Silicon reactions

The hydrogen reduction of the halides of nonmetallic elements, such as silicon (Reaction 8) and boron, is an essential process in the production of semiconductors and high-strength fibers. 

An older process to form silicides is siliconizing which is a relatively simple CVD process used to provide oxidation and chemical resistance to refractory metals. The siliconizing reaction uses the substrate itself, (such as Mo or Ti), as the metal source. Silicon diffuses readily in... 

T. Shibata, A. Wakita, T.W. Sigmon, and James F. Gibbons, Metal-Silicon Reactions and Silicide... 

Pseudohalides of silicon, reactions of pseudohalides and halides. J. Amer. 

In all three complexes the Si-metal bond is short (Si—Fe = 219, Si—Ni = 221, Si—Cr = 228 pm). These distances are about 10 pm less than for typical Si-metal single bonds, consistent with partial back-bonding from the metal d-orbitals to the p-orbital on silicon. Reactions of 59 to form silylene-metal complexes appear to be general, and many more examples are likely to be prepared in the future, for this and other stable silylenes. 

Recently, RBS has been used to study the metal-silicon reactions induced by both a CW laser and an electron beam (53). Uniform, large area, single phase silicides were formed by adjusting the beam power level to induce a solid state reaction. Under certain conditions metastable mixed-phase systems were also obtained. RBS could non-destructively determine the stoichiometry of the phases formed without additional standards. AES and SIMS have also been used in the study of metal silicides. These applications and other points of interest in the fabrication, characterization and application of metal-semiconductor Schottky barrier junctions have been reviewed recently by Sharma and Gupta (54). 

The first and second pair of tubes were connected to a U-shaped reactor by the silicon reaction zone. In the center of the tubes, silicon slabs served as a recuperation zone for the fluids entering and leaving the system. Their impressive efficiency was demonstrated by CFD simulations revealing the highest heat transfer resistance in the fluid itself and thus temperature profiles across the width of the ducts (see Figure 2.39). 

Therefore, even under close temperature and pressure conditions, the sequence of occurrence of silicide layers in metal-silicon reaction couples may be different. Indeed, A. Noya et al 255 found that Ta5Si3 is the first... 

P. Gas. Silicide thin films formed by metal/silicon reaction Role of diffusion // Mater.Sci. Forum.- 1994.- V.155-156 - P.39-54. 

W. P. Weber, Silicon Reactions for Organic Synthesis, Springer, Berlin, 1983. 

Steric and inductive effects determine the rate of formation of the pentacovalent silicon reaction complex. In alkaline hydrolysis, replacement of a hydrogen by alkyl groups, which have lower electronegativity and greater steric requirements, leads to slower hydrolysis rates. Replacement of alkyl groups with bulkier alkyl substituents has the same effect. Reaction rates decrease according to ... 

With chlorine, oxygen, ozone, or silicon, reaction is known to take jilace. The liberation of iodine from an acidified solution of potassium iodide can probably be represented (assuming orthochromic acid to exist in solution) by the equation ... 

Deposition of metals on a silicon surface can be either a conduction band process or a valence band process depending on the redox potential of the metal and solution composition. Deposition of Au on p-Si in alkaline solution occurs only under illumination indicating that it is a conduction band process due to the unfavorable position of the redox couple for hole injection. " On the other hand, deposition of platinum on p-Si can occur in the dark by hole injection into the valence band. For Cu, although the deposition proceeds via the conduction band as shown in Fig. 6.9, it can also proceed via the valence band because a large anodic current of n-Si occurs in the dark in copper-containing HF solution as shown in Fig. 6.10. The reduction of copper under this condition is via hole injection. The holes are consumed by silicon dissolution and the silicon reaction intermediates then inject electrons into the conduction band, resulting in the anodic current on n-Si in the dark. 

Br2 reacts chemically with siiicon resulting in the etching of siiicon (etch rate ofp-Si is large and is independent of the cathodic potentiai). On the other hand, on -Si at cathodic potentials the reduction of Bf2 can proceed more favorably by capturing tbe electrons from the conduction band than by injecting holes into the valence band. Thus, the etch rate ofn-Si at cathodic potentials is aimost zero due to the lack of holes to initiate the dissolution process. The anodic current on n-Si in the presence of Br2 in the dark is due to electron injection from the silicon reaction intermediates. 

Northrup, M.A., B. Benett, D. Hadley, P. Landre, S. Lehew, J. Richards, and P. Stratton. A miniature analytical instrument for nucleic acids based on micromachined silicon reaction chambers. Anal Chem. 1998, 70(5), 918-922... 

Reaction of SiH3 with C02 is rapid (reaction efficiency 0.60). Ab initio calculations fail to reveal a low-energy pathway for direct attack on oxygen (with subsequent loss of CO) but do suggest that rearrangement from an initial complex can occur via oxygen addition to silicon (reaction 133). 

Silicon reactions are central to rock weathering and soil development. Silicon is the soil component lost in greatest amount from rock minerals during weathering, and the transformations of silica into secondary minerals are the major reactions of soil development. The sand fraction of soils is usually >90% quartz (SiC>2), the most prevalent form of Si in soils. Highly weathered soils may contain as little as 20% Si (Table 2.1a). A1 and Fe ore deposits are essentially highly weathered soils from which most of the Si has been lost. 

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