Atomic layer chemical vapour deposition of copper

Copper films with (1 1 1) texture are of crucial importance in integrated circuit interconnects. We have deposited strongly (1 1 1)-textured thin films of copper by atomic layer deposition (ALD) using [2,2,6,6-tetramethyl-3,5-heptadionato] Cu(II), Cu(thd)₂, as the precursor. The dependence of the microstructure of the films on ALD conditions, such as the number of ALD cycles and the deposition temperature was studied by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy. Analysis of (1 1 1)-textured films shows the presence of twin planes in the copper grains throughout the films. SEM shows a labyrinthine structure of highly connected, large grains developing as film thickness increases. This leads to low resistivity and suggests high resistance to electromigration.     

Pristine and cadmium-doped zinc oxide: chemical synthesis and characterizations

The chemical synthesis of pristine and cadmium-doped ZnO powders using a simple, cost-effective at 65 °C is reported and characterized for their structures, optical and morphological studies using X-ray diffraction, UV–visible–Near Infra-Red (UV–Vis–NIR) spectroscopy, scanning electron microscopy measurement techniques where XRD spectra confirm the formation of ZnO and Cd-doped ZnO with hexagonal crystal structure. The particle size of ZnO is reduced on Cd-doping from 16 to 14 nm. Plane-view surface morphology analysis supported for spherical-type crystallites and UV–Vis–NIR spectra reveal shift in the band edge of ZnO after Cd-doping. Photo-degradation study of Methylene Blue dye shows Pristine ZnO degrades dye faster than Cd-doped ZnO.     

Friction Stir Surface Processing of Al 6061 Alloy: Role of Surface Alloying with Copper and Heat-Treatment

The current paper focuses on enhancing the surface hardness of the heat-treatable Al-alloy using the combined approach of thermal-spray, friction stir surface processing (FSSP) and heat-treatment. Copper powder was thermal-sprayed in the surface groove of Al 6061 alloy specimens followed by FSSP. Defect-free stirred zone was observed at lower transverse speed of 10 mm/min. The width of the hardness profiles across the stirred zone was increased with increase in the rotational speed of the tool. Grain refining was observed in the stirred zone due to the FSSP. In post-FSSP T6 heat-treatment, aging kinetics in the non-surface-alloyed specimen was accelerated due to the FSSP. Precipitation of Al₂Cu phase was observed in the stirred zone. Copper-alloying and post-FSSP heat-treatment were effective in enhancing the surface hardness (about 39% improvement in the surface hardness was observed).     

Interfacial tension approach toward drug loading with two-dimensional crosslinked polymer embedded gold: Adsorption kinetics evaluation

Interfacial tension of drugs with hydrophilic polymer (A) embedded gold resulting into selective drug adsorption, which also affected the drug adsorption kinetics. Two-dimensional crosslinked polymer embedded gold was synthesized for drug loading application in an acidic buffer. Lower interfacial tension of pantoprazole sodium (B) revealed the exponential loading inversely loading was gradual for chloroquine (C) having more interfacial tension with adsorbent. Initial 2 h was the exponential adsorption period for a pantoprazole sodium whereas exponential adsorption begins after 12 h for a chloroquine. Monolayer drug adsorption was obtained because Langmuir adsorption isotherm was obeyed by both drugs. Moreover, pseudo first- and pseudo second-order kinetics was also evaluated which demonstrated that reactive sites of the adsorbent are homogeneous and drug adsorption mechanism is chemisorption and not the physisorption. Thermal analysis was evaluated to confirm the polymer thermostability and glass transition temperature during catalytic applications in thermal reactions.     

Copolymer resin. VII. 8‐hydroxyquinoline‐5‐sulfonic acid–thiourea–formaldehyde copolymer resins and their ion‐exchange properties

8‐Hydroxyquinoline‐5‐sulfonic acid–thiourea–formaldehyde copolymer resins were synthesized through the condensation of 8‐hydroxyquinoline‐5‐sulfonic acid and thiourea with formaldehyde in the presence of hydrochloric acid as a catalyst and with various molar ratios of the reacting monomers. The resulting copolymers were characterized with UV‐visible, IR and 1H‐NMR spectral data, employed to determine the reactivity of monomers. The average molecular weights of these resins were determined with vapor pressure osmometry and conductometric titration in a nonaqueous medium. The chelation ion‐exchange properties were also studied with the batch equilibrium method. The resins were proved to be selective chelating ion‐exchange copolymers for certain metals. The chelation ion‐exchange properties of these copolymers were studied for Cu²⁺, Ni²⁺, Co²⁺, Pb²⁺, and Fe³⁺ ions. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymers showed a higher selectivity for Fe³⁺ ions than for Cu²⁺, Ni²⁺, Co²⁺, and Pb²⁺ ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Electrochemical studies of n-Cd1−xMnxSe thin film photodetector

Studies on dilute semimagnetic semiconductor thin films are of immense importance. Coupled with their semiconducting properties, they have the characteristic magnetic properties, which make them an attractive alternative in a variety of electronic and optoelectronic devices including gas sensors and solar energy conversion devices. The basic materials are cheap and the actual material can easily be obtained from an aqueous alkaline medium (pH=10.5±0.2) by deposition of Cd²⁺, Mn²⁺ and Se^2– ions. The temperature and time for deposition were optimized as 50 °C and 120 min, respectively. The deposits were adherent to the substrate support, uniform and smooth with color changing from deep orange red to yellowish orange as Mn²⁺ concentration was varied from 0 to 0.5. The electrochemical detector cells were formed out of these series of films as the active photoelectrodes, an electrolyte and a counter electrode and were characterized through their electrical properties. A short circuit current (I _sc) of 147 A/cm² and open circuit voltage (V _oc) 468 mV were noticed at x=0.1 under a steady illumination intensity of 20 mW/cm². The calculated conversion efficiency (%) approached to 0.13% whereas the maximum cell fill factor is 38.45%. These electrochemical detectors exhibited a considerable amount of recombination and series resistance effects.