Showing papers on "Layer by layer published in 2003"

LnCuO(S,Se,Te)monocrystalline thin film, its manufacturing method, and optical device or electronic device using the monocrystalline thin film

Abstract: Disclosed is a method of producing an LnCuOX single-crystal thin film (wherein Ln is at least one selected from the group consisting of lanthanide elements and yttrium, and X is at least one selected from the group consisting of S, Se and Te), which comprises the steps of growing a base thin film on a single-crystal substrate, depositing an amorphous or polycrystalline LnCuOX thin film on the base thin film to form a laminated film, and then annealing the laminated film at a high temperature of 500° C. or more. While a conventional LnCuOX film produced by growing an amorphous film through a sputtering process under appropriate conditions and then annealing the film at a high temperature was unexceptionally a polycrystalline substance incapable of achieving high emission efficiency and electron mobility required for a material of light-emitting devices or electronic devices, the method of the present invention can grow a thin film with excellent crystallinity suitable as a single crystal to an building black of light-emitting diodes, semiconductor leasers, filed-effect transistors, or a hetero-bipolar transistors.

Biomedical applications of electrostatic layer-by-layer nano-assembly of polymers, enzymes, and nanoparticles

Abstract: The introduction of electrostatic layer-by-layer (LbL) self-assembly has shown broad biomedical applications in thin film coating, micropatterning, nanobioreactors, artificial cells, and drug delivery systems. Multiple assembly polyelectrolytes and proteins are based on electrostatic interaction between oppositely charged layers. The film architecture is precisely designed and can be controlled to 1-nm precision with a range from 5 to 1000 nm. Thin films can be deposited on any surface including many widely used biomaterials. Microencapsulation of micro/nanotemplates with multilayers enabled cell surface modification, controlled drug release, hollow shell formation, and nanobioreactors. Both in vitro and in vivo studies indicate potential applications in biology, pharmaceutics, medicine, and other biomedical areas.

High-contrast electrochromism from layer-by-layer polymer films

Abstract: Layer-by-layer (LBL) assembly is the ideal processing technique to combine two electrochromic polymers into a single thin film composite with fine control over morphology and composition. Here we present a very-high-contrast electrochromic composite developed from the LBL assembly of two readily available cathodically coloring electrochromic polymers: poly(hexyl viologen) (PXV) and the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:SPS) colloid. Characterization of assembly reveals that film thickness increases exponentially with increasing layer-pair number, seemingly due to the globular nature of the PEDOT:SPS colloid. Elemental analysis confirmed the presence of both polymers in the final film and allowed the determination of a bulk composition profile. In detailed electrochemical and spectral investigations, the “dual electrochrome” was compared to single-electrochrome LBL films, confirming that both polymers contribute to electrochromic switching. Due to the unusual film architectur...

Layer-by-Layer Deposition of Thermoresponsive Microgel Thin Films

Abstract: We report investigations of the assembly of thermoresponsive, 4-acrylamidofluorescein-modified (indicated by an asterisk) poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc*) microgel thin films via a traditional alternate layer deposition protocol. In this work, pNIPAm-co-AAc* microgels have been synthesized and incorporated into thin films by alternatively exposing glass slides functionalized with 3-aminopropyltrimethoxysilane to pNIPAm-co-AAc* microgels, which act as polyanions, and poly(allylamine hydrochloride), which acts as a polycation. Using this method, pNIPAm-co-AAc* microgel thin films have been constructed as confirmed by fluorescence microscopy. Investigations were also conducted on the effect of the microgel deposition temperature on the film morphology and thermoresponsivity. In addition, the thermoresponsivities of the pNIPAm-co-AAc* microgel thin films were studied with respect to the microgel layer number, microgel deposition conditions, and pH. As expected from the solution beh...

Method of forming a thin film in a semiconductor device

Abstract: The present invention relates to a method of forming a thin film in a semiconductor device. According the method, the thin film is formed by alternately repeating an atomic layer deposition (ALD) method and a plasma enhanced atomic layer deposition (PEALD) method and further by adjusting the ratio of repetition times of the methods, so that it is possible to adjust and estimate the growth rate, density, and material properties such as refraction index, dielectric constant, electric resistance, etc.

Nanotubes Prepared by Layer‐by‐Layer Coating of Porous Membrane Templates

Abstract: Polyelectrolyte (PE) (see Figure) and PE-nanoparticle hybrid nanotubes are prepared by the layer-by-layer deposition of oppositely charged species into the cylindrical pores of polycarbonate membrane templates (see also cover). This method affords the preparation of compositionally complex tubes with nanometer-level controllable tube wall thicknesses and enhanced structural stabilities.

