In metallic silicon, are B and P present in their elemental form or do they form covalent bonds with Si?
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What is the form of existence of B and P impurities in metallic silicon raw materials? Are they in their elemental form or do they form covalent bonds with Si? This post was last edited by LHY8771 on 2009-4-15 at 10:51
I want to know that too; I guess it’s covalent
Covalent bonds are classified based on the number of electron pairs
Covalent bonds: When the trivalent element boron is introduced into pure silicon crystals to replace the silicon atoms in the lattice, boron has 3 valence electrons; when it bonds with the 4 surrounding silicon atoms, it lacks one electron. This resulting empty space is called a hole, and this gives rise to P-type material； A phosphorus atom is incorporated; its atomic nucleus has a charge of +5, and it has 5 valence electrons, giving it a charge of -5. Due to the structure of silicon crystals, it can form covalent bonds only with 4 surrounding silicon atoms, which results in one extra electron being present – this is what constitutes n-type material
It should be a coexistence of elements and covalent bonds. B has a certain solubility in metallic silicon; the dissolved B forms covalent bonds, while saturated B exists in its elemental form, and B-Si alloys may even form.
Mainly borohydride, boron chloride, and things like silicon boride
That’s more or less the case; it’s possible that some atoms still remain in the gaps of the lattice without forming covalent bonds. Pure silicon is an insulator and of little use; it only becomes a semiconductor after being doped with very small amounts of elements from groups III or V such as B, P, and As – the levels of doping used in ion implantation are below 107 atoms/cm2, which means it is practically pure from a chemical perspective. This is why such high purity is required for silicon. This post was last edited by Toxic hazard on 2009-4-19 13:41]
I think it is a simple element, as that’s what enables conductivity.
Conduction relies on the directed movement of electrons
I think the content of covalent bonds is relatively higher
It depends on what kind of treatment it has undergone; personally, I think the element in its pure form is the most likely option. If it is a covalent bond substance, high-temperature reduction reactions will completely remove it.