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Communication: Gold is an excellent contact, connect, and wiring material for microelectronic devices, while silver is of interest for optics, superconducting, and magnetic applications. However, the usual precursors for these materials are difficult to synthesize and handle. This work reports on a new group of precursors based on complexes of AuI and AgI with tertiary phosphines and perfluorinated carboxylates. It is shown that the quality of the films obtained depends on the length of the perfluorinated chain as well as the deposition temperature - AuI and AgI Complexes with Tertiary Phosphines and Perfluorinated Carboxylates as Precursors for CVD of Gold and Silver
Full Paper: Oxygen in titanium nitride gives a range of materials with interesting new properties. Layer characteristics, including surface morphology, of oxynitride films deposited by low-pressure CVD have been investigated as a function of deposition temperature. Three different regions are observed (see Figure) with a transition from semiconducting behavior to metallic conductivity at high temperatures - Correlation Between the Electrical Properties and the Morphology of Low-Pressure MOCVD Titanium Oxynitride Thin Films Grown at Various Temperatures
Full Paper: Titanium nitride thin films have applications for ultra large scale integration (ULSI) metallization and as protective mechanical coatings. These applications require a range of TiN thicknesses. The effect of one deposition step (ODS) or multiple deposition steps (MDS) on growth rate and resistivity has been studied. For ODS they are both quite low initially, but after a critical point they increase dramatically. For MDS no critical point is observed. Thus it is concluded that MDS would be preferred for ULSI, but for coatings ODS could be better - Optimization of Titanium Nitride Rapid Thermal CVD Process
Full Paper: Dye-sensitized photovoltaic solar cells have given new incentives to the study of wide bandgap semiconductors. Pyrite may be a good candidate as a sensitizer for TiO2 as it shows strong optical absorption and has a suitable band structure. Here the complex kinetics of low-pressure MOCVD of FeS2 are investigated. The Figure shows the influence of gas flow rate on the film thickness profile - Synthesis of Pyrite (FeS2) Thin Films by Low-Pressure MOCVD
Full Paper: Precursors for CVD processes need to be volatile, usually monomeric, and easy to handle. Satisfying these requirements provides a significant challenge to the synthetic chemist. Previously explored ligand platforms range from b-diketonates to amides. The marrying of the two ligand motifs produces the b-ketoiminate hybrid. Here are described the synthesis, structural characterization, and preliminary CVD results of the first homoleptic magnesium b-ketoiminate (see also cover) - CVD of MgO from a Mg(b-ketoiminate)2: Preparation, Characterization, and Utilization of an Intramolecularly Stabilized, Highly Volatile, Thermally Robust Precursor
Full Paper: A new approach to CVD of oxides is presented. This technique of volatile surfactant-assisted (VSA) deposition is achieved by carrying out film formation in the presence of a volatile, low melting point oxide, Bi2O3. A marked improvement in crystalline quality and surface morphology is found for VSA-deposited LaAlO3 films. The high perfection of a VSA film is shown in the Figure - Volatile Surfactant-Assisted MOCVD: Application to LaAlO3 Thin-Film Growth
Full Paper: Thin films in the Bi-Ti-O system have been deposited for the first time by atomic layer CVD (ALCVD). This ternary system contains several bismuth titanates with a range of properties, but although a variety of methods have been used for film growth ALCVD with its intrinsic advantage of self-limiting adsorption and resulting enhancement of lateral uniformity and 2D growth has not previously been studied. The influence of precursor pulsing ratio and deposition temperature on layer characteristics has been investigated - Atomic Layer CVD in the Bi-Ti-O System
Communication: Ordered nanoporous films have been generated via selective degradation of self-assembled block copolymer films of polystyrene (PS) and poly(methyl-methacrylate) (PMMA), which contain oriented cylindrical microdomains. Deep UV irradiation degrades the PMMA, which can be rinsed away, leaving an ordered array of circular holes in a film of cross-linked PS (see Figure) - Nanoscopic Templates from Oriented Block Copolymer Films
Communication: The effect of illumination on the agglomeration of surface-modified gold nanoparticles both in solution and on gold (111) surfaces is investigated here. It is shown that illumination induces additional interparticle interactions, which can be controlled by changing the illumination wavelength. The Figure shows linear arrays of gold nanoparticles formed on a gold surface upon illumination at 830 nm - Formation of Linearly Arrayed Gold Nanoparticles on Gold Single-Crystal Surfaces
Communication: Rapid construction of nanoarchitectures of high dimension and complexity is what these authors aim to achieve using core-shell tecto-(dendrimers). Self-assembly of the core-dendrimer tectons followed by amide bond formation to attach the shell-dendrimer tectons (see Figure) allows the construction of dendrimers so large and generationally advanced that they can be treated as spheroids - Core-Shell Tecto(dendrimers): I. Synthesis and Characterization of Saturated Shell Models
Communication: The efficiency of polymer light-emitting diodes (LEDs) is highly dependent on the heat treatment conditions and procedures. With the aim of enhancing the luminescence efficiency of polymer LEDs, the effect of thermal annealing at temperatures above the Tg of the emissive polymer in a ITO-polymer-Al device is investigated. Four different cases are considered: An unannealed device, a pre- (aluminum) deposition annealed device, a post-deposition annealed device, and a post-deposition annealed device after pre-deposition annealing - The Effect of Different Heat Treatments on the Luminescence Efficiency of Polymer Light-Emitting Diodes