Langmuir-Blodgett Films of Single-Wall Carbon Nanotubes: Layer-by-layer Deposition and In-plane Orientation of Tubes

Abstract: The Langmuir–Blodgett technique has been applied to build optically homogeneous thin films of chemically solubilized single-wall carbon nanotubes (s-SWNTs) which possess good surface spreading properties at the air/water interface. Deposition can be performed in a layer-by-layer fashion up to 100 or more layers either by horizontal lifting or vertical dipping, allowing to readily control the film thickness. Their visible to near-infrared absorption spectra showing the characteristic features of semiconducting and metallic SWNTs prove the intactness of their one-dimensional electronic states during the preparation process. Polarized absorption spectroscopy and atomic force microscope (AFM) observation demonstrate that the tubes are oriented in the direction of the trough barrier (horizontal lifting) or in the dipping direction (vertical dipping). These are attributed to compression-induced or flow-induced orientation, respectively, the latter found to be much stronger than the former. The realization of homogeneous thin films of SWNTs with a controllable thickness and tube orientation should be an important basis for the future development of their scientific understanding and technological applications.

Hybrid thin film/thick film solid oxide fuel cell and method of manufacturing the same

Abstract: A SOFC providing higher power densities than PEM-based cells; the possibility of direct oxidation and/or internal reforming of fuel; and reduced SOFC operating temperatures. The SOFC comprises a thin film electrolyte layer. A thick film anode layer is disposed on one surface of the electrolyte layer; and a thick film cathode layer is disposed on the opposite surface of the electrolyte layer. A method of making the SOFC comprises the steps of: creating a well in one side of a dielectric or semiconductor substrate; depositing a thin film solid oxide electrolyte layer on the surface of the well; applying a thick film electrode layer in the electrolyte coated well; creating a counter well in the opposite side of the substrate, the counter well abutting the electrolyte layer; and applying a thick film counter electrode layer in the counter well.

Insulating layers in semiconductor devices having a multi-layer nanolaminate structure of SiNx thin film and BN thin film and methods for forming the same

Abstract: The present invention discloses a novel insulating layer for use in semiconductor devices, the insulating layer having a multi-layer nanolaminate structure consisting of alternating boron nitride thin films and silicon nitride thin films, each of a controlled, desired thickness, together with methods for forming the same The insulating layer of the present invention has a multi-layer nanolaminate structure consisting of alternating boron nitride thin films and silicon nitride thin filmsformed by the steps of: (a) depositing a silicon nitride thin film on a wafer, (b) depositing a boron nitride thin film on the silicon nitride thin film, and (c) forming the multi-layer nanolaminate thin film by alternately repeating steps (a) and (b)

Fast Ion Conduction in Layer-By-Layer Polymer Films

Abstract: The layer-by-layer (LBL) deposition technique has been applied to the design of polymer electrolyte films appropriate for electrochemical applications such as sensors and electrochromic cells. In this work, we describe the properties of three LBL polymer electrolyte systems assembled from cationic layers of linear poly(ethylene imine) (LPEI), with anionic layers of Nafion, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS), and poly(acrylic acid) (PAA). The assembly behavior of these systems was carefully examined, and ionic conductivity was determined using impedance spectroscopy. The influences of assembly conditions and water plasticization on ion conduction were elaborated. Room-temperature ionic conductivity greater than 10-5 S/cm can be achieved within LPEI/PAMPS and LPEI/PAA films, which is 2 orders of magnitude greater than the highest values previously described in LBL films. By manipulating a unique assembly mechanism, high ionic conductivity can be achieved in LPEI/PAMPS films at low pl...

Solid‐State Photovoltaic Thin Films using TiO2, Organic Dyes, and Layer‐by‐Layer Polyelectrolyte Nanocomposites

Abstract: We report photovoltaic devices consisting of patterned TiO2, porphyrin dyes, and layer-by-layer (LBL) polyelectrolyte multilayer/oligoethylene glycol dicarboxylic acid (OEGDA) composite films. A composite polyelectrolyte LBL/OEGDA film was fabricated by formation of an alternating multilayer of linear polyethyleneimine (LPEI) and polyacrylic acid (PAA), followed by immersion of the LBL film into an OEGDA aqueous solution. The ionic conductivity attained in this LBL LPEI/PAA and OEGDA composite film was approximately 10–5 S cm–1 at room temperature and humidity. Investigations of dye-sensitized photovoltaic devices constructed with the LBL (LPEI/PAA)/OEGDA composite films, TiO2, and four types of porphyrin dyes resulted in optimization of the dye molecule and its orientation at the interface with the ionically conductive composite. The photocurrent value of photovoltaic devices constructed with the composite LBL/OEGDA film from illumination of a xenon white light source exhibited a nearly 1.5 times enhancement over the device without OEGDA. This enhancement of the photocurrent was due to the high room-temperature ionic conductivity of the multilayer composite film. Further marked improvements of the photovoltaic performance were achieved by patterning the TiO2 electrode using polymer stamping as a template for TiO2 deposition. The device with patterned TiO2 electrodes exhibited almost 10 times larger conversion efficiencies than a similar device without patterning.

