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Detailed syntheses are reported for the previously reported homoleptic 1-norbornyl complexes [M([norb).sub.4]] {M = Ti (1), Zr (3), Hf (4), and Mn (5)}. These compounds were characterized by combustion elemental analysis, NMR spectroscopy single crystal X-ray diffraction (for 1 and 3), and SQUID magnetometry (for 5). The reaction by-product [{([norb).sub.3][Ti}.sub.2]([micro]-0)] (2) was also spectroscopically and structurally characterized. To assess the potential viability of 1 and 3-5 as precursors for thin film deposition by CVD or ALD, their volatility and thermal stability were evaluated by sublimation, thermogravimetric analysis, and in the case of 4, bulk thermolysis. Key words: homoleptic 1-norbornyl complexes, titanium, zirconium, hafnium, manganese Nous presentons des protocoles detailles pour la synthese des complexes homoleptiques de 1 norbornyle publies anterieurement [M([norb).sub.4]] {M = Ti (1), Zr (3), Hf (4) et Mn (5)}. Nous avons caracterise ces composes par analyse elementaire par combustion, spectroscopie de resonance magnetique nucleaire (RMN), diffraction des rayons X sur monocristal (dans le cas des complexes 1 et 3) et magnetometrie a interferometre quantique supraconducteur (SQUID pour Superconducting Quantum Interference Device) (dans le cas du complexe 5). Le sous-produit de la reaction [{([norb).sub.3][Ti}.sub.2]([micro]-0)] (2) a egalement ete caracterise par analyse spectroscopique et structurale. Ann d'evaluer si les complexes 1 et 3 a 5 pourraient etre des precurseurs viables pour le depot chimique en phase vapeur (CVD pour Chemical Vapor Deposition) de couches minces, ou le depot de couches atomiques (ALD pour Atomic Layer Deposition), nous avons mesure leur volatilite et leur stabilite thermique par sublimation et par analyse thermogravimetrique, et dans le cas du complexe 4, par thermolyse de l'echantillon. [Traduit par la Redaction] Mots-cles : complexes homoleptiques de 1-norbornyle, titane, zirconium, hafnium, manganese, Introduction Homoleptic alkyl complexes, with or without additional neutral Lewis base coordination, are of interest as starting materials for the synthesis of new alkyl derivatives (via alkane elimination), (1) as [...]

