High Purity Silane (SiH4) Specialty Gases
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| Purity , % | 99.9999 |
| Oxygen + Argon | ≤0.06 ppmv |
| Nitrogen | ≤0.5 ppmv |
| Carbon Dioxide | ≤0.05 ppmv |
| Hydrogen | ≤20.0 ppmv |
| Carbon Monoxide | ≤0.08 ppmv |
| Water | ≤0.5 ppmv |
| Methane | ≤0.04 ppmv |
| Helium | ≤1.0ppmv |
| THC(Sum of C2-C4) | ≤0.1 ppmv |
| Total Chlorosilanes | ≤0.1 ppmv |
| Disilane | ≤0.5 ppmv |
| Disiloxane | ≤0.05 ppmv |
| Resistivity, N-type ( ohm-cm) | >2500 |
Technical Information
| Cylinder State @ 21.1°C | Gas |
| Flammable Limits In Air | 1.37-97% |
| Auto Ignition Temperature (°C ) | -50 |
| Molecular Weight (g/mol) | 32.117 |
| Specific gravity (air =1) | 1.11 |
| Critical Temperature ( °C ) | 3.45 |
| Critical Pressure ( psig ) | 687.8 |
Description
Silane (Silicane) is an inorganic compound with chemical formula SiH4. It is a colorless, pyrophoric, toxic gas with a sharp, repulsive, pungent smell, somewhat similar to that of acetic acid.Silane is of practical interest as a precursor to elemental silicon. Silane with alkyl groups are effective water repellents for mineral surfaces such as concrete and masonry. Silanes with both organic and inorganic attachments are used as coupling agents. They are commonly used to apply coatings to surfaces or as an adhesion promoter.
Silane is the silicon analogue of methane. All four Si−H bonds are equal and their length is 147.98 pm.Because of the greater electronegativity of hydrogen in comparison to silicon, this Si–H bond polarity is the opposite of that in the C–H bonds of methane. One consequence of this reversed polarity is the greater tendency of silane to form complexes with transition metals. A second consequence is that silane is pyrophoric — it undergoes spontaneous combustion in air, without the need for external ignition.However, the difficulties in explaining the available (often contradictory) combustion data are ascribed to the fact that silane itself is stable and that the natural formation of larger silanes during production, as well as the sensitivity of combustion to impurities such as moisture and to the catalytic effects of container surfaces causes its pyrophoricity.Above 420 °C, silane decomposes into silicon and hydrogen; it can therefore be used in the chemical vapor deposition of silicon.The Si–H bond strength is around 384 kJ/mol, which is about 20% weaker than the H–H bond in H2. Consequently, compounds containing Si–H bonds are much more reactive than is H2. The strength of the Si–H bond is modestly affected by other substituents: the Si–H bond strengths are: SiHF3 419 kJ/mol, SiHCl3 382 kJ/mol, and SiHMe3 398 kJ/mol.
Applications
Mainly used for semiconductors , TFT-LCD, Solar cells , Energy-saving Green Glass and applications in vapor deposition thin film precess .
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