Tetraethylorthosilicate Vapor Research Articles

Immobilization of CNT on Bamboo Charcoal by TEOS Vapor

ABSTRACTCarbon nanotubes (CNTs) are successfully immobilized on a bamboo charcoal by chemical vapor deposition of gaseous tetraethyl orthosilicate (TEOS). Electron microscopies, Raman spectroscopy and electron energy loss spectroscopy are used to characterize the sample. The CNTs found on the bamboo charcoal support were several microns long, and their diameters ranged from 50nm to 300nm. From the high resolution transmission electron microscopic analysis, we found that the CNTs were composed of ∼30 layers of graphitic carbon sheets. Amorphous droplets were also found at the tips of the CNTs. This suggested that the growth of the CNT was via a vapor-liquid-solid mechanism. The amorphous droplets contained calcium, silicon and oxygen. The calcium impurity was originated from the bamboo while the silicon impurity was supplied by the TEOS. CNTs partially filled with calcium silicate were also found. It was evident that calcium silicate had played a critical role in the formation of these CNTs.

ＰＥＣＶＤ成膜装置内での粒子汚染現象に対する操作流量の影響

The effects of gas flow rate on the contamination by dust particles in an RF plasma reactor were studied experimentally. A mixture of tetraethylorthosilicate vapor, oxygen and nitrogen were fed into the reactor to fabricate SiO2 thin film. Dust particles generated in the plasma were visualized by a laser light scattering technique. Particle size was measured by a laser particle counter, and particle deposition for the film was observed by a scanning electron microscope. The dust particles were found to be trapped in a certain region in the reactor. The amount and size of the trapped particles decreased with increasing gas flow rate. The particle contamination on the film surface also decreased with increasing gas flow rate. At a high flow rate, however, dust particles embedded into the film were observed. In addition, high gas flow rate degraded the film uniformity. It is considered from the above results that a proper selection of gas flow rate is important to decrease particulate contamination as much as possible.

Enhancement of Structural Stability of Mesoporous Silica Thin Films Prepared by Spin-Coating

A mesoporous silica film was prepared on a silicon substrate using a spin-coating process followed by a tetraethyl orthosilicate (TEOS) vapor treatment. The TEOS-treated mesostructured silica film did not contract during calcination, showing high structural stability. Thermal treatment without TEOS vapor was not effective to enhance the structural stability of mesostructured films. A flat mesoporous silica film about 250 nm thick was grown from the silicon substrate. No silica particle was deposited from TEOS vapor on the surface of the film, suggesting the penetration of TEOS vapor into the film. A periodic porous structure was observed in the FE-SEM image of the cross section of the mesostructured film. This indicates that the channels run predominantly parallel to the surface of the silicon substrate. FTIR studies suggested that the silanol groups in the film significantly decreased after the TEOS treatment. TEOS molecules penetrate into an originally deposited silicate film and react with the silanol ...

Solid softwood coated with plasma-polymer for water repellence

Cold plasmas were produced by electrical glow discharges in a gas medium at reduced pressure and at low frequency. The precursor gases used were ethylene, acetylene, butene-1, and vapor of vinyl acetate. The treatment caused the solid softwood surface to become hydrophobic; 1-butene-plasma produced the best results. Although the surface plasma treatment resulted in water repellence, permeability to water vapor remained. Using a mixture of tetraethyl orthosilicate vapor (TEOS) and oxygen (O 2) it was possible to investigate the inability of the glow discharge to coat the surface of wood orifices.

