Preparation of zinc oxide coatings by using newly designed metal-organic complexes of Zn: Effect of molecular structure of the precursor and surfactant over the crystallization, growth and luminescence

We report large scale deposition of tapered zinc oxide (ZnO) nanorods on Si(100) substrate by using newly designed metal-organic complex of zinc (Zn) as the precursor, and microwave irradiation assisted chemical synthesis as a process. The coatings are uniform and high density ZnO nanorods (similar to 1.5 mu m length) grow over the entire area (625 mm(2)) of the substrate within 1-5 min of microwave irradiation. ZnO coatings obtained by solution phase deposition yield strong UV emission. Variation of the molecular structure/molecular weight of the precursors and surfactants influence the crystallinity, morphology, and optical properties of ZnO coatings. The precursors in addition with the surfactant and the solvent are widely used to obtain desired coating on any substrate. The growth mechanism and the schematics of the growth process of ZnO coatings on Si(100) are discussed. (c) 2013 Elsevier B.V. All rights reserved.

Negative differential resistance and effect of defects and deformations in MoS2 armchair nanoribbon metal-oxide-semiconductor field effect transistor

In this work, we present a study on the negative differential resistance (NDR) behavior and the impact of various deformations (like ripple, twist, wrap) and defects like vacancies and edge roughness on the electronic properties of short-channel MoS2 armchair nanoribbon MOSFETs. The effect of deformation (3 degrees-7 degrees twist or wrap and 0.3-0.7 angstrom ripple amplitude) and defects on a 10 nm MoS2 ANR FET is evaluated by the density functional tight binding theory and the non-equilibrium Green's function approach. We study the channel density of states, transmission spectra, and the I-D-V-D characteristics of such devices under the varying conditions, with focus on the NDR behavior. Our results show significant change in the NDR peak to valley ratio and the NDR window with such minor intrinsic deformations, especially with the ripple. (C) 2013 AIP Publishing LLC.

Gas sensing response analysis of p-type porous chromium oxide thin films

The ethanol sensing properties of porous Cr2O3 thin films deposited by the ultrasonic nebulized spray pyrolysis of an aqueous combustion mixture is reported. The impact of the precursor selection and various deposition parameters on the film crystallinity, surface morphology and stoichiometry are studied using thermo-gravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy techniques. The film morphology exhibits a highly porous nature, as a result of the exothermic combustion reaction during film deposition. The gas sensing properties of these films are investigated in the temperature range of 200-375 degrees C for ethanol. The films show two different regions of response for ethanol above and below 300 degrees C. A good relationship between the response and the ethanol concentration is observed, and is modeled using an empirical relation. The possible mechanism and the surface chemical reactions of ethanol over the chromium oxide surface are discussed.

Catalytic Reduction of Graphene Oxide Nanosheets by Glutathione Peroxidase Mimetics Reveals a New Structural Motif in Graphene Oxide

A catalytic reduction of graphene oxide (GO) by glutathione peroxidase (GPx) mimics is reported. This study reveals that GO contains peroxide functionalities, in addition to the epoxy, hydroxyl and carboxylic acid groups that have been identified earlier. It also is shown that GO acts as a peroxide substrate in the GPx-like catalytic activity of organoselenium/tellurium compounds. The reaction of tellurol, generated from the corresponding ditelluride, reduces GO through the glutathione (GSH)-mediated cleavage of the peroxide linkage. The mechanism of GO reduction by the tellurol in the presence of GSH involves the formation of a tellurenic acid and tellurenyl sulfide intermediates. Interestingly, the GPx mimics also catalyze the decarboxylation of the carboxylic acid functionality in GO at ambient conditions. Whereas the selenium/tellurium-mediated catalytic reduction/decarboxylation of GO may find applications in bioremediation processes, this study suggests that the modification of GO by biologically relevant compounds such as redox proteins must be taken into account when using GO for biomedical applications because such modifications can alter the fundamental properties of GO.