the c-Si wafer facing the emitter, to the indium tin oxide/P-a-Si:H front contact barrier height and to the band gap and activation energy of the P-a-Si:H emitter, while the I-a-Si:H layer is necessary to achieve both high Voc and fill factor, as it passivates the defects on the surface of the c-Si wafer. Finally, we describe in detail for most parameters how they affect current transport and cell properties.

Ray-theory approach to electrical-double-layer interactions.

PubMed

Schnitzer, Ory

2015-02-01

A novel approach is presented for analyzing the double-layer interaction force between charged particles in electrolyte solution, in the limit where the Debye length is small compared with both interparticle separation and particle size. The method, developed here for two planar convex particles of otherwise arbitrary geometry, yields a simple asymptotic approximation limited to neither small zeta potentials nor the "close-proximity" assumption underlying Derjaguin's approximation. Starting from the nonlinear Poisson-Boltzmann formulation, boundary-layer solutions describing the thin diffuse-charge layers are asymptotically matched to a WKBJ expansion valid in the bulk, where the potential is exponentially small. The latter expansion describes the bulk potential as superposed contributions conveyed by "rays" emanating normally from the boundary layers. On a special curve generated by the centers of all circles maximally inscribed between the two particles, the bulk stress-associated with the ray contributions interacting nonlinearly-decays exponentially with distance from the center of the smallest of these circles. The force is then obtained by integrating the traction along this curve using Laplace's method. We illustrate the usefulness of our theory by comparing it, alongside Derjaguin's approximation, with numerical simulations in the case of two parallel cylinders at low potentials. By combining our result and Derjaguin's approximation, the interaction force is provided at arbitrary interparticle separations. Our theory can be generalized to arbitrary three-dimensional geometries, nonideal electrolyte models, and other physical scenarios where exponentially decaying fields give rise to forces.

Depositing bulk or micro-scale electrodes

DOEpatents

Shah, Kedar G.; Pannu, Satinderpall S.; Tolosa, Vanessa; Tooker, Angela C.; Sheth, Heeral J.; Felix, Sarah H.; Delima, Terri L.

2016-11-01

Thicker electrodes are provided on microelectronic device using thermo-compression bonding. A thin-film electrical conducting layer forms electrical conduits and bulk depositing provides an electrode layer on the thin-film electrical conducting layer. An insulating polymer layer encapsulates the electrically thin-film electrical conducting layer and the electrode layer. Some of the insulating layer is removed to expose the electrode layer.

Stress-Induced Resistive Switching in Pt/HfO2/Ti Devices

NASA Astrophysics Data System (ADS)

Zeevi, Gilad; Katsman, Alexander; Yaish, Yuval E.

2018-02-01

In the present work, we study the initial SET mechanism of resistive switching (RS) in Pt/HfO2/Ti devices under a static electrical stress and the RS mechanism under a bias sweeping mode with rates of 100 mV/s-300 mV/s. We characterize the thin HfO2 dielectric layer by x-ray photoelectron spectroscopy and x-ray diffraction. These findings show that the layer structure is stoichiometric and nanocrystalline with a crystal diameter of ˜ 14 Å. We measure the temporal dependence of the conductive filament growth at different temperatures and for various biases. Furthermore, these devices present stable bipolar resistive switching with a high-to-low resistive state (HRS/LRS) ratio of more than three orders of magnitude. Activation energy E RS ≈ 0.56 eV and drift current parameter V 0 ≈ 0.07 V were determined from the temporal dependence of the initial `SET' process, first HRS to LRS transition [for static electrical stress of V DS = (4.7-5.0 V)]. We analyze the results according to our model suggesting generation of double-charge oxygen vacancies at the anode and their diffusion across the dielectric layer. The double-charge vacancies transform to a single charge and then to neutral vacancies by capturing hot electrons, and form a conductive filament as soon as a critical neutral-vacancy cluster is formed across the dielectric layer.

Method for bonding thin film thermocouples to ceramics

DOEpatents

Kreider, Kenneth G.

1993-01-01

A method is provided for adhering a thin film metal thermocouple to a ceramic substrate used in an environment up to 700 degrees Centigrade, such as at a cylinder of an internal combustion engine. The method includes the steps of: depositing a thin layer of a reactive metal on a clean ceramic substrate; and depositing thin layers of platinum and a platinum-10% rhodium alloy forming the respective legs of the thermocouple on the reactive metal layer. The reactive metal layer serves as a bond coat between the thin noble metal thermocouple layers and the ceramic substrate. The thin layers of noble metal are in the range of 1-4 micrometers thick. Preferably, the ceramic substrate is selected from the group consisting of alumina and partially stabilized zirconia. Preferably, the thin layer of reactive metal is in the range of 0.015-0.030 micrometers (15-30 nanometers) thick. The preferred reactive metal is chromium. Other reactive metals may be titanium or zirconium. The thin layer of reactive metal may be deposited by sputtering in ultra high purity argon in a vacuum of approximately 2 milliTorr (0.3 Pascals).

Multi-layer assemblies with predetermined stress profile and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor); Phillips, Stephen M. (Inventor)

2003-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin films may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films. Multi-layer assemblies exhibiting selectively determinable overall bending moments are also disclosed. Selective production of overall bending moments in microstructures enables manufacture of such structures with a wide array of geometrical configurations.

Optical Properties of Hybrid Inorganic/Organic Thin Film Encapsulation Layers for Flexible Top-Emission Organic Light-Emitting Diodes.

PubMed

An, Jae Seok; Jang, Ha Jun; Park, Cheol Young; Youn, Hongseok; Lee, Jong Ho; Heo, Gi-Seok; Choi, Bum Ho; Lee, Choong Hun

2015-10-01

Inorganic/organic hybrid thin film encapsulation layers consist of a thin Al2O3 layer together with polymer material. We have investigated optical properties of thin film encapsulation layers for top-emission flexible organic light-emitting diodes. The transmittance of hybrid thin film encapsulation layers and the electroluminescent spectrum of organic light-emitting diodes that were passivated by hybrid organic/inorganic thin film encapsulation layers were also examined as a function of the thickness of inorganic Al203 and monomer layers. The number of interference peaks, their intensity, and their positions in the visible range can be controlled by varying the thickness of inorganic Al2O3 layer. On the other hand, changing the thickness of monomer layer had a negligible effect on the optical properties. We also verified that there is a trade-off between transparency in the visible range and the permeation of water vapor in hybrid thin film encapsulation layers. As the number of dyads decreased, optical transparency improved while the water vapor permeation barrier was degraded. Our study suggests that, in top-emission organic light-emitting diodes, the thickness of each thin film encapsulation layer, in particular that of the inorganic layer, and the number of dyads should be controlled for highly efficient top-emission flexible organic light-emitting diodes.

A strip-shield improves the efficiency of a solenoid coil in probes for high-field solid-state NMR of lossy biological samples.

PubMed

Wu, Chin H; Grant, Christopher V; Cook, Gabriel A; Park, Sang Ho; Opella, Stanley J

2009-09-01

A strip-shield inserted between a high inductance double-tuned solenoid coil and the glass tube containing the sample improves the efficiency of probes used for high-field solid-state NMR experiments on lossy aqueous samples of proteins and other biopolymers. A strip-shield is a coil liner consisting of thin copper strips layered on a PTFE (polytetrafluoroethylene) insulator. With lossy samples, the shift in tuning frequency is smaller, the reduction in Q, and RF-induced heating are all significantly reduced when the strip-shield is present. The performance of 800MHz (1)H/(15)N and (1)H/(13)C double-resonance probes is demonstrated on aqueous samples of membrane proteins in phospholipid bilayers.

Research on liquid impact forming technology of double-layered tubes

NASA Astrophysics Data System (ADS)

Sun, Changying; Liu, Jianwei; Yao, Xinqi; Huang, Beixing; Li, Yuhan

2018-03-01

A double-layered tube is widely used and developed in various fields because of its perfect comprehensive performance and design. With the advent of the era of a double-layered tube, the requirements for double layered tube forming quality, manufacturing cost and forming efficiency are getting higher, so forming methods of a double-layered tube are emerged in an endless stream, the forming methods of a double-layered tube have a great potential in the future. The liquid impact forming technology is a combination of stamping technology and hydroforming technology. Forming a double-layered tube has huge advantages in production cost, quality and efficiency.

Design of a 1200-V ultra-thin partial SOI LDMOS with n-type buried layer

NASA Astrophysics Data System (ADS)

Qiao, Ming; Wang, Yuru; Li, Yanfei; Zhang, Bo; Li, Zhaoji

2014-11-01

A novel 1200-V ultra-thin partial silicon-on-insulator (PSOI) lateral double-diffusion metal oxide semiconductor (LDMOS) with n-type buried (n-buried) layer (NBL PSOI LDMOS) is proposed in this paper. The new PSOI LDMOS features an n-buried layer underneath the n-type drift (n-drift) region close to the source side, providing a large conduction region for majority carriers and a silicon window to improve self-heating effect (SHE). A combination of uniform and linear variable doping (ULVD) profile is utilized in the n-drift region, which alleviates the inherent tradeoff between specific on-resistance (Ron,sp) and breakdown voltage (BV). With the n-drift region length of 80 μm, the NBL PSOI LDMOS obtains a high BV of 1243 V which is improved by around 105 V in comparison to the conventional SOI LDMOS with linear variable doping (LVD) profile for the n-drift region (LVD SOI LDMOS). Besides, the 1200-V NBL PSOI LDMOS has a lower maximum temperature (Tmax) of 333 K at a power (P) of 1 mW/μm which is reduced by around 61 K. Meanwhile, Ron,sp and Tmax of the NBL PSOI LDMOS are lower than those of the conventional LVD SOI LDMOS for a wide range of BV.

Channel length dependence of negative-bias-illumination-stress in amorphous-indium-gallium-zinc-oxide thin-film transistors

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

Um, Jae Gwang; Mativenga, Mallory; Jang, Jin, E-mail: jjang@khu.ac.kr

2015-06-21

We have investigated the dependence of Negative-Bias-illumination-Stress (NBIS) upon channel length, in amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The negative shift of the transfer characteristic associated with NBIS decreases for increasing channel length and is practically suppressed in devices with L = 100-μm. The effect is consistent with creation of donor defects, mainly in the channel regions adjacent to source and drain contacts. Excellent agreement with experiment has been obtained by an analytical treatment, approximating the distribution of donors in the active layer by a double exponential with characteristic length L{sub D} ∼ L{sub n} ∼ 10-μm, the latter being the electron diffusion length. The model alsomore » shows that a device with a non-uniform doping distribution along the active layer is in all equivalent, at low drain voltages, to a device with the same doping averaged over the active layer length. These results highlight a new aspect of the NBIS mechanism, that is, the dependence of the effect upon the relative magnitude of photogenerated holes and electrons, which is controlled by the device potential/band profile. They may also provide the basis for device design solutions to minimize NBIS.« less

Langmuir probe measurements of double-layers in a pulsed discharge

NASA Technical Reports Server (NTRS)

Levine, J. S.; Crawford, F. W.

1980-01-01

Langmuir probe measurements were carried out which confirm the occurrence of double-layers in an argon positive column. Pulsing the discharge current permitted probe measurements to be performed in the presence of the double-layer. Supplementary evidence, obtained from DC and pulsed discharges, indicated that the double-layers formed in the two modes of operation were similar. The double-layers observed were weak and stable; their relation to other classes of double-layers are discussed, and directions for future work are suggested.

Dry-spray deposition of TiO2 for a flexible dye-sensitized solar cell (DSSC) using a nanoparticle deposition system (NPDS).

PubMed

Kim, Min-Saeng; Chun, Doo-Man; Choi, Jung-Oh; Lee, Jong-Cheon; Kim, Yang Hee; Kim, Kwang-Su; Lee, Caroline Sunyong; Ahn, Sung-Hoon

2012-04-01

TiO2 powders were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates for application to the photoelectrode of a dye-sensitized solar cell (DSSC). In the conventional DSSC manufacturing process, a semiconductor oxide such as TiO2 powder requires a sintering process at higher temperature than the glass transition temperature (T(g)) of polymers, and thus utilization of flexible polymer substrates in DSSC research has been constrained. To overcome this restriction related to sintering, we used a nanoparticle deposition system (NPDS) that could produce a thin coating layer through a dry-spray method under atmospheric pressure at room temperature. The powder was sprayed through a slit-type nozzle having a 0.4 x 10 mm2 rectangular outlet. In order to determine the deposited TiO2 thickness, five kinds of TiO2 layered specimens were prepared, where the specimens have single and double layer structures. Deposited powders on the ITO coated PET substrates were observed using FE-SEM and a scan profiler The thicker TiO2 photoelectrode with a DSSC having a double layer structure showed higher energy efficiency than the single layer case. The highest fabricated flexible DSSC displayed a short circuit current density J(sc) = 1.99 mA cm(-2), open circuit voltage V(oc) = 0.71 V, and energy efficiency eta = 0.94%. These results demonstrate the possibility of utilizing the dry-spray method to fabricate a TiO2 layer on flexible polymer substrates at room temperature under atmospheric pressure.

Wireless Power Transmission to Organic Light Emitting Diode Lighting Panel with Magnetically Coupled Resonator

NASA Astrophysics Data System (ADS)

Kim, Yong-Hae; Han, Jun-Han; Kang, Seung-Youl; Cheon, Sanghoon; Lee, Myung-Lae; Ahn, Seong-Deok; Zyung, Taehyoung; Lee, Jeong-Ik; Moon, Jaehyun; Chu, Hye Yong

2012-09-01

We are successful to lit the organic light emitting diode (OLED) lighting panel through the magnetically coupled wireless power transmission technology. For the wireless power transmission, we used the operation frequency 932 kHz, specially designed double spiral type transmitter, small and thin receiver on the four layered printed circuit board, and schottky diodes for the full bridge rectifier. Our white OLED is a hybrid type, in which phosphorescent and fluorescent organics are used together to generate stable white color. The total efficiency of power transmission is around 72%.

Short-period (AlAs)(GaAs) superlattice lasers grown by molecular beam epitaxy

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

Blood, P.; Fletcher, E.D.; Foxon, C.T.

1988-07-25

We have used short-period all-binary (AlAs)(GaAs) superlattices with layers as thin as three monolayers to synthesize the barrier and cladding regions of GaAs quantum well lasers grown by molecular beam epitaxy. By studying the threshold current of single- and double-well devices as a function of cavity length and temperature, we conclude that the optical scattering losses are very low, that the gain-current characteristics are similar to alloy barrier devices, and that there is evidence for current leakage by recombination in the barriers.

Composite polymeric film and method for its use in installing a very-thin polymeric film in a device

DOEpatents

Duchane, D.V.; Barthell, B.L.

1982-04-26

A composite polymeric film and a method for its use in forming and installing a very thin (< 10 ..mu..m) polymeric film are disclosed. The composite film consists of a thin film layer and a backing layer. The backing layer is soluble in a solvent in which the thin film layer is not soluble. In accordance with the method, the composite film is installed in a device in the same position in which it is sought to finally emplace the thin film. The backing layer is then selectiely dissolved in the solvent to leave the insoluble thin film layer as an unbacked film. The method permits a very thin film to e successfully installed in devices where the fragility of the film would preclude handling and installation by conventional methods.

Composite polymeric film and method for its use in installing a very thin polymeric film in a device

DOEpatents

Duchane, David V.; Barthell, Barry L.

1984-01-01

A composite polymeric film and a method for its use in forming and installing a very thin (<10 .mu.m) polymeric film are disclosed. The composite film consists of a thin film layer and a backing layer. The backing layer is soluble in a solvent in which the thin film layer is not soluble. In accordance with the method, the composite film is installed in a device in the same position in which it is sought to finally emplace the thin film. The backing layer is then selectively dissolved in the solvent to leave the insoluble thin film layer as an unbacked film. The method permits a very thin film to be successfully installed in devices where the fragility of the film would preclude handling and installation by conventional methods.

Maximum screening fields of superconducting multilayer structures

DOE PAGES

Gurevich, Alex

2015-01-07

Here, it is shown that a multilayer comprised of alternating thin superconducting and insulating layers on a thick substrate can fully screen the applied magnetic field exceeding the superheating fields H s of both the superconducting layers and the substrate, the maximum Meissner field is achieved at an optimum multilayer thickness. For instance, a dirty layer of thickness ~0.1 μm at the Nb surface could increase H s ≃ 240 mT of a clean Nb up to H s ≃ 290 mT. Optimized multilayers of Nb 3Sn, NbN, some of the iron pnictides, or alloyed Nb deposited onto the surfacemore » of the Nb resonator cavities could potentially double the rf breakdown field, pushing the peak accelerating electric fields above 100 MV/m while protecting the cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.« less

Excitation of hybridized Dirac plasmon polaritons and transition radiation in multi-layer graphene traversed by a fast charged particle

NASA Astrophysics Data System (ADS)

Akbari, Kamran; Mišković, Zoran L.; Segui, Silvina; Gervasoni, Juana L.; Arista, Néstor R.

2018-06-01

We analyze the energy loss channels for a fast charged particle traversing a multi-layer graphene (MLG) structure with N layers under normal incidence. Focusing on a terahertz (THz) range of frequencies, and assuming equally doped graphene layers with a large enough separation d between them to neglect interlayer electron hopping, we use the Drude model for two-dimensional conductivity of each layer to describe hybridization of graphene’s Dirac plasmon polaritons (DPPs). Performing a layer decomposition of ohmic energy losses, which include excitation of hybridized DPPs (HDPPs), we have found for N = 3 that the middle HDPP eigenfrequency is not excited in the middle layer due to symmetry constraint, whereas the excitation of the lowest HDPP eigenfrequency produces a Fano resonance in the graphene layer that is first traversed by the charged particle. While the angular distribution of transition radiation emitted in the far field region also shows asymmetry with respect to the traversal order by the incident charged particle at supra-THz frequencies, the integrated radiative energy loss is surprisingly independent of both d and N for N ≤ 5, which is explained by a dominant role of the outer graphene layers in transition radiation. We have further found that the integrated ohmic energy loss in optically thin MLG scales as ∝1/N at sub-THz frequencies, which is explained by exposing the role of dissipative processes in graphene at low frequencies. Finally, prominent peaks are observed at supra-THz frequencies in the integrated ohmic energy loss for MLG structures that are not optically thin. The magnitude of those peaks is found to scale with N for N ≥ 2, while their shape and position replicate the peak in a double-layer graphene (N = 2), which is explained by arguing that plasmon hybridization in such MLG structures is dominated by electromagnetic interaction between the nearest-neighbor graphene layers.

Excitation of hybridized Dirac plasmon polaritons and transition radiation in multi-layer graphene traversed by a fast charged particle.

PubMed

Akbari, Kamran; Mišković, Zoran L; Segui, Silvina; Gervasoni, Juana L; Arista, Néstor R

2018-06-01

We analyze the energy loss channels for a fast charged particle traversing a multi-layer graphene (MLG) structure with N layers under normal incidence. Focusing on a terahertz (THz) range of frequencies, and assuming equally doped graphene layers with a large enough separation d between them to neglect interlayer electron hopping, we use the Drude model for two-dimensional conductivity of each layer to describe hybridization of graphene's Dirac plasmon polaritons (DPPs). Performing a layer decomposition of ohmic energy losses, which include excitation of hybridized DPPs (HDPPs), we have found for N = 3 that the middle HDPP eigenfrequency is not excited in the middle layer due to symmetry constraint, whereas the excitation of the lowest HDPP eigenfrequency produces a Fano resonance in the graphene layer that is first traversed by the charged particle. While the angular distribution of transition radiation emitted in the far field region also shows asymmetry with respect to the traversal order by the incident charged particle at supra-THz frequencies, the integrated radiative energy loss is surprisingly independent of both d and N for N ≤ 5, which is explained by a dominant role of the outer graphene layers in transition radiation. We have further found that the integrated ohmic energy loss in optically thin MLG scales as ∝1/N at sub-THz frequencies, which is explained by exposing the role of dissipative processes in graphene at low frequencies. Finally, prominent peaks are observed at supra-THz frequencies in the integrated ohmic energy loss for MLG structures that are not optically thin. The magnitude of those peaks is found to scale with N for N ≥ 2, while their shape and position replicate the peak in a double-layer graphene (N = 2), which is explained by arguing that plasmon hybridization in such MLG structures is dominated by electromagnetic interaction between the nearest-neighbor graphene layers.

Measurements of Induced-Charge Electroosmotic Flow Around a Metallic Rod

NASA Astrophysics Data System (ADS)

Beskok, Ali; Canpolat, Cetin

2012-11-01

A cylindrical gold-coated stainless steel rod was positioned at the center of a straight microchannel connecting two fluid reservoirs on either end. The microchannel was filled with 1 mM KCl containing 0.5 micron diameter carboxylate-modified spherical particles. Induced-charge electro-osmotic (ICEO) flow occurred around the metallic rod under a sinusoidal AC electric field applied using two platinum electrodes. The ICEO flows around the metallic rod were measured using micro particle image velocimetry (micro-PIV) technique as functions of the AC electric field strength and frequency. The present study provides experimental data about ICEO flow in the weakly nonlinear limit of thin double layers, in which, the charging dynamics of the double layer cannot be presented analytically. Flow around the rod is quadrupolar, driving liquid towards the rod along the electric field and forcing it away from the rod in the direction perpendicular to the imposed electric field. The measured ICEO flow velocity is proportional to the square of the electric field strength, and depends on the applied AC frequency.

The impact of electrostatic correlations on Dielectrophoresis of Non-conducting Particles

NASA Astrophysics Data System (ADS)

Alidoosti, Elaheh; Zhao, Hui

2017-11-01

The dipole moment of a charged, dielectric, spherical particle under the influence of a uniform alternating electric field is computed theoretically and numerically by solving the modified continuum Poisson-Nernst-Planck (PNP) equations accounting for ion-ion electrostatic correlations that is important at concentrated electrolytes (Phys. Rev. Lett. 106, 2011). The dependence on the frequency, zeta potential, electrostatic correlation lengths, and double layer thickness is thoroughly investigated. In the limit of thin double layers, we carry out asymptotic analysis to develop simple models which are in good agreement with the modified PNP model. Our results suggest that the electrostatic correlations have a complicated impact on the dipole moment. As the electrostatic correlations length increases, the dipole moment decreases, initially, reach a minimum, and then increases since the surface conduction first decreases and then increases due to the ion-ion correlations. The modified PNP model can improve the theoretical predictions particularly at low frequencies where the simple model can't qualitatively predict the dipole moment. This work was supported, in part, by NIH R15GM116039.

Hydrophobic forces in the foam films stabilized by sodium dodecyl sulfate: effect of electrolyte.

PubMed

Wang, Liguang; Yoon, Roe-Hoan

2004-12-21

Further studies of the hydrophobic force in foam films were carried out, including the effect of added inorganic electrolyte. We used a thin film balance of Scheludko-Exerowa type to obtain the disjoining pressure isotherms of the foam films stabilized by 10(-4) M sodium dodecyl sulfate in varying concentrations of sodium chloride. The results were compared with the disjoining pressure isotherms predicted from the extended Derjaguin-Landau-Verwey-Overbeek theory, which considers contributions from hydrophobic force in addition to those from double layer and van der Waals dispersion forces. The double layer forces were calculated from the surface potentials (psi s) obtained using the Gibbs adsorption equation and corrected for the counterion binding effect, while the dispersion forces were calculated using the Hamaker constant (A232) of 3.7 x 10(-20) J. The hydrophobic forces were calculated from the equilibrium film thickness as described previously. The predicted disjoining pressure isotherms were in good agreement with the experimental ones. It was found that the hydrophobic force is dampened substantially by the added electrolyte.

OLED emission zone measurement with high accuracy

NASA Astrophysics Data System (ADS)

Danz, N.; MacCiarnain, R.; Michaelis, D.; Wehlus, T.; Rausch, A. F.; Wächter, C. A.; Reusch, T. C. G.

2013-09-01

Highly efficient state of the art organic light-emitting diodes (OLED) comprise thin emitting layers with thicknesses in the order of 10 nm. The spatial distribution of the photon generation rate, i.e. the profile of the emission zone, inside these layers is of interest for both device efficiency analysis and characterization of charge recombination processes. It can be accessed experimentally by reverse simulation of far-field emission pattern measurements. Such a far-field pattern is the sum of individual emission patterns associated with the corresponding positions inside the active layer. Based on rigorous electromagnetic theory the relation between far-field pattern and emission zone is modeled as a linear problem. This enables a mathematical analysis to be applied to the cases of single and double emitting layers in the OLED stack as well as to pattern measurements in air or inside the substrate. From the results, guidelines for optimum emitter - cathode separation and for selecting the best experimental approach are obtained. Limits for the maximum spatial resolution can be derived.

Multi-layered, chemically bonded lithium-ion and lithium/air batteries

DOEpatents

Narula, Chaitanya Kumar; Nanda, Jagjit; Bischoff, Brian L; Bhave, Ramesh R

2014-05-13

Disclosed are multilayer, porous, thin-layered lithium-ion batteries that include an inorganic separator as a thin layer that is chemically bonded to surfaces of positive and negative electrode layers. Thus, in such disclosed lithium-ion batteries, the electrodes and separator are made to form non-discrete (i.e., integral) thin layers. Also disclosed are methods of fabricating integrally connected, thin, multilayer lithium batteries including lithium-ion and lithium/air batteries.

Double layers and circuits in astrophysics

NASA Technical Reports Server (NTRS)

Alfven, Hannes

1986-01-01

As the rate of energy release in a double layer with voltage delta V is P approx I delta V, a double layer must be treated as a part of a circuit which delivers the current I. As neither double layer nor circuit can be derived from magnetofluid models of a plasma, such models are useless for treating energy transfer by means of double layers. They must be replaced by particle models and circuit theory. A simple circuit is suggested which is applied to the energizing of auroral particles, to solar flares, and to intergalactic double radio sources. Application to the heliospheric current systems leads to the prediction of two double layers on the Sun's axis which may give radiations detectable from Earth. Double layers in space should be classified as a new type of celestial object (one example is the double radio sources). It is tentatively suggested in X-ray and Gamma-ray bursts may be due to exploding double layers (although annihilation is an alternative energy source). A study of how a number of the most used textbooks in astrophysics treat important concepts like double layers, critical velocity, pinch effects and circuits is made.

Fabrication of low-temperature solid oxide fuel cells with a nanothin protective layer by atomic layer deposition

PubMed Central

2013-01-01

Anode aluminum oxide-supported thin-film fuel cells having a sub-500-nm-thick bilayered electrolyte comprising a gadolinium-doped ceria (GDC) layer and an yttria-stabilized zirconia (YSZ) layer were fabricated and electrochemically characterized in order to investigate the effect of the YSZ protective layer. The highly dense and thin YSZ layer acted as a blockage against electron and oxygen permeation between the anode and GDC electrolyte. Dense GDC and YSZ thin films were fabricated using radio frequency sputtering and atomic layer deposition techniques, respectively. The resulting bilayered thin-film fuel cell generated a significantly higher open circuit voltage of approximately 1.07 V compared with a thin-film fuel cell with a single-layered GDC electrolyte (approximately 0.3 V). PMID:23342963

Simulation of plasma double-layer structures

NASA Technical Reports Server (NTRS)

Borovsky, J. E.; Joyce, G.

1982-01-01

Electrostatic plasma double layers are numerically simulated by means of a magnetized 2 1/2 dimensional particle in cell method. The investigation of planar double layers indicates that these one dimensional potential structures are susceptible to periodic disruption by instabilities in the low potential plasmas. Only a slight increase in the double layer thickness with an increase in its obliqueness to the magnetic field is observed. Weak magnetization results in the double layer electric field alignment of accelerated particles and strong magnetization results in their magnetic field alignment. The numerical simulations of spatially periodic two dimensional double layers also exhibit cyclical instability. A morphological invariance in two dimensional double layers with respect to the degree of magnetization implies that the potential structures scale with Debye lengths rather than with gyroradii. Electron beam excited electrostatic electron cyclotron waves and (ion beam driven) solitary waves are present in the plasmas adjacent to the double layers.

Thin film electronic devices with conductive and transparent gas and moisture permeation barriers

DOEpatents

Simpson, Lin Jay

2015-07-28

Thin film electronic devices (or stacks integrated with a substrate) that include a permeation barrier formed of a thin layer of metal that provides a light transmitting and electrically conductive layer, wherein the electrical conductive layer is formed on a surface of the substrate or device layer such as a transparent conducting material layer with pin holes or defects caused by manufacturing and the thin layer of metal is deposited on the conductive layer and formed from a self-healing metal that forms self-terminating oxides. A permeation plug or block is formed in or adjacent to the thin film of metal at or proximate to the pin holes to block further permeation of contaminants through the pin holes.

Large area polysilicon films with predetermined stress characteristics and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor); Phillips, Stephen M. (Inventor)

2002-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin films may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films. Multi-layer assemblies exhibiting selectively determinable overall bending moments are also disclosed. Selective production of overall bending moments in microstructures enables manufacture of such structures with a wide array of geometrical configurations.

Comparison Between Navier-Stokes and Thin-Layer Computations for Separated Supersonic Flow

NASA Technical Reports Server (NTRS)

Degani, David; Steger, Joseph L.

1983-01-01

In the numerical simulation of high Reynolds-number flow, one can frequently supply only enough grid points to resolve the viscous terms in a thin layer. As a consequence, a body-or stream-aligned coordinate system is frequently used and viscous terms in this direction are discarded. It is argued that these terms cannot be resolved and computational efficiency is gained by their neglect. Dropping the streamwise viscous terms in this manner has been termed the thin-layer approximation. The thin-layer concept is an old one, and similar viscous terms are dropped, for example, in parabolized Navier-Stokes schemes. However, such schemes also make additional assumptions so that the equations can be marched in space, and such a restriction is not usually imposed on a thin-layer model. The thin-layer approximation can be justified in much the same way as the boundary-layer approximation; it requires, therefore, a body-or stream-aligned coordinate and a high Reynolds number. Unlike the boundary-layer approximation, the same equations are used throughout, so there is no matching problem. Furthermore, the normal momentum equation is not simplified and the convection terms are not one-sided differenced for marching. Consequently, the thin-layer equations are numerically well behaved at separation and require no special treatment there. Nevertheless, the thin-layer approximation receives criticism. It has been suggested that the approximation is invalid at separation and, more recently, that it is inadequate for unsteady transonic flow. Although previous comparisons between the thin-layer and Navier-Stokes equations have been made, these comparisons have not been adequately documented.

Multilayer composites and manufacture of same

DOEpatents

Holesinger, Terry G.; Jia, Quanxi

2006-02-07

The present invention is directed towards a process of depositing multilayer thin films, disk-shaped targets for deposition of multilayer thin films by a pulsed laser or pulsed electron beam deposition process, where the disk-shaped targets include at least two segments with differing compositions, and a multilayer thin film structure having alternating layers of a first composition and a second composition, a pair of the alternating layers defining a bi-layer wherein the thin film structure includes at least 20 bi-layers per micron of thin film such that an individual bi-layer has a thickness of less than about 100 nanometers.

Exploration and engineering of physical properties in high-quality Sr2CrReO6 epitaxial films

NASA Astrophysics Data System (ADS)

Lucy, Jeremy Matthew

Double perovskites have proven to be highly interesting materials, particularly in the past two decades, with many materials in this family exhibiting strong correlations. These materials are some of many novel complex oxides with potential spintronics application. Sr2CrReO6, in particular, is a double perovskite with one of the highest Curie temperatures of its class (> 620 K in bulk and ~510-600 K in thin films), as well as high spin polarization, ferrimagnetic behavior, and semiconducting properties. This dissertation covers recent work in exploring and tuning physical properties in epitaxial films of Sr2CrReO6. It starts by providing a background for the field of spintronics and double perovskites, bulk and thin film synthesis of Sr2CrReO6, and standard and specialized characterization techniques utilized in both university and national laboratories, and then provides reports of work on Sr2CrReO6 epitaxial films. Examples of exploration and engineering of properties of Sr2CrReO 6 include: (1) tuning of electrical resistivity, such as at T= 7 K by a factor of 18,000%, via control of oxygen partial pressure during film growth; (2) enhancement of interfacial double perovskite ordering, demonstrated with high-angle annular dark-field scanning transmission electron microscopy, via the use of double perovskite buffer layer substrates; (3) measurement of magnetization suppression near film/substrate interfaces via polarized neutron reflectometry, which reveals a reduction of thickness (from 5.6 nm to 3.6 nm) of the magnetically suppressed interface region due to buffer layer enhancement; (4) strain tunability of atomic spin and orbital moments of Cr, Re, and O atoms probed with x-ray magnetic circular dichroism, which demonstrates ferrimagnetic behavior and reveals important magnetic contributions of the oxygen sites (~0.02 muB/site); (5) strain tunability of large magnetocrystalline anisotropy via applied epitaxial strain, revealing anisotropy fields of up to 10s of tesla; and (6) depth-resolved synchrotron x-ray studies of correlated magnetic and structural relaxation in a thick relaxing film. The utilized techniques and demonstrated results for Sr2CrReO6 will hopefully benefit researchers of complex oxide materials and perhaps stimulate further work on this and other related materials.

In vivo thickness and birefringence determination of the human retinal nerve fiber layer using polarization-sensitive optical coherence tomography.

PubMed

Cense, B; Chen, T C; de Boer, J F

2006-01-01

Thinning of the retinal nerve fiber layer and changes in retinal nerve fiber layer birefringence may both precede clinically detectable glaucomatous vision loss. We present in vivo thickness and depth-resolved birefringence measurements of the human retinal nerve fiber layer (RNFL) by use of polarization-sensitive optical coherence tomography (PS-OCT). Using a fiber-based PS-OCT setup real-time images of the human retina in vivo were recorded, co-registered with retinal video images of the location of PS-OCT scans. PS-OCT scans around the optic nerve head (ONH) of two healthy young volunteers were made using 10 concentric circles of increasing radius. Both the mean retinal nerve fiber layer thickness and mean retinal nerve fiber birefringence for each of 48 sectors on a circle were determined. The retinal nerve fiber layer thickness and birefringence varied as a function of sector around the ONH. Measured double pass phase retardation per unit depth values around the ONH range between 0.10 and 0.35 degrees/microm. The retinal nerve fiber layer becomes thinner with increasing distance from the ONH. In contrast, the birefringence does not vary significantly with increasing distance from the ONH.