Communication: Chemically defined surface patterning has been achieved via irradiation with low-energy electrons. Irradiation of nitro-arene-thiol monolayers leads to the reduction of the nitro groups to amino groups, which can then be further chemically modified. The Figure shows-such a monolayer that was irradiated through a copper grid followed by acylation with trifluoroacetic acid anhydride - Generation of Surface Amino Groups on Aromatic Self-Assembled Monolayers by Low Energy Electron Beams -- A First Step Towards Chemical Lithography
Communication: Submicrometer hollow spheres of CdS are produced here (see Figure) in a one-pot in-situ source-template-interface reaction (ISTIR) -- Thus named because CS2 plays both the role of sulfur source and template and the main reaction region is at the CS2-water interface. Examination of the photoluminescence spectrum of these spheres indicates quantum confinement - In-Situ Source-Template-Interface Reaction Route to Semiconductor CdS Submicrometer Hollow Spheres
Communication: Photonic crystals fabricated from a diblock copolymer-homopolymer blend are reported. It is shown that large-area, highly reflective, flexible films can be obtained in which the peak reflective wavelength can be tuned simply by altering the percentage of homopolymer in the blend. A fracture surface of a 40 % homopolymer blend is shown in the Figure - Tunable Block Copolymer-Homopolymer Photonic Crystals
Communication: Inorganic nano- and microtubes intercalated with silver and gold are reported here for the first time. These alloyed phases of MoS2 and WS2 are stabilized by the tubular structure -- Remaining unknown in the bulk material. Analysis with TEM shows that the Au intercalated tubes (the Figure shows the termination of an Au-WS2 tube) show a concentric growth with a conical tip - Structural Stabilization of New Compounds: MoS2 and WS2 Micro- and Nanotubes Alloyed with Gold and Silver
Communication: The solution synthesis of Mg(OH)2 nanorods is discussed with emphasis on the influence of experimental conditions on the morphology of the products. A templating mechanism is suggested for the formation of the nanorods that involves solvent molecules (ethylenediamine) acting as bidentate ligands to form a complex (see Figure). The 1D Mg(OH)2 nano-rod structure can then condense out - Preparation of Mg(OH)2 Nanorods
Communication: Liquid-crystal polymer brushes are a special class of soft alignment layers for liquid-crystal displays, which are designed to transfer orientation from the surface to the bulk. The brushes (see Figure) are grown from a substrate covered with a monolayer of initiator, and it is shown here that rubbing the surface with a velvet cloth before growth of the brush produces nematic orientation in the resulting brushes - Homogeneously Aligned Liquid-Crystal Polymer Brushes
Communication: Light-emitting polymer electrochemical cells (LECs) emit brighter light at lower voltages in comparison to conventional LEDs. The fundamental mode of operation of LECs is investigated here: The internal electrical field distribution was determined for LECs based on methyl-substituted ladder-type poly(p-phenylene) (mLPPP) using electroabsorption measurements as a function of an external bias voltage. These results were compared to measurements on mLPPP LEDs, and a model for the working principle of both types of devices is presented, showing that electrochemical doping is important in LECs - Comparison of the Internal Field Distribution in Light-Emitting Diodes and Light-Emitting Electrochemical Cells
Communication: Novel spiro-functionalized polyfluorene derivatives (see Figure) are synthesized here. The absorbance and photoluminescence properties of these compounds are investigated and pure blue electroluminescence is demonstrated in single-layered and double-layered devices. Spiro-functionalization is concluded to be a promising approach to addressing the issues of color impurity and poor spectral stability of polyfluorenes - Spiro-Functionalized Polyfluorene Derivatives as Blue Light-Emitting Materials
Research News: Macroporous metals with strong diffractive properties at visible wavelengths can be synthesized from colloidal crystal templates. The synthesis, characterization, and potential applications of macroporous metals created in this manner are summarized in this article. The Figure shows a macroporous copper film, illustrating the long-range order of the porous structure (see also cover) - Porous Metals from Colloidal Templates
Research News: Huge length silica nanotubes (see Figure) can be synthesized using a surfactant-mediated sol-gel method. In this article, the method and mechanism of nanotube formation are discussed and the strategy for controlling the geometry of the tubes is illustrated. The procedure described may be applicable to the fabrication of nanotubes composed of other inorganic species, e.g., titania - Surfactant-Mediated Fabrication of Silica Nanotubes
Research News: Drug carriers, antimicrobial agents, and biocides are three of the versatile applications of dendrimers that arise due to their unique architecture. The central cavity can encapsulate a hydrophobic drug while transporting it through an aqueous system, while the high concentration of endgroups allows multiple simultaneous interactions -- The polycationic nature of the biocide in the Figure is 200 times more effective against E. coli than its mono-functional analogues - Recent Advances in Antimicrobial Dendrimers