The elimination of [H.sub.2] from the dissociation of four methyl-substituted silane molecules, including monomethylsilane (MMS), dimethylsilane (DMS), trimethylsilane (TriMS), and tetramethylsilane (TMS), on a heated tungsten or tantalum filament surface has been studied using laser ionization mass spectrometry. Two complementary ionization methods, i.e., single photon ionization (SPI) using a vacuum ultraviolet wavelength at 118 nm (10.5 eV) and a dual ionization source incorporating both 10.5 eV SPI and laser-induced electron ionization, were employed to detect the production of [H.sub.2]. Examination of the intensity of the [H.sub.2.sup.+] peak from the four molecules has shown that it increases with temperature until reaching a plateau at around 2000- 2100°C on both tungsten and tantalum filaments. These methyl-substituted silanes are dissociatively adsorbed on tungsten and tantalum surfaces by Si-H bond cleavage, and as the temperature is raised, by C-H bond rupture. Experiments with the isotopomers of MMS, DMS, and TriMS have shown that the formation of [H.sub.2] follows the Langmuir-Hinshelwood mechanism where two adsorbed hydrogen atoms on metal surfaces recombine to produce [H.sub.2]. The determined activation energy ([E.sub.a]) for [H.sub.2] formation from MMS, DMS, and TriMS, in the range of 58.2-93.4 kJ [mol.sup.-1], has been found to increase with the number of methyl substitutions in the precursor molecule. Comparison of these [E.sub.a] values with the reported values of 51.1-78.8 kJ [mol.sup.-1] for the methyl radical formation from the same three precursor molecules has led to the conclusion that the initial Si-H bond cleavage in the dissociative adsorption of MMS, DMS, and TriMS is the rate-limiting step for the formation of both [H.sub.2] molecules and - C[H.sub.3] radicals. Key words: [H.sub.2] elimination, methyl-substituted silanes, tungsten and tantalum surfaces, laser ionization mass spectrometry, chemical vapor deposition. Nous avons etudie, au moyen de la spectrometrie de masse par ionisation laser, l'elimination d'[H.sub.2] resultant de la dissociation de quatre molecules a substituants methyliques, le monomethylsilane (MMS), le dimethylsilane (DMS), le trimethylsilane (TriMS) et le tetramethylsilane (TMS), chauffees sur une surface de filament de tungstene ou de tantale. Nous avons employe deux methodes d'ionisation complementaires, soit l'ionisation monophotonique a l'aide de rayons ultraviolets sous vide a la longueur d'onde de 118 nm (10,5 eV) et l'ionisation a deux sources integrant a la fois l'ionisation monophotonique a 10,5 eV et l'ionisation electronique induite par laser, en vue de detecter la production de [H.sub.2]. En examinant l'intensite des pics d'[H.sub.2.sup.+] des quatre molecules, nous avons observe que celle-ci augmente en fonction de la temperature, jusqu';! ce que cette derniere atteigne un plateau se situant autour de 2000-2100°C, tant pour les filaments de tungstene que pour ceux de tantale. Ces silanes a substituants methyliques sont adsorbes sur les surfaces de tungstene et de tantale par dissociation de la liaison Si-H et, a mesure que la temperature augmente, par rupture de la liaison C-H. Des experiences menees avec les isotopomeres de MMS, DMS et TriMS ont indique que la formation d'[H.sub.2] se produit selon le mecanisme de Langmuir-Hinshelwood, oU deux atomes d'hydrogene adsorbes sur la surface des metaux se recombinent pour former d'[H.sub.2]. Nous avons determine que l'energie d'activation ([E.sub.a]) pour la formation d'[H.sub.2] a partir du MMS, du DMS et du TriMS se situait entre 58,2 et 93,4 kJ [mol.sup.-1] et avons observe qu'elle augmentait avec le nombre de substituants methyliques sur la molecule de depart. En comparant ces valeurs d'[E.sub.a] avec les valeurs publiees (51,1-78,8 kJ [mol.sup.-1]) pour la formation du radical methyle a partir des memes molecules de depart, nous sommes arrives a la conclusion que le clivage initial de la liaison Si-H dans le processus d'adsorption dissociative du MMS, du DMS et du TriMS constitue l'etape limitante de la formation des molecules d'[H.sub.2] et des radicaux -C[H.sub.3]. [Traduit par la Redaction] Mots-cles : elimination d'hydrogene moleculaire, silanes a substituants methyliques, surfaces de tungstene et de tantale, spectrometrie de masse par ionisation laser, depot chimique en phase vapeur., Introduction Hydrogen, especially atomic hydrogen, is perhaps the most critical determinant for the purity and growth rate of diamond thin films by chemical vapor deposition (CVD) methods. (1) Several groups [...]

For centuries, practitioners of origami ('ori', fold; 'kami', paper) and kirigami ('kiru', cut) have fashioned sheets of paper into beautiful and complex three-dimensional structures. Both techniques are scalable, and scientists and engineers are adapting them to different two-dimensional starting materials to create structures from the macro- to the microscale (1, 2). Here we show that graphene (3-6) is well suited for kirigami, allowing us to build robust microscale structures with tunable mechanical properties. The material parameter crucial for kirigami is the Foppl-von Karman number (7, 8) γ: an indication of the ratio between in-plane stiffness and out-of-plane bending stiffness, with high numbers corresponding to membranes that more easily bend and crumple than they stretch and shear. To determine γ, we measure the bending stiffness of graphene monolayers that are 10-100 micrometres in size and obtain a value that is thousands of times higher than the predicted atomic-scale bending stiffness. Interferometric imaging attributes this finding to ripples in the membrane (9-13) that stiffen the graphene sheets considerably, to the extent that γ is comparable to that of a standard piece of paper. We may therefore apply ideas from kirigami to graphene sheets to build mechanical metamaterials such as stretchable electrodes, springs, and hinges. These results establish graphene kirigami as a simple yet powerful and customizable approach for fashioning one-atom-thick graphene sheets into resilient and movable parts with microscale dimensions., Devices such as those shown in Fig. 1a, c, d are made from polycrystalline monolayer graphene that is grown on copper by chemical vapour deposition (14), and then transferred to [...]