Composite carbon foam electrode

DOEpatents

Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

1997-01-01

Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

A thin film approach for SiC-derived graphene as an on-chip electrode for supercapacitors

NASA Astrophysics Data System (ADS)

Ahmed, Mohsin; Khawaja, Mohamad; Notarianni, Marco; Wang, Bei; Goding, Dayle; Gupta, Bharati; Boeckl, John J.; Takshi, Arash; Motta, Nunzio; Saddow, Stephen E.; Iacopi, Francesca

2015-10-01

We designed a nickel-assisted process to obtain graphene with sheet resistance as low as 80 Ω square-1 from silicon carbide films on Si wafers with highly enhanced surface area. The silicon carbide film acts as both a template and source of graphitic carbon, while, simultaneously, the nickel induces porosity on the surface of the film by forming silicides during the annealing process which are subsequently removed. As stand-alone electrodes in supercapacitors, these transfer-free graphene-on-chip samples show a typical double-layer supercapacitive behaviour with gravimetric capacitance of up to 65 F g-1. This work is the first attempt to produce graphene with high surface area from silicon carbide thin films for energy storage at the wafer-level and may open numerous opportunities for on-chip integrated energy storage applications.

A thin film approach for SiC-derived graphene as an on-chip electrode for supercapacitors.

PubMed

Ahmed, Mohsin; Khawaja, Mohamad; Notarianni, Marco; Wang, Bei; Goding, Dayle; Gupta, Bharati; Boeckl, John J; Takshi, Arash; Motta, Nunzio; Saddow, Stephen E; Iacopi, Francesca

2015-10-30

We designed a nickel-assisted process to obtain graphene with sheet resistance as low as 80 Ω square(-1) from silicon carbide films on Si wafers with highly enhanced surface area. The silicon carbide film acts as both a template and source of graphitic carbon, while, simultaneously, the nickel induces porosity on the surface of the film by forming silicides during the annealing process which are subsequently removed. As stand-alone electrodes in supercapacitors, these transfer-free graphene-on-chip samples show a typical double-layer supercapacitive behaviour with gravimetric capacitance of up to 65 F g(-1). This work is the first attempt to produce graphene with high surface area from silicon carbide thin films for energy storage at the wafer-level and may open numerous opportunities for on-chip integrated energy storage applications.

Electroosmosis of viscoelastic fluids over charge modulated surfaces in narrow confinements

NASA Astrophysics Data System (ADS)

Ghosh, Uddipta; Chakraborty, Suman

2015-06-01

In the present work, we attempt to analyze the electroosmotic flow of a viscoelastic fluid, following quasi-linear constitutive behavior, over charge modulated surfaces in narrow confinements. We obtain analytical solutions for the flow field for thin electrical double layer (EDL) limit through asymptotic analysis for small Deborah numbers. We show that a combination of matched and regular asymptotic expansion is needed for the thin EDL limit. We subsequently determine the modified Smoluchowski slip velocity for viscoelastic fluids and show that the quasi-linear nature of the constitutive behavior adds to the periodicity of the flow. We also obtain the net throughput in the channel and demonstrate its relative decrement as compared to that of a Newtonian fluid. Our results may have potential implications towards augmenting microfluidic mixing by exploiting electrokinetic transport of viscoelastic fluids over charge modulated surfaces.

Multilayer thin film design as far ultraviolet polarizers

NASA Technical Reports Server (NTRS)

Kim, Jongmin; Zukic, Muamer; Torr, Douglas T.

1993-01-01

We use a concept of induced transmission and absorption to design multilayer thin film reflection polarizers in the FUV region. We achieve high s-polarization reflectance and a high degree of polarization by means of a MgF2/Al/MgF2 three layer structure on an opaque thick film of aluminum as the substrate. For convenience they are designed at a 45 deg angle of incidence. For example, our polarizer designed for the Lyman-alpha line (121.6 nm) has 88.67 percent reflectance for the s-polarization case, and 1.21 percent for the p-polarization case, with a degree of polarization of 97.31 percent. If we make a double surface polarizer with this design, it will have a degree of polarization of 99.96 percent and s-polarization throughput of 78.62 percent.

Ordered organic-organic multilayer growth

DOEpatents

Forrest, Stephen R.; Lunt, Richard R.

2016-04-05

An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

Ordered organic-organic multilayer growth

DOEpatents

Forrest, Stephen R; Lunt, Richard R

2015-01-13

An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

Electrosorption capacitance of nanostructured carbon-based materials.

PubMed

Hou, Chia-Hung; Liang, Chengdu; Yiacoumi, Sotira; Dai, Sheng; Tsouris, Costas

2006-10-01

The fundamental mechanism of electrosorption of ions developing a double layer inside nanopores was studied via a combination of experimental and theoretical studies. A novel graphitized-carbon monolithic material has proven to be a good electrical double-layer capacitor that can be applied in the separation of ions from aqueous solutions. An extended electrical double-layer model indicated that the pore size distribution plays a key role in determining the double-layer capacitance in an electrosorption process. Because of the occurrence of double-layer overlapping in narrow pores, mesopores and micropores make significantly different contributions to the double-layer capacitance. Mesopores show good electrochemical accessibility. Micropores present a slow mass transfer of ions and a considerable loss of double-layer capacitance, associated with a shallow potential distribution inside pores. The formation of the diffuse layer inside the micropores determines the magnitude of the double-layer capacitance at low electrolyte concentrations and at conditions close to the point of zero charge of the material. The effect of the double-layer overlapping on the electrosorption capacitance can be reduced by increasing the pore size, electrolyte concentration, and applied potential. The results are relevant to water deionization.

Parallel electric fields in extragalactic jets - Double layers and anomalous resistivity in symbiotic relationships

NASA Technical Reports Server (NTRS)

Borovsky, J. E.

1986-01-01

After examining the properties of Coulomb-collision resistivity, anomalous (collective) resistivity, and double layers, a hybrid anomalous-resistivity/double-layer model is introduced. In this model, beam-driven waves on both sides of a double layer provide electrostatic plasma-wave turbulence that greatly reduces the mobility of charged particles. These regions then act to hold open a density cavity within which the double layer resides. In the double layer, electrical energy is dissipated with 100 percent efficiency into high-energy particles, creating conditions optimal for the collective emission of polarized radio waves.

Nano-crystalline thin and nano-particulate thick TiO{sub 2} layer: Cost effective sequential deposition and study on dye sensitized solar cell characteristics

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

Das, P.; Sengupta, D.; CSIR-Central Mechanical Engineering Research Institute, Academy of Scientific and Innovative Research

Highlights: • Thin TiO{sub 2} layer is deposited on conducting substrate using sol–gel based dip coating. • TiO{sub 2} nano-particles are synthesized using hydrothermal route. • Thick TiO{sub 2} particulate layer is deposited on prepared thin layer. • Dye sensitized solar cells are made using thin and thick layer based photo-anode. • Introduction of thin layer in particulate photo-anode improves the cell efficiency. - Abstract: A compact thin TiO{sub 2} passivation layer is introduced between the mesoporous TiO{sub 2} nano-particulate layer and the conducting glass substrate to prepare photo-anode for dye-sensitized solar cell (DSSC). In order to understand the effectmore » of passivation layer, other two DSSCs are also developed separately using TiO{sub 2} nano-particulate and compact thin film based photo-anodes. Nano-particles are prepared using hydrothermal synthesis route and the compact passivation layer is prepared by simply dip coating the precursor sol prepared through wet chemical route. The TiO{sub 2} compact layer and the nano-particles are characterised in terms of their micro-structural features and phase formation behavior. It is found that introduction of a compact TiO{sub 2} layer in between the mesoporous TiO{sub 2} nano-particulate layer and the conducting substrate improves the solar to electric conversion efficiency of the fabricated cell. The dense thin passivation layer is supposed to enhance the photo-excited electron transfer and prevent the recombination of photo-excited electrons.« less

Electrokinetic transport of rigid macroions in the thin double layer limit: a boundary element approach.

PubMed

Allison, Stuart A; Xin, Yao

2005-08-15

A boundary element (BE) procedure is developed to numerically calculate the electrophoretic mobility of highly charged, rigid model macroions in the thin double layer regime based on the continuum primitive model. The procedure is based on that of O'Brien (R.W. O'Brien, J. Colloid Interface Sci. 92 (1983) 204). The advantage of the present procedure over existing BE methodologies that are applicable to rigid model macroions in general (S. Allison, Macromolecules 29 (1996) 7391) is that computationally time consuming integrations over a large number of volume elements that surround the model particle are completely avoided. The procedure is tested by comparing the mobilities derived from it with independent theory of the mobility of spheres of radius a in a salt solution with Debye-Huckel screening parameter, kappa. The procedure is shown to yield accurate mobilities provided (kappa)a exceeds approximately 50. The methodology is most relevant to model macroions of mean linear dimension, L, with 1000>(kappa)L>100 and reduced absolute zeta potential (q|zeta|/k(B)T) greater than 1.0. The procedure is then applied to the compact form of high molecular weight, duplex DNA that is formed in the presence of the trivalent counterion, spermidine, under low salt conditions. For T4 DNA (166,000 base pairs), the compact form is modeled as a sphere (diameter=600 nm) and as a toroid (largest linear dimension=600 nm). In order to reconcile experimental and model mobilities, approximately 95% of the DNA phosphates must be neutralized by bound counterions. This interpretation, based on electrokinetics, is consistent with independent studies.

Ionic liquid versus SiO 2 gated a-IGZO thin film transistors: A direct comparison

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

Pudasaini, Pushpa Raj; Noh, Joo Hyon; Wong, Anthony T.

Here, ionic liquid gated field effect transistors have been extensively studied due to their low operation voltage, ease of processing and the realization of high electric fields at low bias voltages. Here, we report ionic liquid (IL) gated thin film transistors (TFTs) based on amorphous Indium Gallium Zinc Oxide (a-IGZO) active layers and directly compare the characteristics with a standard SiO 2 gated device. The transport measurements of the top IL gated device revealed the n-channel property of the IGZO thin film with a current ON/OFF ratio ~10 5, a promising field effect mobility of 14.20 cm 2V –1s –1,more » and a threshold voltage of 0.5 V. Comparable measurements on the bottom SiO2 gate insulator revealed a current ON/OFF ratio >108, a field effect mobility of 13.89 cm 2V –1s –1 and a threshold voltage of 2.5 V. Furthermore, temperature-dependent measurements revealed that the ionic liquid electric double layer can be “frozen-in” by cooling below the glass transition temperature with an applied electrical bias. Positive and negative freezing bias locks-in the IGZO TFT “ON” and “OFF” state, respectively, which could lead to new switching and possibly non-volatile memory applications.« less

Ionic liquid versus SiO 2 gated a-IGZO thin film transistors: A direct comparison

DOE PAGES

Pudasaini, Pushpa Raj; Noh, Joo Hyon; Wong, Anthony T.; ...

2015-08-12

Here, ionic liquid gated field effect transistors have been extensively studied due to their low operation voltage, ease of processing and the realization of high electric fields at low bias voltages. Here, we report ionic liquid (IL) gated thin film transistors (TFTs) based on amorphous Indium Gallium Zinc Oxide (a-IGZO) active layers and directly compare the characteristics with a standard SiO 2 gated device. The transport measurements of the top IL gated device revealed the n-channel property of the IGZO thin film with a current ON/OFF ratio ~10 5, a promising field effect mobility of 14.20 cm 2V –1s –1,more » and a threshold voltage of 0.5 V. Comparable measurements on the bottom SiO2 gate insulator revealed a current ON/OFF ratio >108, a field effect mobility of 13.89 cm 2V –1s –1 and a threshold voltage of 2.5 V. Furthermore, temperature-dependent measurements revealed that the ionic liquid electric double layer can be “frozen-in” by cooling below the glass transition temperature with an applied electrical bias. Positive and negative freezing bias locks-in the IGZO TFT “ON” and “OFF” state, respectively, which could lead to new switching and possibly non-volatile memory applications.« less

An Electrochemical Experiment Using an Optically Transparent Thin Layer Electrode

ERIC Educational Resources Information Center

DeAngelis, Thomas P.; Heineman, William R.

1976-01-01

Describes a unified experiment in which an optically transparent thin layer electrode is used to illustrate the techniques of thin layer electrochemistry, cyclic voltammetry, controlled potential coulometry, and spectroelectrochemistry. (MLH)

Rectenna that converts infrared radiation to electrical energy

DOEpatents

Davids, Paul; Peters, David W.

2016-09-06

Technologies pertaining to converting infrared (IR) radiation to DC energy are described herein. In a general embodiment, a rectenna comprises a conductive layer. A thin insulator layer is formed on the conductive layer, and a nanoantenna is formed on the thin insulator layer. The thin insulator layer acts as a tunnel junction of a tunnel diode.

Surface studies on superhydrophobic and oleophobic polydimethylsiloxane-silica nanocomposite coating system

NASA Astrophysics Data System (ADS)

Basu, Bharathibai J.; Dinesh Kumar, V.; Anandan, C.

2012-11-01

Superhydrophobic and oleophobic polydimethylsiloxane (PDMS)-silica nanocomposite double layer coating was fabricated by applying a thin layer of low surface energy fluoroalkyl silane (FAS) as topcoat. The coatings exhibited WCA of 158-160° and stable oleophobic property with oil CA of 79°. The surface morphology was characterized by field emission scanning electron microscopy (FESEM) and surface chemical composition was determined by energy dispersive X-ray spectrometery (EDX) and X-ray photoelectron spectroscopy (XPS). FESEM images of the coatings showed micro-nano binary structure. The improved oleophobicity was attributed to the combined effect of low surface energy of FAS and roughness created by the random distribution of silica aggregates. This is a facile, cost-effective method to obtain superhydrophobic and oleophobic surfaces on larger area of various substrates.

GaN membrane MSM ultraviolet photodetectors

NASA Astrophysics Data System (ADS)

Muller, A.; Konstantinidis, G.; Kostopoulos, A.; Dragoman, M.; Neculoiu, D.; Androulidaki, M.; Kayambaki, M.; Vasilache, D.; Buiculescu, C.; Petrini, I.

2006-12-01

GaN exhibits unique physical properties, which make this material very attractive for wide range of applications and among them ultraviolet detection. For the first time a MSM type UV photodetector structure was manufactured on a 2.2 μm. thick GaN membrane obtained using micromachining techniques. The low unintentionally doped GaN layer structure was grown by MOCVD on high resistivity (ρ>10kΩcm) <111> oriented silicon wafers, 500μm thick. The epitaxially grown layers include a thin AlN layer in order to reduce the stress in the GaN layer and avoid cracking. Conventional contact lithography, e-gun Ni/Au (10nm /200nm) evaporation and lift-off techniques were used to define the interdigitated Schottky metalization on the top of the wafer. Ten digits with a width of 1μm and a length of 100μm were defined for each electrode. The distance between the digits was also 1μm. After the backside lapping of the wafer to a thickness of approximately 150μm, a 400nm thick Al layer was patterned and deposited on the backside, to be used as mask for the selective reactive ion etching of silicon. The backside mask, for the membrane formation, was patterned using double side alignment techniques and silicon was etched down to the 2.2μm thin GaN layer using SF 6 plasma. A very low dark current (30ρA at 3V) was obtained. Optical responsivity measurements were performed at 1.5V. A maximum responsivity of 18mA/W was obtained at a wavelength of 370nm. This value is very good and can be further improved using transparent contacts for the interdigitated structure.

Cadmium-free junction fabrication process for CuInSe.sub.2 thin film solar cells

DOEpatents

Ramanathan, Kannan V.; Contreras, Miguel A.; Bhattacharya, Raghu N.; Keane, James; Noufi, Rommel

1999-01-01

The present invention provides an economical, simple, dry and controllable semiconductor layer junction forming process to make cadmium free high efficiency photovoltaic cells having a first layer comprised primarily of copper indium diselenide having a thin doped copper indium diselenide n-type region, generated by thermal diffusion with a group II(b) element such as zinc, and a halide, such as chlorine, and a second layer comprised of a conventional zinc oxide bilayer. A photovoltaic device according the present invention includes a first thin film layer of semiconductor material formed primarily from copper indium diselenide. Doping of the copper indium diselenide with zinc chloride is accomplished using either a zinc chloride solution or a solid zinc chloride material. Thermal diffusion of zinc chloride into the copper indium diselenide upper region creates the thin n-type copper indium diselenide surface. A second thin film layer of semiconductor material comprising zinc oxide is then applied in two layers. The first layer comprises a thin layer of high resistivity zinc oxide. The second relatively thick layer of zinc oxide is doped to exhibit low resistivity.

Method for double-sided processing of thin film transistors

DOEpatents

Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.; Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang

2008-04-08

This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

Design of a portable dose rate detector based on a double Geiger-Mueller counter

NASA Astrophysics Data System (ADS)

Wang, Peng; Tang, Xiao-Bin; Gong, Pin; Huang, Xi; Wen, Liang-Sheng; Han, Zhen-Yang; He, Jian-Ping

2018-01-01

A portable dose rate detector was designed to monitor radioactive pollution and radioactive environments. The portable dose detector can measure background radiation levels (0.1 μSv/h) to nuclear accident radiation levels (>10 Sv/h). Both automatic switch technology of a double Geiger-Mueller counter and time-to-count technology were adopted to broaden the measurement range of the instrument. Global positioning systems and the 3G telecommunication protocol were installed to prevent radiation damage to the human body. In addition, the Monte Carlo N-Particle code was used to design the thin layer of metal for energy compensation, which was used to flatten energy response The portable dose rate detector has been calibrated by the standard radiation field method, and it can be used alone or in combination with additional radiation detectors.

The threshold strength of laminar ceramics utilizing molar volume changes and porosity

NASA Astrophysics Data System (ADS)

Pontin, Michael Gene

It has been shown that uniformly spaced thin compressive layers within a ceramic body can arrest the propagation of an otherwise catastrophic crack, producing a threshold strength: a strength below which the probability of failure is zero. Previous work has shown that the threshold strength increases with both the magnitude of the compressive stress and the fracture toughness of the thin layer material, and finite element analysis predicts that the threshold strength can be further increased when the elastic modulus of the compressive layer is much smaller than the thicker layer. The current work describes several new approaches to increase the threshold strength of a laminar ceramic system. The initial method utilized a molar volume expansion within the thin layers, produced by the tetragonal-to-monoclinic phase transformation of unstabilized zirconia during cooling, in order to produce large compressive stresses within the thin layers. High threshold strengths were measured for this system, but they remained relatively constant as the zirconia content was increased. It was determined that microcracking produced during the transformation reduced the magnitude of the compressive stresses, but may also have served to reduce the modulus of the thin compressive layer, providing an additional strengthening mechanism. The second approach studied the addition of porosity to reduce the elastic modulus of the thin compressive layers. A new processing method was created and analyzed, in which thick layers of the laminate were fabricated by tape-casting, and then dip-coated into a slurry, containing rice starch, to create thin porous compressive layers upon densification. The effects of porosity on the residual compressive stress, elastic modulus, and fracture toughness of the thin layers were measured and calculated, and it was found that the elastic modulus mismatch between the thin and thick layers produced a large strengthening effect for volume fractions of porosity below a critical level. Specimens with greater volume fractions of porosity exhibited complete crack arrest, typically followed by non-catastrophic failure, as cracks initiating in adjacent thick layers coalesced by cracking or delamination along the thin porous layers.

Characterization of Cu buffer layers for growth of L10-FeNi thin films

NASA Astrophysics Data System (ADS)

Mizuguchi, M.; Sekiya, S.; Takanashi, K.

2010-05-01

A Cu(001) layer was fabricated on a Au(001) layer to investigate the use of Cu as a buffer layer for growing L10-FeNi thin films. The epitaxial growth of a Cu buffer layer was observed using reflection high-energy electron diffraction. The flatness of the layer improved drastically with an increase in the substrate temperature although the layer was an alloy (AuCu3). An FeNi thin film was epitaxially grown on the AuCu3 buffer layer by alternate monatomic layer deposition and the formation of an L10-FeNi ordered alloy was expected. The AuCu3 buffer layer is thus a promising candidate material for the growth of L10-FeNi thin films.

Ceramic Composite Thin Films

NASA Technical Reports Server (NTRS)

Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor); Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor)

2013-01-01

A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

Thin-layer voltammetry of soluble species on screen-printed electrodes: proof of concept.

PubMed

Botasini, S; Martí, A C; Méndez, E

2016-10-17

Thin-layer diffusion conditions were accomplished on screen-printed electrodes by placing a controlled-weight onto the cast solution and allowing for its natural spreading. The restricted diffusive conditions were assessed by cyclic voltammetry at low voltage scan rates and electrochemical impedance spectroscopy. The relationship between the weight exerted over the drop and the thin-layer thickness achieved was determined, in such a way that the simple experimental set-up designed for this work could be developed into a commercial device with variable control of the thin-layer conditions. The experimental results obtained resemble those reported for the voltammetric features of electroactive soluble species employing electrodes modified with carbon nanotubes or graphene layers, suggesting that the attainment of the benefits reported for these nanomaterials could be done simply by forcing the solution to spread over the screen-printed electrodic system to form a thin layer solution. The advantages of thin-layer voltammetry in the kinetic characterization of quasi-reversible and irreversible processes are highlighted.

A model for thin layer formation by delayed particle settling at sharp density gradients

NASA Astrophysics Data System (ADS)

Prairie, Jennifer C.; White, Brian L.

2017-02-01

Thin layers - regions where plankton or particles accumulate vertically on scales of a few meters or less - are common in coastal waters, and have important implications for both trophic dynamics and carbon cycling. These features can form by a variety of biological and physical mechanisms, including localized growth, shear-thinning, and directed swimming. An additional mechanism may result in the formation of thin layers of marine aggregates, which have been shown to decrease their settling velocity when passing through sharp density gradients, a behavior termed delayed settling. Here, we apply a simple vertical advection-diffusion model to predict the properties of aggregate thin layers formed by this process. We assume a constant vertical flux of particles from the surface, which is parameterized by observations from laboratory experiments with marine aggregates. The formation, maintenance, and shape of the layers are described in relation to non-dimensional numbers that depend on environmental conditions and particle settling properties. In particular, model results demonstrate layer intensity and sharpness both increase with higher Péclet number (Pe), that is, under conditions with weaker mixing relative to layer formation. Similarly, more intense and sharper layers are found when the delayed settling behavior of aggregates is characterized by a lower velocity minimum. The model also predicts layers that are vertically asymmetric and highly "peaky" when compared with a Gaussian distribution, features often seen in thin layers in natural environments. Lastly, by comparing model predictions with observations of thin layers in the field, we are able to gain some insight into the applicability of delayed settling as a thin layer formation mechanism in different environmental conditions.

TUBEWALL: a passive solar thermo-siphoning, field-fabricated, water storage wall system

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

Moore, F.; Hemker, P.

1980-01-01

The basic component of TUBEWALL is a water-filled thin-wall cylindrical tube with an insulating foam vertical partition insert that divides the inside of the tube into a thin collector water compartment (solar side) and a larger storage water compartment (room side). The two compartments are connected at the top and bottom by means of circulation holes in the foam partition. When the sun strikes the solar side of the tube, the thin layer of collector water is heated, thermosiphons through the top opening in the partition into the larger storage compartment on the room side, and is replaced with coolmore » water drawn from the bottom of the storage through the bottom hole in the partition. Night back-siphonage is prevented by a thin flap valve over the top circulation hole. The tubes may by used between wall studs having a low-cost fiberglass/tedlar double glazing. The tubes can be covered on the room side with drywall and heat transferred to the living space by indirect radiation, and either natural air convection through top and bottom vent slots or by fan. Alternatively, the tubes can be left exposed for direct radiation.« less

Thin Film Transistors On Plastic Substrates

DOEpatents

Carey, Paul G.; Smith, Patrick M.; Sigmon, Thomas W.; Aceves, Randy C.

2004-01-20

A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The silicon based thin film transistor produced by the process includes a low temperature substrate incapable of withstanding sustained processing temperatures greater than about 250.degree. C., an insulating layer on the substrate, a layer of silicon on the insulating layer having sections of doped silicon, undoped silicon, and poly-silicon, a gate dielectric layer on the layer of silicon, a layer of gate metal on the dielectric layer, a layer of oxide on sections of the layer of silicon and the layer of gate metal, and metal contacts on sections of the layer of silicon and layer of gate metal defining source, gate, and drain contacts, and interconnects.

Room temperature rubbing for few-layer two-dimensional thin flakes directly on flexible polymer substrates

PubMed Central

Yu, Yan; Jiang, Shenglin; Zhou, Wenli; Miao, Xiangshui; Zeng, Yike; Zhang, Guangzu; Liu, Sisi

2013-01-01

The functional layers of few-layer two-dimensional (2-D) thin flakes on flexible polymers for stretchable applications have attracted much interest. However, most fabrication methods are “indirect” processes that require transfer steps. Moreover, previously reported “transfer-free” methods are only suitable for graphene and not for other few-layer 2-D thin flakes. Here, a friction based room temperature rubbing method is proposed for fabricating different types of few-layer 2-D thin flakes (graphene, hexagonal boron nitride (h-BN), molybdenum disulphide (MoS2), and tungsten disulphide (WS2)) on flexible polymer substrates. Commercial 2-D raw materials (graphite, h-BN, MoS2, and WS2) that contain thousands of atom layers were used. After several minutes, different types of few-layer 2-D thin flakes were fabricated directly on the flexible polymer substrates by rubbing procedures at room temperature and without any transfer step. These few-layer 2-D thin flakes strongly adhere to the flexible polymer substrates. This strong adhesion is beneficial for future applications. PMID:24045289

Polymer thin film as coating layer to prevent corrosion of metal/metal oxide film

NASA Astrophysics Data System (ADS)

Sarkar, Suman; Kundu, Sarathi

2018-04-01

Thin film of polymer is used as coating layer and the corrosion of metal/metal oxide layer is studied with the variation of the thickness of the coating layer. The thin layer of polystyrene is fabricated using spin coating method on copper oxide (CuO) film which is deposited on glass substrate using DC magnetron sputtering technique. Thickness of the polystyrene and the CuO layers are determined using X-ray reflectivity (XRR) technique. CuO thin films coated with the polystyrene layer are exposed to acetic acid (2.5 v/v% aqueous CH3COOH solution) environments and are subsequently analyzed using UV-Vis spectroscopy and atomic force microscopy (AFM). Surface morphology of the film before and after interaction with the acidic environment is determined using AFM. Results obtained from the XRR and UV-Vis spectroscopy confirm that the thin film of polystyrene acts as an anticorrosion coating layer and the strength of the coating depends upon the polymer layer thickness at a constant acid concentration.

Layer-by-layer strippable Ag multilayer films fabricated by modular assembly.

PubMed

Li, Yan; Chen, Xiaoyan; Li, Qianqian; Song, Kai; Wang, Shihui; Chen, Xiaoyan; Zhang, Kai; Fu, Yu; Jiao, Yong-Hua; Sun, Ting; Liu, Fu-Chun; Han, En-Hou

2014-01-21

We have developed a new method to fabricate multilayer films, which uses prepared thin films as modular blocks and transfer as operation mode to build up multilayer structures. In order to distinguish it from the in situ fabrication manner, this method is called modular assembly in this study. On the basis of such concept, we have fabricated a multilayer film using the silver mirror film as the modular block and poly(lactic acid) as the transfer tool. Due to the special double-layer structure of the silver mirror film, the resulting multilayer film had a well-defined stratified architecture with alternate porous/compact layers. As a consequence of the distinct structure, the interaction between the adjacent layers was so weak that the multilayer film could be layer-by-layer stripped. In addition, the top layer in the film could provide an effective protection on the morphology and surface property of the underlying layers. This suggests that if the surface of the film was deteriorated, the top layer could be peeled off and the freshly exposed surface would still maintain the original function. The successful preparation of the layer-by-layer strippable silver multilayer demonstrates that modular assembly is a feasible and effective method to build up multilayer films capable of creating novel and attractive micro/nanostructures, having great potential in the fabrication of nanodevices and coatings.

The scaling of oblique plasma double layers

NASA Technical Reports Server (NTRS)

Borovsky, J. E.

1983-01-01

Strong oblique plasma double layers are investigated using three methods, i.e., electrostatic particle-in-cell simulations, numerical solutions to the Poisson-Vlasov equations, and analytical approximations to the Poisson-Vlasov equations. The solutions to the Poisson-Vlasov equations and numerical simulations show that strong oblique double layers scale in terms of Debye lengths. For very large potential jumps, theory and numerical solutions indicate that all effects of the magnetic field vanish and the oblique double layers follow the same scaling relation as the field-aligned double layers.

Nonenzymatic detection of glucose using BaCuO2 thin layer

NASA Astrophysics Data System (ADS)

Ito, Takeshi; Asada, Tsuyoshi; Asai, Naoto; Shimizu, Tomohiro; Shingubara, Shoso

2017-01-01

A BaCuO2 thin layer was deposited on a glassy carbon electrode and used for the direct oxidation of glucose. The crystalline, electrochemical, and physicochemical properties that depend on the deposition temperature and deposition time were studied. X-ray diffraction (XRD) analysis showed that the thin layer was amorphous even at 400 °C. The current density of the glucose oxidation using the thin layer deposited at 200 °C was higher than those at other deposition temperatures. Under this condition, the current density increased with the glucose concentration and deposition time. These results indicate that a BaCuO2 thin layer has potential for measuring the blood glucose level without enzymes.

Mesoscopic Oxide Double Layer as Electron Specific Contact for Highly Efficient and UV Stable Perovskite Photovoltaics.

PubMed

Tavakoli, Mohammad Mahdi; Giordano, Fabrizio; Zakeeruddin, Shaik Mohammed; Grätzel, Michael

2018-04-11

The solar to electric power conversion efficiency (PCE) of perovskite solar cells (PSCs) has recently reached 22.7%, exceeding that of competing thin film photovoltaics and the market leader polycrystalline silicon. Further augmentation of the PCE toward the Shockley-Queisser limit of 33.5% warrants suppression of radiationless carrier recombination by judicious engineering of the interface between the light harvesting perovskite and the charge carrier extraction layers. Here, we introduce a mesoscopic oxide double layer as electron selective contact consisting of a scaffold of TiO 2 nanoparticles covered by a thin film of SnO 2 , either in amorphous (a-SnO 2 ), crystalline (c-SnO 2 ), or nanocrystalline (quantum dot) form (SnO 2 -NC). We find that the band gap of a-SnO 2 is larger than that of the crystalline (tetragonal) polymorph leading to a corresponding lift in its conduction band edge energy which aligns it perfectly with the conduction band edge of both the triple cation perovskite and the TiO 2 scaffold. This enables very fast electron extraction from the light perovskite, suppressing the notorious hysteresis in the current-voltage ( J-V) curves and retarding nonradiative charge carrier recombination. As a result, we gain a remarkable 170 mV in open circuit photovoltage ( V oc ) by replacing the crystalline SnO 2 by an amorphous phase. Because of the quantum size effect, the band gap of our SnO 2 -NC particles is larger than that of bulk SnO 2 causing their conduction band edge to shift also to a higher energy thereby increasing the V oc . However, for SnO 2 -NC there remains a barrier for electron injection into the TiO 2 scaffold decreasing the fill factor of the device and lowering the PCE. Introducing the a-SnO 2 coated mp-TiO 2 scaffold as electron extraction layer not only increases the V oc and PEC of the solar cells but also render them resistant to UV light which forebodes well for outdoor deployment of these new PSC architectures.

Methods for making thin layers of crystalline materials

DOEpatents

Lagally, Max G; Paskiewicz, Deborah M; Tanto, Boy

2013-07-23

Methods for making growth templates for the epitaxial growth of compound semiconductors and other materials are provided. The growth templates are thin layers of single-crystalline materials that are themselves grown epitaxially on a substrate that includes a thin layer of sacrificial material. The thin layer of sacrificial material, which creates a coherent strain in the single-crystalline material as it is grown thereon, includes one or more suspended sections and one or more supported sections.

Transparent and flexible high-performance supercapacitors based on single-walled carbon nanotube films

NASA Astrophysics Data System (ADS)

Kanninen, Petri; Dang Luong, Nguyen; Hoang Sinh, Le; Anoshkin, Ilya V.; Tsapenko, Alexey; Seppälä, Jukka; Nasibulin, Albert G.; Kallio, Tanja

2016-06-01

Transparent and flexible energy storage devices have garnered great interest due to their suitability for display, sensor and photovoltaic applications. In this paper, we report the application of aerosol synthesized and dry deposited single-walled carbon nanotube (SWCNT) thin films as electrodes for an electrochemical double-layer capacitor (EDLC). SWCNT films exhibit extremely large specific capacitance (178 F g-1 or 552 μF cm-2), high optical transparency (92%) and stability for 10 000 charge/discharge cycles. A transparent and flexible EDLC prototype is constructed with a polyethylene casing and a gel electrolyte.

Numerical modelling of a fibre reflection filter based on a metal–dielectric diffraction structure with an increased optical damage threshold

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

Terentyev, V S; Simonov, V A

2016-02-28

Numerical modelling demonstrates the possibility of fabricating an all-fibre multibeam two-mirror reflection interferometer based on a metal–dielectric diffraction structure in its front mirror. The calculations were performed using eigenmodes of a double-clad single-mode fibre. The calculation results indicate that, using a metallic layer in the structure of the front mirror of such an interferometer and a diffraction effect, one can reduce the Ohmic loss by a factor of several tens in comparison with a continuous thin metallic film. (laser crystals and braggg ratings)

Cell and Particle Interactions and Aggregation During Electrophoretic Motion

NASA Technical Reports Server (NTRS)

Wang, Hua; Zeng, Shulin; Loewenberg, Michael; Todd, Paul; Davis, Robert H.

1996-01-01

The stability and pairwise aggregation rates of small spherical particles under the collective effects of buoyancy-driven motion and electrophoretic migration are analyzed. The particles are assumed to be non-Brownian, with thin double-layers and different zeta potentials. The particle aggregation rates may be enhanced or reduced, respectively, by parallel and antiparallel alignments of the buoyancy-driven and electrophoretic velocities. For antiparallel alignments, with the buoyancy-driven relative velocity exceeding the electrophoretic relative velocity between two widely-separated particles, there is a 'collision-forbidden region' in parameter space due to hydrodynamic interactions; thus, the suspension becomes stable against aggregation.

Soft x-ray imaging with incoherent sources

NASA Astrophysics Data System (ADS)

Wachulak, P.; Torrisi, A.; Ayele, M.; Bartnik, A.; Czwartos, J.; Wegrzyński, Ł.; Fok, T.; Parkman, T.; Vondrová, Š.; Turnová, J.; Odstrcil, M.; Fiedorowicz, H.