Layer-by-layer self-assembled chitosan/poly(thiophene-3-acetic acid) and organophosphorus hydrolase multilayers.

Abstract: The aim of this study is to immobilize an enzyme, namely, organophosphorus hydrolase (OPH), and to detect the presence of paraoxon, which is an organophosphorus compound, using the layer-by-layer (LbL) deposition technique. To lift the OPH from the solid substrate, a pair of polyelectrolytes (positively charged chitosan (CS) and negatively charged poly(thiophene-3-acetic acid) (PTAA)) were combined. These species were made charged by altering the pH of the solutions. LbL involved alternate adsorption of the oppositely charged polyions from dilute aqueous solutions onto a hydrophilic quartz slide. This polyion cushion was held together by the electrostatic attraction between CS and PTAA. The growing process was monitored by fluorescence spectroscopy. OPH was then adsorbed onto the five-bilayer CS/PTAA system. This five-bilayer macromolecular structure compared to the solid substrate rendered stability to the enzyme by giving functional integrity in addition to the ability to react with paraoxon solutions. The ultimate goal is to use such a system to detect the presence of organophosphorus compounds with speed and sensitivity using the absorption and fluorescence detection methodologies.

Layer-by-layer biosensor assembly incorporating functionalized quantum dots

Abstract: Layer-by-layer (LbL) assembly has been utilized to fabricate an ultrathin film of polyelectrolytes. The architecture was composed of chitosan and organophosphorus hydrolase polycations along with thioglycolic acid-capped CdSe quantum dots (QDs) as the polyanion. The topography of the films was studied using epifluorescence microscopy imaging. The photoluminescence property of the functionalized QDs improved when sandwiched between the polycation layers. The enhanced optical property of QDs allowed easy monitoring of LbL growth and detection of paraoxon with high sensitivity. The presence of organophosphorus compounds was confirmed through UV−vis and emission spectroscopies.

Ambipolar Organic Thin Film Transistor-like Behavior of Cationic and Anionic Phthalocyanines Fabricated Using Layer-by-Layer Deposition from Aqueous Solution

Abstract: Organic thin film field effect transistors of water-soluble cationic and anionic phthalocyanine derivatives were successfully prepared using the layer-by-layer deposition technique. The alternating film growth and subsequent transistor properties were studied with a variety of techniques including ellipsometry, UV−vis spectroscopy, polarized UV−vis spectroscopy, AFM, and field effect transistor measurements. A stepwise and regular deposition of copper(II) phthalocyanine tetrakis(methyl pyridinium) chloride and copper(II) phthalocyanine tetrasulfonic acid, tetrasodium salt multilayers in both pure water and 0.03 M NaCl solution was observed. Differences in linear growth were observed between pure water and 0.03 M NaCl-based solutions. Polarized UV−vis spectra indicated that the conjugated phthalocyanine ring lies almost flat on the substrate surface with a random orientation within the plane of the substrate. Unusual “ambipolar” transistor-like behavior was found for the films that can be attributed to an ...

Dye-sensitized solar cell fabricated by electrostatic layer-by-layer assembly of amphoteric TiO2 nanoparticles

Abstract: Nanocrystalline TiO2 amphoteric colloidal charged particles and polyelectrolytes have been used to fabricate a dye-sensitized solar cell. Two weak polyelectrolytes, poly(allylamine hydrochloride) and poly(acrylic acid), and two strong polyelectrolytes, poly(dimethyldiallylammonium chloride) (PDAC) and poly(sodium 4-styrenesulfonate), have been utilized to assemble polyion/TiO2 nanocomposite multilayered films by the electrostatic layer-by-layer deposition technique. The layer-by-layer assembly of the TiO2 nanoparticles proceeds linearly as shown by sequential UV−vis absorption and thickness measurements. The morphology of these assemblies was characterized using atomic force microscopy. The nanoporous polyion/TiO2 films were sintered and used as working electrodes for cis-di(thiocyanato)-N,N-bis(2,2‘-bipyridyldicarboxylate)-ruthenium(II) (N3) sensitized solar cells. I−V characteristics of the solar cells made by the calcinated polyelectrolyte/TiO2 electrodes show several interesting results. (i) The short...

