Preparation of films from aluminum acetylacetonate by plasma sputtering

Aluminum acetylacetonate has been reported as a precursor for the deposition of alumina films using different approaches. In this work, alumina-containing films were prepared by plasma sputtering this compound, spread directly on the powered lowermost electrode of a reactor, while grounding the substrates mounted on the topmost electrode. Radiofrequency power (13.56 MHz) was used to excite the plasma from argon atmosphere at a working pressure of 11 Pa. The effect of the plasma excitation power on the properties of the resulting films was studied. Film thickness and hardness were measured by profilometry and nanoindentation, respectively. The molecular structure and chemical composition of the layers were analyzed by Fourier transform infrared spectroscopy and energy dispersive spectroscopy. Surface micrographs, obtained by scanning electron microscopy, allowed the determination of the sample morphology. Grazing incidence X-ray diffraction was employed to determine the structure of the films. Amorphous organic layers were deposited with thicknesses of up to 7 μm and hardness of around 1.0 GPa. The films were composed by aluminum, carbon, oxygen and hydrogen, their proportions being strongly dependent on the power used to excite the plasma. A uniform surface was obtained for low-power depositions, but particulates and cracks appeared in the high-power prepared materials. The presence of different proportions of aluminum oxide in the coatings is ascribed to the different activations promoted in the metalorganic molecule once in the plasma phase. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.

Mechanical and tribological properties of a-C:H:F Thin Films

a-C:H films were grown by plasma-enhanced chemical vapor deposition in atmospheres composed by 30 % of acetylene and 70 % of argon. Radiofrequency signal (RF) was supplied to the sample holder to generate the depositing plasmas. Deposition time and pressure were chosen 300 s and 9.5 Pa, respectively, while the excitation power changed from 5 to 125 W. The films were exposed to a post-deposition treatment during 300 s in RF-plasmas (13.56 MHz, 70 W) excited from 13.33 Pa of SF6. Raman and X-ray photoelectron spectroscopy were used to evaluate the microstructure and chemical composition of the films. The thickness was measured by perfilometry. Hardness and friction coefficient were determined from nanoindentation and risk tests, respectively. With increasing power, the film thickness reduced, but a further shrinkage occurred upon the fluorination process. After that, the molecular structure was observed to vary with deposition power. Fluorine was detected in all samples replacing H atoms. Consistently with the elevation in the proportion of C atoms with sp3 hybridization, hardness increased from 2 to 18 GPa. Friction coefficient also increased with power due to the generation of dangling bonds during the fluorination process. © 2012 Springer Science+Business Media, LLC.

Eumelanin thin films: Solution-processing, growth, and charge transport properties

Eumelanin pigments show hydration-dependent conductivity, broad-band UV-vis absorption, and chelation of metal ions. Solution-processing of synthetic eumelanins opens new possibilities for the characterization of eumelanin in thin film form and its integration into bioelectronic devices. We investigate the effect of different synthesis routes and processing solvents on the growth, the morphology, and the chemical composition of eumelanin thin films using atomic force microscopy and X-ray photoelectron spectroscopy. We further characterize the films by transient electrical current measurements obtained at 50% to 90% relative humidity, relevant for bioelectronic applications. We show that the use of dimethyl sulfoxide is preferable over ammonia solution as processing solvent, yielding homogeneous films with surface roughnesses below 0.5 nm and a chemical composition in agreement with the eumelanin molecular structure. These eumelanin films grow in a quasi layer-by-layer mode, each layer being composed of nanoaggregates, 1-2 nm high, 10-30 nm large. The transient electrical measurements using a planar two-electrode device suggest that there are two contributions to the current, electronic and ionic, the latter being increasingly dominant at higher hydration, and point to the importance of time-dependent electrical characterization of eumelanin films. This journal is © 2013 The Royal Society of Chemistry.

Estudo da arquitetura molecular de filmes layer-by-layer de ftalocianina tetrasulfonada de cobre

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Investigação da temperatura eletrônica da fase plasma e estudo da morfologia, estrutura molecular e crescimento do polímero proveniente de um plasma de benzeno excitado por tensão contínua

Pós-graduação em Física - FEG

Fabricação e caracterização de filmes finos de perileno: arquitetura molecular e aplicações sensoriais

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Filmes evaporados de ftalocianina de cobalto: arquitetura molecular e aplicação sensorial

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Bending of Layer-by-Layer Films Driven by an External Magnetic Field

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of Different Conditions of Contact for Caprolactam Migration from Multilayer Polyamide Films into Food Simulants

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nanocomposites based on LbL films of polyaniline and sodium montmorillonite clay

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Layer-by-Layer Films Based on Carbon Nanotubes and Polyaniline for Detecting 2-Chlorophenol

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Supramolecular arrangements of an organometallic forming nanostructured films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electrical and electrochemical measurements in nanostructured films of polythiophene derivatives

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Supramolecular organization-electrical properties relation in nanometric organic films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Innovative low temperature plasma approach for deposition of alumina films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)