13,413 research outputs found
Fermilab: science at work
No full textSix days. Three frontiers. One amazing lab. From 2010 to 2012, a film crew followed a group of scientists at the Department of Energy's Fermilab and filmed them at work and at home. This 40-minute documentary shows the diversity of the people, research and work at Fermilab. Viewers catch a true behind-the-scenes look of the United States' premier particle physics laboratory while scientists explain why their research is important to them and the world. Scientists included: Brendan Casey, Herman White, Craig Hogan, Denton Morris, Mary Convery, Bonnie Fleming, Deborah Harris, Dave Schmitz, Brenna Flaugher and Aron Soha
Evaporated organic films of tetrathiafulvalene and related materials
No full textThis thesis describes the design, construction and application of a novel vacuum system for the preparation of thin films of organic charge-transfer compounds. The method of thermal evaporation was used for four materials: tetrathiafulvalene (TTF) and three of its derivatives, dimethyltetrathiafiilvalene (DiMe-TTF), trimethyltetrathiafiilvalene (TriMe-TTF) and bis(ethylenedithio)tetrathiafiilvalene (BEDT-TTF). The resulting thin layers were characterised using optical and electron microscopy, infrared/visible spectroscopy and dc conductivity measurements down to 77K.Thin films of tetrathiafulvalene, after doping with iodine, exhibited a maximum value of dc, in-plane room temperature conductivity σ of 8.0+2.4 S cm(^-1). Semiconducting behaviour was exhibited over the range 77-300 K with AE = 0.09+0.02 eV. The effect of the deposition rate on fihn morphology is reported. TTF iodide layers were also prepared by co- evaporating the two components. These films exhibited a maximum conductivity of 2.9+0.4 S cm(^-1) at room temperature. Again, semiconducting behaviour was noted over the range 77- 300 K with AE = 0.2+0.02 eV. A comparison of the optical, structural and electrical properties of the two types of films is made. DiMe-TTF and TriMe-TTF thin films were also successfully prepared. Doping with iodine resulted in in-plane, dc room temperature conductivities of 10(^-6) and 10(^-7) S cm(^-1), respectively. These values, together with data from optical spectroscopy, suggested that both salts were in the full charge-transfer state. (BEDT-TTF) iodide thin films were deposited by evaporating the organic compound and subsequent doping. Doped films possessed a dc, in-plane room temperature conductivity of 10(^-3) S cm(^-1).Annealing these layers at 60ºC resulted in an increase in conductivity with a final value of 1.6 S cm(^-1). Semiconducting behaviour over the range 77-300 K was exhibited by the annealed films (ΔE = 0.028 eV).Finally, thin film transistors, incorporating TTF and BEDT-TTF doped layers, were fabricated and their electrical characteristics measured
Enhanced electrical and optical properties of room temperature deposited Aluminium doped Zinc Oxide (AZO) thin films by excimer laser annealing
No full textHigh quality transparent conductive oxides (TCOs) often require a high thermal budget fabrication process. In this study, Excimer Laser Annealing (ELA) at a wavelength of 248 nm has been explored as a processing mechanism to facilitate low thermal budget fabrication of high quality aluminium doped zinc oxide (AZO) thin films. 180 nm thick AZO films were prepared by radio frequency magnetron sputtering at room temperature on fused silica substrates. The effects of the applied RF power and the sputtering pressure on the outcome of ELA at different laser energy densities and number of pulses have been investigated. AZO films deposited with no intentional heating at 180 W, and at 2 mTorr of 0.2% oxygen in argon were selected as the optimum as-deposited films in this work, with a resistivity of 1×10−3 Ω.cm, and an average visible transmission of 85%. ELA was found to result in noticeably reduced resistivity of 5×10−4 Ω.cm, and enhancing the average visible transmission to 90% when AZO is processed with 5 pulses at 125 mJ/cm2. Therefore, the combination of RF magnetron sputtering and ELA, both low thermal budget and scalable techniques, can provide a viable fabrication route of high quality AZO films for use as transparent electrodes
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Films based on bacteriorhodopsin in sol-gel matrices
No full textThe bacteriorhodopsin film in gelatin matrixes which are used as sensitive
elements of integrated optic and fibre-optic sensors of various vapor and gases
components will not be able to carry out the chemical control of aqueous
solutions. In the given paper the results of technological development of
obtaining the bacteriorhodopsin (bR) films in a sol-gel matrix are represented.
