Silane molecules

The SiH radical is tlie dominant growtli precursor for tlie fonnation of tlie a-Si H films in a low-temperature silane plasma [32]. Silane molecules are dissociated by energetic plasma electrons ... 

Fig. 3. Logarithm of room temperature electrical conductivity of a-Si H as a function of doping with diborane, B2H, and phosphine [7803-51-2] where is the ratio of the number of diborane to silane molecules Nppp /Ng pp is the ratio of phosphine to silane molecules. Both ratios refer to...

The effective absorption of radiation by a gas can be increased by the addition of a sensitizer. For example, when mercuty vapour is added to silane gas, the mercury vapour absorbs radiation to form an excited atom Hg which collides with a silane molecule to lead to partial dissociation... 

Prior to the chemical reaction of the silane with the silanol-groups on the sUica surface, the silane molecule has to make contact with the sUica surface by adsorption. Then the chemical reaction of silica with an alkoxy-silyl moiety of the coupling agent takes place in a two-step, endothermic reaction. The primary step is the reaction of alkoxy-groups with silanol-groups on the silica filler surface [4]. Two possible mechanisms are reported ... 

Optical emission is a result of electron impact excitation or dissociation, or ion impact. As an example, the SiH radical is formed by electron impact on silane, which yields an excited or superexcited silane molecule (e + SiHa SiH -t-e ). The excess energy in SiH is released into the fragments SiH SiH -I-H2 + H. The excited SiH fragments spontaneously release their excess energy by emitting a photon at a wavelength around 414 nm. the bluish color of the silane discharge. In addition, the emission lines from Si. H, and H have also been observed at 288, 656, and 602 nm, respectively. 

The ion clusters (Si2H+, Si.sH, ,...) are also present, and larger clusters (positive and neutral) can be formed through reactions with silane molecules. Negative ions have been detected [321], which are thought responsible for the powders in the discharge [322]. 

Device quality a-Si H made by HWCVD (as they termed it) was first reported by Mahan et al. [19, 527], They obtained n-Si H with hydrogen concentrations as low as 1%. Deposition rates as high as 5 nm/s [528] and 7 nm/s [529] have been achieved for n-Si H of high quality. In order to obtain device quality material it was shown by Doyle et al. [525] that the radicals that are generated at the filament (atomic Si and atomic H) must react in the gas phase to yield a precursor with high surface mobility. Hence, the mean free path of silane molecules should be smaller than the distance between filament and substrate, d(s- Too many reactions between radicals and silane molecules, however, result in worse material. In fact, optimal film properties are found for values of pdf of about 0.06 mbar-cm [530, 531]. 

SiH4 is heavier than CH4 however, both molecules have the same average kinetic energy. This is due to the fact that methane molecules have an average speed which is 1.4 times faster than that of silane molecules. 

Separation of SWNTs based on chirality and diameter with surfactants has also been evidenced by density-gradient ultracentrifugation [86]. Finally, a recent study has demonstrated the separation of semiconducting nanotubes from metallic ones by chemical interaction of the former with attached amine-terminated silane molecules assembled on a silicon wafer. In a separate experiment, metallic nanotubes were also... 

A silane-based CVD reactor suitable for performing high-temperatnre anneals in an Si- rich ambient was used for these experiments [86]. The samples were placed on a SiC-coated graphite susceptor and an RF induction coil used to heat the susceptor to temperatures on the order of 1,600-1,800°C. Silane and argon were the two process gases used, where Ar not only serves as a dilutant gas but also as a carrier gas to transport silane molecules to the crystal surface. All the implant annealing experiments were performed at atmospheric pressure. 

The relative rates of the consecutive hydrolysis reactions and the rate of condensation to form siloxane bonds depend on the structure of the silane molecule. Data such as those presented here provide the knowledge necessary to permit one to tailor the composition of species of alkoxysilane compounds in solution to obtain the desired rate and degree of hydrolysis of alkoxy groups, and the extent of siloxane bond formation. This is accomplished by the use of several easily observed bands in the mid-infrared spectrum. 

Figure 7. Simple model for predicting the ">0 " 0 ratio in observed secondary ions as a function of bonding configuration, (a) Condensation allows for a range of abundances depending on the number of bonds between the silane molecule and the surface. Electron donation (b). and protonation (c). both predict that no mixing of O O should be observed.

All ions can be identified as arising from the monomeric silane molecules. There is no evidence for peaks due to contaminants originally present at the substrate surface or in the silane solution. Further, there are no ions which contain more than three carbon atoms. 

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