Hydrogen-Bonding-Directed Layer-by-Layer Assembly of Dendrimer and Poly(4-vinylpyridine) and Micropore Formation by Post-Base Treatment

Abstract: We reported a way to fabricate microporous films by post-base treatment of hydrogen-bonding-directed multilayer films of poly(4-vinylpyridine) (PVP) and carboxyl-terminated polyether dendrimer (DEN−COOH). The PVP/DEN−COOH multilayer film was fabricated by layer-by-layer assembly of PVP and DEN−COOH from a methanol solution. UV−visible spectroscopy revealed a uniform deposition process. The interaction between PVP and DEN−COOH was identified as hydrogen bonding through Fourier transform infrared (FT-IR) spectroscopy. Meanwhile, the composition change of a PVP/DEN−COOH multilayer film in a basic solution was detected by X-ray photoelectron spectroscopy and UV−visible spectroscopy, and the morphology variation was observed by atomic force microscopy. A two-step variation was observed: the dissolution of DEN−COOH from the multilayer into the basic solution and the gradual reconformation of PVP polymer chains remaining on the substrate, which produced a microporous film. Interestingly, compared with our previ...

Electrochemical catalysis with redox polymer and polyion-protein films.

Abstract: Supramolecular redox-active assemblies on electrodes are of fundamental interest and can be used to create functioning devices such as sensors, biosensors, and bioreactors. The ability of redox-active films to mediate electron transfer reactions in 3-D dramatically increases the sensitivity with which target molecules can be determined. Metallopolyion hydrogel films immobilized on electrode surfaces exhibit many properties that are reminiscent of those shown by redox-active proteins. This review discusses the electrochemical properties and applications of such films, including mediating electron transfer between electrodes and oxidase enzymes. In addition, polyion-protein films grown layer by layer have certain advantages in device fabrication, including facilitating direct electron transfer for many proteins, mechanical stability, use of tiny amounts of protein, and control of film architecture. This review presents examples of iron heme proteins in films grown layer by layer by alternate electrostatic adsorption for catalytic reduction of hydrogen peroxide and trichloroacetic acid and for oxidation of styrene.

Fabrication of a Metalloporphyrin−Polyoxometalate Hybrid Film by a Layer-by-Layer Method and Its Catalysis for Hydrogen Evolution and Dioxygen Reduction

Abstract: [Tetrakis (N-methylpyridyl) porphyrinato] cobalt (CoTMPyP) and 1:12 silicotungstic acid (SiW12) were alternately deposited on a 4-aminobenzoic acid (4-ABA) -modified glassy carbon electrode through a layer-by-layer method. The resulting organic−inorganic hybrid films were characterized by cyclic voltammetry (CV) and UV/vis absorption spectroscopy. We proved that the prepared multilayer films are uniform and stable. SiW12-containing multilayer films (SiW12 as the outermost layer) exhibit remarkable electrocatalytic activity for the hydrogen evolution reaction (HER). The kinetic constants for HER were comparatively investigated at different layers of SiW12/CoTMPyP multilayer film-modified electrodes by hydrogen evolution voltammetry. In addition, rotating disk electrode (RDE) and rotating ring−disk electrode (RRDE) voltammetric methods confirm that SiW12/CoTMPyP (CoTMPyP as the outermost layer) multilayer films catalyze almost a two-electron reduction of O2 to H2O2 in pH 1−6 buffer solutions. Furthermore, P...

Layer-by-Layer Films of Chitosan, Organophosphorus Hydrolase and Thioglycolic Acid-Capped CdSe Quantum Dots for the Detection of Paraoxon

Abstract: A polyelectrolyte architecture was fabricated that was composed of chitosan and organophosphorus hydrolase polycations along with thioglycolic acid-capped CdSe quantum dots (QDs) as the polyanion. This film was imaged by epifluorescence microscopy. UV−vis and emission spectroscopies were used to monitor the growth of the bilayer film due to the enhanced optical property of QDs. Photoluminescence of the functionalized QDs improved when sandwiched between the polycations layers. The presence of organophosphorus compounds was confirmed through photoluminescence spectroscopy.

Layer-by-layer growth of metal-metal bonded supramolecular thin films and its use in the fabrication of lateral nanoscale devices.

Abstract: Layer-by-layer self-assembly of metal-metal bonded supramolecules is demonstrated and utilized to fabricate lateral nanoelectronic devices. Mercaptoethylpyridine is used to bind to Au substrates and to template the sequential assembly of alternating layers of redox active dirhodium complexes [Rh2(DAniF)2]2(O2CCH2CO2)2 (DAniF = N,N'-di-p-anisylformamidinate) and conjugated organic ligands trans-1,2-bis(4-pyridyl)ethylene. Optical spectroscopy and atomic force microscopy show that the structure and composition of these thin films are similar to those found in tightly packed single crystals. Electrochemical studies of these films grown on Au substrates reveal a reversible oxidation wave at approximately 406 mV, corresponding to the one electron oxidation of the Rh24+ center. This directed assembly technique has been used to fabricate lateral nano-electronic devices in which the supramolecules span the channels. Tailoring the chemistry of the templating ligand enables assembly on desired surfaces and engineering the chemistry of the supramolecules' dimetal units and coordinating ligands may tune the device characteristics.