2017-05-01

In this work we present experimental, compact desk-top SXR microscope, the EUV microscope which is at this stage a technology demonstrator, and finally, the SXR contact microscope. The systems are based on laser-plasma EUV and SXR sources, employing a double stream gas puff target. The EUV and SXR full field microscopes, operating at 13.8 nm and 2.88 nm wavelengths, respectively, are capable of imaging nanostructures with a sub-50 nm spatial resolution with relatively short (seconds) exposure times. The SXR contact microscope operates in the "water-window" spectral range, to produce an imprint of the internal structure of the sample in a thin layer of SXR light sensitive photoresist. Applications of such desk-top EUV and SXR microscopes for studies of variety of different samples - test objects for resolution assessment and other objects such as carbon membranes, DNA plasmid samples, organic and inorganic thin layers, diatoms, algae and carcinoma cells, are also presented. Details about the sources, the microscopes as well as the imaging results for various objects will be presented and discussed. The development of such compact imaging systems may be important to the new research related to biological, material science and nanotechnology applications.

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.

Photon induced non-linear quantized double layer charging in quaternary semiconducting quantum dots.

PubMed

Nair, Vishnu; Ananthoju, Balakrishna; Mohapatra, Jeotikanta; Aslam, M

2018-03-15

Room temperature quantized double layer charging was observed in 2 nm Cu 2 ZnSnS 4 (CZTS) quantum dots. In addition to this we observed a distinct non-linearity in the quantized double layer charging arising from UV light modulation of double layer. UV light irradiation resulted in a 26% increase in the integral capacitance at the semiconductor-dielectric (CZTS-oleylamine) interface of the quantum dot without any change in its core size suggesting that the cause be photocapacitive. The increasing charge separation at the semiconductor-dielectric interface due to highly stable and mobile photogenerated carriers cause larger electrostatic forces between the quantum dot and electrolyte leading to an enhanced double layer. This idea was supported by a decrease in the differential capacitance possible due to an enhanced double layer. Furthermore the UV illumination enhanced double layer gives us an AC excitation dependent differential double layer capacitance which confirms that the charging process is non-linear. This ultimately illustrates the utility of a colloidal quantum dot-electrolyte interface as a non-linear photocapacitor. Copyright © 2017 Elsevier Inc. All rights reserved.

Tests on Double Layer Metalization

NASA Technical Reports Server (NTRS)

Woo, D. S.

1983-01-01

28 page report describes experiments in fabrication of integrated circuits with double-layer metalization. Double-layer metalization requires much less silicon "real estate" and allows more flexibility in placement of circuit elements than does single-layer metalization.

Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

NASA Astrophysics Data System (ADS)

Gupta, Sanju; Price, Carson

2015-10-01

Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO)1, (PPy/ErGO)1, (PAni/GO)1 and (PPy/GO)1. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, Cs, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent Cs of ≥350 F g-1 as compared with constituents (˜70 F g-1) at discharge current density of 0.3 A g-1 that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (re)activity of surface ion adsorption sites density at solid/liquid interface.

Improvement in temperature dependence and dielectric tunability properties of PbZr0.52Ti0.48O3 thin films using Ba(Mg1/3Ta2/3)O3 buffer layer

NASA Astrophysics Data System (ADS)

Wu, Zhi; Zhou, Jing; Chen, Wen; Shen, Jie; Yang, Huimin; Zhang, Shisai; Liu, Yueli

2016-12-01

In this paper, Pb(Zr0.52Ti0.48)O3 (PZT) thin films were prepared via sol-gel method. The effects of Ba(Mg1/3Ta2/3)O3 (BMT) buffer layer on the temperature dependence and dielectric tunability properties of PZT thin films were studied. As the thickness of BMT buffer layer increases, the tan δ and tunability of PZT thin films decrease while tunability still maintains above 10%. This result shows that BMT buffer layer can improve the dielectric tunability properties of PZT thin films. Furthermore, the temperature coefficient of the dielectric constant decreases from 2333.4 to 906.9 ppm/°C with the thickness of BMT buffer layer increasing in the range from 25 to 205 °C, indicating that BMT buffer layer can improve the temperature stability of PZT thin films. Therefore, BMT buffer layer plays a critical role in improving temperature dependence and dielectric tunability properties of PbZr0.52Ti0.48O3 thin films.

Breakthrough to Non-Vacuum Deposition of Single-Crystal, Ultra-Thin, Homogeneous Nanoparticle Layers: A Better Alternative to Chemical Bath Deposition and Atomic Layer Deposition

PubMed Central

Liao, Yu-Kuang; Liu, Yung-Tsung; Hsieh, Dan-Hua; Shen, Tien-Lin; Hsieh, Ming-Yang; Tzou, An-Jye; Chen, Shih-Chen; Tsai, Yu-Lin; Lin, Wei-Sheng; Chan, Sheng-Wen; Shen, Yen-Ping; Cheng, Shun-Jen; Chen, Chyong-Hua; Wu, Kaung-Hsiung; Chen, Hao-Ming; Kuo, Shou-Yi; Charlton, Martin D. B.; Hsieh, Tung-Po; Kuo, Hao-Chung

2017-01-01

Most thin-film techniques require a multiple vacuum process, and cannot produce high-coverage continuous thin films with the thickness of a few nanometers on rough surfaces. We present a new ”paradigm shift” non-vacuum process to deposit high-quality, ultra-thin, single-crystal layers of coalesced sulfide nanoparticles (NPs) with controllable thickness down to a few nanometers, based on thermal decomposition. This provides high-coverage, homogeneous thickness, and large-area deposition over a rough surface, with little material loss or liquid chemical waste, and deposition rates of 10 nm/min. This technique can potentially replace conventional thin-film deposition methods, such as atomic layer deposition (ALD) and chemical bath deposition (CBD) as used by the Cu(In,Ga)Se2 (CIGS) thin-film solar cell industry for decades. We demonstrate 32% improvement of CIGS thin-film solar cell efficiency in comparison to reference devices prepared by conventional CBD deposition method by depositing the ZnS NPs buffer layer using the new process. The new ZnS NPs layer allows reduction of an intrinsic ZnO layer, which can lead to severe shunt leakage in case of a CBD buffer layer. This leads to a 65% relative efficiency increase. PMID:28383488

Layer-by-Layer Assembly of a pH-Responsive and Electrochromic Thin Film

ERIC Educational Resources Information Center

Schmidt, Daniel J.; Pridgen, Eric M.; Hammond, Paula T.; Love, J. Christopher

2010-01-01

This article summarizes an experiment on thin-film fabrication with layer-by-layer assembly that is appropriate for undergraduate laboratory courses. The purpose of this experiment is to teach students about self-assembly in the context of thin films and to expose students to the concepts of functional polymeric coatings. Students dip coat…

High-performance SEGISFET pH Sensor using the structure of double-gate a-IGZO TFTs with engineered gate oxides

NASA Astrophysics Data System (ADS)

Pyo, Ju-Young; Cho, Won-Ju

2017-03-01

In this paper, we propose a high-performance separative extended gate ion-sensitive field-effect transistor (SEGISFET) that consists of a tin dioxide (SnO2) SEG sensing part and a double-gate structure amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor (TFT) with tantalum pentoxide/silicon dioxide (Ta2O5/SiO2)-engineered top-gate oxide. To increase sensitivity, we maximized the capacitive coupling ratio by applying high-k dielectric at the top-gate oxide layer. As an engineered top-gate oxide, a stack of 25 nm-thick Ta2O5 and 10 nm-thick SiO2 layers was found to simultaneously satisfy a small equivalent oxide thickness (˜17.14 nm), a low leakage current, and a stable interfacial property. The threshold-voltage instability, which is a fundamental issue in a-IGZO TFTs, was improved by low-temperature post-deposition annealing (˜87 °C) using microwave irradiation. The double-gate structure a-IGZO TFTs with engineered top-gate oxide exhibited high mobility, small subthreshold swing, high drive current, and larger on/off current ratio. The a-IGZO SEGISFETs with a dual-gate sensing mode showed a pH sensitivity of 649.04 mV pH-1, which is far beyond the Nernst limit. The non-ideal behavior of ISFETs, hysteresis, and drift effect also improved. These results show that the double-gate structure a-IGZO TFTs with engineered top-gate oxide can be a good candidate for cheap and disposable SEGISFET sensors.

Gyrotactic trapping: A numerical study

NASA Astrophysics Data System (ADS)

Ghorai, S.

2016-04-01

Gyrotactic trapping is a mechanism proposed by Durham et al. ["Disruption of vertical motility by shear triggers formation of thin Phytoplankton layers," Science 323, 1067-1070 (2009)] to explain the formation of thin phytoplankton layer just below the ocean surface. This mechanism is examined numerically using a rational model based on the generalized Taylor dispersion theory. The crucial role of sedimentation speed in the thin layer formation is demonstrated. The effects of variation in different parameters on the thin layer formation are also investigated.

[High performance thin-layer chromatography in specific blood diagnosis (author's transl)].

PubMed

Bernardelli, B; Masotti, G

1976-01-01

Furthering their research into the differentiation of various haemoglobins (both human and animal) with the use of thin layer chromatographic methods, the Authors have applied Kaiser's high performance thin layer chromatography (HPTLC) to the specific diagnosis of blood. Although the method was superior to ascending one-dimensional thin layer chromatography for its sensitivity, Rf reproducibility and much briefer migration times, it did not turn out to be suitable for application to the specific requirements of forensic haematology.

Thin-film metal coated insulation barrier in a Josephson tunnel junction. [Patent application

DOEpatents

Hawkins, G.A.; Clarke, J.

1975-10-31

A highly stable, durable, and reproducible Josephson tunnel junction consists of a thin-film electrode of a hard superconductor, a thin oxide insulation layer over the electrode constituting a Josephson tunnel junction barrier, a thin-film layer of stabilizing metal over the barrier, and a second thin-film hard superconductive electrode over the stabilizing film. The thin stabilizing metal film is made only thick enough to limit penetration of the electrode material through the insulation layer so as to prevent a superconductive short.

Double-layer versus single-layer bone-patellar tendon-bone anterior cruciate ligament reconstruction: a prospective randomized study with 3-year follow-up.

PubMed

Mei, Xiaoliang; Zhang, Zhenxiang; Yang, Jingwen

2016-12-01

To evaluate the clinical results of a randomized controlled trial of single-layer versus double-layer bone-patellar tendon-bone (BPTB) anterior cruciate ligament (ACL) reconstruction. Fifty-eight subjects who underwent primary ACL reconstruction with a BPTB allograft were prospectively randomized into two groups: single-layer reconstruction (n = 31) and double-layer reconstruction (n = 27). The following evaluation methods were used: clinical examination, KT-1000 arthrometer measurement, muscle strength, Tegner activity score, Lysholm score, subjective rating scale regarding patient satisfaction and sports performance level, graft retear, contralateral ACL tear, and additional meniscus surgery. Forty-eight subjects (24 in single-layer group and 24 in double-layer group) who were followed up for 3 years were evaluated. Preoperatively, there were no differences between the groups. At 3-year follow-up, the Lachman and pivot-shift test results were better in the double-layer group (P = 0.019 and P < 0.0001, respectively). KT measurements were better in the double-layer group (mean 2.9 versus 1.5 mm; P = 0.0025). The Tegner score was also better in the double-layer group (P = 0.024). There were no significant differences in range of motion, muscle strength, Lysholm score, subjective rating scale, graft retear, and secondary meniscal tear. In ACL reconstruction, double-layer BPTB reconstruction was significantly better than single-layer reconstruction regarding anterior and rotational stability at 3-year follow-up. The results of KT measurements and the Lachman and pivot-shift tests were significantly better in the double-layer group, whereas there was no difference in the anterior drawer test results. The Tegner score was also better in the double-layer group; however, there were no differences in the other subjective findings.

Fabrication of Crack-Free Barium Titanate Thin Film with High Dielectric Constant Using Sub-Micrometric Scale Layer-by-Layer E-Jet Deposition.

PubMed

Liang, Junsheng; Li, Pengfei; Wang, Dazhi; Fang, Xu; Ding, Jiahong; Wu, Junxiong; Tang, Chang

2016-01-19

Dense and crack-free barium titanate (BaTiO₃, BTO) thin films with a thickness of less than 4 μm were prepared by using sub-micrometric scale, layer-by-layer electrohydrodynamic jet (E-jet) deposition of the suspension ink which is composed of BTO nanopowder and BTO sol. Impacts of the jet height and line-to-line pitch of the deposition on the micro-structure of BTO thin films were investigated. Results show that crack-free BTO thin films can be prepared with 4 mm jet height and 300 μm line-to-line pitch in this work. Dielectric constant of the prepared BTO thin film was recorded as high as 2940 at 1 kHz at room temperature. Meanwhile, low dissipation factor of the BTO thin film of about 8.6% at 1 kHz was also obtained. The layer-by-layer E-jet deposition technique developed in this work has been proved to be a cost-effective, flexible and easy to control approach for the preparation of high-quality solid thin film.

Capacitor with a composite carbon foam electrode

DOEpatents

Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

1999-01-01

Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid partides being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy.

Method for fabricating composite carbon foam

DOEpatents

Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

2001-01-01

Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy.

Capacitor with a composite carbon foam electrode

DOEpatents

Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

1999-04-27

Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

Composite carbon foam electrode

DOEpatents

Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

1997-05-06

Carbon aerogels used as a binder for granulated materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

Transparent and flexible electrodes and supercapacitors using polyaniline/single-walled carbon nanotube composite thin films

NASA Astrophysics Data System (ADS)

Ge, Jun; Cheng, Guanghui; Chen, Liwei

2011-08-01

Large-scale transparent and flexible electronic devices have been pursued for potential applications such as those in touch sensors and display technologies. These applications require that the power source of these devices must also comply with transparent and flexible features. Here we present transparent and flexible supercapacitors assembled from polyaniline (PANI)/single-walled carbon nanotube (SWNT) composite thin film electrodes. The ultrathin, optically homogeneous and transparent, electrically conducting films of the PANI/SWNT composite show a large specific capacitance due to combined double-layer capacitance and pseudo-capacitance mechanisms. A supercapacitor assembled using electrodes with a SWNT density of 10.0 µg cm-2 and 59 wt% PANI gives a specific capacitance of 55.0 F g-1 at a current density of 2.6 A g-1, showing its possibility for transparent and flexible energy storage.

Transparent and flexible electrodes and supercapacitors using polyaniline/single-walled carbon nanotube composite thin films.

PubMed

Ge, Jun; Cheng, Guanghui; Chen, Liwei

2011-08-01

Large-scale transparent and flexible electronic devices have been pursued for potential applications such as those in touch sensors and display technologies. These applications require that the power source of these devices must also comply with transparent and flexible features. Here we present transparent and flexible supercapacitors assembled from polyaniline (PANI)/single-walled carbon nanotube (SWNT) composite thin film electrodes. The ultrathin, optically homogeneous and transparent, electrically conducting films of the PANI/SWNT composite show a large specific capacitance due to combined double-layer capacitance and pseudo-capacitance mechanisms. A supercapacitor assembled using electrodes with a SWNT density of 10.0 µg cm(-2) and 59 wt% PANI gives a specific capacitance of 55.0 F g(-1) at a current density of 2.6 A g(-1), showing its possibility for transparent and flexible energy storage. This journal is © The Royal Society of Chemistry 2011

Utilizing boron nitride sheets as thin supports for high resolution imaging of nanocrystals.

PubMed

Wu, Yimin A; Kirkland, Angus I; Schäffel, Franziska; Porfyrakis, Kyriakos; Young, Neil P; Briggs, G Andrew D; Warner, Jamie H

2011-05-13

We demonstrate the use of thin BN sheets as supports for imaging nanocrystals using low voltage (80 kV) aberration-corrected high resolution transmission electron microscopy. This provides an alternative to the previously utilized 2D crystal supports of graphene and graphene oxide. A simple chemical exfoliation method is applied to get few layer boron nitride (BN) sheets with micrometer-sized dimensions. This generic approach of using BN sheets as supports is shown by depositing Mn doped ZnSe nanocrystals directly onto the BN sheets and resolving the atomic structure from both the ZnSe nanocrystals and the BN support. Phase contrast images reveal moiré patterns of interference between the beams diffracted by the nanocrystals and the BN substrate that are used to determine the relative orientation of the nanocrystals with respect to the BN sheets and interference lattice planes. Double diffraction is observed and has been analyzed.

Elastic Valve Using Induced-Charge Electro-Osmosis

NASA Astrophysics Data System (ADS)

Sugioka, Hideyuki

2015-06-01

Biomimic devices using induced-charge electro-osmosis (ICEO) is interesting since they have the possibility to realize high-performance functions with simple structures and with low-energy consumption. Thus, inspired by a cilium, we propose a two-dimensional artificial elastic valve using hydrodynamic force due to ICEO with a thin elastic beam in a microfluidic channel and numerically examine the valving performance. By an implicit strongly coupled simulation technique between a fluid and an elastic structure based on the boundary-element method, along with the thin-double-layer approximation, we realize stable calculations and find that the elastic valve using ICEO functions effectively at high frequency with low applied voltages in a realistic pressure flow. Further, we also examine passive motion of the valve; i.e., it stops a reverse flow effectively and releases a forward flow in the channel. We believe that our device can be used in a wide range of microfluidic applications, such as mixers, pumps, etc.

Defect generation in amorphous-indium-gallium-zinc-oxide thin-film transistors by positive bias stress at elevated temperature

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

Um, Jae Gwang; Mativenga, Mallory; Jang, Jin, E-mail: jjang@khu.ac.kr

2014-04-07

We report on the generation and characterization of a hump in the transfer characteristics of amorphous indium gallium zinc-oxide thin-film transistors by positive bias temperature stress. The hump depends strongly on the gate bias stress at 100 °C. Due to the hump, the positive shift of the transfer characteristic in deep depletion is always smaller that in accumulation. Since, the latter shift is twice the former, with very good correlation, we conclude that the effect is due to creation of a double acceptor, likely to be a cation vacancy. Our results indicate that these defects are located near the gate insulator/activemore » layer interface, rather than in the bulk. Migration of donor defects from the interface towards the bulk may also occur under PBST at 100 °C.« less

Performance enhancement in Sb doped Cu(InGa)Se2 thin film solar cell by e-beam evaporation

NASA Astrophysics Data System (ADS)

Chen, Jieyi; Shen, Honglie; Zhai, Zihao; Li, Yufang; Yi, Yunge

2018-03-01

To investigate the effects of Sb doping on the structural and electrical properties of Cu(InGa)Se2 (CIGS) thin films and solar cells, CIGS thin films, prepared by e-beam evaporation on soda-lime glass, were doped with lower and upper Sb layers in the precursor stacks respectively. Change of structure and introduction of stress were observed in the CIGS thin films with upper Sb layer in stack through XRD and Raman measurement. Both crystalline quality and compactness of CIGS thin films were improved by the doping of upper Sb layer in stack and the CIGS thin film showed an optimal structural property with 20 nm Sb layer. Movement of Fermi level of the surface of CIGS thin film after doping of upper Sb layer in stack and electrons transfer between Cu/Cu+ redox couple and CIGS thin films, which provided probability for the substitution of Sb for Cu sites at the surface of CIGS thin films, were proposed to explain the migration of Cu from the surface to the bulk of CIGS thin films. The larger barrier at the CIGS/CdS interface after doping of upper Sb layer in stack made contribution to the increase of VOC of CIGS solar cells. The efficiency of CIGS solar cell was improved from 3.3% to 7.2% after doping with 20 nm upper Sb. Compared to the CIGS solar cell with lower Sb layer in stack, in which an additional Cu2-xSe phase was found, the CIGS solar cell with upper Sb layer in stack possessed a higher efficiency.

Photovoltaic devices comprising cadmium stannate transparent conducting films and method for making

DOEpatents

Wu, Xuanzhi; Coutts, Timothy J.; Sheldon, Peter; Rose, Douglas H.

1999-01-01

A photovoltaic device having a substrate, a layer of Cd.sub.2 SnO.sub.4 disposed on said substrate as a front contact, a thin film comprising two or more layers of semiconductor materials disposed on said layer of Cd.sub.2 SnO.sub.4, and an electrically conductive film disposed on said thin film of semiconductor materials to form a rear electrical contact to said thin film. The device is formed by RF sputter coating a Cd.sub.2 SnO.sub.4 layer onto a substrate, depositing a thin film of semiconductor materials onto the layer of Cd.sub.2 SnO.sub.4, and depositing an electrically conductive film onto the thin film of semiconductor materials.

Observation of a stationary, current-free double layer in a plasma

NASA Technical Reports Server (NTRS)

Hairapetian, G.; Stenzel, R. L.

1990-01-01

A stationary, current-free, potential double layer is formed in a two-electron-population plasma due to self-consistent separation of the two electron species. The position and amplitude of the double layer are controlled by the relative densities of the two electron populations. The steady-state double layer traps the colder electrons on the high potential side, and generates a neutralized, monoenergetic ion beam on the low potential side. The field-aligned double layer is annihilated when an electron current is drawn through the plasma.

Amplitude various angles (AVA) phenomena in thin layer reservoir: Case study of various reservoirs

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

Nurhandoko, Bagus Endar B., E-mail: bagusnur@bdg.centrin.net.id, E-mail: bagusnur@rock-fluid.com; Rock Fluid Imaging Lab., Bandung; Susilowati, E-mail: bagusnur@bdg.centrin.net.id, E-mail: bagusnur@rock-fluid.com

2015-04-16

Amplitude various offset is widely used in petroleum exploration as well as in petroleum development field. Generally, phenomenon of amplitude in various angles assumes reservoir’s layer is quite thick. It also means that the wave is assumed as a very high frequency. But, in natural condition, the seismic wave is band limited and has quite low frequency. Therefore, topic about amplitude various angles in thin layer reservoir as well as low frequency assumption is important to be considered. Thin layer reservoir means the thickness of reservoir is about or less than quarter of wavelength. In this paper, I studied aboutmore » the reflection phenomena in elastic wave which considering interference from thin layer reservoir and transmission wave. I applied Zoeppritz equation for modeling reflected wave of top reservoir, reflected wave of bottom reservoir, and also transmission elastic wave of reservoir. Results show that the phenomena of AVA in thin layer reservoir are frequency dependent. Thin layer reservoir causes interference between reflected wave of top reservoir and reflected wave of bottom reservoir. These phenomena are frequently neglected, however, in real practices. Even though, the impact of inattention in interference phenomena caused by thin layer in AVA may cause inaccurate reservoir characterization. The relation between classes of AVA reservoir and reservoir’s character are different when effect of ones in thin reservoir and ones in thick reservoir are compared. In this paper, I present some AVA phenomena including its cross plot in various thin reservoir types based on some rock physics data of Indonesia.« less

Nanoplasmonic sensing of metal-halide complex formation and the electric double layer capacitor.

PubMed

Dahlin, Andreas B; Zahn, Raphael; Vörös, Janos

2012-04-07

Many nanotechnological devices are based on implementing electrochemistry with plasmonic nanostructures, but these systems are challenging to understand. We present a detailed study of the influence of electrochemical potentials on plasmon resonances, in the absence of surface coatings and redox active molecules, by synchronized voltammetry and spectroscopy. The experiments are performed on gold nanodisks and nanohole arrays in thin gold films, which are fabricated by improved methods. New insights are provided by high resolution spectroscopy and variable scan rates. Furthermore, we introduce new analytical models in order to understand the spectral changes quantitatively. In contrast to most previous literature, we find that the plasmonic signal is caused almost entirely by the formation of ionic complexes on the metal surface, most likely gold chloride in this study. The refractometric sensing effect from the ions in the electric double layer can be fully neglected, and the charging of the metal gives a surprisingly small effect for these systems. Our conclusions are consistent for both localized nanoparticle plasmons and propagating surface plasmons. We consider the results in this work especially important in the context of combined electrochemical and optical sensors. This journal is © The Royal Society of Chemistry 2012

Polyaniline-coated freestanding porous carbon nanofibers as efficient hybrid electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Tran, Chau; Singhal, Richa; Lawrence, Daniel; Kalra, Vibha

2015-10-01

Three-dimensional, free-standing, hybrid supercapacitor electrodes combining polyaniline (PANI) and porous carbon nanofibers (P-CNFs) were fabricated with the aim to integrate the benefits of both electric double layer capacitors (high power, cyclability) and pseudocapacitors (high energy density). A systematic investigation of three different electropolymerization techniques, namely, potentiodynamic, potentiostatic, and galvanostatic, for electrodeposition of PANI on freestanding carbon nanofiber mats was conducted. It was found that the galvanostatic method, where the current density is kept constant and can be easily controlled facilitates conformal and uniform coating of PANI on three-dimensional carbon nanofiber substrates. The electrochemical tests indicated that the PANI-coated P-CNFs exhibit excellent specific capacitance of 366 F g-1 (vs. 140 F g-1 for uncoated porous carbon nanofibers), 140 F cm-3 volumetric capacitance, and up to 2.3 F cm-2 areal capacitance at 100 mV s-1 scan rate. Such excellent performance is attributed to a thin and conformal coating of PANI achieved using the galvanostatic electrodeposition technique, which not only provides pseudocapacitance with high rate capability, but also retains the double-layer capacitance of the underlying P-CNFs.

Electroosmosis over charge-modulated surfaces with finite electrical double layer thicknesses: Asymptotic and numerical investigations

NASA Astrophysics Data System (ADS)

Ghosh, Uddipta; Mandal, Shubhadeep; Chakraborty, Suman

2017-06-01

Here we attempt to solve the fully coupled Poisson-Nernst-Planck-Navier-Stokes equations, to ascertain the influence of finite electric double layer (EDL) thickness on coupled charge and fluid dynamics over patterned charged surfaces. We go beyond the well-studied "weak-field" limit and obtain numerical solutions for a wide range of EDL thicknesses, applied electric field strengths, and the surface potentials. Asymptotic solutions to the coupled system are also derived using a combination of singular and regular perturbation, for thin EDLs and low surface potential, and good agreement between the two solutions is observed. Counterintuitively to common arguments, our analysis reveals that finite EDL thickness may either increase or decrease the "free-stream velocity" (equivalent to net throughput), depending on the strength of the applied electric field. We also unveil a critical EDL thickness for which the effect of finite EDL thickness on the free-stream velocity is the most prominent. Finally, we demonstrate that increasing the surface potential and the applied field tends to influence the overall flow patterns in the contrasting manners. These results may be of profound importance in developing a comprehensive theoretical basis for designing electro-osmotically actuated microfluidic mixtures.

3D-fabrication of tunable and high-density arrays of crystalline silicon nanostructures

NASA Astrophysics Data System (ADS)

Wilbers, J. G. E.; Berenschot, J. W.; Tiggelaar, R. M.; Dogan, T.; Sugimura, K.; van der Wiel, W. G.; Gardeniers, J. G. E.; Tas, N. R.

2018-04-01

In this report, a procedure for the 3D-nanofabrication of ordered, high-density arrays of crystalline silicon nanostructures is described. Two nanolithography methods were utilized for the fabrication of the nanostructure array, viz. displacement Talbot lithography (DTL) and edge lithography (EL). DTL is employed to perform two (orthogonal) resist-patterning steps to pattern a thin Si3N4 layer. The resulting patterned double layer serves as an etch mask for all further etching steps for the fabrication of ordered arrays of silicon nanostructures. The arrays are made by means of anisotropic wet etching of silicon in combination with an isotropic retraction etch step of the etch mask, i.e. EL. The procedure enables fabrication of nanostructures with dimensions below 15 nm and a potential density of 1010 crystals cm-2.

Transition from single to multiple double layers. [of plasma

NASA Technical Reports Server (NTRS)

Chan, C.; Hershkowitz, N.

1982-01-01

Laboratory results are presented to define parameters which allow the boundary conditions to control the characteristics of double layers of plasma. It is shown that multiple double layers arise when the ratio of Debye length to system length decreases, a result which is in line with boundary layer theory. The significance of inclusion of the system length is noted to render BGK treatments of double layers, wherein the length is neglected, invalid.

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation

DOEpatents

Ruffner, Judith A.; Bullington, Jeff A.; Clem, Paul G.; Warren, William L.; Brinker, C. Jeffrey; Tuttle, Bruce A.; Schwartz, Robert W.

1999-01-01

A monolithic infrared detector structure which allows integration of pyroelectric thin films atop low thermal conductivity aerogel thin films. The structure comprises, from bottom to top, a substrate, an aerogel insulating layer, a lower electrode, a pyroelectric layer, and an upper electrode layer capped by a blacking layer. The aerogel can offer thermal conductivity less than that of air, while providing a much stronger monolithic alternative to cantilevered or suspended air-gap structures for pyroelectric thin film pixel arrays. Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 thin films deposited on these structures displayed viable pyroelectric properties, while processed at 550.degree. C.

Synthesis and Characterization of 2-D Materials

NASA Astrophysics Data System (ADS)

Pazos, S.; Sahoo, P.; Afaneh, T.; Rodriguez Gutierrez, H.

Atomically thin transition-metal dichacogenides (TMD), graphene, and boron nitride (BN) are two-dimensional materials where the charge carriers (electrons and holes) are confined to move in a plane. They exhibit distinctive optoelectronic properties compared to their bulk layered counterparts. When combined into heterostructures, these materials open more possibilities in terms of new properties and device functionality. In this work, WSe2 and graphene were grown using Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD) techniques. The quality and morphology of each material was checked using Raman, Photoluminescence Spectroscopy, and Scanning Electron Microscopy. Graphene had been successfully grown homogenously, characterized, and transferred from copper to silicon dioxide substrates; these films will be used in future studies to build 2-D devices. Different morphologies of WSe2 2-D islands were successfully grown on SiO2 substrates. Depending on the synthesis conditions, the material on each sample had single layer, double layer, and multi-layer areas. A variety of 2-D morphologies were also observed in the 2-D islands. This project is supported by the NSF REU Grant #1560090 and NSF Grant #DMR-1557434.

THE EFFECTS OF CURVATURE AND EXPANSION ON HELIUM DETONATIONS ON WHITE DWARF SURFACES

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

Moore, Kevin; Bildsten, Lars; Townsley, Dean M.

2013-10-20

Accreted helium layers on white dwarfs have been highlighted for many decades as a possible site for a detonation triggered by a thermonuclear runaway. In this paper, we find the minimum helium layer thickness that will sustain a steady laterally propagating detonation and show that it depends on the density and composition of the helium layer, specifically {sup 12}C and {sup 16}O. Detonations in these thin helium layers have speeds slower than the Chapman-Jouget (CJ) speed from complete helium burning, v{sub CJ} = 1.5 × 10{sup 9} cm s{sup –1}. Though gravitationally unbound, the ashes still have unburned helium (≈80%more » in the thinnest cases) and only reach up to heavy elements such as {sup 40}Ca, {sup 44}Ti, {sup 48}Cr, and {sup 52}Fe. It is rare for these thin shells to generate large amounts of {sup 56}Ni. We also find a new set of solutions that can propagate in even thinner helium layers when {sup 16}O is present at a minimum mass fraction of ≈0.07. Driven by energy release from α captures on {sup 16}O and subsequent elements, these slow detonations only create ashes up to {sup 28}Si in the outer detonated He shell. We close by discussing how the unbound helium burning ashes may create faint and fast 'Ia' supernovae as well as events with virtually no radioactivity, and speculate on how the slower helium detonation velocities impact the off-center ignition of a carbon detonation that could cause a Type Ia supernova in the double detonation scenario.« less

Microstructure and thermochromic properties of VOX-WOX-VOX ceramic thin films

NASA Astrophysics Data System (ADS)

Khamseh, S.; Araghi, H.; Ghahari, M.; Faghihi Sani, M. A.

2016-03-01

W-doped VO2 films have been synthesized via oxygen annealing of V-W-V (vanadium-tungsten-vanadium) multilayered films. The effects of middle layer's thickness of V-W-V multilayered film on structure and properties of VOX-WOX-VOX ceramic thin films were investigated. The as-deposited V-W-V multilayered film showed amorphous-like structure when mixed structure of VO2 (M) and VO2 (B) was formed in VOX-WOX-VOX ceramic thin films. Tungsten content of VOX-WOX-VOX ceramic thin films increased with increasing middle layer's thickness. With increasing middle layer's thickness, room temperature square resistance ( R sq) of VOX-WOX-VOX ceramic thin films increased from 65 to 86 kΩ/sq. The VOX-WOX-VOX ceramic thin film with the thinnest middle layer showed significant SMT (semiconductor-metal transition) when SMT became negligible on increasing middle layer's thickness.

Antiferroelectricity in lanthanum doped zirconia without metallic capping layers and post-deposition/-metallization anneals

NASA Astrophysics Data System (ADS)

Wang, Zheng; Gaskell, Anthony Arthur; Dopita, Milan; Kriegner, Dominik; Tasneem, Nujhat; Mack, Jerry; Mukherjee, Niloy; Karim, Zia; Khan, Asif Islam

2018-05-01

We report the effects of lanthanum doping/alloying on antiferroelectric (AFE) properties of ZrO2. Starting with pure ZrO2, an increase in La doping leads to the narrowing of the AFE double hysteresis loops and an increase in the critical voltage/electric field for AFE → ferroelectric transition. At higher La contents, the polarization-voltage characteristics of doped/alloyed ZrO2 resemble that of a non-linear dielectric without any discernible AFE-type hysteresis. X-ray diffraction based analysis indicates that the increased La content while preserving the non-polar, parent AFE, tetragonal P42/nmc phase leads to a decrease in tetragonality and the (nano-)crystallite size and an increase in the unit cell volume. Furthermore, antiferroelectric behavior is obtained in the as-deposited thin films without requiring any capping metallic layers and post-deposition/-metallization anneals due to which our specific atomic layer deposition system configuration crystallizes and stabilizes the AFE tetragonal phase during growth.

Influence of the charge double layer on solid oxide fuel cell stack behavior

NASA Astrophysics Data System (ADS)

Whiston, Michael M.; Bilec, Melissa M.; Schaefer, Laura A.

