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Films Leads (film + lead)

Distribution by Scientific Domains

Physics and Astronomy	42%
Polymers and Materials Science	28%

Selected Abstracts

First InGaN/GaN thin film LED using SiCOI engineered substrate

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
J. Dorsaz
Abstract InGaN / GaN multiple quantum well (MQW) light emitting diodes (LEDs) were deposited by metal-organic chemical vapor deposition (MOCVD) onto SiCOI engineered substrates. SiCOI substrates are composed of SiC thin film transferred on a silicon substrate through silicon oxide layer by the Smart CutÔ technology. LEDs structures grown on SiCOI were characterized, then transferred onto Si substrates via a metallic bonding process and SiCOI substrates were removed. Three different metallic stacks were used for metallic bonding, including mirror and barrier diffusion. Vertical thin film LED obtained were characterized and showed a 2 to 3 times increase of external quantum efficiency. These results demonstrate the potential of SiCOI engineered substrates as an alternative to laser lift off for thin film LED fabrication. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The effect of low pressure chemical vapor deposition of silicon nitride on the electronic interface properties of oxidized silicon wafers

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2007
Hao Jin
Abstract The effect of LPCVD Si3N4 film deposition on oxidized Si wafers, to form Si3N4/SiO2/Si stacks, is studied using capacitance,voltage and carrier lifetime measurements. The deposition of a nitride film leads to an increase in the density of defects at the Si,SiO2 interface, with the increase being greater the thinner the oxide. However, even the presence of a very thin intermediate oxide results in a dramatic improvement in interface properties compared to the direct deposition of the Si3N4 film on Si. The interface degradation occurs in the initial stages of nitride film deposition and appears to be largely the result of increased interfacial stress. Subsequent thermal treatments do not result in significant further degradation of the Si,SiO2 interface (except for a loss of hydrogen), again in contrast to the case where the nitride films is deposited onto Si. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Transport Processes at ,-Quartz,Water Interfaces: Insights from First-Principles Molecular Dynamics Simulations

CHEMPHYSCHEM, Issue 7 2008
Waheed A. Adeagbo Dr.
Abstract Car,Parrinello molecular dynamics (CP,MD) simulations are performed at high temperature and pressure to investigate chemical interactions and transport processes at the ,-quartz,water interface. The model system initially consists of a periodically repeated quartz slab with O-terminated and Si-terminated (1000) surfaces sandwiching a film of liquid water. At a temperature of 1000 K and a pressure of 0.3 GPa, dissociation of H2O molecules into H+ and OH, is observed at the Si-terminated surface. The OH, fragments immediately bind chemically to the Si-terminated surface while Grotthus-type proton diffusion through the water film leads to protonation of the O-terminated surface. Eventually, both surfaces are fully hydroxylated and no further chemical reactions are observed. Due to the confinement between the two hydroxylated quartz surfaces, water diffusion is reduced by about one third in comparison to bulk water. Diffusion properties of dissolved SiO2 present as Si(OH)4 in the water film are also studied. We do not observe strong interactions between the hydroxylated quartz surfaces and the Si(OH)4 molecule as would have been indicated by a substantial lowering of the Si(OH)4 diffusion coefficient along the surface. No spontaneous dissolution of quartz is observed. To study the mechanism of dissolution, constrained CP,MD simulations are done. The associated free energy profile is calculated by thermodynamic integration along the reaction coordinate. Dissolution is a stepwise process in which two SiO bonds are successively broken. Each bond breaking between a silicon atom at the surface and an oxygen atom belonging to the quartz lattice is accompanied by the formation of a new SiO bond between the silicon atom and a water molecule. The latter loses a proton in the process which eventually leads to protonation of the oxygen atom in the cleaved quartz SiO bond. The final solute species is Si(OH)4. [source]

Symmetric Wrinkling Patterns: Diffusion-Controlled, Self-Organized Growth of Symmetric Wrinkling Patterns (Adv. Mater.

ADVANCED MATERIALS, Issue 13 2009
13/2009)
Irradiation of thin polystyrene films leads to the formation of a stiff skin layer, which can dynamically wrinkle under osmotic swelling of a small molecule penetrant from localized defects in the film. As shown by Christopher Stafford and co-workers on p. 1358, these wrinkled surfaces display a rich diversity of pattern symmetries that are not readily accessible by any other route. [source]

IR spectroscopy of adsorbates on ultrathin metal films

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2005
Annemarie Pucci
Abstract Metal films with thickness in the nanometer range are optically transparent. With IR transmittance spectroscopy the in-plane film conductivity with its correlation to the film-growth process can be studied without electrical contacts and, on metal-island films, adsorbate vibrations can be observed because of surface enhanced IR absorption (SEIRA). Their analysis enables insight into the adsorbate-metal bonding and therefore gives information on the available adsorption sites and the crystalline facets correlated to. As in IR reflection absorption spectra dipole,dipole interaction of molecules on different sites modifies the vibration lines according to the degree of disorder ("atomic roughness"). Depending on that roughness IR spectra of adsorbate vibrations may be further modified because of their interaction with electronic excitations of the film. So, the limited facet size on cold-condensed metal films leads to additional IR activity: Raman lines of certain centrosymmetric adsorbate molecules (C2H4) are observed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Phase behaviour of methylcellulose,poly(acrylic acid) blends and preparation of related hydrophilic films

POLYMER INTERNATIONAL, Issue 1 2003
Vitaliy V Khutoryanskiy
Abstract The phase behavior of methylcellulose-poly(acrylic acid) mixtures was studied in aqueous solution. It was shown that the complexation between the two polymers decreases considerably the cloud-point of methylcellulose. The addition of inorganic salts shifts the critical pH values toward a higher pH region. Films were prepared based on methylcellulose-poly(acrylic acid) blends and were analyzed by dynamic mechanical thermal analysis, scanning electron microscopy and thermal gravimetric analysis. The miscibility between the two polymers in the films was shown. It was found that the thermal treatment of the films leads to their cross-linking with the formation of materials swellable both in water and ethanol. © 2003 Society of Chemical Industry [source]