The films are obtained in a broad thickness range (from 0.5 to 20 microns) with
various bR concentrations and photosensitize additives. The optimal
technological conditions of obtaining of uniform films with given optical
parameters are defined. The surface morphology and cross section of the obtained
films was studied using an AFM and SEM. The films have a reasonable surface
roughness (~ 100 nm) and a uniform distribution of the purple membrane fragments
in the nanostructured sol-gel glass matrix along the films surface and
thickness. The transmission spectrums have the characteristic for bR the
absorption band, the value of which depends on bR concentration and
technological features of the films deposition. The investigated photosensitive
properties of the obtained films and influence on them of chemical components of
aqueous solutions, allow recommending the thin bR films in sol-gel matrixes for
creation of planar waveguides in the role of components of the chemical sensors
of liquid solutions
Giant dielectric permittivity in ferroelectric thin films : domain wall ping pong
No full textThis study was supported by the National Key Basic Research Program of China (No. 2014CB921004), the National Natural Science Foundation of China (Nos. 61225020 and 61176121), and the Program for Professor of Special Appointment (Eastern Scholar) in Shanghai. C.S.H. acknowledges the support of the Global Research Laboratory Program (2012040157) through the National Research Foundation (NRF) of Korea. Date of Acceptance: 02/09/2015The dielectric permittivity in ferroelectric thin films is generally orders of magnitude smaller than in their bulk. Here, we discover a way of increasing dielectric constants in ferroelectric thin films by ca. 500% by synchronizing the pulsed switching fields with the intrinsic switching time (nucleation of domain plus forward growth from cathode to anode). In a 170-nm lead zirconate titanate thin film with an average grain size of 850' this produces a dielectric constant of 8200 with the maximum nucleus density of 3.8 μ1-2, which is one to three orders of magnitude higher than in other dielectric thin films. This permits smaller capacitors in memory devices and is a step forward in making ferroelectric domain-engineered nano-electronics.Peer reviewe
Fabrication, characterisation, and optical applications of electrochemically deposited nanostructured IrOx films
No full textIn this work, nanostructured iridium oxide films were fabricated by electrochemical deposition within a template made with polystyrene spheres on gold substrates. SEM pictures show that the nanostructured IrOx films have a very ordered hexagonal structure. To our knowledge, this is the first report of templated deposition of nanostructured IrOx films and only the 2nd of fabrication of templated deposition of nanostructured electrochromic metal oxides.The deposition solution was carried out under voltammetric control with a solution made from iridium tetrachloride, hydrogen peroxide, oxalic acid and potassium carbonate based on a recipe reported by Yamanaka (Anodically Electrodeposited Iridium Oxide-Films (AEIROF) from Alkaline-Solutions for Electrochromic Display Devices, Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. 1989, 28, 632). Both non structured and nanostructured IrOx films were grown with the deposition solution. During the voltammetry, the growth of the film was followed by monitoring the cathodic peaks and anodic peaks which reflect redox reactions Ir(?) / Ir(IV) and Ir(IV) / Ir(V) within the IrOx oxide film. During the deposition, the peak currents increase almost linearly with the number of voltammetric cycles thus allowing a fine control of the deposition process. Several attempts were made to estimate the film thickness and establish a relationship between film thickness and deposition cycles. The thickness of the nanostructured films is particularly difficult to measure accurately. Following deposition, the electrochemistry of the nanostructured IrOx films was characterised with cyclic voltammetry in both acid and base solutions.Optical properties of the nanostructured IrOx films were investigated. The transmittance of a nanostructured IrOx films was measured with transparent ITO substrates. The novel idea of coating a thin layer of IrOx film on a nanostructured gold surface was investigated to test whether the electrochromism of the nanostructured IrOx film could be used to alter the surface plasmons of the nanostructured substrate. The nanostructured IrOx film worked as a surface plasmon modulator when its colours shifted between dark and transparent under potential control. The reflectance of thickness-graded nanostructured IrOx films was measured over a range of incident angles for different potentials. Following very recent publications on the theoretical modelling of light interaction with nanostructured gold films, an attempt was made to analyse the results obtained with the nanostructured IrOx films in terms of the interplay between the localised and delocalised surface plasmons
Properties of Al-doped ZnS films grown by chemical bath deposition
No full textZinc sulphide (ZnS) buffer layers are a cadmium free, wider energy band gap, alternative to the cadmium sulphide(CdS) buffer layers commonly used in copper indium gallium diselenide (CuInGaSe2)-based solar cells. However extrinsic doping of the ZnS is important to lower the resistivity of the layers and to improve flexibility of device design. In this work, Al-doped ZnS nanocrystalline films have been produced on glass substrates using a chemical bath deposition (CBD) method. The Al- concentration was varied from 0 at. % to 10 at. %, keeping other deposition parameters constant. The elemental composition of a typical sample with 6 at. % ‘Al’ in ZnS was Zn=44.9 at. %, S=49.8 at. % and Al=5.3 at.%. The X-ray diffraction data taken on these samples showed a broad peak corresponding to the (111) plane of ZnS while the crystallite size varied in the range, 8 – 15 nm, depending on the concentration of Al in the layers. The films with a Al-doping content of 6 at. % had an optical transmittance of 75 % in the visible range and the energy band gap evaluated from the data was 3.66 eV. The films n-type electrical conductivities and the electrical resistivity varied in the range, 107-103 Ωcm, it decreasing with an increase of the Al-concentration in the solution
Preparation and characterization of suitable insulating and transparent conducting thin films for thin film electroluminescent devices by sol-gel process
No full textThin film electroluminescent (TFEL) displays are attractive because they are light, have low power consumption, wide viewing angle and long lifetime, are extremely rugged and can be used in hostile environments. Recently, there has been a renewed interest in thin film electroluminescent devices because of their promising application to head mounted displays for use in automobiles, aircraft, microsurgery and virtual reality applications. Both conventional and inverted thin film electroluminescent device structures consist of insulating film, transparent conducting film and luminescent layer. In a thin film electroluminescent device, the luminescent layer is sandwiched between two insulating layers. Electrodes outside both insulating layers are used to apply an electric field, with one electrode being transparent.