The present paper discusses the ability to separate chemical species using high-aspect-ratio, silicon oxide-enclosed pillar arrays. These miniaturized chromatographic systems require smaller sample volumes, experience less flow resistance, and generate superior separation efficiency over traditional packed bed liquid chromatographic columns, improvements controlled by the increased order and decreased pore size of the systems. In our distinctive fabrication sequence, plasma-enhanced chemical vapor deposition (PECVD) of silicon oxide is used to alter the surface and structural properties of the pillars for facile surface modification while improving the pillar mechanical stability and increasing surface area. The separation behavior of model compounds within our pillar systems indicated an unexpected hydrophobic-like separation mechanism. The effects of organic modifier, ionic concentration, and pressure-driven flow rate were studied. A decrease in the organic content of the mobile phase increased peak resolution while detrimentally effecting peak shape. A resolution of 4.7 (RSD = 3.7%) was obtained for nearly perfect Ganssian shaped peaks, exhibiting plate heights as low as 1.1 and 1.8 [micro]m for fluorescein and sulforhodamine B, respectively. Contact angle measurements and DART mass spectrometry analysis indicate that our employed elastomeric soft bonding technique modifies pillar properties, creating a fortuitous stationary phase. This discovery provides evidence supporting the ability to easily functionalize PECVD oxide surfaces by gas-phase reactions. 10.1021/ac1023342

A design methodology for optimizing low-temperature poly-Si (LTPS) thin-film transistors (TFTs) for digital super and subthreshold operations is presented. The optimization of LTPS TFTs results in the achievement of comparable performance as a single-crystalline silicon silicon-on-insulator (SOI).

The growth of large area tubular graphite cones (TGCs) with a single-crystal nanotube tip on Si substrates by microwave plasma-assisted chemical vapor deposition (MPCVD) by using in-situ-evaporated Fe catalysts is described. It is shown that TGCs with single crystalline nanotips are useful for scanning probes in high-temperature oxygen-containing environments.

A new magnetism-assisted chemical vapor deposition method is devised to produce and synthesize branched or iron-capsulated carbon nanotubes (CNTs). The coalescence or the division of the catalyst particles is found to being promoted by the external magnetic field, providing such CNTs.

A method to fabricate E-mode AIN/GaN HfETs is described by using Cat-CVD SiN to control the formation of a high-density 2-D electron gas (2DEG). It is found that the fromat6ion of a 2DEG in the AIN/GaN heterostructure can be controlled by the presence of the Cat-CVD SiN on the barrier layer.

In this paper, the Poisson's ratio v of low-temperature plasma-enhanced chemical vapor deposited silicon nitride (Si[N.sub.x][H.sub.y]) thin films has been determined by a modified double-membrane bulge test. This test method utilizes a square membrane and a large-aspect-ratio rectangular membrane that is fabricated alongside from the same thin film. The Poisson's ratio is determined from the ratio of the bulge deflections of the two membranes under an applied pressure. The method is suitable for determining v of either stress-free thin films or those containing low tensile residual stresses. Poisson's ratio values of 0.23 [+ or -] 0.02 and 0.25 [+ or -] 0.01 were measured for Si[N.sub.x][H.sub.y] films that were deposited at 125 [degrees]C and 205 [degrees]C, respectively. [2006-0065] Index Terms--Amorphous materials, dielectric films, plasma chemical vapor deposition (CVD), thin films.

A stand-alone germanium solar cell process is developed based on emitter diffusion using spin-on dopant (SOD), plasma enhanced chemical vapor deposition (PEVCVD) a-Si surface passivation and front contact formation and these process steps is investigated in detail to optimize the final solar cell efficiency. Phosphorous diffusion experiments in germanium show that the obtained profits are suitable for solar cell emitter formation.

The electrical and optical properties of SiONC dielectric thin films prepared by a polymer-source chemical vapor deposition (CVD) process using an organosilane precursor is investigated as a function of oxygen concentration in the films. The results have indicated that SiONC thin films deposited by polymer-source CVD process is an attractive alternative to SiON thin films obtained by other methods.

Plasma processing at atmospheric pressure (APPlasmas) has attractions for both economic and technological reasons. Potential costs-saving factors are associated with online-processing capability and increase throughput due to high deposition rates. Capital cost savings for both equipment and line space (foot print), and relative ease of integration, are further benefits in comparison to low-pressure-technology approaches. Three types of APPlasmas are considered for coating: microwave chemical vapor deposition (CVD), dc ArcJet-CVD based on a linearly extended plasma source, and dielectric barrier glow discharge plasma CVD. Spectroscopic plasma characterization has shown that high fluxes of activated species are available in the plasma downstream region and can be used for deep fragmentation of even stable molecules. After precursor injection, a range of atomic and molecular intermediates, precursor fragments, and reaction products were identified leading to a conclusion that a complete conversion of the element-organic precursors into an inorganic materials take place. Alternatively, the dc Arc Jet source is used for plasma chemical etching. All AP-plasma-enhanced chemical vapor deposition (PECVD), reactors are designed for continuous air-to-air processing on flat or slightly shaped substrates and allow deposition of nonoxide films. Reactor design is supported by fluid-dynamic modeling. Typical thin-film growth rates for PECVD are in the range of 5-100 nm/s (static) and up to 2 nm*m/s (dynamic). The rates for plasma chemical etching are typically ten times higher. Plasma activation substantially widens the range of potential applications, e.g., coating on steel, lightweight metals, preshaped glass, and plastics. Developments are underway to explore the use of the coating technologies in areas such as scratch-resistant coatings on metals, barrier layers, self-clean coatings, biocidal functional surfaces, and antireflective coatings. The coating materials range explored, so far, includes: silica, titania, carbon, silicon nitride/carbide, and metal oxides. Index Terms--Plasma chemical vapor deposition (CVD), plasma diagnostics, plasma etching.

