Conductivity Of Metal Films Research Articles

Rapid selective metal patterning on polydimethylsiloxane (PDMS) fabricated by capillarity-assisted laser direct write

In this study we demonstrate a novel approach for the rapid fabricating micro scale metal (silver) patterning directly on a polydimethylsiloxane (PDMS) substrate. Silver nanoparticles were sintered on PDMS to form conductive metal films using laser direct write (LDW) technology. To achieve good metal film quality, a capillarity-assisted laser direct writing (CALDW) of nanoparticle suspensions on a low surface energy material (PDMS) was utilized. Experimental results showed controllable electrical conductivities and good film properties of the sintered silver patterns. This study reveals an advanced method of metal patterning on PDMS, and proposes a new research application of LDW in a nanoparticle colloidal environment.

Light passage through a film with subwavelength slits

The effect of anomalously high transmission of an electromagnetic wave through a periodic array of subwavelength slits in a metal film was studied. Results of numerical simulation were compared with theoretical and semi-analytical calculations of anomalous transmission through a silver film. Transmission through a perfectly conductive metal film with subwavelength slits was considered; anomalous transmission through it was detected.

Optical absorption losses in metal layers used in thin film solar cells

AbstractWe apply optical transmittance and reflectance spectroscopy, photothermal deflection spectroscopy (PDS) and laser calorimetry (LC) to evaluate optical absorption losses at rough interface between thin conductive oxide (TCO) and metal films used as backreflectors and electrical contacts in thin film solar cells. The paper proposes a simple method how to model the dielectric function of rough metal layers used in thin film solar cells. We show that the rough metal layer optically behaves as a semi‐infinite layer with modified dielectric function calculated by the Landau–Lifshitz–Looyenga (LLL) model from the dielectric function of a smooth metal, the dielectric function of TCO and just one free parameter that needs to be found by fitting the total optical absorptance. This approach can be used to simplify the modelling of the optical properties of thin film solar cells.

Optical Emission from the Interaction of Fast Electrons with Metallic Films Containing a Circular Aperture: A Study of Radiative Decoherence of Fast Electrons

Light emission resulting from the interaction of swift electrons with a distant material is shown to produce an unexpectedly large fraction of decoherence in the moving charges. The decoherence probability diverges for an electron passing through a hole drilled in a perfectly conducting metal film, regardless of the size of the opening. This divergence, which is logarithmic in the ratio of film radius to aperture radius, originates in an infrared catastrophe that differs from other sources of decoherence (e.g., bremsstrahlung radiation). Our results provide new avenues for controlling and assessing the role of coherence during electron acceleration (for example, in transmission electron microscopes) and for exploiting partial quantum interference of fast electrons.

Fabricating atom chips with femtosecond laser ablation

We report on the microfabrication of atom chips using a femtosecond laser ablation technique to arbitrarily sculpture both thin conductive metal films and permanent magnetic materials. We have measured the threshold fluences for a variety of materials relevant to atom chip development (Au, Ag, Cu, Cr, Ni, TbGdFeCo, SmCo, CoCr). The quality of the ablation process is investigated by extracting the power spectral density of the edge roughness from composite scanning electron microscope images and through the use of a magnetoresistance microscope to measure the associated magnetic field noise. Finally, we present results from a sculptured wire which produces an array of tunable double wells designed for near-surface force sensing with Bose–Einstein condensates.

A low-cure-temperature copper nano ink for highly conductive printed electrodes

We have developed a copper metal-organic-based conductive ink which can be applied to printing and roll-to-roll processes. Metal-organics printed on flexible substrates decompose into highly conductive copper metal when annealed at above 250 °C. The new nano ink was prepared by mixing copper carboxylate with copper complex nano particles of a mean size below 100 nm. The viscosity of the copper ink was in the range of 10 4–10 5 mPa s (at 50 rpm). The resistivity of the conductive film, after annealing under the condition of 3% H 2 above 250 °C for 20 min, was below 10 μΩ cm and it could be further reduced to 4.4 μΩ cm when annealed at 320 °C for 20 min. We successfully demonstrated a printable copper nano ink that proceeds to form highly conductive metal film when annealed at low temperature on flexible substrates.

Prediction of size effect on thermal conductivity of nanoscale metallic films

Incorporating both the scattering mechanisms of the rough film surfaces and the microscopic grain boundaries, we report on a realistic simulation of the in-plane thermal conductivity of nanoscale gold, copper and aluminum films on the basis of non-interacting electron and kinetic theory. The results are consistent with previous theoretical analyses and molecular dynamic simulations, as well as available experimental data. The thermal conductivity of metallic films is found to drop much below the bulk value, even showing dielectric effects. As with the size effect on the electrical conductivity of metallic films, the fine-grain structure has a greater effect on the thermal conductivity than the film surface properties. The influence of temperature on the thermal conductivity is also investigated.