These thin films are found to be sensitive to preparation conditions and can be prepared by a variety of methods, such as, magnetron sputtering, chemical vapour deposition, reactive electron beam evaporation, reactive thermal deposition, spray pyrolysis, laser ablation and more recently by sol-gel process. Nowadays, the sol-gel process is a wellaccepted technology for the preparation of thin films, monoliths, fibers and monosized powders. Compared to conventional thin film forming processes such as CVD, evaporation or sputtering, sol-gel film formation requires considerably less equipment and is potentially less expensive; however the most important advantage of sol-gel processing over conventional coating methods is the ability to control precisely the microstructure of the deposited film, i.e., the pore volume, pore size and surface area.
The sol-gel process is a method where the substrate to be coated is dipped into a liquid solution containing the active material. When the substrate is removed from the solution a thin layer remains. On exposure to the atmosphere a hydrolysis reaction takes place which solidifies the liquid film.
In this work, all the thin films have been prepared by using sol-gel process. Insulating films of titanium dioxide and tantalum oxide were prepared from titanium and tantalum alkoxides respectively and their characteristics have been investigated. The most important requirements for the insulating layers are high dielectric constant and high electric field strength. The dielectric constants of the films were calculated from the maximum capacitance of the Al/film/Si structure. The maximum dielectric constants for Ti02 and Ta20 5 films were approximately 50 and 82 respectively annealed at 700°C in oxygen. These results suggest that the Ti02 and Ta2Os thin film can be used as a high dielectric constant insulating layer in thin film electroluminescent devices.
Highly conductive and transparent aluminum-doped zinc oxide thin films have been prepared from the solution of zinc acetate and aluminum nitrate in ethanol by the sol-gel process. The effect of changing the aluminum-to-zinc ratio from 0 to 5 at. % and annealing temperature from 0 to 700°C in air, oxygen and nitrogen has been investigated. The resistivities of thin films were measured as a function of annealing temperature and also as a function of aluminum dopant concentration in the solution. As-deposited films have high resistivity and high optical transmission. Annealing of the as-deposited films in atmosphere leads to a substantial reduction in resistivity. The films have a minimum value of resistivity of 1.3xl0'4 Q-cm for 0.8 at. % aluminum-doped zinc oxide annealed at 500°C in nitrogen and a maximum transmission of about 88% when deposited on glass substrates. X-ray diffraction measurements employing CuKa radiation were performed to determine the crystallinity of the ZnO:Al films which showed that the films were polycrystalline with a hexagonal structure when annealed at higher temperatures in air, oxygen and nitrogen.
Transparent conductive indium tin oxide (ITO) thin films have been prepared by a solgel
process. The starting solution was prepared by mixing indium chloride dissolved in acetylacetone and tin chloride dissolved in ethanol. 0-20 % by weight Sn-doped indium oxide (ITO) films were prepared by heat-treatment at above 400°C. The electrical, optical and structural properties of ITO thin films were investigated. The electrical resistivity was measured by using four-point probe method. The ITO thin films containing 10 wt.% Sn showed the minimum resistivity of p = 8.0xl0'4 Q-cm annealed at 500°C in nitrogen. The films have an optical transparency up to 89% at 900 nm. X-ray diffraction measurements employing CuKa radiation were performed to determine the crystallinity of the ITO films which showed that the ITO films were polycrystalline with a cubic bixbyite structure annealed in air, oxygen and nitrogen.
Aluminum doped zinc oxide thin films have been deposited on titanium dioxide and
tantalum oxide films on glass by sol-gel process. The resistivity of ZnO:Al thin films
deposited on titanium dioxide and tantalum oxide films on glass have a minimum value
of 2.5xl0'3 Q-cm and 9.6xl0'4 Q-cm respectively annealed at 500°C in nitrogen. ZnO:Al
thin films deposited on titanium dioxide film on glass have a higher resistivity than that
deposited on glass. This increase in resistivity on titanium dioxide film is due to the
diffusion of titanium into the zinc oxide layer.
Indium tin oxide thin films have been deposited on titanium dioxide and tantalum oxide
films on glass for thin film electroluminescent devices. The resistivity of ITO films
deposited on titanium dioxide and tantalum oxide films has a minimum value of 9.5x1 O'4
Q-cm and 9.0x10'4 Q-cm respectively annealed at 500°C in nitrogen which are as low as
the resistivity of ITO films deposited on glass. This combination of transparent conductive ITO thin films and titanium dioxide or tantalum oxide insulating layer can be
used for thin film electroluminescent devices
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