2015-10-01

While the charge double layer effect has traditionally been characterized as a millisecond phenomenon, longer timescales may be possible under certain operating conditions. This study simulates the dynamic response of a previously developed solid oxide fuel cell (SOFC) stack model that incorporates the charge double layer via an equivalent circuit. The model is simulated under step load changes. Baseline conditions are first defined, followed by consideration of minor and major deviations from the baseline case. This study also investigates the behavior of the SOFC stack with a relatively large double layer capacitance value, as well as operation of the SOFC stack under proportional-integral (PI) control. Results indicate that the presence of the charge double layer influences the SOFC stack's settling time significantly under the following conditions: (i) activation and concentration polarizations are significantly increased, or (ii) a large value of the double layer capacitance is assumed. Under normal (baseline) operation, on the other hand, the charge double layer effect diminishes within milliseconds, as expected. It seems reasonable, then, to neglect the charge double layer under normal operation. However, careful consideration should be given to potential variations in operation or material properties that may give rise to longer electrochemical settling times.

Improved High-Energy Response of AlGaAs/GaAs Solar Cells Using a Low-Cost Technology

NASA Astrophysics Data System (ADS)

Noorzad, Camron D.; Zhao, Xin; Harotoonian, Vache; Woodall, Jerry M.

2016-12-01

We report on an AlGaAs/GaAs solar cell with a significantly increased high-energy response that was produced via a modified liquid phase epitaxy (LPE) technique. This technique uses a one-step process in which the solid-liquid equilibrium Al-Ga-As:Zn melt in contact with an n-type vendor GaAs substrate simultaneously getters impurities in the substrate that shorten minority carrier lifetimes, diffuses Zn into the substrate to create a p- n junction, and forms a thin p-AlGaAs window layer that enables more high-energy light to be efficiently absorbed. Unlike conventional LPE, this process is performed isothermally. In our "double Al" method, the ratio of Al in the melt ("Al melt ratio") that was used in our process was two times more than what was previously reported in the record 1977 International Business Machines (IBM) solar cell. Photoluminescence (PL) results showed our double Al sample yielded a response to 405 nm light ("blue light"), which was more than twice as intense as the response from our replicated IBM cell. The original 1977 cell had a low-intensity spectral response to photon wavelengths under 443 nm (Woodall and Hovel in Sol Energy Mater Sol Cells 29:176, 1990). Secondary ion mass spectrometry results confirmed the increased blue light response was due to a large reduction in AlGaAs window layer thickness. These results proved increasing the Al melt ratio broadens the spectrum of light that can be transmitted through the window layer into the active GaAs region for absorption, increasing the overall solar cell efficiency. Our enhanced double Al method can pave the way for large-scale manufacturing of low-cost, high-efficiency solar cells.

Modeling electrical double-layer effects for microfluidic impedance spectroscopy from 100 kHz to 110 GHz.

PubMed

Little, Charles A E; Orloff, Nathan D; Hanemann, Isaac E; Long, Christian J; Bright, Victor M; Booth, James C

2017-07-25

Broadband microfluidic-based impedance spectroscopy can be used to characterize complex fluids, with applications in medical diagnostics and in chemical and pharmacological manufacturing. Many relevant fluids are ionic; during impedance measurements ions migrate to the electrodes, forming an electrical double-layer. Effects from the electrical double-layer dominate over, and reduce sensitivity to, the intrinsic impedance of the fluid below a characteristic frequency. Here we use calibrated measurements of saline solution in microfluidic coplanar waveguide devices at frequencies between 100 kHz and 110 GHz to directly measure the double-layer admittance for solutions of varying ionic conductivity. We successfully model the double-layer admittance using a combination of a Cole-Cole response with a constant phase element contribution. Our analysis yields a double-layer relaxation time that decreases linearly with solution conductivity, and allows for double-layer effects to be separated from the intrinsic fluid response and quantified for a wide range of conducting fluids.

AC electric field induced dielectrophoretic assembly behavior of gold nanoparticles in a wide frequency range

NASA Astrophysics Data System (ADS)

Liu, Weiyu; Wang, Chunhui; Ding, Haitao; Shao, Jinyou; Ding, Yucheng

2016-05-01

In this work, we focus on frequency-dependence of pearl chain formations (PCF) of gold nanoparticles driven by AC dielectrophoresis (DEP), especially in a low field-frequency range, where induced double-layer charging effect at ideally polarizable surfaces on particle DEP behavior and surrounding liquid motion need not be negligible. As field frequency varies, grown features of DEP assembly structures ranging from low-frequency non-bridged gap to high-frequency single gold nanoparticle-made nanowires bridging the electrodes are demonstrated experimentally. Specifically, at 10 kHz, a kind of novel channel-like structure with parallel opposing banks is formed at the center of interelectrode gap. In stark contrast, at 1 MHz, thin PCF with diameter of 100 nm is created along the shortest distance of the isolation spacing. Moreover, a particular conductive path of nanoparticle chains is produced at 1 MHz in a DEP device embedded with multiple floating electrodes. A theoretical framework taking into account field-induced double-layer polarization at both the particle/electrolyte and electrode/electrolyte interface is developed to correlate these experimental observations with induced-charge electrokinetic (ICEK) phenomenon. And a RC circuit model is helpful in accounting for the formation of this particular non-bridged channel-like structure induced by a low-frequency AC voltage. As compared to thin PCF formed at high field frequency that effectively short circuits the electrode pair, though it is difficult for complete PCF bridging to occur at low frequency, the non-bridged conducting microstructure has potential to further miniaturize the size of electrode gap fabricated by standard micromachining process and may find useful application in biochemical sensing.

Nonlocal Poisson-Fermi double-layer models: Effects of nonuniform ion sizes on double-layer structure

NASA Astrophysics Data System (ADS)

Xie, Dexuan; Jiang, Yi

2018-05-01

This paper reports a nonuniform ionic size nonlocal Poisson-Fermi double-layer model (nuNPF) and a uniform ionic size nonlocal Poisson-Fermi double-layer model (uNPF) for an electrolyte mixture of multiple ionic species, variable voltages on electrodes, and variable induced charges on boundary segments. The finite element solvers of nuNPF and uNPF are developed and applied to typical double-layer tests defined on a rectangular box, a hollow sphere, and a hollow rectangle with a charged post. Numerical results show that nuNPF can significantly improve the quality of the ionic concentrations and electric fields generated from uNPF, implying that the effect of nonuniform ion sizes is a key consideration in modeling the double-layer structure.

Dynamical features and electric field strengths of double layers driven by currents. [in auroras

NASA Technical Reports Server (NTRS)

Singh, N.; Thiemann, H.; Schunk, R. W.

1985-01-01

In recent years, a number of papers have been concerned with 'ion-acoustic' double layers. In the present investigation, results from numerical simulations are presented to show that the shapes and forms of current-driven double layers evolve dynamically with the fluctuations in the current through the plasma. It is shown that double layers with a potential dip can form even without the excitation of ion-acoustic modes. Double layers in two-and one-half-dimensional simulations are discussed, taking into account the simulation technique, the spatial and temporal features of plasma, and the dynamical behavior of the parallel potential distribution. Attention is also given to double layers in one-dimensional simulations, and electrical field strengths predicted by two-and one-half-dimensional simulations.

System and Method for Fabricating Super Conducting Circuitry on Both Sides of an Ultra-Thin Layer

NASA Technical Reports Server (NTRS)

Brown, Ari D. (Inventor); Mikula, Vilem (Inventor)

2017-01-01

A method of fabricating circuitry in a wafer includes depositing a superconducting metal on a silicon on insulator wafer having a handle wafer, coating the wafer with a sacrificial layer and bonding the wafer to a thermally oxide silicon wafer with a first epoxy. The method includes flipping the wafer, thinning the flipped wafer by removing a handle wafer, etching a buried oxide layer, depositing a superconducting layer, bonding the wafer to a thermally oxidized silicon wafer having a handle wafer using an epoxy, flipping the wafer again, thinning the flipped wafer, etching a buried oxide layer from the wafer and etching the sacrificial layer from the wafer. The result is a wafer having superconductive circuitry on both sides of an ultra-thin silicon layer.

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.

Device and method for luminescence enhancement by resonant energy transfer from an absorptive thin film

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

Akselrod, Gleb M.; Bawendi, Moungi G.; Bulovic, Vladimir

Disclosed are a device and a method for the design and fabrication of the device for enhancing the brightness of luminescent molecules, nanostructures, and thin films. The device includes a mirror, a dielectric medium or spacer, an absorptive layer, and a luminescent layer. The absorptive layer is a continuous thin film of a strongly absorbing organic or inorganic material. The luminescent layer may be a continuous luminescent thin film or an arrangement of isolated luminescent species, e.g., organic or metal-organic dye molecules, semiconductor quantum dots, or other semiconductor nanostructures, supported on top of the absorptive layer.

The design and performance of the nano-carbon based double layers flexible coating for tunable and high-efficiency microwave absorption

NASA Astrophysics Data System (ADS)

Zhang, Danfeng; Hao, Zhifeng; Qian, Yannan; Zeng, Bi; Zhu, Haiping; Wu, Qibai; Yan, Chengjie; Chen, Muyu

2018-05-01

Nanocarbon-based materials are outstanding microwave absorbers with good dielectric properties. In this study, double-layer silicone resin flexible absorbing coatings, composed of carbon-coated nickel nanoparticles (Ni@C) and carbon nanotubes (CNTs), with low loading and a total thickness of 2 mm, were prepared. The reflection loss (RL) of the double-layer absorbing coatings has measured for frequencies between 2 and 18 GHz using the Arch reflecting testing method. The effects of the thickness and electromagnetic parameters of each layer and of the layer sequence on the absorbing properties were investigated. It is found that the measured bandwidth (RL ≤ - 10 dB) of the optimum double-layer structure in our experiment range achieves 3.70 GHz. The results indicated that the double coating structure composed of different materials has greater synergistic absorption effect on impedance matching than that of same materials with different loading. The maximum RL of S1 (5 wt% CNTs)/S3 (60 wt% Ni@C) double-layer absorbing coating composed of different materials (S1 and S3) was larger than the one achieved using either S1 or S3 alone with the same thickness. This was because double-layer coating provided a suitable matching layer and improve the interfacial impedance. It was also shown that absorbing peak value and frequency position can be adjusted by double-layer coating structure.

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.

Y1Ba2Cu3O(6+delta) growth on thin Y-enhanced SiO2 buffer layers on silicon

NASA Technical Reports Server (NTRS)

Robin, T.; Mesarwi, A.; Wu, N. J.; Fan, W. C.; Espoir, L.; Ignatiev, A.; Sega, R.

1991-01-01

SiO2 buffer layers as thin as 2 nm have been developed for use in the growth of Y1Ba2Cu3O(6+delta) thin films on silicon substrates. The SiO2 layers are formed through Y enhancement of silicon oxidation, and are highly stoichiometric. Y1Ba2Cu3O(6+delta) film growth on silicon with thin buffer layers has shown c orientation and Tc0 = 78 K.

Photovoltaic devices comprising cadmium stannate transparent conducting films and method for making

DOEpatents

Wu, X.; Coutts, T.J.; Sheldon, P.; Rose, D.H.

1999-07-13

A photovoltaic device is disclosed having a substrate, a layer of Cd[sub 2]SnO[sub 4] disposed on said substrate as a front contact, a thin film comprising two or more layers of semiconductor materials disposed on said layer of Cd[sub 2]SnO[sub 4], and an electrically conductive film disposed on said thin film of semiconductor materials to form a rear electrical contact to said thin film. The device is formed by RF sputter coating a Cd[sub 2]SnO[sub 4] layer onto a substrate, depositing a thin film of semiconductor materials onto the layer of Cd[sub 2]SnO[sub 4], and depositing an electrically conductive film onto the thin film of semiconductor materials. 10 figs.

Layered Organization in the Coastal Ocean: 4-D Assessment of Thin Layer Structure, Dynamics and Impacts

DTIC Science & Technology

2009-09-30

maintenance and dissipation of layers; (2) to understand the spatial coherence and spatial properties of thin layers in the coastal ocean (especially in...ORCAS profilers at K1 South and K2 had a Nortek ADV (Acoustic Doppler Velocity meter) for simultaneously measuring centimeter- scale currents and...year will be used to (1) detect the presence, intensity, thickness, temporal persistence, and spatial coherence of thin optical and acoustical layers

Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films.

PubMed

Eita, Mohamed; Arwin, Hans; Granberg, Hjalmar; Wågberg, Lars

2011-11-15

Over the last decade, the use of nanocellulose in advanced technological applications has been promoted both due the excellent properties of this material in combination with its renewability. In this study, multilayered thin films composed of nanofibrillated cellulose (NFC), polyvinyl amine (PVAm) and silica nanoparticles were fabricated on polydimethylsiloxane (PDMS) using a layer-by-layer adsorption technique. The multilayer build-up was followed in situ by quartz crystal microbalance with dissipation, which indicated that the PVAm-SiO(2)-PVAm-NFC system adsorbs twice as much wet mass material compared to the PVAm-NFC system for the same number of bilayers. This is accompanied with a higher viscoelasticity for the PVAm-SiO(2)-PVAm-NFC system. Ellipsometry indicated a dry-state thickness of 2.2 and 3.4 nm per bilayer for the PVAm-NFC system and the PVAm-SiO(2)-PVAm-NFC system, respectively. Atomic force microscopy height images indicate that in both systems, a porous network structure is achieved. Young's modulus of these thin films was determined by the Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) technique. The Young's modulus of the PVAm/NFC films was doubled, from 1 to 2 GPa, upon incorporation of silica nanoparticles in the films. The introduction of the silica nanoparticles lowered the refractive index of the films, most probably due to an increased porosity of the films. Copyright © 2011 Elsevier Inc. All rights reserved.

A tri-layer thin film containing graphene oxide to protect zinc substrates from wear

NASA Astrophysics Data System (ADS)

Wang, Ying; Gu, Zhengpeng; Yuan, Ningyi; Chu, Fuqiang; Cheng, Guanggui; Ding, Jianning

2018-06-01

Due to its excellent properties, Zn alloy is widely used in daily life. However, the poor wear-resisting properties of Zn alloys limits their application. In this paper, a tri-layer thin film consisting of 3-aminopropyltriethoxysilane (APS), graphene oxide (GO) and perfluoropolyethers (PFPE) were successfully prepared on the surface of Zn alloy to improve the wear-resisting properties. The as-prepared tri-layer thin films were characterized by atomic force microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy and contact angle measurement. In addition, the tribological properties of the as-prepared tri-layer thin films were studied on a ball-on-plate tribometer and the morphologies of worn surfaces were observed using 3D noncontact interferometric microscope. Compared with the control samples, the tri-layer thin films showed excellent friction-reducing and wear-resisting properties, which was attributed to the synergistic effect of the GO as the load-carrying layer and the PFPE as the lubricating layer.

Electroacoustic theory for concentrated colloids with overlapped DLs at arbitrary kappa alpha. I. Application to nanocolloids and nonaqueous colloids.

PubMed

Shilov, V N; Borkovskaja, Y B; Dukhin, A S

2004-09-15

Existing theories of electroacoustic phenomena in concentrated colloids neglect the possibility of double layer overlap and are valid mostly for the "thin double layer," when the double layer thickness is much less than the particle size. In this paper we present a new electroacoustic theory which removes this restriction. This would make this new theory applicable to characterizing a variety of aqueous nanocolloids and of nonaqueous dispersions. There are two versions of the theory leading to the analytical solutions. The first version corresponds to strongly overlapped diffuse layers (so-called quasi-homogeneous model). It yields a simple analytical formula for colloid vibration current (CVI), which is valid for arbitrary ultrasound frequency, but for restricted kappa alpha range. This version of the theory, as well the Smoluchowski theory for microelectrophoresis, is independent of particle shape and polydispersity. This makes it very attractive for practical use, with the hope that it might be as useful as classical Smoluchowski theory. In order to determine the kappa alpha range of the quasi-homogeneous model validity we develop the second version that limits ultrasound frequency, but applies no restriction on kappa alpha. The ultrasound frequency should substantially exceed the Maxwell-Wagner relaxation frequency. This limitation makes active conductivity related current negligible compared to the passive dielectric displacement current. It is possible to derive an expression for CVI in the concentrated dispersion as formulae inhering definite integrals with integrands depending on equilibrium potential distribution. This second version allowed us to estimate the ranges of the applicability of the first, quasi-homogeneous version. It turns out that the quasi-homogeneous model works for kappa alpha values up to almost 1. For instance, at volume fraction 30%, the highest kappa alpha limit of the quasi-homogeneous model is 0.65. Therefore, this version of the electroacoustic theory is valid for almost all nonaqueous dispersions and a wide variety of nanocolloids, especially with sizes under 100 nm.

Clinical Results and Mechanical Properties of the Carotid CGUARD Double-Layered Embolic Prevention Stent.

PubMed

Wissgott, Christian; Schmidt, Wolfram; Brandt-Wunderlich, Christoph; Behrens, Peter; Andresen, Reimer

2017-02-01

To report early clinical outcomes with a novel double-layer stent for the internal carotid artery (ICA) and the in vitro investigation of the stent's mechanical properties. A prospective single-center study enrolled 30 consecutive patients (mean age 73.1±6.3 years; 21 men) with symptomatic (n=25) or high-grade (n=5) ICA stenosis treated with the new double-layer carotid CGUARD Embolic Prevention System (EPS) stent, which has an inner open-cell nitinol design with an outer closed-cell polyethylene terephthalate layer. The average stenosis of the treated arteries was 84.1%±7.9% with a mean lesion length of 16.6±2.1 mm. In the laboratory, 8×40-mm stents where tested in vitro with respect to their radial force during expansion, the bending stiffness of the stent system and the expanded stent, as well as the collapse pressure in a thin and flexible sheath. The wall adaptation was assessed using fluoroscopy after stent release in step and curved vessel models. The stent was successfully implanted in all patients. No peri- or postprocedural complications occurred; no minor or major stroke was observed in the 6-month follow-up. The bending stiffness of the expanded stent was 63.1 N·mm 2 and (not unexpectedly) was clearly lower than that of the stent system (601.5 N·mm 2 ). The normalized radial force during expansion of the stent to 7.0 mm, consistent with in vivo sizing, was relatively high (0.056 N/mm), which correlates well with the collapse pressure of 0.17 bars. Vessel wall adaptation was harmonic and caused no straightening of the vessel after clinical application. Because of its structure, the novel CGUARD EPS stent is characterized by a high flexibility combined with a high radial force and very good plaque coverage. These first clinical results demonstrate a very safe implantation behavior without any stroke up to 6 months after the procedure.

Thin film silicon by a microwave plasma deposition technique: Growth and devices, and, interface effects in amorphous silicon/crystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Jagannathan, Basanth

Thin film silicon (Si) was deposited by a microwave plasma CVD technique, employing double dilution of silane, for the growth of low hydrogen content Si films with a controllable microstructure on amorphous substrates at low temperatures (<400sp°C). The double dilution was achieved by using a Ar (He) carrier for silane and its subsequent dilution by Hsb2. Structural and electrical properties of the films have been investigated over a wide growth space (temperature, power, pressure and dilution). Amorphous Si films deposited by silane diluted in He showed a compact nature and a hydrogen content of ˜8 at.% with a photo/dark conductivity ratio of 10sp4. Thin film transistors (W/L = 500/25) fabricated on these films, showed an on/off ratio of ˜10sp6 and a low threshold voltage of 2.92 volts. Microcrystalline Si films with a high crystalline content (˜80%) were also prepared by this technique. Such films showed a dark conductivity ˜10sp{-6} S/cm, with a conduction activation energy of 0.49 eV. Film growth and properties have been compared for deposition in Ar and He carrier systems and growth models have been proposed. Low temperature junction formation by undoped thin film silicon was examined through a thin film silicon/p-type crystalline silicon heterojunctions. The thin film silicon layers were deposited by rf glow discharge, dc magnetron sputtering and microwave plasma CVD. The hetero-interface was identified by current transport analysis and high frequency capacitance methods as the key parameter controlling the photovoltaic (PV) response. The effect of the interface on the device properties (PV, junction, and carrier transport) was examined with respect to modifications created by chemical treatment, type of plasma species, their energy and film microstructure interacting with the substrate. Thermally stimulated capacitance was used to determine the interfacial trap parameters. Plasma deposition of thin film silicon on chemically clean c-Si created electron trapping sites while hole traps were seen when a thin oxide was present at the interface. Under optimized conditions, a 10.6% efficient cell (11.5% with SiOsb2 A/R) with an open circuit voltage of 0.55 volts and a short circuit current density of 30 mA/cmsp2 was fabricated.

Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule

DOE PAGES

Abellán, Gonzalo; Jordá, Jose Luis; Atienzar, Pedro; ...

2014-12-04

In this study, a hybrid magnetic multilayer material of micrometric size, with highly crystalline hexagonal crystals consisting of CoAl–LDH ferromagnetic layers intercalated with thermoresponsive 4-(4 anilinophenylazo)benzenesulfonate (AO5) molecules diluted (ratio 9 : 1) with a flexible sodium dodecylsulphate (SDS) surfactant has been obtained. The resulting material exhibits thermochromism attributable to the isomerization between the azo (prevalent at room temperature) and the hydrazone (favoured at higher temperatures) tautomers, leading to a thermomechanical response. In fact, these crystals exhibited thermally induced motion triggering remarkable changes in the crystal morphology and volume. In situ variable temperature XRD of these thin hybrids shows thatmore » the reversible change into the two tautomers is reflected in a shift of the position of the diffraction peaks at high temperatures towards lower interlayer spacing for the hydrazone form, as well as a broadening of the peaks reflecting lower crystallinity and ordering due to non-uniform spacing between the layers. These structural variations between room temperature (basal spacing (BS) = 25.91 Å) and 100 °C (BS = 25.05 Å) are also reflected in the magnetic properties of the layered double hydroxide (LDH) due to the variation of the magnetic coupling between the layers. Finally and in conclusion, our study constitutes one of the few examples showing fully reversible thermo-responsive breathing in a 2D hybrid material. In addition, the magnetic response of the hybrid can be modulated due to the thermotropism of the organic component that, by influencing the distance and in-plane correlation of the inorganic LDH, modulates the magnetism of the CoAl–LDH sheets in a certain range.« less

Accelerating dewetting on deformable substrates by adding a liquid underlayer.

PubMed

Xu, Lin; Reiter, Günter; Shi, Tongfei; An, Lijia

2010-05-18

We investigated the dependence of the dewetting velocity of a thin, low-viscosity polystyrene (PS) top film on a poly(methyl methacrylate) (PMMA) double layer consisting of a low-viscosity underlayer of thickness h(L) coated with a high-viscosity middle layer of thickness h(M). The addition of the liquid underlayer generated complex nonmonotonic behavior of the dewetting velocity as a function of increasing h(M). In particular, we observed an acceleration of dewetting for an intermediate range of h(M). This phenomenon has been interpreted by a combination deformation of the middle elastic layer and a concurrent change in the contact angle. On one hand, deformation led to the formation of a trench that dissipated energy during its movement through the liquid underlayer and thus caused a slowing down of dewetting. However, with an increase in the thickness of the elastic middle layer, the size of the trench decreased and its influence on the dewetting velocity also decreased. On the other hand, the deformation of the elastic layer also led to an increase in the contact angle. This increase in the driving capillary forces caused an increase in the dewetting velocity.

Fabrication of Crack-Free Barium Titanate Thin Film with High Dielectric Constant Using Sub-Micrometric Scale Layer-by-Layer E-Jet Deposition

PubMed Central

Liang, Junsheng; Li, Pengfei; Wang, Dazhi; Fang, Xu; Ding, Jiahong; Wu, Junxiong; Tang, Chang

2016-01-01

Dense and crack-free barium titanate (BaTiO3, BTO) thin films with a thickness of less than 4 μm were prepared by using sub-micrometric scale, layer-by-layer electrohydrodynamic jet (E-jet) deposition of the suspension ink which is composed of BTO nanopowder and BTO sol. Impacts of the jet height and line-to-line pitch of the deposition on the micro-structure of BTO thin films were investigated. Results show that crack-free BTO thin films can be prepared with 4 mm jet height and 300 μm line-to-line pitch in this work. Dielectric constant of the prepared BTO thin film was recorded as high as 2940 at 1 kHz at room temperature. Meanwhile, low dissipation factor of the BTO thin film of about 8.6% at 1 kHz was also obtained. The layer-by-layer E-jet deposition technique developed in this work has been proved to be a cost-effective, flexible and easy to control approach for the preparation of high-quality solid thin film. PMID:28787860

MultiLayer solid electrolyte for lithium thin film batteries

DOEpatents

Lee, Se -Hee; Tracy, C. Edwin; Pitts, John Roland; Liu, Ping

2015-07-28

A lithium metal thin-film battery composite structure is provided that includes a combination of a thin, stable, solid electrolyte layer [18] such as Lipon, designed in use to be in contact with a lithium metal anode layer; and a rapid-deposit solid electrolyte layer [16] such as LiAlF.sub.4 in contact with the thin, stable, solid electrolyte layer [18]. Batteries made up of or containing these structures are more efficient to produce than other lithium metal batteries that use only a single solid electrolyte. They are also more resistant to stress and strain than batteries made using layers of only the stable, solid electrolyte materials. Furthermore, lithium anode batteries as disclosed herein are useful as rechargeable batteries.

Longitudinal transvaginal ultrasound evaluation of cesarean scar niche incidence and depth in the first two years after single- or double-layer uterotomy closure: a randomized controlled trial.

PubMed

Bamberg, Christian; Hinkson, Larry; Dudenhausen, Joachim W; Bujak, Verena; Kalache, Karim D; Henrich, Wolfgang

2017-12-01

Cesarean deliveries are the most common abdominal surgery procedure globally, and the optimal way to suture the hysterotomy remains a matter of debate. The aim of this study was to assess the incidence of cesarean scar niches and the depth after single- or double-layer uterine closure. We performed a randomized controlled trial in which women were allocated to three uterotomy suture techniques: continuous single-layer unlocked, continuous locked single-layer, or double-layer sutures. Transvaginal ultrasound was performed six weeks and 6-24 months after cesarean delivery [Clinicaltrials.gov (NCT02338388)]. The study included 435 women. Six weeks after delivery, the incidence of niche was not significantly different between the groups (p = 0.52): 40% for single-layer unlocked, 32% for single-layer locked and 43% for double-layer sutures. The mean ± SD niche depths were 3.0 ± 1.4 mm for single-layer unlocked, 3.6 ± 1.7 mm for single-layer locked and 3.3 ± 1.3 mm for double-layer sutures (p = 1.0). There were no significant differences (p = 0.58) in niche incidence between the three groups at the second ultrasound follow up: 30% for single-layer unlocked, 23% for single-layer locked and 29% for double-layer sutures. The mean ± SD niche depth was 3.1 ± 1.5 mm after single-layer unlocked, 2.8 ± 1.5 mm after single-layer locked and 2.5 ± 1.2 mm after double-layer sutures (p = 0.61). There was a trend (p = 0.06) for the residual myometrium thickness to be thicker after double-layer repair at the long-term follow up. The incidence of cesarean scar niche formation and the niche depth was independent of the hysterotomy closure technique. © 2017 Nordic Federation of Societies of Obstetrics and Gynecology.

Developments of the Physical and Electrical Properties of NiCr and NiCrSi Single-Layer and Bi-Layer Nano-Scale Thin-Film Resistors.

PubMed

Cheng, Huan-Yi; Chen, Ying-Chung; Li, Chi-Lun; Li, Pei-Jou; Houng, Mau-Phon; Yang, Cheng-Fu

2016-02-25

In this study, commercial-grade NiCr (80 wt % Ni, 20 wt % Cr) and NiCrSi (55 wt % Ni, 40 wt % Cr, 5 wt % Si) were used as targets and the sputtering method was used to deposit NiCr and NiCrSi thin films on Al₂O₃ and Si substrates at room temperature under different deposition time. X-ray diffraction patterns showed that the NiCr and NiCrSi thin films were amorphous phase, and the field-effect scanning electronic microscope observations showed that only nano-crystalline grains were revealed on the surfaces of the NiCr and NiCrSi thin films. The log (resistivity) values of the NiCr and NiCrSi thin-film resistors decreased approximately linearly as their thicknesses increased. We found that the value of temperature coefficient of resistance (TCR value) of the NiCr thin-film resistors was positive and that of the NiCrSi thin-film resistors was negative. To investigate these thin-film resistors with a low TCR value, we designed a novel bi-layer structure to fabricate the thin-film resistors via two different stacking methods. The bi-layer structures were created by depositing NiCr for 10 min as the upper (or lower) layer and depositing NiCrSi for 10, 30, or 60 min as the lower (or upper) layer. We aim to show that the stacking method had no apparent effect on the resistivity of the NiCr-NiCrSi bi-layer thin-film resistors but had large effect on the TCR value.

Developments of the Physical and Electrical Properties of NiCr and NiCrSi Single-Layer and Bi-Layer Nano-Scale Thin-Film Resistors

PubMed Central

Cheng, Huan-Yi; Chen, Ying-Chung; Li, Chi-Lun; Li, Pei-Jou; Houng, Mau-Phon; Yang, Cheng-Fu

2016-01-01

In this study, commercial-grade NiCr (80 wt % Ni, 20 wt % Cr) and NiCrSi (55 wt % Ni, 40 wt % Cr, 5 wt % Si) were used as targets and the sputtering method was used to deposit NiCr and NiCrSi thin films on Al2O3 and Si substrates at room temperature under different deposition time. X-ray diffraction patterns showed that the NiCr and NiCrSi thin films were amorphous phase, and the field-effect scanning electronic microscope observations showed that only nano-crystalline grains were revealed on the surfaces of the NiCr and NiCrSi thin films. The log (resistivity) values of the NiCr and NiCrSi thin-film resistors decreased approximately linearly as their thicknesses increased. We found that the value of temperature coefficient of resistance (TCR value) of the NiCr thin-film resistors was positive and that of the NiCrSi thin-film resistors was negative. To investigate these thin-film resistors with a low TCR value, we designed a novel bi-layer structure to fabricate the thin-film resistors via two different stacking methods. The bi-layer structures were created by depositing NiCr for 10 min as the upper (or lower) layer and depositing NiCrSi for 10, 30, or 60 min as the lower (or upper) layer. We aim to show that the stacking method had no apparent effect on the resistivity of the NiCr-NiCrSi bi-layer thin-film resistors but had large effect on the TCR value. PMID:28344296

Resonance line transfer calculations by doubling thin layers. I - Comparison with other techniques. II - The use of the R-parallel redistribution function. [planetary atmospheres

NASA Technical Reports Server (NTRS)

Yelle, Roger V.; Wallace, Lloyd

1989-01-01

A versatile and efficient technique for the solution of the resonance line scattering problem with frequency redistribution in planetary atmospheres is introduced. Similar to the doubling approach commonly used in monochromatic scattering problems, the technique has been extended to include the frequency dependence of the radiation field. Methods for solving problems with external or internal sources and coupled spectral lines are presented, along with comparison of some sample calculations with results from Monte Carlo and Feautrier techniques. The doubling technique has also been applied to the solution of resonance line scattering problems where the R-parallel redistribution function is appropriate, both neglecting and including polarization as developed by Yelle and Wallace (1989). With the constraint that the atmosphere is illuminated from the zenith, the only difficulty of consequence is that of performing precise frequency integrations over the line profiles. With that problem solved, it is no longer necessary to use the Monte Carlo method to solve this class of problem.

Mechanically activated artificial cell by using microfluidics

NASA Astrophysics Data System (ADS)

Ho, Kenneth K. Y.; Lee, Lap Man; Liu, Allen P.

2016-09-01

All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology.

Monitoring the layer-by-layer self-assembly of graphene and graphene oxide by spectroscopic ellipsometry.

PubMed

Zhou, Kai-Ge; Chang, Meng-Jie; Wang, Hang-Xing; Xie, Yu-Long; Zhang, Hao-Li

2012-01-01

Thin films of graphene oxide, graphene and copper (II) phthalocyanine dye have been successfully fabricated by electrostatic layer-by-layer (LbL) assembly approach. We present the first variable angle spectroscopic ellipsometry (VASE) investigation on these graphene-dye hybrid thin films. The thickness evaluation suggested that our LbL assembly process produces highly uniform and reproducible thin films. We demonstrate that the refractive indices of the graphene-dye thin films undergo dramatic variation in the range close to the absorption of the dyes. This investigation provides new insight to the optical properties of graphene containing thin films and shall help to establish an appropriate optical model for graphene-based hybrid materials.

Discharging dynamics in an electrolytic cell

NASA Astrophysics Data System (ADS)

Feicht, Sarah E.; Frankel, Alexandra E.; Khair, Aditya S.

2016-07-01

We analyze the dynamics of a discharging electrolytic cell comprised of a binary symmetric electrolyte between two planar, parallel blocking electrodes. When a voltage is initially applied, ions in the electrolyte migrate towards the electrodes, forming electrical double layers. After the system reaches steady state and the external current decays to zero, the applied voltage is switched off and the cell discharges, with the ions eventually returning to a uniform spatial concentration. At voltages on the order of the thermal voltage VT=kBT /q ≃25 mV, where kB is Boltzmann's constant, T is temperature, and q is the charge of a proton, experiments on surfactant-doped nonpolar fluids observe that the temporal evolution of the external current during charging and discharging is not symmetric [V. Novotny and M. A. Hopper, J. Electrochem. Soc. 126, 925 (1979), 10.1149/1.2129195; P. Kornilovitch and Y. Jeon, J. Appl. Phys. 109, 064509 (2011), 10.1063/1.3554445]. In fact, at sufficiently large voltages (several VT), the current during discharging is no longer monotonic: it displays a "reverse peak" before decaying in magnitude to zero. We analyze the dynamics of discharging by solving the Poisson-Nernst-Planck equations governing ion transport via asymptotic and numerical techniques in three regimes. First, in the "linear regime" when the applied voltage V is formally much less than VT, the charging and discharging currents are antisymmetric in time; however, the potential and charge density profiles during charging and discharging are asymmetric. The current evolution is on the R C timescale of the cell, λDL /D , where L is the width of the cell, D is the diffusivity of ions, and λD is the Debye length. Second, in the (experimentally relevant) thin-double-layer limit ɛ =λD/L ≪1 , there is a "weakly nonlinear" regime defined by VT≲V ≲VTln(1 /ɛ ) , where the bulk salt concentration is uniform; thus the R C timescale of the evolution of the current magnitude persists. However, nonlinear, voltage-dependent, capacitance of the double layer is responsible for a break in temporal antisymmetry of the charging and discharging currents. Third, the reverse peak in the discharging current develops in a "strongly nonlinear" regime V ≳VTln(1 /ɛ ) , driven by neutral salt adsorption into the double layers and consequent bulk depletion during charging. The strongly nonlinear regime features current evolution over three timescales. The current decays in magnitude on the double layer relaxation timescale, λD2/D ; then grows exponentially in time towards the reverse peak on the diffusion timescale, L2/D , indicating that the reverse peak is the results of fast diffusion of ions from the double layer layer to the bulk. Following the reverse peak, the current decays exponentially to zero on the R C timescale. Notably, the current at the reverse peak and the time of the reverse peak saturate at large voltages V ≫VTln(1 /ɛ ) . We provide semi-analytic expressions for the saturated reverse peak time and current, which can be used to infer charge carrier diffusivity and concentration from experiments.