An Experimental Study on Composition Characteristics of SiO$_2$/TiO$_2$/Multicomponent Particle Generated in a Coflow Diffusion Flame

Chemical compositions of polydisperse SiO/TiOmulticomponent aggregates were measured for different heights from the burner surface and different mobility diameters of aggregates. SiO/TiOmulticomponent particles were generated in a hydrogen/oxygen coflow diffusion flame from two sets of precursors: TTIP(titanium tetraisopropoxide), TEOS(tetraethylorthosilicate). To maintain 1:1 mole ratio of TTIP:TEOS vapor, flow rate of carrier gas was fixed at 0.6lpm for TTIP, at 0.1lpm for TEOS. In-situ sampling probe was used to supply particles into DMA(differential mobility analyzer) which was calibrated with using commercial DMA(TSI, model 3071A) and classifying monodisperse multicomponent particles. Classified monodisperse particles were collected with electrophoretic collector. The distributions of composition from particles to particle were determined using EDS(energy dispersive spectrometry) coupled with TEM(transmission electron microscope). The chemical(atomic) compositions of classified monodisperse particle were obtained for different heights; z=40mm, 60mm, 80mm. The results suggested that the chemical(atomic) composition of SiOdecreased with the height from burner surface and the composition of SiOand TiOapproached to the value of 1 to 1 fat downstream. It is also found that the composition of SiOdecreases as the mobility diameter of aggregate increases.

Nano-sized particles from the CO2 laser assisted decomposition of tetraethylorthosilicate vapour

Nano-sized particles from the CO2 laser assisted decomposition of tetraethylorthosilicate vapour

Preparation of fine particles by CO 2 laser assisted decomposition of tetraethylorthosilicate vapour

Preparation of fine particles by CO 2 laser assisted decomposition of tetraethylorthosilicate vapour

Fine particles synthesis in excimer laser assisted decomposition of tetraethylorthosilicate vapour

Fine particles synthesis in excimer laser assisted decomposition of tetraethylorthosilicate vapour

Gas phase synthesis of fine silica particles by oxidation of tetraethylorthosilicate vapour

Gas phase synthesis of fine silica particles by oxidation of tetraethylorthosilicate vapour

Electron cyclotron resonance plasma source for metalorganic chemical vapor deposition of silicon oxide films

An electron cyclotron resonance (ECR) plasma source was employed for low‐temperature (50–300 °C) metalorganic plasma‐enhanced chemical vapor deposition of silicon oxide films. The plasma was excited in mixtures of oxygen and tetraethylorthosilicate vapor, and oxygen and tris(trimethylsiloxy)boron (TTMSB) vapor. The operation pressure range was 1–50 mTorr; oxygen and metalorganic vapor flow rates varied from 10 to 100 sccm. Microwave power (f=2.45 GHz, P=100–1500 W) was introduced into a 15‐cm‐diam ECR chamber via a microwave quartz introduction window. A static magnetic field in the plasma chamber was generated by two Helmholtz coils. It had intensity near the microwave window, Bvw=875–935 G in a narrow plasma mode, and Bvw=1000–1100 G in a uniform plasma mode. Silicon dioxide films were deposited onto a 10‐cm‐diam silicon wafer located at 16 cm from the source output. A line‐averaged plasma density Ne was measured with a microwave interferometer (35 MHz) at 11 cm from the source output. In the mixture o...

Structual Changes of Arsenic Silicate Glasses with Heat Treatments

Silicate glass containing arsenic as a diffusant into silicon was studied. The glass was deposited on a heated silicon substrate in the atmosphere of mixture of tetra-ethyl ortho-silicate vapor, arsenic trichloride vapor and oxygen gas between 500–700°C. The structure of the glass and its changes with heat treatments in the atmosphere of oxygen, hydrogen, nitrogen gas and in vacuum were studied by infra-red spectroscopy, electron diffraction analysis and so on. Density, mole percentage of As2O3 and refractive index were also measured. By the heat treatment in hydrogen gas, As2O3 in glass is easily reduced to As and after its treatment, As is oxidized again to As2O3 by the heat treatment in oxygen gas. During a long time heat treatment in oxygen gas, the surface of the glass is crystallized. The damage of the glass by the heat treatment in oxygen gas may be explained by the low softening point and large thermal expansion coefficient of this glass.