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H Films (h + film)

Distribution by Scientific Domains
Physics and Astronomy72%
Polymers and Materials Science27%

Selected Abstracts

Superficial modification in recycled PET by plasma etching for food packaging

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010
S. A. Cruz
Abstract An oxygen plasma treatment has been used to improve the adhesion of amorphous hydrogenated carbon (a-C:H) films onto surfaces of recycled poly(ethylene terephthalate) (PET). Modifications produced by the oxygen plasma on the PET surface in chemical bonds and morphology were investigated by X-ray photoelectron spectroscopy and atomic force microscopy, respectively. Contact angle measurements were used to study the changes in the surface wettability. Adhesion of the a-C:H film onto the PET surface was investigated by the tape test method. It was observed that the improvement in film adhesion is in good correlation with the increase in surface roughness, due to plasma etching, and with the appearance of oxygen-related functional groups at the surface. The results of this study indicate that a-C:H-coated recycled PET can be used in food packaging. The a-C:H film could be used as a functional barrier to reduce or prevent migration of contaminants from the polymer to the package content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Lifetime distribution of photoluminescence and radiative recombination rate of electron-hole pairs in a-Si:H

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010
Chisato Ogihara
Abstract Temperature variations of radiative recombination rates of electron-hole pairs responsible for photoluminescence in a-Si:H films have been analysed from the intensity, I, and the characteristic value of the lifetime, ,, obtained from frequency resolved spectroscopy. In a defective a-Si:H film, the radiative recombinationrate increases with increasing temperature because of thermal excitation of the electrons and holes from the tail states to more ex-tended tail states. In the case of a high-quality a-Si:H film, the temperature variation of I,,1 is explained by contributions from regions in the vicinity of the defects and the regions not affected by the defects (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Optical bandgap and quantum well model in hydrogenated amorphous silicon carbon alloy films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003
D.K. BasaArticle first published online: 14 JAN 200
Abstract Hydrogenated amorphous silicon carbon alloy (a-SiC : H) films of various composition were prepared by the rf glow discharge decomposition of acetylene and silane as well as ethylene and silane and were also annealed for various annealing temperatures. Careful and detailed IR absorption and the optical bandgap (Eopt) measurements were undertaken for a-SiC : H films of different composition (x) and annealing temperatures (Ta). Interesting variation of Eopt with x and Ta have been observed. Our study demonstrates, for the first time, that the models involving alloying or/and ordering break down and the proposed quantum well model based on heterogeneity is found to be the only model capable of explaining the observed variation of Eopt. This, consequently, may have considerable implications. [source]

A new method used to control the structure of high rate microcrystalline silicon thin films

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010
X. D. Zhang
Abstract We report a systematic study of plasma heating effect on microcrystalline silicon (,c-Si:H) deposition. Normally, substrate surface temperature increases with time during a high rate deposition of ,c-Si:H thin film, especially under a high power and high pressure condition. We deposited ,c-Si:H films using a very high frequency discharge under the high pressure and high power condition at a fixed heater temperature or a profiled heater temperature. Raman spectra with different wavelength excitations showed that a proper heater temperature profiling during ,c-Si:H deposition is an effective method to modify the structure of ,c-Si:H films, which can control the structure evolution to form a uniform crystallinity along the growth direction and reduce the amorphous incubation layer thickness (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Lifetime distribution of photoluminescence and radiative recombination rate of electron-hole pairs in a-Si:H

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010
Chisato Ogihara
Abstract Temperature variations of radiative recombination rates of electron-hole pairs responsible for photoluminescence in a-Si:H films have been analysed from the intensity, I, and the characteristic value of the lifetime, ,, obtained from frequency resolved spectroscopy. In a defective a-Si:H film, the radiative recombinationrate increases with increasing temperature because of thermal excitation of the electrons and holes from the tail states to more ex-tended tail states. In the case of a high-quality a-Si:H film, the temperature variation of I,,1 is explained by contributions from regions in the vicinity of the defects and the regions not affected by the defects (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Structural and defect changes of hydrogenated SiGe films due to annealing up to 600°C

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010
Petr Sládek
Abstract In order to better understand the effects of the hydrogen incorporation on the defects and the disorder in the undoped nano/microcrystalline SiGe:H, we performed a comparative study on samples deposited under different plasma conditions. With variation of the pressure, we were able to change the structure of SiGe:H films. We have used the combination of the infrared spectroscopy, CPM, PDS and thermal desorption measurements to study the thermal dependence of defect density, disorder, as well as hydrogen concentration. The film mechanical properties were tested by depth sensing indentation technique. The results showing a different hydrogen bonding with the change of deposition conditions are interpreted as a whole by terms of the specific local hydrogen bonding environment, related to different growth mechanism. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Microcrystalline silicon n-i-p solar cells prepared with microcrystalline silicon oxide (,c-SiOx:H) n-layer

