A scientist requested a quote for their following research project.
"We are looking for glass substrate (2 or 3") with an epi Si layer (thickness ~ 400 nm). I was just wondering if this can be customized? I thought about this more carefully, and I think it might not be doable to put (grow or deposit) an epi silicon layer on top of glass substrate, due to the lattice mismatch and maybe other factors?
After more discussion with my colleague, it seems that we just need to put down a layer of amorphous Si instead of epi Si, due to its lower optical loss.
The other thing I'd like to take the chance to check with you for another project: we are also considering to have a layer of single crystalline, undoped epitaxial GaAs layer (thickness= 360 nm) on fused silica substrate (3" or 4"), and I was just wondering if this is something that can be provided by university wafers, or we just need to ask MBE/MOCVD grower to do the epilayer growth on GaAs substrate, and then do the wafer bonding on our own?"
UniversityWafer, Inc. responded:
"Let's try. Send us all your specs."
Reference #270980 for the result.
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The silicon lattice has a diamond-like structure, in which every Si atom has four nearby neighbors connected through covalent bonds, creating tetrahedrons, which are space-periodic, as seen in the diagram. Each carbon atom is bound by a covalent bond sharing the electronic doublet with the four neighbouring carbon atoms, with the result of creating a lattice stretching out in each direction through an enormous number of elementary cells, creating a crystal with a covalent lattice. In this orientation, each silicon atom has four neighbouring silicon atoms that it is bound to.
Lattice Parameter of Silicon
|Value||543.102 0504 x 10-12 m|
|Standard uncertainty||0.000 0089 x 10-12 m|
|Relative standard uncertainty||1.6 x 10-8|
|Concise form||543.102 0504(89) x 10-12 m|
Silicon shares the bonding versatility of carbon, thanks to the presence of its four valence electrons, but is otherwise a relatively inert element. It is a Group 14 element, within the same periodic group as carbon, but it acts differently from all its Group-mates in chemistry. Silicon has no thermodynamically stable allotropes at standard pressure, but a few other crystal structures are known to exist at higher pressures.
Covalent bonds can be either polar or nonpolar, depending on the electronegativity of the bonded atoms. Electronegativity is a measure of an atom's ability to attract electrons towards itself. If the electronegativities of the bonded atoms are different, the bond is said to be polar. If the electronegativities are the same, the bond is said to be nonpolar.
Silicon is a member of Group 14 of the periodic table. It has an atomic number of 14 and a melting point of 1414 degC. It has a high conductivity which makes it great for silicon-based semiconductors.
A silicon-oxygen bond (Si-O bond) is the chemical bond between the silicon and oxygen atoms, which is found in many inorganic and organic compounds. In a silicon crystal, which forms the basis for the electronics industry, each silicon atom forms covalent bonds with four other silicon atoms, sharing one of its electrons (and receiving in return a shared electron) from each of the four neighbors. The forming ionic bonds matches the different electronegativity of the participating atoms, such that the high-electronegativity atoms are powerful enough to draw in a valence electron of a lower-electronegativity atom.
To better understand the covalent synergy between Si and graphene substrates, the projected density of Si atom states over G and SG was calculated based on electron structure and bonding. The results showed Si has positive charge after Si adsorption over G and SG, indicating there is an electron flux from Si atoms on graphene substrates upon Si adsorption. The electron flow is more significant for Si adsorption on SG compared with G, as the Si deposited on SG has more positive charge compared to G. Table 1 also shows that C-atoms bound with the Si atoms on SG-Si, for example, C 7 and C 8 on SG-Si (SG-Si(A), C 2 and C 3 on SG-Si(B), are of higher negative charges compared with G-Si(C 2 and C 3 on G.