Influences of Indium Tin Oxide Layer on the Properties of RF Magnetron-Sputtered (BaSr)TiO3 Thin Films on Indium Tin Oxide-Coated Glass Substrate

NASA Astrophysics Data System (ADS)

Kim, Tae Song; Oh, Myung Hwan; Kim, Chong Hee

1993-06-01

Nearly stoichiometric ((Ba+Sr)/Ti=1.08-1.09) and optically transparent (BaSr)TiO3 thin films were deposited on an indium tin oxide (ITO)-coated glass substrate by means of rf magnetron sputtering for their application to the insulating layer of an electroluminescent flat panel display. The influence of the ITO layer on the properties of (BaSr)TiO3 thin films deposited on the ITO-coated substrate was investigated. The ITO layer did not affect the crystallographic orientation of (BaSr)TiO3 thin film, but enhanced the grain growth. Another effect of the ITO layer on (BaSr)TiO3 thin films was the interdiffusion phenomenon, which was studied by means of secondary ion mass spectrometry (SIMS). As the substrate temperature increased, interdiffusion intensified at the interface not only between the grown film and ITO layer but also between the ITO layer and base glass substrate. The refractive index (nf) of (BaSr)TiO3 thin film deposited on a bare glass substrate was 2.138-2.286, as a function of substrate temperature.

Synthesis and adsorption properties of flower-like layered double hydroxide by a facile one-pot reaction with an eggshell membrane as assistant

NASA Astrophysics Data System (ADS)

Li, Songnan; Zhang, Jiawei; Jamil, Saba; Cai, Qinghai; Zang, Shuying

In this paper, flower-like layered double hydroxides were synthesized with eggshell membrane assistant. The as-prepared samples were characterized by a series of techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermal gravity-differential thermal analysis and Nitrogen sorption/desorption. The resulting layered double hydroxides were composed of nanoplates with edge-to-face particle interactions. The specific surface area and total pore volume of the as-prepared flower-like layered double hydroxides were 160m2/g and 0.65m3/g, respectively. The adsorption capacity of flower-like layered double hydroxides to Congo Red was 258mg/g, which was higher than that of layered double hydroxides synthesized by the traditional method.

Corrosion-resistant multilayer structures with improved reflectivity

DOEpatents

Soufli, Regina; Fernandez-Perea, Monica; Robinson, Jeff C.

2013-04-09

In one general embodiment, a thin film structure includes a substrate; a first corrosion barrier layer above the substrate; a reflective layer above the first corrosion barrier layer, wherein the reflective layer comprises at least one repeating set of sub-layers, wherein one of the sub-layers of each set of sub-layers being of a corrodible material; and a second corrosion barrier layer above the reflective layer. In another general embodiment, a system includes an optical element having a thin film structure as recited above; and an image capture or spectrometer device. In a further general embodiment, a laser according to one embodiment includes a light source and the thin film structure as recited above.

Internal hypersonic flow. [in thin shock layer

NASA Technical Reports Server (NTRS)

Lin, T. C.; Rubin, S. G.

1974-01-01

An approach for studying hypersonic internal flow with the aid of a thin-shock-layer approximation is discussed, giving attention to a comparison of thin-shock-layer results with the data obtained on the basis of the imposition theory or a finite-difference integration of the Euler equations. Relations in the case of strong interaction are considered together with questions of pressure distribution and aspects of the boundary-layer solution.

Methods for producing thin film charge selective transport layers

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

Hammond, Scott Ryan; Olson, Dana C.; van Hest, Marinus Franciscus Antonius Maria

Methods for producing thin film charge selective transport layers are provided. In one embodiment, a method for forming a thin film charge selective transport layer comprises: providing a precursor solution comprising a metal containing reactive precursor material dissolved into a complexing solvent; depositing the precursor solution onto a surface of a substrate to form a film; and forming a charge selective transport layer on the substrate by annealing the film.

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%.

Growth and optical property characterization of textured barium titanate thin films for photonic applications

NASA Astrophysics Data System (ADS)

Dicken, Matthew J.; Diest, Kenneth; Park, Young-Bae; Atwater, Harry A.

2007-03-01

We have investigated the growth of barium titanate thin films on bulk crystalline and amorphous substrates utilizing biaxially oriented template layers. Ion beam-assisted deposition was used to grow thin, biaxially textured, magnesium oxide template layers on amorphous and silicon substrates. Growth of highly oriented barium titanate films on these template layers was achieved by molecular beam epitaxy using a layer-by-layer growth process. Barium titanate thin films were grown in molecular oxygen and in the presence of oxygen radicals produced by a 300 W radio frequency plasma. We used X-ray and in situ reflection high-energy electron diffraction (RHEED) to analyze the structural properties and show the predominantly c-oriented grains in the films. Variable angle spectroscopic ellipsometry was used to analyze and compare the optical properties of the thin films grown with and without oxygen plasma. We have shown that optical quality barium titanate thin films, which show bulk crystal-like properties, can be grown on any substrate through the use of biaxially oriented magnesium oxide template layers.

Tribological Properties of TiO2/SiO2 Double Layer Coatings Deposited on CP-Ti

NASA Astrophysics Data System (ADS)

Çomakli, O.; Yazici, M.; Yetim, T.; Yetim, A. F.; Çelik, A.

In the present paper, the influences of different double layer on wear and scratch performances of commercially pure Titanium (CP-Ti) were investigated. TiO2/SiO2 and SiO2/TiO2 double layer coatings were deposited on CP-Ti by sol-gel dip coating process and calcined at 750∘C. The phase structure, cross-sectional morphology, composition, wear track morphologies, adhesion properties, hardness and roughness of uncoated and coated samples were characterized with X-ray diffraction, scanning electron microscopy (SEM), nano-indentation technique, scratch tester and 3D profilometer. Also, the tribological performances of all samples were investigated by a pin-on-disc tribo-tester against Al2O3 ball. Results showed that hardness, elastic modulus and adhesion resistance of double layer coated samples were higher than untreated CP-Ti. It was found that these properties of TiO2/SiO2 double layer coatings have higher than SiO2/TiO2 double layer coating. Additionally, the lowest friction coefficient and wear rates were obtained from TiO2/SiO2 double layer coatings. Therefore, it was seen that phase structure, hardness and film adhesion are important factors on the tribological properties of double layer coatings.

Effect of different coating layer on the topography and optical properties of ZnO nanostructured

NASA Astrophysics Data System (ADS)

Mohamed, R.; Mamat, M. H.; Malek, M. F.; Ismail, A. S.; Yusoff, M. M.; Asiah, M. N.; Khusaimi, Z.; Rusop, M.

2018-05-01

Magnesium (Mg) and aluminum (Al) co-doped zinc oxide (MAZO) thin films were synthesized on glass substrate by sol-gel spin coating method. MAZO thin films were prepared at different coating layers range from 1 to 9. Atomic Force Microscopy (AFM) was used to investigate the topography of the thin films. According to the AFM results, Root Means Square (RMS) of MAZO thin films was increased from 0.747 to 6.545 nm, with increase of number coating layer from 1 to 9, respectively. The results shown the variation on structural and topography properties of MAZO seed film when it's deposited at different coating layers on glass substrate. The optical properties was analyzed using UV-Vis spectroscopy. The obtained results show that the transmittance spectra was increased as thin films coating layer increases.

Thin layer model for nonlinear evolution of the Rayleigh-Taylor instability

NASA Astrophysics Data System (ADS)

Zhao, K. G.; Wang, L. F.; Xue, C.; Ye, W. H.; Wu, J. F.; Ding, Y. K.; Zhang, W. Y.

2018-03-01

On the basis of the thin layer approximation [Ott, Phys. Rev. Lett. 29, 1429 (1972)], a revised thin layer model for incompressible Rayleigh-Taylor instability has been developed to describe the deformation and nonlinear evolution of the perturbed interface. The differential equations for motion are obtained by analyzing the forces (the gravity and pressure difference) of fluid elements (i.e., Newton's second law). The positions of the perturbed interface are obtained from the numerical solution of the motion equations. For the case of vacuum on both sides of the layer, the positions of the upper and lower interfaces obtained from the revised thin layer approximation agree with that from the weakly nonlinear (WN) model of a finite-thickness fluid layer [Wang et al., Phys. Plasmas 21, 122710 (2014)]. For the case considering the fluids on both sides of the layer, the bubble-spike amplitude from the revised thin layer model agrees with that from the WN model [Wang et al., Phys. Plasmas 17, 052305 (2010)] and the expanded Layzer's theory [Goncharov, Phys. Rev. Lett. 88, 134502 (2002)] in the early nonlinear growth regime. Note that the revised thin layer model can be applied to investigate the perturbation growth at arbitrary Atwood numbers. In addition, the large deformation (the large perturbed amplitude and the arbitrary perturbed distributions) in the initial stage can also be described by the present model.

Polysulfide intercalated layered double hydroxides for metal capture applications

DOEpatents

Kanatzidis, Mercouri G.; Ma, Shulan

2017-04-04

Polysulfide intercalated layered double hydroxides and methods for their use in vapor and liquid-phase metal capture applications are provided. The layered double hydroxides comprise a plurality of positively charged host layers of mixed metal hydroxides separated by interlayer spaces. Polysulfide anions are intercalated in the interlayer spaces.

Two-dimensional models for the optical response of thin films

NASA Astrophysics Data System (ADS)

Li, Yilei; Heinz, Tony F.

2018-04-01

In this work, we present a systematic study of 2D optical models for the response of thin layers of material under excitation by normally incident light. The treatment, within the framework of classical optics, analyzes a thin film supported by a semi-infinite substrate, with both the thin layer and the substrate assumed to exhibit local, isotropic linear response. Starting from the conventional three-dimensional (3D) slab model of the system, we derive a two-dimensional (2D) sheet model for the thin film in which the optical response is described by a sheet optical conductivity. We develop criteria for the applicability of this 2D sheet model for a layer with an optical thickness far smaller than the wavelength of the light. We examine in detail atomically thin semi-metallic and semiconductor van-der-Waals layers and ultrathin metal films as representative examples. Excellent agreement of the 2D sheet model with the 3D slab model is demonstrated over a broad spectral range from the radio frequency limit to the near ultraviolet. A linearized version of system response for the 2D model is also presented for the case where the influence of the optically thin layer is sufficiently weak. Analytical expressions for the applicability and accuracy of the different optical models are derived, and the appropriateness of the linearized treatment for the materials is considered. We discuss the advantages, as well as limitations, of these models for the purpose of deducing the optical response function of the thin layer from experiment. We generalize the theory to take into account in-plane anisotropy, layered thin film structures, and more general substrates. Implications of the 2D model for the transmission of light by the thin film and for the implementation of half- and totally absorbing layers are discussed.

Capacitance of carbon-based electrical double-layer capacitors.

PubMed

Ji, Hengxing; Zhao, Xin; Qiao, Zhenhua; Jung, Jeil; Zhu, Yanwu; Lu, Yalin; Zhang, Li Li; MacDonald, Allan H; Ruoff, Rodney S

2014-01-01

Experimental electrical double-layer capacitances of porous carbon electrodes fall below ideal values, thus limiting the practical energy densities of carbon-based electrical double-layer capacitors. Here we investigate the origin of this behaviour by measuring the electrical double-layer capacitance in one to five-layer graphene. We find that the capacitances are suppressed near neutrality, and are anomalously enhanced for thicknesses below a few layers. We attribute the first effect to quantum capacitance effects near the point of zero charge, and the second to correlations between electrons in the graphene sheet and ions in the electrolyte. The large capacitance values imply gravimetric energy storage densities in the single-layer graphene limit that are comparable to those of batteries. We anticipate that these results shed light on developing new theoretical models in understanding the electrical double-layer capacitance of carbon electrodes, and on opening up new strategies for improving the energy density of carbon-based capacitors.

Initial formation of calcite crystals in the thin prismatic layer with the periostracum of Pinctada fucata.

PubMed

Suzuki, Michio; Nakayama, Seiji; Nagasawa, Hiromichi; Kogure, Toshihiro

2013-02-01

Although the formation mechanism of calcite crystals in the prismatic layer has been studied well in many previous works, the initial state of calcite formation has not been observed in detail using electron microscopes. In this study, we report that the soft prismatic layer with transparent color (the thin prismatic layer) in the tip of the fresh shell of Pinctada fucata was picked up to observe the early calcification phase. A scanning electron microscope (SEM) image showed that the growth tip of the thin prismatic layer was covered by the periostracum, which was also where the initial formation of calcite crystals began. A cross-section containing the thin calcite crystals in the thin prismatic layer with the periostracum was made using a focused ion beam (FIB) system. In a transmission electron microscope (TEM) observation, the thin calcite crystal (thickness is about 1μm) on the periostracum was found to be a single crystal with the c-axis oriented perpendicular to the shell surface. On the other hand, many aggregated small particles consisting of bassanite crystals were observed in the periostracum suggesting the possibility that not only organic sulfate but also inorganic sulfates exist in the prismatic layer. These discoveries in the early calcification phase of the thin prismatic layer may help to clarify the mechanism of regulating the nucleation and orientation of the calcite crystal in the shell. Copyright © 2012 Elsevier Ltd. All rights reserved.

A Prospective Randomized Clinical Trial of Single vs. Double Layer Closure of Hysterotomy at the Time of Cesarean Delivery: The Effect on Uterine Scar Thickness.

PubMed

Bamberg, Christian; Dudenhausen, Joachim W; Bujak, Verena; Rodekamp, Elke; Brauer, Martin; Hinkson, Larry; Kalache, Karim; Henrich, Wolfgang

2018-06-01

 We undertook a randomized clinical trial to examine the outcome of a single vs. a double layer uterine closure using ultrasound to assess uterine scar thickness.  Participating women were allocated to one of three uterotomy suture techniques: continuous single layer unlocked suturing, continuous locked single layer suturing, or double layer suturing. Transvaginal ultrasound of uterine scar thickness was performed 6 weeks and 6 - 24 months after Cesarean delivery. Sonographers were blinded to the closure technique.  An "intent-to-treat" and "as treated" ANOVA analysis included 435 patients (n = 149 single layer unlocked suturing, n = 157 single layer locked suturing, and n = 129 double layer suturing). 6 weeks postpartum, the median scar thickness did not differ among the three groups: 10.0 (8.5 - 12.3 mm) single layer unlocked vs. 10.1 (8.2 - 12.7 mm) single layer locked vs. 10.8 (8.1 - 12.8 mm) double layer; (p = 0.84). At the time of the second follow-up, the uterine scar was not significantly (p = 0.06) thicker if the uterus had been closed with a double layer closure 7.3 (5.7 - 9.1 mm), compared to single layer unlocked 6.4 (5.0 - 8.8 mm) or locked suturing techniques 6.8 (5.2 - 8.7 mm). Women who underwent primary or elective Cesarean delivery showed a significantly (p = 0.03, p = 0.02, "as treated") increased median scar thickness after double layer closure vs. single layer unlocked suture.  A double layer closure of the hysterotomy is associated with a thicker myometrium scar only in primary or elective Cesarean delivery patients. © Georg Thieme Verlag KG Stuttgart · New York.

Buffer layers for high-Tc thin films on sapphire

NASA Technical Reports Server (NTRS)

Wu, X. D.; Foltyn, S. R.; Muenchausen, R. E.; Cooke, D. W.; Pique, A.; Kalokitis, D.; Pendrick, V.; Belohoubek, E.

1992-01-01

Buffer layers of various oxides including CeO2 and yttrium-stabilized zirconia (YSZ) have been deposited on R-plane sapphire. The orientation and crystallinity of the layers were optimized to promote epitaxial growth of YBa2Cu3O(7-delta) (YBCO) thin films. An ion beam channeling minimum yield of about 3 percent was obtained in the CeO2 layer on sapphire, indicating excellent crystallinity of the buffer layer. Among the buffer materials used, CeO2 was found to be the best one for YBCO thin films on R-plane sapphire. High Tc and Jc were obtained in YBCO thin films on sapphire with buffer layers. Surface resistances of the YBCO films were about 4 mOmega at 77 K and 25 GHz.

Re-Usable Thin-Layer Spectroelectrochemical Cell for Non-Aqueous Solvent Systems.

DTIC Science & Technology

1987-11-01

rapidly reassembied. It can be used under 1-gassei .I I. wIII aquleous solution or a variety of comon rg-an Ic 1 ,+.t r . -, 1 1 soivenrts , u( h as o...for 1 days. Lithium chloride (Anachemia, reagent grade) was dried at 12ooC for 24 h. Water was purified by double distillation over KMnO4, foiluwed by...peak to peaK 3eparatiun witn ;r-’ra.in scan rate from Ib mV at lmV/s to lUU mV at lUU mv/. r-eaK IC , ,:.ik ;eparatiurts measured at several scan rates

Investigation of the thickness non-uniformity of the very thin silicon-strip detectors

NASA Astrophysics Data System (ADS)

Liu, Qiang; Ye, Yanlin; Li, Zhihuan; Lin, Chengjian; Jia, Huiming; Ge, Yucheng; Li, Qite; Lou, Jianling; Yang, Xiaofei; Yang, Biao; Feng, Jun; Zang, Hongliang; Chen, Zhiqiang; Liu, Yang; Liu, Wei; Chen, Sidong; Yu, Hanzhou; Li, Jingjing; Zhang, Yun; Yang, Feng; Yang, Lei; Ma, Nanru; Sun, Lijie; Wang, Dongxi

2018-07-01

The properties of some very thin (∼ 20 μm) large-area Single-sided Silicon-Strip Detectors (SSSDs) were investigated by using the 12C-particles elastically scattered from a Au target. In the detection system, each thin SSSD was installed in front of a thick (300 μm or 500 μm) Double-sided Silicon-Strip Detector (DSSD) to form a ΔE - E particle-telescope. The energy calibration of these detectors was realized by varying the beam energy and also by the irradiation from a three-component α-particle source. The thickness distribution each SSSD is precisely determined from the energy loss in the thin layer, which was independently measured by the corresponding DSSD. It is found that, for the SSSD with the nominal thicknesses of ∼ 20 μm, the real thickness may vary by several μm over the active area. The reason for this large non-uniformity still needs to be investigated. For the present application, this non-uniformity could be corrected according to the known pixel-thickness. This correction allows to restore a good particle identification (PID) performance for the entire large-area detector, the importance of which is demonstrated by an example of measuring the cluster-decays of the highly-excited resonant states in 16O.

Critical current enhancement driven by suppression of superconducting fluctuation in ion-gated ultrathin FeSe

NASA Astrophysics Data System (ADS)

Harada, T.; Shiogai, J.; Miyakawa, T.; Nojima, T.; Tsukazaki, A.

2018-05-01

The framework of phase transition, such as superconducting transition, occasionally depends on the dimensionality of materials. Superconductivity is often weakened in the experimental conditions of two-dimensional thin films due to the fragile superconducting state against defects and interfacial effects. In contrast to this general trend, superconductivity in the thin limit of FeSe exhibits an opposite trend, such as an increase in critical temperature (T c) and the superconducting gap exceeding the bulk values; however, the dominant mechanism is still under debate. Here, we measured thickness-dependent electrical transport properties of the ion-gated FeSe thin films to evaluate the superconducting critical current (I c) in the ultrathin FeSe. Upon systematically decreasing the FeSe thickness by the electrochemical etching technique in the Hall bar-shaped electric double-layer transistors, we observed a dramatic enhancement of I c reaching about 10 mA and corresponding to about 107 A cm‑2 in the thinnest condition. By analyzing the transition behavior, we clarify that the suppressed superconducting fluctuation is one of the origins of the large I c in the ion-gated ultrathin FeSe films. These results indicate the existence of a robust superconducting state possibly with dense Cooper pairs at the thin limit of FeSe.

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.

Layered ultra-thin coherent structures used as electrical resistors having low-temperature coefficient of resistivity

DOEpatents

Werner, T.R.; Falco, C.M.; Schuller, I.K.

1982-08-31

A thin film resistor having a controlled temperature coefficient of resistance (TCR) ranging from negative to positive degrees kelvin and having relatively high resistivity. The resistor is a multilayer superlattice crystal containing a plurality of alternating, ultra-thin layers of two different metals. TCR is varied by controlling the thickness of the individual layers. The resistor can be readily prepared by methods compatible with thin film circuitry manufacturing techniques.

Laboratory observation of multiple double layer resembling space plasma double layer

NASA Astrophysics Data System (ADS)

Alex, Prince; Arumugam, Saravanan; Sinha, Suraj

2017-10-01

Perceptible double layer consisting of more than one layers were produced in laboratory using a double discharge plasma setup. The confinement of oppositely charged particles in each layer with sharply defined luminous boarder is attributed to the self-organization scenario. This structure is generated in front of a positively biased electrode when the electron drift velocity (νd) exceeds 1.3 times the electron thermal velocity (νte) . Stable multiple double layer structures were observed only between 1.3 νte <=νd <= 3 νte. At νd = 1.3 νte, oscillations were excited in the form of large amplitude burst followed by a high frequency stable oscillation. Beyond νd = 3 νte, multiple double layer begins to collapse which is characterized by an emergence in turbulence. Long range dependence in the corresponding electrostatic potential fluctuations indicates the role of self-organized criticality in the emergence of turbulence. The algebraic decaying tale of the autocorrelation function and power law behavior in the power spectrum are consistent with the observation.

Effect of ZnO buffer layer on phase transition properties of vanadium dioxide thin films

NASA Astrophysics Data System (ADS)

Zhu, Huiqun; Li, Lekang; Li, Chunbo

2016-03-01

VO2 thin films were prepared on ZnO buffer layers by DC magnetron sputtering at room temperature using vanadium target and post annealing at 400 °C. The ZnO buffer layers with different thickness deposited on glass substrates by magnetron sputtering have a high visible and near infrared optical transmittance. The electrical resistivity and the phase transition properties of the VO2/ZnO composite thin films in terms of temperature were investigated. The results showed that the resistivity variation of VO2 thin film with ZnO buffer layer deposited for 35 min was 16 KΩ-cm. The VO2/ZnO composite thin films exhibit a reversible semiconductor-metal phase transition at 48 °C.

Thin-Layer Fuel Cell for Teaching and Classroom Demonstrations

ERIC Educational Resources Information Center

Shirkhanzadeh, M.

2009-01-01

A thin-layer fuel cell is described that is simple and easy to set up and is particularly useful for teaching and classroom demonstrations. The cell is both an electrolyzer and a fuel cell and operates using a thin layer of electrolyte with a thickness of approximately 127 micrometers and a volume of approximately 40 microliters. As an…

Optical characterizations of silver nanoprisms embedded in polymer thin film layers

NASA Astrophysics Data System (ADS)

Carlberg, Miriam; Pourcin, Florent; Margeat, Olivier; Le Rouzo, Judikael; Berginc, Gerard; Sauvage, Rose-Marie; Ackermann, Jorg; Escoubas, Ludovic

2017-10-01

The precise control of light-matter interaction has a wide range of applications and is currently driven by the use of nanoparticles (NPs) by the recent advances in nanotechnology. Taking advantage of the material, size, shape, and surrounding media dependence of the optical properties of plasmonic NPs, thin film layers with tunable optical properties are achieved. The NPs are synthesized by wet chemistry and embedded in a polyvinylpyrrolidone (PVP) polymer thin film layer. Spectrophotometer and spectroscopic ellipsometry measurements are coupled to finite-difference time domain numerical modeling to optically characterize the heterogeneous thin film layers. Silver nanoprisms of 10 to 50 nm edge size exhibit high absorption through the visible wavelength range. A simple optical model composed of a Cauchy law and a Lorentz law, accounting for the optical properties of the nonabsorbing polymer and the absorbing property of the nanoprisms, fits the spectroscopic ellipsometry measurements. Knowing the complex optical indices of heterogeneous thin film layers let us design layers of any optical properties.

Double layers and circuits in astrophysics

NASA Technical Reports Server (NTRS)

Alfven, H.

1986-01-01

A simple circuit is applied to the energizing of auroral particles, to solar flares, and to intergalactic double radio sources. Application to the heliospheric current systems leads to the prediction of two double layers on the Sun's axis which may give radiations detectable from Earth. Double layers in space should be classified as a new type of celestial object. It is suggested that X-ray and gamma-ray bursts may be due to exploding double layers (although annihilation is an alternative energy source). The way the most used textbooks in astrophysics treat concepts like double layers, critical velocity, pinch effects and circuits was studied. It is found that students using these textbooks remain essentially ignorant of even the existence of these, although some of the phenomena were discovered 50 yr ago.

Experimental evidence of mobility enhancement in short-channel ultra-thin body double-gate MOSFETs by magnetoresistance technique

NASA Astrophysics Data System (ADS)

Chaisantikulwat, W.; Mouis, M.; Ghibaudo, G.; Cristoloveanu, S.; Widiez, J.; Vinet, M.; Deleonibus, S.

2007-11-01

Double-gate transistor with ultra-thin body (UTB) has proved to offer advantages over bulk device for high-speed, low-power applications. There is thus a strong need to obtain an accurate understanding of carrier transport and mobility in such device. In this work, we report for the first time an experimental evidence of mobility enhancement in UTB double-gate (DG) MOSFETs using magnetoresistance mobility extraction technique. Mobility in planar DG transistor operating in single- and double-gate mode is compared. The influence of different scattering mechanisms in the channel is also investigated by obtaining mobility values at low temperatures. The results show a clear mobility improvement in double-gate mode compared to single-gate mode mobility at the same inversion charge density. This is explained by the role of volume inversion in ultra-thin body transistor operating in DG mode. Volume inversion is found to be especially beneficial in terms of mobility gain at low-inversion densities.

Extracting elastic properties of an atomically thin interfacial layer by time-domain analysis of femtosecond acoustics

NASA Astrophysics Data System (ADS)

Chen, H.-Y.; Huang, Y.-R.; Shih, H.-Y.; Chen, M.-J.; Sheu, J.-K.; Sun, C.-K.

2017-11-01

Modern devices adopting denser designs and complex 3D structures have created much more interfaces than before, where atomically thin interfacial layers could form. However, fundamental information such as the elastic property of the interfacial layers is hard to measure. The elastic property of the interfacial layer is of great importance in both thermal management and nano-engineering of modern devices. Appropriate techniques to probe the elastic properties of interfacial layers as thin as only several atoms are thus critically needed. In this work, we demonstrated the feasibility of utilizing the time-resolved femtosecond acoustics technique to extract the elastic properties and mass density of a 1.85-nm-thick interfacial layer, with the aid of transmission electron microscopy. We believe that this femtosecond acoustics approach will provide a strategy to measure the absolute elastic properties of atomically thin interfacial layers.

Switchable silver mirrors with long memory effects.

PubMed

Park, Chihyun; Seo, Seogjae; Shin, Haijin; Sarwade, Bhimrao D; Na, Jongbeom; Kim, Eunkyoung

2015-01-01

An electrochemically stable and bistable switchable mirror was achieved for the first time by introducing (1) a thiol-modified indium tin oxide (ITO) electrode for the stabilization of the metallic film and (2) ionic liquids as an anion-blocking layer, to achieve a long memory effect. The growth of the metallic film was denser and faster at the thiol-modified ITO electrode than at a bare ITO electrode. The electrochemical stability of the metallic film on the thiol-modified ITO was enhanced, maintaining the metallic state without rupture. In the voltage-off state, the metal film maintained bistability for a long period (>2 h) when ionic liquids were introduced as electrolytes for the switchable mirror. The electrical double layer in the highly viscous ionic liquid electrolyte seemed to effectively form a barrier to the bromide ions, to protect the metal thin film from them when in the voltage-off state.

Toward maximum transmittance into absorption layers in solar cells: investigation of lossy-film-induced mismatches between reflectance and transmittance extrema.

PubMed

Chang, Yin-Jung; Lai, Chi-Sheng

2013-09-01

The mismatch in film thickness and incident angle between reflectance and transmittance extrema due to the presence of lossy film(s) is investigated toward the maximum transmittance design in the active region of solar cells. Using a planar air/lossy film/silicon double-interface geometry illustrates important and quite opposite mismatch behaviors associated with TE and TM waves. In a typical thin-film CIGS solar cell, mismatches contributed by TM waves in general dominate. The angular mismatch is at least 10° in about 37%-53% of the spectrum, depending on the thickness combination of all lossy interlayers. The largest thickness mismatch of a specific interlayer generally increases with the thickness of the layer itself. Antireflection coating designs for solar cells should therefore be optimized in terms of the maximum transmittance into the active region, even if the corresponding reflectance is not at its minimum.

Multifocal visual evoked potentials for early glaucoma detection.

PubMed

Weizer, Jennifer S; Musch, David C; Niziol, Leslie M; Khan, Naheed W

2012-07-01

To compare multifocal visual evoked potentials (mfVEP) with other detection methods in early open-angle glaucoma. Ten patients with suspected glaucoma and 5 with early open-angle glaucoma underwent mfVEP, standard automated perimetry (SAP), short-wave automated perimetry, frequency-doubling technology perimetry, and nerve fiber layer optical coherence tomography. Nineteen healthy control subjects underwent mfVEP and SAP for comparison. Comparisons between groups involving continuous variables were made using independent t tests; for categorical variables, Fisher's exact test was used. Monocular mfVEP cluster defects were associated with an increased SAP pattern standard deviation (P = .0195). Visual fields that showed interocular mfVEP cluster defects were more likely to also show superior quadrant nerve fiber layer thinning by OCT (P = .0152). Multifocal visual evoked potential cluster defects are associated with a functional and an anatomic measure that both relate to glaucomatous optic neuropathy. Copyright 2012, SLACK Incorporated.

Paradigm transition in cosmic plasma physics

NASA Technical Reports Server (NTRS)

Alfven, H.

1982-01-01

New discoveries in cosmic plasma physics are described, and their applications to solar, interstellar, galactic, and cosmological problems are discussed. The new discoveries include the existence of double layers in magnetized plasmas and in the low magnetosphere, and energy transfer by electric current in the auroral circuit. It is argued that solar flares and the solar wind-magnetosphere interaction should not be interpreted in terms of magnetic merging theories, and that electric current needs to be explicitly taken account of in understanding these phenomena. The filamentary structure of cosmic plasmas may be caused by electric currents in space, and the pinch effect may have a central role to play in the evolutionary history of interstellar clouds, stars, and solar systems. Space may have a cellular structure, with the cell walls formed by thin electric current layers. Annihilation may be the source of energy for quasars and the Hubble expansion, and the big bang cosmology may well be wrong.

SEMICONDUCTOR TECHNOLOGY Development of spin-on-glass process for triple metal interconnects

NASA Astrophysics Data System (ADS)

Li, Peng; Wenbin, Zhao; Guozhang, Wang; Zongguang, Yu

2010-12-01

Spin-on-glass (SOG), an interlayer dielectric material applied in liquid form to fill narrow gaps in the sub-dielectric surface and thus conducive to planarization, is an alternative to silicon dioxide (SiO2) deposited using PECVD processes. However, its inability to adhere to metal and problems such as cracking prevent the easy application of SOG technology to provide an interlayer dielectric in multilevel metal interconnect circuits, particularly in university processing labs. This paper will show that a thin layer of CVD SiO2 and a curing temperature below the sintering temperature of the metal interconnect layer will promote adhesion, reduce gaps, and prevent cracking. Electron scanning microscope analysis has been used to demonstrate the success of the improved technique. This optimized process has been used in batches of double-poly, triple-metal CMOS wafer fabrication to date.

Determination of the Mass Absorption Coefficient in Two-Layer Ti/V and V/Ti Thin Film Systems by the X-Ray Fluorescence Method

NASA Astrophysics Data System (ADS)

Mashin, N. I.; Chernyaeva, E. A.; Tumanova, A. N.; Gafarova, L. M.

2016-03-01

A new XRF procedure for the determination of the mass absorption coefficient in thin film Ti/V and V/Ti two-layer systems has been proposed. The procedure uses easy-to-make thin-film layers of sputtered titanium and vanadium on a polymer film substrate. Correction coefficients have been calculated that take into account attenuation of primary radiation of the X-ray tube, as well as attenuation of the spectral line of the bottom layer element in the top layer.

High Performance and Highly Reliable ZnO Thin Film Transistor Fabricated by Atomic Layer Deposition for Next Generation Displays

DTIC Science & Technology

2011-08-19

zinc oxide ( ZnO ) thin film as an active channel layer in TFT has become of great interest owing to their specific...630-0192 Japan Phone: +81-743-72-6060 Fax: +81-743-72-6069 E-mail: uraoka@ms.naist.jp Keywords: zinc oxide , thin film transistors , atomic layer...deposition Symposium topic: Transparent Semiconductors Oxides [Abstract] In this study, we fabricated TFTs using ZnO thin film as the

Study on dynamic deformation synchronized measurement technology of double-layer liquid surfaces

NASA Astrophysics Data System (ADS)

Tang, Huiying; Dong, Huimin; Liu, Zhanwei

2017-11-01

Accurate measurement of the dynamic deformation of double-layer liquid surfaces plays an important role in many fields, such as fluid mechanics, biomechanics, petrochemical industry and aerospace engineering. It is difficult to measure dynamic deformation of double-layer liquid surfaces synchronously for traditional methods. In this paper, a novel and effective method for full-field static and dynamic deformation measurement of double-layer liquid surfaces has been developed, that is wavefront distortion of double-wavelength transmission light with geometric phase analysis (GPA) method. Double wavelength lattice patterns used here are produced by two techniques, one is by double wavelength laser, and the other is by liquid crystal display (LCD). The techniques combine the characteristics such as high transparency, low reflectivity and fluidity of liquid. Two color lattice patterns produced by laser and LCD were adjusted at a certain angle through the tested double-layer liquid surfaces simultaneously. On the basis of the refractive indexes difference of two transmitted lights, the double-layer liquid surfaces were decoupled with GPA method. Combined with the derived relationship between phase variation of transmission-lattice patterns and out-of plane heights of two surfaces, as well as considering the height curves of the liquid level, the double-layer liquid surfaces can be reconstructed successfully. Compared with the traditional measurement method, the developed method not only has the common advantages of the optical measurement methods, such as high-precision, full-field and non-contact, but also simple, low cost and easy to set up.