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010
Vladimir Smirnov
Abstract N-type hydrogenated microcrystalline silicon oxide (,c-SiOx:H) layers were used as window layers in n-side illuminated microcrystalline silicon n,i,p solar cells. Optical, electrical and structural properties of ,c-SiOx:H films were investigated by Photothermal Deflection Spectroscopy, conductivity and Raman scattering measurements. ,c-SiOx:H layers were prepared over a range of carbon dioxide (CO2) flow and film thickness, and the effects on the solar cell performance were investigated. By optimising the ,c-SiOx:H window layer properties, an improved short-circuit current density of 23.4 mA/cm2 is achieved, leading to an efficiency of 8.0% for 1,m thick absorber layer and Ag back contact. The correlation between cell performance and ,c-SiOx:H layer properties is discussed. The results are compared to the performance of solar cells prepared with alternative optimised window layers. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Temperature variation of radiative recombination rate of electron-hole pairs responsible for defect photoluminescence in a-Si:H

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S1 2009
C. Ogihara
Abstract Lifetime distribution and characteristic lifetime of the defect photoluminescence (PL) in a-Si:H have been obtained by means of frequency resolved spectroscopy at various temperatures in the range of 10-200 K. Temperature variation of the radiative recombination rate has been obtained from the intensities and the characteristic lifetimes. The results obtained for the a-Si:H films as grown and after prolonged illumination have been compared. Thermal quenching of the defect PL becomes more significant after illumination. However the decrease of lifetime with raising temperature becomes less significant after illumination. Increase of the radiative recombination rate with increasing temperature, which is significantly observed above 100 K, becomes less significant after the illumination, indicating that the illumination causes the increase of the density of strongly localised tail states. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Annealing effects on crystallized Al-doped a-Ge:H thin films

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2005
F. Fajardo
Abstract Annealing effects on crystallized aluminum doped hydrogenated amorphous germanium (a-Ge:H) thin films have been studied by Raman spectroscopy, as a function of Al concentration ([Al/Ge] ,10,6,10,2 range). All the as-deposited Al-doped a-Ge:H samples with [Al/Ge] < 1.3 at% possess a Raman spectra that includes the signal given by the amorphous phase and a shoulder at around 300 cm,1, that evolves with increasing impurity content, to a well defined peak, corresponding to the contribution of the TO vibration of crystallized Ge. The scattering intensity of samples having 1.4 , [Al/Ge] , ,1.8 at% is dominated by the c-Ge TO vibration. Aluminum concentrations above [Al/Ge] > ,1.8 at% do not indicate crystallization of a-Ge:H films to levels detectable by Raman spectroscopy. An abrupt crystallization was observed to occur after annealing at Ta , 500 °C for all the range of the Al-doped samples, including the intrinsic one. These results and the comparison with data of the local order and coordination of Ga atoms into the a-Ge:H network, suggest that Al-induced crystallization originates from fourfold coordinated aluminum atoms that act as crystallization seeds. These seeds have only small influence on the abrupt crystallization of Al doped a-Ge:H films due to annealing treatments. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

New Antimicrobial Materials Based on Polymers With Nanostructured Surface Modified by Organic Fullerene[60] Derivatives

PLASMA PROCESSES AND POLYMERS, Issue S1 2009
Vera M. Ellinson
Abstract In the present work, the surface of natural and artificial polymers was modified by plasma treatment using reactive gases mixture, ion-beam-induced deposition of , -C:H films and organic C60 derivatives deposition. The study of prepared biomaterials with nanostructured surface was carried out by means of atomic force microscopy, X-ray photoelectron spectroscopy, contact angle measurement and surface energy calculation. The investigation of antimicrobial activity of the materials was carried out by application method in relation to Gram-positive (Staphylococcus aureus ATCC 29213) and Gram-negative (Escherichia coli ATCC 54383 and Pseudomonas aeruginosa ATCC 27853) microorganisms and fungi (Candida albicans). [source]

Structural and Mechanical Study of Nanocomposite Ti,Zr,C,H Coatings Prepared by Reactive Magnetron Sputtering

PLASMA PROCESSES AND POLYMERS, Issue S1 2009
Diego Martínez-Martínez
Abstract Nanocomposite structures formed by small crystallites embedded in a lubricant matrix present moderate,high hardness, good toughness, and low values of friction coefficient and wear rate, and they are a promising alternative for protective tasks. In this study, we have prepared Ti,Zr,C,H films as potential candidates as protective layers for biocompatible applications. The constituting elements were selected due to their proven good biocompatibility at the macroscale. The films were prepared by reactive dc magnetron sputtering, and further characterized by X-ray photoelectron spectroscopy and X-ray diffraction. Mechanical and tribological properties were also evaluated. [source]