Nanosized Glass Frit as an Adhesion Promoter for Ink‐Jet Printed Conductive Patterns on Glass Substrates Annealed at High Temperatures

AbstractInk‐jet printed metal nanoparticle films have been shown to anneal at high temperatures (above 500 °C) to highly conductive metal films on glass or ceramic substrates, but they suffer from cracking and inadequate substrate adhesion. Here, we report printable conductive materials, with added nanosized glass frit that can be annealed at 500 °C to form a crack‐free dense microstructure that adheres well to glass substrates. This overcomes the previous challenges while still retaining the desired high film conductivity. Controlling the particle characteristics and dispersion behavior plays an important role in successfully incorporating the glass frit into the conductive inks.

고분자전해질 연료전지용 바이폴라 플레이트의 다층 코팅의 증착

The surface region of commercial stainless steel 304 and 316 plates has been modified through deposition of the multi-layered coatings composed of titanium film (0.1 ㎛) and gold film (1-2 ㎛) by an electron beam evaporation method. XRD patterns of the stainless steel plates deposited with conductive metal films showed the peaks of the external gold film and the stainless steel substrate. Surface microstructural morphologies of the stainless steel bipolar plates modified with multi-layered coatings were observed by AFM and FE-SEM images. The stainless steel plates modified with 0.1 ㎛ titanium film and 1 ㎛ gold film showed microstructure of grains of under 100 ㎚ diameter. The external surface of the stainless steel plates deposited with 0.1 ㎛ titanium film and 2 ㎛ gold film represented somewhat grain growth of Au grains in FE-SEM image. The electrical resistance and water contact angle of the stainless steel bipolar plates modified with multi-layered coatings were examined with the thickness of the gold film.

Self‐bank metal conductor fabricated with silver nanoparticles

Abstract— A novel self‐bank method for fabricating a thin‐film metal conductor was studied by drying silver‐nanoparticle dispersion droplets. The bank of the thin‐film metal conductor was created spontaneously utilizing the self‐bank method. A uniform film of polymethyl methacrylate (PMMA) used as a barrier layer was formed on a glass substrate. Silver nanoparticles were dispersed in a suitable solvent for which PMMA is soluable and a silver nanoparticle fluid suspension was formed. When the silver‐nanoparticle fluid suspension was injected into the PMMA film of the substrate, the solvent dissolved the PMMA film, creating a restricted area for silver nanoparticle material defining the bank of the conductive area which improves the uniformity and conductivity of metal film. The metal conductor with a self‐defined bank is formed when the PMMA film was removed after sintering. This self‐bank method would be helpful in improving the deposition process of the functional materials in the fabrication of organic light‐emitting diodes, organic thin‐film transistors, color filters, metal electrodes, and biosensors.

Corrosion dynamics of electric conductivity of metal films in ice under its structural and phase transformations

The corrosion-induced decrease in the electric conductivity of metal films in ice under its thermally induced structural relaxation and at the water crystallization front have been investigated. Mathematical models of corrosion enhancement are proposed that are based on the suggestion about overcoming the reaction barrier as a result of the release of recombination energy of orientational defects during structural and phase transformations of ice.

Coated fused silica fibers for enhanced sensitivity torsion pendulum for LISA

In order to investigate the fundamental thermal noise limit of a torsion pendulum using a fused silica fiber, we systematically measured and modeled the mechanical losses of thin fused silica fibers coated by electrically conductive thin metal films. Our results indicate that it is possible to achieve a thermal noise limit for coated silica a factor of 9 lower than obtained with the tungsten fiber used in the recent LISA torsion pendulum study [L. Carbone, et al., Phys. Rev. Lett. 91 (2003) 151101]. This will allow a corresponding increase in sensitivity of torsion pendula used for small force measurements.

Effective medium description of plasmonic metamaterials

We demonstrate that the electromagnetic properties of a plasmonic metamaterial, composed of a perfectly conducting metal film perforated with an array of holes, can be effectively described by a structureless, three layer film. The enhanced transmission, first observed by Ebbessen, is identified with resonant tunneling in the equivalent three layer system and perfect transmission is shown to be possible below the critical thickness of a metamaterial. The nature of modes mediating perfect transmission is clarified.