Domain matched epitaxial growth of (111) Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films on (0001) Al{sub 2}O{sub 3} with ZnO buffer layer

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

Krishnaprasad, P. S., E-mail: pskrishnaprasu@gmail.com, E-mail: mkj@cusat.ac.in; Jayaraj, M. K., E-mail: pskrishnaprasu@gmail.com, E-mail: mkj@cusat.ac.in; Antony, Aldrin

2015-03-28

Epitaxial (111) Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) thin films have been grown by pulsed laser deposition on (0001) Al{sub 2}O{sub 3} substrate with ZnO as buffer layer. The x-ray ω-2θ, Φ-scan and reciprocal space mapping indicate epitaxial nature of BST thin films. The domain matched epitaxial growth of BST thin films over ZnO buffer layer was confirmed using Fourier filtered high resolution transmission electron microscope images of the film-buffer interface. The incorporation of ZnO buffer layer effectively suppressed the lattice mismatch and promoted domain matched epitaxial growth of BST thin films. Coplanar inter digital capacitors fabricated on epitaxial (111) BSTmore » thin films show significantly improved tunable performance over polycrystalline thin films.« less

Preparation and characterization of flexible asymmetric supercapacitors based on transition-metal-oxide nanowire/single-walled carbon nanotube hybrid thin-film electrodes.

PubMed

Chen, Po-Chiang; Shen, Guozhen; Shi, Yi; Chen, Haitian; Zhou, Chongwu

2010-08-24

In the work described in this paper, we have successfully fabricated flexible asymmetric supercapacitors (ASCs) based on transition-metal-oxide nanowire/single-walled carbon nanotube (SWNT) hybrid thin-film electrodes. These hybrid nanostructured films, with advantages of mechanical flexibility, uniform layered structures, and mesoporous surface morphology, were produced by using a filtration method. Here, manganese dioxide nanowire/SWNT hybrid films worked as the positive electrode, and indium oxide nanowire/SWNT hybrid films served as the negative electrode in a designed ASC. In our design, charges can be stored not only via electrochemical double-layer capacitance from SWNT films but also through a reversible faradic process from transition-metal-oxide nanowires. In addition, to obtain stable electrochemical behavior during charging/discharging cycles in a 2 V potential window, the mass balance between two electrodes has been optimized. Our optimized hybrid nanostructured ASCs exhibited a superior device performance with specific capacitance of 184 F/g, energy density of 25.5 Wh/kg, and columbic efficiency of approximately 90%. In addition, our ASCs exhibited a power density of 50.3 kW/kg, which is 10-fold higher than obtained in early reported ASC work. The high-performance hybrid nanostructured ASCs can find applications in conformal electrics, portable electronics, and electrical vehicles.

Boulder damage symposium annual thin film laser damage competition

DOE PAGES

Stolz, Christopher J.

2012-11-28

Optical instruments and laser systems are often fluence-limited by multilayer thin films deposited on the optical surfaces. When comparing publications within the laser damage literature, there can be confusing and conflicting laser damage results. This is due to differences in testing protocols between research groups studying very different applications. In this series of competitions, samples from multiple vendors are compared under identical testing parameters and a single testing service. Unlike a typical study where a hypothesis is tested within a well-controlled experiment with isolated variables, this competition isolates the laser damage testing variables so that trends can be observed betweenmore » different deposition processes, coating materials, cleaning techniques, and multiple coating suppliers. The resulting series of damage competitions has also been designed to observe general trends of damage morphologies and mechanisms over a wide range of coating types (high reflector and antireflector), wavelengths (193 to 1064 nm), and pulse lengths (180 fs to 13 ns). A double blind test assured sample and submitter anonymity were used in each of the competitions so only a summary of the deposition process, coating materials, layer count and spectral results are presented. Laser resistance was strongly affected by substrate cleaning, coating deposition method, and coating material selection whereas layer count and spectral properties had minimal impact.« less

Nanopore thin film enabled optical platform for drug loading and release.

PubMed

Song, Chao; Che, Xiangchen; Que, Long

2017-08-07

In this paper, a drug loading and release device fabricated using nanopore thin film and layer-by-layer (LbL) nanoassembly is reported. The nanopore thin film is a layer of anodic aluminum oxide (AAO), consisting of honeycomb-shape nanopores. Using the LbL nanoassembly process, the drug, using gentamicin sulfate (GS) as the model, can be loaded into the nanopores and the stacked layers on the nanopore thin film surface. The drug release from the device is achieved by immersing it into flowing DI water. Both the loading and release processes can be monitored optically. The effect of the nanopore size/volume on drug loading and release has also been evaluated. Further, the neuron cells have been cultured and can grow normally on the nanopore thin film, verifying its bio-compatibility. The successful fabrication of nanopore thin film device on silicon membrane render it as a potential implantable controlled drug release device.

Shell structure of natural rubber particles: evidence of chemical stratification by electrokinetics and cryo-TEM.

PubMed

Rochette, Christophe N; Crassous, Jérôme J; Drechsler, Markus; Gaboriaud, Fabien; Eloy, Marie; de Gaudemaris, Benoît; Duval, Jérôme F L

2013-11-26

The interfacial structure of natural rubber (NR) colloids is investigated by means of cryogenic transmission electron microscopy (cryo-TEM) and electrokinetics over a broad range of KNO3 electrolyte concentrations (4-300 mM) and pH values (1-8). The asymptotic plateau value reached by NR electrophoretic mobility (μ) in the thin double layer limit supports the presence of a soft (ion- and water-permeable) polyelectrolytic type of layer located at the periphery of the NR particles. This property is confirmed by the analysis of the electron density profile obtained from cryo-TEM that evidences a ∼2-4 nm thick corona surrounding the NR polyisoprene core. The dependence of μ on pH and salt concentration is further marked by a dramatic decrease of the point of zero electrophoretic mobility (PZM) from 3.6 to 0.8 with increasing electrolyte concentration in the range 4-300 mM. Using a recent theory for electrohydrodynamics of soft multilayered particles, this "anomalous" dependence of the PZM on electrolyte concentration is shown to be consistent with a radial organization of anionic and cationic groups across the peripheral NR structure. The NR electrokinetic response in the pH range 1-8 is indeed found to be equivalent to that of particles surrounded by a positively charged ∼3.5 nm thick layer (mean dissociation pK ∼ 4.2) supporting a thin and negatively charged outermost layer (0.6 nm in thickness, pK ∼ 0.7). Altogether, the strong dependence of the PZM on electrolyte concentration suggests that the electrostatic properties of the outer peripheral region of the NR shell are mediated by lipidic residues protruding from a shell containing a significant amount of protein-like charges. This proposed NR shell interfacial structure questions previously reported NR representations according to which the shell consists of either a fully mixed lipid-protein layer, or a layer of phospholipids residing exclusively beneath an outer proteic film.

Surface passivation investigation on ultra-thin atomic layer deposited aluminum oxide layers for their potential application to form tunnel layer passivated contacts

NASA Astrophysics Data System (ADS)

Xin, Zheng; Ling, Zhi Peng; Nandakumar, Naomi; Kaur, Gurleen; Ke, Cangming; Liao, Baochen; Aberle, Armin G.; Stangl, Rolf

2017-08-01

The surface passivation performance of atomic layer deposited ultra-thin aluminium oxide layers with different thickness in the tunnel layer regime, i.e., ranging from one atomic cycle (∼0.13 nm) to 11 atomic cycles (∼1.5 nm) on n-type silicon wafers is studied. The effect of thickness and thermal activation on passivation performance is investigated with corona-voltage metrology to measure the interface defect density D it(E) and the total interface charge Q tot. Furthermore, the bonding configuration variation of the AlO x films under various post-deposition thermal activation conditions is analyzed by Fourier transform infrared spectroscopy. Additionally, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) is used as capping layer on ultra-thin AlO x tunneling layers to further reduce the surface recombination current density to values as low as 42 fA/cm2. This work is a useful reference for using ultra-thin ALD AlO x layers as tunnel layers in order to form hole selective passivated contacts for silicon solar cells.

STM/STS Study of the Sb (111) Surface

NASA Astrophysics Data System (ADS)

Chekmazov, S. V.; Bozhko, S. I.; Smirnov, A. A.; Ionov, A. M.; Kapustin, A. A.

An Sb crystal is a Peierls insulator. Formation of double layers in the Sb structure is due to the shift of atomic planes (111) next but one along the C3 axis. Atomic layers inside the double layer are connected by covalent bonds. The interaction between double layers is determined mainly by Van der Waals forces. The cleave of an Sb single crystal used to be via break of Van der Waals bonds. However, using scanning tunneling microscopy (STM) and spectroscopy (STS) we demonstrated that apart from islands equal in thickness to the double layer, steps of one atomic layer in height also exist on the cleaved Sb (111) surface. Formation of "unpaired" (111) planes on the surface leads to a local break of conditions of Peierls transition. STS experiment reveals higher local density of states (LDOS) measured for "unpaired" (111) planes in comparison with those for the double layer.

Fabrication and properties of ZnO/GaN heterostructure nanocolumnar thin film on Si (111) substrate

PubMed Central

2013-01-01

Zinc oxide thin films have been obtained on bare and GaN buffer layer decorated Si (111) substrates by pulsed laser deposition (PLD), respectively. GaN buffer layer was achieved by a two-step method. The structure, surface morphology, composition, and optical properties of these thin films were investigated by X-ray diffraction, field emission scanning electron microscopy, infrared absorption spectra, and photoluminiscence (PL) spectra, respectively. Scanning electron microscopy images indicate that the flower-like grains were presented on the surface of ZnO thin films grown on GaN/Si (111) substrate, while the ZnO thin films grown on Si (111) substrate show the morphology of inclination column. PL spectrum reveals that the ultraviolet emission efficiency of ZnO thin film on GaN buffer layer is high, and the defect emission of ZnO thin film derived from Zni and Vo is low. The results demonstrate that the existence of GaN buffer layer can greatly improve the ZnO thin film on the Si (111) substrate by PLD techniques. PMID:23448090

Fabrication and properties of ZnO/GaN heterostructure nanocolumnar thin film on Si (111) substrate.

PubMed

Wei, Xianqi; Zhao, Ranran; Shao, Minghui; Xu, Xijin; Huang, Jinzhao

2013-02-28

Zinc oxide thin films have been obtained on bare and GaN buffer layer decorated Si (111) substrates by pulsed laser deposition (PLD), respectively. GaN buffer layer was achieved by a two-step method. The structure, surface morphology, composition, and optical properties of these thin films were investigated by X-ray diffraction, field emission scanning electron microscopy, infrared absorption spectra, and photoluminiscence (PL) spectra, respectively. Scanning electron microscopy images indicate that the flower-like grains were presented on the surface of ZnO thin films grown on GaN/Si (111) substrate, while the ZnO thin films grown on Si (111) substrate show the morphology of inclination column. PL spectrum reveals that the ultraviolet emission efficiency of ZnO thin film on GaN buffer layer is high, and the defect emission of ZnO thin film derived from Zni and Vo is low. The results demonstrate that the existence of GaN buffer layer can greatly improve the ZnO thin film on the Si (111) substrate by PLD techniques.

Conductive layer for biaxially oriented semiconductor film growth

DOEpatents

Findikoglu, Alp T.; Matias, Vladimir

2007-10-30

A conductive layer for biaxially oriented semiconductor film growth and a thin film semiconductor structure such as, for example, a photodetector, a photovoltaic cell, or a light emitting diode (LED) that includes a crystallographically oriented semiconducting film disposed on the conductive layer. The thin film semiconductor structure includes: a substrate; a first electrode deposited on the substrate; and a semiconducting layer epitaxially deposited on the first electrode. The first electrode includes a template layer deposited on the substrate and a buffer layer epitaxially deposited on the template layer. The template layer includes a first metal nitride that is electrically conductive and has a rock salt crystal structure, and the buffer layer includes a second metal nitride that is electrically conductive. The semiconducting layer is epitaxially deposited on the buffer layer. A method of making such a thin film semiconductor structure is also described.

Unexpected structural and magnetic depth dependence of YIG thin films

NASA Astrophysics Data System (ADS)

Cooper, J. F. K.; Kinane, C. J.; Langridge, S.; Ali, M.; Hickey, B. J.; Niizeki, T.; Uchida, K.; Saitoh, E.; Ambaye, H.; Glavic, A.

2017-09-01

We report measurements on yttrium iron garnet (YIG) thin films grown on both gadolinium gallium garnet (GGG) and yttrium aluminum garnet (YAG) substrates, with and without thin Pt top layers. We provide three principal results: the observation of an interfacial region at the Pt/YIG interface, we place a limit on the induced magnetism of the Pt layer, and confirm the existence of an interfacial layer at the GGG/YIG interface. Polarized neutron reflectometry (PNR) was used to give depth dependence of both the structure and magnetism of these structures. We find that a thin film of YIG on GGG is best described by three distinct layers: an interfacial layer near the GGG, around 5 nm thick and nonmagnetic, a magnetic "bulk" phase, and a nonmagnetic and compositionally distinct thin layer near the surface. We theorize that the bottom layer, which is independent of the film thickness, is caused by Gd diffusion. The top layer is likely to be extremely important in inverse spin Hall effect measurements, and is most likely Y2O3 or very similar. Magnetic sensitivity in the PNR to any induced moment in the Pt is increased by the existence of the Y2O3 layer; any moment is found to be less than 0.02 μB/atom .

Transition from moving to stationary double layers in a single-ended Q machine

NASA Technical Reports Server (NTRS)

Song, Bin; Merlino, R. L.; D'Angelo, N.

1990-01-01

Large-amplitude (less than about 100 percent) relaxation oscillations in the plasma potential are known to be generated when the cold endplate of a single-ended Q machine is biased positively. These oscillations are associated with double layers that form near the hot plate (plasma source) and travel toward the endplate at about the ion-acoustic velocity. At the endplate they dissolve and then form again near the hot plate, the entire process repeating itself in a regular manner. By admitting a sufficient amount of neutral gas into the system, the moving double layers were slowed down and eventually stopped. The production of stationary double layers requires an ion source on the high-potential side of the double layers. These ions are provided by ionization of the neutral gas by electrons that are accelerated through the double layer. The dependence of the critical neutral gas pressure required for stationary double-layer formation on endplate voltage, magnetic field strength, and neutral atom mass has been examined. These results are discussed in terms of a simple model of ion production and loss, including ion losses across the magnetic field.

Toward low friction in water for Mo2N/Ag coatings by tailoring the wettability

NASA Astrophysics Data System (ADS)

Dai, Xuan; Wen, Mao; Huang, Keke; Wang, Xin; Yang, Lina; Wang, Jia; Zhang, Kan

2018-07-01

Increasing demands for robust surfaces in harsh conditions, such as erosion, abrasion and sea-water, has stimulated the development of self-lubricated protective coatings. Meanwhile, due to the oil crisis, research in water lubrication again attracts much attention from both academics and practical engineers. Here, a higher hydrophilicity accompanying with a remarkable drop of friction coefficient in water environment was achieved successfully in Mo2N/Ag coatings by increasing Ag content. To do these, the Mo2N/Ag coatings with different Ag content were deposited by co-sputtering, which exhibit a nanocomposite structure consisting of precipitate Ag embedded in the Mo2N matrix. The high hydrophilicity can be ascribed to the combined contributions of the partial oxidation of Mo2N and high polarity of Ag precipitates. The decrease of friction coefficient is illustrated by the colloidal friction products and a mode with electric double layer. In which, enhanced hydrophilicity will result in forming a thin "water film" layer between the interface of counterpart and the coatings. And the MoOx/Ag2Mo4O13 derived from the hydrolysis action of Mo2N/Ag sliding in water could function as lubricant phase. Meanwhile, these negative charged MoOx/Ag2Mo4O13 colloidal particles induce the rearrangement of positive ions in the "water film" and form an electric double layer, which also contributes to the decrease of friction coefficient.

Methods for fabricating thin film III-V compound solar cell

DOEpatents

Pan, Noren; Hillier, Glen; Vu, Duy Phach; Tatavarti, Rao; Youtsey, Christopher; McCallum, David; Martin, Genevieve

2011-08-09

The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

Schottky barrier solar cell

NASA Technical Reports Server (NTRS)

Stirn, R. J.; Yeh, Y. C. M. (Inventor)

1981-01-01

A method of fabricating a Schottky barrier solar cell is described. The cell consists of a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive. A thin layer of heavily doped n-type polycrystalling germanium is deposited on the substrate after a passivation layer is deposited to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes to serve as a base layer on which a thin layer of gallium arsenide is vapor-epitaxilly grown followed by a thermally-grown oxide layer. A metal layer is deposited on the oxide layer and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer.

Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

DOEpatents

Braunlich, Peter F.; Tetzlaff, Wolfgang

1989-01-01

Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phoshphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate.

Method of making a high performance ultracapacitor

DOEpatents

Farahmandi, C. Joseph; Dispennette, John M.

2000-07-26

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

Aluminum-carbon composite electrode

DOEpatents

Farahmandi, C. Joseph; Dispennette, John M.

1998-07-07

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

Aluminum-carbon composite electrode

DOEpatents

Farahmandi, C.J.; Dispennette, J.M.

1998-07-07

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg. 3 figs.

Double layer drainage performance of porous asphalt pavement

NASA Astrophysics Data System (ADS)

Ji, Yangyang; Xie, Jianguang; Liu, Mingxi

2018-06-01

In order to improve the design reliability of the double layer porous asphalt pavement, the 3D seepage finite element method was used to study the drainage capacity of double layer PAC pavements with different geometric parameters. It revealed that the effect of pavement drainage length, slope, permeability coefficient and structure design on the drainage capacity. The research of this paper can provide reference for the design of double layer porous asphalt pavement in different rainfall intensity areas, and provide guides for the related engineering design.

Layered Organization in the Coastal Ocean: 4-D Assessment of Thin Layer Structure, Dynamics and Impacts

DTIC Science & Technology

2007-09-30

For example, the differences seen between the waters off of the US Pacific Northwest and the California Bight are almost certainly a reflection of the...the Pacific Northwest were favorable for thin layer development during that study. This is even more evident in those cases where thin layers...approach during the 2005 and 2006 LOCO process study combined time series data from an array of our Ocean Response Coastal Analysis System ( ORCAS ) (Donaghay

Using ambient ozone for assignment of double bond position in unsaturated lipids.

PubMed

Ellis, Shane R; Hughes, Jessica R; Mitchell, Todd W; in het Panhuis, Marc; Blanksby, Stephen J

2012-03-07

Unsaturated lipids deposited onto a range of materials are observed to react with the low concentrations of ozone present in normal laboratory air. Parent lipids and ozonolysis cleavage products are both detected directly from surfaces by desorption electrospray ionisation mass spectrometry (DESI-MS) with the resulting mass spectra providing clear evidence of the double bond position within these molecules. This serendipitous process has been coupled with thin-layer chromatography (TLC) to provide a simple but powerful approach for the detailed structural elucidation of lipids present in complex biological extracts. Lipid extracts from human lens were deposited onto normal phase TLC plates and then developed to separate components according to lipid class. Exposure of the developed plates to laboratory air for ca. 1 h prior to DESI-MS analysis gave rise to ozonolysis products allowing for the unambiguous identification of double bond positions in even low abundant, unsaturated lipids. In particular, the co-localization of intact unsaturated lactosylceramides (LacCer) with products from their oxidative cleavage provide the first evidence for the presence of three isomeric LacCer (d18:0/24:1) species in the ocular lens lipidome, i.e., variants with double bonds at the n-9, n-7 and n-5 positions.

Surface transport processes in charged porous media

DOE PAGES

Gabitto, Jorge; Tsouris, Costas

2017-03-03

Surface transport processes are important in chemistry, colloidal sciences, engineering, biology, and geophysics. Natural or externally produced charges on surfaces create electrical double layers (EDLs) at the solid-liquid interface. The existence of the EDLs produces several complex processes including bulk and surface transport of ions. In this work, a model is presented to simulate bulk and transport processes in homogeneous porous media comprising big pores. It is based on a theory for capacitive charging by ideally polarizable porous electrodes without Faradaic reactions or specific adsorption of ions. A volume averaging technique is used to derive the averaged transport equations inmore » the limit of thin electrical double layers. Description of the EDL between the electrolyte solution and the charged wall is accomplished using the Gouy-Chapman-Stern (GCS) model. The surface transport terms enter into the average equations due to the use of boundary conditions for diffuse interfaces. Two extra surface transports terms appear in the closed average equations. One is a surface diffusion term equivalent to the transport process in non-charged porous media. The second surface transport term is a migration term unique to charged porous media. The effective bulk and transport parameters for isotropic porous media are calculated solving the corresponding closure problems.« less

Influence of photo-generated carriers on current spreading in double diode structures for electroluminescent cooling

NASA Astrophysics Data System (ADS)

Radevici, Ivan; Tiira, Jonna; Sadi, Toufik; Oksanen, Jani

2018-05-01

Current crowding close to electrical contacts is a common challenge in all optoelectronic devices containing thin current spreading layers (CSLs). We analyze the effects of current spreading on the operation of the so-called double diode structure (DDS), consisting of a light emitting diode (LED) and a photodiode (PD) fabricated within the same epitaxial growth process, and providing an attractive platform for studying electroluminescent (EL) cooling under high bias conditions. We show that current spreading in the common n-type layer between the LED and the PD can be dramatically improved by the strong optical coupling between the diodes, as the coupling enables a photo-generated current through the PD. This reduces the current in the DDS CSL and enables the study of EL cooling using structures that are not limited by the conventional light extraction challenges encountered in normal LEDs. The current spreading in the structures is studied using optical imaging techniques, electrical measurements, simulations, as well as simple equivalent circuit models developed for this purpose. The improved current spreading leads further to a mutual dependence with the coupling efficiency, which is expected to facilitate the process of optimizing the DDS. We also report a new improved value of 63% for the DDS coupling quantum efficiency.

A one-dimensional Fickian model to predict the Ga depth profiles in three-stage Cu(In,Ga)Se{sub 2}

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

Rodriguez-Alvarez, H., E-mail: humberto.rodriguez@helmholtz-berlin.de; Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109 Berlin; Mainz, R.

2014-05-28

We present a one-dimensional Fickian model that predicts the formation of a double Ga gradient during the fabrication of Cu(In,Ga)Se{sub 2} thin films by three-stage thermal co-evaporation. The model is based on chemical reaction equations, structural data, and effective Ga diffusivities. In the model, the Cu(In,Ga)Se{sub 2} surface is depleted from Ga during the deposition of Cu-Se in the second deposition stage, leading to an accumulation of Ga near the back contact. During the third deposition stage, where In-Ga-Se is deposited at the surface, the atomic fluxes within the growing layer are inverted. This results in the formation of amore » double Ga gradient within the Cu(In,Ga)Se{sub 2} layer and reproduces experimentally observed Ga distributions. The final shape of the Ga depth profile strongly depends on the temperatures, times and deposition rates used. The model is used to evaluate possible paths to flatten the marked Ga depth profile that is obtained when depositing at low substrate temperatures. We conclude that inserting Ga during the second deposition stage is an effective way to achieve this.« less

Startup of electrophoresis in a suspension of colloidal spheres.

PubMed

Chiang, Chia C; Keh, Huan J

2015-12-01

The transient electrophoretic response of a homogeneous suspension of spherical particles to the step application of an electric field is analyzed. The electric double layer encompassing each particle is assumed to be thin but finite, and the effect of dynamic electroosmosis within it is incorporated. The momentum equation for the fluid outside the double layers is solved through the use of a unit cell model. Closed-form formulas for the time-evolving electrophoretic and settling velocities of the particles in the Laplace transform are obtained in terms of the electrokinetic radius, relative mass density, and volume fraction of the particles. The time scale for the development of electrophoresis and sedimentation is significantly smaller for a suspension with a higher particle volume fraction or a smaller particle-to-fluid density ratio, and the electrophoretic mobility at any instant increases with an increase in the electrokinetic particle radius. The transient electrophoretic mobility is a decreasing function of the particle volume fraction if the particle-to-fluid density ratio is relatively small, but it may increase with an increase in the particle volume fraction if this density ratio is relatively large. The particle interaction effect in a suspension on the transient electrophoresis is much weaker than that on the transient sedimentation of the particles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface transport processes in charged porous media

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

Gabitto, Jorge; Tsouris, Costas

Surface transport processes are important in chemistry, colloidal sciences, engineering, biology, and geophysics. Natural or externally produced charges on surfaces create electrical double layers (EDLs) at the solid-liquid interface. The existence of the EDLs produces several complex processes including bulk and surface transport of ions. In this work, a model is presented to simulate bulk and transport processes in homogeneous porous media comprising big pores. It is based on a theory for capacitive charging by ideally polarizable porous electrodes without Faradaic reactions or specific adsorption of ions. A volume averaging technique is used to derive the averaged transport equations inmore » the limit of thin electrical double layers. Description of the EDL between the electrolyte solution and the charged wall is accomplished using the Gouy-Chapman-Stern (GCS) model. The surface transport terms enter into the average equations due to the use of boundary conditions for diffuse interfaces. Two extra surface transports terms appear in the closed average equations. One is a surface diffusion term equivalent to the transport process in non-charged porous media. The second surface transport term is a migration term unique to charged porous media. The effective bulk and transport parameters for isotropic porous media are calculated solving the corresponding closure problems.« less

Prospects for reducing the processing cost of lithium ion batteries

DOE PAGES

Wood III, David L.; Li, Jianlin; Daniel, Claus

2014-11-06

A detailed processing cost breakdown is given for lithium-ion battery (LIB) electrodes, which focuses on: elimination of toxic, costly N-methylpyrrolidone (NMP) dispersion chemistry; doubling the thicknesses of the anode and cathode to raise energy density; and, reduction of the anode electrolyte wetting and SEI-layer formation time. These processing cost reduction technologies generically adaptable to any anode or cathode cell chemistry and are being implemented at ORNL. This paper shows step by step how these cost savings can be realized in existing or new LIB manufacturing plants using a baseline case of thin (power) electrodes produced with NMP processing and amore » standard 10-14-day wetting and formation process. In particular, it is shown that aqueous electrode processing can cut the electrode processing cost and energy consumption by an order of magnitude. Doubling the thickness of the electrodes allows for using half of the inactive current collectors and separators, contributing even further to the processing cost savings. Finally wetting and SEI-layer formation cost savings are discussed in the context of a protocol with significantly reduced time. These three benefits collectively offer the possibility of reducing LIB pack cost from $502.8 kWh-1-usable to $370.3 kWh-1-usable, a savings of $132.5/kWh (or 26.4%).« less

Start-up of electrophoresis of an arbitrarily oriented dielectric cylinder.

PubMed

Chen, Guan Y; Keh, Huan J

2014-09-01

An analytical study is presented for the transient electrophoretic response of a circular cylindrical particle to the step application of an electric field. The electric double layer adjacent to the particle surface is thin but finite compared with the radius of the particle. The time-evolving electroosmotic velocity at the outer boundary of the double layer is utilized as a slip condition so that the transient momentum conservation equation for the bulk fluid flow is solved. Explicit formulas for the unsteady electrophoretic velocity of the particle are obtained for both axially and transversely applied electric fields, and can be linearly superimposed for an arbitrarily-oriented applied field. If the cylindrical particle is neutrally buoyant in the suspending fluid, the transient electrophoretic velocity is independent of the orientation of the particle relative to the applied electric field and will be in the direction of the applied field. If the particle is different in density from the fluid, then the direction of electrophoresis will not coincide with that of the applied field until the steady state is attained. The growth of the electrophoretic mobility with the elapsed time for a cylindrical particle is substantially slower than for a spherical particle. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characteristics of a-IGZO/ITO hybrid layer deposited by magnetron sputtering.

PubMed

Bang, Joon-Ho; Park, Hee-Woo; Cho, Sang-Hyun; Song, Pung-Keun

2012-04-01

Transparent a-IGZO (In-Ga-Zn-O) films have been actively studied for use in the fabrication of high-quality TFTs. In this study, a-IGZO films and a-IGZO/ITO double layers were deposited by DC magnetron sputtering under various oxygen flow rates. The a-IGZO films showed an amorphous structure up to 500 degrees C. The deposition rate of these films decreased with an increase in the amount of oxygen gas. The amount of indium atoms in the film was confirmed to be 11.4% higher than the target. The resistivity of double layer follows the rules for parallel DC circuits The maximum Hall mobility of the a-IGZO/ITO double layers was found to be 37.42 cm2/V x N s. The electrical properties of the double layers were strongly dependent on their thickness ratio. The IGZO/ITO double layer was subjected to compressive stress, while the ITO/IGZO double layer was subjected to tensile stress. The bending tolerance was found to depend on the a-IGZO thickness.

The Electrical Double Layer and Its Structure

NASA Astrophysics Data System (ADS)

Stojek, Zbigniew

At any electrode immersed in an electrolyte solution, a specific interfacial region is formed. This region is called the double layer. The electrical properties of such a layer are important, since they significantly affect the electrochemical measurements. In an electrical circuit used to measure the current that flows at a particular working electrode, the double layer can be viewed as a capacitor. Figure I.1.1 depicts this situation where the electrochemical cell is represented by an electrical circuit and capacitor C d corresponds to the differential capacity of the double layer. To obtain a desired potential at the working electrodes, the double-layer capacitor must be first appropriately charged, which means that a capacitive current, not related to the reduction or oxidation of the substrates, flows in the electrical circuit. While this capacitive current carries some information concerning the double layer and its structure, and in some cases can be used for analytical purposes, in general, it interferes with electrochemical investigations. A variety of methods are used in electrochemistry to depress, isolate, or filter the capacitive current.

Effectiveness evaluation of double-layered satellite network with laser and microwave hybrid links based on fuzzy analytic hierarchy process

NASA Astrophysics Data System (ADS)

Zhang, Wei; Rao, Qiaomeng

2018-01-01

In order to solve the problem of high speed, large capacity and limited spectrum resources of satellite communication network, a double-layered satellite network with global seamless coverage based on laser and microwave hybrid links is proposed in this paper. By analyzing the characteristics of the double-layered satellite network with laser and microwave hybrid links, an effectiveness evaluation index system for the network is established. And then, the fuzzy analytic hierarchy process, which combines the analytic hierarchy process and the fuzzy comprehensive evaluation theory, is used to evaluate the effectiveness of the double-layered satellite network with laser and microwave hybrid links. Furthermore, the evaluation result of the proposed hybrid link network is obtained by simulation. The effectiveness evaluation process of the proposed double-layered satellite network with laser and microwave hybrid links can help to optimize the design of hybrid link double-layered satellite network and improve the operating efficiency of the satellite system.

Characteristic Features of Double Layers in Rotating, Magnetized Plasma Contaminated with Dust Grains with Varying Charges

NASA Astrophysics Data System (ADS)

Paul, Jaydeep; Nag, Apratim; Devi, Karabi; Das, Himadri Sekhar

2018-03-01

The evolution and the characteristic features of double layers in a plasma under slow rotation and contaminated with dust grains with varying charges under the effect of an external magnetic field are studied. The Coriolis force resulting from the slow rotation is responsible for the generation of an equivalent magnetic field. A comparatively new pseudopotential approach has been used to derive the small amplitude double layers. The effect of the relative electron-ion concentration, as well as the temperature ratio, on the formation of the double layers has also been investigated. The study reveals that compressive, as well as rarefactive, double layers can be made to co-exist in plasma by controlling the dust charge fluctuation effect supplemented by variations of the plasma constituents. The effectiveness of slow rotation in causing double layers to exist has also emanated from the study. The results obtained could be of interest because of their possible applications in both laboratories and space.

Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

PubMed Central

Nakayama, Hirokazu; Hayashi, Aki

2014-01-01

The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids. PMID:25080007

Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition.

PubMed

Nakayama, Hirokazu; Hayashi, Aki

2014-07-30

The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids.

High average power scaleable thin-disk laser

DOEpatents

Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Payne, Stephen A.; Powell, Howard; Krupke, William F.; Sutton, Steven B.

2002-01-01

Using a thin disk laser gain element with an undoped cap layer enables the scaling of lasers to extremely high average output power values. Ordinarily, the power scaling of such thin disk lasers is limited by the deleterious effects of amplified spontaneous emission. By using an undoped cap layer diffusion bonded to the thin disk, the onset of amplified spontaneous emission does not occur as readily as if no cap layer is used, and much larger transverse thin disks can be effectively used as laser gain elements. This invention can be used as a high average power laser for material processing applications as well as for weapon and air defense applications.

Front and backside processed thin film electronic devices

DOEpatents

Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.; Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang

2010-10-12

This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

Advanced light-scattering materials: Double-textured ZnO:B films grown by LP-MOCVD

NASA Astrophysics Data System (ADS)

Addonizio, M. L.; Spadoni, A.; Antonaia, A.

2013-12-01

Double-textured ZnO:B layers with enhanced optical scattering in both short and long wavelength regions have been successfully fabricated using MOCVD technique through a three step process. Growth of double-textured structures has been induced by wet etching on polycrystalline ZnO surface. Our double-layer structure consists of a first ZnO:B layer wet etched and subsequently used as substrate for a second ZnO:B layer deposition. Polycrystalline ZnO:B layers were etched by utilizing diluted solutions of fluoridic acid (HF), chloridric acid (HCl) and phosphoric acid (H3PO4) and their effect on surface morphology modification was systematically investigated. The morphology of the second deposited ZnO layer strongly depended on the surface properties of the etched ZnO first layer. Growth of cauliflower-like texture was induced by protrusions presence on the HCl etched surface. Optimized double-layer structure shows a cauliflower-like double texture with higher RMS roughness and increased spectral haze values in both short and long wavelength regions, compared to conventional pyramidal-like single texture. Furthermore, this highly scattering structure preserves excellent optical and electrical properties.

The enhancement mechanism of thin plasma layer on antenna radiation

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

Wang, Chunsheng, E-mail: wangcs@hit.edu.cn; Jiang, Binhao; Li, Xueai

A model of plasma-antenna is carried out to study the radiation enhancement mechanism of antenna covered by thin plasma layer. The results show when the radiation intensity achieves maximum, a region of equal electric field is formed due to the reflection of electric field at the interface of plasma and air. The plasma layer acted as an extension of the antenna. Furthermore, the shape of plasma layer is changed to verify the effect of plasma boundary on antenna radiation. The study shows the effect of thin plasma layer on electromagnetic field and provides a type of plasma antenna.