The synchrotron x-ray diffraction and transmission electron microscopy was used to investigate the ferroelectric domain structures and microstructure of epitaxial tetragonal Pb([Zr.sub.0.35], [Ti.sub.0.65])[O.sub.3] films which were grown on SrRu[O.sub.3](100)/SrTi[O.sub.3](100) substrates by metal organic chemical vapor deposition. The findings reveal that it is possible to obtain highly a-axis oriented films by reducing the compressive strain that was caused by reducing the growth temperature and increasing the film thickness.

The electrical and structural characterization of Mg-doped Al-rich p-type [Al.sub.0.69][Ga.sub.0.31]N alloys on SiC substrate grown by metal organic chemical vapor deposition is presented. Transmission electron microscopy has shown the generation of vertical spike-like defects with increasing Mg doping and the increase in resistivity with the increase in Mg doping.

A series of films grown by hybrid physical chemical vapor deposition (HPCVD) that are neutron irradiated at different fluences up to [10.sup.20] [cm.sup.-2] is reported. The measured critical field values are extremely high and turn out to be rather independent of the experimental resistivity at least at low fluences.

A study was conducted to investigate AlGaN potential barrier heights of AlGaN/GaN heterostructures with and without SiN passivation. Catalytic chemical vapor deposition (Cat-CVD) SiN passivation lowered the AlGaN potential barrier height more significantly than plasma-enhanced CVD (PECVD) SiN passivation, suggesting that the passivation method could influence the AlGaN potential barrier height.

The multistacked Ge quantum dots (QDs) with Si spacers of different thickness are grown on (100) Si wafer by rapid thermal chemical vapor deposition and are characterized by using photoluminescence (PL) and Raman scattering. The results have shown that the optical properties are strongly related with the correlation between the QDs and the Ge-Si intermixing.

The synthesis and characterization of four novel hafnium guanidinate complexes as well as the growth and characterization of Hf[O.sub.2] thin films by metal-organic chemical vapor deposition (MOCVD) using [Hf[{[[eta].sub.2]-[([super i]PN).sub.2]CNRtMe}.sub.2][(NEtMe).sub.2] are reported. Guanidinate-based Hf complexes have the potential for atomic layer deposition (ALD) of Hf[O.sub.2] thin films because of their good thermal stability and reactivity.

The fabrication of embedded microchannels monolithically integrated with optical waveguides by plasma-enhanced chemical vapor deposition of doped silica glass is reported. Both waveguide ridges and template ridges for microchannel formation are patterned in a single photolithography step. The microchannels are formed within an overlay of borophosphosilicate glass (BPSG), which also serves as the top cladding layer of the silica wavegnides. No top sealing of the channels is required. Surface accessible fluid input ports are formed in a BPSG layer, with no additional steps, by appropriate design of template layers. By tightly controlling the refractive index of the waveguide layer and the microchannel-forming layer, fully integrated structures facilitating optical coupling between solid waveguides and liquids segments in various geometries are demonstrated. Applications in liquid-filled photonic device elements for novel nonlinear optical devices and in optical sensors and on-chip spectroscopy are outlined. OCIS codes: 130.1750, 130.3120, 230.7380.

The band lineups of Ga[As.sub.1-x][Sb.sub.x] quantum well (QW) heterostructures having different QW barriers (QWBs) grown by metal-organic chemical vapor deposition (MOCVD) are investigated and the change of band lineups of Ga[As.sub.1-x][Sb.sub.x] QW heterostructures depending on the materials used for the QWBs, such as GaAs, GaAsP and InGaP, is reported. The results are compared to the experimental room-temperature photoluminescence (PL) data.