Controlled insulator-to-metal transformation in printable polymer composites with nanometal clusters

Although organic semiconductors have received the most attention, the development of compatible passive elements, such as interconnects and electrodes, is also central to plastic electronics. For this, ligand-protected metal-cluster films have been shown to anneal at low temperatures below 250 degrees C to highly conductive metal films, but they suffer from cracking and inadequate substrate adhesion. Here, we report printable metal-cluster-polymer nanocomposites that anneal to a controlled-percolation nanostructure without complete sintering of the metal clusters. This overcomes the previous challenges while still retaining the desired low transformation temperatures. Highly water- and alcohol-soluble gold clusters (75 mg ml-1) were synthesized and homogeneously dispersed into poly(3,4-ethylenedioxythiophene) to give a material with annealed d.c. conductivity tuneable between 10(-4) and 10(5) S cm-1. These composites can inject holes efficiently into all-printed polymer organic transistors. The insulator-metal transformation can also be electrically induced at 1 MV cm-1, suggesting possible memory applications.

Fabrication of Thin, Metallic Films along the Sidewalls of a Topographically Patterned Stamp and Their Application in Charge Printing

Thin, electrically conductive metallic films have been generated on the sidewalls of relief patterns on a poly(dimethylsiloxane) stamp using a combination of thin-film metal deposition and nanotransfer printing (see image). These conductive metal films generate patterns of charge in thin films of dielectrics using electrical microcontact printing. Sub-micrometer particles of polystyrene and iron oxide adhere specifically to the regions of charge.

Coating a thin metal electrode on a fiber to induce nonlinearity by poling it

A fabrication technique to coat a conductive metal film on the direct surface of a fiber, which is readily extendable to volume manufacturing, is demonstrated. A D-shaped fiber was used to produce second harmonic generation (SHG) that proves nonlinearity of a poled-fiber. The metal film coated on a single mode fiber provided a key technology to achieve an all-fiber nonlinear system. A pump pulse system which generates the high peak-power ns-pulse using an all-fiber system is also demonstrated.

Electrical transport in metallic films

On the basis of the Boltzmann equation, the authors propose a model that includes scattering from both film surfaces and grain boundaries, and have studied the quasiclassical electrical transport in metallic films. The in-plane electric conductivity of metallic films is obtained, and the theoretical results are shown to be in good agreement with experimental data. We also give the relation between temperature coefficient of resistivity and thickness of metallic films and make a comparison with experiment.

Low-temperature synthesis of large-area CNx nanotube arrays.

Well-aligned nitrogen-doped multiwall carbon nanotube arrays have been successfully grown over large areas on quartz and silicon wafers by floating-catalyst chemical vapor deposition at low temperatures (600 degrees C). These nitrogen-including nanotubes, derived from pyridine-ferrocene mixtures, have smaller outer diameters but larger inner diameters compared with carbon nanotubes grown from a xylene-ferrocene mixture under similar conditions. The N-doped nanotubes exhibit bamboo-like structures in the core. Elemental analysis and electron energy loss spectroscopy analysis show that the as-prepared nanotubes contain as much as 2.62 wt.% N, with most of the N concentrated in the inner few shells of the nanotube. Such large-scale arrays of well-aligned N-doped nanotubes on silicon wafers have a current density as high as 23.8 mA/cm2 at an applied electric field of 17 V/micron, which can be further improved by patterning the tubes and coating the silicon substrate with a conductive thin metal film for the fabrication of flat panel displays.

Pulsed-laser-deposited epitaxial Sr2FeMoO6−y thin films: Positive and negative magnetoresistance regimes

Epitaxial thin films of ordered double-perovskite Sr2FeMoO6−y are deposited on (001) SrTiO3 substrates by pulsed-laser deposition using a two step growth process. Selection of growth conditions is found to lead to either highly conductive metallic thin films (residual resistivity of about 1 μΩ cm) or semiconducting films. The metallic films show a positive magnetoresistance (MR) as high as 35%, while the semiconducting films show a negative MR of −3%, at a temperature of 5 K and a field of 8 T.

Introduction to manufacturing processes

Using the Boltzmann approach we have developed one dimensional (1D) model of metal films conductivity for the quantum electron transport. Thickness fluctuation of film has an effect on the electron spectra via carriers scattering in quantum size regime. In the framework of the developed model size dependent conductivity of metal films has been calculated. Here, we employed above mentioned model to explain experimental data on single crystalline CoSi2 films and fine-grained gold films. Wide film thickness ranges applicable by the described model cover also the crossover from quantum to quasiclassical electron transport.