Improving Fire Resistance of Cotton Fabric through Layer-by-Layer Assembled Graphene Multilayer Nanocoating

NASA Astrophysics Data System (ADS)

Jang, Wonjun; Chung, Il Jun; Kim, Junwoo; Seo, Seongmin; Park, Yong Tae; Choi, Kyungwho

2018-05-01

In this study, thin films containing poly(vinyl alcohol) (PVA) and graphene nanoplatelets (GNPs), stabilized with poly(4-styrene-sulfonic acid) (PSS), were assembled by a simple and cost-effective layer-by-layer (LbL) technique in order to introduce the anti-flammability to cotton. These antiflammable layers were characterized by using UV-vis spectrometry and quartz crystal microbalance as a function of the number of bilayers deposited. Scanning electron microscopy was used to visualize the morphology of the thin film coatings on the cotton fabric. The graphene-polymer thin films introduced anti-flammable properties through thermally stable carbonaceous layers at a high temperature. The thermal stability and flame retardant property of graphene-coated cotton was demonstrated by thermogravimetric analysis, cone calorimetry, and vertical flame test. The results indicate that LbL-assembled graphene-polymer thin films can be applied largely in the field of flame retardant.

Chromium-induced ferromagnetism with perpendicular anisotropy in topological crystalline insulator SnTe (111) thin films

NASA Astrophysics Data System (ADS)

Wang, Fei; Zhang, Hongrui; Jiang, Jue; Zhao, Yi-Fan; Yu, Jia; Liu, Wei; Li, Da; Chan, Moses H. W.; Sun, Jirong; Zhang, Zhidong; Chang, Cui-Zu

2018-03-01

Topological crystalline insulator is a recently discovered topological phase of matter. It possesses multiple Dirac surface states, which are protected by the crystal symmetry. This is in contrast to the time-reversal symmetry that is operative in the well-known topological insulators. In the presence of a Zeeman field and/or strain, the multiple Dirac surface states are gapped. The high-Chern-number quantum anomalous Hall (QAH) state is predicted to emerge if the chemical potential resides in all the Zeeman gaps. Here, we use molecular-beam epitaxy to grow 12 double-layer (DL) pure and Cr-doped SnTe (111) thin film on heat-treated SrTi O3 (111) substrate using a quintuple layer of insulating (Bi0.2Sb0.8 ) 2T e3 topological insulator as a buffer film. The Hall traces of Cr-doped SnTe film at low temperatures display square hysteresis loops indicating long-range ferromagnetic order with perpendicular anisotropy. The Curie temperature of the 12 DL S n0.9C r0.1Te film is ˜110 K. Due to the chemical potential crossing the bulk valence bands, the anomalous Hall resistance of 12 DL S n0.9C r0.1Te film is substantially lower than the predicted quantized value (˜1 /4 h /e2 ). It is possible that with systematic tuning the chemical potential via chemical doping and electrical gating, the high-Chern-number QAH state can be realized in the Cr-doped SnTe (111) thin film.

Variation of microstructural and optical properties in SILAR grown ZnO thin films by thermal treatment.

PubMed

Valanarasu, S; Dhanasekaran, V; Chandramohan, R; Kulandaisamy, I; Sakthivelu, A; Mahalingam, T

2013-08-01

The influence of thermal treatment on the structural and morphological properties of the ZnO films deposited by double dip Successive ionic layer by adsorption reaction is presented. The effect of annealing temperature and time in air ambient is presented in detail. The deposited films were annealed from 200 to 400 degrees C in air and the structural properties were determined as a function of annealing temperature by XRD. The studies revealed that films were exhibiting preferential orientation along (002) plane. The other structural parameters like the crystallite size (D), micro strain (epsilon), dislocation density (delta) and stacking fault (alpha) of as-deposited and annealed ZnO films were evaluated and reported. The optical properties were also studied and the band gap of the ZnO thins films varied from 3.27 to 3.04 eV with the annealing temperature. SEM studies revealed that the hexagonal shaped grains with uniformly distributed morphology in annealed ZnO thin films. It has been envisaged using EDX analysis that the near stoichiometric composition of the film can be attained by thermal treatment during which microstructural changes do occur.

Lithographically patterned thin activated carbon films as a new technology platform for on-chip devices.

PubMed

Wei, Lu; Nitta, Naoki; Yushin, Gleb

2013-08-27

Continuous, smooth, visibly defect-free, lithographically patterned activated carbon films (ACFs) are prepared on the surface of silicon wafers. Depending on the synthesis conditions, porous ACFs can either remain attached to the initial substrate or be separated and transferred to another dense or porous substrate of interest. Tuning the activation conditions allows one to change the surface area and porosity of the produced carbon films. Here we utilize the developed thin ACF technology to produce prototypes of functional electrical double-layer capacitor devices. The synthesized thin carbon film electrodes demonstrated very high capacitance in excess of 510 F g(-1) (>390 F cm(-3)) at a slow cyclic voltammetry scan rate of 1 mV s(-1) and in excess of 325 F g(-1) (>250 F cm(-3)) in charge-discharge tests at an ultrahigh current density of 45,000 mA g(-1). Good stability was demonstrated after 10,000 galvanostatic charge-discharge cycles. The high values of the specific and volumetric capacitances of the selected ACF electrodes as well as the capacity retention at high current densities demonstrated great potential of the proposed technology for the fabrication of various on-chip devices, such as micro-electrochemical capacitors.

Electro-osmotic flow in a rotating rectangular microchannel

PubMed Central

Ng, Chiu-On; Qi, Cheng

2015-01-01

An analytical model is presented for low-Rossby-number electro-osmotic flow in a rectangular channel rotating about an axis perpendicular to its own. The flow is driven under the combined action of Coriolis, pressure, viscous and electric forces. Analytical solutions in the form of eigenfunction expansions are developed for the problem, which is controlled by the rotation parameter (or the inverse Ekman number), the Debye parameter, the aspect ratio of the channel and the distribution of zeta potentials on the channel walls. Under the conditions of fast rotation and a thin electric double layer (EDL), an Ekman–EDL develops on the horizontal walls. This is essentially an Ekman layer subjected to electrokinetic effects. The flow structure of this boundary layer as a function of the Ekman layer thickness normalized by the Debye length is investigated in detail in this study. It is also shown that the channel rotation may have qualitatively different effects on the flow rate, depending on the channel width and the zeta potential distributions. Axial and secondary flows are examined in detail to reveal how the development of a geostrophic core may lead to a rise or fall of the mean flow. PMID:26345088

Some metal oxides and their applications for creation of Microsystems (MEMS) and Energy Harvesting Devices (EHD)

NASA Astrophysics Data System (ADS)

Denishev, K.

2016-10-01

This is a review of a part of the work of the Technological Design Group at Technical University of Sofia, Faculty of Electronic Engineering and Technologies, Department of Microelectronics. It is dealing with piezoelectric polymer materials and their application in different microsystems (MEMS) and Energy Harvesting Devices (EHD), some organic materials and their applications in organic (OLED) displays, some transparent conductive materials etc. The metal oxides Lead Zirconium Titanate (PZT) and Zinc Oxide (ZnO) are used as piezoelectric layers - driving part of different sensors, actuators and EHD. These materials are studied in term of their performance in dependence on the deposition conditions and parameters. They were deposited as thin films by using RF Sputtering System. As technological substrates, glass plates and Polyethylenetherephtalate (PET) foils were used. For characterization of the materials, a test structure, based on Surface Acoustic Waves (SAW), was designed and prepared. The layers were characterized by Fourier Transform Infrared spectroscopy (FTIR). The piezoelectric response was tested at variety of mechanical loads (tensile strain, stress) in static and dynamic (multiple bending) mode. The single-layered and double-layered structures were prepared for piezoelectric efficiency increase. A structure of piezoelectric energy transformer is proposed and investigated.

Effect of Al gate on the electrical behaviour of Al-doped Ta2O5 stacks

NASA Astrophysics Data System (ADS)

Skeparovski, A.; Novkovski, N.; Atanassova, E.; Paskaleva, A.; Lazarov, V. K.

2011-06-01

The electrical behaviour of Al-doped Ta2O5 films on nitrided silicon and implemented in Al-gated MIS capacitors has been studied. The dopant was introduced into the Ta2O5 through its surface by deposing a thin Al layer on the top of Ta2O5 followed by an annealing process. The HRTEM images reveal that the initial double-layer structure of the stacks composed of doped Ta2O5 and interfacial SiON layer undergoes changes during the formation of the Al gate and transforms into a three-layer structure with an additional layer between the Al electrode and the doped Ta2O5. This layer, being a result of reaction between the Al gate and the Al-doped Ta2O5, affects the overall electrical properties of the stacks. Strong charge trapping/detrapping processes have been established in the vicinity of the doped Ta2O5/SiON interface resulting in a large C-V hysteresis effect. The charge trapping also influences the current conduction in the layers keeping the current density level rather low even at high electric fields (J < 10-6 A cm-2 at 7 MV cm-1). By employing a three-layer model of the stack, the permittivity of both, the Al-doped Ta2O5 and the additional layer, has been estimated and the corresponding conduction mechanisms identified.

Light scattering management of dye-sensitized solar cells based on double-layered photoanodes aided by uniform TiO{sub 2} aggregates

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

Bakhshayesh, A.M., E-mail: bakhshayesh@alum.sharif.edu

2016-01-15

Highlights: • A new architecture of double-layered TiO{sub 2} electrodes is presented. • The electrode contains two alternate layers of TiO{sub 2} nanoparticles and aggregates. • The aggregates layers are deposited onto the nanocrystalline layer. • The new design showed improved efficiency compared to conventional cells. - Abstract: This study presents a new double-layered TiO{sub 2} film containing a nanocrystalline under-layer and a uniform, sponge-like light scattering over-layer for dye-sensitized solar cells (DSCs) application. The over-layer is composed of 2-μm-diameter uniform aggregates, containing small nanoparticles with the average grain size of 20 nm. X-ray diffraction reveals that the light scatteringmore » layer has a mixture of anatase and rutile phases, whereas the nanocrystalline layer has a pure anatase phase. Ultraviolet–visible (UV–vis) spectra show that the light scattering layer has lower band gap energy than the nanocrystalline under-layer, extending the absorption of TiO{sub 2} into visible region. Diffuse reflectance spectroscopy demonstrates that the double-layered electrode enjoyed better light scattering ability. The double-layered DSC shows the highest power conversion efficiency of 7.69% and incident photon-to-current efficiency of 88% as a result of higher light harvesting and less recombination which is demonstrated by electrochemical impedance spectroscopy.« less

Programmable Electrochemical Rectifier Based on a Thin-Layer Cell.

PubMed

Park, Seungjin; Park, Jun Hui; Hwang, Seongpil; Kwak, Juhyoun

2017-06-21

A programmable electrochemical rectifier based on thin-layer electrochemistry is described here. Both the rectification ratio and the response time of the device are programmable by controlling the gap distance of the thin-layer electrochemical cell, which is easily controlled using commercially available beads. One of the electrodes was modified using a ferrocene-terminated self-assembled monolayer to offer unidirectional charge transfers via soluble redox species. The thin-layer configuration provided enhanced mass transport, which was determined by the gap thickness. The device with the smallest gap thickness (∼4 μm) showed an unprecedented, high rectification ratio (up to 160) with a fast response time in a two-terminal configuration using conventional electronics.

The effects of layering in ferroelectric Si-doped HfO{sub 2} thin films

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

Lomenzo, Patrick D.; Nishida, Toshikazu, E-mail: nishida@ufl.edu; Takmeel, Qanit

2014-08-18

Atomic layer deposited Si-doped HfO{sub 2} thin films approximately 10 nm thick are deposited with various Si-dopant concentrations and distributions. The ferroelectric behavior of the HfO{sub 2} thin films are shown to be dependent on both the Si mol. % and the distribution of Si-dopants. Metal-ferroelectric-insulator-semiconductor capacitors are shown to exhibit a tunable remanent polarization through the adjustment of the Si-dopant distribution at a constant Si concentration. Inhomogeneous layering of Si-dopants within the thin films effectively lowers the remanent polarization. A pinched hysteresis loop is observed for higher Si-dopant concentrations and found to be dependent on the Si layering distribution.

NMR of thin layers using a meanderline surface coil

DOEpatents

Cowgill, Donald F.

2001-01-01

A miniature meanderline sensor coil which extends the capabilities of nuclear magnetic resonance (NMR) to provide analysis of thin planar samples and surface layer geometries. The sensor coil allows standard NMR techniques to be used to examine thin planar (or curved) layers, extending NMRs utility to many problems of modern interest. This technique can be used to examine contact layers, non-destructively depth profile into films, or image multiple layers in a 3-dimensional sense. It lends itself to high resolution NMR techniques of magic angle spinning and thus can be used to examine the bonding and electronic structure in layered materials or to observe the chemistry associated with aging coatings. Coupling this sensor coil technology with an arrangement of small magnets will produce a penetrator probe for remote in-situ chemical analysis of groundwater or contaminant sediments. Alternatively, the sensor coil can be further miniaturized to provide sub-micron depth resolution within thin films or to orthoscopically examine living tissue. This thin-layer NMR technique using a stationary meanderline coil in a series-resonant circuit has been demonstrated and it has been determined that the flat meanderline geometry has about he same detection sensitivity as a solenoidal coil, but is specifically tailored to examine planar material layers, while avoiding signals from the bulk.

Effect of processing parameters on microstructure of MoS{sub 2} ultra-thin films synthesized by chemical vapor deposition method

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

Song, Yang; You, Suping; Sun, Kewei

2015-06-15

MoS{sub 2} ultra-thin layers are synthesized using a chemical vapor deposition method based on the sulfurization of molybdenum trioxide (MoO{sub 3}). The ultra-thin layers are characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy and atomic force microscope (AFM). Based on our experimental results, all the processing parameters, such as the tilt angle of substrate, applied voltage, heating time and the weight of source materials have effect on the microstructures of the layers. In this paper, the effects of such processing parameters on the crystal structures and morphologies of the as-grown layers are studied. It is found that the film obtainedmore » with the tilt angle of 0.06° is more uniform. A larger applied voltage is preferred to the growth of MoS{sub 2} thin films at a certain heating time. In order to obtain the ultra-thin layers of MoS{sub 2}, the weight of 0.003 g of source materials is preferred. Under our optimal experimental conditions, the surface of the film is smooth and composed of many uniformly distributed and aggregated particles, and the ultra-thin MoS{sub 2} atomic layers (1∼10 layers) covers an area of more than 2 mm×2 mm.« less

The properties of plasma-enhanced atomic layer deposition (ALD) ZnO thin films and comparison with thermal ALD

NASA Astrophysics Data System (ADS)

Kim, Doyoung; Kang, Hyemin; Kim, Jae-Min; Kim, Hyungjun

2011-02-01

Zinc oxide (ZnO) thin films were prepared by plasma-enhanced atomic layer deposition (PE-ALD) using oxygen plasma as a reactant and the properties were compared with those of thermal atomic layer deposition (TH-ALD) ZnO thin films. While hexagonal wurzite phase with preferential (0 0 2) orientation was obtained for both cases, significant differences were observed in various aspects of film properties including resistivity values between these two techniques. Photoluminescence (PL) measurements have shown that high resistivity of PE-ALD ZnO thin films is due to the oxygen interstitials at low growth temperature of 200 °C, whose amount decreases with increasing growth temperature. Thin film transistors (TFT) using TH- and PE-ALD ZnO as an active layer were also fabricated and the device properties were evaluated comparatively.

Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

DOEpatents

Braunlich, P.F.; Tetzlaff, W.

1989-04-25

Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters are disclosed. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phosphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate. 34 figs.

Fermi level de-pinning of aluminium contacts to n-type germanium using thin atomic layer deposited layers

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

Gajula, D. R., E-mail: dgajula01@qub.ac.uk; Baine, P.; Armstrong, B. M.

Fermi-level pinning of aluminium on n-type germanium (n-Ge) was reduced by insertion of a thin interfacial dielectric by atomic layer deposition. The barrier height for aluminium contacts on n-Ge was reduced from 0.7 eV to a value of 0.28 eV for a thin Al{sub 2}O{sub 3} interfacial layer (∼2.8 nm). For diodes with an Al{sub 2}O{sub 3} interfacial layer, the contact resistance started to increase for layer thicknesses above 2.8 nm. For diodes with a HfO{sub 2} interfacial layer, the barrier height was also reduced but the contact resistance increased dramatically for layer thicknesses above 1.5 nm.

Long-time relaxation of photo-induced influence on BiFeO3 thin films

NASA Astrophysics Data System (ADS)

Gu, Jun-xing; Jin, Kui-juan; Wang, Le; He, Xu; Guo, Hai-zhong; Wang, Can; He, Meng; Yang, Guo-zhen

2015-11-01

An intuitively persistent enhancement of the local surface potential of BiFeO3 layers in both heterostructures of BiFeO3/SrRuO3/SrTiO3 and BiFeO3/Sr0.09Nb0.01TiO3 was observed by the Kelvin probe force microscopy technique after the illumination of 375 nm laser. This photo-induced enhanced surface potential can maintain as long as 15 h after the illumination. We attributed this super-long-time relaxation of photo-induced influence to a photo-induced depolarization in the BiFeO3 thin films, and our first-principles calculation of double-potential well further provides an instinct understanding on this depolarization process. Our findings provide a peculiar understanding into the photo-induced phenomena on the widely researched ferroelectric systems and offer an approach to tune their multifunctionality of the magnetization and polarization not only by applied magnetic and electric fields but also by optical filed.

Suspended sub-50 nm vanadium dioxide membrane transistors: fabrication and ionic liquid gating studies

NASA Astrophysics Data System (ADS)

Sim, Jai S.; Zhou, You; Ramanathan, Shriram

2012-10-01

We demonstrate a robust lithographic patterning method to fabricate self-supported sub-50 nm VO2 membranes that undergo a phase transition. Utilizing such self-supported membranes, we directly observed a shift in the metal-insulator transition temperature arising from stress relaxation and consistent opening of the hysteresis. Electric double layer transistors were then fabricated with the membranes and compared to thin film devices. The ionic liquid allowed reversible modulation of channel resistance and distinguishing bulk processes from the surface effects. From the shift in the metal-insulator transition temperature, the carrier density doped through electrolyte gating is estimated to be 1 × 1020 cm-3. Hydrogen annealing studies showed little difference in resistivity between the film and the membrane indicating rapid diffusion of hydrogen in the vanadium oxide rutile lattice consistent with previous observations. The ability to fabricate electrically-wired, suspended VO2 ultra-thin membranes creates new opportunities to study mesoscopic size effects on phase transitions and may also be of interest in sensor devices.

Control of magnetism in Co by an electric field

NASA Astrophysics Data System (ADS)

Chiba, D.; Ono, T.

2013-05-01

In this paper, we review the recent experimental developments on electric-field switching of ferromagnetism in ultra-thin Co films. The application of an electric field changes the electron density at the surface of the Co film, which results in modulation of its Curie temperature. A capacitor structure consisting of a gate electrode, a solid-state dielectric insulator and a Co bottom electrode is used to observe the effect. To obtain a larger change in the electron density, we also fabricated an electric double-layer capacitor structure using an ionic liquid. A large change in the Curie temperature of ∼100 K across room temperature is achieved with this structure. The application of the electric field influences not only the Curie temperature but also the domain-wall motion. A change in the velocity of a domain wall prepared in a Co micro-wire of more than one order of magnitude is observed. Possible mechanisms to explain the above-mentioned electric-field effects in Co ultra-thin films are discussed.

Transition from Reconstruction toward Thin Film on the (110) Surface of Strontium Titanate

PubMed Central

2016-01-01

The surfaces of metal oxides often are reconstructed with a geometry and composition that is considerably different from a simple termination of the bulk. Such structures can also be viewed as ultrathin films, epitaxed on a substrate. Here, the reconstructions of the SrTiO3 (110) surface are studied combining scanning tunneling microscopy (STM), transmission electron diffraction, and X-ray absorption spectroscopy (XAS), and analyzed with density functional theory calculations. Whereas SrTiO3 (110) invariably terminates with an overlayer of titania, with increasing density its structure switches from n × 1 to 2 × n. At the same time the coordination of the Ti atoms changes from a network of corner-sharing tetrahedra to a double layer of edge-shared octahedra with bridging units of octahedrally coordinated strontium. This transition from the n × 1 to 2 × n reconstructions is a transition from a pseudomorphically stabilized tetrahedral network toward an octahedral titania thin film with stress-relief from octahedral strontia units at the surface. PMID:26954064

Anisotropy of the upper critical field and its thickness dependence in superconducting FeSe electric-double-layer transistors

NASA Astrophysics Data System (ADS)

Shiogai, Junichi; Kimura, Shojiro; Awaji, Satoshi; Nojima, Tsutomu; Tsukazaki, Atsushi

2018-05-01

Anisotropy of superconductivity is one of the fundamental physical parameters for understanding layered iron-based superconductors (IBSs). Here we investigated the anisotropic response of resistive transition as a function of thickness (d ) in iron selenide (FeSe) based electric-double-layer transistors (EDLTs) on SrTi O3 , which exhibit superconducting transition temperatures Tc as high as 40 K below d =10 nm . According to the analyses of the in-plane (Hc2 //) and out-of-plane (Hc2 ⊥) upper critical fields (Hc 2) and the magnetic field angle dependence of the resistance (Rs-θ ) in ultrathin condition, we found that the anisotropy factor ɛ0=Hc2 ///Hc2 ⊥ is 7.4 in the thin limit of d ˜1 nm , which is larger than that of bulk IBSs. In addition, we observed the shorter out-of-plane coherence length ξc of 0.19 nm compared to the c -axis lattice constant, which implies the confinement of the order parameter in the one unit cell FeSe. These findings suggest that high-Tc superconductivity in the ultrathin FeSe-EDLT exhibits an anisotropic three-dimensional (3D) or quasi-two-dimensional (2D) nature rather than the pure 2D one, leading to the robust superconductivity. Moreover, we carried out the systematic evaluation of the anisotropic Hc 2 against thickness reduction in the FeSe channel. The in-plane Hc 2 as a function of normalized temperature T /Tc is almost independent of d until the thin limit condition. On the other hand, the out-of-plane Hc 2 near T /Tc˜1 decreases with increasing d , resulting in the increase of ɛ0 at around Tc to 32.0 at the thick condition of d =9.3 nm , which is also confirmed by Rs-θ measurements. The counterintuitive behavior can be attributed to the degree of coupling strength between two electron-rich layers possessing a high superconducting order parameter induced by electrostatic gating at the top interface and charge transfer from SrTi O3 substrates at the bottom interface. Besides a large Hc2 ⊥ for d =9.3 nm exceeding 20 T even at T =0.8 Tc , we observe the decoupling crossover of the two superconducting layers at low temperature, which is a unique feature for the high-Tc FeSe-EDLT on SrTi O3 .

Self-assembled three-dimensional and compressible interdigitated thin-film supercapacitors and batteries

PubMed Central

Nyström, Gustav; Marais, Andrew; Karabulut, Erdem; Wågberg, Lars; Cui, Yi; Hamedi, Mahiar M.

2015-01-01

Traditional thin-film energy-storage devices consist of stacked layers of active films on two-dimensional substrates and do not exploit the third dimension. Fully three-dimensional thin-film devices would allow energy storage in bulk materials with arbitrary form factors and with mechanical properties unique to bulk materials such as compressibility. Here we show three-dimensional energy-storage devices based on layer-by-layer self-assembly of interdigitated thin films on the surface of an open-cell aerogel substrate. We demonstrate a reversibly compressible three-dimensional supercapacitor with carbon nanotube electrodes and a three-dimensional hybrid battery with a copper hexacyanoferrate ion intercalating cathode and a carbon nanotube anode. The three-dimensional supercapacitor shows stable operation over 400 cycles with a capacitance of 25 F g−1 and is fully functional even at compressions up to 75%. Our results demonstrate that layer-by-layer self-assembly inside aerogels is a rapid, precise and scalable route for building high-surface-area 3D thin-film devices. PMID:26021485

Thin film electronic devices with conductive and transparent gas and moisture permeation barriers

DOEpatents

Simpson, Lin Jay

2013-12-17

A thin film stack (100, 200) is provided for use in electronic devices such as photovoltaic devices. The stack (100, 200) may be integrated with a substrate (110) such as a light transmitting/transmissive layer. A electrical conductor layer (120, 220) is formed on a surface of the substrate (110) or device layer such as a transparent conducting (TC) material layer (120,220) with pin holes or defects (224) caused by manufacturing. The stack (100) includes a thin film (130, 230) of metal that acts as a barrier for environmental contaminants (226, 228). The metal thin film (130,230) is deposited on the conductor layer (120, 220) and formed from a self-healing metal such as a metal that forms self-terminating oxides. A permeation plug or block (236) is formed in or adjacent to the thin film (130, 230) of metal at or proximate to the pin holes (224) to block further permeation of contaminants through the pin holes (224).

Thickness dependence of the levitation performance of double-layer high-temperature superconductor bulks above a magnetic rail

NASA Astrophysics Data System (ADS)

Sun, R. X.; Zheng, J.; Liao, X. L.; Che, T.; Gou, Y. F.; He, D. B.; Deng, Z. G.

2014-10-01

A double-layer high-temperature superconductor (HTSC) arrangement was proposed and proved to be able to bring improvements to both levitation force and guidance force compared with present single-layer HTSC arrangement. To fully exploit the applied magnetic field by a magnetic rail, the thickness dependence of a double-layer HTSC arrangement on the levitation performance was further investigated in the paper. In this study, the lower-layer bulk was polished step by step to different thicknesses, and the upper-layer bulk with constant thickness was directly superimposed on the lower-layer one. The levitation force and the force relaxation of the double-layer HTSC arrangement were measured above a Halbach magnetic rail. Experimental result shows that a bigger levitation force and a less levitation force decay could be achieved by optimizing the thickness of the lower-layer bulk HTSC. This thickness optimization method could be applied together with former reported double-layer HTSC arrangement method with aligned growth sector boundaries pattern. This series of study on the optimized combination method do bring a significant improvement on the levitation performance of present HTS maglev systems.

Fabrication of read-only type triple-layered disc

NASA Astrophysics Data System (ADS)

Yang, Huei Wen; Jeng, Tzuan Ren; Yen, Wen Hsin; Chan, Rong Po; Shin, Kuo Ding; Huang, Der Ray

2003-06-01

The approach to increase optical recording density has become very popular research subject in these years. One direct and effective method is to increase the recording layer stack number. That is to say, to add one more recording layer can get one more recording capacity. In this paper, we will propose a new method for manufacturing read only type multi-layered disc. The process is described in the following. This first recorded data layer (called L0) still follows the traditional DVD disc manufacturing process. We obtain the polycarbonate substrate by replicating from Ni stamper. Then polycarbonate substrate is sputtered thin silicon film for semi-reflection layer. As for second layer (L1) and even more layer (Ln-1) producing, one special kind of duplication (called SKD) method is proposed. The duplication (or replication) source of second or nth recorded data is not only limited from Ni stamper. Even polycarbonate or PMMA substrate has recording data are also acceptable sources. At next step, the duplication source is deposited by thin gold film. Then we apply spin coating to bond the first layer (L0) substrate and second layer (L1) duplication source by choosing suitable UV curing glue. After being emitted by UV lamp for several seconds, we can easily separate the duplication source of second layer (L1) from (L0) substrate. Then we find the thin second data layer (L1) is replicated and stacks upon the first layer. On the same way, we sputter thin AgTi layer on the thin second data layer for another semi- reflective layer. By following the above manufacture step, we can produce more layers. In our experimental, we prepare triple layered read-only type disc. The total capacity is almost 12GB for one side of disc, and 24GB for two side of disc. The read-out intensity of laser from each data layer is expected to be similar. Thus we have designed particular reflectance and transmittance for each data layer by controlling the thickness of thin silicon film. We can verify our design by checking the focusing error signal in S-curve search of optical pickup head. The signal quality for each layer can be found from the signal eye pattern and jitter. For compatibility with present drive system, the requirement of the readout signal from each layer should be same as DVD or CD specification

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.

Use of a thin-layer technique in thyroid fine needle aspiration.

PubMed

Malle, Despoina; Valeri, Rosalia-Maria; Pazaitou-Panajiotou, Kalliopi; Kiziridou, Anastasia; Vainas, Iraklis; Destouni, Charicleia

2006-01-01

To investigate the efficacy of the ThinPrep Processor (Cytyc Corporation, Boxborough, Massachusetts, U.S.A) in fine needle aspiration (FNA) of thyroid gland lesions. This study included 459 thyroid FNA specimens obtained from patients who came to our endocrinology department with various thyroid disorders over 3 years. The cytologic material was prepared using both the conventional and ThinPrep method in the first 2 years (285 cases), while in the last one only the ThinPrep method was used (1 74 cases). The smears were stained using a modified Papanicolaou procedure and May-Grünwald-Giemsa stain. Immunocytochemistry was performed on thin-layer slides using specific monoclonal antibodies when needed. Thin-layer and direct smear diagnoses were compared with the final cytologic or histologic diagnoses, when available. Our cases included 279 adenomatoid nodules, 15 cases of Hashimoto thyroiditis, 45 follicular neoplasms, 14 Hürthle cell tumors, 58 papillary carcinomas and 1 5 anaplastic carcinomas. Thin-layer preparations showed a trend toward a lower proportion of inadequate specimens and a lower false negative rate. Cytomorphologic features showed some differences between the 2 methods. Colloid was less frequently observed on ThinPrep slides, while nuclear detail and micronucleoli were more easily detected with this technique. Moreover, ThinPrep appeared to be the appropriate method for the use of ancillary techniques in suspicious cases. Thin-layer cytology improves the diagnostic accuracy of thyroid FNA and offers the possibility of performing new techniques, such as immunocytochemistry, on the same sample in order to detect malignancy as well as the type and origin of thyroid gland neoplasms.

Increased upstream ionization due to formation of a double layer.

PubMed

Thakur, S Chakraborty; Harvey, Z; Biloiu, I A; Hansen, A; Hardin, R A; Przybysz, W S; Scime, E E

2009-01-23

We report observations that confirm a theoretical prediction that formation of a current-free double layer in a plasma expanding into a chamber of larger diameter is accompanied by an increase in ionization upstream of the double layer. The theoretical model argues that the increased ionization is needed to balance the difference in diffusive losses upstream and downstream of the expansion region. In our expanding helicon source experiments, we find that the upstream plasma density increases sharply at the same antenna frequency at which the double layer appears.

Capacitance of the Double Layer Formed at the Metal/Ionic-Conductor Interface: How Large Can It Be?

NASA Astrophysics Data System (ADS)

Skinner, Brian; Loth, M. S.; Shklovskii, B. I.

2010-03-01

The capacitance of the double layer formed at a metal/ionic-conductor interface can be remarkably large, so that the apparent width of the double layer is as small as 0.3 Å. Mean-field theories fail to explain such large capacitance. We propose an alternate theory of the ionic double layer which allows for the binding of discrete ions to their image charges in the metal. We show that at small voltages the capacitance of the double layer is limited only by the weak dipole-dipole repulsion between bound ions, and is therefore very large. At large voltages the depletion of bound ions from one of the capacitor electrodes triggers a collapse of the capacitance to the mean-field value.

Tailoring properties of lossy-mode resonance optical fiber sensors with atomic layer deposition technique

NASA Astrophysics Data System (ADS)

Kosiel, Kamil; Koba, Marcin; Masiewicz, Marcin; Śmietana, Mateusz

2018-06-01

The paper shows application of atomic layer deposition (ALD) technique as a tool for tailoring sensorial properties of lossy-mode-resonance (LMR)-based optical fiber sensors. Hafnium dioxide (HfO2), zirconium dioxide (ZrO2), and tantalum oxide (TaxOy), as high-refractive-index dielectrics that are particularly convenient for LMR-sensor fabrication, were deposited by low-temperature (100 °C) ALD ensuring safe conditions for thermally vulnerable fibers. Applicability of HfO2 and ZrO2 overlays, deposited with ALD-related atomic level thickness accuracy for fabrication of LMR-sensors with controlled sensorial properties was presented. Additionally, for the first time according to our best knowledge, the double-layer overlay composed of two different materials - silicon nitride (SixNy) and TaxOy - is presented for the LMR fiber sensors. The thin films of such overlay were deposited by two different techniques - PECVD (the SixNy) and ALD (the TaxOy). Such approach ensures fast overlay fabrication and at the same time facility for resonant wavelength tuning, yielding devices with satisfactory sensorial properties.

Photovoltaic sub-cell interconnects

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

van Hest, Marinus Franciscus Antonius Maria; Swinger Platt, Heather Anne

2017-05-09

Photovoltaic sub-cell interconnect systems and methods are provided. In one embodiment, a photovoltaic device comprises a thin film stack of layers deposited upon a substrate, wherein the thin film stack layers are subdivided into a plurality of sub-cells interconnected in series by a plurality of electrical interconnection structures; and wherein the plurality of electrical interconnection structures each comprise no more than two scribes that penetrate into the thin film stack layers.

Effect of atmospheric-pressure plasma treatment on the adhesion properties of a thin adhesive layer in a selective transfer process

NASA Astrophysics Data System (ADS)

Yoon, Min-Ah; Kim, Chan; Hur, Min; Kang, Woo Seok; Kim, Jaegu; Kim, Jae-Hyun; Lee, Hak-Joo; Kim, Kwang-Seop

2018-01-01

The adhesion between a stamp and thin film devices is crucial for their transfer on a flexible substrate. In this paper, a thin adhesive silicone layer on the stamp was treated by atmospheric pressure plasma to locally control the adhesion strength for the selective transfer. The adhesion strength of the silicone layer was significantly reduced after the plasma treatment, while its surface energy was increased. To understand the inconsistency between the adhesion strength and surface energy changes, the surface properties of the silicone layer were characterized using nanoindentation and X-ray photoelectron spectroscopy. These techniques revealed that a thin, hard, silica-like layer had formed on the surface from plasma-enhanced oxidation. This layer played an important role in decreasing the contact area and increasing the interfacial slippage, resulting in decreased adhesion. As a practical application, the transfer process was demonstrated on GaN LEDs that had been previously delaminated by a laser lift-off (LLO) process. Although the LEDs were not transferred onto the treated adhesive layer due to the reduced adhesion, the untreated adhesive layer could readily pick up the LEDs. It is expected that this simple method of controlling the adhesion of a stamp with a thin adhesive layer would enable a continuous, selective and large-scale roll-to-roll selective transfer process and thereby advance the development of flexible, stretchable and wearable electronics.

Synthesis and characterization of Zn(O,OH)S and AgInS2 layers to be used in thin film solar cells

NASA Astrophysics Data System (ADS)

Vallejo, W.; Arredondo, C. A.; Gordillo, G.

2010-11-01

In this paper AgInS2 and Zn(O,OH)S thin films were synthesized and characterized. AgInS2 layers were grown by co-evaporation from metal precursors in a two-step process, and, Zn(O,OH)S thin films were deposited from chemical bath containing thiourea, zinc acetate, sodium citrate and ammonia. X-ray diffraction measurements indicated that AgInS2 thin films grown with chalcopyrite structure, and the as-grown Zn(O,OH)S thin films were polycrystalline. It was also found that the AgInS2 films presented p-type conductivity, a high absorption coefficient (greater than 104 cm-1) and energy band-gap Eg of about 1.95 eV, Zn(O,OH),S thin films presented Eg of about 3.89 eV. Morphological analysis showed that under this synthesis conditions Zn(O,OH),S thin films coated uniformly the absorber layer. Additionally, the Zn(O,OH)S kinetic growth on AgInS2 layer was studied also. Finally, the results suggest that these layers possibly could be used in one-junction solar cells and/or as top cell in a tandem solar cell.

Deformation behavior of coherently strained InAs/GaAs(111)A heteroepitaxial systems: Theoretical calculations and experimental measurements

NASA Astrophysics Data System (ADS)

Zepeda-Ruiz, Luis A.; Pelzel, Rodney I.; Nosho, Brett Z.; Weinberg, W. Henry; Maroudas, Dimitrios

2001-09-01

A comprehensive, quantitative analysis is presented of the deformation behavior of coherently strained InAs/GaAs(111)A heteroepitaxial systems. The analysis combines a hierarchical theoretical approach with experimental measurements. Continuum linear elasticity theory is linked with atomic-scale calculations of structural relaxation for detailed theoretical studies of deformation in systems consisting of InAs thin films on thin GaAs(111)A substrates that are mechanically unconstrained at their bases. Molecular-beam epitaxy is used to grow very thin InAs films on both thick and thin GaAs buffer layers on epi-ready GaAs(111)A substrates. The deformation state of these samples is characterized by x-ray diffraction (XRD). The interplanar distances of thin GaAs buffer layers along the [220] and [111] crystallographic directions obtained from the corresponding XRD spectra indicate clearly that thin buffer layers deform parallel to the InAs/GaAs(111)A interfacial plane, thus aiding in the accommodation of the strain induced by lattice mismatch. The experimental measurements are in excellent agreement with the calculated lattice interplanar distances and the corresponding strain fields in the thin mechanically unconstrained substrates considered in the theoretical analysis. Therefore, this work contributes direct evidence in support of our earlier proposal that thin buffer layers in layer-by-layer semiconductor heteroepitaxy exhibit mechanical behavior similar to that of compliant substrates [see, e.g., B. Z. Nosho, L. A. Zepeda-Ruiz, R. I. Pelzel, W. H. Weinberg, and D. Maroudas, Appl. Phys. Lett. 75, 829 (1999)].

Self-assembly of dodecaphenyl POSS thin films

NASA Astrophysics Data System (ADS)

Handke, Bartosz; Klita, Łukasz; Niemiec, Wiktor

2017-12-01

The self-assembly abilities of Dodecaphenyl Polyhedral Oligomeric Silsesquioxane thin films on Si(1 0 0) surfaces were studied. Due to their thermal properties - relatively low sublimation temperature and preservation of molecular structure - cage type silsesquioxanes are ideal material for the preparation of a thin films by Physical Vapor Deposition. The Ultra-High Vacuum environment and the deposition precision of the PVD method enable the study of early stages of thin film growth and its molecular organization. X-ray Reflectivity and Atomic Force Microscopy measurements allow to pursuit size-effects in the structure of thin films with thickness ranges from less than a single molecular layer up to several tens of layers. Thermal treatment of the thin films triggered phase change: from a poorly ordered polycrystalline film into a well-ordered multilayer structure. Self-assembly of the layers is the effect of the π-stacking of phenyl rings, which force molecules to arrange in a superlattice, forming stacks of alternating organic-inorganic layers.

Effect of Al doping on performance of ZnO thin film transistors

NASA Astrophysics Data System (ADS)

Dong, Junchen; Han, Dedong; Li, Huijin; Yu, Wen; Zhang, Shendong; Zhang, Xing; Wang, Yi

2018-03-01

In this work, we investigate the Aluminum-doped Zinc Oxide (AZO) thin films and their feasibility as the active layer for thin film transistors (TFTs). A comparison on performance is made between the AZO TFTs and ZnO TFTs. The electrical properties such as saturation mobility, subthreshold swing, and on-to-off current ratio are improved when AZO is utilized as the active layer. Oxygen component of the thin film materials indicates that Al is the suppressor for oxygen defect in active layer, which improves the subthreshold swing. Moreover, based on band structure analyzation, we observe that the carrier concentration of AZO is higher than ZnO, leading to the enhancement of saturation mobility. The microstructure of the thin films convey that the AZO films exhibit much smaller grain boundaries than ZnO films, which results in the lower off-state current and higher on-to-off current ratio of AZO TFTs. The AZO thin films show huge potential to be the active layer of TFTs.

Molecular Engineering for Enhanced Charge Transfer in Thin-Film Photoanode.

PubMed

Kim, Jeong Soo; Kim, Byung-Man; Kim, Un-Young; Shin, HyeonOh; Nam, Jung Seung; Roh, Deok-Ho; Park, Jun-Hyeok; Kwon, Tae-Hyuk

2017-10-11

We developed three types of dithieno[3,2-b;2',3'-d]thiophene (DTT)-based organic sensitizers for high-performance thin photoactive TiO 2 films and investigated the simple but powerful molecular engineering of different types of bonding between the triarylamine electron donor and the conjugated DTT π-bridge by the introduction of single, double, and triple bonds. As a result, with only 1.3 μm transparent and 2.5-μm TiO 2 scattering layers, the triple-bond sensitizer (T-DAHTDTT) shows the highest power conversion efficiency (η = 8.4%; V OC = 0.73 V, J SC = 15.4 mA·cm -2 , and FF = 0.75) in an iodine electrolyte system under one solar illumination (AM 1.5, 1000 W·m -2 ), followed by the single-bond sensitizer (S-DAHTDTT) (η = 7.6%) and the double-bond sensitizer (D-DAHTDTT) (η = 6.4%). We suggest that the superior performance of T-DAHTDTT comes from enhanced intramolecular charge transfer (ICT) induced by the triple bond. Consequently, T-DAHTDTT exhibits the most active photoelectron injection and charge transport on a TiO 2 film during operation, which leads to the highest photocurrent density among the systems studied. We analyzed these correlations mainly in terms of charge injection efficiency, level of photocharge storage, and charge-transport kinetics. This study suggests that the molecular engineering of a triple bond between the electron donor and the π-bridge of a sensitizer increases the performance of dye-sensitized solar cell (DSC) with a thin photoactive film by enhancing not only J SC through improved ICT but also V OC through the evenly distributed sensitizer surface coverage.

Thin film photovoltaic device with multilayer substrate

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1984-01-01

A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

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

Gupta, Sanju, E-mail: sanju.gupta@wku.edu; Price, Carson

2015-10-15

Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO){sub 1}, (PPy/ErGO){sub 1}, (PAni/GO){sub 1} and (PPy/GO){sub 1}. The rationale design is to create thin films that possess interconnectedmore » graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, C{sub s}, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent C{sub s} of ≥350 F g{sup −1} as compared with constituents (∼70 F g{sup −1}) at discharge current density of 0.3 A g{sup −1} that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (re)activity of surface ion adsorption sites density at solid/liquid interface.« less

Controlled placement and orientation of nanostructures

DOEpatents

Zettl, Alex K; Yuzvinsky, Thomas D; Fennimore, Adam M

2014-04-08

A method for controlled deposition and orientation of molecular sized nanoelectromechanical systems (NEMS) on substrates is disclosed. The method comprised: forming a thin layer of polymer coating on a substrate; exposing a selected portion of the thin layer of polymer to alter a selected portion of the thin layer of polymer; forming a suspension of nanostructures in a solvent, wherein the solvent suspends the nanostructures and activates the nanostructures in the solvent for deposition; and flowing a suspension of nanostructures across the layer of polymer in a flow direction; thereby: depositing a nanostructure in the suspension of nanostructures only to the selected portion of the thin layer of polymer coating on the substrate to form a deposited nanostructure oriented in the flow direction. By selectively employing portions of the method above, complex NEMS may be built of simpler NEMSs components.

Double layer mixed matrix membrane adsorbers improving capacity and safety hemodialysis

NASA Astrophysics Data System (ADS)

Saiful; Borneman, Z.; Wessling, M.

2018-05-01

Double layer mixed matrix membranes adsorbers have been developed for blood toxin removal by embedding activated carbon into cellulose acetate macroporous membranes. The membranes are prepared by phase inversion method via water vapor induced phase separation followed by an immersion precipitation step. Double layer MMM consisting of an active support and a separating layer. The active support layer consists of activated carbon particles embedded in macroporous cellulose acetate; the separating layer consists of particle free cellulose acetate. The double layer membrane possess an open and interconnected macroporous structure with a high loading of activated carbon available for blood toxins removal. The MMM AC has a swelling degree of 6.5 %, porosity of 53 % and clean water flux of 800 Lm-2h-1bar-1. The prepared membranes show a high dynamic Creatinine (Crt) removal during hemodilysis process. The Crt removal by adsorption contributes to amore than 83 % of the total removal. The double layer adsorptive membrane proves hemodialysis membrane can integrated with adsorption, in which blood toxins are removed in one step.

Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

NASA Astrophysics Data System (ADS)

Deng, Z.; Wang, J.; Zheng, J.; Lin, Q.; Zhang, Y.; Wang, S.

2009-05-01

In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

Effect of inserting a hole injection layer in organic light-emitting diodes: A numerical approach

NASA Astrophysics Data System (ADS)

Lee, Hyeongi; Hwang, Youngwook; Won, Taeyoung

2015-01-01

For investigating the effect of inserting a hole injection layer (HIL), we carried out a computational study concerning organic light-emitting diodes (OLEDs) that had a thin CuPc layer as the hole injection layer. We used S-TAD (2, 2', 7, 7'-tetrakis-(N, Ndiphenylamino)-9, 9-spirobifluoren) for the hole transfer layer, S-DPVBi (4, 4'-bis (2, 2'-diphenylvinyl)-1, 1'-spirobiphenyl) for the emission layer and Alq3 (Tris (8-hyroxyquinolinato) aluminium) for the electron transfer layer. This tri-layer device was compared with four-layer devices. To this tri-layer device, we added a thin CuPc layer, which had a 5.3 eV highest occupied molecular orbital (HOMO) level and a 3.8 eV lowest unoccupied molecular orbital (LUMO) level, as a hole injection layer, and we chose this device for Device A. Also, we varied the LUMO level or the HOMO level of the thin CuPc layer. These two devices were identified as Device C and Device D, respectively. In this paper, we simulated the carrier injection, transport and recombination in these four devices. Thereby, we showed the effect of the HIL, and we demonstrated that the characteristics of these devices were improved by adding a thin layer of CuPc between the anode and the HTL.

Modification of Indirect Solar Dryer for Simplicia Production

NASA Astrophysics Data System (ADS)

Purnomo, C. W.; Indarti, S.

2018-03-01

Simplicia is natural ingredient for herbal medicine that has been subjected to drying only. This study aims to develop an appropriate drying equipment to produce dried leaves of sambung nyawa (Gynura procumbens (Lour.) Merr.) or also called “longevity spinach”. Typical indirect solar drier was modified to be able to process more fresh leaves in order to speed up the production. The modification was done using double solar collector and wind powered ventilation. The double solar collector was applied in order to collect more solar energy for larger dimension of drying chamber, while the wind-ventilator was installed to provide forced convection of hot air flow inside the dryer. The drying kinetic including the drying constants were investigated using three common thin layer drying equations to model the drying behavior of the leaves. The moisture ratio (MR) depletion with respect to the drying time (t) of the leaves can be well represented by equation of MR=1.1732exp(-0.0993.t)-0.1732exp(-17.3871.t).

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.

Activated carbon/manganese dioxide hybrid electrodes for high performance thin film supercapacitors

NASA Astrophysics Data System (ADS)

Jang, Yunseok; Jo, Jeongdai; Jang, Hyunjung; Kim, Inyoung; Kang, Dongwoo; Kim, Kwang-Young

2014-06-01

We combine the activated carbon (AC) and the manganese dioxide (MnO2) in a AC/MnO2 hybrid electrode to overcome the low capacitance of activated carbon and MnO2 by exploiting the large surface area of AC and the fast reversible redox reaction of MnO2. An aqueous permanganate (MnO4 -) is converted to MnO2 on the surface of the AC electrode by dipping the AC electrode into an aqueous permanganate solution. The AC/MnO2 hybrid electrode is found to display superior specific capacitance of 290 F/g. This shows that supercapacitors classified as electric double layer capacitors and pseudocapacitors can be combined together.

355-nm, nanosecond laser mirror thin film damage competition

NASA Astrophysics Data System (ADS)

Negres, Raluca A.; Stolz, Christopher J.; Thomas, Michael D.; Caputo, Mark

2017-11-01

This competition aimed to survey state-of-the-art UV high reflectors. The requirements of the coatings are a minimum reflection of 99.5% at 45 degrees incidence angle for P-polarized light at 355-nm. The choice of coating materials, design, and deposition method were left to the participants. Laser damage testing was performed at a single testing facility using the raster scan method with a 5-ns pulse length laser system operating at 10 Hz in a single longitudinal mode. A double blind test assured sample and submitter anonymity. In addition to the laser damage resistance results, details of the deposition processes, cleaning method, coating materials and layer count are also shared.

Electrophoretic interactions and aggregation of colloidal biological particles

NASA Technical Reports Server (NTRS)

Davis, Robert H.; Nichols, Scott C.; Loewenberg, Michael; Todd, Paul

1994-01-01

The separation of cells or particles from solution has traditionally been accomplished with centrifuges or by sedimentation; however, many particles have specific densities close to unity, making buoyancy-driven motion slow or negligible, but most cells and particles carry surface charges, making them ideal for electrophoretic separation. Both buoyancy-driven and electrophoretic separation may be influenced by hydrodynamic interactions and aggregation of neighboring particles. Aggregation by electrophoresis was analyzed for two non-Brownian particles with different zeta potentials and thin double layers migrating through a viscous fluid. The results indicate that the initial rate of electrophoretically-driven aggregation may exceed that of buoyancy-driven aggregation, even under conditions in which buoyancy-driven relative motion of noninteracting particles is dominant.

High work function transparent middle electrode for organic tandem solar cells

NASA Astrophysics Data System (ADS)

Moet, D. J. D.; de Bruyn, P.; Blom, P. W. M.

2010-04-01

The use of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) in combination with ZnO as middle electrode in solution-processed organic tandem solar cells requires a pH modification of the PEDOT:PSS dispersion. We demonstrate that this neutralization leads to a reduced work function of PEDOT:PSS, which does not affect the performance of polythiophene:fullerene solar cells, but results in a lower open-circuit voltage of devices based on a polyfluorene derivative with a higher ionization potential. The introduction of a thin layer of a perfluorinated ionomer recovers the anode work function and gives an open-circuit voltage of 1.92 V for a double junction polyfluorene-based solar cell.

Self-consistent electrostatic simulations of reforming double layers in the downward current region of the aurora

NASA Astrophysics Data System (ADS)

Gunell, H.; Andersson, L.; De Keyser, J.; Mann, I.

2015-10-01

The plasma on a magnetic field line in the downward current region of the aurora is simulated using a Vlasov model. It is found that an electric field parallel to the magnetic fields is supported by a double layer moving toward higher altitude. The double layer accelerates electrons upward, and these electrons give rise to plasma waves and electron phase-space holes through beam-plasma interaction. The double layer is disrupted when reaching altitudes of 1-2 Earth radii where the Langmuir condition no longer can be satisfied due to the diminishing density of electrons coming up from the ionosphere. During the disruption the potential drop is in part carried by the electron holes. The disruption creates favourable conditions for double layer formation near the ionosphere and double layers form anew in that region. The process repeats itself with a period of approximately 1 min. This period is determined by how far the double layer can reach before being disrupted: a higher disruption altitude corresponds to a longer repetition period. The disruption altitude is, in turn, found to increase with ionospheric density and to decrease with total voltage. The current displays oscillations around a mean value. The period of the oscillations is the same as the recurrence period of the double layer formations. The oscillation amplitude increases with increasing voltage, whereas the mean value of the current is independent of voltage in the 100 to 800 V range covered by our simulations. Instead, the mean value of the current is determined by the electron density at the ionospheric boundary.

Structural characterization of ultrathin Cr-doped ITO layers deposited by double-target pulsed laser ablation

NASA Astrophysics Data System (ADS)

Cesaria, Maura; Caricato, Anna Paola; Leggieri, Gilberto; Luches, Armando; Martino, Maurizio; Maruccio, Giuseppe; Catalano, Massimo; Grazia Manera, Maria; Rella, Roberto; Taurino, Antonietta

2011-09-01

In this paper we report on the growth and structural characterization of very thin (20 nm) Cr-doped ITO films, deposited at room temperature by double-target pulsed laser ablation on amorphous silica substrates. The role of Cr atoms in the ITO matrix is carefully investigated with increasing doping content by transmission electron microscopy (TEM). Selected-area electron diffraction, conventional bright field and dark field as well as high-resolution TEM analyses, and energy dispersive x-ray spectroscopy demonstrate that (i) crystallization features occur despite the low growth temperature and small thickness, (ii) no chromium or chromium oxide secondary phases are detectable, regardless of the film doping levels, (iii) the films crystallize as crystalline flakes forming large-angle grain boundaries; (iv) the observed flakes consist of crystalline planes with local bending of the crystal lattice. Thickness and compositional information about the films are obtained by Rutherford back-scattering spectrometry. Results are discussed by considering the combined effects of growth temperature, smaller ionic radius of the Cr cation compared with the trivalent In ion, doping level, film thickness, the double-target doping technique and peculiarities of the pulsed laser deposition method.

Growth of multilayered polycrystalline reaction rims in the MgO-SiO2 system, part I: experiments

NASA Astrophysics Data System (ADS)

Gardés, E.; Wunder, B.; Wirth, R.; Heinrich, W.

2011-01-01

Growth of transport-controlled reaction layers between single crystals of periclase and quartz, and forsterite and quartz was investigated experimentally at 1.5 GPa, 1100°C to 1400°C, 5 min to 72 h under dry and melt-free conditions using a piston-cylinder apparatus. Starting assemblies consisting of Per | Qtz | Fo sandwiches produced polycrystalline double layers of forsterite and enstatite between periclase and quartz, and enstatite single layers between forsterite and quartz. The position of inert Pt-markers initially deposited at the interface of the reactants and inspection of mass balance confirmed that both layer-producing reactions are controlled by MgO diffusion, while SiO2 is relatively immobile. BSE and TEM imaging revealed thicknesses from 0.6 μm to 14 μm for double layers and from 0 to 6.8 μm for single layers. Both single and double layers displayed non-parabolic growth together with pronounced grain coarsening. Textural evolution and growth rates for each reaction are directly comparable. Forsterite-enstatite double layers are always wider than enstatite single layers, and the growth of enstatite in the double layer is slower than that in the single layer. In double layers, the enstatite/forsterite layer thickness ratio significantly increases with temperature, reflecting different MgO mobilities as temperature varies. Thus, thickness ratios in multilayered reaction zones may contain a record of temperature, but also that of any physico-chemical parameter that modifies the mobilities of the chemical components between the various layers. This potential is largely unexplored in geologically relevant systems, which calls for further experimental studies of multilayered reaction zones.

Double-Layer Gadolinium Zirconate/Yttria-Stabilized Zirconia Thermal Barrier Coatings Deposited by the Solution Precursor Plasma Spray Process

NASA Astrophysics Data System (ADS)

Jiang, Chen; Jordan, Eric H.; Harris, Alan B.; Gell, Maurice; Roth, Jeffrey

2015-08-01

Advanced thermal barrier coatings (TBCs) with lower thermal conductivity, increased resistance to calcium-magnesium-aluminosilicate (CMAS), and improved high-temperature capability, compared to traditional yttria-stabilized zirconia (YSZ) TBCs, are essential to higher efficiency in next generation gas turbine engines. Double-layer rare-earth zirconate/YSZ TBCs are a promising solution. From a processing perspective, solution precursor plasma spray (SPPS) process with its unique and beneficial microstructural features can be an effective approach to obtaining the double-layer microstructure. Previously durable low-thermal-conductivity YSZ TBCs with optimized layered porosity, called the inter-pass boundaries (IPBs) were produced using the SPPS process. In this study, an SPPS gadolinium zirconate (GZO) protective surface layer was successfully added. These SPPS double-layer TBCs not only retained good cyclic durability and low thermal conductivity, but also demonstrated favorable phase stability and increased surface temperature capabilities. The CMAS resistance was evaluated with both accumulative and single applications of simulated CMAS in isothermal furnaces. The double-layer YSZ/GZO exhibited dramatic improvement in the single application, but not in the continuous one. In addition, to explore their potential application in integrated gasification combined cycle environments, double-layer TBCs were tested under high-temperature humidity and encouraging performance was recorded.

Organic doping of rotated double layer graphene

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

George, Lijin; Jaiswal, Manu, E-mail: manu.jaiswal@iitm.ac.in

2016-05-06

Charge transfer techniques have been extensively used as knobs to tune electronic properties of two- dimensional systems, such as, for the modulation of conductivity \\ mobility of single layer graphene and for opening the bandgap in bilayer graphene. The charge injected into the graphene layer shifts the Fermi level away from the minimum density of states point (Dirac point). In this work, we study charge transfer in rotated double-layer graphene achieved by the use of organic dopant, Tetracyanoquinodimethane. Naturally occurring bilayer graphene has a well-defined A-B stacking whereas in rotated double-layer the two graphene layers are randomly stacked with differentmore » rotational angles. This rotation is expected to significantly alter the interlayer interaction. Double-layer samples are prepared using layer-by-layer assembly of chemical vapor deposited single-layer graphene and they are identified by characteristic resonance in the Raman spectrum. The charge transfer and distribution of charges between the two graphene layers is studied using Raman spectroscopy and the results are compared with that for single-layer and A-B stacked bilayer graphene doped under identical conditions.« 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.

Oriented conductive oxide electrodes on SiO2/Si and glass

DOEpatents

Jia, Quanxi; Arendt, Paul N.

2001-01-01

A thin film structure is provided including a silicon substrate with a layer of silicon dioxide on a surface thereof, and a layer of cubic oxide material deposited upon the layer of silicon dioxide by ion-beam-assisted-deposition, said layer of cubic oxide material characterized as biaxially oriented. Preferably, the cubic oxide material is yttria-stabilized zirconia. Additional thin layers of biaxially oriented ruthenium oxide or lanthanum strontium cobalt oxide are deposited upon the layer of yttria-stabilized zirconia. An intermediate layer of cerium oxide is employed between the yttria-stabilized zirconia layer and the lanthanum strontium cobalt oxide layer. Also, a layer of barium strontium titanium oxide can be upon the layer of biaxially oriented ruthenium oxide or lanthanum strontium cobalt oxide. Also, a method of forming such thin film structures, including a low temperature deposition of a layer of a biaxially oriented cubic oxide material upon the silicon dioxide surface of a silicon dioxide/silicon substrate is provided.

Electron temperature differences and double layers

NASA Technical Reports Server (NTRS)

Chan, C.; Hershkowitz, N.; Lonngren, K. E.

1983-01-01

Electron temperature differences across plasma double layers are studied experimentally. It is shown that the temperature differences across a double layer can be varied and are not a result of thermalization of the bump-on-tail distribution. The implications of these results for electron thermal energy transport in laser-pellet and tandem-mirror experiments are also discussed.

Damped response of shells by a constrained viscoelastic layer

NASA Technical Reports Server (NTRS)

El-Raheb, M.; Wagner, P.

1986-01-01

Vibration absorbers are introduced into an asymmetric configuration of thin cylinders and tori enclosing an acoustic medium. The absorbers consist of thin axial strips bonded to the cylinder with a thin viscoelastic layer. The constrained layer dissipates the energy of relative motions between strip and cylinder. The absorber is most effective on response modes with two or more circumferential waves. The use of transfer matrices is extended to the coupled cylinder-absorber system.

Photocurrent generation in SnO2 thin film by surface charged chemisorption O ions

NASA Astrophysics Data System (ADS)

Lee, Po-Ming; Liao, Ching-Han; Lin, Chia-Hua; Liu, Cheng-Yi

2018-06-01

We report a photocurrent generation mechanism in the SnO2 thin film surface layer by the charged chemisorption O ions on the SnO2 thin film surface induced by O2-annealing. A critical build-in electric field in the SnO2 surface layer resulted from the charged O ions on SnO2 surface prolongs the lifetime and reduces the recombination probability of the photo-excited electron-hole pairs by UV-laser irradiation (266 nm) in the SnO2 surface layer, which is the key for the photocurrent generation in the SnO2 thin film surface layer. The critical lifetime of prolonged photo-excited electron-hole pair is calculated to be 8.3 ms.

Multi-oxide active layer deposition using Applied Materials Pivot array coater for high-mobility metal oxide TFT

NASA Astrophysics Data System (ADS)

Park, Hyun Chan; Scheer, Evelyn; Witting, Karin; Hanika, Markus; Bender, Marcus; Hsu, Hao Chien; Yim, Dong Kil

2015-11-01

By controlling a thin indium tin oxide (ITO), indium zinc oxide interface layer between gate insulator and indium gallium zinc oxide (IGZO), the thin-film transistor (TFT) performance can reach higher mobility as conventional IGZO as well as superior stability. For large-area display application, Applied Materials static PVD array coater (Applied Materials GmbH & Co. KG, Alzenau, Germany) using rotary targets has been developed to enable uniform thin layer deposition in display industry. Unique magnet motion parameter optimization in Pivot sputtering coater is shown to provide very uniform thin ITO layer to reach TFT performance with high mobility, not only on small scale, but also on Gen8.5 (2500 × 2200 mm glass size) production system.

Highly stable thin film transistors using multilayer channel structure

NASA Astrophysics Data System (ADS)

Nayak, Pradipta K.; Wang, Zhenwei; Anjum, D. H.; Hedhili, M. N.; Alshareef, H. N.

2015-03-01

We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60 °C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

Method of manufacturing a shapeable short-resistant capacitor

DOEpatents

Taylor, Ralph S.; Myers, John D.; Baney, William J.

2013-04-02

A method that employs a novel combination of conventional fabrication techniques provides a ceramic short-resistant capacitor that is bendable and/or shapeable to provide a multiple layer capacitor that is extremely compact and amenable to desirable geometries. The method allows thinner and more flexible ceramic capacitors to be made. The method includes forming a first thin metal layer on a substrate; depositing a thin, ceramic dielectric layer over the metal layer; depositing a second thin metal layer over the dielectric layer to form a capacitor exhibiting a benign failure mode; and separating the capacitor from the substrate. The method may also include bending the resulting capacitor into a serpentine arrangement with gaps between the layers that allow venting of evaporated electrode material in the event of a benign failure.

Method and apparatus for fabricating a thin-film solar cell utilizing a hot wire chemical vapor deposition technique

DOEpatents

Wang, Qi; Iwaniczko, Eugene

2006-10-17

A thin-film solar cell is provided. The thin-film solar cell comprises an a-SiGe:H (1.6 eV) n-i-p solar cell having a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer by hot wire chemical vapor deposition. A method for fabricating a thin film solar cell is also provided. The method comprises depositing a n-i-p layer at a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer.

Compressive and rarefactive double layers in non-uniform plasma with q-nonextensive distributed electrons

NASA Astrophysics Data System (ADS)

Shan, S. Ali; Saleem, H.

2018-05-01

Electrostatic solitary waves and double layers (DLs) formed by the coupled ion acoustic (IA) and drift waves have been investigated in non-uniform plasma using q-nonextensive distribution function for the electrons and assuming ions to be cold Ti< Te. It is found that both compressive and rarefactive nonlinear structures (solitary waves and DLs) are possible in such a system. The steeper gradients are supportive for compressive solitary (and double layers) and destructive for rarefactive ones. The q-nonextensivity parameter q and the magnitudes of gradient scale lengths of density and temperature have significant effects on the amplitude of the double layers (and double layers) as well as on the speed of these structures. This theoretical model is general which has been applied here to the F-region ionosphere for illustration.

A fluid description of plasma double-layers

NASA Technical Reports Server (NTRS)

Levine, J. S.; Crawford, F. W.

1979-01-01

The space-charge double-layer that forms between two plasmas with different densities and thermal energies was investigated using three progressively realistic models which are treated by fluid theory, and take into account four species of particles: electrons and ions reflected by the double-layer, and electrons and ions transmitted through it. The two plasmas are assumed to be cold, and the self-consistent potential, electric field and space-charge distributions within the double-layer are determined. The effects of thermal velocities are taken into account for the reflected particles, and the modifications to the cold plasma solutions are established. Further modifications due to thermal velocities of the transmitted particles are examined. The applicability of a one dimensional fluid description, rather than plasma kinetic theory, is discussed. Theoretical predictions are compared with double layer potentials and lengths deduced from laboratory and space plasma experiments.

A new hydrodynamic analysis of double layers

NASA Technical Reports Server (NTRS)

Hora, Heinrich

1987-01-01

A genuine two-fluid model of plasmas with collisions permits the calculation of dynamic (not necessarily static) electric fields and double layers inside of plasmas including oscillations and damping. For the first time a macroscopic model for coupling of electromagnetic and Langmuir waves was achieved with realistic damping. Starting points were laser-produced plasmas showing very high dynamic electric fields in nonlinear force-produced cavitous and inverted double layers in agreement with experiments. Applications for any inhomogeneous plasma as in laboratory or in astrophysical plasmas can then be followed up by a transparent hydrodynamic description. Results are the rotation of plasmas in magnetic fields and a new second harmonic resonance, explanation of the measured inverted double layers, explanation of the observed density-independent, second harmonics emission from laser-produced plasmas, and a laser acceleration scheme by the very high fields of the double layers.

Synergetic effect of double-step blocking layer for the perovskite solar cell

NASA Astrophysics Data System (ADS)

Kim, Jinhyun; Hwang, Taehyun; Lee, Sangheon; Lee, Byungho; Kim, Jaewon; Kim, Jaewook; Gil, Bumjin; Park, Byungwoo

2017-10-01

In an organometallic CH3NH3PbI3 (MAPbI3) perovskite solar cell, we have demonstrated a vastly compact TiO2 layer synthesized by double-step deposition, through a combination of sputter and solution deposition to minimize the electron-hole recombination and boost the power conversion efficiency. As a result, the double-step strategy allowed outstanding transmittance of blocking layer. Additionally, crystallinity and morphology of the perovskite film were significantly modified, provoking enhanced photon absorption and solar cell performance with the reduced recombination rate. Thereby, this straightforward double-step strategy for the blocking layer exhibited 12.31% conversion efficiency through morphological improvements of each layer.

Directly Grown Nanostructured Electrodes for High Volumetric Energy Density Binder-Free Hybrid Supercapacitors: A Case Study of CNTs//Li4Ti5O12

NASA Astrophysics Data System (ADS)

Zuo, Wenhua; Wang, Chong; Li, Yuanyuan; Liu, Jinping

2015-01-01

Hybrid supercapacitor (HSC), which typically consists of a Li-ion battery electrode and an electric double-layer supercapacitor electrode, has been extensively investigated for large-scale applications such as hybrid electric vehicles, etc. Its application potential for thin-film downsized energy storage systems that always prefer high volumetric energy/power densities, however, has not yet been explored. Herein, as a case study, we develop an entirely binder-free HSC by using multiwalled carbon nanotube (MWCNT) network film as the cathode and Li4Ti5O12 (LTO) nanowire array as the anode and study the volumetric energy storage capability. Both the electrode materials are grown directly on carbon cloth current collector, ensuring robust mechanical/electrical contacts and flexibility. Our 3 V HSC device exhibits maximum volumetric energy density of ~4.38 mWh cm-3, much superior to those of previous supercapacitors based on thin-film electrodes fabricated directly on carbon cloth and even comparable to the commercial thin-film lithium battery. It also has volumetric power densities comparable to that of the commercial 5.5 V/100 mF supercapacitor (can be operated within 3 s) and has excellent cycling stability (~92% retention after 3000 cycles). The concept of utilizing binder-free electrodes to construct HSC for thin-film energy storage may be readily extended to other HSC electrode systems.

Ultra-high current density thin-film Si diode

DOEpatents

Wang; Qi

2008-04-22

A combination of a thin-film .mu.c-Si and a-Si:H containing diode structure characterized by an ultra-high current density that exceeds 1000 A/cm.sup.2, comprising: a substrate; a bottom metal layer disposed on the substrate; an n-layer of .mu.c-Si deposited the bottom metal layer; an i-layer of .mu.c-Si deposited on the n-layer; a buffer layer of a-Si:H deposited on the i-layer, a p-layer of .mu.c-Si deposited on the buffer layer; and a top metal layer deposited on the p-layer.

Electron transport in ultra-thin films and ballistic electron emission microscopy

NASA Astrophysics Data System (ADS)

Claveau, Y.; Di Matteo, S.; de Andres, P. L.; Flores, F.

2017-03-01

We have developed a calculation scheme for the elastic electron current in ultra-thin epitaxial heterostructures. Our model uses a Keldysh’s non-equilibrium Green’s function formalism and a layer-by-layer construction of the epitaxial film. Such an approach is appropriate to describe the current in a ballistic electron emission microscope (BEEM) where the metal base layer is ultra-thin and generalizes a previous one based on a decimation technique appropriated for thick slabs. This formalism allows a full quantum mechanical description of the transmission across the epitaxial heterostructure interface, including multiple scattering via the Dyson equation, which is deemed a crucial ingredient to describe interfaces of ultra-thin layers properly in the future. We introduce a theoretical formulation needed for ultra-thin layers and we compare with results obtained for thick Au(1 1 1) metal layers. An interesting effect takes place for a width of about ten layers: a BEEM current can propagate via the center of the reciprocal space (\\overlineΓ ) along the Au(1 1 1) direction. We associate this current to a coherent interference finite-width effect that cannot be found using a decimation technique. Finally, we have tested the validity of the handy semiclassical formalism to describe the BEEM current.